Thickness-dependent exciton relaxation dynamics of few-layer rhenium diselenide

Rhenium diselenide(ReSe_(2))has gathered much attention due to its low symmetry of lattice structure,which makes it possess in-plane anisotropic optical,electrical as well as excitonic properties and further enables ReSe_(2)have an important application in optoelectronic devices.Here,we report the thickness-dependent exciton relaxation dynamics of mechanically exfoliated few-layer ReSe_(2)flakes by using time-resolved pump–probe transient transmission spectroscopies.The results reveal two thickness-dependent relaxation processes of the excitons.The fast one correlates with the exciton formation(i.e.,the conversion of hot carriers to excitons),while the slow one is attributed to the exciton recombination dominated by defect-assisted exciton trapping besides photon emission channel.The decrease of scattering probability caused by defects leads to the increase of fast lifetime with thickness,and the increase of slow lifetime with thickness is related to the trap-mediated exciton depopulation induced by surface defects.Polarization-dependent transient spectroscopy indicates the isotropic exciton dynamics in the two-dimensional(2D)plane.These results are insightful for better understanding of excitonic dynamics of ReSe_(2)materials and its application in future optoelectronic and electronic devices.

Establishment of the Effectiveness of Follow-Up Protocols for Patients under COVID-19 Epidemic

Objectives: To control the Corona Virus Disease (COVID-19) epidemic, it is meaningful to improve the home quarantine ability and home-quarantine compliancy of patients released from medical isolation, and to prevent cross-contamination. This study aimed to up protocols for COVID-19 patients released from medical isolation. Methods: A total of 35 patients discharged from the isolation ward of the Third Affiliated Hospital of Guangzhou Sun Yat-sen University from January 22, 2020 to February 18, 2020 were included. The patients received health education through discharge preparation, education leaflets and videos. The patients were followed up on the 2nd, 7th and 14th day after discharge through WeChat and phone call. On the 2nd and 14th day after discharge, the patients completed the knowledge assessment, self-perceived burden survey and satisfaction survey using a self-made home quarantine knowledge paper. Results: There were statistical differences in the knowledge and understanding of home quarantine and self-perceived burden between the 2nd day and 14th day after home quarantine (P < 0.05). The completion rate of home quarantine was 94.3%, and the satisfaction rate was 96.7%. Conclusion: By improving the discharge preparation, conducting in-time follow-up after discharge via WeChat and phone call, and performing multi-channel health education, the follow-up researchers could help the patients perform a more effective home quarantine, which could effectively prevent the spread of COVID-19 epidemic.

Viral hepatitis E:Clinical manifestations,treatment,and prevention

Hepatitis E is a globally distributed infection that varies in seroprevalence between developed and developing regions.In the less developed regions of Asia and Africa,a high seropositivity rate has been reported for hepatitis E virus(HEV)antibodies.Although acute hepatitis E is often self-limited and has a favorable prognosis,some populations experience severe manifestations,which may progress to liver failure.Moreover,some immunocompromised patients are at risk of developing chronic HEV infection and cirrhosis.Proactive screening,reducing misdiagnosis,improving patient management,timely anti-viral therapy for severe and chronic cases,and vaccination of high-risk groups are important measures to reduce the morbidity of hepatitis E.This review focused on the clinical presentation,management,and prevention of hepatitis E.

Double Plasma Molecular Adsorption System with Sequential Low-dose Plasma Exchange in Patients with Hepatitis B Virus-related Acute-on-chronic Liver Failure:A Prospective Study

Background and Aims:To investigate the safety and efficacy of double plasma molecular adsorption system(DPMAS)with sequential low-dose plasma exchange(LPE)in treating early hepatitis B virus-related acute-on-chronic liver failure(HBV-ACLF).Methods:Clinical data of patients with HBVACLF were prospectively collected,including patients in a DPMAS with sequential LPE(DPMAS+LPE)group and those in a standard medical treatment(SMT)group.The primary endpoint was death or liver transplantation(LT)at 12 weeks of follow-up.Propensity-score matching was performed to control the effects of confounding factors on prognosis between the two groups.Results:After 2 weeks,total bilirubin,alanine aminotransferase,blood urea nitrogen levels,and Chinese Group on the Study of Severe Hepatitis B score,were significantly lower in the DPMAS+LPE group than those in the SMT group(p<0.05).After 4 weeks,laboratory parameters of the two groups were similar.The cumulative survival rate of the DPMAS+LPE group was significantly higher than that of the SMT group at 4 weeks(97.9%vs.85.4%,p=0.027),but not at 12 weeks(85.4%vs.83.3%,p=0.687).Cytokine levels were significantly lower in 12-week survival group than in the death-or-LT group(p<0.05).Functional enrichment analysis showed that downregulated cytokines were mainly involved in positive regulation of proliferation and activation of lymphocytes and monocytes,regulation of immune effect response,regulation of endotoxin response,and glial cell proliferation.Conclusion:DPMAS+LPE significantly improved the 4-week cumulative survival rate,and ameliorated the inflammatory response in patients.DPMAS+LPE may be a promising modality for patients with early HBV-ACLF.

All-optical generation,detection,and manipulation of picosecond acoustic pulses in 2D semiconductor/dielectric heterostructures

Launching,tracking,and controlling picosecond acoustic(PA)pulses are fundamentally important for the construction of ultrafast hypersonic wave sources,ultrafast manipulation of matter,and spatiotemporal imaging of interfaces.Here,we show that GHz PA pulses can be all-optically generated,detected,and manipulated in a 2D layered MoS_(2)∕glass heterostructure using femtosecond laser pump-probe.Based on an interferometric model,PA pulse signals in glass are successfully decoupled from the coexisting temperature and photocarrier relaxation and coherent acoustic phonon(CAP)oscillation signals of MoS_(2)lattice in both time and frequency domains.Under selective interface excitations,temperature-mediated interfacial phonon scatterings can compress PA pulse widths by about 50%.By increasing the pump fluences,anharmonic CAP oscillations of MoS_(2)lattice are initiated.As a result,the increased interatomic distance at the MoS_(2)∕glass interface that reduces interfacial energy couplings can markedly broaden the PA pulse widths by about 150%.Our results open new avenues to obtain controllable PA pulses in 2D semiconductor/dielectric heterostructures with femtosecond laser pump-probe,which will enable many investigations and applications.

Serum from Acute-on-chronic Liver Failure Patients May Affect Mesenchymal Stem Cells Transplantation by Impairing the Immunosuppressive Function of Cells

Background and Aims:The safety and efficacy of mesenchymal stem cells(MSCs)in the treatment of acute-onchronic liver failure(ACLF)have been validated.However,the impact of the pathological ACLF microenvironment on MSCs is less well understood.This study was designed to explore the changes in the functional properties of MSCs exposed to ACLF serum.Methods:MSCs were cultured in the presence of 10%,30%and 50%serum concentrations from ACLF patients and healthy volunteers.Then,the cell morphology,phenotype,apoptosis and proliferation of MSCs were evaluated,including the immunosuppressive effects.Subsequently,mRNA sequencing analysis was used to identify the molecules and pathways involved in MSC functional changes in the context of ACLF.Results:In the presence of ACLF serum,MSC morphology significantly changed but phenotype did not.Besides,MSC proliferation activity was weakened,while the apoptosis rate was lightly increased.Most importantly,the immunosuppressive function of MSCs was enhanced in a lowconcentration serum environment but transformed into a proinflammatory response in a high-concentration serum environment.RNA sequencing indicated that 10%serum concentration from ACLF patients mediated the PI3K-Akt pathway to enhance the anti-inflammatory effect of MSCs,while the 50%serum concentration from ACLF patients promoted the conversion of MSCs into a proinflammatory function by affecting the cell cycle.Conclusions:The 50%ACLF serum concentration is more similar to the environment in the human body,which means that direct peripheral blood intravenous infusion of MSCs may reduce the effect of transplantation.Combining treatments of plasma exchange to reduce harmful substances in serum may promote MSCs to exert a stronger anti-inflammatory effect.

Association between the nasopharyngeal microbiome and metabolome in patients with COVID-19

SARS-CoV-2,the causative agent for COVID-19,infect human mainly via respiratory tract,which is heavily inhabited by local microbiota.However,the interaction between SARS-CoV-2 and nasopharyngeal microbiota,and the association with metabolome has not been well characterized.Here,metabolomic analysis of blood,urine,and nasopharyngeal swabs from a group of COVID-19 and non-COVID-19 patients,and metagenomic analysis of pharyngeal samples were used to identify the key features of COVID-19.Results showed lactic acid,L-proline,and chlorogenic acid methyl ester(CME)were significantly reduced in the sera of COVID-19 patients compared with non-COVID-19 ones.Nasopharyngeal commensal bacteria including Gemella morbillorum,Gemella haemolysans and Leptotrichia hofstadii were notably depleted in the pharynges of COVID-19 patients,while Prevotella histicola,Streptococcus sanguinis,and Veillonella dispar were relatively increased.The abundance of G.haemolysans and L.hofstadii were significantly positively associated with serum CME,which might be an anti-SARS-CoV-2 bacterial metabolite.This study provides important information to explore the linkage between nasopharyngeal microbiota and disease susceptibility.The findings were based on a very limited number of patients enrolled in this study;a larger size of cohort will be appreciated for further investigation.

The relationship between zinc deficiency and infectious complications in patients with hepatitis B virus-related acute-on-chronic liver failure

Background The prevalence of zinc deficiency is high in patients with chronic liver disease,but few studies have hitherto explored the relationship between the serum zinc level and hepatitis B virus(HBV)-related acute-on-chronic liver failure(ACLF).This study aimed to assess the association between zinc deficiency and infectious complications,and model for end-stage liver disease(MELD)score in patients with HBV-related ACLF.Methods Patients with HBV-related ACLF from the Department of Infectious Diseases of the Third Affiliated Hospital of Sun Yat-sen University(Guangzhou,China)between January 2019 and December 2019 were retrospectively analysed in this study.Their demographic,clinical,and laboratory data were retrieved from the hospital information system and analysed.The Student’s t-test was used for normally distributed continuous variables between two groups and the Chi-square test was used for categorical data.Univariate and multivariate logistic regression analyses were applied to identify independent parameters.Results A total of 284 patients were included in this study,including 205 liver cirrhosis and 79 non-cirrhosis patients.The proportion of patients with zinc deficiency was the highest(84.5%),followed by subclinical zinc deficiency(14.1%)and normal zinc level(1.4%).Patients in the zinc deficiency group had a higher MELD score than the subclinical zinc deficiency or normal zinc group(P=0.021).Age,total bilirubin,and serum zinc level were independent factors for infection(P_(s)<0.05).The serum zinc level in patients without complications at admission was significantly higher than that in patients with complications(P=0.004).Moreover,the serum zinc level in patients with prothrombin time activity(PTA)of<20%was significantly lower than that in patients with 20%≤PTA<30%(P=0.007)and that in patients with 30%≤PTA<40%(P<0.001).Conclusions Zinc deficiency is common in patients with HBV-related ACLF.Zinc deficiency is closely associated with infectious complications and MELD score in patients with HBV-related ACLF.