Fatty acid hydrazides in heterocyclic synthesis: Synthesis of 1,2‐diazepine and pyridazine derivatives

1,2‐Diazepinone derivatives 6a–d, 8a,b, and 10a–c were synthesized from the reaction of olefines carrying EWG as ethoxymethylene malononitrile, ethoxymethylene cyanoacetate, and tetracyanoethylene with 1a–f respectively. Also, 5‐alkyl‐6‐oxotetrahydropyridazine‐4,4‐dicarboxylate derivatives 12a–c were afforded via the reaction of 1d–f with diethyl ethoxymethylene malonate. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:259–264, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20294     

Inverse Gas Chromatographic Study of the Oxidation Stability of Lubricating Base Oils via Solubility Parameter Calculations

 The Flory-Huggins interaction parameter (χ∞1,2) and solubility parameter (δ2) and its hydrogen bonding sensing component (δh) were determined using inverse gas chromatography (IGC). These parameters were successfully used in the probes of chemical changes that occur during the oxidation of naphthenic and paraffinic base oils in a GC column. Changes in χ∞1,2 values reflect the different types of intermolecular interactions (dispersive, polar, hydrogen bonding) of the given lubricating base oil during oxidation. The obtained results showed that δh component of solubility parameter is the most important parameter for probing the oxidative-chemical changes during the oxidation of given lubricating oils.     

One-pot,solvent-free and efficient synthesis of 2,4,6-triarylpyridines catalyzed by nano-titania-supported sulfonic acid as a novel heterogeneous nanocatalyst

Nano titania-supported sulfonic acid (n-TSA) has found to be a highly efficient, eco-friendly and recyclable heterogeneous nanocatalyst for the solvent-free synthesis of 2, 4, 6-triarylpyridines through one-pot three-component reaction of acetophenones, aryl aldehydes and ammonium acetate. This reported method illustrates several advantages such as environmental friendliness reaction conditions, simplicity, short reaction time, easy work up, reusability of catalyst and high yields of the products. One new compound is reported too. Furthermore, the catalyst could be recycled after a simple work-up, and reused at least six times without substantial reduction in its catalytic activity.     

Zinc polyoxometalate on activated carbon: an efficient catalyst for selective oxidation of alcohols with hydrogen peroxide

[PW₁₁ZnO₃₉]^5? was immobilized on activated carbon and characterized using Fourier transform infrared, X‐ray diffraction, Brunauer–Emmett–Teller and elemental analysis techniques. Effective oxidation of various alcohols with hydrogen peroxide was performed in the presence of this catalyst. Easy separation of the catalyst from the reaction mixture, cheapness, high activity and selectivity, stability as well as retained activity in subsequent catalytic cycles make this supported catalyst suitable for small‐scale synthesis. Copyright © 2015 John Wiley & Sons, Ltd.     

The Effect of Pancreas Islet-Releasing Factors on the Direction of Embryonic Stem Cells Towards Pdx1 Expressing Cells

Diabetes mellitus, which is the result of autoimmune destruction of the insulin-producing β cells, occurs by loss of insulin-secreting capacity. The insufficient source of insulin-producing cells (IPCs) is the major obstacle for using transplantation as diabetes treatment method. The present study suggests a method to form islet-like clusters of IPCs derived from mouse embryonic stem cells (mESCs). This protocol consists of several steps. Before starting this protocol, embryoid bodies (EBs) should be cultured in suspension in conditioned medium of isolated mouse pancreatic islet in combination with activing A to be induced. Then differentiated mESCs were replaced with dishes supplemented with basic fibroblast growth factor (bFGF). Next, bFGF was withdrawn, and cyclopamine and noggin were added. Then the cells were treated with B27, nicotinamide, and islet-conditioned medium for maturation. mESCs, as the control group, were cultured without any treatment. An enhanced expression of pancreatic-specific genes was detected by qRT-PCR and immunofluorescence in the differentiated mESCs. The differentiated mESCsco express other markers of pancreatic islet cells as well as insulin. This method exhibited higher insulin generation and further improvement in IPCs protocol that may result in an unlimited source of ES cells suitable for transplantation. The results indicated that conditioned medium, just as critical components of the stem cell niche associated with other factors, had high potential to differentiate mESCs into IPCs.     

<Superscript>68</Superscript>Ga-radiolabeled magnetic nanoparticles for PET–MRI imaging

In this study, magnetic multimodal nanoparticles with potential applications in magnetic- and nuclear-medicine imaging, magnetic resonance imaging, hyperthermia, and theranostic (therapeutic and diagnostic), applications were prepared by coating iron oxide nanoparticles with silica (core–shell), functionalizing with aminopropyltriethoxy silane and coupling with diethylenetriamine pentaacetic acid ligand (DTPA). Radiolabeling of core–shell–DTPA particles with ⁶⁸Ga radiometal was carried out through chelation of ⁶⁸Ga(III) ions by DTPA and was used for positron emission tomography. The biodistribution of the ⁶⁸Ga-radiolabeled magnetic nanoparticles compared to free ⁶⁸Ga(III) was checked in normal Balb/c mice up to 2 h.     

Smart modification of inorganic fibers and flammability mechanical and radiation shielding properties of their rubber composites

Facile and smart method for the modification of inorganic fibers has been developed. The polyaniline was synthesized on basalt fiber surface presenting an organic polymer shell to the inorganic fibers. The modified basalt fibers were dispersed in rubber-producing well-dispersed rubber composites. Various mass loadings of modified basalt fibers were dispersed and optimized. The effect of radiation on the properties of developed rubber composites was investigated by exposure to different gamma radiation doses. The flammability, thermal and mechanical properties were studied. The flammability of developed composites was improved achieving 62 and 16% reduction in the peak heat release rate compared to blank rubber and unmodified basalt fiber-based rubber composite, respectively. This is in addition to significant reduction in emission of CO and CO₂ gases by 65 and 58%, respectively. Also, the tensile strength property was enhanced by 38 and 53% compared to blank and unmodified basalt composite, respectively. The role of polyaniline layer on inorganic fiber surface and their effect on the properties of the produced composites was studied. The organic polymer shell achieved good compatibility and interfacial adhesion of basalt fibers with rubber matrix and radiation protection effect for the developed composites.     

Dispelling myths on superposition attacks: formal security model and attack analyses

Designs, Codes and Cryptography - With the emergence of quantum communication, it is of folkloric belief that the security of classical cryptographic protocols is automatically broken if the...     

Comparison of GC and HPLC Methods for Quantitative Analysis of Tinuvin 622 After Saponification in Polyethylene

This study describes the sample preparation and two chromatographic techniques for determination of Tinuvin 622 in polyethylene. The first part of the two methods consisting of dissolving the polyethylene in boiling xylene is followed by addition of a methanolic solution of potassium hydroxide. The polymeric light stabilizer, Tinuvin 622, is thereby saponified to 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (diol). Addition of the methanolic solution of the saponification reagent simultaneously precipitates the polyethylene matrix. Then the diol is quantified using either gas chromatography (GC) or high performance liquid chromatography (HPLC). For GC, a Macherey Nagel Optima-17 capillary column (30m×0.25mm ID, film thickness 0.25µm) is used. Nitrogen is used as carrier gas and make-up gas. The detection system is a flame ionization detector. For HPLC, an octadecyl silane (ODS) column (30cm×4mm, particle size 5µm) and a mobile phase methanol: water mixture (3:97, v/v) are used. Detection of analyte is carried out at 215nm. Both methods can be used to determine Tinuvin 622 in polyethylene in the concentration range of 0.02–1%, which represents the usual application concentration.     

The estimation of the hydrophobic and electrostatic contributions to the free energy change upon cationic surfactants binding to Jack bean urease

The binding of a homologous series of n-alkyltrimethyl ammonium bromides with Jack bean urease (JBU) have been studied previously. It has been suggested that both electrostatic and hydrophobic interactions are involved in the formation of surfactant-protein complexes, but there is not any quantities analyzing method for resolution of their contributions in the process. In the present study, at first, the intrinsic Gibbs free energy of binding, ΔG_b,ν, has been calculated for these systems and the trend of variation for both binding sets have been interpreted on basis of cooperativity and hydrophobicity of surfactants. Subsequently, a novel approach has been introduced for estimation of electrostatic and hydrophobic interactions in ΔG_b,ν, by considering of this fact that ΔG_b,ν is the summation of electrostatic, ΔG_b,ν(ele), and hydrophobic, ΔG_b,ν(hyd), parts and considering this fact that just ΔG_b,ν(hyd) is a function of hydrocarbon tail length of surfactant (C_n). The results represents the higher positive rule of electrostatic interactions in binding affinity of first set and inhibiting rule of this interaction in the second binding set. The predominate driving force in the second binding set is entropy statistical effect, which arises from numerous number of binding sites in this set. A binding mechanism on basis of structural changes in JBU due to its interaction with cationic surfactants has also been proposed.