The impedance of the alkaline zinc-mercuric oxide cell. I. Cell behaviour and interpretation of impedance spectra

The impedances of small (2400 mA h) alkaline Zn-HgO cells have been measured in the range 10 kHz-0.001 Hz at various states of charge from fully charged to fully discharged. The behaviour of the cell conforms to that expected for rate control by charge transfer at the zinc electrode and diffusion in solution. At low frequencies there is a relaxation in the diffusive circuit elements which ultimately results in a complete suppression of the capacitative component of the impedance at zero frequency. The low-frequency behaviour is analogous to convective diffusion and is due to the effective distance between the electrodes being small compared with the characteristic length (D/)^1/2. The magnitude of the charge transfer resistance is the best measure of the state of charge.Nomenclature a effective electrode separation - C _DL double-layer capacitance of cell - C _R capacitative component of cell impedance - C concentration difference - D percentage discharge in Equation 12 - D _i diffusion coefficient of speciesi - R ohmic resistance of cell - R _R resistive component of cell Faradaic impedance - Ui constant defined by Equation 10 - Z total cell impedance - Z _F cell Faradaic impedance - Z _F cell impedance modified for porosity effect - Z _x cell impedance of Faradaic component plus double layer - cell Warburg coefficient (slope ofR _R and 1/C _Rversus su}-1/2) - _C Warburg coefficient calculated fromC _r values - _i cell Warburg coefficient for speciesi - Warburg coefficient calculated fromR _R values - dihedral angle of tail of Sluyters plot (after coming-off high-frequency semicircle) - angular frequency     

Formation of γ-ketols from 13- and 9-hydroperoxides of linolenic acid by flaxseed hydroperoxide isomerase

A reexamination of the flaxseed hydroperoxide isomerase reaction showed that a minor enzymic product (ca. 5%), identified as a γ-ketol, was present. The substrates were the 13- or 9-hydroperoxides of linolenic acid, which were converted to 9-hydroxy-12-oxo-cis-15-trans-11-octadecadienoic acid, respectively. These compounds were formed in addition to the major products reported earlier: a 12,13-α-ketol and 12-oxo-cis-10,15-phytodienoic acid from the 13-isomer, and a 9,10-α-ketol from the 9-isomer.     

A study of tailored blank welding between mild steel sheet and zn-coated steel sheet by CO2 laser beam

Research was conducted on tailored blank welding between mild steel sheet and Zn-coated steel sheet using CO₂ laser beam. The materials used in this study were low carbon steel sheets with a thickness of 1.2 mm and Zn-coated steel sheet with the same thickness and 6.3 μm Zn coating. Experiments were conducted by applying the Taguchi method to obtain optimum conditions for the application of this tailored blank laser welding method in practical manufacturing processes. Optical microscopy, XRD, SEM and TEM analysis were performed to observe the microstructures and to determine the structures of welded zone. In addition, mechanical properties were measured by the microhardness test, tensile test and Erichsen test to evaluate the formability of the welded specimen. There was no trapped Zn in the fusion zone, and the phases of this region consisted of polygonal ferrite, quasi-polygonal ferrite, banitic ferrite and martensite. The elongation value of welded specimen was more than 80% of the value in substrate metal, and the LDH value was more than 90% of the value in substrate metal.     

The A.O.C.S. and the protective coating industry

Journal of the American Oil Chemists' Society -     

The impedance of the Ledanché cell. I. The treatment of experimental data and the behaviour of a typical undischarged cell

The impedance spectrum of an undischarged commercial Leclanché cell (Ever Ready type SP11) is presented in the forms of the Sluyters plot and the modified Randies plot. The decomposition of the experimental cell impedances into the component parts has been achieved using a computer. The decomposition process and the component processes representing the overall cell behaviour are described.List of symbols R _s in-phase component of (experimental) electrode impedance - R _t charge transfer resistance referred to nominal area of Zn ( cm²) - 1/(C _s) out-of-phase component of (experimental) electrode impedance - angular frequency (= 2f) - R resistance of electrolyte solution - charge transfer resistance - C _L double layer capacitance - C _DL double layer capacitance of electrode referred to nominal area of Zn (F cm^–2) - j –1 - Warburg coefficient - D factor in Equations 1 and 2 - C _s R _s calculated values ofC _s andR _s (first approximation) - C _s R _s calculated values ofC _s andR _s (refined values taking into account the additional network) - C _s R _s calculated values of C_s andR _s (refined values taking into account porosity) - _x resistive part of additional series component (parallel connection) - C _x capacitance part of additional series component (parallel connection) - D factor in Equations 6 and 7     

TRANSFER PLASMAS DESTROY PCB FLUIDS

High voltage, ac transfer arcs were used as a reaction zone to destroy polychlorinated biphenyls dissolved in transformer fluid. The extremely high temperature of the arc is of sufficient magnitude that it destroys both the PCB's and the oil in which the PCB's are dissolved.

Although fast pyrolysis is the major destructive mechanism, several other features of the process are unique. For example, the transfer arc discharge is submerged. The arc is created beneath the surface of the transformer oil at a water interface. Furthermore, the water phase is part of the electrical circuit; but it also participates in the reaction chemistry of the plasma arc. Water vapor created by the discharge reacts with the carbon and acetylene formed by pyrolysis to produce hydrogen and carbon monoxide. This retards carbon buildup within the system.

The presence of the water phase also provides a convenient adsorption medium for acid gases (HC1) which are formed by pyrolysis of the PCB's, These gases are infinitely more soluble in the water phase than they are in the transformer oil through which they would have to pass to escape the submerged reaction zone. As a result, this new technology provides a convenient small-scale destruction for oils contaminated with PCB     

Generation of protein lattices by fusing proteins with matching rotational symmetry

The self-assembly of supramolecular structures that are ordered on the nanometre scale is a key objective in nanotechnology. DNA and peptide nanotechnologies have produced various two- and three-dimensional structures, but protein molecules have been underexploited in this area of research. Here we show that the genetic fusion of subunits from protein assemblies that have matching rotational symmetry generates species that can self-assemble into well-ordered, pre-determined one- and two-dimensional arrays that are stabilized by extensive intermolecular interactions. This new class of supramolecular structure provides a way to manufacture biomaterials with diverse structural and functional properties.     

Composition of castor oil by optical activity

Summary The optical activity of castor oil and its derivatives has been studied. Pure methyl ricinoleate and methyl acetyl ricinoleate were prepared. The mixed methyl esters and acetylated methyl esters of castor oil were also prepared. By the determination of specific rotation of the pure and technical esters, the percentage of ricinoleate fraction can be deduced. This was calculated to be 93% and 90%, respectively. The esters of castor oil were calculated to contain 91.6% ricinoleate from the chemical hydroxyl value. This was about the average of the two values obtained optically and is believed close to the actual value. A number of castor oils were analyzed by both optical and chemical methods and found to be of nearly constant ricinoleic content. Dehydrated castor oil was found to have a comparative high specific rotation. This was believed due to its estolide content formed during dehydration.     

Balanced pasture fertilization in the Basque Country: I. Phosphorus and potassium budgets on dairy farms

Dairy farming is the main agricultural activity of the Basque Country. A dairy farm is characterized as a system with soils and crops, forage, cattle and manure as main components, and in such a system, nutrient cycling is very important to maintain soil fertility and optimize forage production. To quantify nutrient transfers in the cycle, a simple system was developed and has been applied to seventeen farms to examine its ability to achieve a balanced P and K fertilization. These farms have provided data on inputs (fertilizer, feeds, concentrates), pasture and manure management, and outputs (milk production), and soil samples have been taken from farm pastures. Phosphorus and K in excreta and uneaten pasture is used with a relatively high efficiency as suggested by the relatively high efficiency of P and K utilization by the pasture that usually ranges from 70 to 90%. Concentrate feeding (3000 kg cow^–1 yr^–1) represents one of the main P and K inputs in Basque Country dairy farms, averaging 26 and 66 kg ha^–1, respectively. Besides, release of K in the soil through slow liberation from non-exchangeable sites was estimated as 30 kg ha^–1. Thus, a high efficiency in excreta recycling would diminish substantially P and K mineral fertilizer needs. Farm nutrient budgets appear to be a convenient tool for determining nutrient shortages and surpluses at farm level, and thus they are considered as a first step to support a better management of maintenance fertilization of permanent pastures.