Synthesis of polysulfone-b-polystyrene block copolymers by mechanistic transformation from condensation polymerization to free radical polymerization

Synthesis of polysulfone-b-polystyrene (PSU-b-PS) block copolymers by a combination of condensation polymerization and free radical polymerization processes are described. First, a new macroazoinitiator (MAI) containing polysulfone (PSU) units was prepared by direct esterification of 4,4-azobis(4-cyanopentanoic acid) with α,ω-hydroxyl PSU telechelics at ambient conditions. The macroinitiator was then used in conventional free radical polymerization of styrene leading to the formation of desired block copolymers. In this process, initiating macroradicals were generated by thermal cleavage of the azo group present in the macroazoinitiator structure. The precursor polysulfone macroazoinitiator (PSU-MAI) and resulting block copolymers were characterized by spectral analysis using FT-IR, ¹H-NMR, GPC, TGA, and DSC.     

The global research progress of enzymatic processing of oils with Omega 3 polyunsaturated fatty acids（网络首发、推荐阅读）

综述ω-3多不饱和脂肪酸（polyunsaturated fatty acids,PUFA）作为一类必需脂肪酸（essential fatty acids,EFAs）,主要来源为海产品中的鱼油,对多种人体疾病治疗和/或预防具有的积极作用。梳理了酶法制备富含ω-3多不饱和脂肪酸油脂的研究最新进展（截至2019年）,讨论很多不同产品的营养功效、不同脂肪酸组成的结构脂质、ω-3多不饱和脂肪酸浓缩液、磷脂的酶促酯交换制备技术及应用,历年研究发现,可以通过改善油脂中ω-3多不饱和脂肪酸含量的方式提高其在饮食中的摄入量。由于酶法反应条件温和,尤其是脂肪酶特异性强,且从生物利用度角度ω-3多不饱和脂肪酸在脂质分子上的位置与其含量同等重要,因此相对于化学法,酶法制备含ω-3多不饱和脂肪酸的油脂因安全高效而更受青睐。     

Influence of gel preparation concentration on statistical mechanics of poly(dialkylaminoethyl methacrylate) gels on the basis of scaling concept: Toward tunable elasticity and thermomechanical parameters

In order to evaluate the scaling parameters of weakly cationic crosslinked network structures, poly(dialkylaminoethyl methacrylate)-based hydrogels were synthesized via free-radical crosslinking in aqueous solution varying systematically concentration of pregel solution. Based on the gel-preparation concentration, variation in structural properties, effective crosslinking density, average molecular weight of polymer chains, and thermodynamic parameters from combined swelling and elasticity results were discussed using the scaling theory to predict various exponent identities. The concentration dependence of compressive elastic modulus as-prepared state was described by a power-law relationship with the exponent of m = 3.55 indicating the importance of the trapped entanglements. Two structural characteristics, the network chain length N and the average molecular weight of polymer chains have inverse dependence on the gel-preparation concentration in the matrix, while the compressive moduli and effective crosslinking density show completely direct dependence. Experimentally determined N values of PDMAEMA hydrogels first decrease with increasing up to 0.2972 and the dependence of N on the gel-preparation concentration gives the relation with a scaling parameter n = −1.80, which coincides with the prediction of scaling theory. Acceptable agreement was found between the estimate of crosslink density fluctuations deduced from mechanical measurements and the results derived from independent swelling observations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48350.     

Evolving Technologies and Strategies for Combating Antibacterial Resistance in the Advent of the Postantibiotic Era

The threats posed by the impending “postantibiotic era” have put forward urgent challenges to be overcome by providing new diagnostic and therapeutic regimes for improved diagnosis and treatment of bacterial infections. Antibiotic resistance and incurable bacterial infections are especially important in a society faced with rapid demographic changes. With very few new antibiotics in the drug development pipeline, not being able to match the pace of antimicrobial resistance evolution, developments within other fields such as materials sciences and medical technologies are required to realize innovative antibacterial approaches. This progress report presents recent advances in especially nanotechnology‐based approaches and their concomitant use with complementary antibacterial treatments. Synergistically improved antibacterial activity can be reached by considering novel, promising approaches such as photodynamic and photothermal therapy as well as cold atmospheric pressure treatments as complementary strategies to fight against antibacterial resistance. Moreover, this report describes how these novel technologies can be further improved especially by integration of nanomaterials into the currently applied single modal strategies against bacterial infections.     

Bioimprinted Immobilization of <Emphasis Type="Italic">Candida antarctica</Emphasis> Lipase A for Concentration of Omega-3 Polyunsaturated Fatty Acids

Bioimprinting and immobilization of Candida antarctica lipase A (CALA) was optimized by response surface methodology to improve its selectivity for concentration of omega-3 polyunsaturated fatty acids (PUFA) by lipase-catalyzed ethanolysis of salmon oil obtained from salmon by-products. Enzyme-to-support ratio, oleic acid concentration, and immobilization time were the factors investigated. Total omega-3 PUFA lost to the ethyl esters (EE) fraction was monitored in relation to the varying levels of the factors. Results showed that the second-order polynomial model generated adequately fitted the experimental data. The most critical factor was the enzyme-to-support ratio, which led to decreased recovery of omega-3 PUFA in the glycerides fraction with increasing levels of enzyme amount. Optimum conditions were selected as follows: enzyme-to-support ratio, 0.2 (w/w); oleic acid concentration, 50 mM; immobilization time, 85 min. The total omega-3 PUFA lost to the EE fraction through ethanolysis of salmon oil decreased from 3.76 to 1.47 (mol%) under the optimum conditions.     

Turbo Code with Modified LLR and Performance Analysis for Bluetooth Packets in Indoor Environments

Most of the restrictions in indoor environments do not exist for outdoor sites. The main limitations for indoors are the attenuation of walls and the multipath fading effects. The signal propagation is limited by the standard free space path loss in outdoor environments or free space. The loss in free space is usually equal to the range squared whereas the loss exponent for indoors is more like the 4th power. This study investigates the performance of turbo codes with modified Maximum-A-Posteriori (MAP) decoding algorithm for Bluetooth data packets in indoor environments over the frequency selective Rayleigh fading channels; which are also called as indoor wireless communication channels. In order to reduce the computational complexity of turbo decoders, MAP algorithm is modified in this study. Bit error rate (BER) versus energy of bit-to-noise ratio (E _b /N _o ) of modified MAP algorithms for Bluetooth data packets at 2.4 GHz industrial-scientific-medical (ISM) band are evaluated by means of computer simulations. Thus, modified logarithmic likelihood ratio (LLR) method can significantly reduce the computational complexity of the MAP algorithm. Furthermore, the performances of different types of forward error correction (FEC) coding for Bluetooth data packets are compared in the study.     

Evaluation of energy efficiency of fifth generation mobile systems

There has been active research worldwide to develop the next generation, i.e., fifth generation, wireless network. Next generation mobile communication networks are broadening their spectrum to higher frequency bands (above 6 GHz) to support a high data rate up to multigigabits per second. This work examines how to substantially improve energy efficiency for next fifth generation mobile communication systems. It is depicted how by limited exchange of information between neighboring base stations it is possible to maintain quality of service, over a range of traffic loads, while enabling inactive base stations to sleep. Performance of distributed energy efficient topology management schemes are compared against the system without topology management. Performance evaluation is examined using both analytical and simulation based models. Extensive numerical results show that the schemes deliver a significant energy reduction in energy consumption in the mobile network systems.     

A new flap from the dorsum of the first intermetacarpal area: the first dorsal intermetacarpal flap

Soft-tissue reconstruction of the hand still remains a challenge for plastic and reconstructive surgeons. Several flaps have been described to cover soft-tissue defects of the digits and the hand. In the first web region, there are some communications between the intermediate artery arising from the dorsal branch of the radial artery and the volar arteries of the thumb and the index finger. Depending on these communications, a new distally based flap is raised from the first dorsal intermetacarpal area. This flap has been used to cover various defects of the thumb in four patients and the distal radial side of the palmar area in one patient. Donor sites have been closed primarily except in one patient. There were no complications, and the results show that this flap is useful to cover soft-tissue defects of the thumb and proximal phalanx of the index finger as well as the radial side of the palmar and dorsal surfaces of the hand.