[Course of disease and related epidemiological parameters of COVID-19: a prospective study based on contact tracing cohort]

Objective: To analyze the course of disease and epidemiological parameters of COVID-19 and provide evidence for making prevention and control strategies. Methods: To display the distribution of course of disease of the infectors who had close contacts with COVID-19 cases from January 1 to March 15, 2020 in Guangdong Provincial, the models of Lognormal, Weibull and gamma distribution were applied. A descriptive analysis was conducted on the basic characteristics and epidemiological parameters of course of disease. Results: In total, 515 of 11 580 close contacts were infected, with an attack rate about 4.4%, including 449 confirmed cases and 66 asymptomatic cases. Lognormal distribution was fitting best for latent period, incubation period, pre-symptomatic infection period of confirmed cases and infection period of asymptomatic cases; Gamma distribution was fitting best for infectious period and clinical symptom period of confirmed cases; Weibull distribution was fitting best for latent period of asymptomatic cases. The latent period, incubation period, pre-symptomatic infection period, infectious period and clinical symptoms period of confirmed cases were 4.50 (95%CI:3.86-5.13) days, 5.12 (95%CI:4.63-5.62) days, 0.87 (95%CI:0.67-1.07) days, 11.89 (95%CI:9.81-13.98) days and 22.00 (95%CI:21.24-22.77) days, respectively. The latent period and infectious period of asymptomatic cases were 8.88 (95%CI:6.89-10.86) days and 6.18 (95%CI:1.89-10.47) days, respectively. Conclusion: The estimated course of COVID-19 and related epidemiological parameters are similar to the existing data.

Bain and Nishiyama–Wassermann transition path separation in the martensitic transitions of Fe

The importance of martensitic transformations has led to tremendous efforts to explore the microscopic martensitic transition paths. There are five possible transformation paths (for γ → α transition) known for Fe at present, and at an arbitrary activation energy, any of the five paths might be followed. It then becomes considerably difficult to monitor the microscopic phase transition mechanism in experiments. Therefore, it is helpful to realize only one of the paths in a physical process. Based on first-principles calculations, we show that at suitable activation energies the Nishiyama–Wassermann (N–W) transformation path can be realized without the involvement of the Bain path, since the condition E_NW(θ) < E < E_Bain can be satisfied by pure Fe. E is the activation energy of the system, and E_NW(θ) and E_Bain are the energy barriers for the N–W and Bain transformations, respectively. In particular, the potential energy surface (PES) for the N–W transformation has been calculated as being four-dimensional, i.e., E = E(a,b,c,θ), where (a, b, c) are the lattice constants and θ is the shear angle involved in the shear distortion of the N–W path.

The importance of martensitic transformations has led to tremendous efforts to explore the microscopic martensitic transition paths.

[Clinical study on the relations of obstructive sleep apnea hypopneasyndrome and the degree and prognosis of coronary lesions]

Objective:The aim of this study is to discuss the relations between obstructive sleep apnea hypopnea syndrome (OSAHS) and severity and prognosis of coronary artery disease. Method:The OSAHS patients were divided into mild, moderate and severe groups according to Results of sleep monitoring. The severity of coronary artery lesion in each group was compared by counting the numbers of the lesion extension of coronary artery, calculating the Gensin score and evaluating the Thromblysis in myocardial infarction. The patients were followed up within 2 years, the incidence of major clinical cardiac adverse events was compared between each groups. Result:Three groups confirmed the numbers of the lesion extension of coronary artery and Gensin score increased, the Thromblysis in myocardial infarction reduced with the seriousness of OSAHS by coronary angiography (P<0.05). There was no statistical significance in compliance for oral use of three groups (P>0.05). Incidence of the main adverse cardiac events during two years in three groups were16.28%, 29.36% and 44.26%. Incidence of the main adverse cardiac events increased with the seriousness of OSAHS (P<0.05). Conclusion:The coronary artery pathologic change severity aggravated with the seriousness of OSAHS，and the incidence of the main adverse cardiac events increased with the seriousness of OSAHS.

Comparison of FIB-4 and APRI in Chinese HBV-infected patients with persistently normal ALT and mildly elevated ALT

Significant liver disease has been reported in chronic hepatitis B patients with normal alanine aminotransferase (ALT). Liver biopsy (LB) is the current gold standard for assessing hepatic inflammation and fibrosis in patients with chronic HBV. However, associated risks have led to the development of noninvasive models. Their utility in patients with normal ALT is unknown. FIB-4 and aspartate aminotransferase (AST)-to-platelet ratio index (APRI) were calculated for patients with chronic HBV infection undergoing biopsy. The performance of each model and AUROC for predicting significant fibrosis (Scheuer's score ≥ S2) were determined for the entire cohort and stratified by elevated (≥50 U/L) and normal ALT. Two-hundred and thirty-one liver biopsies were included. The number of patient with normal ALT was 140, and 22.1% had significant fibrosis. The AUROC curve for patients with normal ALT was 0.81 for FIB-4 and 0.80 for APRI, compared with 0.71 for FIB-4 and 0.72 for APRI for those with mildly elevated ALT level. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of FIB-4 were 0.63, 0.88, 0.61 and 0.93, for patients with normal ALT; the values for APRI were 0.40, 0.88, 0.33 and 0.93. Both FIB-4 and APRI are useful for identification of those without significant fibrosis. However, because they have poor PPV, LB will continue to be used for assessment of HBV-infected patients with normal ALT and mildly elevated ALT.

Optimization of multistage phenol adsorption by organobentonites: theoretical developments and experimental verification

Material balance equations were developed for representing phenol adsorption by organobentonites in a countercurrent multistage adsorption process. The developed equations were employed to analyze the adsorption performance of the multistage process. Results of the theoretical analyses using empirical Freundlich adsorption isotherm had shown that the multistage process is more efficient than the single-stage process in terms of phenol removal per unit amount of organobentonite. It was also shown that equal division of the total amount of organobentonite among all adsorption stages yields the best overall phenol removal efficiency for the multistage process in comparison with other organobentonite allocations. The Freundlich adsorption isotherm was confirmed by experimental tests to describe well the phenol adsorption by organobentonites. Results of theoretical performance analyses of the multistage adsorption process were experimentally verified using two- and three-stage test examples.

Adsorption of phenol and m-chlorophenol on organobentonites and repeated thermal regeneration

Experimental investigations were conducted on the adsorption characteristics of phenol and m-chlorophenol by organobentonites. The organobentonites were prepared by modifying natural bentonite with various quaternary ammonium salts including tetramethylammonium bromide, hexadecyltrimethylammonium bromide, benzyl-triethylammonium bromide, tetraethylammonium bromide and cetylpyridinium bromide. The adsorption characteristics of phenol and chlorophenol by these organobentonites were examined in detail. The empirical Freundlich isotherm was found to describe well the equilibrium adsorption data. Thermal regeneration of spent organobentonites was also investigated and operating conditions of 200 degrees C and 2 h heating were found to yield very good results.

Quinoline alkaloids and other constituents of Melicope semecarpifolia with antiplatelet aggregation activity

Three new quinoline alkaloids, 2-acetylevolitrine (1), 2-acetylpteleine (2), and semecarpifoline (3), along with 26 known compounds were isolated from the root bark of Melicope semecarpifolia. The structures of 1-3 were elucidated by means of spectral analysis. In addition, (2S)-(--)-7,8-dimethoxyplatydesmine (4), cis-(+)-7,8-dimethoxymyrtopsine (5), and (3R)-(--)-8,9-dimethoxygeibalansine (6) were isolated as new natural products. Several of these isolates were determined as exhibiting significant antiplatelet aggregation activities in vitro.

Cloning and Expression of Chinese Duck Interferon-gamma Gene

The efficacy of cytokine therapy has been demonstrated in several viral diseases. Interferon-gamma is a cytokine that has potent antiviral property and immunomodulatory activity. To investigate the role of IFN-gamma in viral clearance during natural infection and to define the antiviral mechanism, DHBV-infected ducks was used as an animal model. To clone, express, and develop the method of quantifying DuIFN-gamma gene transcription and expression, DuIFN -gamma cDNA was amplified by RT-PCR from PHA stimulated duck PBMC. Recombinant plasmid expressing DuIFN-gamma was used to transfect COS-7, and the cell culture supernatant was analyzed by CPE inhibitory assay and MTT methods to determine the antiviral titer of IFN-gamma. The GST-DuIFN-gamma fusion protein was expressed in E.coli and purified using the GST sepharose 4B. Results indicated that the supernatant collected from COS-7 cells transfected with DuIFN-gamma cDNA was able to prevent duck fibroblasts from VSV induced CPE in a dose dependent manner. An anti-DuIFN-gamma antibody neutralized this antiviral activity.