Tetrazole derivatives synthesis using Fe3O4@fibroin-SO3H as a magnetically separable green solid acid nanocatalyst under solvent-free conditions

Research on Chemical Intermediates - In the present study, a magnetically separable potent solid acid nanocatalyst with a facile preparation technique was fabricated via incorporation of fibroin as...     

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 Next, bFGF was withdrawn, and cyclopamine and noggin were added.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.     

Nitric acid in the presence of P2O5 supported on silica gel—a useful reagent for nitration of aromatic compounds under solvent-free conditions

A variety of aromatic compounds are nitrated to parent nitro aromatic compounds under solvent-free conditions using 65% nitric acid in the presence of P₂O₅ supported on silica gel is described. This methodology is useful for nitration of activated and deactivated aromatic rings.     

Water promoted one-pot synthesis of 2′-aminobenzothiazolomethyl naphthols and 5-(2′-aminobenzothiazolomethyl)-6-hydroxyquinolines

A novel one-pot, three-component condensation reaction of an aldehyde, 2-aminobenzothiazole and 2-naphthol or 6-hydroxyquinoline in water to give 2′-aminobenzothiazolomethyl naphthols or 5-(2′-aminobenzothiazolomethyl)-6-hydroxyquinolines in high yields at 90 °C without using any catalyst, is described.     

Green Oxidations. Manganese(II) Sulfate Aided Oxidations of Organic Compounds by Potassium Permanganate

Summary. The oxidation of arenes and sulfides by potassium permanganate was accomplished in good yields under solvent free and heterogeneous conditions when manganese(II) sulfate is used as a solid support. After extraction of the organic products, the inorganic products can be reoxidized to permanganate. This result is important because it provides an approach to oxidation reactions that is, in theory, infinitely sustainable.