饲料中重金属检测技术的研究进展

综述了饲料中重金属的检测方法如光谱分析法(包括原子吸收光谱法、原子荧光光谱法、电感耦合等离子体发射光谱法、X-射线荧光光谱法和激光诱导击穿光谱法)、电感耦合等离子体质谱法、电化学分析法和分光光度法的研究进展,对各类检测方法的优缺点进行了对比与分析,并在此基础上对饲料中重金属检测技术的发展趋势进行了展望。     

Synthesis and surface properties of novel fluorinated polyurethane base on F‐containing chain extender

A novel fluorinated chain extender, (1‐(ethyl(2‐hydroxyethyl)amino)‐3‐ ((3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctyl)oxy)propan‐2‐ol) (FPO), was synthesized and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and elemental analysis. Poly (ether urethane)s containing various amounts of the chain extender with fluorinated side chains (FPUs) were prepared by isophorone diisocyanate (IPDI), polytetra‐methylene‐ether‐glycol (PTMG), 3‐aminopropyltriethoxysilane (KH‐550), and 1,4‐butandiol (BDO). Films of FPUs were investigated by water absorption, contact angle, pencil hardness, adhesive force, and thermal analysis. Coating FPUs on micro‐nano concave‐convex structure plate realizes superhydrophobic performance. Scanning electron microscope (SEM) and atomic force microscopy (AFM) demonstrated that there is a lot of irregular concave‐convex structure, which forms a typical air cushion model. X‐ray photoelectron spectroscopy (XPS) analysis showed that surface fluorine content is 165% more than that of film average fluorine content. The superhydrophobic plate with 10% or higher F‐containing FPUs coating is of outstanding chemical corrosion resistance, excellent solvent resistance, and wear resistance.     

Analysis of ginseng root and leaf by multiple columns and detections liquid chromatography

Abstract

A multiple columns and detections liquid chromatography system, including size exclusion chromatography (SEC) and reversed phase liquid chromatography (RPLC), for the analysis of macromolecules and micromolecules in ginseng root and leaf was developed. The columns were connected by two switching valves. Macromolecules were separated on a SEC column (TSK gel SuperMultipore PW-H column, 6?mm× 150?mm, 8?μm) by isocratic elution of 50?mM ammonium acetate aqueous solution, 0.3?mL/min of flow rate and detected by evaporative light scattering detection (ELSD). Micromolecules were analyzed on a Poroshell RP column (Agilent Poroshell 120?SB-Aq column, 4.6?mm × 50?mm, 2.7 µm) with gradient elution of water and acetonitrile, 0.6?mL/min of flow rate and detected by ultraviolet detection (UV). As a result, in the macromolecules chromatogram of ginseng root sample showed two main peaks while only one major peak for ginseng leaf. For micromolecules analysis, 17 compounds (3 nucleosides + 14 saponins) and 17 compounds (3 nucleosides + 1 flavonoid + 13 saponins) were found in ginseng root and leaf, respectively. The developed method is helpful for the quality evaluation of ginseng root and leaf.     

Combustion behavior and thermal stability of TPU composites based on layered yttrium hydroxides and graphene oxide

Journal of Thermal Analysis and Calorimetry - Layered yttrium hydroxides (LYH)- and graphene oxide (GO)-supported layered yttrium hydroxides (GO–LYH) were synthesized by a co-precipitation...     

Poly(2‐Oxazoline)‐Based Functional Peptide Mimics: Eradicating MRSA Infections and Persisters while Alleviating Antimicrobial Resistance

Peptides have important biological functions. However, their susceptibility to proteolysis limits their applications. We demonstrated here for the first time, that poly(2‐oxazoline) (POX) can work as a functional mimic of peptides. POX‐based glycine pseudopeptides, a host defense peptide mimic, had potent activities against methicillin‐resistant S. aureus, which causes formidable infections. The POX mimic showed potent activity against persisters that are highly resistant to antibiotics. S. aureus did not develop resistance to POX owning to the reactive oxygen species related antimicrobial mechanism. POX‐treated S. aureus is sensitive to common antibiotics, demonstrating no observable antimicrobial pressure or cross‐resistance in using antimicrobial POX. This study highlights POX as a new type of functional mimic of peptides and opens new avenues in designing and exploring peptide mimetics for biological functions and applications.     

Enhanced Surface Interactions Enable Fast Li+ Conduction in Oxide/Polymer Composite Electrolyte

Li⁺‐conducting oxides are considered better ceramic fillers than Li⁺‐insulating oxides for improving Li⁺ conductivity in composite polymer electrolytes owing to their ability to conduct Li⁺ through the ceramic oxide as well as across the oxide/polymer interface. Here we use two Li⁺‐insulating oxides (fluorite Gd_0.1Ce_0.9O_1.95 and perovskite La_0.8Sr_0.2Ga_0.8Mg_0.2O_2.55) with a high concentration of oxygen vacancies to demonstrate two oxide/poly(ethylene oxide) (PEO)‐based polymer composite electrolytes, each with a Li⁺ conductivity above 10^?4 S cm^?1 at 30 °C. Li solid‐state NMR results show an increase in Li⁺ ions (>10 %) occupying the more mobile A2 environment in the composite electrolytes. This increase in A2‐site occupancy originates from the strong interaction between the O^2? of Li‐salt anion and the surface oxygen vacancies of each oxide and contributes to the more facile Li⁺ transport. All‐solid‐state Li‐metal cells with these composite electrolytes demonstrate a small interfacial resistance with good cycling performance at 35 °C.     

Non‐natural Cofactor and Formate‐Driven Reductive Carboxylation of Pyruvate

A non‐natural cofactor and formate driven system for reductive carboxylation of pyruvate is presented. A formate dehydrogenase (FDH) mutant, FDH*, that favors a non‐natural redox cofactor, nicotinamide cytosine dinucleotide (NCD), for generation of a dedicated reducing equivalent at the expense of formate were acquired. By coupling FDH* and NCD‐dependent malic enzyme (ME*), the successful utilization of formate is demonstrated as both CO₂ source and electron donor for reductive carboxylation of pyruvate with a perfect stoichiometry between formate and malate. When ¹³C‐isotope‐labeled formate was used in in vitro trials, up to 53 % of malate had labeled carbon atom. Upon expression of FDH* and ME* in the model host E. coli, the engineered strain produced more malate in the presence of formate and NCD. This work provides an alternative and atom‐economic strategy for CO₂ fixation where formate is used in lieu of CO₂ and offers dedicated reducing power.     

Visible-NIR Photodetectors Based on Low-Dimensional GeSe Micro-Crystals: Designed Morphology and Improved Photoresponsivity

GeSe micro-sheets and micro-belts have been synthesized by a facile one-pot wet chemical method in 1-octadecene solvent and oleic acid solvent, respectively. The adsorption of more oleic acid molecules on the (002) plane promoted growth along [010] direction of the GeSe micro-belts and limited carrier transport in this direction, resulting in higher carrier concentration and mobility of the GeSe micro-belts. The performance of the photodetectors based on the single GeSe micro-sheet and the single GeSe micro-belt was investigated under illumination at 532 nm, 980 nm and 1319 nm. Both, photodetectors based on a single GeSe micro-sheet and a single GeSe micro-belt, exhibit a high photoresponse, short response/recovery times, and long-term durability. Moreover, the photodetector based on a single GeSe micro-belt displays a broadband response with a high responsivity (5562 A/W at 532 nm, 1546 A/W at 980 nm) and detectivity (3.01×10¹² Jones at 532 nm, 8.38×10¹¹ Jones at 980 nm). These excellent characteristics render single GeSe micro-belts very interesting for use as highly efficient photodetectors, especially in the NIR region.     

Iridoid,phenylethanoid and flavonoid glycosides from Forsythia suspensa

Abstract

As part of our continuing efforts to explore bioactive compounds from natural resources, a new iridoid glycoside, adoxosidic acid-6′-oleuroperic ester (1), together with one known phenylethanoid glycoside (2) and two known flavonoid glycosides (3–4) were isolated from the fruit of Forsythia suspensa. The structure of the new compound (1) was elucidated through 1D and 2D NMR spectroscopic data and HR-ESIMS. Interestingly, compound 1 was a monoterpene ester of one iridoid glycoside. Compounds 2–4 were identified as calceolarioside A (2), kaempferol-3-O-rutinoside (3), kampferol-3-O-robinobioside (4) on the basis of NMR spectroscopic data analyses and comparison with the data reported in the literature. The antiviral activity aganisist influenza A (H5N1) virus of compound 1 was studied as well.     

Rotational Spectra of 2,3,6-Trifluoropyridine: Effect of Fluorination on Ring Geometry

The ground state rotational spectrum of 2, 3, 6-trifluoropyridine has been investigated in the 2.0\begin{document}$ - $\end{document}20.0 GHz region by pulsed jet Fourier transform microwave spectroscopy. The experimental rotational constants are \begin{document}$ A $\end{document} = 3134.4479(2) MHz, \begin{document}$ B $\end{document} = 1346.79372(7) MHz, and \begin{document}$ C $\end{document} = 941.99495(6) MHz. The transitions are so intense that rotational transitions of all mono-\begin{document}$ ^{13} $\end{document}C and \begin{document}$ ^{15} $\end{document}N isotopologues are measured in natural abundance. The semi-experimental equilibrium rotational constants of the 7 isotopologues were derived by taking account of the anharmonic vibrational corrections, which allowed a semi-experimental determination of the equilibrium structure of 2, 3, 6-trifluoropyridine.