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In order to meet the domestic urgent needs of evaluating the immunogenicity of vaccines and the potency testing of therapeutic antibody products against coronavirus disease 2019 (COVID-19), the first Chinese national standards for SARS-CoV-2 neutralizing antibody were established. The potency and stability of the candidate standards were determined by neutralization assay and accelerated degradation study. The stability studies showed that the standards were stable in the short-term. The collaborative study showed that the candidate standards could reduce the variations in neutralization titers between labs and thus improve comparability of neutralizing antibody measurements. Sample 22 has been approved by the Biological Product Reference Standards Sub-Committee of the National Drug Reference Standards Committee as the first Chinese National Standard for Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) neutralizing antibody, with an assigned potency of 1,000 units per milliliter (U/ml). This standard will contribute to the standardized assessment of the quality and efficacy of vaccines and therapeutics for COVID-19 in China.

Slag waste can be effectively used to produce coal–fired slag concrete (CSC), which has economic and environmental benefits. However, CSC used in engineering construction will eventually be subjected to damage. The purpose of this study is to investigate the mechanical characteristics and damage evolution behaviour of CSC specimens under a uniaxial compressive load using acoustic emission (AE) monitoring technology. Through uniaxial compression testing and AE monitoring, the stress–strain curve and AE characteristics of CSC specimens are obtained. Subsequently, a damage evolution model of the CSC specimens under a uniaxial compression load is constructed, and the damage evolution characteristics of the concrete are analysed. The results indicate that an increase in the ratio of the coal–fired slag mass to the cement mass results in a gradual reduction in the compressive strength of the CSC. Moreover, the maximum value of the cumulative energy count and cumulative ringing count of the AEs gradually increases while the damage degree gradually decreases. The damage evolution process for CSC can be divided into three stages: the initial damage formation stage, accelerated damage growth stage, and damage failure stage. The damage model, based on the AE cumulative ringing count, reasonably reflects the damage evolution process of the CSC specimens. The results of this study provide a reference for theoretical research and the engineering application of CSC.

Aiming at backfill with crack under the thermo-mechanical (TM) coupling, the concepts of crack macro-damage, loading meso-damage, thermal meso-damage, and total damage of backfill were proposed. Ba...

Currently, there are no approved specific antiviral agents for novel coronavirus disease 2019 (COVID-19). In this study, 10 severe patients confirmed by real-time viral RNA test were enrolled prospectively. One dose of 200 mL of convalescent plasma (CP) derived from recently recovered donors with the neutralizing antibody titers above 1:640 was transfused to the patients as an addition to maximal supportive care and antiviral agents. The primary endpoint was the safety of CP transfusion. The second endpoints were the improvement of clinical symptoms and laboratory parameters within 3 d after CP transfusion. The median time from onset of illness to CP transfusion was 16.5 d. After CP transfusion, the level of neutralizing antibody increased rapidly up to 1:640 in five cases, while that of the other four cases maintained at a high level (1:640). The clinical symptoms were significantly improved along with increase of oxyhemoglobin saturation within 3 d. Several parameters tended to improve as compared to pretransfusion, including increased lymphocyte counts (0.65 × 10 9 /L vs. 0.76 × 10 9 /L) and decreased C-reactive protein (55.98 mg/L vs. 18.13 mg/L). Radiological examinations showed varying degrees of absorption of lung lesions within 7 d. The viral load was undetectable after transfusion in seven patients who had previous viremia. No severe adverse effects were observed. This study showed CP therapy was well tolerated and could potentially improve the clinical outcomes through neutralizing viremia in severe COVID-19 cases. The optimal dose and time point, as well as the clinical benefit of CP therapy, needs further investigation in larger well-controlled trials.

Aiming at the problem of roadway support in the re-mining of residual coal in the goaf under the condition of regenerated roof in thick seam, this paper takes 6F301 re-mining face in Taiping Coal Mine as the background, combines with the roadway layout of the re-mining face, uses 3DEC simulation software to study the movement law of overlying rock in the re-mining face, and designs and studies the support scheme of the re-mining roadway according to the movement law of overlying rock. The results show that the shotcrete + steel roof support scheme can improve the strength parameters of surrounding rock, improve the stress state of surrounding rock and limit the yield failure of surrounding rock. The measured results show that the maximum relative displacement of roof and floor and two sides of roadway is 97 mm and 105 mm respectively, which effectively controls the deformation of surrounding rock strata with good supporting effect. Through on-site industrial test and application, it can effectively improve the average recovery rate of coal resources, improve the economic efficiency of coal mining, reduce the comprehensive cost of coal mining in coal mining enterprises, and has very important engineering application and research value.

The shrinkage of swelling rock boreholes in coalmines is a complex problem affected by multiple fields coupling, such as humidity field and stress field. By establishing the equilibrium equation of swelling rock boreholes in coalmines, considering the expansion and softening properties, the elastic-plastic mechanics analysis was carried out, and the plastic zone radius and radial displacement of the surrounding rock of the swelling rock in coalmines were determined under the coupling of humidity and stress field. According to an example based on the research background of the floor rock roadway in the 8# coal seam of Songzao Coal Mine in Chongqing, the calculation results were carried out, and the influences of water content, ground stress and water pressure inside the hole on boreholes shrinkage were studied. The results show that with the increase of water content of the surrounding rock, the radius of plastic zone and radial displacement of borehole wall gradually increase; Both the humidity expansion and softening have an important influence on boreholes shrinkage in coalmines, and the radial displacement of borehole wall under the coupling of swelling and softening is greater than that of only considering expansion or softening; With the increase of the ground stress P, the radius of plastic zone and radial displacement of borehole wall gradually increase, showing a nonlinear increasing relation; The larger the water pressure in the boreholes, the smaller the radius of plastic zone and radial displacement of borehole walls, and properly increasing the water pressure in the boreholes can effectively control the boreholes shrinkage. The accuracy of theoretical analysis was further verified by indoor model tests. The results can provide a theoretical basis for solving the problem of boreholes shrinkage.

Currently, there are no approved specific antiviral agents for 2019 novel coronavirus disease (COVID-19). In this study, ten severe patients confirmed by real-time viral RNA test were enrolled prospectively. One dose of 200 mL convalescent plasma (CP) derived from recently recovered donors with the neutralizing antibody titers above 1:640 was transfused to the patients as an addition to maximal supportive care and antiviral agents. The primary endpoint was the safety of CP transfusion. The second endpoints were the improvement of clinical symptoms and laboratory parameters within 3 days after CP transfusion. The median time from onset of illness to CP transfusion was 16.5 days. After CP transfusion, the level of neutralizing antibody increased rapidly up to 1:640 in five cases, while that of the other four cases maintained at a high level (1:640). The clinical symptoms were significantly improved along with increase of oxyhemoglobin saturation within 3 days. Several parameters tended to improve as compared to pre-transfusion, including increased lymphocyte counts (0.65×109/L vs. 0.76×109/L) and decreased C-reactive protein (55.98 mg/L vs. 18.13 mg/L). Radiological examinations showed varying degrees of absorption of lung lesionswithin 7 days. The viral load was undetectable after transfusion in seven patients who had previous viremia. No severe adverse effects were observed. This study showed CP therapy was welltolerated and could potentially improve the clinical outcomes through neutralizing viremia in severe COVID-19 cases. The optimal dose and time point, as well as the clinical benefit of CP therapy, needs further investigation in larger well-controlled trials.Significance StatementCOVID-19 is currently a big threat to global health. However, no specific antiviral agents are available for its treatment. In this work, we explored the feasibility of convalescent plasma (CP) transfusion to rescue severe patients. The results from 10 severe adult cases showed that one dose (200 mL) of CP was welltolerated and could significantly increase or maintain the neutralizing antibodies at a high level, leading to disappearance of viremia in 7 days. Meanwhile, clinical symptoms and paraclinical criteria rapidly improved within 3 days. Radiological examination showed varying degrees of absorption of lung lesions within 7 days. These results indicate that CP can serve as a promising rescue option for severe COVID-19 while the randomized trial is warranted.

In order to study the effects of seepage on the long-term stability of cemented gangue-fly ash backfill (CGFB), the triaxial creep test of CGFB under seepage-stress coupling was carried out in this paper. The creep deformation law of CGFB considering the seepage-stress coupling effect was explored and a creep damage constitutive model considering seepage-stress coupling effect was established. The results show that CGFB has obvious creep properties under the coupling action of seepage and stress and its creep generally has three stages: decelerating creep, constant velocity creep and accelerating creep; the higher the seepage water pressure, the larger the creep deformation and steady-state creep rate, and the shorter the time to enter the accelerated creep. The ratio of long-term strength to instantaneous strength under different seepage water pressure conditions is 0.56–0.75, and it shows that seepage has a significant effect on the long-term strength of CGFB. The improved Nishihara Masaki model considers the influence of seepage and stress level on creep parameters, and can better reflect the creep mechanical characteristics of CGFB under the underground seepage pressure and ground stress environment. The research results provide an important experimental basis for the safety and long-term stability analysis of backfill mining in underground coal mines.

Seepage and cracks are two important factors affecting the stability of the cemented gangue-fly ash backfill (CGFB, a mixture of coal gangue, fly ash, cement and water). In this study, the CGFB samples with a 45° single crack were prepared and the mechanical properties of CGFB with cracks under different seepage water pressures were studied. Based on the theory of damage mechanics, the damage variable which can evaluate the seepage effect and crack effect was introduced, and the damage evolution law of CGFB with cracks under the seepage-stress coupling was discussed. The research hat: The mechanical properties of CGFB with cracks under seepage-stress coupling are mainly determined by the seepage water pressure, prefabricated crack and their coupling effects. Seepage and crack aggravate the attenuation of the peak strength and elastic modulus of CGFB, but with the increase of seepage water pressure, the deterioration effect of the crack weakens. Seepage and crack have significant effects on the damage of CGFB. Finally, based on the discrete element software, damage mechanism of CGFB with cracks under seepage-stress coupling was analyzed from a microscopic perspective. The research results can lay a foundation for the long-term stability analysis and instability prediction of CGFB with geological defects such as joints and cracks in water-rich mines.

Fibrinogen has been used as surgical sealant in the clinical setting for decades. The application of human plasma-derived fibrinogen is limited due to high cost and the risk of prion and virus infection. We developed a novel arginine-formulated fibrinogen from cryoprecipitates of porcine plasma. This porcine-derived fibrinogen exhibited excellent stability during sterilization and better hemostatic efficacy than a leading commercial hemostatic product in a nonlethal hemorrhage model. Therefore, it has the potential to be more economical and readily available while having a decreased risk of human blood-borne pathogen transmission.