Thermal conductivity modeling of nanofluids with ZnO particles by using approaches based on artificial neural network and MARS

Journal of Thermal Analysis and Calorimetry - Nanofluids are attractive alternatives for the current heat transfer fluids due to their remarkably higher thermal conductivity which leads to the...     

Unexpected ring transformation to pyrrolo[3.2-b]pyridine derivatives. Fused azolium salts. 22

2-Arylsulfanyl and 2-benzylsulfanylpyridinium N-arylimides (2) easily prepared from 3-aryltetrazolopyridinium salts (1) with aryl and benzylthiolates, respectively, reacted with various dipolarophiles yielding cycloadducts that underwent transformation to give tetrahydropyrrolo[3,2-b]pyridines (5, 6, and 8) in good yields. A similar rearrangement (formation of 15) was also observed in the case of parent derivatives being unsubstituted in position 2 (12). The abscence of any significant solvent effect, comparison of the sulfur and non-sulfur analogues, as well as the stereoselective nature of the observed ring transformation seem to support a sigmatropic mechanism. Structure elucidation of the products has been carried out by single-crystal X-ray diffraction and (1)H NMR experiments.     

Di­aqua­bis(4,5‐di­hydro‐1,2,4‐triazolo[1,5‐a]­pyrimidin‐5‐one‐N3)bis­(thiocyanato‐N)­nickel(II)

The title compound, [Ni(NCS)₂(C₅H₄N₄O)₂(H₂O)₂], crystallizes in the triclinic space group P. The molecular unit contains two neutral mol­ecules of 4,5‐di­hydro‐1,2,4‐triazolo[1,5‐a]­pyrimidin‐5‐one (5HtpO) coordinated through the N atom in position 3, two thio­cyanate ligands coordinated through their N atoms and two water mol­ecules completing an octahedral environment around the Ni^II ion, which lies on a centre of inversion. The structure is stabilized by hydrogen bonding. Distances in the coordination sphere are Ni—N3(5HtpO) 2.132 (2), Ni—O(water) 2.085 (2) and Ni—N(thio­cyanato) 2.040 (2) Å.     

Application of Supercritical fluid Extraction For Analysis of Organophosphates in Cereals

Abstract

Application of supercritical fluid extraction (SFE) utilizing pure carbon dioxide for selective isolation of organophosphates from contaminated cereals has been tested.

At the beginning of the experiments the extractability of added standards from an empty extraction vessel (thimble) and from various materials such as filter paper, sand, Celite and anhydrous sodium sulfate was tested to estimate the behavior of organophosphates. Further method development was carried out using a spiked sample of flour, which was analyzed within the proficiency testing for organophosphorus pesticides analysis (round 7) organized by Food Analysis Performance Assessment Scheme (FAPAS, MAFF-UK).

Comparison of the SFE method with a classical method currently employed for sample preparation (i.e. extraction with acetone/methanol mixture followed by gel permeation chromatographic clean up) showed advantages of the SFE technique such as simplification of the sample preparation step and thereby significant speeding up of the determination of organophosphates in cereals.     

Analysis of PCBs in Biotic Matrices by Two-Dimensional GC-ECD

Abstract

The suitability of three GC-ECD systems for the separation of a model mixture containing various congeners of PCBs together with persistent chlorinated aromatics (pesticides and their metabolites, industrial chemicals) was tested. Analyses were performed on two parallel capillaries, the stationary phase of one of them was always in routine practice very common 5% phenyl-methylpolysiloxane, the second one was either 50% phenylmethylpolysiloxane or 7% phenyl-7% cyanopropyl-methylpolysiloxane. The number of unresolved (coeluted) analytes was significantly reduced in these systems and thus unbiased quantitation of PCBs and other components used for regulation was possible. The utilization of this type of multidimensional chromatography for rapid and reliable analysis of real samples (fish oil, human fat) was documented.     

Head-to-head bisbenzazole derivatives as antiproliferative agents: design,synthesis, in vitro activity,and SAR analysis

Molecular Diversity - In the present work, a series of bisbenzazole derivatives were designed and synthesized as antiproliferative agents. The antiproliferative activity of these compounds was...     

The new method of fabrication of submicron structures by optical lithography with mask shifting and mask rotation

This paper presents the methods of fabricating narrow parallel submicrometric stripes in silicon dioxide and a resist layer. The experiments were conducted by two techniques: double patterning lithography and double exposure lithography. In addition to the above mentioned processes, mask translation was applied. For all conducted experiments, chrome masks and a 405 nm line of the high pressure mercury lamp of an MA-56 Mask Aligner System were used. The main aim of the performed tests was to establish the utility and the possible applications of the methods used.     

Applications of intelligent methods in various types of heat exchangers: a review

Journal of Thermal Analysis and Calorimetry - Heat exchangers are applicable in different industries and technologies, and their performance is influenced by different parameters. In addition to...