An improved model of thin cylindrical piezoelectric layers between isotropic elastic media

AbstractRadially polarized piezoelectric fibers are now considered to be used in smart composites. The piezoelectric layers in these fibers are generally anisotropic in the transverse direction and therefore difficult to analyze when dynamic loads are involved. The present paper presents a theoretical study of the dynamic behavior of radially polarized cylindrical piezoelectric layers between isotropic elastic media. A new interphase model is developed to provide simple yet accurate evaluation of the dynamic response of such anisotropic elastic layers. Unlike the traditional interface-spring model, the current interphase model satisfies the equations of motion of the layers and can provide reliable prediction of the stress and displacement. A comparison between the developed model, the interface-spring model and the finite element analysis is conducted. The results clearly show the advantages of the current model over the traditional interface-spring model in simulating anisotropic layers. Numerical examples based on this interphase model for different interphase thicknesses, loading frequencies and material combinations are presented to evaluate the dynamic behavior of multilayered elastic media

Spatio-temporal variations of macrobenthic fauna in Lake Nasser khors, Egypt

AbstractSpatial and temporal variations of macrobenthic fauna in Lake Nasser khors, were studied at four subsequent seasons during 2013. Khor Tushka West recorded the highest average number (597Org./m2). It was decreased at khor Kursku (112Org./m2) and Kalabsha (105Org./m2) while it reached the lowest at khor Wadi Abyad (65Org./m2). The highest average number was recorded during spring (447Org./m2). It decreased during winter (174Org./m2) and summer (151Org./m2), then reached the lowest during autumn (107Org./m2). Annelida, Arthropoda and Mollusca were the most dominant groups in the lake during the study being 72.65%, 26.09% and 1.35%, respectively. The highest number of species (16) was observed at khor Kalabsha. This may be due to its nature of sandy bottom. Biological indices showed high richness values of all the studies khors except khor Tushka West.These low values of indices may be due to the dominance of Annelids species especially, Limnodrilus spp. and Branchiura sowerbyi. There is a positive correlation between these species and total annelids with all physico-chemical parameters. The analysis of variance between the different khors based on the main macrobenthic groups showed a highly significant value (p<0.001)

On the pseudo-incident wave technique for interacting inhomogeneities in electromechanical problems

The current paper presents the Pseudo-Incident Wave method for the theoretical treatment of the dynamic interaction between general inhomogeneities in advanced piezoelectric structures. Instead of simulating the response of such complicated systems using purely numerical or analytical methods, the current technique will take the advantages of the accuracy and reliability of analytical solutions and the flexibility of numerical methods. Using this method the original interaction problem is reduced to the solution of coupled single inhomogeneity problems, for which analytical solutions or simpler numerical solutions could be derived. By considering the consistency condition between different inhomogeneities, the steady state dynamic solution of multiple interaction problems can be formulated in terms of coupled single inhomogeneity solutions. The current method is very general and can provide reliable simulation of complicated interaction problems. Numerical examples are presented to illustrate the effectiveness of the Pseudo-Incident Wave method in simulating dynamic interaction between general inhomegeneities under complicated geometries

Irrigation and drainage in the new millennium

Presented at the 2000 USCID international conference, Challenges facing irrigation and drainage in the new millennium on June 20-24 in Fort Collins, Colorado.Includes bibliographical references.A field study was conducted at Mashtul Pilot Area MPA (260 feddans' 1 feddan = 4200 m2) situated at north Zagazig to evaluate the performance of the long term constructed subsurface drainage system. The evaluation of grades, alignment and clogging of drain lines can give an indication of the system performance and efficiency. Three drainage units served by the same collector were selected. Four 30 m interval PVC lateral pipes were installed at different depths. The results revealed that, the collector drain slopes were either steep or flat while the overall slope of the collector drain was considered steep for about 45.50% of the sections and flat for the rest. On the other hand, some sections showed an inverse slope which can cause a decrease in the discharge rate. The regularity was classified as good for about 82% of the sections and moderate for the rest. The slope of the lateral drains was correct for 41.7% of those under study (12 lateral drains), steep for 16.60%, and flat for the rest, and the regularity was classified as poor except lateral number 71 which had moderate regularity in the first approach while, in the second approach 41.67% had moderate regularity and poor for the rest. Also the deviation of the drain pipes from the straight line was generally larger than pipe diameter. Consequently, air entrapment and sedimentation resulted. The results also indicated that, the average height of sedimentation inside lateral drains was 12.70 mm (618.30 gm/m drain length) while for collector drains, sediment was in 22.88% of pipe diameter. The average reduction in discharge capacity due to sedimentation for laterals and collectors upstream and downstream parts were 17.17%, 32.80% and 17.60% respectively. Also using Manning, Visser and Wesseling equations leads to different safety factors

Modulation of L-arginine-induced acute pancreatitis by meloxicam and/or L-carnitine in rats

Background: Acute pancreatitis (AP) is an inflammatory disease, where oxidative stress, subsequently inflammatory mediators activation play a pivotal role. Currently, no definite treatment exists and therapy is mainly supportive that directed to inhibit local pancreatic injury and systemic inflammatory complications. This study is presented to explore whether anti-inflammatory and/or antioxidant drug could ameliorate L-arginine-induced AP.Methods: Rats were sub-grouped randomly into five groups. Control group, AP was provoked by a single intraperitoneal injection of L-arginine (250 mg/100g), rat treated with meloxicam (4 mg/kg, IP), animals treated with L-carnitine (500 mg/kg, IP), and rats were treated with both meloxicam and L-carnitine. All treatments were once daily for 7 consecutive days and started 1 hr later after L-arginine administration. Serum and tissues samples were prepared for biochemical analysis. Histopathological examination for the other pancreatic tissues was done.Results: L-arginine significantly elevated serum activity of amylase and lipase enzymes, while notably reduced serum calcium level. Moreover, L-arginine markedly increased the pancreatic tissues content of tumor necrosis factor-α, malondialdehyde, and nitric oxide. In addition, L-arginine significantly increased pancreatic activity of myeloperoxidase, while markedly depleted glutathione level. Treatment with either meloxicam or L-carnitine significantly attenuated L-arginine-induced biochemical changes. On the other hand, co-administration of both meloxicam and carnitine has an ameliorative effect greater than each drug alone.Conclusion: Treatment with both meloxicam and L-carnitine is a more effective than each of them alone which is attributed to augmentation their antioxidant, anti‑inflammatory effects

Spectrophotometric determination of the sulfhydryl containing drug mesna

AbstractFour simple and sensitive spectrophotometric methods were developed for the determination of the sulfhydryl containing drug mesna (MSN). Methods I and II rely on nucleophilic aromatic substitution reactions using two UV tagging reagents namely: 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) for method I and 2,4-dinitrofluorobenzene (DNFB) for method II. Both reactions took place in alkaline buffered medium and the obtained yellowish products were measured at 414 and 332nm for methods I and II, respectively. Methods III and IV are indirect spectrophotometric methods based on the suppressive effect of MSN on the absorption of two ternary complex systems which are composed of 1,10-phenanthroline, silver and eosin for method III and 1,10-phenanthroline, silver and bromopyrogallol red for method IV. The decrease in absorbance of the ternary complexes was measured at 547 and 635nm for methods III and IV, respectively. All the experimental parameters affecting these reactions were carefully studied and optimized. The methods were validated as per the ICH guidelines. The methods were applicable in the linearity ranges 4–18μg/mL for method I, 4–16μg/mL for method II, 0.25–2.25μg/mL for method III and 0.25–1.75μg/mL for method IV. The proposed methods were successfully applied for the analysis of MSN in its commercial ampoules and no interference was encountered from the present excipients as indicated by the satisfactory percentage recoveries. The results obtained were in a good agreement with those obtained from a previously published method of the investigated drug

Irrigation and drainage in the new millennium

Presented at the 2000 USCID international conference, Challenges facing irrigation and drainage in the new millennium on June 20-24 in Fort Collins, Colorado.Includes bibliographical references.Current global population growth rates require an increase in agricultural food production of about 40-50% over the next thirty to forty years, in order to maintain present levels of food intake. To meet the target, irrigated agriculture must play a vital role, in fact the FAO estimates that 60% of future gains will have to come from irrigation. The practice of controlling drainage involves the extension of on-farm water management to include drainage management. With the integration of irrigation and drainage management, the water balance can be managed to reduce excess water losses and increase irrigation efficiencies. Controlled drainage is relatively new and there are many theoretical and practical issues to be addressed. The technique involves maintaining high water table in the soil profile for extended periods of time, requiring careful management to ensure that crop growth is not affected by anaerobic conditions. A fieldwork programme has been investigated to test controlled drainage in the Nile Delta, where water resources are stretched to the limit. Water saving is essential in the next 20 years. Pressures from the fixed Nile water allocation, population growth, industry and other sectors and the horizontal expansion programme mean that this need is urgent. One crop season has been completed at a site in the Western Nile Delta using simple control devices in the subsurface drainage system. This paper discusses the potential benefits of controlled drainage to save water in agricultural areas such as the Nile Delta, and presents findings from the first crop season

Determination of medical waste composition in hospitals of Sana'a city, Yemen

The composition analysis of medical waste is generally considered to be the fundamental information for the most basic steps in the development of a plan for solid hospitals waste management. The objectives of this study were to determine the quantity, generation rate, and the physical composition of medical waste generated in hospitals of Sana'a city, Yemen. This cross-sectional, descriptive study was conducted on the composition of hospital wastes generated in four governmental hospitals in Sana'a City. Purposive sampling was used in the selection of the hospitals, which included (Al-Thawra, Al-Kuwait, Republic, and Military). Results of this study showed that the daily average of the waste generated from the studied hospitals was 5615 kg/day. Approximately 26% of the total waste was hazardous (infectious, pathological, and chemical wastes). While 74% was a general (non-hazardous) waste. The average rate of the total waste generation was 3 kg/patient/day, and 2.5 kg/bed/day. The mean individual components of generated waste in the studied hospitals were; foods 27%, plastic 22%, paper/cardboard 22%, glass 11%, metals 10%, and others 8%. In conclusion, about 26% of the waste was hazardous. The physical component analysis of the waste indicated that the foods, plastic, and paper/cartoon has the highest content of the hospitals waste. Decision makers in Yemen can use this study information for designing and plan the properly management for the collecting system and the healthy disposal of the hazardous waste. Also, for estimating the total policy of required facilities, manpower, and other related costs.Keywords: Composition; medical waste; hospitals waste; Yeme

Protective Effects of Simvastatin, a Lipid Lowering Agent, against Oxidative Damage in Experimental Diabetic Rats

The present study was undertaken to evaluate the possible protective effects of simvastatin (SMV) against oxidative stress in streptozotocin- (STZ)-induced diabetic rats. Diabetes was induced experimentally in rats by i.p. injection of STZ in a dose of 60 mg/kg bwt. After 5 weeks of STZ injection, there were apparent reductions in the animal body weight and significant increase in blood glucose, HbA1c, urea, creatinine, AST, ALT, and lipid profiles with a concomitant decrease in total hemoglobin, plasma glutathione and vitamin C as compared to the control group. The treatment with SMV at a dose (10 mg/kg, orally) normalized all the above-mentioned biochemical parameters in STZ-induced diabetic rats. In vitro studies confirmed the free radical scavenging and antioxidant activity of SMV. Therefore, the present results revealed that SMV has a protective effect against STZ-induced oxidative damage by scavenging the free radicals generation and restoring the enzymatic and nonenzymatic antioxidant systems