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In this research, Computational Fluid Dynamics (CFD) is employed to simulate the distribution of velocity, temperature, and mass fraction of water vapor in moist air and the evaporation rate of drying material within a drying chamber. These simulations are grounded in the application of conservation principles for mass, momentum, and energy. Experiments were conducted at building H3 in HCMUT at the Di An Campus to measure velocity and temperature at various locations within the drying chamber and the mass of dried turmeric rhizome. To model the drying process of turmeric rhizome in a tray dryer, the CFD software ANSYS Fluent was utilized for 3D modeling. Various models, such as the standard k-epsilon turbulence model and the species model used in conjunction with the transient solver, were employed to analyze the distribution of velocity, temperature, the mass fraction of water vapor in moist air, and the evaporation rate of the drying material within the tray dryer over 8000 seconds with a drying agent at 50 °C. The simulation results for the evaporation rate of the drying material and drying temperatures were compared to experimental data and found to be in excellent agreement. This was indicated by R² values of 1, 0.99, and 0.97 for the three drying stages. Consequently, simulation can serve as a viable option for studying drying mechanisms and mitigating certain limitations associated with conducting experiments. [ABSTRACT FROM AUTHOR]

The process of ensuring basement airflow and explosion safety is currently a critical concern. Designing a smoke management system for a multi-story basement poses a significant challenge for engineers because the basement is located underground, making natural ventilation through openings nearly impossible. Furthermore, the placement of stacking vehicles in the basement increases the risk of fire and smoke spread due to the high density of vehicles in a limited area. To address these challenges, Fire Dynamics Simulation (FDS), a Computational Fluid Dynamics (CFD) tool, was chosen to provide solutions for the combustion process and to predict risks. FDS enables the visualization and prediction of fire scenarios on a large scale without compromising safety or requiring substantial investment. This research aims to predict the efficiency of smoke management in a level-2 basement containing two car stackers in an actual office building in Melbourne, Australia. The model incorporates Very-Large Eddy Simulation (V-LES) for turbulence, with fire modeled using the Heat Release Rate (HRR) of 15 MW and an ultrafast T-square fire growth. The study examines the performance of the smoke management system by considering different criteria relating to temperature, visibility and toxic gas level with an exhaust fan capacity of 4 m3/s under two scenarios: successful activation of the sprinkler system and failure to activate the sprinkler system. The obtained results show a requirement of better smoke management system in the structure due to the risks to human life in both scenarios. [ABSTRACT FROM AUTHOR]

Nam Le Van,1,* Chung Pham Van,2,* Manh Nguyen Dang,2 Thang Dao Van,1 Quyen Le T Do,1 Hung Vu Hoang,1 Tien Tran Viet,1,3 Binh Nhu Do1,4 1Department of Infectious Disease, Military Hospital 103, Vietnam Military Medical University, Ha Noi, Vietnam; 2Institute of Clinical Infectious and Tropical Diseases, Military Central Hospital 108, Ha Noi, Vietnam; 3Director Office, Military Hospital 103, Ha Noi, Vietnam; 4Division of Military Science, Military Hospital 103, Ha Noi, Vietnam*These authors contributed equally to this workCorrespondence: Binh Nhu Do Email nhubinh.do@vmmu.edu.vnIntroduction: Rickettsioses are diseases caused by intracellular Gram-negative bacteria of the Rickettsiaceae family and transmitted through the bite of infected ticks or mites.Aim of Study: To investigate the clinical and subclinical characteristics and prognostic severe factors of the disease caused by Rickettsiaceae.Methods: A prospective, descriptive cross-sectional study was conducted at Department of Infectious Diseases of two military hospitals in Northern Vietnam from May 2013 to June 2019, in which 88 adult febrile patients caused by Orientia tsutsugamushi (50 patients) or Rickettsia spp. (38 patients) were enrolled. We recorded information regarding epidemiological characteristics (age, geography, residence, occupation), medical history, clinical and subclinical findings, life-threatening complications during treatment, outcomes and some factors predicting serious life-threatening complications in a case record form.Results: Scrub typhus (ST) patients had eschar (70%), skin-conjunctiva congestion (60%) and lymphadenopathy (44%). Rickettsia patients had a higher rate of maculopapular rash (39.5%), no ulcers and no lymphadenopathy detected. The majority of patients had elevated PCT > 0.05 ng/μL and increase in liver enzymes and thrombocytopenia. Major prognostic factors for severe complications included diffuse infiltrates on lung X-ray (OR: 19.5; p = 0.014), coarse crackles (OR: 18; p = 0.016), respiratory rate ≥ 25 cycles/minute (OR: 18; p = 0.016), shortness of breath (OR: 7.44; p = 0.003), pleural fluid (OR: 4.3; p = 0.035) and increase in AST ≥ 200 UI/l (OR: 4.42; p = 0.012). The PCT value is able to distinguish between the two groups with quite high reliability (the area under the ROC curve is 0.75).Conclusion: Eschar and peripheral lymphadenopathy were two valuable clinical symptoms for the diagnosis of scrub typhus and distinguishing 2 groups of diseases. Respiratory distress, increase in AST ≥ 200 UI/l and level of PCT were used as major prognostic factors in patients with Rickettsiaceae.Keywords: Rickettsiaceae, Orientia tsutsugamushi, Rickettsia spp., scrub typhus

This paper examines whether heterogeneities in financial development among Vietnamese provinces matter for firm growth in Vietnam. Using a nationally representative firm survey that covers more than 41,000 firms for the period 2009 − 2013, we estimate the impact of provincial financial development on the growth rates of firms by accounting for sectoral differences in growth opportunities. We find that province-level financial development promotes the growth rates of sales, investment and sales per worker of small firms, and reduces the growth rate of the wage-to-sales ratio. Our results imply that firms grow faster in provinces with a higher level of financial development. Moreover, the effect of financial development on growth rates is larger when firms operate in sectors with better growth opportunities. [ABSTRACT FROM AUTHOR]

Biomass-based aerogels are of interest due to their abundant precursors, ease of functionalization, eco-friendliness, low cost, and effectiveness in dye-contaminated water treatment. Coconut pith (CP) known as a by-product after coconut processing is a sponge-like and lightweight material discarded in large volumes. For the first time, carbon micro-particles resulting from two-step treatment and pyrolysis of CP have been successfully incorporated with chitosan to produce aerogel composites by high-speed homogenization and freeze-drying. After pretreatment, holocellulose content and crystallinity index of the recovered CP pulp are respectively 75.4 and 58.6 % along with a solid recovery rate of 27.5 %. Characteristic properties of the aerogel composites are featured by their density as low as 15.23–28.17 mg/cm3, remarkably high porosity of 98.17–99.05 %, and Young's modulus of 1.64–12.23 kPa. Synergistic effects of the porous network, electrostatic interactions between both amine groups in chitosan and carbon surface with methyl orange (MO) cause the as-fabricated aerogel composites to achieve an extremely high adsorption capacity of 454.13 mg/g and removal efficiency of 92.32 % at initial MO concentration of 500 mg/L. Therefore, the CP-derived carbon/chitosan aerogel composites synthesized from a feasible procedure exhibit their great potential in enhancing the value of coconut waste and dealing with dye-contaminated water pollution by simple and economical adsorption. [ABSTRACT FROM AUTHOR]

Bromelain, a proteolytic enzyme derived from pineapple waste, which accounts for more than two-thirds of the total volume of pineapples utilized, has gained significant attention in recent years. The employment of membrane technology has surfaced as a promising approach for the production of enzymes. A complete comprehension regarding the purification and preservation of bromelain enzymes is yet to be achieved. To address this gap, the present study aimed to extract and purify bromelain from pineapple waste to enhance the value of these by-products. The continuous microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and lyophilization system were optimized to enhance enzyme recovery and purity. The filtration process increased bromelain purity by 1.37-fold and achieved a 96.5 % enzyme recovery rate, indicating its effectiveness in separating bromelain from the pineapple crude extract. The highest activity of 3279.02 GDU/g was achieved through lyophilization, combined with 10 % of skim milk as a cryoprotectant. The product was detected and quantified using Liquid Chromatography with Refractive Index Detector (LC-RID). The combination of membrane and lyophilization processes could potentially separate bromelain from pineapple waste, with promising applications in biotechnology and the food industry. [ABSTRACT FROM AUTHOR]

Chitosan nanoparticles are a naturally derived substance with exceptional physicochemical properties and nontoxic bioactivity, making them suitable for extensive applications. This study evaluates and compares chitosan nanoparticles and chitosan nanoparticles incorporating antimicrobial agents. Copper ions were incorporated into chitosan matrices using a modified ionic gelation method to form a nano-coating solution. The particle size of chitosan nanoparticles (CN) was 118.23 ± 0.58 nm, and the particle size of chitosan nanoparticles loaded copper ions (CNCu) was 166.65 ± 7.36 nm, with low polydispersity index values and moderate to high zeta potential values. Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM) were used to determine their particle size and morphology. The antioxidant activity of chitosan nanoparticles and chitosan nanoparticles loaded with copper ions was also evaluated. CNCu exhibited superior antimicrobial activity against yeasts and molds. The results suggest CN and CNCu have great pre and post-harvest fruit preservation potential. [ABSTRACT FROM AUTHOR]

This study investigates the internal conditions of laboratory and effectiveness of ventilation system with evaporation of benzene from a hypothetical accident by using a computational fluid dynamic program. There are five inlets which moist air enter and exits through four vent hoods connecting with the exhaust fan was placed on the ceiling. The species model and the realizable k-ε turbulence model with standard wall function are used to investigate the effects of turbulence. The benzene leakage source in laboratory was modelled as vapour phase with natural evaporation rate and the ventilation system was set up with different modes such as 1,000 m³/h, 2,000 m³/h, 3,000 m³/h, and 4,000 m³/h. The objective of this research is to investigate chemical leakage and dispersion in indoor environments and consider the performance of ventilation system of different exhaust fan modes and various layout designs (single-inlet or multi-inlets). Based on the analysis of air flow patterns and the distribution of pollutant concentrations, the performance of the ventilation system is evaluated and appropriate solutions are proposed to manage the problem. The results show that in both cases of opening all doors and opening only doors, the ventilation rate of 3,000 m³/h is considered to be the most effective in terms of pollutant removal because the benzene concentration meets the safety standard (< 10 ppm), namely 4.6 ppm in the multi-inlets and 2.8 ppm in the single-inlet. [ABSTRACT FROM AUTHOR]

Liquefied Petroleum Gas (LPG) is a hydrocarbon gas that exists in liquefied form as an energy-saving, clean, convenient fuel, it has been widely used in civil and industrial applications such as oil fields, gas and oil industry. This present work considers the flammable gas release and dispersion safety evaluation caused by the LPG (50 % propane, 50 % n-butane) leakage and diffusion from an accidentally punctured pipe (with the diameters varies from 1-3 mm) during the operation of a 33 m3 LPG tank. Process equipment during a puncture can swiftly release hazardous compounds in sufficient quantities to distribute throughout a working and local area in clouds. LPG leakage diffusion model is created using the computational fluid dynamics (CFD) method, and the characteristics of LPG dispersion and the various of LPG release rate - dispersed by natural wind in an open area, with wind speeds range of 1.0 - 10.0 m/s corresponding to different atmospheric stability classes from A to F are computed and simulated. The result shows that wind speeds have a considerable impact on the spread of LPG from the release site to different distances in the domain. The maximum LPG concentration distribution is 101.71 ppm at 1 m/s wind velocity, while the minimum is 3.12 ppm at 10 m/s wind velocity. This suggests that the dispersion of LPG in the environment is minimal, accounting for roughly 0.01% of its total volume, which implies that LPG stations are not at significant risk in the event of a small puncture ranging from 1 to 3 mm in diameter. In the simulation work, the realizable k-ε model is utilised for the turbulence model. This study can provide guidance to authorities to comply with fire protection regulations, firefighting and prevention, and emergency response measures, which can ensure the safety of the factory operating in particular and neighbouring factories in the industrial area in general. [ABSTRACT FROM AUTHOR]

Chitosan - the second most abundant polysaccharide on Earth has been known as a kind of non-toxic, environmentally friendly, biodegradable, antibacterial, and antifungal material. Compared with bulk chitosanbased materials, nanochitosan has superior properties in terms of permeability, solubility, and bioactivity. Nanochitosan is used as a carrier encapsulating various components via complexes with NH2 and OH groups of chitosan molecules to protect, stabilize, and deliver targeted bioactive compounds. For the first time, chitosanzinc ion nanoparticles (CSZ NPs) have been successfully synthesized by ultrasound-assisted ionic gelation to produce much smaller particles with enhanced antibacterial and antifungal activities. The fabricated CSZ NPs have a diameter from 119.3 to 212.6 nm, polydispersity index ranging from 0.2 to 0.3, and zeta potential from 16.4 to 22.4 mV. The average size of the as-fabricated CSZ NPs is two times smaller than zinc ions loaded nanochitosan without ultrasonic treatment. The spherical shape of the nanochitosan particles is confirmed, along with a wide range of elemental distributions, including C (29.74 %), O (42.14 %), Na (15.80 %), and Zn (1.11 %). The antimicrobial activities of CSZ NPs are evaluated by using the agar well diffusion method with gramnegative bacteria (E. coli, P. aeruginosa), gram-positive (E. feacalis, S. aureus, S. aureus methicillin-resistant (MRSA)), and fungi (C. albicans, A. niger). The minimum inhibitory concentration of CSZ NPs is 14 µg/mL for bacteria and more than 58 µg/mL for fungi. CSZ NPs have potential antimicrobial applications in the food industry and agriculture. [ABSTRACT FROM AUTHOR]

Lignin derived from rice straw, an abundant renewable feedstock in nature, has the potential to be utilized as a substitute for fossil fuels in the production of value-added aromatic derivatives. However, depolymerization becomes one of the most difficult obstacles in the lignin-to-valuable products conversions due to the structural complexity and recalcitrance of lignin. In this work, rice straw-derived lignin was depolymerized to aromatics by using the hydrothermal liquefaction method in the ethanol-water solvent under hydrogen pressure. Effects of various process parameters on yields such as reaction time, ethanol concentration, reaction temperature, initial hydrogen pressure, and solvent-to-lignin ratio, were investigated. The suitable conditions for the highest yield of oil products (~ 75 %) were determined to be 65 vol. % ethanol, 250 °C, 60 min, 20 bar of hydrogen, and the solvent-to-lignin ratio of 35 mL/g. The obtained oil products were characterized by gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared (FT-IR). The bio-oil was mainly aromatics such as phenol, 3-ethylphenol, guaiacol and had a heating value of 22.2 MJ/kg. Hydrothermal liquefaction was demonstrated as an appropriate method for lignin depolymerization into aromatic compounds with high production yields. [ABSTRACT FROM AUTHOR]

This study investigates internal conditions of the solar greenhouse dryer with drying agricultural products. The operating conditions inside the solar greenhouse dryer were analysed by ANSYS Fluent software using mathematical models. Additionally, the moist air outside changed according to the climatic conditions of the day. Specifically, moist air enters the dryer through two front doors and exits through three exhaust fans installed in the back, and the flow was considered unstable and tumultuous. Agricultural products inside the solar greenhouse dryer were modelled as a porous material, and the radiation was modelled according to the radiation model. The simulation results show the distribution of temperature and humidity inside the solar drying greenhouse by the influence of heat exchange, turbulent flow, and the process of removing moisture from the drying material to the outside. The simulation results show that indoor drying temperature ranges from 303.15 K to 323.1 K at each time from 7:00 AM to 6:00 PM. The drying house reached its highest temperature at 2:00 PM. Variations of relative humidity in GHSD are between 23.70% and 79.55%. The airflow velocity inside the drying house is almost independent of time and varies based on location. [ABSTRACT FROM AUTHOR]

A continuous process flowsheet for biodiesel production from crude castor oil and methanol was developed on Aspen HYSYS™ simulation environment. It consists of an acid-catalysed sub-process for pre-treatment of the crude feedstock and a base-catalysed one for trans-esterification of treated oil. Reactions involved were defined using kinetic parameters obtained from lab-scale experiments for increased realism, and reactor setup was decided based on basic technological and economical assessments. Specifications of other unit operations and flows were obtained from different approximation methods, literature adaptation and trade-off consideration. Input and output quality controls were achieved via simple adjustments with tight tolerances. The use of crude feedstock reduced the cost of raw material while expanding the scale of the process, which managed to produce 8000 tons of biodiesel having purity of over 99 % a year. Specifically, the process could remove up to 90.83 % amount of free fatty acids in the crude oil and convert up to 93.82 % of oil to biodiesel. [ABSTRACT FROM AUTHOR]