Analysis of p-Type Doping in Graphene Induced by Monolayer-Oxidized TMDs.

Doping is one of the most difficult technological challenges for realizing reliable two-dimensional (2D) material-based semiconductor devices, arising from their ultrathinness. Here, we systematically investigate the impact of different types of nonstoichiometric solid MOx (M are W or Mo) dopants obtained by oxidizing transition metal dichalcogenides (TMDs: WSe2 or MoS2) formed on graphene FETs, which results in p-type doping along with disorders. From the results obtained in this study, we were able to suggest an analytical technique to optimize the optimal UV-ozone (UVO) treatment to achieve high p-type doping concentration in graphene FETs (∼2.5 × 1013 cm-2 in this study) without generating defects, mainly by analyzing the time dependency of D and D' peaks measured by Raman spectroscopy. Furthermore, an analysis of the structure of graphene sheets using TEM indicates that WOx plays a better protective role in graphene, compared to MoOx, suggesting that WOx is more effective for preventing the degradation of graphene during UVO treatment. To enhance the practical application aspect of our work, we have fabricated a graphene photodetector by selectively doping the graphene through oxidized TMDs, creating a p-n junction, which resulted in improved photoresponsivity compared to the intrinsic graphene device. Our results offer a practical guideline for the utilization of surface charge transfer doping of graphene toward CMOS applications.

Escalating Ferromagnetic Order via Se-Vacancies Near Vanadium in WSe2 Monolayers.

Magnetic order has been proposed to arise from a variety of defects, including vacancies, antisites, and grain boundaries, which are relevant in numerous electronics and spintronics applications. Nevertheless, its magnetism remains controversial due to the lack of structural analysis. The escalation of ferromagnetism in vanadium-doped WSe2 monolayer is herein demonstrated by tailoring complex configurations of Se vacancies (SeVac ) via post heat-treatment. Structural analysis of atomic defects is systematically performed using transmission electron microscopy (TEM), enabled by the monolayer nature. Temperature-dependent magnetoresistance hysteresis ensures enhanced magnetic order after high-temperature heat-treatment, consistent with magnetic domain analysis from magnetic force microscopy (MFM). The vanadium-Se vacancy pairing is a key to promoting ferromagnetism via spin-flip by electron transfer, predicted from density-functional-theory (DFT) calculations. The approach toward nanodefect engineering paves a way to overcome weak magnetic order in diluted magnetic semiconductors (DMSs) for renovating semiconductor spintronics.

Spin-Selective Hole-Exciton Coupling in a V-Doped WSe2 Ferromagnetic Semiconductor at Room Temperature.

While valley polarization with strong Zeeman splitting is the most prominent characteristic of two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors under magnetic fields, enhancement of the Zeeman splitting has been demonstrated by incorporating magnetic dopants into the host materials. Unlike Fe, Mn, and Co, V is a distinctive dopant for ferromagnetic semiconducting properties at room temperature with large Zeeman shifting of band edges. Nevertheless, little known is the excitons interacting with spin-polarized carriers in V-doped TMDs. Here, we report anomalous circularly polarized photoluminescence (CPL) in a V-doped WSe2 monolayer at room temperature. Excitons couple to V-induced spin-polarized holes to generate spin-selective positive trions, leading to differences in the populations of neutral excitons and trions between left and right CPL. Using transient absorption spectroscopy, we elucidate the origin of excitons and trions that are inherently distinct for defect-mediated and impurity-mediated trions. Ferromagnetic characteristics are further confirmed by the significant Zeeman splitting of nanodiamonds deposited on the V-doped WSe2 monolayer.

Gate-Tunable Magnetism via Resonant Se-Vacancy Levels in WSe2.

The confined defects in 2D van der Waals (vdW)-layered semiconductors can be easily tailored using charge doping, strain, or an electric field. Nevertheless, gate-tunable magnetic order via intrinsic defects has been rarely observed to date. Herein, a gate-tunable magnetic order via resonant Se vacancies in WSe2 is demonstrated. The Se-vacancy states are probed via photocurrent measurements with gating to convert unoccupied states to partially occupied states associated with photo-excited carrier recombination. The magneto-photoresistance hysteresis is modulated by gating, which is consistent with the density functional calculations. The two energy levels associated with Se vacancies split with increasing laser power, owing to the robust Coulomb interaction and strong spin-orbit coupling. The findings offer a new approach for controlling the magnetic properties of defects in optoelectronic and spintronic devices using vdW-layered semiconductors.

Deployable Telescopic Tubular Mechanisms With a Steerable Tongue Depressor Towards Self-Administered Oral Swab.

Swabbing tests have proved to be an effective method of diagnosis for a wide range of diseases. Potential occupational health hazards and reliance on healthcare workers during traditional swabbing procedures can be mitigated by self-administered swabs. Hence, we report possible methods to apply closed kinematic chain theory to develop a self-administered viral swab to collect respiratory specimens. The proposed sensorized swab models utilizing hollow polypropylene tubes possess mechanical compliance, simple construction, and inexpensive components. In detail, the adaptation of the slider-crank mechanism combined with concepts of a deployable telescopic tubular mechanical system is explored through four different oral swab designs. A closed kinematic chain on suitable material to create a developable surface allows the translation of simple two-dimensional motion into more complex multi-dimensional motion. These foldable telescopic straws with multiple kirigami cuts minimize components involved in the system as the characteristics are built directly into the material. Further, it offers a possibility to include soft stretchable sensors for realtime performance monitoring. A variety of features were constructed and tested using the concepts above, including 1) tongue depressor and cough/gag reflex deflector; 2) changing the position and orientation of the oral swab when sample collection is in the process; 3) protective cover for the swabbing bud; 4) a combination of the features mentioned above.

Medication Errors in Vietnamese Hospitals: Prevalence, Potential Outcome and Associated Factors.

BACKGROUND: Evidence from developed countries showed that medication errors are common and harmful. Little is known about medication errors in resource-restricted settings, including Vietnam. OBJECTIVES: To determine the prevalence and potential clinical outcome of medication preparation and administration errors, and to identify factors associated with errors. METHODS: This was a prospective study conducted on six wards in two urban public hospitals in Vietnam. Data of preparation and administration errors of oral and intravenous medications was collected by direct observation, 12 hours per day on 7 consecutive days, on each ward. Multivariable logistic regression was applied to identify factors contributing to errors. RESULTS: In total, 2060 out of 5271 doses had at least one error. The error rate was 39.1% (95% confidence interval 37.8%- 40.4%). Experts judged potential clinical outcomes as minor, moderate, and severe in 72 (1.4%), 1806 (34.2%) and 182 (3.5%) doses. Factors associated with errors were drug characteristics (administration route, complexity of preparation, drug class; all p values < 0.001), and administration time (drug round, p = 0.023; day of the week, p = 0.024). Several interactions between these factors were also significant. Nurse experience was not significant. Higher error rates were observed for intravenous medications involving complex preparation procedures and for anti-infective drugs. Slightly lower medication error rates were observed during afternoon rounds compared to other rounds. CONCLUSIONS: Potentially clinically relevant errors occurred in more than a third of all medications in this large study conducted in a resource-restricted setting. Educational interventions, focusing on intravenous medications with complex preparation procedure, particularly antibiotics, are likely to improve patient safety.

Modified electrodes used for electrochemical detection of metal ions in environmental analysis.

Heavy metal pollution is one of the most serious environmental problems, and regulations are becoming stricter. Many efforts have been made to develop sensors for monitoring heavy metals in the environment. This review aims at presenting the different label-free strategies used to develop electrochemical sensors for the detection of heavy metals such as lead, cadmium, mercury, arsenic etc. The first part of this review will be dedicated to stripping voltammetry techniques, on unmodified electrodes (mercury, bismuth or noble metals in the bulk form), or electrodes modified at their surface by nanoparticles, nanostructures (CNT, graphene) or other innovative materials such as boron-doped diamond. The second part will be dedicated to chemically modified electrodes especially those with conducting polymers. The last part of this review will focus on bio-modified electrodes. Special attention will be paid to strategies using biomolecules (DNA, peptide or proteins), enzymes or whole cells.

The effect of a clinical pharmacist-led training programme on intravenous medication errors: a controlled before and after study.

BACKGROUND: Little is known about interventions to reduce intravenous medication administration errors in hospitals, especially in low- and middle-income countries. OBJECTIVE: To assess the effect of a clinical pharmacist-led training programme on clinically relevant errors during intravenous medication preparation and administration in a Vietnamese hospital. METHODS: A controlled before and after study with baseline and follow-up measurements was conducted in an intensive care unit (ICU) and a post-surgical unit (PSU). The intervention comprised lectures, practical ward-based teaching sessions and protocols/guidelines, and was conducted by a clinical pharmacist and a nurse. Data on intravenous medication preparation and administration errors were collected by direct observation 12 h/day for seven consecutive days. Generalised estimating equations (GEE) were used to assess the effect of the intervention on the prevalence of clinically relevant erroneous doses, corrected for confounding factors. RESULTS: 1204 intravenous doses were included, 516 during the baseline period (236 on ICU and 280 on PSU) and 688 during the follow-up period (407 on ICU and 281 on PSU). The prevalence of clinically relevant erroneous doses decreased significantly on the intervention ward (ICU) from 64.0% to 48.9% (p<0.001) but was unchanged on the control ward (PSU) (57.9% vs 64.1%; p=0.132). GEE analysis showed that doses on the intervention ward were 2.60 (1.27-5.31) times less likely to have clinically relevant errors (p=0.013). CONCLUSIONS: The pharmacist-led training programme was effective, but the error rate remained relatively high. Further quality improvement strategies are needed, including changes to the working environment and promotion of a safety culture.

Errors in preparation and administration of insulin in two urban Vietnamese hospitals: an observational study.

BACKGROUND: Medication errors involving insulin are common, particularly during the administration stage, and may cause severe harm. Little is known about the prevalence of insulin administration errors in hospitals, especially in resource-restricted settings, where the burden of diabetes is growing alarmingly. OBJECTIVES: The aim of this study was to determine the prevalence, type, and potential clinical outcome of errors in preparation and administration of insulin in resource-restricted setting hospitals. METHODS: This study was conducted on six wards in two urban public hospitals in Vietnam using a direct observation method. Details of insulin preparation and administration were collected by pharmacy students 12 hours per day for 7 consecutive days on each ward. Potential clinical outcome was judged by a panel of four experts using a validated scale. RESULTS: The error rate was 28.8% (95% confidence interval [23.1%, 35.2%], n = 66 out of 229 insulin doses)-all with potentially moderate/severe outcome. Higher error rates were observed for infusion doses than for subcutaneous ones (80.0% vs. 22.5%, p < .01). Incorrect time, incorrect preparation/administration technique, and omissions were mostly encountered. DISCUSSION: Interventions suitable for resource-restricted settings need to be developed and tested to improve insulin preparation and administration, probably starting with education and providing information, especially infusion doses.

Cryptic Streptococcus mutans 5.6-kb plasmids encode a toxin-antitoxin system for plasmid stabilization.

BACKGROUND: In all Streptococcus mutans strains, 5-13% carry a 5.6-kb plasmid. Despite its frequency, little is known about its mediated functions with most of the information coming from a single study focussing on plasmid pUA140. OBJECTIVE: Here, we describe the sequence and genetic organization of two S. mutans 5.6-kb plasmids, pDC09 and pNC101. RESULTS: Based on PicoGreen dsDNA quantification and Real-Time quantitative PCR (RTQ-PCR), the plasmid copy number was found to range between 10 and 74, depending on the strain tested. In contrast to literature, we identified six instead of five open reading frames (ORFs). While the putative gene products of ORF1 (as a Rep-protein) and ORF2 (as a Mob-protein) could be confirmed as being identical to those from pUA140, the functions of ORF3 (unknown) and ORF 4 (possibly AtpE homologue) could not be further revealed. However, the product of ORF5 showed a fairly high identity (38-50%) and structural similarity (58-74%) to RelE of Streptococcus pneumoniae, Streptococcus equi, and Streptococcus downei. In addition, we identified a functionally corresponding ORF6 encoding a protein with 61-68% identity (81-86% similarity) to the S. equi and S. downei antitoxin of the RelB family. RelE and RelB together form a plasmid-encoded toxin-antitoxin (TA) system, RelBE(plas). Despite its rather limited sequence similarity with chromosomal TA systems in S. mutans (RelBE(chro), MazEF, HicBA), we found similar tertiary structures applying I-Tasser protein prediction analysis. CONCLUSION: Type II-toxins, as the plasmid-encoded RelE, are RNA endonucleases. Depending on their mRNA cleavage activity, they might 1) kill every plasmid-free progeny, thereby stabilizing plasmid transfer at the expense of the host and/or 2) help S. mutans enter a dormant state and survive unfavourable environmental conditions. Whilst a function in plasmid stabilization has been confirmed, a function in persistence under nutritional stress, tested here by inducing amino acid starvation, could not be demonstrated so far.