Mixed layers of octadecyltrichlorosilane (ODTS) and 1H,1H,2H,2H‐perfluorooctyltriethoxysilane (FOTS) on an active layer of graphene are used to induce a disordered doping state and form a robust defense system against machine‐learning attacks (ML attacks). The resulting security key is formed from a 12 × 12 array of currents produced at a low voltage of 100 mV. The uniformity and inter‐Hamming distance (HD) of the security key are 50.0 ± 12.3% and 45.5 ± 16.7%, respectively, indicating higher security performance than other graphene‐based security keys. Raman spectroscopy confirmed the uniqueness of the 10,000 points, with the degree of shift of the G peak distinguishing the number of carriers. The resulting defense system has a 10.33% ML attack accuracy, while a FOTS‐inserted graphene device is easily predictable with a 44.81% ML attack accuracy. Using graphene, this study presents efficient extraction of a security key at a low voltage of 100 mV. By inserting self‐assembled monolayers with different functional groups into the graphene device, an irregular distribution of dipoles in the channel is created, resulting in unique characteristics with sufficient randomness, achieving 50% uniformity, a 45.5% inter‐Hamming distance, and a defense rate of 10.33% against machine learning attacks. This is achieved using the variations in physical properties that form during semiconductor manufacture, which produce a “fingerprint” unique to each device. PUFs are commonly used in high‐security applications, such as encryption, because of their ability to produce a randomly generated output specific to the physical structure of a device. The majority of PUFs currently used commercially are developed using silicon integrated circuits (ICs), where both the measurement circuit and the corresponding PUFs are produced through a complementary metal‐oxide‐semiconductor (CMOS) fabrication process based on silicon.In 1984, Gustavus Simmons suggested using the variability of physical properties to produce an authentication application. This idea led to the development of a physically unclonable function (PUF) that generates a distinct cryptographic key for every device. This system has attracted considerable interest in the security industry.1 A PU transistors, and batteries. One of the advantages of graphene‐based electronic devices is their low processing cost compared to conventional silicon‐based devices. Graphene‐based devices offer several advantages over conventional silicon‐based devices with respect to simplicity reducing the overall manufacturing time and lowering the production cost. Complex manufacturing processes are needed in conventional silicon‐based devices, including lithography, etching, and doping. These processes involve multiple steps and require expensive equipment, making the production cost of silicon‐based devices high. In contrast, graphene‐based devices can be fabricated using a simple and cost‐effective process. Graphene can be grown on various substrates by chemical vapor deposition (CVD) or other methods, and the graphene layer can be patterned using conventional photolithography techniques. The process of fabricating graphene‐based electronic devices is more straightforward and less expensive than the process of fabricating silicon‐based devices. Moreover, graphene‐based electronic devices have other advantages over silicon‐based devices. Graphene has excellent electrical conductivity, high carrier mobility, and good thermal conductivity, making it suitable for high‐speed and high‐frequency electronic devices. More importantly, the interfacial dipole effect in graphene is a promising avenue for exploring new applications in electronics. The interfacial dipole effect is a phenomenon that occurs when graphene comes into contact with a substrate or another material with a different electronegativity than graphene. This effect produces a dipole moment at the interface, resulting in a potential difference between the two materials, leading to various phenomena, such as charge transfer, band bending, and doping. For example, when graphene is placed on a substrate with a higher electronegativity, such as SiO2, the electron density in the graphene layer is shifted towards the substrate, forming a negative charge on the substrate side and a positive charge on the graphene side. This potential difference can modify the electronic properties of graphene, including its carrier concentration and mobility.While PUFs based on silicon ICs have been successful, their manufacturing processes are complex and expensive, requiring the same process steps, including unnecessary ones for PUFs that use physical property variations. As a result, PUFs made with emerging non‐silicon materials are gaining traction as a more viable alternative. PUFs can be fabricated using simplified process steps by inducing randomness in the physical properties. Graphene is a 2D material with unique electronic properties, making it attractive for electronic devices. Graphene‐based electronic devices have been developed for various applications, including sensors,5 tran In our work, we amplified device deviation by introducing additional doping using materials that possess an opposite dipole to that of graphene. This study introduces an approach for producing secure electronic devices using a mixed‐assembled layer (MAL) inserted into graphene PUFs. Graphene was used to extract a security key efficiently at a low voltage, as low as 100 mV. To implement PUFs with high entropy, it is necessary to have significant device‐to‐device variation. To achieve this, several approaches have been attempted, including 1) variation in filament formation in memristors, and 3) randomness induced by impurity variation. Another approach is to utilize an atomically‐thin graphene, which exhibits a strong interfacial dipole effect. This effect occurs when graphene contacts a material with distinct electronegativity compared to the graphene itself. By manipulating the interfaces with materials possessing contrasting polarities, significant variations in electrical characteristics can be achieved. Graphene's unique electrical conductivity in comparison to other materials enables the realization of substantial differences in electrical properties upon contact with substrates with distinct electronegativities. To implement graphene‐based PUFs with high entropy, we used a mixed‐assembled layer of ODTS and FOTS inserted into graphene PUFs. Both self‐assembled monolayers (SAMs) of ODTS and FOTS share the same silane group as the head group, but they differ in their tails: ODTS possesses an alkyl chain, whereas FOTS features a fluoroalkyl chain. These SAMs' tails exhibit non‐identical dipole moments; ODTS has a dipole moment of +0.84 D, while FOTS carries a dipole moment of −3.49 D. The significant shift in the Dirac point, which enables the realization of high‐performance PUFs, depends on whether graphene is predominantly bound to ODTS or, conversely, predominantly bound to FOTS. They adjusted the Fermi level by inserting SAMs with different functional groups into the graphene device. This produced an irregular distribution confirmed by measuring the doping state through the electrical characteristics. To assess the security key generated by the device, we employed several indicators, including uniformity, inter‐Hamming distance (inter‐HD), and entropy. These metrics allow us to quantitatively evaluate the randomness and uniqueness of the security key. Each device had unique electrical characteristics because of the irregular distribution of dipoles in the channel. We produced 200 irregular devices with sufficient randomness, 50% uniformity, and a 45.5% inter‐HD, which provided non‐reproducible uniqueness. They measured the peak shift in the G band of a 100 × 100 array of graphene with irregular SAMs using non‐destructive Raman spectroscopy. The security key generated from the data extracted from 10 000 points measured by Raman spectroscopy revealed 50.02% uniformity, a 46.15% inter‐HD, and a defense rate of 10.33% against machine learning (ML) attacks.Several studies have proposed that emerging PUFs incorporate variations in current and other physical signals as a means of differentiation.16 In 2Figure  The dipole moment of SAMs can act as a chemical dopant. This study examined the doping effect of mixing ODTS and FOTS at the same concentration. The channel material was graphene, a 2D material capable of chemical doping. A graphene transistor was fabricated to extract the Dirac point and analyze the doping effects. Figure 2 wafer that bonds well with silane groups because the head groups of the SAM materials used are all silane groups, as shown in Figure  Graphene was wet‐transferred onto the SAM, and Au was chosen as an electrode because a previous study reported that using Au as the electrode strengthens the p‐type behavior of graphene. Au was deposited onto the device by thermal evaporation. A bottom‐gate top‐contact graphene transistor was fabricated using a series of processes, as shown in Figure 2/Si substrates. To separate the effects of mechanical strain and charge doping in graphene, we employed the method previously reported by Lee et al. The distributions of doping concentration and mechanical strain are summarized in Table  The Dirac points of ODTS‐, FOTS‐, and MAL‐inserted graphene (IG) were compared to analyze the doping effect. The transfer curve was measured, as shown in Figure Each transistor in the MAL‐IG device exhibits a distinct Dirac point, suggesting that the doping states and levels vary because of the random distribution of ODTS and FOTS. This randomness is an inherent characteristic of the physical entity and a result of the semiconductor manufacturing process during spin coating. This feature suggests that MAL‐IG can be used as a PUF device, and its security properties can be assessed. The devices were arranged in a 12 × 12 grid, and the output of each device was converted into a binary digital value to produce a hardware‐based security system. The current value of each device was used as the reference for each binary bit. The current data was divided into 0 and 1 based on the median current value to produce the dichotomous data for each bit.Figure The median value of the current was determined to establish a standard state. The currents were obtained by sweeping the current–voltage characteristics between two Au electrodes from −100 mV to 100 mV, as shown in The security key was obtained by matching the current generated by each device in the 12 × 12 array to its actual position. The current distribution map, shown in Figure ri is the number of a bit ‘0′, and n is the string length of the security key.ri and rj indicate the responses of the security key ‘i’ and “j”, respectively, in response to a given challenge, and k and n are the number of security keys and the string length of the security key, respectively. Uniformity is a parameter representing the ratio of states 0 to 1. A uniformity of 50% indicates the high randomness of the response bit. The pattern is monotonic and predictable when the states are clustered on 0 or 1. That is, a uniformity of 50% is ideal as a security device. Inter‐HD represents the difference in pattern between the units when the security key is divided into units and analyzed. For example, the inter‐HD is 0% if the pattern arrangements of the two units match and is 100% if they are opposite. The patterns were normalized and predicted when inter‐HD approaches 0% or 100%. Hence, a 50% inter‐HD is ideal as a security device. The security key based on ODTS‐IG was evaluated. This key could not be used as a security device because it consisted only of state 0 as shown in Figure We first evaluated two parameters to assess the security key obtained: uniformity and inter‐HD. The method for calculating these two parameters is as follows:5 seconds, indicating strong ambient stability. Second, even at a high temperature of 100°C, both ODTS‐IG and FOTS‐IG showed no significant degradation, demonstrating their stability under elevated thermal conditions. Lastly, moisture exposure had minimal impact on the electrical properties of ODTS‐IG and FOTS‐IG, as evidenced by similar I–V curves in both ambient air and high humidity (80% relative humidity). The stability of graphene on ODTS can be attributed to the hydrophobic surface  with 100 input neurons, 200 neurons in the first hidden layer, 200 neurons in the second hidden layer, and 50 output neurons. The MLP was trained using a 100‐bit challenge and 100‐bit response, which were used as features and labels, respectively. A sigmoid activation function was used to enhance the accuracy of the MLP, and the synapse weights were initialized using a normal distribution with a mean of 0 and a standard deviation of the reciprocal square root of the number of nodes. The MLP was trained using 10 000 challenge‐response pairs, and the ML attack test was performed by varying the number of epochs. Furthermore, to compare the performance of our PUF with other graphene‐based PUFs, we examined their respective mechanisms, operational voltages, and machine‐learning prediction accuracies. Notably, our study achieved the lowest prediction ratio of 10.33%, as presented in Table The ML attack showed that it was very difficult to model the MAL‐IGD PUF with an attack rate of only 10.33% for the partially randomly doped graphene device. Hence, the MAL‐IGD PUF is highly resistant to ML attacks, as shown in Table 40 Fur33 functional group. MAL‐IGD, in which two SAMs coexist, showed a moderate shift because of the dipole moment of each SAM. The strong PUF exhibited randomness with 50.02% uniformity and 46.15% inter‐HD, with each state distributed unpredictably and non‐uniformly. The ML attack accuracy of the strong PUF resulted in a high defense rate of 10.33%. A hardware‐based high‐security system could be implemented using this approach. However, the readout speed of our Raman‐based PUF is not enough to meet the requirement for registration, thus further work is being conducted to improve the readout speed using the advanced Raman systems. As this study proposed a dual‐mode security system using irregular electrical characteristics and Raman spectroscopy to modulate the Fermi level of doped graphene, it is believed that this new approach to dual‐mode security system manufacturing with make a valuable contribution to security systems.This study achieved non‐uniform electrical characteristics by doping graphene with two MALs with different functional groups to modulate the Fermi level. The device was fabricated using a MAL, intentionally inducing an irregular dipole distribution to produce dual‐mode security keys. The doping state was determined by the self‐variation of MAL, and an unpredictable key with 50% uniformity and 45.5% inter‐HD performance was achieved by measuring the electrical characteristics of a 12 × 12 array. Raman spectroscopy was used to measure the singularity of the device at 100 × 100 points, and the G band peak of graphene was used to distinguish the effect of the dipole. Single ODTS‐IGD was similar to intrinsic graphene, and the single FOTS‐IGD had a larger G band shift because of the p‐doping effect of the CF systems.41 As 43(CH2)17SiCl3) (ODTS) (≥90%), 1H,1H,2H,2H‐perfluorodecyltriethoxysilane (C14H19F13O3Si) (FOTS) (98%), and chlorobenzene (C6H5Cl) (≥99.5%) were supplied by Sigma–Aldrich (USA). SiO2‐coated Si substrate (4‐inch) was used as the substrate. Au was used as the electrodes.Octadecyltrichlorosilane  to transfer the CVD‐grown graphene onto SAM‐treated Si substrates, as reported elsewhere.Monolayer graphene was deposited by low‐pressure chemical vapor deposition. Copper foil was heated to 1030 °C under flowing Hlsewhere.27The self‐assembled monolayer (SAM) materials used in this study were ODTS (≥90%) and FOTS (98%). The SAM materials were dissolved in chlorobenzene (≥99.5%) (Sigma–Aldrich).2 layer. The substrates were cleaned sequentially with ethanol and isopropyl alcohol (IPA) in bath sonication and dried using blowing N2. The substrate was ozone treated to form an o─bond. The solutions were synthesized by dissolving SAM materials  in chlorobenzene and spin‐coated at 3 000 rpm for 10 s using 6.48 mL of solution on a 4‐inch wafer. The device was annealed on a hotplate at 120 °C for 20 min to align the SAM materials. A 100 nm Au layer was deposited by thermal evaporation.The material was coated on a four‐inch wafer with a 300 nm SiORaman spectroscopy  was conducted to investigate the SAM‐inserted graphene film. The transfer curve was measured using a DC source meter (Keithley 2450), and the device property was measured using a Keithley 4200A device to measure the electrical characteristics of the SAM‐inserted graphene device.The authors declare no conflict of interest.Supporting InformationClick here for additional data file.


Injection drug use (IDU) increases risk for myriad health complications, including infections , tissue injury, and overdose. Despite the prevalence of IDU and associated harms, tools to assess risk and provide harm reduction counseling are uncommon. We sought to create and refine a tool for assessment of IDU practices, using the input of experienced clinicians and people with lived experience of IDU.The INJECT-RESPECT tool was evaluated and refined in 3 phases, each seeking input from different groups of stakeholders. IDU, injection drug use; PWID, people who inject drugs.INJECT-RESPECT version 1 based on existing literature and their experience. In Phase 1, 12 attending physicians in 6 specialties provided feedback on INJECT-RESPECT version 1, which was incorporated into version 2. In Phase 2, 20 people who were hospitalized with infectious complications of IDU were interviewed about INJECT-RESPECT version 2 and asked (1) Were you asked this question? and (2) Is this important to ask? Responses were recorded as “Yes”/“No”. In Phase 3, a focus group was conducted with 7 people with lived experience of IDU, focused on healthcare providers’ approach to discussing IDU practices.A 3-part process of feedback and refinement was used . The authors developed p < 0.001; Figure 2). In the focus group, important themes were shame, stigma, and trauma .Of the 20 hospitalized participants in Phase 2, 45% were women and the median age was 37 years (range 24-48 years). Only 7 questions (11%) were asked of most respondents, yet 29 questions (44%) were classified as important by ≥75% of respondents (Table 1). Importance was correlated with whether the question was asked  who were asked the question and who thought it was important are reported. The proportions are colored on a spectrum from red (0.0) to yellow (0.5) to green (1.0).The importance of the INJECT-RESPECT questions—as assessed by hospitalized people who inject drugs in Phase 2—was positively correlated with whether the participants had been asked the questions. People admitted with acute complications of IDU were not asked questions about their IDU practices that they and surveyed clinicians deemed important. Our results suggest more important questions are asked more frequently, but many important questions are rarely asked. One third of questions were rated as not important by ≥50% of respondents; these questions will be refined or removed. The focus group yielded important considerations for discussing IDU. The feedback from Phases 1, 2, and 3 will be used to further improve the INJECT-RESPECT tool. Future efforts will focus on implementing the tool with clinicians and evaluating its real-world use .INJECT-RESPECT will be refined based on the results of this study. It will be disseminated to clinicians through the EMR, which will also allow evaluation of how it is used. EMR, electronic medical record.All Authors: No reported disclosures


Idiopathic pulmonary fibrosis (IPF) has attracted considerable attention worldwide and is challenging to diagnose. Cuproptosis is a new form of cell death that seems to be associated with various diseases. However, whether cuproptosis-related genes (CRGs) play a role in regulating IPF disease is unknown. This study aims to analyze the effect of CRGs on the progression of IPF and identify possible biomarkers.Based on the GSE38958 dataset, we systematically evaluated the differentially expressed CRGs and immune characteristics of IPF disease. We then explored the cuproptosis-related molecular clusters, the related immune cell infiltration, and the biological characteristics analysis. Subsequently, a weighted gene co-expression network analysis (WGCNA) was performed to identify cluster-specific differentially expressed genes. Lastly, the eXtreme Gradient Boosting (XGB) machine-learning model was chosen for the analysis of prediction and external datasets validated the predictive efficiency.Nine differentially expressed CRGs were identified between healthy and IPF patients. IPF patients showed higher monocytes and monophages M0 infiltration and lower naive B cells and memory resting T CD4 cells infiltration than healthy individuals. A positive relationship was found between activated dendritic cells and CRGs of LIPT1, LIAS, GLS, and DBT. We also identified cuproptosis subtypes in IPF patients. Go and KEGG pathways analysis demonstrated that cluster-specific differentially expressed genes in Cluster 2 were closely related to monocyte aggregation, ubiquitin ligase complex, and ubiquitin-mediated proteolysis, among others. We also constructed an XGB machine model to diagnose IPF, presenting the best performance with a relatively lower residual and higher area under the curve (AUC= 0.700) and validated by external validation datasets . The analysis of the nomogram model demonstrated that XKR6, MLLT3, CD40LG, and HK3 might be used to diagnose IPF disease. Further analysis revealed that CD40LG was significantly associated with IPF.Our study systematically illustrated the complicated relationship between cuproptosis and IPF disease, and constructed an effective model for the diagnosis of IPF disease patients. IPF hasCuproptosis, a novel unique non-apoptotic programmed cell death, targets and leads the aggregation of fatty acylated components and the loss of Fe-S cluster-containing proteins, causing proteotoxic stress and cell death . At pres22.1www.ncbi.nlm.nih.gov/geo). Database GSE38958 (platform GPL5175), which includes 45 healthy and 70 IPF blood samples, was selected to analyze the relationship between CRGs and IPF and construct the machine learning model to diagnose IPF. Datasets GSE28042 (GPL6480 platform)  and GSE33566 (GPL6480)  were used for the validation of the IPF prediction model and following analysis. The three datasets were processed with limma package and normalized using the normalizeBetweenArrays method.Three datasets  were downloaded from the database of the website GEO  and circlize  and a test set . Interpretive analysis of the 4 models was performed by the DALEX package (http://www.genemania.org). R package rms was used to build a nomogram model, and the predictive power of the nomogram model was tested by the calibration curve and decision curve analysis (DCA).Four machine-learning models: Support Vector Machines (SVM), XGB, generalized linear model (GLM), and Random Forest (RF) models were built by the R package caret, and all the models worked with default parameters and assessed  package , and the2.8P < 0.05 represented a significant correlation and R represented a correlation coefficient.To determine the relationship between key genes and clinical indicators associated with IPF, including age, diffusing capacity of the lung for carbon monoxide (DLCO), and FVC, the spearman correlation analysis was performed to explore the correlations. R packages ggplot2, ggpubr (version 0.4.0), and ggExtra (version 0.10.0) were used to draw the scatter plot. 33.1We systematically analyzed the differentially expressed curproptosis genes between healthy and IPF patients using the GSE38958 database. There were 9 CRGs with significant differences in IPF patients including, NLRP3, ATP7B, ATP7A, SLC31A1, FDX1, LIAS, LIPT1, DLAT, GLS, CDKN2A, and DBT. Among them, 3 CRGs in IPF samples were higher than that in healthy subjects, including NLRP3, SLC31A1, and CDKN2A, while others exhibited a lower expression, especially GLS . Moreover, the CDF curves fluctuated within a minimum range at a consensus index of 0.2 to 0.8  , except HK3   was compared and selected based on the high predictive efficacy in the testing cohort. Results showed that the XGB-based machine-learning model had the best performance in predicting the IPF. We then selected 4 critical genes  to construct a 4-gene-based XGBand nomogram models. The constructed 4-gene-based XGB model could accurately predict IPF, validated in other external datasets (AUC = 0.700), which provides new insights into the diagnosis of IPF. The nomogram was established for the diagnosis of IPF, exhibiting effective predictive efficacy with possible clinical application. Next, we analyzed the correlations between the clinical characteristics of IPF and 4 critical genes. DLCO was used to evaluate the diffusing capacity of the lung for carbon monoxide and aiding in IPF diagnosis. Our result revealed that only DLCO strongly correlated with the selected 4 genes. Additionally, an increasing number of studies have confirmed that TGF-β1 is a fundamental pathological mechanism, which contributes to the progression of IPF by promoting the transformation of fibroblast into myofibroblast, epithelial cells into mesenchymal cells, the production of collagen, filamentous actin, and α-SMA . TherefoWe also constructed a gene-gene network and performed Go and KEGG analyses of similar genes related to the 4 critical genes. GO analysis of CD40LG showed that tumor necrosis and NF-κB were primarily enriched. Many studies have demonstrated that the tumor necrosis factor is primarily produced by macrophages and monocytes linked to a number of pulmonary inflammatory diseases, including IPF , 39. It This study has some limitations. Firstly, more IPF samples are needed to demonstrate the correlation between CRGs and IPF disease or immune cells infiltration. Secondly, it is necessary to do more experiments to clarify the regulation and mechanism of the 4 critical genes identified and CRGs in the progression of IPF. Lastly, more clinical features are required to confirm the validity of the predictive model.5In conclusion, our study clarified that CRGs might play a role in IPF progression. We also showed the correlation between CRGs and immune cell infiltration, and elucidated the significance of immune heterogeneity in IPF patients with distinct cuproptosis clusters. The prognostic model based on the 4 critical genes may allow a new way to predict the prognosis of IPF.The original contributions presented in the study are included in the article/supplementary material. Further inquiries can be directed to the corresponding authors.XS and ZP wrote and revised the manuscript. YZ, WC and JD collected the original data and visualized the final results. XS provided the funding. TC and RL supervised the study. The final manuscript was read and approved by all authors. All authors contributed to the article and approved the submitted version.


To our knowledge, this provides the first observation of photoresist induced photocurrent in such systems. Without the influence of the photoresist the device can respond to infrared light up to 980 nm wavelength in vacuum in a cryostat, in which the photocurrent is positive and photoconduction effect is believed to dominate the photocurrent. Finally, the adsorption effect is modeled using a first-principle method to give a picture of charge transfer and orbital contribution in the interaction of phosphorus atoms and single-layer graphene.Black phosphorus quantum dots (BPQDs) are synthesized and combined with graphene sheet. The fabricated BPQDs/graphene devices are capable of detecting visible and near infrared radiation. The adsorption effect of BPQDs in graphene is clarified by the relationship of the photocurrent and the shift of the Dirac point with different substrate. The Dirac point moves toward a neutral point under illumination with both SiO Black phosphorus (BP) is a direct bandgap semiconductor with a bandgap ranging from 0.3 eV for bulk material to 1.5 eV for a monolayer. The geometry dependent energy band gap and high absorption make BP important in optoelectronic detection, especially in near-infrared frequencies . The banGraphene is a kind of two-dimensional material with good conductivity, but the low absorption coefficient limits its application in photodetectors. Some methods can improve the performance of photodetectors, such as plasma modification, lead substitution, heterostructure formation and thickness control of the active material –10. AmonBPQD show saturable absorption characteristic and this can be exploited in laser mode locking . The pho3N4/Si substrate is adopted and processed with bufferred oxide etch (BOE) to achieve a nearly intrinsic graphene layer. Expectedly, the Dirac point shifts to the negative side after the BPQDs are applied. Photoresist induced photocurrent on the surface of graphene is first reported in this work. A new structure is designed to remove the effect of photoresist on graphene leaving only the effect of BPQDs in the experiment. Photocurrent rises rapidly when the device operates under vacuum conditions in a cryostat. The mechanism for photosensitivity in the cryostat is believed to be photoconductivity, and totally different from the mechanism at room temperature, where unintentional doping of graphene is compensatedby BPQDs. An ab initio simulation of the BPQDs/graphene system is carried out to present the energy band unfolding, charge transfer and orbital contribution. The phosphorous atom acts as an electron donor and the net charge transfer is − 0.294 e.In this work, a comprehensive investigation of the adsorption and related doping effect of BPQDs on graphene is presented. Phototransistors based on graphene or BPQDs/graphene are fabricated. The doping effect is confirmed by manipulating the Dirac point both in dark mode and under illumination using different substrates. To fully identify the n-doping effect of BPQDs, an intrinsic graphene is needed. A SiBPQD are fabricated by means of liquid exfoliation introduced by Zhang’s group . The rat2 layer utilizing thermal oxidation or a 50 nm Si3N4 layer utilizing conventional wet method [The structure of the phototransistor is shown in the inset of Fig. t method . Then a The synthesized BPQDs in NMP solvent is shown in the inset of Fig. A comparison of drain current entclass1pt{minimaentclass1pt{minimaL are fabricated. For L ranging from 20 to 600 μm, the dependence of responsivity on channel length is shown in Fig. n and p denote electron and hole concentration respectively. The responsivity can be extracted the current–time curve. In Fig. entclass1pt{minimais small :\documen2/Si and Si3N4/Si layer shows a natural p-doping due to the inevitable absorption of oxygen and water. A minimum conductivity is found around 60 V for SiO2/Si substrate, which is known as the Dirac point Fermi energy shift relative to the Dirac point can be calculated from the gate voltage at the Dirac point VG is the gate voltage, and 2, with 2, 2 is 3.9 and the thickness is 285 nm as determined by ellipsometry measurement. As a result, the Fermi energy shifts To find the origin of the photocurrent in the BPQDs/graphene system, transfer characteristic curve is measured and illustrated in Fig. t}VDirac :\documengiven by :\documenThe mobility is estimated to be ~With the BPQDs on the graphene sheet, the Dirac point shift in the direction of negative axis. Accordingly, the graphene tends to be intrinsic. This shift can be understood if the adsorption of phosphorous atoms is taken into account. When graphene adsorbs oxygen or water, weak intermolecular bonds are formed between carbon atoms in graphene and oxygen or hydrogen atoms in the adsorbed molecule. Oxygen atoms possess higher attraction to the electron cloud, thus bare ion cores of carbon atoms are exposed, which is a necessary condition for p-doping. Phosphorous atoms have weaker electronegativity, with an electron affinity  .2, graphene is unintentionally doped and this complicates the situation and makes it difficult to determine the additional doping effect of BPQDs. BOE, rinsing or substituting the dielectric material can reduce the doping concentration of graphene [3N4 is used to serve as an insulating substrate and electrical measurement is again performed. As shown in Fig. 3N4/Si. If the graphene is dealt with BOE, the Dirac point moves to zero. If the graphene on Si3N4/Si is drop casted with BPQDs, the adhesion of phosphorus atoms causes the 2 substrate, when laser radiation of 405 nm wavelength incidents to the device and BPQDs produces excess electrons and holes, the excess carriers transfer to graphene due to diffusion. These carriers balance out the p-doping effect of oxygen and water to graphene. The The work function of black phosphorous is difficult to determine because of various doping conditions and work function pinning effect. Due to the hydrophily of the insulating substrate material SiOgraphene . Si3N4 i2 substrate, contact between BPQDs and graphene results in diffusion of carriers toward each other. The adsorbed oxygen and water are partly replaced by the BPQDs, relieving the p-doping of graphene. The density difference of holes and electrons in BPQDs is still less than that in graphene, thus holes tend to transfer from graphene to BPQDs and a built-in electric field pointing toward graphene is formed. Energy band then bend upward toward side. Excess carriers induced by laser radiation transfer into graphene, making the concentration of electrons and holes to be more balanced, thus leading to the left-hand movement of the Dirac point as shown in Fig. The energy band of the BPQDs/graphene system under illumination can be modeled using the conventional energy band theory, in a similar way to modelling the PbS quantum dots/graphene hybrid system , as show2/Si susbstrate, photolithography is performed using a negative tone resist NR9-3000PY. To eliminate the effect of photoresist and to verify our conclusion about the adsorption induced photocurrent, a metal mask is utilized to make the electrodes. Graphene outside of the channel is cut off using a sharp probe on the probe station. By using this method, although the edge of the channel cannot be finely controlled, fundamental mechanisms can be explored easily. The device made by using metal mask is measured in ambient air and vacuum respectively and the result is shown in Fig. In the process of making BPQDs/graphene on SiOPhotoresist induced photocurrent is first observed to our knowledge. A series of incident laser radiation with different power densities and wavelengths in the visible and infrared range is applied on the graphene exposed to NR9-3000PY photoresist and the photocurrent is shown in Fig. ab-initio simulation software OpenMx. Bulk BP possesses an orthorhombic lattice [Detailed explanation of charge transfer in the system of adsorbed phosphorus atom or BPQDs and graphene is given by modelling using the first-principle method. BPQDs and graphene are modeled by using an  lattice –26 and a lattice . The obt lattice . Quantum lattice . The band. Due to the symmetry of graphene, it is convenient to find three possible horizontal positions for the phosphorous atom [The result of phosphorus atoms adsorbed on graphene is given in Fig. ous atom –32. ThesTo investigate the details of the charge transfer contribution of phosphorus to graphene, we plot the unfolded energy band diagram of a phosphorus atom doping grapheneand the result is presented in Fig. 2, the total current at zero gate voltage decreases and the Dirac point of graphene moves toward zero with the laser radiation, which means BPQDs anti-dope graphene. The photoresist can play a role in the fast response of light. When the device is in the low temperature in vacuum, phosphorus offers excess carriers and the photocurrent is positive. The BPQDs/graphene device can work in the visible to near-infrared wavelengths at low temperatures. The adsorption effect of BPQDs on graphene is modeled using a first-principle method. The net charge transfer for a phosphorus atom on the graphene is found to be − 0.294 e for the most stable state. A picture of charge transfer and orbital contribution in the interacted BPQDs and single-layer graphene system is also given.In the BPQDs/graphene device, the introducing of quantum dots reduces the unintentional p-doping of graphene and accounts for the large negative photocurrent. In the ambient air, for the device with BPQDs/graphene on SiO


Plants were more sensitive to silver at high initial frond densities. Growth rates based on frond number and area were lower for plants at 40 and 80 initial frond density in both silver treatments. AgNPs had no effect on frond number, biomass, and frond area at 20 initial frond density. However, AgNO3 plants had lower biomass than control and AgNP plants at 20 initial frond density. Competition and crowding at high frond densities resulted in reduced growth when silver was present, therefore plant density and crowding effects should be considered in toxicity studies.Silver nanoparticles (AgNPs) are the most popular engineered nanomaterials in consumer products due to their antimicrobial properties. They enter aquatic ecosystems via insufficient purified wastewaters from manufacturers or consumers. AgNPs inhibit growth of aquatic plants, including duckweeds. Growth media nutrient concentration and initial duckweed frond density can affect growth. However, it is not well understood how frond density affects nanoparticle toxicity. We investigated the toxicity of 500 µg/L AgNPs and AgNO Silver nanoparticles (AgNPs) are popular nanomaterials in consumer products due to their antibacterial properties and multifunctional applications ,2. AgNPsDuckweeds are ideal for studies on nanoparticle toxicity because of their small size, fast growth rates, ease of harvest, and ability to reproduce vegetatively . These cLemna sp., with at least one other variable such as frond area, dry weight, or fresh weight [Inhibition test guidelines recommended frond number as the primary measurement variable for assessing toxicity of substances to h weight . Table 2L. minor [Spirodela polyrrhiza [Lemna minor growth rates at low (25% cover) and high (100% cover) compared to moderate frond densities (50% cover), which they attributed to inverse density dependence and competition. High frond density was also associated with greater toxicity in plants. Dry weight decreased with increasing plant density in controls, and more so when plants were exposed to 20 mg/L Ni [L. minor and S. polyrrhiza resulted in decreased growth when exposed to the pesticide dimethomorph [While several studies relied on frond number as a primary growth measurement, none addressed the effects of nanoparticle toxicity on initial frond density. Differences in toxicity effects across studies could be attributed to different initial plant densities since growth rates and biomass are dependent on plant density. In nutrient removal studies, higher initial frond densities resulted in decreased growth rates in L. minor ,34 and dlyrrhiza . In contlyrrhiza  reported mg/L Ni . Similarthomorph . Färber thomorph ,40 indicthomorph ,40. Ther3 of L. minor frond number, frond area, and dry weight. Most other works only evaluated frond number and/or dry weight. Total frond area is a good assessment of growth and biomass production and can be measured without biomass loss or injury to the plants. We assessed the effects on Lemna minor growth at three frond densities . Most studies only assessed toxicity on 21 or fewer fronds, and none have investigated the influence of frond density. We used AgNO3 to compare effects of AgNPs to ionic silver. AgNO3 readily provides dissolved silver ions [3 had greater toxicity on duckweeds than AgNPs [3 would have decreased growth at higher initial frond densities, and AgNO3 would have greater inhibition overall. Frond density is not static, and laboratory experiments do not accurately reflect densities observed in the environment, so our goal was to assess the influence of frond density on silver toxicity.We investigated how initial frond densities influence toxicity of AgNPs and AgNOver ions  and is uver ions ,26,27. Ian AgNPs ,27. We hDilution of the Hoagland solution decreased growth. Plants in 2.5% Hoagland solution produced 1.5 times fewer fronds compared to 25% Hoagland solution, while plants in more diluted Hoagland solutions (0.25–1%) produced 2.4–4 times fewer fronds. There was no difference in dry weight and frond area between plants in 2.5% Hoagland solution and 25% Hoagland solution . The 2.5Dilution of the Hoagland solution resulted in greater AgNP stability. Zeta potential values of 2.5% Hoagland solution indicated stability (average ± standard deviation +25 ± 2 mV), while 25% Hoagland solution was unstable (+12 ± 1 mV). Plants exposed to 500 µg/L AgNPs had greater dry weight than plants exposed to 1000 µg/L, and had lower dry weight and frond area than plants exposed to no AgNPs . The hig3 produced fewer fronds than the 80–control, while plants in the 80–AgNP produced similar frond numbers as both the 80–control and 80–AgNO3  produced similar frond numbers among silver treatments and the control. Growth rates according to frond number decreased with increasing frond density regardless of silver treatment  in other studies  and growth rates are dependent on initial frond density regardless of silver exposure. At higher frond densities duckweeds became crowded in our study. Crowding results in plants being pushed together, leading to an increase in ethylene production, which in turn inhibits growth [Lemna minor also experiences frond detachment and decreased growth rates in response to crowding [Overall, our study showed that s growth ,40. Lemncrowding . Crowdincrowding . This mecrowding ,36. GrowPlants exposed to silver at higher initial frond densities had lower dry weight and total frond area than the controls in the current study. Higher initial frond densities also resulted in increased inhibition of growth in the presence of silver. These findings were consistent with another study that reported increased inhibition due to Ni exposure with increasing duckweed density . The inhL. minor and S. polyrrhiza densities resulted in lower growth rates in pesticide treatments than in controls [L. minor growth. Growth rates of our controls were consistent with other studies that reported decreased growth rates with increased initial duckweed density in the absence of a toxicant  [In the current study, growth rates (based on frond number and area) showed that silver had no effect when compared to the controls at the same initial frond densities. This was not consistent with findings of another study that reported increased initial controls . Our groontrols) ,34,35. Tontrols) ,38.L. minor experienced reduced frond numbers after 7–14 days of exposure to AgNPs of similar size as in our study, but at 25–100 times lower concentrations (5–20 μg/L) than the AgNP concentrations we tested [AgNPs had no effect on frond number in our study, which coincided with Pereira et al. , who repe tested ,23,24. T3 decreased frond number in the highest initial frond densities while AgNPs had no effect. These findings are consistent with other studies that reported greater toxicity of AgNO3 than AgNPs on duckweeds [3 resulted in decreased frond number, but at concentrations 4–100 times lower (5–120 µg/L) than the concentration in our study [L. minor was exposed to 1000 µg/L AgNO3. Ag+ ions are more readily available for plant uptake in AgNO3 than in AgNP treatments, which likely explains the greater toxicity of AgNO3 [AgNOuckweeds ,26,27,43ur study ,25. Souzof AgNO3 .Our findings on AgNP effects on dry weight did not correspond with other studies. Some studies reported decreased dry weights, but at concentrations 50 times lower (10 µg/L)  and 16 t3 had greater toxic effects on plants than AgNPs. Jiang et al. [Spirodela polyrrhiza when exposed to AgNO3 than those in the control and AgNP treatment. The sensitivity to AgNO3 at low and high initial frond densities also highlighted the greater toxicity of AgNO3 than AgNPs. At low densities, the greater toxic effect could be due to inverse density dependence [Similar to other studies, our dry weight findings emphasized that AgNOg et al.  reportedpendence , while apendence ,40.L. punctata frond area at similar AgNP concentrations (1.3 times higher) to our study. They reported that frond area decreased in L. punctata at AgNP concentrations 21 times higher than in our study. This could be due to L. punctata having greater AgNP tolerance than L. minor. We observed reduced frond area, but not frond number for 80–AgNP plants, indicating that the toxic effect was due to decreased frond size. Again, these observations indicate that the inhibitory effects of overcrowding and competition possibly exacerbated AgNP toxicity at high initial frond densities. To further support our reasoning of inhibition due to overcrowding, higher densities (40 and 80) had decreased frond area when exposed to AgNO3.Only one other study assessed the effects of AgNPs on frond area in duckweeds. Lalau et al.  reported3 plants produced more fronds than the 20–control plants, possibly because of the additional supply of nitrates from AgNO3.Both forms of silver had no effect on growth rates based on frond number and area. Growth rates were only dependent on initial frond density, which coincides with other studies that reported that growth rates depended on initial plant density ,34,35. FSEM images provided some insight into potential mechanisms of inhibition at high frond densities. SEM images of the upper surface of the sample fronds from the 80–AgNP contrasted with findings reported by Lalau et al. . Their cLemna initial frond densities influence growth and their responses to silver, therefore initial and varying frond densities must be factored into toxicity tests and phytoremediation studies.Similar to our findings, several studies reported AgNPs reduced duckweed frond numbers, dry weight (biomass), and frond area ,20,23,24Lemna minor plants from among Wolffia brasiliensis and Spirodela polyrrhiza growing in Valley Water Mill Pond, a spring impoundment in Springfield, Missouri. We identified L. minor using identification keys of Yatskievych [M, 0.5 KH2PO4, 1.5 KNO3, 0.5 MgSO4•7H2O, 0.25 NaCl, and in µM, 11.5 H3BO3, 2.3 MnCl2, 0.19 ZnSO4, 0.08 CuS4, 0.026 H2MoO4, and 22.4 Fe-Na EDTA (as ferric-sodium EDTA complex) [M Ca(NO3)2 and 2 mM HEPES. We used plants triple-rinsed with deionized water from this culture to conduct three experiments in unsterile conditions. In experiment 1, we tested effects of diluting Hoagland solution on growth. In experiment 2, we tested effects of different AgNP concentrations on growth. In experiment 3, we measured effects of AgNPs and AgNO3 on L. minor at different initial frond densities. All experiments were carried out in 170 mL acid-washed plastic cups on shelves with LED lighting in our laboratory .We collected skievych  and Landskievych . Some deskievych ,48. Vouccomplex) . After aL. minor in 170 mL plastic cups (40 fronds each) of 120 mL of 25%, 2.5%, 1%, 0.5%, 0.3%, and 0.25% Hoagland solution (5 replicates per dilution group). Previous research recommended diluting nutrient solutions at pH 5.5 since AgNPs aggregate in standard nutrient solutions ,24. DiluL. minor, we conducted an AgNP range-finding experiment . To assess nanoparticle stability, we measured the Zeta potential of 2.5% and 25% Hoagland solutions with 20 mg/L AgNPs using the Smoluchoski method on a NanoBrook Omini by Brookhaven Instruments Corporation, Holtsville, NY, USA. We transferred L. minor (40 fronds each) from our culture to 30 plastic cups containing 120 mL 2.5% Hoagland solution. Plants acclimatized to the solution for four days before addition of AgNPs. Each cup received AgNPs at concentrations of 0, 60, 125, 250, 500, or 1000 µg/L (five replicates per treatment group). After 14 days, we determined frond number, frond area, and dry weight as described above. Based on this experiment, we used 500 µg/L AgNPs or AgNO3 for experiment 3 because, at this concentration, AgNPs had moderate inhibition and sublethal effects on growth. Lower AgNP concentrations were either similar to controls or had little to no inhibition.To determine the lowest AgNP concentration that caused sub-lethal effects on 2) of 120 mL nutrient solution. This experiment used three initial frond densities . Lemna minor were placed in plastic cups , each containing 120 mL 2.5% Hoagland solution. After four days of acclimatization, 500 µg/L AgNPs was added to five cups of each frond density group  and 500 µg/L of AgNO3 to another five cups of each group . The remaining five cups from each frond density group received no silver and served as the controls . Plants grew for two weeks, and small volumes (<25 mL) of 2.5% Hoagland solution were added to cups twice a week to account for evaporation. After 14 days, we determined frond number, frond area, and dry weight as described above.Frond density refers to number of fronds per plastic cup  .(1)μi−jrI) for each treatment group using Equation (2) [C = mean growth rate of controlμT = mean growth rate of treatmentμWe calculated percent inhibition of growth rate (tion (2) .(2)%Ir=® 19. For experiments 1 and 2, we analyzed for differences in frond number, frond area, and dry weight between Hoagland solutions or AgNPs. We analyzed for differences in frond number, frond area, dry weight, and growth rate among AgNPs and AgNO3 treatments and the control for each initial frond density group. Prior to statistical analyses, we transformed data not meeting assumptions of ANOVA using Johnson transformation to achieve homogeneity of variance and normal distributions.Significance of differences was determined by One–Way or Two–Way ANOVA (α = 0.05) followed by Tukey multiple comparisons tests (α = 0.05) in Minitab3 on L. minor growth at different initial plant densities . Greater inhibition and decreased biomass (dry weight) at higher frond densities (40 and 80) in silver treatments than in controls indicated that increasing frond density exacerbated silver toxicity. Decreased growth rates with increasing initial frond density, regardless of the presence of silver, emphasized that the effects of crowding played a major role in growth inhibition. Future work should assess the influence of different plant densities on the toxicity of nanoparticles and other contaminants, since overcrowding could play a role in the toxicity effect. In addition, since both forms of silver affected frond number, dry weight, and frond area differently, it is important to assess the toxic effects of contaminants on multiple growth parameters in toxicity studies.We evaluated the toxic effects of AgNPs and AgNO


D/IG ratio decreases for graphene grown on OH-terminated surfaces. Furthermore, two different regimes related to the nature of graphene defects were identified and, depending on the sapphire terminated surface, are bound either to vacancy or boundary-like defects. Finally, studying the density of defects and the crystallite area, as well as their relationship with the sapphire surface termination, paves the way for increasing the crystallinity of the synthesized graphene.In this work, we study the influence of the different surface terminations of c-plane sapphire substrates on the synthesis of graphene via plasma-enhanced chemical vapor deposition. The different terminations of the sapphire surface are controlled by a plasma process. A design of experiments procedure was carried out to evaluate the major effects governing the plasma process of four different parameters: i.e., discharge power, time, pressure and gas employed. In the characterization of the substrate, two sapphire surface terminations were identified and characterized by means of contact angle measurements, being a hydrophilic (hydrophobic) surface and the fingerprint of an Al- (OH-) terminated surface, respectively. The defects within the synthesized graphene were analyzed by Raman spectroscopy. Notably, we found that the I Focus4 ratio) .The properties of sapphire have been extensively studied for its use as a substrate in the synthesis of III-V semiconductors. There are different surface reconstructions and three stable terminations for c-plane sapphire, which strongly influence the properties of its surface . For exaConsidering the case of graphene synthesis on sapphire, several works report different nucleation behaviors depending on the crystal orientation or surface reconstruction of sapphire . For exa2 thermal etching at 1180 °C [2 on sapphire [On the other hand, Mishra et al. reported a significant increase in the measured mobility of graphene synthesized by CVD on a c-plane sapphire, including an Hsapphire . Howeversapphire ,28. The 2 plasma for 600 s at 400 W and 1.5 mbar . Afterward, the following 2-solvent method was employed: to remove any particles, they were rinsed below running deionized water for 30 s, blown dry in N2 and immersed in acetone for 300 s at room temperature (RT). Finally, the sapphire substrates were sonicated in isopropyl alcohol (IPA) for 300 s at RT, blown dry with N2 and introduced into the PECVD system .Pristine 4 inch c-plane sapphire wafers (PHOTONEXPORT Epi-Ready), covered with a protective PMMA resist to avoid splinters, were diced in 10 × 10 mm squares. The diced sapphire substrates were subjected to the following cleaning procedure: First, the PMMA resist was removed with an O8 orthogonal array (4−1 [2 atomic force microscopy (AFM) measurements  in tapping mode. Silicon AFM probes  coated in the backside with reflective aluminum were employed. The AFM measurements were then analyzed using open-source Gwyiddion software.First, the top and bottom heaters of the synthesis chamber were heated up to 900 °C and 800 °C, respectively, with a heating rate of 200 °C/min in a pure Ar atmosphere at 4 mbar. To eliminate undesired temperature gradients within the synthesis chamber, the heaters remained at the target temperatures for 600 s at 800 °C. Afterward, the plasma process was initiated. The series of experiments were decided based on the table of signs or Lal array  to studyray (4−1 . The fra4) was introduced with the following gas ratio 1:5:5; CH4, N2 and H2, respectively, and the DC plasma turned on with a discharge power of 100 W. The growing process was set to 1200 s. The synthesis conditions were optimized for the PECVD growth of graphene on pristine sapphire . The samples were cleaned using the 2-solvent method described above and introduced into the PECVD chamber. Similar to the heating process explained before, the system stayed for 600 s in a pure Ar atmosphere with a process pressure of 4 mbar once the top and bottom heaters reached 900 °C and 800 °C, respectively, with a heating rate of 200 °C/min. Afterward, the supply of Ar was halted while the reactive gas  from the laser diode module was 2.33 eV (532 nm), and the power was set to 25 mW. More information about the measurement parameters can be found in the The structural quality of the synthesized graphene was characterized using Raman spectroscopy at room temperature. A confocal Raman imaging microscope  was employed in the backscattering configuration using a 100× objective and a 600 gr/mm grating with 2.8 cmThe needle-in-sessile-drop method was used to measure the advancing and receding contact angle of the etched sapphire substrates before and after the graphene synthesis using an automatized goniometer  . The mea2O adsorption [2-based process , which, if sufficient hydrogen is supplied, become terminal hydroxide bridges (Al2(OH) species) [However, the sapphire surface can also exhibit terminal oxygen bridges (Alspecies) . When thspecies) ,34. ThisFurthermore, the wettability properties of sapphire can be modified to a large extent using patterned nanostructures . HoweverWhen the contact angle of graphene is evaluated, a large controversy exists because of its “wetting transparency,” as the graphene layer modifies the adsorption energy between the water molecule and the substrate . Contact2 or Ar processes  on the parameter under study (contact angle) allows us to find the influence of a particular factor within the process . As has rocesses . When th surface ,33. WhenHowever, when Ar is employed, the wettability of sapphire is completely different, and the surface becomes more hydrophobic, which is indicative of an OH-terminated sapphire surface . In thisWhen the main effects analysis evaluates the roughness of the sapphire substrate after the plasma process , the par−1 together with the defect-related bands: the D (1300 cm−1), its overtone the 2D (2680 cm−1) and the D′ (1620 cm−1) band [2-based plasma process  and, independently of the sapphire surface termination, for every Ar-based plasma process.The Raman fingerprint modes of pristine graphene are the G band at around 1583 cm−1) band . Althoug−1) band . When th−1, whereas a blue shift (~10 cm−1) is experienced by the G and D′ peaks as compared with the reference sample. On the other hand, when graphene is grown on Al-terminated sapphire surfaces, no remarkable shifts are observed for the D, G, D′ and 2D band positions.The Raman fingerprint bands of graphene show different shifts depending on the sapphire termination employed . When grD/IG ratio is usually employed to provide a measure of defects in graphene (D/IG ratios are comparable to those of the reference sample (3.48). However, the ID/IG ratio decreases for graphene grown on OH-terminated sapphire surfaces where a reduction of 38% is observed .The Igraphene A. Within2D/IG ratio. Independently of either the Al- or OH- terminated sapphire surface, the I2D/IG ratio decreases as compared with the reference sample (I2D/IG ratio ~0.37). Both smaller (30%) and larger (59%) reductions are observed for the graphene grown on OH-terminated sapphire surfaces.On the other hand, the structural quality is usually evaluated by the ID) or the defect density (σ); thus, L (nm) after Equations (1) and Equation (2), respectively [The presence of sharp defect-related D and D′ bands, together with the presence of the D + D′ band and the position of the G band, allows us to identify the synthesized graphene within stage I of the amorphization trajectory in graphite . In thisectively .(1)LD2 D/ID′ ratio does not depend on the defect concentration but on the nature of the defects [D/ID′ tends to seven. Within our samples, there are two different regimes depending on the plasma-induced sapphire surface terminations . For a perfect graphene D → 0. On the other hand, line defects (1D) are evaluated by the crystallite size (La) Equation (3) or by the crystallite area  .(3)La . On the other hand, independently of the plasma process, the I2D/IG ratio, which is usually reported as a quality measure of graphene, is reduced as compared with the pristine c-plane sapphire. The nature of graphene defects was identified by the ID/ID′ ratio: Al-terminated sapphire surfaces show vacancy-like defects in graphene, whereas boundary-like defects are more prominent in the graphene grown on OH-terminated sapphire surfaces.The IThe representation of defect density (


Rammed-earth dwellings have a long history in the construction field. It is a natural material that is both green and environmentally friendly. In recent years, the advantages of rammed earth, such as environmental protection, low cost, and recyclability, have attracted considerable attention. In this study, the thermal and humidity physical properties of rammed–earth materials in the northwest Sichuan region, the variation laws of thermal physical parameters, such as the thermal conductivity of rammed–earth under different moisture content conditions, and isothermal moisture absorption and desorption curves were investigated. The results indicated that the thermal physical parameters of the rammed earth measured in the experiment increased with an increase in moisture content, and its moisture absorption performance was better than the moisture release performance in the range of 11.31–97.3% relative humidity. The experimental site, Mianyang City, Sichuan Province, is a subtropical monsoon humid climate zone characterized by warm winters and hot summers with four distinct seasons. In this study, we investigated the hygrothermal coupling transfer of walls, as well as the indoor temperature and humidity changes in new rammed–earth buildings during summer and winter climates. During the test period, the maximum indoor temperature in summer was 35.08 °C, the minimum temperature was 33.76 °C, and the average daily temperature fluctuation was 3.62 °C. In winter, the maximum indoor temperature was 8.59 °C, the minimum temperature was 6.18 °C, and the average daily temperature fluctuation was 1.21 °C. An analysis was performed on the thermal insulation performance of rammed–earth buildings in an extremely high-temperature climate during summer, thermal insulation performance, the thermal–buffering capacity of walls in a low–temperature and high-humidity climate during winter, and thermal and humidity regulation of indoor environments provided by walls during summer and winter. The results showed that the rammed–earth buildings exhibited warmth in winter, coolness in summer, and a more stable and comfortable indoor environment. Against the backdrop of global economic integration, a rapidly developing world economy has brought about significant energy consumption, with the construction sector accounting for a large proportion . This haRammed earth is a very old building material, which is very common and often promoted as a sustainable building material . As a loIt is well known that rammed–earth walls can regulate indoor temperature and humidity , reduce A wide range of domestic and foreign scholars have conducted studies on the different properties of rammed earth. Fernando et al.  investigThis study considered rammed–earth buildings in northwest Sichuan as a case study. First, the heat and humidity physical property parameters of rammed-earth materials were measured under different relative humidity environments, and their change laws were analyzed. Second, the heat and moisture coupling transfer of rammed–earth buildings in the winter and summer seasons was comprehensively monitored and analyzed through field tests, theoretical analysis, and other methods to study the heat and moisture performance of rammed–earth walls under typical climatic conditions and the temperature and humidity changes in building indoor environments, as well as their influence on living comfort.3 met the strength requirements of the standard compressive strength of 2.0 MPa [The rammed earth used for the experiment was obtained from Mianyang , Sichuan Province, consistent with the rammed–earth used in the building, and approximately 5 kg of the sample soil was taken, crushed, sieved with a test sieve (square hole diameter of 1.6 mm), and pressed into a shape in a mold, as shown in  2.0 MPa  for ramm 2.0 MPa .3.After the prepared specimens were maintained at 25 ± 0.5 °C and 60 ± 2% RH for 7 d, the specimen was dried in a dry box at 105 °C for 24 h as shown in The specimens were placed on a cling film, and six faces of the specimens were continuously and randomly sprayed with pure water using a capillary nozzle. Nine groups of rammed–earth specimens with moisture content ranging from 0% to 16% (moisture content gradient of 2%) were prepared separately . As showu(φ) is the equilibrium moisture content of the specimen corresponding to the relative humidity, kg/kg; im(φ) is the mass of the specimen when the relative humidity is in equilibrium, kg; m0 is the mass of the specimen when it is completely dry, kg.Isothermal moisture absorption and discharge curves were plotted based on the equilibrium moisture content obtained in isothermal environments with different relative humidities. The moisture absorption and discharge capacities of the rammed–earth materials were obtained by studying their isothermal moisture absorption and discharge curves. The experiment was conducted using the desiccator method, and the indoor experimental environment was maintained at 25 ± 1 °C and 60 ± 1% relative humidity ,23,24. Tλ is the thermal conductivity (W/m·K), D is the thermal–diffusion coefficient (m2/s), and w is the moisture content weight.The test results for the thermal conductivity and thermal–diffusion coefficient, and the calculation results for the specific heat capacity  are showFor the same substance, the material structure, density, temperature, humidity, and pressure affect the thermal conductivity . In geneFrom D is the thermal–diffusion coefficient (m2/s), λ is the thermal conductivity (W/m·K), pCm, is the mass–specific heat capacity (J/kg·K), and mρ is the density, kg/m3.The ability of a rammed–earth material to maintain its initial temperature when disturbed is called the thermal mass, and the thermal mass of materials is quantified by the thermal–diffusion coefficient. As the thermal–diffusion coefficient increases, the thermal inertia of the material decreases, enabling the surface material to reach thermal equilibrium more quickly. The formula used is as follows:Based on Equation (4), using the measured thermal conductivity and thermal diffusion coefficients, the mass specific heat capacity was calculated. A quadratic polynomial was fitted to the results, and the functional relationship was obtained as follows:The experimental results showed that the thermal conductivity, thermal diffusion coefficient, and mass specific heat capacity of rammed–earth materials increased with the increase in moisture content. The thermal conductivity of the material was most affected by the moisture content, compared to the moisture content at 0% . The thermal conductivity improved by 114.1% when the moisture content reached 16%, and the thermal–diffusion coefficient was least affected, with an improvement of 36.9%. The greatest increase in thermal conductivity and mass specific heat capacity was observed at 4% moisture content of the rammed–earth material, with a 12.3% increase in thermal conductivity and an 8.2% increase in mass specific heat capacity, and the smallest increase in mass specific heat capacity was observed at 16% moisture content, with a 2.1% increase.φ is the relative humidity, taking a value between 0 and 1, and U is the equilibrium moisture content of the material, kg/kg.There are many different analytical expressions for isothermal hygroscopic curves, and the Peleg model was used to calculate these curves . The modAs shown in To study the coupled heat and humidity transfer process and the indoor heat and humidity environment of the rammed–earth building envelope, the temperature and humidity were measured. The experiment was a year–round uninterrupted test. The test data from 11 August to 17 August and 1 December to 7 December 2022 were selected for the analysis and research in this paper, with the summer period having a local extreme high–temperature climate of 1 in 60 years. During the experiment, the doors and windows were closed, and there was no ventilation, indoor heat source, or moisture source. The experimental building is located at Southwest University of Science and Technology, Mianyang , Sichuan Province. It was constructed using the slab–on–wall construction method, completed in August 2021, and is only used for experiments without human habitation. From the interior floor to the highest point of the sloped roof is 3.5 m, and to the eaves is 2.7 m. The room width is 3 m, depth is 4 m, and wall thickness is 0.37 m, as shown in The test system provided real–time measurements of the indoor temperature and humidity in the buildings, internal temperature, humidity in walls, outdoor temperature and humidity, and solar radiation on the north side of the building. The experiments were conducted by collecting, recording, and storing temperature and humidity data using a Keysight-DAQ970A data acquisition instrument at a recording interval of 10 min. Temperature data were measured using a K-type thermocouple , humidity data were measured by a Honeywell capacitive humidity sensor , and the humidity sensor was connected to a 5 V DC power supply. Solar radiation was measured by a JTR05 type solar radiation sensor . The internal wall temperature and humidity sensors were arranged in a perforated manner at 1.7 m high and 1 m from the corner of the north wall, with the arrangement direction perpendicular to the wall, and the arrangement depths were 0.07 m(C), 0.19 m(B), and 0.30 m(A) from the internal surface of the wall, as shown in The test data from 00:00 on 11 August to 24:00 on 17 August in summer were selected for research, which all had typical summer high–temperature weather, and the test period consisted of continuous sunny days with no rainfall. To avoid affecting the test environment during the test, there was no heat or humidity source in the building.testq is the heat flux during the test period, W/m2; ih is the convective heat–transfer coefficient of the surface inside the wall, W/(m2·K); iT is the room temperature, K; surfiT is the temperature of the surface inside the wall, K.Because the energy performance of a building is difficult to quantify, as it depends on its inherent parameters as well as the living environment, this study investigated the energy transfer information of a building in terms of heat flux. Based on Equation (9), the heat flux of a rammed–earth wall can be calculated using test data, which was calculated as2 and the total heat release was 1656.46 W/m2.The building was built in only one year, and a large amount of moisture was retained inside the wall; therefore, the moisture content was highest in the middle of the wall. According to testg is the wet flux during the test period (kg/m2), βi is the convective mass transfer coefficient of the surface inside the wall (s/m), iφ is the relative humidity of the room, surfiφ is the relative humidity of the internal surface of the wall (%), satPi, is the indoor saturated water vapor partial pressure (Pa), and sat,surfiP is the saturated water vapor partial pressure on the internal surface of the wall (Pa).The moisture flux on the inner surface of the wall was calculated based on test data.2.According to Indoor relative humidity is an important reference index for comfort in a living environment. As shown in Test data from 00:00 on 1 December to 24:00 on 7 December in winter were selected for research, which all had typical winter low–temperature weather. The seventh day of the test was sunny, and the rest of the period was cloudy with no rainfall, similar to summer, with no other indoor heat or humidity sources.As shown in 2 and the total heat release was 361.96 W/m2.The heat flux calculation formula for the inner surface of the wall in winter was the same as that for summer, the calculation results are shown in −4 kg/m2, and the moisture dissipation was 4.78 × 10−4 kg/m2.According to As shown in In this study, the thermal and physical properties of rammed–earth materials in the northwest region of Sichuan were investigated. The changes in their thermal physical properties under different moisture content conditions, as well as the corresponding functional relationships and isothermal moisture absorption and release curves, were obtained. During summer and winter, the coupled heat and moisture transfer processes of rammed-earth walls and changes in the indoor environment of buildings were analyzed. The main findings of this study are as follows:(1) The thermal conductivity and other thermophysical parameters of rammed earth under different moisture content conditions were measured, and the equations of the thermal physical parameters as a function of moisture content were fitted, which proved that the higher the moisture content of the rammed–earth materials, the larger the related thermal physical parameters.(2) The moisture absorption and discharge amounts of the rammed–earth materials were measured under different relative humidities, and the corresponding isothermal equilibrium moisture contents were calculated. The isothermal moisture absorption and discharge curves of the rammed–earth materials were fitted by nonlinear curves, and the results showed that they had good moisture absorption and discharge characteristics, and that the moisture absorption performance was better than the moisture discharge performance.(3) Under the extremely high–temperature weather conditions during summer, the rammed–earth wall interior surface and building interior environment had lower temperatures and relatively stable temperature and humidity fluctuations. The daily average indoor temperature fluctuation was 3.62 °C, and the daily average relative humidity fluctuation was 12.85%. The new wall continuously dissipated moisture in summer, and the interior relative humidity was in the comfort zone of 50–60% for 72.6% of the time. The fluctuations were more stable, which proves that the rammed–earth building has excellent thermal insulation and buffer characteristics under extremely high-temperature weather and can create a more comfortable indoor environment.(4) Under the low-temperature and high–humidity conditions during winter, the rammed–earth wall interior surface and building interior environment had more stable temperature and humidity fluctuations, with higher temperatures and lower humidity. The daily average indoor temperature fluctuation was 1.21 °C, and the daily average relative humidity fluctuation was 9.69%. With a change in the indoor relative humidity, the wall interior surface could absorb and release moisture accordingly, effectively regulating the indoor humidity environment. This indicates that the rammed-earth building has excellent thermal insulation performance and humidity–buffering characteristics during winter.


Staphylococcus aureus 33591, Pseudomonas aeruginosa 15442, Candida albicans 10231) were also examined. The results indicate that the addition of graphene flakes significantly enhances both the mechanical and antimicrobial properties of the coatings.In this study, graphene flakes were obtained using an electrolytic method and characterized using X-ray diffraction (XRD), Raman and FTIR spectroscopy, scanning and transmission electron microscopy (SEM/TEM). Graphene-based composites with varying concentrations of 0.5%, 1% and 3% by weight were prepared with acrylic paint, enamel and varnish matrices. The mechanical properties were evaluated using micro-hardness testing, while wettability and antimicrobial activity against three pathogens ( Graphene is a well-known, single-layer, two-dimensional material. Its Young’s modulus is 1 TPa . GraphenThanks to high electron mobility, thermal conductivity and biocompatibility, graphene structures have found application in many areas, such as electronics ,7,8, sen3O4 composite varnish with higher than ordinary paint corrosion resistance was invented, providing great coverage for ships or urban exteriors [Due to its superior mechanical properties, graphene-based composites with various polymers or graphene-based paints and varnishes are widely studied ,15,16,17xteriors .For this reason, and to take advantage of graphite electrolysis’s simplicity and low costs, graphene flakes were examined herein. An attempt was made to prepare graphene-based paints and varnishes in order to study graphene’s mechanical and biological properties and to further evaluate its potential applications.2 planes, while the second is observed due to the crystalline structure of graphite, which still exists in the sample. The broad band observed in the diffractogram indicates that the graphene observed here takes the form of reduced graphene oxide (rGO) [−1), G (1580 cm−1) and 2D—also referred to as G’ (2700 cm−1) [−1, which is associated with the D + G mode. The 2D band intensity is lower than the G band, while the D band has a similar intensity as the G band. The ratio of the D band to the G band indicates the degree of deformation [2D/IG is dependent on the number of graphene layers [2D/IG ∼ 2–3 is observed for mono-layer graphene, 2 > I2D/IG > 1 for bi-layer graphene and I2D/IG below 1 for multi-layer one. The I2D/IG ratio for rGO in the studied material is 0.44, which confirms the multi-layer character of the prepared flakes. The FTIR spectrum  . Based ode (rGO) , the ave00 cm−1) —and an aormation  and is ee layers . As the spectrum c is quitThe SEM images of graphene flakes used as a filler in the composites are shown in For the enamel composite coatings, SEM images were taken to show how the graphene flakes are arranged on the surface . It can Knoop micro-hardness measurements were conducted for each composite, and the recorded results were limited to the enamel samples. The ED3 sample displayed the highest micro-hardness, with comparable values obtained for the reference sample . Micro-hThe wettability tests conducted on graphene-based varnish, enamel and acrylic composites revealed contact angles of less than 90°. Water droplets were observed to remain on the surfaces of enamel and varnish, while on the acrylic paint surface, the droplets tended to flow, and in some areas, they were even absorbed by the coating. Multiple measurements were taken at different locations to obtain an average result. However, due to the weak dispersion of graphene flakes within the composite volume and partial aggregation of flakes in certain areas (as seen in the SEM images), the measurements were subject to a significant measurement error. This was particularly evident in composites with higher graphene content (1% and 3% by weight), where the wettability of the composite was sometimes lower than that of the pure paint . In contStaphylococcus aureus (Gram-positive bacteria), Pseudomonas aeruginosa (Gram-negative bacteria) and Candida albicans (fungi). Octenidine dihydrochloride was used as a control antimicrobial agent with proven activity against these pathogens, where the reduction in living cells was close to 100%, and it was set as a reference for the activity of composites. The lowest antimicrobial activity was revealed for the acrylic composite paint. Only in a few cases was the reduction in bacteria higher in composites compared to pure paint. There was also no clear tendency in the pathogen survival rate with the concentration of graphene flakes in the composites  in contrast to alternative paints. Given that the contact angle exerts a substantial influence on the micro-biological activity of the composite  increas. Anti-baThe physical and biological properties of acrylic paint, enamel and varnish composites after the addition of graphene flakes were evaluated in this study. The graphene flakes used in this study were characterized as being of good quality with a large size, which posed challenges in achieving well-homogenized materials. The varnish and enamel composites showed notable hydrophobic properties, while all graphene-based paints exhibited low micro-hardness. However, the rapid disappearance of indentation observed during micro-hardness tests suggested a high potential for developing graphene-based coatings with self-healing properties. Additionally, antimicrobial tests showed a significant pathogen reduction on the surface of the paints, even for very low concentrations of the graphene flakes. The physical and biological measurements shed new light on the development of graphene-based composite paints. To fully realize their potential, further solutions need to be implemented to make them fully functional and suitable for commercial use.Staphylococcus aureus 33591, Pseudomonas aeruginosa 15442, Candida albicans 10231 (American Type and Culture Collection) were incubated for 24 h at 37 °C in Tryptic Soy Broth (TSB).The graphite foil  was cut and prepared for stripes with dimensions of 20 × 100 mm. The 0.1 M aqueous solution of ammonium sulfate  was used as a reaction medium in electrolysis. For the composite paints, commercial products were used: acrylic paint , varnish , enamel . The reference strains of methicillin-resistant −3 mbar.The graphene nanoflakes were prepared using the electrochemical method previously described by us in detail in Ref . The two−1 range with a resolution of 2 cm−1. The IR spectra in the mid-IR range of 4000–400 cm−1 were measured using a Nicolet iS50 infrared spectrometer with the KBr pellet method. Scanning and transmission electron microscopies ; TEM-Philips CM-20 SuperTwin, Eindhoven, The Netherlands) were used to study the morphology of graphene flakes. Samples for SEM and TEM measurements were prepared by dispersing a small amount of specimens in methanol and putting a droplet of the suspension on a carbon stub or copper microscope grid covered by carbon, respectively.The structure, morphology and quality of graphene flakes were examined using several techniques. X-ray diffraction measurements were carried out using Cu Kα monochromatic radiation (λ = 1.5406 Å) on an X’Pert PRO, PANalytical  by scanning the diffraction angles (2θ) between 10° and 40° at room temperature in the Bragg–Brentano geometry. The Raman spectra were measured using a Renishaw InVia Raman spectrometer equipped with an optical microscope , a thermoelectrically cooled charge-coupled device (CCD) as a detector and an argon laser operating at 514 nm as an excitation source. The spectrum was measured in the 1000–3200 cmDry graphene flakes were added into acrylic paint (FA), enamel (ED) and varnish (LV) to obtain composites with 0.5 , 1  and 3 weight %  graphene concentrations. For this purpose, 0.25, 0.5 and 1.5 g of graphene flakes were added to paints (up to 50 g) for each concentration, respectively. The paint with the filler was mixed in a laboratory stirrer for 20 min, starting with the lowest rotations and finishing with the maximum 830 RPM. Afterward, metal plates with dimensions of 30 × 50 × 2 mm were covered with graphene-based composites for future studies.The morphology of the enamel composite surface was investigated by FE-SEM. In the first step, the samples were placed on the stub in order to eliminate charging and drift problems. Afterward, the samples were put under an electron beam and analyzed by using a secondary electron (SE) for the stub tilted at an angle of 70 degrees in order to show more detailed features of the samples. The SEM images were recorded at 5.0 kV in a beam deceleration mode, which improves imaging parameters, such as resolution and contrast.The micro-hardness measurements of dried samples were performed using the Knoop method, according to the ASTM E92 standard, using the ZHVµ-A  hardness tester. The tests were conducted after establishing the optimal load, which allowed the measurement of the diagonals of the resulting imprint. For the indentations, 50 g load was applied for 10 s. Five measurements were conducted on the top surface of the samples. The wettability/water contact angle of the obtained composites was measured using an PGX goniometer  with integrated software, using the sitting drop method in the static mode, where the automatically released drop of deionized water with ~5 µL was placed on the surface of the measured sample.Staphylococcus aureus 33591, Pseudomonas aeruginosa 15442 and Candida albicans 10231  were incubated for 24 h at 37 °C in Tryptic Soy Broth . A suspension of the test strains was prepared in saline with a density of 0.5 McFarland (1.5 × 108 CFU/mL) and diluted a thousand times in the culture medium. Next, 1 mL of the suspension was added to the wells of the 6-well plate containing the test paints and incubated for 24 h at 37 °C under static conditions. To control for microbial growth, the suspension was also added to wells devoid of test substances in 6 replicates. After incubation, the medium was gently removed from the wells, and 1 mL of a 0.1% (w/v) solution of 3,2,5-triphenyltetrazolium chloride  in TSB was added to the wells. The system was then incubated again at 21 °C for 4 h. Next, the medium was removed from the plate wells, and 1 mL of a 9:1 mixture of methanol and acetic acid was added. The plate was incubated at room temperature for 30 min with shaking (350 RPM). From each well, 100 µL of the solution was withdrawn three times and transferred to 3 wells of a 96-well plate. The absorbance of the solutions was measured spectrophotometrically at a wavelength of 490 nm, and the absorbance of each sample was determined by calculating the average of 3 measurements.To conduct antimicrobial studies, the tested paints were evenly spread into the wells of a 6-well plate  using a micro-biological spatula under aseptic conditions in a laminar chamber. The plate was then incubated at room temperature for 24 h to dry the paint. The reference strains of methicillin-resistant