An improved error bound for a finite element approximation of a model for phase separation of a multi-component alloy

Using the approach of Rulla (1996 SIAM J. Numer. Anal. 33, 68-87)for analysing the time discretization error and assuming moreregularity on the initial data, we improve on the error boundderived by Barrett and Blowey (1996 IMA J. Numer. Anal. 16,257-287) for a fully practical piecewise linear finite elementapproximation with a backward Euler time discretization of amodel for phase separation of a multi-component alloy.     

Excess molar volumes and enthalpies for the binary systems propyl propanoate + o-xylene, m-xylene, and p-xylene at 298.15 K

This paper reports excess molar enthalpies, H_m^E, and excess molar volumes, V_m^E, of the binary systems {propyl propanoate + o-xylene}, {propyl propanoate + m-xylene} and {propyl propanoate + p-xylene} at the temperature 298.15 K and atmospheric pressure, over the whole composition range. V_m^E was calculated from the experimental measurement of the corresponding densities, while H_m^E was measured directly. The excess magnitudes were correlated to a Redlich-Kister type equation. Finally, we will discuss the results of the three mixtures studied here and by comparison with other binary systems containing propyl propanoate and a benzene-based compound previously published.     

New progesterone esters as 5alpha-reductase inhibitors

The pharmacological activity of four new progesterone derivatives: 4-bromo-17alpha-(p-fluorobenzoyloxy)-4-pregnene-3,20-dione (7), 4-bromo-17alpha-(p-bromobenzoyloxy)-4-pregnene-3,20-dione (8), 4-bromo-17alpha-(p-chlorobenzoyloxy)-pregnene-3,20-dione (9) and 4-bromo-17alpha-(p-toluoyloxy)-4-pregnene-3,20-dione (10) was determined. These compounds were evaluated as 5alpha-reductase inhibitors on gonadectomized hamster seminal vesicles and flank organs. The pharmacological data of this study indicate that compounds 7 and 9 having at C-17 p-fluorobenzoyloxy and p-chlorobenzoyloxy ester functions respectively showed the highest antiandrogenic effect as measured by the reduction of the weight of the seminal vesicles. In the flank organ model, the same compounds 7 and 9 exhibited a smaller diameter, 1.8 and 1.0 mm, respectively, than the commercially available finasteride 3 (2.3 mm), thus indicating a higher inhibitory effect on 5alpha-reductase enzyme. Steroid 7 showed a higher inhibitory activity on the conversion of T to DHT (Fig. 3) than the presently used finasteride, thus indicating a higher antiandrogenic effect. The nonsubstituted benzoyloxy ester (compound 15) showed a lower antiandrogenic activity as measured in the seminal vesicles model than the p-substituted benzoyloxy compounds.     

5 Alpha-reductase inhibitory and antiandrogenic activities of novel steroids in hamster seminal vesicles

The pharmacological activity of several 16-bromosubstituted trienediones 4 and 5, 16-methyl substituted dienediones 6 and 7 and the 16-methyl substituted trienedione 8 was determined on gonadectomized hamster seminal vesicles by measuring the in vitro conversion of testosterone (T) to dihydrotestosterone (DHT) as 5alpha-reductase inhibitors and also the ability of these steroids to bind to the androgen receptor. Steroids 6 and 7 when injected together with T decreased the weight of the seminal vesicles thus showing an antiandrogenic effect. Compounds 5 and 6 reduced substantially the conversion of T to DHT and therefore can be considered good inhibitors for the enzyme 5alpha-reductase; however both steroids failed to form a complex with the androgen receptor. On the other hand compound 7 which showed a very small inhibitory activity for the enzyme 5alpha-reductase, exhibited a very high affinity for the androgen receptor and thus can be considered an effective antiandrogen. This compound also reduced substantially the weight of the seminal vesicles. Steroids 4 and 8 did not reduce the weight of the seminal vesicles and exhibited a low affinity for the androgen receptor; 8 showed a weak 5alpha-reductase inhibitory activity, whereas 4 exhibited a weak androgenic effect.     

Crystal Structure and Synthesis of 17α-Acetoxy-pregn-4,6-diene-3,20-dione

Abstract  

17α-Acetoxy-pregn-4,6-diene-3,20-dione (1), C₂₃H₃₀O₄, was synthesized from the commercially available 17α-acetoxyprogesterone. X-ray diffraction analysis of (1) demonstrated that it consists of four rings, three six-membered rings (A, B and C) and one-five-membered ring (D). A, B, C and D rings occur in an envelope; half chair and chair; and half chair conformations, respectively. The crystal of 17α-acetoxy-pregn-4,6-diene-3,20-dione is in orthorhombic crystal system with space group P2₁2₁2₁, lattice constants: a = 10.843(1), b = 11.744(1), c = 15.815(2)?, V = 2013.9(4)?³, Dx = 1.222 g/cm³ and Z = 4. The molecules in the crystal are stabilized by C–H···O interactions and van der Waals forces.     

Role of Van der Waals Forces in Graphene Adsorption over Pd, Pt, and Ni

We report ab initio computations with the Vienna Ab initio Simulation Package (VASP) aimed at elucidating the adsorption mechanism of graphene-like structures on (111) Pd, Pt, and Ni surfaces. To study the adsorption properties, we simulate an already-formed graphene layer. We present a comparative discussion of the graphene interactions with the three metals, focusing on the very particular adsorption of graphene over Pd.     

Reactions of Late First-Row Transition Metal (Fe-Zn) Dichlorides with a PGeP Pincer Germylene

The reactivity of the PGeP germylene 2,2’-bis(di-isopropylphosphanylmethyl)-5,5’-dimethyldipyrromethane-1,1’-diylgermanium(II), Ge(pyrmPiPr₂)₂CMe₂, with late first-row transition metal (Fe-Zn) dichlorides has been investigated. All reactions led to PGeP pincer chloridogermyl complexes. The reactions with FeCl₂ and CoCl₂ afforded paramagnetic square planar complexes of formula [MCl{κ³P,Ge,P-GeCl(pyrmPiPr₂)₂CMe₂}] (M=Fe, Co). While the iron complex maintained an intermediate spin state (S¹; μ_eff=3.0 μ_B) over the temperature range 50–380 K, the effective magnetic moment of the cobalt complex varied linearly with temperature from 1.9 μ_B at 10 K to 3.6 μ_B at 380 K, indicating a spin crossover behavior that involves S^1/2 (predominant at T<180 K) and S^3/2 (predominant at T>200 K) species. Both cobalt(II) species were detected by electron paramagnetic resonance at T<20 K. The reaction of Ge(pyrmPiPr₂)₂CMe₂ with [NiCl₂(dme)] (dme=dimethoxyethane) gave a square planar nickel(II) complex, [NiCl{κ³P,Ge,P-GeCl(pyrmPiPr₂)₂CMe₂}], whereas the reaction with CuCl₂ involved a redox process that rendered a mixture of the germanium(IV) compound GeCl₂(pyrmPiPr₂)₂CMe₂ and a binuclear copper(I) complex, [Cu₂{μ-κ³P,Ge,P-GeCl(pyrmPiPr₂)₂CMe₂}₂], whose metal atoms are in tetrahedral environments. The reaction of the germylene with ZnCl₂ led to the tetrahedral derivative [ZnCl{κ³P,Ge,P-GeCl(pyrmPiPr₂)₂CMe₂}].