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Comorbidities are important for the disease outcome of COVID‐19, however, which underlying diseases that contribute the most to aggravate the conditions of COVID‐19 patients are still unclear. Viral clearance is the most important laboratory test for defining the recovery of COVID‐19 infections. To better understand which underlying diseases that are risk factors for delaying the viral clearance, we retrospectively analyzed 161 COVID‐19 clinical cases in the Zhongnan Hospital of Wuhan University, Wuhan, China between January 5 and March 13, 2020. The demographic, clinical and laboratory data, as well as patient treatment records were collected. Univariable and multivariable analysis were performed to explore the association between delayed viral clearance and other factors by using logistic regression. Survival analyses by Kaplan‐Meier and Cox regression modeling were employed to identify factors negatively influencing the viral clearance negatively. We found that hypertension and intravenous immunoglobulin adversely affected the time of viral RNA shedding. Hypertension was the most important risk factor to delay the SARS‐CoV‐2 virus clearance, however, the use of Angiotensin‐Converting Enzyme Inhibitors(ACEI)/Angiotensin Receptor Blockers(ARB) did not shorten the time for virus clearance in these hypertensive patients’ virus clearance. We conclude that patients having hypertension and intravenous immunoglobulin may delay the viral clearance in COVID‐19 patients.

In addition to the recent emerged SARS-CoV-2, hepatitis B virus (HBV) is one of the viruses which cause a global infection and threat public health. In worldwide, the prevalence of HBsAg is about 3.9% (Polaris Observatory 2018). According to a nationwide epidemiological survey of population whose ages range from 1 to 59 years in China, 2006, the prevalence of HBsAg was 7.2% (Liang et al. 2009). As SARS-CoV-2 and HBV both can cause liver damage (Fan et al. 2020), further understanding of the risk of SARS-CoV-2 on patients with HBV infection is urgently required in order to design an optimized treatment strategy. However, the impacts of SARS-CoV-2 infection on HBV patients are still not clear. For example, we do not yet know whether the SARS-CoV-2 infection is more severe in HBV patients and we also do not have much knowledge about the impact of SARS-CoV-2 on the course of HBV infection. In this retrospective study, we investigated the clinical characterizes of the patients coinfected with SARS-CoV-2 and HBV by analyzing the clinical records and laboratory tests of 123 COVID-19 patients admitted to Zhongnan Hospital of Wuhan University, Wuhan, China, from January 5 to February 20, 2020.

Circulating in China and 158 other countries and areas, the ongoing COVID-19 outbreak has caused devastating mortality and posed a great threat to public health. However, efforts to identify effectively supportive therapeutic drugs and treatments has been hampered by our limited understanding of host immune response for this fatal disease. To characterize the transcriptional signatures of host inflammatory response to SARS-CoV-2 (HCoV-19) infection, we carried out transcriptome sequencing of the RNAs isolated from the bronchoalveolar lavage fluid (BALF) and peripheral blood mononuclear cells (PBMC) specimens of COVID-19 patients. Our results reveal distinct host inflammatory cytokine profiles to SARS-CoV-2 infection in patients, and highlight the association between COVID-19 pathogenesis and excessive cytokine release such as CCL2/MCP-1, CXCL10/IP-10, CCL3/MIP-1A, and CCL4/MIP1B. Furthermore, SARS-CoV-2 induced activation of apoptosis and P53 signalling pathway in lymphocytes may be the cause of patients’ lymphopenia. The transcriptome dataset of COVID-19 patients would be a valuable resource for clinical guidance on anti-inflammatory medication and understanding the molecular mechansims of host response.

Seagrass meadows provide important ecosystem services, but are among the least conserved marine ecosystems. The Southern bioregion of China has the nation’s largest seagrass distribution. However, lack of information on the distribution of seagrasses and the threats they face pose a significant obstacle to their conservation and restoration. Accordingly, a framework for prioritizing conservation and restoration objectives was proposed in the present study. First, we modeled the suitable habitats with MaxEnt, random forest (RF), and ensemble models to obtain a reliable basis map of seagrass distribution. A potentially suitable area of approximately 3,536–4,852 km2 was mapped in the coastal sea of South China, with the greatest area occurring between 18 °N and 22 °N. The anthropogenic pressures on the seagrass habitat were then estimated using an integrated exposure index consisting of four indicators, namely, population density, fishery economy, aquaculture, and shipping. The results indicated 48% of the coastal seas were under intensive anthropogenic pressures, with a higher exposure in the north than the south. The current conservation status suggests that there is a large seagrass conservation gap. By coupling the two dimensions of habitat suitability and integrated exposure, priority sites for seagrass management in South China were identified for the first time. Our work will not only provide basic information for coastal ecosystem management, but also serve as a tool to support the conservation and restoration planning of seagrass, thus, ultimately promoting the sustainability of seagrasses habitats.

Background: Many studies have shown that long noncoding RNAs (lncRNAs) derived from the host and human immunodeficiency virus (HIV) itself play important roles in virus-host interactions and viral pathogenesis. To identify potential key lncRNAs in the regulation of HIV pathogenesis, transcriptome analysis of peripheral blood mononuclear cells (PBMCs), which were derived from 6 HIV/acquired immunodeficiency syndrome (AIDS) subjects pre-HAART and post-HAART with effective control of plasma viremia (Results: We identified a total of 974 lncRNAs whose expression levels were restored to normal after ART therapy. The results of the cis-acting analysis showed that only six lncRNAs have cis-regulated target genes, among which the target gene RP11-290F5.1, interferon regulatory factors 2 (IRF2), could promote HIV replication. We also identified lncRNA CTB-119C2.1, which regulates most mRNAs with differential expression between pre- and post-HAART, and the differences were significant. We selected lncRNA CTB-119C2.1 for qRT–PCR verification, and the results were consistent with those of RNA-seq. RAB3A and GADD45A, two of the lncRNA CTB-119C2.1-associated genes, have been shown to be associated with HIV infection. KEGG analysis of lncRNA CTB-119C2.1-associated genes revealed that most of the genes are involved in the p53 signaling pathway or pathways related to cell circulation and DNA replicationConclusion: In this study, we used RNA-seq to systematically compare the expression profiles of lncRNAs in HIV subjects between untreated and treated time points. We successfully identified some lncRNAs with differential expression during certain periods (no HIV infection, HIV infection before treatment, and after treatment). Their expression is associated with viral loads, and some of their regulating genes were found to be involved in HIV pathogenesis through bioinformatic analysis. These findings could help to reveal the underlying molecular mechanism of the progression of AIDS.

Global mangrove forests have exhibited distinct changes in the past decades owing to anthropogenic activities, with land-use pressure being among the main causes of mangrove loss. Thus, understanding the inherent conflicts between conservation/restoration and land-use demands is fundamental for mangrove management. To predict how land-use changes will drive the spatiotemporal patterns of mangrove habitats, a novel integrated framework coupling MaxEnt and Dyna-CLUE modeling was proposed. The coupled model can identify suitable mangrove afforestation habitats and predict the impact of land-use change on potential mangrove habitats. In this study, the model was used to predict the mangrove habitat change in 2030 in the province with the most mangrove forests in China. The potential suitable habitat of 14 mangrove species under three coastal land-use scenarios were mapped using the coupled model. Under the current trend scenario, only 41.2% of the existing wetland would be retained, whereas the potential distribution area of all the mangrove species will decrease by an average of 30%. Under the sustainable development and ecological protection scenarios, the mangrove habitat could be increased by 11% to 61%, depending on the species. Different mangrove species showed varied sensitivity to the improved land-use policies, with several species being harder to restore than others, even under aggressive protection and restoration policies. The combined use of both MaxEnt and Dyna-CLUE models proved complementary and offered insights into the impacts of different land-use policies on the spatiotemporal change of mangrove habitats.

Background & AimsThe coronavirus disease 2019 (COIVD-19) caused by SARS-CoV-2 has been characterized as a pandemic, which causes a serious public health challenge in the world. A very large group of patients infected by HBV has been reported worldwide, especially in China. In order to answer whether specific treatment strategy on the patients coinfected with HBV and SARS-CoV-2, it requires profound understanding of the clinical characteristics on those patients. However, the impacts of SARS-CoV-2 infection on HBV patients remain largely unknown.Approach & ResultsIn this retrospective investigation, we included 123 COVID-19 patients admitted to Zhongnan Hospital of Wuhan University, Wuhan, China, from January 5 to March 7, 2020. All enrolled patients are the laboratory confirmed COVID-19 pneumonia cases according to the criteria reported previously. A total of 123 patients were analyzed for their Clinical records, laboratory results including the diagnosis of HBV infection and liver function. Among 123 confirmed COVID-19 patients, the mean age was 51 years old and 59.3% were females (73/123). Fifteen were previously HBV infected patients, 66.7% of them were males (10/15), patients with HBV infection appeared to have a higher incidence of liver cirrhosis and an increased level of total bilirubin. Seven (46.7%) patients with HBV infection were defined as severe cases, while the severity rate was 24.1% for the patients without HBV infection (26/108). The mortality of patients with HBV infection was 13.3% (2/15) compared to 2.8% (3/108) for the patients without HBV infection.ConclusionsSARS-CoV-2 infection may cause Live function damage in COVID-19 cases and the patients with HBV infection are likely to have more severe disease outcome.

ObjectivesComorbidities have significant indications for the disease outcome of COVID-19, however which underlying diseases that contribute the most to aggravate the conditions of COVID-19 patients is still largely unknown. SARS-CoV-2 viral clearance is a golden standard for defining the recovery of COVID-19 infections. To dissect the underlying diseases that could impact on viral clearance, we enrolled 106 COVID-19 patients who were hospitalized in the Zhongnan Hospital of Wuhan University, Wuhan, China between Jan 5 and Feb 25, 2020.MethodologyWe comprehensively analyzed demographic, clinical and laboratory data, as well as patient treatment records. Survival analyses with Kaplan-Meier and Cox regression modelling were employed to identify factors influencing the viral clearance negatively.ResultsWe found that increasing age, male gender, and angiotensin-converting enzyme 2 (ACE2) associated factors (including hypertension, diabetes, and cardiovascular diseases) adversely affected the viral clearance. Furthermore, analysis by a random forest survival model pointed out hypertension, cortisone treatment, gender, and age as the four most important variables.ConclusionsWe conclude that patients at old age, males, and/or having diseases associated with high expression of ACE2 will have worse prognosis during a COVID-19 infections.

Background The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to the outbreak of pneumonia in Wuhan. The virus is highly infectious. Patients with cancer might be susceptible to the viral infection because of the immunosuppressive state cause by therapies on tumors. Case presentation We present the clinical features of four cancer patients who were infected with SARS-CoV-2 in late January of 2020 in our hospital. Cases 1 and 3 were diagnosed as mild and common type of coronavirus disease 2019 (COVID-2019) and survived from the viral infection. They acquired SARS-CoV-2 infection during their staying in hospital under radiotherapy and surgery of the tumors. Cases 2 and 4 suffered from severe type of COVID-19, and Case 2 was dead owning to the advanced age, uncontrolled chronic B cell lymphocytic leukemia and many other underlying diseases. The immunosuppressive state induced by liver transplantation and anti-rejection therapy might contribute to the severity of COVID-19 in Case 4, who suffered from hepatitis B related hepatocellular carcinoma. However, Case 4 was recovered from COVID-19 after a combination therapy against virus, bacteria and fungi, and also respiratory support. Nearly all patients showed a decrease in lymphocytes including total CD3+ T cells, B cells, and natural killer cells after infection of the virus. Conclusions The severity of COVID-19 might be influenced by immune system state and underlying diseases in cancer patients. And the treatment of SARS-CoV-2 infection in cancer patients is challenged by the immunosuppressive state of these patients under chemotherapy or surgery.

SummaryBackgroundViral clearance is one important indicator for the recovery of SARS-CoV-2 infected patients. Previous studies have pointed out that suboptimal T and B cell responses can delay viral clearance in MERS-CoV and SARS-CoV infected patients. The role of leukomonocytes in viral clearance of COVID-19 patients is not yet well defined.MethodsFrom January 26 to February 28, 2020, an observational study was launched at the Department of Infectious Diseases, Zhongnan Hospital of Wuhan University, Wuhan, China. We enrolled 25 laboratory-confirmed COVID-19 patients, whose throat-swab specimens were tested positive for SARS-CoV-2 infection by qRT-PCR. To investigate the factors that contribute to the viral clearance, we comprehensively analyzed clinical records, counts of lymphocyte subsets including CD3+, CD4+, CD8+ T cells, B cells and NK cells in the patients who successfully cleared SARS-CoV-2, and compared to those that failed to, after a standardized treatment of 8-14 days.FindingsIn 25 enrolled COVID-19 patients, lymphopenia was a common feature. After the treatment, 14 out of the 25 enrolled patients were tested negative for SARS-CoV-2. The patients that cleared the infection had restored the numbers of CD3+, CD4+, CD8+ T cells and B cells as compared to the still viral RNA positive patients, while the recovered patients had a higher count of leukomonocytes.ConclusionsBy comparison of leukomonocytes counts in COVID-19 patients at different stages of the disease, we found that CD3+, CD4+, CD8+ T cells and B cells appear to play important roles in viral clearance. The restoration of leukomonocytes counts from peripheral blood can be used as prognosis for the recovery of an COVID-19 infection. We propose that restoration of leukomonocytes counts can be added to the COVID-19 diagnostic guidance as a criterion for releasing and discharging patients.

Real time fluorescent quantitative PCR (RT-PCR) is widely used as the gold standard for clinical detection of SARS-CoV-2. However, due to the low viral load in patient throats and the limitations of RT-PCR, significant numbers of false negative reports are inevitable, which results in failure to timely diagnose, early treat, cut off transmission, and assess discharge criteria. To improve this situation, an optimized droplet digital PCR (ddPCR) was used for detection of SARS-CoV-2, which showed that the limit of detection of ddPCR is significantly lower than that of RT-PCR. We further explored the feasibility of ddPCR to detect SARS-CoV-2 nucleic acid from 77 clinical throat swab samples, including 63 suspected outpatients with fever and 14 supposed convalescents who were about to discharge after treatment, and compared with RT-PCR in terms of the diagnostic accuracy. In this double-blind study, we tested, surveyed subsequently and statistically analyzed 77 clinical samples. According to our study, 26 samples from COVID-19 patients with RT-PCR negative were detected as positive by ddPCR. No FPRs of RT-PCR and ddPCR were observed. The sensitivity, specificity, PPV, NPV, NLR and accuracy were improved from 40% (95% CI: 27–55%), 100% (95% CI: 54–100%), 100%, 16% (95% CI: 13–19%), 0.6 (95% CI: 0.48–0.75) and 47% (95% CI: 33–60%) for RT-PCR to 94% (95% CI: 83–99%), 100% (95% CI: 48–100%), 100%, 63% (95% CI: 36–83%), 0.06 (95% CI: 0.02–0.18) and 95% (95% CI: 84–99%) for ddPCR, respectively. Moreover, 14 (42.9 %) convalescents still carry detectable SARS-CoV-2 after discharge. Overall, ddPCR shows superiority for clinical diagnosis of SARS-CoV-2 to reduce the false negative reports, which could be a powerful complement to the current standard RT-PCR. It also suggests that the current clinical practice that the convalescent after discharge continues to be quarantined for at least 2 weeks is completely necessary which can prevent potential viral transmission.

Quantitative real time PCR (RT-PCR) is widely used as the gold standard for clinical detection of SARS-CoV-2. However, due to the low viral load specimens and the limitations of RT-PCR, significant numbers of false negative reports are inevitable, which results in failure to timely diagnose, cut off transmission, and assess discharge criteria. To improve this situation, an optimized droplet digital PCR (ddPCR) was used for detection of SARS-CoV-2, which showed that the limit of detection of ddPCR is significantly lower than that of RT-PCR. We further explored the feasibility of ddPCR to detect SARS-CoV-2 RNA from 77 patients, and compared with RT-PCR in terms of the diagnostic accuracy based on the results of follow-up survey. 26 patients of COVID-19 with negative RT-PCR reports were reported as positive by ddPCR. The sensitivity, specificity, PPV, NPV, negative likelihood ratio (NLR) and accuracy were improved from 40% (95% CI: 27–55%), 100% (95% CI: 54–100%), 100%, 16% (95% CI: 13–19%), 0.6 (95% CI: 0.48–0.75) and 47% (95% CI: 33–60%) for RT-PCR to 94% (95% CI: 83–99%), 100% (95% CI: 48–100%), 100%, 63% (95% CI: 36–83%), 0.06 (95% CI: 0.02–0.18), and 95% (95% CI: 84–99%) for ddPCR, respectively. Moreover, 6/14 (42.9%) convalescents were detected as positive by ddPCR at 5–12 days post discharge. Overall, ddPCR shows superiority for clinical diagnosis of SARS-CoV-2 to reduce the false negative reports, which could be a powerful complement to the RT-PCR.

Circulating in China and 75 other countries and territories, the ongoing COVID-19 outbreak has caused devastating mortality and posed a great threat to public health. However, efforts to identify effectively supportive therapeutic drugs and treatments has been hampered by our limited understanding of host immune response for this fatal disease. To characterize the transcriptional signatures of host inflammatory response to SARS-CoV-2 infection, we carried out transcriptome sequencing of the RNAs isolated from the bronchoalveolar lavage fluid (BALF) and peripheral blood mononuclear cells (PBMC) specimens of COVID-19 patients. Our results reveal distinct host inflammatory cytokine profiles to SARS-CoV-2 infection in patients, and highlight the association between COVID-19 pathogenesis and excessive cytokine release such as CCL2/MCP-1, CXCL10/IP-10, CCL3/MIP-1A, and CCL4/MIP1B. Furthermore, SARS-CoV-2 induced activation of apoptosis and P53 signaling pathway in lymphocytes may be the cause of patients’ lymphopenia. The transcriptome dataset of COVID-19 patients would be a valuable resource for clinical guidance on anti-inflammatory medication and understanding the molecular mechansims of host response. Funding: This study was supported by Special Fund for COVID-19 Research of Wuhan University, National Science and Technology Major Project (#2018ZX10733403), China NSFC grants (#81672008, 31871316), Hubei Natural Science Foundation (#2018CFA035), Basic Scientific Research Foundation of Central Universities (#2042019gf0026), Ministry of Science and Technology of China, the National Mega Project on Major Infectious Disease Prevention (#2017ZX10103005) and National Key Research and Development Program of China (#2018YFE0204500). Declaration of Interest: The authors declare no competing interests. Ethical Approval: This study was approved by the Ethics Committee of the Zhongnan Hospital of Wuhan University. The RNA-seq analyses of BALF samples and PBMC were performed on existing samples collected during standard diagnostic tests, posing no extra burden to patients.

Background/aims Inflammatory bowel disease (IBD) is associated with considerable impairment of patients' health-related quality of life (HRQoL). Knowledge of factors that significantly affect IBD patients' HRQoL can contribute to better patient care. However, the HRQoL of IBD patients in non-Western countries are limited. Hence, we assessed the HRQoL of Singaporean IBD patients and identified its determinants. Methods A prospective, cross-sectional study was conducted at Singapore General Hospital outpatient IBD Centre. The HRQoL of IBD patients was assessed using the short IBD questionnaire (SIBDQ), Short Form-36 physical and mental component summary (SF-36 PCS/MCS) and EuroQol 5-dimensions 3-levels (EQ-5D-3L) and visual analogue scale (VAS). Independent samples t-test was used to compare HRQoL between Crohn's disease (CD) and ulcerative colitis (UC). Determinants of HRQoL were identified through multiple linear regression. Results A total of 195 IBD patients (103 UC, 92 CD) with a mean disease duration of 11.2 years were included. There was no significant difference in HRQoL between patients with UC and CD. Factors that significantly worsened HRQoL were presence of active disease (b=-6.293 [SIBDQ], -9.409 [PCS], -9.743 [MCS], -7.254 [VAS]), corticosteroids use (b=-7.392 [SIBDQ], -10.390 [PCS], -8.827 [MCS]), poor medication adherence (b=-4.049 [SIBDQ], -1.320 [MCS], -8.961 [VAS]), presence of extraintestinal manifestations (b=-13.381 [PCS]), comorbidities (b=-4.531 [PCS]), non-employment (b=-9.738 [MCS], -0.104 [EQ-5D-3L]) and public housing (b=-8.070 [PCS], -9.207 [VAS]). Conclusions The HRQoL is impaired in this Asian cohort of IBD. The magnitude of HRQoL impairment was similar in UC and CD. Clinical characteristics were better determinants of patients' HRQoL than socio-demographic factors. Recognizing the factors that impact patients' HRQoL would improve the holistic management of IBD patients.

Urban development based on the “carrying capacity” of its resources and environment is a key principle for China’s green development stated in its 13th Five-Year Plan (2016–2020). It is, however, difficult to understand the carrying capacity especially in coastal and marine areas. A Pressure–Support (PS) framework was designed to illustrate the relationships of pressures and support and the integrated carrying capacity of a given coastal and marine area. A PS index was then developed based on the framework to apply to a case study in the coastal and marine areas of Guangxi Province, China. The evaluation results showed a decreasing marine carrying capacity trend and indicate major pressures from land reclamation, fishing, coastal industry, port construction and tourism activities. This case study demonstrates a practical approach to disentangling complex information around the carrying capacity of coastal areas, which could be an effective tool for facilitating related policy making in sustainable coastal and marine development.

The segmented model test is often used to study the wave load characteristics of large ships as it can account for the hydroealstic effect. The vertical bending moment (VBM) is of crucial importance in ensuring the safety of ocean-going vessels in rough seas, and there exists in the literature a large number of experimental studies of the VBM. For ships with large openings in the deck, for instance, container ships, the lateral wave loads, such as horizontal bending moment (HBM) and torsional moment (TM) in quartering seas, are as important as VBM. There are, however, few studies on the measurement of the coupled horizontal-torsional vibrations of such ships in model tests. In the paper, a method is proposed for designing flexible backbone models that satisfy the similarities of vertical and horizontal bending stiffness as well as the torsional stiffness, and the measurement of the wave load components is also described. In order to meet the similarity of the hull girder stiffness, the backbone cross-section of a complex form is designed. Finite element method (FEM) is used to calculate the natural frequencies and mode shapes of the segmented model. Measurement of the vertical bending moment, horizontal bending moment and torsional moment are calibrated by applying various combinations of loads.

Background and aims Aging-induced bone loss is a multifactorial, age-related, and progressive phenomenon among the general population and may further progress to osteoporosis and increase the risk of fractures. Cycloastragenol (CAG), currently the only compound reported that activates human telomerase, is thought to be able to alleviate or delay the symptoms of aging and chronic diseases. Previous research has suggested that CAG may have the potential to alleviate age-related bone loss. However, to date, no research has specifically focused on this aspect. In this study, we aimed to investigate whether CAG could prevent senile osteoporosis, and further reveal its underlying mechanism. Methods CAG treatment was administrated into two bone loss rat models (D-galactose administration and aging) for 20 weeks and 33 weeks, respectively. Serum biomarkers analyses, bone biomechanical tests, micro-computed tomography assessment, and bone histomorphometry analyses were performed on the bone samples collected at the endpoint, to determine whether CAG could prevent or alleviate age-related bone loss. Proteomic analysis was performed to reveal the changes in protein profiles of the bones, and western blot was used to further verify the identity of the key proteins. The viability, osteoblastic differentiation, and mineralization of MC3T3-E1 cells were also evaluated after CAG treatment in vitro. Results The results suggest that CAG treatment improves bone formation, reduces osteoclast number, alleviates the degradation of bone microstructure, and enhances bone biomechanical properties in both d -galactose- and aging-induced bone loss models. CAG treatment promotes viability, osteoblastic differentiation, and mineralization in MC3T3-E1 cells. Proteomic and western blot analyses revealed that CAG treatment increases osteoactivin (OA) expression to alleviate bone loss. Conclusion The results revealed that CAG alleviates age-related bone loss and improves bone microstructure and biomechanical properties. This may due to CAG-induced increase in OA expression. In addition, the results support preclinical investigations of CAG as a potential therapeutic medicine for the treatment of senile osteoporosis.

Thirty years ago, Yundang Lagoon, located in the centre of Xiamen in southeast China, was heavily polluted. A series of clean-up projects have been implemented since the 1980s. After three phases of restoration projects, the lagoon's environment quality has improved significantly, although it is not fully restored. Clean-up activities are still ongoing. In 1994, Xiamen became the first city in China to adopt an Integrated Coastal Management (ICM) strategy to address its coastal environmental problems. The restoration of Yundang Lagoon remained a priority and has been a key issue in the development of the city's pollution abatement and environmental management strategy. This study reviews and examines the restoration efforts and management scheme of Yundang Lagoon from 1988 to the present, analyses the environmental changes, explores the challenges of its restoration and analyses the benefits of ICM to its long-term restoration by extracting six key principles. Specific suggestions are proposed for future ...

The solution-processed PbSe colloidal quantum-dot (CQD) infrared photodetector with tandem architecture is proposed to address the high dark current issue. The electrical transport mechanism in tandem has been fundamentally changed in which the recombination of carriers at an intermediate layer becomes dominant rather than carriers hopping between nearest neighbors in CQD materials. As a result, the tandem photodetector exhibits ultra-high detectivities of 4.7 × 10(13) Jones and 8.1 × 10(13) Jones under 34 μW cm(-2) illumination at 1100 nm, at 275 K and 100 K, respectively.

PbSe quantum dot light emitting diodes (QD-LEDs) of a multi-layer architecture are reported in the present work to exhibit high external quantum efficiencies. In these devices, a ligand replacement technique was employed to activate PbSe QDs, and ZnO nanoparticles were used for the electron transport layer. The emission wavelength of this solution processed device is QD size tunable over a broad spectral range, and an LED efficiency of 0.73% was measured at 1412 nm. Higher efficiencies at longer wavelengths are also inferred from spectral characterization.

With the advantages of clean, renewable and wide distribution, wind power generation becomes an important part of the smart grid. Wind generator is the key apparatus in application of wind energy, which has been paid great attention to its operation reliability. Partial discharge in the insulation system is a serious threat to its safe operation. Polyimide (PI) has been widely applied as one of the most important organic materials owing to its excellent physical and chemical properties. And nano particals are incorporated in polyimide to enhance the properties, such as breakdown characteristics. In this paper, polyimide/Al 2 O 3 (PI/Al 2 O 3 ) nanocomposite films were prepared using in-situ dispersion polymerization process. The mechanical and electrical characteristics of the PI/Al 2 O 3 nanocomposite films with different alumina content comparing to the unfilled polyimide film, including the tensile strength and elongation, dielectric spectroscopy, dielectric breakdown strength and the corona resistance property as well, were studied.

The degradation mechanism of CdSe/ZnS quantum dots (QDs) light-emitting diodes (LEDs) was investigated with steady-state and time-resolved photoluminescence measurements. Our study reveals that the degradation is associated with the decreasing quantum efficiency of the CdSe/ZnS QDs in the devices. Two mechanisms that cause the efficiency reduction were verified in the experiments: i.e., thermal instability and luminescence quenching.

In an attempt to suppress the dark current, the barrier layer engineer for solution-processed PbSe colloidal quantum-dot (CQD) photodetectors has been investigated in the present study. It was found that the dark current can be significantly suppressed by implementing two types of carrier blocking layers, namely, hole blocking layer and electron blocking layer, sandwiched in between two active PbSe CQD layers. Meanwhile no adverse impact has been observed for the photo current. Our study suggests that this improvement resides on the transport pathway created via carrier recombination at intermediate layer, which provides wide implications for the suppression of dark current for infrared photodetectors.

We report a high-performance colloidal quantum dot (CQD)-based near-infrared tandem photodetector fabricated on flexible substrates via solution-processed method. The tandem photodetector on poly(ethylene terephthalate) substrates exhibited low dark current and high detectivities over ∼8.8 × 1011 Jones at near infrared range at −0.5 V bias and over ∼1013 Jones near 0 bias. The critical bend radii of ∼8 mm and ∼3 mm have been demonstrated for tensile and compressive bending, respectively. The performance of photodetectors remains stable under mechanical stress, making PbSe CQD material a promise candidate for flexible infrared sensing applications.