k-torsionless modules with finite Gorenstein dimension

Let R be a commutative Noetherian ring. It is shown that the finitely generated R-module M with finite Gorenstein dimension is reflexive if and only if M _p is reflexive for p ∈ Spec(R) with depth(R _p) ? 1, and $G - {\dim _{{R_p}}}$ (M _p) ? depth(R _p) ? 2 for p ∈ Spec(R) with depth(R _p) ? 2. This gives a generalization of Serre and Samuel’s results on reflexive modules over a regular local ring and a generalization of a recent result due to Belshoff. In addition, for n ? 2 we give a characterization of n-Gorenstein rings via Gorenstein dimension of the dual of modules. Finally it is shown that every R-module has a k-torsionless cover provided R is a k-Gorenstein ring.     

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.     

Mono‐ and dinuclear oxime palladacycles bearing diphosphine ligands: An unusual coordination mode for dppe

Three new oxime‐based palladacycles, namely [Pd{C,N‐C₆H₄{C(Me)?NOH}‐2}(dppm)]ClO₄ ( 1 ), [Pd₂{C,N‐C₆H₄{C(Me)?NOH}‐2}₂(dppe)₂(μ‐dppe)](ClO₄)₂ ( 2 ) and [Pd{C,N‐C₆H₄{C(Me)?NOH}‐2}(dppmS₂)]ClO₄ ( 3 ), were synthesized by the reaction of dinuclear oxime complex [Pd{C,N‐C₆H₄{C(Me)?NOH}‐2}(μ‐Cl)]₂ with different diphosphine ligands (dppm, dppe and dppmS₂). The synthesized complexes were characterized using Fourier transform infrared, ³¹P NMR, ¹H NMR and ¹³C NMR spectroscopic methods and elemental analyses, and their molecular structures were elucidated using X‐ray crystallography. The structure of 2 is worthy of note as it is the first oxime palladacycle where there are both bridging (P–) and chelating (P^P) dppe ligands, giving rise to a dinuclear complex. The palladium atom is in a five‐coordinate, square pyramidal P₃NC environment, while in 3 the palladium atom is in a distorted square planar environment, coordinated by the oxime ligand and a chelating (S^S) dppmS₂ ligand. These complexes were employed as efficient catalysts for the Suzuki–Miyaura cross‐coupling reaction of several aryl bromides with phenylboronic acid. The in vitro cytotoxicity of the compounds was also evaluated against human tumour cell lines (HT29, A549 and HeLa) using the MTT assay method. The results indicate that the dinuclear complex 2 has greater catalytic and anticancer activity in comparison with the mononuclear complexes 1 and 3 .     

2D ZnO/Fe3O4 nanocomposites as a novel catalyst-promoted green synthesis of novel quinazoline phosphonate derivatives

In this research a novel and efficient procedure for the preparation of phosphonate derivatives using the reaction of 2,4-dihydroxyacetophenone, isopropenylacetylene, 2-amino-N-alkyl benzamide, dialkyl acetylenedicarboxylates and trimethyl phosphite or triphenyl phosphite in the presence of reusable 2D ZnO/Fe₃O₄ nanocomposites in water at room temperature was investigated. The 2D ZnO/Fe₃O₄ nanocomposites were synthesized using ionic liquid [OMIM]Br as a stabilizer and soft template. In addition, the power of antioxidant for some prepared compounds was studied using trapping of radicals by DPPH and a ferric reduction activity potential experiment. As a result, compound 6f displayed a noteworthy power for trapping of free radicals and 6b exhibited excellent reducing power compared with standards (BHT and TBHQ). Moreover, the antimicrobial power of some prepared quinazolinone phosphonates was proved by employing the disk diffusion experiment on two kinds of bacteria, Gram-positive and -negative bacteria. The obtained outcomes of disk diffusion test showed that these compounds prevented bacterial growth. Some advantages of this procedure are: short time of reaction, high yields of product and easy separation of catalyst and products.     

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.