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Development of a dual temperature control system for isoprene biosynthesis in

《化学科学与工程前沿(英文)》 2022年 第16卷 第7期   页码 1079-1089 doi: 10.1007/s11705-021-2088-0

摘要: Conflict between cell growth and product accumulation is frequently encountered in the biosynthesis of secondary metabolites. To address the growth-production conflict in yeast strains harboring the isoprene synthetic pathway in the mitochondria, the dynamic control of isoprene biosynthesis was explored. A dual temperature regulation system was developed through engineering and expression regulation of the transcriptional activator Gal4p. A cold-sensitive mutant, Gal4ep19, was created by directed evolution of Gal4p based on an internally developed growth-based high-throughput screening method and expressed under the heat-shock promoter PSSA4 to control the expression of PGAL-driven pathway genes in the mitochondria. Compared to the control strain with constitutively expressed wild-type Gal4p, the dual temperature regulation strategy led to 34.5% and 72% improvements in cell growth and isoprene production, respectively. This study reports the creation of the first cold-sensitive variants of Gal4p by directed evolution and provides a dual temperature control system for yeast engineering that may also be conducive to the biosynthesis of other high-value natural products.

关键词: transcriptional activator     directed evolution     dynamic control     heat-shock     isoprene    

Expression of heat shock protein gp96 in osteosarcoma and its clinical significance

GUO Weichun, CHEN Anmin

《医学前沿(英文)》 2008年 第2卷 第2期   页码 200-203 doi: 10.1007/s11684-008-0038-6

摘要: This study aims to detect the expression of heat shock protein gp96 (HSPgp96) in osteosarcoma and explore its role in anti-tumor immunity. Expression of HSPgp96 in 45 cases of osteosarcoma, including 24 cases of the osteoblast type, 21 cases of chondroblast type and 5 cases of normal bone tissue were detected by immunohistochemistry (IHC). The expression rate of HSPgp96 was 100% (45/45) in osteosarcoma, compared with 20% (1/5) in normal bone tissue. The average positive cell rates were 97.23% and 0.48% in osteosarcoma and normal bone tissue, respectively, and the difference between them was significant ( < 0.01). The positive cell rates in osteoblast type and chondroblast type were 97.78% and 96.56%, respectively, and the difference had no statistical significance ( > 0.05). The expression degree of HSPgp96 in osteosarcoma had a clear correlation with the pathologic degree ( < 0.05), while it had no relationship with the clinical stage ( > 0.05). The expression of HSPgp96 is high in osteosarcoma and it may be a significant index for judgment of malignancy degree and an important target site of anti-tumor immunity.

Alteration of heat shock protein 20 expression in preeclamptic patients and its effect in vascular and

Fanfan Li, Mengzhou He, Meitao Yang, Yao Fan, Yun Chen, Xi Xia, Yin Xie, Dongrui Deng

《医学前沿(英文)》 2018年 第12卷 第5期   页码 542-549 doi: 10.1007/s11684-017-0576-x

摘要:

Preeclampsia (PE) is a pregnancy-specific, multi-system disorder and the leading cause of maternal and perinatal morbidity and mortality in obstetrics worldwide. Excessive vasoconstriction and dysregulated coagulation function are closely associated with PE. Heat shock protein 20 (HSP20) is ubiquitously expressed under normal physiological conditions and has important roles in vascular dilatation and suppression of platelet aggregation. However, the role of HSP20 in the pathogenesis of PE remains unclear. In this study, we collected chorionic plate resistance arteries (CPAs) and serum from 118 healthy pregnant women and 80 women with PE and detected the levels of HSP20 and its phosphorylated form. Both HSP20 and phosphorylated HSP20 were downregulated in CPAs from women with PE. Comparison of the vasodilative ability of CPAs from the two groups showed impaired relaxation responses to acetyl choline in preeclamptic vessels. In addition to the reduced HSP20 in serum from women with PE, the platelet distribution width and mean platelet volume were also decreased, and the activated partial thromboplastin time and thromboplastin time were elevated. With regard to the vital roles of HSP20 in mediating vasorelaxation and coagulation function, the decreased HSP20 might contribute to the pathogenesis of PE.

关键词: preeclampsia     heat shock protein 20     vascular relaxation     coagulation-fibrinolytic system    

Beneficial effect of arginine vasopressin on hemorrhagic shock through improving the vascular reactivity

LI Tao, YANG Guangming, XU Jing, LIU Jiancang, LIU Liangming

《医学前沿(英文)》 2008年 第2卷 第3期   页码 248-254 doi: 10.1007/s11684-008-0047-5

摘要: The vascular reactivity and calcium sensitivity were decreased following hemorrhagic shock. Arginine vasopressin (AVP) was beneficial to endotoxic, infectious/septic and hemorrhagic shock. Our previous studies found that Rho kinase played an important role in the occurrence of calcium desensitization following shock. It was reported that AVP was with stimulation effect of Rho kinase. So we hypothesized that AVP might have beneficial effect on shock via activation of Rho kinase to regulate the calcium sensitivity and vascular reactivity. Hemorrhagic shock (40 mmHg for 2 h) Wistar rats were adopted to observe the effects of small dose of AVP on hemodynamics, 24-h survival rate, the pressor effect of norepinephrine (NE) and the contractility of superior mesenteric artery (SMA). Isolated SMAs from hemorrhagic shock rats were adopted to observe the effects of AVP on vascular reactivity and calcium sensitivity and its relationship to Rho kinase with an isolated organ perfusion system. The results show that AVP at the concentration of 0.1 U/kg and 0.4 U/kg significantly improved the hemodynamic parameters and the 24-h survival rate of hemorrhagic shock rats. Meanwhile, these dosages of AVP significantly increased the pressor effect of NE and the contractile response of SMA to NE. Y-27632 (3 ?g/kg), a Rho kinase specific inhibitor, abolished the beneficial effects of AVP. , the calcium sensitivity and vascular reactivity of SMA to calcium and NE were significantly decreased following hemorrhagic shock. AVP at the concentration of 0.5 nmol/L and 5 nmol/L significantly increased the calcium sensitivity and vascular reactivity. These effects of AVP were abolished by Y-27632 (10 ?mol/L). Taken together, the results suggest that AVP at 0.1 U/kg and 0.4 U/kg is beneficial to hemorrhagic shock by improving the vascular reactivity, which involves activation of Rho kinase.

Centrifuge experiment and numerical analysis of an air-backed plate subjected to underwater shock loading

Zhijie HUANG, Xiaodan REN, Zuyu CHEN, Daosheng LING

《结构与土木工程前沿(英文)》 2019年 第13卷 第6期   页码 1350-1362 doi: 10.1007/s11709-019-0559-x

摘要: In this study, systematic centrifuge experiments and numerical studies are conducted to investigate the effect of shock loads due to an underwater explosion on the dynamic responses of an air-backed steel plate. Numerical simulations with three different models of pressure time history generated by underwater explosion were carried out. The first model of pressure time history was measured in test. The second model to predict the time history of shock wave pressure from an underwater explosion was created by Cole in 1948. Coefficients of Cole’s formulas are determined experimentally. The third model was developed by Zamyshlyaev and Yakovlev in 1973. All of them are implemented into the numerical model to calculate the shock responses of the plate. Simulated peak strains obtained from the three models are compared with the experimental results, yielding average relative differences of 21.39%, 45.73%, and 13.92%, respectively. The Russell error technique is used to quantitatively analyze the correlation between the numerical and experimental results. Quantitative analysis shows that the simulated strains for most measurement points on the steel plate are acceptable. By changing the scaled distances, different shock impulses were obtained and exerted on the steel plate. Systematic numerical studies are performed to investigate the effect of the accumulated shock impulse on the peak strains. The numerical and experimental results suggest that the peak strains are strongly dependent on the accumulated shock impulse.

关键词: underwater explosion     centrifuge experiment     shock load     dynamic response     accumulated shock impulse    

Influence evaluation of loading conditions during pressurized thermal shock transients based on thermal-hydraulics

Jinya KATSUYAMA, Shumpei UNO, Tadashi WATANABE, Yinsheng LI

《机械工程前沿(英文)》 2018年 第13卷 第4期   页码 563-570 doi: 10.1007/s11465-018-0487-9

摘要:

The thermal hydraulic (TH) behavior of coo-lant water is a key factor in the structural integrity assessments on reactor pressure vessels (RPVs) of pressurized water reactors (PWRs) under pressurized thermal shock (PTS) events, because the TH behavior may affect the loading conditions in the assessment. From the viewpoint of TH behavior, configuration of plant equipment and their dimensions, and operator action time considerably influence various parameters, such as the temperature and flow rate of coolant water and inner pressure. In this study, to investigate the influence of the operator action time on TH behavior during a PTS event, we developed an analysis model for a typical Japanese PWR plant, including the RPV and the main components of both primary and secondary systems, and performed TH analyses by using a system analysis code called RELAP5. We applied two different operator action times based on the Japanese and the United States (US) rules: Operators may act after 10 min (Japanese rules) and 30 min (the US rules) after the occurrence of PTS events. Based on the results of TH analysis with different operator action times, we also performed structural analyses for evaluating thermal-stress distributions in the RPV during PTS events as loading conditions in the structural integrity assessment. From the analysis results, it was clarified that differences in operator action times significantly affect TH behavior and loading conditions, as the Japanese rule may lead to lower stresses than that under the US rule because an earlier operator action caused lower pressure in the RPV.

关键词: structural integrity     reactor pressure vessel     pressurized thermal shock     thermal hydraulic analysis     pressurized water reactor     weld residual stress    

Absorption heat pump for waste heat reuse: current states and future development

Zhenyuan XU, Ruzhu WANG

《能源前沿(英文)》 2017年 第11卷 第4期   页码 414-436 doi: 10.1007/s11708-017-0507-1

摘要: Absorption heat pump attracts increasing attention due to its advantages in low grade thermal energy utilization. It can be applied for waste heat reuse to save energy consumption, reduce environment pollution, and bring considerable economic benefit. In this paper, three important aspects for absorption heat pump for waste heat reuse are reviewed. In the first part, different absorption heat pump cycles are classified and introduced. Absorption heat pumps for heat amplification and absorption heat transformer for temperature upgrading are included. Both basic single effect cycles and advanced cycles for better performance are introduced. In the second part, different working pairs, including the water based working pairs, ammonia based working pairs, alcohol based working pairs, and halogenated hydrocarbon based working pairs, for absorption heat pump are classified based on the refrigerant. In the third part, the applications of the absorption heat pump and absorption heat transformer for waste heat reuse in different industries are introduced. Based on the reviews in the three aspects, essential summary and future perspective are presented at last.

关键词: absorption     heat pump     heat transformer     waste heat     working pair    

岩石冲击损伤演化规律数值流形方法模拟

刘红岩,吕淑然,秦四清

《中国工程科学》 2007年 第9卷 第3期   页码 92-96

摘要:

采用应力波衰减损伤模型对仅适用于模拟基于线性本构关系和恒定载荷作用下物体变形规律的数值 流形程序进行了扩展;利用扩展后的程序对岩石长杆在冲击载荷作用下的损伤演化规律进行了模拟,得出了不 同位置点处的损伤演化曲线和材料总体的损伤演化曲线。模拟结果表明,损伤的增加主要集中在冲击载荷作用的初始阶段,随着时间的推移,应力波强度衰减,损伤将不再明显增加。

关键词: 岩石     数值流形方法     冲击损伤     演化规律    

Effects on mechanical properties in electron beam welding of TC4 alloy by laser shock processing

LU Jinzhong, ZHANG Yongkang, KONG Dejun, REN Xudong, GE Tao, ZOU Shikun

《机械工程前沿(英文)》 2007年 第2卷 第4期   页码 478-482 doi: 10.1007/s11465-007-0083-x

摘要: The surface of TC4 titanium alloy welding line by electron beam welding (EBW) was processed by high power Q-switched and repetition-rate Nd: glass laser. Effects of laser power and spot diameter on residual stress and micro-hardness of the TC4 alloy welding line by laser shock processing (LSP) have been analyzed. Results show that residual stresses almost do not change as laser power is 45.9 J, spot diameter is φ9 mm; While laser power is 45.9 J, spot diameter less than φ3 mm, the distribution of residual stress in welding line occurs obvious variation, which residual stress increase obviously with spot diameter decrease. When power density is bigger than 1.8×10 W/cm, residual stresses of electron beam welding line occur change by LSP, which improve obviously residual stress distribution; while laser power is bigger than 1.2×10 W/cm, the surface micro-hardness of electron beam welding line occurs change by LSP, which improve obviously micro-hardness distribution. Mechanical properties of TC4 titanium alloy welding line will be improved by LSP, which provides experimental foundation for further controlling the distributions of residual stress and micro-hardness during laser shock processing.

Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over

Krishnendu Bhattacharyya

《化学科学与工程前沿(英文)》 2011年 第5卷 第3期   页码 376-384 doi: 10.1007/s11705-011-1121-0

摘要: In this paper, an investigation is made to study the effects of radiation and heat source/sink on the unsteady boundary layer flow and heat transfer past a shrinking sheet with suction/injection. The flow is permeated by an externally applied magnetic field normal to the plane of flow. The self-similar equations corresponding to the velocity and temperature fields are obtained, and then solved numerically by finite difference method using quasilinearization technique. The study reveals that the momentum boundary layer thickness increases with increasing unsteadiness and decreases with magnetic field. The thermal boundary layer thickness decreases with Prandtl number, radiation parameter and heat sink parameter, but it increases with heat source parameter. Moreover, increasing unsteadiness, magnetic field strength, radiation and heat sink strength boost the heat transfer.

关键词: MHD boundary layer     unsteady flow     heat transfer     thermal radiation     heat source/sink     shrinking sheet     suction/injection    

水下钻孔爆破的爆炸冲击波测试与分析

柯松林,李琳娜,司剑峰,钟冬望

《中国工程科学》 2014年 第16卷 第11期   页码 103-106

摘要:

以厦门港古雷航道水下炸礁为例,分析了水下钻孔爆破的水击波形成特征,并通过爆破区的水中冲击波压力监测,实测了不同距离处的水击波压力大小和变化规律,研究了水中冲击波压力幅值、正压作用时间等作用特性,得到了水击波传播衰减公式。研究成果对指导工程设计施工和环境安全评估具有参考意义。

关键词: 水下钻孔爆破     水中冲击波     压力特性    

Heat-spreading analysis of a heat sink base embedded with a heat pipe

B. V. BORGMEYER, H. B. MA,

《能源前沿(英文)》 2010年 第4卷 第2期   页码 143-148 doi: 10.1007/s11708-010-0013-1

摘要: A simplified model predicting the heat transfer performance of a heat sink base with a high thermal conductivity was developed. Numerical analysis was performed using the commercial software FLUENT. The investigation indicates that for heat sink bases with a high effective thermal conductivity, such as the base embedded with a typical heat pipe, the entire heat sink can be modeled as a flat plate with a uniform temperature and an effective convection heat transfer coefficient. This simplified model can be used to determine the heat transfer performance of a heat sink embedded with a typical heat pipe or vapor chamber.

关键词: heat pipe     heat sink     microprocessor heat removal    

Application of entransy dissipation theory in heat convection

Mingtian XU, Jiangfeng GUO, Lin CHENG,

《能源前沿(英文)》 2009年 第3卷 第4期   页码 402-405 doi: 10.1007/s11708-009-0055-4

摘要: In the present work, formulas for calculating the rates of the local thermodynamic entransy dissipation in convective heat transfer in general, and the internal and external flows in particular, are established. Practically, these results may facilitate the application of entransy dissipation theory in thermal engineering. Theoretically they shed light on solving the contradiction of the minimum entropy production principle with balance equations in continuum mechanics.

关键词: entransy dissipation     heat convection     heat exchanger    

化爆冲击波在90°拐角通道内的到时规律

沈俊,李永池,庞伟宾,

《中国工程科学》 2006年 第8卷 第3期   页码 53-57

摘要:

对空气冲击波在90°拐角坑道内传播的到时规律及其影响因素进行了实验研究,在无量纲分析基础上建立了简化的工程模型。通过对实验数据拟合建立了可以对高能炸药在90°拐角坑道内爆炸产生的空气冲击波到达时间进行预计的公式,利用该公式可以进一步求得空气冲击波在90°拐角坑道内的传播速度。

关键词: 内爆炸     冲击波     到时    

Experimental investigation of liquid metal alloy based mini-channel heat exchanger for high power electronic

Manli LUO, Jing LIU

《能源前沿(英文)》 2013年 第7卷 第4期   页码 479-486 doi: 10.1007/s11708-013-0277-3

摘要: There is currently a growing demand for developing efficient techniques for cooling integrated electronic devices with ever increasing heat generation power. To better tackle the high-density heat dissipation difficulty within the limited space, this paper is dedicated to clarify the heat transfer behaviors of the liquid metal flowing in mini-channel exchangers with different geometric configurations. A series of comparative experiments using liquid metal alloy Ga68%In20%Sn12% as coolant were conducted under prescribed mass flow rates in three kinds of heat exchangers with varied geometric sizes. Meanwhile, numerical simulations for the heat exchangers under the same working conditions were also performed which well interpreted the experimental measurements. The simulated heat sources were all cooled down by these three heat dissipation apparatuses and the exchanger with the smallest channel width was found to have the largest mean heat transfer coefficient at all conditions due to its much larger heat transfer area. Further, the present work has also developed a correlation equation for characterizing the Nusselt number depending on Peclet number, which is applicable to the low Peclet number case with constant heat flux in the hydrodynamically developed and thermally developing region in the rectangular channel. This study is expected to provide valuable reference for designing future liquid metal based mini-channel heat exchanger.

关键词: heat exchanger     liquid metal     mini-channel     heat dissipation     heat transfer coefficient    

标题 作者 时间 类型 操作

Development of a dual temperature control system for isoprene biosynthesis in

期刊论文

Expression of heat shock protein gp96 in osteosarcoma and its clinical significance

GUO Weichun, CHEN Anmin

期刊论文

Alteration of heat shock protein 20 expression in preeclamptic patients and its effect in vascular and

Fanfan Li, Mengzhou He, Meitao Yang, Yao Fan, Yun Chen, Xi Xia, Yin Xie, Dongrui Deng

期刊论文

Beneficial effect of arginine vasopressin on hemorrhagic shock through improving the vascular reactivity

LI Tao, YANG Guangming, XU Jing, LIU Jiancang, LIU Liangming

期刊论文

Centrifuge experiment and numerical analysis of an air-backed plate subjected to underwater shock loading

Zhijie HUANG, Xiaodan REN, Zuyu CHEN, Daosheng LING

期刊论文

Influence evaluation of loading conditions during pressurized thermal shock transients based on thermal-hydraulics

Jinya KATSUYAMA, Shumpei UNO, Tadashi WATANABE, Yinsheng LI

期刊论文

Absorption heat pump for waste heat reuse: current states and future development

Zhenyuan XU, Ruzhu WANG

期刊论文

岩石冲击损伤演化规律数值流形方法模拟

刘红岩,吕淑然,秦四清

期刊论文

Effects on mechanical properties in electron beam welding of TC4 alloy by laser shock processing

LU Jinzhong, ZHANG Yongkang, KONG Dejun, REN Xudong, GE Tao, ZOU Shikun

期刊论文

Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over

Krishnendu Bhattacharyya

期刊论文

水下钻孔爆破的爆炸冲击波测试与分析

柯松林,李琳娜,司剑峰,钟冬望

期刊论文

Heat-spreading analysis of a heat sink base embedded with a heat pipe

B. V. BORGMEYER, H. B. MA,

期刊论文

Application of entransy dissipation theory in heat convection

Mingtian XU, Jiangfeng GUO, Lin CHENG,

期刊论文

化爆冲击波在90°拐角通道内的到时规律

沈俊,李永池,庞伟宾,

期刊论文

Experimental investigation of liquid metal alloy based mini-channel heat exchanger for high power electronic

Manli LUO, Jing LIU

期刊论文