Colloidal woodpile structure: three-dimensional photonic crystal with a dual periodicity

With planar photolithography and self-assembly techniques, multilayer colloidal crystals with a woodpile structure were fabricated. They represent a new kind of photonic crystals, that is, three-dimensional (3D) photonic crystals with a dual periodicity; one comes from the face-centered cubic (fcc) structure within the colloidal crystal strips and the other one results from the periodic arrangement of the colloidal crystal strips.     

Large area impingement spray cooling from multiple normal and inclined spray nozzles

An inclined spray chamber with four multiple nozzles to cool a 1 kW 6U electronic test card has been designed and tested in this study. The multiple inclined sprays can cover the same heated surface area as that with the multiple normal sprays but halve the volume of the spray chamber. The spray cooling system used R134a as a working fluid in a modified refrigeration cycle. It is observed that increasing mass flow rate and pressure drop across the nozzles improved the heat transfer coefficient with a maximum enhancement of 117 %, and reduced the maximum temperature difference at the heated surface from 13.8 to 8.4 °C in the inclined spray chamber with a heat flux of 5.25 W/cm², while the heat transfer coefficient of the normal spray increased with a maximum enhancement of 215 % and the maximum temperature difference decreased from 10.8 to 5.4 °C under similar operating conditions. We conclude that the multiple inclined sprays could produce a higher heat transfer coefficient but with an increase in non-uniformity of the surface temperature compared with the multiple normal sprays.     

Enhancement of GaAs/InGaAs quantum well emission by disordered gold nanoparticle arrays

Coupling effect of surface plasmon (SP) with InGaAs/GaAs QW emission is demonstrated experimentally. The SP resonance is generated by disordered arrays of Au nanodisks on the InGaAs/GaAs QW surface. More than twofold enhancement in QW PL is observed. Theoretical simulations also indicated that the disordered arrays of Au structures enlarged the cone angle for which light can be radiated out. The larger angle enhances the PL intensity.     

Copper-catalyzed aerobic spirocyclization of biaryl-N-H-imines via 1,4-aminooxygenation of benzene rings

A synthetic method of azaspirocyclohexadienones has been developed through copper-catalyzed aerobic spirocyclization of biaryl-N-H-imines prepared by the reaction of biarylcarbonitriles and Grignard reagents.     

The Impact of Long-Term In Vitro Expansion on the Senescence-Associated Markers of Human Adipose-Derived Stem Cells

Human adipose-derived stem cells (ASCs) have generated a great deal of excitement in regenerative medicine. However, their safety and efficacy issue remain a major concern especially after long-term in vitro expansion. The aim of this study was to investigate the fundamental changes of ASCs in long-term culture by studying the morphological feature, growth kinetic, surface marker expressions, expression level of the senescence-associated genes, cell cycle distribution and ß-galactosidase activity. Human ASCs were harvested from lipoaspirate obtained from 6 patients. All the parameters mentioned above were measured at P5, P10, P15 and P20. Data were subjected to one-way analysis of variance with a Tukey post hoc test to determine significance difference (P?相似文献   

Introducing dichlorocarbene in graphene

The functionalization of graphene with dichlorocarbene has been successfully attained based on a conventional method for the generation of dichlorocarbenes. The obtained material was fully characterized using high resolution X-ray photoelectron spectroscopy, transmission electron microscopy, infrared and Raman spectroscopies.     

Graphenes Prepared by Hummers,Staudenmaier and Hofmann Methods for Analysis of TNT‐Based Nitroaromatic Explosives in Seawater

The detection of TNT and related nitroaromatic compounds in seawater is of great interest. Electrochemical techniques can be applied for detection purposes since nitroaromatic compounds contain easily reducible nitro groups. In this study, we investigate the performance of thermally reduced graphenes prepared by three different oxidative methods: Hummers, Staudenmaier and Hofmann methods with consequent thermal exfoliation. The Hofmann method‐based graphene was found to exhibit the highest sensitivity in detecting TNT electrochemically. Extended study on the detection of TNT in seawater using the graphene material provided significant improvements in the detection sensitivity. These findings will have profound impacts on the detection of nitroaromatic explosives in seawater.     

Effect of C∶N molar ratio on monomer composition of polyhdroxyalk anoates produced by Pseudomonas mendocina 0806 and Pseudomonas pseudoalkaligenus YS1

Polyhydroxyalkanoates (PHAs) are biodegradable polymers produced by bacteria. In this study, the effect of C∶N molar ratio on the monomer composition of PHAs was investigated, including medium chain length PHA produced by Pseudomonas mendocina 0806 and PHA blends consisting of monomers of 3-hydroxybutyrate and medium chain length hydroxyalkan⇘te produced by Pseudomonas pseudoalkaligenus YS1. It was observed that there were some fixed ranges of C∶N molar ratio that affect the monomer composition of PHA independently of the substrate. For strain 0806, the ranges were C∶N <20, 20<C∶N<200, and C∶N>200. The monomer composition was constant among these ranges when using glucose and octanoate as the sole substrate. For strain YS1, the ranges were C∶N<20, 20<C∶N<45, and C∶N>45. These results are useful for controlling monomer composition in PHA production.     

Detection of Bacterial Neutral Ceramidase in Diabetic Foot Ulcers with an Optimized Substrate and Chemoenzymatic Probes

Ceramidases (CDases) are important in controlling skin barrier integrity by regulating ceramide composition and affording downstream signal molecules. While the functions of epidermal CDases are known, roles of neutral CDases secreted by skin-residing microbes are undefined. Here, we developed a one-step fluorogenic substrate, S-B , for specific detection of bacterial CDase activity and inhibitor screening. We identified a non-hydrolyzable substrate mimic, C6 , as the best hit. Based on C6 , we designed a photoaffinity probe, JX-1 , which efficiently detects bacterial CDases. Using JX-1 , we identified endogenous low-abundance PaCDase in a P. aeruginosa monoculture and in a mixed skin bacteria culture. Harnessing both S-B and JX-1 , we found that CDase activity positively correlates with the relative abundance of P. aeruginosa and is negatively associated with wound area reduction in clinical diabetic foot ulcer patient samples. Overall, our study demonstrates that bacterial CDases are important regulators of skin ceramides and potentially play a role in wound healing.