It was a van der Waals (vdWs) stacked configuration composed of gold (Au) film, few quintuple layer (QL) Bi2Se3 and few-layered graphene. In particular, the proposed biosensor was created by Goos-Hänchen (GH) shift rather than phase, resulting in a more sensitive biosensing response. Under the excitation of 632.8 nm, significant sensitivity enhancement performance was obtained via varying the thickness of Bi2Se3-Graphene heterostructures. The best configuration was 32 nm Au film−2-QL Bi2Se3-3-layer graphene, generating the largest GH shift, as high as −1.0202 × 104 µm. Moreover, the highest detection sensitivity was determined to be 8.5017 × 106 µm/RIU, responding to a tiny refractive index (RI) change of 0.0012 RIU . More importantly, our proposed biosensor has shown a theoretical feasibility of monitoring virus samples. For example, there was an efficient linear detection range for severe acute respiratory syndrome coronavirus 2 ) and its Spike (S) glycoprotein (0~59.74 nM), respectively. It is expected that our proposed plasmonic biosensor has a potential application in performing sensitive detection of SARS-CoV−2.This study provided a theoretical insight for designing novel plasmonic biosensors using bismuth selenide (Bi Thus, Bi2Se3 film shows an enhanced sensitivity for RI variation [Surface plasmon resonance (SPR) biosensors are a class of important optoelectronic devices widely employed in the biomedicine science field. To date, significant breakthroughs in plasmonic biosensing are focused on the following two studies: (i) novel plasmonic materials and (ii) optimization of biosensing process . For plaariation . In addiariation . It is p2X3. Here, M stands for the element Bi or Sb, and X denotes the element Te or Se. Bi2Se3 is the most common 2D topological insulator material, whose crystal lattice consists of quintuple layers (QL) orderly arranged by a Se–Bi–Se–Bi–Se unit [2Se3 has shown many unique features, such as a large bandgap of ~0.3 eV [2Se3 films exhibited the maximum photon response [2Se3 films with a thickness less than 22 nm is 50~200 cm2V−1s−1 [2Se3/Graphene heterostructures was observed as high as 5000~6000 cm2V−1s−1 [2Se3/graphene heterostructures at room temperature can be optimized to be 3400 cm2V−1s−1 [It is well-known that TIs family has several prototypical members, which can be described as M–Se unit ,17. In a ~0.3 eV , well-de ~0.3 eV , high ph ~0.3 eV ,20 and e ~0.3 eV . It is presponse . At roomm2V−1s−1 . Howeverm2V−1s−1 ,25. Morem2V−1s−1 . To the 2Se3-Graphene heterostructures to linearly detect SARS-CoV−2 and its S glycoprotein. Rather than phase-modulation, our proposed SPR biosensor was designed by GH shift, showing a higher biosensing performance. Both photon absorption and energy dissipation were optimized to be a balance state by varying thickness of Bi2Se3/Graphene heterostructures. The optimal configuration: 32 nm Au film−2-QL Bi2Se3–3-layer graphene could provide the largest GH shift up to −1.0202 × 104 µm. For a tiny RI variation of 0.0012 RIU, the highest detection sensitivity of 8.5017 × 106 µm/RIU can be achieved. Moreover, the proposed biosensor could be employed to simulate the adsorption behavior of SARS-CoV−2 and its S glycoprotein. A good linear response interval for monitoring SARS-CoV−2 was from 0 to13.44 nM. For S glycoprotein, a theoretical linear detection interval was from 0 to 59.74 nM. In all, the optimal biosensor is a potential candidate in quantitatively monitoring SARS-CoV−2 and other infectious viruses in practical clinical applications.Inspired by these observations, we theoretically proposed a novel plasmonic biosensor using vdWs Bi2Se3 interlayer and graphene overlayer, as shown in 2Se3/Graphene heterostructures having high carrier mobility, it was introduced to work as an important plasmonic layer, significantly developing the energy dissipation. Then, Bi2Se3 interlayer was vdWs stacked onto the top of plasmonic gold film. After this, few layered graphene overlayer was further stacked onto Bi2Se3 interlayer to form Bi2Se3/Graphene heterostructures. The topmost layer was a sealed cell containing work solutions. It is worth noting that the work solutions consisting of 10 mM HEPES (4-(2-hydroxyethyl)−1-piperazineethanesulfonic acid) and 120 mM NaCl (sodium chloride) was utilized to contain SARS-CoV−2 and its S glycoprotein in this simulation. To really calculate the binding interaction between SARS-CoV−2 and sensing interface of Bi2Se3/Graphene heterostructures, the work buffer consisting of 10 mM HEPES and 120 mM NaCl solutions was injected from left entrance. Once the target analytes in running buffer were bound to the sensing interface, the change in local RI would be different. Generally, the tiny variation in RI could be readout by measuring the change in intensity of reflected light, SPR angle and differential phase. In this work, p-polarized incident light having a wavelength at 632.8 nm was applied to resonate with SPPs wave in Au film/Bi2Se3/Graphene heterostructures. Unlike previous SPR biosensors created by phase modulation, our proposed biosensor was designed by measuring GH shift. It is well-known that GH shift is an interesting displacement behavior of reflected light relative to geometric reflection theory, because practical incident lights generated by lasers are not ideal monochromatic electromagnetic plane waves [The theoretically proposed SPR biosensor consists of an SF11 prism, an Au thin film, few layered Bine waves . Moreovene waves , indicatne waves ,30, whicne waves ,32. Unde2Se3 nanosheets and graphene overlayer is 1.7786 [2Se3 and monolayer graphene is 0.9725 nm [C) can be determined to be 1.3345 [2Se3/Graphene configuration was assumed to be proportional to the concentration of S glycoprotein, which can be calculated by Equation (2):An is the RI due to the adsorption interaction of S glycoprotein and Cn is the RI of running buffer. Ac is the concentration of S glycoprotein solution. In addition, the parameter (dn⁄dc) denotes the increment of refractive index and the value of dn⁄dc is usually ~0.186 cm3•g−1 for studying protein-protein binding interactions [Ac) of S glycoproteins can be calculated according to the binding parameter (dn⁄dc).Both photon absorption and energy dissipation in our proposed configuration highly depend on optical dielectric constant of each layer. Prior to biosensing simulation, the dielectric constant of each layer needs to be determined. Under the excitation light of 632.8 nm, the refractive indices of SF11 prism layer, Au film layer, Bis 1.7786 . 0.1838 s 1.7786  and 3.00.9725 nm  and 0.34.9725 nm , respectractions . For a f1 = 0, and the relationship between the last boundary ZN−1 and first boundary Z1 could be given as:In addition to SPR reflectivity, change in incident angle and differential phase, change in GH shift generated by plasmonic enhancement in our proposed SPR configuration was systematically simulated using transfer matrix method (TMM) and Fresnel equations in a N-layer stacked model. Theoretically, each layer was supposed to parallel in Z-direction and each layer was considered to be isotropic and non-magnetic. It was assumed that the number of antibody sites on graphene layers was much more than that of S protein. The adsorption sites on graphene overlayer were S protein antibody, which can be employed for specifically capture SARS-CoV−2 using antibody-antigen interactions. Generally, the electromagnetic fields at the first boundary along the tangential direction was supposed to be Zk could be described as:kβ and kq can be determined using the following two Equations (6) and (7):kd stands for the thickness of the k-th layer. Additionally, kε represents the dielectric constant of the k-th layer. In Equation (7), 1θ and 1n are the incident angle and RI of the first stacking layer, respectively.Here, M is a transfer matrix, which can be obtained by the following equation for p-polarized light:kq was described by Equation (8):For s-polarized light, these relationships described above are still practicable. However, pR) in our proposed configuration can be obtained using Equation (9):Prior to calculating GH shift, the reflectivity : sφ stands for the phase of s-polarized light.Therefore, the differential phase ΔGHS) can be calculated by Equation (12):According to the stationary phase theory, the GH shift (dGHS) between p- and s-polarized light can be calculated as follows:For p-polarized light, the GH shifts produced by metal films are negative. However, the GH shift excited by s-polarized light in metal films are usually positive . MoreoveφS) and GH shift sensitivity (SGHS), were introduced. Both of them can be determined as follows: bion denotes a tiny variation of RI in sensing interface of Bi2Se3/graphene heterostructures due to strong adsorption binding interaction.To evaluate the biosensing performance of our proposed configuration, two parameters, such as phase sensitivity , as shown in 2Se3/graphene heterostructures, the plasmonic Au film (32 nm) has a reflectivity of 0.2786 under the illumination of 632.8 nm  and GH shift (ΔdGHS) response for a defined RIU variation (Δbion = 0.0012) were plotted, as shown in 2Se3/3-layer graphene. dGHS) by changing the number of Bi2Se3 and graphene layers. The configuration of 32 nm Au film-Bi2Se3 (2 QL)-graphene (3 layer) provides the highest differential GH shift of 1.0202 × 104 µm (green curve), which is almost 324 times larger than the second highest differential GH shift of 31.466 µm (blue curve) generated by the configuration of 32 nm Au film/2-QL Bi2Se3/2-layer graphene. When the number of Bi2Se3 QLs is 2, the phase detection sensitivity obtained by varying the number of graphene overlayer are almost on the same order of magnitude of 104°/RIU, as shown in To study the biosensing ability of our proposed biosensor, both differential phase (ΔSPRθ) for a defined RIU variation (Δbion = 0.0012), as shown in 4 degree/RIU, as shown in 6 µm/RIU. It is generally agreed that such a large GH shift can be easily detected by common optical devices. Compared with other reported GH shift-based plasmonic configurations  and graphene overlayers (0–5) were studied, as shown in 2Se3 layers was less than 2, there was a good linear response for change in differential GH shift by changing the RI of sensing interface. Obviously, the obtained GH shift was relative weak, indicating that there was no significant SPR enhancement effects, as shown in 2Se3 layers is 2, the addition of 3-layer graphene can precipitously produce an ultrasensitive response, as shown in 2Se3 layers was larger than 2, the addition of graphene overlayer could not provide a positive response because of excessive energy loss. It can be concluded that the configuration of 32 nm Au film coated with two-QL Bi2Se3 and three-layer graphene has the strongest GH shift response, showing great promise for performing ultrasensitive biosensing for a tiny RI variation.Next, the detailed changes in differential GH shift for the RI from 1.3345 to 1.3357 RIU by tuning the number of Bi2Se3-3-layer graphene. −6 RIU. In contrast to 32 nm Au thin film, 3-layer graphene coated on 32 nm Au film, the optimal configuration: 32 nm Au film−2-QL Bi2Se3-3-layer graphene can provide an enhancement factor (EF) of 2 × 105. It was assumed that significantly local field intensity enhancement should contribute to obtain such a high EF. It is well-known that typical nanoscale heterogeneous configurations, such as C-shaped [2Se3-3-layer graphene was further simulated via finite element analysis method, as shown in 2Se3/graphene sensing interface. Moreover, the electric field intensity decayed exponentially into a running buffer, resulting in a penetration depth of 150 nm. In addition, the charge-transfer mechanism generated by difference in work function (Fermi level) was proposed to contribute to giant electric field enhancement. It has been reported that the work function of Au film is ~5.54 eV and the work function of 2-QL Bi2Se3-3-layer graphene is ~4.75 eV [2Se3/Graphene heterostructures to Au thin film.To quantitatively monitor the concentrations of target analytes, it is necessary to determine a linear response interval for our optimal plasmonic configuration: 32 nm Au film−2-QL BiC-shaped , Φ-shapeC-shaped , bowtie-C-shaped  and ringC-shaped  nanostru~4.75 eV . The lar2Se3-3-layer graphene, the feasibility of monitoring SARS-CoV-2 and its S protein was theoretically studied. It was predicted that the molecular weight (MW) of SARS-CoV-2 is approximately 800 kDa [dGHS = 30.1047 *cSprotein. Here, the Sproteinc denotes the concentration of S protein solution. More importantly, our proposed biosensor also exhibited an excellent response interval (0–13.44 nM) for quantitatively monitoring SARS-CoV−2. The linear response can be expressed by such an equation ΔdGHS = 133.7987 *SARS-CoV−2c, where SARS-CoV−2c stands for the concentration of SARS-CoV−2 solution. Therefore, our proposed plasmonic biosensor has shown great feasibility in quantitatively monitoring SARS-CoV-2 and its S protein.Employing the linear response interval of 32 nm Au film-2-QL Bi 800 kDa , which i 800 kDa . Accordi2Se3/graphene heterostructures with conventional plasmonic Au film. The biosensing performance of our proposed configuration was designed by GH shift, superior to phase modulation. The energy loss could approach zero by introducing the Bi2Se3/graphene heterostructures. The best configuration employed to achieve the highest photon absorption is 32 nm Au film/2-QL Bi2Se3/3-layer graphene, producing an ultralow (approaching zero) reflectivity of 5.4402 × 10−9 and a highest GH shift of −1.0202 × 104 µm. Responding to a small RI variation in 0.0012 RIU, the proposed biosensor was able to provide an ultra-high sensitivity of 8.5017 × 106 µm/RIU. To extend the potential application in biosensing, our proposed biosensor was employed to theoretically predict the adsorption response of SARS-CoV−2 in a tiny RI variation as low as 0.000002 RIU. For SARS-CoV−2, a linear relationship (0~13.44 nM) was determined by an equation ΔdGHS = 133.7987 *SARS-CoV−2c. For its S protein, another linear relationship was described by an equation ΔdGHS = 30.1047 *S proteinc and there was a linear detection interval (0~59.74 nM). In view of these observations, we concluded that, our optimal plasmonic biosensor shows great promise in quantitatively monitoring SARS-CoV−2 and other infectious viruses for practical applications.In this work, we theoretically proposed a sensitivity enhanced SPR biosensor by incorporating Bi


Despite advances in neonatal nutrition, very preterm infants remain at increased risk of extrauterine growth faltering. This prospective study aimed to examine the effect of hindmilk, the milk at the end of a breast expression session, on growth and plasma fatty acids (FAs) of infants born <30 weeks’ gestation who had been on full enteral feeds for ≥2 weeks and had a weight gain of <15 g/kg/day despite optimizing energy and protein intakes. Weight and plasma FAs were assessed before and two weeks after feeding hindmilk. Growth anthropometrics were assessed weekly for four weeks. Paired t-tests and multiple linear regression were used for statistical analyses of data from 34 infants and their 29 mothers. There was a significant increase in weight gain in the two weeks after feeding hindmilk . Weight Z-scores were larger at two weeks  and onwards. Head circumference Z-scores were larger at three weeks  and onwards. Plasma linoleic acid (LA) and α-linolenic acid (ALA) increased after feeding hindmilk. In conclusion, hindmilk may improve weight and head growth and increase LA and ALA in very preterm infants with suboptimal growth. A large randomized controlled trial is required to examine and validate the potential benefits of hindmilk. Despite advances in neonatal nutrition, very preterm infants remain at increased risk of extrauterine growth faltering ,2. Poor Fat constitutes the main energy source in human milk and accounts for 40–50% of caloric intake ,7,8. HinBreastmilk is also the main source of essential fatty acids (EFAs) in the postnatal period. EFAs are essential for brain development, visual functions, and growth . FeedingThe primary aim of this study was to assess the effect of feeding hindmilk on the growth velocity of very preterm infants with suboptimal growth velocity. The secondary aim was to examine the impact of feeding hindmilk on infants’ plasma fatty acid profile. This was a prospective cohort study conducted between January 2019 and June 2022 in the 39-bed level III NICU at Foothills Medical Center in Calgary, Alberta, Canada. The study was approved by the Conjoint Research Ethics Board of the University of Calgary . Written informed consent was obtained from mothers before enrollment. Infants born <30 completed weeks gestation and weighing <1500 g to mothers with enough milk supply (≥150% of infant’s daily needs) were on full enteral feeds for more than 2 weeks and that had slow weight gain , despite optimization of energy and protein intakes, were eligible. Optimization of nutritional intakes was achieved by our two neonatal registered dietitians to meet recommended daily intakes of energy intake  and protein (4.0−4.5 g/kg/day for infants weighing <1000 g and 3.5−4.2 g/kg/day for infants weighing 1000−1500 g) [The primary outcome of the study was the rate of weight gain in the two weeks after feeding hindmilk. Weight gain (g/kg/day) was calculated using the average 2-point method [(W2 − W1)/([(W2 + W1)/2]/1000) /number of days] (W = weight expressed in grams) . The secMother’s own milk (MOM) was the exclusive source of enteral nutrition for study subjects. None of the subjects required pasteurized donor human milk in the 2 weeks prior to hindmilk fractioning or during the study. Weight-based enteral feeding tables were used as per our NICU guidelines, and daily feeding goals were posted at each infant’s bedside. Nutrient fortification commenced at 80 mL/kg/day, and parenteral nutrition was stopped once feeding volume reached 100–120 mL/kg per day and tolerance was observed. Fortification began at 1 package/50 mL human milk, and when the infant reached 100 mL/kg/day it was increased to 2 packages/50 mL human milk . Similac Human Milk Fortifier Extensively Hydrolyzed Protein Concentrated Liquid  was used for nutrient enrichment. In infants with protein intake less than recommended values, Similac Extensively Hydrolyzed Protein Concentered Liquid  was prescribed at 0.5–1.5 g/kg/day amounts after nutrient fortification had reached 0.78 kcal/mL. Enteral feeds were further concentrated if weekly weight gain was <15 g/kg/day. Powdered hydrolyzed-protein formula  was prescribed to further concentrate feeds to approximately 0.92 kcal/mL  as needed. Infants identified to have suboptimal growth velocity were followed daily by registered dietitians.Probiotics were prescribed in infants weighing ≥1000 g as per our NICU protocol. Standardized multivitamin drops were provided daily, containing 375 IU of vitamin A, 200 IU of vitamin D, and 17.5 mg of vitamin C, with an additional 400 IU of vitamin D until the infant reached 37 weeks corrected gestational age. Iron supplement was prescribed at 2–3 mg elemental iron/kg/day beginning at 14 days of life. All infants were weighed daily on electronic scales with a precision of 10 grams by nursing personnel, using the In-Bed scale . Other anthropometric measurements, length, and head circumference were taken by nursing personnel on admission and then weekly till discharge with a newborn length board  and measuring tape, respectively. Infants were classified as being small for gestational age at admission to the NICU if they were below the 10th centile using Fenton’s Growth Curves . Levels Once the mother’s consent was obtained, mothers were counseled by the study lactation support consultant on techniques to separate their milk during routine pumping sessions. All mothers used the double-pumping system for milk expression . Foremilk was defined as the milk collected for 3 min after the flow has begun . HindmilTwo fresh milk samples, 6 mL each, were collected once for milk content analysis at the start of the study. The first sample was from composite milk and the second sample was from hindmilk. Milk samples were analyzed using a near-infrared (NIR) instrument . Milk samples for fatty acid profiles and dried spots  were collected at the same time. Blood samples for plasma fatty acid profiles were collected on dried spots and on the same day as milk sampling; the second sample was collected after 2 weeks. Dried blood and milk spots were initially placed in a refrigerator for <12 h and then stored in a −80 °C freezer. The collection of blood samples was coordinated with other blood tests obtained for clinical purposes. Data on fluid volumes, feeds, macronutrient intakes, and any change in the nutrition plan were collected from electronic charts. Average weight gain was collected weekly for 2 weeks before and 2 weeks after starting hindmilk. The clinical team was encouraged to not change the nutrition plan for 2 weeks after starting hindmilk. Daily weight and weekly length and head circumference were collected from the electronic charts. Furthermore, weight, length, and head circumference were used to calculate Z scores using Fenton Z scores completed gestational week calculator . Our local data (unpublished) indicated that very preterm infants with suboptimal growth velocity had an average weight gain of 13 g/kg/day (standard deviation (SD) = 7). A previous small study of 15 preterm infants showed a 7 g (SD = 4.4) increase in weight gain when hindmilk was fed [p value < 0.05 was considered statistically significant. STATA software was used for all analyses.Descriptive statistics using mean, median, SD, and interquartile range (IQR) were used to describe the study population. A paired t test was used to compare average weight gain before and after hindmilk use. Linear regression analysis was used to assess the association between weight gain and milk content, and to adjust for potential confounding factors that included changes in measured milk protein, gestational age at birth, infant sex, exposure to low-dose postnatal dexamethasone to facilitate extubation (DART protocol) , and BPDn = 82), parental refusal to participate (n = 27), and other reasons (n = 21). Thirty-four infants completed the study . One hundred twenty-nine infants were excluded for; not meeting the inclusion criteria . The median age at starting hindmilk was 33.5  days. Total fluid intake slightly decreased in weeks 3 and 4 A. Total There was a significant increase in the rate of weight gain in the 2 weeks after starting hindmilk compared with the prior 2 weeks . Because the nutritional intakes and growth during the transitional period after reaching full enteral feeds were unstable in some infants, we compared weight gain between the latest week when the infants were on composite milk with the 2 weeks after hindmilk introduction. The detailed nutrient intakes during this period are summarized in Linear regression analysis showed a significant association between the difference in fat content (Δ fat) between composite milk and hindmilk, and weight Z-score catch-up (Δ) between the start of hindmilk and 4 weeks later , Oleic (C18:1 n9), palmitic (C16:0), and linoleic acid  were the dominant fatty acids in milk  and plasOur study indicates that feeding hindmilk to very preterm infants with growth faltering may result in larger weight gain and higher weight and head circumference Z-scores after four weeks. Concentrations of fat and energy were significantly higher in hindmilk and were associated with improved weight and head size growth. Feeding hindmilk resulted in higher plasma EFAs, LA, and ALA. There was no difference in milk fatty acids distribution between hindmilk and composite milk. Although the pathogenesis of suboptimal extrauterine growth is multifactorial, variations in energy intakes could explain approximately 45% of the growth deficits in preterm infants . MeetingFractionating breastmilk in our study resulted in approximately 1.4- and 1.16-fold increases in fat and energy of hindmilk content, respectively, compared with composite milk. This is in line with previous studies on the hindmilk of mothers of preterm infants ,8. PreviOur finding of increased weight gain is consistent with that in a previous study that used similar pre- and post-study design . ValentiIt is worth mentioning that the effect of hindmilk in our study was temporary. The discharge weight z-score returned to values that were presented at the time of hindmilk introduction. The transitional period between 33–34 weeks corrected gestational age, which matches the endpoints in our study, and hospital discharge is complex in extremely preterm infants on respiratory support. Healthcare providers typically try weaning infants off nasogastric tubes and non-invasive respiratory support during this period. In addition, the type of fortification and other nutritional support are usually modified to facilitate hospital discharge. Some infants in our cohort required PN after the study endpoints due to morbidities including late-onset sepsis, NEC, and the need for surgical ligation to close the patent ductus arteriosus. Furthermore, most of the preterm infants in our cohort were transferred to level II NICUs before discharge. Unfortunately, we were not able to track nutritional intakes after the transfer. Using a mathematical approach, a 1.3 g fat/dL difference between analyzed composite milk and hindmilk results in an actual nutritional difference of 1.07 g of fat (83% of milk volume in 100 mL of fortified HM) and 9.6 Kcal/dL, after considering the fortification with liquid HMF and assuming relatively equal fluid intakes between pre- and post-hindmilk. Because the fat absorption in preterm infants is significantly lower than the fat absorption rate used to define metabolizable energy of the Atwater factor (70–80% in preterm infants versus 96% in adults) , the metHindmilk is an attractive source of non-protein energy for improving growth in preterm infants because of its high energy density, lower osmolality compared with other fortification strategies, and its role in providing higher concentrations of soluble vitamins . HoweverStudies of optimal nutrition in preterm infants have primarily focused on the need for adequate protein intake to improve linear growth ,30. Use There was a significant improvement in head circumference Z-score three and four weeks after feeding hindmilk. Previous studies on hindmilk did not reveal a significant change in head growth after hindmilk; however, these studies monitored head circumference for shorter durations ,25,26. In-6 and n-3 long-chain polyunsaturated fatty acids (LCPUFAs). Dietary intakes of LA and ALA, and the balance between them, have the potential to affect the LCPUFA status and impact neural functions and tissue adiposity in preterm infants [n-6: n-3 ratio of 4.5:1.0. The use of human milk fortifier in both phases of our study may partly explain the lack of difference in plasma DHA and ARA levels with hindmilk.Plasma LA and ALA in our study increased by 1.1 and 1.3-fold, respectively, with no change in plasma ARA and DHA. LA and ALA are precursors for  infants ,36. Inte infants . This is infants . It is i infants . The con infants . The humOur study included more infants than previous studies and followed growth velocity for a longer duration. The study is the first to report plasma fatty acid distribution after feeding hindmilk. Our study has several limitations to acknowledge. First, the study did not have a control group to compare growth anthropometrics and fatty acids, so it is not known how much of the infants’ growth improvements were due to the hindmilk intervention and how much might have occurred without the intervention. Randomization or having a control group for the infants with suboptimal growth velocity was not logistically feasible or ethical in our NICU settings, because hindmilk was part of standardized practice guidelines that aim to optimize postnatal growth. It is worth noting that the only change for the infants in our cohort was the hindmilk, and there were no other changes to their diet. Second, due to logistical challenges, we analyzed the samples of composite milk and hindmilk at the beginning of the study only and before fortification. A more frequent and comprehensive analysis is required in future studies. Third, we did not perform body composition or magnetic resonance imaging to identify if hindmilk alters the body’s fat mass, fat-free mass, or brain volume and connectivity. Fourth, we did not follow up regarding the long-term growth or neurodevelopmental outcomes. Long-term follow-up studies are needed to further understand the impact of feeding fortified hindmilk.In conclusion, hindmilk produced by mothers of very preterm infants born <30 weeks’ gestation has higher concentrations of fat and energy compared with composite milk. Feeding very preterm infants with suboptimal growth velocity their mothers’ fortified hindmilk may improve weight and head growth trajectories and plasma concentrations of LA and ALA. Whether the infants’ accelerated weight and head growth and increasing plasma LA and ALA improve long-term neurodevelopment and brain growth parameters remains to be explored. Larger studies are required to examine the benefits of hindmilk and validate our results.


This activity, known as retrotransposition, may induce genomic alterations, such as insertions and deletions. Interestingly, L1s can retrotranspose and generate more de novo L1 copies in brains than in other somatic tissues. Here, we describe for the first time interchromosomal translocation triggered by ectopic L1 retrotransposition in neural progenitor cells. Such an observation adds to the studies in neurological and psychiatric diseases that exhibited variation in L1 activity between diseased brains compared with controls, suggesting that L1 activity could be detrimental when de-regulated. LINE-1 (L1) elements are a class of transposons, comprising approximately 19% and 21% of the mouse and human genomes, respectively. L1 retrotransposons can reverse transcribe their own RNA sequence into a  About 20% of the human, rat and mouse genomes are composed of LINE-1 (L1) retrotransposons . Althougin vitro and in vivo, resulting in a L1 genetic mosaic nervous system . HCN cells represent a heterogeneous population composed of neural stem cells and more differentiated NPCs. An episomal retrotransposition-competent human active L1 element (LRE3) controlled by its endogenous promoter and carried an EGFP reporter construct was used to obtain the Clone C6+ . BrieflyPreviously characterized L1 clones in NPCs showed a neuronal differentiation tendency using a mixed differentiation protocol . Then, win situ hybridization) reaction revealed the presence of two signals in two independent chromosomes in HCN cells, suggesting the presence of two X chromosomes, as expected for a female-derived cell line. However, clone C6+ cells displayed an extra signal in a third chromosome (Inverse PCR was used to characterize the post-integration site from clone C6+ . The insromosome . Finallyromosome . Interesde novo L1 insertion using a similar system described here was previously described to map a putative interchromosomal translocation in HeLa cells (Chromosomal translocations caused by L1 retrotransposons were proposed as a mechanism to explain the evolution of recent rodent L1 subfamilies and the occurrence of promoters swapping for non-LTR retroelements in certain avian species . A de noLa cells . The facThe L1 target in the clone C6+ was inside the Loc317538 in chromosome Xq22, which is a region like the dystrophin major muscle isoform. Alterations in gene expression in this region do not seem to cause the strong neurogenic effect observed in this clone. However, the SKY experiment also revealed other, less frequent chromosomal translocations that may contribute to the final phenotype. While our data was observed using an ectopic L1 reporter construct, it is currently unknown if these other interchromosomal translocations were caused by endogenous L1 retrotransposition.A chromosomal inversion involving parental L1 retrotransposon polymorphism has been correlated to autism in siblings . At a so


Letermovir (LTV) for CMV prophylaxis in allogeneic hematopoietic cell transplant (HCT) recipients has decreased utilization of broad-spectrum antivirals for CMV, which may result in more frequent reactivation of herpesviruses not targeted by LTV. We hypothesized that the cumulative incidence of HHV-6 and EBV reactivation, and associated diseases, within 100 days after HCT would increase following the introduction of LTV.We conducted a retrospective study of CMV-seropositive adults who received an allogeneic HCT at our center prior to (5/2015 – 9/2018) and after (10/2018 – 12/2021) routine use of LTV. We reviewed medical records for antiviral use, viral testing, and virus-associated end-organ disease within days 0-100 after HCT. Testing was performed at the discretion of healthcare providers or according to treatment protocols. We computed cumulative incidence estimates treating death and subsequent HCT as competing risks.Figure 1). Two patients in each cohort (0.5%) developed proven or probable HHV-6 encephalitis. Median peak plasma HHV-6 viral load was nearly 1 log10 higher in the LTV cohort . The incidence of tests for and detection of EBV was higher in the LTV cohort, but the proportion of patients with ≥ 1 positive test among tested patients was similar (14% pre-LTV vs 20% post-LTV); of note, EBV testing in both cohorts was mainly protocol driven . There were no cases of PTLD by day 100 in either cohort.We identified 403 patients prior to and 378 patients after routine use of LTV. Characteristics were similar between cohorts except for more frequent use of post-transplant cyclophosphamide for GVHD prophylaxis in the LTV cohort. Broad-spectrum antiviral use, as estimated by available data, was 68% pre-LTV versus 23% post-LTV. The incidence of tests for and detection of HHV-6 were similar in both cohorts (Despite a 66% decrease in broad-spectrum antiviral use after the introduction of LTV prophylaxis in CMV-seropositive allogeneic HCT recipients, there was no evidence for increased HHV-6 or EBV reactivation and associated end-organ diseases. Whether the higher peak HHV-6 viral load in the LTV cohort has clinical implications requires further study.Danielle M. Zerr, MD MPH, AlloVir: Advisor/Consultant Michael J. Boeckh, MD PhD, Allovir: Advisor/Consultant|Amazon: Grant/Research Support|Ansun Biopharma: Grant/Research Support|EvrysBio: Advisor/Consultant|Gates Ventures: Grant/Research Support|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Grant/Research Support|GlaxoSmithKline: Advisor/Consultant|GlaxoSmithKline: Grant/Research Support|Helocyte: Advisor/Consultant|Janssen: Advisor/Consultant|Janssen: Grant/Research Support|Kyorin Pharmaceuticals: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Moderna: Advisor/Consultant|Moderna: Grant/Research Support|Regeneron: Grant/Research Support|ReViral: Advisor/Consultant|Symbio: Advisor/Consultant|Takeda: Grant/Research Support|Vir Biotechnology: Advisor/Consultant|Vir Biotechnology: Grant/Research Support Joshua A. Hill, MD, Allovir: Advisor/Consultant|Allovir: Grant/Research Support|Covance/CSL: Advisor/Consultant|CRISPR: Advisor/Consultant|Deverra: Grant/Research Support|Gilead: Grant/Research Support|Karius: Advisor/Consultant|Karius: Grant/Research Support|Merck: Grant/Research Support|Octapharma: Advisor/Consultant|OptumHealth: Advisor/Consultant|Oxford Immunotec: Grant/Research Support|Pfizer: Advisor/Consultant|Symbio: Advisor/Consultant|Takeda: Advisor/Consultant.


It is widely accepted that some types of learning involve structural and functional changes of hippocampal synapses. Cell adhesion molecules neural cell adhesion molecule (NCAM), its polysialylated form polysialic acid to NCAM (PSA-NCAM), and L1 are prominent modulators of those changes. On the other hand, trace eyeblink conditioning, an associative motor learning task, requires the active participation of hippocampal circuits. However, the involvement of NCAM, PSA-NCAM, and L1 in this type of learning is not fully known. Here, we aimed to investigate the possible time sequence modifications of such neural cell adhesion molecules in the hippocampus during the acquisition of a trace eyeblink conditioning. To do so, the hippocampal expression of NCAM, PSA-NCAM, and L1 was assessed at three different time points during conditioning: after one , three , and six (complete acquisition) sessions of the conditioning paradigm. The conditioned stimulus (CS) was a weak electrical pulse separated by a 250-ms time interval from the unconditioned stimuli . An acquisition-dependent regulation of these adhesion molecules was found in the hippocampus. During the initial acquisition of the conditioning eyeblink paradigm (12 h after 1 and 3 days of training), synaptic expression of L1 and PSA-NCAM was transiently increased in the contralateral hippocampus to the paired CS-US presentations, whereas, when the associative learning was completed, such increase disappeared, but a marked and bilateral upregulation of NCAM was found. In conclusion, our findings show a specific temporal pattern of hippocampal CAMs expression during the acquisition process, highlighting the relevance of NCAM, PSA-NCAM, and L1 as learning-modulated molecules critically involved in remodeling processes underlying associative motor-memories formation. Acquired motor abilities are believed to be stored in the form of structural and/or functional changes in synaptic efficiency . The neuThe role of NCAM, its polysialylated form, and L1 in synaptic plasticity and cognitive processes has been based on several lines of evidence. First, interference with the expression and/or function of these molecules in knock-out mice models or pharmacologically by the administration of antibodies, peptides, enzymes, or antisense oligonucleotides results in impaired long term potentiation (LTP)  and learClassical conditioning of eyelid responses is a well-known and widely used associative motor learning task. In trace eyeblink conditioning paradigms, the conditioned stimulus (CS) is separated from the unconditioned stimulus (US) presentation by a stimulus-free interval (trace), and the hippocampus is thought to play a major role in the formation of this memory trace , 2015. IGiven the critical role of the hippocampus in associative learning , and thead libitum. All experimental procedures were reviewed and approved by the Ethical Committee for Use of Laboratory Animals of the National Distance Education University (UNED) and conducted according to the European Union guidelines (2010/63/EU) and the Spanish regulations for the use of laboratory animals in chronic experiments . All efforts were made to minimize animal suffering.Fifty-seven adult male Wistar rats , group housed three per cage, were used for all experiments. Animals were kept in their home cages at 22 ± 2°C and with a 12 h light-dark cycle (lights on at 7:00 a.m.). Food and water were provided All surgical procedures were carried out under sodium pentobarbital anesthesia (40 mg/kg i.p.) and using aseptic surgical techniques. Four teflon-coated stainless-steel wires  were implanted in the subcutaneous tissue of the right upper eyelid to be used as bipolar stimulating electrodes of the right supraorbital branch of the trigeminal nerve and as bipolar electromyographic (EMG) recording electrodes in the ipsilateral orbicularis oculi (OO) muscle . Electroswivel, Plastics One, US) which allowed the rat to move freely during training.Classical conditioning training was developed using an experimental design that allowed the animals to freely move during acquisition sessions . For this purpose, electrical stimulation of the supraorbital sensory nerve was used as conditioned (CS) and unconditioned (US) stimuli, respectively . ElectriClassical conditioning was achieved using a trace paradigm . BrieflyThe EMG activity of the OO muscle was recorded using a GRASS P511 differential amplifier with a bandwidth of 1 Hz to 10 kHz . Data was stored directly on a computer with an analog/digital converter , at a sampling frequency of 11–22 kHz and an amplitude resolution of 12 bits. Data was analyzed off-line for quantification CRs. The presence of EMG activity during the CS-US period which lasted >10 ms and was initiated >50 ms after CS onset was considered a CR; thus, we avoided including putative alpha responses in the quantification of true CRs. Those recordings presenting EMG activity in the 250 ms preceding CS presentation (change in baseline), or with an evident startle response (response beginning 4 ms after CS and expanded until 100 ms) or artifactual recordings were excluded from the quantitative analysis. The percentage of trials containing a CR in a given session was calculated based on the number of valid trials.g for 5 min. The supernatant was then centrifuged at 15,000 g for 15 min, and the pellet was resuspended in Krebs buffer, containing protease inhibitors, for further use. Protein concentration for each sample was measured by the Bradford method  12 h after the end of the 1st, 3rd, or 6th training session and decapitated. A total of 4–9 animals per group were used. Immediately after decapitation, brains were kept on ice and both right and left hippocampi  were dissected. Tissue samples were coded and stored at −80°C until use. Crude synaptosomal pellets were obtained according to a modified protocol from d method .2CO3 0.1 M/NaHCO3, 0.1 M) for 2 h at room temperature (RT). The solution was removed and 50 μl of pellet samples were added at a concentration of 10 μg/ml to each well of polystyrene flat-bottom ELISA plates. Plates were incubated overnight at 4°C and then washed three times with 1 M phosphate-buffered saline (PBS) containing 0.05% Tween 20, pH 7.4. Additional binding sites were blocked with BSA (3%) for 2 h at RT. Wells were rinsed three times as described above, and incubated with 50 μl aliquots of the corresponding first antibody for 20–24 h at 4°C. Then, wells were washed and 50 μl aliquots of peroxidase-conjugated secondary antibody were added for a 2 h incubation period. Afterward, 50 μl of citrate buffer  containing 1 mg/ml o-phenylene diamine and 0.06% H2O2, added just before use, were placed in each well, and the peroxidase allowed to react for 10 min at RT. The reaction was terminated by the addition of 50 μl of 10 M H2SO4 to each well. Optical density was determined by measuring absorbance at 492 nm with a Microplate Reader .Total NCAM , PSA-NCAM, and L1 were quantified by enzyme-linked immunosorbent assays (ELISAs) according to a previously described protocol . In brieThe following primary antibodies were used: a polyclonal rabbit anti-rat NCAM IgG ; a monoclonal mouse IgM antibody that recognizes specifically a-2–8-linked PSA with chain length superior to 12 residues, and binds with high specificity to PSA on NCAM ; and a monoclonal rat anti-rat L1 IgG . As secondary antibodies, an anti-rabbit IgG peroxidase conjugate , an IgM anti-mouse peroxidase conjugate , and an anti-rat Ig-POD Fab fragments (from sheep immunoglobulin) to IgG-rat peroxidase conjugated  were used, respectively.post-hoc analysis. Biochemical data were analyzed with three-way ANOVAs , followed by Tukey’s post-hoc analysis. Statistical significance was set at p < 0.05. If the Levene’s test for normal distribution was significant then data were normalized by square root transformation (percentage of conditioned responses). All analyses were performed using the SPSS software v.28  and final figures were prepared using CorelDraw X8 Software .Data was expressed as mean ± SEM. Statistical differences between percentages of CRs were determined by repeated measures two-way ANOVA, followed by Tukey’s n = 26), pseudo-conditioning , or context exposure without stimulation . Animals were sacrificed after the 1st , 3rd , or 6th  training sessions.Animals were randomly assigned to one of the following three experimental paradigms: classical eyeblink conditioning  of the supraorbital nerve evoked an early (6–7 ms) activation of the OO muscle, followed by a second, more variable (15–25 ms) EMG activation (not illustrated). These successive muscle activations corresponded to the R1 and R2 components previously described in rats , as wellF = 318.802; p < 0.001; post-hoc analysis revealed that the different was present in all training sessions except the first one.Then the learning capabilities of conditioned and pseudo-conditioned rats were compared using a trace conditioning paradigm. As illustrated in In order to evaluate the effect of classical eyeblink conditioning on the expression of neural cell adhesion molecules in the hippocampus, expression levels of NCAM, PSA-NCAM, and L1 in hippocampal crude synaptosomes were determined 12 h after the 1st , 3rd , and 6th conditioning sessions (complete acquisition) .F = 1.967; p = 0.168], PSA-NCAM , or L1  expression levels at any of the training session studied (The two control groups submitted to either pseudo-conditioning (unpaired CS/US training) or context exposure (non CS or US stimulation) did not significantly differ in neither their synaptic ipsi- nor the contralateral hippocampal NCAM  and post-hoc analysis indicated that it was specifically an upregulation of L1 expression in the contralateral hippocampus of conditioned rats after sessions one and three. Moreover, there was also an hippocampal side effect , since that increase in the contralateral hippocampus was not present in the ipsilateral area, and a session effect  as the difference between groups was lost in the last session. Thus, L1 levels seems to be regulated by conditioning learning in an acquisition-dependent way in the contralateral hippocampus, being overexpressed specifically in this side during initial and partial learning acquisition but not when the conditioning was completely acquired.Regarding L1 levels , a threeF = 4.113; p = 0.0452] in the contralateral hippocampus after one and three training sessions. Once again, there was a significant side effect , specifically in the contralateral hippocampus. After one and three conditioning session PSA-NCAM values were enhanced, but they did not differ to control ones after six sessions . As it happened with L1, PSA-NCAM was overexpressed in the contralateral hippocampus during the initial and partial acquisition sessions but decreased to normal values after complete conditioning acquisition.A similar pattern of learning-induced modulation was found for synaptic PSA-NCAM levels in the paired  group . ConditiF = 47.53; p < 0.0001]. The regulation was not only session-dependent, but also training-dependent. Hence, synaptic NCAM levels from conditioned rats were higher than those of both pseudo-conditioned and context-exposed control groups after the sixth conditioning session, when asymptotic learning levels had been reached . As shown in F = 3.195; p = 0.0772]. Therefore, NCAM seems to be bilaterally upregulated by conditioning learning only after complete acquisition of the association.Finally, total NCAM expression in hippocampal crude synaptosomes, as assessed by ELISA using an antibody that recognizes all NCAM isoforms, was bilaterally increased 12 h after submitting rats to six conditioning sessions [The hippocampus has been one of the brain areas tightly related to the acquisition of new motor abilities. Many studies have proven that this area facilitates, reinforces, and organizes the proper achievement of CRs. According to available information, the full integrity of the hippocampus is needed in order to acquire the conditioning .In the present work, classical eyeblink conditioning in rats was achieved using a trace paradigm in which both the CS and the US were electric pulses. Although rats in both paired (conditioned) and unpaired (pseudo-conditioned) groups were presented with CS and US electrical stimuli, only rats assigned to the paired group did establish an association between both stimuli and therefore learned the task , achieviThen, to evaluate the effect of classical eyeblink conditioning on the expression of cell adhesion molecules in the hippocampus, levels of L1, PSA-NCAM, and NCAM in hippocampal crude synaptosomes were determined. A few rodent studies have evaluated the possible regulation on NCAM, its polysialylation and/or L1 by hippocampal-dependent training experiences  but noneAdditionally, to determine the evolution of the expression of these molecules throughout the learning curve, the measurement was carried out after 1st , 3rd , and 6th (complete acquisition) conditioning sessions.We report here that L1 and PSA-NCAM upregulation is transient in the hippocampus. Thus, both CAMs were overexpressed after first and third sessions in the contralateral hippocampus of the conditioned animals compared to both its ipsilateral hippocampus and the hippocampi of the control group. However, after the 6th conditioning session both L1 and PSA-NCAM returned to basal levels. This finding is in accordance with other studies relating learning to changes in cell adhesion molecules ,b or theOn the other hand, our data showed a completely different pattern for NCAM expression. During the initial and partial conditioning, there were no alterations of its levels, while after conditioning completion (six sessions), a bilateral enhancement of NCAM was observed in the paired group compared to control animals. Previous studies have related NCAM with the progression from a labile memory to a stable, consolidated memory . Our resMoreover, NCAM is composed of three molecular components with relative molecular masses of 120, 140, and 180 kD. NCAM-120 does not appear to be expressed in synapses, whereas NCAM-140 is located on both pre- and post-synaptic membranes and NCAM-180 is restricted mostly to post-synaptic sites . In the In conclusion, the temporal evolution of the three studied adhesion molecules in the hippocampus along the conditioning eyeblink paradigm  could account for initial facilitation of structural changes during learning acquisition (by PSA-NCAM and L1) and late stabilization of previously restructured synapses to progress from a labile to a stable motor memory (by NCAM). These results also suggest that CAMs are learning-modulated molecules whose expression needs to be orchestrated in a coordinated manner in the hippocampus for the proper acquisition of hippocampal-dependent associative motor learning.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.This animal study was reviewed and approved by Ethical Committee for Use of Laboratory Animals of the National Distance Education University (UNED).LJ-D, JD-G, AG, and CS were responsible for the initial conceptualization. LJ-D, AH, KT, KC, and CV performed the experiments. LJ-D, JN-L, and AC analyzed the data, did the writing—review and editing, and were responsible for writing the original draft. CS contributed to the materials. LJ-D, JN-L, JD-G, and AG were responsible for funding acquisition. All authors contributed to the article and approved the submitted version.


Copper is often used as a heat-dissipating material due to its high thermal conductivity. In order to improve its heat dissipation performance, one of the feasible methods is to compound copper with appropriate reinforcing phases. With excellent thermal properties, graphene has become an ideal reinforcing phase and displays great application prospects in metal matrix composites. However, systematic theoretical research is lacking on the thermal conductivity of the copper–graphene interface and associated affecting factors. Molecular dynamics simulation was used to simulate the interfacial thermal conductivity of copper/graphene composites, and the effects of graphene layer number, atomic structure, matrix length, and graphene vacancy rate on thermal boundary conductance (TBC) were investigated. The results show that TBC decreases with an increase in graphene layers and converges when the number of graphene layers is above five. The atomic structure of the copper matrix affects the TBC, which achieves the highest value with the (011) plane at the interface. The length of the copper matrix has little effect on the TBC. As the vacancy rate is between 0 and 4%, TBC increases with the vacancy rate. Our results present insights for future thermal management optimization based on copper matrix composites. Electronic devices are increasingly becoming more integrated, multi-functional, and smaller as a result of the rapid development of the electronics industry. The increment in power density per unit volume produces a great deal of heat, which needs to be quickly dissipated to avoid negative impacts on the efficiency and longevity of equipment ,2,3. By Graphene has attracted the attention of many researchers due to its excellent thermal properties ,15. In eIn this work, we have studied the heat transfer characteristics and mechanism of the Cu/Gr interface using the nonequilibrium molecular dynamics (NEMD) method. ij) = 4ε[(σ/rij)12 − (σ/rij)6] with the values σCu−Gr = 0.30825 nm and εCu−Gr = 0.02578 eV describes the non-bonded van der Waals interactions between Cu and C atoms [The large-scale atomic/molecular massively parallel simulator (LAMMPS) program is applied to carry out the molecular dynamics (MD) simulations ,27,28. R C atoms ,34. Basen = 1–7). The value n here refers to the number of layers of graphene. Lx, Ly, and Lt stand for the Cu block’s length, breadth, and thickness, respectively. To guarantee tiny lattice mismatch strain imposed in the Cu/Gr interface structure, we chose different periods while similar model lengths for the copper and graphene models  across the interfaces to clarify the process of interfacial heat transfer. First, the velocity autocorrelation function (Vacf)  can be oThen, the VDOS is calculated through the Fourier transform of the Vacf:Gr to 140.44 MW/m2K (n = 5).We used the Cu(001)/Gr interface model to study the effect of graphene layer number on TBC. The simulations were performed at 300 K through the NEMD approach, and The interfacial phonon scattering across the interface enhanced by the increment in graphene thickness results in a reduction in TBC. Similar phenomena can be observed in research on heat transport across the gra/Al, gra/Ti, and gra/Ni interfaces. To clarify the underlying mechanisms, we calculated the vibrational densities of different modes (in-plane and out-of-plane) of the interfacial copper and graphene layers and obtained the corresponding phonon coupling strengths as shown in 2K) is about 4.2% and 5.2% higher than the values of the Cu(001)/Gr (640.19 MW/m2K) and Cu(111)/Gr (644.41 MW/m2K) models, respectively. We create three distinct crystal surfaces—(001), (011), and (111)—of the Cu crystals coupled with graphene at the interface to assess the effect of distinct atomic structures upon thermal transport across the Cu/Gr interface c. To stu−3 eV, 1.0 × 10−2 eV, and 1.8 × 10−3 eV, respectively. This means that the energy required to move graphene from a stable position to an unstable position is higher on the (011) surface. Therefore, graphene has the strongest binding ability bonding with the (011) surface. Stronger interfacial bonding is good for phonon transmission, as shown in We calculated the potential energy distribution on different atomic structures by shifting the graphene layer on the ground in order to further confirm the veracity of the findings. The calculation results are shown in t.We further explore the TBC by elongating the length of the copper matrix, i.e., setting the length of the copper matrix as 3.6 nm, 5.4 nm, and 7.2 nm, respectively. As shown in 2K, which is 52.6% higher than that of the model without vacancy defect  graphene decreases by about 78%. The underlying mechanism is that the increase in graphene layers enhances phonon scattering, which weakens the phonon coupling between copper and graphene in the low-frequency region. Second, Cu(011)/Gr possesses the highest TBC (673.61 MW/m2K), which has an increment of 4.2% and 5.2%, compared with the values of the Cu(001)/Gr (640.19 MW/m2K) and Cu(111)/Gr (644.41 MW/m2K) models, respectively. The effect of atomic structures can be clarified through the potential energy distribution, which indicates that a higher energy barrier within the interface means stronger interfacial bonding and is good for phonon transmission. In addition, the interface thermal conductivity increases gradually when the vacancy defect density of graphene increases from 0 to 3.5%. The increasing trend can be attributed to variation in the vibration frequency schemes caused by the fracture between carbon atoms caused around the vacancy defects.In summary, the interfacial thermal conductivity of the copper–graphene interface was systematically studied by means of MD simulations. The key findings are concluded as follows. First, the thermal conductivity of the interface decreases with the increase in the number of graphene layers. Compared with single-layer graphene, the thermal conductivity of n-layer (Compared with previous research regarding the Cu/Gr interface, we have investigated the influence of different factors on the TBC more systematically and gained a comprehensive understanding of the thermal conductance of the copper–graphene interface. The obtained findings are helpful regarding thermal transport mechanisms in future application of Cu/Gr MMCs in thermal management materials.


Decreased BDNF and impaired TRKB signaling contribute to neurodegeneration in Alzheimer’s disease (AD). We have shown previously that coumarin derivative LM-031 enhanced CREB/BDNF/BCL2 pathway. In this study we explored if LM-031 analogs LMDS-1 to -4 may act as TRKB agonists to protect SH-SY5Y cells against Aβ toxicity. By docking computation for binding with TRKB using 7,8-DHF as a control, all four LMDS compounds displayed potential of binding to domain d5 of TRKB. In addition, all four LMDS compounds exhibited anti-aggregation and neuroprotective efficacy on SH-SY5Y cells with induced Aβ-GFP expression. Knock-down of TRKB significantly attenuated TRKB downstream signaling and the neurite outgrowth-promoting effects of these LMDS compounds. Among them, LMDS-1 and -2 were further examined for TRKB signaling. Treatment of ERK inhibitor U0126 or PI3K inhibitor wortmannin decreased p-CREB, BDNF and BCL2 in Aβ-GFP cells, implicating the neuroprotective effects are via activating TRKB downstream ERK, PI3K-AKT and CREB signaling. LMDS-1 and -2 are blood–brain barrier permeable as shown by parallel artificial membrane permeability assay. Our results demonstrate how LMDS-1 and -2 are likely to work as TRKB agonists to exert neuroprotection in Aβ cells, which may shed light on the potential application in therapeutics of AD. Alzheimer’s disease (AD) is the most common disorder that causes dementia. Amyloid β (Aβ)-containing plaques and neurofibrillary tangles deposited in the brains are the main pathological features . SeveralBrain-derived neurotrophic factor (BDNF), a neurotrophic factor, is expressed ubiquitously in whole brain and plays a vital role in promoting neural plasticity, neuronal growth and cell survival . BDNF haDecreased BDNF has been shown in several neurodegenerative diseases . PreviouDeveloping novel small molecule agonists of TRKB receptor is a potential therapeutic strategy for neurodegenerative diseases including AD . To iden2 [We tested the coumarin derivative LM-031 and the analogs LMDS-1 to -4 . Accordi2 , which w2   values of curcumin, LM-031, LMDS-1 to -4 and coumarin to inhibit Aβ aggregation were: <5, 9, <5, 18, 14, <5 and 25 μM, respectively  compared to the untreated cells (100%). Treatment with LM-031, LMDS-1, -2, -4 at 1.2–5 μM, or LMDS-3 at 2.5–5 μM significantly increased the intensity of green fluorescence  (P > 0.05)  increased significantly in Aβ-GFP-expressing SH-SY5Y cells , while treatments with curcumin, LM-031, analogs and coumarin at a concentration of 5 μM decreased the ROS level induced by induced Aβ expression  (Aβ-GFP SH-SY5Y cells  were use106–92%) , while A > 0.05) . For Aβ < 0.001) . These rP = 0.002), process  and branch  of neurites. Respective curcumin, LM-031 or analogs (5 μM) treatment successfully increased neurite length  and branch , while rescue of process was evident only for curcumin and LM-031  (P = 0.007) and caspase 1  activities were also considerably elevated by Aβ overexpression, whereas treatment with curcumin, LM-031 and analogs (5 μM) decreased AChE  and caspase 1  activities in comparison to no treatment  and caspase 1 activity, and neurite outgrowth, were evaluated. Aβ overexpression significantly reduced length  . AChE (1reatment .P > 0.05). TRKB expression was unaffected by treatment with LM-031 and analogs . In contrast, TRKB-specific shRNA decreased the amount of TRKB in Aβ-GFP-expressing cells without  or with  LM-031 and analogs treatment , p-AKT , and p-CREB  in cells infected with scrambled shRNA, and the reduction was not worsened by TRKB-specific shRNA infection (P > 0.05). Treatment with LM-031 or analogs rescued the reduced p-ERK , p-AKT  and p-CREB  levels, and the rescue was blocked by TRKB-specific shRNA .In addition to examining the level of TRKB, the levels of downstream signaling effectors including ERK, AKT and CREB in TRKB-knockdown cells in response to treatment with LMDS compounds were also examined . Aβ-GFP P < 0.001) of neurite, and shRNA targeting TRKB furthermore decreased neurite length/branch to 18.7 μm/1.5 (P = 0.040–0.020). In Aβ-GFP cells, treatment with the LM-031 or analogs rescued the reduced neurite length (from 22.4 μm to 27.7–30.9 μm) and branch (from 1.8 to 2.6–2.9) (P < 0.001), and the rescue was blocked by shRNA targeting TRKB . Neurite process was significantly increased only by LM-031 , which was deterred by shRNA targeting TRKB .In the aforementioned TRKB-knockdown Aβ-GFP cells, the effects of LM-031 and analogs on increasing neurite outgrowth were assessed . OverexpP = 0.004–0.007), LMDS-1 and -2 treatment rescued the reduction , whereas U0126 treatment lowered the elevation of p-ERK  and wortmannin treatment lowered the elevation of p-AKT  (P = 0.004–0.001), p-CREB , pro- and m-BDNF  and BCL2 , and increased BCL2 associated X, apoptosis regulator (BAX) . In contrast, treatment with LMDS-1 and -2 increased p-TRKB Y516 and Y817 , p-CREB , pro- and m-BDNF  and BCL2 , and reduced BAX . Treatment with U0126 or wortmannin attenuated the increase in p-CREB , pro- and m-BDNF  and BCL2 , and reduced the decrease in BAX   to LMDS-1/2-treated SH-SY5Y cells expressing Aβ-GFP . Overexp< 0.001) . Additio > 0.05) .P = 0.007–<0.001). BDNF at 100 ng/ml and LMDS-1, -2 at 5 μM were then selected to compare the efficacy in TRKB signaling (P = 0.001), p-AKT  and p-CREB , and BDNF, LMDS-1 and -2 treatment rescued the reduction . No significant differences in p-ERK, p-AKT and p-CREB were detected between BDNF and LMDS-1/2 groups (P > 0.05).As LMDS-1 and -2 target ERK, AKT and downstream CREB, effects of BDNF and LMDS compounds on TRKB signaling were compared. Oxidative stress attenuation was first evaluated by treating Aβ-GFP cells with BDNF at 1–100 ng/ml concentration or LMDS-1, -2 at 1.2–5 μM concentration . The ROSignaling . Overexpin vitro BBB permeability of LM-031 and analogs was then estimated using the PAMPA-BBB approach. Quality controls, including high permeability bupropion [−6 cm/s) and low (< 2 × 10−6 cm/s) BBB permeable controls, had effective permeability (Pe) values of 17.06 and 1.65 (10−6 cm/s), respectively  respectively, suggesting to be categorized as BBB permeable (Pe > 2 ×10−6 cm/s) in PAMPA-BBB measurement. Due to the low mass recovery (12.7%), the Pe value of LMDS-4 was not determined.As of now, the PAMPA model has been proposed to analyze membrane permeability, including BBB , 33. Theupropion , and intectively . Well-ac0 ± 0.12 , 14.88 ±2 [There are several reasons for identifying small molecules acting as novel potential TRKB agonists for AD therapeutic uses. First, there is no available treatment currently to cure AD or to halt its progression. Second, substantial evidence has shown that decreased BDNF and impaired TRKB pathways, including ERK, CREB and PI3K-AKT, contribute to neurodegeneration in AD –17. Thir2  and pred2  support LM-031 and LMDS-1 to -4 significantly reduced ROS production  and promin vitro biding assay should be performed to provide evidence of LMDS compounds binding to extracellular domain of TRKB [In addition to targeting TRKB, neurotrophic receptor tyrosine kinase 1 (TRKA) agonist D3 have been shown to provide beneficial effects to activate TRKA-related signaling cascades and enhance cholinergic neurotransmission in transgenic mice overexpressing human APP with KM670/671NL and V717F mutations . Targeti of TRKB  to show Once TRKB is activated, three major signaling cascades, PLC-γ1, ERK and PI3K-AKT, ensue . CREB caSeveral known small molecules or compounds such as catalpol, cystamine, rosmarinic acid and wogonin could increase BDNF expression, but their role as TRKB agonists are not validated –50. Up tIn this study, we identified LM-031 analogous compounds LMDS-1 and -2 which may serve as the potential TRKB agonists to treat AD. This is supported by our experimental results demonstrating TRKB signaling-activating, aggregation-inhibitory, oxidative stress- and caspase 1-reducing, and neurite outgrowth-promoting effects in Aβ-GFP SH-SY5Y cells. Pursuit of analogous compounds resembled to the identified compounds should be of interest in the future.https://www.ibscreen.com/), ChEMBL (https://www.ebi.ac.uk/chembl/) and ZINC (http://zinc15.docking.org/) databases were screened using compound similarity search software tools. Four top-scoring compounds LMDS-1 to -4 were selected and obtained from Enamine . In cell culture media, these five compounds had no solubility problems all the way to 100 μM. The following items were bought from Sigma-Aldrich Co. : curcumin (control for monitoring Aβ folding), kaempferol (antioxidant control in DPPH assay), coumarin  and BDNF.In-house LM-031 activating the CREB-dependent survival and anti-apoptosis pathway was prepared as described . To searhttp://www.perkinelmer.com/tw/category/chemdraw), the following properties of LM-031 and its analogs were computed: MW, HBD, HBA, cLogP, and PSA. Additionally, BBB permeation scores were derived utilizing the BBB prediction server Online BBB Predictor (https://www.cbligand.org/BBB/) [Using Internet software ChemDraw (rg/BBB/) .in vitro [Thioflavin T is widely used to visualize and quantify the presence of misfolded amyloid protein aggregates in vitro . The Aβ in vitro . In addiin vitro  was usedin vitro .Docking calculations for LM-031 and analogs were carried out using the GOLD docking program , 63. TheHuman neuroblastoma SH-SY5Y-derived Aβ-GFP cells were maintained as stated . The rec4/well) were seeded on day 1, pre-treated with test compounds (1.2–5 μM) plus induced Aβ-GFP expression (5 μg/ml doxycycline) on day 2, and stained with Hoechst 33342  on day 8 as stated [Neuronal differentiation of Aβ-GFP SH-SY5Y cells was induced by retinoic acid  . Cells os stated . Cell imΔCt, ΔCT = CT (HPRT1) - CT (EGFP), where CT stands for cycle threshold, was used to compute fold change.Total RNA was extracted, converted to cDNA, and the expressed Aβ-GFP RNA was quantified as stated . The for4/24-well) with retinoic acid addition on day 1, treated with tested compounds (5 μM) plus induced Aβ-GFP expression (5 μg/ml doxycycline) on day 2, and stained with TUBB3 (tubulin beta 3 class III) primary antibody , goat anti-rabbit Alexa Fluor® 555 secondary antibody , and DAPI  on day 8 [As stated, Aβ-GFP SH-SY5Y cells were seeded (6 × 10on day 8 . Neurona5/well) were subjected to the retinoic acid, test compound and doxycycline treatments as stated. Cells were collected on day 8 and cell lysates prepared for caspase 1  and AChE (Sigma-Aldrich) activity measurement [Cells on 6-well plate  on day 1, infected with lentivirus on day 2, pretreated with test compound (5 μM) plus inducing Aβ-GFP expression on day 3, and collected for neurite outgrowth or TRKB protein analysis on day 9 as stated [To knock down TRKB expression in Aβ-GFP SH-SY5Y cells, lentiviral short hairpin RNA (shRNA) targeting TRKB and control (scrambled) were used . Cells ws stated .5/6-well) on day 1, treated with tested compounds (5 μM) plus induced Aβ-GFP expression with doxycycline (5μg/ml) on day 2, as stated. Kinase inhibitors U0126 (an inhibitor of ERK) or wortmannin (an inhibitor of PI3K)  (10 μM) were added on day 6. The cells were collected on day 8 for BDNF, BCL2, BAX, total/phosphorylated TRKB, ERK, AKT, and CREB protein analysis as previously stated.Cells were plated in the presence of retinoic acid  was computed [The permeability of LMDS-1 and -2 was determined by a PAMPA-BBB assay. Firstly, 300 μl of LMDS-1 or -2 (1 μM) solution were added to the donor well (Millipore). Bupropion (a high permeability marker), piroxicam (a low permeability marker), and lucifer yellow (an integrity marker) (Sigma-Aldrich) were used as quality control (QC) compounds for comparison. The sandwich with aqueous donor on the bottom, artificial lipid membrane (PVDF filter coated with porcine polar brain lipid) in the middle, and aqueous acceptor (5% DMSO in PBS) on the top was assembled as stated . Each cocomputed .t test or one-way ANOVA  with a post hoc Tukey test were used to assess group differences. P values < 0.05 indicated statistical significance.The mean ± standard deviation from three independent experiments are reported as the data. As appropriate, a two-tailed Student’s


Further, the samples of different grades reinforced with varying graphene percentages are subjected to mechanical characterisation tests such as the tensile test and hardness. It is found that 2 wt% graphene reinforced composites exhibited enhanced yield strength and ultimate tensile strength. Microstructural studies and fracture morphology are studied, and it is proven that composite processed via the microwave method has exhibited good ductile behaviour and promising failure mechanisms at higher load levels.From the aspect of exploring the alternative lightweight composite material for the aerospace launch vehicle external fuel tank structural components, the current research work studies three different grades of Aluminium alloy reinforced with varying graphene weight percentages that are processed through powder metallurgy (P/M) route. The prepared green compacts composite ingots are subjected to microwave processing (Sintering), hot extruded, and solution treated (T6). The developed Nano-graphene reinforced composite is studied further for the strength–microstructural integrity. The nature of the graphene reinforcement and its chemical existence within the composite is further studied, and it is found that hot extruded solution treated (HEST) composite exhibited low levels of carbide (Al Graphene has been the focus material in the current trend, owing to its exceptional physical and mechanical properties. Graphene comprises carbon atoms arranged in a honeycomb structure in a single layer, and this monolayer surface is 2D in nature . It was Aluminium , possessing an excellent strength-to-weight ratio, is a non-ferrous alloy used in various strategic applications such as space exploration, aircraft, and several structural areas, which are the reasons for considering potential material in this study. The research experiments were focused on three different grades, i.e., AA 2024 , AA 6061 , and AA 7075  aluminium powders (gas atomized) in the order of 10 Microns average particle diameter and up to 99.98 wt% purity, which was procured from Ampal Inc. .2/g, was purchased from Angstron Materials Inc., . The same has been used to reinforce the alloys AA2024, AA6061, and AA7075 matrices with varying weight composition percentage by 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, and 3 wt%.Graphene as a potential reinforcing material, with its exceptional mechanical and physical properties and an average of ~5–10 μm (X-Y dimensions) and specific surface area of 1200 to 1450 mAluminium graphene composite was initially fabricated by employing the stir-Squeeze casting method; however, the homogenous dispersion of graphene was observed as a challenge due to agglomeration and graphene being less dense; it flies off the liquid molten pool. Powder metallurgy was found to be a suitable method for fabrication of AA -Graphene nano composites.The process involves processing and extraction of fine layers of graphene by ultra-sonication and consolidated with calculated weight of metal powders introduced which is stirred for a period of 60 min to obtain uniform slurry in the shear mixer and then dried in a vacuum for 2 h at 60 °C. To ensure homogeneous distribution, the mixture is ball milled for 30 min with a ball-to-powder ratio of 10:1. Tungsten carbide balls of 10 mm were utilised. The homogenised composite mixture with different combinations of graphene percentage  was further mixed with zinc stearate binders and polyvinyl alcohol (PVA) as functionaliser, and compaction was carried out with steel dies at a dwell time of 3 min at 500 MPa pressure to obtain Ø50 mm × 100 mm-long green compacts. Powder metallurgy involves various processes, which include weighing, blending, and consolidation of the powder mixture , compaction, and finally sintering (microwave). The green compacts are sintered in a microwave furnace for C for 15 min holding time in the continuous presence of an argon inert gas environment. The process parameters of sintering were arrived after a series of pilot studies and optimisation. Thus, sintered green billets are then subjected to hot extrusion to eliminate porosities and improve the density of composites  External tank Structural application), and to obtain a definite shape of flat and 450 °round bars, as shown in 2/g; the large surface area of graphene provides high wettability and contact area. The layer of graphene is stacked one over the other into agglomerations. However, it is necessary to ultra-sonicate the graphene during fabrication in order to prevent agglomeration of graphene sheets. When graphene-reinforced composites are studied and validated for external fuel tank structural application, the morphology of graphene used as a reinforcement must be examined using HR-TEM, which is a powerful tool to analyse the morphological and structural characteristics of graphene from the micro- to nanoscale in the order of atomic resolution. The electron diffraction pattern is instrumental in determining the layer and lattice parameters of the material examined. Morphological characteristics such as particle shape, size, texture, and surface area can be analysed using FESEM. To understand the suitability of the fabricated composite for the SLWT External tank structural application, the final composite properties matching the existing material need to be studied from the materials aspect, which can be influenced by factors such as grain size and the reinforcement-matrix strength microstructural integrity of the final extruded composite. In this direction, P/M fabrication process on materials involves different distributions of the particle size (10–25 µm) to ensure enhanced uniform properties in the final part. Generally, secondary operations such as laser treatment, bulk modification including heat treatment, and aging play major roles in controlling the grain size growth and eventually in controlling the mechanical properties of the final component .Particle shape and size plays a significant role on the component’s final properties. Resultant grain size analysis is the fundamental characteristic of powder particles that affects other parameters such as materials flow rate, apparent density, processability, compressibility, and formability. Obtaining ultra-fine grained microstructure improves the mechanical properties such as ultimate tensile, compressive and rupture strengths, elongation to failure, tensile and compressive young’s modulus, shear modulus, density, and at last the thermal characteristics such as thermal conductivity, specific heat capacity, and thermal expansion coefficient, which are in agreement with the properties highlighted, outlined, and published by Metallic Materials Properties Development and Standardization (MMPDS), Federal Aviation Administration (FAA) .In the process of developing a new alternative composite material combination for the existing SLWT external tank structural application, final composite materials grain size is engineered by using matrix average particle size of (~10–25 µm) and reinforcement average particle size of (~10 nm) ,17. The 2, Mg2Si, CuAl2 and Al2CuMg [As aimed for the alternative composite material for existing SLWT external tank structural components such as the liquid oxygen tank, intertank, and liquid hydrogen system, it is very important to study the elemental composition of the matrix and reinforcement used in fabricating the composite . In the  Al2CuMg ,15,16.2Si) improves resistance to abrasive wear and magnesium-silicon combination enhances strength of the alloy by heat treatments. Silicon also increases the followability of these alloys when casted [Aluminium 6061 is a medium-to-high strength alloy with heat-treatable properties; the alloy has good corrosion resistance and manufacturability, as magnesium 1.16 wt% and silicon 1.51 wt% are the major alloying elements present in 6061. The inclusion of silicon  which can be associated with Al–O–Al bonds of anhydrous Al2O3, as seen in similar Al4C3 occurs at 499, 609, 711, and 785 cm−1, possibly due to Al–C bonding vibrations. 4C3. The possible explanation could be attributed to the maximum carbon solubility in aluminium being 0.015 wt% at PPM levels. This clearly proves that there is very low levels of Al4C3 formation in the composite matrix. Additional examination of FTIR Spectra from −1 and 1405 cm−1. Corresponding peaks are majorly due to the association of the C–O–C stretching with respective wavenumber and are mainly due to O–H deformation as a result of in-plane bending vibrations [Fourier Transform Infrared (FTIR) Spectroscopy is widely used as a method of elemental analysis for a wide range of inorganic materials, organic, polymeric, and two or more chemical compounds. In many studies, it is speculated that graphene present as reinforcements reacts with aluminium, forming aluminium carbides. This reaction may cause the composites to lose reinforcing properties, can degrade the processed composites, and is quite risky to use as a replacement composition for the SLWT external fuel tank structural application. However, Al 1400 °C . Figure brations  researchbrations . The stabrations .2 C=C bonds peak, which is specific to the asymmetric flaky carbon in the form of graphene nano particles (GNPs) appearing at 1670 cm−1 in the spectrum recorded for the AA 7075 2 wt% Gr composite (β) [−1 with a stronger intensity that exhibited the form of exfoliated GNPs. This characteristics phenomenon can be related with flaky graphene carbon atoms interact with the incident ray, more widely and potentially owing to the exfoliation process as a result of ultra-sonification and microwave processing followed by hot extrusion of the composite. Reinforced nano GNPs exhibited no reaction and conversion of any intermetallic compound’s groups i.e., like Al4C3. It can also be understood that absorption bands in such phenomenon may be due to the detection boundary of the FTIR process for the solid samples [The stretching vibrations of spsite (β) . Yet, a  samples ,23,24.The EBSD maps and data show vital information such as average grain size diameter, grain elongation and misorientation angle, and pole figures, grains boundaries, and crystal structure orientation. r—radius of the particle, f—volume fraction (dispersed phase).Comparing The refined grains, however, rely on the time profile and temperature, and depend on the critical size of the particle. These extruded samples produce elongated grains along with Graphene, during extrusion in the direction of metal flow, however larger weight fraction of graphene for above 2 wt% shows agglomeration of particles in the EBSD maps. These agglomerations make the grain boundaries weaker. The dispersed graphene particles are more clearly visible in higher magnification which can be ascertained from TEM analysis. It is also noted that the graphene remains as heterogeneous particle by not reacting with the phases and alloying elements present in the microstructure, the same can be verified in FTIR spectroscopy and TEM.The introduced graphene reinforcements mainly interrupt the growth of grains due to re-nucleation by graphene creating more fine grain structure. This is obvious, as the pinning effect of added graphene blocks the composite growth. Graphene acts a nano-level fillers thereby minimizing defects in the matrix material such as point defects, line dislocation, and surface defects. It was also noted that the interface between the matrix and graphene is effectively interlocked . 4C3, whereas few others testified there is no transformation of Al4C3. The pictures also displays precipitates found in the alloy matrix, which are responsible for improving material strength. These precipitates resist the movement and rearrangement of dislocations by means of pinning force. The optimum pinning power of dislocation is achieved over graphene, which stabilizes the microstructure by trapping the mobile dislocations. Two major challenges in the fabrication of Al–Gr composites are the formation of aluminium carbides with graphene and surface contamination of aluminium powders forming oxides. Few papers have reported the formation of AlThis study also confirms there is no formation of carbides in the composite matrix. The possibility of carbide formation can be due one of several reasons, including (i) maximum solubility of carbon in aluminium , (ii) suMitigation of oxide formation was yet another challenging task and can be addressed by fabricating the composite mixture in a vacuum/inert  atmospheThe comparative findings obtained from the tensile test are compiled in The increase in tensile strength demonstrates the effect of the addition of graphene in a virgin alloy as a suitable and promising reinforcement material. Increasing the mechanical properties meanwhile reflects the graphene’s elastic nature. Such a major UTS enhancement with the advent of graphene cannot simply be assumed to be a simple rule of mixtures, further its influence is far beyond what was previously reported and can be extensively studied ,31,32,33The strengthening is due to load transferring from the matrix material to graphene particle reinforcements, which also act as a load bearing component and not merely controlling dislocation movement. There is a small drop in strength due to agglomeration in the higher concentrations of graphene 2.5% and 3%, and lower concentrations are not adequate to bear matrix loads. The stress–strain curves generated during the experiments are shown in The degree of strengthening depends on the particle distribution in the ductile matrix; in addition to shape of the particles, the reinforcements can be described by specifying average particle size, volume fraction, and mean interparticle spacing. Graphene prevents the propagation of cracks thereby strengthening the matrix by absorbing the dislocations from the matrix material. Such reinforcements work in two distinct ways to delay dislocation movement: the reinforcement particles can be cut by dislocations, or the graphene particles can resist dislocation .It is also known that graphene’s planar 2-D structure interlocks the aluminium matrix thus establishing a diffusion-free bond between both increasing the dislocation density by thermal disparity between filler and the matrix. Such 2-D planar structures can be in the form folds and wrinkles, when the material is loaded the load transfer to reinforcements either try to unfold or expand the graphene particles. The other predictable reason for strength increase is due to grain fineness by graphene particles due to thermal heat absorption, the grain fineness can be examined in a microstructural investigation.Hall-Petch  grain reThe other strength mechanisms could be by inherent properties of the alloy attributed to stacking fault energy, coherency strain, lattice friction stress, modulus effect, ordered structure, and interfacial energy.The strain field resulting from the discrepancy between particle and the matrix given by Mott and Nabarro would be a basis of strengthening. The increase in yield strength is given by Equation (4) ∆σ = 2 In most alloys, there is not enough of a modulus difference; however, the reinforcement fulfils the criteria for the difference in modulus, thereby producing a possible strong strengthening effect. The above equation given by Hirsch and Kelly is derived for the case of spherical reinforcements, but the maximum strengthening due to surface effects arises from thin plate-shaped (planar) reinforcements which can resemble graphene’s planar structure.The significant improvement in the ultimate tensile strength, results in a longer life with nominal ductility. These enhancements of composite strength are attributed mainly to strengthening of dislocation, optimum grain refinement, and various other models. The Orowan strengthening mechanism may also contribute to improvement in the strength of the composites. It can also be justified that the extrusion process is also leading to an improvement in tensile strength; however, it is challenging to understand the contributions from two or more mechanisms combined .The graphene pulls and tear signifies that the transition of load occurred from the matrix to the reinforcement, and partially pulled out and pulled off graphene was also observed which confirms the transformation of load from matrix to graphene. In this research study, an exhaustive characterisation such as spectroscopy, XRD, EDS, EBSD, FE-SEM, and HR-TEM analysis was carried out to determine the metallurgical properties, chemical analysis, and formation of detrimental phases, and mechanical properties such as tensile and hardness were investigated. The findings from the characterisation and mechanical evaluation were compared potentially with the materials requirements of the SLWT external fuel tank structural components, indicating the following clarifications.Graphene nano-flake analysis at higher magnification revealed that graphene is a two–dimensional flaky structure. It was also noted that graphene has an enormous surface area, which plays a key role as matrix material reinforcements with good wettability and can be a potential reinforcing material when considered for the launch vehicle SLWT external tank structural application.The composites were successfully fabricated and the reinforcement particles were found to be homogenously distributed and clarified through EBSD maps and HR-TEM. EBSD of 2 wt% Gr shows more uniform dispersion of particles; however, higher wt% Gr exhibited grain boundary agglomeration. Microwave processing and hot extrusion  procGraphene remains as a heterogeneous particle by not reacting with the phases and alloying elements present in the microstructure, the same can be also verified in FTIR spectroscopy, and TEM.XRD, EDS, and FTIR confirm the presence of graphene was intact as a reinforcement material and that there was no formation of carbide. This non-reactive nature of the graphene is achieved by the microwave processing, as the process is quite fast and heat is achieved from the core of the composite.The maximum yield strength exists at aluminium alloys reinforced by 2 wt% graphene. AA 7075 is also reported to have outperformed other alloys due to its inherent alloy properties. The maximum tensile yield strength observed for AA2024 + 2% Gr, AA6061 + 2% Gr, and AA7075 + 2% Gr was 255.5 MPa, 252.0 MPa, and 332.5, respectively. AA 7075 with 2% graphene displayed the highest hardness values, and the lowest was AA 6061, with 1% graphene. The hardness was a maximum of 95 HRB for 7075 + 2% Gr and the lowest 63 HRB was reported for AA 6061 + 1 wt% Gr.The graphene pulls and tears signify that the transition of load occurred from the matrix to the reinforcement, and partially pulled out and pulled off graphene was also observed, which confirms the transformation of load from matrix to graphene. The bonding mechanism, processing conditions offered by microwave sintering, and the hot extrusion process (compared to hot rolling process) were found to be potential and perfect conditions to convert the fabricated composites for the launch vehicle SLWT external tank structural application.


A self-grinding exfoliation strategy that depends on mutual shear friction between flake graphite particles is successfully developed to prepare pristine graphene with largely enhanced yield and productivity.Bioinspired assembly of pristine graphene nanosheets to an interconnected aramid nanofiber network is achieved by a continuous sol-gel-film transformation strategy and generates a flexible yet highly thermoconductive film.Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices. Herein, we report a bioinspired nanostructured film with the integration of large ductility and high thermal conductivity based on self-exfoliated pristine graphene and three-dimensional aramid nanofiber network. A self-grinding strategy to directly exfoliate flake graphite into few-layer and few-defect pristine graphene is successfully developed through mutual shear friction between graphite particles, generating largely enhanced yield and productivity in comparison to normal liquid-based exfoliation strategies, such as ultrasonication, high-shear mixing and ball milling. Inspired by nacre, a new bioinspired layered structural design model containing three-dimensional nanofiber network is proposed and implemented with an interconnected aramid nanofiber network and high-loading graphene nanosheets by a developed continuous assembly strategy of sol–gel-film transformation. It is revealed that the bioinspired film not only exhibits nacre-like ductile deformation behavior by releasing the hidden length of curved aramid nanofibers, but also possesses good thermal transport ability by directionally conducting heat along pristine graphene nanosheets.The online version contains supplementary material available at 10.1007/s40820-022-00919-0. Hybrite films –13. Grapte films , 15, higte films –18 and bte films , 20. Thete films . Neverth [−1 L−1 . A typicFor the co-assembly of the exfoliated graphene and polymers, layered composite structure with high-loading, well-aligned graphene is one of the most effective structural patterns, which makes full use of the ultrahigh in-plane thermal conductivity of graphene nanosheets for directional heat conduction along orientation direction . Solutio−1 L−1)  and post-yield ductility (5.5–18.6%) in the graphene-based composite film  were used as received.Flake graphite , commercial aramid microfiber , potassium ethoxide , dimethyl sulfoxide  and ZrO2 mirobeads with a diameter of 500 μm as grinding media were loaded into the tank, followed by grinding at a peripheral speed of 23 m s−1. Unless otherwise stated, the grinding time is fixed to be 24 h. The weight ratio of ZrO2 mirobeads to DMSO is fixed to be 5.3. In order to decrease the interparticle distance between flake graphite for self-grinding, initial graphite concentration is increased from 1 to 50 mg mL−1.Flake graphite was added into a grinding tank containing the solvent of DMSO. ZrO2) into water for gelation. DMSO and potassium ethoxide were gradually diffused into water, generating a robust, black hydrogel. Finally, the hydrogel was dried to remove water at about 50 ℃, forming a ductile film with a thickness of about 30 μm.Graphene/aramid nanofiber film is prepared continuously by a sol–gel-film transformation process. Commercial aramid microfiber, potassium ethoxide and DMSO were mixed at a weight ratio of 2: 1.5: 96.5. The mixture was mechanically stirred for two days at 40 ℃, forming a viscous and dark red aramid nanofiber (ANF) solution. The ANF solution was mixed with the exfoliated graphene by mechanical stirring, forming a uniform sol. The weight ratio of graphene to ANF is controlled to be 40/60, 50/50, 60/40, and 70/30. The sol was extruded continuously from a die with a rectangular gap . Values of thermal conductivity were calculated from the equation K = α × Cp × ρ, where K, α, Cp and ρ represent thermal conductivity, thermal diffusivity coefficient, specific heat capacity and density, respectively. Specific heat capacity was measured with a differential scanning calorimetry . Thermal diffusion coefficient in plane was measured using an LFA 467 NanoFlash. Density was obtained by the calculation of sample dimension and weight. High-temperature stabilities were evaluated by thermogravimetric analysis , and thermal mechanical analysis .Morphology characterizations were carried out in a field-emission scanning electron microscope , transmission electron microscopy  and atomic force microscopy . Raman spectra were taken in a Raman spectrometer . X-ray photoelectron spectroscopy (XPS) was performed in an X-ray photoelectron spectroscopy excitation . X-ray diffraction (XRD) spectra were collected in an x-ray diffractometer . Rheometer test was carried out on a Haake Mars60, Thermo Fisher Scientific. Mechanical properties were measured on a Shimadzu AGS-X Tester. In tensile test, the gauge length and load speed are 5 mm and 1 mm min−1) and small diameter of grinding beads (500 μm). At high initial concentration, graphite particles would generate a decreased interparticle distance and even contact physically, which enables their mutual shear friction. To drive the rotation of graphite particles at such high initial concentration, small-size grinding beads are used, which help to form stable turbulent flow, homogenize the whole mixed system and improve the exfoliation yield and productivity during grinding . It is different from previously used ball milling process that can only exfoliate graphite at a low concentration by using large balls with a typical diameter from several millimeters to centimeters [To implement the concept of self-grinding exfoliation, we design a microbead milling process which is characterized by high initial concentration of flake graphite . The remarkable decrease is visualized by manually stirring the grinded mixture with a glass rod . It is converted from a viscosity paste into a flow state. The prominent shear thinning behavior facilitates the formation of stable turbulent flow during microbead milling to homogenize the whole grinded mixture [Rheological test is carried out to prove that graphite particles at the high concentration form a jammed network for self-grinding exfoliation. Frequency sweep shows that the storage modulus of the grinded mixture is an order of magnitude higher than its loss modulus over the whole frequency ranging from 0.1 to 100 Hz, indicating that elastic response is predominant Fig. f. It revindrance , 45. Str mixture .d-spacing of few-layer graphene . XPS spectra show that the graphene contains the dominant carbon element and a little oxygen element Fig. i. The oxite Fig. j. These  formula :1\documeM is a dimensionless parameter that describes the shape change of 2D peak. It can be calculated by the following formula:Here Igraphite, p and Igraphite, s are the intensities of 2D peak and shoulder of graphite, while Igraphene, p, and Igraphene, s are the intensities of 2D peak and shoulder of graphene at the same location as graphite  and graphene  are present [−1 in comparison to pure ANF . And their representative stress–strain curves are shown in Fig. The nacre-like deformation behavior is further proved by cyclic tension test. Cyclic loading–unloading at a small strain in the elastic deformation region exhibits negligible hysteresis, while obvious hysteresis with large loops is generated by cyclic loading–unloading at a strain above the yielding strain Fig. b–c. It iA simplified tensile deformation model is illustrated to understand the relationship between the nacre-like microstructure and its tensile property, as shown in Fig. 2 s−1 with the increased loading from 40 to 70% . Moreover, the composite film with 40% loading of graphene exhibits good thermal stability that the tensile strength and elongation remains about 150 MPa and 14% even at 200 ℃  after heating for 120 s. The temperature evolution curves of hot spot at cross-point with working time are displayed in Fig. The good heat conduction ability is visualized by placing the graphene/aramid nanofiber films with different graphene loadings under a high-power LED lamp as heat dissipating substrate for infrared thermal imaging Fig. g. It is A self-grinding exfoliation strategy is developed successfully through a designed microbead milling of high-concentration flake graphite to prepare pristine graphene with sharply increased yield and productivity. The obtained graphene nanosheets have few atomic layers in thickness, several hundreds of nanometers in lateral size and few defects without introduction of heteroatoms. A sol–gel-film transformation strategy is further developed to continuously assembly the graphene nanosheets and aramid nanofibers into nacre-like layered composite structure with a three-dimensional interconnected nanofiber network. The bioinspired film simultaneously exhibits nacre-like deformation behavior by releasing the hidden length of curved nanofibers and good thermal transport ability by directionally conducting heat along pristine graphene nanosheets, leading to the integration of large ductility and high thermal conductivity. The integrated properties make the composite film potential for heat management in flexible electronic devices.Supplementary file1 (PDF 709 kb)Below is the link to the electronic supplementary material.