Observation of an unprecedented Cu Bis-His site: crystal structure of the H129V mutant of nitrite reductase

Copper nitrite reductases contain both an electron-transfer type 1 Cu site and a catalytic type 2 Cu site. We have mutated one of the type 2 copper ligating histidines to observe the effect on catalytic turnover. This mutation has created a unique site where Cu is ligated by 2 His Nepsilon2 atoms alone.     

L-Amino Acid Esters Studies: Part II: Synthesis of N-(Dimethoxy/3,5-Diacetoxybenzoyl)-L-Amino Acid Hydrazides and their Reactions with Aldehydes and Ketones

The synthesis of N-(dimethoxy and 3, 5-diacetoxybenzoyl) -L- amino acid hydrazides, and their reactions with some aldehydes and ketones are described.     

Determination of primordial radionuclide concentrations in UAE groundwater using high-resolution gamma-ray spectrometry

Journal of Radioanalytical and Nuclear Chemistry - Groundwater is the most valuable resource in arid regions, such as UAE. Estimations of natural radionuclide concentrations are important to...     

Synthesis of attapulgite-MnO2 nanocomposite from manganese complex by ultrasound for hydrogen storage

The research included the synthesis of a new complex of manganese with 3,4,5-tri-methoxybenzoic acid in the presence of triethylamine as a base to which gives the complex with formula [Mn (TMB)₂].2H₂O. This complex was characterized by FTIR, CHN, magnetic susceptibility and thermal analysis. Furthermore, this complex was used as a novel precursor of manganese in preparing the attapulgite-MnO₂ nanocomposite by one-pot addition method using ultrasound. The resulting nanocomposite was characterized by X-ray diffraction and TEM and the results prove that this composite was found as nanochannel of the diameter 45 nm decorated with 26–41 nm of MnO₂ nanoparticles. The attapulgite-MnO₂ nanocomposite was used in the application of hydrogen storage, and the results proved that attapulgite-MnO₂ nanocomposite has the ability to store 3.55 wt% of hydrogen under a pressure of 90 bar and a temperature of 77 K. Furthermore, the measurement demonstrated that increasing the pressure increased the stored hydrogen, implying that the stored gas will be liberated by altering the pressure, implying that the storage will be of the physical kind.     

1,3,4-Oxadiazole N-Mannich Bases: Synthesis,Antimicrobial, and Anti-Proliferative Activities

The reaction of 5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thione 3 with formaldehyde solution and primary aromatic amines or 1-substituted piperazines, in ethanol at room temperature yielded the corresponding N-Mannich bases 3-arylaminomethyl-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thiones 4a–l or 3-[(4-substituted piperazin-1-yl)methyl]-5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazole-2(3H)-thiones 5a–d, respectively. The in vitro inhibitory activity of compounds 4a–l and 5a–d was assessed against pathogenic Gram-positive, Gram-negative bacteria, and the yeast-like pathogenic fungus Candida albicans. The piperazinomethyl derivatives 5c and 5d displayed broad-spectrum antibacterial activities the minimal inhibitory concentration (MIC) 0.5–8 μg/mL) and compounds 4j, 4l, 5a, and 5b showed potent activity against the tested Gram-positive bacteria. In addition, the anti-proliferative activity of the compounds was evaluated against prostate cancer (PC3), human colorectal cancer (HCT-116), human hepatocellular carcinoma (HePG-2), human epithelioid carcinoma (HeLa), and human breast cancer (MCF7) cell lines. The optimum anti-proliferative activity was attained by compounds 4l, 5a, 5c, and 5d.     

Novel Foaming-Agent Free Insulating Geopolymer Based on Industrial Fly Ash and Rice Husk

This study highlights the synthesis of a new thermal insulating geopolymer based on the alkaline activation of fly ashes. A porous geopolymer material can be prepared without the addition of a foaming agent, using high ratio solution/ashes (activating solutions used are water, sodium or potassium hydroxide). In order to increase the porosity of the material and to make it more ecological, rice husks are incorporated into the formulation. The geopolymer materials were prepared at room temperature and dried at moderate temperature (105 °C) by a simple procedure. The microstructural characteristics of these new porous geopolymers were assessed by optical microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray fluorescence (XRF). Infrared spectroscopy (FTIR) was used to confirm the geopolymerisation. The effect of the ratio solution/ashes and the percentage of the rice husk addition on thermal and mechanical analysis was evaluated. An insulating material for a solution/ashes ratio of 0.9 and a rice husk content of 15% having a λ value of 0.087 W/(m·K), a porosity of 61.4% and an Rc value of 0.1 MPa was successfully prepared.     

The Application of Vinamidinium Salts to the Synthesis of 2‐Amino‐5‐aryl or Formylpyridine‐3‐carbonitriles

The symmetrical vinamidinium salts were allowed to react with malononitrile in refluxing ethanol in the presence of ammonium acetate for 12 h to afford the 2‐amino‐5‐aryl or formylpyridine‐3‐carbonitriles.     

L-Amino Acid Esters Studies: Part I: Synthesis Of New Methyl N -(Dimethoxy / 3,5 -Diacetoxybenzoyl) -L- Amino Acid Ester Derivatives

A series of new methyl N-(dimedioxy / 3,5-diacetoxybenzoyl)-L-amino acid esters have been synthesized by two methods.     

Synthesis of the active sites of molybdoenzymes: MoO2(VI) and MoO(IV)-dithiolene complexes mimicking enzymatic reactions of sulphite oxidase with saturation kinetics

[Mo^VIO₂(S₂C₂(CN)₂)₂]₂₋ (┘1) and [Mo^IVO(S₂C₂(CN)₂)₂]²⁻ (2) mimick oxidoreductase enzymatic activities of sulphite oxidase with biological electron donor, SO ₃ ²⁻ , andin vitro electron acceptor, [Fe(CN)₆]³⁻, demonstrating proton coupled electron transfer reaction in water and inhibition of the oxidation of (2) in the presence of KCN. The sulphite exidizing system is characterized by substrate saturation kinetics indicating the biological significance of the reactions