11,092 research outputs found
Synthesis and Antimicrobial Activity of Some 2-Amino-4-(7- Substituted/Unsubstituted Coumarin-3-yl)-6-(Chlorosubstitutedphenyl) Pyrimidines
Purpose: To prepare some 2-amino 4- (7-substituted/unsubstitutedcoumarin-3-yl)-6-(chlorosubstitute dphenyl) pyrimidines as antimicrobial agents.Methods: Some 2-amino-4-(7-substituted/unsubstitutedcoumarin-3-yl)-6-(chlorosubstitutedphenyl) pyrimidines were prepared by reacting 3-chlorosubstitutedphenyl-1-(7-substituted/unsubstituted coumarin 3-yl)prop-2-ene-1-ones with guanidine carbonate. The chemical structures of the synthesized compounds were elucidated by Fourier transform infra-red spectroscopy (FTIR), 1H-nuclear magnetic resonance (1H-NMR), mass spectrometry and elemental analysis. The synthesized compounds were investigated for their antimicrobial activity against four bacteria and five fungi by serial plate dilution method using ofloxacin and ketoconazole as reference antimicrobial drugs, respectively, and their minimum inhibitory concentrations (MICs) were determined.Results: Compounds 1 (p < 0.0001), 2 (p < 0.0001), 6 (p < 0.0001) and 8 (p < 0.0001) were the most active antibacterial agents among the synthesized compounds compared to control and standard agents. Structure-activity relationship revealed that substitution of chlorine atoms at 2- and 6- positions of the phenyl ring are critical for antibacterial activity in the case of dichlorophenyl derivatives, while for monochlorophenyl derivatives, the positions 2 and 4 of the phenyl ring were critical for antibacterial activity. None of the compounds exhibited comparable antifungal activity to the standard antifungal drug, ketoconazole, even at high concentrations.Conclusion: It is evident that the synthesized compounds are relatively very active antibacterial agents but are weak antifungal agents. However, these compounds need further evaluation of their antibacterial activity against other bacterial strains to ascertain their broad spectrum antibacterial activity.Keywords: Pyrimidine, Coumarin, Antibacterial, Antifungal, Structure-activity Relationshi
Are clinicopathological factors predictive of bactibilia in biliary tract diseases?
Background: Biliary tract disease is very common in Indian side of Jammu and Kashmir and because of this we got prompted to undertake a study to find out the association between presenting features and bactibilia.Methods: The study was conducted prospectively on 121 patients of various biliary tract disorders in the Department of Surgery, Government Medical College Jammu, India prospectively over a period of one year from March 2003-February 2004. Details of age, history, radiology, operation and postoperative course were noted and information obtained recorded on special forms. All the patients included in this study were given single shot of preoperative antibiotic at the induction of anaesthesia and antibiotics modified postoperatively on the culture report.Results; After recording the observations made while managing these patients of biliary tract disease the results were analysed and entered into the individual patient’s protocol. The age range of our series of 121 patients was 15-74 years with a mean age of 42.5 years. There were 100 females and 21 males with male to female ratio of 4.7:1. Abdominal pain was the commonest symptom (98.3%) followed by dyspepsia (47.1%), abdominal lump (16.5%), jaundice (9.9%) and cholangitis (3.3%).Most of the patients had more than one presentation. Out of 121 cases 42(34.7%) turned out to be culture positive and rest of the cases turned out to be culture negative. In culture positive cases aerobes were identified in 38 (34.1%) and anaerobes were identified in 10 (8.2%) patients. The results of gram stain of bile were compared with bile cultures. Out of 121 patients gram staining was positive in 51(42.1%) patients. Among these patients bile cultures were positive in 42 (82.3%) patients.Conclusion: It was concluded that the presence or absence of bactibilia can predict possibility to stratify patients in low and high risk group so that necessary pre-emptive measures be taken
Switched-capacitor integrated single-phase (2n+1)-levels boost inverter for grid-tied photovoltaic (pv) applications
© 2019 IEEE. This paper presents a switched-capacitor integrated (2N+1)-level (N≥2) boost inverter for single-phase photovoltaic (PV) applications. It consists of N modular switching cells, where each cell consists of two switched capacitors and three active switching elements. A boost converter at the front side of the switching cells helps to maintain the capacitor voltage balance during different operation modes. With this arrangement, the inverter is capable to generate 2N+1 output voltage levels, and able to accommodate a wide range of input voltage. Detailed analysis followed by simulation and experimental results of a 5-level inverter as an example is presented to verify the proposed concept. Further, comparison with other multilevel inverter topologies is presented to show the merit of the proposed concept
Prevalence of Chronic airflow limitation in Kashmir, North India: Results from the BOLD study.
BACKGROUND: Data on spirometrically defined chronic airflow limitation (CAL) are scarce in developing countries. OBJECTIVE: To estimate the prevalence of spirometrically defined CAL in Kashmir, North India. METHODS: Using Burden of Obstructive Lung Disease survey methods, we administered questionnaires to randomly selected adults aged 40 years. Post-bronchodilator spirometry was performed to estimate the prevalence of CAL and its relation to potential risk factors. RESULTS: Of 1100 participants initially recruited, 953 (86.9%) responded and 757 completed acceptable spirometry and questionnaires. The prevalence of a forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) ratio less than the lower limit of normal was 17.3% (4.5) in males and 14.8% (2.1) in females. Risk factors for CAL included higher age, cooking with wood and lower educational status. The prevalence of current smoking was 61% in males and 22% in females; most smoked hookahs. CAL was found equally in non-smoking males and females, and was independently associated with the use of the hookah, family history of respiratory disease and poor education. A self-reported doctor's diagnosis of chronic obstructive pulmonary disease was reported in 8.4/1000 (0.9% of females and 0.8% of males). CONCLUSION: Spirometrically confirmed CAL is highly prevalent in Indian Kashmir, and seems to be related to the high prevalence of smoking, predominantly in the form of hookah smoking
Phytotoxic, insecticidal and leishmanicidal activities of aerial parts of Polygonatum verticillatum
The aim of the present study was to explore the aerial parts of the Polygonatum verticillatum for variousbiological activities such as phytotoxic, insecticidal and leishmanicidal properties. Outstandingphytotoxicity was observed for the crude extract and its subsequent solvent fractions against Lemnaacquinoctialis Welv at tested doses of 5, 50 and 500 ìg/ml. Complete growth inhibition (100%) wasdemonstrated by the crude extract and aqueous fraction at maximum tested dose (500 ìg/ml). Amongthe tested insects, moderate insecticidal activity was recorded against Rhyzopertha dominica. However,neither crude extract nor its solvent fraction registered any significant (> 100 ìg/ml) leishmanicidalactivity against Leishmania major. Based on the phytotoxicity, the aerial parts of the plant could be asignificant source of natural herbicidal for sustainable weed control
Confirmation of sunflower F1 hybrids using SDS-PAGE analysis
Among bio-chemical techniques, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDSPAGE) is most widely used due to its validity and simplicity for describing genetic structures of group of plants. In the present study, SDS-PAGE was used to confirm sunflower hybrids. Four male sterile lines, four restorer lines and their sixteen F1 hybrids were analyzed. Based on results of electrophoretic band spectra, Jaccard’s similarity index (S) was calculated for all possible pairs. The similarity matrix, thus, generated was converted to a dissimilarity matrix and used to construct dendrogram, using unweighed pair-group method with arithmetic means. Euclidean distance of 1.0 was observed among 5 comparisons, whereas maximum distance (3.87) was observed for 1 comparison only. In most of the cases, female parents, along with their respective crosses, were found in one cluster, indicating thatSDS-PAGE can be used reliably for the identification of hybrids in sunflower
Pharmacokinetic Studies on Metoprolol - Eudragit Matrix Tablets and Bioequivalence Consideration with Mepressor®
Purpose: To investigate the pharmacokinetics of of a developed metoprolol and a reference standard (Mepressor®).Methods: Metoprolol tartrate-loaded Eudragit® FS microparticles were formulated and compressed into tablets. The tablets were tested for their physicochemical properties according to United States Pharmacopoeia (USP) criteria. In vivo studies of the formulations were carried out in 28 young healthy fasting male volunteers based on a randomized open label 4×4 crossover study design with a washout period of 7 days.Results: In vitro tests showed that the developed and reference standard of metoprolol tablets met compendia (USP) requirements. Zero order release of drug was observed from all the tablets. In vivo data demonstrated that there were significant (p < 0.05) differences in tmax, Cmax, MRT, AUC0−t, and AUC0–∞ between the reference and test (developed) formulations. However, the 90 % class interval for the mean ratios of the ln-transformed Cmax, AUC0-t and AUC0-α for the reference, T1, T2, and T3 lied in the bioequivalence range (80 to 125 %) indicating bioequivalence between the compared formulations. Conclusion: It can be concluded from this single-dose study that the reference and test (developed) formulations met the predetermined criteria for bioequivalence in young healthy fasting male human subjects as the bioequivalence factor lie in the pre-determined limits for bioequivalence. Thus, the two formulations can be considered bioequivalent.Keywords: Metoprolol tartrate, Eudragit® FS, Microparticles, Bioavailability, Pharmacokinetics
Model Predictive Observer Based Control for Single-Phase Asymmetrical T-Type AC/DC Power Converter
© 1972-2012 IEEE. This paper presents a robust control strategy for the control of single-phase five-level asymmetrical T-type ac/dc power converter. A cascaded control scheme consisting of a finite control set model predictive control (FCS-MPC) with an extended state observer (ESO) is proposed to govern the converter. In this scheme, a proportional integral (PI) controller combined with an ESO-based disturbance observer is employed as an external control loop. This control loop dynamically modifies the active power reference to realize the desired operating point of the system state (converter output voltage). The proposed control system presents a high degree of disturbance rejection capability and robustness against the external disturbances to the converter, whereas the conventional PI control performance suffers in the presence of these disturbances. In this paper, the inner current tracking loop is accomplished by an FCS-MPC algorithm. This algorithm is derived to force the input currents to track the reference values while realizing a user-defined reactive power and maintaining balanced voltages in the series-connected capacitors. Theoretical analysis and the design procedure of the proposed control system are presented. Finally, experimental studies are conducted to verify the effectiveness of the proposed control scheme
A high efficiency transformerless PV grid- Connected inverter with leakage current suppression
© 2016 IEEE. This paper presents a new diode free freewheeling and common-mode voltage (CMV) clamping branches for single phase transformerless grid connected photovoltaic (PV) inverter for complete leakage current elimination and low conduction losses. In the past, various isolation techniques have been proposed for leakage current elimination in transformerless PV inverters. However, galvanic isolation only cannot completely eliminate leakage current due to that a resonant path is created by the switch junction capacitors, which also generate leakage current. The proposed freewheeling branch consists of four MOSFETs along with a clamping branch, which consists of two MOSFETs and a capacitor divider. The divider is connected to the DC side of the converter to keep constant CMV in the freewheeling path. As a result, the improved CMV clamping has been achieved for complete leakage current elimination. The unipolar sinusoidal pulse width modulation (SPWM) technique and modified HERIC topology with AC-decoupling for galvanic isolation is adopted for lower conduction losses. The proposed topology consists of only MOSFET in the freewheeling and clamping path which provides lower conduction losses compared with diode based topologies. The performances of the proposed topology in terms of common mode characteristics, leakage current, total harmonic distortion and conversion efficiency are analyzed and compared with H5, H6, HERIC and HBZBR topologies. The detail analyses are performed using MATLAB/Simulink and PSIM
Model predictive control applied to a single phase seven-level active rectifier
© 2017 IEEE. This paper presents an improved single phase seven-level active rectifier architecture controlled by finite control set model predictive control (FCS-MPC). The FCS-MPC is designed to enable power conversion with a unity power factor and generate seven level voltage waveform at the input. The proposed active rectifier architecture reduces harmonic contents of the rectifier input current by producing different voltage levels at the rectifier input. Owing to the architecture and multilevel operation, it reduces the EMI filter size, input current harmonic, the voltage rating on devices and switching losses that are lower than those of conventional three-level rectifier topologies. The proposed converter can also be operated as a multilevel inverter. Extensive simulation results are presented to verify the proposed converter when the load changes, the reference active and reactive power changes
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