Enhancement of transglutaminase production in Streptomyces mobaraensis DSM 40587 by non-nutritional stress conditions: Effects of heat shock, alcohols, and salt treatments

Lili Zhang,Lanwei Zhang,Huaxi Yi,Ming Du,Yingchun Zhang,Xue Han,Zhen Feng,Jingyan Li,Yuehua Jiao,Yanhe Zhang,Chunfeng Guo 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.7

Stress-mediated bioprocess is a strategy designed to enhance biological target productivity. In this study,an attempt was made to enhance transglutaminase (TGase) production by Streptomyces mobaraensis by using different stress conditions including heat shock, alcohols and salt stress. Results showed that the effects of stress on TGase production depended on the type applied. For heat shock, TGase production (1.32 U/ml) was recorded maximum in the culture treated at 48 h post inoculation in water bath at 60 oC for 1 min. For alcohols treatment, the maximum activity of TGase (1.77 and 1.75 U/ml) was obtained when 3% methanol was added into the medium at 0 or 24 h of fermentation. However, a 3.5-fold increased production of TGase (3.8 U/ml) was observed in the medium supplemented with 0.2mol/l MgCl2 compared with the basic medium at the beginning of fermentation. In conclusion, TGase production from S. mobaraensis was improved by heat shock, methanol and salt stress treatments, MgCl2 stress was the most effective.

Nonradiative energy transfer between colloidal quantum dot-phosphors and nanopillar nitride LEDs.

Zhang, Fan,Liu, Jie,You, Guanjun,Zhang, Chunfeng,Mohney, Suzanne E,Park, Min Joo,Kwak, Joon Seop,Wang, Yongqiang,Koleske, Daniel D,Xu, Jian Optical Society of America 2012 Optics express Vol.20 No.2

<P>We present in this communication our study of the nonradiative energy transfer between colloidal quantum dot (QD) phosphors and nitride nanopillar light emitting diodes (LEDs). An epitaxial p-i-n InGaN/GaN multiple quantum-well (QW) heterostructure was patterned and dry-etched to form dense arrays of nanopillars using a novel etch mask consisting of self-assembled In3Sn clusters. Colloidal QD phosphors have been deposited into the gaps between the nanopillars, leading to sidewall coupling between the QDs and InGaN QW emitters. In this approach, close QW-QD contact and a low-resistance design of the LED contact layer were achieved simultaneously. Strong non-radiative energy transfer was observed from the InGaN QW to the colloidal QD phosphors, which led to a 263% enhancement in effective internal quantum efficiency for the QDs incorporated in the nanopillar LEDs, as compared to those deposited over planar LED structures. Time-resolved photoluminescence was used to characterize the energy transfer process between the QW and QDs. The measured rate of non-radiative QD-QW energy-transfer agrees well with the value calculated from the quantum efficiency data for the QDs in the nanopillar LED.</P>

Identification by Inner-pages of Characteristics of Naxi Manuscripts Collected by Harvard-Yenching Institute

Chunfeng ZHANG 세계한자학회 2016 世界漢字硏究 Vol.2 No.1

The Impact of Carrier Transport Confinement on the Energy Transfer Between InGaN/GaN Quantum‐Well Nanorods and Colloidal Nanocrystals

Jiang, Bin,Zhang, Chunfeng,Wang, Xiaoyong,Park, Min Joo,Kwak, Joon Seop,Xu, Jian,Zhang, Huichao,Zhang, Jiayu,Xue, Fei,Xiao, Min WILEY‐VCH Verlag 2012 Advanced Functional Materials Vol.22 No.15

<P><B>Abstract</B></P><P>The energy transfer (ET) between InGaN/GaN multiple‐quantum‐well (MQW) nanorods (NRs) and semiconductor nanocrystals (NCs) for efficient color conversion is studied. An exceptional contribution of carrier transport confinement to the ET mechanisms is observed in the proximal side‐wall coupling system, which consists of InGaN/GaN NRs and CdSe NCs. Under relatively low or high excitation, the ET rate shows different carrier‐density dependence, resulting from different electron‐hole configurations, i.e., bound excitons and free carriers. In the localized exciton regime, the ET rate decreases when increasing temperature from 20 K to 200 K. However, in the free‐carrier regime, the ET rate varies insignificantly in the same temperature range. The temperature dependence in this NR‐NC coupling system is different from that in the previously studied planar MQW‐NC coupling system. It is suggested that the carrier transport confinement in NRs is a major factor for these divergences. The highly efficient ET with efficiency up to 80% shows a promising potential of using such NR‐NC coupled structures for ET‐pumped, NC‐based, light‐emitting devices.</P>

9.73% Efficiency Nonfullerene All Organic Small Molecule Solar Cells with Absorption-Complementary Donor and Acceptor

Bin, Haijun,Yang, Yankang,Zhang, Zhi-Guo,Ye, Long,Ghasemi, Masoud,Chen, Shanshan,Zhang, Yindong,Zhang, Chunfeng,Sun, Chenkai,Xue, Lingwei,Yang, Changduk,Ade, Harald,Li, Yongfang American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.14

<P>In the last two years, polymer solar cells (PSCs) developed quickly with n-type organic semiconductor (n-OSs) as acceptor. In contrast, the research progress of nonfullerene organic solar cells (OSCs) with organic small molecule as donor and the n-OS as acceptor lags behind. Here, we synthesized a D-A structured medium bandgap organic small molecule H11 with bithienyl-benzodithiophene (BDTT) as central donor unit and fluorobenzo-triazole as acceptor unit, and achieved a power conversion efficiency (PCE) of 9.73% for the all organic small molecules OSCs with H11 as donor and a low bandgap n-OS IDIC as acceptor. A control molecule H12 without thiophene conjugated side chains on the BDT unit was also synthesized for investigating the effect of the thiophene conjugated side chains on the photovoltaic performance of the p-type organic semiconductors (p-OSs). Compared with H12, the 2D-conjugated H11 with thiophene conjugated side chains shows intense absorption, low-lying HOMO energy level, higher hole mobility and ordered bimodal crystallite packing in the blend films. Moreover, a larger interaction parameter (chi) was observed in the H11 blends calculated from Hansen solubility parameters and differential scanning calorimetry measurements. These special features combined with the complementary absorption of H11 donor and IDIC acceptor resulted in the best PCE of 9.73% for nonfullerene all small molecule OSCs up to date. Our results indicate that fluorobenzotriazole based 2D conjugated p-OSs are promising medium bandgap donors in the nonfullerene OSCs.</P>

Damage identification using chaotic excitation

Chunfeng Wan,Tadanobu Sato,Zhishen Wu,Jian Zhang 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.11 No.1

Vibration-based damage detection methods are popular for structural health monitoring. However, they can only detect fairly large damages. Usually impact pulse, ambient vibrations and sine-wave forces are applied as the excitations. In this paper, we propose the method to use the chaotic excitation to vibrate structures. The attractors built from the output responses are used for the minor damage detection. After the damage is detected, it is further quantified using the Kalman Filter. Simulations are conducted. A 5-story building is subjected to chaotic excitation. The structural responses and related attractors are analyzed. The results show that the attractor distances increase monotonously with the increase of the damage degree. Therefore, damages, including minor damages, can be effectively detected using the proposed approach. With the Kalman Filter, damage which has the stiffness decrease of about 5% or lower can be quantified. The proposed approach will be helpful for detecting and evaluating minor damages at the early stage.

Structural damage identification with output-only measurements using modified Jaya algorithm and Tikhonov regularization method

Chunfeng Wan,Guangcai Zhang,Liyu Xie,Songtao Xue 국제구조공학회 2023 Smart Structures and Systems, An International Jou Vol.31 No.3

The absence of excitation measurements may pose a big challenge in the application of structural damage identification owing to the fact that substantial effort is needed to reconstruct or identify unknown input force. To address this issue, in this paper, an iterative strategy, a synergy of Tikhonov regularization method for force identification and modified Jaya algorithm (M-Jaya) for stiffness parameter identification, is developed for damage identification with partial output-only responses. On the one hand, the probabilistic clustering learning technique and nonlinear updating equation are introduced to improve the performance of standard Jaya algorithm. On the other hand, to deal with the difficulty of selection the appropriate regularization parameters in traditional Tikhonov regularization, an improved L-curve method based on B-spline interpolation function is presented. The applicability and effectiveness of the iterative strategy for simultaneous identification of structural damages and unknown input excitation is validated by numerical simulation on a 21-bar truss structure subjected to ambient excitation under noise free and contaminated measurements cases, as well as a series of experimental tests on a five-floor steel frame structure excited by sinusoidal force. The results from these numerical and experimental studies demonstrate that the proposed identification strategy can accurately and effectively identify damage locations and extents without the requirement of force measurements. The proposed M-Jaya algorithm provides more satisfactory performance than genetic algorithm, Gaussian bare-bones artificial bee colony and Jaya algorithm.

Analytical Solution for Borehole Contraction Caused by Radial Unloading

Chunfeng Zhao,Yanzong Yang,Cheng Zhao,Changguang Zhang 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.1

The elastoplastic analysis of a borehole was conducted using the elasto-brittle-plastic softening model and the Mohr-Coulomb strength theory, combined with earth pressure formulas derived from the cavity wall formula and Berezantsev’s formula. The analytical solutions for the plastic zone radius and radial displacement are presented. Using the curves of the plastic zone radius and the wall displacement of the borehole versus borehole depth, the influence of various factors such as different earth pressure calculation methods, the unloading process, the borehole radius, and the dilatation and softening effects are discussed in detail. According to the results, the use of the cavity wall formula leads to convergence easily and both the knee points for the plastic zone radius and the wall displacement of the borehole occur in the shallower part of the borehole. On the other hand, according to Berezantsev’s formula, the earth pressure increases along the shaft, following a hyperbolic curve, and continues to increase at the bottom of the borehole. Because there is a significant difference between the results of the previous two methods, an integrated method for estimating the earth pressure should be derived using the in situ results. The unloading process, borehole radius used in the design, dilatation and softening effects, etc., also have a great influence on the plastic zone radius and the wall displacement of the borehole. Moreover, the borehole radius has huge impact on the boundary force.

Damage identification using chaotic excitation

Wan, Chunfeng,Sato, Tadanobu,Wu, Zhishen,Zhang, Jian Techno-Press 2013 Smart Structures and Systems, An International Jou Vol.11 No.1

Vibration-based damage detection methods are popular for structural health monitoring. However, they can only detect fairly large damages. Usually impact pulse, ambient vibrations and sine-wave forces are applied as the excitations. In this paper, we propose the method to use the chaotic excitation to vibrate structures. The attractors built from the output responses are used for the minor damage detection. After the damage is detected, it is further quantified using the Kalman Filter. Simulations are conducted. A 5-story building is subjected to chaotic excitation. The structural responses and related attractors are analyzed. The results show that the attractor distances increase monotonously with the increase of the damage degree. Therefore, damages, including minor damages, can be effectively detected using the proposed approach. With the Kalman Filter, damage which has the stiffness decrease of about 5% or lower can be quantified. The proposed approach will be helpful for detecting and evaluating minor damages at the early stage.

Reducing the efficiency droop by lateral carrier confinement in InGaN/GaN quantum-well nanorods.

Shi, Chentian,Zhang, Chunfeng,Yang, Fan,Park, Min Joo,Kwak, Joon Seop,Jung, Sukkoo,Choi, Yoon-Ho,Wang, Xiaoyong,Xiao, Min Optical Society of America 2014 Optics express Vol.22 No.suppl3

<P>Efficiency droop is a major obstacle facing high-power application of InGaN/GaN quantum-well (QW) light-emitting diodes (LEDs). In this paper, we report the suppression of efficiency droop induced by the process of density-activated defect recombination in nanorod structures of a-plane InGaN/GaN QWs. In the high carrier density regime, the retained emission efficiency in a dry-etched nanorod sample is observed to be over two times higher than that in its parent QW sample. We further argue that such improvement is a net effect that the lateral carrier confinement overcomes the increased surface trapping introduced during fabrication.</P>