Synthesis of 2,6-Disubstituted Fluorenones

Various 2,6-disubstituted fluorenones 1a-1g were synthesized by the dry salt decomposition of 5,4′ -disubstituted 2-diazoniobenzophenone tetrafluoroborates 8a-8g via Pschorr cyclization in reasonable yields.     

A comparative study on sorption and diffusion of Cs in crushed argillite and granite investigated in batch and through-diffusion experiment

The batch and through-diffusion experiments in this study were conducted and compared in order to investigate the sorption and diffusion of cesium (Cs) for two potential host rocks in Taiwan: argillite from Taitung and granite from Kinmen Island, with the purpose of establishing a reliable safety-performance assessment methodology for the final disposal of low level radioactive waste. The results of Cs mapping by scanning electron microscope equipping by energy dispersive spectrometer (SEM–EDS) showed that the distribution of Cs on argillite and granite were enriched in illite and biotite, respectively. In addition, it showed that higher sorption capacities were found for argillite than granite; due to the clay mineral content (illite) in the argillite. Experiments for diffusion of Cs is agreement to the values estimated for the diffusive results (D _a) of Cs in argillite were revealed to be lower than those of granite.

     

The theory of similarity and the profile of vertical distribution of concentration of sand particles

In this article, we treat the problem of two-dimensional uniform steady channel flow of turbid water with theory of similarity. Under the condition of similarity of turbulent fluctuation velocity and fluctuation of concentration of sand particles, we obtain the profile of the vertical distribution of concentration of sand particles. This profile of vertical distribution of concentration of sand particles is slightly different from that obtained by diffusion theory, and departs from that obtained by gravitational theory.     

Steric stabilization of thermally responsive N-isopropylacrylamide particles by poly(vinyl alcohol)

Poly(vinyl alcohol) (PVA) was used as a steric stabilizer for the dispersion polymerization of cross-linked poly(N-isopropylacrylamide) (PNIPAM) in water. A series of reactions were carried out using PVA of varying molecular weight and degree of hydrolysis. Under appropriate conditions, PNIPAM particles of uniform and controllable size were produced using PVA as the stabilizer. The colloidal stability was investigated by measuring changes in particle size with temperature in aqueous suspensions of varying ionic strength. For comparison, parallel colloidal stability measurements were conducted on PNIPAM particles synthesized with low-molecular-weight ionic surfactants. PVA provides colloidal stability over a wide range of temperature and ionic strength, whereas particles produced with ionic surfactants flocculate in moderate ionic strength solutions upon collapse of the hydrogel as the temperature is increased. Experimental results and theoretical consideration indicate that sterically stabilized PNIPAM particles resulted from the grafting of PVA to the PNIPAM particle surface. The enhanced colloidal stability afforded by PVA allows the temperature-responsive PNIPAM particles to be used under physiological conditions where electrostatic stability is ineffective.     

Rapid determination of aristolochic acids I and II in herbal products and biological samples by ultra-high-pressure liquid chromatography-tandem mass spectrometry

Aristolochic acids (AAs) are a mixture of structural-related compounds, in which aristolochic acid I (AA I) and aristolochic acid II (AA II) are reported to be correlated with Aristolochic acid nephropathy (AAN). In this work, a rapid and sensitive ultra-high-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to determine AA I and AA II in herbal products and biological fluids. By using gradient elution with a mobile phase composed of a mixture of 10 mM ammonium formate buffer (pH 3.0) and acetonitrile, AAs could be determined within 10 min. Under optimum UHPLC-MS/MS conditions, the limit of detections was 0.14 and 0.26 ng mL⁻¹ for AA I and AA II, respectively. Run-to-run repeatability and intermediate precision of peak area for AA I and AA II were less than 5.74% relative standard deviation (RSD). Accuracy was tested by spiking 10, 100 and 1000 ng mL⁻¹ in rat serum and the recoveries were within 76.5-92.9%. Matrix effects were within 78.8-127.7%. The developed method was successfully applied to determine AA I and AA II in several herbal products and to investigate their pharmacokinetic behavior in female Wister rats. The result shows that the developed UHPLC-MS/MS method is efficient, sensitive, and accurate for the determination of AA I and AA II in herbal products and biological samples.     

Green Synthesis of Silver Nanoparticles Using Ionic Liquid and Application for the Detection of Dissolved Oxygen

The electrochemical synthesis of silver nanoparticles (nano‐Ag) has been successfully carried out on glassy carbon electrode (GCE) and indium tin oxide electrode (ITO) using 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMT) as green electrolytes. Further the electrodeposited nano‐Ag modified ITO electrode has been examined using atomic force microscopy (AFM), and X‐ray diffraction studies (XRD). The electrodeposited Ag nanoparticles on ITO were found in the size range of 5 to 35 nm. The nano‐Ag film modified GCE was further coated with nafion (Nf) and BMT (1 : 1 ratio) mixture and found to be stable in BMT and in pH 7 phosphate buffer solution (PBS). The nano‐Ag/BMT‐Nf film modified GCE successfully applied for the oxygen reduction reaction in neutral pH (pH 7.0 PBS). The proposed film modified GCE successfully reduces the over potential and show well defined reduction peaks for the detection of dissolved oxygen using cyclic voltammetry (CV) and rotating disc voltammetry (RDE). The film also applied for the detection of dissolved oxygen using electrochemical impedance spectroscopic studies (EIS).     

Synthesis, properties and enzymatic hydrolysis of biodegradable alicyclic/aliphatic copolyesters based on 1,3/1,4-cyclohexanedimethanol

This study synthesizes a series of cyclohexanedimethanol (CHDM)-based alicyclic/aliphatic copolyesters (PBSCs) using succinic acid, 1,4-butanediol and 1,3/1,4-CHDM at various molar ratios to investigate the effects of these compositions on crystallinity, biodegradability and the mechanical properties of PBSCs. The PBSCs were characterized using proton nuclear magnetic resonance, gel permeation chromatography, wide-angle X-ray diffraction, differential scanning calorimeter and thermogravimetric analysis. Biodegradability was evaluated by enzymatic hydrolysis with a lipase from Pseudomonas cepacia. The mechanical properties of PBSCs were determined using a tensile testing machine.Experimental results reveal that the PBSCs containing 1,3/1,4-CHDM in total diol with less than 50 mol% are crystallizable, while those containing 1,3/1,4-CHDM with more than 50 mol% are amorphous. The biodegradability test results suggest that PBSCs can be classified as surface-eroding polymers with a random endo-type scission. Surface hydrophilicity of PBSCs was the predominant effect on enzymatic hydrolysis, not crystallinity.     

Crystallinity and dimensional stability of biaxial oriented poly(lactic acid) films

Transparent biaxial oriented poly(lactic acid) (BOPLA) films with improved dimensional stability were successfully prepared by controlling the crystallization of poly(lactic acid) (PLA). The crystalline morphology of PLA films can be manipulated by changing certain processing parameters, such as stretch ratio, heat setting temperatures, and heat setting time. Optical and mechanical properties as well as dimensional stability of the resulting polymer films are governed by their crystallinity and crystalline morphology. Crystallization behavior and kinetics of PLA, therefore, were investigated using wide angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS), and differential scanning calorimetry (DSC) techniques. Mechanical properties and the dimensional stability of the biaxial oriented PLA films were obtained and correlated with their processing conditions. Poly(lactic acid) films prepared by melt extrusion methods have great potential for food packaging, shrink labeling and protective film applications. However, shrinkage at elevated processing temperature should be minimized to avoid puckering of the polymer film. Shrinkage of less than 2% was achieved for a BOPLA film stretched 300% in both directions at 75 °C and then annealed at 160 °C for 30 s. Fabrication, properties, and potential applications of a series of biodegradable films will be described.     

Proteomic identification of salivary transferrin as a biomarker for early detection of oral cancer

Oral cancer has a low five-year survival rate. Early detection of oral cancer could reduce the mortality and morbidity associated with this disease. Saliva, which can be sampled non-invasively and is less complex than blood, is a good potential source of oral cancer biomarkers. Proteomic analysis of saliva from oral cancer patients and control subjects was performed to identify salivary biomarkers of early stage oral cancer in humans. The protein profile of pooled salivary samples from patients with oral squamous cell carcinoma (OSCC) or OSCC-free control subjects was analyzed using two-dimensional gel electrophoresis (2DE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses. Potential biomarkers were verified by Western blotting and ELISA assays. Transferrin levels were elevated in the saliva of OSCC patients as determined using 2DE followed by MALDI-TOF MS and confirmed by MALDI-TOF/TOF MS, Western blotting and ELISA. The increase in salivary transferrin levels in OSCC patients strongly correlated with the size and stage of the tumor. The area under the receiver-operating characteristics curves showed that salivary transferrin-based ELISA was highly specific, sensitive and accurate for the early detection of oral cancer. We have identified salivary transferrin as a biomarker for the detection of early stage oral cancer. This finding provides a promising basis for the development of a non-invasive diagnostic test for early stage oral cancer.