Optimization of control setting and size of shunt capacitors on distribution feeders

Loads on electric utility systems have two components: active power (measured in kilowatts) and reactive power (measured in kilovars). Active power has to be generated at the power plant, whereas reactive power can be provided by either power plants or capacitors. It is a well-known fact that shunt power capacitors are the most economical source to meet the reactive power requirements of inductive loads and transmission lines operating at a lagging power factor.This paper describes new contributions to the problem of optimization of size and control setting of shunt capacitors on distribution feeders, so that the losses along the feeder are minimized. The variation of the KVAR of the load on the feeder with the distance from the substation is assumed to be linear. The parameters of this function are estimated from the available KVAR loading on the feeder first by using least-square techniques and then by using least-absolute-value parameter estimation techniques. The results obtained are compared with that obtained if the current profile is assumed to be uniformly distributed on the feeder. Our results show that the optimum size of the capacitor bank as well as its optimum location depend on the parameters of the model used for the load. Also, our results show a large saving in the size of the capacitor banks used with a considerable per-unit-loss reduction along the feeder.This work was supported by the National Science and Engineering Research Council of Canada, Grant No. A4146. The first author acknowledges the help received from Engineer Samy Soliman for reviewing all the mathematical expressions in this paper.     

Spectrophotometric study of the reaction mechanism between DDQ as pi-acceptor and potassium iodate and flucloxacillin and dicloxacillin drugs and their determination in pure and in dosage forms

Two simple and accurate spectrophotometric methods are presented for the determination of beta-lactam drugs, flucloxacillin (Fluclox) and dicloxacillin (Diclox), in pure and in different pharmaceutical preparations. The charge transfer (CT) reactions between Fluclox and Diclox as electron donors and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) pi-acceptor and potassium iodate via oxidation reduction reaction where the highly coloured complex species or the liberated iodine have been spectrophotometrically studied. The optimum experimental conditions have been studied carefully. Beer's law is obeyed over the concentration range of 2-450 microg ml(-1) for Fluclox and 10-450 microg ml(-1) for Diclox using DDQ reagent and at 50-550 microg ml(-1) for Fluclox and 50-560 microg ml(-1) for Diclox using iodate method, respectively. For more accurate results, Ringbom optimum concentration range is calculated and found to be 6-450 and 15-450 microg ml(-1) for Fluclox and Diclox using DDQ, respectively, and 65-550 and 63-560 microg ml(-1) for Fluclox and Diclox using iodine, respectively. The Sandell sensitivity is found to be 0.018 and 0.011 microg cm(-2) for DDQ method and 0.013 and 0.011 microg cm(-2) for iodate method for Fluclox and Diclox, respectively, which indicates the high sensitivity of both methods. Standard deviation (S.D.=0.01-0.80 and 0.07-0.98) and relative standard deviation (R.S.D.=0.13-0.44 and 0.11-0.82%) (n=5) for DDQ and iodate methods, respectively, refer to the high accuracy and precision of the proposed methods. These results are also confirmed by between-day precision of percent recovery of 99.87-100.2 and 99.90-100% for Fluclox and Diclox by DDQ method and 99.88-100.1 and 99.30-100.2% for Fluclox and Diclox by iodate method, respectively. These data are comparable to those obtained by British and American pharmacopoeias assay for the determination of Fluclox and Diclox in raw materials and in pharmaceutical preparations.     

Synthesis and QSAR Study of Some Novel Heterocyclic Derivatives as In Vitro Cytotoxic Agents

2,3‐Diaryloxirane‐2,3‐dicarbonitriles have employed in heterocyclic synthesis in many organic reactions. Authors highlight its use as intermediate in the synthesis of various organic compounds through the reaction with different nitrogen nucleophiles as methyl hydrazine, thiourea, thiosemicarbazide, methylglycinate, and others to furnish new heterocyclic derivatives. They are also used as key starting materials to construct some important heterocycles. Structures of all newly synthesized products are substantiated by studying their micro analytical and spectral data. Some of newly synthesized compounds were evaluated for their in vitro cytotoxic effects against a panel of three human tumor cell lines, namely, Hep‐G2, Hela, and MCF‐7. Most of the newly synthesized compounds ( 1a , 2a , 2d , 3 , 4 , 5 , 6a , 6c , 6d , 7a , and 7b ) inhibited cell proliferation with IC₅₀ values in range of 0.52–5.21 μΜ. For activity against HepG2 cell line, compounds 5 , 6a , 6d , and 7b emerged as the most active members. The Hela cell line showed highest sensitivity toward compounds 2a , 2d , and 6c whereas compounds 2d and 6c showed the highest inhibitory activity against MCF‐7 cell line.     

Structure investigation of mesalazine drug using thermal analyses,mass spectrometry,DFT calculations,and NBO analysis

Mesalazine (MZ) drug has been used for several decades as a primary treatment for inflammatory bowel diseases. The drug was investigated using thermal analysis (TA) measurements and electron impact mass spectral fragmentation at 70 and 15 eV of electron energy. The optimum molecular geometry and the total energy of the neutral and the positively charged MZ molecules were calculated by density functional theory method with 6-311++G(d,p) basis sets. Stability of the molecules arising from hyperconjugative interactions, charge delocalization, and the natural atomic charges has been analyzed using natural bond orbital analysis. In electron ionization mass spectrometry, the primary rupture is due to successive loss of H₂O (OH from carboxyl and H from phenolic OH of the ring) and CO of the acetyl group. Thermogravimetric results have revealed two stages of mass loss at 75.3 and 25.3 % in ranges 225–350 and 350–650 °C, respectively. The first one may be due to successive losses of different groups or molecules with fast rate of decomposition. A comparison between MS and TA helped in selection the proper pathway representing the fragmentation mechanism of this drug.     

Novel Thorium Membrane Sensors with Anionic Response Based on Trioctylphosphine Oxide and Toluate Ionophores

Two novel potentiometric polymeric membrane sensors for rapid and accurate determination of thorium are described. These are based on the use of trioctylphosphine oxide (TOPO) and thorium toluate (Th‐TA) as ionophores dispersed in poly(vinyl chloride) matrix membranes plasticized with nitrophenyloctyl ether. In strong nitric acid medium, Th(IV) nitrate is converted into [Th(NO₃)₆]^2? complex and sensed as anionic divalent ion which exclude most cationic effect. Validation of the assay methods using the quality assurance standards (linearity range, accuracy, precision, within‐day variability, between‐day‐repeatability, lower detection limit and sensitivity) reveals excellent performance characteristics of both sensors. The sensors exhibit near‐Nernstian response for 1.0×10^?6–1.0×10^?1 M Th over the pH range 2.5–4.5. Calibration slopes of ?32.3±0.3 and ?27.2±0.2 mV/decade, precision of ±0.5 and ±0.8% and accuracy of 98.8±0.9 and 97.9±0.7% are obtained with TOPO and Th‐TA based sensors, respectively. Negligible interferences are caused by most interfering mono‐, di‐, tri‐, tetra‐, penta‐, and hexa‐valent elements commonly associated with thorium in naturally occurring minerals and ores. High concentrations of Cl^?, F^?, SO₄^2?, and NO₃^? ions have no diverse effect. Complete removal of the effect of the interferents in complex matrices is achieved by retention of [Th(NO₃)₆]^2? complex from 5 M nitric acid/methanol mixture (1 : 9 v/v) on a strong anion exchanger, washing out the cationic interferents followed by stripping off thorium anion complex and measurements. Both sensors are used for determining thorium in certified thorium ore samples (20–120 mg Th/kg) and some naturally occurring ores (200–600 mg Th/kg). The results obtained agree fairly well with the certified labeled values or the data obtained using X‐ray fluorescence spectrometry     

Oxymatrine Loaded Cross-Linked PVA Nanofibrous Scaffold: Design and Characterization and Anticancer Properties

This study focuses on the fabrication, characterization and anticancer properties of biocompatible and biodegradable composite nanofibers consisting of poly(vinyl alcohol) (PVA), oxymatrine (OM), and citric acid (CA) using a facile and high-yield centrifugal spinning process known as Forcespinning. The effects of varying concentrations of OM and CA on fiber diameter and molecular cross-linking are investigated. The morphological and thermo-physical properties, as well as water absorption of the developed nanofiber-based mats are characterized using microscopical analysis, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. In vitro anticancer studies are conducted with HCT116 colorectal cancer cells. Results show a high yield of long fibers embedded with beads. Fiber average diameters range between 462 and 528 nm depending on OM concentration. The thermal analysis results show that the fibers are stable at room temperature. The anticancer study reveals that PVA nanofiber membrane with high concentrations of OM can suppress the proliferation of HCT116 colorectal cancer cells. The study provides a comprehensive investigation of OM embedded into nanosized PVA fibers and the prospective application of these membranes as a drug delivery system.     

Synthesis and antimicrobial evaluation of novel 1,3-thiazoles and unsymmetrical azines

Research on Chemical Intermediates - 1,3-Thiazol derivatives have been synthesized via reaction of 1-(1-(5,6-dimethoxy-2-oxobenzo[d]thiazol-3(2H)-yl)propan-2-ylidene)-4-substituted...     

Cytotoxity of two new coumarin derivatives isolated from Launaea mucronata

The chloroform fraction of methanol (MeOH) extract of the aerial parts of Launaea mucronata was in vitro investigated for cytotoxicity against HCT116, HepG2 and MCF-7 cell lines, and resulted with IC₅₀ = 20.0, 18.6 and 14.30 μg/mL, respectively. The chloroform fraction of the MeOH extract was subjected to further fractionation, which led to the isolation of two new coumarin compounds (6-isobutyl coumarin and 6-isobutyl-7-methyl- coumarin). The structures of the new compounds were elucidated by high field 1D and 2D NMR and ESI-MS spectroscopies. Low polar fractions revealed the isolation of other known triterpene compounds which were identified according to its spectral data and comparison with the literature. New coumarin compounds show high cytotoxicity against MCF-7, HCT116 and HepG2 cell lines.