Search Results (10,151)

The river ecosystems of the Qinghai–Tibet Plateau, recognized as a vital component of the “Asian Water Tower,” possess unique hydrological conditions and extreme environments that have shaped key indicator groups, most notably zooplankton. The community dynamics and structural characteristics of these zooplankton exhibit regular spatio-temporal distribution patterns across elevational gradients and seasonal successions. However, the intrinsic mechanisms underlying community succession and their correlations with environmental factors remain poorly understood, and the primary environmental drivers influencing community structure require further elucidation. Based on systematic zooplankton surveys and environmental data collection conducted across the Lhasa River basin from 2019 to 2021, this study established a comprehensive species inventory comprising 113 taxa across four major groups, alongside a multi-dimensional environmental dataset. We analyzed the spatio-temporal heterogeneities of zooplankton community structures—including abundance, biomass, and diversity indices—across different seasons and river reaches. The results revealed the composition and seasonal turnover of dominant taxa, with rotifers accounting for 39.82% of the total taxonomic richness. Mean zooplankton abundance and biomass across the basin were 1.18 ind./L and 343.60 × 10⁻⁵ mg/L, respectively, with peak values observed during autumn and within the Chabalang Wetland. The zooplankton community structure in the upstream, midstream, and downstream reaches, as well as associated wetlands, was significantly correlated with specific environmental factors (p < 0.05), including ammoniacal nitrogen (NH₄⁺-N), magnesium (Mg²⁺), total hardness (TH), potassium (K⁺), iron (Fe²⁺), sodium (Na⁺), sulfite (SO₃²⁻), nitrate ion (NO₃⁻), chloride ion (Cl⁻), total phosphorus (TP), and sulfide (S²⁻). Cl⁻, TH, Mg²⁺, SO₃²⁻, and elevation (Ele) were the key environmental drivers significantly influencing zooplankton abundance across seasons (p < 0.05). Furthermore, zooplankton abundance decreased significantly with increasing elevation during the winter. This research deepens our understanding of community assembly mechanisms in plateau river ecosystems and provides a scientific foundation for aquatic biodiversity conservation and ecological management in the Lhasa River basin. Full article

Magnesium phosphate cement (MPC) is a type of rapid-hardening inorganic cementitious material, which has important application value in rapid road repair, solidification of hazardous and radioactive waste, and other fields. However, it suffers from excessively fast setting and hardening and a short working time retention, which severely restrict its engineering application. Therefore, the development of high-efficiency set retarders is of great significance for optimizing MPC performance, enhancing its construction workability, and expanding its application scope. In this study, the effect of sodium polyacrylate (PAAS) on the setting and hardening of magnesium potassium phosphate cement (MKPC) was investigated by testing the setting time and fluidity at a low water-to-solid ratio (W/S = 0.18). Through pH and electrical conductivity measurements, combined with XRD, TG/DTG, and FTIR characterizations, we elucidated the retarding mechanism of PAAS on MKPC using a high water-to-solid ratio (W/S = 10). The results indicate that the setting time of MKPC is positively correlated with the PAAS dosage, whereas the fluidity and compressive strength exhibited a negative correlation with the PAAS dosage. Additionally, PAAS reduces the total heat release and the heat release rate of MKPC. The addition of PAAS increased the pH of the suspension, thereby reducing the solubility of MgO, but did not inhibit the dissolution of KH₂PO₄  The carboxylate groups in PAAS chemically reacted with Mg²⁺ on the surface of MgO to form magnesium carboxylate complexes (Mg-PAA), which remained as precipitates in the MKPC suspension system, thus reducing the amount of available Mg²⁺ participating in the hydration reaction. Furthermore, PAAS had no effect on the final precipitate composition at the end of hydration, which was composed of MgKPO₄·6H₂O  and Mg₃(PO₄)₂·22H₂O  in all cases. Full article

Enzyme-assisted carbon capture is attracting massive interest, and absorbents composed of aqueous carbonate supplemented with carbonic anhydrase have proven particularly promising. Here, we study basic capture mechanisms using a novel approach grounded in comparative enzymology. We determined initial, steady-state capture rates in potassium carbonate under a range of conditions and observed a characteristic saturation behavior at high concentrations of either enzyme or CO₂. These results could be rationalized by a modified Michaelis–Menten framework applied to a “reaction zone” near the liquid surface. Capture rates corresponded directly to enzyme reaction rates in the reaction zone as determined by K_M and k_cat, and this explained the observed saturation behavior. The kinetic data suggested a depth of the reaction zone of about 20 µm. This meant that equilibrium between CO₂ and HCO₃⁻ was obtained within this shallow film and that enzymes deeper in the liquid had little or no influence on capture rates. This approach also allowed us to rationalize the effect of pH on enzyme-assisted capture rates. Overall, steady-state kinetics can be used in comparative and mechanistic analyses of enzyme-accelerated carbon capture. The approach is theoretically simple, requires limited experimental input, and offers key molecular insights. Full article

Spreading depolarizations (SDs) are major pathophysiological events in several brain diseases, including migraine, brain ischemia, trauma, and epilepsy. However, the electrophysiological detection of SDs remains challenging. In this study, we examined changes in spikes (action potentials (APs) and action currents (ACs)) in layer 5 neurons of the somatosensory cortex of anesthetized rats during transient excitation at the onset of high-potassium-induced SDs. During whole-cell recordings, spike amplitude progressively decreased while spike duration increased during gradual neuronal depolarization at SD onset, culminating in depolarization block. A similar decrease in spike amplitude and increase in spike duration were observed during the pre-SD excitation phase in loose cell-attached recordings from single neurons and in cluster analysis of extracellular spikes. Multiple (non-clustered) unit activity also showed decrease in spike amplitude and spike broadening during pre-SD excitation. These findings suggest that dynamic changes in spike amplitude and duration at SD onset could serve as markers for SD detection. Full article

Glued-laminated timber (GLT) and cross-laminated timber (CLT) panels are increasingly used as exposed structural elements in representative buildings. These structures are often part of public-use areas, which require the application of restrictive fire-safety measures without significantly affecting the color of exposed wooden surfaces during the service life of these building elements. The effect of fire-retardant treatments on the color of Scots pine (Pinus sylvestris L.) wood was evaluated using five impregnation agents with different active substances. Changes in gloss and color characteristics—lightness (L*), green-red coordinate (a*), and blue-and-yellow coordinate (b*)—were measured sequentially directly after impregnation, after exposure to variable humidity conditions and after exposure to UV radiation. The total color difference (ΔE*) ranged from 2.82 to 17.76 after impregnation and increased to 6.31–20.71 after aging, indicating a risk of aesthetic deterioration of fire-retardant-treated wood surfaces under typical service conditions for timber structures in representative buildings. The most pronounced color changes were observed for the fire retardant containing potassium and copper compounds (FR4) and the combination of 2-aminoethanol with boric acid (FR5). Full article

Neuron-targeted therapies for Alzheimer’s disease (AD) have shown limited efficacy, highlighting the need to explore glial-based mechanisms of neuroprotection. Here, we show that astrocyte mitochondrial uncoupling via viral overexpression of uncoupling protein 4 (UCP4) restores neuronal circuits and ion channel function in aged 3xTG AD mice with overt symptoms. Spontaneous local field potential recordings revealed a partial recovery of hippocampal and subicular sharp wave ripple oscillations, electrophysiological signatures of neuronal circuits known to be altered in AD. Combined whole-cell patch-clamp electrophysiology with two-photon Ca²⁺ imaging further demonstrated that UCP4 modulates activity-dependent Ca²⁺ influx, A-type potassium channel function, and enhances glial cell line-derived neurotrophic factor (GDNF) signaling. These findings identify astrocytic mitochondrial uncoupling as a potent mechanism enhancing neuronal resilience and restoring circuit function in symptomatic AD brains. Full article

Sustainable fertilizer technologies are essential to address nutrient losses, environmental pollution, and inefficiencies associated with conventional urea application. In this study, humic acid–functionalized starch (St–HA) gel coatings were developed and optimized via a Wurster fluidized-bed system to produce controlled-release urea granules, with an additional carnauba wax outer layer to further extend nutrient release duration. The coating formulation was synthesized through in situ crosslinking of tapioca starch with humic acid using N,N′-methylenebisacrylamide and potassium persulfate, yielding a cohesive film. A central composite rotatable design (CCRD) was employed to investigate the influence of atomizing air pressure, fluidizing air flow rate, fluidized-bed temperature, and spray rate on coating performance. Comprehensive characterization; including FTIR, XRD, rheological analysis, thermogravimetric studies, water retention, biodegradability, and surface abrasion, confirmed chemical crosslinking, structural stability, and mechanical robustness of the coatings. Nitrogen release analysis in both water and soil demonstrated a substantial extension of release longevity from less than 2 days (uncoated) to 18–20 days for St–HA-coated urea, and up to 28 days with the additional wax coating. Coated granules exhibited low abrasion (8–24%), high water-retention capacity, and 68% biodegradation in 60 days, ensuring environmental compatibility. The findings establish St–HA/wax hybrid coatings as a viable, eco-friendly strategy for controlled-release fertilizers, integrating renewable feedstocks with scalable industrial processing for precision nutrient management. Full article

The integration of appropriate tillage practices with straw returning can effectively mitigate soil degradation in Northeast China. However, limited research has explored the impacts of different tillage practices combined with varying straw incorporation depths on the structure and diversity of soil microbial communities. In 2016, a field experiment was initiated using a two-factor split-plot design, featuring six treatments: two tillage depths of 10 cm (D10) and 30 cm (D30) combined with three straw management practices—straw mixing incorporation (SM), straw deep burial (SB), and straw removal (SR). Soil samples collected in 2019 were analyzed for multiple soil properties and microbial indices. Results indicated that both straw returning and tillage depth significantly influenced soil organic carbon (SOC), soil total nitrogen (STN), total phosphorus (TP), and total potassium (TK), with the D30 treatment combined with straw returning optimizing soil nutrient contents most effectively. Under straw returning, D10 significantly increased urease activity in the 0–10 cm soil layer, whereas D30 enhanced this enzyme activity in the 10–30 cm soil layer, while β-glucosidase activity was less responsive to tillage depth. For the D10 treatment with straw returning, acid phosphatase activity was markedly higher than that in the straw removal treatment, whereas N-acetyl-β-D-glucosaminidase activity exhibited the opposite trend. Straw-returning methods had no significant effects on the bacterial and fungal Chao1 indices, while the Shannon index was positively correlated with key soil properties. Redundancy analysis (RDA) of microbial community composition at the phylum level and soil environmental factors revealed that soil nutrients in the 0–10 cm soil layer were positively correlated with Actinobacteriota, Ascomycota, and Basidiomycota, whereas the explanatory power of soil nutrients for microbial community variation decreased in the 10–30 cm soil layer. Our results highlight that tillage depth and straw returning can regulate soil microbial community composition and enhance soil nutrient cycling, thereby providing a theoretical basis for optimizing the combined application mode of tillage and straw-returning practices in Northeast China. Full article

We report on sub-50 fs pulse generation from a diode-pumped mode-locked laser based on an ytterbium-doped monoclinic potassium yttrium double tungstate crystal operating in the 1 μm spectral region. Pumping by a low-power, spatially single-mode, fiber-coupled laser diode at 976 nm, a maximum continuous-wave output power of 433 mW at 1066.1 nm was obtained. Using a quartz-based intracavity Lyot filter, an exceptionally broad continuous-wavelength tuning range of 98 nm was achieved. In the mode-locked regime, the diode-pumped Yb:KY(WO₄)₂ laser delivered soliton pulses as short as 46 fs at a central wavelength of 1069.2 nm by employing a SEmiconductor Saturable Absorber Mirror. To the best of our knowledge, these results represent the broadest continuous-wave tuning range and the shortest pulse duration ever reported for lasers based on ytterbium-doped monoclinic double tungstate crystals. Full article

The rhizosphere is a critical interface linking plants and soil; however, the mechanisms by which parasitic plants affect host growth through rhizosphere microecological changes remain unclear. This study systematically elucidates how Monochasma savatieri, a hemiparasitic plant, promotes blueberry growth by reshaping rhizosphere microecology. Pot experiments showed that parasitism significantly enhanced urease, sucrase, and soil nitrate reductase activities, improving organic matter decomposition and nutrient transformation efficiency. Concurrently, soil total nitrogen (TN), total phosphorus (TP), and total potassium (TK), along with alkali-hydrolyzable nitrogen (AN) and available potassium (AK), decreased, suggesting enhanced nutrient absorption by roots. At the microbial level, parasitism altered community composition and diversity, enriching functional taxa such as Nitrosomonas, OLB5, and Serendipita. Functionally, pathways related to stress resistance (necroptosis and glutamatergic synapses) were activated, whereas those linked to pathogen colonization (Pseudomonas aeruginosa biofilm formation and tryptophan metabolism) were suppressed. These modifications reduced harmful microbial competition, optimized nutrient cycling and signaling networks, and established a favorable rhizosphere microenvironment for root health. By integrating soil enzyme activity, nutrient dynamics, and microbial functions, M. savatieri systemically improves the rhizosphere microenvironment, ultimately enhancing blueberry growth. This study provides theoretical support for intercropping and management of parasitic plants with blueberries. Full article

Cadmium (Cd) contamination of agricultural soils poses a serious threat to crop productivity and food safety due to its high mobility, bioaccumulation potential, and toxicity. This study investigated the effects of increasing Cd levels on growth performance, physiological responses, Cd partitioning, mineral nutrient disruption, and Cd accumulation in four Brassicaceae crops (cress, watercress, broccoli, and white cabbage). Plants were grown in plastic pots filled with 4 kg of soil under controlled greenhouse conditions and exposed to five different Cd concentrations (0, 5, 10, 20, and 50 mg kg⁻¹). Cd exposure significantly affected growth and physiological responses in a species-dependent manner. Compared to the control, shoot dry weight decreased by up to 66.4% in broccoli and 51.7% in cress at the highest Cd level, while white cabbage exhibited comparatively greater tolerance. Oxidative stress indicators showed contrasting patterns, with hydrogen peroxide (H₂O₂) increasing by up to 8.8-fold, whereas proline and membrane permeability (MP) responses varied among species. Photosynthetic pigments declined in cress but increased in broccoli under high Cd conditions, suggesting differential adaptive strategies. Cd accumulated predominantly in roots; however, root retention capacity declined at elevated Cd concentrations (20–50 mg kg⁻¹ soil), leading to greater Cd translocation to shoots. Elevated translocation factors and shoot Cd distribution demonstrated that physiological tolerance did not necessarily limit Cd accumulation in edible tissues. Cd stress also induced notable imbalances in essential mineral nutrients, particularly potassium (K), calcium (Ca), and zinc (Zn), reflecting strong Cd–nutrient interactions at uptake and transport levels. These nutrient disruptions not only exacerbated physiological stress responses but also reduced the nutritional quality of plant tissues. Notably, species maintaining relatively stable growth under moderate Cd exposure still accumulated substantial Cd concentrations in shoots, highlighting a critical disconnect between agronomic performance and food safety. In conclusion, the findings demonstrate that Brassicaceae crops exhibit contrasting strategies in response to Cd stress, with significant implications for Cd entry into the food chain. The study emphasizes the importance of integrating physiological assessment with metal partitioning and nutrient balance analyses when evaluating crop suitability for cultivation in Cd-contaminated soils and for mitigating potential risks to human health. Full article

Salt stress inhibits plant growth, requiring salt-tolerant genes for the development of resilient plants. A key tolerance mechanism is potassium/sodium homeostasis, governed by Shaker K⁺ channels. Given that Shaker K⁺ channels from salt-sensitive species have been extensively studied while their counterparts in salt-tolerant plants remain largely unexplored, this study investigates the evolution and function of these channels in salt-tolerant bermudagrass to address this knowledge gap. Genomic analysis identified 25 Shaker K⁺ channel genes, an expanded family relative to other species. Phylogenetics placed them into five groups (I–V), with groups I, II, III, and V expanded via segmental duplication. Salt stress response screening revealed that only CdKAT1.1 was rapidly upregulated. Functional assays in yeast demonstrated that both CdKAT1.1 and its closest homolog CdKAT1.2 improve potassium uptake and salt tolerance, but the enhancement from CdKAT1.1 was significantly greater. This work elucidates the expansion and functional divergence of Shaker K⁺ channels in bermudagrass. CdKAT1.1 emerges as a superior regulator of potassium efficiency and salt tolerance, making it a prime candidate for molecular breeding to improve plant resilience in saline-alkaline soils. Full article

Returning organic amendments to saline–alkali soils constitutes a key strategy for soil amelioration, as it enhances crop productivity by modulating the rhizosphere microenvironment. In this study, straw, biochar, and peat were selected as representative organic amendments, and a two-year field experiment—employing a rotational cropping system of Sesbania and Triticale—was conducted to investigate their differential regulatory effects on rhizosphere properties and root development. Results demonstrated that all three amendments induced coordinated shifts in the rhizosphere “extract–microbiota–enzymes–nutrients” nexus, concomitant with significant stimulation of root growth. The hypothesized pathways through which different organic amendments improve the rhizosphere environment vary mechanistically: straw application appears to enhance alkaline phosphatase activity and enrich phosphorus-solubilizing microorganisms; it is hypothesized that this promotes root growth by facilitating the mineralization of organic phosphorus. In contrast, peat amendment induces the most pronounced increases in esterase content and sucrase activity, and its growth-promoting effect is likely attributable to accelerated carbon and phosphorus cycling. Biochar, meanwhile, is associated with elevated catalase activity, improved potassium retention, and enhanced organic carbon sequestration; its beneficial function is postulated to stem from mitigation of oxidative stress. Collectively, this study provides initial evidence that distinct organic amendments modulate rhizosphere processes via divergent biochemical and microbial mechanisms—offering a theoretical foundation for their rational selection and application in saline–alkali soil remediation. Full article

The vitamin D receptor (VDR) acts as both a nuclear transcription factor and a non-genomic mediator that regulates a broad spectrum of physiological processes beyond calcium and phosphate homeostasis. VDR plays an important role in the modulation of ion channels across multiple tissues, including osteoblasts, renal and intestinal epithelial cells, neurons, and vascular smooth muscle. These regulatory mechanisms encompass genomic actions through vitamin D response elements in target genes—such as TRPV5, TRPV6, KCNK3, and KCNH1—as well as rapid, non-genomic actions at the plasma membrane involving protein disulfide isomerase A3 and associated signaling cascades. VDR-mediated transcriptional control of calcium, potassium, and chloride channels contributes to the fine-tuning of cellular excitability, calcium transport, and mitochondrial function. Evidence also implicates VDR–ion channel crosstalk in various pathological contexts, including renal cell carcinoma, breast and cervical cancers, pulmonary arterial hypertension, and osteoporosis. Understanding the molecular interplay between VDR and ion channels provides new perspectives on the pleiotropic effects of vitamin D and offers promising therapeutic opportunities in oncology, cardiovascular disease, and skeletal disorders. This review synthesizes previous and current evidence on the genomic and non-genomic mechanisms underlying VDR–ion channel regulation and highlights novel frontiers in vitamin D signaling relevant to human health and disease. Full article

Soil degradation poses a serious threat to the sustainability of global agricultural development, endangering the foundation and environment of human survival. Therefore, elucidating the effects of different agricultural production patterns on the quality and health of paddy soils is of great significance. To investigate the impact of the integrated rice-red swamp crayfish farming on paddy soil health, this paper systematically analyzed the differences in 19 soil physicochemical indicators and bacterial and eukaryotic microbial communities between the traditional rice monoculture (TRM) and integrated rice-red swamp crayfish (Procambarus clarkii) farming (IRPF), and it features a comprehensive quantitative assessment of paddy soil health status through Principal Component Analysis based on a minimum dataset. The experimental results showed that IRPF significantly increased the soil aggregate mean weight diameter, total phosphorus, available potassium, cation exchange capacity, pH, available zinc, and available silicon contents. Meanwhile, IRPF exerted marked effects on the beta diversity and composition of both bacterial and eukaryotic microbial communities, markedly enhancing the relative abundances of Bacillariophyta and Chlorophyta in the paddy soil. The integrated analysis of 19 soil physicochemical indicators along with bacterial and eukaryotic microbial community parameters revealed that the Soil Health Index under IRPF was obviously higher than that under the rice monoculture. In conclusion, the integrated rice-red swamp crayfish farming system markedly impacted the soil fertility, effectively improved soil aggregate structure and enhanced the overall paddy soil health status, representing a promising and sustainable agricultural production pattern within a single production cycle. Full article