Lei Zhang

Bio: Lei Zhang is an academic researcher from Central South University. The author has contributed to research in topics: Population & Medicine. The author has an hindex of 51, co-authored 588 publications receiving 11345 citations. Previous affiliations of Lei Zhang include Monash University & Kirby Institute.

Broadband polarization-independent perfect absorber using a phase-change metamaterial at visible frequencies.

Abstract: We report a broadband polarization-independent perfect absorber with wide-angle near unity absorbance in the visible regime. Our structure is composed of an array of thin Au squares separated from a continuous Au film by a phase change material (Ge2Sb2Te5) layer. It shows that the near perfect absorbance is flat and broad over a wide-angle incidence up to 80° for either transverse electric or magnetic polarization due to a high imaginary part of the dielectric permittivity of Ge2Sb2Te5. The electric field, magnetic field and current distributions in the absorber are investigated to explain the physical origin of the absorbance. Moreover, we carried out numerical simulations to investigate the temporal variation of temperature in the Ge2Sb2Te5 layer and to show that the temperature of amorphous Ge2Sb2Te5 can be raised from room temperature to > 433 K (amorphous-to-crystalline phase transition temperature) in just 0.37 ns with a low light intensity of 95 nW/μm2, owing to the enhanced broadband light absorbance through strong plasmonic resonances in the absorber. The proposed phase-change metamaterial provides a simple way to realize a broadband perfect absorber in the visible and near-infrared (NIR) regions and is important for a number of applications including thermally controlled photonic devices, solar energy conversion and optical data storage.

HIV prevalence in China: integration of surveillance data and a systematic review.

Abstract: Summary Background Asian HIV epidemics are concentrated among particular behavioural groups, but large variations exist in epidemic types, timing, and geographical spread between countries and within countries, especially in China. We aimed to understand the complexity of HIV epidemics in China by systematically analysing prevalence trends by data source, region, population group, and time period. Methods We collected HIV prevalence data from official national sentinel surveillance sites at the provincial level from Jan 1, 1995, to Dec 31, 2010. We also searched PubMed, VIP Chinese Journal Database (VIP), China National Knowledge Infrastructure, and Wanfang Data from Jan 1, 1990, to Dec 31, 2012, for independent studies of HIV prevalence. We integrated both sets of data, and used an intraclass correlation coefficient test to assess the similarity of geographical pattern of HIV disease burden across 31 Chinese provinces in 2010. We investigated prevalence trends (and 95% CIs) to infer corresponding incidence by region, population group, and year. Findings Of 6850 articles identified by the search strategy, 821 studies (384 583 drug users, 52 356 injecting drug users, 186 288 female sex workers, and 87 834 men who have sex with men) met the inclusion criteria. Official surveillance data and findings from independent studies showed a very similar geographical distribution and magnitude of HIV epidemics across China. We noted that HIV epidemics among injecting drug users are decreasing in all regions outside southwest China and have stabilised at a high level in northwest China. Compared with injecting drug users, HIV prevalence in female sex workers is much lower and has stabilised at low levels in all regions except in the southwest. In 2010, national HIV prevalence was 9·08% (95% CI 8·04–10·52) in injecting drug users and 0·36% (0·12–0·71) in female sex workers, whereas incidence in both populations stabilised at rates of 0·57 (0·43–0·72) and 0·02 (0·01–0·04) per 100 person-years, respectively. By comparison, HIV prevalence in men who have sex with men increased from 1·77% (1·26–2·57) in 2000, to 5·98% (4·43–8·18) in 2010, with a national incidence of 0·98 (0·70–1·25) per 100 person-years in 2010. We recorded strong associations between HIV prevalence among at-risk populations in each province, supporting the existence of overlap in risk behaviours and mixing among these populations. Interpretation HIV epidemics in China remain concentrated in injecting drug users, female sex workers, and men who have sex with men. HIV prevalence is especially high in southwest China. Sex between men has clearly become the main route of HIV transmission. Funding The World Bank Group, the Australian Research Council, the University of New South Wales, and Chinese Center for Disease Control and Prevention.

Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury

Abstract: Acute kidney injury (AKI) is a complex disorder for which currently there is no accepted definition. Having a uniform standard for diagnosing and classifying AKI would enhance our ability to manage these patients. Future clinical and translational research in AKI will require collaborative networks of investigators drawn from various disciplines, dissemination of information via multidisciplinary joint conferences and publications, and improved translation of knowledge from pre-clinical research. We describe an initiative to develop uniform standards for defining and classifying AKI and to establish a forum for multidisciplinary interaction to improve care for patients with or at risk for AKI. Members representing key societies in critical care and nephrology along with additional experts in adult and pediatric AKI participated in a two day conference in Amsterdam, The Netherlands, in September 2005 and were assigned to one of three workgroups. Each group's discussions formed the basis for draft recommendations that were later refined and improved during discussion with the larger group. Dissenting opinions were also noted. The final draft recommendations were circulated to all participants and subsequently agreed upon as the consensus recommendations for this report. Participating societies endorsed the recommendations and agreed to help disseminate the results. The term AKI is proposed to represent the entire spectrum of acute renal failure. Diagnostic criteria for AKI are proposed based on acute alterations in serum creatinine or urine output. A staging system for AKI which reflects quantitative changes in serum creatinine and urine output has been developed. We describe the formation of a multidisciplinary collaborative network focused on AKI. We have proposed uniform standards for diagnosing and classifying AKI which will need to be validated in future studies. The Acute Kidney Injury Network offers a mechanism for proceeding with efforts to improve patient outcomes.

Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study

Abstract: Summary Background Since December, 2019, Wuhan, China, has experienced an outbreak of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Epidemiological and clinical characteristics of patients with COVID-19 have been reported but risk factors for mortality and a detailed clinical course of illness, including viral shedding, have not been well described. Methods In this retrospective, multicentre cohort study, we included all adult inpatients (≥18 years old) with laboratory-confirmed COVID-19 from Jinyintan Hospital and Wuhan Pulmonary Hospital (Wuhan, China) who had been discharged or had died by Jan 31, 2020. Demographic, clinical, treatment, and laboratory data, including serial samples for viral RNA detection, were extracted from electronic medical records and compared between survivors and non-survivors. We used univariable and multivariable logistic regression methods to explore the risk factors associated with in-hospital death. Findings 191 patients (135 from Jinyintan Hospital and 56 from Wuhan Pulmonary Hospital) were included in this study, of whom 137 were discharged and 54 died in hospital. 91 (48%) patients had a comorbidity, with hypertension being the most common (58 [30%] patients), followed by diabetes (36 [19%] patients) and coronary heart disease (15 [8%] patients). Multivariable regression showed increasing odds of in-hospital death associated with older age (odds ratio 1·10, 95% CI 1·03–1·17, per year increase; p=0·0043), higher Sequential Organ Failure Assessment (SOFA) score (5·65, 2·61–12·23; p Interpretation The potential risk factors of older age, high SOFA score, and d-dimer greater than 1 μg/mL could help clinicians to identify patients with poor prognosis at an early stage. Prolonged viral shedding provides the rationale for a strategy of isolation of infected patients and optimal antiviral interventions in the future. Funding Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences; National Science Grant for Distinguished Young Scholars; National Key Research and Development Program of China; The Beijing Science and Technology Project; and Major Projects of National Science and Technology on New Drug Creation and Development.