摘要 : Microbial polysaccharides (MPs) are biopolymers secreted by microorganisms such as bacteria and fungi during their metabolic processes. Compared to polysaccharides derived from plants and animals, MPs have advantages such as wide sources, high production efficiency, and less susceptibility to natural environmental influences. The most attractive feature of MPs lies in their diverse biological activities, such as antioxidative, anti-tumor, antibacterial, and immunomodulatory activities, which have demonstrated immense potential for applications in functional foods, cosmetics, and biomedicine. These bioactivities are precisely regulated by their sophisticated molecular structure. However, the mechanisms underlying this precise regulation are not yet fully understood and continue to evolve. This article presents a comprehensive review of the most representative species of MPs, including their fermentation and purification processes and their biomedical applications in recent years. In particular, this work presents an in-depth analysis into the structure-activity relationships of MPs across multiple molecular levels. Additionally, this review discusses the challenges and prospects of investigating the structure-activity relationships, providing valuable insights into the broad and high-value utilization of MPs.

摘要 : Capturing organics from wastewater is recognized as the initial step towards carbon valorization, since the direct valorization of organics in domestic wastewater is limited by the low concentration. An innovative method was proposed in our former research, which utilizes captured organics from wastewater as raw material for producing a coarse flocculant, thereafter, using the coarse flocculant to capture organics from wastewater in a cyclical manner. Hydrothermal processing (HTP) and chemical modification are jointly applied to coarse flocculant production . Besides, the hydrothermal liquid fraction of concentrated organic matter was indicated as the potential effective precursor. However, the role of hydrothermal liquid fraction as precursor for coarse flocculant and the regulatory mechanism remain unclear. Therefore, this study aims to evaluate the characteristics of the hydrothermal liquid fraction under different alkaline addition, temperature and time from the perspective of coarse flocculant preparation. The results demonstrated that the dissolved polymeric substances extracting through HTP and acid precipitation process exhibit a high molecular weight (reaching up to 9929 Da) and abundant functional groups (including C O, C N, OH, C O C, etc.). Furthermore, the addition of NaOH, along with relatively moderate temperature and time were recommended for producing the flocculant precursor. Specifically, this study suggests a temperature of 140 °C and a duration of 30 min for the flocculant precursor producing.

摘要 : Chemical-nose strategy has achieved certain success in the discrimination and identification of pathogens. However, this strategy usually relies on non-specific interactions, which are prone to be significantly disturbed by the change of environment thus limiting its practical usefulness. Herein, we present a novel chemical-nose sensing approach leveraging the difference in the dynamic metabolic variation during peptidoglycan metabolism among different species for rapid pathogen discrimination. Pathogens were first tethered with clickable handles through metabolic labeling at two different acidities (pH = 5 and 7) for 20 and 60 min, respectively, followed by click reaction with fluorescence up-conversion nanoparticles to generate a four-dimensional signal output. This discriminative multi-dimensional signal allowed eight types of model bacteria to be successfully classified within the training set into strains, genera, and Gram phenotypes. As the difference in signals of the four sensing channels reflects the difference in the amount/activity of enzymes involved in metabolic labeling, this strategy has good anti-interference capability, which enables precise pathogen identification within 2 h with 100% accuracy in spiked urinary samples and allows classification of unknown species out of the training set into the right phenotype. The robustness of this approach holds significant promise for its widespread application in pathogen identification and surveillance.

摘要 : Thermodynamic inhibitors may be used to inhibit hydrate formation in industry. Alcohol substances, due to their hydrophilic hydroxyl groups in their molecular structure, are prone to form hydrogen bond with water molecules to inhibit hydrate formation. In this work, sec -butyl alcohol is chosen to study the effects on CO 2 hydrate dissociation equilibrium conditions, where the step-heating method is utilized to obtain hydrate equilibrium conditions. The equilibrium curve of carbon dioxide hydrate dissociation moves to the region of lower temperatures or higher pressures. The higher mass fraction of sec -butyl alcohol, the better effect of inhibiting hydrate formation. Sec-butyl alcohol can be used as a thermodynamic hydrate inhibitor.

摘要 : The polycrystalline Yb 23 Cu 7 Mg 4 -type {Gd, Tb} 23 Ni 7 In 4 compounds (space group P 6 3 / mmc, N 194, hP 68) were prepared by arc melting with following annealing. They exhibit ferromagnetic ordering below Curie temperature T C = 142 K for Gd 23 Ni 7 In 4 and T C = 112 K for Tb 23 Ni 7 In 4, respectively. A field-sensitive antiferromagnetic transformation takes place around 90 K in Gd 23 Ni 7 In 4 and 106 K in Tb 26 Ni 7 In 4, respectively. Down to 10 K, they are soft ferromagnets with magnetizations of 4.7 μ B /Gd for Gd 23 Ni 7 In 4 and 5.7 μ B /Tb for Tb 23 Ni 7 In 4 in 90 kOe. In a field change of 50 kOe around T C, Gd 23 Ni 7 In 4 shows magnetic entropy change of −4.7 J/kg⋅K at 133–143 K, while Tb 23 Ni 7 In 4 shows magnetic entropy change of −5.4 J/kg⋅K at 109 K.

摘要 : Fine particulate matter (PM 2.5 ) harms human health and hinders normal human life. Considering the serious complexity and obvious regional characteristics of PM 2.5 pollution, it is urgent to fill in the comprehensive overview of regional characteristics and interannual evolution of PM 2.5 . This review studied the PM 2.5 pollution in six typical areas between 2014 and 2022 based on the data published by the Chinese government and nearly 120 relevant literature. We analyzed and compared the characteristics of interannual and quarterly changes of PM 2.5 concentration. The Beijing-Tianjin-Hebei region (BTH), Yangtze River Delta (YRD) and Pearl River Delta (PRD) made remarkable progress in improving PM 2.5 pollution, while Fenwei Plain (FWP), Sichuan Basin (SCB) and Northeast Plain (NEP) were slightly inferior mainly due to the relatively lower level of economic development. It was found that the annual average PM 2.5 concentration change versus year curves in the three areas with better pollution control conditions can be merged into a smooth curve. Importantly, this can be fitted for the accurate evaluation of each area and provide reliable prediction of its future evolution. In addition, we analyzed the factors affecting the PM 2.5 in each area and summarize the causes of air pollution in China. They included primary emission, secondary generation, regional transmission, as well as unfavorable air dispersion conditions. We also suggested that the PM 2.5 pollution control should target specific industries and periods, and further research need to be carried out on the process of secondary production. The results provided useful assistance such as effect prediction and strategy guidance for PM 2.5 pollution control in Chinese backward areas.

摘要 : Soil cadmium (Cd) pollution has emerged as a pressing concern due to its deleterious impacts on both plant physiology and human well-being. Silicon (Si) is renowned for its ability to mitigate excessive Cd accumulation within plant cells and reduce the mobility of Cd in soil, whereas Selenium (Se) augments plant antioxidant capabilities and promotes rhizosphere microbial activity. However, research focusing on the simultaneous utilization of Si and Se to ameliorate plant Cd toxicity through multiple mechanisms within the plant-rhizosphere remains comparatively limited. This study combined hydroponic and pot experiments to investigate the effects of the combined application of Si and Se on Cd absorption and accumulation, as well as the growth and rhizosphere of A. selengensis Turcz under Cd stress. The results revealed that a strong synergistic effect was observed between both Si and Se. The combination of Si and Se significantly increased the activity and content of enzymes and non-enzyme antioxidants within A. selengensis Turcz, reduced Cd accumulation and inhibiting its translocation from roots to shoots. Moreover, Si and Se application improved the levels of reducing sugar, soluble protein, and vitamin C, while reducing nitrite content and Cd bioavailability. Furthermore, the experimental results showed that the combination of Si and Se not only increased the abundance of core rhizosphere microorganisms, but also stimulated the activity of soil enzymes, which effectively limited the migration of Cd in the soil. These findings provided valuable insights into the effective mitigation of soil Cd toxicity to plants and also the potential applications in improving plant quality and safety.

摘要 : Herein, we engineered a novel pH-responsive ratiometric assay by virtue of the composite system of Ce 3+ -enhanced glutathione-encapsulated copper nanoclusters (GSH-CuNCs-Ce 3+ ) and N-doped carbon quantum dots (N-CQDs). The GSH-CuNCs-Ce 3+ and N-CQDs were fabricated using one-pot chemical reduction and hydrothermal approaches, respectively, and their morphologies as well as physical and chemical properties were testified in detail by a series of characterization techniques. At 350 nm excitation wavelength, the GSH-CuNCs-Ce 3+ /N-CQDs system (GCC-NC) featured the 440/650 nm dual-emitting property. The ratios of fluorescence intensities (F 650 /F 440 ) demonstrated a strong pH-dependence from 3.0 to 5.0 with a coefficient of determination of 0.9982. Consequently, the GCC-NC system was feasible for constructing a pH-responsive dual-emitting fluoroprobe. Based on the catalytic effect of acetylcholinesterase on acetylcholine to yield acetic acid and further trigger varying solution pH, the as-constructed GCC-NC fluoroprobe was satisfactorily applied for detecting malathion. Under optimized conditions, the newly developed GCC-NC fluoroprobe supplied a wider linear range (0.25–200 μM), lower detection limit (0.075 μM), satisfactory recoveries (96.3–106.2%) and higher precision for malathion in several kinds of fruit juice samples. The fortified experiments by malathion's structural analogues and metal ions provided compelling evidence that this fluoroprobe had strong anti-interference capacity and high specificity for malathion. These findings render us to believe that the as-constructed pH-responsive dual-emitting fluoroprobe holds great promise in trace malathion assay in food matrices.

摘要 : Electrocatalytic hydrodechlorination (EHDC) is a promising approach to safely remove halogenated emerging contaminants (HECs) pollutants. However, sluggish production dynamics of adsorbed atomic H (H ads ) limit the applicability of this green process. In this study, bimetallic Pd–Cu@MXene catalysts were synthesized to achieve highly efficient removal of HECs. The alloy electrode (Pd–Cu@MX/CC) exhibited better EHDC performance in comparison to Pd@MX/CC electrode, resulting in diclofenac degradation efficiency of 93.3 ± 0.1%. The characterization analysis revealed that the Pd 0 /Pd II ratio decreased by forming bimetallic Pd–Cu alloy. Density functional theory calculations further demonstrated the electronic configuration modulation of the Pd–Cu@MXene catalysts, optimizing binging energies for H and thereby facilitating H ads production and tuning the reduction capability of H ads . Noteably, the amounts and reduction potential of H ads for Pd–Cu@MXene catalysts were 1.5 times higher and 0.37 eV lower than those observed for the mono Pd electrode. Hence, the introduction of Cu into the Pd catalyst optimized the dynamics of H ads production, thereby conferring significant advantages to EHDC reactions. This augmentation was underscored by the successful application of the alloy catalysts supported by MXene in EHDC experiments involving other HECs, which represented a new paradigm for EHDC for efficient recalcitrant pollutant removal by H ads .

摘要 : Although trace metals in strawberry production system have attracted growing attention, little is known about metal fractionation in soil for strawberry cultivation. We hypothesized that the metal fractions in soil influenced by strawberry production had significant effect on food chain transport of metals and their risk in soil. Here, samples of strawberries and soil were gathered in the Yangtze River Delta, China to verify the hypothesis. Results showed that the acid-soluble Cr, Cd, and Ni in soil for strawberry cultivation were 21.5%–88.3% higher than those in open field soil, which enhanced uptake and bioaccessible levels of these metals in strawberries. Overall, the ecological, mobility, and health risks of Pb, Zn, Ni, and Cu in soil were at a low level. However, the ecological risk of bioavailable Cd, mobility risk of Cd, and cancer risk of bioavailable Cr in over 70% of the soil samples were at moderate, high, and acceptable levels, respectively. Since the increased acid-soluble Cr and Ni in soil were related to soil acidification induced by strawberry production, nitrogen fertilizer application should be optimized to prevent soil acidification and reduce transfer of Cr and Ni. Additionally, as Cd and organic matter accumulated in soil, the acid-soluble Cd and the ecological and mobility risks of Cd in soil were enhanced. To decrease transfer and risk of Cd in soil, organic fertilizer application should be optimized to mitigate Cd accumulation, alter organic matter composition, and subsequently promote the transformation of bioavailable Cd into residual Cd in soil.