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.


In addition, the graphene-modified electrode had a considerably larger sensitivity (0.0124 A/M) and lower detection limit (1.81 × 10−6 M), proving the advantages of employing graphene in electrochemical sensing.In this study, a graphene sample (EGr) was synthesized by electrochemical exfoliation of graphite rods in electrolyte solution containing 0.1 M ammonia and 0.1 M ammonium thiocyanate. The morphology of the powder deposited onto a solid substrate was investigated by the scanning electron microscopy (SEM) technique. The SEM micrographs evidenced large and smooth areas corresponding to the basal plane of graphene as well as white lines (edges) where graphene layers fold-up. The high porosity of the material brings a major advantage, such as the increase of the active area of the modified electrode (EGr/GC) in comparison with that of bare glassy carbon (GC). The graphene modified electrode was successfully tested for L-tyrosine detection and the results were compared with those of bare GC. For EGr/GC, the oxidation peak of L-tyrosine had high intensity (1.69 × 10 Tyrosine (Tyr) is a small, electroactive, and aromatic amino acid used to regulate the signal transduction process in proteins . In humaSeveral methods have been developed for the detection of L-tyrosine including surface-enhanced Raman scattering , high-peGraphene, consisting of a monolayer of carbon atoms exhibits excellent mechanical, thermal, electrical, and optical properties ,15. Its In this work, a simple approach was used for manufacturing a modified glassy carbon electrode employing electrochemically exfoliated graphene. The electrochemical properties of the modified electrode were investigated at electro-catalytic oxidation of Tyr. The electrochemically exfoliated graphene exhibits good electro-catalytic activity to the oxidation of Tyr, since it enhances the peak current and lowers the peak potential. In order to demonstrate the possible application of this electrochemical sensor, we used the standard addition method for the determination of Tyr in spiked samples, demonstrating excellent results.In order to investigate the morphological characteristics of graphene sample, a SEM/TEM Hitachi HD2700 instrument  equipped with a cold field emission gun (CSEG), operated at 200 kV and coupled with a double cut windowless 100 EDX detector acted by AZtec Software (Oxford Instruments) was used.α1 radiation (λ = 1.5406 Å). The background corrected pattern was used for the calculation of graphene structural parameters The X-ray powder diffraction (XRD) pattern was obtained with a Bruker D8 Advance Diffractometer using CuK−1 spectral domain; 4 cm−1 resolution).The FTIR spectrum of graphene sample (mixed with KBr) was recorded with a JASCO 6100 FTIR spectrometer . The sample was dispersed by ultrasound in double-distilled water for 3 min, to form a homogeneous suspension. Next, the spectrum was recorded within 200–800 nm range.5 Hz, in solution containing 10−3 M potassium ferrocyanide and 0.2 M KCl.For electrochemical measurements  a three-electrode cell coupled with a Potentiostat/Galvanostat Instrument  was used. The CVs and LSVs measurements were generally run from 0.0 to +1 V vs. Ag/AgCl, at 10 mV/s scanning rate. EIS measurements were recorded between 0.1 and 10−4 M Tyr was prepared in pH 7 PBS. Next, 0.1 mL of the stock was mixed with 4.9 mL pH 7 PBS which gave a final concentration of 1 × 10−5 M Tyr. This was denoted the unknown concentration (Cx). Next, three volumes  of the stock solution (5 × 10−4 M) were added to three beakers, each also containing the unknown concentration Cx .For standard addition method, the following procedure was applied. A stock solution of 5 × 10All chemicals, including: ammonia , ammonium thiocyanate , potassium chloride , potassium ferrocyanide , L-Tyrosine  and Dimethylformamide (DMF)  were used without further purification. The electrolyte solutions were prepared with double-distilled water produced with Fistreem Cyclon equipment.Two electrochemical cells each containing two graphite rods and filled with 100 mL solution of electrolyte (0.1 M ammonia + 0.1 M ammonium thiocyanate) were connected to the exfoliation system (home-made system). A constant voltage of 11 V was applied between the graphite rods (anode and cathode) for about 4 h. In order to avoid the over-heating of the electrolyte, short pulses of current were applied for 0.8 s, followed by short pauses (0.2 s). The black powder deposited after exfoliation at the bottom of each cell was collected, washed with distilled water (10 L) and finally dispersed by ultrasound for 30 min in 125 mL water. Next, the black suspension was filtered on white-ribbon paper to remove the large particles and finally dried by lyophilization. The obtained sample was following denoted EGr.In 2 mL solution of N,N-dimethylformamide (DMF) were dispersed by sonication 2 mg of graphene powder . Next, a volume of 10 µL from the dispersion was deposited by drop-casting onto the clean surface of a glassy carbon (GC) electrode and dried at room temperature for 24 h. After that, the modified electrode (EGr/GC) was employed for the electrochemical detection of Tyr.The morphology of graphene powder deposited onto a solid substrate was investigated by scanning electron microscopy technique. Two representative micrographs are presented in The structure of graphene sample was next investigated by X-ray powder diffraction technique. In −1 is assigned to the O-H stretching vibrations from the adsorbed water molecules, while the two adsorption peaks at 1383 and 1057 cm−1 are assigned to the C-O stretching vibrations. Their weak intensity is in excellent agreement with the XRD pattern of the sample where a small GO peak is evidenced. The peaks at 1577 cm−1 and 1638 cm−1 represents the vibration modes of sp2-hybridized C=C. Complementary to this, the UV-Vis spectrum of the sample  values were determined after fitting the Nyquist plots with the appropriate equivalent electrical circuit. The first circuit characterizes the bare GC electrode and contains the following elements: the solution resistance (Rs) which depends on the concentration of supporting electrolyte, the Warburg impedance (ZW) that appears due to the diffusion of ions within the double-layer at low frequency, the charge-transfer resistance (Rct) that reflects the easiness of electron transfer across electrode-solution interface and a constant phase element (CPE) that replaces the double-layer capacitance (Cdl). For graphene-modified electrode, due to the high porosity of graphene layer the circuit additionally contains a transmission line (T) [ct values were determined to be: 75.5 kΩ for bare GC and 1.16 kΩ for EGr/GC, indicating that the graphene layer highly favors the transfer of electrons when deposited on top of a conductive substrate.In order to fully characterize the bare and graphene-modified electrodes, the EIS spectra were recorded and the experimental data were represented as Nyquist plots . The chaline (T) . After f−4 M) was investigated in buffer solutions of various pH (3.6–8), using the LSV technique . In highly acidic solution (pH 3.6) a clear oxidation peak appears at around +0.85 V which shifts towards lower potentials, in neutral and basic solutions. The linear regression equation that describes the variation of peak potential, Ep, versus pH is given by: y = 1.019 − 0.053 × pH. In this case, the slope value is 0.053 V/pH being close to that obtained from a Nernstian plot (0.059 V/pH) and indicating an equal number of protons and electrons involved in the electrochemical reaction. The maximum peak current, Ip, was observed in pH 7 PBS, so all of the experiments were next performed at this pH  and appears at higher potential (+0.84 V) in comparison with that of graphene-modified electrode (+0.64 V). The increased sensitivity of EGr/GC towards Tyr oxidation may be due to the enhanced electron transfer rate at the edges of graphene sheets. In addition, the π–π stacking interaction between the aromatic ring of Tyr and graphene may help with the orientation of OH group towards graphene, favoring its oxidation.In order to evidence the electro-catalytic properties of the synthesized material towards L-tyrosine oxidation, the comparison between the graphene-modified electrode and the bare GC electrode is shown . The LSV−6 M Tyr, while with bare GC the lowest signal was obtained at a higher concentration, of 3 × 10−5 M Tyr. This indicates an increased sensitivity of the graphene-modified electrode, in comparison with bare GC.Next, Tyr was quantitatively analyzed by LSV and the corresponding recordings at various concentrations are plotted in p) versus Tyr concentration, the corresponding calibration plots were obtained and represented in p = 1.88 × 10−7 + 0.0124 × C, R2 = 0.988, while for bare GC is Ip = 8.8 × 10−8 + 0.00265 × C, R2 = 0.968. As can be seen in this figure, the EGr/GC electrode has a considerably higher sensitivity (0.0124 A/M) and lower detection limit (1.81 × 10−6 M), in comparison with those of bare GC: 0.00264 A/M sensitivity and 9 × 10−6 M detection limit. The detection limit was obtained by dividing the limit of determination (LOD) by 3.3.By representing the peak current (I−4 M each). In the case of a single analyte (ascorbic acid) the oxidation signal appears as a very broad peak, at low potential . The dopamine peak is well defined and appears at higher potential  while uric acid appears at +0.35 V (pink curve). When Tyr is mixed with all of these analytes (10−4 M each), an increase of the capacitive current is observed but no changes are noticed for the peak potential (see the olive curve in comparison with the brown curve). For the Tyr peak intensity, a slight increase is observed, from 1.042 × 10−6 A  to 1.129 × 10−6 A (mixture of TYR + AA + DOP + UA), indicating a weak influence of the interfering species.The selectivity of EGr/GC electrode towards Tyr oxidation was evaluated in the presence of other biomolecules, such as ascorbic acid (AA), dopamine (DOP) and uric acid (UA). In −5 M, giving an excellent recovery (98.5 %). In order to confirm the results five standard addition measurements were performed and the recovery range was between 98.5% and 103.1%, proving the efficiency of the EGr/GC electrode.The EGr/GC electrode was also tested for Tyr detection using the standard addition method . The peaSeveral advantages of the employed electrode can be mentioned such as the simple approach used for manufacturing the graphene-modified electrode, the very wide linear range of L-Tyrosine with good sensitivity and detection limit, and the excellent recovery results obtained with the standard addition method in spiked samples .In addition, it is important to mention that the graphene sample employed as electro-catalyst has an excellent time stability. If stored in a closed recipient it can be used in electrochemistry for over a year. As concerned the modified electrode, it shows an excellent working sensitivity. More than 20 measurements were recorded with the same electrode and the signal was >95% of its original value. Between the measurements, the electrode was kept in distilled water for 15 min to desorb the surface contaminants. The longtime stability was also investigated over a 10 days period, indicating that the analytical performance of the modified electrode has not significantly changed , 2 configuration of carbon atoms is predominant within the synthesized material. The graphene sample was used for glassy carbon surface modification (EGr/GC) and next tested towards Tyr detection. By representing the peak current (Ip) versus Tyr concentration, the corresponding calibration plots were obtained. The linear regression equation for EGr/GC electrode was: Ip = 1.88 × 10−7 + 0.0124 × C, R2 = 0.988, while for bare GC was Ip = 8.8 × 10−8 + 0.00265 × C, R2 = 0.968. As expected, the EGr/GC electrode had higher sensitivity (0.0124 A/M) and lower detection limit (1.81 × 10−6 M), in comparison with those of bare GC: 0.00264 A/M sensitivity and 9 × 10−6 M detection limit.A graphene sample was prepared by electrochemical exfoliation of graphite rods in solution containing 0.1 M ammonia + 0.1 M ammonium thiocyanate. The porous morphology of the sample was revealed by SEM technique while the structural parameters were determined from the XRD pattern. Hence, the average number (n) of layers within the graphene crystallites, the inter-layer spacing (d), the mean crystallite size (D) of graphene and the amount of GO, FLG, and MLG (expressed as %) were determined. In addition, FTIR and UV-Vis complementarily characterized the sample indicating that the sp


We reported an innovative transparent, elastic and flexible conductive composite materials P(SSNa-BA-St)/PEDOT/graphene which were prepared by using P(SSNa-BA-St) latex as template for PEDOT polymerization and graphene doping. This P(SSNa-BA-St)/PEDOT/graphene film exhibited highly transparent, good water resistance, low moisture adsorption, highly elastic and highly conductive properties, which can serve as a practical approach to fabricate the flexible, conductive and transparent films for wearable and implantable electronic devices, and photovoltaic cells. We reported an transparent, water resistant, and flexible conductive materials P(SSNa-BA-St)/PEDOT/graphene and their conductivity are due to the large surface area to polymerize the extended PEDOT chain on the nanoparticles. Basically, EDOT can be chemically polymerized in a PSS solution to form PSS/PEDOT dispersion.5 However, PSS as an insulator could strongly decrease the conductivity of the PSS/PEDOT.6 Therefore, increasingly intensive work is going on to enhance the conductivity of PSS/PEDOT by organic compounds, salts, acid, zwitterions and anionic surfactant, etc.7–9 Secondary doping by polar solvents is also used to increase the conductivity, which is attributed to morphological changes. Doping the polar solvents could trigger phase separation between the conducting PEDOT chains and insulating PSS chains, leading to an interconnected network of elongated PEDOT grains and removal of insulating PSS chains for electrical conductivity enhancement.10–12The polyelectrolyte complex poly (PEDOT)/poly(styrene sulfonate) (PSS) is one of the most well-known organic conductors with highly conductive, largely transmissive to light, processible in water and flexible.13 Directing mixing the water soluble graphene oxide (GO) with PEDOT/PSS was limited by the poor conductivity of GO,14 therefore, the water insoluble reduced graphene oxide (RGO) was carefully in situ polymerized with PEDOT/PSS to make the highly conductive PEDOT/PSS/graphene composite.15Graphene has also been used as the candidates for making conductive composite with PEDOT/PSS.16 Blending with polymers is one of the most efficient route to increase the flexibility of PSS/PEDOT. Poly(ethylene glycol) (PEG), poly(ethylene oxide) (PEO), poly (PVA), and polyurethane (PUR) have all been used.16–19 Chiu et al. designed highly flexible PEDOT:PSS–P(styrene-co-butyl acrylate) (P(St-BA)) dispersions by using PEDOT:PSS as stabilizer for P(St-BA) latex, but the P(St-BA) latex were micro-sized range with polydispersity due to the weak stabilizing capability of PEDOT:PSS.20,21 Chiu et al. also designed PEDOT:PSS–(P(St-BA)) dispersions by applying dodecylbenzene sulfonic acid (DBSA) as surfactant.22 However, one disadvantage of these polymer blended film is the decrease in conductivity with increasing amounts of insulating polymer. And the blending approach is even more difficult with hydrophobic elastomers.On the other hand, much work has been devoted to increasing the flexibility and stretchability of PEDOT/PSS which is a characteristic required for a range of applications such as wearable, implantable and large-area electronic devices.Herein, P(SSNa-BA-St) latex were used as template for both graphene and PEDOT to prepare the transparent, highly elastic and conductive P(SSNa-BA-St)/PEDOT dispersions. SSNa served as both stabilizer and monomer for P(SSNa-BA-St) copolymerization latex, therefore, no extra surfactant is needed and monodispersed nanoparticles are formed. The graphene locating on the surface of P(SSNa-BA-St)/PEDOT particles through the hydrogen bonding and stacking interaction between not only PSS and graphene but also PSt and graphene. P(SSNa-BA-St) latex with approximately 128 nm sizes have large surface area to polymerize the extended PEDOT chain on the surface of the nanoparticles, which can provide much higher conductivity than PSS/PEDOT that having grains with hydrophobic coiled PEDOT chains in the core and hydrophilic insulating PSS as the shell. Moreover, the P(SSNa-BA-St)/PEDOT/graphene presented here exhibited transparent, good water resistance, low moisture adsorption and highly elastic properties, which can serve as a practical approach to fabricate the flexible, conductive and transparent films for wearable and implantable electronic devices, and photovoltaic cells.2.2.1n-butyl acrylate , potassium persulfate , dimethyl sulfoxide  and methanol (≥99%) were purchased from Aladdin.Sodium styrenesulfonate  and iron(iii) ferric sulfate (Fe2(SO4)3, AR 99%) were purchased from Macklin. Reduced graphene oxide was purchased from Suzhou Tanfeng Graphene Tech Co., Ltd.3,4-Ethylenedioxythiophene , styrene (St), 2.22 with stirring in a round bottom flask, followed by addition of the 0.1 g KPS through a constant flow pump. After stirring at 78 °C for 4 h, the emulsion polymerization was finished. The NPs were washed twice by centrifugation at 10 000 rpm for 30 min and ready to use.A total of 3 g SSNa, 4.9 g BA and 2.1 g St were mixed with 78 g water at 78 °C for 15 min under N2.32, followed by stirring overnight at 30 °C. Then the P(SSNa-Ba-St)/PEDOT elastic conductive dispersions was prepared.15 g of the prepared P(SSNa-Ba-St) emulsion and 0, 1, 2, 4, 5 g EDOT  were separately mixed with 15 g water followed by 15 min sonication. 0.005 g ferric sulfate in 10 g water and 2.85 g KPS in 60 g water were separately added into two constant pressure dropping funnels. Extra water was added into the flask to keep the total mass of the content as 135 g. Then the two mixture in funnels were dropped into the flask for 2 h at the same time under N2.4−4, 1.5 × 10−3, 3.0 × 10−3, 3.7 × 10−3 wt%) was added into the flask with 30 min sonication and 1 h stirring at 30 °C under N2. 0.005 g sulphate heptahydrate in 10 g water and 2.85 g KPS in 60 g water were separately added into two constant pressure dropping funnels. Extra water was added in to the flask to keep the total mass of the content as 135 g. Then the two mixture were dropped into the flask for 2 h at the same time under N2 and stirring followed by stirring overnight at 30 °C. A flow of N2 was used to prevent the overoxidation of PEDOT which might lead to conductivity deceasing. Then the P(SSNa-Ba-St)/PEDOT elastic conductive dispersions was prepared.15 g of the prepared P(SSNa-BA-St) emulsion and 0, 1, 2, 4, 5 g EDOT  were mixed with 15 g water followed by 30 min sonication. Then 0, 1, 2, 4, 5 g graphene /PEDOT or P(SSNa-Ba-St)/PEDOT/graphene dispersion in advances.The mixed solution was dropped cast on a glass plate and then dried at 50 °C for 3 h to form the P(SSNa-Ba-St)/PEDOT or P(SSNa-Ba-St)/PEDOT/graphene elastic conductive composite film.2.6−1 resolution in the spectral range 4000–400 cm−1. The glass transition temperature (Tg) of each sample was determined using a differential scanning calorimeter (DSC) . 12 mg of dispersions dried powders were sealed into a 40 μL aluminium pan. An empty pan was used as a reference sample. The temperature scan for each sample was measured from −50 °C to 50 °C at a heating rate of 5 °C per minute. The data acquired by the DSC were analysed by STAR Thermal Analysis software (NETZSCH 200F3) to determine the onset and endset glass transition temperatures.To determine the hydrodynamic diameter and zeta potential of the P(SSNa-Ba-St) latexes, dynamic light scattering (DLS) and zeta potential measurements were carried out using a Zetasizer Nano ZS system . DTS Application 5.10 software was employed to analyse the data obtained. The chemical groups of the nanoparticles were analysed by Fourier transform infrared (FTIR) (Thermo NICOLET iS10) in transmission mode. For that, dried material powders were mixed with KBr (40 mg) and then formed into a disc in a manual press. Transmission spectra were recorded using at least 32 scans with 4 cm, where R represents the surface resistance (Ω sq−1), D is the film thickness (cm). Equal width and length were used throughout this study. The optical transmittance spectra of the conductive composite films in the visible light wavelength range (300–700 nm) were detected using a UV-visible spectrometer. The contact angle was measured by Powereach JC 2000D.The surface resistance was measured using an ohmmeter. The conductivity of the composite films was evaluated by the following equation: Bending tests of the PSS/PEDOT and P(SSNa-Ba-St)/PEDOT/graphene film were performed to detect the flexibility. The conductive dispersions were coated on flexible poly substrates to form the specimens. The bending test was executed by bending the specimens back and forth (180°) 100 times.3.ca. 128 nm by intensity (PDI: 0.08) and the average zeta potentials was ca. −50 mV. With the help of efficient stabilizer SSNa, the size of the latex was in nanometre range with low PDI which provide large surface area to polymerize EDOT on the nanoparticles. And the strong negative surface charges make them serve as good charge compensator of positively charged PEDOT and also provide the high colloidal stability of the nanoparticles. Then the P(SSNa-BA-St) latex were applied as a template for both EDOT polymerization and graphene–water dispersion. As shown in 13,23The P(SSNa-BA-St)/PEDOT/graphene were synthesized as shown in −1, 1080 cm−1, 1335 cm−1, and 1519 cm−1 are corresponding to the C–S bond in thiophene rings; –SO2, and –SO3− in PSS; C–C stretching in thiophene rings and C PBM data was replaced with SVG by xgml2pxml:<glyph-data id="z.dbd" format="PBM" resolution="300" x-size="8" y-size="10" xml:space="preserve">00000000000000000000000000000000111111110000000011111111000000000000000000000000</glyph-data><svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="13.200000pt" height="16.000000pt" viewBox="0 0 13.200000 16.000000" preserveAspectRatio="xMidYMid meet"><metadata>Created by potrace 1.16, written by Peter Selinger 2001-2019</metadata><g transform="translate scale" fill="currentColor" stroke="none"><path d="M0 440 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z M0 280 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z"/></g></svg>C asymmetrical stretching in thiophene rings, respectively, indicating the successful incorporating the PSS in the system.24 The peaks at 1725 cm−1 of PEDOT/P(SSNa-BA-St) and PEDOT/P(SSNa-BA-St)/graphene was associated with CO stretch of BA.25 The extra peaks at 3152 cm−1 and 3432 cm−1 for PEDOT/P(SSNa-BA-St)/graphene are attributed to the remaining –OH group on the surface of the graphene, which are typical peaks for reduced graphene oxide, and it confirms the formation of graphene dispersed PEDOT/P(SSNa-BA-St) dispersions.23,26In order to investigate the components of the conductive film, the typical FTIR spectrum of the extracted composite polymer was shown in −1, owing to the first-order scattering of the E2g phonons and the D band exhibited at 1343 cm−1 which is attributed to the breathing mode of κ-point phonons of A1g symmetry.27 Based on the empirical equation, ωG = 1581.6 + 11/(1 + n1.6),28 where ωG is the band position in wavenumbers and n is the number of layers present in the sample, the number of layers of the graphene can be estimated as two. And also, the 2D band in Fig. S128,29 However, the D band exhibited very high intensity (ID/IG = 1.1) indicating the disorder or the defect present in the graphene.29,30 For the P(SSNa-BA-St)/PEDOT in C anti-symmetric stretching (1570 cm−1), CC asymmetrical stretching (1502 cm−1), CC symmetrical stretching (1437 cm−1) and single C–C stretching (1366 cm−1).31 Comparing with the PEDOT/P(SSNa-BA-St), the graphene doped PEDOT/P(SSNa-BA-St) exhibited slightly shifted  according to the strong π–π interaction of aromatic structures of PEDOT/P(SSNa-BA-St) and electron-rich graphene, illustrating the successful doping of graphene into PEDOT/P(SSNa-BA-St).23,32The protection effect of PSS and electron-stacking interaction between graphene and P(SSNa-BA-St)/PEDOT are confirmed by Raman spectroscopy. The Raman spectrum of graphene applied in this work was consistent of the typical reduced graphene oxide spectrum as shown in Fig. S1.The conductive dispersions were drop casting on glass coverslips and PSS/PEDOT , PSSNa- and PSS films al−1 to 0.025 S cm−1 owing to the concentrations of conducive component increasing, followed by the decreasing to 0.006 S cm−1 owing to the precipitation formation of excessive PEDOT, indicating the best doping concentration of EDOT to PSS here was 0.06. More important, instead of PSS, the conductivity trend of applying P(SSNa-BA-St) as the template for PEDOT polymerization follows the same with PEDOT/PSS but exhibit much higher conductivities than them. The sample of EDOT to PSS(SSNa-BA-St) ratio as 0.06 provides the highest conductivity as 0.25 S cm−1 which is 10 times higher than PEDOT/PSS with the same content ratio. The improvement of conductivity is owing to the small nanoparticles sizes (approximately 128 nm) of P(SSNa-BA-St) latex providing larger surface area to polymerize the extended PEDOT chain on the surface of the nanoparticles, leading to higher conductivity than PSS/PEDOT that having grains with hydrophobic coiled PEDOT chains in the core and hydrophilic insulator PSS as the shell.In order to investigate the optoelectronic properties, P(SSNa-BA-St)/PEDOT were drop casting on the glass substrate to form the well mixed uniform conductive films. The conductivity of PSS/PEDOT and P(SSNa-BA-St)/PEDOT films were shown in −1 to 2.500 S cm−1 which is higher than the reported PEDOT/graphene composite layers (0.13–0.20 S cm−1).33,34 The 10 times conductivity increasing compared with P(SSNa-BA-St)/PEDOT and 100 times increasing comparing with PSS/PEDOT are due to the help of unique electrical properties of graphene and also indicates that the graphene were successfully doped on the surface of P(SSNa-BA-St)/PEDOT particles through hydrogen bonding and strong π–π interaction of graphene with PSS and PSt. Then the conductivity dropped down to 0.625 S cm−1 by reaching the graphene to EDOT ratio at 0.005, owing to the excess of graphene precipitated out of the solution. In addition, the conductivity of P(SSNa-BA-St)/PEDOT/graphene films can also be enhanced by applying the solvent effect. As shown in By controlling the EDOT to PSS ratio as 0.06, the conductivity of the graphene doped P(SSNa-BA-St)/PEDOT were shown in 35 However, the P(SSNa-BA-St)/PEDOT films exhibited elongated grains and form longer connected networks of PEDOT-rich area and the phase segregate of P(SSNa-BA-St) and PEDOT was shown in 36 This phenomenon demonstrated that the conductivity improvement from PSS/PEDOT to P(SSNa-BA-St)/PEDOT is also attributed to an increase of phase separation. The graphene sheet of P(SSNa-BA-St)/PEDOT/graphene film was observed by AFM images which illustrated the graphene sheet was stabilized in the system and located in the P(SSNa-BA-St)/PEDOT matrix, as shown in Atomic force microscopy (AFM) was applied to reflect the morphological changes in the films. 37 indicating their excellent waterproof ability due to the copolymerization of water insoluble monomers BA and St, as shown in In addition, the hydrophobicity of as prepared films was also investigated. The high hydrophilic PEDOT:PSS film exhibit the water contact angle at 30°, however, the contact angle of P(SSNa-BA-St)/PEDOT/graphene film can reach to 78° which is much higher than the reported 4.8–7.0° for PSS/PEDOT/graphene,Tg but the DSC results showed that the Tg for P(SSNa-BA-St)/PEDOT was around −8.1 °C and P(SSNa-BA-St)/PEDOT/graphene was around −10.6 °C which can be attributed to the introduction of the lower Tg material BA and St. The decreases of Tg could provide the excellent flexibility and elasticity to the films. The bending tests were also performed in σ0/σ) was used, where σ0 and σ were the surface conductivity before and after bending, respectively. For the pure PSS/PEDOT specimen, the surface conductivity decreases to 15% of the original after 100 times bending cycles while P(SSNa-BA-St)/PEDOT/graphene remain 83% of the original. This indicated that the introduction of P(SSNa-BA-St) latex could strongly enhance the flexibility of conductive films compared with the conventional PSS/PEDOT film.4.Tg of (SSNa-BA-St)/PEDOT/graphene film provide the excellent flexibility and elasticity to the films. Therefore, the P(SSNa-Ba-St)/PEDOT/graphene presented here exhibited transparent, good water resistance, low moisture adsorption, highly elastic and highly conductive properties, which can serve as a practical approach to fabricate the flexible, conductive and transparent films for wearable and implantable electronic devices, and photovoltaic cells.We reported an innovative transparent, elastic and flexible conductive composite materials P(SSNa-Ba-St)/PEDOT/graphene which were prepared by using P(SSNa-Ba-St) latex as template for both graphene and PEDOT. No extra surfactant is needed and monodispersed nanoparticles are formed. The conductivity of P(SSNa-BA-St)/PEDOT/graphene exhibit 220 times higher than the untreated PSS/PEDOT, which are due to the phase separation between the conducting PEDOT chains and insulating P(SSNa-Ba-St) chains. And P(SSNa-BA-St) latex have large surface area to polymerize the extended PEDOT chain on the surface of the nanoparticles, which provide higher conductivity than PSS/PEDOT that having grains with hydrophobic coiled PEDOT chains in the core and hydrophilic insulating PSS as the shell. Furthermore, the water contact angle of P(SSNa-BA-St)/PEDOT/graphene film can reach to 78° and remain the original shape on the substrate under water flow, and also, the moisture absorption of P(SSNa-BA-St)/PEDOT/graphene films is 13.3 times lower than of PSS/PEDOT film after leaving in air for 12 h, which indicates an excellent water resistance ability due to the copolymerization of water proof BA and St monomers. The relatively low There are no conflicts to declare.RA-009-C9RA09099A-s001


Background: Long-Interspersed Nuclear Element (L1) retrotransposons are silenced in healthy tissues but unrepressed in cancer. Even if L1 reactivation has been associated with reduced overall survival in breast cancer (BC) patients, a comprehensive correlation with clinicopathological features is still missing. Methods: Using quantitative, reverse-transcription PCR, we assessed L1 mRNA expression in 12 BC cells, 210 BC patients and in 47 normal mammary tissues. L1 expression was then correlated with molecular and clinicopathological data. Results: We identified a tumor-exclusive expression of L1s, absent in normal mammary cells and tissues. A positive correlation between L1 expression and tumor dedifferentiation, lymph-node involvement and increased immune infiltration was detected. Molecular subtyping highlighted an enrichment of L1s in basal-like cells and cancers. By exploring disease-free survival, we identified L1 overexpression as an independent biomarker for patients with a high risk of recurrence in hormone-receptor-negative BCs. Conclusions: Overall, L1 reactivation identified BCs with aggressive features and patients with a worse clinical fate. The “Junk DNA” definition was coined to describe the large fraction of the non-coding, redundant and repeated human genome ,2. The LAPC (in a colon cancer patient) [MYC (in a breast tumor patient) [In healthy adult human cells, this process is negatively monitored, and retro-transpositions are rarely identified. However, in stressing cell conditions such as cancer, the deregulation of global DNA methylation favors L1 reactivation ,8. Alongpatient)  and MYC patient) , L1 sequpatient) . L1 reacpatient)  or the Lpatient) . Confirmpatient) , L1 de npatient) . Accordipatient) ,16 and tpatient) , with popatient) . DespiteTo assess the poorly known correlation between L1 reactivation and the clinical and molecular characteristics of breast carcinomas, we evaluated the expression of these retrotransposons in pre-clinical and clinical settings, investigating BC and non-transformed mammary epithelial cells along with a cohort of 210 BCs and 47 normal mammary glands. To this purpose, we assessed the expression of L1 transcript (mRNA) by using two independent qRT-PCR assays encompassing the ORF1 and ORF2 sequences. The mRNA expression results were then compared with several molecular and clinical data, including promoter methylation, molecular subtyping and disease-free survival (DFS).We profiled 14 cell lines, 2 non-transformed and 12 breast cancer cells. HMEC non-transformed cells were grown in DMEM/F15 with 10% FCS plus 10 ng/mL insulin, 0.5 μg/mL hydrocortisone and 5 ng/mL EGF. MCF-10A cells were grown in DMEM/F12 with 5% HS, 10 μg/mL insulin, 10 ng/mL EGF and 500 ng/mL hydrocortisone. MDA-MB-453 cells were grown in Leibovitz’s L-15 Medium  with 10% FBS  in free-gas-exchange atmospheric air; SKBR3 and MDA-MB 231 in high-glucose DMEM  with 10% FBS; MCF-7 in high-glucose DMEM with 10% FBS supplemented with 10 µg/mL insulin; T47D, ZR751, MDA-MB 468, BT549, HS-578T, HCC70 and HCC1187 in RPMI (Sigma-Aldrich) with 10% FBS; BT474 in RPMI with 20% FBS and 10 µg/mL insulin. MDA-MB-468, T-47D, HS-578T, MDA-MB-231 and BT549 cell lines were obtained from the NCI-60 panel, while MDA-MB-453, SKBR3 and ZR751 cells were derived from the Interlab Cell Line Collection (ICLC) and MCF-7, HCC70, HCC1187, HMEC and MCF-10A from the American Type Culture Collection (ATCC). Lastly, BT474 cells were obtained from the “Deutsche Sammlung von Mikroorganismen und Zellkulturen” . BC cell lines are reported in ® 16 HS System, Promega, Madison, WI, USA) evaluated in September 2021.The genetic identity was confirmed by short tandem repeat profiling , as reported . Patient™ DNase  treatment was additionally performed, according to the manufacturer’s protocol, to avoid the problem of genomic contamination in qRT-PCR.DNA was extracted from cells using the Blood & Cell Cultured Mini Kit , while the RNeasy Mini Kit  was used for RNA extraction. TURBO® 2.0 fluorometer .After review with hematoxylin and eosin (H&E), FFPE tumoral sections were dissected to obtain nucleic acids from tissue areas containing at least 100 cells with >50% tumoral cells. Maxwell RSC FFPE RNA Kit (Promega) was used to obtain RNA from the 210 FFPE BC samples and the 47 FFPE BC normal mammary glands. Genomic DNA was purified from a subset of 41/210 FFPE tissues using the GeneRead DNA FFPE Kit . Nucleic acids were quantified with the Qubit™ IV VILO™ reverse transcriptase .One μg of purified RNA was reverse-transcribed in a mix containing both oligo(dT) and random hexamers using SuperScriptThe expression of L1-ORF1 and ORF2 transcripts were evaluated in triplicate by qRT-PCR using two independent couples of primers and specific thermal profiles, reported in ® assay  based on the classification algorithm PAM50 [Molecular subtyping was performed using the Prosignahm PAM50 ,22,23,24® system  based on the MALDI-TOF (matrix-assisted laser desorption ionization time-of-flight) method, as previously reported [The 41 BCs with available DNA were mutationally characterized with a 147-hotspot breast cancer gene panel using the MassARRAYreported .L1 methylation was studied for both cancer cells and the 41 BCs with available DNA by performing quantitative bisulfite pyrosequencing in triplicate using the PyroMarkQ96 pyrosequencing , as previously reported . BrieflyData analysis was carried out with the SPSS version 20.0 software  by three independent authors .p-values are reported within the text and/or in the tables. p < 0.05 was considered statistically significant. ROC curves were produced with the pROC package (R v4.0.2).Student’s t-distribution was used to determine the distribution of L1-ORF1 and L1-ORF2 expression and the Fisher’s Exact Test to evaluate contingency tables for nominal variables. Survival analysis of disease-free survival (DFS) was evaluated with the Kaplan–Meier method, and groups were compared with the log-rank test. DFS was calculated as the interval between the beginning of the therapy to the time of progression. The Cox regression model  was used to perform the multivariate analysis for tumor relapse. All the available (RQ): 0.05 and ORF2(RQ):0.03; ORF1(RQ): 0.08 and ORF2(RQ): 0.09, respectively), whereas all BC cells showed higher but heterogeneous levels of both ORF1 and ORF2 (ORF1(RQ)mean: 0.59, range 0.03–1.83; ORF2(RQ)mean: 0.81, range 0.09–2.54, p < 0.01, ρ Spearman = 0.91, p = 0.019, p = 0.09, We first assessed L1 expression by evaluating the relative quantification RQ (ΔCt) of ORF1 and ORF2 in twelve BC and two non-transformed mammary gland cell lines. L1 transcript levels were barely detectable in the non-transformed mammary gland cells, namely, HMEC and MCF-10A  , which is the cut-off to discriminate methylation/hypomethylation ,31, wher= −0.65) D.(RQ): 0.05, range: 0.005–0.09; ORF2(RQ): 0.06, range: 0.006–0.07, To confirm the BC-exclusive expression of ORF1 and ORF2, we compared the RQs (ΔCt) of both transcripts in 210 BCs and 47 normal mammary glands. Unsupervised clustering revealed a clear separation between BCs and non-tumoral tissues, the latter being characterized by barely detectable levels of expression for both ORFs (ORF1(RQ): 0.55, range: 0.11–3.47; ORF2(RQ): 1.32, range: 0.09–11.75), supporting the tumor-specific expression of both transcripts  mean: 17.79, range: 0.37–108.13; ORF2(RQ) mean: 27.69, range: 1.24–235.24).None of the tumor samples showed an ORF amount lower than the most expressive normal tissue mean: 34.54, range: 3.43–107.49; ORF2(RQ)mean: 58.76, range: 7.10–235.24) ((RQ) for each subgroup is reported in Each of the PAM50 molecular subtypes had a comparable number of patients . Similar to the scenario detected in the BC cell lines, we observed the enrichment of L1 transcripts in the basal-like subtype (ORF1–235.24) C. Lumina–235.24) C. The HEp < 0.01) ((RQ)p < 0.01 and ORF2(RQ)p < 0.01) ((RQ)p = 0.02, ORF2(RQ)p = 0.01), with a higher L1 expression in tumors with higher TIL scores ((RQ) for each group is reported in L1-ORF expression was increased in poorly differentiated (G3) BCs compared to G1/2 tumors (ORF1 and ORF2 both  < 0.01) D. BCs ch < 0.01) . FollowiL scores E. The men = 8, Luminal B: n = 11, basal-like: n = 12, and HER2-enriched: n = 10). In addition to a mean methylation percentage of 57% (range 27–82%), we observed a negative correlation between demethylation and ORF2 expression , together with a weaker trend for ORF1  (TP53 (29%), eight PIK3CA (20%), two AKT1 (5%), and one CDH1 pathogenic variants (2%)   . Hotspotnts (2%) . Sevente < 0.01) .(RQ) and ORF2(RQ) showed a trending polarization of the patients with recurrence according to high L1 expression . A heatmap for both ORF1pression . Patient(RQ) median level as the cut-off. The BCs highly expressing ORF1 were characterized by a median of 32 months of DFS compared to 49 months for the low expressors (p < 0.01), with a two-times higher risk  of relapse. Similarly, high ORF2 values identified patients with an increased risk of relapse  to assess whether L1 expression was associated with differential DFS. As shown in Data concerning the stratification with the mean levels of ORF1 and ORF2 expression are reported in (RQ) values over the median level, whereas “L1 low-expressors” included patients with at least one ORF(RQ) below the median level. The derived Kaplan–Meier curve identified a strong level of significance (p < 0.01), with an HR for L1 high expressors of 1.9  for both cut-offs , node involvement (0 vs. 1–3 nodes vs. >3 nodes), Ki67 expression (high vs. low), PAM50 subtypes, TILs  and tumor size. Of note, only L1 expression (both stratified for average and median) and lymph-node involvement retained an independent level of significance .p-values, HR and CI95% in Since we described increased L1 mRNA expression as a negative prognostic factor, we focused on the DFS of L1 high expressors (cut-off: median L1(RQ)). In this subgroup, patients with a basal-like (median: 46 months) or with a HER2-enriched subtype (median: 52 months) had a worse prognosis, whereas Luminal patients with a tumor showing high L1 expressions were characterized by a longer DFS . No other correlations were identified between L1 expression and recurrence in other therapeutic approaches , compared with those without recurrence (21/50) (LINE-1 (L1) sequences are usually silenced in human tissues through several mechanisms, including hypermethylation of their promoter . DeregulHere, we report for the first time a detailed characterization of RNA-based L1-ORF expression in a large cohort of BC patients in the attempt to contextualize L1 transcription among BC patients and to correlate L1 reactivation with clinical outcome. We demonstrated a high level of tumor-specific L1 transcripts in 12 BC cell lines and in a retrospective BC cohort, enhanced in HR-negative BCs. Moreover, the association between ORF expression and a high risk of tumor recurrence, confirmed by multivariate analysis, proposes L1 as a biomarker for BC prognostic stratification.The tumor-specific activation of L1 mRNA can be considered crucial to define L1 as a biomarker . The absL1-ORF expression using IHC on FFPE tissue is complex. A pioneering work about L1 expression in BC was based on IHC staining, allowing us to also evaluate the localization of the expression as a marker ; howeverThe application of an RNA-based test was not free from issues, mainly associated with the overlapping of L1 DNA–RNA sequences  and withMYC gene showed the correlation between the hypomethylation of these sequences and a retrotransposon-linked carcinogenic effect [L1 reactivation in BC has historical proofs: in 1988 the insertion of L1 into the c effect . Over thc effect ,15,42,44TP53 mutated tumors, recently confirmed in breast, ovarian and colon cancers [Our results in the BC cell lines are in line with previous reports ,45, thus cancers . The pre cancers .Among all BC pathological factors, we highlighted a possible cross-link between L1 expression and immune-cell infiltration, since L1-high BCs showed high levels of TILs in the stroma. Histologic evaluation of TILs has reached level IB evidence as a prognostic marker in TNBC and level 2A with respect to prediction of response to chemotherapy. Some authors have shown a favorable outcome in TNBCs with TILs > 30% treated by surgery alone , thus suWe also explored the possible clinical impact of L1 expression levels. High L1 levels significantly correlated with a higher risk of BC recurrence in terms of DFS. In the multivariate analysis, lymph-node involvement and L1 expression were the only two independent/significant variables. Node involvement is recognized as one of the main markers for the risk of relapse in BC ,55,56. BBy stratifying the risk according to the BC subtype, the relationship between HR-negative BCs and L1 expression showed stronger results, whereas HR-positive/L1-high lesions did not show a reduced DFS, suggesting poor biological and prognostic significance of L1 retrotransposons in Luminal tumors. HER2-enriched BCs showed great heterogeneity for L1 mRNA level, both in cell models and in the retrospective cohort. HER2-addicted tumors were also characterized by a significant, albeit less robust, L1 stratification of the risk of relapse.Interestingly, L1 has also been considered from a therapeutic perspective. The use of reverse-transcriptase inhibitors (efavirenz) has been shown as particularly effective in TNBC preclinical models and is associated with the metabolism of fatty acids . ConversOur work presents two main issues, both associated with the retrospective design. First, given the heterogeneity of the population, it is impossible to recover data about the overall survival. Second, the small amount of archival material precluded high-throughput DNA analysis for all tumors in the study cohort.L1 expression could be interpreted as a strong negative prognostic marker, especially for HR-negative BCs. When considering the impact on treatment, our data may lead to a hypothesis generating further studies. Indeed, whether L1 expression may be exploited to modulate the treatment of TNBCs or to predict response to chemotherapy or to the combination of chemotherapy and ICIs warrants further investigation.


Position-sensitive detectors (PSDs) are of great significance to optical communication, automatic alignment, and dislocation detection domains, by precisely obtaining the position information of infrared light spots which are invisible to human eyes. Herein, a kind of PSD based on graphene/germanium (Ge) heterojunction architecture is proposed and demonstrated, which exhibits amplified signals by unitizing the charge injection effect. Driven by the graphene/Ge heterojunction, a large number of photogenerated carriers diffuse from the incident position of the light spot and subsequently inject into graphene, which ultimately generates a photoresponse with high efficiency. The experimental results show that the device can exhibit a fast response speed of 3 μs, a high responsivity of ~40 A/W, and a detection distance of 3000 μm at the 1550 nm band, which hints that the graphene/Ge heterojunction can be used as an efficient platform for near-infrared light spot position sensing. PSDs are optoelectronic position sensors that can accurately detect the light spot position, distance, incident angle, and other related physical parameters ,2,3,4. TThe silicon-based PIN  and SchoTwo-dimensional materials are those in which electrons can move freely in only two dimensions, including graphene, black phosphorus, and transition metal dichalcogenides . Two-dimIn this paper, a photoconductive type of PSD based on graphene/Ge heterojunction by using the charge injection effect is presented. Under near-infrared illumination, the photogenerated carriers in Ge diffuse laterally to the graphene/Ge heterojunction region and then inject into graphene. During this process, the graphene/Ge heterojunction plays a critical role in efficiently collecting the photogenerated carriers. As a result, the graphene/Ge photoconductive PSD shows a responsivity of ~40 A/W and a response speed of 3 μs/1.9 μs. More importantly, the device shows a dependent photocurrent variation with the position change of the 1550 nm light spot, and its working distance can reach 3000 μm.−28 A2/Hz. When calibrating the power of the laser, a commercial power meter from Thorlabs was utilized. Throughout the measurement, the bias voltage of the device is 1 V.Raman measurements were performed under ambient conditions using a Renishaw inVia system with a 532 nm excitation wavelength. During the electric characteristic measurement, the graphene/Ge photoconductive PSD was attached to a printed circuit board and inserted into a socket located at a scanning Galvo System. The printed circuit board was connected to a semiconductor device analyzer Keithley 4200A-SCS for electrical signal read-out. The 1550 nm and 980 nm lasers were focused and vertically irradiated the device through the refraction optical path. The spot diameter of the 1550 nm laser is about 2 μm, and the spot diameter of the 980 nm laser is around 1 μm. The laser and microscope share the same optical path. By exploiting a charge-couple device (CCD) camera, the 980 nm laser light spot (with an overlapping incident position with 1550 nm laser) and the device can be seen in the software, in which the light spot of 980 nm laser is marked with visible color. With the assistance of the software, the alignment of the light spot and device can be realized. To measure the position sensitivity, the scanning system carried the graphene/Ge photoconductive PSD and moved accurately with a given value. To measure the response speed, a signal generator was used to connect the laser and generated a modulated light signal at a frequency of 1 kHz. Then, a SourceMeter (FS-Pro) with a high sampling rate was used to measure the transient response of the device. For the noise measurement, a noise analyzer was connected to the device and recorded the noise current of the device. The measurable value of the noise analyzer is as low as 2 × 10−1 (G band) and 2700 cm−1 (2D band), respectively. The intensity of the 2D band is twice as high as that of the G band, indicating that the monolayer graphene used in this work is of good quality. The insert of To prove the improvement effect of introducing graphene, the detection distances of the devices with and without graphene are compared. As shown in netI) is defined bypI is the photocurrent and darkI is the dark current. The noise current of the device is shown in −16 A2/Hz, which provides a strong guarantee for weak light detection and a large working area. oP is the incident light power. Under different light power densities, the average responsivity is about 40 A/W, and the minimum noise equivalent power is 7.15 × 10−12 W·Hz−1/2. The noise equivalent power is defined bynI is the noise current. The high responsivity and low noise equivalent power can be attributed to two factors, namely, high photoconductive gain brought by the high carrier mobility of graphene [In addition to the position sensitivity characteristics, the photoresponse performance of the graphene/Ge photoconductive PSD was also measured. As shown in graphene ,32,33 angraphene ,35.Note that the high carrier mobility of graphene and the built-in field of the graphene/Ge heterojunction are vital for the response speed. The former can ensure the rapid transport of carriers through graphene channels, while the latter can accelerate the charge injection. The response speed of the device is shown in In summary, PSDs that can detect the position change of the 1550 nm laser spot have been realized by integrating graphene with Ge. The introduction of graphene can produce a strong built-in field at the graphene/Ge heterojunction region, which is helpful for effectively collecting photogenerated carriers and driving these photogenerated carriers to inject into graphene. Thereby, the graphene/Ge photoconductive PSD achieves a fast response and linear near-infrared detection. Moreover, the working distance of the graphene/Ge photoconductive PSD is up to 3000 μm, which is three times higher than that of the bare Ge device. These results provide a promising opportunity for infrared PSDs based on low-dimensional materials and traditional bulk semiconductors.