Oral short-chain fatty acids administration regulates innate anxiety in adult microbiome-depleted mice.

Anxiety is characterized by feelings of tension and worry even in the absence of threatening stimulus. Pathological condition of anxiety elicits defensive behavior and aversive reaction ultimately impacting individuals and society. The gut microbiota has been shown to contribute to the modulation of anxiety-like behavior in rodents through the gut-brain axis. Several studies observed that germ-free (GF) and the broad spectrum of antibiotic cocktail (ABX)-treated rodents display lowered anxiety-like behavior. We speculate that gut microbial short-chain fatty acids (SCFA) modulate the innate anxiety response. Herein, we administered SCFA in the drinking water in adult mice treated with ABX to deplete the microbiota and tested their anxiety-like behavior. To further augment the innate fear response, we enhanced the aversive stimulus of the anxiety-like behavior tests. Strikingly, we found that the anxiety-like behavior in ABX mice was not altered when enhanced aversive stimulus, while control and ABX mice supplemented with SCFA displayed increased anxiety-like behavior. Vagus nerve serves as a promising signaling pathway in the gut-brain axis. We determined the role of vagus nerve by subdiaphragmatic vagotomy (SDV) in ABX mice supplemented with SCFA. We found that the restored anxiety-like behavior in ABX mice by SCFA was unaffected by SDV. These findings suggest that gut microbiota can regulate anxiety-like behavior through their fermentation products SCFA.

A Facile Way to Form a Graded Halide Layer in Perovskite Solar Cells.

A light harvest layer composed of gradual change from formamidinium lead triiodide (FAPbI3) to methylammonium lead triiodide (MAPbI3) was fabricated using a novel two-step process. That is, a graded halide layer structure without extra processing steps is demonstrated. Conventionally, in the fabrication of MAPbI3 perovskite solar cells (PSCs) using two-step process, PbI2 layer was the first deposited on a mesoporous TiO2 coated substrate. The methylammonium iodide (MAI) solvent was then spin-coated on the surface of PbI2 layer and heated to form the MAPbI3 perovskite layer. Double perovskite layers such as FAPbI3 plus MAPbI3 requires twice of the second step which FAI and MAI should be spin-coated individually. This can be tedious and time consuming. We report here a facile way to form a graded perovskite layer, consisting FAPbI3 to MAPbI3, in a single step. FAI was first added into dimethylformamide (DMF) solution that was used to form PbI2 layer, then MAI solution was dripped on top of the FAI/PbI2 layer. The graded perovskite layer structure (FAPbI3/MAPbI3) in a gradient manner are readily formed, where the structure is confirmed by EDS to be FTO/compact TiO2/mesoporous TiO2/FAPbI3(thin)/MAPbI3/Spiro-OMeTAD/Ag. The Jsc, and Voc of solar cells with this graded perovskite layer are enhanced and the efficiency increases from 11.62% to 14.06%.

Three-dimensional electrodes for dye-sensitized solar cells: synthesis of indium-tin-oxide nanowire arrays and ITO/TiO2 core-shell nanowire arrays by electrophoretic deposition.

Dye-sensitized solar cells (DSSCs) show promise as a cheaper alternative to silicon-based photovoltaics for specialized applications, provided conversion efficiency can be maximized and production costs minimized. This study demonstrates that arrays of nanowires can be formed by wet-chemical methods for use as three-dimensional (3D) electrodes in DSSCs, thereby improving photoelectric conversion efficiency. Two approaches were employed to create the arrays of ITO (indium-tin-oxide) nanowires or arrays of ITO/TiO(2) core-shell nanowires; both methods were based on electrophoretic deposition (EPD) within a polycarbonate template. The 3D electrodes for solar cells were constructed by using a doctor-blade for coating TiO(2) layers onto the ITO or ITO/TiO(2) nanowire arrays. A photoelectric conversion efficiency as high as 4.3% was achieved in the DSSCs made from ITO nanowires; this performance was better than that of ITO/TiO(2) core-shell nanowires or pristine TiO(2) films. Cyclic voltammetry confirmed that the reaction current was significantly enhanced when a 3D ITO-nanowire electrode was used. Better separation of charge carriers and improved charge transport, due to the enlarged interfacial area, are thought to be the major advantages of using 3D nanowire electrodes for the optimization of DSSCs.

Formation of barium strontium titanate thin films via electrophoretic deposition process.

Synthesis of crystalline barium stronium titanate (Ba(0.6)Sr(0.4)TiO(3)) nanoparticles and subsequent formation of thin films have been carried out. The crystalline products were confirmed by X-ray diffractometry. Uniform Ba(0.6)Sr(0.4)TiO(3) thin films were formed by using electrophoretic deposition method (EPD) under a 0.3 to 5 V dc bias for 10 min to 1 h. Ba(0.6)Sr(0.4)TiO(3) nanoparticles having an average crystallite size of 20 to 50 nm, and Ba(0.6)Sr(0.4)TiO(3) thin films with thickness of 150 nm to 4 mum were obtained. A scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to characterize the morphologies of nanoparticles and thin films. The results show that the EPD process route is a rapid, cost-effective alternative for forming Ba(0.6)Sr(0.4)TiO(3) thin films.

Standing [111] gold nanotube to nanorod arrays via template growth.

Standing [111]-oriented crystalline gold nanotube (AuNT) and nanorod (AuNR) arrays using electrochemical deposition through template growth are reported. Segments of single crystal and bamboo-like crystalline AuNR arrays with growing direction of [111], having a diameter of 100-150 nm and a length of 10 µm, standing perpendicular to Ti metal foil substrates, are synthesized. The as-synthesized AuNTs and AuNRs are characterized by powder and five circle x-ray diffractometry, UV-visible molecular absorption spectrometry, field emission scanning electron microscopy, and transmission electron microscopy. AuNRs and AuNTs are formed by starting with a tube and the wall of the tube gets progressively thicker and eventually sealed up to form nanorods. Optical absorption at 548 and 578 nm wavelength for gold nanotubes and nanorods, respectively, caused by the transverse (width) mode is identified.

Screening CYP3A single nucleotide polymorphisms in a Han Chinese population with a genotyping chip.

Human cytochrome P450 (CYP)3A is a major P450 enzyme found in the liver and gastrointestinal tract. It plays an important role in the metabolism of a wide variety of drugs, some endogenous steroids and harmful environmental contaminants. It has been shown that CYP3A alleles encoding enzymes with little or no activity are largely created by single nucleotide polymorphisms (SNPs) in the sequences of these genes. The most prevalent of these SNPs are often of low allelic frequency, and many are specific to certain ethnic groups. Therefore, an accurate determination of their frequency in any given ethnic population requires investigations involving large sample sizes. A genotyping chip with enzyme-colorimetric detection was developed and used for simultaneous analysis of 22 known CYP3A SNPs in 451 Han Chinese subjects. Following multiplex polymerase chain reaction and allele-specific primer extension labeling, an enzymatic colorimetry detection system was employed to visualize genotype patterns on a nylon membrane. With this robust system, accurate discrimination ratios were obtained, and approximately 9,922 genotypes were determined. We found that the major CYP3A SNPs in the Chinese subjects were CYP3A4*4 (allele frequency 2.4%), CYP3A4*5 (0.7%), CYP3A4*18A (2.7%) and CYP3A5*3C (70.2%). Most of the major CYP3A4 SNPs found in other ethnicities were not found in this study. Using these SNPs, 11 haplotypes were identified. Comparison between present and previous studies shows that CYP3A4*4 and CYP3A4*5 alleles were Chinese-specific. The genotyping chip developed in this study is an efficient, economic and accurate system for screening multiple SNPs in a large population. Application of such technology is expected to be less labor intensive and easier to adapt to specific searches when compared with other methodologies.