Large set of P3‐decompositions

Let G=(V(G),E(G)) be a graph. A (n,G, λ)‐GD is a partition of the edges of λK_n into subgraphs (G‐blocks), each of which is isomorphic to G. The (n,G,λ)‐GD is named as graph design for G or G‐decomposition. The large set of (n,G,λ)‐GD is denoted by (n,G,λ)‐LGD. In this work, we obtain the existence spectrum of (n,P₃,λ)‐LGD. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 151–159, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10008     

A completion of the spectrum for large sets of disjoint transitive triple systems

In this paper, we give a recursive construction from an LTTS(v + 2) to an LTTS(16v + 2) for v 3. Furthermore, the existence of LTTS(2ⁿ + 2) is proved. Thereby, we completely solve the existence problem of LTTS)(v) (large set of pairwise disjoint transitive triple systems of order v).     

Study on structural variation of silica gel using Nd3+ as a probe by photoacoustic spectroscopy

The structural variations of silica gels heated at different temperatures have been firstly studied using Nd(3+) as a probe by photoacoustic spectroscopy (PAS), together with IR spectroscopy and thermal analysis. With increasing temperature, the f-f transitions of Nd(3+) show a red shift and the PA intensities increase. The PA branching vector of the transitions from ground state to 4G(5/2)+(2)G(7/2), which are hypersensitive transitions, increase and the others decrease or change little. These indicate that the covalency of the bond that Nd(3+) forms increases and the symmetry around Nd(3+) decreases, which reflects the structural variations of silica gels.     

Determination of Organophosphorus Pesticides in Soil by MMSPD-GC-NPD and Confirmation by GC-MS

A novel method, modified matrix solid-phase dispersion (MMSPD), has been developed for quantitative analysis of organophosphorus pesticide residues in soil. It was based on matrix solid-phase dispersion (MSPD) and continuous liquid-solid extraction (continuous LSE), using Florisil as sorbent and dichloromethane as the recycling solvent. Two soils with different texture and physicochemical properties were studied to validate the method. The effect of residence time of pesticides in soil was also studied. MMSPD was compared with MSPD and continuous LSE respectively. Determination was carried out by gas chromatography with nitrogen-phosphorus detection (GC-NPD). The method gave recoveries ranging from 72–105% with relative standard deviations (RSDs) lower than 15% for the pesticides studied. The limits of detection (LODs) ranged from 0.1 to 0.6 ng g⁻¹. Two pesticide residues have been detected in real soil samples from Fujian, China, using MMSPD. The pesticides were confirmed by gas chromatography-mass spectrometry (GC-MS) in a selected-ion monitoring (SIM) mode. Revised: 4 and 9 April 2006     

Catalytic Oxidation of Dimethyl Ether to Dimethoxymethane over Cs Modified HaPW12O40/SiO2 Catalysts

The attractive utilization route for one-step catalytic oxidation of dimethyl ether to dimethoxymethane was successfully carried out over the H3PW12O40（40%）/SiO2 catalyst, modified by Cs, K, Ni, and V. The Cs modification of H3PW12O40（40%）/SiO2 gave the most promising result of 20% dimethyl ether conversion and 34.8% dimethoxymethane selectivity. Dimethoxymethane could be synthe- sized via methoxy groups decomposed from dimethyl ether through the synergistic effect between the acid sites and the redox sites of Cs modified H3PW12O40（40%）/SiO2.     

Dynamic ultrasound-assisted extraction of polyphenols in tobacco

A novel extraction method, namely dynamic ultrasound-assisted extraction, is investigated. This technique is efficient with respect to both time and solvent consumption because it utilizes ultrasonic energy in dynamic mode during extraction. Polyphenols (chlorogenic acid, esculetin, rutin, scopoletin, and quercitrin) are extracted from a tobacco (Nicotina tobaccum L.) sample for 10 min with 6 mL of solvent. Fresh solvent is continuously pumped through the sample, with which the analytes can be rapidly extracted, and the possibility of degradation efficiently avoided. Methanol involving 0.5% w/v ascorbic acid was used as extraction solvent; optimal flow rate and extraction time were investigated. The extract was cleaned up by C18 disposable cartridge. The spiked and nonspiked tobacco samples were used for the evaluation of the proposed method. Recoveries obtained were varied from 96 to 108% and RSDs from 2.0 to 4.6%. This extraction technique was revealed to recover larger amounts of polyphenols from tobacco, compared to the static ultrasound-assisted extraction method.     

Removal of major interference sources in aqueous near-infrared spectroscopy techniques

This work describes a hybrid procedure for eliminating major interference sources in aqueous near-infrared (NIR) spectra, that include aqueous influence, noise, and systemic variations irrelevant to concentration. The scheme consists of two parts: extension of wavelet prism (WPe) and orthogonal signal correction (OSC). First, WPe is employed to remove variations due to aqueous absorbance and noise; then OSC is applied to remove systemic spectral variations irrelevant to concentration. Although water possesses strong absorption bands that overshadow and overlap the absorption bands of analytes, along with noise and systematic interference, successful calibration models can be generated by employing the method proposed here. We show that the elimination of major interference sources from the aqueous NIR spectra results in a substantial improvement in the precision of prediction, and reduces the required number of PLS components in the model. In addition, the strategy proposed here can be applied to various analytical data for quantitative purposes as well.     

γ辐照引发无皂乳液聚合法一步合成Ag-聚4-乙烯基吡啶杂化微凝胶

无机-聚合物纳米复合材料是将聚合物与一种或多种无机纳米粒子复合而成的一种材料,它同时具有无机纳米粒子和聚合物的优良特性,在许多重要技术领域具有广泛的应用前景.近20年来,无机-聚合物纳米复合材料的制备及应用备受关注[1~6].包括杂化微凝胶在内的纳米复合微球是无机-聚合     

A Study on Photoacoustic Phase Spectra of Rare Earth Complexes with Oxine

Photoacoustic phase is the time delay that occurs from light to acoustic signal. the phase includes two components: one is the time delay that occurs during the process in which light absorbed by a sample converts into heat; the other is the time delay caused from heat to acoustic signal. a modified formula of PA phase is presented based on the R-G theory considering the phase caused by non-radiative relaxation processes. the phase is associated with absorption coefficient (β), thermal diffusion length of sample (μ_s), the longest lifetime of all excited states (r), and the ratio of rapid to slow heat component (R). When the photoacoustic signal is saturated the phase is associated with only T and R. the effect of different rare earth ions on the PA phase spectra of the ligand (oxine) in the rare earth complexes are reported and are well explained by using the phase formula of PA saturation.