Simultaneous K plus L shell ionized atoms during heavy-ion collision process

The fraction of simultaneous K plus L shell ionized atoms is estimated in Fe, Co and Cu elements using carbon ions at different projectile energies. The present results indicate that the fraction of simultaneous K plus L shell ionization probability decreases with increase in projectile energy as well as with increase in the atomic number of the targets atoms.     

Using metallic interlayers to stabilize abrupt,epitaxial metal-metal interfaces

An approach is described for stabilizing metal-metal epitaxial interfaces using a thin metallic interlayer. Rutherford backscattering and channeling techniques along with low-energy electron diffraction and keV He+ ion backscattering are used to demonstrate that an atomically thin layer of Ti deposited at the Fe-Al interface, a system well known for considerable intermixing at room temperature, forms a thin interface alloy that prevents interdiffusion and improves epitaxial growth of Fe on Al(100). The structure is stable up to about 200 degrees C.     

Isothermal flow behind a shock wave propagating in the solar wind

A Parker-type blast wave, which is headed by a strong shock, driven out by a propelling contact surface, moving into an ambient solar wind having a strictly inverse square law radial decay in density, is studied. Assuming the self-similar flow behind the shock to be isothermal, approximate analytical and exact numerical solutions are obtained. There is a good agreement between the approximate analytical and exact numerical solutions. It is observed that the mathematical singularity in density at the contact surface is removed for the isothermal flow.     

Ortho effects in organic molecules on electron impact. IV—Ortho interaction of the carboxyl group with the olefinic bond in substituted benzoic acids

Fragments ions involving hydrogen migration from the –COOH group to the olefinic bond in the mass spectra of stilbene-2-carboxylic acid and ortho-carboxylbenzalaniline are discussed.     

Ortho effects in organic molecules on electron impact. V—ortho effects of the nitro group in n-substituted anilines

Some very interesting ortho effects are observed in the mass spectra of N-benzyl-o-nitroaniline and N,N-dibenzyl-2,4-dinitroaniline. Fragment ions arising from the transfer of oxygen from the nitro group to the benzylic carbon are seen in these spectra.     

A search for heavy leptons in cosmic radiation underground

An experiment to search massive long-lived, weakly interacting particles (leptons) in cosmic radiation has been conducted at Kolar Gold Fields at a depth of 7.6 hg cm⁻² (1 hg cm⁻²=100 g cm⁻²) below surface. The apparatus was senstive to sub-relativistic (velocity<0.75 c) charged leptons of mass greater than that of a proton and life times greater than a microsecond. The method consists of selecting charged particles using a scintillator counter telescope and vetoing relativistic particles (velocity >0.75 c) by using a water Čerenkov detector. The range of the particle is observed in arrays of neon flash tubes interspersed with iron absorbers. During 3000 hours of observation 28 events were recorded satisfying the trigger and event selection criteria. Bulk of these events were interpreted as due to recoil protons (low energy) from the inelastic scattering of high energy muons in the overhead absorber. The remaining events were interpreted as either atmospheric stopping protons or stopping muons that failed to generate a Čerenkov signal. The observed events are thus consistent with the background and no heavy leptons were seen. From our observations an upper limit of 2.12×10⁻⁷ (with 90% confidence level) is set on the ratio of the flux of heavy leptons to that of all muons at this depth.     

Toward a synthesis of the antitumor macrolide peloruside A: a chiral pool approach for the C(1)-C(11) segment

Dihydroxylation of the glucose derived α,β-unsaturated lactones 6 and 13 was found to be on the α-face of the pyranolactone ring exclusively. The resulting dihydroxylated compound from 13 has been used in a synthesis of the lactone 4, which corresponds to C(1)-C(11) of peloruside A.     

Studies on the reactivity of new types of tetracyclic‐1,5‐benzoxazepines: Part V

The syntheses of tetracyclic 1,5‐benzoxazepines 3a‐e from heterocyclic (3‐chloroaldehydes 1a‐e and 2‐aminophenol are reported herein (Scheme I). Attempted lithium aluminium hydride (LiAlH₄) reduction of the imine double bond in 3a‐e failed to furnish the corresponding saturated compounds 5a‐e. Attempted catalytic hydrogenation of 3a‐e in the presence of acetic acid and acetic anhydride gave surprisingly only the acetoxy derivatives 6a‐e in high yields (Scheme II). Base catalysed hydrolysis of acetoxy derivatives 6a‐e furnished, as expected, the corresponding phenolic derivatives 7a‐e , in moderate yields. Attempted cyclofunctionalization of 3a‐e either with mercaptoacetic acid or its methyl ester to obtain the new penta‐cyclic heterocycles 4a‐e was, however, not successful.