Bounds on Codes Derived by Counting Components in Varshamov Graphs

We are interested in improving the Varshamov bound for finite values of length n and minimum distance d. We employ a counting lemma to this end which we find particularly useful in relation to Varshamov graphs. Since a Varshamov graph consists of components corresponding to low weight vectors in the cosets of a code it is a useful tool when trying to improve the estimates involved in the Varshamov bound. We consider how the graph can be iteratively constructed and using our observations are able to achieve a reduction in the over-counting which occurs. This tightens the lower bound for any choice of parameters n, k, d or q and is not dependent on information such as the weight distribution of a code. This work is taken from the author’s thesis [10]     

Structural, morphological, wettability and thermal resistance properties of hydro-oleophobic thin films prepared by a wet chemical process

The structural properties of fluorine containing polymer compounds make them highly attractive materials for hydro-oleophobic applications. However, most of these exhibit low surface energy and poor adhesion on the substrates. In the present investigation, crack free, smooth and uniform thin films of poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole]-co-tetrafluoroethylene (TFD-co-TFE) with good adhesion have been deposited by wet chemical spin-coating technique on polished AISI 440C steel substrates. The as-deposited films (xerogel films) have been subjected to annealing for 1 h at different temperatures ranging from 100 to 500 °C in an argon atmosphere. The size growth of the nano-hemispheres increased from 8 nm for xerogel film to 28 nm for film annealed at 400 °C. It was found that as the annealing temperature increased from 100 to 400 °C, nano-hemisphere-like structures were formed, which in turn have shown increase in the water contact angle from 122° to 147° and oil (peanut) contact angle from 85° to 96°. No change in the water contact angle (122°) has been observed when the films deposited at room temperature were heated in air from 30 to 80 °C as well as exposed to steam for 8 days for 8 h/day indicating thermal stability of the film.     

XPS investigations of ink‐jet printed paper

Different ink‐jet printed paper materials were investigated using X‐ray photoelectron spectroscopy (XPS) yielding the elemental composition of the near‐surface region of the papers. We found significant differences with respect to the detected elements and their atomic concentrations in the different inks studied here. Two different groups of inks could be identified by means of a lower ratio of the O and C atomic concentrations and lower concentrations in specific trace elements like Mg, Na and Si. High‐resolution spectra of C 1s and O 1s core levels allowed a detailed determination of the chemical state of the respective elements. On the basis of a detailed deconvolution of these XPS signals, significant differences between all the investigated ink‐jet printed papers were found, thereby allowing their discrimination. The applicability of the measurements and, more generally, the XPS technique for forensic investigations of paper are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

X射线荧光光谱滤纸片法测定矿石中的铜

我们用Ｘ射线荧光光谱滤纸片法分析了古今１３铜矿石样品中的铜含量，测量结果与化学法一致。此法不需要铜矿石的标样，而且手续简单，方便，检出限低，灵敏度高，测量结果正确可靠，是分析矿石中单一或几个元素的含量较好的方法之一。     

Identification of a chemical indicator of the rupture of 1,4-β-glycosidic bonds of cellulose in an oil-impregnated insulating paper system

In this study, headspace gas chromatography/mass spectrometry has been used to assess the volatile by-products generated by the ageing of oil-impregnated paper insulation of power transformers. Sealed-glass ampoules were used to age under oxidative conditions 0.5-g specimens of insulating paper in 9 mL of inhibited mineral oil in a temperature range of 60–120 °C and moisture of 0.5, 1 and 2% (w/w). A linear relationship between one of the oil-soluble degradation by-products, i.e. methanol, and the number of ruptured 1,4-β-glycosidic bonds of cellulose, regardless of the type of paper (ordinary Kraft or thermally-upgraded (TU) Kraft paper), was established for the first time in this field. Ageing at 130 °C of model compounds of the Kraft paper constituents (α-cellulose, hemicellulose and lignin) and two cellulosic breakdown by-products (D-(+)-glucose and 1,6-anhydro-β-d-glucopyranose) confirmed that the α-cellulose degradation was mostly responsible for the presence of this molecule in the system. Furthermore, additional 130 °C-tests with six different papers and pressboard samples under a tight control of initial moisture indicated that at least one molecule of methanol is formed for each rupture of 1,4-β-glucosidic bond of the molecular chains. Stability tests showed that the ageing indicator is stable under the oxygen and temperature conditions of open-breathing transformers. The presence of methanol was detected in 94% of oil samples collected from over than 900 in-service pieces of equipment, confirming the potential for this application. Lastly, the tests have shown that oil-oxidation by-products and TU-nitrogenous agents modify the methanol partitioning coefficients in the paper/oil/air system, which makes their study essential over a range of field conditions encountered by power transformers. Results are presented and discussed in comparison with 2-furfuraldehyde, which is the current reference in the domain.     

Interaction of aryldiazonium salts with some schiff-base complexes of cobalt and ruthenium

The interaction of aryldiazonium ions with some Schiff-base complexes of cobalt and ruthenium have been studied. With cobalt, one-electron oxidation of [Co(II)Salen] occurred; with [Co(I)Salen] the corresponding Co(III)-aryl complexes were isolated. In the case of ruthenium oxidation also occurs, [Ru(Salen)(CO)py] gave the corresponding monocation. The results, especially for ruthenium, are in contrast to the stabilisation of both nitrosyl and aryldiazonium adducts in analogous porphyrin complexes.     

微生物法分析天然抗氧化剂性能

建立了微生物抑菌活性纸片试验法，对葛根黄酮、诃子提取物、丹皮酚、竹叶黄酮等4种天然抗氧化剂的抗氧化性能进行了研究。竹叶黄酮、诃子、葛根具有较强的抗单线态氧能力，而丹皮酚抗单线态氧的能力较差。在不同的氧化还原微环境下，天然抗氧化剂可能表现出抗氧化能力，亦可能表现出促氧化能力，二者有着不同的反应机理。微生物抑菌活性纸片法可作为研究较复杂生物环境中抗氧化剂性能的一种简便方法。     

Redox behavior of V/MgO catalyst in H2S wet oxidation at room temperature

The room temperature wet catalytic oxidation was conducted in a batch reactor with V/MgO catalyst. The XRD study of the catalyst used indicated that V/MgO could not only oxidize H2S to sulfur selectively, but also prevent the sulfidation of metal oxide effectively at the room temperature. The XPS study indicated that the H2S oxidation with V/MgO could proceed by a redox mechanism (V⁵⁺↔ V⁴⁺) and that V³⁺ formation (V⁴⁺→ V³⁺), was responsible for the deactivation of V/MgO. This revised version was published online in June 2006 with corrections to the Cover Date.     

STUDY ON STYRENE-BUTADIENE BLOCK COPOLYMER FOR THE MODIFICATI0N OF TIRE TREAD

This paper mainly deals with the design and synthesis of a novel styrene-butadieneblock copolymer. When this copolymer is used in the tread portion of tyres, it can improvewet skid resistance and reduce rolling resistance without sacrificing its general physical-mechanical properties. The visco-elastic curve of tire tread using the novel copolymer asits rubber portion was showed. Reactivity ratios for two monomers in the polymerizingsystem were calculated. The diagrams of differelitial, integral and finite difference calculithroughout the whole molecular chain were presented. The influence of the micro- andmacro-structure of the copolymer chain on wet skid resistance and rolling resistance wasdiscussed     

Cellulase Activity in Different Buffering Media During Waste Paper Hydrolysis by HPLC

The activity of cellulase has traditionally been described by pH and temperature; however, the buffering medium is also an important factor, Taking plain water as a reference medium, three kinds of buffer including KH₂PO₄/K₅HPO₄, citric acid/sodium citrate, and acetic acid/sodium acetate were adopted to survey their effects on the activity of cellulase. Chromatographic assays indicated that xylose, glucose, and cellobiose were the major products and that minor products such as cellotriose and cellotetraose were present in some cases. The activities of cellulase based on glucose production showed that the phosphate buffer acted as a deactivator for cellulase and each of the two organic acid buffers acted as activators for cellulase. The concentration of activation buffer should be high to reach a high cellulase activity; however, this effect would be compensated for by the product inhibition of cellulase. The highest activity obtained was 4.16 ± 0.08 (× 10^?3) IU mg^?1 for the citric acid/sodium citrate buffer under pH 4.80, 40 °C and an agitation speed of 150 rpm.