Low-Temperature Conversion of <Emphasis Type="Italic">ortho</Emphasis>-Hydrogen into Liquid <Emphasis Type="Italic">para</Emphasis>-Hydrogen: Process and Catalysts. Review

The present review is devoted to some problems of the production of liquid para-hydrogen by catalytic ortho-para conversion (OPC) of molecular hydrogen at cryogenic temperatures, the catalysts of this process, and catalyst operation in hydrogen liquefiers. The methods of evaluating the catalyst activity in OPC and calculations of the performance of hydrogen liquefiers are given. The most important papers that deal with the use of catalysts of OPC under the conditions of hydrogen liquefiers were considered. A procedure for processing the experimental data on catalyst activity was presented for calculations of the laboratory and industrial hydrogen liquefiers working at different temperature levels based on these data.     

Polyelectrolytes with sulfonic acid groups useful in the synthesis and stabilization of Au and Ag nanoparticles

Two novel polyelectrolytes were obtained by chemical modification of poly(4-acryloyloxybenzaldehyde) using o- and p-aminophenylsulfonic acid, the characterization shows a chemical modification of 24.38 and 63.33%, respectively. The study shows that the polyelectrolyte with sulfonic acid in para position reduces metal ions more rapidly than polyelectrolyte in ortho position. The obtained nanoparticles of Au and Ag were characterized by ultraviolet–visible absorption spectroscopy (UV–vis) and transmission electron microscopy. The results showed that these ionic polymers are not only capable of reducing gold and silver ions, but also can stabilize the nanoparticles in the colloidal solutions. With these polymers, the process of metallic ions reduction is very slow and they lead to the production of Au and Ag nanoparticles with quasi-spherical shapes which are stable in colloidal solutions for several months. The advantage of the method used here is that the reduction can be realized in water at room temperature.     

Growth of silver nanoparticles on poly(acrylic acid) brushes and their properties

A simple procedure is employed for the growth of silver nanoparticles (Ag NPs) onto the silicon substrate modified by poly(acrylic acid) (PAA) brushes, via: (1) surface-initiated ATRP of tert-butyl acrylate on Si surface to the preparation of poly(tert-butyl acrylate) brushes, (2) acid hydrolysis of PBA to the formation of PAA, and (3) in situ synthesis of Ag NPs via chemical reduction of AgNO₃ in the presence of PAA brushes. The polymer brushes are thoroughly characterized. Moreover, Ag nanoparticles are homogeneously immobilized into the brush layer and have been used to fabricate a sensor platform of surface-enhance Raman scattering for the detection of organic molecules and effectively catalyze the reduction of methylene blue by NaBH₄.     

Dual stimuli-responsive supramolecular polymeric nanoparticles based on poly(<Emphasis Type="Italic">α</Emphasis>-cyclodextrin) and acetal-modified <Emphasis Type="Italic">β</Emphasis>-cyclodextrin-azobenzene

To aim at pH environment in tumor tissue and light-controlled drug release, UV and pH dual-responsive supramolecular polymeric nanoparticles mediated by host-guest interactions of poly(α-cyclodextrin) and acetal-modified β-cyclodextrin-azobenzene were developed in this work. The host molecule was poly(α-cyclodextrin) and the guest molecule was composed of acetal-modified β-cyclodextrin with one azobenzene linked. The inclusion of α-cyclodextrin and azobenzene leaded to amphiphilic supramolecular polymer, which further self-assembled to form supramolecular polymeric nanoparticles in aqueous medium. UV and pH responsiveness of supramolecular polymeric nanoparticles attributed to azobenzene and acetal, respectively. Supramolecular polymeric nanoparticles based on poly(α-cyclodextrin) and acetal-modified β-cyclodextrin-azobenzene with the average diameter of sub-100 nm were controllable to release the drugs regulated by pH and UV.     

Identification of Crepenynic Acid in the Seed Oil of <Emphasis Type="Italic">Atractylodes lancea</Emphasis> and <Emphasis Type="Italic">A. macrocephala</Emphasis>

Atractylodes rhizome is widely used in traditional Chinese herbal medicine. Although the chemical composition of the root has been studied in detail, the oil content and fatty acid composition of the seeds of Atractylodes species have not been reported. Fatty acyl composition of seeds from Atractylodes lancea and A. macrocephala was determined by gas chromatography and mass spectrometry of fatty acid methyl esters and 3-pyridylcarbinol esters. The predominant fatty acid in the seeds of both species was linolenic acid, but the unusual acetylenic fatty acid, crepenynic acid (cis-9-octadecen-12-ynoic acid), was also observed at levels of 18% in A. lancea and 13–15% in A. macrocephala. Fatty acid content was 24% for the samples of A. lancea and 16–17% for samples from A. macrocephala. sn-1,3 regioselective lipase digestion of seed lipids revealed that crepenynic acid was absent from the sn-2 position of the seed triacylglycerol. Crepenynic acid was also found in the seed oil of Jurinea mollis at 24% and was not present in the sn-2 position of the TAG. A contrasting distribution of crepenynic acid was found in the oil of Crepis rubra, suggesting differences in crepenynic acid synthesis or TAG assembly between these species.     

Bioengineering functional copolymers: synthesis and characterization of poly(<Emphasis Type="Italic">N</Emphasis>-isopropyl acrylamide-<Emphasis Type="Italic">co</Emphasis>-3,4-2H-dihydropyran)s

Novel bioengineering copolymers were synthesized by radical copolymerization of N-isopropylacrylamide (NIPA) and 3,4-2H-dihydropyran (DHP) with 2,2′-azobisisobutyronitrile as an initiator in acetone solution at 70 °C under nitrogen atmosphere. Structure, tacticity and compositons of the copolymers prepared in a wide range of monomer feed were confirmed by FTIR, ¹H{¹³C} NMR-DEPT and elemental analyses. The monomer reactivity ratios (r ₁ and r ₂) were detected using known two methods: r ₁ (NIPA)?=?1.25 and r ₂?=?0.035 (DHP), and r ₁ (NIPA) ?=?0.97 and r ₂?=?0.022 (DHP) by Kelen-Tüdös and Jaacks methods, respectively. It was demonstrated that the studied monomer pair has a tendency to form H-bonding beween amide/ether groups through ?NH...O< complexation which played an important role in the stereoselective chain growth, and significant decrease of allyl degradative chain transfer reactions. This phenomenon is also confirmed by the observed relatively high molecular weights of copolymers (M _v ). The synthesized water-soluble stimuli-responsive poly(NIPA-co-DHP)s exhibit thermal stability, higher glass-transition temperature, polyelectrolyte, pH- and temperature-sensitive behavior and can be attributed to the class of bioengineering functional copolymers useful for various bio- and gene-engineering, and drug delivery applications.     

Polypropylene surface with antibacterial property by photografting 1-vinylimidazole and subsequent chemical modification

The surface of polypropylene (PP) fiber was modified by UV-induced graft polymerization of 1-vinylimidazole (Vim), followed by quaternization with iodomethane, sulfonation with chlorosulfonic acid, or loading of silver (Ag) nanoparticles to endow the surface with antibacterial properties. The modified PP fibers were characterized by FT-IR, SEM, and surface charge analyses. The antibacterial activity of the modified PP fibers was assessed against the Gram-negative and Gram-positive bacteria, Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus), respectively. The PP-g-Vim was greatly improved by loading of Ag nanoparticles (≥99.9%), quaternization (98.9–99.2%), or sulfonation (≥99.9%).     

Polymer Protected and Gel Immobilized Gold and Silver Nanoparticles in Catalysis

This mini-review is focused on preparation of polymer protected gold (AuNPs) and silver (AgNPs) nanoparticles that are immobilized on the surface of inorganic supporters and within hydrogel and/or cryogel matrices. A series of water soluble polymers such as poly(N-vinylpyrrolidone), poly(acrylic acid), branched polyethyleneimine, and amphoteric cryogel based on the copolymer of N,N-dimethylaminoethylmethacrylate and methacrylic acid poly(DMAEM-MAA) were used for reduction and stabilization of metal nanoparticles. The catalytic properties of polymer protected AuNPs and AgNPs were evaluated with respect to hydrogen peroxide decomposition, hydrogenation of 4-nitrophenol and oxidation of cyclohexane.     

Sulfonic acid cation-exchange resins in the synthesis of straight-chain alkylphenols

Kinetic characteristics of reactions occurring in the alkylation of phenol with straight-chain alkenes (C₉, C₁₆) over the Amberlyst 15 Dry, Amberlyst 35 Dry, Amberlyst 36 Dry, Amberlyst 70, Amberlyst DT, Tulsion 66 MP, Lewatit K2640, Lewatit K 2431, and Relite EXC8D sulfonic acid cation-exchange resins have been determined experimentally. The activities of these catalysts in different types of reactions have been compared. The rate constants of all reactions decrease on passing from 1-nonene to straight-chain hexadecene. In the alkylations of phenol with straight-chain alkenes, the ortho-alkylphenol/para-alkylphenol ratio is practically equal to the statistical ratio for all of the resins examined in their operation range.     

<Emphasis Type="Italic">trans</Emphasis>-10,<Emphasis Type="Italic">cis</Emphasis>-12 Conjugated Linoleic Acid Enhances Endurance Capacity by Increasing Fatty Acid Oxidation and Reducing Glycogen Utilization in Mice

The supplementation of conjugated linoleic acid (CLA) has been shown to improve endurance by enhancing fat oxidation during exercise in rodents and humans. This study was designed to investigate the isomer-specific effects of CLA on endurance capacity and energy metabolism in mice during exercise. Male 129Sv/J mice were divided into three dietary groups and fed treatment diet for 6 weeks; control, 0.5 % cis-9,trans-11 (c9,t11) CLA, or 0.5 % trans-10,cis-12 (t10,c12) CLA. Dietary t10,c12 CLA induced a significant increase in maximum running time and distance until exhaustion with a dramatic reduction of total adipose depots compared to a control group, but there were no significant changes in endurance with the c9,t11 CLA treatment. Serum triacylglycerol and non-esterified fatty acid concentrations were significantly lower in the t10,c12 fed mice after exercise compared to control and the c9,t11 CLA fed-animals. Glycogen contents in livers of the t10,c12 fed-mice were higher than those in control mice, concomitant with reduction of serum l-lactate level. There were no differences in non-exercise physical activity among all treatment groups. In addition, the mRNA expression levels of carnitine palmitoyl transferase 1β, uncoupling protein 2 and peroxisome proliferator-activated receptor δ (PPARδ) in skeletal muscle during exercise were significantly up-regulated by the t10,c12 CLA but not the c9,t11 CLA. These results suggest that the t10,c12 CLA is responsible for improving endurance exercise capacity by promoting fat oxidation with a reduction of the consumption of stored liver glycogen, potentially mediated via PPARδ dependent mechanisms.     

Non-cytotoxic poly(amino acid) with excellent thermo-sensitivity from <Emphasis Type="Italic">L</Emphasis>-lysine and <Emphasis Type="Italic">L</Emphasis>-aspartic acid as a hydrophobic drug carrier

The thermo-sensitive poly(amino acid)s have aroused great concern due to their good biocompatibility, chirality and multi-functional groups. In this investigation, a group of poly(L-lysine ester -co- N-propionyl-L-aspartic acid)s (PLPA) with excellent thermo-sensitivity and non-cytotoxicity have been successfully synthesized by the polycondensation between α/ε-amino groups of L-lysine and α/γ-carboxyls from L-aspartic acid. The structure and properties of PLPA including monomers are characterized by FTIR, ¹H NMR, UV, DSC, GPC, SEM, Contact angle measurement, CCK-8 Cell Counting Kit assess and Confocal laser-scanning microscopy (CLSM). Among four designed PLPAs, only PLPAs possessing methyl/ethyl in the ester moiety show a reversible lower critical solution temperature (LCST) of 21.3–36.2 °C, very close to body temperature. The thermo-sensitivity of PLPAs is strongly affected by the polymer structure, its molecular weight and concentration. The contact angle measurement clearly reveals the effect of pendant groups and temperature on the hydrophlilicity/hydrophobicity of PLPAs. Furthermore, the viability of HeLa cells in 0.01–100 μg/mL PLPA solution is found to be in a range of 90–102% after 24, 48 and 72 h of incubation, indicating its no cytotoxicity. PLPA can facilely form a spherical nano-scale particle with core-shell structure via its thermo-sensitivity. CLSM observations manifest that the curcumin-loaded PLPA particles clearly internalize into the cellular inside. Overall, this noncytotoxic PLPA with excellent thermo-sensitivity is expected to be a promising material in the biomedical fields such as a hydrophobic drug carrier.     

Phytofabrication,Characterization and Antibacterial Activity of <Emphasis Type="Italic">Cassia auriculata</Emphasis> Leaf Extract Derived CuO Nanoparticles

A simple, eco-friendly phytosynthesis of copper oxide nanoparticles (CuO NPs) using Cassia auriculata leaf extract was reported. The prepared CuO NPs was characterized by UV–vis spectroscopy which exhibited the surface plasmon resonance (SPR) band at 380–385 nm. TEM and EDX analysis confirmed that CuO NPs were spherical and in size range of 30–35 nm with identified elements Cu and O. X-ray diffraction (XRD) spectrum showed the crystalline nature of the prepared CuO NPs. FTIR spectrum confirmed the presence of Cu–O functional groups. CuO NPs showed significant antibacterial efficacy against all the tested bacterial strains, i.e., Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. CuO NPs showed strong antibacterial action against B. subtilis and E. coli than P. aeruginosa and S. aureus. The results of this study revealed that C. auriculata leaf extract was found to be an effective bio-reducing agent for CuO NPs synthesis and also the antibacterial efficacy of phytofabricated CuO may be useful for its applications in medical and textile industries.     

Comparison of dye degradation potential of biosynthesized copper oxide,manganese dioxide,and silver nanoparticles using <Emphasis Type="Italic">Kalopanax pictus</Emphasis> plant extract

Copper(II) oxide (CuO), manganese dioxide (MnO₂), and silver (Ag) nanoparticles were synthesized using Kalopanax pictus plant extract. The nanoparticle synthesis was monitored using UV-visible spectra. The occurrence of each peak at 368, 404, and 438 nm wavelength indicated the synthesis of CuO, MnO₂, and Ag nanoparticles, respectively. The synthesized nanoparticles were characterized by X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. Catalytic potentials of the synthesized nanoparticles were compared to degrade two typical acidic and basic dyes (Congo red and Safranin O). The degradation ability of MnO₂ nanoparticles against Congo red was higher than that of Ag and CuO nanoparticles. All three types of nanoparticles showed a similar degradation ability against Safranin O over 80%. This study demonstrates that biologically synthesized nanoparticles using Kalopanax pictus are good agents for degradation of dyes.     

Shape selective catalysis in methylation of toluene: Development,challenges and perspectives

Toluene methylation with methanol offers an alternative method to produce p-xylene by gathering methyl group directly from C1 chemical sources. It supplies a “molecular engineering” process to realize directional conversion of toluene/methanol molecules by selective catalysis in complicated methylation system. In this review, we introduce the synthesis method of p-xylene, the development history of methylation catalysts and reaction mechanism, and the effect of reaction condition in para-selective technical process. If constructing p-xylene as the single target product, the major challenge to develop para-selective toluene methylation is to improve the p-xylene selectivity without, or as little as possible, losing the fraction of methanol for methylation. To reach higher yield of p-xylene and more methanol usage in methylation, zeolite catalyst design should consider improving mass transfer and afterwards covering external acid sites by surface modification to get short “micro-tunnels” with shape selectivity. A solid understanding of mass transfer will benefit realizing the aim of converting more methanol feedstock into para-methyl group.

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Microbial Conversion of Arachidonic Acid to Arachidonyl Alcohol by a New <Emphasis Type="Italic">Acinetobacter</Emphasis> Species

Arachidonyl alcohol rarely occurs in natural oils. It can be used as a substrate for production of several ether lipids possessing beneficial functions. Although arachidonyl alcohol has been produced on a laboratory scale by the chemical reduction of arachidonic acid, it will be difficult to scale up this process for industrial application. The aim of this study was to develop a new bioprocess for converting arachidonic acid to arachidonyl alcohol. Screening was conducted using 11 wax ester- (esters of fatty acids and fatty alcohols) producing strains reported in our previous study, and a single-cell oil containing arachidonic acid. A new strain, Acinetobacter species N-476-2, most effectively converted arachidonic acid to arachidonyl alcohol, which accumulated inside the cells as a wax ester. GC–MS, FT–IR, and NMR analyses showed that this strain reduced the carboxyl group of 5-cis,8-cis,11-cis,14-cis-arachidonic acid to a hydroxyl group without altering the position or configuration of the double bonds; the product was identified as 5-cis,8-cis,11-cis,14-cis-arachidonyl alcohol. A time-course study of cultivation showed that the amount of arachidonyl alcohol produced by the strain after 4 days was 2.2 mg/mL culture. The bioprocess using Acinetobacter sp. N-476-2 can be applied to the large-scale production of arachidonyl alcohol.     

(1<Emphasis Type="Italic">S</Emphasis>,3<Emphasis Type="Italic">R</Emphasis>)-<Emphasis Type="Italic">cis</Emphasis>-Chrysanthemyl Tiglate: Sex Pheromone of the Striped Mealybug, <Emphasis Type="Italic">Ferrisia virgata</Emphasis>

Derivatives of 2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylic acid (chrysanthemic acid) are classic natural pyrethroids discovered in pyrethrum plants and show insecticidal activity. Chrysanthemic acid, with two asymmetric carbons, has four possible stereoisomers, and most natural pyrethroids have the (1R,3R)-trans configuration. Interestingly, chrysanthemic acid–related structures are also found in insect sex pheromones; carboxylic esters of (1R,3R)-trans-(2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl)methanol (chrysanthemyl alcohol) have been reported from two mealybug species. In the present study, another ester of chrysanthemyl alcohol was discovered from the striped mealybug, Ferrisia virgata (Cockerell), as its pheromone. By means of gas chromatography–mass spectrometry, nuclear magnetic resonance spectrometry, and high-performance liquid chromatography analyses using a chiral stationary phase column and authentic standards, the pheromone was identified as (1S,3R)-(?)-cis-chrysanthemyl tiglate. The (1S,3R)-enantiomer strongly attracted adult males in a greenhouse trapping bioassay, whereas the other enantiomers showed only weak activity. The cis configuration of the chrysanthemic acid–related structure appears to be relatively scarce in nature, and this is the first example reported from arthropods.     

Influence of <Emphasis Type="Italic">Cissus quadrangularis</Emphasis> Stabilized AgNPs and Its Structural,Optical, Antibacterial Analysis: A Comparative Study

Silver nanoparticles (AgNPs) was synthesized by using AgCl precursor with the stabilizing agent Cissus quadrangularis by precipitation method and the obtained particles were characterized by X-ray diffraction (XRD) analysis, Field Emission Scanning Electron Microscope (FESEM) and UV–Visible (UV–Vis) analysis. The influence of a stabilizing agent on AgNPs was compared with non-stabilized AgNPs through the experimental analysis. The XRD patterns show pure face center cubic structure for both samples, whereas the crystallite size is found to be low in stabilizer used samples. FESEM image and the UV–Vis spectra show less agglomeration and blue shift respectively, for stabilizer used AgNPs, indicating small size particles. Photoluminescence spectra show the emission band at 390 nm for both samples. Antibacterial tests show good activity against Pseudomonas aeruginosa for stabilizer used AgNPs. The study concluded that Cissus quadrangularis can be used as a potential stabilizing agent for preparing AgNPs from AgCl, for optical and biomedical applications.     

Synthesis of Structured Lipids Containing Pinolenic Acid at the <Emphasis Type="Italic">sn</Emphasis>-2 Position via Lipase-Catalyzed Acidolysis

Lipase-catalyzed acidolysis of a modified pine nut oil (MPNO)—the pine nut oil was obtained from Pinus koraiensis Siebold &; Zucch.—with capric acid was studied in a continuous packed bed reactor (PBR) using Lipozyme RM IM from Rhizomucor miehei as a biocatalyst. The MPNO containing pinolenic acid (PLA) at the sn-2 position of the triacylglycerol (TAG) backbone was prepared by lipase-catalyzed redistribution of pine nut oil using Novozym 435 from Candida antarctica. The effects of the water content in the reaction mixture and the molar ratio of substrates on the extent of the acidolysis reaction as a function of residence time in a PBR were investigated. The water content of the reaction mixture significantly influenced both the rate of acidolysis and the degree of acyl migration, but the molar ratio of substrates affected only the rate of acidolysis. The optimum water content and molar ratio for synthesis of the structured lipid containing PLA at the sn-2 position and capric acid at the sn-1,3 positions of the TAG backbone were 0.04%, and 1:5 (MPNO to capric acid), respectively.     

Synthesis of novel polymer brushes of poly(acrylonitrile-<Emphasis Type="Italic">g</Emphasis>-<Emphasis Type="Italic">N,N</Emphasis>ʹ-dimethylaminoethyl methacrylate) by nitrile modification

Functional polymer brushes of poly(acrylonitrile-g-N,N?-dimethylaminoethyl methacrylate) were efficiently synthesized by a novel approach of combining Cu(0)-mediated controlled/“living” radical polymerization and nitrile click chemistry. The poly(acrylonitrile-g-N,N?-dimethylaminoethyl methacrylate) as a promising material exhibited excellent hydrophile–lipohile balance in the process of self-assembly and could autonomously develop the orderly structure micelle in N,N?-dimethylformamide/water mixture solvent for the potential application of a new drug delivery carrier. In the process of self-assembly, polyacrylonitrile acted as a backbone of the functional polymer brushes due to its hydrophobic feature and poly(N,N?-dimethylaminoethyl methacrylate) as the branch of functional polymer brushes due to its hydrophilic characteristic, which both were prepared by Cu(0)-mediated controlled/“living” radical polymerization with ethyl-bromoisobutyrate as initiator. Poly(N,N?-dimethylaminoethyl methacrylate) containing azide end group was synthesized by substitution reaction of poly(N,N?-dimethylaminoethyl methacrylate) containing bromine end groups with sodium azide in N,N?-dimethylformamide. The click reaction between the nitrile of polyacrylonitrile and the azide group of poly(N,N?-dimethylaminoethyl methacrylate) was carried out under ammonium chloride as catalyst in N,N?-dimethylformamide. The polymer was further confirmed by GPC, FTIR, ¹H NMR and TGA. Meanwhile, the micelles with different morphologies were observed by TEM, and the particle diameter distribution of self-assembled micelle from the PAN-g-PDMAEMA brushes was determined by DLS.     

<Emphasis Type="Bold">Photo-sensitive bio-based copolymer containing cholic acids: novel functional materials for 248nm photoresist</Emphasis>

Cholic acid is a class of biological compounds that exhibit valuable properties, and have been applied in many fields due to its special chemical structures for many areas. In this study, poly[(methacrylic acid tert-butyl cholate ester)-co-(acetoxy styrene)] [P(MATC-co-AS)] was synthesized from cholic acid, then the final copolymer poly[(methacrylic acid tert-butyl cholate ester)-co-(p-hydrostyrene)] [P(MATC-co-HS)] was obtained after P(MATC-co-AS) was hydrolysized. The structure and properties of the copolymers were determined through nuclear magnetic resonance, gel permeation chromatography, UV spectrometry, thermogravimetric analysis, and differential scanning calorimetry. The ultraviolet spectra of the copolymers indicate that they exhibit excellent optical transmittance at 248 nm. Moreover, the photolithography performance of a positive-tone photoresist based on the copolymers were evaluated using an KrF laser exposure system. The results indicate that a resolution of 0.25 μm could be achieved at a low exposure dose.