First excited 0+ states in the germanium isotopes via the Se(d, 6Li) reaction

A systematic study of the even-A germanium isotopes with mass 70 ≦ A ≦ 78 via the Se(d, ⁶Li) reaction has been performed at E_d = 45 MeV. The reaction products were momentum analysed and mass identified with a QMG/2 magnetic spectrograph and the accompanying focal-plane detector system. The main emphasis of this investigation was on the nature of the first excited 0⁺ states. The striking variation in strength from one isotope to the other already observed in the (p, t) reactions to the same final nuclei is also seen for the α-pickup reaction. Previously derived wave functions that assume the excited 0⁺₂ states to be pure proton configuration states can also account for the present results.     

Instrumented tensile-impact tests of bone

An instrumented pendulum-type impact tester was used to obtain tensile-impact properties for compact bone. Load-time histories throughout impact were recorded. Impact tests on 50 longitudinally oriented fresh-beef-bone samples yielded a proportional limit of 9.6±4.1 ksi (66.2±28.2 MPa), an ultimate stress of 17.6±5.3 ksi (121.3±36.5 MPa) and an energy-absorption capacity of 142±85 in. Ib/in.² (24900±14900 J/m²). A static tensile strength of 14.7±2.8 ksi (101±19 MPa) was obtained from static testing of 24 additional specimens. The tensile-impact strength was 20 percent higher than the static strength. Statistically significant correlations between elastic properties, impact strength and impact energy were found. Bone microstructure and fracture-surface topography were also examined.     

On construction and uses of balancedn-ary designs

Summary Methods of construction of balancedn-ary designs using difference sets have been studied in this paper. Some properties of balancedn-ary designs are studied. Use of balanced ternary designs has been made to construct some efficient weighing designs. Institute of Agricultural Research Statistics     

Functionalized proline with double hydrogen bonding potential: highly enantioselective Michael addition of carbonyl compounds to β-nitrostyrenes in brine

Simple synthetic manipulation of S-proline allows access to prolinamides 5-7 as organocatalysts capable of double hydrogen bonding for enantioselective Michael addition reactions of carbonyl compounds to β-nitrostyrenes. It is shown that prolinamide catalyst 7 leads to addition products with a high diastereo- as well as enantioselectivity. The transition state structure involving the binding of electrophilic nitrostyrene via two H-bonds is believed to be further stabilized by π,π stacking interactions mediated by the tosyl ring.     

Solvent-dependent aggregation behavior of a new Ru(II)-polypyridyl based metallosurfactant

Variation of the solvent polarity leads to the formation of vesicles and reverse vesicles of a newly synthesized amphiphilic Ru(II)-polypyridyl complex.     

Synthesis of cationic quantum dots via a two-step ligand exchange process

A new class of quaternary ammonium derivatives has been used to synthesize cationic CdSe/ZnS quantum dots with exceptional stability in water as well as in biological media.     

Observation of enhanced orbital electron-capture nuclear decay rate in a compact medium

The eigenstate energies of an atom increase under spatial confinement and this effect should increase the electron density of the orbital electrons at the nucleus thus increasing the decay rate of an electron capturing radioactive nucleus. We have observed that the orbital electron capture rates of ¹⁰⁹In and ¹¹⁰Sn increased by (1.00±0.17)%$(1.00\pm 0.17)\mathrm{\%}$ and (0.48±0.25)%$(0.48\pm 0.25)\mathrm{\%}$ respectively when implanted in the smaller Au lattice compared to implantation in a larger Pb lattice. These observations are interpreted to be a result of the higher compression experienced by the large radioactive atoms in the smaller spatial confinement of the Au lattice.     

Gram level synthesis of lead-free solder in the nanometer length scale obtained from tin and silver compounds using silicone oil

A straightforward route to gram level synthesis of a pure phase of the Sn-Ag nanoalloy in an eutectic composition (Sn/Ag 96.5:3.5) in silicone oil is reported. The composition, morphology, and microstructure of the alloy were fully characterized. In a mixture of ethylene glycol and silicone oil, direct reduction of Sn(II) acetate and Ag(I) nitrate gave the Sn-Ag nanoalloy. The nanoalloy disintegrates by sonication and reforms by heating, leading to smaller particles with a melting point as low as 128 degrees C.     

Ligand tuning in asymmetric hydrovinylation of 1,3-dienes: a stereoselective route to either steroid-C20 (S) or -C20 (R) derivatives

1,3-Dienes derived from steroidal D-ring C 17-ketones undergo Ni(II)-catalyzed hydrovinylation to give 1,2- or 1,4-addition of ethylene. Using finely tuned phosphoramidite ligands, it is possible to synthesize either the C 20 ( R)- or ( S)-derivatives without mutual contamination. The proportion of the 1,4-adduct, which is also formed stereoselectively, can be minimized by optimizing the reaction conditions. Because the two alkenes in the resultant dienes have differing steric demands for many potential reactions, and are ideally juxtaposed for further D-ring functionalization, these intermediates could be useful for the preparation of biologically important compounds such as vitamin D analogs and various antitumor steroidal glycosides.     

Micellar shape transition under dilute salt-free conditions: promotion and self-fluorescence monitoring of stimuli-responsive viscoelasticity by 1- and 2-naphthols

Effect of 1 and 2-naphthols on the shape transition of cetyl trimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) micelles are studied. Stimuli-responsive viscoelastic gels of long wormlike micelles are formed at low surfactant concentrations in the presence of neutral naphthols, where H-bonding plays a key role in micellar shape transition in the absence of any charge screening. Micelle-embedded naphthols also act as novel self-fluorescence probes for monitoring viscoelasticity of the system as a function of applied shear. 1H NMR study shows that the solubilization sites of naphthols in the micelle are located near the surface. While UV absorption and Fourier transform infrared studies confirm the presence of intermolecular H-bonds in micelle embedded naphthols, transmission electron micrographs of vacuum-dried samples at room temperature demonstrate the transition in shape from sphere to rodlike micelles.