Hasil untuk "Chemical technology"

Nei Pereira Junior

Lignocellulosic biomass is one of the most abundant renewable carbon resources available, currently used predominantly for energy generation through direct combustion, yet still underutilized as a feedstock for higher-value biochemical conversion. Its structural complexity and intrinsic recalcitrance continue to challenge efficient biological processing. Overcoming these barriers requires an integrated understanding of plant cell-wall architecture, pretreatment chemistry, enzymatic mechanisms, and process engineering. This review provides a clear and conceptually grounded synthesis of these elements, illustrating how they converge to enable the development of second-generation (2G) lignocellulosic biorefineries. This review examines the hierarchical organization of cellulose, hemicelluloses, and lignin; the principles and performance of modern pretreatment technologies; the synergistic action of cellulolytic systems, including lytic polysaccharide monooxygenases (LPMOs) and non-hydrolytic proteins such as swollenins; advances in C5/C6 sugar fermentation; and emerging strategies for lignin upgrading. In addition to a comprehensive analysis of the literature, representative industrial and experimental case studies reported in the literature are discussed to illustrate practical process behavior and design considerations. By integrating mechanistic insight with industrially relevant examples, this review highlights the technical feasibility, current maturity, and remaining challenges of lignocellulosic biorefineries, underscoring their strategic role in enabling a competitive, low-carbon bioeconomy.

Cuixia Liu, Meng Meng, Xian Luo

Based on the innovative mode driven by “data + artificial intelligence”, in this study, three methods, namely Gaussian noise (GAUSS Noise), the Generative Adversarial Network (GAN), and the optimized Generative Adversarial Network (GANPro), are adopted to expand and enhance the collected dataset of element contents and the hardness of the AlCoCrCuFeNi high-entropy alloy. Bayesian optimization with grid search is used to determine the optimal combination of hyperparameters, and two interpretability methods, SHAP and permutation importance, are employed to further explore the relationship between the element features of high-entropy alloys and hardness. The results show that the optimal data augmentation method is Gaussian noise enhancement; its accuracy reaches 97.4% under the addition of medium noise (σ = 0.003), and an optimal performance prediction model based on the existing dataset is finally constructed. Through the interpretability method, it is found that the contributions of Al and Ni are the most prominent. When the Al content exceeds 0.18 mol, it has a positive promoting effect on hardness, while Ni and Cu exhibit a critical effect of promotion–inhibition near 0.175 mol and 0.14 mol, respectively, revealing the nonlinear regulation law of element contents. This study solves the problem of revealing the mutual relationship between the element contents and hardness of high-entropy alloys in the case of a lack of alloy data and provides theoretical guidance for further improving the performance of high-entropy alloys.

Samantha N. Atkinson, Caron Dean, Victoria L. Woyach et al.

Childhood and adolescent obesity and its associated morbidities are increasing in part due to the ingestion of diets high in fat (HFD). Changes in the gastrointestinal microbiome have been associated with these morbidities, including insulin resistance, cardiovascular disease, and inflammatory states. The use of dietary probiotics may mitigate these microbiome-associated morbidities and improve health during maturation. Using our established model of obesity in rats consuming an HFD from weaning, we examined the gut microbiome with a single-strain probiotic in the drinking water [<i>Lactiplantibacillus plantarum</i> 299v (Lp299v, LP299V^®)] of adolescent and adult rats. Our main finding was a differential effect of HFD and probiotic on the gut microbiome that was associated with maturation (adolescence vs. adulthood). Specifically, probiotic treatment of adolescent rats on an HFD led to alterations in the enrichment of the gut microbiome, which were associated with the morbidities of obesity, while adult rats under the same conditions exhibited minimal changes, demonstrating differences in plasticity associated with maturation. Of particular relevance in this regard is the fact that <i>Oscillospiraceae</i> and <i>Lachnospiraceae,</i> associated with beneficial short-chain fatty acid production, were enriched in adolescent rats on an HFD and treated with Lp299v. Our data suggest that the use of probiotics in childhood and adolescence may improve health in adulthood by potentially affecting the developing gastrointestinal microbiome.

Elyse S. Czapalay, Yasamin Soleimanian, Jarvis A. Stobbs et al.

Cellulosic scaffolds filled with oil were designed to replicate animal adipose tissues. Many plants are structured as polysaccharide-based cellular solids. They maintain their integrity after drying, can serve as a scaffold for incorporating fat, and do not lose integrity upon heating, thus resembling native adipose tissue. Carrots, broccoli, and asparagus were freeze-dried and subsequently filled with peanut oil, its glycerolysis product (GP), and the oleogel of this GP. Oleogel-filled scaffolds displayed high oil binding capacity (≥95%), and an oil loss resembling that of adipose tissue. In addition, the texture of oleogel-filled asparagus and broccoli tissue closely resembled that of beef and pork adipose tissues, respectively. Plant scaffolds closely emulated the temperature-dependent rheological behavior of adipose tissue. These new materials could significantly improve the quality of plant-based meat analogues, such as burgers and sausages, by preventing the thermal softening of the material upon cooking and excessive oil loss.

Li Chen, Yuan Tian, Nana Zhang et al.

To prevent toxic and harmful gas suffocation accidents in underground metal mine stopes, the Fluent numerical simulation method was employed to investigate the wind field distribution patterns and the diffusion laws of blasting fumes in stopes with and without middle–end roadways under varying effective ranges. The simulation accuracy was validated through laboratory experiments. The results demonstrate that over time, the CO concentration in the blasting area decreases, while in other regions of the stope, it initially increases before declining. The presence or absence of a middle roadway does not significantly alter the migration and diffusion behavior of blasting fumes in the stope. When the effective range is ER–1, the simulation error is only 8 s. As the effective range increases, the time required to reduce the CO concentration to 24 ppm on the respiratory plane, across the entire space, and at the monitoring point follows a linearly increasing trend. Meanwhile, the maximum wind speed at the working face exhibits a linearly decreasing trend, whereas the peak CO concentration shows a linearly increasing trend. Under the ER–1 effective range, the CO concentration can be reduced to a safe threshold more rapidly. The experimental and simulation results exhibit an error margin within 16.97%, confirming the accuracy of the numerical simulation.

Ammad Aslam, Octavian Postolache, Sancho Oliveira et al.

Sharding is an emerging blockchain technology that is used extensively in several fields such as finance, reputation systems, the IoT, and others because of its ability to secure and increase the number of transactions every second. In sharding-based technology, the blockchain is divided into several sub-chains, also known as shards, that enhance the network throughput. This paper aims to examine the impact of integrating sharding-based blockchain network technology in securing IoT sensors, which is further used for environmental monitoring. In this paper, the idea of integrating sharding-based blockchain technology is proposed, along with its advantages and disadvantages, by conducting a systematic literature review of studies based on sharding-based blockchain technology in recent years. Based on the research findings, sharding-based technology is beneficial in securing IoT systems by improving security, access, and transaction rates. The findings also suggest several issues, such as cross-shard transactions, synchronization issues, and the concentration of stakes. With an increased focus on showcasing the important trade-offs, this paper also offers several recommendations for further research on the implementation of blockchain network technology for securing IoT sensors with applications in environment monitoring. These valuable insights are further effective in facilitating informed decisions while integrating sharding-based technology in developing more secure and efficient decentralized networks for internet data centers (IDCs), and monitoring the environment by picking out key points of the data.

Elena Laura Mazzoldi, Giulia Gaudenzi, Paola Serena Ginestra et al.

IntroductionTissue engineering has advanced significantly in recent years, owing primarily to additive manufacturing technology and the combination of biomaterials and cells known as 3D cell printing or Bioprinting. Nonetheless, various obstacles remain developing adequate 3D printed structures for biomedical applications, including bioinks optimization to meet biocompatibility and printability standards. Hydrogels are among the most intriguing bioinks because they mimic the natural extracellular matrix found in connective tissues and can create a highly hydrated environment that promotes cell attachment and proliferation; however, their mechanical properties are weak and difficult to control, making it difficult to print a proper 3D structure.MethodsIn this research, hydrogels based on Alginate and Gelatin are tested to evaluate the metabolic activity, going beyond the qualitative evaluation of cell viability. The easy-to-make hydrogel has been chosen due to the osmotic requirements of the cells for their metabolism, and the possibility to combine temperature and chemical crosslinking. Different compositions (%w/v) are tested (8% gel-7% alg, 4% gel-4% alg, 4% gel-2% alg), in order to obtain a 3D structure up to 10.3 ± 1.4 mm.ResultsThe goal of this paper is to validate the obtained cell-laden 3D structures in terms of cell metabolic activity up to 7 days, further highlighting the difference between printed and not printed cell-laden hydrogels. To this end, MS5 cells viability is determined by implementing the live/dead staining with the analysis of the cellular metabolic activity through ATP assay, enhancing the evaluation of the actual cells activity over cells number.DiscussionThe results of the two tests are not always comparable, indicating that they are not interchangeable but provide complementary pieces of information.

Andrey Smirnov, Vladimir Anisimkin, Natalia Voronova et al.

The detection of the liquid-to-ice transition is an important challenge for many applications. In this paper, a method for multi-parameter characterization of the liquid-to-ice phase transition is proposed and tested. The method is based on the fundamental properties of bulk acoustic waves (BAWs). BAWs with shear vertical (SV) or shear horizontal (SH) polarization cannot propagate in liquids, only in solids such as ice. BAWs with longitudinal (L) polarization, however, can propagate in both liquids and solids, but with different velocities and attenuations. Velocities and attenuations for L-BAWs and SV-BAWs are measured in ice using parameters such as time delay and wave amplitude at a frequency range of 1–37 MHz. Based on these measurements, relevant parameters for Rayleigh surface acoustic waves and Poisson’s modulus for ice are determined. The homogeneity of the ice sample is also detected along its length. A dual sensor has been developed and tested to analyze two-phase transitions in two liquids simultaneously. Distilled water and a 0.9% solution of NaCl in water were used as examples.

M. Abdinejad, B. Talaie, H. S. Qorbani et al.

Sahil Bhagat, Jacopo Bongiorno, Andrea Mariscotti

Stray current is a relevant phenomenon in particular for DC electrified transportation systems, affecting track and infrastructure within the right of way and other structures and installations nearby. It worsens with time and the level of protection depends on timely maintenance, as well as correct design choices. The assessment of track insulation is the starting point for both stray current monitoring systems and at commissioning or upon major changes. Standardized methods (ref. EN 50122-2 or IEC 62128-2) have been almost unchanged in the last 20 years but suffer from accuracy issues and variability due to parameters and conditions not under the operator’s control. The uncertainty of test methods is increasingly important now that contractual specifications require a high level of insulation for new systems. A critical discussion and analysis of the sources of variability and practical constraints is proposed, followed by an evaluation of uncertainty, with the objective not only to assess the accuracy of the provided results, but also to foster research on innovative, more flexible and accurate methods.

Yizhou Dai, Huan Li, Chuanhao Wang et al.

Abstract Electrochemical CO2 conversion to methane, powered by intermittent renewable electricity, provides an entrancing opportunity to both store renewable electric energy and utilize emitted CO2. Copper-based single atom catalysts are promising candidates to restrain C-C coupling, suggesting feasibility in further protonation of CO* to CHO* for methane production. In theoretical studies herein, we find that introducing boron atoms into the first coordination layer of Cu-N4 motif facilitates the binding of CO* and CHO* intermediates, which favors the generation of methane. Accordingly, we employ a co-doping strategy to fabricate B-doped Cu-N x atomic configuration (Cu-N x B y ), where Cu-N2B2 is resolved to be the dominant site. Compared with Cu-N4 motifs, as-synthesized B-doped Cu-N x structure exhibits a superior performance towards methane production, showing a peak methane Faradaic efficiency of 73% at −1.46 V vs. RHE and a maximum methane partial current density of −462 mA cm−2 at −1.94 V vs. RHE. Extensional calculations utilizing two-dimensional reaction phase diagram analysis together with barrier calculation help to gain more insights into the reaction mechanism of Cu-N2B2 coordination structure.

D. L. Smith, D. W. Hoffman

Clara Medina-García, Clara Medina-García, Sharmada Nagarajan et al.

Literatures on social innovation, collective agency and multi-actor collaboration stress the importance of action research and joint problematization to research ongoing processes of collaboration and transformation to advance both theory and practice in these fields. In this paper we analyze our experience building a transdisciplinary action research (TAR) trajectory between 2020 and 2021 to investigate socially innovative multi-actor collaborations (IMACs) and urban governance innovation trajectories in the city of Leuven (Belgium). We specifically focus on (1) how we involved a wide array of researchers, stakeholders and practitioners in the TAR trajectory; (2) how we enacted joint problematization and action, ensuring that all facilitative leadership roles were taken care of; (3) the challenges that the specific COVID context posed on TAR and the innovative tools and approaches we took to adapt under such circumstances; and (4) how our TAR contributed to the ongoing IMACs in Leuven. Discussing our experience in relation to issues raised in action research literature, we summarize key dimensions, roles and tasks necessary in TAR to enable facilitative leadership and multi-actor collaboration and successfully drive joint problematization and transformative change. We conclude that our TAR trajectory in Leuven became a case study of IMAC in itself, and so learnings from our TAR directly dialogue with and inform our empirical analysis of the performance of IMACs too. Through this realization and the analysis of our experience, we get to broader question the role of action research and researchers in urban governance innovation.

Hailu Gemechu Benti, Abraham Debebe Woldeyohannes, Belete Sirahbizu Yigezu

The challenge of enhancing cutting tool life has been dealt with by many research studies. However, this challenge seems endless with growing technological advancement which brings about incremental improvement in tool life. The objective of this review paper is focused at assessing filtered cathodic vacuum arc deposition techniques applied on cutting tools and their effect on tool efficiency. The paper particularly picks filtered cathodic vacuum arc deposition (FCVAD) among other well-identified methods of coating like the Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD). Filtered Cathodic Vacuum Arc Deposition is the state of art in the coating technology finding wide application in the electronics industry and medical industry in addition to the machining industry, which is the concern of this review paper. This review is made in order to summarize and present the various techniques of FCVAD coatings and their applications, as investigated by various researches in the area.

M. Czarnecki, Y. Morisawa, Y. Futami et al.

B. O'Regan, J. Durrant

S. McGrath, J. Zhao, E. Lombi

A. Tremel, P. Wasserscheid, M. Baldauf et al.

Liang Zhang, Rong Feng, Songhe Geng et al.

Seepage-type gas hydrate accumulation in subsea shallow formations involves complicated thermo-hydro-solid coupling processes and matching problem between various accumulation elements. The formation physical properties control local natural gas migration pathway and thus the final reservoir characteristics of hydrates. In this paper, a novel mixed-flux model for gas hydrate accumulation is established and then used to simulate the process of methane gas migration into the shallow stratum to form a hydrate reservoir. The effects of reservoir heterogeneity and gas source conditions on the distribution of pore fluid and hydrate accumulation are examined. The simulation results show that reservoir heterogeneity is conducive to the retention and lateral migration of CH4 in a hydrate stability zone. CH4 can contact more pore water to form a large hydrate reserve, but the formed hydrate is often dispersed. Low-permeability layers enhance the trapping of CH4 and form a uniform and large hydrate saturation. Besides, gas source conditions have an important impact on the hydrate accumulation in reservoirs. Large gas flux, small pore water flux, continuous gas supply, high content of heavy components in natural gas, and numerous gas source points contribute to large amounts of hydrates generation in a certain time period. The presented work will deepen our understanding of the controls of natural gas hydrate systems in subea shallow formations.

B. Kuswandi, Yudi Wicaksono, Jayus et al.