Behavior study of polyvinyl alcohol aqueous solution in presence of short chain micelle-forming polyols

Interactions in aqueous solution between polyvinyl alcohol (PVA) and various short chain nonionic polyols surfactants having six to nine carbon atoms and two to three hydroxyl groups are investigated using tensiometry, viscosity, and dynamic laser light scattering techniques. Despite the fact that weak interactions are noticed, they begin to occur at surfactant concentrations far lower than the Critical Micellar Concentration. Partition coefficients of the surfactants between water and the PVA macromolecules are determined, and the contributions of the surfactant alkyl chain length on one hand and of the hydroxyl groups on the other hand to the PVA interactions with monomer surfactants are discussed in terms of thermodynamic contributions.     

Two New Diterpenes from the Twigs of Cinnamomum cassia

Two new diterpene derivatives named cinnacasol ( 1 ) and cinnacaside ( 2 ) were isolated from the MeOH extract of the twigs of Cinnamomum cassia Blume . Their structures were identified based on physicochemical properties and spectroscopic‐data analyses such as IR, HR‐MS, and 1D‐ and 2D‐NMR, and by comparison with published values.     

Extraction of uranium from simulated ore by the supercritical carbon dioxide fluid extraction method with nitric acid-TBP complex.

The supercritical fluid extraction (SFE) method using CO(2) as a medium with an extractant of HNO(3)-tri-n-butyl phosphate (TBP) complex was applied to extract uranium from several uranyl phosphate compounds and simulated uranium ores. An extraction method consisting of a static extraction process and a dynamic one was established, and the effects of the experimental conditions, such as pressure, temperature, and extraction time, on the extraction of uranium were ascertained. It was found that uranium could be efficiently extracted from both the uranyl phosphates and simulated ores by the SFE method using CO(2). It was thus demonstrated that the SFE method using CO(2) is useful as a pretreatment method for the analysis of uranium in ores.     

Organic dyes containing nonsubstituted aryl amino moieties and azobenzene units for dye‐sensitized solar cells

A series of novel sensitizers were successfully synthesized utilizing azobenzene as a π‐linkage unit for the D–π–A structure. A slight red shift on the absorption spectra and λ_onset of the sensitizers could be observed when the thienyl group was introduced to the acceptor moiety (A). In addition, replacing the donor moiety (D) from carbazole to diarylamino could lead to a negative shift (approximately 0.3 V) in the first oxidation potential. DFT calculation was also carried out and the trend of calculated HOMO–LUMO gaps was consistent to the experimental data obtained from the CV results ( DT1 < DT2 < DT3 < DT4 ). These sensitizers were then employed in dye‐sensitized solar cells to investigate their photovoltaic performances. Highest power conversion efficiency (PCE) of 0.84% was achieved for DT1 ‐based DSSC according to its most bathochromic absorption spectrum.     

The isolation of chitinase from Streptomyces thermocarboxydus and its application in the preparation of chitin oligomers

Research on Chemical Intermediates - Microbial chitinase has received great attention due to its medical, biological, and agricultural applications. In this study, over 50 bacterial strains were...     

Evaluation of the Saponin Content in Panax vietnamensis Acclimatized to Lam Dong Province by HPLC–UV/CAD

Panax vietnamensis, or Vietnamese ginseng (VG), an endemic Panax species in Vietnam, possesses a unique saponin profile and interesting biological activities. This plant is presently in danger of extinction due to over-exploitation, resulting in many preservation efforts towards the geographical acclimatization of VG. Yet, no information on the saponin content of the acclimatized VG, an important quality indicator, is available. Here, we analyzed the saponin content in the underground parts of two- to five-year-old VG plants acclimatized to Lam Dong province. Nine characteristic saponins, including notoginsenoside-R1, ginsenoside-Rg1, -Rb1, -Rd, majonoside-R1, -R2 vina-ginsenoside-R2, -R11, and pseudoginsenoside-RT4, were simultaneously determined by HPLC coupled with UV and with a charged aerosol detector (CAD). Analyzing the results illustrated that the detection of characteristic ocotillol-type saponins in VG by CAD presented a superior capacity compared with that of UV, thus implying a preferential choice of CAD for the analysis of VG. The quantitative results indicating the saponin content in the underground parts of VG showed an increasing tendency from two to five years old, with the root and the rhizome exhibiting different saponin accumulation patterns. This is the first study that reveals the preliminary success of VG acclimatization and thereby encourages the continuing efforts to develop this valuable saponin-rich plant.     

Simulating self-assembly of ZnS nanoparticles into mesoporous materials

Characterization of materials is crucial for the quantification and prediction of their physical, chemical, and mechanical properties. However, as the complexity of a system increases, so do the challenges involved in elucidating its structure. While molecular simulation and modeling have proved invaluable as complements to experiment, such simulations now face serious challenges: new materials are being synthesized with ever increasing structural complexity, and it may soon prove impossible to generate models that are sufficiently realistic to describe them adequately. Perhaps, ultimately, it will only be possible to generate such models by simulating the synthetic process itself. Here, we attempt such a strategy to generate full atomistic models for mesoporous molecular sieves. As in experiment, this is done by allowing nanoparticles to self-assemble at high temperature to form an amorphous mesoporous framework. The temperature is then reduced, and the system is allowed to crystallize. Animations of atomic trajectories, available as Supporting Information, reveal the evolution of multiple seeds which propagate to form a complex framework. The products are polycrystalline mesoporous framework structures containing cavities connected by channels running along "zero", one, two, and three perpendicular directions. We suggest that it is easier to generate these model structures by attempting to simulate the synthetic process rather than by using more conventional techniques. The strategy is illustrated using ZnS as a model system. Further development of the mathematics of minimal surfaces will advance our understanding of these structures.     

Green synthesis of silver nanoparticle-decorated porous reduced graphene oxide for antibacterial non-enzymatic glucose sensors

A simple and environmentally friendly approach was developed to fabricate silver nanoparticle (Ag NP)-decorated porous reduced graphene oxide (grGO) using glucose as a crosslinking and reducing agent. Physicochemical analysis, such as X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission-scanning electron microscopy (FE-SEM) were used to confirm the structural, morphological characteristics of the as-prepared samples. The electrocatalytic activity of Ag/grGO towards glucose oxidation was examined by cyclic voltammetry and amperometry. The fabricated sensor showed excellent sensitivity of 725.0 μA cm^?2 mM^?1 with a rapid response time of 11 s. Furthermore, the hybrids showed significant antibacterial activity against Escherichia coli with 99.76% antibacterial efficiency after 18 h.     

Microwaves in drug discovery and multi-step synthesis

The interest of microwaves in drug discovery and multi-step synthesis is exposed with the aim of describing our strategy. These studies are connected with our work on the synthesis of original heterocyclic compounds with potential pharmaceutical value. Reactions in the presence of solvent and solvent-free synthesis can be realised under a variety of conditions; for some of these selected results are given, and where available, results from comparison with the same solvent-free conditions but with classical heating are given.     

Atlas-based automatic mouse brain image segmentation revisited: model complexity vs. image registration

Although many atlas-based segmentation methods have been developed and validated for the human brain, limited work has been done for the mouse brain. This paper investigated roles of image registration and segmentation model complexity in the mouse brain segmentation. We employed four segmentation models [single atlas, multiatlas, simultaneous truth and performance level estimation (STAPLE) and Markov random field (MRF) via four different image registration algorithms (affine, B-spline free-form deformation (FFD), Demons and large deformation diffeomorphic metric mapping (LDDMM)] for delineating 19 structures from in vivo magnetic resonance microscopy images. We validated their accuracies against manual segmentation. Our results revealed that LDDMM outperformed Demons, FFD and affine in any of the segmentation models. Under the same registration, increasing segmentation model complexity from single atlas to multiatlas, STAPLE or MRF significantly improved the segmentation accuracy. Interestingly, the multiatlas-based segmentation using nonlinear registrations (FFD, Demons and LDDMM) had similar performance to their STAPLE counterparts, while they both outperformed their MRF counterparts. Furthermore, when the single-atlas affine segmentation was used as reference, the improvement due to nonlinear registrations (FFD, Demons and LDDMM) in the single-atlas segmentation model was greater than that due to increasing model complexity (multiatlas, STAPLE and MRF affine segmentation). Hence, we concluded that image registration plays a more crucial role in the atlas-based automatic mouse brain segmentation as compared to model complexity. Multiple atlases with LDDMM can best improve the segmentation accuracy in the mouse brain among all segmentation models tested in this study.