Calculation of average L shell fluorescence yields for the elements with 25≤Z≤101

Average L shell fluorescence yield , average L shell Auger yields and the total L shell X-ray fluorescence (LXRF) cross sections (σ _L ^x ) at 30 keV have been calculated theoretically for the elements with 25≤Z≤101. These calculated values have been compared with the other experimental and theoretical values.     

Investigation of Host–Guest Interactions in the Hofmann-daddn-type Clathrates: M(1,12-diaminododecane)Ni(CN) 4 .G (M = Co, Ni or Cd; G = toluene, m-xylene, o-xylene or p-xylene)

New Hofmann-diaminododecane-type clathrates of the form M(1,12-diaminododecane) Ni(CN)₄?G (M = Co, Ni or Cd; G = toluene, m-xylene, o-xylene or p-xylene) have been prepared in powder form and their infared spectra are reported. The spectral data suggest that the host–guest frame-works of these compounds are similar in structure to other Hofmann-diam-type clathrates.     

Stability issues of covalently and noncovalently bonded peptide subunits

The present study focuses on important questions associated with modeling of peptide and protein stability. Computing at different levels of theory (RHF, B3LYP) for a representative ensemble of conformers of di- and tripeptides of alanine, we found that the Gibbs Free Energy values correlate significantly with the total electronic energy of the molecules (0.922 < or = R2). For noncovalently attached but interacting peptide subunits, such as [For-NH2]2 or [For-L-Ala-NH2]2, we have found, as expected, that the basis set superimposition error (BSSE) is large in magnitude for small basis set but significantly smaller when larger basis sets [e.g., B3LYP/6-311++G(d,p)] are used. Stability of the two hydrogen bonds of antiparallel beta-pleated sheets were quantitatively determined as a function of the molecular structure, S10 and S14, computed as 4.0 +/- 0.5 and 8.1 +/- 1.1 kcal/mol, respectively. Finally, a suitable thermoneutral isodesmic reaction was introduced to scale both covalently and noncovalently attached peptide units onto a common stability scale. We found that a suitable isodesmic reaction can result in the total electronic energy as well as the Gibbs free energy of a molecule, from its "noninteracting" fragments, as accurate as a few tenths of a kcal per mol. The latter observation seems to hold for peptides regardless of their length (1 < or = n < or = 8) or the level of theory applied.     

Antiandrogenic effect of 16-substituted, non-substituted and D-homopregnane derivatives

The pharmacological activities of 12 pregnane derivatives (4-15) were determined on gonadectomized male hamster flank organs and seminal vesicles as antiandrogens and as 5alpha-reductase inhibitors. The results from this study indicate that subcutaneous injection of testosterone for 3 d increased the diameter of the pigmented spot in the flank organs, whereas finasteride when injected with testosterone decreased the size of the spot significantly when steroids 4-15 were injected together with testosterone, the diameter of the flank organs of gonadectomized male hamsters, decreased significantly (p<0.005) compared to testosterone. Compound 11 was the most active steroid and reduced the diameter of the pigmented spot more than the other synthesized steroids or finasteride. Subcutaneous injections of testosterone to gonadectomized animals restore the seminal vesicle size lost upon castration. Injection of testosterone plus finasteride decreased significantly the weight of these glands (p<0.005). Steroids 5-15 when injected with testosterone decreased the weight of the seminal vesicles compared to testosterone. Finasteride is a good inhibitor of the conversion of testosterone to dihydrotestosterone (DHT) (low formation of DHT) measured as pmole of DHT/g of protein/h. Steroids 6-15 inhibited the conversion of testosterone to DHT as compared to testosterone however finasteride and 10 appeared to be the most effective compounds. Castration increases the protein content of the seminal vesicles (control) expressed as microg/mg of tissues. Testosterone tends to decrease it significantly, as did compounds 4, 5, 7, 9, and 15. We demonstrated that DHT as well as cyproterone acetate and steroids 5, 6, 8, 9, 11, and 14 at increasing non radioactive steroid concentration, inhibited the binding of [3H]DHT to cytosolic androgen receptor (AR), as indicated by its Ki values. However, 4, 7, 10, 12, and 13 did not have any inhibitory effect.     

Trichloroacetylation of some cyclic enamines

The pyrrolidine and morpholine enamines of cyclic ketones such as cyclohexanone and cyclopentanone were successfully diacetylated at alpha- and alpha'-positions with trichloroacetyl chloride using zinc catalyst. Morpholine enamines of the cyclic ketones gave acetylated morpholine in good yields besides the corresponding diacetylated cyclic enamines. When the same reactions were performed by using triethylamine without using zinc, monoacetylation products of the same enamines were synthesized.     

The Equilibrium and Kinetic Modelling of the Biosorption of Copper(II) Ions on <Emphasis Type="Italic">Cladophora crispata</Emphasis>

The biosorption of Cu(II) ions on Cladophora crispata was investigated as a function of the initial pH, temperature and initial Cu(II) ion concentration. Algal biomass exhibited the highest Cu(II) uptake capacity at 25C and at the initial pH of 4.5. Equilibrium data fitted very well to both the Langmuir and Freundlich isotherm models. The pseudo second order kinetic model was applied to describe the kinetic data and the rate constants were evaluated in the studied concentration range of Cu(II) ions at all the temperatures studied. The experimental data fitted well to the pseudo second order kinetic model with a high correlation coefficient (R² > 0.99), which indicates that the external mass transfer limitations in the system can be neglected and the chemical sorption is the rate-limiting step. The pseudo second order kinetic constants were also used to calculate the activation energy of Cu(II) biosorption.     

Coupling of pentacarbonyl[(cyclopropyl)methoxymethylene]molybdenum complex with ferrocenyl alkynes: Synthesis of ferrocenyl-substituted cycloheptadienones and cycloheptenediones

Pentacarbonyl[(cyclopropyl)methoxymethylene]molybdenum complex reacts with ferrocenyl alkynes to afford ferrocenyl-substituted 2,4-cycloheptadienones as major products, accompanied by varying amounts of 2-cycloheptene-1,4-diones and/or 2-cyclobutenones. 2-Cycloheptene-1,4-diones are secondary reaction products and result from initially formed 2,4-cycloheptadienones via hydrolysis. In one reaction, a hydroxy-substituted 2,4-cycloheptadienone derivative was isolated, which was not observed previously from similar reactions.     

Kinetics and mechanisms of homogeneous catalytic reactions. Part 8. Regioselective reduction of benzo[ b ]thiophene catalyzed by OsH(CO)(κ3-OCOCH3)(PPh3)2

The complex OsH(CO)(κ³-OCOCH₃)(PPh₃)₂ (1) catalyzes the reduction of benzo[b]thiophene (BT) to 2,3-dihydrobenzo[b]thiophene (DHBT), under mild reaction conditions. A kinetic study lead to the rate law: r = K ₁ K ₂ k ₃ /{1 + K ₁ (1+K ₂ )[BT]}[Os][BT][H₂]. A catalytic cycle was proposed, which involves the oxidative addition of hydrogen as rate-determining step.     

An infrared and raman spectroscopic investigation of copper(II) tetracyanonickelate complexes ofα-,β- andγ-picoline

Copper(II) dipicoline tetracyanonickelate complexes, CuL₂Ni(CN)₄ (L=,- or-picoline), have been prepared for the first time and their infrared and Raman spectra are reported. Their structure consists of polymeric layers of {Cu-Ni(CN)₄} with picoline molecules bound directly to the copper. It is proposed that the Cu-NC bonds are in two nonequivalent pairs in trans positions. Low temperature (83K) IR spectra have also been recorded and it is noted that the Ni(CN)₄ group frequencies increase with decreasing temperature while the picoline frequencies are insensitive to temperature.