Search Results (1,201)

Carboxymethyl hydroxypropyl cellulose (CMHPC) combines the advantages of both carboxymethyl and hydroxypropyl substitutions, exhibiting superior solubility, viscosity characteristics, and enhanced salt tolerance compared to carboxymethyl cellulose (CMC). This study presents an optimized synthesis route for CMHPC through homogeneous hydroxypropylation of CMC under alkaline conditions. The effects of key reaction parameters, including propylene oxide amount and reaction time, on the structure and resulting properties were systematically investigated. The resulting CMHPC were comprehensively characterized using FTIR, solid state ¹³C NMR, and scanning electron microscopy (SEM), etc., confirming the successful hydroxypropyl group incorporation and morphological changes. In our findings, the suitable concentrations for NaOH and CMC were 5% and 4%, respectively, which could balance the yield and solution fluidity. CMHPC exhibited a much faster dissolution speed (3–5 min) than that of CMC (>30 min), indicating markedly enhanced hydrophilicity and solubility. Moreover, CMHPC also exhibited improved salt and acidity tolerance due to the steric hindrance of hydroxypropyl groups. CMHPC was also used to modify recycled coarse aggregate (RCA), and the results indicated that CMHPC could enhance the surface compactness and structural integrity of RCA. Moreover, CMHPC effectively improved the water resistance of RCA by constructing a physical barrier and optimizing the pore structure of the aggregate. This research provides valuable insights into the fabrication of modified cellulose ethers in homogeneous systems and offers a practical pathway for producing high-value cellulose derivatives with tailored properties, particularly for potential construction applications. Full article

The combination of gold nanoparticles (AuNPs) with hydrogels has drawn significant interest in the design of smart materials as advanced platforms for biomedical applications. These systems endow light-responsiveness enabled by the AuNPs localized surface plasmon resonance (LSPR) phenomenon. In this study, we propose a nanocomposite hydrogel in which gold nanorods (AuNRs) are included in an agarose–carbomer–hyaluronic acid (AC-HA)-based hydrogel matrix to study the correlation between light irradiation, local temperature increase, and drug release for potential light-assisted drug delivery applications. The gel is obtained through a facile microwave-assisted polycondensation reaction, and its properties are investigated as a function of both the hyaluronic acid molecular weight and ratio. Afterwards, AuNRs are incorporated in the AC-HA formulation, before the sol–gel transition, to impart light-responsiveness and optical properties to the otherwise inert polymeric matrix. Particular attention is given to the evaluation of AuNRs/AC-HA light-induced heat generation and drug delivery performances under near-infrared (NIR) laser irradiation in vitro. Spatiotemporal thermal profiles and high-resolution thermal maps are registered using fiber Bragg grating (FBG) sensor arrays, enabling accurate probing of maximum internal temperature variations within the composite matrix. Lastly, using a high-steric-hindrance protein (BSA) as a drug mimetic, we demonstrate that moderate localized heating under short-time repeated NIR exposure enhances the release from the nanocomposite hydrogel. Full article

Hydrophilic modification of polymeric membranes by employing TiO₂ nanoparticles has attracted much attention in enhancing antifouling performance. Micelles of PVPylated-TiO₂ nanoparticles were designed to alleviate the agglomeration of TiO₂ nanoparticles via steric hindrance and electrostatic stabilization effect. Herein, Poly(vinyl pyrrolidone) (PVP) was used as a surfactant to mitigate the thorny agglomeration of nanoparticles in the casting solution and simultaneously as a pore-forming additive during the membrane preparation process. The lowest backscattering (BS) peak and turbiscan stability index (TSI) of the composite casting solution indicated the effective dispersion and stabilization under the steric interaction of 4 wt.% PVP. Properties such as the fully developed finger-like structure of cross-sectional morphologies, water permeability, negative Zeta potential, and hydrophilicity were enhanced evidently by the optimal modification of PVPylated-TiO₂ materials. High interaction energy indicated by classic extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory as well as the high relative flux during the filtration of various model foulants demonstrated the effective antifouling modification. The results of critical flux and fouling rate in 30 min also verified the enhancement of the antifouling performance of PVDF/PVPylated-TiO₂ composite membrane. This work provides a feasible strategy to construct composite membranes with high antifouling performance for wastewater treatment. Full article

This work explores a novel and efficient synthetic approach to a new class of boron cluster derivatives via the nucleophilic addition of stabilized phosphorus ylides, Ph₃P=CHR² (R² = COOEt, CN), to a series of nitrilium salts of the closo-decaborate anion, [2-B₁₀H₉NCR¹]⁻ (R¹ = Me, Et, ⁿPr, ⁱPr, Ph). The reaction proceeds regio- and stereospecifically, affording a diverse range of iminoacyl phosphorane derivatives, [2-B₁₀H₉NH=C(R¹)C(PPh₃)R²]⁻, in high isolated yields (up to 95%). The obtained compounds (10 examples) were isolated as tetrabutylammonium or tetraphenylphosphonium salts and thoroughly characterized by multinuclear NMR (¹¹B, ¹H, ¹³C, ³¹P), high-resolution mass spectrometry, and single-crystal X-ray diffraction. The reaction feasibility was found to be strongly influenced by the steric hindrance of the R¹ group. Furthermore, the practical utility of these novel hybrids was demonstrated by employing the [2-B₁₀H₉NH=C(CH₃)C(COOC₂H₅)=PPh₃]⁻ anion as a highly effective membrane-active component in ion-selective electrodes. The developed tetraphenylphosphonium (TPP⁺) sensor exhibited a near-Nernstian response, a low detection limit of 3 × 10⁻⁸ M, and excellent selectivity over a range of common inorganic and organic cations, showcasing the potential of closo-borate-based ionophores in analytical chemistry. Full article

The advancement of reactive powder concrete (RPC) technology primarily focuses on modifications to its conventional composition. This involves substituting Portland cement (CEM I) with alternative cement types and finely ground mineral additives, as well as replacing quartz aggregate with another type of aggregate. The paper presents an analysis of the properties of RPC obtaining using waste sand and powder generated during the processing of aggregates from migmatite-amphibolite rock. Research into RPC mixtures revealed that in one scenario, replacing quartz powder with waste powder resulted in a significant increase in flexural strength by 23%, although there was a slight decrease in compressive strength by 7%. However, when both quartz powder and quartz sand were substituted with waste powder and waste sand, there was a 14% reduction in compressive strength, while flexural strength increased, albeit to a much lesser extent. The analysis of mineral composition and microstructure of migmatite-amphibolite waste powder and sand revealed that the primary factor contributing to the increase in flexural strength is the presence of biotite in a flake shape form. The microscopy images clearly show hydration products gathering mainly at the rims of biotite flakes and not on their smooth surfaces. The reason could be better availability for hydration products attachment and lower steric hindrance to the rims of single biotite flakes instead of its large packets. Conversely, the reduction in RPC compressive strength, resulting from the substitution of quartz sand with migmatite-amphibolite waste sand, can be attributed mainly to the lower compressive strength of the waste sand itself. Test results indicate that the waste powder generated during the production of migmatite-amphibolite aggregates, which contains fine flakes of biotite, can be utilised as a mineral admixture in concrete, thereby enhancing its flexural strength. Full article

The rapid advancement of Artificial Intelligence (AI) has profoundly transformed organizational systems, reshaping how employees interact with technology and adapt to changing work environments. However, the systemic mechanisms through which AI-induced technostress influences employee career growth remain insufficiently understood. Grounded in a socio-technical systems perspective, this study conceptualizes organizations as adaptive systems where technological, organizational, and human subsystems dynamically interact. We propose a dual-path framework that distinguishes between challenge-related technostressors (a resource-gain process) and hindrance-related technostressors (a resource-loss process), elucidating how AI-related pressures can simultaneously foster and hinder career development. Furthermore, employee resilience and organizational AI support are incorporated as systemic moderators that modulate the intensity of these effects within the human–AI–organization system. Using two-stage survey data from 326 matched pairs of employees and supervisors, results largely support the proposed model, with some pathways showing marginal significance. The findings reveal that AI challenge-related technostressors stimulate proactive adaptation and skill development, whereas hindrance-related technostressors generate anxiety and insecurity, thereby impeding growth. This research extends systems theory by demonstrating how technostressors function as an emergent property of human–technology interactions and provides actionable insights for designing more adaptive and resilient socio-technical work systems. Full article

Background/Objectives: Docetaxel is a widely used chemotherapeutic agent for several malignancies and is an established treatment for castration-resistant prostate cancer. However, its poor aqueous solubility, systemic toxicity, and the emergence of drug resistance limit its clinical benefit. Zein, a prolamin, forms micelles that enhance the solubility and delivery of hydrophobic drugs. As PEG length and ligand presentation govern micelle behavior, we investigated transferrin-functionalized PEGylated zein micelles as docetaxel nanocarriers and examined how PEG chain length (5 K vs. 10 K) and transferrin-mediated targeting affect delivery to prostate cancer cells. Methods: Docetaxel-loaded zein micelles bearing 5 K or 10 K PEG chains were prepared and conjugated to transferrin. Formulations were characterized for size, charge, morphology, critical micelle concentration, colloidal stability, drug loading and transferrin density. Cellular uptake and mechanisms were assessed in PC-3-Luc, DU145 and LNCaP cells by confocal microscopy, flow cytometry and pharmacological inhibition. Anti-proliferative activity was determined by MTT assays. Results: Both PEG5K and PEG10K micelles formed micellar dispersions with low polydispersity and high encapsulation efficiency. PEG5K micelles achieved higher transferrin conjugation and drug loading. Transferrin-functionalized PEG5K micelles showed enhanced uptake in DU145 and LNCaP cells but lower internalization in PC-3-Luc cells. Inhibitor studies indicated receptor-dependent uptake via clathrin- and caveolae-mediated endocytosis. Free docetaxel remained the most potent. However, among nanocarriers, transferrin-targeted PEG5K micelles showed the greatest anti-proliferative efficacy relative to their non-targeted counterparts, whereas transferrin-targeted PEG10K micelles were less potent than the non-targeted PEG10K micelles across all three cell lines. Conclusions: PEG chain length and ligand presentation are key determinants of uptake and cytotoxicity of docetaxel-loaded zein micelles. Shorter PEG chains favor effective transferrin display and receptor engagement, whereas longer PEG likely induces steric hindrance and reduces targeting, supporting transferrin-conjugated PEG5K zein micelles (the lead formulation in this study) as a targeted delivery platform that improves performance relative to matched non-targeted micelles in vitro, while free docetaxel remains more potent in 2D monolayer assays. Full article

Background: Adoptive cell therapy using genetically engineered recombinant T cell receptors (rTCRs) expressed in T cells (TCR-T cell therapy) provides precision targeting of cancer cells expressing tumor-associated or tumor-specific antigens recognized by the rTCRs. Standardized analytical tools are lacking to easily quantify receptor expression. Methods: To overcome this hindrance, a universal tagging system (UniTope & TraCR) was designed consisting of a minimal peptide epitope (UniTope) inserted into the constant region of the rTCR α or β chain and a high-affinity monoclonal antibody (TraCR) specific to this tag. Detailed biophysical, biochemical, and functional assays were performed to evaluate rTCR expression, folding, pairing, and antigen recognition, as well as antibody performance, using the UniTope & TraCR System. Results: Tagged rTCRs were stably expressed in human T cells with surface densities comparable to untagged rTCRs. The TraCR antibody bound UniTope with nanomolar affinity and no detectable cross-reactivity was observed for endogenous proteins expressed by human cells of diverse origin, importantly, including T cells of the natural T cell repertoires of multiple human donors. Functional assays confirmed that UniTope-tagged rTCRs preserved their antigen-specific cytokine secretion and cytolytic activity upon antigen-specific stimulation. The UniTope & TraCR System enabled robust detection of rTCR-expressing T cells by flow cytometry, and rTCR protein expression by Western blot or immunoprecipitation, supporting the quantitative assessment of receptor copy number and structural integrity. Conclusions: The UniTope & TraCR System provides a modular, construct-agnostic platform for monitoring engineered rTCRs, integrated into TCR-T cell therapies currently in development. Full article

Balancing high fluidity and stability is a critical challenge in deep-shaft cemented paste backfill (CPB) with high-concentration tailings. This study investigates the synergistic regulation mechanism of a combined admixture system comprising hydroxypropyl methylcellulose (HPMC) thickener and polycarboxylate (PCE) or Melamine-Formaldehyde Resin (MFR) superplasticizers on CPB rheology, mechanical strength, and microstructure. Results indicate that HPMC significantly enhanced anti-segregation performance via intermolecular bridging, substantially increasing yield stress and plastic viscosity. Upon PCE introduction, the steric hindrance provided by its side chains effectively disrupted HPMC-induced flocs and released entrapped water. Consequently, yield stress and plastic viscosity were reduced by up to 22.1% and 64.3%, respectively, with PCE exhibiting markedly superior viscosity-reducing efficiency compared to MFR. Mechanical testing revealed that PCE co-addition did not compromise early-age strength but enhanced 3, 7, and 28-day unconfined compressive strength (UCS) by refining pore structures and promoting the uniform distribution of hydration products. Microstructural analysis unveiled a competitive adsorption mechanism: preferential PCE adsorption dispersed particle agglomerates, while non-adsorbed HPMC formed a viscoelastic network within the pore solution, constructing a stable “dispersion-suspension” microstructure. This work provides a theoretical basis for optimizing high-performance backfill formulations. Full article

Understanding how molecular structure governs the reactivity of organic amines with CO₂ is essential for the rational design of next-generation carbon-capture solvents. In this work, three representative series of amines, including linear aliphatic, cyclic aliphatic, and aromatic, were systematically conducted with substituents at different positions, and their reaction rate constants and equilibrium constants with CO₂ were calculated using transition state theory. A suite of electronic-structure and steric descriptors, including ALIE, Hirshfeld charge, Fukui functions, and ESP-derived parameters, was developed to quantify structure–reactivity relationships. Linear aliphatic amines were found to be most sensitive to steric hindrance, while cyclic and aromatic amines were predominantly governed by inductive and conjugation effects. Key descriptors such as N_ALIE and q(N) showed strong correlations with both kinetic and thermodynamic parameters, enabling quantitative interpretation of substituent effects. Notably, a positive linear correlation between ln(k) and ln(K) was observed across all amine classes, revealing an intrinsic coupling between reaction rate and equilibrium. These findings deepen the mechanistic understanding of CO₂–amine chemistry and provide a theoretical foundation for the targeted design and optimization of high-performance CO₂-capture solvents. Full article

The poor stability of CsPbBr₃ perovskite nanocrystals (PNCs) caused by weak and dynamic ligand coordination severely limits their commercial applications. Herein, a dual-ligand synergistic modification strategy based on bromocarboxylic acids (BCAs) and oleylamine (OAm) was developed to mediate the surface structures and luminescent dynamics of CsPbBr₃ PNCs. The results reveal that carboxylate groups of BCA ligands modulate crystal growth, while its terminal Br atom forms a strong coordination with exposed Pb²⁺ on the PNCs surface, which can effectively passivate lead- and bromine-related defects. The synergistic protection of OAm ligands enhances the stability of PNCs via amino-halide electrostatic interactions and steric hindrance effects. Notably, based on the relatively dense surface coating of 4-bromobutyric acid (BBA) and OAm dual-ligands, the prepared CsPbBr₃ PNCs exhibit a high photoluminescence quantum yield (PLQY) of 85.2 ± 2.4% and remarkable storage stability, retaining 90.2 ± 1.7% of their initial PL intensity after being stored for 63 days under ambient conditions. Furthermore, a prototype white light-emitting diode (WLED) fabricated with these PNCs displays a wide color gamut covering 122.1% of the NTSC standard and a luminous efficacy of 64.6 lm/W. This work provides a facile and feasible ligand engineering strategy to obtain highly stable and emissive PNCs. Full article

Forested areas in Poland comprise numerous post-mining sites that hinder effective forest management. Such mining remnants may pose a threat to humans, animals, and operating forest machines. This study aimed to determine the feasibility of inventorying such man-made landforms as mining waste heaps, excavations, remnants of shallow shafts, adits, etc., using the Digital Elevation Model (DEM) based on Airborne Laser Scanning (ALS) data provided by the national agency (the Head Office of Geodesy and Cartography—HOGC) as open data. The DEM, when combined with other cartographic materials using GIS, accurately reflects the anthropogenic transformation evident in the topography. This paper presents the results of inventorying remnants of iron ore mining in the present-day forested area located between Krzepice, Kłobuck, and Częstochowa in southern Poland. The identification and inventory of post-mining landforms, mainly mounds resulting from shallow shaft mining operations, were supplemented by their digitization, automatically providing information on parameters such as perimeter (ranged in most cases from 24.3 to 159 m), surface area (46.9 to 1656 m²), length and width (7.8 to 59.2 m). The heights of the investigated structures were also read from the DEM, ranging from 0.3 to 4.1 m. Much larger structures were also identified, but they occurred accidentally (up to 23.5 m in height). In this manner, approximately 823 morphological forms were characterized, resulting in a database. Test fieldwork was then conducted to verify the DEM readings. It was proposed to calculate deformation indexes (Id [%]) for forested areas and apply them when estimating the forest management hindrance index used by the State Forests. The studied forest compartments managed by State Forests were characterized by an Id value from 0.1 to 55.5%. This type of measure provides a helpful tool in planning forestry operations in areas with diverse topography, including those transformed by mining activities. The actual environmental impact is highlighted. Forest management practices in the study area must take into consideration, in particular, topography, as well as geology and hydrology. Studies have shown that the DEM based on the ALS data is sufficiently accurate to detect even minor post-mining deformations (which may be important, in particular, in inaccessible areas). The recorded parameters can be considered when planning management, protection interventions, or reclamation activities. Full article

In the context of global energy demands, the efficient demulsification of highly stable heavy crude oil emulsions remains a critical challenge. This study systematically investigated the demulsification mechanisms of two demulsifiers (P1# and P2#) through multi-dimensional characterisation and performance evaluation. The results indicated that asphaltenes and resins can strengthen the oil–water interfacial film and stabilise the emulsion due to their unique structural properties. FTIR and ¹HNMR analyses showed that both demulsifiers contained polar groups and alkyl chains; however, P1# exhibited higher viscosity and lower surface tension, which favored its rapid adsorption at the interface. Demulsification tests at 60 °C demonstrated that P1# achieved superior efficiency (92.44% demulsification efficiency (DE) in 120 min versus 82.31% for P2#), attributable to its enhanced ability to displace asphaltene/resin at the oil-water interface. Turbiscan stability analysis and microscopic observations confirmed that P1#-treated emulsions underwent faster droplet coalescence and significant interfacial film disruption. Mechanistic studies indicated that the demulsifiers competitively adsorb at the interface, thereby weakening film cohesion through steric hindrance and charge redistribution. XRD and FTIR analyses suggested that interactions between the demulsifier and the asphaltene/resin increased interlayer spacing and reduced crystallinity. Zeta potential and interfacial tension measurements further highlighted P1#’s ability to neutralize negative charges (from −14.52 mV to +8.3 mV) and reduce the IFT (from 28.5 mN/m to 12.1 mN/m), thereby promoting droplet aggregation. This study helps elucidate the mechanism of emulsion phase transition induced by demulsifiers and provides theoretical support for improving the demulsification efficiency of crude oil emulsions. Full article

Perovskite solar cells (PSCs) have emerged as a rising next-generational photovoltaic technology due to low fabrication costs through solution processing as compared to traditional silicon solar cells and high-power conversion efficiency. However, the poor long-term operational stability due to environmental and mechanical degradation remains a hindrance to commercialization. Herein, self-healing polymer additives are utilized by researchers to enhance the photovoltaic performance of PSCs by enabling self-restorative behavior from physical damage or chemical degradation. This review explores the design and application of self-healing polymers in both flexible and rigid PSCs, contrasting the two main reversible bonding mechanisms: physical bonds, such as hydrogen bonds, and chemical bonds, such as dynamic covalent disulfide bonds. Physical bonds provide passive healing at ambient conditions; meanwhile, chemical bonds offer a stronger restoration under external stimuli such as heat or light. These polymers are exceptionally effective at mitigating mechanical stress and cracks in flexible PSCs and combating moisture-induced degradation in rigid PSCs. The applications of self-healing polymers are categorized based on substrate type, healing mechanism, and perovskite composition, with the benefits and limitations of each approach highlighted. Additionally, the review explores the potential of multifunctional self-healing polymers to passivate defects at the grain boundaries and on surface of perovskite films, thereby enhancing the overall photovoltaic performance. Full article

Rifampicin-resistant tuberculosis (RR-TB) remains a major threat to global TB control, primarily driven by mutations in the rpoB gene of Mycobacterium tuberculosis (Mtb). Most resistance-conferring mutations occur within the 81-base pair RIF resistance determining region (RRDR), particularly at codons S450L, H445Y/D, and D435V, which are strongly associated with high level resistance. However, increasing evidence of low-frequency and disputed variants both within and beyond the RRDR reveals a broader genetic spectrum that contributes to diagnostic uncertainty and variable phenotypic outcomes. This review summarizes current knowledge of high frequency, low frequency, and disputed rpoB mutations and their implications for molecular detection of RIF resistance. Structural analyses show that specific amino acid substitutions alter key hydrogen bonds or create steric hindrance in the RIF-binding pocket, leading to diverse resistance levels. Despite the success of molecular platforms such as Xpert MTB/RIF and line probe assays, their hotspot-based detection limits sensitivity to noncanonical variants. Lowering the minimum inhibitory concentration (MIC) breakpoint and integrating sequencing-based approaches, such as targeted and whole-genome sequencing, can enhance detection accuracy. A combined genomic and phenotypic framework will be essential to close existing diagnostic gaps and advance precision guided management of RIF-resistant and multidrug-resistant tuberculosis. Full article