Hasil untuk "Chemical engineering"

Cecilia Naveira-Pazos, María C. Veiga, Christian Kennes

The ability of <i>Rhodotorula toruloides</i> DSM 4444 to metabolize low-cost carbon sources such as fatty acids was comprehensively studied. This organism is shown, for the first time, to simultaneously accumulate microbial oils (biofuel precursors) and carotenoids from acetic acid obtained from CO₂ fermentation. This fatty acid is typically the single end product of acetogenic bioconversion of one-carbon gas pollutants (e.g., CO₂ and CO). In the first set of experiments, different aerobic fermentations were carried out in automated bioreactors, with acetic acid in one case and with glucose, a more conventional carbon source, as a control, in another bioreactor. <i>R. toruloides</i> consumed around 80 g/L substrate under both conditions. Maximum lipid content (27.2% g/g dry weight) was reached from 38 g/L glucose, while carotenoid content was higher with acetic acid (1.4 mg/g cell after 54.1 g/L acetic acid consumed), representing a 40% increase compared to glucose (1.0 mg/g cell after 64.2 g/L glucose consumed). Additionally, in the second set of assays, a fermented broth produced by <i>Acetobacterium woodii</i> from CO₂ fermentation, containing residual nutrients and metabolites, was tested. Despite its complex composition, <i>R. toruloides</i> grew and produced carotenoids (up to 0.141 mg/g), showing potential adaptability. To the best of our knowledge, this is the first report on a greenhouse gas-based biotechnological process as a promising sustainable alternative for the valorization of pollutants, e.g., gas emissions, their bioconversion to VFAs, such as acetic acid, and subsequent fermentation of the carboxylic acid into microbial oils, as a source of renewable energy, as well as carotenoids as a high-value nutraceutical product.

Suman Lata Yadav

The concept of life skills is related to the way of life that emphasises the mutual exchange of knowledge, attitudes, and interpersonal skills in education. Its objective is to develop diverse skills among students and prepare them to face life’s challenges with determination. The World Health Organization has defined life skills as “the positive behaviours and tendencies that enable a person to adapt in day-to-day life.” Life skills are the abilities that enable a person to adapt and exhibit positive behaviour, allowing them to deal effectively with the problems and challenges of daily life. Life is a unique gift. Therefore, by equipping life with various skills, happiness, peace, and prosperity are created. In this research, with the objectives of the study in mind, an analytical examination of life skills among secondary-level students has been conducted. This research study examines the effects of living conditions, gender, and social class on students’ life skills and presents the findings. Future researchers can build upon this, and other factors affecting the research can also be explored.

Hongyan Shi, Xiaofei Wu, Guogang Wang

Achieving satisfactory control accuracy in typical chemical processes is a challenging task. This is primarily due to their complex nonlinear dynamic characteristics. To address this challenge, this study proposes a novel deep reinforcement learning (DRL) approach that integrates an improved Ornstein-Uhlenbeck (IOU) noise into the twin delayed deep deterministic policy gradient (TD3) algorithm. This method is applied to the tracking control of continuous stirred tank reactors (CSTRs). Initially, a mechanistic model of the CSTRs system is established to simulate its dynamic environment, enabling interaction between the TD3 agent and the system. To enhance exploration capabilities and convergence speed, fractional-order characteristics and a reward feedback mechanism are introduced into the OU noise, dynamically adjusting noise intensity to improve adaptability to complex states and optimize the exploration strategy of the TD3 algorithm. Furthermore, a well-designed reward function and optimized hyperparameters enable the agent to efficiently learn the optimal control policy, achieving high-precision tracking control of the CSTRs system. Simulation results demonstrate that the proposed TD3 algorithm outperforms conventional control methods, such as PID control and nonlinear model predictive control, as well as other DRL algorithms, including SAC and PPO, in terms of control accuracy and convergence speed.

Pornanong Aramwit, Kamonpan Fongsodsri, Khwanchanok Tuentam et al.

Abstract Therapeutic treatment forms can play significant roles in resolving psoriatic plaques or promoting wound repair in psoriatic skin. Considering the biocompatibility, mechanical strength, flexibility, and adhesive properties of silk fibroin sheets/films, it is useful to combine them with anti-psoriatic agents and healing stimulants, notably silk sericin. Here, we evaluate the curative properties of sericin-coated thin polymeric films (ScF) fabricated from silk fibroin, using an imiquimod-induced psoriasis rat model. The film biocompatibility and psoriatic wound improvement capacity was assessed. A proteomics study was performed to understand the disease resolving mechanisms. Skin-implantation study exhibited the non-irritation property of ScF films, which alleviate eczema histopathology. Immunohistochemical and gene expression revealed the depletion of β-defensin, caspase-3 and -9, TNF-α, CCL-20, IL-1β, IL-17, TGF-β, and Wnt expressions and S100a14 mRNA level. The proteomics study suggested that ScF diminish keratinocyte proliferation via the mTOR pathway by downregulating mTOR protein, corresponding to the modulation of TNF-α, Wnt, and IL-1β levels, leading to the enhancement of anti-inflammatory environment by IL-17 downregulation. Hematology data demonstrated the safety of using these biomaterials, which provide a potential therapeutic-option for psoriasis treatment due to desirable effects, especially anti-proliferation and anti-inflammation, functioning via the mTOR pathway and control of IL-17 signaling.

Zohreh Masoumi, Mahdi Tayebi, S. Ahmad Masoumi Lari et al.

Photoelectrochemical (PEC) water splitting is an eco-friendly method for producing clean and sustainable hydrogen fuels. Compared with the fabrication of solar hydrogen using n-type metal oxide semiconductor photoanodes, that of solar hydrogen using p-type metal oxide semiconductor photocathodes has not been researched as thoroughly. Therefore, this study investigated the effect of drop casting time on the PEC performance of a prepared CuBi₂O₄ photocathode. XPS, HRTEM, UV-DRS, Raman spectroscopy, XRD, and SEM analyses were used to characterize the prepared CuBi₂O₄ photocathode. Owing to the high charge separation and transfer, the photocurrent density of the CuBi₂O₄ photocathode was ~0.6 mA cm⁻² at 0.3 V vs. RHE. The nanoporous CuBi₂O₄ photocathode exhibited a high photocurrent density of up to 1.2 mA cm⁻² at 0.3 V vs. RHE with H₂O₂ as a sacrificial agent. Mott–Schottky and impedance measurements were also performed on the CuBi₂O₄ photocathode to estimate its acceptor density and charge-transfer resistance.

Wenjun Zeng, Lulu Chen, Zhihui Xiao et al.

The molecular weight, the triple-helix conformation, the monosaccharide content, the manner of glycosidic linkages, and the polysaccharide conjugates of polysaccharides all affect bioactivity. The purpose of this study was to determine how different molecular weights affected the bioactivity of the <i>Lycium barbarum</i> polysaccharides (LBPs). By ethanol-graded precipitation and ultrafiltration membrane separation, one oligosaccharide (LBPs-1, 1.912 kDa) and two polysaccharides (LBPs-2, 7.481 kDa; LBPs-3, 46.239 kDa) were obtained from <i>Lycium barbarum</i>. While the major component of LBPs-1 and LBPs-2 was glucose, the main constituents of LBPs-3 were arabinose, galactose, and glucose. LBPs-2 and LBPs-3 exhibited triple-helix conformations, as evidenced by the Congo red experiment and AFM data. Sugar residues of LBPs-2 and LBPs-3 were elucidated by NMR spectra. The polysaccharides (LBPs-2 and LBPs-3) exhibited much higher antioxidant capacities than oligosaccharide (LBPs-1). LBPs-3 showed higher oxygen radical absorbance capacity (ORAC) and superoxide dismutase (SOD) activity than LBPs-2, but a lower capability for scavenging ABTS⁺ radicals. In zebrafish, LBPs-2 and LBPs-3 boosted the growth of T-lymphocytes and macrophages, enhanced the immunological response, and mitigated the immune damage generated by VTI. In addition to the molecular weight, the results indicated that the biological activities would be the consequence of various aspects, such as the monosaccharide composition ratio, the chemical composition, and the chemical reaction mechanism.

Rizki Ramadhan, Syamsul Bahri, Agam Muarif et al.

Proses pembuatan furfural dari biomassa (ampas tebu) melalui dua tahap reaksi, yaitu hidrolisa dan dehidrasi. Pertama kali mengalami hidrolisa pentosan menjadi pentosa, yang diikuti dengan tahap dehidrasi pentosa menjadi furfural dengan bantuan katalis asam sulfat. Produk yang dihasilkan dianalisa jumlah dan konsentrasi furfural yang dihasilkan dengan cara titrasi menggunakan larutan Na2S2O3 0.1 N, analisa densitas dengan alat piknometer dan analisa viskositas menggunakan alat viskositas Ostwald. Proses hidrolisa ini berlangsung pada temperatur 1100C serta konsentrasi asam sulfat 10% dengan volume 150 ml dan menggunakan pelarut aquades 40 ml dan juga memvariasikan ukuran sampel sebesar 20, 50, 80 dan 100 mesh dan waktu operasi 90, 120, 150 dan 180 menit. Hasil terbaik diperoleh pada penelitian kali ini pada ukuran bahan baku 100 mesh dengan waktu operasi 150 menit dan jumlah furfural yang dihasilkan sebesar 0.2467 gram dengan konsentrasi furfural sebesar 1.656 gr/L.

Bailing An, Yan Xin, Rongmei Niu et al.

To study discontinuous precipitation, which is an important method for strengthening materials, we observed the nucleation and growth of discontinuous precipitates in Cu–Ag alloys using electron backscatter diffraction and scanning transmission electron microscopy. We found that discontinuous precipitation always started with Ag precipitates, which nucleated on Cu grain boundaries. These precipitates then each took the shape of a large, abutted cone that shared a semi-coherent interface with one of the Cu grains, topped by a small spherical cap that shared an incoherent interface with the Cu grain on the opposite side of the boundary. This formation created a difference between the levels of interface energy on each side of boundary. We assume that this difference and boundary curvature together generates the driving force necessary to push grain boundary migration, thus triggering discontinuous precipitation. Because of grain boundary migration, Ag solute was consumed at one side of the grain, which causes a solute difference. The difference produces mainly driving force, pushing the boundaries to migrate forward.

Hao-Chen Wu, Tomohisa Yoshioka, Keizo Nakagawa et al.

The use of an Amphotericin B_Ergosterol (AmBEr) channel as an artificial water channel in forward osmosis filtration (FO) was studied via molecular dynamics (MD) simulation. Three channel models were constructed: a common AmBEr channel and two modified C3deOAmB_Ergosterol (C3deOAmBEr) channels with different diameters (12 Å and 18 Å). During FO filtration simulation, the osmotic pressure of salt-water was a driving force for water permeation. We examined the effect of the modified C3deOAmBEr channel on the water transport performance. By tracing the change of the number of water molecules along with simulation time in the saltwater region, the water permeability of the channel models could be calculated. A higher water permeability was observed for a modified C3deOAmBEr channel, and there was no ion permeation during the entire simulation period. The hydrated ions and water molecules were placed into the channel to explore the ion leakage behavior of the channels. The mean squared displacement (MSD) of ions and water molecules was obtained to study the ion leakage performance. The Amphotericin B-based channels showed excellent selectivity of water molecules against ions. The results obtained on an atomistic scale could assist in determining the properties and the optimal filtration applications for Amphotericin B-based channels.

Costa Bruna Muriel F., Coelho Carolina Monteiro, Souza Cássia Ribeiro et al.

Malt bagasse is a by-product of the brewing industry that has high moisture, making it very unstable and susceptible to fast microbial deterioration. This work evaluated drying kinetic models of malt bagasse during pneumatic transport with air flow at 30, 45 and 60°C and layouts of 4.5 and 7.0 m. The results showed that the decrease of moisture from malt bagasse was favored at higher air temperature due to the higher diffusion coefficient. In the ranges measured, the values of the effective moisture diffusivity and heat transfer coefficient were obtained between 2.05×10−10 to 12.74×10−10 m2/s and 175 to 363 W/(m2 K), respectively. Average energy for liquid diffusion in the malt bagasse drying process was 44.30 kJ/mol. Pneumatic transport with air flow at 60°C and layout of 7.0 m reached rapidly the final moisture of 12% (w.b.), which may reduce transport costs and allow for long periods of stable storage for malt bagasse. The statistical tests results showed that the experimental data presented excellent fit using the modified Henderson-Pabis model, in the temperature range for both layouts.

Changyin Gan

In this research, the concentration effect of silica nanoparticles on electrochemical and strain sensitivity of smart polymer concretes were investigated. Silica nanoparticles with uniform and spherical morphology was synthesized by in situ sol-gel method. The structural properties of synthesized silica nanoparticles were studied by X-ray diffraction and Fourier transform infrared analyses, showing the amorphous and high stable phase of the nanoparticles. Strain sensitivity of smart polymer concrete was enhanced with increasing the concentration of silica nanoparticles in concretes. A very large variation of resistance was observed under mechanical strain because of higher mobility of silica nanoparticles and their stronger adhesion to the polymer matrix. Electrochemical corrosion of steel rebars were considered by electrochemical impedance spectroscopy technique which indicated that the addition of silica nanoparticles in cement content led to improve the thickness, corrosion resistance and stability of passive film on steel rebar.

Guillaume Henry, Alexandra Pere-Gigante, Jacopo Siewert et al.

The most common way to produce hydrogen at an industrial scale is, by far, the Steam Methane Reforming (SMR) process. The ever-growing interest about hydrogen as the fuel of the future has led to a redesign of the process for smaller production capacity. The intensification of the SMR process concerns different pieces of equipment such as the heat-exchanger reactor, the shift reactor or the vaporizer. In this paper, an intensified vaporizer is studied for the vaporization of water in 2 mm diameter channels with semi-circular cross section. The vaporizer is tested, and the effect of the various operating parameters (flowrates, temperatures and pressure) on the vapour quality produced is analysed.

Sutini Sutini, Susilowati Susilowati, M Rasjad Indra et al.

This study was aimed to assess flavan-3-ol biomass in C. sinensis through callus cultures and suspension cultures derived from leaf explants. Callus initiation of both cultures were using Murashige and Skoog medium were enriched with plant growth regulators Naphtha-lene Acetic Acid 3.0 mg/L and kinetin 2.0 mg/L. The procedures in this study were: (1) callus initiation by cutting the leaves of C. sinen-sis shoots then planted on Murashige and Skoog medium that were enriched with plant growth regulators, (2) sub callus culture on fresh medium that enriched with the same growth regulators, (3) suspension culture initiation of liquid callus, (4) growth examination of callus and suspension cultures in week 12, (5) examination of qualitative-quantitative content of flavan-3-olin suspension cultures at week 4. The results show that suspension cultures contain biomass flavan-3-ol that increase in the same manner of the increase of callus age and weight

Eslam Kashi, Farshad Mirzaei, Farzad Mirzaei

In some instances, it is inevitable that large amounts of potentially hazardous chemicals like chlorine gas are stored and used in facilities in densely populated areas. In such cases, all safety issues must be carefully considered. To reach this goal, it is important to have accurate information concerning chlorine gas behaviors and how it is dispersed in dense urban areas. Furthermore, maintaining adequate air movement and the ability to purge ambient from potential toxic and dangerous chemicals like chlorine gas could be helpful. These are among the most important actions to be taken toward the improvement of safety in a big metropolis like Tehran. This paper investigates and analyzes chlorine gas leakage scenarios, including its dispersion and natural air ventilation  effects on how it might be geographically spread in a city, using computational  fluid dynamic (CFD). Simulations of possible hazardous events and solutions for preventing or reducing their probability are presented to gain a better insight into the incidents. These investigations are done by considering hypothetical scenarios which consist of chlorine gas leakages from pipelines or storage tanks under different conditions. These CFD simulation results are used to investigate and analyze chlorine gas behaviors, dispersion, distribution, accumulation, and other possible hazards by means of a simplified CAD model of an urban area near a water-treatment facility. Possible hazards as well as some prevention and post incident solutions are also suggested.