The infection by the new coronavirus SARS-CoV-2 (called as COVID-19 disease) is a worldwide emergency, however, there is no antiviral treatment or vaccine until now. The crystal structure of SARS-CoV-2 main protease has been made publicity in the Protein Data Bank recently. Many efforts have been conducted by scientists including the use of several commercial medicines, however, understanding at atomic level how these compounds prevent SARS-CoV-2 protease is still lacking. In this context docking protocol was employed to rapidly estimate the binding affinity and binding pose of six drugs on the main protease.

Vibration of two-directional functionally graded sandwich (2D-FGSW) Timoshenko beams under a moving harmonic load is investigated. The beams consist of three layers, a homogeneous core and two functionally graded skin layers with the material properties continuously varying in both the thickness and length directions by power functions. A finite element formulation is derived and employed to compute the vibration characteristics of the beams. The obtained numerical result reveals that the material inhomogeneity and the layer thickness ratio play an important role on the natural frequencies and dynamic response of the beams. A parametric study is carried out to highlight the effects of the power-law indexes, the moving load speed and excitation frequency on the vibration characteristics of the beams. The influence of the beam aspect ratio on the vibration of the beams is also examined and discussed.

Atmospheric ultrafine, accumulation mode and coarse fractions collected at representative rice straw open burning areas in Hanoi were investigated to identify characteristics of size distribution and contribution of particles emitted from rice straw (RS) burning season to the atmosphere. The sampling was conducted in two episodes: RS burning episode and RS non-burning episode at Dong Anh and Quoc Oai, in seven consecutive days for each sampling campaign from 2018 to 2019. In the RS burning episode, PM1-2.5 showed the highest fraction among all collected particles in both sampling sites, while PM2.5-10 was the most abundant in RS non-burning season. The average mass concentration of PM2.5 in RS burning period and RS non-burning period were 79.7  46.5 g m-3 and 65.2  21.9 g m-3, respectively at Dong Anh sampling site. Those values were 90.9  33.2 g m-3 in the QO_RS burning site and 71.9  29.3 g m-3 in the TM_RS non-burning site. The proportion of fine particle (PM2.5) at both sites were considerable higher in RS burning period as compared to non-burning period, while the concentration of ultrafineparticle (PM0.1) and coarse particle (PM>10m) were similar between two episodes. This result provides better understanding on size distribution and contribution of fine particles from open RS burning to the atmosphere in Hanoi, which is an useful information for the environmental managers to control RS open burning in Hanoi as well as in Vietnam.

The novelty of this study is to apply Material Flow Analyses (MFAs) for both production line and wastewater treatment processes in a modern-technology beer company with an aim to assess cleaner production opportunities and potentials of the company through different scenarios for each cleaner production measure. As aspect of production line, two energy saving measures were proposed: (1) to reuse water-for-cooling for bottle and keg washing, and (2) to reuse thermal heat produced during rapid cooling to supply heat for the malt pasting process. The 2nd measure could save 11% of heat needed for malt pasting and 5.5% of steam from boiler that heats keg washing water was reduced in the 1nd solution compared to the case of no heat reuse in loop. Within the wastewater treatment plant (WWTP), the study proposed using biogas to generate energy through CHP (combine heat and power) system, of which electrical power is utilized for the WWTP operation and heat is used to maintain the temperature of sludge anaerobic digester (SAD) through a heat exchanger (HE). The results showed that the energy generated from biogas could compensate 16% of the total energy consumption of the WWTP with 43% (corresponding to 1,735 kWh) of electrical energy saving; 11% of heat saving to maintain SAD system

Performance indicators of water supply company can provide important information of its service quality and business efficiency, and be intelligent basis for decision making process. The authors have analyzed key performance indicators of 19 selected municipal water supply systems in Vietnam, including operation and design capacities, treated water quality, unit investment cost, water tariff, non-revenue water (NRW) ratio, and energy consumption rate. The average NRW of the 19 systems was 12.6% which was lower than country-wide value of 21%. The energy consumption rate of selected systems was ranging from 0.16 to 0.5KWh/m3, in average 0.3KWh/m3, which was also lower than country average of 0.35KWh/m3, whereas the rate of energy consumption in municipal water systems in China, USA, Australia, Chile, Canada was ranging from 0.1 to 1.33KWh/m3, depending on ground elevation, transfer distance, influent water quality, and applied technologies for water treatment and transportation. The selected water systems have applied improved treatment technologies such as mechanized coagulation-flocculation, lamella settling tank, dual media sand filter, combined contact clarifier with lamella plates, etc. The average treated water turbidity was ≤0.5NTU. The domestic water tariff of the selected systems was within the country range, from USD0.2 to 0.4/m3. Further, the authors have indicated correlation between selected performance indicators, such as energy consumption rate and non-revenue water ratio. The analytical results shown performance indicators of top water companies in Vietnam were in fairly good position compared to others, but improvements were still needed. Reduction of NRW ratio and keeping it at a low value are other challenges requiring water utility efforts.

Recent interest in wastewater treatment has shifted to the use of agricultural waste to treat antibiotics in aqueous solutions due the economic efficiency the technique brings. This study focuses on the synthesis, properties and study of the kinetic mechanism of activated carbon and its potential application to remove antibiotics from aqueous solutions. Activated carbon is synthesized from sugarcane bagasse by activated method with active substance of ZnCl2. With a specific surface area of about 980.84 m2/g and high porosity, the product could absorb a large amount of ciprofloxacin (CIP) antibiotics. The properties of materials are characterized by relevant analytical techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET). The behavior of CIP adsorption was studied under the effect of adsorption dose, initial CIP concentration and pH value. The adsorption and isothermal mechanisms are also studied. The results show that the adsorption adhered to the second kinetic model and the experimental data was found to be reasonably fitted to the Langmuir isotherm. Therefore, activated carbon manufactured from sugarcane bagasse could be used as a potential adsorbent to effectively remove antibiotics from aqueous solution.

Despite its prominent potential, the use of rubber wood (Hevea brasiliensis) for bio-oil production has not been fully investigated. This study reported experimental results of the bio-oil production and upgrading from rubber wood using fast pyrolysis technology. The effects of catalyst nature (vermiculite and dolomite), upgrading temperature and bio-oil/catalyst ratio on the product quality were deeply investigated. The results showed that dolomite was suitable to be used as a catalyst for bio-oil upgrading. At 600 °C and a bio-oil/catalyst ratio of 1:1, the bio-oil yield was maximized, while at 400 °C and a ratio of 1:3, the bio-oil heating value was maximized. Depending on usage purposes, a yield-oriented, heating value-oriented or in-between bio-oil upgrading solution could be considered.

Four known polyhydroxypregnane glycosides, dregeoside Da1 (1), volubiloside A (2), drevoluoside N (3), and volubiloside C (4) were isolated from the methanol extract of the leaves of Dregea volubilis. Their structures were elucidated by 1D-, 2D-NMR, spectra and comparing with those reported in the literature.

ABSTRACTFrom leaves of Amesiodendron chinense (Mer.) Hu four lignans (+)-aptosimon (1), (+)-isolariciresinol (2), (-)-cleomiscosin A (3), and (-)-cleomiscosin C (3) were isolated. Their structures were determined by spectroscopic analysis including MS, 1D and 2D NMR as well as by comparison with reported data in literature. All compounds were evaluated for cytotoxic activities against five human cancer cell lines, KB, SK-LU-1, MCF-7, HepG-2, and SW-480. They showed weak cytotoxic activity on five tested human cancer cell lines with IC50 values ranging from 32.61 to 95.18 µg/ml.

This work focused on monitoring CO2production, microbial growth and residual hydrocarbon concentration during bioremediation experiments performed on laboratory soil microcosms. A natural soil was artificially contaminated with hexadecane and adjusted with inorganic nutrients to stimulate biodegradation. Microbial growth, CO2production and residual hexadecane were periodically monitored at different soil water contents ranging from 0.15 to 0.25 g water g_1 of dry soil and at different temperatures ranging from 20 to 25oC. Results showed that the humidity has a greater effect on microbial activity and contaminant degradation than the temperature. The study established the experimental regression equation of temperature and humidity to the hexadecane mineralization rate, an important parameter in assessing the ability to convert organic carbon into inorganic carbon. The difference between the results of the hexadecane mineralization rate obtained from the experiment and calculated from the regression equation is not too high, from 2% to 20%.