Ordered Assembly of DNA on Topological Insulator Bi2Se3 and Octadecylamine for a Sensitive Biosensor.

Controlling the assembly of DNA in order on a suitable electrode surface is of great significance for biosensors and disease diagnosis, but it is full of challenges. In this work, we creatively assembled DNA on the surface of octadecylamine (ODA)-modified topological insulator (Tls) Bi2Se3 and developed an electrochemical biosensor to detect biomarker DNA of coronavirus disease 2019 (COVID-19). A high-quality Bi2Se3 sheet was obtained from a single crystal synthesized in our lab. A uniform ODA layer was coated in argon by chemical vapor deposition (CVD). We observed and analyzed the assembly and mechanism of single-strand DNA (ssDNA) and double-strand DNA (dsDNA) on the Bi2Se3 surface through atomic force microscopy (AFM) and molecular dynamics (MD) simulations. The electrochemical signal revealed that the biosensor based on the DNA/ODA/Bi2Se3 electrode has a wide linear detection range from 1.0 × 10-12 to 1.0 × 10-8 M, with the limit of detection as low as 5 × 10-13 M. Bi2Se3 has robust surface states and improves the electrochemical signal-to-noise ratio, while the uniform ODA layer guides high-density ordered DNA, enhancing the sensitivity of the biosensor. Our work demonstrates that the ordered DNA/ODA/Bi2Se3 electrode surface has great application potential in the field of biosensing and disease diagnosis.

Risks of Occupational-Related Adverse Events (ORAEs) and Effect of Bundled Interventions Among Health Care Workers in Novel Coronavirus Pneumonia Wards.

OBJECTIVE: The aims of the study were to investigate the burden for health care workers (HCWs) who suffer from occupational-related adverse events (ORAEs) while working in contaminated areas in a specialized hospital for novel coronavirus pneumonia, to explore related risk factors, to evaluate the effectiveness of bundled interventions, as well as to provide scientific evidence regarding the reduction of risks concerning ORAEs and occupational exposure events. METHODS: The study was completed using a special team of 138 HCWs assembled for a specialized hospital for novel coronavirus pneumonia in Wuhan, dated from February 16 to March 26, 2020. The incidence of occupational exposure was determined by data reported from the hospital, while the prevalence of ORAEs was derived from questionnaire results. The relation coefficients of ORAEs and the variable potential risk factors are analyzed by logistic regression. After the risk factors were identified, targeted organized intervention was implemented and chi-square tests were performed to compare the incidence of occupational exposure and the prevalence of ORAEs in contaminated areas before and after the interventions. RESULTS: Ninety one out of 138 (65.94%) had reported ORAEs with 300 (27.96%) cases of ORAEs being recorded in a total of 1073 entries into contaminated areas. The prevalence of different ORAEs include 205 tenderness (24.73%), 182 headache/dizziness (21.95%), 138 dyspnea (16.65%), 130 blurred vision (15.68%), and 95 nausea/vomiting (11.46%). Personal protective equipment (PPE) is significantly associated with ORAEs in contaminated areas (P < 0.05). Among non-PPE-related factors, insomnia is associated with the majority of ORAEs in contaminated areas. Significant differences were achieved after organized interventions in the incidence of occupational exposure of HCWs (χ2 = 39.07, P < 0.001) and the prevalence of ORAEs in contaminated areas (χ2 = 22.95, P < 0.001). CONCLUSION: During the epidemic period of novel severe respiratory infectious disease, the burden of the ORAEs in contaminated areas and the risk of occupational exposure of HCWs were relatively high. In time, comprehensive and multi-level bundled interventions may help decrease the risk of both ORAEs and occupational exposure.

Field-effect at electrical contacts to two-dimensional materials.

The inferior electrical contact to two-dimensional (2D) materials is a critical challenge for their application in post-silicon very large-scale integrated circuits. Electrical contacts were generally related to their resistive effect, quantified as contact resistance. With a systematic investigation, this work demonstrates a capacitive metal-insulator-semiconductor (MIS) field-effect at the electrical contacts to 2D materials: The field-effect depletes or accumulates charge carriers, redistributes the voltage potential, and gives rise to abnormal current saturation and nonlinearity. On one hand, the current saturation hinders the devices' driving ability, which can be eliminated with carefully engineered contact configurations. On the other hand, by introducing the nonlinearity to monolithic analog artificial neural network circuits, the circuits' perception ability can be significantly enhanced, as evidenced using a coronavirus disease 2019 (COVID-19) critical illness prediction model. This work provides a comprehension of the field-effect at the electrical contacts to 2D materials, which is fundamental to the design, simulation, and fabrication of electronics based on 2D materials. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material (results of the simulation and SEM) is available in the online version of this article at 10.1007/s12274-021-3670-y.

Structure analysis of the receptor binding of 2019-nCoV.

2019-nCoV is a newly identified coronavirus with high similarity to SARS-CoV. We performed a structural analysis of the receptor binding domain (RBD) of spike glycoprotein responsible for entry of coronaviruses into host cells. The RBDs from the two viruses share 72% identity in amino acid sequences, and molecular simulation reveals highly similar ternary structures. However, 2019-nCoV has a distinct loop with flexible glycyl residues replacing rigid prolyl residues in SARS-CoV. Molecular modeling revealed that 2019-nCoV RBD has a stronger interaction with angiotensin converting enzyme 2 (ACE2). A unique phenylalanine F486 in the flexible loop likely plays a major role because its penetration into a deep hydrophobic pocket in ACE2. ACE2 is widely expressed with conserved primary structures throughout the animal kingdom from fish, amphibians, reptiles, birds, to mammals. Structural analysis suggests that ACE2 from these animals can potentially bind RBD of 2019-nCoV, making them all possible natural hosts for the virus. 2019-nCoV is thought to be transmitted through respiratory droplets. However, since ACE2 is predominantly expressed in intestines, testis, and kidney, fecal-oral and other routes of transmission are also possible. Finally, antibodies and small molecular inhibitors that can block the interaction of ACE2 with RBD should be developed to combat the virus.

Beyond the virus: a first look at coronavirus-themed Android malware.

As the COVID-19 pandemic emerged in early 2020, a number of malicious actors have started capitalizing the topic. Although a few media reports mentioned the existence of coronavirus-themed mobile malware, the research community lacks the understanding of the landscape of the coronavirus-themed mobile malware. In this paper, we present the first systematic study of coronavirus-themed Android malware. We first make efforts to create a daily growing COVID-19 themed mobile app dataset, which contains 4,322 COVID-19 themed apk samples (2,500 unique apps) and 611 potential malware samples (370 unique malicious apps) by the time of mid-November, 2020. We then present an analysis of them from multiple perspectives including trends and statistics, installation methods, malicious behaviors and malicious actors behind them. We observe that the COVID-19 themed apps as well as malicious ones began to flourish almost as soon as the pandemic broke out worldwide. Most malicious apps are camouflaged as benign apps using the same app identifiers (e.g., app name, package name and app icon). Their main purposes are either stealing users' private information or making profit by using tricks like phishing and extortion. Furthermore, only a quarter of the COVID-19 malware creators are habitual developers who have been active for a long time, while 75% of them are newcomers in this pandemic. The malicious developers are mainly located in the US, mostly targeting countries including English-speaking countries, China, Arabic countries and Europe. To facilitate future research, we have publicly released all the well-labelled COVID-19 themed apps (and malware) to the research community. Till now, over 30 research institutes around the world have requested our dataset for COVID-19 themed research.

[Experts recommendation on the diagnosis and treatment of oral mucosal diseases during prevention and control stage of the novel coronavirus infection]

The announcement of National Health Commission on January 20, 2020 (No. 1 of 2020) has included Novel Coronavirus Pneumonia(NCP) into the B class infectious diseases according to the law of the People's Republic of China on the prevention and control of infectious diseases, and has been managed as A class infectious diseases. People's governments at all levels and health administration departments have been paying high attention to it, and medical and health institutions have taken a series of prevention and control measures according to the law to prevent and control the spread of NCP. In the process of combating the outbreak of NCP, how to protect the oral mucosal disease physicians normatively, how to ensure hand and environmental cleaning and disinfection;how to carry out triage of the patients with oral mucosal disease accompanied by fever reasonably;how to carry out oral mucosal disease patients'self-care and self-management during this stage, are the practical problems that all levels of medical institutions and medical workers and patients will meet. For these three problems, we invited the experts from the Society of Oral Medicine, Shanghai Stomatological Association and the Oral Mucosal Disease Specialist Alliance Organization of Shanghai Ninth People's Hospital Group to write the recommendation on the diagnosis and treatment of oral mucosal disease during prevention and control stage of novel coronavirus infection, in order to provide references for oral mucosal disease medical physicians and patients in this special period. This recommendation will be updated according to the situation of epidemic prevention and control in China and the new relevant diagnosis and treatment plans.