Dissolution of coal with NaOH-alcohol: Effect of alcohol species

Methanol, ethanol, straight-chain propanol, isopropanol, straight-chain butanol, sec-butanol, tert-butanol, straight-chain pentanol, and iso-pentanol were used for the reaction of coal with NaOH-alcohol at 290 °C for 1 h. All the products dissolved in pyridine with an extraction yield > 80 wt%. Straight-chain alcohols are less reactive than the secondary alcohols owing to the differences in hydrogen donating ability.     

High-speed InGaP/GaAs transistors with a sidewall base contactstructure

We have fabricated InGaP/GaAs double heterojunction bipolar transistors with a sidewall base contact structure. These transistors operate in both emitter-up and emitter-down modes. Symmetric characteristics of the cutoff frequency f_T=68 GHz and the maximum oscillation frequency f_max=31 GHz were obtained at a base-collector bias V_BC of 0 V. For emitter-down operation, f _T was found to reach a maximum of 78 GHz when the base-collector junction was forward biased at 0.9 V. The product of f _T for emitter-down operation and f_T for emitter-up operation was 5.3×10³ GHz², which is about six times that of previously reported SiGe heterojunction bipolar transistors     

Analysis of oil obtained from mild hydrogenation of coal. 1. structural analysis of fractionated oil

Shin Yubari coal (86.7% C) was mildly hydrogenated repeatedly at 340–385°C under an initial hydrogen pressure of 10 MPa for 1 h, using Adkins catalyst. The product was extracted with benzene at 200°C and the residue was again reacted. Finally, benzene solubles were extracted with n-hexane, and n-hexane insolubles were hydrogenated under similar conditions at 380°C; the product was then extracted with n-hexane. The yield of total n-hexane solubles was 52.5%. Acid and base were extracted with sulfuric acid and NaOH, and the neutral part (50.2%) was chromatographed using an alumina column with 2.5% water and separated into 12 fractions. UV and IR spectra, ultimate analysis and ¹H-NMR spectra were obtained for each fraction and a structural analysis was carried out to obtain an image of each average structure. The aromatic ring numbers estimated from UV spectra and from structural analysis for each fractions agree well with each other; the average value was 3.2.     

Finite spectrum assignment problem for systems with delay in state variables

This correspondence is concerned with the finite spectrum assignment problem for linear systems with delay in state variables. A systematic procedure for constructing the feedback law is presented on the basis of advanced elementary row operations on matrices with two variablessandz = e^{-sh}.     

Biomimetic autoseparation of leukocytes from whole blood in a microfluidic device

Leukocytes comprise less than 1% of all blood cells. Enrichment of their number, starting from a sample of whole blood, is the required first step of many clinical and basic research assays. We created a microfluidic device that takes advantage of the intrinsic features of blood flow in the microcirculation, such as plasma skimming and leukocyte margination, to separate leukocytes directly from whole blood. It consists of a simple network of rectangular microchannels designed to enhance lateral migration of leukocytes and their subsequent extraction from the erythrocyte-depleted region near the sidewalls. A single pass through the device produces a 34-fold enrichment of the leukocyte-to-erythrocyte ratio. It operates on microliter samples of whole blood, provides positive, continuous flow selection of leukocytes, and requires neither preliminary labeling of cells nor input of energy (except for a small pressure gradient to support the flow of blood). This effortless, efficient, and inexpensive technology can be used as a lab-on-a-chip component for initial whole blood sample preparation. Its integration into microanalytical devices that require leukocyte enrichment will enable accelerated transition of these devices into the field for point-of-care clinical testing.     

Study of carbonaceous mesophase through the e.s.r. spectra of vanadyl chelates

The behaviour of vanadyl chelate complexes in Iranian heavy oil and ethylene tar pitch during the carbonization process has been investigated by the e.s.r. technique to obtain information on the mesophase transformation. Activation energies for rotation of chelates incorporated with aromatic lamellae, and ordering parameters, are estimated from correlation times and intensities of e.s.r. spectra. The molecular plane of the chelates incorporated into the mesophase was found to be oriented parallel to the applied field. The value of activation energy is higher for a mesophase of small size than for a larger one.     

Modulation of waveheight spectrum and radar cross section byvarying surface currents

This paper investigates the validity of the relaxation model which is generally used to describe the modulation of wind-generated ocean waves by slowly varying surface currents, and the applicability of the model to illustrating features observed in the radar images of internal wave wakes. The amplitude and phase modulations in the waveheight spectrum are examined for sinusoidal current variations; these changes are then translated into the radar cross section (RCS) modulation using the Kirchoff scattering theory. The present study concludes that: 1) the relaxation model is valid under intermediate to strong wind conditions and/or weak current signatures, and the conditions for the validity are given; 2) the relaxation model combined with the Kirchoff model could, under certain conditions, explain the differences in amplitude and phase between the P-band and L (C- and X-) band SAR images of ship-generated internal wave wakes observed during the 1989 Loch Linnhe experiment; and 3) the directional dependence of the relaxation rate enhances these differences     

Influence of alkali on the carbonization process—II: Carbonization of various coals and asphalt with NaOH

Four kinds of coal, one weathered coal and one petroleum asphalt, were carbonized with 120 wt% NaOH. With the addition of NaOH, the amount of hydrogen evolved increases enormously and the temperature of its evolution is lowered by 200–300°C. The reaction is thought to be a dehydrogenation resulting from the addition of NaO- to the active methylene groups or to aromatic nuclei, followed by liberation of NaOH, and causing some condensation reactions. At a higher temperature a large amount of CO evolves. This evolution is due to a reduction of Na₂O or Na₂CO₃ produced in an earlier step of the reaction, with residual carbon.