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1.
In this paper, we propose a mechanism on how to construct long MDS self-dual codes from short ones. These codes are special types of generalized Reed-Solomon (GRS) codes or extended generalized Reed-Solomon codes. The main tool is utilizing additive structure or multiplicative structure on finite fields. By applying this method, more MDS self-dual codes can be constructed. 相似文献
2.
Stimulated by a suggestion of the late Professor Jack D. Dunitz, that perdeuterated Janus face cycloalkanes may be more polar than their unlabelled forms, the deuterated isotopologue of all cis-1,2,3,4,5,6-hexafluorocyclohexane ([2H6]- 1a ) and all cis-1,2,3,4-tetrafluorocyclopentane ([2H6]- 3a ) were prepared. Computation at the B3LYP−D3 level indicated that [2H6]- 1a is not more polar than its protio form 1, however perdeuterated cyclopentane [2H6]- 3a may indeed be more polar than 3 , although the magnitude is predicted to be small. None-the-less retention time analysis on a reverse phase GC/MS column of an add-mix of 3 and [2H6]- 3a gave some indication that the per-deuterated isotopologue 3a was detected marginally before the unlabelled compound consistent with increased polarity associated with perdeuteration. 相似文献
3.
The effect of tetramethylenedicarboxylic dibenzoylhydrazide (designated here as TMC) on the nonisothermal and isothermal crystallization behavior of PLA was investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide angle X-ray diffraction (WAXD). TMC shows excellent nucleating effect on PLA. With the addition of 0.05 wt% TMC, the crystallization half-time of PLA decreases from 26.06 to 6.13 min at 130 °C. The isothermal crystallization data were further analyzed by the Avrami model. The values of the Avrami exponent of the blends are comparable to that of neat PLA, indicating that the presence of TMC does not change the crystallization mechanism of the matrix. The observation from POM and WAXD measurements showed that the presence of TMC increases significantly the nuclei density of PLA but has no discernible effect on its crystalline structure. 相似文献
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《Proceedings of the Combustion Institute》2023,39(3):3303-3311
Lignin pyrolysis involves complex radical reactions, whereas the radical chain process, especially the influence of aliphatic substituents, has been rarely studied. Herein, the typical β-O-4 lignin dimer, phenethyl phenyl ether (PPE), and three aliphatic substituted derivatives of PPE, namely α-OH substituted, β-CH2OH substituted, and α,β-disubstituted PPE (αPPE, βPPE, and αβPPE) were employed as model compounds. DFT calculations, electronic analyses, and fast pyrolysis experiments were combined to investigate three core steps of the radical chain mechanism in lignin pyrolysis, i.e., homolysis, hydrogen abstraction, and radical decomposition. The pathway involving successive Cβ-O homolysis → α-hydrogen abstraction → Cβ-O breakage of α-dehydrogenated radical is dominated for the pyrolysis of aliphatic substituted β-O-4 linked lignin, with the formation of phenolics. The hydrogen abstraction reactions at the Cα site are obviously superior to those at other sites for PPE derivatives, due to the p-π conjugate stability. Notably, α-hydrogen abstraction can be significantly promoted by the π-electron-dispersing α-OH substitution. The decomposition step of dehydrogenated radicals can be facilitated by the electron-donating β-CH2OH substitution, where the Cβ-O breakage of the α-dehydrogenated radical is dominant. Totally, aliphatic substituents can improve the radical growth stage and change the competitiveness of the hydrogen abstraction and radical decomposition reactions. The fast pyrolysis experiments of PPE and αPPE gave direct proof that the generation of characteristic products from the radical chain process, i.e., benzaldehyde and phenylacetaldehyde, was enhanced by the α-OH substitution. The present work offers the potential to give a comprehensive image of the radical chain mechanism in lignin pyrolysis. 相似文献
7.
Pumpkin seed oil (PSO), which is a valuable compound with high nutritional value used for the prevention of various chronic diseases, is prone to oxidation. In this work, small and uniform (su) ovalbumin (OVA) and pectin (PEC) were used to stabilize PSO in the form of an emulsion. The results showed that suOVA-PEC-PSO emulsion with a droplet size of 9.82 ± 0.05 μm was successfully self-assembled from PSO, PEC, and suOVA solution (with a droplet size of 230.13 ± 14.10 nm) treated with 300 W ultrasound, owing to the formation of a more stable interfacial film on the surface of droplets. The interfacial, rheological, emulsifying, and antioxidant properties of the suOVA-PES-PSO emulsions were excellent, owing to the synergistic effects between PEC and suOVA solution. Moreover, the physical stability of the suOVA-PEC-PSO emulsions to salt stress, a freeze-thaw cycle, and heat treatment was also increased and the oxidation of linolenic acid was notably delayed. These results have extended the food-related applications of OVA and PSO, and provide a promising foundation for further exploration of the self-assembly of composite emulsions by small and uniform proteins. 相似文献
8.
Yanfeng Chu Huan Yu Yunti Zhang Guangyan Zhang Yingying Ma Renxi Zhuo Xulin Jiang 《Journal of polymer science. Part A, Polymer chemistry》2014,52(23):3346-3355
Biodegradable amphiphilic ABC Y‐shaped triblock copolymer (MPBC) containing PEG, PBLA, and PCL segments was synthesized via the combination of enzymatic ring‐opening polymerization (ROP) of epsilon‐caprolactone, ROP of BLA‐N‐carboxyanhydride and click chemistry, where PEG, PBLA, and PCL are poly(ethylene glycol), poly(benzyl‐l ‐aspartate), and polycaprolactone, respectively. Propynylamine was employed as ROP initiator for the preparation of alkynyl‐terminated PBLA and methyloxy‐PEG with hydroxyl and azide groups at the chain‐end was used as enzymatic ROP initiator for synthesis of monoazido‐midfunctionalized block copolymer mPEG‐b‐PCL. The subsequent click reaction led to the formation of Y‐shaped asymmetric heteroarm terpolymer MPBC. The polymer structures were characterized by different analyses. The MPBC terpolymer self‐assembled into micelles and physically encapsulated drug doxorubicin (DOX) to form DOX‐loaded micelles, which showed good stability and slow drug release. In vitro cytotoxicity study indicated that the MPBC micelles were nontoxic and the DOX‐loaded micelles displayed obvious anticancer activity similar to free DOX against HeLa cells. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3346–3355 相似文献
9.
《中国化学快报》2020,31(8):2137-2141
To develop a novel food preservation technology for efficiently enhance bactericidal activity in a long term, hollow mesoporous silica spheres (HMSS) with regular nanostructures were applied to encapsulate natural organic antimicrobial agents. The chemical structures, morphologies and thermal stabilities of linalool, HMSS and linalool-functionalized hollow mesoporous silica spheres (L-HMSS) nanoparticles were evaluated by polarimeter, field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), fourier transform infrared (FT-IR), thermal gravimetric analyzer (TGA), nitrogen adsorption-desorption, zeta potential and small angle X-ray diffraction (SXRD). The results show that the linalool was successfully introduced into the cavities of HMSS, and the inorganic host exhibited a high loading capacity of about 1500 mg/g. In addition, after 48 h of incubation, the minimum bactericidal concentrations (MBC) of L-HMSS against Escherichia coli (E. coli), Salmonella enterica (S. enterica) and Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes) were decreased to be 4 (< 5) mg/mL and 8 (< 10) mg/mL, respectively. These results revealed linalool-functionalized hollow mesoporous spheres could efficiently improve the bactericidal activities of the organic component. Furthermore, SEM images clearly showed that L-HMSS indeed had an extremely inhibitory effect against gram-negative (E. coli) and gram-positive (S. aureus) by breaking the structure of the cell membrane. This research is of great significance in the application of linalool in nano-delivery system as well as food industry. 相似文献
10.
Multiarm star block copolymers hyperbranched polyethylenimine-b-poly(2-hydroxyethyl methacrylate) (HPEI-b-PHEMA) with average 28 PHEMA arms have been prepared by atom transfer radical polymerization (ATRP) of HEMA in a mixed solvent of methanol and water using a core-first strategy. The hyperbranched macroinitiator employed was prepared on the basis of well-defined hyperbranched polyethylenimine with Mw/Mn of 1.04 by amidation with 2-bromo-isobutyryl bromide. The polymerization condition was optimized to prepare star copolymers with narrow dispersity, and the variables included the volume ratio of methanol to water, the molar ratio of initiating site to CuCl and the molar ratio of [CuCl]:[CuBr2]. Under the optimized polymerization condition, the lowest Mw/Mn value of the obtained star copolymers was around 1.3. Kinetic analysis showed that an induction period existed in the polymerization of HEMA. After this induction period, a linear dependence of ln([M]0/[M]t) on time was observed. The obtained HPEI-b-PHEMA could adsorb hydrophilic molecules. The comparison with the star copolymer with hydrophobic core and hydrophilic PHEMA shell verified that both the hydrophilic core and shell could host the hydrophilic guests, but the amidated HPEI core was more effective than the PHEMA shell. 相似文献