A Theoretical Study of OH and OCH3 Free Radical Adsorption on a Nanosized Tube of BC2N

By using density functional theory calculations, we have investigated the adsorption of OH and OCH₃ free radicals on a BC₂N nanotube based on the energetic, electronic and geometric properties. The adsorption of radicals on the top of a B atom is more favorable than that on the other sites and reaction energies have been calculated to be in the range of ?0.57 to ?1.48 eV for OH and ?0.27 to ?1.19 eV for OCH₃. It was found that the adsorption of radicals may facilitate the electron emission from the BC₂N nanotube surface by decreasing the work function due to the charge transfer which occurs between the tube and radicals. Also, HOMO/LUMO gap of the tube is significantly decreased, which may result in the increase of the electrical conductivity of the tube.     

Cloning and Expression of Che a 1, the Major Allergen of <Emphasis Type="Italic">Chenopodium album</Emphasis> in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Chenopodium album is a weedy annual plant in the genus Chenopodium. C. album pollen represents a predominant allergen source in Iran. The main C. album pollen allergens have been described as Che a 1, Che a 2, and Che a 3. The aim of this work was to clone the Che a 1 in Escherichia coli to establish a system for overproduction of the recombinant Che a 1 (rChe a 1). In order to clone this allergen, the pollens were subjected to RNA extraction. A full-length fragment encoding Che a 1 was prepared by polymerase chain reaction amplification of the first-strand cDNA synthesized from extracted RNA. Cloning was carried out by inserting the cDNA into the pET21b (+) vector, thereafter the construct was transformed into E. coli Top10 cells and expression of the protein was induced by IPTG. The rChe a 1 was purified using histidine tag in recombinant protein by means of Ni–NTA affinity chromatography. IgE immunoblotting, ELISA, and inhibition ELISA were done to evaluate IgE binding of the purified protein. In conclusion, the cDNA for the major allergen of the C. album pollen, Che a 1, was successfully cloned and rChe a 1 was purified. Inhibition assays demonstrated allergic subjects sera reacted with rChe a 1 similar to natural Che a 1 in crude extract of C. album pollen. This study is the first report of using the E. coli as a prokaryotic system for Che a 1 cloning and production of rChe a 1.     

Solid Particle Distribution in Centrifugal Impeller Contactors

The recently developed centrifugal impeller is examined to investigate the solid–liquid mixing in a mechanically agitated contactor. Using the sample withdrawal method, the effects of impeller geometrical parameters, impeller rotational speed (200–700 rpm), solid particle size (500–1100 µm), and solid loading (2–10 vol%) on the degree of homogeneity are studied. The axial and the radial solid concentration profiles and the minimum impeller speed for the complete homogenization are also determined. In comparison with a widely used propeller impeller, considerably higher homogeneity values in lower impeller speeds are obtained (90% homogeneity against 16% homogeneity at 200 rpm at the same conditions). Having also lower power consumption makes this a superior impeller in solid–liquid mixing processes especially in shear-sensitive systems.      

Synthesis, computational study and binding properties of some structurally rigid glycoluril-derived molecular clips

Several new clip-shaped molecules, with different degrees of steric hindrance around their cavities as well as more rigidity on their glycoluril scaffold, have been synthesized and the molecular geometry of their most stable structures has been investigated and optimized with density functional theory (DFT) at the B3LYP level of theory using 6-311G basis set. The affinity of these molecular clips for some dihydroxybenzene derivatives (guests) has been computationally and experimentally studied. The clips having dimethyl-substituted aromatic side walls, showed the best interaction energies towards the mentioned guests. Also, the computational results revealed that the more electron-deficient guest interacts more strongly with the clips (hosts).     

Synthesis and computational study of two new glycoluril clips containing benzocrown ether side walls

Two new glycoluril-derived molecular clips containing benzocrown ether side walls have been synthesized via reaction of a glycoluril scaffold with two bromomethylated benzocrown ethers. The molecular geometry of their most stable structures were investigated with density functional theory at the B3LYP level of theory using STO-3G, 6-31G, and 6-311G basis sets. Then based on the obtained computer-optimized structures, the binding properties of one clip with some 5-substituted resorcinols have been calculated.     

A comparative MP2 study between water- and acid-assisted proton transfer: allophanic acid as a case of study

Electronic structures of allophanic acid were studied using MP2/6-311++G(d,p) level of theory. Five most stable tautomers were selected and stability of them was studied in detail. Obtained data showed that tautomer 1 having hydrogen atom in the central nitrogen N3 and also in a trans conformation of carbonyl and amino functional groups becomes the most stable one. Then, interconversion of these tautomers to each other was investigated step by step through internal rotation and proton transfer routes. Results indicated that movement of protons determines rate-determining step of all paths A–E. Effects of different solvents were carefully surveyed for each tautomer, and among investigated solvents, water made slight stabilization. Activation barrier for proton exchange assisted by one water molecule and one formic acid molecule was also studied, separately. Both molecules had a great influence on lowering barrier especially for proton transfer routes. Comparative MP2 study showed that the barrier will be lowered much more when acid-assisted proton exchange takes place.     

Cyclometalated organoplatinum(II) complexes: first example of a monodentate benzo[h]quinolyl ligand and a complex with bridging bis(diphenylphosphino)ethane

The cyclometalated complexes [Pt(ppy)R(SMe(2))] or [Pt(bhq)R(SMe(2))], where ppyH = 2-phenylpyridine, bhqH = benzo[h]quinoline and R = methyl or p-tolyl, react with bis(diphenylphosphino)ethane, dppe, in a 1:1 ratio to give the corresponding complexes [Pt(κ(1)-C-ppy)R(dppe)] or [Pt(κ(1)-C-bhq)R(dppe)], in which the ppy or bhq ligands are monodentate and dppe is chelating. The similar reaction in a 2:1 ratio gives the binuclear complexes [{Pt(ppy)R}(2)(μ-dppe)] or [{Pt(bhq)R}(2)(μ-dppe)], in which the dppe ligands are in the unusual bridging bidentate bonding mode.     

Adsorption of p-Nitrophenol in Untreated and Treated Activated Carbon

The adsorption of p-nitrophenol in one untreated activated carbon (F100) and three treated activated carbons (H₂, H₂SO₄ and Urea treated F100) was carried out at undissociated and dissociated conditions.To characterize the carbon, N₂ and CO₂ adsorption were used. X-ray Photoelectron Spectroscopy (XPS) was used to analyze the surface of the activated carbon.The experimental isotherms are fitted via the Langmuir homogenous model and Langmuir binary model. Variation of the model parameters with the solution pH is studied. Both Q _max and the adsorption affinity coefficient (K ₁) were dependent on the PZC of the carbons and solution pH. The Effect of pH must be considered due to its combined effects on the carbon surface and on the solute molecules. Adsorption of p-nitrophenol at higher pH was found to be dependent on the concentration of the anionic form of the solute.     

An efficient method for purification of nonspecific lipid transfer protein‐1 from rice seeds using kiwifruit actinidin proteolysis and ion exchange chromatography

Plant nonspecific lipid transfer proteins are small basic proteins that transport phospholipids between membranes and are subdivided into two subfamilies, nsLTP₁ (9 kDa) and nsLTP₂ (7 kDa). LTPs have potential application in the defense reactions against pathogens and the drug delivery systems. Many efforts have been made for purification of different nsLTPs from various plants; however, most of them used successive purification procedures. We have developed a relatively simple and efficient method for the purification of rice nsLTP₁, based on the proteolytic activity of kiwifruit actinidin on the rice seed extract and one‐step chromatographic procedure on a CM‐Sepharose column. The purity of protein was determined by reversed‐phase high‐performance liquid chromatography (RP‐HPLC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). The isolated LTP₁ migrated as a homogenous polypeptide with molecular mass of 9 kDa that confirms the efficiency of actinidin on the digestion of major contaminations present in the rice seed extract without any harmful effect on the LTP₁. The advantages of using proteolytic activity of actinidin in purifying rice LTP₁ includes the reduced separation time allowing the purification of LTP₁ in one‐step chromatographic procedure, low costing, high efficiency, and the relative simplicity of the method.