فهرست مطالب teng

An improved delayed detached eddy simulation (IDDES) is carried out to investigate both the mean and the instantaneous flow characteristics of conical cavities fixed on a cone surface in a Mach 0.9 freestream. Two model categories, a single cavity model with different length (L) to depth (D) ratio and a multi-cavity model that inserted the separation disk into a single cavity are studied. Results indicate that in case of a single cavity model, the cavity L/D ratio is the key parameter that influences mean flow structure and oscillatory characteristics. The bulk reverse flow structure can be broken up into smaller structures as L/D value reduces from 4.0 to 0.51 inside the cavity. Smaller longitudinal pressure gradients on the cavity wall and the thicker downstream boundary layer are observed when larger L/D values are present. The cavities with smaller L/D values can stimulate the pressure oscillation fundamental frequency as well as the acoustic tones to increase the value. Multi-cavity configurations through insertion of a separation disk into the single cavity are helpful in cutting the large reverse flow structure inside a cavity into a smaller, similar, coherent structure, and to reduce the overall cone drag. The insertion of the separation disk can modulate pressure oscillation peaks and sound pressure levels to higher frequency, however, they are not able to reduce the overall sound pressure inside the cavity. Pressure oscillations within each cavity of the multi-cavity configuration have a weak correlation.

The effects of various carbonization parameters on the COD reduction of Rhodamine B dye aqueous solutions using carbonized Elaeis guineensis frond fiber (EGFF) chars have been studied experimentally. The adsorbent with the particle size of

A novel inorganic-organic hybrid polymer of magnesium chloride-polyethylene oxide (MgCl2-PEO) was prepared, characterised and applied in the coagulation-flocculation of a reactive dye, Cibacron Blue F3GA (RCB). The hybrid polymers were prepared in various ratios and their conductivity and viscosities were measured. For the application in the coagulation-flocculation of RCB, the hybrid polymer of 90% MgCl2:10% PEO ratio was selected as it showed the highest conductivity and lowest viscosity. The factors that affect coagulation-flocculation of RCB, namely initial dye concentration, initial pH, agitation speed, agitation time and hybrid polymer dosage, were studied using fractional factorial design and response surface methodology (RSM). The process was also optimised, with respect to colour removal and chemical oxygen demand (COD) reduction efficiency. The five factors studied showed significant effects toward the colour removal and COD reduction of RCB. The process was optimum at initial dye concentration of 173 mg/L, pH 11.13, agitation speed of 150 rpm, agitation time of 6 minutes and hybrid polymer dosage of 1020 mg/L. Under these optimum conditions, maximum colour removal of 99.76% and COD reduction of 92.09%, were achieved.

Application of an ionic liquid (4-Methyl-2-pentanone) carrier on liquid-liquid extraction of nickel and cadmium from aqueous solutions is reported. 4-Methyl-2-pentanone was found to dissolve in octanol (as diluent) and was capable of extracting both nickel and cadmium ions, however in terms of extraction efficiency, 4-Methyl-2-pentanone has higher capability for nickel extraction in compare to cadmium. The effects of feed phase pH, carrier concentration, mixing time, stripping phase pH and inert salt concentration on extraction of nickel and cadmium were analyzed using factorial design for screening experiment and face centered composite design of experiments for optimization. The results of liquid-liquid extraction process led to removal of 91% of nickel ions and 32% of cadmium from mixed Ni-Cd aqueous feed phase with carrier concentration of 250 mM, feed phase pH of 4, mixing time of 5 minutes and 1.5 M of sodium sulphate as inert salt. In stripping phase, both nickel and cadmium were highly stripped while stripping phase pH was set at alkaline range of 10-11. The effect of feed phase pH on distribution ratio (Feed/Org) for both metals was investigated and the results revealed that one nickel ion is extracted into the organic phase by an average 3.2 of 4- Methyl-2-pentanone molecules to form nickel-4-Methyl-2-pentanone complex, while for cadmium extraction, the carrier molecules involved in metal-carrier complexation is equal to 2.

A high prevalence of gastroesophageal reflux disease symptoms has observed among chronic obstructive pulmonary disease (COPD) patients, and proton-pump inhibitors (PPIs) are the main medication in clinical practices. The aim of this study is to analyze the impact of PPIs to the risk of pneumonia in the cases with COPD. This was a nationwide, population-based, cohort study using National Health Insurance Program in Taiwan. The enrolled cases were newly-diagnosed COPD, older than 30 years, between 2001 and 2005. Patients’ prescriptions with PPIs and histamine receptor 2 antagonists (HR2As),>2 months, were identified. The appearance of pneumonia and mortality of these enrolled patients was recorded. Multivariate Cox’s regression was used to examine the influence of acid-suppressing drugs to pneumonia on individuals with COPD. A total of 17,498 patients were included, of whom 109 (0.6%) and 526 (3%) cases had used PPIs and HR2As respectively. The risk of pneumonia existed when patients had used concurrent PPIs (adjusted hazard ratio [HR] = 1.76; 95% confidence interval [CI] = 1.33-2.34) or HR2As (adjusted HR = 1.25; 95% CI = 1.07-1.47). The positive association was lost in the cases over 70 years. The ratio of mortality also increased in those with PPIs or HR2As. Acid-suppressing drugs, especially PPIs, are attributed to more pneumonia happening in COPD patients compare with nonusers. The association was lost in elderly cases. Use acid-suppressing drugs should be careful about a higher possibility of pneumonia in younger individuals with COPD.

Visfatin (also known as pre-B cell colony-enhancing factor) is increased in patients with chronic kidney disease and has been linked with coronary atherosclerosis. Given that it has been reported that visfatin plays a role in endothelial dysfunction in chronic kidney disease patients, we examined associations between visfatin levels and several markers related to atherosclerosis. The association between visfatin and atherosclerotic risk factors was studied in 173 chronic kidney disease patients (130 men and 43 women). Serum levels of visfatin were measured by the enzyme-linked immunosorbent assay. With increasing visfatin tertiles, patients proved to have a larger number of vessels with stenosis and a higher likelihood of coronary artery disease, as well as having incrementally lower estimated glomerular filtration rate and serum albumin and higher total leukocyte, neutrophil, and monocyte counts; high-sensitivity C-reactive protein; and brain natriuretic peptide levels. Visfatin showed significant positive correlations with low-density lipoprotein cholesterol, uric acid, blood urea nitrogen, creatinine, brain natriuretic peptide, E-selectin, total leukocyte count, neutrophil count, and high-sensitivity C-reactive protein, and a significant negative correlation with estimated glomerular filtration rate and albumin. Only E-selectin was independently associated with visfatin in multiple linear regression analysis. This study indicates that plasma visfatin levels are significantly higher in the presence of coronary artery disease and are correlated with E-selectin levels, which suggest that increased plasma visfatin may be involved in the pathogenesis of coronary atherosclerosis in CKD patients.

To report the outcomes of trabeculectomy with adjunctive 5-Fluorouracil (5-FU) at a Nigerian tertiary hospital. In this prospective study, all patients with glaucoma undergoing trabeculectomy with 5-FU at the University College Hospital, Ibadan, Nigeria, from June 2009 to May 2010 were enrolled. Each patient had a complete ophthalmic evaluation. Intraocular pressure (IOP), visual acuity (VA) and complications post-trabeculectomy were assessed at one year. Success of the procedure was defined as complete when no additional medications were required to achieve an IOP of? 18mmHg, or qualified when additional medications were required to achieve the same goal. A total of 47 eyes of 31 patients with mean age of 48.9±19.6 (range 14-77; median 52) years including 21 (67.7%) male subjects underwent trabeculectomy with 5-FU. Mean presenting IOP was 31.8±12.2 mmHg. Mean deviation (MD) on Humphrey visual fields was -15.9±9.7dB with the majority of the patients (18 subjects 58.1%) presenting with advanced glaucoma based on MD worse than -12dB and severe glaucomatous optic neuropathy (cup to disc ratio of 0.9-1.0). At 1 year postoperatively, 95.1% achieved qualified success while 83% had complete success. This prospective study adds to the existing knowledge that trabeculectomy with 5-FU is effective at controlling IOP in Nigerian patients.