Surface area of papermaking woodpulps used by the British paper industry

The surface area was determined for various papermaking woodpulps: bleached eucalyptus globulus sulphate pulp; bleached eucalyptus grandis sulphate pulp; bleached betula verrucosa sulphate pulp; bleached pine/spruce sulphate pulp; bleached pine/spruce sulphate pulp fines. The method of negative adsorption was used which gives an effective wet surface area. By looking at negative adsorption data more closely, some inference can be made about the morphology of the substrate.Glossary of symbols B (e²/2kT)^1/2 - ¯C concentration of fibre per unit volume of pulp - 1 - ¯¯c - h angle between pore and the axis of the bed in a permeable material - K permeability coefficient - k Boltzmann constant - k ₀ shape factor for pores in a permeable material - n _i concentration of co-ion in the bulk solution - n _i experimentally observed increase in concentration of co-ion in the bulk solution - S surface area - S _t wS - S ₀ surface area per unit volume of permeable material - V _t total volume of solution - V excluded volume - V _s excluded volume accessible to water but not to ions - V _obs experimentally observed excluded volume - w weight of dry fibre - ¯ effective volume of fibres in a permeable pad - surface potential at outer Helmholtz plane     

Bestimmung von Kupfer

Ohne Zusammenfassung     

Effect of Pr-Ca substitution on the transport and magnetic behavior of LaMnO3 perovskite

The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO₃ perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good example of these properties is (La_1−2x Pr _x Ca _x )MnO₃ (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T _c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for understanding the structural, transport and magnetic properties are discussed in detail.     

Spectrophotometric determination of the rare earths yttrium and cerium by bromopyrogallol red

A method is described for the spectrophotometric determination of microgram quantities of rare carths, yttrium and cerous cerium ions, using the colour of the complexes formed with bromopyrogallol red. The procedure has been applied to pure solutions containing 10–50 μg of the element.     

An optical study of the stretching absorption band near 3 microns from OH- defects in LiNbO3

A near infrared absorption band (λ = 2.87 μ), identified as the 0–1 stretching vibrational band of OH^- defects in LiNbO₃, has been observed at 6, 77, and 300 K. This band was completely polarized perpendicular to the crystallographic c-axis within experimental error and two peaks, separated by approximately 13 cm^?1, were resolved. Both the structure and optical anisotropy of this band were independent of stoichiometry and sample treatments and may be understood in terms of a simple model where protons are captured by O^2- anions forming OH^- defects whose orientations are determined by neighboring O^2- ions.     

Benign reduction of carbon nanotube agglomerates using a supercritical carbon dioxide process

A method was developed to deagglomerate commercially available multi-walled carbon nanotube (MWCNT) bundles while maintaining the carbon nanotube aspect ratio. The process utilizes the rapid expansion of a supercritical carbon dioxide/MWCNT mixture to separate large primary carbon nanotube agglomerates. High levels of deagglomeration of Baytubes^® C 150 P and Nanocyl? NC-7000 MWCNT bundles were observed on the macroscale and nanoscale, resulting in 30-fold and 50-fold decreases in bulk density, respectively, with median agglomerate sizes <8 μm in diameter. These results were obtained while retaining the aspect ratio of the as-received nanomaterial, irrespective of the MWCNT agglomerate morphology. It was found that a temperature and pressure of 40 °C and 7.86 MP resulted in maximum deagglomeration without damage to the MWCNTs. Thermodynamic principles were applied to describe the effect of processing variables on the efficiency of the deagglomeration. These results suggest that combining this process with a composite processing step, such as melt compounding, will result in nanocomposites with enhanced electrical properties.     

SCOTfluors: Small,Conjugatable, Orthogonal,and Tunable Fluorophores for In Vivo Imaging of Cell Metabolism

The transport and trafficking of metabolites are critical for the correct functioning of live cells. However, in situ metabolic imaging studies are hampered by the lack of fluorescent chemical structures that allow direct monitoring of small metabolites under physiological conditions with high spatial and temporal resolution. Herein, we describe SCOTfluors as novel small‐sized multi‐colored fluorophores for real‐time tracking of essential metabolites in live cells and in vivo and for the acquisition of metabolic profiles from human cancer cells of variable origin.     

Comparison of sulfide-selective electrode and gas-stripping monitors for hydrogen sulfide in effluents

A commercial prototype monitor, in which a sulfide-selective electrode detects hydrogen sulfide with a pH electrode used as the reference electrode in a sample acidified to pH <5, is compared to a monitor in which a solid-state sensor detects hydrogen sulfide stripped from the sample by an air—CO₂ mixture. Each monitor has a detection limit of ?0.005 mg kg^-1 and both monitors performed well over a six-month period in the field, sampling a heavy water plant effluent. Both monitors are simple to operate, calibrate, and maintain, but their accuracies are affected by oil and particulates in the sample. Advantages of using the suifide/glass electrode detection system in acidic solutions are presented.     

关于K个复相关矩阵相等的检验

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