Role of the human beta-herpesviruses in organ allograft rejection following transplantation.

In previous prospective studies conducted in our department, PCR was used to detect the three ({dollar}-herpesviruses, human cytomegalovirus (HCMV), and human herpesviruses 6 and 7 (HHV-6 and HHV-7) in the blood of solid organ transplant patients. The viruses were commonly detected post-transplantation, and HCMV and HHV-6 were independently associated with graft rejection in liver recipients. HHV-7 was also associated with increased episodes of rejection in renal transplant patients. To better understand the role of these viruses in graft rejection, in situ techniques including in situ hybridisation (ISH) and immunohistochemistry (IHC) were developed to detect these viruses in renal and liver allograft biopsies from patients in the original prospective studies. HCMV DNA was detected in a significant proportion of liver and renal biopsies (approximately 50%) by ISH, with detection being widespread especially in renal allografts. The presence of HCMV DNA in the biopsies is likely to represent low level HCMV replication not detectable by IHC. HCMV was not statistically associated with either renal or liver allograft rejection by ISH. It remains possible that HCMV infection in the graft leads to dysfunction and is clinically interpreted as allograft rejection. HHV-6 and HHV-7 were not detected in any allografts by ISH or IHC. In addition, an uncommon form of HHV-6 persistence is characterized by high viral loads in blood and integration of viral sequences into host cell chromosomes. Fluorescence in situ hybridisation (FISH) was developed to examine integration events in a healthy individual with a consistently high HHV-6 load and also in a case of genetic transmission of integrated virus through stem cell transplantation. In the former individual, integrated HHV-6 was identified on chromosome lip 15.5 and in the latter shown in the donor and the recipient (post-transplantation only) on chromosome 17pl3.3. The confounding effect of HHV-6 integration must be considered when investigating novel disease associations of HHV-6

CFD Modelling of Finned-tube CO2 Gas Cooler for Refrigeration Systems

As a main component in a refrigeration system, finned-tube CO2 gas cooler plays an important role to the system performance and thus needs to be thoroughly investigated. To achieve this, some effective parameters including the CO2 and air fluid velocity fields, temperature profiles and heat transfer characteristics at different operating conditions are predicted and analysed by means of Computational Fluid Dynamics (CFD) modelling and simulation. It is noted that CFD modelling can accurately obtain the local heat transfer coefficients of both air and refrigerant sides, which are difficult to be predicted by conventional empirical correlations. This paper investigates the effect of varied operational parameters on local heat transfer coefficients and temperature profiles of the working fluids in a finned-tube CO2 gas cooler by means of CFD modelling. As one of the simulation results, it is found that the approach temperature decreases with increased air inlet velocity. The model has been compared and validated with experimental measurements and literature correlations. The research methods and outcomes can be used for further investigation and optimization in this area

Noninvasive Two-Dimensional Strain Imaging of Atherosclerosis: A Preliminary Study in Carotid Arteries In Vivo

AbstractAtherosclerosis remains a major cause of mortality all over the world and the sudden rupture of atherosclerotic plaque is the most important assassin. Vascular ultrasound elastography has shown promise in estimating the elastic properties to evaluate the plaque vulnerability. Contrary to intravascular elastography, noninvasive applications use a transcutaneous ultrasound transducer that is inexpensive, re-useable and convenient. To estimate the strain map, we employ a cross-correlation method in complex field to extract both the magnitude and phase messages of the ultrasound RF-echo signal. Two-dimension noninvasive carotid elastography was studied in atherosclerotic rats and New Zealand Rabbits and also in healthy volunteer, and the results indicate huge potential for diagnosis of the vulnerability of atheromatous plaques

Prediction of atherosclerotic plaque life – Perceptions from fatigue analysis

Cardiovascular diseases are the leading causes of morbidity and mortality globally. Heart disease and stroke contribute to most fatalities in which atherosclerotic plaque disruption is the underlying pathology. The pulsatile blood flow in the arteries generates mechanical stresses that affect the rupture of the atherosclerotic plaque. Fatigue failure being the accumulation of the damage due to repeated loading that occurs when the stresses are much lower than those needed to rupture the plaque with normal loading. Therefore, fracture mechanics concepts were used to investigate the impact of morphology and blood pressure on the plaque life. Incremental fatigue crack propagation simulations were performed on idealized geometries based on the maximum circumferential stress criteria by using a finite element solver. XFEM, which extends the standard finite element formulation by introducing additional enrichment functions was used to model the fatigue crack growth simulations. Paris’ Law was used to determine the fatigue crack growth rate. Cracks extended radially and fatigue crack growth rate increased with increase in pulse pressure. Further validation studies on the 3D printed arteries are necessary for better understanding the factors contributing to plaque rupture. The results could help in assessing the atherosclerotic plaque life under the fatigue environment of the cardiovascular system

Modeling on Stress Evolution of Step Part for Casting-heat Treatment Processes

AbstractHeat treatment usually follows the casting process to improve the physical properties of parts. Under the strong assumption that casting has no effect on the following heat treatment, the modeling of heat treatment process is currently based on ideal material conditions with zero residual stress and uniform properties. In this paper, residual stress generated by casting has been introduced as the initial conditions for a heat treated step part of 4140 steel. The results have been compared with that of no consideration about initial residual stresses of casting

A Performance Evaluation of Introducing Balanced Scorecard to High-tech Related Industries in Taiwan

Balanced Scorecard (BSC) has become the most desirable performance evaluation tool for industries in Taiwan; however, difficulty or bad performance of system introduction has occurred due to an incomplete understanding of the implementation approaches and correct objectives of the BSC system, causing the risk of cost loss. Two domestic high-tech companies in the high-tech related industry were served as the object of study in this research. The contents of four perspectives of the BSC were converted to twenty key performance evaluation indicators in terms of modern business administration as the variables in the research. Based on the DMAIC model, the importance and satisfaction of BSC implementation factors in high-tech related industry are defined first. The performance indices of satisfaction and importance of implementing BSC are standardized by fuzzy methods for evaluation and a performance matrix with the target line and upper and lower performance control lines are established. Management can analyze the performance level and compare the performance indices and matrixes of two companies after introducing BSC according to the coordinates of satisfaction and importance of implementation factors in the matrixes. These two-dimension matrices will then be converted to one-dimension coordinates for cross performance matrices of four quadrants. Next, performance improvement strategies will be devised in accordance with the aspects of the theory of constraints. After carrying out improvement strategies, the cross performance matrix will be constructed to verify the effect and ascertain the factors of bad performance. In this way, improvement strategies can be re-devised and the most appropriate distribution of resources will be made to sustain the optimum state of ability and cost during the process of introducing the BSC system. Requirements for a short period of time and low cost to evaluate the performance of BSC introduction can be met via this simple and convenient evaluation model presented in this research. Resources will be invested to enhance satisfaction for the implementation factors of high importance and low satisfaction. Likewise, resources will be adjusted to reduce the cost of system introduction for the implementation factors of low importance and high satisfaction. As a result, the time efficiency of introducing the BSC system will be promoted effectively

Finite Element Analysis of the Displacement Adjustment Scheme for Column Bases of a 10000 m3 Spherical Tank During Whole-body Heat Treatment

AbstractThe stress of spherical tank and displacement of column bases were calculated by finite element method, considering the uneven gravity loads on support columns which was caused by manufacturing and setting errors. The preliminary displacement adjustment scheme for column bases was made, according to the safety range of column bases displacement which was determined by the maximum stress restricted by allowable stress at the set heat treatment temperatures. The final scheme was made after checking the preliminary scheme. The method of making adjustment scheme of column bases for a 10000m3 spherical tank during the whole-body heat treatment may provide a reference for other large spherical tank

Analytical Simulations for Shaking Table Tests of a Full Scale Buckling Restrained Braced Frame

AbstractThe seismic response tests of a full-scale five-story passively-controlled steel building have been conducted on the EDefense shaking table in Japan in March 2009. Before the tests, a blind prediction contest was held to allow researchers and practitioners from all over the world to construct numerical model and predict the dynamic responses of the building frame equipped with buckling restrained braces or viscous dampers. This paper presents the response predictions made before the tests of the buckling restrained braced frame (BRBF). A three-dimensional shell finite element subassembly model was constructed to investigate the stiffness of the buckling-restrained brace end joint. The dynamic test results of the sample steel dampers provided by the organizer were used to calibrate the BRB strength in the numerical model. The details of the numerical model for the composite beam, hollow structural section column, and the beam-to-column panel zone are described. Base on the numerical and test analyses, effective numerical models are presented and the recommended nonlinear modeling techniques for BRBF are provided