Rotational measurements on (4–6), (5–7) bands of CN (B2Σ+ − X2Σ+) transition

Rotational analysis of (4–6), (5–7) bands of CN (B ² Σ ⁺ −X ² Σ ⁺) transition extending to highJ and emitted from the chemiluminescent reaction involving pink afterglow of nitrogen is presented.     

Total Synthesis of (±)-Celaphanol A

Celaphanol A was a diterpene isolated from the stems of Celastrus stephanotifolius1, which have been the subject of continued and growing interest, due to the range of biological activities shown by many members of this family2. Some have been used in traditional medicine3 or as a stimulant4 from ancient times. In order to further study the relationship between the structure and biological activity of the diterpene compound and as an extension of diterpenoid synthesis in our laboratory5, 6, …     

分光光度法测定土壤中总磷

氢氧化钠熔融法消解，调节pH值，加入抗坏血酸溶液及钼酸铵盐溶液显色15min，用30mm比色皿，以水为参比．于700nm波长处测定吸光度，求出土壤中的总磷。实验表明，样品分解完全，回收率为96．2％-97．5％；RSD为3．1％；检出限为0．07mg／L；线性范围为0-1．00mg／L。本法简便、可靠、能够满足环境监测对土壤中总磷分析的需要。     

Total reflection X-ray fluorescence polymer spectra: classification by taxonomy statistic tools

The aim of this work is to explore the use of chemometric tools for the classification of synthetic and natural polymers with a mean molecular weight greater than 10(6). Total Reflection X-Ray Fluorescence (TXRF) spectra were obtained and analyzed in order to retrieve matrix information and to illustrate the calibration procedure. The intensities of the coherent and incoherent scattered peaks were specially selected for this purpose. The polymers studied were aqueous solutions of scleroglucan, polyacrilamide, polyoxyethylene oxide, glucomannan, 2,3,6-tri-o-ethylamylose and xhantan, in concentrations upto 1% (m/m). matlab software was used for numerical calculations. Using a combination of principal component analysis and cluster analysis, the differences in composition of various analyzed polymers can be visualized.     

Theoretical investigation of the initial steps of the adsorption of N atoms on Si(1 0 0)-2×1

Structural, energetics, and mechanistics aspects of initial steps of the reaction of a N atom with Si(1 0 0)-2×1 modeled by the Si₉H₁₂+N system are reported. Hybrid density functional B3LYP calculations predict a barrierless first step leading to an adsorbate where N is bound to one of the dimer Si. Two possible activated routes for internal rearrangements were found, with that leading to the incorporation of Si below the first layer predicted to be kinetically dominant (98%) under the experimental conditions. This structure and frequency calculations are consistent with the experimental finding of a planar NSi₃ moeity and with the experimental SiN asymmetric stretching frequency of the NSi₃ groups.     

Three-Dimension Mathematical Model of Total Phosphor in the Reservoir and Application

Taking the transport of total phosphor pollutants in the Beijing Miyun reservoir for example, we haveobtained three dimensional distributing regularity of total phosphor pollutants by the calculation of the linearinterpolation value of each point between horizontal layers. The credibility analysis in allusion to this methodwas carried out and the programming scheme for realizing this method was set forth.     

Effect of complexones and tensides on selectivity of nitrogen dioxide determination in air with a chemiluminescence aerosol detector

Modification of the luminol solution by means of addition of various complexones and surfactants has been investigated to eliminate interferences from gaseous co-pollutants in the determination of ambient nitrogen dioxide using a chemiluminescence aerosol detector. The simultaneous presence of EDTA and triton X-100 or X-405 together with sulphite and iodide in the luminol solution suppressed interferences from ozone and peroxyacetyl nitrate to a negligible level and no scrubbers or corrections of the NO₂ measurements were needed.

In general, the best composition of the reagent solution included luminol, KOH, Na₂SO₃, KI, Na₂EDTA and triton X-100. From the point of view of selectivity of NO₂ determination, an optimum reagent solution consisted of luminol (0.002 M), KOH (0.5 M), Na₂SO₃ (0.2 M), KI (0.1 M), Na₂EDTA (0.05 M) and triton X-100 (0.5 vol.%). Interferences from ozone (170 ppb (v/v)) and peroxyacetyl nitrate (81 ppb (v/v)) were 0.2 and 1.2%, respectively, for nitrogen dioxide at a concentration of 50 ppb (v/v) and 0.25 and 1.7%, respectively, for 0.5 ppb (v/v) NO₂. The calibration graph was linear for NO₂ concentrations ranging from 3 to 665 ppb (v/v). Below 3 ppb (v/v) NO₂ the detector response to nitrogen dioxide can be fitted with a linear equation of the third order.     

Analysis of the relationship between total and effective rainfall by means of streamflow shot noise and rainfall stochastic models

Linking the results of two research topics on rainfall and streamflow stochastic models, the relationship between total and effective rainfall is studied here. The short time streamflow process is examined concerning the climatic and hydrogeological characters of the watershed, identifying four distinct components giving rise to runoff. In this way the watershed can be regarded as a four-component linear system, whose input is the effective rainfall. Finally, the streamflow model is used as an effective rainfall inverse estimator, allowing the analysis of the links between total and effective rainfall assuming a simple transformation law. The determination of this law is performed by applying a stochastic model, whose parameters are estimated on the companion series of recorded total rainfall and reconstructed effective rainfall. An application to a case study shows the effectiveness of the proposed approach.

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Sommario Raccordando i risultati di due ricerche sui modelli stocastici di pioggia e dei deflussi, vengono qui studiate le relazioni fra la pioggia totale e la pioggia efficace. I deflussi aggregati a breve scala temporale sono esaminati alla luce delle caratteristiche climatiche e idrogeologiche del bacino idrografico, identificando quanttro distinte componenti che danno origine al deflusso. II bacino idrografico viene così rappresentato da un sistema lineare a quattro componenti, il cui input è la pioggia efficace. Pertanto, il modello dei deflussi viene usato per effettuare la stima inversa delle piogge efficaci, consentendo lo studio delle relazioni fra le piogge totali ed efficaci ipotizzando una semplice legge di trasformazione. La determinazione di questa legge è effettuata applicando un modello stocastico, i cui parametri sono stimati sulle serie corrispondenti di pioggia totale registrata e di pioggia efficace ricostruita. Un'applicazione a un caso reale mostra l'efficacia dell'approccio proposto.