Indirect determination of organic compounds by atomic-absorption spectrophotometry

A review of the published methods for analysis of organic compounds by atomic-absorption spectrophotometry is given. Most of the applications are based on precipitation of metal compounds or solvent extraction of metal chelates or ion-association complexes. Although many of the methods offer great sensitivity, simplicity, and speed of analysis, few have been widely accepted by analysts, but some have proved to be satisfactory in field trials.     

Die Wechselwirkung zwischen Polymerisations-Initiatoren und -Inhibtoren in L?sung. 6. Mitt. Der Mechanismus der Wechselwirkung von Aroylperoxiden mit Hydrochinon in Chloroform und Acetonitril

Ohne Zusammenfassung     

Some of the dielectric properties of cotton cellulose and viscose

Complex dielectric constants were measured at frequencies of 0.1–10,000 kc/s over the temperature range of 0–60°C in medicated cotton cellulose and viscose. In these fibers evidence is found for a new secondary relaxation process within the frequency region of 0.1–1 kc/s. The significance of the results is discussed.     

Regioselective Diastereomeric Michael Adducts as Building Blocks in Heterocyclic Synthesis

The reaction of 4‐(4‐acetylamino/bromophenyl)‐4‐oxobut‐2‐enoic acids with carbon nucleophiles afforded Michael adducts depending on the type of nucleophilic reagents and medium (acidic or basic). The adducts 2 and 3 were used as key starting materials to synthesize some heterocyclic compounds, which include pyridazinone, furanone, 1,2‐oxazin‐5‐one, 1.2‐diazapine, pyrane, and hydroxyl pyridine derivatives. The Steric factor plays an important role in regioselectivity. The structure of newly synthesized compounds was elucidated by elemental analysis and spectroscopic data.     

Synthesis and Antimicrobial Evaluation of Newly Synthesized N,S‐Bisphosphonate Derivatives

An easy strategy for the synthesis of tetraethyl‐2‐(3‐mercapto‐4H‐1,2,4‐triazol‐4‐ylamino)‐2‐(aryl)ethane‐1,1‐diyldiphosphonate and tetraethyl‐(6‐(aryl)‐5,6‐dihydro[1,2,4]triazolo[3,4‐b]‐[1,3,4]thiadiazol‐6‐yl)methylenediphosphonate derivatives with reasonable 67–85% overall yields has been developed. The approach was achieved via applying Wadsworth–Horner–Emmons reagent, tetraethylmethylenebisphosphonate, to 4‐(arylideneamino)‐4H‐1,2,4‐triazole‐3‐thiols under phase‐transfer catalysis conditions. Screening results of antimicrobial potency for 12 out of 17 methylene‐1,1‐bisphosphonate products were reported. Two of the tested thiadiazolomethylenebisphosphonates displayed better spectrum of antimicrobial activity against the pathogens, compared with that of the positive controls.     

Synthetic Routes to Pyrazole‐3(5)‐carboxylates

The data on the synthetic methods of the pyrazole‐3(5)‐carboxylates published over the last years are reviewed here for the first time.     

Expansions for the Fundamental Hermite Interpolation Polynomials in Terms of Chebyshev Polynomials

We obtain explicit expansions of the fundamental Hermite interpolation polynomials in terms of Chebyshev polynomials in the case where the nodes considered are either zeros of the (n + 1)th-degree Chebyshev polynomial or extremum points of the nth-degree Chebyshev polynomial.     

The influence of electron density on the formation of streamers inelectrical discharges triggered with ultrashort laser pulses

In an ongoing program using ultrashort laser pulses to provoke discharges in air over considerable distances at electric fields below breakdown threshold, we have studied the conditions for the onset of streamers in such laser-produced plasmas, both experimentally and through numerical simulations. The results demonstrate the importance of the electron density and of its gradient on the generation of streamers. Also, a significant reduction of the breakdown voltage for a 30 cm plane-plane gap in air was observed with a laser pulse energy of 15 mJ. Finally, a direct comparison of laser-induced breakdown in air and in nitrogen shows the influence of electron attachment to oxygen on the discharge process     

Microanalysis of Two Members of Oxicam Drugs by Quenching the Fluorescence of Newly Isolated Carbonaceous Materials From Incense Ash

Journal of Fluorescence - For the first time ever, useful fluorescent (FL) carbonaceous materials (CMTS) were isolated from incense ash using facile procedure on two steps; dispersion of the CMTS...