Parametric study on dynamic behavior of rectangular concrete storage tanks

Tanks are used to store a wide variety of liquids such as oil, gasoline and water. It is reported that, a large number of tanks have been damaged during severe earthquakes. Therefore, understanding their behavior under earthquake is an important subject for structural engineers. In this paper, a comprehensive study is presented on dynamic response of tanks. A parametric study has been completed on the rectangular storage tanks with aid of finite element method (FEM). Various parameters are investigated, such as; liquid height, density and earthquake with different peak ground acceleration (PGA). When investigating these parameters, modal and time history method is used. Six different earthquake records are used for time history analysis. The analysis results show that when the PGA increases by 10.7 times, the maximum displacements, stress, sloshing and base shear increase by 11.4, 22.6, 5.46 and 17.8 times, respectively and when the liquid height increases by two times, the absolute maximum values of stress, displacements, base shear and sloshing increase 1.65, 2.04, 2.05 and 1.34. Furthermore, values of sloshing increase with decrease in density

The national energy requirements of residential windows in the U.S.: Today and tomorrow

This paper describes an end-use analysis of the national energy requirements of US residential window technologies. The authors estimate that the current US stock of 19 billion square feet of residential windows is responsible for 1.7 quadrillion BTUs (or quads) per year of energy use--1.3 quads of heating and 0.4 quads of cooling energy--which represents about 2% of total US energy consumption. They show that national energy use due to windows could be reduced by 25% by the year 2010 through accelerated adoption of currently available, advanced window technologies such as low-e and solar control low-e coatings, vinyl and wood frames, and superwindows. The authors evaluate the economics of the technologies regionally, considering both climatic and energy price variations, and find that the technologies would be cost effective for most consumers

A Comparison Between the Hemodynamic Effects of Cisatracurium and Atracurium in Patient with Low Function of Left Ventricle who are Candidate for Open Heart Surgery

BACKGROUND: The need for muscle relaxants in general anesthesia in different surgeries including cardiac surgeries, and the type of relaxant to be used considering its different hemodynamic effects on patients with heart disease can be of considerable importance. In this study, the hemodynamic effects of two muscle relaxants, Cisatracurium and Atracurium in patients whit low function of left ventricle who are candidate for open heart surgery have been considered. METHOD: This study has been designed as a randomized prospective double-blind clinical trial. The target population included all adult patients with heart disease whose ejection fraction reported by echocardiography or cardiac catheterization was 35 or less before the surgery, and were candidate for open heart surgery in Shahid Rajaei Heart Center. Taking into account the inclusion and exclusion criteria, the patients were randomly placed in two groups of 30 people each. In the induction stage, all the patients received midazolam, etomidate, and one of the considered muscle relaxant, either 0.2 mg/kg of cisatracurium or 0.5mg/kg of Atracurium within one minute. In the maintenance stage of anesthesia, the patients were administered by infusion of midazolam, sufentanil and the same muscle relaxant used in the induction stage. The hemodynamic indexes were recorded and evaluated in different stages of anesthesia and surgery as well as prior to transfer to ICU. RESULTS: In regard with descriptive indexes (age and sex distributions, premedication with cardiac drugs, ejection fraction before surgery, basic disease) there was no statistically significant difference between the groups. CONCLUSIONS: The significant difference of hemodynamic indexes between the two groups of this study, and the need for hemodynamic stability in all stages of surgery for patients with low function of left ventricle who are candidate for open heart surgery, proves that administering Cisatracurium as the muscle relaxant is advantageous and better

Biodiversity of the ground beetles (Coleoptera: Carabidae) in orchard ecosystems of Azadshahr region, Golestan province, Iran

The coleopteran family Carabidae is one of the most abundant and diverse generalist predators in agroecosystems, playing an important role in maintaining pest populations below economic threshold. Using pitfall traps, carabid beetle specimens were collected from olive, peach, and mixed peach-olive orchards in Azadshahr region, east of Golestan province in 2009-2010. Two indices of Shannon-Weaver and Margalef were employed to evaluate the diversity and structure of the beetle communities. The species richness of ground beetles was 31, 19, and 12 species in mixed olive-peach, peach, and olive orchards; and the dominant species were Harpalus rufipes (De Geer), H. rufipes and Calathus peltatus Kolenati, respectively. The values of Brillouinâs index of evenness and Shannonâs index of diversity were calculated as 0.46 ± 0.04, 0.51 ± 0.07, 0.65 ± 0.13 and 1.59 ± 0.18, 1.52 ± 0.21, 1.57 ± 0.23, respectively. There was no significant difference in overall Shannonâs indices, but the evenness of ground beetles in olive orchards was significantly higher than other orchards. The community of ground beetles on orchard margins was found to be more diverse than central parts. The high diversity of ground beetles in orchards of this region underlines their role in protecting the diversity of vegetations around or within the orchards and also efficiently keeping the populations of economic orchard pests in check throughout the season

Tetrazole compounds: The effect of structure and pH on Caco-2 cell permeability

A tetrazole ring is often used in drug discovery as a replacement for the carboxylic acid group. Previous work indicates that compounds containing a tetrazole moiety show asymmetric permeability in Caco-2 cells characteristic of an efflux transporter substrate. The aim of this study is to determine which transporters are responsible for polarization of transport of tetrazole-containing compounds in Caco-2 cells. Results indicate that only select compounds with tetrazole moieties display asymmetric transport. Three compounds (two commercial drug products and one druglike structure) were selected for further studies. Losartan appears to be primarily a P-glycoprotein (P-gp) substrate, as previously reported, but MRP inhibitors such as MK-571 and rifampicin also affect the difference between apical to basolateral and basolateral to apical transport. Pemirolast and phenyltetrazole derivative C are sensitive to P-gp inhibition, but transport seems to be mediated by one or more of the MRP family of transporters. Additionally, lowering the pH from 7.4 to 4.0 eliminates the polarization of permeability in Caco-2 cells. These studies indicate that some tetrazole compounds are susceptible to efflux, therefore caution should be used when choosing an appropriate functional group to replace carboxylic acids when synthesizing a drug candidate. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:717–725, 200

Quantitative analysis of lab-to-lab variability in Caco-2 permeability assays

In this study, Caco-2 permeability results from different laboratories were compared. Six different sets of apparent permeability coefficient (Papp) values reported in the literature were compared to experimental Papp obtained in our laboratory. The differences were assessed by determining the root mean square error (RMSE) values between the datasets, which reached levels as high as 0.581 for the training set compounds, i.e. ten compounds with known effective human permeability (Peff). The consequences of these differences in Papp for prediction of oral drug absorption were demonstrated by introducing the Papp into the absorption and pharmacokinetics simulation software application GastroPlus™ for prediction of the fraction absorbed (Fa) in humans using calibrated “user-defined permeability models”. The RMSE were calculated to assess the differences between the simulated Fa and experimental values reported in the literature. The RMSE for Fa simulated with the permeability model calibrated using experimental Papp from our laboratory was 0.128. When the calibration was performed using Papp from literature datasets, the RMSE values for Fa were higher in all cases except one. This study shows quantitative lab-to-lab variability of Caco-2 permeability results and the potential consequences this can have in the use of these results for predicting intestinal absorption of drugs

Frequency fluctuations in silicon nanoresonators

Frequency stability is key to performance of nanoresonators. This stability is thought to reach a limit with the resonator's ability to resolve thermally-induced vibrations. Although measurements and predictions of resonator stability usually disregard fluctuations in the mechanical frequency response, these fluctuations have recently attracted considerable theoretical interest. However, their existence is very difficult to demonstrate experimentally. Here, through a literature review, we show that all studies of frequency stability report values several orders of magnitude larger than the limit imposed by thermomechanical noise. We studied a monocrystalline silicon nanoresonator at room temperature, and found a similar discrepancy. We propose a new method to show this was due to the presence of frequency fluctuations, of unexpected level. The fluctuations were not due to the instrumentation system, or to any other of the known sources investigated. These results challenge our current understanding of frequency fluctuations and call for a change in practices

A UK practitioner view of domestic energy performance measurement

There is a growing body of evidence concerning the energy efficiency performance of domestic buildings in the UK, driven by policy-based agenda, such as the need for zero carbon dioxide homes by 2016 for new build homes, and Green Deal and energy company obligation for sustainable refurbishment. While there have been a number of studies funded and results presented in this area, little work has been done to understand the drivers, practices and issues of data collection and analysis. There are a number of major building performance evaluation (BPE) studies in the UK, yet behind many of these research projects are practical issues of data loss, experimental error, data analysis variances and resident issues that are common when studies move from the actual to the living lab. In this paper the issues of domestic energy are addressed by leading BPE practitioners in the UK. They identify issues of client demands, technical failure, costs and implementation. The work provides insights of both academic and industry-based practitioners and considers not only the practicalities of building performance studies, but also implications for these types of studies in the future