Background Coronavirus disease 2019 (COVID-19) is a public health emergency of international concern and has caused traumatic experience for nurses worldwide. However, the prevalence of depression and anxiety symptoms in nurses, and how psychosocial factors influence nurses in this public crisis are unknown. Objectives To determine the effect of COVID-19 on the mental health of nurses and the prevalence of anxiety and depression symptoms among nurses in China during the outbreak. Design A cross-sectional study. Settings and participants A total of 3,228 nurses in Sichuan Province and Wuhan City were selected by convenience sampling. All participants were invited to complete the questionnaire through WeChat from January 27 to February 3, 2020. Methods A self-reported questionnaire combining depression and anxiety scale was used to collect data anonymously. Binary and multivariate logistic regression was applied to measure the odds of psychosocial factors of anxiety and depression and perceived health, respectively. Results The total incidence of depression (34.3%) and anxiety (18.1%) during the COVID-19 outbreak was lower than that during the SARS outbreak; however, the rate of depression in our study (47.1%) was high and similar in a recent study (50.4%) about the health care workers exposed to COVID-19 in China. The results indicated that COVID-19-related stress, relationship quality with family, and demographic characteristics were associated with depression, anxiety, and perceived health status. Furthermore, the prevalence of depression was similar between nurses working in low-risk COVID-19 wards was as high as working in high-risk COVID-19 wards (OR, 1.078; 95% CI, 0.784–1.481). Conclusions Our study revealed the high prevalence of depression and anxiety among nurses during the outbreak of COVID-19. COVID-19 factors and psychosocial factors were associated with mental health of nurses. The results suggest that hospitals should implement effective mental health promotion programs focused on occupational safety and family support to improve the well-being of nurses.

In vitro models of circulatory hemodynamics are required to mimic the microcirculation for study of endothelial cell responses to pulsatile shear stress by live cell imaging. This study reports the design, fabrication and characterisation of a microfluidic device that generates cardiac-like flow in a continuous culture system with a circulatory volume of only 2-3 μL. The device mimics a single chamber heart, with the following cardiac phases: (1) closure of the ventricle inlet valve, (2) contraction of the ventricle (systole) followed by opening of the outlet valve and (3) relaxation of the ventricle (diastole) with opening of the inlet valve whilst the outlet valve remains closed. Periodic valve states and ventricular contractions were actuated by microprocessor controlled pneumatics. The time-dependent velocity-field was characterised by micro-particle image velocimetry (μ-PIV). μ-PIV observations were used to help tune electronic timing of valve states and ventricular contractions for synthesis of an arterial pulse waveform to study the effect of pulsatile shear stress on bovine artery endothelial cells (BAECs). BAECs elongated and aligned with the direction of shear stress after 48 h of exposure to a pulsatile waveform with a maximum shear stress of 0.42 Pa. The threshold for BAECs alignment and elongation under steady (non-pulsatile) flow reported by Kadohama et al. (2006) is 0.7-1.4 Pa. These cells respond to transient shear stress because the time average shear stress of the pulse waveform to generate this morphological response was only 0.09 Pa, well below the steady flow threshold. The microfluidic pulse generator can simulate circulatory hemodynamics for live cell imaging of shear-induced signalling pathways.

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We report the design and validation of a two-layered microfluidic device platform for single cell capture, culture and clonal expansion. Under manual injection of a cell suspension, deterministic trapping of hundreds to thousands of single cells (adherent and non-adherent) in a high throughput manner and at high trapping efficiency was achieved simply through the incorporation of a U-shaped hydrodynamic trap into the downstream wall of each micro-well. Post single cell trapping, we confirmed that these modified micro-wells permit the attachment, spreading and proliferation of the trapped single cells for multiple generations over extended periods of time (>7 days) under media perfusion. Due to its a) low cost, b) simplicity in fabrication and operation, c) high trapping efficiency, d) reliable and repeatable trapping mechanism, e) cell size selection and f) capability to provide perfused long-term culture and continuous time-lapse imaging, the microfluidic device developed and validated in this study is seen to have significant potential application in high-throughput single cell quality assessment and clonal analysis.

Microfluidic paper-based analytical devices (μPADs) have been extensively studied for disease diagnostics, food quality control, and environmental monitoring due to the advantages of low cost, portability, and simplicity. The lack of flow controllability has triggered the development of valves for such devices. This paper reports the μPADs integrating novel wax valves for distance-based detection. The valves are printed on paper and can be manually opened by organic solvents within seconds. The opened valve does not influence the flow. The μPADs with wax valves were then applied in the distance-based detection of potassium iodate and glucose. The valves allow mixing of reagents and subsequent incubation in the loading zone, resulting in a shorter detection time and larger linear detection range. This study has demonstrated a linear detection range of 0.05–0.5 mM for potassium iodate, while linear ranges of 1–5 and 2.5–80 mg/dL are achieved for glucose when total detection time is 15 and 25 min, respectively. The lower detection limit is only 1/11 of that in a previous study. The detection ranges of iodate and glucose assays cover the concentrations of iodate in salt/milk and glucose in human saliva, respectively. Due to the simplicity, reliability, and ability for high-density integration, the μPADs with wax valves are of great potential in point-of-care (sampling) applications.

The study of cell elasticity provides new insights into not only cell biology but also disease diagnosis based on cell mechanical state variation.

Tracking living cells in video sequence is difficult, because of cell morphology and high similarities between cells. Tracking-by-detection methods are widely used in multi-cell tracking. We perform multi-cell tracking based on the cell centroid detection, and the performance of the detector has high impact on tracking performance. In this paper, UNet is utilized to extract inter-frame and intra-frame spatio-temporal information of cells. Detection performance of cells in mitotic phase is improved by multi-frame input. Good detection results facilitate multi-cell tracking. A mitosis detection algorithm is proposed to detect cell mitosis and the cell lineage is built up. Another UNet is utilized to acquire primary segmentation. Jointly using detection and primary segmentation, cells can be fine segmented in highly dense cell population. Experiments are conducted to evaluate the effectiveness of our method, and results show its state-of-the-art performance.

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