The Separation of Alanine Enatiomer Derivatives by the Proton‐Inhibition Method

Better peak shapes and complete separation of amino‐3,5‐dinitro derivatives by (S)‐N‐(2‐naphthyl)alanine derived chiral stationary phase (CSP) is achieved by adding a trace amount of acetic acid in the mobile phase. This method provides an indication of its broad applicability on direct separation of a series of amino‐containing enantiomers on CSP. In addition, the reversed elution order was obtained on its enatiomeric CSP.     

In Vitro Osteoblast Differentiation is Negatively Regulated by Hoxc8

Hoxc8 has multiple roles in normal skeletal development. In this paper, a MC3T3-E1 subclone 4 osteogenic cell differentiation model was used to examine expression of Hoxc8 at multiple stages of osteogenesis. We found that Hoxc8 expression levels do not change in the early stage but increase in the middle stage and decrease in the late stage of osteogenesis. A knockdown of Hoxc8 by small-interfering RNA transfection in C2C12 cells indicated that Hoxc8 is a negative regulator of osteogenesis. Similarly, expression of Hoxc8 in C2C12 cells decreases alkaline phosphatase levels induced by bone morphogenetic protein-2 (BMP-2). The results of this study showed that Hoxc8 is involved in BMP-2-induced osteogenesis, and osteoblast differentiation in vitro is negatively regulated by Hoxc8, suggesting that Hoxc8 regulation is essential for osteoblast differentiation.     

Validation and use of a fast sample preparation method and liquid chromatography–tandem mass spectrometry in analysis of ultra-trace levels of 98 organophosphorus pesticide and carbamate residues in a total diet study involving diversified food types

This paper reports a comprehensive sensitive multi-residue liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for detection, identification and quantitation of 73 pesticides and their related products, a total of 98 analytes, belonging to organophosphorus pesticides (OPPs) and carbamates, in foods. The proposed method makes use of a modified QuEChERS (quick, easy, cheap, effective, rigged, and safe) procedure that combines isolation of the pesticides and sample clean-up in a single step. Analysis is performed by liquid chromatography-electrospray ionization–tandem mass spectrometry operated in the multiple reaction monitoring (MRM) mode, acquiring two specific precursor-product ion transitions per target compound. Two main fragment ions for each pesticide were obtained to achieve the identification according to the SANCO guidelines 10684/2009. The method was validated with various food samples, including edible oil, meat, egg, cheese, chocolate, coffee, rice, tree nuts, citric fruits, vegetables, etc. No significant matrix effect was observed for tested pesticides, therefore, matrix-matched calibration was not necessary. Calibration curves were linear and covered from 1 to 20 μg L⁻¹ for all compounds studied. The average recoveries, measured at 10 μg kg⁻¹, were in the range 70–120% for all of the compounds tested with relative standard deviations below 20%, while a value of 10 μg kg⁻¹ has been established as the method limit of quantitation (MLOQ) for all target analytes. Similar trueness and precision results were also obtained for spiking at 200 μg kg⁻¹. Expanded uncertainty values were in the range 21–27% while the HorRat ratios were below 1. The method has been successfully applied to the analysis of 700 food samples in the course of a baseline monitoring study of OPPs and carbamates.     

Juncenolides H – K,New Briarane Diterpenoids from Junceella juncea

Chemical investigation of the Taiwanese gorgonian coral Junceella juncea resulted in the isolation of four new briarane‐type diterpenoids, juncenolides H, I, J, and K ( 1 – 4 ). Their structures were determined on the basis of spectroscopic analysis, especially 1‐ and 2D‐NMR. The inhibitory effects of compounds 1 – 4 on superoxide‐anion generation and elastase release by human neutrophils were evaluated.     

New method for determination of equilibrium/kinetic sorption parameters

We proposed a new method from which kinetic sorption parameters can be estimated using aqueous phase concentration versus time data commonly available from adsorption tests. The method relies on the analytical solution that was solved for two-site reversible sorption kinetics based on mass conservation law for solute in a batch reaction system. In order to validate the method, model parameters were compared with those of three-stage kinetic models available in the literature. It was revealed that model parameters of the two-site kinetics could accurately be estimated as much as other model parameters. Advantage of the new method is acquisition of additional parameter, distribution or partitioning coefficient (K_d) frequently used in the analysis of chemical transfer in the solid–liquid interface.     

A 1 × 4 polarization and wavelength independent optical power splitter based on a novel wide-angle low-loss Y-junction

A 1 × 4 polarization and wavelength independent optical power splitter is reported. This device is based on a novel wide-angle low-loss Y-junction structure which can give a theoretical TE junction excess loss of 0.26 dB at a branching angle of 16°. To the best of our knowledge, it is so far the lowest reported loss at such a large angle. The detailed design of the device and its fabrication are described. Our experimental results show the measured TE excess loss to be 1.2 dB and TM excess loss 1.8 dB for the whole splitter over the wavelength between 1.47 μm and 1.57 μm.     

Effect of buffer layers on the property of Pb(Zr,Ti)O3-Pb(Mn,W,Sb,Nb)O3 thin films grown by pulsed laser deposition

New ferroelectric Pb(Zr,Ti)O₃-Pb(Mn,W,Sb,Nb)O₃ (PZT-PMWSN) thin film has been deposited on a Pt/Ti/SiO₂/Si substrate by pulsed laser deposition. Buffer layer was adopted between film and substrate to improve the ferroelectric properties of PZT-PMWSN films. Effect of a Pb(Zr_0.52Ti_0.48)O₃ (PZT) and (Pb_0.72La_0.28)Ti_0.93O₃ (PLT) buffer layers on the stabilization of perovskite phase and the suppression of pyrochlore phase has been examined. Role of buffer layers was investigated depending on different types of buffer layer and thickness. The PZT-PMWSN thin films with buffer layer have higher remnant polarization and switching polarization values by suppressing pyrochlore phase formation. The remnant polarization, saturation polarization, coercive field and relative dielectric constant of 10-nm-thick PLT buffered PZT-PMWSN thin film with no pyrochlore phase were observed to be about 18.523 μC/cm², 47.538 μC/cm², 63.901 kV/cm and 854, respectively.