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Yanfeng Guo,Mei Han,Weiliu Yan,Jianzhong Xu,Weiguo Zhang 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.3
In Corynebacterium glutamicum, acetohydroxyacid synthase (AHAS, encoded by ilvBN) is regulated bythe end products in biosynthesis pathway, which catalyzesthe first common reaction in the biosynthesis of branchedchainamino acids (BCAAs). In this study, conserved A42,A89 and K136 residues in AHAS regulatory subunit werechosen for site-directed mutagenesis, and the resultingmutations A42V, A89V and K136E exhibited higherresistance to inhibition by BCAAs than wild type AHAS. Furthermore, double-mutation was carried out on A42V,A89V and K136E mutations. Expectedly, A42V-A89Vmutation exhibited nearly complete resistance to inhibitionby all three BCAAs, which retained above 93% enzymeactivity even at 10 mM. Strains were further studied toinvestigate the effects of over-expressing different mutantilvBN on the biosynthesis of BCAAs. It was found thatproduction of BCAAs was increased with the increase ofresistance to BCAAs. However, the increase of isoleucineand leucine was slower than valine which showed asignificant increase (up to 86.30 mM). Furthermore, strainsharboring plasmids with different mutant ilvBN couldsignificantly decrease production of alanine (main byproduct). This work gives additional understanding of rolesof A42, A89 and K136 residues and makes the A42V,A89V, K136E and A42V-A89V mutations a good startingpoint for further development by protein engineering.
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Liu Haonan,Wu Han,Wang Ying,Wang Fan,Liu Xiaoli,Zhou Jianzhong 한국응용생명화학회 2021 Applied Biological Chemistry (Appl Biol Chem) Vol.64 No.6
A blueberry anthocyanin extract was obtained from Brightwell blueberry fruits cultivated in eastern China and the extraction and purification conditions were optimized. The components of the anthocyanin extract were identified using ultra-performance liquid chromatography-electrospray ionization interface-mass spectrometer. The antioxidant and antibacterial activities of the blueberry fruit supernatant (BFS), blueberry anthocyanin crude extract (BCE), and blueberry anthocyanin rich extract (BRE) were evaluated. The extraction yield was 1.79 ± 0.0014 mg/g under the following optimal conditions: 1:20 solid-to-liquid ratio (v/w), 24 h, 34 °C, and 90% ethanol containing 0.21% (v/v) hydrochloric acid. With regard to purification, anthocyanin purity increased 19.1-fold. Nine fractions were identified as the glycosides of delphinidin, cyanidin, petunidin, and malvidin. The biological activities of the blueberry anthocyanin extract were improved through extraction and purification. Compared with BFS and BCE, BRE had a higher DPPH radical scavenging activity ( EC50 = 0.51 mg/mL), ABTS antioxidant capacity ( EC50 = 0.32 mg/mL), and oxygen radical absorbance capacity (0.43 mmol Trolox/g). Furthermore, BRE (2 mg/mL) showed a maximum of 84.64 ± 0.35% reduction in the biofilm biomass of Listeria monocytogenes and the inhibition zone given by BRE against Escherichia coli was 16.04 ± 0.38 mm. BRE showed the highest antioxidant capacities and obvious antibacterial effects against foodrelated microorganisms than the other samples. Therefore, BRE can be used as a natural antioxidant and antibacterial agent and has potential health advantages and food industry applications.
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Andrews, Jeffrey G.,Buzzi, Stefano,Choi, Wan,Hanly, Stephen V.,Lozano, Angel,Soong, Anthony C. K.,Zhang, Jianzhong Charlie IEEE 2014 IEEE journal on selected areas in communications Vol.32 No.6
<P>What will 5G be? What it will <I>not</I> be is an incremental advance on 4G. The previous four generations of cellular technology have each been a major paradigm shift that has broken backward compatibility. Indeed, 5G will need to be a paradigm shift that includes very high carrier frequencies with massive bandwidths, extreme base station and device densities, and unprecedented numbers of antennas. However, unlike the previous four generations, it will also be highly integrative: tying any new 5G air interface and spectrum together with LTE and WiFi to provide universal high-rate coverage and a seamless user experience. To support this, the core network will also have to reach unprecedented levels of flexibility and intelligence, spectrum regulation will need to be rethought and improved, and energy and cost efficiencies will become even more critical considerations. This paper discusses all of these topics, identifying key challenges for future research and preliminary 5G standardization activities, while providing a comprehensive overview of the current literature, and in particular of the papers appearing in this special issue.</P>
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Full Dimension MIMO (FD-MIMO): Demonstrating Commercial Feasibility
Xu, Gary,Yang Li,Jin Yuan,Monroe, Robert,Rajagopal, Sridhar,Ramakrishna, Sudhir,Young Han Nam,Ji-Yun Seol,Jaeweon Kim,Gul, Malik Muhammad Usman,Aziz, Ahsan,Jianzhong Zhang IEEE 2017 IEEE journal on selected areas in communications Vol.35 No.8
<P>Massive multi-input multi-output (MIMO) is shown to significantly increase spectral efficiency by exploiting a large number of antennas to support high-order multiuser MIMO. In 3GPP Release-13, a full-dimension MIMO (FD-MIMO) technology was introduced to address practical aspects for massive MIMO in cellular systems; extensive simulations show 2-4 times capacity gain compared with current LTE systems. FD-MIMO has been identified as one of the key 5G technologies and is being continuously improved in 3GPP new radio standards. However, several practical challenges such as interference mitigation among MIMO streams for a large number of users with limited channel feedback, hardware limitations, such as calibration errors that limit the precoding capabilities need to be addressed carefully. A proof of concept (PoC) base-station and user equipment (UE) prototype has been designed to validate the potential of FD-MIMO technology and demonstrate commercial implementation feasibility. In this paper, we present theory and architecture behind an FD-MIMO prototype and share the field test results with LTE-based UEs in a multi-user MIMO setup. We also analyze the impact of transmitter and receiver calibration errors on the performance of the FD-MIMO system.</P>
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Inactivation of Vibrio parahaemolyticus by Aqueous Ozone
( Lifang Feng ),( Kuo Zhang ),( Mengsha Gao ),( Chunwei Shi ),( Caiyun Ge ),( Daofeng Qu ),( Junli Zhu ),( Yugang Shi ),( Jianzhong Han ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.8
Vibrio parahaemolyticus contamination causes serious foodborne illness and has become a global health problem. As a disinfectant, aqueous ozone can effectively kill a number of bacteria, viruses, parasites, and other microorganisms. In this study, three factors, namely, the aqueous ozone concentration, the exposure time, and the bacterial density, were analyzed by response surface methodology, and the aqueous ozone concentration was the most influential factor in the sterilization ratio. Under low aqueous ozone concentrations (less than 0.125 mg/l), the bacterial cell membranes remained intact, and the ozone was detoxified by intracellular antioxidant enzymes (e.g., superoxide dismutase and catalase). Under high aqueous ozone concentrations (more than 1 mg/l), cell membranes were damaged by the degree of peripheral electronegativity at the cell surface and the concentration of lactate dehydrogenase released into the extracellular space, and the ultrastructures of the cells were confirmed by transmission electron microscopy. Aqueous ozone penetrated the cells through leaking membranes, inactivated the enzymes, inhibited almost all the genes, and degraded the genetic materials of gDNA and total RNA, which eventually led to cell death.
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