Dynamic Variation of Amino Acid Contents and Identification of Sterols in Xinyang Mao Jian Green Tea

As important biomolecules in Camellia sinensis L., amino acids (AAs) are considered to contribute to the overall green tea sensory quality and undergo dynamic changes during growth. However, limited by analytical capacity, detailed AAs composition in different growth stages remains unclear. To address this question, we analyzed the dynamic changes of 23 AAs during leaf growth in Xinyang Mao Jian (XYMJ) green tea. Using amino acid analyzer, we demonstrated that most AAs are abundant on Pure Brightness Day and Grain Rain Day. After Grain Rain, 23 AAs decreased significantly. Further analysis shows that theanine has a high level on the day before Spring Equinox and Grain Rain, accounting for 44–61% of the total free AAs content in tea leaves. Glu, Pro, and Asp are the second most abundant AAs. Additionally, spinasterol and 22,23-dihydrospinasterol are first purified and identified in ethanol extract of XYMJ by silica gel column chromatography method. This study reveals the relationship between plucking days and the dynamic changes of AAs during the growth stage and proves the rationality of the traditional plucking days of XYMJ green tea.     

High-performance potassium poly(heptazine imide) films for photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is an appealing approach by which to convert solar energy into hydrogen fuel. Polymeric semiconductors have recently attracted intense interest of many scientists for PEC water splitting. The crystallinity of polymer films is regarded as the main factor that determines the conversion efficiency. Herein, potassium poly(heptazine) imide (K-PHI) films with improved crystallinity were in situ prepared on a conductive substrate as a photoanode for solar-driven water splitting. A remarkable photocurrent density of ca. 0.80 mA cm⁻² was achieved under air mass 1.5 global illumination without the use of any sacrificial agent, a performance that is ca. 20 times higher than that of the photoanode in an amorphous state, and higher than those of other related polymeric photoanodes. The boosted performance can be attributed to improved charge transfer, which has been investigated using steady state and operando approaches. This work elucidates the pivotal importance of the crystallinity of conjugated polymer semiconductors for PEC water splitting and other advanced photocatalytic applications.

Potassium poly(heptazine imide) photoanode is synthesized, and owing to the improved crystallinity, it has presented a remarkable performance for solar-driven water splitting.     

Preparation of nano-hydroxyapatite/poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide) biocomposite microspheres

Nano-hydroxyapatite (HA)/poly(l-lactide) (PLLA) composite microspheres with relatively uniform size distribution were prepared by a solid-in-oil-in-water (s/o/w) emusion solvent evaporation method. The encapsulation of the HA nanopaticles in microshperes was significantly improved by grafting PLLA on the surface of the HA nanoparticles (p-HA) during emulsion process. This procedure gave a possibility to obtain p-HA/PLLA composite microspheres with uniform morphology and the encapsulated p-HA nanoparticle loading reached up to 40 wt% (33 wt% of pure HA) in the p-HA/PLLA composite microspheres. The microstructure of composite microspheres from core-shell to single phase changed with the variation of p-HA to PLLA ratios. p-HA/PLLA composite microspheres with the diameter range of 2–3 μm were obtained. The entrapment efficiency of p-HA in microspheres could high up to 90 wt% and that of HA was only 13 wt%. Surface and bulk characterizations of the composite microspheres were performed by measurements such as wide angle X-ray diffraction (WAXD), thermal gravimetric analysis (TGA), environmental scanning electron microscope (ESEM) and transmission electron microscopy (TEM).     

Seasonal variation of 129I species in the Baltic Proper

Iodine speciation plays a significant role in iodine volatilizing into atmosphere from the seas, as well as serving as a biological indicator. Despite this importance, the data on iodine species revealed inconclusive evidence of what factors controlling speciation transformation. We here present new data on profiles of ¹²⁹I speciation in the Baltic Proper during November 2009. Along with the two earlier investigations (August 2006 and April 2007), an assessment of seasonal variation of ¹²⁹I species is presented. The results show that, due to the anoxic nature of Baltic Proper, presence of ¹²⁹IO₃ ^? in the Baltic Proper does not follow an obvious seasonal cycle, as the case with ¹²⁹I^?. Concentrations of ¹²⁹I^? in the Baltic Proper exhibit higher values in summer than the other two seasons (spring and winter), which might be associated with degrading of organic matter and release from sediment to water column that is more pronounced during summer. ¹²⁹I^? in surface water from the three seasons does not reflect the release function from the reprocessing facilities during the period April 2007 to November 2009. Consequently variability of ¹²⁹I^? in surface seawater of the Baltic Proper depends, to some extent, on local physical as well as biochemical conditions.     

Poly(methyl methacrylate‐co‐pentaerythritol tetraacrylate‐co‐butyl methacrylate)‐g‐polystyrene: Synthesis and high oil‐absorption property

Well‐defined high oil‐absorption resin was successfully prepared via living radical polymerization on surface of polystyrene resin‐supported N‐chlorosulfonamide group utilizing methyl methacrylate and butyl methacrylate as monomers, ferric trichloride/iminodiacetic acid (FeCl₃/IDA) as catalyst system, pentaerythritol tetraacrylate as crosslinker, and L ‐ascorbic acid as reducing agent. The polymerization proceeded in a “living” polymerization manner as indicated by linearity kinetic plot of the polymerization. Effects of crosslinker, catalyst, macroinitiator, reducing agent on polymerization and absorption property were discussed in detail. The chemical structure of sorbent was determined by FTIR spectrometry. The oil‐absorption resin shows a toluene absorption capacity of 21 g g^?1. The adsorption of oil behaves as pseudo‐first‐order kinetic model rather than pseudo‐second‐order kinetic model. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis of a benzoxazine with precisely two phenolic OH linkages and the properties of its high‐performance copolymers

A phenolic OH‐containing benzoxazine ( F‐ap ), which cannot be directly synthesized from the condensation of bisphenol F, aminophenol, and formaldehyde by traditional procedures, has been successfully prepared in our alternative synthetic approach. F‐ap was prepared by three steps including (a) condensation of 4‐aminophenol and 5,5'‐methylenebis(2‐hydroxybenzaldehyde) (1) , (b) reduction of the resulting imine linkage by sodium borohydride, and (c) ring closure condensation by formaldehyde. The key starting material, (1) , was prepared from 2‐hydroxybenzaldehyde and s‐trioxane in the presence of sulfuric acid. F‐ap is structurally similar to bis(3,4‐dihydro‐2H‐3‐phenyl‐1,3‐benzoxazinyl)methane ( F‐a, a commercial benzoxazine based on bisphenol F/aniline/formaldehyde) except for two phenolic OHs. The phenolic OHs can provide reaction sites with epoxy and 1,1'‐(methylenedi‐p‐phenylene)bismaleimide (BMI). The structure–property relationships between the thermosets of F‐ap /epoxy, F‐a /epoxy, F‐ap /BMI, and F‐a /BMI were discussed. Experimental data showed that thermosets based on F‐ap /epoxy and F‐ap /BMI provided much better thermal properties than those based on F‐a /epoxy and F‐a /BMI. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2686–2694     

Polymeric ytterbium(ii) complex with pyridyl amido ligands

The reaction of potassium pyridyl amido ligand {L = [N(R)(2-C5H3N-6-Me)]–, R = CH2But} with YbI2(thf)2 afforded the linear polymeric complex [K0.5(L)3YbiiK0.5]n, which was characterized by X-ray structure analysis.     

The effect of drying method on the properties and nanoscale structure of cellulose whiskers

Cellulose whiskers were prepared from wood- and cotton-based microcrystalline cellulose and dried by two methods: freeze-drying or air-drying. The effect of drying method on the properties and structure of the whiskers were studied. Furthermore, the influence of the source of cellulose on the nanoscale structure was investigated. Drying method was observed to slightly influence the thermal stability of cellulose whiskers, whereas the char residue varied significantly depending on the drying process performed. Small- and wide-angle X-ray scattering and solid state nuclear magnetic resonance spectroscopy were used to examine the crystallinity and nanoscale structure of the dried whiskers. It was observed that the crystal structure and crystallinity of cellulose whiskers remained during all treatments, whereas their nanoscale structure was significantly influenced by drying method, neutralization, and source of cellulose. Relationships between thermal behavior and nanoscale structure were reported and discussed.