Multicomponent Charge Research Articles

Charge transport diagnosis by: I– V (resistivity), screening and Debye length, mean free path, Mott effect and Bohr radius in InAs, In 0.53Ga 0.47As and GaAs MBE epitaxial layers

We propose using collected galvano-magnetic data on MBE samples of n-type undoped epi-layers of InAs, In 0.57Ga 0.47As and GaAs on InP semi-insulating and GaAs semi-insulating substrates to characterize their charge transport properties. Hall concentration and resistance measurements vs. temperature were carried out, and these results allowed us to calculate the mean free path and magnetic length. However, they are mono-crystalline, they present multi-component charge transport structures. The characterization of these layers by means of a combined analysis of galvano-magnetic properties, I– V (resistivity), screening and Debye length, mean free path, Mott effect and Bohr radius characteristics gave new and very interesting results. The application of a previously described method of analysis also allows for the presence of a Mott transition to be determined. The presence of a Mott transition leads to the hypothesis that a part of conductance in such layers, especially at low temperatures may be due to an impurity band. We suppose either that during their epitaxial growth all of the investigated layers were unintentionally doped with excess atoms of one component, vacancies of other or that dangling bonds are present. Therefore, in the range of low temperatures, the possible and dominant conduction mechanism is conduction via such defects, with electrons moving by thermally activated hopping.

Comparative analysis of the mineralogical composition and metallurgical properties of sinters obtained from iron-ore-bearing charges of different origins

A study is made to determine how the main genetic groups of iron-ore-bearing components in the sintering charges used at the MMK affect the sintering operation and the quality of the finished product (shallow bed and a complex multi-component charge). Recommendations are presented for improving efficiency in the production of low-basicity (1.6 ± 0.1) sinter in a shallow (260 mm high) bed with certain proportions of different genetic types of components in the iron-ore-bearing part of the charge.

System for Continuously Monitoring Gas Composition over the Radius of the Top of Blast Furnaces

During a class-II overhaul of its 1719-m3 blast furnace, the blast-furnace shop at ISPAT-Karmet installed a system to continuously monitor the composition of the gases and their distribution over the top of the furnace. The information is sent to a computer monitor. A stationary gas-sampling beam was installed to sample the gas at the neutral line. The beam is connected to an EMG-20-1 gas analyzer by heated pulse lines. The data that is obtained makes it possible to correct the operation of the furnace in real time, which is particularly important when a multi-component charge is being used. Use of the system for continuous monitoring of gas composition has improved smelting conditions and increased furnace productivity by 263 tons/day while saving 5.0 kg of coke per ton of pig iron.

Photosensitization of nanocrystalline TiO 2 thin films by a polyimide bearing pendent substituted-Ru(bpy) 3+2groups

Under visible illumination, a thin film of nanocrystalline TiO 2 coated with an adsorbed substituted-Ru(bpy) 3 +2-labeled polyimide 1 produces a sensitized photocurrent when spin-coated on a conductive ITO support. The magnitude of the observed anodic photocurrent defines the efficiency of charge injection from the adsorbed dye to the nanoparticle and of interparticulate electron hopping to the conductive support. Power characteristics and photocatalytic activity of the sensitized film have been investigated. Laser flash photolysis at different applied potentials produces transient absorption spectra that have been analyzed as multicomponent charge injections. Lifetime measurements permit a characterization of the efficiency of electron migration across the semiconductor film. The polymeric dye is also shown to be an effective photosensitizer in inducing the catalytic oxidative decomposition of methylene blue.

Improving Quality Control in Alliances and Partnering

Improving Quality Control in Alliances and Partnering

Primary processes and structure of the Photosystem II reaction center: II. Low-temperature picosecond fluorescence kinetics of a D 1-D 2-cyt- b-559 reaction center complex isolated by short Triton exposure

The fluorescence kinetics of a D 1-D 2-cyt- b-559 reaction center complex isolated by short Triton-exposure has been measured with picosecond resolution as a function of temperature below 150 K. The data were analyzed by combined global analysis of data measured with different time resolutions and are presented as decay-associated fluorescence spectra (DAS). Emphasis is given to the resolution and assignment of the fast components below 100 ps. Six lifetime components were generally necessary for a good fit of the data over a long time-range. The shortest lifetime of 13–24 ps (depending on temperature) is attributed to an energy transfer from (accessory) Chlorophyll to P680, presumably via pheophytin. A component in the range of 40–70 ps is attributed to energy transfer from pheophytin to P680. These components can only be properly resolved and assigned from measurements at temperatures below about 40 K. An ultrashort component of 1–6 ps, which had been resolved in our previous measurements (Biochim. Biophys. Acta (1991) 1060, 237–244) was not resolved in the particles studied here. We propose that the absence of the ultrashort component in this study is attributable to the larger chlorophyll content of the present short-term Triton-exposed D 1-D 2-cyt- b-559 preparation as compared to the previous long-term Triton-exposed RC particles. In the particles studied here the effective charge separation kinetics in the short time-range is rate-limited by relatively slow energy transfer components (lifetimes from 13 to 24 ps) upon preferential excitation of the accessory chlorophylls. In the long time-range a multicomponent charge recombination kinetics giving rise to four fluorescence lifetimes in the range of 1.56–49.7 ns are resolved. All these components show basically identical DAS with maxima near 682 nm.

Energy split and kinetics of ball mill grinding of mixture feeds in heterogeneous environment

Complex interactions between the constituents of a multicomponent mill charge can be conveniently characterized by an energy split factor, which is defined as the ratio of energies consumed per unit mass of a component when it is ground in an admixture and ground alone for equal time intervals. It is shown that the grinding paths of the components are independent of the homogeneous or heterogeneous nature of the particulate environment, and as a consequence the energy split factors can be computed from a mill power-grinding rate correlation. Using these split factors, it is possible to track the flow of energy to the constituents of the feed charge and integrate the energetic and kinetic aspects of multicomponent grinding. Extensive data on dry and wet ball mill grinding of binary feeds comprising calcite-quartz, hematite-quartz and dolomite-hematite mixtures in different proportions have been analyzed using the energy split factors. Interaction effects between hard and soft minerals are quantified, energies expended in grinding individual constituents are estimated, and kinetics of mixture grinding are simulated successfully. Some industrial implications of grinding in heterogeneous environments are discussed.

Relative intensities and temperatue effects on charge transfer transitions of carbazoles with p-chloranil

Multicomponent charge transfer (CT) spectra of carbazoles with p-chloranil are shown to arise via two different conformational arrangements of donor and acceptor units; surprisingly the most intense CT transition arises from the second-highest energy, rather than from the highest-energy filled orbital of the carbazole.

Expected charge states of energetic ions in the magnetosphere

This paper reviews major developments in our understanding of the physics of energetic heavy ions in the Earth's plasma environment during the past four years (1974–1977). Emphasis is placed on processes that influence or are influenced by the ion charge states. This has been a period of growing awareness of the important role heavy ions play in space plasmas. Large fluxes of helium ions and even heavier ions have been observed at the geostationary altitude and in the heart of the radiation belts. Such ions have also been observed on low latitude rockets and satellites, and oxygen ion precipitation exceeding that of protons has been reported. In the outer parts of the Earth's plasma envelope there is mounting evidence for significant fluxes of heavy ions: in the magnetotail, the magnetosheath and in the polar cusp regions. In the inner magnetosphere there is a limited theoretical understanding of equatorially mirroring ions, but generally only radial diffusion at one pitch angle and pitch angle diffusion at one L- shell have been studied; for ions the coupled equations are yet unsolved even for the simplest case of only one charge state (protons). Theoretical modeling of the charge state structures of geophysical heavy ion populations is in part frustrated by the lack of adequate laboratory measurements of the pertinent charge exchange cross sections. A first attempt has, however, been made to treat the charge state transformation processes in the radiation belts for equatorially mirroring atomic oxygen ions. Wave-particle interactions in the magnetosphere become much more complex in multi component and multi charge state plasmas where hybrid resonances and wave-particle interaction induced non-linear species-species coupling could be important. Heavy ion plasma physics in the Earth's magnetosphere and in the magnetospheres of other planets should be a field of fruitful study for both experimentalists and theoreticians in the years ahead.

Research on the process of glass formation from a synthetic multicomponent charge

Research on the process of glass formation from a synthetic multicomponent charge