Search Results (7,891)

Nitroguanidine-type energetic materials have broad application prospects in the propellant field, and their derivative structures are numerous, with intricate changes in macro-level properties. However, due to the unclear inherent evolution mechanisms of these macro-level properties, the structural optimization of compounds and the iteration of application systems face difficulties. This work systematically investigates the variations in density, thermal decomposition, and sensitivity among nitroguanidine (NQ), 1-amino-2-nitroguanidine (ANQ), and 1-amino-2-nitroguanidinium nitrate (ANGN). Hirshfeld surface and bond dissociation energy analyses reveal that strengthened electrostatic and inductive interactions enhance the hydrogen bonding network in ANGN, leading to its higher density compared to NQ. In contrast, weakened electrostatic interactions in ANQ result in a less robust hydrogen bonding network and a correspondingly lower density. The sensitivity trend is consistently explained from both molecular and crystalline perspectives: an increasingly inhomogeneous electrostatic potential distribution, coupled with a higher frequency of O···O contacts, provides a coherent explanation for the experimental observations. Furthermore, the electron-withdrawing -NH₃⁺ group in ANGN weakens the N–NO₂ bond, reducing its bond dissociation energy and leading to the most intense NO₂ mass spectral signal during thermal decomposition. ANQ exhibits the opposite behavior. A linear correlation (R² = 0.92) is observed between the N–NO₂ BDE and NO₂ mass spectral intensity across NQ, ANQ, and ANGN. This study provides unique insights into the intrinsic mechanisms governing variations in the properties of nitroguanidine derivatives. Full article

Salinity is a key determinant governing microalgal growth, biochemical composition, and the structure of associated epiphytic bacterial communities. To investigate the effects of salinity on the structure and function of the epiphytic bacterial community in Desmodesmus intermedius, this study utilized 16S rRNA gene high-throughput sequencing to analyze the communities across the control (S0) and experimental groups (S5, S10, S15). The results demonstrated that salinity is a key environmental driver governing the structural and functional succession of the bacterial community. Alpha diversity analysis revealed that the control group exhibited the highest bacterial diversity and greater evenness. In contrast, the experimental groups showed a significant increase in the relative abundance of Thauera and a concurrent decrease in Roseococcus with increasing salinity. Beta diversity analysis revealed clear segregation of the epiphytic bacterial communities across the salinity groups. FAPROTAX functional prediction revealed that increasing salinity led to a reduction in chemoheterotrophy, photoheterotrophy, and aerobic chemoheterotrophy, while enhancing nitrogen respiration, nitrate reduction, and other denitrification processes. This shift indicates a substantial reconfiguration of carbon and nitrogen metabolic pathways. BugBase phenotype analysis further revealed that the experimental groups exhibited a higher proportion of Gram-positive bacteria and enhanced biofilm-forming capacity. Canonical correspondence analysis identified salinity as the predominant factor shaping bacterial community structure. This study comprehensively investigates the response mechanisms of the D. intermedius epiphytic bacterial community to salt stress, laying a foundation for understanding microbial functions within the phycosphere. Full article

The low water and fertiliser utilisation efficiency and soil quality degradation caused by high water and fertiliser inputs are the primary challenges facing goji berry cultivation in arid regions. A two-year field experiment was conducted from 2021 to 2022. The experiment included three irrigation rates (I₁, I₂, I₃) of 2160, 2565, and 2970 m³·hm⁻² and three nitrogen application rates (N₁, N₂, N₃) of 165, 225, and 285 kg·hm⁻² to quantify their impacts on soil nutrients, enzyme activity, and goji berry yield in the root zone. Results indicate that the indicators of soil nutrients decrease with increasing soil depth, with depths of 0–20 cm accounting for 24.80–72.48% of total content. With fertility period progression, soil organic matter at depths of 0–80 cm exhibits a “folded-line” trend, while total nitrogen, nitrate nitrogen, and available phosphorus show an “M”-type trend. At depths of 0–40 cm, the proportions of urease, sucrase, and alkaline phosphatase activities all exceeded 70%. At I₁ irrigation rate, enzyme activities gradually increased with rising nitrogen application rates. At I₂ and I₃ irrigation rates, enzyme activities first increased, then decreased with increasing nitrogen application. The highest yields of both fresh and dried fruits were achieved at I₂N₂ treatment, increasing by 14.17% and 14.78%, respectively, compared to conventional management (CK). Analysis of the random forest model indicates that the soil-driven factors influencing yield formation include SA, UA, APA, HPA, SOM, NH₄⁺-N, and TP. Analysis of SQI and yield fitted data indicates that water–nitrogen coupling significantly influences wolfberry yield by regulating soil quality. Partial least squares (PLS-PM) showed that N application and irrigation of soil nutrients did not cause a significant indirect impact on goji berry yield, but a significant positive effect on goji berry yield occurred through enzyme activity. Full article

Glaucoma is a major ocular neurodegenerative disease and a leading cause of irreversible blindness worldwide, with prevalence projected to exceed 110 million by 2040. Although lowering intraocular pressure (IOP) remains the only proven treatment, glaucoma arises from a complex interplay of genetic, local, and systemic factors—including oxidative stress, vascular dysregulation, mitochondrial dysfunction, and neuroinflammation. Emerging evidence suggests that modifiable lifestyle factors may influence these pathogenic pathways. In this review, higher dietary nitrate from leafy greens is consistently associated with lower primary open-angle glaucoma risk, aligning with nitric-oxide-mediated endothelial support and more stable ocular perfusion pressure. Flavonoids (anthocyanins and flavanols), carotenoids (lutein/zeaxanthin), and B vitamins have strong biological rationale for glaucoma prevention but have limited support from long-term, large population-based studies. The effect of polyunsaturated fats on glaucoma remains inconsistent and warrants source-(plant vs. animal) and substitution-based analyses. Consistent protective effects of aerobic exercise and high-quality sleep may be associated with favorable metabolic profiles and ocular perfusion, potentially mitigating retinal ganglion cell loss. Conversely, smoking and alcohol use are frequently coupled with poorer diet quality (e.g., lower vegetable intake) and heightened oxidative stress, which may exacerbate glaucomatous neurodegeneration. However, much of the current literature is constrained by cross-sectional designs, reliance on self-reported food frequency questionnaires, and insufficient use of structural endpoints such as retinal nerve fiber layer imaging. This review focuses on the potential of lifestyle modification and future directions in prevention and treatment strategies for glaucoma, highlighting the need for large-scale, multi-ethnic, genotype-stratified longitudinal studies and randomized controlled trials to establish causality and define optimal intervention strategies. Full article

Background: Patient-reported outcomes are integral to chronic coronary syndrome (CCS) care. The Seattle Angina Questionnaire (SAQ) is validated and prognostic, yet its clinical integration in Bulgaria is undefined. Aim: The aim of this study was to provide a structured, clinically oriented framework for integrating the SAQ into the full CCS care pathway—from screening and phenotyping (obstructive vs. ANOCA/INOCA endotypes) to diagnostics, mechanism-tailored therapy, and follow-up—while outlining a pragmatic roadmap for Bulgarian implementation. Methods: We conducted a semi-structured narrative review (1995–2024) of SAQ’s validation, prognostic utility, and implementation in the literature, augmented with guideline-based frameworks for CCS/ANOCA care. Results: The SAQ (and SAQ-7) shows strong reliability and responsiveness and independently predicts health status and clinical outcomes. Embedding the SAQ at baseline, at 4–12 weeks after therapy changes, and after 6–12 months enables symptom-guided decision-making. A phenotype-guided pathway is proposed that couples the SAQ with CAD burden assessment and—where indicated—ANOCA diagnostics (CFR/IMR, vasoreactivity testing). Mechanism-tailored therapy maps to endotypes (e.g., VSA → CCB ± nitrates; MVA → beta-blocker/ACEi/statin ± ranolazine; obstructive CADGDMT ± PCI/CABG). A minimum dataset, metrics, and registry fields are specified for Bulgarian deployment. Conclusions: A clinically structured framework clarifies how the SAQ adds value beyond description—by informing triage, treatment selection, and follow-up across CCS phenotypes. This approach provides educational guidance and a practical blueprint for pilot implementation in Bulgaria. Full article

In this study, thermodynamic properties such as water activity, osmotic coefficient, and saturation points of the aqueous mixture in the system D-Sucrose + Water + ammonium nitrate (AN) were determined at 298.15 K. The measurements were carried out on the mixtures of concentrations of NH₄NO₃ (ranging from 0.1 to 6 mol·kg⁻¹) and D-sucrose (from 0.1 to 4 mol·kg⁻¹) using our hygrometric method. Powder X-ray diffraction (XRD) and attenuated total reflection–Fourier transform infrared (ATR-FTIR) spectroscopy were used to characterize the solid phases crystallized during the supersaturation of the solution. Other thermodynamic quantities such as the solute activity coefficients, excess Gibbs energies, transfer energies, and solute solubilities were calculated using the Pitzer–Simonson–Clegg (PSC) model. The results obtained indicate that at an AN concentration lower than 1 mol·kg⁻¹, the system exhibits increasingly negative deviations from ideality, and that NH₄NO₃ promotes the salting-out effect of sucrose. Full article

A highly active Co/Beta catalyst was prepared via ion-exchange method, in which sodium cations in the beta zeolite framework were replaced by cobalt ions using an aqueous cobalt nitrate solution. Based on XRD, SEM, TEM, XPS, and nitrogen adsorption–desorption analyses, it was confirmed that cobalt species successfully took the place of sodium ions in beta zeolite, while the cobalt species diffused with a uniform dispersion. Strong electronic coupling between cobalt species and zeolite framework oxygen stabilizes Co²⁺ sites in the material. The catalysts perform high efficiency in dye Acid Orange II (AO7) degradation reactions, which gives more than 99.5% removal efficiency at room temperature and initial pH within 10 min under low catalyst dosage. The advantages of the Co/Beta catalyst are reasonably attributed to its maximized metal−zeolite synergistic efficiency. Full article

Cannabis is usually dioecious, with male and female flowers on separate plants. Cultivators prioritize the use of female plants because their flowers contain a higher density of glandular trichomes, the primary source of cannabinoids, compared to male flowers. Feminized seeds, which give rise exclusively to female plants, are highly valued in the cannabis industry. These seeds are produced by crossing a natural female plant with another female plant that has been masculinized to generate pollen. Masculinization is achieved by inhibiting ethylene and/or applying gibberellins prior to flower initiation in female plants. Currently, silver thiosulfate (STS) is the most common treatment used in the cannabis industry, though environmental concerns arise from silver applications. This study compared STS with three other ethylene-inhibiting agents: aminoethoxyvinylglycine (AVG), cobalt nitrate (CBN), and 1-methylcyclopropene (1-MCP). Some STS and CBN treatments also included gibberellic acid as a synergist. STS-treated plants displayed the most effective masculinization and pollen dispersal, compared to plants treated with AVG. Only STS and AVG generated sufficient pollen for collection. This pollen was initially tested for germination potential and subsequently stored for up to five weeks at 22.2 °C, 7.2 °C, or 1.1 °C.Germination rates ranged from 2.2% to 5.8%, underscoring the influence of storage conditions and highlighting the need to refine preservation methods to enhance agricultural viability. Pollen from plants treated with AVG remained viable for three weeks at 1.1 °C, although there were concerns about a high risk of phytotoxicity. STS-treated pollen also remained viable for three weeks at the same temperature. Neither CBN nor 1-MCP treatments were effective in inducing masculinization. No clear synergistic effect of gibberellic acid combined with STS or AVG was observed; however, growth stunting led to increased mortality. Due to pollen viability and phytotoxicity problems with AVG, STS remains the best treatment to masculinize female cannabis plants when breeding for feminized seeds. Full article

Celery (Apium graveolens L.) is a widely cultivated leafy vegetable of significant agronomic and nutritional importance. Owing to its high nutritional value, global demand for celery has steadily increased. However, under natural cultivation conditions, uncontrolled light exposure often prolongs the seedling stage and impairs celery growth quality. Improving the nutritional quality of celery through artificial regulation of the light environment has therefore become an important research focus. This work aimed to elucidate the impact of varying light–dark cycles on the growth characteristics and nutritional attributes of celery. Six light–dark cycle treatments (4 h/2 h, 8 h/4 h, 16 h/8 h, 24 h/12 h, 32 h/16 h, and 40 h/20 h) were applied, using ‘Oster Ziyu Xiangqin’ as the plant material under a constant light intensity of 400 μmol·m⁻²·s⁻¹. The results revealed that the 24 h/12 h light–dark treatment significantly enhanced plant height, total fresh weight, and root vigor and showed superior performance in photosynthetic and chlorophyll fluorescence parameters. The 32 h/16 h treatment significantly enhanced the accumulation of soluble sugars, proteins, total phenolic compounds, and flavonoids, as well as the activities of antioxidant enzymes, while reducing nitrate-nitrogen levels. In conclusion, the 24 h/12 h light–dark cycle was most conducive to the growth and photosynthetic performance of celery, whereas the 32 h/16 h treatment optimally enhanced its nutritional quality and antioxidant capacity. Full article

Fe₄₂Mn₂₈Cr₁₅Co₁₀Si₅ is a highly strain-hardenable high-entropy alloy (HEA) that is challenging to machine with traditional metal cutting tools. The electrochemical behavior of this HEA was examined in nitrate- and chloride-based electrolytes to understand the electrochemical machining (ECM) process. Potentiodynamic and potentiostatic tests were conducted on this alloy in 1 M and 2.35 M NaNO₃ solutions, with and without additions of 0.01 M nitric acid and 0.01 M citric acid. A 20% NaCl solution was also tested as an electrolyte. Nitrate solutions caused passivation of the HEA, while no passivation was observed in chloride solutions. Surface analysis with X-ray photoelectron spectrometry (XPS) indicated that adding citric acid helped reduce surface passivation. The Faradaic efficiency of ECM increased with higher applied voltage. The chloride solution showed higher Faradaic efficiency than nitrate-based solutions. Specifically, the Faradaic efficiency of 20% NaCl at 10 V is 57.4%, compared to 21.9% for 20% NaNO₃ + 0.01 M citric acid at 10 V. Electrochemical parameters, including anodic and cathodic exchange current densities, Tafel slopes, and corrosion current densities, were calculated from the experimental data. The corrosion current densities in the 20% nitrate solutions ranged from 2.35 to 3.2 × 10⁻⁵ A/cm², while the 20% chloride solution had a lower corrosion rate at 1.45 × 10⁻⁵ A/cm². These electrochemical parameters can help predict the dissolution behavior of the HEA in nitrate and chloride solutions and aid in optimizing the ECM process. Full article

Fe–Ce-MOFs with a rice-grain-like morphology were successfully obtained via hydrothermal synthesis, where ferric chloride (FeCl₃) and cerium nitrate [Ce(NO₃)₃] served as the metal precursors and terephthalic acid (PTA) acted as the organic coordinating ligand. The effects of the Fe:Ce molar ratio, (Fe/Ce):PTA ratio, reaction duration, and synthesis temperature on adsorption performance of the Fe–Ce-MOFs were systematically studied. A comprehensive evaluation was conducted on the removal of fluoride and phosphate ions from aqueous solution. Under optimized conditions, the maximum adsorption capacities of Fe–Ce-MOFs for fluoride and phosphate reached 183.82 mg g⁻¹ and 110.74 mg g⁻¹, respectively. Adsorption data correlated strongly with the Langmuir isotherm, were best represented by the pseudo-second-order kinetic model, and were identified as a spontaneous and endothermic reaction. After three regeneration cycles, the adsorbent still maintained high removal efficiencies for fluoride (85.17%) and phosphate (47.34%) removal. In practical wastewater treatment, removal efficiencies of 92.04% for fluoride and 93.87% for phosphate were achieved. Mechanistic studies revealed that fluoride removal was dominated by electrostatic attraction and hydroxyl–fluoride ion exchange, whereas phosphate removal was attributed to the generation of inner-sphere complexes involving PO₄³⁻ and Fe/Ce active sites. This study not only elucidates the synergistic mechanism of fluoride and phosphate elimination by Fe–Ce-MOFs but also provides theoretical guidance and application prospects for the development of highly efficient and stable bimetallic MOF-based adsorbents for environmental remediation. Full article

Rational fertilization boosts crop yields and enhances nutritional value, but over-fertilization is counterproductive. Furthermore, water eutrophication caused by excessive use of nitrogen fertilizers has become a major agricultural non-point source pollution problem in the Erhai Lake Basin of China. This study took high-fertility soil as the research object and set up six treatments: no fertilization (CK), local recommended fertilization (T1), optimized chemical fertilizer (T2), organic fertilizer replacing 20% (T3), 40% (T4), 60% (T5) of chemical fertilizer with equal nitrogen. The results show that replacement of chemical nitrogen fertilizers with organic nitrogen fertilizers at an appropriate ratio can optimize soil nitrogen supply, enhance the activity of soil nitrogen cycle enzymes, thereby promoting the activity of nitrogen metabolism enzymes and nitrogen assimilation capacity in potato plants, and ultimately achieve a synergistic effect of increased yield, improved quality and higher fertilizer use efficiency. Among the treatments, the nitrate reductase (S-NR) activity in potato leaves was 36.74% and 41.66% higher under T3 than T1 and T4, respectively. For potato quality, Vitamin C (VC) content was 17.41% higher under T3 than T2; soluble protein content was 11.44%, 10.63%, and 9.44% higher under T3 than T1, T2, and T4, respectively. The replacement of chemical fertilizers with organic fertilizers mainly enhances the protein content in potato tubers by increasing soil urease (S-URE) activity and leaf relative chlorophyll content (SPAD) value. Based on the comprehensive differential combination evaluation model, considering potato metabolic absorption, yield, quality, and soil nitrogen content, the T3 treatment is the optimal fertilization method in the Erhai Lake Basin of China. Full article

The Mangalia–Limanu coastal lake system, located in southeastern Romania along the Black Sea, represents a transitional aquatic environment shaped by the interplay between freshwater and marine influences. This study provides an integrated assessment of its physicochemical water parameters, sedimentological and geochemical properties, and benthic macroinvertebrate communities, aiming to evaluate its current ecological status and environmental dynamics. Field measurements using a multiparameter sonde revealed a predominantly freshwater to oligohaline system with moderate spatial heterogeneity. DO levels frequently reached supersaturation (>180%), coupled with high pH (~9.1), indicating intense daytime photosynthetic activity. Conductivity, TDS, and salinity increased longitudinally toward the port water area, while nitrate concentrations showed stronger signals upstream. Sediments were dominated by organic matter (18–88%), with lower carbonate (3–53%) and siliciclastic (8–49%) contents. Organic-rich deposits prevailed in the western-central sector, where reduced hydrodynamics and submerged vegetation favor autochthonous organic accumulation, whereas the eastern sector, exposed to marine action, showed more siliciclastic-rich substrates. Geochemical analyses revealed localized exceedances of Cr, Ni, Cu, Zn, and Pb regulatory thresholds (Order 161/2006), suggesting potential contamination hotspots. Benthic communities included 26 taxa, dominated by polychaetas, gammarids, and gastropods, with moderate diversity (H′ < 2). The results highlight a system under moderate anthropogenic pressure but retaining transitional lagoon characteristics, emphasizing the need for continued ecological monitoring and integrated management measures. Full article

Global warming is expected to increase the frequency and intensity of extreme precipitation, yet its effects on soil greenhouse gas (GHG) emissions and functional stability remain uncertain. This study explored the impact of extreme soil moisture conditions on farmland and forest soil under three scenarios: 60% field water capacity (W1), soil saturation (W2), and 10 cm of standing water (W3). We used a laboratory incubation to evaluate how three extreme soil moisture regimes—60% of field water capacity (W1), soil saturation (W2), and 10 cm of standing water (W3)—affect GHG emissions and the functional stability of farmland and forest soils. Forest soils exhibited significantly higher global warming potential (GWP) than farmland across all regimes (p < 0.05). Relative to W1, farmland GWP increased by 0.14% under W3, whereas forest GWP increased by 13.7% under W2 (p < 0.05). Extreme soil moisture conditions markedly elevated total organic C (TOC) and ammonium N (NH₄⁺–N) contents in soil solutions from both farmland and forest, with increases of 25.0% and 6.0% for TOC and 78.6% and 69.6% for NH₄⁺–N, respectively. Conversely, nitrate N (NO₃⁻–N) content in farmland soil decreased by 3.54% and 6.96% under W2 and W3 treatments, while forest soil NO₃⁻–N increased by 39.68% under W2 and decreased by 39.13% under W3. Functional stability declined under extreme precipitation and was positively correlated with total CO₂ emissions, GWP, and TOC (p < 0.001), as well as with total N₂O emissions and soil total C (p < 0.05). Overall, forest soils maintained greater functional stability than farmland under extreme moisture. These findings clarify how extreme soil-moisture events influence soil functional stability in a warming climate and highlight the potential for post-event recovery of soil functions. Full article

The present research moves the focus from merely describing epikarst flow to quantifying its natural filtration performance and contaminant retention mechanisms through integrating in situ tracer experiments with controlled laboratory modelling—an approach seldom applied in previous studies. Two field experiments at Peč Cave demonstrated that the epikarst exhibits rapid hydraulic connectivity—evidenced by fast tracer breakthrough with virtual flow speeds between 0.0041 and 0.006 m/s—yet simultaneously provides strong attenuation, as shown by the low tracer recovery and near-complete removal of microbial contaminants as well as nitrogen compounds through retention, degradation, and dilution under natural infiltration conditions, including rainfall and snowmelt. Complementary laboratory simulations further confirmed this duality, with nitrate concentrations reduced by 30–50%. Field data and lab results consistently indicated that the epikarst does not merely transmit water but actively adsorbs and transforms pollutants. Overall, the epikarst on Suva Planina functions as an effective natural filtration layer that substantially improves groundwater quality before it reaches major karst springs, acting as a protective yet vulnerable “skin” of the aquifer. These findings highlight the epikarst’s critical role in Suva planina Mt. karst aquifer protection and results support consideration of epikarst in groundwater management strategies, particularly in regions where springs are used for public water supply. Full article