Search Results (5,069)

The maturity method (ASTM C1074) predicts in situ concrete strength from a recorded temperature history but assumes a constant apparent activation energy, contradicting the experimental evidence that the activation energy falls as hydration shifts from kinetics control to diffusion control—an effect that differs between binder chemistries when supplementary cementitious materials (SCMs) are used. This study develops a physics-based maturity model in which the apparent activation energy varies linearly with temperature, Q(T) = Q₀ + β_Q(T − T_ref), coupling a variable-energy Arrhenius equivalent age to a hyperbolic strength–maturity relationship. The model was calibrated on 196 mean-strength observations (588 cube tests) from seven self-compacting concrete mixtures cured isothermally at 10, 20, 35 and 50 °C and tested at seven ages (1–90 days). All four SCM systems (fly ash, GGBS, silica fume and rice husk ash) returned a negative coefficient (−210 to −974), enclosing the temperature sensitivity implied by independent calorimetric measurements on Portland cement paste (≈−580 J/(mol·K)), whereas the ordinary Portland cement control returned a positive point estimate (+101) that is not statistically distinguishable from zero. The model achieved R² = 0.929 (RMSE = 4.74 MPa), outperforming the constant-energy ASTM C1074 baseline in both accuracy and the Akaike Information Criterion while eliminating its systematic bias at the temperature extremes. Five-fold cross-validation confirms the out-of-sample accuracy (R² = 0.901, RMSE = 5.59 MPa), and bootstrap analysis shows the negative coefficients of the fly ash, GGBS and rice husk ash systems to be statistically significant. External validation on 120 independent literature observations gave R² = 0.881. Full article

Polyethylene (PE) microplastics are environmentally persistent contaminants whose progressive fragmentation suggests that degradation may not be governed by uniform backbone stability. In this work, density functional theory and non-isothermal thermogravimetric analysis were combined to evaluate PE degradation from complementary molecular and kinetic perspectives. A C₉₀H₁₈₂ polyethylene oligomer was optimized at the M06-2X/def2-TZVP level, and position-resolved C–H and C–C bond dissociation energies were calculated along the chain. The C–H bonds showed comparatively high and homogeneous stability, whereas the C–C backbone displayed lower dissociation energies and a localized energetic depression in the central region. The minimum C–C BDE was found at C44, with a value of 85.73 kcal·mol⁻¹, identifying a model-specific low-BDE region within the finite all-trans-derived oligomer that may favor backbone scission under the evaluated computational conditions. Thermogravimetric analysis under nitrogen at 5, 10, and 20 °C min⁻¹ showed a dominant degradation event, with DTG maxima shifting from 462.6 to 494.6 °C as the heating rate increased. Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose analyses revealed a progressive increase in apparent activation energy from approximately 170–175 kJ·mol⁻¹ at low conversion to 280–285 kJ·mol⁻¹ at high conversion. Although BDE and apparent activation energy are not directly equivalent, their combined interpretation supports a heterogeneous degradation model in which PE fragmentation preferentially initiates at localized low-BDE C–C environments before progressing toward regular backbone scission and secondary degradation reactions. Full article

Low-cost adsorbents derived from agricultural and livestock waste offer a sustainable approach to wastewater remediation. In this study, a material derived from cow dung ash (SMCDA) was prepared through a simple waste-valorization route without chemical activation and evaluated for the removal of methylene blue (MB) from aqueous solution. X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller analysis, and zeta-potential measurements were used to characterize the mineral composition, surface functional groups, morphology, pore structure, and surface charge of SMCDA. Batch adsorption experiments examined the effects of solution pH, adsorbent dosage, initial MB concentration, contact time, and temperature. The highest removal efficiency, 97.33%, was obtained at pH 8 with an SMCDA dosage of 1000 mg L⁻¹. Equilibrium data were fitted using seven isotherm models and evaluated using multiple statistical criteria and Multi-Objective Optimization by Ratio Analysis (MOORA). The Freundlich model achieved the highest MOORA ranking and predicted an equilibrium adsorption capacity of 13.944 mg g⁻¹ at the highest concentration investigated, which is close to the experimental value of 14.425 mg g⁻¹. The results are consistent with heterogeneous adsorption involving electrostatic attraction, possible π–π interactions, hydrogen bonding, and pore filling. These findings demonstrate the potential of cow dung ash as a low-cost adsorbent prepared without hazardous chemical activating agents. Full article

Phosphorus is recognized as one of the primary contributors to eutrophication in freshwater ecosystems. Among the various strategies proposed to mitigate its impact, adsorption-based removal has emerged as one of the most widely adopted and effective approaches globally. In this study, Zn/Al-layered double hydroxides (LDHs) were synthesized by varying the molar ratio of cations to obtain materials with different cationic densities. The materials were additionally modified via a co-precipitation method to incorporate titanium dioxide (TiO₂) or zinc oxide (ZnO) nanoparticles to synthesize novel composite nanomaterials aimed at phosphate species removal from aqueous solutions. The resulting materials demonstrated orthophosphate adsorption capacities exceeding 45 mg/g in most cases. Adsorption kinetics were evaluated using pseudo-first order and pseudo-second order models, while equilibrium data were fit to the Langmuir and Freundlich isotherms. The results indicated that the pseudo-second order model and the Langmuir isotherm provided the best fit, suggesting that the adsorption process is predominantly chemisorption occurring on a homogeneous monolayer. These findings highlight the potential of TiO₂/ZnO–LDH composites as efficient adsorbents for phosphorus remediation in aquatic environments. Full article

The aim of this study is to synthesize zinc oxide nanoparticles (ZnO NPs) using G. globosa aqueous leaf extract. The preliminary screening of the phytochemicals was performed with the G. globosa aqueous leaf extract. The physical and chemical characteristics of G. globosa-mediated ZnO NPs were evaluated using UV-Vis spectroscopy, Fourier-transform infra-red spectroscopy (FTIR), X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), nanoanalysis and thermogravimetry. The antibacterial activity of G. globosa-mediated ZnO NPs was assessed against Gram-negative bacteria. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) analyses were performed to evaluate the antibacterial efficacy of the G. globosa-mediated ZnO NPs. The heavy metal adsorption capacity of the synthesized ZnO NPs was evaluated using atomic adsorption spectroscopy (AAS). The UV-Vis spectrum of G. globosa-mediated ZnO NPs proved the excitonic absorption of the synthesized ZnO NPs. FTIR analysis determined the presence of metal oxide functional groups in the G. globosa-mediated ZnO NPs. The average size of 60 nm and the spherical shape of G. globosa-mediated ZnO NPs were confirmed by HRTEM and SEM analyses. The synthesized ZnO NPs had prominent antibacterial activity against Klebsiella pneumoniae and Escherichia coli. G. globosa-mediated ZnO NPs acted as an important adsorbent of heavy metals such as cadmium and lead. Adsorption kinetic studies (pseudo-first-order and pseudo-second-order kinetics) and isotherm analyses (Langmuir and Freundlich models) were performed. The kinetic studies and isotherm models revealed that the synthesized ZnO NPs showed higher adsorption efficiency for cadmium. Full article

The growing volume of crustacean shell waste generated during seafood processing poses a serious environmental problem. However, this type of biowaste remains underutilized, despite being a promising renewable raw material for the production of functional carbon materials. This study aims to investigate how synthesis parameters influence the formation of a hierarchical porous structure in shrimp shell-based carbon materials and to optimize these parameters to improve CO₂ adsorption efficiency. Under optimal carbonization conditions (holding time: 2 h; temperature: 650 °C) and activation conditions (holding time: 2 h; temperature: 750 °C) with activator-to-carbon weight ratios (A/C) of 1/1, 2/1 and 4/1, the resulting porous carbon samples exhibited relatively high S_BET values (1175, 2708 and 3052 m²/g, respectively) and V_T (0.70, 1.55 and 2.60 cm³/g, respectively), as well as different pore size distributions. Notably, the resulting carbon materials demonstrated exceptional CO₂ adsorption performance at 298 K, reaching a maximum adsorption capacity of 40.03 mmol/g at 40 bar for sample SS_652_41752, 15.12 mmol/g at 15 bar for SS_652_21752, and 3.41 mmol/g at 1 bar for SS_652_11752. These values rank among the highest ever reported for biomass-derived porous carbon materials. The adsorption behavior of the most efficient sorbent, SS_652_41752, was further analyzed using Langmuir and Freundlich isotherm models over the temperature range of 298–318 K and at pressures up to 40 bar, and the isosteric heats of adsorption were calculated to elucidate adsorbent–adsorbate interactions. It was found that the differential molar isosteric heat of CO₂ adsorption decreased from approximately 20 to approximately 17 kJ/mol with increasing adsorption uptake, confirming the physisorption nature of the process. These results demonstrate that crustacean shell waste is a promising feedstock for producing carbon materials with tailored properties and significant potential for CO₂ adsorption applications. Full article

Biogas slurry can enhance soil fertility, but the heavy metals it contains may pose potential ecological risks to soil-crop systems. To mitigate heavy metal pollution resulting from the application of biogas slurry to soil, this study investigated potential remediation strategies through the use of blended biochar application. In this study, soil incubation experiments were conducted to evaluate the immobilization performance of cow dung biochar (CB), corn straw biochar (SB), and blended biochar (cow dung + corn straw) (C3S7, C5S5, and C7S3) toward Pb, Zn, Ni, Cr, Cu, As, and Cd under different biogas slurry ratios (Z0, Z1:8, and Z1:4). The results concluded that immobilization efficiency consistently followed the order C7S3 ≥ C5S5 > C3S7 > CB ≈ SB, indicating that the blended biochar generally outperformed the two single biochar in the biogas slurry-irrigated soil system. Batch adsorption experiments showed that adsorption of all metals was better described by the pseudo-second-order model (R² > 0.94). Isotherm fitting further indicated that Zn, Ni, Cr, Cu, and Cd were better fitted by the Langmuir model, whereas Pb and As were better fitted by the Freundlich model. Physicochemical characterization, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDS), and Fourier transform infrared spectroscopy (FTIR) analyses collectively suggested that the superior performance of blended biochar was associated with the integration of mineral-related characteristics from CB and surface chemical properties from SB, which together enhanced the synergistic fixation of coexisting metals. Consistently, biochar application reduced the potential ecological risk index (RI) of bioavailable heavy metals in soil, with blended biochar showing lower RI values than CB and SB. C7S3 exhibited the best performance in all treatments, highlighting the potential of blended biochar as an effective amendment for mitigating multi-metal pollution risks with biogas slurry utilization. Full article

DNA polymerases are crucial for the replication and repair of genetic material. Advances in recombinant DNA technology and protein engineering have enabled the production of enzymes with specific catalytic properties tailored to the requirements of molecular diagnostics, next-generation sequencing, and synthetic biology. This review discusses the classification and structural–functional organization of DNA polymerases, with an emphasis on the thermostable members of Families A and B, which are of great practical importance. The main systems for heterologous expression and methods for purifying recombinant polymerases are summarized. Molecular engineering approaches, including rational design, site-directed mutagenesis, directed evolution, and domain engineering, are also discussed, highlighting how enzymes with improved synthesis fidelity, processivity, inhibitor resistance, and broadened substrate specificity are created. Technologies for developing hot-start polymerases along with the creation of chimeric and multifunctional polymerases are reviewed. Information on commercial polymerases utilized in scientific research and molecular diagnostics is also provided. Furthermore, the current applications of recombinant DNA polymerases in conventional, quantitative, and digital PCR; isothermal amplification; sequencing; synthetic biology; and molecular diagnosis of infectious and hereditary diseases are summarized. Finally, we discuss how the integration of structural biology, computational modeling, and high-throughput screening creates new prospects for engineering next-generation specialized enzymes. Full article

Cataracts are the leading cause of reversible blindness worldwide; this condition results from the aggregation of lens proteins. Currently, surgery remains the only treatment; however, there is growing interest in non-surgical approaches, including the use of bioactive compounds incorporated into nanostructured systems designed to enhance solubility, enable controlled release, and improve bioavailability and bioactivity. Among the bioactive compounds investigated, curcumin has attracted considerable attention due to its antioxidant and anti-inflammatory properties, positioning it as a potential anticataractogenic agent. In the present study, curcumin-loaded nanoemulsion was developed via ultrasonication and characterized by average particle size, D90 percentile, ζ potential, and rheological behavior. In addition, its anti-cataract efficacy was evaluated both using an in vivo model in rats and an ex vivo model employing human cataract samples. The resulting curcumin-loaded nanoemulsion exhibited an average particle size of 152 ± 19.79 nm with a monomodal distribution, along with good physical stability over time. The nanoemulsion exhibited apparent viscosity between 30 and 25 mPa·s, at shear rate values (100 to 0 s⁻¹), indicating slight shear-thinning behavior. Regarding the effect on cataracts, in the in vivo model, cataract reversal was observed. Furthermore, ex vivo isothermal titration calorimetry (ITC) analyses indicated exothermic heat exchange between the curcumin nanoemulsions and cataract fragments, consistent with binding interactions occurring within lens components, likely involving crystallin proteins. These findings provide biophysical and in vivo evidence that intravitreally administered curcumin-loaded nanoemulsions not only prevent but actively reverse lens opacity, positioning them as a promising non-surgical therapeutic approach for cataract treatment. Full article

Triclosan (TCS) is an antimicrobial agent belonging to the bisphenol class, and is widely used in healthcare applications and in personal care products (PCPs). As an emerging pollutant frequently detected in aquatic environments, its toxicity to aquatic organisms and the male reproductive system highlights the need for effective removal methods such as adsorption. In this study, bio-based activated carbon was prepared from chestnut shell as waste biomass (CnSAC), modified by polyethylenimine (PEI) (CnSAC/PEI), manganese oxide MnO₂ (CnSAC/Mn) or a combination of these (CnSAC/Mn-PEI). The prepared adsorbents were evaluated for their efficiency in TCS removal. The composite material CnSAC₅₀₀PEI exhibited improved adsorption efficiency for TCS (99.5%) at pH 3, whereas MnO₂ modification alone did not provide a significant improvement over the pristine activated carbon. The pH_pzc analysis determined the surface charge of the adsorbent, while SEM, FTIR, EDS, and XRD characterization confirmed that the modification formed a thin, homogeneous PEI layer. This layer introduced N–H and C–N functional groups without affecting the porous structure of the activated carbon. The adsorption kinetics showed excellent agreement between both the PSO and PFO models, a combination of physical adsorption mechanisms and surface interactions. Isotherm analysis revealed a Freundlich behavior, indicating adsorption on a heterogeneous surface and a maximum capacity of 250.33 mg/g at 303 K for the CnSAC₅₀₀PEI material. Full article

Climate change may substantially alter the habitat suitability and spatial stability of highland edible and medicinal plant resources. Argentina anserina (L.) Rydb. is an important wild resource plant in western China, but its potential distribution and future climate-change response in the three ethnic prefectures of Sichuan Province remain insufficiently understood. In this study, we used an ensemble species distribution modeling framework based on 31 spatially filtered occurrence records and 12 environmental predictors to evaluate the current and future habitat suitability of A. anserina under SSP126, SSP370, and SSP585 scenarios for the 2050s and 2090s. The ensemble model showed acceptable overall discrimination ability and was used to identify broad-scale suitability patterns. Mean diurnal range, precipitation of the driest quarter, isothermality, and topsoil pH were the main environmental predictors, indicating that thermal variability, dry-season moisture availability, and edaphic conditions jointly shaped habitat suitability. Under current conditions, the total suitable habitat area was predicted to be 15.57 × 10⁴ km², accounting for 57.2% of the study region, with high-suitability habitats mainly concentrated in the northern, northwestern, and central areas. Future projections suggested an overall decline in suitable habitats, especially in high-suitability areas, although the magnitude varied among scenarios and periods. Spatial change and centroid migration analyses indicated that future suitable habitats may undergo contraction and westward or northwestward redistribution rather than uniform expansion. Niche overlap analysis further showed moderate to relatively high overlap between current and future environmental spaces, suggesting partial niche stability with scenario-dependent shifts. Given the limited field-based occurrence records, these findings should be interpreted as broad-scale spatial guidance rather than precise local predictions. Full article

Ammonia-responsive gelatin-based composite films containing cobalt metal–organic frameworks (Co–MOFs) synthesized using gallic acid as an organic ligand were developed and evaluated as intelligent packaging materials. Co–MOFs were incorporated into gelatin films at concentrations of 2.5, 5.0, 7.5, and 10.0% (w/w, based on gelatin). The effects of Co–MOF incorporation on the physicochemical, structural, thermal, mechanical, and sensing properties of gelatin films were systematically investigated. Increasing Co–MOF content reduced film moisture content (from 14.47 to 13.25–13.58%) and swelling capacity (from 599.37 to 484.88–547.30%), while increasing solubility (from 39.09 to 48.88%), water vapor permeability (WVP; from 1.652 to 2.054 g·mm/m²·h·kPa), and moisture sorption behavior. Sorption isotherm analyses based on the Guggenheim–Anderson–de Boer (GAB) and Brunauer–Emmett–Teller (BET) models confirmed enhanced water adsorption capacity and increased specific surface area in the films (from 356.13 to 455.74 m²/g). Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) analyses demonstrated successful incorporation of Co–MOFs into the gelatin matrix, revealing good dispersion at low and moderate concentrations and partial aggregation at higher loadings. The incorporation of Co–MOFs improved the thermal stability of the films, while only a moderate reduction in mechanical strength was observed with increasing filler content. The composite films exhibited rapid and concentration-dependent colorimetric responses toward ammonia vapor. After 120 min of exposure, the color difference (ΔE) increased from less than 1 in the control film to approximately 12, 15, 24, and 27 for G/Co–MOF2.5, G/Co–MOF5, G/Co–MOF7.5, and G/Co–MOF10 films, respectively. Films containing higher amounts of Co–MOF showed faster response kinetics and greater color differences, enabling clear visual detection of ammonia. These findings demonstrate that gelatin/Co–MOF composite films based on gallic acid-derived metal–organic frameworks are promising intelligent packaging materials for monitoring food freshness and spoilage through ammonia detection. Full article

To address the challenges of procedural complexity, the lack of an integrated heating–forming capability, and poor formability in the hot forming of titanium alloy skin components, an electrically assisted forming (EAF) process is proposed. A Johnson–Cook constitutive model was established to characterize the flow behavior of Ti–6Al–4V alloy under electric-assisted conditions, achieving a correlation coefficient of 0.968 and an average relative error of 7.67%. Forming parameters were investigated through a combined approach of numerical simulation and experimentation. At a current density of 7.59 A/mm², a forming speed of 1 mm/min, and a friction coefficient of 0.1, the maximum springback of the component was 1.04 mm. Compared with isothermal forming, the EAF process reduced the springback by 7.14% and enhanced the ultimate tensile strength by 5.34%. Microstructural characterization revealed that, under pulsed current, the α-phase grains of the material were refined, whereas the β-phase fraction and the average grain size increased, accompanied by a 15.3% reduction in the geometrically necessary dislocation (GND) density. This study validates the process feasibility of electrically assisted forming for thin-walled titanium alloy skin components. Full article

Sustainable development is seriously hampered by environmental contamination. Heavy metals are perhaps the most significant of these silent pollutants because of the poisoning they inflict on different ecosystems, particularly water systems, as well as the direct threat they pose to the safety of such systems and the ensuing health issues that affect people and other living things. The goal of the current work is to ascertain how effective peanut (Arachis hypogaea) hulls are as easily accessible and reasonably priced adsorbent materials for the ion adsorption of various heavy metals, including lead, copper, zinc, and cadmium. A series of variables, such as pH, temperature, retention time, shape, quantity of adsorbent and particle size, were investigated to reach the optimal conditions for the biosorption process, which were achieved at pH 6 (close to pH-zero charge), a temperature of 40 °C, a retention time of 60 min, an adsorbent dose of 5 g/L, and a particle diameter of 0.1 mm. Experiments showed that lead had the highest treatment rate, approximately 95%, followed by zinc, copper, and cadmium. The results were confirmed and validated using SEM analysis to identify the morphology of the hulls before and after treatment, FTIR spectroscopy to investigate the functional groups responsible for binding to the metal ions, and further supported by kinetic isotherms of the adsorption behavior, which matched the Langmuir and Freundlich models. Nevertheless, the results of the batch experiment were employed by designing a laboratory treatment unit for municipal wastewater containing beads of alginate-immobilized Arachis hypogaea hulls. The designed laboratory unit was effective in treating unacceptable levels of heavy metals in some municipal wastewater from the local drainages of Ramadi City, Iraq. Overall, the study’s findings suggested that peanut hulls could be used to mitigate toxic metal pollution in an eco-friendly manner that guarantees the accomplishment of the Sustainable Development Goals pertaining to future generations’ right to the safe use of water resources. Full article

In this study, hectorite intercalated with octadecyl trimethylammonium ions was synthesized via one-pot synthesis, and the octadecyl trimethylammonium-modified hectorite was used as an adsorbent to remove phenol from an aqueous solution. The pH and content of the adsorbent were studied to determine the optimized conditions for the adsorption of phenol. The phenol removal rate attained for 50 mL of 100 mg/L initial phenol solution at pH 12 was about 92.3% when 0.5 g of adsorbent was used. As for the adsorption isotherm, the Langmuir and Freundlich models were appropriate. The adsorption kinetics were in accordance with the pseudo-second-order model, and the activation energy (Ea) was about 11.15 kJ/mol. The modified hectorite could be recycled and reused, maintaining a high adsorption amount after five cycles. Full article