Direct determination of oxygen in organic materials-I A study of the carbon reduction method

The results of an investigation into the nature of the carbon reduction process in the Unterzaucher method for the microdetermination of oxygen are reported and discussed. The reaction between carbon dioxide and carbon is discussed, and its relation to the specific surface area, which contrary to belief has been found not to contribute to the efficiency of the reaction. It is shown that carbon-oxygen complexes give rise to errors in the results, and that an intermediate, SiO(OH), formed on the inner surface of the silica pyrolysis tube might be a precursor to the formation of carbon monoxide as a source of blank error and of the apparent oxygen content of pure hydrocarbons.     

Candoluminescence-a new flame technique for trace analysis-I Development of a method for determination of bismuth

Early work on candoluminescence is reviewed and the phenomenon is investigated experimentally for the elements Bi, Mn, Sb and the lanthanides. It is demonstrated that it is feasible to determine bismuth (5-1000mug) by measuring its candoluminescent intensity at 399 nm, using a calcium hydroxide-calcium sulphate matrix and a hydrogen-helium-air flame.     

Nitrogen determination in coal and coke with an ammonia electrode

The selective-electrode procedure described for determining 0.2-2.5% of nitrogen in coal and coke offers significant advantages over Kjeldahl distillation and titration. The Kjeldahl digest is diluted, neutralized, cooled, diluted to volume, adjusted to a standard temperature and rendered alkaline prior to measurement with an ammonia-selective electrode. Accuracy and precision of 1% relative are demonstrated by comparative analyses of a range of samples. Important experimental aspects discussed include the role as neutralization indicator played by vanadium derived from the catalyst, precision of the mV-meter, the influence of solution temperature and concentration, the repeatability of the readings, and interferences.     

Nuclear disintegration in relativistic heavy ion collisions

The breakdown of the participant spectator model for central relativistic nuclear collisions is discussed and a different picture of a hot spot followed by a target explosion is suggested to be more consistent with the data.     

On the range of influences in back-circulant Latin squares

In this note we obtain a large lower bound for the index of a certain critical set in the back-circulant Latin squares of odd order. This resolves in the negative a conjecture of Fitina, Seberry and Chaudhry [Back-circulant Latin square and the influence of a set, Austral. J. Combin. 20 (1999) 163-180].     

Automorphisms of higher‐dimensional Hadamard matrices

This article derives from first principles a definition of equivalence for higher‐dimensional Hadamard matrices and thereby a definition of the automorphism group for higher‐dimensional Hadamard matrices. Our procedure is quite general and could be applied to other kinds of designs for which there are no established definitions for equivalence or automorphism. Given a two‐dimensional Hadamard matrix H of order ν, there is a Product Construction which gives an order ν proper n‐dimensional Hadamard matrix P⁽ⁿ⁾(H). We apply our ideas to the matrices P⁽ⁿ⁾(H). We prove that there is a constant c > 1 such that any Hadamard matrix H of order ν > 2 gives rise via the Product Construction to cν inequivalent proper three‐dimensional Hadamard matrices of order ν. This corrects an erroneous assertion made in the literature that ”P⁽ⁿ⁾(H) is equivalent to “P⁽ⁿ⁾(H′) whenever H is equivalent to H′.” We also show how the automorphism group of P⁽ⁿ⁾(H) depends on the structure of the automorphism group of H. As an application of the above ideas, we determine the automorphism group of P⁽ⁿ⁾(Hk) when Hk is a Sylvester Hadamard matrix of order 2^k. For ν = 4, we exhibit three distinct families of inequivalent Product Construction matrices P⁽ⁿ⁾(H) where H is equivalent to H₂. These matrices each have large but non‐isomorphic automorphism groups. © 2008 Wiley Periodicals, Inc. J Combin Designs 16: 507–544, 2008     

Liquid scintillation counters calibration stability over long timescales

Liquid scintillation spectrometry is widely used for the analysis of alpha and beta emitting radionuclides. Robust calibration of liquid scintillation (LS) spectrometers is fundamental to accurate LS measurement but at the same time is time consuming and costly, particularly if a wide range of radionuclides are analysed by the laboratory. The frequency of the calibration varies in different laboratories and is based on many practical and operational factors. This work summarizes the observations regarding variations in 1220 Quantulus spectrometers efficiency calibrations performed annually using various radionuclides: ³H ⁶³Ni, ⁵⁵Fe, ³⁶Cl, ⁴⁵Ca, ¹⁴⁷Pm, ²⁴¹Pu, ⁹⁹Tc for a period of 9 years and discusses the implication to calibration frequency.

     

Graphene Oxide Nanosheets Modified with Single‐Domain Antibodies for Rapid and Efficient Capture of Cells

Peripheral blood can provide valuable information on an individual’s immune status. Cell‐based assays typically target leukocytes and their products. Characterization of leukocytes from whole blood requires their separation from the far more numerous red blood cells. 1 Current methods to classify leukocytes, such as recovery on antibody‐coated beads or fluorescence‐activated cell sorting require long sample preparation times and relatively large sample volumes. 2 A simple method that enables the characterization of cells from a small peripheral whole blood sample could overcome limitations of current analytical techniques. We describe the development of a simple graphene oxide surface coated with single‐domain antibody fragments. This format allows quick and efficient capture of distinct WBC subpopulations from small samples (～30 μL) of whole blood in a geometry that does not require any specialized equipment such as cell sorters or microfluidic devices.