Ten patients with biopsy verified chronic hepatitis C virus (HCV) infection were treated with oral ribavirin at a dose of 1,000-1,200 mg per day in two divided doses for 12 weeks. Serum alanine aminotransferase (ALT) levels and hepatitis C viral ribonucleic acid (RNA) levels in serum were followed prior to, during, and 12 weeks posttreatment. ALT levels decreased significantly in all patients during therapy from a mean level of 3.21 mukat/l (range 1.22 to 7.79) before, to 1.25 mukat/l (range 0.78 to 2.04) at the end of treatment (P < 0.005). Hereafter, relapse to pretreatment levels was seen within 12 weeks after treatment stop. The hepatitis C viral RNA levels decreased from a mean 10 log titer of 4.1 (range 1-6) before treatment to 3.4 (range 1-5) at treatment stop. Five patients did not change their HCV RNA titers during treatment. Twelve weeks posttreatment only 3 patients had lower titers than prior to treatment. We conclude that oral ribavirin seems to reduce the viral load, at least temporarily, in some patients with chronic viremic HCV infection. Further studies are needed to evaluate fully the effect of oral ribavirin on chronic HCV infection. 相似文献
Results are presented of elastic, elastic-plastic and elastic-plastic-creep analyses of an actively cooled cowl lip. A cowl lip is part of the leading edge of an engine inlet of proposed hypersonic aircraft and is subject to severe thermal loadings and gradients during flight. Values of stresses calculated by elastic analysis are well above the yield strength of the cowl lip material. Such values are highly unrealistic, and thus elastic stress analyses are inappropriate. The inelastic (elastic-plastic and elastic-plastic-creep) analyses produce more reasonable and acceptable stress and strain distributions in the component. Finally, using the results from these analyses, predictions are made for the cyclic crack initiation life of a cowl lip. A comparison of predicted cyclic lives shows the cyclic life prediction from the elastic-plastic-creep analysis to be the lowest and, hence, most realistic. 相似文献
Self-stratification strategy can be used to prepare films in which both bulk and surface properties can be optimized. By using this approach, only a very small quantity of fluorinated species is needed to generate a surface with low surface energy. When cross-linking is involved during film formation, we are dealing with a competition behavior between the diffusion of fluorinated species and the formation of cross-linked network. In this study low surface energy polymeric films were prepared on the basis of partially fluorinated polyisocyanates, in combination with hydroxyl-end-capped three-armed solventless liquid oligoesters and modified hyperbranched polyesters. At a fluorine concentration of only 0.5 wt.%, contact angles of water and hexadecane can reach 120° and 80°, respectively. A surface energy as low as 10–15 mN/m can be obtained upon the addition of less than 1 wt.% of fluorine in the films. It was shown, from real time ATR-FTIR and contact angle measurements, that the curing temperatures demonstrated significant effects on the cross-linking rate as well as on the wettability of the films. 相似文献
Most of the published literature on robust design is basically concerned with a single response. However, the reality is that common industrial problems usually involve several quality characteristics, which are often correlated. Traditional approaches to multidimensional quality do not offer much information on how much better or worse a process is when finding optimal settings. Köksoy and Fan [Engineering Optimization 44 (8): 935–945] pointed out that the upside-down normal loss function provides a more reasonable risk assessment to the losses of being off-target in product engineering research. However, they only consider the single-response case. This article generalizes their idea to more than one response under possible correlations and co-movement effects of responses on the process loss. The response surface methodology has been adapted, estimating the expected multivariate upside-down normal loss function of a multidimensional system to find the optimal control factor settings of a given problem. The procedure and its merits are illustrated through an example. 相似文献
In recent years, there has been considerable research showing that coffee consumption seems to be beneficial to human health, as it contains a mixture of different bioactive compounds such as chlorogenic acids, caffeic acid, alkaloids, diterpenes and polyphenols. Neurodegenerative diseases (NDs) are debilitating, and non-curable diseases associated with impaired central, peripheral and muscle nervous systems. Several studies demonstrate that neuroinflammation mediated by glial cells—such as microglia and astrocytes—is a critical factor contributing to neurodegeneration that causes the dysfunction of brain homeostasis, resulting in a progressive loss of structure, function, and number of neuronal cells. This happens over time and leads to brain damage and physical impairment. The most known chronic NDs are represented by Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and Huntington’s disease (HD). According to epidemiological studies, regular coffee consumption is associated with a lower risk of neurodegenerative diseases. In this review, we summarize the latest research about the potential effects of caffeine in neurodegenerative disorders prevention and discuss the role of controlled caffeine delivery systems in maintaining high plasma caffeine concentrations for an extended time. 相似文献
Excess body weight has been considered beneficial to bone health because of its anabolic effect on bone formation; however, this results in a poor quality bone structure. In this context, we evaluated the involvement of circulating extracellular vesicles in the impairment of the bone phenotype associated with obesity. Circulating extracellular vesicles were collected from the plasma of participants with normal weight, as well as overweight and obese participants, quantified by flow cytometry analysis and used to treat mesenchymal stromal cells and osteoblasts to assess their effect on cell differentiation and activity. Children with obesity had the highest amount of circulating extracellular vesicles compared to controls. The treatment of mesenchymal stromal cells with extracellular vesicles from obese participants led to an adipogenic differentiation in comparison to vesicles from controls. Mature osteoblasts treated with extracellular vesicles from obese participants showed a reduction in differentiation markers in comparison to controls. Children with obesity who regularly performed physical exercise had a lower circulating extracellular vesicle amount in comparison to those with a sedentary lifestyle. This pilot study demonstrates how the high amount of circulating extracellular vesicles in children with obesity affects the bone phenotype and that physical activity can partially rescue this phenotype. 相似文献
Current studies about lipase production involve the use of agro-industrial residues and newly isolated microorganisms aimed at increasing economic attractiveness of the process. Based on these aspects, the main objective of this work is to perform the partial characterization of enzymatic extracts produced by a newly isolated Penicillium crustosum in solid-state fermentation. Lipase extract presented optimal temperature and pH of 37?°C and 9?C10, respectively. The concentrated enzymatic extract showed more stability at 25?°C and pH?7. The enzymes kept 100% of their enzymatic activity until 60?days of storage at 4 and ?10?°C. The stability under calcium salts indicated that the hydrolytic activity presented decay with the increase of calcium concentration. The specificity under several substrates indicated good enzyme activities in triglycerides from C4 to C18. 相似文献
In this work, we contribute to the study of the structural reorganisation of biological tissues in response to mechanical stimuli. We specialise our investigation to a class of hydrated soft tissues, whose internal structure features reinforcing fibres. These are oriented statistically within the tissue, and their pattern of orientation is such that, at each material point, the tissue is anisotropic. From its natural, stress-free state, the tissue can be distorted anelastically into a global reference configuration, and then deformed under the action of external mechanical loads. The anelastic distortions are responsible for changing irreversibly the internal structure of the tissue, which, in the present context, occurs through both the rearrangement of the bonds among the tissue cells and the deformation-driven reorientation of the fibres. The anelastic strains, in addition, are assumed to model the onset and evolution of microcracks in the tissue, which may be triggered by the mechanical loads applied to the tissue in the case of traumatic events, or diseases. For our purposes, we formulate an anisotropic model of remodelling and we consider a fully isotropic model of structural reorganisation for comparison, with the aim to study if, how, and to what extent the evolution of anelastic distortions is influenced by the tissue’s anisotropy.