Electron-Sponge Nature of Polyoxometalates for Next-Generation Electrocatalytic Water Splitting and Nonvolatile Neuromorphic Devices.

Designing next-generation molecular devices typically necessitates plentiful oxygen-bearing sites to facilitate multiple-electron transfers. However, the theoretical limits of existing materials for energy conversion and information storage devices make it inevitable to hunt for new competitors. Polyoxometalates (POMs), a unique class of metal-oxide clusters, have been investigated exponentially due to their structural diversity and tunable redox properties. POMs behave as electron-sponges owing to their intrinsic ability of reversible uptake-release of multiple electrons. In this review, numerous POM-frameworks together with desired features of a contender material and inherited properties of POMs are systematically discussed to demonstrate how and why the electron-sponge-like nature of POMs is beneficial to design next-generation water oxidation/reduction electrocatalysts, and neuromorphic nonvolatile resistance-switching random-access memory devices. The aim is to converge the attention of scientists who are working separately on electrocatalysts and memory devices, on a point that, although the application types are different, they all hunt for a material that could exhibit electron-sponge-like feature to realize boosted performances and thus, encouraging the scientists of two completely different fields to explore POMs as imperious contenders to design next-generation nanodevices. Finally, challenges and promising prospects in this research field are also highlighted.

Glutamate-pantothenate pathway promotes antibiotic resistance of Edwardsiella tarda.

Although cellular metabolic states have been shown to modulate bacterial susceptibility to antibiotics, the interaction between glutamate (Glu) and chloramphenicol (CAP) resistance remains unclear because of the specificity of antibiotics and bacteria. We found that the level of Glu was upregulated in the CAP-resistant strain of Edwardsiella tarda according to a comparative metabolomics approach based on LC-MS/MS. Furthermore, we verified that exogenous metabolites related to Glu, the tricarboxylic acid (TCA) cycle, and glutathione (GSH) metabolism could promote CAP resistance in survival assays. If GSH metabolism or the TCA cycle is inhibited by L-buthionine sulfoximine or propanedioic acid, the promotion of CAP resistance by Glu in the corresponding pathway disappears. According to metabolomic analysis, exogenous Glu could change pantothenate metabolism, affecting GSH biosynthesis and the TCA cycle. These results showed that the glutamate-pantothenate pathway could promote CAP resistance by being involved in the synthesis of GSH, entering the TCA cycle by direct deamination, or indirectly affecting the metabolism of the two pathways by pantothenate. These results extend our knowledge of the effect of Glu on antibiotic resistance and suggest that the potential effect, which may aggravate antibiotic resistance, should be considered before Glu and GSH administration in the clinic.

Continuous renal replacement therapy with oXiris® in patients with hematologically malignant septic shock: A retrospective study.

BACKGROUND: The mortality rate from septic shock in patients with hematological malignancies (HMs) remains significantly higher than that in patients without HMs. A longer resuscitation time would definitely be harmful because of the irreversibly immunocompromised status of the patients. Shortening the resuscitation time through continuous renal replacement therapy (CRRT) with oXiris® would be an attractive strategy in managing such patients. AIM: To explore the effects of CRRT and oXiris® in shortening the resuscitation time and modifying the host response by reducing inflammation mediator levels. METHODS: Forty-five patients with HM were diagnosed with septic shock and underwent CRRT between 2018 and 2022. Patients were divided into two groups based on the hemofilter used for CRRT (oXiris® group, n = 26; M150 group, n = 19). We compared the number of days of negative and total fluid balance after 7 d of CRRT between the groups. The heart rate, norepinephrine dose, Sequential Organ Failure Assessment (SOFA) score, and blood lactic acid levels at different time points in the two groups were also compared. Blood levels of inflammatory mediators in the 26 patients in the oXiris® group were measured to further infer the possible mechanism. RESULTS: The average total fluid balance after 7 d of CRRT in the oXiris® group was significantly lower than that of patients in the M150 hemofilter group. The SOFA scores of patients after CRRT with oXiris® therapy were significantly lower than those before treatment on day 1 (d1), d3 and d7 after CRRT; these parameters were also significantly lower than those of the control group on d7. The lac level after oXiris® therapy was significantly lower than that before treatment on d3 and d7 after CRRT. There were no significant differences in the above parameters between the two groups at the other time points. In the oXiris® group, procalcitonin levels decreased on d7, whereas interleukin-6 and tumor necrosis factor levels decreased significantly on d3 and d7 after treatment. CONCLUSION: CRRT with oXiris® hemofilter may improve hemodynamics by reducing inflammatory mediators and playing a role in shortening the resuscitation period and decreasing total fluid balance in the resuscitation phases.

Engineering Multishelled Nanostructures Enables Stepwise Self-Degradability for Drug-Release Optimization.

The balance between degradability and drug release kinetics is a major challenge for the development of drug delivery systems. Here we develop hierarchically structured nanoparticles comprising multiple noncontact silica shells using an amorphous calcium carbonate template. The system could be degraded in a sequential fashion on account of the molecularly engineered multishelled structures. The hydrolysis rate of drug-containing cores is inversely correlated with the nanoparticle concentration due to the shielding effect of the hierarchical nanostructure and could be exploited to regulate the release kinetics. Specifically, multishelled nanospheres show a low drug release rate with high doses that increases steadily as the concentration decreases due to continuous degradation, thus stabilizing the local drug concentration for effective tumor therapy. Moreover, the nanoparticles could be eventually degraded completely, which may reduce their health risks. This kind of hierarchically structured silica-based nanoparticle could serve as a sustainable drug depot and provides a new avenue for tumor treatment.

Amorphous Calcium Carbonate Cluster Nanospheres in Water-Deficient Organic Solvents.

As the key intermediate phase of crystalline calcium carbonate biominerals, amorphous calcium carbonate (ACC) remains mysterious in its structures because of its long-range disorder and instability. We herein report the synthesis of ACC nanospheres in a water-deficient organic solvent system. The obtained ACC nanospheres are very stable under dry conditions. Cryo-TEM reveals that each nanospheres consists of smaller nanosized clusters. We further demonstrate that these clusters can precipitate on other substrates to form an ultrathin ACC coating, which should be an ACC cluster monolayer. The results demonstrate that the presence of small ACC clusters as the subunits of larger aggregates is inherent to ACC synthesized in water-alcohol system but not induced by polymer additives.

Bio-Inspired Lotus-Fiber-like Spiral Hydrogel Bacterial Cellulose Fibers.

Hydrogel materials with high water content and good biocompatibility are drawing more and more attention now, especially for biomedical use. However, it still remains a challenge to construct hydrogel fibers with enough strength and toughness for practical applications. Herein, we report a bio-inspired lotus-fiber-mimetic spiral structure hydrogel bacterial cellulose fiber with high strength, high toughness, high stretchability, and energy dissipation, named biomimetic hydrogel fiber (BHF). The spiral-like structure endows BHF with excellent stretchability through plastic deformation and local failure, assisted by the breaking-reforming nature of the hydrogen bonding network among cellulose nanofibers. With the high strength, high stretchability, high energy dissipation, high hydrophilicity, porous structure, and excellent biocompatibility, BHF is a promising hydrogel fiber for biomedicine. The outstanding stretchability and energy dissipation of BHF allow it to absorb energy from the tissue deformation around a wound and effectively protect the wound from rupture, which makes BHF an ideal surgical suture.

Tartary buckwheat protein prevented dyslipidemia in high-fat diet-fed mice associated with gut microbiota changes.

As one of low-digestible proteins, tartary buckwheat protein (BWP) revealed a cholesterol-lowering activity. The relationship between the prevention of BWP on dyslipidemia and changes in the numbers of gut microbiota was investigated. The male C57BL/6 mice were separately fed on normal diet, high-fat diet (HFD) with casein, and HFD with BWP extract for 6 weeks. Quantitative PCR assay was applied to quantify the microbiota composition in feces. The levels of plasma total cholesterol (TC) and triglyceride (TG) in the mice fed on HFD with BWP were significantly lower than those on HFD with casein. BWP promoted the growth of Lactobacillus, Bifidobacterium and Enterococcus and inhibited the growth of Escherichia coli in HFD-fed mice. Moreover, Bifidobacterium population was closely related to contents of plasma lipids. Further, BWP significantly decreased the levels of plasma inflammation factors as induced by HFD, including lipopolysaccharide, tumor necrosis factor α and interleukin 6. BWP significantly increased the excretion of total bile acids and short-chain fatty acids in feces. In conlusion, BWP benefited cholesterol metabolism, which could be attributed to regulating composition of gut microbiota.

Two-step biocatalytic process using lipase and whole cell catalysts for biodiesel production from unrefined jatropha oil.

OBJECTIVE: To avoid lipase deactivation by methanol in the enzymatic transesterification process, a two-step biocatalytic process for biodiesel production from unrefined jatropha oil was developed. RESULTS: Unrefined jatropha oil was first hydrolyzed to free fatty acids (FFAs) by the commercial enzyme Candida rugosa lipase. The maximum yield achieved of FFAs 90.3% at 40 °C, water/oil ratio 0.75:1 (v/v), lipase content 2% (w/w) after 8 h reaction. After hydrolysis, the FFAs were separated and converted to biodiesel by using Rhizopus oryzae IFO4697 cells immobilized within biomass support particles as a whole-cell biocatalyst. Molecular sieves (3 Å) were added to the esterification reaction mixture to remove the byproduct water. The maximum fatty acid methyl ester yield reached 88.6% at 35 °C, molar ratio of methanol to FFAs 1.2:1, molecular sieves (3 Å) content 60% (w/w) after 42 h. In addition, both C. rugosa lipase and R. oryzae whole cell catalyst in the process showed excellent reusability, retaining 89 and 79% yields, respectively, even after six batches of reactions. CONCLUSION: This novel process, combining the advantages of enzyme and whole cell catalysts, saved the consumption of commercial enzyme and avoid enzyme deactivation by methanol.

[Quantitative Measurement of Equivalence Ratios of Methane/Air Mixture by Laser-Induced Breakdown Spectroscopy: the Effects of Detector Gated Mode and Laser Wavelength].

Laser-induced breakdown spectroscopy (LIBS) has been increasingly used in combustion diagnostics as a novel spectral analysis method in recent years. The quantitative local equivalence ratio of methane/air mixture is determined by LIBS using different emission intensity ratios of H/O and H/N. The comparison between calibration curves of H656/O777 and H656/N746 is performed in gated mode, which shows that H656/O777 can achieve better prediction accuracy and higher sensitivity. More spectral intensity ratios (H656/O777, H656/N500⁺, H656/N567 and H656/N746) can be used to make calibration measurements in ungated mode and H656/O777 is also tested best among them. The comparison between gated and ungated detection modes shows that gated mode offers better accuracy and precision. In addition, the effects of different laser wavelengths (1064, 532 and 355 nm) on LIBS spectra and calibration curves are investigated with laser focal point size and laser fluence kept constant. The results show that with longer laser wavelength, the peak intensity and SNR of H, O and N lines increase, as well as the slope of calibration curve of H656/O777. Among these three wavelengths, 1064 nm laser is best suited to measure the equivalence ratio of CH4/air mixture by LIBS. The experimental results are explained in terms of plasma electron density and temperature, which have a significant impact on the emission intensity and the partition function of hydrogen and oxygen, respectively.

Biodiesel production in a magnetically-stabilized, fluidized bed reactor with an immobilized lipase in magnetic chitosan microspheres.

Biodiesel production by immobilized Rhizopus oryzae lipase in magnetic chitosan microspheres (MCMs) was carried out using soybean oil and methanol in a magnetically-stabilized, fluidized bed reactor (MSFBR). The maximum content of methyl ester in the reaction mixture reached 91.3 (w/v) at a fluid flow rate of 25 ml/min and a magnetic field intensity of 150 Oe. In addition, the MCMs-immobilized lipase in the reactor showed excellent reusability, retaining 82 % productivity even after six batches, which was much better than that in a conventional fluidized bed reactor. These results suggested that a MSFRB using MCMs-immobilized lipase is a promising method for biodiesel production.