State of Charge of Lead Acid Battery

Lead acid batteries are used in hybrid vehicles and telecommunications power supply. For reliable operation of these systems, an indication of state of charge of battery is essential. To determine the state of charge of battery, current integration method combined with open circuit voltage, is being implemented. To reduce the error in the current integration method the dependence of available capacity as a function of discharge current is determined. The current integration method is modified to incorporate this factor. The experimental setup built to obtain the discharge characterstics of the battery is presented.

Direct precipitation of lead zirconate titanate by the hydrothermal method

Direct precipitation of fine powders of lead zirconate titanate (PZT) in the complete range of solid solution, is investigated under hydrothermal conditions, starting from lead oxide and titania/zirconia mixed gels. The perovskite phase is formed in the temperature range of 165 – 340°C. Sequence of the hydrothermal reactions is studied by identifying the intermediate phases. The initial formation of PbO: TiO2 solid solution is followed by the reaction of the same with the remaining mixed gels giving rise to X-ray amorphous PZT phase. Further, through crystallite growth, the X-ray crystalline PZT is formed. This method can be extended for the preparation of PLZT powder as well. The resulting powders are sinterable to high density ceramics.

Crystal data for high-temperature dicalcium lead propionate, Ca2Pb(CH3CH2COO)6

The high-temperature paraelectric phase of dicalcium lead propionate, DCLP, at 363 ± 5 K is tetragonal, with a = 12.574 (6), c = 17.403 (9) Å, V = 2751.4 Å3, Z = 4 and corresponds to the space group P41212 (or P43212). The thermal expansion curve shows the transition somewhere between 328 and 343 K.

Synthesis and characterization of a new sulphate derivative of hydrazine, N2H5HSO4

Hydrazinium(1 +) hydrogensulphate, N2H5HSO4, has been prepared for the first time by the reaction of solid ammonium hydrogensulphate with hydrazine monohydrate. The compound has been characterized by chemical analysis, infrared spectra, and X-ray powder diffraction. Thermal properties of N2H5HSO4 have been investigated using differential thermal analysis and thermogravimetric analysis and compared with those of N2H6SO4 and (N2H5)2SO4.

State of Charge of Lead Acid Battery

Lead acid batteries are used in hybrid vehicles and telecommunications power supply. For reliable operation of these systems, an indication of state of charge of battery is essential. To determine the state of charge of battery, current integration method combined with open circuit voltage, is being implemented. To reduce the error in the current integration method the dependence of available capacity as a function of discharge current is determined. The current integration method is modified to incorporate this factor. The experimental setup built to obtain the discharge characterstics of the battery is presented

Proton spin lattice relaxation in lithium ammonium sulphate LiNH4SO4

Lithium ammonium sulphate (LAS) undergoes a phase transition at TC1=459.5K from a paraelectric phase (phase I) to a ferroelectric phase (phase II) and again at TC2=283K to a polar ferroelastic phase (phase III). Proton spin lattice relaxation time measured at 10 MHz in powdered LAS in the temperature range 480 to 77K shows discontinuous changes at the two transitions.

Simplified Mathematical Model for Effects of Freezing on the Low-Temperature Performance of the Lead-Acid Battery

Discharge periods of lead-acid batteries are significantly reduced at subzero centigrade temperatures. The reduction is more than what can he expected due to decreased rates of various processes caused by a lowering of temperature and occurs despite the fact that active materials are available for discharge. It is proposed that the major cause for this is the freezing of the electrolyte. The concentration of acid decreases during battery discharge with a consequent increase in the freezing temperature. A battery freezes when the discharge temperature falls below the freezing temperature. A mathematical model is developed for conditions where charge-transfer reaction is the rate-limiting step. and Tafel kinetics are applicable. It is argued that freezing begins from the midplanes of electrodes and proceeds toward the reservoir in-between. Ionic conduction stops when one of the electrodes freezes fully and the time taken to reach that point, namely the discharge period, is calculated. The predictions of the model compare well to observations made at low current density (C/5) and at -20 and -40 degrees C. At higher current densities, however, diffusional resistances become important and a more complicated moving boundary problem needs to be solved to predict the discharge periods. (C) 2009 The Electrochemical Society.

Effect of pressure on the resistivity of lead oxide-lead halide glasses

Resistivity behaviour of PbO---PbX2 (X=F,Cl) glasses has been investigated as a function of pressure at laboratory temperature. All PbO---PbX2 glasses undergo crystallization under pressure and the resistivities of crystallized samples are lower than the corresponding glasses. Transitions in PbO---PbF2 glasses exhibit a first order behaviour while transitions in PbO---PbCl2 glasses possess features of a continuous transition. The differences in the pressure behaviour of the two glass systems have been attributed to the differences in the ionic sizes of F− and Cl− ions and also to pressure induced modifications of Pb---O bonding.

Lead-acid batteries for partial-state-of-charge applications

2 V/40 Ah valve-regulated lead-acid (VRLA) cells have been constructed with negative plates employing carbon black as well as an admixture of carbon black fumed silica as additives in negative active material for partial-state-of-charge (PSoC) applications. Electrical performance of such cells is compared with conventional 2 V/40 Ah VRLA cells for PSoC operation. Active material utilization has been found to be higher for carbon-black fumed-silica mixed negative plates while formation is faster for cells with carbon-black mixed negative plates. Both faradaic efficiency and percentage capacity delivered have been found to be higher for cells with carbon-black + fumed-silica mixed negative plates. However, a high self-discharge rate is observed for cells with carbon-black + fumed-silica mixed negative plates.

Small local variations in B-form DNA lead to a large variety of global geometries which can accommodate most DNA-binding protein motifs

An important question of biological relevance is the polymorphism of the double-helical DNA structure in its free form, and the changes that it undergoes upon protein-binding. We have analysed a database of free DNA crystal structures to assess the inherent variability of the free DNA structure and have compared it with a database of protein-bound DNA crystal structures to ascertain the protein-induced variations.

Two- and three-dimensional lead-1H-imidazole-4,5-dicarboxylates

Reaction of lead nitrate and 1H-imidazole-4,5-dicarboxylic acid under hydrothermal conditions carried out at different temperatures and pH yields a hybrid Compound Pb-2(1H-imidazole-4,5-dicarboxylate)2, 1, and a three-dimensional coordination polymer Pb(1H-imidazole-4,5-dicarboxylate), It. The two-dimensional double-layered compound, 1, with two-dimensional inorganic connectivities and one-dimensional organic connectivity is novel since hybrid compounds formed by 1H-imidazole-4,5-dicarboxylic acid are uncommon. The lead atoms in I have holodirectional geometry, while those in II show hemidirectionality. In both I and II, 1H-imidazole-4,5-dicarboxylic acid acts as a multi-dentate ligand with both the carboxylic groups and the amine group taking part in coordination. (C) 2009 Elsevier B.V. All rights reserved.

Recovery of intravenously infused chromium EDTA and lithium sulphate in the urine of cattle and their use as markers to measure urine volume

A series of metabolism experiments investigated the recovery of continuous-, intravenously infused chromium complexed with ethylenediamine tetra-acetic acid (CrEDTA) and lithium sulphate in the urine of cattle with a view to using the markers to estimate urine and metabolite output in grazing cattle. The recovery of Cr in urine from these infusions was similar (90%) in metabolism trials when cattle consumed three very contrasting diets: high-grain formulated pellet, lucerne hay (Medicago sativa) or low-quality native grass hay (predominantly Heteropogon contortus). By contrast, Li recovery in urine averaged 46.3 +/- 0.40% and 72.6 +/- 0.43% for native pasture and lucerne hays, respectively, but was not constant across days. There was negligible transfer of Cr from CrEDTA in blood serum to the rumen or faeces, whereas appreciable quantities of infused Li were found in both. The ratio of urine volume estimated by spot samples and marker dilution of Cr, to urine volume measured gravimetrically, was 1.05. In grazing studies using rumen-fistulated (RF) steers grazing seven different tropical and temperate grass and legume pastures, the ratio of concentrations of purine derivatives (PD) to Cr in spot samples of urine was shown to vary diurnally in the range of 49% to 157% of the average 24 h value. This finding indicated the need for regular sampling of urine to achieve an accurate average value for the PD: Cr ratio in urine for use in estimating urinary PD excretion and hence microbial protein production in the rumen. It was concluded that continuous, intravenous infusion of CrEDTA resulted in a constant recovery of Cr in the urine of cattle across diets and, provided an intensive sampling regime was followed to account for diurnal variation, it would be suitable as a marker to estimate urine volume and urinary output of PD in grazing cattle.

Glass Formation in the Ternary Sulphate System, K2S04-Na2S04-ZnS04

Glasses have been prepared by conventional quenching techniques in the ternary sulphate system KzSO4-Na2SO4-ZnSO4, in the range 30-80 % ZnS04. The proportions of alkali sulphates in the glass have been varied widely. The glass formation region has been delineated and densities, refractive indices and microhardnesses have been measured. The heat capacities of the glasses have been measured over a wide range of temperature by differential scanning calorimetry. The effect of composition on molar volume, molar polarization and glass transition have been explained on the basis of a random close-packing model.

Kinetics and mechanism of anodic oxidation of chlorate ion to perchlorate ion on lead dioxide electrodes

The kinetics and mechanism of anodic oxidation of chlorate ion to perchlorate ion on titanium-substrate lead dioxide electrodes have been investigated experimentally and theoretically. It has been demonstrated that the ionic strength of the solution has a marked effect on the rate of perchlorate formation, whereas the pH of the solution does not influence the reaction rate. Experimental data have also been obtained on the dependence of the reaction rate on the concentration of chlorate ion in the solution at constant ionic strength. With these data, diagnostic kinetic criteria have been deduced and compared with corresponding quantities predicted for various possible mechanisms including double layer effects on electrode kinetics. It has thus been shown that the most probable mechanisms for anodic chlorate oxidation on lead dioxide anodes involve the discharge of a water molecule in a one-electron transfer step to give an adsorbed hydroxyl radical as the rate-determining step for the overall reaction.