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( Zhaofeng Li ),( Si-qian Chen ),( Xiao Cao ),( Lin Li ),( Jie Zhu ),( Hongpeng Yu ) 한국미생물생명공학회(구 한국산업미생물학회) 2021 Journal of microbiology and biotechnology Vol.31 No.3
Bacterial cellulose (BC) is widely used in the food industry for products such as nata de coco. The mechanical properties of BC hydrogels, including stiffness and viscoelasticity, are determined by the hydrated fibril network. Generally, Komagataeibacter bacteria produce gluconic acids in a glucose medium, which may affect the pH, structure and mechanical properties of BC. In this work, the effect of pH buffer on the yields of Komagataeibacter hansenii strain ATCC 53582 was studied. The bacterium in a phosphate and phthalate buffer with low ionic strength produced a good BC yield (5.16 and 4.63 g/l respectively), but there was a substantial reduction in pH due to the accumulation of gluconic acid. However, the addition of gluconic acid enhanced the polymer density and mechanical properties of BC hydrogels. The effect was similar to that of the bacteria using glycerol in another carbon metabolism circuit, which provided good pH stability and a higher conversion rate of carbon. This study may broaden the understanding of how carbon sources affect BC biosynthesis.
Bin Li,Lei Wang,Lingqia Su,Sheng Chen,Zhaofeng Li,Jian Chen,Jing Wu 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.6
OmpA signal peptide mediated cgt gene from Paenibacillus macerans JFB05-01 was cloned and expressed in E. coli BL21 (DE3). The effects of glycine and Triton X-100 on extracellular production of α-cyclodextrin glycosyltransferase (α-CGTase) were investigated. When supplemented with Gly or Triton X-100 to the culture media individually, the secreted extracellular enzyme reached 32or 33 U/mL at 48 h of cultivation, respectively. When supplemented with Gly and Triton X-100 together, the extracellular α-CGTase activity reached 48 U/mL after 48 h cultivation, which was 20-fold of the control group without any additives. Analysis of membrane permeability demonstrated that addition of glycine and Triton X-100enhanced the permeability of both outer and inner membrane. The potential mechanism of the enhanced protein secretion was discussed.
A new geopolymeric grout blended completely weathered granite with blast-furnace slag
Zhang, Jian,Li, Shucai,Li, Zhaofeng,Li, Hengtian,Du, Junqi,Gao, Yifan,Liu, Chao,Qi, Yanhai,Wang, Wenlong Techno-Press 2020 Advances in concrete construction Vol.9 No.6
In order to reduce the usage of cement slurry in grouting engineering and consume the tunnel excavation waste soil, a new geopolymeric grouting material (GGM) was prepared by combine completely weathered granite (CWG) and blast-furnace slag (BFS), which can be applied to in-situ grouting treatment of completely weathered granite strata. The results showed CWG could participate in the geopolymerization process, and GGM slurry has the characteristics of short setting time, high flowability, low viscosity, high stone rate and high mechanical strength, and a design method of grouting pressure based on viscosity evolution was proposed. By adjusted the content of completely weathered granite and alkali activator concentration, the setting time of GGM were ranged from 5 to 30 minutes, the flowability was more than 23.5 cm, the stone rate was higher than 90%, the compressive strength of 28 days were 7.8-16.9 MPa, the porosity were below 30%. This provides a novel grouting treatment and utilizing excavated soil of tunnels in the similar strata.
An Extension Theoretical Model for Grouting Effect Evaluation in Sand Stratum of Metro Construction
Jiwen Bai,Shucai Li,Yujing Jiang,Rentai Liu,Zhaofeng Li,Wei Li 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.5
Water-rich sand stratum is a common geological disaster source for the metro construction in coastal cities, and grouting is the most widely-used and efficient method to improve the characteristics of tunnel-surrounding rock. The grouting effect evaluation plays a key role in guaranteeing the subsequent construction safety. However, the grouting effect evaluation is a complex problem since it involves influence factors of uncertainty and variability. In order to comprehensively and quantitatively evaluate the grouting quality and guarantee the safety of metro construction, an extension theoretical model for grouting effect evaluation in water-rich sand stratum is established. Firstly, according to the geological and engineering influence factors, rock mass strength, permeability of surrounding rock, attitude of stratum, moisture content, grouting material, and grouting technology are selected as the grouting effect evaluation indexes, which make up the evaluation index system. The dimensionless method is used to avoid the influence of the unit and order of magnitude of each index, and index weight of each factor is ascertained by entropy-information theory. Also, through the grouting information of typical waterrich sand stratum and expert experience, the grouting effect evaluation grade classification is achieved. Combining with the extension theory and measured data, the correlation degree of each evaluation grade is obtained. Finally, according to the correlation degree identification criteria, the grouting effect evaluation categories can be judged. In the engineering application, the water-rich sand stratum grouting effect in Qingdao metro is evaluated based on the proposed model. The results show that the evaluation grade agrees well with the excavation situation. The extension theoretical model provides an effective method for grouting effect evaluation in water-rich sand stratum.
New avenues to heavy right-handed neutrinos with pair production at hadronic colliders
Kang, Zhaofeng,Ko, P.,Li, Jinmian American Physical Society 2016 Physical Review D Vol.93 No.7
<P>In many models incorporating the type-I seesaw mechanism, the right-handed neutrino (N) couples to heavy vector/scalar bosons and thereby has resonant pair production. It has barely received attention thus far; however, it may provide the best avenue to probe TeV scale N without requiring anomalously large mixing between N and the active neutrino nu(L). In this paper we explore the discovery prospects of (mainly heavy) N pair production at the 14 TeV LHC and future 100 TeV pp collider, based on the three signatures: (1) trilepton from N (-> lW(l)) N (-> lW(h)) with W-l/h being the leptonically/hadronically decaying W; (2) boosted di-Higgs boson plus E-T from N (-> nu(L)h) N (-> nu(L)h); (3) a single boosted Higgs boson with leptons and E-T from N (-> lW(l)) N (-> nu(L)h). At the 100 TeV collider, we also consider the situation when the Higgs boson is overboosted, thus losing its jet substructure. Interpreting our tentative results in the benchmark model, the local B-L model, we find that the (multi-) TeV scale N can be probed at the (100) 14 TeV colliders.</P>
Uncover compressed supersymmetry via boosted bosons from the heavier stop/sbottom
Kang, Zhaofeng,Li, Jinmian,Zhang, Mengchao Springer-Verlag 2017 European Physical Journal C Vol.77 No.6
<P>A light stop around the weak scale is a hopeful messenger of natural supersymmetry (SUSY), but it has not shown up at the current stage of LHC. Such a situation raises the question of the fate of natural SUSY. Actually, a relatively light stop can easily be hidden in a compressed spectra such as mild mass degeneracy between stop and neutralino plus top quark. Searching for such a stop at the LHC is a challenge. On the other hand, in terms of the argument of natural SUSY, other members in the stop sector, including a heavier stop (t) over tilde (2) and lighter sbottom (b) over tilde (1) (both assumed to be left-handedlike), are also supposed to be relatively light and therefore searching for them would provide an alternative method to probe natural SUSY with a compressed spectra. In this paper we consider quasi-natural SUSY which tolerates relatively heavy colored partners near the TeV scale, with a moderately large mass gap between the heavier members and the lightest stop. Then W/Z/h as companions of (t) over tilde (2) and (b) over tilde (1) decaying into (t) over tilde (1) generically are well boosted, and they, along with other visible particles from (t) over tilde (1) decay, are a good probe to study compressed SUSY. We find that the resulting search strategy with boosted bosons can have better sensitivity than those utilizing multi-leptons.</P>