[Isothermal amplification technology based on microfluidic chip].

Polymerase chain reaction (PCR) is the gold standard for nucleic acid amplification in molecular diagnostics. The PCR includes multiple reaction stages (denaturation, annealing, and extension), and a complicated thermalcycler is required to repetitively provide different temperatures for different stages for 30-40 cycles within at least 1-2 hours. Due to the complicated devices and the long amplification time, it is difficult to adopt conventional PCR in point-of-care testing (POCT). Comparing to conventional PCR, isothermal amplification is able to provide a much faster and more convenient nucleic acid detection because of highly efficient amplification at a constant reaction temperature provided by a simple heating device. When isothermal amplification is combined with microfluidics, a more competent platform for POCT can be established. For example, various diagnosis devices based on isothermal amplification have been used to rapidly and conveniently detect SARS-CoV-2 viruses. This review summarized the recent development and applications of the microfluidics-based isothermal amplification. First, different typical isothermal amplification methods and related detection methods have been introduced. Subsequently, different types of microfluidic systems with isothermal amplification were discussed based on their characteristics, for example, functionality, system structure, flow control, and operation principles. Furthermore, detection of pathogens (e.g. SARS-CoV-2 viruses) based on isothermal amplification was introduced. Finally, the combination of isothermal amplification with other new technologies, e.g. CRISPR, has been introduced as well.

Rapid PCR powered by microfluidics: A quick review under the background of COVID-19 pandemic.

PCR has been widely used in different fields including molecular biology, pathogen detection, medical diagnosis, food detection and etc. However, the difficulty of promoting PCR in on-site point-of-care testing reflects on challenges relative to its speed, convenience, complexity, and even cost. With the emerging state-of-art of microfluidics, rapid PCR can be achieved with more flexible ways in micro-reactors. PCR plays a critical role in the detection of SARS-CoV-2. Under this special background of COVID-19 pandemic, this review focuses on the latest rapid microfluidic PCR. Rapid PCR is concluded in two main features, including the reactor (type, size, material) and the implementation of thermal cycling. Especially, the compromise between speed and sensitivity with microfluidic PCR is explored based on the system ratio of (thermal cycling time)/(reactor size). Representative applications about the detection of pathogens and SARS-CoV-2 viruses based on rapid PCR or other isothermal amplification are discussed as well.

Intravenous immunoglobulin-based adjuvant therapy for severe COVID-19: a single-center retrospective cohort study.

OBJECTIVE: Coronavirus disease 2019 (COVID-19) is a major challenge facing the world. Certain guidelines issued by National Health Commission of the People's Repubilic of China recommend intravenous immunoglobulin (IVIG) for adjuvant treatment of COVID-19. However, there is a lack of clinical evidence to support the use of IVIG. METHODS: This single-center retrospective cohort study included all adult patients with laboratory-confirmed severe COVID-19 in the Respiratory and Critical Care Unit of Dabie Mountain Regional Medical Center, China. Patient information, including demographic data, laboratory indicators, the use of glucocorticoids and IVIG, hospital mortality, the application of mechanical ventilation, and the length of hospital stay was collected. The primary outcome was the composite end point, including death and the use of mechanical ventilation. The secondary outcome was the length of hospital stay. RESULTS: Of the 285 patients with confirmed COVID-19, 113 severely ill patients were included in this study. Compared to the non-IVIG group, more patients in the IVIG group reached the composite end point [12 (25.5%) vs 5 (7.6%), P = 0.008] and had longer hospital stay periods [23.0 (19.0-31.0) vs 16.0 (13.8-22.0), P < 0.001]. After adjusting for confounding factors, differences in primary outcomes between the two groups were not statistically significant (P = 0.167), however, patients in the IVIG group had longer hospital stay periods (P = 0.041). CONCLUSION: Adjuvant therapy with IVIG did not improve in-hospital mortality rates or the need for mechanical ventilation in severe COVID-19 patients. Our study does not support the use of immunoglobulin in patients with severe COVID-19 patients.

Seepage Time Soft Sensor Model of Nonwoven Fabric Based on the Extreme Learning Machine Integrating Monte Carlo.

Nonwoven fiber materials are materials with multifunctional purposes, and are widely used to make masks for preventing the new Coronavirus Disease 2019. Because of the complexity and particularity of their structure, it becomes difficult to model the penetration and flow characteristics of liquid in nonwoven fiber materials. In this paper, a novel seepage time soft sensor model of nonwoven fabric, based on Monte Carlo (MC), integrating extreme learning machine (ELM) (MCELM) is proposed. The Monte Carlo method is used to expand data samples. Then, an ELM method is used to establish the prediction model of the dyeing time of the nonwoven fiber material overlaps with the porous medium, as well as the insertion degree and height of the different quantity of hides. Compared with the back propagation (BP) neural network and radial basis function (RBF) neural network, the results show that the prediction model based on the MCELM method has significant power in terms of accuracy and prediction speed, which is conducive to the precise and rapid manufacture of nonwoven fiber materials in practical applications between liquid seepage characteristics and structural characteristics of porous media. Furthermore, the relationship between the proposed models has certain value for predicting the behavior and use of nonwoven fiber materials with different structural characteristics and related research processes.