A Study on the Effectiveness of Bracing System for Lateral loading

An attempt has been made to study the reduction in responses of a structure under lateral loading due to the incorporation of a bracing system. In practice a building structure is subjected to eccentric loading due to the placement of different nonstructural elements within and above the structure. Due to the effect of eccentric loading a building normally experiences lateral as well as torsional displacement under seismic loading. Bracing system in any form increases the overall stiffness of the system and hence acts as a control mechanism for both lateral and torsional movement of the structure. In this study a single storey steel frame model is analyzed in a shake table for three different loading conditions namely frame without any extra mass, frame with a central mass and frame with an eccentric mass. A pair of X bracing system is then introduced to the structure and analyzed for the same three conditions. Comparisons are made for different responses namely lateral displacement, velocity, acceleration and torsional movement of the frame at roof level with and without bracing system. From the study it is clear that the bracing system is effective for reducing the lateral movement as well as the torsional effect to a great extent. Model study shows that a bracing system results in a reduction in the displacement at roof level up to about 80% as compared to that of an unbraced frame

Betel nut and tobacco chewing; potential risk factors of cancer of oesophagus in Assam, India

Cancer of the oesophagus is the most commonly diagnosed cancer in males in Assam, in north-eastern India, and ranks second for females. The chewing of betel nut, with or without tobacco and prepared in various ways, is a common practice in the region and a case–control study has been designed to study the pattern of risk associated with different ways of preparing and chewing the nuts. 358 newly diagnosed male patients and 144 female have been interviewed together with 2 control subjects for each case chosen at random from among the attendants who accompanied patients to hospital. There were significant trends in risk ratios associated with the frequency of chewing each day, with the duration of chewing in years and with the age at which the habit was started that were apparent for both males and females and which remained significant after allowance was made for other known risk factors, notably tobacco smoking and alcohol consumption. The adjusted ratios, in comparison with non-chewers, were 13.3 M and 5.7 F for chewing more than 20 times a day, 10.6 M and 7.2 F for persons who had chewed for more than 20 years and 10.3 M and 5.3 F for those who had started before the age of 20. Among the different combinations of ingredients that were chewed the adjusted odds ratios were highest for those who had been using fermented betel nut with any form of tobacco (7.1 M and 3.6 F). The risk associated with tobacco smoking and alcohol consumption, which are high in some parts of the world, were less in Assam than those associated with the chewing of betel nut. © 2001 Cancer Research Campaign http://www.bjcancer.co

Modeling of WEDM Parameters while Machining Mg-SiC Metal Matrix Composite

In this paper an attempt has been made to study the effects of the process parameters of wire cut electrical discharge machining (WEDM) on Magnesium-Silicon Carbide MMC with 5% SiC in particulate form. For the analysis, six factors, namely pulse on time, pulse off time, spark gap voltage, peak current, dielectric flushing pressure and servo feed have been taken and a Taguchi L16 orthogonal array for two levels was used. Response surface methodology was also used to develop second-order models for material removal rate (MRR) and surface roughness (SR). From the analysis of variances, it has been observed that pulse on time and pulse off time were the most significant parameters among all those observed in predicting the MRR and SR, respectively

Synthesis, characterization and antimalarial activity of hybrid 4-aminoquinoline-1,3,5-triazine derivatives

AbstractA novel series of hybrid 4-aminoquinolines-1,3,5-triazine were synthesized by means of aromatic nucleophilic displacement of chlorine atoms of 2,4,6-trichloro-1,3,5-triazine. Afforded title analogs were subsequently characterised by elemental analysis, FT-IR, 1H NMR, 13C NMR and mass spectroscopy and subjected to screening against chloroquine sensitive RKL2 strain of Plasmodium falciparum in 96 well-microtitre plates. However, synthesized derivatives exhibit mild to moderate antimalarial activity and acute toxicity studies of the most active (6a and 6g) compounds were shown to have no significant change in body insight and toxic sign

Short and Long-Term Sensitivity of Lab-Scale Thermocline Based Thermal Storage to Flow Disturbances

Molten-salt thermocline-based systems are a low-cost option for single-tank thermal energy storage in concentrated solar power plants. Due to the high variability in solar energy availability, these energy storage devices are subject to transient heat loads during charging that can affect the storage efficiency. Numerical simulations were conducted to analyze the stability characteristics of a lab-scale thermocline tank subject to a flow disturbance during charging under different operating temperatures. The charging process was first simulated at a constant Reynolds number for three different Atwood numbers; a stably stratified fluid layer develops inside the storage tank in all cases. A flow disturbance was then introduced at the inlet of the stratified thermocline tank by inserting colder fluid for a short period of time. The disturbance interacts with the thermocline and causes oscillations and mixing. The thermocline oscillations are under-damped and lead to an increase in thermocline region thickness. The transient behavior of the thermocline and the decay rate in its oscillations were analyzed; the damping time depends on the Atwood number. The persistence of flow disturbance effects during long-term cyclical operation was also investigated. Several charge/discharge cycles were simulated at constant Reynolds number to obtain a time-periodic thermal response for each Atwood number. The characteristic flow disturbance was introduced at the inlet during a single charging process, and the thermocline region was observed during several subsequent charge/discharge cycles to assess the long-term temporal attenuation of the disturbance. The thermocline almost fully recovers to the time-periodic behavior after a single cycle

Stereoselective total synthesis of bistramide A

A highly stereoselective and convergent total synthesis of bistramide A is described. The salient feature of this synthesis is the construction of the spiroketal subunit by hydrolysis of dialkylated tosylmethyl isocyanide derivative derived via alkylation of TosMIC with suitably substituted halohydrin derivatives

ANTIOXIDANT, ANTIBACTERIAL AND HEPATOPROTECTIVE ACTIVITIES OF CISSUS REPENDA VAHL ON CARBON TETRACHLORIDE (CCL4) INDUCED LIVER DAMAGE IN BIRD COLUMBA LIVIA

Objectives: Drug induced liver damage has been identified as one of the major global diseases in recent years. The plant derived alternative medicines are considered as the most effective solution for combating such liver diseases. In the present study, the antioxidant, antibacterial and hepatoprotective property of Cissus rependa Vahl. was evaluated. Methods: Anti-oxidant activity of the extracts were spectrophotometrically determined using ascorbic acid as standard. Determination of antimicrobial activity followed by Agar well diffusion method and nutrient content by standard laboratory methods. The activity of the two enzymes were measured spectrophotometrically (520 nm) following the DNPH method with minor modification   Results: The study shows that the aqueous extract of the plant leaf contains a good number of phytochemicals such as cardiac glycoside, saponin, alkaloid etc. as well as antioxidant with respect to the scavenging activity against free radicals DPPH (79.79 %) and ABTS (84.6%) which were roughly comparable to that of ascorbic acid (88.2% and 83.0 % respectively). The plant extract also exhibited potent antibacterial activity against S. aureus and P. vulgaris indicating its bactericidal or bacteriostatic properties. The study also indicates that the oral feeding of aqueous extract of the plant could reduce the CCl4 induced chronic damage of hepatic tissue in bird (C. livia) which was reflected by the decreased level of total soluble protein as well as activity of the enzymes Aspertate aminotransferase (AST) and Alanin aminotransferase (ALT) in both liver and muscle tissues of EX (experimental) group treated with plant extract as compared to that of untreated birds PC (positive control) group which otherwise had highly increased due to CCl4 induced tissue damages. Key words: Antioxidants, Cissus rependa Vahl, hepatotoxicity, Aspertate aminotransferas and phytochemicals