Comparative study on the heat transfer performance of micro-grooved anodized thermosyphon with R134a,R600a and R717 for low-temperature applications

Journal of Mechanical Science and Technology - A comparative heat transfer performance of an internally grooved anodized thermosyphon with eco-friendly refrigerants is presented in this study....     

新型磷酸二酯酶Ⅳ抑制剂Ariflo 对内皮素-1诱发离体人子宫平滑肌收缩的影响

目的:研究选择性磷酸二酯酶(phosphodiesterase, PDE) Ⅳ抑制剂Ariflo 对内皮素-1 (endothelin-1,ET-1)诱发的非妊娠人子宫平滑肌收缩的影响。方法:累积给药法观察药物对离体平滑肌收缩的作用。结果:Ariflo 可降低子宫平滑肌自主收缩的收缩频率及收缩幅度(pD₂ =7.90), 且对ET-1 (3 ×10^-8 mol·L^-1)诱发的子宫平滑肌收缩具有浓度依赖性抑制作用(pD₂ =7.40), 作用强度与Rolipram 相似。结论:Ariflo 对ET-1 诱发的离体人子宫平滑肌的收缩具有显著抑制作用, 提示在临床上有缓解痛经的作用。     

Inspection and maintenance of oil & gas pipelines: a review of policies

Oil and gas (O&G) pipelines are expensive assets that cross through both the ecologically sensitive and densely populated urban areas. The pipeline failure may have potentially significant consequences for both the natural and human environments. In order to maintain the integrity of O&G pipelines, inspection and maintenance processes should be governed by efficient policies. The objective of this paper is to conduct a state-of-the-art review of maintenance policies of O&G pipelines to investigate their advantages, limitations, and associated implementation issues. Maintenance policies can be categorised into corrective, preventive, predictive and proactive. Corrective maintenance policies (1940s) were based on the ‘repair when broke’ philosophy. Economic considerations shifted practice towards preventive maintenance (1970s to 1990s); later with improved inspection techniques and environmental regulations, predictive and proactive or risk-based maintenance (RBM) policies were developed. This review explicates different methodologies for RBM and related issues, e.g. uncertainties and variability, conservative assumptions, etc. Uncertainties associated with investigation and prediction of defects have been more frequently reported in the literature so far. Moreover, existing studies primarily focused on reducing the likelihood and cost of failure, whereas consideration of environmental factors in overall risk has been a relatively less addressed issue.     

Shall we dance? How a multicopper oxidase chooses its electron transfer partner

Multicopper oxidases (MCOs) are encoded in the genomes of Eukarya, Bacteria, and Archea. These proteins are unique in that they contain at least four Cu atom prosthetic groups organized into one each of the three spectral classifications of copper sites in biology: type 1 (T1), type 2 (T2), and binuclear type 3 (T3), where the T2 and T3 sites form a trinuclear Cu cluster. With these four redox-active copper sites, the multicopper oxidases catalyze the four-electron (4e(-)) reduction of dioxygen to 2H2O, an activity that they alone share with the terminal heme-containing oxidases. Most MCOs exhibit broad specificity towards organic reductants, while a relatively small number of family members exhibit equally robust activity towards metal ions like Fe(II), Cu(I), and Mn(II) and, thus, are considered metallo-oxidases. This Account analyzes the structure-activity features of multicopper oxidases that determine their relative substrate specificity. Since the substrate oxidation step involves an outer-sphere electron transfer from the reductant to the T1Cu site in the protein, the concepts of Marcus theory are applied to unravel the origin of the substrate specificity of the multicopper ferroxidases.     

In vivo and in vitro antiinflammatory activity of saikosaponins

Buddlejasaponin I and saikosaponin 1 and 2, biologically active compounds from Scrophularia scorodonia and Bupleurum rigidum respectively, exert potent in vivo antiinflammatory effects on mouse ear edema induced by phorbol myristate acetate (PMA). The effects of these compounds on swelling and other inflammatory parameters are described. In screening for in vitro effects of saikosaponins on cellular systems generating cyclooxygenase (COX) and lipoxygenase (LOX) metabolites, we observed that most saikosaponins showed a significant effect. The action is more marked on LOX metabolite LTC4. Our data support the inhibition of arachidonic acid metabolism as one of the biochemical mechanisms that might be the rationale for the putative antiphlogistic activity of these saikosaponins.