Search Results (123)

Agro-industrial waste impacts populations worldwide. Food waste, in turn, is a major source of complex lipids, carbohydrates, and other substances. Therefore, it is crucial to convert food waste into products that reduce environmental problems. Enzymatic hydrolysis has advantages over chemical hydrolysis. Examples include the enzymatic hydrolysis of starch by α-amylase and the hydrolysis of inulin by inulinase, which occur under milder environmental and temperature conditions than acid hydrolysis of starch or inulin. Despite these milder temperature conditions, during substate hydrolysis, enzyme deactivation occurs under exposure to temperature. As temperature increases above $T_{opt}$ (which maximizes catalytic activity), enzyme deactivation becomes more pronounced, leading to a decrease in enzyme activity. Therefore, determining the rate constant of deactivation $k_d$, during biotransformation is an important aspect in understanding enzyme kinetics. Most experimental studies focus on changes in enzyme activity with time and temperature. However, enzyme deactivation also occurs during enzymatic reactions conducted at different temperatures, and this process is characterized by specific deactivation parameters. The study is to present the rate constants of deactivation $k_d$, for selected biotransformation processes. The selected biotransformation processes are hydrolysis of olive oil by lipase, hydrolysis of inulin by inulinase, and hydrolysis of starch by α-amylase. Given the widespread use of enzymes in industry, the information on enzyme deactivation presented in this study can be used by engineers involved in modeling and optimizing enzymatic processes. This knowledge is also essential for the effective and sustainable use of enzymes in industrial applications. It is important to emphasize that the deactivation parameters discussed in this study also carry significant economic, social, and environmental implications. Full article

Multichannel vortex beams serve as an essential physical source for enabling multi-spot laser processing and high-dimensional spatial multiplexing communications. We demonstrate a compact, flexibly tunable multichannel vortex beam generator using spatially structured bidirectional two-color pump vortex four-wave mixing in a single ¹³³Cs vapor cell. To enhance spatial multiplexing, both sides of the cell are utilized. By engineering the propagation directions and frequencies of five input beams, we establish a nonlinear interaction region that supports 16 concurrent phase-matching conditions, thereby enabling the parallel generation of up to eight vortex channels. The orbital angular momentum of the output beams follows deterministic algebraic rules, allowing for programmable control via tailored input orbital angular momentum combinations. Moreover, the channel count can be linearly tuned by selectively deactivating pumps—each switched-off pump reduces the number of output channels by two. This flexible control over orbital angular momentum states, together with channel count and spatial arrangement, establishes a highly integrated platform for on-demand vortex generation. This work highlights the potential of spatially bidirectional structured pumping in atomic vapor to expand optical dimensionality and enhance multiplexing capacity, paving the way toward multidimensional communications, quantum networks, and integrated photonics. Full article

Nitrogen oxides represent a major source of concern related to atmospheric pollution, causing substantial impacts on human health. One innovative approach to reducing these emissions, and a promising alternative to conventional methods using NH₃, is selective catalytic reduction with carbon (SCR-C). The aim of this study is the development of carbon-based catalysts that are active in the reduction of NO. For that, carbon nanotubes were subjected to treatments to modify their surface chemistry, including introducing oxygen and nitrogen groups, as well as potassium (K) and copper (Cu) incorporated as metal phases. In their original form, carbon nanotubes do not exhibit catalytic activity in reducing NO. However, catalytic performance is significantly improved by the addition of surface groups and Cu. Adding K to the support notably contributes to increasing the catalytic performance. N-doped carbon nanotubes impregnated with copper and potassium (CNT_M_BM@5Cu5K) achieved complete NO reduction at 360 °C. In this catalytic system, the formation of CO₂ and N₂ was observed and CO was not identified. Furthermore, although N₂O was detected during the reaction, its amount was very low compared to the N₂ and CO₂ products. The stability of this catalyst was investigated over 87 h continuous test, revealing deactivation after 41 h of reaction. Full article

This study analyzes the characteristics of natural lighting and artificial lighting illuminance, correlated color temperature (CCT), and color rendering index (CRI), and their impact on driver visibility. A real-vehicle experiment was conducted to assess visual recognition distances for small targets under various lighting conditions: six levels of natural light illuminance, and artificial lighting combinations of four CCT levels (3000–6000 K) and five illuminance levels (7.5–67.5 lx). Regression models were developed to relate light source characteristics to visual recognition distance. At low speeds (40 km/h), the natural light illuminance thresholds for activating/deactivating road lighting match current standards. At higher speeds (60 km/h, 80 km/h, and 100 km/h), these thresholds increase significantly, reaching 2, 5.5, and 22 times the standard values, suggesting safety risks at speeds ≥60 km/h. The study also finds that visual recognition distance decreases and then increases with rising CCT, with a minimum at 4000 K and a maximum at 6000 K. At 6000 K, the required illuminance thresholds decrease by 52.32%, 47.74%, and 58.31% at 60 km/h, 80 km/h, and 100 km/h, respectively. The research findings provide a reference for optimizing road lighting control strategies, balancing road safety and energy efficiency. Full article

The study aims to develop a method for obtaining a high-performance catalyst for the synthesis of liquid hydrocarbons using the Fischer–Tropsch method based on ultradisperse cobalt powders obtained by the electric explosion method. To determine the catalytic activity of the obtained catalyst samples, the main process parameters, like temperature in the catalyst bed, the process pressure, the feedstock space velocity, and the ratio of reagents in the synthesis gas, were varied. It has been established that highly dispersed cobalt powder obtained by the electrical explosion method is a fairly active catalyst for the synthesis of liquid hydrocarbons via the Fischer–Tropsch process. It has been established that the overall CO conversion rate in the temperature range from 230 to 330 °C ranges from 25 to 90%. However, the formation of the main byproduct of the synthesis, carbon dioxide, is not observed below 270 °C. It was determined that for the developed catalyst sample, the optimal temperature range is from 230 to 260 °C, in which the yield of by-products of synthesis and gaseous hydrocarbons is quite low—the selectivity for methane does not exceed 20%, with the proportion of C₅₊ hydrocarbons in the liquid phase at the level of 80%. The CO conversion rate increases proportionally with growing pressure. It has been established that cobalt nanopowder exhibits high catalytic activity in reactions of liquid hydrocarbon formation with low hydrogen content in the initial synthesis gas. This fact allows us to conclude that it has potential for use in processing gases obtained during the pyrolysis of biomass or other non-traditional sources of synthesis gas, characterized by an H₂:CO ratio of 1:1 to 1.25:1. Catalysts obtained from ultradisperse cobalt powders were shown to be resistant to rapid deactivation under synthesis conditions at operating temperatures for 30 h. During long-term testing, CO conversion remained at 23.5% at 230 °C for the entire duration of the experiment. Full article

In the context of micro-polluted water sources, the performance decline of filtration units is a major challenge for the operational management of water supply plants. Therefore, it is necessary to systematically analyze the mechanism underlying the decline in filter media activity and optimize the pre-filtration treatment. This study focuses on waterworks, aiming to enhance filtration performance through filter media modification and a combined coagulant-oxidant strategy. A key innovation of this work is the development of a macro-microscopic correlation evaluation system. The results showed that the modified filter media increased the turbidity removal rate by 10.48% compared to the unmodified media. Furthermore, the combined coagulation–pre-oxidation scheme increased the removal rates for turbidity and UV₂₅₄ by 3.24% and 19.03%, respectively, compared to the single-process scheme. Combined with filter media characterization results, the deactivation mechanism of filter media can be inferred. During the high-algae period, microorganisms on the filter media generate anaerobic Extracellular Polymeric Substances (EPS), which form a biofilm with bacteria and adhere to the filter media. The viscous matrix of these EPS then encapsulates inorganic substances, resulting in hard-to-remove clumps. These clumps clog pores and hinder the adsorption of subsequent pollutants, ultimately leading to continuous deterioration in filter media performance until failure. Full article

(1) Lifestyle changes to modify unhealthy dietary patterns with the goal of preventing MASLD have proven challenging. Here, dietary proteins and their modification with ammonium hydroxide enhancement (AHE) provide molecular evidence that this novel approach may attenuate the development of MASLD without undue dietary adjustments, potentially bypassing non-compliance. (2) High-fat diets containing dietary beef (HFB) or casein (HFC) + AHE (HFBN and HFCN, respectively) were fed to 256 C3H/HeJ female and male mice long term. At 6, 12, or 18 months, hepatic samples were analyzed with targeted metabolomics (glucose, lactate, alanine, glutamine, carnitine) and Western analysis (β-catenin, glutamine synthetase, CYP3A4). RNA sequencing was performed on samples collected at 18 months (n = 3; male HFC n = 2). (3) Metabolomics results showed that at 18 months, hepatic glutamine was greater in HFBN versus HFCN in females, whereas in males, hepatic glutamine, glucose and lactate were lower in HFBN versus HFCN. Additionally, diets with AHE decreased β-catenin and CYP3A4 protein expression in males. Ingenuity pathway analysis (IPA) of RNA-seq data predicted that HFBN activates PPARα signaling in the liver in both sexes compared to HFCN. Inflammatory activity showed predicted activation for females in the HFBN:HFCN comparison. In males, the inflammatory pathway molecular mechanisms of cancer was predicted as deactivated in HFBN:HFCN. (4) Dietary protein source impacts outcomes, and these outcomes improved with AHE. The HFBN diet improves signaling associated with lipid utilization for females and males, and improved inflammatory signaling for males compared with HFCN. Further exploration of AHE as a dietary intervention in high-fat diets is warranted. Full article

Density functional theory (DFT) and its extension, time-dependent DFT (TD-DFT), have become fundamental tools for modeling chiral excited states and supporting experimental chiroptical spectroscopies. In this connection, the interest in understanding the asymmetric emission through the circularly polarized luminescence (CPL) technique peaked in the current decade. In the present work, we are computationally faced with an emerging class of luminophores which combines the luminogenic source of the BODIPY unit with the intrinsic chirality of the helicene pendant to obtain a chiral radiative deactivation. In particular, a meso-substituted BODIPY-[6]helicene was deeply examined through a DFT multistep approach to attain an appreciable level of theory for the CPL simulation. Among the multitude of alternatives, TPSSTPSS exchange-correlation functional with 6-311G(d,p) basis set revealed to be the best computational protocol to emulate the CPL spectral profile with regard to peak intensity, band position, and chiral sign for both M and P form. Full article

A Si/SiC heterojunction double-trench MOSFET with improved conduction characteristics is proposed. By replacing the N+ source and P-ch regions with silicon, the device forms a Si/SiC heterojunction that exhibits Schottky-like characteristics, effectively deactivating the parasitic PiN body diode and improving third-quadrant performance. A high-k gate dielectric is incorporated to induce a strong electron accumulation layer at the heterointerface, thinning the energy barrier and enabling tunneling-dominated current transport, thereby significantly enhancing the first-quadrant performance. TCAD simulation results demonstrate that the proposed device achieves a specific on-resistance (R_on,sp) of 1.78 mΩ·cm², representing a 20.5% reduction compared to the conventional SiC DTMOS, while maintaining a comparable breakdown voltage (BV) of approximately 1380 V. A significant reduction in the third-quadrant turn-on voltage (V_on) is achieved with the proposed structure, from 2.74 V to 1.53 V. Meanwhile, the unipolar conduction mechanism similar to that of Schottky effectively suppresses bipolar degradation. To enhance device reliability, the design incorporates a trenched source and heavily doped P-well, which collectively mitigate high electric field concentrations at the trench corners. The proposed device offers an integration strategy enhancing both forward conduction and reverse conduction in high-voltage power electronics. Full article

We consider optimization for different production requirements from the viewpoint of a bio-inspired framework for system flexibility that allows us to study the ability of an algorithm to transfer solutions from previous optimization tasks, which also relates to dynamic evolutionary optimization. Optimizing manufacturing process parameters is typically a multi-objective problem with often contradictory objectives, such as production quality and production time. If production requirements change, process parameters have to be optimized again. Since optimization usually requires costly simulations based on, for example, the Finite Element method, it is of great interest to have a means to reduce the number of evaluations needed for optimization. Based on the extended Oxley model for orthogonal metal cutting, we introduce a multi-objective optimization benchmark where different materials define related optimization tasks. We use the benchmark to study the flexibility of NSGA-II, which we extend by developing two variants: (1) varying goals, which optimizes solutions for two tasks simultaneously to obtain in-between source solutions expected to be more adaptable, and (2) active–inactive genotype, which accommodates different possibilities that can be activated or deactivated. Results show that adaption with standard NSGA-II greatly reduces the number of evaluations required for optimization for a target goal. The proposed variants further improve the adaption costs, where on average, the computational effort is more than halved in comparison to the non-adapted baseline. We note that further work is needed for making the methods advantageous for real applications. Full article

Enzymes are highly selective and efficient biological catalysts that play a critical role in modern industrial biocatalysis. Their ability to operate under mild conditions and reduce environmental impact makes them ideal alternatives to conventional chemical catalysts. This review provides a comprehensive overview of advances in enzyme-based catalysis, focusing on enzyme classification, engineering strategies, and industrial applications. The six major enzyme classes—hydrolases, oxidoreductases, transferases, lyases, isomerases, and ligases—are discussed in the context of their catalytic roles across sectors such as pharmaceuticals, food processing, textiles, biofuels, and environmental remediation. Recent developments in protein engineering, including directed evolution, rational design, and computational modeling, have significantly enhanced enzyme performance, stability, and substrate specificity. Emerging tools such as machine learning and synthetic biology are accelerating the discovery and optimization of novel enzymes. Progress in enzyme immobilization techniques and reactor design has further improved process scalability, reusability, and operational robustness. Enzyme sourcing has expanded from traditional microbial and plant origins to extremophiles, metagenomic libraries, and recombinant systems. These advances support the integration of enzymes into green chemistry and circular economy frameworks. Despite challenges such as enzyme deactivation and cost barriers, innovative solutions continue to emerge. Enzymes are increasingly enabling cleaner, safer, and more efficient production pathways across industries, supporting the global shift toward sustainable and circular manufacturing. Full article

Reductive amination of cyclohexanone with NH₃ and H₂ over Rh and Rh-Ni catalysts on SiO₂ has been studied. Research has focused on the catalytic efficiency of monometallic and bimetallic catalysts in the production of cyclohexylamine, a key intermediate in the synthesis of numerous fine chemicals. Through the wet impregnation method, Rh and Rh-Ni catalysts with varying nickel loadings (1, 2, 5, and 10 wt.%) were synthesized and characterized using techniques such as N₂ physisorption, TEM, HAADF-STEM, XRD, XPS, H₂-TPR, and NH₃-TPD. The catalytic reactions were conducted under controlled conditions using a glass-coated reactor, using ammonia as nitrogen source. Rh-Ni bimetallic catalysts exhibited the highest conversion rates on reductive amination, attributed to enhanced dispersion and advantageous surface properties. High metal dispersion and small particle sizes were confirmed by TEM, HAADF-STEM, and XRD. XPS analysis confirmed the reduced state of Rh and mainly oxidized state of Ni, while H₂-TPR and NH₃-TPD results indicated improved reducibility and acidity, respectively, which are critical for catalytic activity. Monometallic Rh/SiO₂ catalyst showed 83.4% of conversion after 300 min and selectivity of 99.1% toward the desired product cyclohexylamine. The addition of nickel, a cheap and easily available metal, increases the activity without compromising selectivity. At 300 min of the reaction, the 2 wt.% NiRh/SiO₂ catalyst exhibited the highest conversion, yield, and selectivity for the desired product cyclohexylamine, 99.8%, 96.4%, and 96.6% respectively. Additionally, this catalyst is recyclable after the fourth cycle, showing 99.5% selectivity and 74.0% yield for cyclohexylamine at 75.7% conversion. Recycling tests confirmed the stability of bimetallic catalysts, maintaining performance over multiple cycles without significant deactivation. Full article

Bats are a taxa of high conservation concern and are facing numerous threats including widespread mortality due to White-Nose Syndrome (WNS) in North America. With this decline comes increasing difficulty in monitoring imperiled bat species due to lower detection probabilities of both mist-netting and acoustic surveys. Lure technology shows promise to increase detection while decreasing sampling effort; however, to date research has primarily focused on increasing physical captures during mist-net surveys using sound lures. Because much bat monitoring is now performed using acoustic detection, there is a similar need to increase detection probabilities during acoustic surveys. Ultraviolet (UV) lights anecdotally have been shown to attract insects and thereby attract foraging bats for observational studies and to experimentally provide a food source for WNS-impacted bats before and after hibernation. Therefore, we constructed a field-portable and programmable UV lure device to determine the value of lures for increasing acoustic detection of bats. We tested if the lure device increased both the echolocation passes and feeding activity (feeding buzzes) across a transect of bat detectors. There was an increase in feeding activity around the UV light, with a nuanced, species-specific and positionally dependent effect on echolocation passes received. The UV light lure increased echolocation passes for the eastern red bat (Lasiurus borealis), little brown bat (Myotis lucifugus), and evening bat (Nycticeius humeralis), but decreased passes of the North American hoary bat (Lasiurus cinereus). The northern long-eared bat (Myotis septentrionalis) showed a negative response within the illuminated area but increased echolocation activity outside the illuminated area during lure treatment and activity was elevated at all positions after the lure was deactivated. Our study demonstrates some potential utility of UV lures in increasing the feeding activity and acoustic detection of bats. Additional research and development of UV lure technology may be beneficial, including alternating on and off periods to improve detection of light-averse species, and improving echolocation call quality along with the increase in received passes. Full article

We present a dual-mode optical sensing strategy for selective and sensitive detection of sulfide ions (S²⁻), employing copper-anchored nitrogen-doped graphene quantum dots (Cu@N-GQDs) as bifunctional nanozymes. The Cu@N-GQDs were synthesized via citric acid pyrolysis in the presence of ammonium hydroxide (serving as both nitrogen source and reductant) and copper chloride, leading to uniform incorporation of copper oxide species onto the N-GQD surface. The resulting nanohybrids exhibit two synergistic functionalities: intrinsic fluorescence comparable to pristine N-GQDs, and significantly enhanced peroxidase-like catalytic activity attributed to the anchored copper species. Upon interaction with sulfide ions, the system undergoes a dual-optical response: (i) fluorescence quenching via Cu-S complexation, and (ii) inhibition of peroxidase-like activity due to the deactivation of Cu catalytic centers via the interaction with S²⁻. This dual-signal strategy enables sensitive quantification of S²⁻, achieving detection limits of 0.5 µM (fluorescence) and 3.5 µM (colorimetry). The sensor demonstrates excellent selectivity over competing substances and high reliability and precision in real tap water samples. These findings highlight the potential of Cu@N-GQDs as robust, bifunctional, and field-deployable nanozyme probes for environmental and biomedical sulfide ion monitoring. Full article

Biodiesel, a renewable and environmentally friendly alternative to fossil fuels, has attracted significant attention due to its potential to reduce greenhouse gas emissions. However, high production costs and complex processing remain challenges. Heterogeneous catalysts have shown promise in overcoming these barriers by offering benefits, such as easy separation, reusability, low-cost raw materials, and the ability to reduce reaction times and energy consumption. This review evaluates key classes of heterogeneous catalysts, such as metal oxides, ion exchange resins, and zeolites, and their performance in transesterification and esterification processes. It highlights the importance of catalyst preparation methods, textural properties, including surface area, pore volume, and pore size, activation techniques, and critical operational parameters, like the methanol-to-oil ratio, temperature, time, catalyst loading, and reusability. The analysis reveals that catalysts supported on high surface area materials often achieve higher biodiesel yields, while metal oxides derived from natural sources provide cost-effective and sustainable options. Challenges, such as catalyst deactivation, sensitivity to feedstock composition, and variability in performance, are discussed. Overall, the findings underscore the potential of heterogeneous catalysts to enhance biodiesel production efficiency, although further optimization and standardized evaluation protocols are necessary for their broader industrial application. Full article