N-Heterocyclic imine-based bis-gallium(I) carbene analogs featuring a four-membered Ga2N2 ring.

A combination of Ga(I) centers as important building blocks and scaffolds containing N-heterocyclic imines gives new insights into low-valent Ga chemistry. In this study, a mixture of LDipNLi (LDip = 1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene), tBuOK, and Cp*Ga (Cp* = pentamethylcyclopentadienyl) in toluene afforded [LDipN-Ga]2 (1) via salt metathesis. X-ray structure analysis of 1 revealed a four-membered Ga2N2 ring, and DFT studies indicated the presence of a lone pair at each Ga center. In addition, compound 1 demonstrated diverse reactivities towards methyl trifluoromethanesulfonate, diphenyl disulfide, 9,10-phenanthrenequinone, and ECl2 (E = Ge or Sn).

Au-modified PtCu nanodendrites as a highly stable and active electrocatalyst.

Direct galvanic replacement of surface Cu with Au3+ in PtCu3 nanodendrites is applied to synthesize an Au-modified PtCu3 nanodendrite catalyst (PtCu3-Au), which shows both superior stability and excellent activity for the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). The PtCu3-Au catalyst only lost 7% of its MOR activity and its ORR half-wave potential decreased 8 mV after 10 000 potential cycles.

Age- and Severity-Associated Humoral Immunity Response in COVID-19 Patients: A Cohort Study from Wuhan, China.

Age has been found to be the single most significant factor in COVID-19 severity and outcome. However, the age-related severity factors of COVID-19 have not been definitively established. In this study, we detected SARS-CoV-2-specific antibody responses and infectious disease-related blood indicators in 2360 sera from 783 COVID-19 patients, with an age range of 1−92 years. In addition, we recorded the individual information and clinical symptoms of the patients. We found that the IgG responses for S1, N, and ORF3a and the IgM for NSP7 were associated with severe COVID-19 at different ages. The IgM responses for the S-protein peptides S1-113 (aa 673−684) and S2-97 (aa 1262−1273) were associated with severe COVID-19 in patients aged <60. Furthermore, we found that the IgM for S1-113 and NSP7 may play a protective role in patients aged <60 and >80, respectively. Regarding clinical parameters, we analyzed the diagnostic ability of five clinical parameters for severe COVID-19 in six age groups and identified three-target panel, glucose, IL-6, myoglobin, IL-6, and NT proBNP as the appropriate diagnostic markers for severe COVID-19 in patients aged <41, 41−50, 51−60, 61−70, 71−80, and >80, respectively. The age-associated severity factors revealed here will facilitate our understanding of COVID-19 immunity and diagnosis, and eventually provide meaningful information for combating the pandemic.

SARS-CoV-2-specific antibody response characteristics in COVID-19 patients of different ages.

Age has been found to be one of the main risk factors for the severity and outcome of COVID-19. However, differences in SARS-CoV-2 specific antibody responses among COVID-19 patients of different age groups remain largely unknown. In this study, we analyzed the IgG/IgM responses to 21 SARS-CoV-2 proteins and 197 peptides that fully cover the spike protein against 731 sera collected from 731 COVID-19 patients aged from 1 to We show that there is no overall difference in SARS-CoV-2 antibody responses in COVID-19 patients in the 4 age groups. By antibody response landscape maps, we find that the IgG response profiles of SARS-CoV-2 proteins are positively correlated with age. The S protein linear epitope map shows that the immunogenicity of the S-protein peptides is related to peptide sequence, disease severity and age of the COVID-19 patients. Furthermore, the enrichment analysis indicates that low S1 IgG responses are enriched in patients aged <50 and high S1 IgG responses are enriched in mild COVID-19 patients aged >60. In addition, high responses of non-structural/accessory proteins are enriched in severe COVID-19 patients aged >70. These results suggest the distinct immune response of IgG/IgM to each SARS-CoV-2 protein in patients of different age, which may facilitate a deeper understanding of the immune responses in COVID-19 patients.

Grafting nanometer metal/oxide interface towards enhanced low-temperature acetylene semi-hydrogenation.

Metal/oxide interface is of fundamental significance to heterogeneous catalysis because the seemingly "inert" oxide support can modulate the morphology, atomic and electronic structures of the metal catalyst through the interface. The interfacial effects are well studied over a bulk oxide support but remain elusive for nanometer-sized systems like clusters, arising from the challenges associated with chemical synthesis and structural elucidation of such hybrid clusters. We hereby demonstrate the essential catalytic roles of a nanometer metal/oxide interface constructed by a hybrid Pd/Bi2O3 cluster ensemble, which is fabricated by a facile stepwise photochemical method. The Pd/Bi2O3 cluster, of which the hybrid structure is elucidated by combined electron microscopy and microanalysis, features a small Pd-Pd coordination number and more importantly a Pd-Bi spatial correlation ascribed to the heterografting between Pd and Bi terminated Bi2O3 clusters. The intra-cluster electron transfer towards Pd across the as-formed nanometer metal/oxide interface significantly weakens the ethylene adsorption without compromising the hydrogen activation. As a result, a 91% selectivity of ethylene and 90% conversion of acetylene can be achieved in a front-end hydrogenation process with a temperature as low as 44 °C.

Mechanical Properties, Curing Mechanism, and Microscopic Experimental Study of Polypropylene Fiber Coordinated Fly Ash Modified Cement-Silty Soil.

Silty soil has the characteristics of low natural moisture content and poor viscosity, and the strength and deformation required for foundation engineering can be satisfied by reinforcing and improving the silt. In order to study the reinforcement and improvement effects of polypropylene (PP) fiber and fly ash (FA) on cement-silty soil, an unconfined compressive strength (UCS) test, scanning electron microscope (SEM) test, and X-ray diffraction (XRD) analysis test were carried out. Cement (mixed amounts are 4%, 8%, 12%, and 16% of dry soil mass) was used as the basic modifier, and PP fiber (mixed amounts are 0%, 0.15%, 0.3%, and 0.45% of dry soil mass) compounded with FA (adding amounts of 0%, 5%, 10%, and 15% of dry soil mass) were used as an external admixture of cement-silty soil to study the mechanical properties, curing mechanism, and microstructure of the modified soil in different ages of 7 d, 14 d, 28 d, and 60 d. The test results show that with the increase in cement and curing age, the UCS of the modified soil increases, and with the increase in the PP fiber and FA, the UCS of the modified soil first increases and then decreases; there is an optimal content of FA and PP fiber, which are 10 and 0.15%, respectively. A large amount of C-S-H and AFt substances are produced inside the modified soil to cover the surface of soil particles or fill in the pores between soil particles, forming a tight spatial network structure and improving the mechanical properties of the cement-soil. The intensity of the diffraction peaks of the mineral components within the modified soils is more influenced by the cement and age, and the effect of FA is weaker. The stress-strain curve of the modified soil is divided into elastic stage, plastic deformation stage, and strain-softening stage, and the specimens in each stage have corresponding deformation characteristics. By analyzing the behavioral characteristics and curing improvement mechanism of modified soil from the duo perspective of macro-mechanical properties and microstructural composition, it can provide some basis for the engineering application of silty soil.

Engineering porous Pd-Cu nanocrystals with tailored three-dimensional catalytic facets for highly efficient formic acid oxidation.

Rational synthesis of bi- or multi-metallic nanomaterials with both dendritic and porous features is appealing yet challenging. Herein, with the cubic Cu2O nanoparticles composed of ultrafine Cu2O nanocrystals as a self-template, a series of Pd-Cu nanocrystals with different morphologies (e.g., aggregates, porous nanodendrites, meshy nanochains and porous nanoboxes) are synthesized through simply regulating the molar ratio of the Pd precursor to the cubic Cu2O, indicating that the galvanic replacement and Kirkendall effect across the alloying process are well controlled. Among the as-developed various Pd-Cu nanocrystals, the porous nanodendrites with both dendritic and hollow features show superior electrocatalytic activity toward formic acid oxidation. Comprehensive characterizations including three-dimensional simulated reconstruction of a single particle and high-resolution transmission electron microscopy reveal that the surface steps, defects, three-dimensional architecture, and the electronic/strain effects between Cu and Pd are responsible for the outstanding catalytic activity and excellent stability of the Pd-Cu porous nanodendrites.

Influence of Reduction Kinetics on the Preparation of Well-Defined Cubic Palladium Nanocrystals.

A facile synthesis strategy has been developed to synthesize palladium nanocubes with tunable size and well-controlled morphology. Through adjusting the dosages of acetate species (KOAc, NH4OAc, and HOAc), the sizes of well-defined Pd nanocubes are tuned. The reduction of Pd precursors, a first-order reaction, is influenceable by acetate species, and a quantitative relationship between cubic width and apparent reduction rate constant, which has been found to be an effective parameter to describe the growth process of Pd nanocubes, has been uncovered. The effect of apparent reduction rate constant on the growth of Pd nanocubes has been discussed, and the growth kinetics of Pd nanocubes is quantitatively depicted.

Variations in nutrient and trace element composition of rice in an organic rice-frog coculture system.

Introducing frogs into paddy fields can control pests and diseases, and organic farming can improve soil fertility and rice growth. The aim of this 2-year field study was compare the yield and elemental composition of rice between an organic farming system including frogs (ORF) and a conventional rice culture system (CR). The grain yields were almost the same in the ORF system and the CR system. The ORF significantly increased the contents of phosphorus (P), ion (Fe), zinc (Zn), molybdenum (Mo) and selenium (Se) in rice grain at one or both years. However, the ORF system decreased the calcium (Ca) content in grice grains, and increased the concentration of cadmium, which is potentially toxic. A principal components analysis showed the main impacts of ORF agro-ecosystem on the rice grain ionome was to increase the concentration of P and trace metal(loid)s. The results showed that the ORF system is an ecologically, friendly strategy to avoid excessive use of chemical fertilizers, herbicides and pesticides without decreasing yields, and to improve the nutritional status of rice by increasing the micronutrient contents. The potential risks of increasing Cd contents in rice grain should be addressed if this cultivation pattern is used in the long term.

Resistin Induces Hypertension and Insulin Resistance in Mice via a TLR4-Dependent Pathway.

Resistin, an adipokine involved in insulin resistance (IR) and diabetes, has recently been reported to play a role in cardiovascular events. However, its effect on blood pressure (BP) and the underlying mechanisms remain unclear. In the present study, we showed that resistin induces hypertension and IR in wild type (WT) mice, but not in tlr4(-/-) mice. Resistin upregulated angiotensinogen (Agt) expression in WT mice, whereas it had no effect on tlr4(-/-) mice, or in mice treated with the angiotensin-converting enzyme inhibitor perindopril. Real-time PCR and chromatin immunoprecipitation further confirmed that resistin activates the renin-angiotensin system (RAS) via the TLR4/P65/Agt pathway. This finding suggested an essential role of resistin in linking IR and hypertension, which may offer a novel target in clinic on the study of the association between diabetes and hypertension.

The multimerization and secretion of adiponectin are regulated by TNF-alpha.

Obesity is often associated with insulin resistance, mild systemic inflammation, and decreased blood adiponectin. However, some adipokines are increased in the adipose tissue of obese individuals, and whether these adipokines are directly related to the reductions in serum adiponectin levels in an autocrine or paracrine manner remains unknown. This study indicates that the tumor necrosis factor alpha (TNF-α) suppresses the multimerization and secretion of adiponectin both in vitro and in vivo. Additionally, TNF-α remarkably suppressed the expression of the ER-resident chaperone proteins ERO1-La, DsbA-L, and ERp44. Overexpression of the transcription factor PPARγ antagonized the suppressive effect of TNF-α on ERO1-La and DsbA-L expressions. Further study revealed that PPARγ enhanced the transcription of ERO1-La and DsbA-L by directly binding to the PPRE element of ERO1-La and DsbA-L promoters. TNF-α treatment decreased this binding activity. Furthermore, TNF-α treatment enhanced the interaction between adiponectin and ERp44. In this study, we show that TNF-α impairs adiponectin multimerization and consequently decreases adiponectin secretion by altering disulfide bond modification in the endoplasmic reticulum. Altered adiponectin multimerization could explain declined adiponectin levels and altered distribution of adiponectin complexes in the plasma of obese insulin-resistant individuals.