Optimization of heat transfer and pressure drop in a tube with loose-fit perforated twisted tapes by Taguchi method and grey relational analysis

Journal of Thermal Analysis and Calorimetry - This work introduces the determination of the optimum values of the design parameters in a tube with loose-fit perforated twisted tapes. The effects of...     

An observation on realcompact spaces

We give a characterization of realcompact spaces in terms of nets. By using the technique of this characterization we give easy proofs of the Tychonoff Theorem and the Alaoglu Theorem.

     

Preparation of micro- and nanopatterns of polymer chains grafted onto flexible polymer substrates

In this work a simple novel method for preparing micro- and nanoscale patterns of polymer chains grafted onto flexible polymer substrates is described. A combination of the two techniques of radiation grafting and "grafting-from" has been made. This combination makes it possible to prepare grafted structures having micro- or nanoscale lateral dimensions that are determined by the electron beam or X-ray irradiation patterns used. The height of the grafted features can be controlled by the irradiation dose or such grafting reaction conditions as time, temperature, or monomer concentration. Our first results for nanopatterned samples demonstrate resolution comparable to those of other polymer-based lithography processes.     

99mTc-labelled human serum albumin: Chemical and electrochemical labelling methods

The labelling of human serum albumin /HSA/ with^99mTc has been investigated using a chemical method /stannous citrate/ and electrolytically generated tin/II/ ions. A comparative study of various chemical parameters and current intensities has been carried out in order to find the optimal conditions for labelling. The labelling yield was over 95%, for the chemical and electrolytical methods.     

A 45 ns 8+ isomer in the doubly odd150Eu nucleus

In the doubly odd ₆₃ ¹⁵⁰ Eu⁸⁷ nucleus a 45 ns 8⁺ isomer at 589 keV excitation has been identified through (p, 3n) in beamγ ande ^? measurements. The low lying negative parity levels populated in its decay show great similarity to analogous states in the lighter odd-odd Eu neighbours suggesting a spherical shape for¹⁵⁰Eu. A spherical shape is also proposed for the isomer which is assigned as (πh _11/2 vf ₇ ^2/?3 )8⁺ state analogous to the 9⁺ isomers known in¹⁴⁸Eu and¹⁴⁶Eu. The spin change is attributed to the crossing of the half-filledf _7/2 neutron shell atN=86.     

Direct determination of the complete set of iron normal modes in a porphyrin-imidazole model for carbonmonoxy-heme proteins: [Fe(TPP)(CO)(1-MeIm)

Detailed Fe vibrational spectra have been obtained for the heme model complex [Fe(TPP)(CO)(1-MeIm)] using a new, highly selective and quantitative technique, Nuclear Resonance Vibrational Spectroscopy (NRVS). This spectroscopy measures the complete vibrational density of states for iron atoms, from which normal modes can be calculated via refinement of the force constants. These data and mode assignments can reveal previously undetected vibrations and are useful for validating predictions based on optical spectroscopies and density functional theory, for example. Vibrational modes of the iron porphyrin-imidazole compound [Fe(TPP)(CO)(1-MeIm)] have been determined by refining normal mode calculations to NRVS data obtained at an X-ray synchrotron source. Iron dynamics of this compound, which serves as a useful model for the active site in the six-coordinate heme protein, carbonmonoxy-myoglobin, are discussed in relation to recently determined dynamics of a five-coordinate deoxy-myoglobin model, [Fe(TPP)(2-MeHIm)]. For the first time in a six-coordinate heme system, the iron-imidazole stretch mode has been observed, at 226 cm(-)(1). The heme in-plane modes with large contributions from the nu(42), nu(49), nu(50), and nu(53) modes of the core porphyrin are identified. In general, the iron modes can be attributed to coupling with the porphyrin core, the CO ligand, the imidazole ring, and/or the phenyl rings. Other significant findings are the observation that the porphyrin ring peripheral substituents are strongly coupled to the iron doming mode and that the Fe-C-O tilting and bending modes are related by a negative interaction force constant.     

Investigation of spectroscopic studies and DFT calculations on glucofuranose derivatives of dithiophosphonates

Abstract

2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson’s reagent: LR) was reacted with 1,2:5,6-di-O-cyclohexylidene-α-D-glucofuranose and 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose in toluene and gave rise to crude dithiophosphonic acids. The crude dithiophosphonic acids were treated with excess triethylamine and the triethylammonium salts of dithiophosphonic acids (1) and (2) were isolated by crystallization method. Compounds 1 and 2 were characterized by elemental analysis, IR, and NMR (¹H-, ¹³C- and ³¹P-) spectroscopies and mass spectrometry. In addition, NMR spectra, the electronic properties (the electronic chemical potential, electronegativity, chemical hardness and the global electrophilicity index) and NBO analysis of compound 2 have been calculated by using the Gaussian 16?W program. The electronic properties were calculated using Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies by density functional method (DFT/B3LYP) at 6-31G(d,p) level. The HOMO and LUMO energies are ?5.9 and ?0.72?eV, respectively. The HOMO–LUMO energy difference is 5.18?eV and this value shows that compound 2 has a high stability and low reactivity.     

Inhibitor design for 3-hydroxy-3-methyl-glutaryl-CoA reductase enzyme; molecular docking and determination of molecular and electronic properties of ligands by density functional theory method

Designing new inhibitors having less side effects is a need which also could reduce cholesterol levels. To fulfill this aim, we have carried out a molecular docking study toward 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase. A set of designed structural derivatives of statin drugs, eight ligands which are used as HIV-1 integrase inhibitor candidates, a set of terpenoids, and ligands downloaded from Zinc15 database were docked to HMG-CoA reductase enzyme which contains atorvastatin in crystal structure. The analysis of docking studies revealed that statin derivative ligands are more appropriate for inhibition of HMG-CoA reductase. To define the contribution of the molecular properties to the binding of ligands to enzyme structure; the highest occupied molecular orbitals-lowest unoccupied molecular orbitals, hardness, electronegativity, and chemical potential properties of ligands have best score in their sets calculated by quantum mechanical tools.