Nanocomposite mesoporous ordered films for lab-on-chip intrinsic surface enhanced Raman scattering detection

Mesoporous nanocomposite materials have been fabricated through integration of evaporation-induced self-assembly and deep X-ray lithography. Micropatterned films made using a mesoporous ordered silica matrix which contains silver nanoparticles have been obtained. The exposure of the mesoporous films to high energy X-rays, which are generated by a synchrotron source, produces several effects: the removal of the surfactant, the densification of the silica backbone and the formation of silver nanoparticles. This integrated process produces a nanocomposite material which has a 2D-hexagonal organized porosity and silver nanoparticles with a sharp size distribution around 5 nm. The patterned nanostructured films have been tested as a lab-on-chip device for intrinsic surface enhanced Raman scattering detection using a solution containing rhodamine 6G in ethanol and measuring Raman response as a function of laser power.     

Solubilization of coals by reductive alkylation

Anthracite, bituminous and subbituminous coal when treated with naphthalene anion in tetrahydrofuran added negative charges to form the corresponding coal anions. Alkylation of bituminous and subbituminous coal anion with ethyl iodide resulted in the addition of 16 and 14 ethyl groups per 100 carbon atoms. The alkylated coals were 88 and 45% soluble in benzene. The molecular weights of the benzene-soluble portions of the bituminous and subbituminous coal were respectively 2000 and 700. An attempt to add alkyl groups to anthracite anion was not successful.     

Studies on UV/Vis Absorption Spectra of Azo Dyes. 24. The different effect of a 2-methoxy and a 3-methoxy group in 4-N.N-diethylaminoazobenzenes on colour

A number of 2- and 3-methoxy-substituted-4-N.N-diethylaminoazobenzenes have been prepared and their absorption maxima in ethanol and toluene compared with the corresponding 4-N.N-diethylaminoazobenzenes. Both the 2- and 3-methoxy groups cause a bathochromic shift, but the bathochromic shift of a 3-methoxy group depends on the substituents in the diazo component. With increasing electron-withdrawing strength of the substituents in the diazo component a progressive enhancement of bathochromic shift appears. In toluene all 3-methoxy-substituted dyes absorb at longer wavelengths compared with the 2-methoxy-substituted dyes.     

Acylierung von Heterocyclen mit Kohlensäurederivaten. II. Endo- und exo-Carbamoylierung von 2-Amino-benzimidazol-Derivaten mit Isocyanaten. Mechanismus der Acylgruppenwanderung

Acylation of Heterocycles with Carbonic Acid Derivatives. II. Endo and Exo Carbamoylation of 2-Amino-benzimidazole Derivatives with Isocyanates. Mechanism of the Acyl Group Migration 2-Amino-benzimidazoles react with isocyanates with good yields to give 2-amino-1-carbamoyl-aminobenzimidazoles 1 at −30°C and the corresponding 2-carbamoyl isomeres 2 at room temperature, respectively. The isomerization mechanism was studied by crossover experiments and kinetic measurements and has been found to consist of inter- and monomolecular acyl transfer.     

Zur Alkylierung und Acylierung von 5-Hydrazino-1,2,3,4-thiatriazolderivaten

On Alkylation and Acylation of 5-Hydrazino-1,2,3,4-thiatriazole Derivatives 5-Hydrazino-1,2,3,4-thiatriazole reacts with oxo carboxylic acids to give highly unstable 5-carboxyalkylidene-hydrazino-1,2,3,4-thiatriazoles ( 2 ). The more stable 5-alkylidenehydrazino-1,2,3,4-thiatriazoles ( 3 ) may be alkylated; the thiatriazole system is retained. On action of activated nitriles or isocyanates 1,2,4-thiadiazole ( 6 ) or 1,2,4-thiadiazoline derivatives ( 7 ) are formed with nitrogen evolution. At temperatures above 40°C, the described thiatriazoles decomposed to give undefinable components.     

Variability of herbicide losses from 13 fields to surface water within a small catchment after a controlled herbicide application

Diffuse losses from agricultural fields are a major input source for herbicides in surface waters. In this and in a companion paper, we present the results of a comprehensive field study aimed at assessing the overall loss dynamics of three model herbicides (i.e., atrazine, dimethenamid, and metolachlor) from a small agricultural catchment (2.1 km2) and evaluating the relative contributions of various fields having different soil and topographical characteristics. An identical mixture of the three model herbicides as well as an additional pesticide for identification of a given field were applied within 12 h on 13 cornfields (total area approximately 12 ha), thus ensuring that the herbicides were exposed to identical meteorological conditions. After the simultaneous application, the concentrations of the compounds were monitored in the soils and at the outlets of three subcatchments containing between 4 and 5 cornfields each. Particular emphasis was placed on the two rain events that led to the major losses of the herbicides. The rank orders of herbicide dissipation in the soils and of the compound-specific mobilization into runoff were the same in all three subcatchments and were independent of the field characteristics. In contrast, the field properties caused the relative losses from two subcatchments to differ by up to a factor of 56 during the most important event, whereas compound-specific differences of the three neutral herbicides caused the losses to vary only by a factor of 2 during the same event. The enormous spatial variability was mainly caused by factors influencing the fraction of rain that was lost to surface water by fast transport mechanisms. Thus, the key factors determining the spatially variable herbicide losses were the permeability of the soils, the topography, and the location of subsurface drainage systems. These results illustrate the large potential to reduce herbicide losses by avoiding application on risk areas.