Quantum-sized carbon dots for bright and colorful photoluminescence

We report that nanoscale carbon particles (carbon dots) upon simple surface passivation are strongly photoluminescent in both solution and the solid state. The luminescence emission of the carbon dots is stable against photobleaching, and there is no blinking effect. These strongly emissive carbon dots may find applications similar to or beyond those of their widely pursued silicon counterparts.     

Ag/Ag3PO4/g-C3N4三元复合光催化剂的制备及其可见光驱动下的光催化活性增强

报道了一种新型Ag/Ag₃PO₄/g-C₃N₄三元复合光催化剂的制备及其半导体界面处的快速载流子分离所引起的光催化活性的显著增强效应。通过X射线衍射,扫描电子显微镜,紫外-可见吸收光谱以及光致发光光谱等就其晶体结构、形貌、组分、光学吸收以及载流子的快速分离行为进行了表征与分析。以罗丹明B作为模型化合物分子,研究发现,所制备的Ag/Ag₃PO₄/g-C₃N₄三元复合光催化剂在可见光照射下表现出比Ag₃PO₄以及Ag₃PO₄/g-C₃N₄二元催化剂更为优异的光催化活性。研究认为,Ag₃PO₄表面尺寸约为40 nm的Ag纳米粒子在可见光下受激所产生的等离子表面共振效应以及Ag₃PO₄与g-C₃N₄界面处所形成的类似异质结结构对所制备的Ag/Ag₃PO₄/g-C₃N₄三元复合光催化剂光催化活性的显著增强起到重要作用。     

Synthesis of Silver Nanoparticles from Extracts of Wild Ginger (Zingiber zerumbet) with Antibacterial Activity against Selective Multidrug Resistant Oral Bacteria

Antibiotic resistance rate is rising worldwide. Silver nanoparticles (AgNPs) are potent for fighting antimicrobial resistance (AMR), independently or synergistically. The purpose of this study was to prepare AgNPs using wild ginger extracts and to evaluate the antibacterial efficacy of these AgNPs against multidrug-resistant (MDR) Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis. AgNPs were synthesized using wild ginger extracts at room temperature through different parameters for optimization, i.e., pH and variable molar concentration. Synthesis of AgNPs was confirmed by UV/visible spectroscopy and further characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy analysis (EDXA), and Fourier-transform infrared spectroscopy (FTIR). Disc and agar well diffusion techniques were utilized to determine the in vitro antibacterial activity of plant extracts and AgNPs. The surface plasmon resonance peaks in absorption spectra for silver suspension showed the absorption maxima in the range of 400–420 nm. Functional biomolecules such as N–H, C–H, O–H, C–O, and C–O–C were present in Zingiber zerumbet (Z. zerumbet) (aqueous and organic extracts) responsible for the AgNP formation characterized by FTIR. The crystalline structure of ZZAE-AgCl-NPs and ZZEE-AgCl-NPs was displayed in the XRD analysis. SEM analysis revealed the surface morphology. The EDXA analysis also confirmed the element of silver. It was revealed that AgNPs were seemingly spherical in morphology. The biosynthesized AgNPs exhibited complete antibacterial activity against the tested MDR bacterial strains. This study indicates that AgNPs of wild ginger extracts exhibit potent antibacterial activity against MDR bacterial strains.     

Global existence and energy decay for a damped quasi-linear wave equation

In this paper we prove the global existence and study decay property of the solutions to the initial boundary value problem for the quasi-linear wave equation with a dissipative term without the smallness of the initial data. © 1998 B. G. Teubner Stuttgart—John Wiley & Sons, Ltd.     

Formation and dissolution of phase-separated structures in ultrathin blend films

The phase separation of ultrathin polymer blend films of deuterated poly(styrene)/poly(vinylmethylether) leads to a variety of film morphologies, depending on polymer composition. Phase-separation measurements are made at a constant temperature difference from the critical temperature, leading to a bicontinuous spinodal decomposition pattern for near-critical blend compositions and to “mounds” and “holes” for PVME-rich and dPS-rich off-critical mixtures, respectively. Reverse temperature jumps of the phase-separated blend films into the one-phase region result in dissolution of the undulating surface patterns, confirming the phase-separation origin of the film patterns. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 191–200, 1998     

A new stochastic Petri net model and its applications to logistics systems

This is a summary of the author’s PhD thesis supervised by Lionel Amodeo and Hoaxun Chen and defended on 29 November 2005 at the Université de Technologie de Troyes (France). The thesis is written in French and is available from the author upon request. This work deals with a new stochastic Petri net model and its applications for modeling and studying logistics systems and more generally discrete event dynamic systems.      

A semantical proof of the strong normalization theorem for full propositional classical natural deduction

We give in this paper a short semantical proof of the strong normalization for full propositional classical natural deduction. This proof is an adaptation of reducibility candidates introduced by J.-Y. Girard and simplified to the classical case by M. Parigot.     

A study of metals supported on active carbon with a temperature programmed reduction (TPR) technique

The influence of active carbon as support on the reducibility of supported metals (Ni, Cu, Cd, Zn) has been studied by means of a temperature programmed reduction (TPR) technique. The TPR profiles indicate that active carbon behaves as a dispersion agent and the supported metal is dispersed in a disordered phase rather than as a stoichiometric compound. The hydrogen consumed in the reduction indicates that the metal residues are present in monovalent and divalent forms. High-temperature reduction peaks were also observed and are explained on the basis of metal-surface interactions and the porosity of the active carbon. Nitrogen adsorption reveals that the active carbon porosity decreases due to progressive closure of the pores when metals are supported on the surface of active carbon.     

Metal-free synthesis of azacalix[4]arenes

The facile preparation of N(H)-bridged azacalix[4]arenes has been achieved by stepwise nucleophilic aromatic substitutions assisted by hydrogen bonding interactions. The synthesis is uncatalyzed and affords previously unknown tetranitroazacalix[4]arenes.     

Phospholipids in liquid chromatography/mass spectrometry bioanalysis: comparison of three tandem mass spectrometric techniques for monitoring plasma phospholipids,the effect of mobile phase composition on phospholipids elution and the association of phospholipids with matrix effects

Because plasma phospholipids may cause matrix effects in bioanalytical liquid chromatography/tandem mass spectrometry (LC/MS/MS) methods, it is important to establish optimal mass spectrometric techniques to monitor the fate of phospholipids during method development and application. We evaluated three MS/MS techniques to monitor phospholipids using positive and negative electrospray ionization (ESI). The first technique is based on using positive precursor ion scan of m/z 184, positive neutral loss scan of 141 Da and negative precursor ion scan of m/z 153. The second technique is based on using class‐specific positive and negative selected reaction monitoring (SRM) transitions to monitor class‐representative phospholipids. The third technique, previously reported, utilizes in‐source collision‐induced dissociation (CID)‐based positive SRM of m/z 184 → 184. We recommend the all‐inclusive technique 1 for use in qualitative assessment of all classes of phospholipids and technique 2 for use in quantitative assessment of class‐representative phospholipids. Secondly, we evaluated the elution behaviors of the plasma phospholipids under different reversed‐phase mobile phase conditions. The phospholipid‐eluting strength of a mobile phase was mainly dependent on the type and amount (%) of the organic eluent and the strength increased in the order of methanol, acetonitrile and isopropyl alcohol. Under the commonly used gradient and isocratic elution schemes in LC/MS/MS bioanalysis, not all the phospholipids are eluted off the column. Thirdly, we investigated the association between phospholipids and matrix effects in positive and negative ESI using basic, acidic and neutral analytes. While the phospholipids caused matrix effects in both positive and negative ESI, the extent of ionization suppression was analyte‐dependent and was inversely related to the retention factor and broadness of the phospholipids peaks. The lysophospholipids which normally elute earlier in reversed‐phase chromatography are more likely to cause matrix effects compared to the later‐eluting phospholipids in spite of the larger concentrations of the latter in plasma. Copyright © 2009 John Wiley & Sons, Ltd.