Amplified Interfacial Effect in an Atomically Dispersed RuOx -on-Pd 2D Inverse Nanocatalyst for High-Performance Oxygen Reduction.

Atomically dispersed oxide-on-metal inverse nanocatalysts provide a blueprint to amplify the strong oxide-metal interactions for heterocatalysis but remain a grand challenge in fabrication. Here we report a 2D inverse nanocatalyst, RuOx -on-Pd nanosheets, by in situ creating atomically dispersed RuOx /Pd interfaces densely on ultrathin Pd nanosheets via a one-pot synthesis. The product displays unexpected performance toward the oxygen reduction reaction (ORR) in alkaline medium, which represents 8.0- and 22.4-fold enhancement in mass activity compared to the state-of-the-art Pt/C and Pd/C catalysts, respectively, showcasing an excellent Pt-alternative cathode electrocatalyst for fuel cells and metal-air batteries. Density functional theory calculations validate that the RuOx /Pd interface can accumulate partial charge from the 2D Pd host and subtly change the adsorption configuration of O2 to facilitate the O-O bond cleavage. Meanwhile, the d-band center of Pd nanosubstrates is effectively downshifted, realizing weakened oxygen binding strength.

Structure-intensified PtCoRh spiral nanowires as highly active and durable electrocatalysts for methanol oxidation.

Platinum (Pt)-based nanocatalysts with a high density of surface atomic steps hold great prospects in electrocatalysis. However, the structural instability under harsh redox conditions is still a rigorous challenge. Here, we demonstrate that ternary PtCoRh alloyed spiral nanowires (SNWs), which have the advantages of one-dimensional nanowires, alloy synergy, surface atomic steps, and anti-corrosive Rh incorporation, can serve as active and robust MOR electrocatalysts in acidic media. The results showed that the Pt77Co11Rh12 SNWs delivered the highest mass activity (1.48 A mg-1) and specific activity (4.76 mA cm-2), as well as the best durability in the long-term MOR test, compared with the Pt85Co10Rh5 and Pt85Co15 SNWs and Pt black. Further inspections of the morphology, composition, and electronic structure revealed that the incorporated Rh atoms not only stabilized the highly rugged SNWs and the easily leaching Co atoms but also delicately tuned the electron transfer among the three metallic elements, leading to the enhancement of MOR activity, structural stability and anti-CO-poisoning ability. Our work provides a rational strategy for the development of highly efficient and durable alcohol oxidation electrocatalysts.

Inhibitory Effects of Apigenin on Tumor Carcinogenesis by Altering the Gut Microbiota.

The flavonoid apigenin is common to many plants. Although the responsible mechanisms have yet to be elucidated, apigenin demonstrates tumor suppression in vitro and in vivo. This study uses an azoxymethane (AOM)/dextran sodium sulfate- (DSS-) induced colon cancer mouse model to investigate apigenin's potential mechanism of action exerted through its effects upon gut microbiota. The size and quantity of tumors were reduced significantly in the apigenin treatment group. Using 16S rRNA high-throughput sequencing of fecal samples, the composition of gut microbiota was significantly affected by apigenin. Further experiments in which gut microbiota were reduced and feces were transplanted provided further evidence of apigenin-modulated gut microbiota exerting antitumor effects. Apigenin was unable to reduce the number or size of tumors when gut microbiota were depleted. Moreover, tumor inhibition effects were initiated following the transplant of feces from mice treated with apigenin. Our findings suggest that the effect of apigenin on the composition of gut microbiota can suppress tumors.

Kinetically Manipulating the Nucleus Attachment to Create Atypical Defective Rh-Pt Alloyed Nanostructures as Active Electrocatalysts.

Defective metal nanostructures have attracted great attention due to the striking catalytic behavior of the defect sites. Atypical metal nanocrystals generated from attached nuclei can accommodate abundant grain boundaries (GBs) and twin boundaries (TBs). However, the understanding of their growth-mechanism and precisely synthetic control over such defective nanocrystals are still scarce. Herein, using the Rh-Pt nanoalloy as a model system, we systematically demonstrate that a prudent control of the reaction kinetics can manipulate the metal nucleation and nucleus attachment to create atypical nanocrystals, including small isolated nanoparticles (NPs), defect-rich wavy nanowires (WNWs), and {100} facet-bounded spliced nanocubes (SNCs). In the ethanol oxidation electrocatalysis, the Rh47 Pt53 WNWs featured with abundant TBs and GBs show the greatest mass activity (0.655 A ⋅ mg-1 Pt , 2.9 times to the commercial Pt/C) and durability. Our work captures the core of reaction kinetics on regulating the nucleus attachment and enables the rational control over the nanocrystal morphology and defect.

[Value of optimization of bedside Gram staining of sputum smear in the early diagnosis and treatment of ventilator-associated pneumonia].

OBJECTIVE: To investigate the significance of optimization of bedside Gram staining of sputum smear in the early diagnosis and antimicrobial treatment for ventilator-associated pneumonia (VAP) patients. METHODS: The data of patients with VAP undergoing mechanical ventilation over 48 hours in the Department of Critical Care Medicine of Tianjin Fourth Central Hospital from June 2009 to June 2014 were analyzed. The patients were divided into two groups according to whether or not bedside Gram staining of sputum smear was used or not. The sputum samples from lower respiratory tract of all VAP patients were collected daily with tracheal catheter. In empirical examination group (from June 2009 to December 2011, n=43), the patients received antibiotics at the time of onset of VAP, selection of antibiotics depended on the information of bacterial epidemiology of the intensive care unit (ICU), and also existence of high risk factors of multi-drug resistant bacteria. In target treatment group (from January 2012 to June 2014, n=43), the patients received antibiotics according to the results of bedside instant sputum smear examination and empirical antibiotic regime. The correlation between the results of sputum smear examination and culture result was analyzed. The levels of body temperature, white blood cell (WBC) count, procalcitonin (PCT) level,and high sensitivity C- reactive protein (hs-CRP) were measured on the 1st day and 3rd day. The length of antibiotics treatment, duration of mechanical ventilation, and the time of ICU stay were recorded for both groups. RESULTS: There were 512 qualified sputum specimens for culture, from which 336 pathogens were found, and 358 strains of pathogenic bacteria were found from microscopic examination of 512 qualified sputum smear. The coincidence rate of results of bedside examination of sputum smear and that of sputum culture was 78.32%(401/512). The diagnostic acumen of the former was 85.42% (287/336), specificity was 64.77% (114/176), positive predictive value was 80.17% (287/358), and negative predictive value was 74.03% (114/154). On the 1st day, no statistical differences in infection index between the two groups could be found, but on the 3rd day, the results were significantly improved in both groups. Compared with the empirical treatment group, the body temperature, WBC, PCT and hs-CRP in the target treatment group were significantly lower [body temperature (centigrade): 36.83 ± 0.69 vs. 37.64 ± 0.71, WBC (× 109/L): 7.91 ± 2.75 vs. 9.66 ± 3.39, PCT (µg/L): 7.14 ± 3.89 vs. 10.14 ± 4.32, hs-CRP (mg/L): 12.24 ± 6.28 vs. 15.54 ± 5.94, P<0.05 or P<0.01]. Compared with the empirical treatment group, the time of antibiotics use(days: 6.00 ± 2.55 vs. 9.20 ± 3.46), the duration of mechanical ventilation (days: 5.00 ± 1.73 vs. 7.00 ± 1.94), and the length of ICU stay (days: 7.43 ± 1.72 vs. 12.57 ± 4.16) were significantly shortened (P<0.05 or P<0.01). CONCLUSIONS: The results of bedside sputum examination and sputum culture showed a good correlation, and the former is helpful in early diagnosis and treatment of VAP. The result of high quality sputum smear in significant in guiding the first choice of antibiotics, reduce the time of antibiotic use, shorten the duration of mechanical ventilation and the length of ICU stay, and improve the outcome of the patients.

Identification of candidate olfactory genes in Chilo suppressalis by antennal transcriptome analysis.

Antennal olfaction, which is extremely important for insect survival, mediates key behaviors such as host preference, mate choice, and oviposition site selection. In insects, odor detection is mediated by multiple proteins in the antenna, especially the odorant receptors (ORs) and ionotropic receptors (IRs), which ensure the specificity of the olfactory sensory neuron responses. In this study, we identified the olfactory gene repertoire of the rice stem borer, Chilo suppressalis, an economically important agricultural pest, which inflicts great damage to the rice yield in south and east part of Asia, especially in Southern China. By Illumina sequencing of male and female antennal transcriptomes, we identified 47 odorant receptors, 20 ionotropic receptors, 26 odorant binding proteins, 21 chemosensory proteins and 2 sensory neuron membrane proteins. Our findings make it possible for future research of the olfactory system of C. suppressalis at the molecular level.

Effects of granulation on organic acid metabolism and its relation to mineral elements in Citrus grandis juice sacs.

We investigated the effects of granulation on organic acid metabolism and its relation to mineral elements in 'Guanximiyou' pummelo (Citrus grandis) juice sacs. Granulated juice sacs had decreased concentrations of citrate and isocitrate, thus lowering juice sac acidity. By contrast, malate concentration was higher in granulated juice sacs than in normal ones. The reduction in citrate concentration might be caused by increased degradation, as indicated by enhanced aconitase activity, whilst the increase in malate concentration might be caused by increased biosynthesis, as indicated by enhanced phosphoenolpyruvate carboxylase (PEPC). Real time quantitative reverse transcription PCR (qRT-PCR) analysis showed that the activities of most acid-metabolizing enzymes were regulated at the transcriptional level, whilst post-translational modifications might influence the PEPC activity. Granulation led to increased accumulation of mineral elements (especially phosphorus, magnesium, sulphur, zinc and copper) in juice sacs, which might be involved in the incidence of granulation in pummelo fruits.

[Dendrobium officinale stereoscopic cultivation method].

The study is aimed to make the most of available space of Dendrobium officinale cultivation facility, reveal the yield and functional components variation of stereoscopic cultivated D. officinale, and improve quality, yield and efficiency. The agronomic traits and yield variation of stereoscopic cultivated D. officinale were studied by operating field experiment. The content of polysaccharide and extractum were determined by using phenol-sulfuric acid method and 2010 edition of "Chinese Pharmacopoeia" Appendix X A. The results showed that the land utilization of stereoscopic cultivated D. officinale increased 2.74 times, the stems, leaves and their total fresh or dry weight in unit area of stereoscopic cultivated D. officinale were all heavier than those of the ground cultivated ones. There was no significant difference in polysaccharide content between stereoscopic cultivation and ground cultivation. But the extractum content and total content of polysaccharide and extractum were significantly higher than those of the ground cultivated ones. In additional, the polysaccharide content and total content of polysaccharide and extractum from the top two levels of stereoscopic culture matrix were significantly higher than that of the ones from the other levels and ground cultivation. Steroscopic cultivation can effectively improves the utilization of space and yield, while the total content of polysaccharides and extractum were significantly higher than that of the ground cultivated ones. The significant difference in Dendrobium polysaccharides among the plants from different height of stereo- scopic culture matrix may be associated with light factor.