The entransy dissipation expression for a convection heat transfer process was derived by applying entransy conception,and the heat transfer optimizations for N-stream heat exchangers were investigated at different conditions by applying entransy dissipation extremum principle.The results show that the temperature-difference field between the hot and cold fluids is uniform if the entransy dissipation reaches a minimum for a given total heat duty or if the total heat duty reaches a maximum for a given total entransy dissipation on condition that any temperature-difference between hot and cold fluids involved in heat transfer can be controlled independently,that the temperature-difference field between the hot and cold fluids maintain its own uniformity if any heat duty or entransy dissipation between hot and cold fluids involved in heat transfer is given independently,and that the optimum temperature difference between the different hot and cold fluids maintain different uniformity whether the entransy dissipation reaches a minimum for a given total heat duty or the total heat duty reaches a maximum for a given total entransy dissipation when heat transfer exists within any possible hot and cold fluids.

<正>教学冲突是存在于师生之间、生生之间的对立与排斥的态势,是常态存在的文化性冲突,对教学群体和师生个体发展而言,教学冲突具有一定的建设性,即具有策动效应,是教学活动的一种潜在动力。为实现其策动效应,将冲突逐级转化、消解紧张态势是一种有效的实践策略,能较好地促进教学。

Entransy is a physical quantity describing heat transfer ability, and heat transfer is accompanied by entransy transfer. Thermal energy is conserved in its transfer process, while entransy is dissipated because of the irreversibility of its transfer process. As a result, entransy transfer must have its rules which are different from those of thermal energy transfer. Based on the definition of entransy, an entransy transfer equation is derived, which describes the entransy transfer processes of a multi-component viscous fluid subject to heat transfer by conduction and convection, mass diffusion and chemical reactions. The expressions of entransy flux and entransy dissipation are obtained simultaneously, and their physical mechanism is clarified. And further, the theory and method of optimizing heat transfer applying the entransy transfer equation to the steady-state convection heat transfer process are expounded. The minimum thermal resistance principle and the entransy dissipation extremum principle are obtained by applying the steady-state entransy transfer equation to the steady-state convection heat transfer process. The cases of the single-component steady-state convection heat transfer and the steady-state heat conduction show the application of the theory and method.

The main methods of single-phase convection heat transfer enhancement are analyzed in this paper, and the unity of contradiction between heat transfer enhancement and energy consumption (or exergy destruction) is expounded. The thermodynamic relationship between heat (or exergy) transfer efficiency and energy consumption (or exergy destruction) as well as driving forces is established, and a general theoretical principle for single-phase convection heat transfer enhancement is further obtained. The principle shows that temperature gradient field distribution and velocity field distribution constrain each other, and that the optimum heat transfer efficiency can be obtained when they are synergetic. If the level of the synergy of temperature gradient field distribution with velocity field distribution is determined, the relative uniform temperature gradient is required, and vice versa. The principle also shows the relationship of relative temperature gradient with specific heat and coefficient of heat conductivity. The deduced results can be used as a theoretical guidance for single-phase convection heat transfer enhancement and optimum design of heat exchangers.

INTRODUCTION Convenient animal models are needed to study the progression and treatment of human tumors in vivo. Luciferase-based bioluminescent imaging (BLI) enables researchers to monitor tumors noninvasively and is sensitive to subtle changes in tumors. METHODS Three human breast cancer models in nude mice were established by using luciferase-expressing MDA-MB-231-luc cells. They were subcutaneous xenografts (n = 8), mammary gland xenografts (n = 5), and lung metastases (n = 3). The tumors were imaged in live mice by using a highly sensitive BLI system. The relationship between the intensity of bioluminescence from the tumor was analyzed with respect to tumor volume. Bioluminescent signals from lung metastases were studied to determine the threshold of detectability. RESULTS Tumors growing in the mice's backs and mammary gland fat pads were imaged dynamically after administration of D-luciferin. The bioluminescent intensity from the tumors gradually increased and then decreased in a one-hour span. The time to reach maximum signal intensity differed significantly among tumors and was independent of tumor volume and unrelated to maximum signal intensity. A significant correlation was observed between tumor volume and maximum signal intensity in tumors from both sites. Lung metastatic lesions of .3-.5 mm in diameter were clearly detectable through the entire animal imaging process. CONCLUSION The animal models established with luciferase-expressing cancer cells in combination with BLI provide a system for rapid, noninvasive, and quantitative analysis of tumor biomass and metastasis. This biosystem simplifies in vivo monitoring of tumors and will be useful for noninvasive investigation of tumor growth and response to therapy.

Transferrin receptor (TfR) is overexpressed in human head and neck squamous cell carcinomas (HNSCCs). This study was carried out to investigate the feasibility of imaging HNSCC by targeting TfR using near-infrared fluorescent transferrin conjugate (TfNIR). Western blot analysis of four HNSCC cell lines revealed overexpression of TfR in all four lines compared with that in normal keratinocytes (OKFL). Immunocytochemistry further confirmed the expression of TfR and endocytosis of TfNIR in JHU-013 culture cells. Following intravenous administration of TfNIR (200 μL, 0.625 μg/μL), fluorescent signal was preferentially accumulated in JHU-013 tumor xenografts grown in the lower back (n = 14) and oral base tissues (n = 4) of nude mice. The signal in tumors was clearly detectable as early as 10 minutes and reached the maximum at 90 to 120 minutes postinjection. The background showed an increase, followed by a decrease at a much faster pace than tumor signal. A high fluorescent ratio of the tumor to muscle was obtained (from 1.42 to 4.15 among tumors), usually achieved within 6 hours, and correlated with the tumor size (r = .74, p = .002). Our results indicate that TfR is a promising target and that TfNIR-based optical imaging is potentially useful for noninvasive detection of early HNSCC in the clinic.

A dual probe with fluorescent and magnetic reporter groups was constructed by linkage of the near-infrared (NIR) fluorescent transferrin conjugate (TfNIR) on the surface of contrast agent-encapsulated cationic liposome (Lip-CA). This probe was used for magnetic resonance imaging (MRI) and optical imaging of MDA-MB-231-luc breast cancer cells grown as a monolayer in vitro and as solid tumor xenografts in nude mice. Confocal microscopy, optical imaging, and MRI showed a dramatic increase of in vitro cellular uptake of the fluorescent and magnetic reporter groups from the probe compared with the uptake of contrast agent or Lip-CA alone. Pretreatment with transferrin (Tf) blocked uptake of the probe reporters, indicating the importance and specificity of the Tf moiety for targeting. Intravenous administration of the dual probe to nude mice significantly enhanced the tumor contrast in MRI, and preferential accumulation of the fluorescent signal was clearly seen in NIR-based optical images. More interestingly, the contrast enhancement in MRI showed a heterogeneous pattern within tumors, which reflected the tumor's morphologic heterogeneity. These results indicate that the newly developed dual probe enhances the tumor image contrast and is superior to contrast agent alone for identifying the tumor pathologic features on the basis of MRI but also is suitable for NIR-based optical imaging.

The optimization methods to enhanced heat and mass transfer are reviewed.The contradiction between enhancing the driving force of energy transfer and decreasing energy or exergy dissipation is discussed.Based on the field synergy principle and exergy transfer dynamic equation,the thermodynamic relationship between exergy transfer rate and energy or exergy dissipation is obtained.The thermodynamic criteria for designing and optimizing energy transfer systems are suggested.The criteria are applied to the design and optimization of conduction and convective processes of heat transfer of a case.The results show that the trade-off between enhancement of energy transfer and decrease of energy or exergy dissipation can be controlled by coordinating the intersection angles or strength of different driving forces.

Angiotensin II (ANG II) and insulin‐like growth factor‐1 (IGF‐1) are activated early in the development of cardiac hypertrophy. We have shown that angiotensin‐converting enzymes (ACE) inhibitors regress eccentric hypertrophy and improve iontropy of the heart. The objective is to evaluate the role of MAPK and PI 3K in the transduction of ANG II and IGF‐1 signaling during the development and regression (by ACE inhibitor, Captopril 500mg/l) of eccentric cardiac hypertrophy. Western blot analysis revealed that in hypertrophied heart there is an increase in the activation of Akt (73%), p38 (124%), ERK1 (32%) and ERK2 (41%). In sham, ANG II (10−7M) increased Akt, p38, ERK1 and ERK2 phosphorylation by 37%, 165%, 28% and 73%, respectively. In hypertrophied hearts ANG II mainly increased p38 and ERK2 activation. IGF‐1 (10−8M) induced activation of Akt (160%) and p38 (139%) with no change in ERK1 and ERK2 activity in the sham hearts. However in the hypertrophied hearts, IGF‐1 induce activation of Akt (125%) and p38 (150%), with a significant activation of ERK2 (100%). Two‐week treatment with Captopril did not alter MAPK and PI 3K in the normal hearts. However, in shunt animals it decreased the activation level of Akt, with a minor effect on the activation level of ERK1; concomitant with 50% regression of cardiac hypertrophy.

Drag reduction of turbulent water flow with surfactant (CTAC) additives was experimentally investigated. By using PIV and PDA measurements, the spatial velocity distribution of surfactant solution flow was clarified in a two-dimensional water channel. With an increasing Reynolds number, it was found that drag reduction of surfactant solution flow is enhanced within the region of drag reduction. However, in the region of post drag reduction, the drag-reducing coefficient approaches one without surfactant when Reynolds number is increased. In the near-wall region, velocity profiles of the drag-reducing fluid are similar to, but not the same as, the laminar profiles of the Newtonian fluid. When compared to the case of water flow without surfactant, the velocity contour lines of the drag-reducing fluid run approximately parallel to the wall. (C) 2005 Wiley Periodicals, Inc.

Based on the viewpoint of contradiction and unification,the approaches to enhancing heat and mass transfer as well as to optimizing and designing transfer process systems are reviewed,and the contradiction between the decrease of energy destruction and the enhancement of transfer process are analyzed.Further,a governing equation for decreasing energy destruction and enhancing transfer process is derived,and an objective function for the optimization and design of transfer process systems is given.The method for designing and optimizing convective heat transfer systems is clarified,and the trend of study on the optimization and design of transfer process systems is pointed out.

The turbulence characteristics of a surfactant solution in changing from drag-reducing flow to turbulent flow inside two-dimension smooth channel and in changing from mesh plug were investigated through PIV (Particle Image Velocimetry) system in this study. It is concluded that the mean velocity profiles of the surfactant solution are similar to that of the water near the mesh plug, whereas the mean velocity profile of the surfactant solution far from the mesh is consistent to that of the surfactant solution flow in smooth channel. The size of the core region of the surfactant solution is obviously larger near the mesh plug, and there are intense eddies near the wall. For the bubble micelle is assembled to the rod-like micelle, with the result of thickening the intergrades region and of suppressing the formation of the large eddies far from the mesh plug.

BACKGROUND: Clinically affected cystic fibrosis (CF) patients present a spectrum of genital phenotypes ranging from normal fertility to moderately impaired spermatogenesis and congenital bilateral absence of vas deferens (CBAVD). Little is known about the CF incidence in the Taiwanese population. It has been shown that the CBAVD in men without clinical evidence of CF is associated with a high incidence of mutated CFTR (cystic fibrosis transmembrane conductance regulator) alleles. In order to understand the involvement of the CFTR gene in the aetiology of Asian/Taiwanese male infertility, we screened the entirety of the CFTR gene in 36 infertile males with CBAVD. METHODS: Temporal temperature gradient gel electrophoresis (TTGE) followed by direct DNA sequencing was used. RESULTS: Five mutations, p.V201M, p.N287K, c.-8G > C (125G > C), p.M469I and p.S895N, were found in five of the patients. p.N287K occurred in the first transmembrane-spanning domain, p.M469I in the first ATP-binding domain and p.S895N in the second transmembrane-spanning domain, were novel. In addition, seven homozygous and seven heterozygous 5T alleles in the intron 8 poly(T) tract were found. The overall frequency of CFTR mutant alleles in Taiwanese CBAVD males was 26 out of 72=36%. This finding was lower than the published frequency of CFTR mutations in other ethnic CBAVD patients (ranging from 50 to 74%). The frequency of p.M470V in Taiwanese CBAVD patients is not significantly different from that in the general population (P=0.12). CONCLUSIONS: The results of this study add to the short list of Taiwanese/Asian CFTR mutations. Unlike Caucasian patients, the CFTR mutations cannot account for the majority of Taiwanese CBAVD. This is consistent with the low incidence of CF in the Asian/Taiwanese population. Furthermore, the mutation spectrum of CFTR in CBAVD patients does not overlap with the Caucasian CFTR mutation spectrum.

Drag reducing performances of Cetyltrirnethyl Ammonium Chloride (CTAC) drag reducing fluid in two-dimensional channel under different experimental situations were measured. The results indicate that there are the maximum limitation and optimum option even for the same drag reducing additive. Phase Doppler Anemometry (PDA) was applied to measuring the turbulent characteristics of drag reducing fluid. By contrast with those of Newtonian fluid, it is found that the velocity fluctuations and the Reynolds shear stresses in the drag reducing fluid decrease dramatically.

The turbulence characteristics of a surfactant solution in changing from drag-reducing flow to turbulent flow inside two-dimensional smooth channel and in changing from mesh plug were investigated through phase Doppler anemometry (PDA) and particle image velocimetry(PIV) system.It is concluded that the turbulent velocity fluctuation of the drag-reducing flow increases obviously with mesh-addition,and gets more and more weakened along the flow.The mean velocity profiles of the surfactant solution are similar to that of the water near the mesh plug,whereas the mean velocity profile of the surfactant solution far from the mesh is consistent to that of the surfactant solution flow in smooth channel.The size of the core region of the surfactant solution is obviously larger near the mesh plug than away the mesh plug,and there are intense eddies near the wall.The bubble micelle is assembled to the rod-like micelle,with the result of thickening the intergrades region and of suppressing the formation of the large eddies far from the mesh plug.

The approaches to heat transfer enhancement, whether they are traditional or field-synergic, only emphasize the intensity of heat transfer unilaterally, and ignore the restriction of energy destruction caused by heat transfer enhancement. On the levels of intensity of enhancing heat transfer, a mathematical relationship between the intensity of heat transfer and the internal field as well as external field in the fluids is given, which shows that the intensity of heattransfer can be controlled by adjustingthe relationship between differentkinds of driving forces. On the levels of optimum design of heat transfer systems, a thermodynamic criterion for optimum design of heat transfer units is proposed, which indicates the trade-off between irreversibility and driving forces. Further the optimum temperature difference for design of heat exchanger is obtained.

Enhancement of heat transfer must be investigated for the design of heat transfer systems, but energy (or exergy) destruction due to irreversibility should also be considered. In this paper, a differential heat exergy transfer equation is derived and then, based on that and the field synergy principle, a thermodynamic relation, combining exergy destruction with the parameters for enhancing heat (or heat exergy) transfer, is derived. This relationship shows that enhancement of heat transfer as well as decrease of energy (or exergy) destruction can be controlled by coordinating the intersection angles between various driving forces. Further, an objective function, showing the trade-off between irreversibility and driving force, is given, which can be used as a criterion for the design and optimization of heat (or heat exergy) transfer system performances.

综述了过程系统能量综合优化的能量流结构研究与进展;重点介绍了过程系统三环节能量流结构模型,该模型基于对过程系统中能量演变共性规律的认识,定量地描述了过程系统能量流在转换、利用、回收过程中的平衡关系;概述了按照能量流结构进行过程能量综合优化策略和方法;指出了过程系统能量综合优化中能量流结构的进一步发展可以包容其他相关方面 ,如环境、安全等.