Search Results (855)

The physicochemical characteristics of hydrochars produced from tobacco stems through hydrothermal carbonization (HTC) at different temperatures were investigated, along with the variation in contents of nicotine, niacin, and chlorogenic acid in both the hydrochars and the liquid phase. The results indicated that dehydration was the predominant reaction during HTC of wet tobacco stems (WTS), leading to a decrease in the H/C and O/C atomic ratios of the hydrochars. As temperature increased, polycondensation and aromatization reactions became more pronounced, which corresponded with a reduction in the intensity of functional group vibrations such as C–N and N–O in FT-IR spectra. XPS analysis revealed a gradual increase in C=O content, whereas the proportions of C–OH and C–O bonds declined from 51.74% and 35.13% to 36.95% and 20.84%, respectively. Furthermore, the content of pyridine-N rose from 31.08% to 41.30%, while pyrrole-N and quaternary-N contents decreased to varying degrees. Both nicotine and niacin levels in the hydrochars and carbonization liquids exhibited an initial increase followed by a decline, whereas chlorogenic acid content consistently decreased. The underlying mechanisms for the observed changes in nicotine, niacin, and chlorogenic acid contents during HTC are discussed in detail. Full article

Optimizing nitrogen management is essential for maintaining high spring maize yield while mitigating nitrous oxide (N₂O) emissions in irrigated areas. However, the interactive effects of total nitrogen application rate and starter nitrogen proportion on yield and N₂O emissions remain insufficiently quantified. Reliable assessment of these interactions requires well-calibrated DeNitrification–DeComposition (DNDC) simulations, yet existing calibration studies often emphasize crop parameters while neglecting soil parameters critical for soil hydrothermal dynamics and N₂O production. In this study, field data from shallow-buried drip-irrigated spring maize in Tongliao during 2024–2025 were used to conduct Extended Fourier Amplitude Sensitivity Test (EFAST) sensitivity analysis on 12 crop and 13 soil parameters of the DNDC model. Sensitive parameters were calibrated using the differential evolution algorithm, and 64 nitrogen management scenarios were simulated by combining eight total nitrogen application rates (100, 150, 200, 250, 300, 350, 400, and 450 kg N ha⁻¹) with eight starter nitrogen proportions (0%, 15%, 25%, 30%, 35%, 40%, 45%, and 50% of the total nitrogen rate). The results showed that DNDC outputs were jointly controlled by crop and soil parameters, among which maximum yield, leaf carbon-to-nitrogen ratio, stem fraction, grain carbon-to-nitrogen ratio, thermal degree days for maturity, grain fraction, soil organic carbon (SOC) decrease rate below topsoil, soil clay content, soil porosity, wilting point and depth of top soil with uniform SOC content were dominant. Compared with the conventional crop-parameter calibration, the sensitivity-screened parameter set improved the simulation of both cumulative N₂O emissions and yield. Across the 64 scenarios, cumulative N₂O emissions ranged from 0.42 to 4.87 kg [N]/ha, while simulated maize yield ranged from 1597 to 6347 kg [C]/ha. N₂O emissions increased with total nitrogen rate, whereas yield increased initially and then reached a plateau. Increasing the starter nitrogen proportion did not substantially enhance yield but increased N₂O emission risk under high nitrogen rates. Overall, the scenario with 300 kg/ha and no nitrogen applied at sowing achieved a relatively high yield of 5519 kg [C]/ha while maintaining a low cumulative N₂O emission of 0.98 kg [N]/ha and was therefore identified as the preferred trade-off strategy under shallow-buried drip irrigation. This study provides an EFAST–DNDC framework for optimizing nitrogen management to sustain spring maize yield while reducing N₂O emissions in the West Liaohe Plain. Full article

Visual discomfort or visual stress is an uncomfortable subjective experience that occurs in response to specific visual stimuli. It affects a large proportion of the population to various degrees, disproportionately impacting those with heightened sensory sensitivities, particularly neurodivergent individuals. We argue that this might stem from a mismatch between the statistical properties of visual stimuli in human-made environments and those in natural environments that the visual system can process efficiently. We discuss the inefficiency with which images with certain spatial, chromatic and temporal characteristics are processed by the visual system and propose a cerebral mechanism to account for the discomfort they induce. The mechanism offers a potential explanation for the large individual differences in susceptibility to discomfort. We highlight two avenues for intervention: (1) environmental modifications aimed at reducing the prevalence of visually stressing stimuli in urban settings, and (2) individual-level strategies, such as personalised optical treatments. Addressing these challenges requires an interdisciplinary effort bridging neuroscience, vision science, interior and urban design and typography to create visually accessible and inclusive environments. Full article

Socio-technical congruence (STC) theory posits that software development effectiveness depends on the degree to which developer coordination aligns with technical requirements. However, much existing research treats congruence as a static project attribute, overlooking the dynamic coordination needs that arise during periods of intensive development. This study addresses this gap by examining development bursts, brief episodes of significant technical change and collaboration that alter coordination demands. Using fixed-effects regression models, the analysis examines 45,981 development bursts from 6401 open-source software projects. The findings show that higher burst intensity is positively associated with both congruence and delivery throughput, suggesting that effective collaboration often centers on shared integration challenges. Conversely, higher coordination complexity is associated with lower congruence and reduced delivery reliability, indicating that the main risks associated with bursts stem from structural rather than purely volumetric factors. Team experience also mitigates the negative effects of complexity on congruence, highlighting the importance of accumulated coordination capability. However, after accounting for demand-side factors, the relationship between congruence and delivery reliability becomes negative, indicating that congruence observed during bursts reflects not only alignment quality but also coordination burden. These findings extend STC theory by reconceptualizing congruence as a dynamic state and emphasizing the need to understand its evolution in high-frequency coordination contexts. Full article

Gelatin functionalized with methacrylate (GelMA), norbornene (GelNB), and phenol (GelPH) has been studied as a precursor for crosslinkable biomaterials in tissue engineering. Cytocompatibility is usually assessed post-hydrogel formation, but cells briefly encounter soluble precursors during preparation and residual functional groups that may remain post-gelation. However, the biological effects of these uncrosslinked derivatives remain poorly understood. This study systematically investigated the impact of functional group chemistry on cellular responses under uncrosslinking conditions. Four cell lines, including fibroblasts (BALB/3T3), cervical cancer cells (HeLa), mesenchymal stem cells (UE7T-13), and neuronal cells (PC-12), were exposed to soluble GelMA, GelNB, and GelPH at matched polymer concentrations and degrees of functionalization (~50%). The results showed no overt cytotoxicity. The detectable differences were subtle and strongly cell type-dependent. HeLa and PC-12 cells showed no clear differences from untreated controls in most parameters. BALB/3T3 fibroblasts showed mainly GelMA-associated differences in mitochondrial activity, proliferation, and morphology. In the UE7T-13 cells, GelMA-treated cells showed the largest deviations from controls across the readouts examined, including mitochondrial activity, cell area, phenotype-related gene expression, and some osteogenic markers, while GelPH was intermediate and GelNB was comparable to controls. These findings underscore the importance of considering residual precursor effects in gelatin-based biomaterial design. Full article

In this study, nine strains of plant growth-promoting rhizobacteria (PGPR) with multiple growth-promoting functions were isolated and screened from the rhizosphere of plants (Phragmites communis, Triglochin maritimum, and Alhagi maurorum) in the arid and barren regions of Western China. These strains belong to five genera: Klebsiella, Bacillus, Serratia, Pseudomonas, and Flavobacterium. The growth-promoting characteristics of these nine strains (PAP4, PA35, AC12, ACP1, AC25, TP7, TP8, TP12, and TP14) were analyzed. Furthermore, the growth-promoting potential of these PGPR strains was comprehensively evaluated through plate and pot experiments using Arabidopsis thaliana and alfalfa. The results indicate that most strains possess the ability to fix nitrogen and secrete zeatin and extracellular polysaccharides (EPS). Some strains exhibited significant traits such as phosphate solubilization, siderophore secretion, and the production of 1-aminocyclopropane-1-carboxylate (ACC) deaminase and indole-3-acetic acid (IAA). All strains showed high salt tolerance (0–8% NaCl) and were induced to secrete more EPS under salt stress. Plate experiments demonstrated that volatile organic compounds (VOCs) from the nine strains significantly promoted the root development of Arabidopsis thaliana and optimized its root architecture. Pot experiments revealed that inoculation with single strains influenced the growth of alfalfa to varying degrees; among them, strain TP14 showed the best performance, increasing plant height and shoot dry weight by 44.7% and 51.2%, respectively. Regarding microbial consortia, the combinations BD (PAP4 + TP14), ABC (PA35 + PAP4 + AC25), and ABCD (PA35 + PAP4 + AC25 + TP14) significantly improved the biomass, plant height, and stem diameter of alfalfa. The superior strains and their combinations identified in this study effectively promote plant growth. These high-performing PGPR strains provide valuable microbial resources for the development of bio-fertilizers tailored for saline–alkali and barren regions in Western China. Full article

Stress shielding (SS) after cementless total hip arthroplasty arises from the stiffness mismatch between conventional Ti-6Al-4V femoral stems (110 GPa) and cortical bone (10–30 GPa). The β-type Ti-33.6Nb-4Sn (TNS) alloy femoral stem addresses this limitation through a continuous Young’s modulus gradient (~70 GPa proximally to ~40 GPa distally) achieved by localized heat treatment of a single homogeneous alloy. This review synthesizes a translational research program encompassing material characterization, finite element modeling (FEM), preclinical animal studies, and prospective clinical follow-up of up to seven years. FEM demonstrated favorable proximal micromotion well below the osseointegration threshold, with physiological proximal stress concentration concordant with clinical outcomes. At seven years, SS grade distribution was significantly lower in the TNS group than in Ti-6Al-4V controls, with SS frequency reduced in Gruen Zones 2, 3, and 6, and no stem-related failures; however, third-degree SS was still observed in 11 of 34 evaluable cases (32%), indicating that modulus-gradient optimization alone is insufficient to fully prevent SS. TNS alloy is currently the only β-type titanium alloy clinically applied in joint prostheses. Remaining challenges include stem geometry optimization, additive manufacturing-based porous structures, and dual-energy X-ray absorptiometry-based bone density quantification. Future directions encompass long-term follow-up, cyclic fatigue FEM simulations, and expansion to fracture fixation devices and dental implants. Full article

In order to address corrosion and pollution problems of liquid acids and limitations of traditional solid acids, sulfated MOF-808-SO₄ catalysts were developed by creating unsaturated sites in MOF-808 for sulfate grafting with ligand defect engineering. Characterization verified framework integrity, successful sulfate coordination, and maintenance of high surface areas and tunable porosity. Temperature-programmed desorption of ammonia (NH₃-TPD) establishes a clear consistent trend between defect density and the concentration as well as the strength of acid sites, indicating that a higher degree of ligand deficiency promotes the formation of more abundant and stronger acid centers. For esterification of acetic acid with n-butanol, the catalyst prepared by replacing 40 mol% of BTC with BDC achieved ≥99% conversion of acetic acid under mild conditions of 2.0 wt% catalyst loading and 1:2 alcohol/acid molar ratio at 120 °C for 6 h, outperforming conventional solid acids. This performance stems from high-density strong Brønsted acid sites strongly coordinated at defects and an open pore structure facilitating diffusion. The catalyst was easily recovered by ethanol washing and maintained stable activity over five cycles without loss of catalytic capability. This work suggests defect engineering as an effective strategy for tuning acidity and catalytic performance in MOF-based solid acids for green esterification. Full article

The gut microbiota produces chemically diverse metabolites whose levels fluctuate depending on the time of day, driven by bidirectional coupling between host intestinal circadian clocks and intrinsic microbial oscillators. Although short-chain fatty acids have received the most attention as microbial circadian effectors, a broad class of metabolites, including secondary bile acids, indole derivatives, and branched-chain fatty acids, engage distinct epithelial receptors and transcriptional programs through mechanisms that are, to varying degrees, subject to circadian regulation. However, the mechanisms by which these metabolite classes collectively regulate barrier integrity, mucosal immune tone, and stem cell-driven renewal, as well as the consequences of their rhythmicity loss under circadian misalignment, have not been systematically reviewed. This review constructs a mechanistic framework linking microbial metabolite rhythmicity to the circadian regulation of intestinal epithelial homeostasis and evaluates dietary and probiotic interventions that modulate this axis as chronobiotic strategies. Convergent mechanisms, unresolved questions, and translational opportunities are identified across in vitro, preclinical, and clinical evidence. Full article

This article focuses on the research and development of innovative polymer-concrete composites for the manufacture of precision machine tool frames and critical mechanical engineering components. The relevance of this work stems from the need to replace traditional cast iron and cement concrete with materials with superior damping properties and thermal stability. The polymer matrix used in this study was ED-20 epoxy-diane resin, modified with (FAM) furan resin and cured with polyethylenepolyamine (PEPA), which together ensured minimal linear shrinkage (less than 0.5–1%) during polymerization. The focus was on the effect of multimodal filler distribution, including quartz sand, gabbro, and basalt, as well as reinforcing additives such as silicon carbide and fiberglass, on the final performance characteristics of the material. Experimental studies determined the key physical and mechanical parameters of the obtained samples. The results showed that the optimized composition (Smp_001) exhibited compressive strength up to 92.3 MPa, significantly exceeding that of standard high-strength concrete. It was established that the use of silicon carbide and glass fiber promotes the formation of a dense heterogeneous microstructure characterized by extremely low porosity (1.2–2.5%) and record-low water absorption (less than 0.05%). These characteristics guarantee high dimensional stability of the frames during prolonged contact with process fluids and cutting fluids. The scanning electron microscopy (SEM) and (EDS) energy dispersive X-ray spectroscopy methods confirmed the dense packing and high degree of interaction of the polymer matrix with the crystalline phases of the filler. This condition of the interfacial boundaries guarantees stable stress transfer throughout the entire volume of the material, which minimizes the risk of local damage during operation. The study confirmed that the developed material has vibration damping properties 6–10 times more effective than gray cast iron, a critical factor in improving machining accuracy on modern metal-cutting machines. The scientific novelty of the study lies in its substantiation of the synergistic effect of the combined use of basalt fillers and silicon carbide to achieve the precision properties of a structural material. Its practical significance is confirmed by the possibility of producing large-scale parts by casting without the need for complex finishing, opening up new prospects for modernizing the machine tool industry. Full article

As urban–rural integration deepens, the growth of suburban integrated villages, as the key link between urban–rural factor flow and coordinated development, is affected by the asymmetric reciprocal symbiosis between urban and rural areas. Utilizing urban–rural integration and sustainable development theories, this study selected twenty-four suburban integrated villages in the Daoli District of Harbin as its research object. It concentrates on the township–village micro-symbiotic unit, formulates a two-dimensional evaluation framework of “village endogenous + township linkage,” and utilizes quantitative methodologies, including the coupling coordination degree model, the obstacle degree model, and sensitivity analysis, to identify the factors hindering the expansion of these villages and propose targeted strategies according to villages’ coordination levels. The results show that 79% of samples exhibit imbalanced coordination; although spatial constraints are the primary hindrances to village systemic coordination, balanced development of spatial, economic, social and ecological subsystems remains essential; the developmental constraints of the samples stem from weak village developmental foundations and insufficient township–village radiation linkages. This study enhances the township–village symbiosis micro-research framework and functions as a reference for the classification planning of suburban integrated villages and the sustainable amalgamation of urban and rural development. Full article

Plant extracts and microbiological supernatants were subjected to qualitative and compositional analyses to characterize their bioactive profiles and assess their potential agricultural applications. The garlic (Allium sativum) extract was rich in allicin and selected free amino acids, contained betulin as the dominant triterpene, and displayed a favorable elemental profile with high levels of potassium, phosphorus, sulfur, calcium, and magnesium, with no detectable heavy metals. Detectable amounts of B-group vitamins and vitamin E isoforms were also identified. Qualitative phytochemical screening confirmed the presence of saponins and flavonoids in the garlic extract. The Jerusalem artichoke (Helianthus tuberosus) extract exhibited a significantly higher total phenolic content compared to the garlic extract, with qualitative analysis confirming the presence of saponins, tannins, and flavonoids, suggesting a broader spectrum of bioactive compounds. The two bacterial supernatants were characterized by HPLC analysis and differed in their metabolic profiles: the Enterobacter sp. fermentation broth contained glycerol, 2,3-butanediol, and acetic acid, while the Paenibacillus sp. supernatant additionally contained lactic acid, ethanol, and succinic acid, reflecting distinct fermentation pathways. The in vitro and greenhouse studies aimed to evaluate biological preparations for controlling wheat diseases caused by fungi of the Fusarium genus as well as diseases affecting the stem base. Plant extracts (garlic—Allium sativum, Jerusalem artichoke—Helianthus tuberosus) and supernatants (fermentation broths) obtained with the Paenibacillus and Enterobacter bacteria were tested at three concentrations. In laboratory experiments, the degree of inhibition of the growth of the mycelium of the tested fungal species was determined, while in greenhouse studies, the effectiveness in limiting the development of stem base diseases and the impact of the applied biopreparations on plant growth were evaluated. Among the plant extracts, H. tuberosus demonstrated superior antifungal activity, achieving up to 100% inhibition of R. cerealis mycelial growth at 10% concentration and reducing disease severity by 34.3% compared to the untreated control under greenhouse conditions. Paenibacillus sp. supernatant demonstrated strong in vitro antifungal activity. The results indicate that H. tuberosus extract represents a promising candidate for further field evaluation as a component of sustainable wheat protection programs. Full article

Students entering engineering programs often exhibit insufficient mathematics knowledge and considerable variability in prior training, which can create learning gaps and challenges for higher education integration. This study aims to characterize students’ mathematics proficiency at the Coimbra Institute of Engineering and to develop strategies to address these gaps. A diagnostic test was designed based on the Portuguese primary and secondary education syllabus and the guidelines of the European Society for Engineering Education. Data were collected from students enrolling in engineering degrees between the 2013/14 and 2021/22 academic years. Based on the diagnostic results, a targeted intervention was implemented to motivate students and enhance their learning in mathematics. This intervention includes complementary teaching methodologies applied to Differential and Integral Calculus, a mandatory first-year course across all engineering programs. The analysis demonstrates that the combined approach of diagnostic assessment and targeted support improves student engagement and addresses disparities in prior knowledge. This study contributes to the development of evidence-based strategies that support equitable learning opportunities in engineering education and offers a model for integrating diagnostic assessment with active learning practices in foundational STEM courses. Full article

This study examines gender disparities in three STEM departments at the University of the Peloponnese over a twenty-year period. Based on secondary administrative data from 1245 graduates, this study investigates: (i) whether women are underrepresented among STEM graduates; (ii) whether gender influences degree performance; and (iii) whether gender predicts the duration of study. Descriptive statistics, cross-tabulations, chi-square tests, and two-way ANOVA were used to analyze the data. The results reveal a persistent underrepresentation of women in all three departments, with female graduates accounting for only 13.6–26% of the departmental totals. However, no statistically significant differences were found between male and female graduates in terms of degree grades or time to degree completion. The literature review further highlights the personal, social, cultural, and institutional factors that contribute to women’s underrepresentation in STEM internationally. The findings emphasize the need for early interventions, stereotype-free learning environments, targeted outreach programs, and institutional support mechanisms. Further recommendations include expanding STEM education from early childhood, enhancing teacher preparedness for gender-inclusive instruction, promoting female role models in STEM, and implementing targeted university-level initiatives. Finally, this study offers empirical evidence relevant to policymakers and higher education institutions seeking to close the gender gap in STEM fields. Full article

Objective: Effectively eliminating xenoimmunogenicity and achieving recellularization in cardiac xenografts remains a critical challenge in developing an ideal implantable xenograft. We have previously demonstrated that the removal of major antigens, including Galα1-3Gal (α-Gal) epitope and non-human sialic acid N-glycolylneuraminic acid (Neu5Gc), using α-galactosidase and peptide N-glycosidase F (PNGase-F), enables a synergistic effect with decellularization, significantly reducing the expression of carbohydrate-binding lectins without altering the biomechanical properties of the graft. The aim of this study was to establish an effective method for in vitro recellularization by seeding human mesenchymal stem cells (MSCs) on decellularized cardiac xenografts that had undergone optimal xenoantigen removal using α-galactosidase and PNGase-F. Additionally, this study aimed to evaluate the potential for in vivo recellularization. Methods: Decellularized porcine pericardium scaffolds treated with both enzymes were further modified by forming a fibrin mesh on their surface and within their structure, followed by the attachment of heparin and human vascular endothelial growth factor to the mesh. Subsequently, the scaffolds were seeded with human adipose tissue-derived stem cells for 8 weeks. In vitro recellularization, differentiation, and extracellular matrix remodeling of decellularized and enzyme-treated xenografts were assessed using vimentin, calponin, fibronectin, CD31, VWF, and phalloidin staining. To evaluate the potential for in vivo recellularization, decellularized glutaraldehyde-crosslinked xenografts with anticalcification treatments were seeded with rat bone marrow MSCs and implanted into rats subcutaneously to evaluate cell infiltration and calcification via histology, von Kossa staining, and micro-computed tomography. Results: In decellularized xenografts treated with both enzymes, stronger signals were detected and mesenchymal cell infiltration into the tissue was significantly faster, leading to accelerated recellularization. This recellularization process was more pronounced as time went on, with greater cell infiltration and evidence of cell differentiation. An in vivo study showed that decellularization and anticalcification treatments revealed stronger vimentin staining in histological analysis. The recellularization for our biocompatible scaffolds exhibited a lower degree of calcification compared to the non-recellularized tissue. Conclusions: We successfully developed major xenoantigen-free scaffolds by demonstrating the safety and synergistic effect of α-galactosidase and PNGase-F treatments and proved, for the first time, the effectiveness of recellularization using a human MSC monoculture on xenoantigen-free scaffolds. Furthermore, there was potential for in vivo recellularization of our biocompatible scaffolds seeded with MSCs. Full article