Tunability of the electronic properties and electrical contact in graphene/SiH heterostructures.

Stacking different two-dimensional materials to generate a vertical heterostructure has been considered a promising way to obtain the desired properties and improve device performance. Here, in this work, using first principles calculations, we design a vertical heterostructure by stacking graphene (GR) and silicane (SiH) and investigate the electronic properties and electrical contact in the GR/SiH heterostructure as well as the possibility of tuning these properties under an external electric field and vertical strain. The GR/SiH heterostructure is structurally and mechanically stable at the equilibrium interlayer separation. The GR/SiH heterostructure exhibits a p-type Schottky contact with a small Schottky barrier of 0.43 eV, presenting great tunability of the electrical contact from Schottky to Ohmic contact under different conditions. The external electric field not only leads to a transition from the p-type to n-type Schottky contact but also induces a transformation from a Schottky contact to Ohmic one. Furthermore, changing the interlayer separation can be considered a useful tool to regulate the Schottky barriers and electric contact in the GR/SiH heterostructure, which is prominent for constructing electronic devices. Our findings could provide an effective tool for the design of high-performance nanoelectronic devices based on the GR/SiH heterostructure.

The efficiency of potential food waste-degrading bacteria under harsh conditions.

AIMS: Investigate the impact of highly adapted bacterial strains and their ability in waste degradation under a wide range of temperatures. METHODS AND RESULTS: Bacteria isolated from soil and food waste were grown in various media under fluctuated temperatures. After screening for organic compound degradation, the seven strongest bacterial strains have been selected for further experiments. Their enzyme activities were expressed in terms of the size of the hydrolysis zone in a wide temperature range of 2·5-70°C. The enzyme production assay was carried out for each protease, cellulase and amylase. The waste degradation was determined with a maximum 80% decrease in the volume of food waste in 21 days compared to the control in lab scale with enriched bacterial cultures and soil bacteria as additives at room temperature around 18-20°C. CONCLUSION: These seven bacteria are promising candidates for food waste biodegradation in composting especially in the winter without heating expense for maintaining ambient temperature. SIGNIFICANCE AND IMPACT OF THE STUDY: It is necessary to coax the uncultured bacteria from the various environments into the laboratory for investigating their valuable functions. Herein, using enrichment culture of consortium and additive of soil has illustrated the significant mean in food waste degradation.

Measurement of the Spin Absorption Anisotropy in Lateral Spin Valves.

The spin absorption process in a ferromagnetic material depends on the spin orientation relative to the magnetization. Using a ferromagnet to absorb the pure spin current created within a lateral spin valve, we evidence and quantify a sizable orientation dependence of the spin absorption in Co, CoFe, and NiFe. These experiments allow us to determine the spin-mixing conductance, an elusive but fundamental parameter of the spin-dependent transport. We show that the obtained values cannot be understood within a model considering only the Larmor, transverse decoherence, and spin diffusion lengths, and rather suggest that the spin-mixing conductance is actually limited by the Sharvin conductance.

Fluorescent Properties of Carboxyfluorescein Bifluorophores.

Bright fluorescent probes with enhanced intensities in the fluorescein channel are of great value for plenty of biological applications. To design effective probes one should introduce as many as possible fluorophores to the biomolecule while leaving its native structure as intact as possible. To reach this compromise, we designed and synthesized fluorescein bifluorophores on the 3,5-diaminobenzoic acid scaffold, which allows for insertion of two fluorophores at one modification site of a biomolecule. Rigid structure of the branching linker group allows to minimize self-quenching the fluorophores. However, despite the structure similarities of fluorescein isomers (5-FAM and 6-FAM), different photophysical behavior was observed for the corresponding bifluorophores. Here we made efforts to get insight into these effects with the focus on the media viscosity impact.

Bone decay and beyond: how can we approach it better.

Osseo-degeneration is a disorder related to several factors, that may lead to the disruption of several skeletal regions providing support, such as the femur head, the vertebrae and the alveolar bone. The functional condition can be restored by means of grafting procedures, using different materials: calcium powder, xenografts, ceramics and metals. Such procedures aim at reforming an adequate bone volume and strength, that is necessary to support loading forces. Bone regeneration requires that the basic biological principles of osteogenesis, osteoinduction, osteoconduction and biocompatibility are followed. The success of regenerative procedures may depend on the inner structural, mechanical and metabolic condition of the host's bone on which implants should be inserted, on the surgical technique, and on the biomaterial used. Among these, the aging process of the patient appears to be relevant. It can be associated with metabolic disease leading to systemic functional decay, which involves a gradual steady decline of hormonal, immune function and osteo-metabolic activity. The latter can affect the positive outcomes of bone reconstruction and implant therapy. This review will analyze the biological and physiological factors involved in the bone tissue break-down, such as the influences from gut microbiome unbalance and the consequent metabolic, endocrine, immune dysfunctions, the surgery procedures and the quality of the grafting material used. The decline of bone architecture and strength should be corrected by using an appropriate clinical regenerative approach, based on a bio-endocrine, metabolic and immunologic know-how. The final characteristics of the regenerated bone must be able to support the loading forces transmitted by the implants, independent of the body location, and should be individualized according to the different condition of each patient.

Photoinduced electron transfer in a molecular dyad by nanosecond pump-pump-probe spectroscopy.

The design of robust and inexpensive molecular photocatalysts for the conversion of abundant stable molecules like H2O and CO2 into an energetic carrier is one of the major fundamental questions for scientists nowadays. The outstanding challenge is to couple single photoinduced charge separation events with the sequential accumulation of redox equivalents at the catalytic unit for performing multielectronic catalytic reactions. Herein, double excitation by nanosecond pump-pump-probe experiments was used to interrogate the photoinduced charge transfer and charge accumulation on a molecular dyad composed of a porphyrin chromophore and a ruthenium-based catalyst in the presence of a reversible electron acceptor. An accumulative charge transfer state is unattainable because of rapid reverse electron transfer to the photosensitizer upon the second excitation and the low driving force of the forward photodriven electron transfer reaction. Such a method allows the fundamental understanding of the relaxation mechanism after two sequential photon absorptions, deciphering the undesired electron transfer reactions that limit the charge accumulation efficiency. This study is a step toward the improvement of synthetic strategies of molecular photocatalysts for light-induced charge accumulation and more generally, for solar energy conversion.

Quantitative value chain approaches for animal health and food safety.

Economic impact assessments are increasingly important in the context of animal health and food safety, although much of the existing literature does not address the broader systems context in which disease transmission takes place. In this paper, we discuss the role of system dynamics modeling in addressing the value chain impacts associated with animal health and food safety issues. System dynamics methods hold promise as a means of capturing the complex feedbacks that exist between the biology, economics, and behavioral aspects of food safety and animal health systems. We provide a proof-of-concept of this approach in the context of food safety and animal health in the smallholder pig sector of Viet Nam. Results highlight the important tradeoffs that exist between policy objectives and the costs required to achieve them.

Phylodynamics of foot-and-mouth disease virus O/PanAsia in Vietnam 2010-2014.

Foot-and-mouth disease virus (FMDV) is endemic in Vietnam, a country that plays an important role in livestock trade within Southeast Asia. The large populations of FMDV-susceptible species in Vietnam are important components of food production and of the national livelihood. In this study, we investigated the phylogeny of FMDV O/PanAsia in Vietnam, reconstructing the virus' ancestral host species (pig, cattle or buffalo), clinical stage (subclinical carrier or clinically affected) and geographical location. Phylogenetic divergence time estimation and character state reconstruction analyses suggest that movement of viruses between species differ. While inferred transmissions from cattle to buffalo and pigs and from pigs to cattle are well supported, transmission from buffalo to other species, and from pigs to buffalo may be less frequent. Geographical movements of FMDV O/PanAsia virus appears to occur in all directions within the country, with the South Central Coast and the Northeast regions playing a more important role in FMDV O/PanAsia spread. Genetic selection of variants with changes at specific sites within FMDV VP1 coding region was different depending on host groups analyzed. The overall ratio of non-synonymous to synonymous nucleotide changes was greater in pigs compared to cattle and buffalo, whereas a higher number of individual amino acid sites under positive selection were detected in persistently infected, subclinical animals compared to viruses collected from clinically diseased animals. These results provide novel insights to understand FMDV evolution and its association with viral spread within endemic countries. These findings may support animal health organizations in their endeavor to design animal disease control strategies in response to outbreaks.

Brevundimonas albigilva sp. nov., isolated from forest soil.

Strain NHI-13T, a Gram-stain-negative, aerobic and short rod-shaped bacterium, was isolated from forest soil at Kyonggi University in Suwon, South Korea. It grew optimally in R2A medium, at 20-30 °C, in the presence of 0-4 % NaCl. Colonies resulting from incubation of the strain on agar plates for 2 days were circular, raised, translucent, viscous and whitish-yellow, with entire margins. This strain exhibited high catalase activity but was negative for oxidase. 16S rRNA gene sequence analysis showed that strain NHI-13T formed a coherent cluster with members of the genus Brevundimonas. Its similarities were 98.0 % with Brevundimonas aurantiaca DSM 4731T, 97.9 % with Brevundimonas vesicularis LMG 2350T, 97.6 % with Brevundimonas intermedia ATCC 15262T, 97.5 % with Brevundimonas nasdae GTC 1043T, 97.1 % with 'Brevundimonas olei' MJ15, 97.1 % with Brevundimonas mediterranea V4.BO.10T and 97.0 % with Brevundimonas poindexterae FWC40T. The major cellular fatty acids were summed feature 8 (C18 : 1ω7c/C18 : 1ω6c), C16 : 0 and 11-methyl C18 : 1ω7c. The DNA G+C content was 63 mol%. The predominant quinone was ubiquinone Q-10. The polar lipid profile contained 1,2-di-O-acyl-3-O-α-d-glycopyranuronosyl glycerol, 1,2-di-O-acyl-3-O-α-d-glycopyranosyl glycerol, 1,2-di-O-acyl-3-O-[d-glycopyranosyl (1 → 4)-α-d-glucopyranuronosyl] glycerols, phosphatidylglycerol, 1,2-diacyl-3- O-(6'-phosphatidyl-α-d-glucopyranosyl) glycerol and other unknown lipids. The DNA relatedness of strain NHI-13T with its reference strains was in the range of 43-56 %. On the basis of its phenotypic, genotypic, chemotaxonomic and phylogenetic distinctiveness, strain NHI-13T is suggested to be a representative of a novel species, belonging to the genus Brevundimonas. Therefore, the name Brevundimonas albigilva. sp. nov. is proposed, with the type strain being NHI-13T ( = KEME 9005-016T = KACC 18249T = JCM 30385T).

The structure of liquid water up to 360 MPa from x-ray diffraction measurements using a high Q-range and from molecular simulation.

X-ray diffraction measurements of liquid water are reported at pressures up to 360 MPa corresponding to a density of 0.0373 molecules per Å(3). The measurements were conducted at a spatial resolution corresponding to Q(max) = 16 Å(-1). The method of data analysis and measurement in this study follows the earlier benchmark results reported for water under ambient conditions having a density of 0.0333 molecules per Å(3) and Q(max) = 20 Å(-1) [J. Chem. Phys. 138, 074506 (2013)] and at 70 °C having a density of 0.0327 molecules per Å(3) and Q(max) = 20 Å(-1) [J. Chem. Phys. 141, 214507 (2014)]. The structure of water is very different at these three different T and P state points and thus they provide the basis for evaluating the fidelity of molecular simulation. Measurements show that at 360 MPa, the 4 waters residing in the region between 2.3 and 3 Å are nearly unchanged: the peak position, shape, and coordination number are nearly identical to their values under ambient conditions. However, in the region above 3 Å, large structural changes occur with the collapse of the well-defined 2nd shell and shifting of higher shells to shorter distances. The measured structure is compared to simulated structure using intermolecular potentials described by both first-principles methods (revPBE-D3) and classical potentials (TIP4P/2005, MB-pol, and mW). The DFT-based, revPBE-D3, method and the many-body empirical potential model, MB-pol, provide the best overall representation of the ambient, high-temperature, and high-pressure data. The revPBE-D3, MB-pol, and the TIP4P/2005 models capture the densification mechanism, whereby the non-bonded 5th nearest neighbor molecule, which partially encroaches the 1st shell at ambient pressure, is pushed further into the local tetrahedral arrangement at higher pressures by the more distant molecules filling the void space in the network between the 1st and 2nd shells.

Positive selection drives accelerated evolution of mosquito salivary genes associated with blood-feeding.

The saliva of bloodsucking animals contains dozens to hundreds of proteins that counteract their hosts' haemostasis, inflammation and immunity. It was previously observed that salivary proteins involved in haematophagy are much more divergent in their primary sequence than those of housekeeping function, when comparisons were made between closely related organisms. While this pattern of evolution could result from relaxed selection or drift, it could alternatively be the result of positive selection driven by the intense pressure of the host immune system. We investigated the polymorphism of five different genes associated with blood-feeding in the mosquito Anopheles gambiae and obtained evidence in four genes for sites with signatures of positive selection. These results add salivary gland genes from bloodsucking arthropods to the small list of genes driven by positive selection.

Effect of primaquine dose on the risk of recurrence in patients with uncomplicated Plasmodium vivax: a systematic review and individual patient data meta-analysis.

BACKGROUND: Primaquine is used to eliminate Plasmodium vivax hypnozoites, but its optimal dosing regimen remains unclear. We undertook a systematic review and individual patient data meta-analysis to investigate the efficacy and tolerability of different primaquine dosing regimens to prevent P vivax recurrence. METHODS: For this systematic review and individual patient data meta-analysis, we searched MEDLINE, Web of Science, Embase, and Cochrane Central for prospective clinical studies of uncomplicated P vivax from endemic countries published between Jan 1, 2000, and June 8, 2023. We included studies if they had active follow-up of at least 28 days, and if they included a treatment group with daily primaquine given over multiple days, where primaquine was commenced within 7 days of schizontocidal treatment and was given alone or coadministered with chloroquine or one of four artemisinin-based combination therapies (ie, artemether-lumefantrine, artesunate-mefloquine, artesunate-amodiaquine, or dihydroartemisinin-piperaquine). We excluded studies if they were on prevention, prophylaxis, or patients with severe malaria, or if data were extracted retrospectively from medical records outside of a planned trial. For the meta-analysis, we contacted the investigators of eligible trials to request individual patient data and we then pooled data that were made available by Aug 23, 2021. We assessed the effects of total dose and duration of primaquine regimens on the rate of first P vivax recurrence between day 7 and day 180 by Cox's proportional hazards regression (efficacy analysis). The effect of primaquine daily dose on gastrointestinal symptoms on days 5-7 was assessed by modified Poisson regression (tolerability analysis). The study was registered with PROSPERO, CRD42019154470. FINDINGS: Of 226 identified studies, 23 studies with patient-level data from 6879 patients from 16 countries were included in the efficacy analysis. At day 180, the risk of recurrence was 51·0% (95% CI 48·2-53·9) in 1470 patients treated without primaquine, 19·3% (16·9-21·9) in 2569 patients treated with a low total dose of primaquine (approximately 3·5 mg/kg), and 8·1% (7·0-9·4) in 2811 patients treated with a high total dose of primaquine (approximately 7 mg/kg), regardless of primaquine treatment duration. Compared with treatment without primaquine, the rate of P vivax recurrence was lower after treatment with low-dose primaquine (adjusted hazard ratio 0·21, 95% CI 0·17-0·27; p<0·0001) and high-dose primaquine (0·10, 0·08-0·12; p<0·0001). High-dose primaquine had greater efficacy than low-dose primaquine in regions with high and low relapse periodicity (ie, the time from initial infection to vivax relapse). 16 studies with patient-level data from 5609 patients from ten countries were included in the tolerability analysis. Gastrointestinal symptoms on days 5-7 were reported by 4·0% (95% CI 0·0-8·7) of 893 patients treated without primaquine, 6·2% (0·5-12·0) of 737 patients treated with a low daily dose of primaquine (approximately 0·25 mg/kg per day), 5·9% (1·8-10·1) of 1123 patients treated with an intermediate daily dose (approximately 0·5 mg/kg per day) and 10·9% (5·7-16·1) of 1178 patients treated with a high daily dose (approximately 1 mg/kg per day). 20 of 23 studies included in the efficacy analysis and 15 of 16 in the tolerability analysis had a low or unclear risk of bias. INTERPRETATION: Increasing the total dose of primaquine from 3·5 mg/kg to 7 mg/kg can reduce P vivax recurrences by more than 50% in most endemic regions, with a small associated increase in gastrointestinal symptoms. FUNDING: Australian National Health and Medical Research Council, Bill & Melinda Gates Foundation, and Medicines for Malaria Venture.

Epidemiological features and risk factors of Salmonella gastroenteritis in children resident in Ho Chi Minh City, Vietnam.

Non-typhoidal Salmonella are an important but poorly characterized cause of paediatric diarrhoea in developing countries. We conducted a hospital-based case-control study in children aged <5 years in Ho Chi Minh City to define the epidemiology and examine risk factors associated with Salmonella diarrhoeal infections. From 1419 diarrhoea cases and 571 controls enrolled between 2009 and 2010, 77 (5∙4%) diarrhoea cases were stool culture-positive for non-typhoidal Salmonella. Salmonella patients were more likely to be younger than controls (median age 10 and 12 months, respectively) [odds ratio (OR) 0∙97; 95% confidence interval (CI) 0∙94-0∙99], to report a recent diarrhoeal contact (8∙1% cases, 1∙8% controls; OR 5∙98, 95% CI 1∙8-20∙4) and to live in a household with >2 children (cases 20∙8%, controls 10∙2%; OR 2∙32, 95% CI 1∙2-4∙7). Our findings indicate that Salmonella are an important cause of paediatric gastroenteritis in this setting and we suggest that transmission may occur through direct human contact in the home.

X-ray absorption spectroscopy of ground and excited rhenium-carbonyl-diimine complexes: evidence for a two-center electron transfer.

Steady-state and picosecond time-resolved X-ray absorption spectroscopy is used to study the ground and lowest triplet states of [ReX(CO)(3)(bpy)](n+), X = Etpy (n = 1), Cl, or Br (n = 0). We demonstrate that the transient spectra at both the Re L(3)- and Br K-edges show the emergence of a pre-edge feature, absent in the ground-state spectrum, which is associated with the electron hole created in the highest occupied molecular orbital following photoexcitation. Importantly, these features have the same dynamics, confirming previous predictions that the low-lying excited states of these complexes involve a two-center charge transfer from both the Re and the ligand, X. We also demonstrate that the DFT optimized ground and excited structures allow us to reproduce the experimental XANES and EXAFS spectra. The ground-state structural refinement shows that the Br atom contributes very little to the latter, whereas the Re-C-O scattering paths are dominant due to the so-called focusing effect. For the excited-state spectrum, the Re-X bond undergoes one of the largest changes but still remains a weak contribution to the photoinduced changes of the EXAFS spectrum.

The importance of arterial blood gas analysis as a systemic diagnosis approach in assessing and preventing chronic diseases, from emergency medicine to the daily practice.

Blood gas analysis is a diagnostic tool to evaluate the partial pressures of gas in blood and acid-base content. The use of blood gas analysis enables a clear understanding of respiratory, circulatory, and metabolic disorders. The arterial blood gas (ABG) explicitly analyzes blood taken from an artery, assessing the patient's partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2) pH (acid/base). PaO2 indicates the oxygenation status, and PaCO2 indicates the ventilation status (chronic or acute respiratory failure). PaO2 is affected by hyperventilation, characterized by rapid or deep breathing, and hypoventilation, characterized by slow or shallow breathing. The acid-base balance tested by the ABG procedure measures the pH and PaCO2 directly, while the use of the Hasselbach equation gives the serum bicarbonate (HCO3) and base deficit or excess. The measured HCO3 is based on a strong alkali that frees all CO2 in serum, including dissolved CO2, carbamino compounds, and carbonic acid. The calculation uses a standard chemistry analysis, giving the amount of "total CO2"; the difference will amount to around 1.2 mmol/L. Though ABG is frequently ordered in emergency medicine contests for acute conditions, it may also be needed in other clinical settings. The ABG analysis shows to be an exceptional diagnostic tool, including the group of diseases known as acid-base diseases (ABDs), which include a great variety of conditions such as severe sepsis, septic shock, hypovolemic shock, diabetic ketoacidosis, renal tubular acidosis, chronic respiratory failure, chronic heart failure, and diverse metabolic diseases.

Soft tissue regeneration in animal models using grafts from adipose mesenchymal stem cells and peripheral blood fibrin gel.

OBJECTIVE: Our study aimed to evaluate the effect of soft tissue regeneration in nude mice using grafts made from the combination of adipocytes from fat tissue mesenchymal stem cells and fibrin gel from peripheral blood. MATERIALS AND METHODS: Mesenchymal stem cells were isolated from adipose tissue and identified according to ISCT criteria. The scaffold used was fibrin obtained from peripheral blood. The grafts in this study were generated by transferring mesenchymal stem cells onto a fibrin scaffold. Two types of grafts, the research sample (fibrin scaffold containing adipocytes differentiated from mesenchymal stem cells) and the control sample (fibrin scaffold only), were grafted under the dorsal skin of the same mouse. After each research period, samples were collected and evaluated by histological methods to observe the existence and growth of cells inside the grafts. RESULTS: The results showed that the study group's graft integrated better within the tissue when compared with the control group. In addition, the grafts in the study group showed the presence of cells with characteristic morphology of adipocytes one week after transplantation. In contrast, control samples showed dimorphous shapes and features mainly composed of non-homogenous fragments. CONCLUSIONS: These initial conclusions might be considered a first step in generating safe bio-compatible engineered grafts specifically usable in post-traumatic tissue regeneration procedures.

A six-month intervention with two different types of micronutrient-fortified complementary foods had distinct short- and long-term effects on linear and ponderal growth of Vietnamese infants.

Traditional complementary foods (CF) with a low nutrient density have been implicated in growth faltering, stunting, and other adverse outcomes in children. The efficacy of 2 types of locally produced, micronutrient-fortified CF to prevent stunting of infants living in rural Vietnam was evaluated. In a village-randomized controlled study, 426 infants, 5 mo of age, received for 6 mo a fortified CF, either as an instant flour (FF) or a food complement (FC) in village canteens, or traditional CF at home (C). After 6 mo of intervention, weight, length, length-for-age Z-score (LAZ) and weight-for-age Z-score were greater in the 2 intervention groups compared with the C group, with an estimated effect of +0.22 LAZ for the FF group and +0.21 LAZ for the FC group. At the last follow-up, 18 mo after the intervention, there was no significant difference in height-for-age Z-score (HAZ) between the groups, even though the HAZ in the FF group was 0.17 greater than that in the C group (P = 0.18). In contrast, the weight-for-height Z-score and BMI Z-score, indices of ponderal growth, were greater in the FF group (-0.49 and -0.26, respectively) than in the FC group (-0.73 and -0.49, respectively), with Z-scores in the C group intermediate and not significantly different from the others. This study shows that regular provision of locally produced CF fortified with micronutrients partly stopped growth faltering in Vietnamese infants, with differential effects on long-term length and ponderal growth. Providing only micronutrients instead of a complete array of nutrients might result in only short-term length growth benefits.

A Hybrid Catheter Localisation Framework in Echocardiography Based on Electromagnetic Tracking and Deep Learning Segmentation.

Interventional cardiology procedure is an important type of minimally invasive surgery that deals with the catheter-based treatment of cardiovascular diseases, such as coronary artery diseases, strokes, peripheral arterial diseases, and aortic diseases. Ultrasound imaging, also called echocardiography, is a typical imaging tool that monitors catheter puncturing. Localising a medical device accurately during cardiac interventions can help improve the procedure's safety and reliability under ultrasound imaging. However, external device tracking and image-based tracking methods can only provide a partial solution. Thus, we proposed a hybrid framework, with the combination of both methods to localise the catheter tip target in an automatic way. The external device used was an electromagnetic tracking system from North Digital Inc (NDI), and the ultrasound image analysis was based on UNet, a deep learning network for semantic segmentation. From the external method, the tip's location was determined precisely, and the deep learning platform segmented the exact catheter tip automatically. This novel hybrid localisation framework combines the advantages of external electromagnetic (EM) tracking and the deep learning-based image method, which offers a new solution to identify the moving medical device in low-resolution ultrasound images.

First principles prediction of two-dimensional Janus XMoGeN2 (X = S, Se and Te) materials.

Motivated by the successful synthesis of two-dimensional MoSi2N4 [Y.-L. Hong et al., Science, 2020, 369, 670-674] and Janus MoSSe [A.-Y. Lu et al., Nat. Nanotechnol., 2017, 12, 744-749], in this work, we propose novel 2D Janus XMoGeN2 (X = S, Se and Te) monolayers using first-principles prediction. The controllable electronic features of Janus XMoGeN2 (X = S, Se and Te) monolayers under an external electric field and strain are also examined. Our predictions demonstrated that 2D XMoGeN2 materials are structurally and dynamically stable. All these 2D XMoGeN2 materials are indirect semiconductors with band gaps of 1.60/2.10, 1.54/2.07 and 1.05/1.56 eV obtained by the PBE/HSE functional for SMoGeN2, SeMoGeN2 and TeMoGeN2 monolayers, respectively. Furthermore, the electronic band gap and band structures of these monolayers are controllable under an external electric field and strain, making them promising candidates for flexible optoelectronics and nanoelectronics. The electric field tunes the TeMoGeN2 monolayer from semiconductor to metal and leads to a change in the band gap. While strain modifies the band gap of the TeMoGeN2 monolayer, giving rise to a shift in the CB from the Γ-M path to the M point and a tendency to transform from semiconductor to metal. Our findings suggest that these novel 2D XMoGeN2 materials are potential candidates for use in future high-performance applications.

Electronic structure and interface contact of two-dimensional van der Waals boron phosphide/Ga2SSe heterostructures.

In this work, we systematically examine the electronic features and contact types of van der Waals heterostructures (vdWHs) combining single-layer boron phosphide (BP) and Janus Ga2SSe using first-principles calculations. Owing to the out-of-plane symmetry being broken, the BP/Ga2SSe vdWHs are divided into two different stacking patterns, which are BP/SGa2Se and BP/SeGa2S. Our results demonstrate that these stacking patterns are structurally and mechanically stable. The combination of single-layer BP and Janus Ga2SSe gives rise to an enhancement in the Young's modulus compared to the constituent monolayers. Furthermore, at the ground state, the BP/Ga2SSe vdWHs possess a type-I (straddling) band alignment, which is desired for next-generation optoelectronic applications. The interlayer separation and electric field are effectively used to tune the electronic features of the BP/Ga2SSe vdWH from the type-I to type-II band alignment, and from semiconductor to metal. Our findings show that the BP/Ga2SSe vdWH would be appropriate for next-generation multifunctional optoelectronic and photovoltaic devices.