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排序方式: 共有73条查询结果,搜索用时 15 毫秒
1.
Metalworking fluid (MWF) supplies a film of lubricant to abate friction, acts as a cooling media to rebate induced heat, and prevents metal pick-ups by flushing away the chips. Hence a liquid used as a cutting fluid reduces wear on the tool, reduces the energy consumption, and produces a better surface quality on the work piece. This paper describes the formulation of a novel water-soluble MWF and its performance evaluation during straight turning and end milling experiments carried out with AISI 304 stainless steel, mild steel, and cast iron as work piece materials. The MWF was prepared by mixing water with white coconut oil as the base oil and food-grade additives as surfactants. Viscosity, pH value, and biodegradability were measured and compared with a commercially available non-vegetable oil–based MWF. The surface roughness and tool surface temperature were measured throughout the machining experiments, and better performances were observed with the coconut oil–based MWF. Tool tip geometry and flank wear for straight turning machining operation were identified by observing scanning electron microscope (SEM) images. 相似文献
2.
Gunaranjan Paturi Tafadzwa Nyanhanda Christine A. Butts Thanuja D. Herath John A. Monro Juliet Ansell 《Journal of food science》2012,77(10):H216-H223
Abstract: The effects of red meat consumption with and without fermentable carbohydrates on indices of large bowel health in rats were examined. Sprague‐Dawley rats were fed cellulose, potato fiber, or potato‐resistant starch diets containing 12% casein for 2 wk, then similar diets containing 25% cooked beef for 6 wk. After week 8, cecal and colonic microbiota composition, fermentation end‐products, colon structure, and colonocyte DNA damage were analyzed. Rats fed potato fiber had lower Bacteroides‐Prevotella‐Porphyromonas group compared to other diet groups. Colonic Bifidobacterium spp. and/or Lactobacillus spp. were higher in potato fiber and potato‐resistant starch diets than in the cellulose diet. Beneficial changes were observed in short‐chain fatty acid concentrations (acetic, butyric, and propionic acids) in rats fed potato fiber compared with rats fed cellulose. Phenol and p‐cresol concentrations were lower in the cecum and colon of rats fed potato fiber. An increase in goblet cells per crypt and longer crypts were found in the colon of rats fed potato fiber and potato‐resistant starch diets. Fermentable carbohydrates had no effect on colonic DNA damage. Dietary combinations of red meat with potato fiber or potato‐resistant starch have distinctive effects in the large bowel. Future studies are essential to examine the efficacy of different types of nondigestible carbohydrates in maintaining colonic health during long‐term consumption of high‐protein diets. Practical Application: Improved understanding of interactions between the food consumed and gut microbiota provides knowledge needed to make healthier food choices for large bowel health. The impact of red meat on large bowel health may be ameliorated by consuming with fermentable dietary fiber, a colonic energy source that produces less harmful by‐products than the microbial breakdown of colonic protein for energy. Developing functional red meat products with fermentable dietary fiber could be one way to promote a healthy and balanced macronutrient diet. 相似文献
3.
P Cairns TJ Polascik Y Eby K Tokino J Califano A Merlo L Mao J Herath R Jenkins W Westra 《Canadian Metallurgical Quarterly》1995,11(2):210-212
BACKGROUND: Carcinoma of the breast is characterized by a variable course with prognosis dependent on disease stage at presentation. Paradoxically, some patients with early malignancy demonstrate disease progression within a short time. The role of tumor markers in the management of carcinoma of the breast is controversial. While CA15-3 is the most widely used tumor marker in carcinoma of the breast, its role in the management of patients with early disease is controversial. STUDY DESIGN: Since 1986, all patients presenting to our unit with carcinoma of the breast have had serial CA15-3 levels measured. This study evaluates the role of serial CA15-3 levels in the management of a consecutive series of 168 patients with Stage I disease at presentation. RESULTS: The mean preoperative CA15-3 levels at presentation were significantly elevated in patients with Stage I disease compared with patients with benign disease. Sixteen patients had either locoregional (five patients) or metastatic recurrence (11 patients). CA15-3 levels were not elevated in patients with locoregional disease and were significantly elevated in patients with bony metastases and gave a mean lead time of 6.3 months over bone scintigraphy. CONCLUSIONS: Serial CA15-3 measurements are an efficient and cost-effective method of monitoring disease progression and have advantages over conventional investigations in patients with early carcinoma of the breast. 相似文献
4.
Ajith C. Herath 《Electrochimica acta》2010,55(27):8319-8324
The electrochemical behavior of tris(4-bromophenyl)amine (TBPA) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was comparatively studied in room temperature ionic liquids (RTILs) containing 1-butyl-3-methylimidazolium cation [BMIm]+ and the anions BF4−, PF6−and CF3SO3−. TEMPO showed a well-defined electrochemical reversibility with anodic to cathodic peak current ratio (Ia/Ic) equals to unity in all RTILs, at a glassy carbon electrode. In contrast, Ia/Ic ratio greater than unity was observed at all scan rates employed (10-1000 mV s−1) in cyclic voltammograms (CV) of TBPA in RTILs. Controlled-potential bulk electrolysis of TBPA in RTILs yielded a dark blue colored solution of monocation TBPA+, which is stable under nitrogen. Diffusion coefficient of TBPA+ cation was determined in all three ILs by chronoamperometry and found to be at least one order of magnitude less than the calculated value of TBPA. This effect, in conjunction with the deviation of the Ia/Ic ratio from unity could be ascribed to ion-pairing interaction between the TBPA+ cation and the anion of the RTILs. 相似文献
5.
Mahesha B. Herath Stephen E. Creager Rama V. Rajagopal Olt E. Geiculescu Darryl D. DesMarteau 《Electrochimica acta》2009,54(24):5877-5883
We report synthesis, characterization and ion transport in polyether-based ionic melt electrolytes consisting of Li salts of low-basicity anions covalently attached to polyether oligomers. Purity of the materials was investigated by HPLC analysis and electrospray ionization mass spectrometry. The highest ionic conductivity of 7.1 × 10−6 S/cm at 30 °C was obtained for the sample consisting of a lithium salt of an arylfluorosulfonimide anion attached to a polyether oligomer with an ethyleneoxide (EO) to lithium ratio of 12. The conductivity order of various ionic melts having different polyether chain lengths suggests that at higher EO:Li ratios the conductivity of the electrolytes at room temperature is determined in part by the amount of crystallization of the polyether portion of the ionic melt. 相似文献
6.
Deterrence theory is one of the most widely applied theories in information systems (IS) security research, particularly within behavioral IS security studies. Based on the rational choice view of human behavior, the theory predicts that illicit behavior can be controlled by the threat of sanctions that are certain, severe, and swift. IS scholars have used deterrence theory to predict user behaviors that are either supportive or disruptive of IS security, and other IS security-related outcome variables. A review of this literature suggests an uneven and often contradictory picture regarding the influence of sanctions and deterrence theory in general in the IS security context. In this paper, we set out to make sense of the discrepant findings in the IS deterrence literature by drawing upon the more mature body of deterrence literature that spans multiple disciplines. In doing so, we speculate that a set of contingency variables and methodological and theoretical issues can shed light on the inconsistent findings and inform future research in this area. The review and analysis presented in this paper facilitates a deeper understanding of deterrence theory in the IS security domain, which can assist in cumulative theory-building efforts and advance security management strategies rooted in deterrence principles. 相似文献
7.
Use of bottled water in Sri Lanka has increased over the last decade, while new brands of bottled water are often introduced to the market. However, the manufacturers' adherence to bottled water regulations is questionable, raising concerns regarding the quality of bottled water. The objective of the current study was to investigate the microbiological and chemical quality of bottled water in Sri Lanka. Thirty bottled water brands were sampled and their chemical and microbiological parameters were analyzed. Microbiological analysis was carried out within 1 to 3, 3 to 6, 6 to 9, and 9 to 12 mo after the date of manufacture. The results indicated that 63% of brands tested exceeded the levels permitted by the Sri Lanka Standards Institution (SLSI) for presumptive total coliforms (TC) (<10 cfu per 100 mL) whereas 97% brands exceeded the World Health Organization (WHO) permitted level. Thirty percent of brands exceeded the limit for presumptive fecal coliforms (FC) (0 cfu per 100 mL in accordance with WHO permitted levels, SLSI and the Sri Lanka Health Ministry requirement). Eighty percent of brands showed higher heterotrophic plate counts (HPC) which exceeded the WHO guidelines for bottled drinking water. Throughout their shelf life, the counts of TC, FC, and HPC bacteria decreased. Bacteria identified were Klebsiella pneumoniae ssp. pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, and Pasteurella haemolytica, the most frequently being P. aeruginosa. The dominant fungi identified were Aspergillus sp. and Penicillium sp. Inorganic chemical parameters were within permitted levels for all brands except for initial content of ammonia. The results of this study show the need for the bottling industry to be monitored closely by relevant authorities, in order to provide safe bottled drinking water to consumers in Sri Lanka. 相似文献
8.
9.
Liang Fang Wan Yan Shunping Chen Qiong Duan Madhubhashitha Herath Jayantha Epaarachchi Yue Liu Chunhua Lu 《大分子材料与工程》2023,308(12):2300158
Shape-memory polymers (SMPs) are smart materials that change shape when exposed to stimuli and have various applications in different fields due to their unique properties. Light, as a kind of electromagnetic radiation, plays an important role in understanding the structure-property relations of SMPs, preparing original shapes, using them as non-contact stimuli sources, and tuning the optical properties of SMPs. This review provides a comprehensive review of the involvement of light in structure-preparation-stimuli-application of SMPs. The review is divided into four sections. First, applications of optical/spectroscopic approaches that provide information for understanding structure-property relations in SMPs, especially during programming and recovery. Second, describes how to build SMPs with light, including different photochemical reactions and 3D photocuring technologies. Third, discusses how light is used to trigger the shape change of SMPs through both photochemical and photothermal mechanisms. Last, focuses on how to take advantage of the shape-memory effect to tune the optical characteristics of polymers, including various structures of SMP color-changing materials and their synthetic strategies. Future research could focus on developing efficient photothermal fillers, new 3D printing techniques for SMPs, exploring their use in biomedical and wearable devices, and optimizing SMPs for industrial applications. 相似文献
10.
This article evaluates the equity performance of bulk water allocation as an irrigation management strategy in the Mahaweli Ganga Development Project, Sri Lanka. Through semi-structured interviews with farmers and irrigation officials, the study collected local perceptions using seven indicators: water rights; decision-making process; contribution of resources for irrigation maintenance; water allocation rules; actual water distribution; information sharing; and conflict resolution. The results highlight gaps in the institution such as the need to enhance the water rights of landless farmers, further encourage crop diversification, increase transparency in decision making, instil a risk-management approach, and strengthen accountability. 相似文献