Production of the NO photofragment in the desorption of RDX and HMX from surfaces

A promising scheme for the remote detection of nitrate-based explosives, which have low vapor pressure, involves two lasers: the first to desorb, vaporize, and photofragment the explosive molecule and the second to create laser-induced fluorescence in the NO fragment. It is desirable to use for the first a powerful 532 nm frequency-doubled Nd:YAG laser. In this study, we investigate the degree of photofragmentation into NO resulting from the irradiation of the explosives RDX and HMX coated on a variety of surfaces. The desorption step is followed by femtosecond laser ionization and time-of-flight mass spectrometry to reveal the fragments produced in the first step. We find that modest laser power of 532 nm desorbs the explosive and produces adequate amounts of NO.     

Fabrication of a nanocarrier system through self-assembly of plasma protein and its tumor targeting

Human serum albumin (HSA) nanoparticles hold great promise as a nanocarrier system for targeted drug delivery. The objective of this study was to explore the possibility of preparing size controllable albumin nanoparticles using the disulfide bond breaking reagent β-mercaptoethanol (β-ME). The results showed that the protein concentration and temperature had positive effects on the sizes of the albumin nanoparticles, while pH had a negative effect on the rate of nanoparticle formation. The addition of β-ME induced changes in HSA secondary structure and exposed the hydrophobic core of HSA, leading to the formation of nanoparticles. Human serum albumin nanoparticles could be internalized by MCF-7 cells and mainly accumulated in cytoplasm. After injection in tumor bearing mice, the HSA nanoparticles accumulated in tumor tissues, demonstrating the targeting ability of the nanoparticles. Therefore, human serum albumin can be fabricated into nanoparticles by breaking the disulfide bonds and these nanoparticles exhibit high tumor targeting ability. Human serum albumin nanoparticles could be ideal for the targeted delivery of pharmacologically active substances.     

A detailed understanding of the electronic bipolar resistance switching behavior in Pt/TiO2/Pt structure

The detailed mechanism of electronic bipolar resistance switching (BRS) in the Pt/TiO(2)/Pt structure was examined. The conduction mechanism analysis showed that the trap-free and trap-mediated space-charge-limited conduction (SCLC) governs the low and high resistance state of BRS, respectively. The SCLC was confirmed by fitting the current-voltage characteristics of low and high resistance states at various temperatures. The BRS behavior originated from the asymmetric potential barrier for electrons escaping from, and trapping into, the trap sites with respect to the bias polarity. This asymmetric potential barrier was formed at the interface between the trap layer and trap-free layer. The detailed parameters such as trap density, and trap layer and trap-free layer thicknesses in the electronic BRS were evaluated. This showed that the degradation in the switching performance could be understood from the decrease and modified distribution of the trap densities in the trap layer.     

Rheological properties of ABS/wood composites

In this work, the rheological properties of acrylonitrile–butadiene–styrene (ABS)/wood composites were investigated using a capillary rheometer. The present composites with different ratios of ABS and wood were prepared by means of an internal bath mixer. The viscosity of the composites that were pseudo plastics in deformation manner increased with increasing amount of wood particles. In addition, the flow activation energy of the composites increased with increasing amount of wood particles.     

Highly Sensitive and Selective Field‐Effect‐Transistor NonEnzyme Dopamine Sensors Based on Pt/Conducting Polymer Hybrid Nanoparticles

Dopamine (DA), as one of catecholamine family of neurotransmitters, is crucially important in humans owing to various critical effects on biometric system such as brine circuitry, neuronal plasticity, organization of stress responses, and control of cardiovascular and renal organizations. Abnormal level of dopamine in the central nervous system causes several neurological diseases, e.g., schizophrenia, Parkinson's disease, and attention deficit hybperactivity disorder (ADHD)/attention deficit disorder (ADD). In this report, we suggest the fabrication of nonenzyme field effect transistor (FET) sensor composed of immobilized Pt particle decorated conducting‐polymer (3‐carboxylate polypyrrole) nanoparticles (Pt_CPPy) to detect dopamine. The hybrid nanoparticles (NPs) are produced by means of facile chemical reduction of pristine CPPyNP‐contained Pt precursor (PtCl₄) solution. The Pt_CPPys are then immobilized on an amine‐functionalized (–NH₂) interdigitated‐array electrode substrate, through the formation of covalent bonds with amine groups (–CONH). The resulting Pt_CPPy‐based FET sensors exhibit high sensitivity and selectivity toward DA at unprecedentedly low concentrations (100 × 10^?15m ) and among interfering biomolecules, respectively. Additionally, due to the covalent bonding involved in the immobilization process, a longer lifetime is expected for the FET sensor.     

图像雾霾等级评价及去雾技术研究进展

图像去雾技术是对有雾图像进行清晰化处理的一门技术,该技术的任务是去除环境因素对图像质量的影响,从而增强图像的视见度。文章首先对雾霾图像的性质与分类研究进行了论述,并进一步综述了图像去雾技术的国内外研究现状,对直方图均衡化算法,Retinex算法和先验暗通道算法等典型的去雾方法的效果进行评价。总结了各类算法的性能,分析他们各自的优势和不足。最后指出了图像去雾技术的发展趋势和未来展望。     

Microbial Ecology of Watery Kimchi

The biochemistry and microbial ecology of 2 similar types of watery (mul) kimchi, containing sliced and unsliced radish and vegetables (nabak and dongchimi, respectively), were investigated. Samples from kimchi were fermented at 4, 10, and 20 °C were analyzed by plating on differential and selective media, high‐performance liquid chromatography, and high‐throughput DNA sequencing of 16S rDNA. Nabak kimchi showed similar trends as dongchimi, with increasing lactic and acetic acids and decreasing pH for each temperature, but differences in microbiota were apparent. Interestingly, bacteria from the Proteobacterium phylum, including Enterobacteriaceae, decreased more rapidly during fermentation at 4 °C in nabak cabbage fermentations compared with dongchimi. Although changes for Proteobacterium and Enterobacteriaceae populations were similar during fermentation at 10 and 20 °C, the homolactic stage of fermentation did not develop for the 4 and 10 °C samples of both nabak and dongchimi during the experiment. These data show the differences in biochemistry and microbial ecology that can result from preparation method and fermentation conditions of the kimchi, which may impact safety (Enterobacteriaceae populations may include pathogenic bacteria) and quality (homolactic fermentation can be undesirable, if too much acid is produced) of the product. In addition, the data also illustrate the need for improved methods for identifying and differentiating closely related lactic acid bacteria species using high‐throughput sequencing methods.     

A High‐Performance Top‐Gated Graphene Field‐Effect Transistor with Excellent Flexibility Enabled by an iCVD Copolymer Gate Dielectric

A high‐performance top‐gated graphene field‐effect transistor (FET) with excellent mechanical flexibility is demonstrated by implementing a surface‐energy‐engineered copolymer gate dielectric via a solvent‐free process called initiated chemical vapor deposition. The ultrathin, flexible copolymer dielectric is synthesized from two monomers composed of 1,3,5‐trimethyl‐1,3,5‐trivinyl cyclotrisiloxane and 1‐vinylimidazole (VIDZ). The copolymer dielectric enables the graphene device to exhibit excellent dielectric performance and substantially enhanced mechanical flexibility. The p‐doping level of the graphene can be tuned by varying the polar VIDZ fraction in the copolymer dielectric, and the Dirac voltage (V_Dirac) of the graphene FET can thus be systematically controlled. In particular, the V_Dirac approaches neutrality with higher VIDZ concentrations in the copolymer dielectric, which minimizes the carrier scattering and thereby improves the charge transport of the graphene device. As a result, the graphene FET with 20 nm thick copolymer dielectrics exhibits field‐effect hole and electron mobility values of over 7200 and 3800 cm² V^?1 s^?1, respectively, at room temperature. These electrical characteristics remain unchanged even at the 1 mm bending radius, corresponding to a tensile strain of 1.28%. The formed gate stack with the copolymer gate dielectric is further investigated for high‐frequency flexible device applications.     

Effects of Indole-3-Lactic Acid,a Metabolite of Tryptophan,on IL-4 and IL-13-Induced Human Skin-Equivalent Atopic Dermatitis Models

Indole-3-lactic acid (I3LA) is a well-known metabolite involved in tryptophan metabolism. Indole derivatives are involved in the differentiation of immune cells and the synthesis of cytokines via the aryl hydrocarbon receptors for modulating immunity, and the indole derivatives may be involved in allergic responses. I3LA was selected as a candidate substance for the treatment of atopic dermatitis (AD), and its inhibitory effect on AD progression was investigated. Full-thickness human skin equivalents (HSEs) consisting of human-derived cells were generated on microfluidic chips and stimulated with major AD-inducing factors. The induced AD-HSEs were treated with I3LA for 7 days, and this affected the AD-associated genetic biomarkers and increased the expression of the major constituent proteins of the skin barrier. After the treatment for 14 days, the surface became rough and sloughed off, and there was no significant difference between the increased AD-related mRNA expression and the skin barrier protein expression. Therefore, the short-term use of I3LA for approximately one week is considered to be effective in suppressing AD.