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Dimethoate, one of the organophosphorus pesticides, was selectively determined by ion mobility spectrometry (IMS) along with the single and mixed alternate reagent ions. By doping ammonium, acetone, ethanol, ether, and methanol into the carrier gas, the best selective detection was obtained by the addition of ammonium having the highest proton affinity among these single alternate reagent ions. Three mixed alternate reagents including ammonium−acetone, ammonium−ether, and acetone−ether, which were also used to improve the selectivity, showed better results than that single-solvent dopants gained. The best resolution and the highest abundance of the dimethoate peak were observed in its IMS spectrum after the addition of the mixed ammonium−acetone among all the above-mentioned dopants. The relationship curves for the concentration of ammonium and mixed ammonium−acetone to the response of dimethoate were studied. Ammonium at ∼1.0 μg/L levels or 1.0 μg/L ammonium at plus acetone at ∼1.0 μg/L levels exhibited ...

Periodically chirped sampled fiber Bragg gratings (PC-SFBGs) are proposed as multichannel comb filters. A PC-SFBG consists of many chirp periods corresponding to the periodic chirp effect. With the same chirp coefficient released for a linearly chirped SFBG (LC-SFBG), the spectral self-imaging phenomenon is also observed in the PC-SFBG. Compared with a uniform SFBG, the PC-SFBG exhibits a narrower channel spacing and a similar group-delay characteristic in the reflection bands. Meanwhile, the PC-SFBG ensures a more accurate phase-shift condition (or a better tolerance on the chirp coefficient) and higher peak reflectivities than the LC-SFBG

Mixed surfactant solutions are studied to understand their synergistic effects. Here we report the micellization properties of mixed surfactant solutions of the gemini surfactant N,N'-bis(dimethyldodecyl)-1,2-ethanediammoniumdibromide (12-2-12) with the imidazolium ionic liquid 1-dodecyl-3-methylimidazolium bromide (C12mimBr) investigated by isothermal titration calorimetry (ITC), conductometry, fluorimetry, and dynamic light scattering (DLS). A two-parameter Margules model was successfully used to correlate the cmc values and calculate the compositions and activity coefficients of the two components in the mixed micelle phase for 12-2-12/C12mimBr aqueous solutions with different overall surfactant compositions. The dissociation degree of counterion, the thermodynamic quantities of micellization, and the excess thermodynamic quantities for the mixed micelle were calculated and discussed. The ITC experiment in the low overall surfactant composition region showed a second phase transition. A thermodynamic model was proposed to explore phase behaviors of two different types of micelle and their solution, which was further confirmed by fluorescence and DLS studies.

The positive ion mobility spectra of selected amines, N,N-diethyl-p-toluidine, N,N-dimethyl-1-naphthylamine, N-napthyl-ethylenediamine, ethanolamine, n-heptylamine, and 2-isopropylaniline were measured with a portable IMS device with lutidine (2,4-dimethyl-pyridine) as the reference compound. The reduced mobilities of the above-mentioned amines were found to be 1.62, 1.60, 2.26, 2.29, 1.51, 1.69 cm(2) V-1 s(-1), respectively, and did not vary with different background gases. These amines were compared with several other amines in the literature, and the results of different mobility values of similar amines were explained. The minimum detection limits of N,N-diethyl-p-toluidine, N,N-dimethyl-1-naphthylamine, and N-naphthyl-ethylenediamine were measured to be 0.05, 0.1, and 30 ppb, respectively. The response curve for N,N-diethyl-p-toluidine was nearly linear in the range from 50 to 110 ppb. The response curve for N,N-dimethyl-1-naphthylamine was nearly linear in the range from 30 to 100 ppb. In this article the IMS spectra of background gases, lutidine, and mixtures of amines with three extraction solvents are measured and analyzed. Selective detection of amines achieved by doping NH3, ethanol, acetone, and ether into a dilute concentration of amines in air is also discussed. Finally, the results of field tests in a chemical plant are presented. (C) 1997 John Wiley & Sons, Inc.

Single-crystal Se and Te tubular structures have been synthesized in one step by a hydrothermal method and characterized by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). The hollow prismatic morphology of the tubular structures has been revealed and explained based on the nucleation and growth mechanism of the highly anisotropic crystal structures of Se and Te.

To evaluate the efficacy of an ultrasound-based quantitative method to diagnose liver fibrosis using a rat model. Ultrasonography was performed on the livers of 90 Sprague-Dawley rats with or without thioacetamide-induced fibrosis. The liver capsule thickness and 13 texture parameters of gray level co-occurrence matrix were extracted from the standard sonograms. After sacrifice, severity of liver fibrosis (S0-S4 classification) was diagnosed by histopathology. Analysis of variance and correlation statistical tests were used to analyze the differences between groups and determine the relationships between each of the 14 quantitative ultrasound index points and the histological results, respectively. Discriminant analysis models were developed for quantitative diagnosis of liver fibrosis, and the leave-one-case-out method was used to verify the efficiency of models. All 14 indices were significantly correlated with the histological stages of fibrosis (P less than 0.05). The accuracy of the discriminant model for S0, S1, S2, S3 and S4 was 83.3%, 84.2%, 70.0%, 50.0% and 88.2%, respectively. In addition, 73.3% of cross-validated rats were accurately classified. Grouping S0 as no fibrosis, S1 as mild fibrosis, S2 with S3 as moderate to severe fibrosis and S4 as early cirrhosis increased the accuracy of the discriminant model for these four groups (respectively, 91.7%, 84.2%, 69.0% and 88.2%) and allowed for 78.9% of cross-validated rats to be correctly identified. Ultrasonography combined with texture analysis was a novel and accurate method to diagnose liver fibrosis in a rat model; further studies may provide insights into its applicability for quantitating liver fibrosis in other animal models or in clinic.

Well-aligned and uniform titanium dioxide nanotube arrays were fabricated in situ on titanium substrate by electrochemical anodic oxidation. SEM images indicate that the TiO2 nanotubes are well organized into high-density uniform arrays,with diameter ranging in size from 70 to 100 nm. The XRD patterns show that the sample fabricated by anodic oxidation is amorphous without being annealed. As the 500 degrees C annealed sample crystallized in the anatase phase, which is in good photocatalytic activity. In quartz glass reactor, the photoelectrocatalytic degradation of MB in aqueous solutions as well as the effect factors and then to 0.1 mol/L NaCl as the electrolyte, under with in oxygen atmospheres annealed the applied bias is 0.5 V and has a pH = 3.25, light intensity is 1 000 microW/cm2 and the surface area of nano-tube array film conditions, will help to improve the TiO2 nanotubes array film photoelectrocatalysis degradation of MB degradation efficiency is 99.56%. The results of EIS analyses revealed that the surface reaction step was the only rate limiting step either for the photoelectrocatalytic process. The extra bias potential could decrease the values of the electron-transfer resistance and increase the separation efficiency of photogenerated electron-hole pairs.

To evaluate the dynamic ocular biometric changes of a modified form-deprivation myopia model in young guinea pigs.THE ANIMALS WERE RANDOMLY ASSIGNED TO TWO GROUPS: the monocularly deprived facemask group (MDF, with all the right eyes covered, n=24) and the normal control group (free of facemask, n=24). Each group was then equally divided into four subgroups which were followed up for 2, 4, 6 and 8 weeks, respectively. Parameters measured from every eye included refraction, corneal curvature, axial length and the dry weight of sclera at the posterior pole.All the facemasks remained in place during the follow-up. The covered eyes developed myopia with the vitreous chamber lengthening and the dry weight of posterior sclera reduced at each time point compared with the contralateral uncovered (P0.05 at all time points). The changes had a linear correlation with the deprivation time (P0.05). There were no significant differences in all the parameters between the uncovered eyes of MDF group and the normal control group (P0.05 at all time points).Monocular form deprivation with the facemask is highly effective and non-invasive in inducing axial myopia in guinea pigs. The axial myopia is mainly caused by the increased vitreous chamber length and the weakened posterior sclera rigidity. The form-deprivation eye didn't interfere with the natural development of the contralateral eye.

In efficiency analysis of weapon system, in order to capture and represent the decision maker's preferences and then to select the most desirable alternative, sensitivity analysis method of operational effectiveness based on LS-SVM is proposed. Firstly, the principle of effectiveness evaluation method based on LS-SVM is discussed. Secondly, to extract learning samples from the MADM problem, an approach to estimate the utility functions for attributes is presented. An optimal selection approach of LS-SVM parameters was put forward based on particle swarm optimization (PSO) algorithm. Finally, the implementation algorithm of sensitivity analysis method of operational effectiveness based on LS-SVM is presented. The proposed method has less number of parameter and is simple and reliable, comparing with SVM. In the end, an example demonstrates the method is feasible and availability.

Experiments were carried out to scrub cooking fumes using by clean water and by bio-slurry, and the effects on the removal rate of cooking oil and particles were studied. The results showed that the scrubbing effect of cooking fumes was the best when the bio-slurry concentration was 1.2 g/L. The particle sizes of fumes reduced from 0.2 ~ 62µm to 0.2 ~ 5µm, and compared with clean water washed, the efficiency of the purification of fumes significantly improves from 65% to about 87%. Bio-slurry can reduce the concentration of cooking fume in the liquid phase by sedimentation and microbial degradation, make it decrease from 20 mg / L to 3 mg / L.

This paper initiated the general hypotheses and propositions about the research on entrepreneurs. The authors reviewed the past three economic perspectives based on the entrepreneurial competency. Three core structures were put forward and four requisite ones as well. Cultivation, selection, competition and motivation were suggested as the strategies finally.

The nano-photochemical reaction of polyethyelene glycol (PEG)-Au3+ was studied by resonance scattering and absorption spectrophotometry, and transmission electron microscopy. Influence of various factors on the preparation of gold nanoparticles was considered. There is a correlation between the molecular mass of PEG and the size of gold nanoparticles. A new photochemical method was proposed for the preparation of gold nanoparticles in size of 6-60 nm, using different molecular mass of PEG. The cause of obtaining gold nanoparticle with different size is the different space effect and hydrophobic property of PEG. A reasonable nano-reaction mechanism was developed.

To investigate the surgical indications and techniques of laparoscopic operation for benign ovarian cysts.Fifty patients with benign ovarian cysts underwent laparoscopic operations of cyst decollement, ovariotomy and adnexectomy.There were 46 cases (92%) of decollement, 2 cases (4%) of adnexectomy and 3 cases (6%) of ovariotomy. The operation time was 30-120 min, and the intraoperative blood loss 20 ml.Laparoscopic operation of benign ovarian cysts has advantages of minimal invasive surgery.

FTIR was employed in the structure analysis of the saponites with an ideal chermical formula [Si6.5Al1.5]IV [Mg6]VI O20(OH)4 the starting gel synthesized by microwave-hydrothermally under different pressures (1 x 10(5), 5 x 10(5), 1.5 x 10(6), 2.5 x 10(6) and .5 x 10(6) Pa). It was found that low frequency absorption region in infrared spectrum was sensitive to the crystallization of the product and the amorphous materials produced in synthesis of saponite under the radiation of microwave. The absorptions belong to amorphous materials were decreased with increasing pressure. Saponite synthesized at 3.5 x 10(6) Pa showed no amorphous absorptions (1240, 90-602 cm(-1)), indicating the purity and quality of the synthetic mineral. It was worthy to note that Si(AI)-O stretching vibration infrared absorption could be regarded as an index in assessing the quality of synthetic 2:1 trioctahedral smectite sample with the same chemical compositions. With the increasing pressure, this strong vibration shifted to low frequency (1022, 1020, 1016, 1016, 1005 cm(-1)) in the medium frequency of the whole infrared spectrum. Since the sensitivity, easiness and simplicity, this infrared index would be meaningful in practical saponite-related minerals analysis. In addition, powder X-ray diffraction and scanning electronic microscopy were employed in charactering the saponite synthesized by microwave-hydrothermal method in this work.

This paper sets up an electronic nose, and presents a kind of combinative and modular single-hidden-layer perceptrons. Every module is made up of multiple single-input single-output multilayer perceptrons (MLPs). One MLP is regarded as an expert, and one module consists of several such experts. In electronic noses, one module is behalf of a kind of odor, and determines its similar degrees, namely its strengths. The most similar module gives the class and strength of the odor. By means of enlarging the input components to the range of [0, 6.0] and transforming the standard sigmoid activation function to be f(x)=3(1+exp(-x/3))/sup -1/, the learning speeds of MLPs are sped up. The experiment for simultaneously estimating the classes and concentrations of 4 kinds of fragrant materials, namely ethanol, ethyl acetate, ethyl caproate and ethyl lactate in different concentrations, shows that the proposed method is quite effective.

This article reports the spectral analysis of Maorenshen (Actinidia valvata) and its confusable materials Actinidia chinennsis and Actinidia polygama by fluorescence test, ultraviolet spectrophotometry and fluorescence spectrophotometry. Strong green or blue fluorescence was observed at UV 254 nm in aqueous solutions of Actinidia chinesis and Actinidia polygama, and was barely seen in that of Maorenshen. There were also obvious differences among the ultraviolet spectra and fluorescence spectra of the extracted solutions of the three materials. No obvious absorption band was observed in the UV spectra of ethanol-extracted solution of Maorenshen, an absorption band at 280 nm was observed in the UV spectra of Actinidia chinensis and Actinidia polygama in ethanol extract-solutions. There were also different wavelength and strength in fluorescence spectra among extracted solutions of Maorenshen, Actinidia chinensis and Actinidia polygama. Therefore, it is feasible to identify Maorenshen (Actinidia valvata) and its confusable materials by ultraviolet spectrophotometry and fluorescence spectrophotometry.

A particle swarm optimization (PSO)-based least square support vector machine (LS-SVM) method was investigated for quantitative analysis of extraction solution of Yangxinshi tablet using near infrared (NIR) spectroscopy. The usable spectral region (5400–6200 cm-1) was identified, then the first derivative spectra smoothed using a Savitzky–Golay filter were employed to establish calibration models. The PSO algorithm was applied to select the LS-SVM hyperparameters (including the regularization and kernel parameters). The calibration models of total flavonoids, puerarin, salvianolic acid B and icariin were established using the optimum hyperparameters of LS-SVM. The performance of LS-SVM models were compared with partial least squares (PLS) regression, feed-forward back-propagation network (BPANN) and support vector machine (SVM). Experimental results showed that both the calibration results and prediction accuracy of the PSO-based LS-SVM method were superior to PLS, BP-ANN and SVM. For PSO-based LS-SVM models, the determination coefficients (R2) for the calibration set were above 0.9881, and the RSEP values were controlled within 5.772%. For the validation set, the RMSEP values were close to RMSEC and less than 0.042, the RSEP values were under 8.778%, which were much lower than the PLS, BP-ANN and SVM models. The PSO-based LS-SVM algorithm employed in this study exhibited excellent calibration performance and prediction accuracy, which has definite practice significance and application value.

The title compound, C26H26N4·2CH3OH, lies across a crystallographic inversion centre. The two benzimidazole pendant substituents adopt a trans conformation. O—H⋯N and C—H⋯O hydrogen bonds link the molecules into a two-dimensional network parallel to (\overline101).