Nanoparticle-Modified Electrode with Size- and Shape-Dependent Electrocatalytic Activities

The size, shape, composition, and crystalline structures of noble metal nanoparticles are the key parameters in determining their electrocatalytic performance. Here, we report on a robust chemical-tethering approach to immobilizing gold nanoparticles onto transparent indium tin oxide (ITO) glass electrode surfaces to systematically investigate their size- and shape-dependent electrocatalysis toward a methanol oxidation reaction (MOR) and an oxygen reduction reaction (ORR). Monodisperse 20 nm nanospheres (NS20s), 45 nm nanospheres (NS45s), and 20 nm × 63 nm nanorods (NRs), which could be chemically tethered to ITO-surface-forming submonolayers without any aggregation, were synthesized. These nanoparticle-modified ITO electrodes exhibited strong electrocatalytic activities toward MOR and ORR, but their mass current densities were highly dependent on the particle sizes and shapes. For particles with similar shapes, the size determined the mass current densities: smaller particle sizes led to greater catalytic current densities per unit mass because of the greater surface-to-volume ratio (NS20s > NS45s). For particles with comparable sizes, the shape or crystalline structure governed the selectivity of the electrocatalytic reactions: NS45 exhibited a higher mass current density in MOR than did NRs because its dominant (111) facets were exposed, whereas NRs exhibited a higher mass current density in ORR because its dominant (100) facets were exposed

Manufacturable Conducting Rubber Ambers and Stretchable Conductors from Copper Nanowire Aerogel Monoliths

We report on a low-cost, simple yet efficient strategy to fabricate ultralightweight aerogel monoliths and conducting rubber ambers from copper nanowires (CuNWs). A trace amount of poly(vinyl alcohol) (PVA) substantially improved the mechanical robustness and elasticity of the CuNW aerogel while maintaining a high electrical conductivity. The resistivity was highly responsive to strains manifesting two distinct domains, and both followed a power law function consistent with pressure-controlled percolation theory. However, the values of the exponents were much less than the predicted value for 3D systems, which may be due to highly porous structures. Remarkably, the CuNW-PVA aerogels could be further embedded into PDMS resin, forming conducting rubber ambers. The ambers could be further manufactured simply by cutting into any arbitrary 1D, 2D, and 3D shapes, which were all intrinsically conductive without the need of external prewiring, a condition required in the previous aerogel-based conductors. The outstanding electrical conductivity in conjunction with high mechanical compliance enabled prototypes of the elastic piezoresistivity switches and stretchable conductors

Late Ordovician high-Mg adakitic andesite in the western South China block: evidence of oceanic subduction

<p>The Early Palaeozoic was an important period in the geologic evolution of the South China block (SCB), marking the intracontinental orogen in the Wuyi-Yunkai region. One salient feature of the western SCB is the absence of Early Palaeozoic oceanic subduction-related magmatism. Here, we report the first known occurrence of Late Ordovician andesites from the Shimian area, western SCB. Zircon SHRIMP U–Pb dating reveals that the andesites formed at ca. 451 Ma. They have geochemical features of high-Mg adakitic andesite (HMAA) and are characterized by low K₂O (1.09–2.24 wt.%) and Th (2.50–5.65 ppm) and high MgO (4.02–6.91 wt.%) and Mg# (56–71). Furthermore, their zircon grains display positive <i>ε</i>_Hf(<i>t</i>) (+11.4 to +19.6) and low <i>δ</i>¹⁸O (4.72–6.20‰) values. The andesites are interpreted to have been derived from partial melting of a peridotitic mantle wedge in an oceanic subduction setting and subsequent fractional crystallization. Integrating previous studies of the Qinling-Dabie orogenic belt with the data presented in this contribution, we suggest that the SCB was probably involved in the Early Palaeozoic Andean-type orogeny along the Gondwanan proto-Tethyan margin.</p

Data_Sheet_1_Geographical and temporal distribution of multidrug-resistant Salmonella Infantis in Europe and the Americas.zip

Recently emerged S. Infantis strains carrying resistance to several commonly used antimicrobials have been reported from different parts of the globe, causing human cases of salmonellosis and with occurrence reported predominantly in broiler chickens. Here, we performed phylogenetic and genetic clustering analyses to describe the population structure of 417 S. Infantis originating from multiple European countries and the Americas collected between 1985 and 2019. Of these, 171 were collected from 56 distinct premises located in England and Wales (E/W) between 2009 and 2019, including isolates linked to incursions of multidrug-resistant (MDR) strains from Europe associated with imported poultry meat. The analysis facilitated the comparison of isolates from different E/W sources with isolates originating from other countries. There was a high degree of congruency between the outputs of different types of population structure analyses revealing that the E/W and central European (Germany, Hungary, and Poland) isolates formed several disparate groups, which were distinct from the cluster relating to the United States (USA) and Ecuador/Peru, but that isolates from Brazil were closely related to the E/W and the central European isolates. Nearly half of the analysed strains/genomes (194/417) harboured the IncFIB(pN55391) replicon typical of the “parasitic” pESI-like megaplasmid found in diverse strains of S. Infantis. The isolates that contained the IncFIB(pN55391) replicon clustered together, despite originating from different parts of the globe. This outcome was corroborated by the time-measured phylogeny, which indicated that the initial acquisition of IncFIB(pN55391) likely occurred in Europe in the late 1980s, with a single introduction of IncFIB(pN55391)-carrying S. Infantis to the Americas several years later. Most of the antimicrobial resistance (AMR) genes were identified in isolates that harboured one or more different plasmids, but based on the short-read assemblies, only a minority of the resistance genes found in these isolates were identified as being associated with the detected plasmids, whereas the hybrid assemblies comprising the short and long reads demonstrated that the majority of the identified AMR genes were associated with IncFIB(pN55391) and other detected plasmid replicon types. This finding underlies the importance of applying appropriate methodologies to investigate associations of AMR genes with bacterial plasmids.</p

A comparative study of the characterization of miR-155 in knockout mice

<div><p>miR-155 is one of the most important miRNAs and plays a very important role in numerous biological processes. However, few studies have characterized this miRNA in mice under normal physiological conditions. We aimed to characterize miR-155 in vivo by using a comparative analysis. In our study, we compared miR-155 knockout (KO) mice with C57BL/6 wild type (WT) mice in order to characterize miR-155 in mice under normal physiological conditions using many evaluation methods, including a reproductive performance analysis, growth curve, ultrasonic estimation, haematological examination, and histopathological analysis. These analyses showed no significant differences between groups in the main evaluation indices. The growth and development were nearly normal for all mice and did not differ between the control and model groups. Using a comparative analysis and a summary of related studies published in recent years, we found that miR-155 was not essential for normal physiological processes in 8-week-old mice. miR-155 deficiency did not affect the development and growth of naturally ageing mice during the 42 days after birth. Thus, studying the complex biological functions of miR-155 requires the further use of KO mouse models.</p></div

Constraining the deep dynamic process beneath the Bangong-Nujiang suture zone: A case study from the early cretaceous trachytic rocks

The geodynamic processes that occurred beneath the Bangong – Nujiang suture zone during the evolution of the Indus – Yarlung Neo-Tethys and Bangong – Nujiang Meso-Tethys are unclear. We conducted a study of Early Cretaceous andesitic rocks from the Nyima area, north – central Tibet, to investigate these processes. The studied rocks have zircon U – Pb ages of 110–104 Ma and negative to positive εHf(t) values (−12.1 to+10.3). These rocks have affinities with trachytes, and have high total alkali contents and Na2O/K2O ratios (5–125). They also have high Sr (281–1409 ppm), Y (21.0–28.5 ppm), and Yb (2.00–2.65 ppm) contents, and exhibit depletions in Nb, Ta, and Ti. Such features indicate these rocks are not adakites, but are similar to typical arc rocks. The geochemical and isotopic data suggest the studied rocks were formed by partial melting of amphibolite-facies oceanic lithosphere, with the addition of enriched sedimentary materials. Based on the regional crustal evolution, we suggest that the Nyima andesitic rocks formed by melting of Bangong – Nujiang oceanic lithosphere. As such, the Early Cretaceous igneous rocks along the central Bangong – Nujiang suture zone were not associated with northward subduction in the Indus – Yarlung Neo-Tethys.</p

Summary of the histological scores.

<p>Summary of the histological scores.</p

Nebulized anionic guanidinylated O-carboxymethyl chitosan/N-2-hydroxypropyltimehyl ammonium chloride chitosan nanoparticles for siRNA pulmonary delivery: preparation, characterization and <i>in vitro</i> evaluation

<p>This study developed a pH-sensitive anionic system composed of guanidinylated O-carboxymethyl chitosan (GOCMCS) and N-2-hydroxypropyltimehyl ammonium chloride chitosan (N-2-HACC) for efficient siRNA delivery to the lungs following nebulization. About 16.8% of guanidine groups were incorporated into O-carboxymethyl chitosan (OCMCS) with the aid of O-methylisourea. Gel electrophoresis images demonstrated that siRNA was successfully encapsulated in nanoparticles ranging from 150 to 180 nm with zeta potential of about −17 mV. The nanoparticles containing GOCMCS existed superior transfection performance compared with their amino-based analogs. The evaluation <i>in vitro</i> revealed that nanoparticles were internalized into A549 cells by energy-dependent endocytosis, then achieved endosomal escape by direct transmembrane penetration of guanidine moieties as well as swelling behavior of nanoparticles due to the pH sensitivity of GOCMCS. The mRNA level of survivin gene was down-regulated to 6.9% using GOCMCS/N-2-HACC/siSurvivin NPs. The survivin siRNA mediated by nanoparticles caused 30% of cell growth inhibition and induced 19.45% of cell apoptosis, which was comparable to Lipofectamin2000. After nebulization of siRNA-loaded nanoparticles, the stability of siRNA was maintained and fine particle fractions were detected by two-stage impinger that accounted for more than 60%. These results suggested that GOCMCS/N-2-HACC nanoparticles possessed potential as safe and efficient carrier for siRNA pulmonary delivery.</p

Summary of reproductive performance.

<p>Summary of reproductive performance.</p

Representative photomicrographs of the vital organs.

<p>Sections fixed with paraformaldehyde were stained with haematoxylin and eosin (HE). Slides were observed with a light microscope (200×), and representative photomicrographs of sections of (A and B) lungs, (C and D) hearts, (E and F) livers, and (G and H) spleens from both the model and control groups are shown. No significant differences were observed for any of the evaluation indices. (Mice were 8 weeks old.).</p