New stigmatic mounting of holographiccylindrical diffraction grating

A new stigmatic mounting of a holographic cylindrical diffraction grating has been considered to be used in the field of X-ray and XUV regions. The conditions for zero astigmatism and sagittal coma have been obtained. Astigmatism per unit length has been plotted against wavelength using the design parameters which give zero astigmatism at least at one wavelength.     

Microwave Activated Solid Support Synthesis of New Antibacterial Quinolones

 A novel synthesis of 6-fluoro-7-(5-aryl-1,3,4-thiadiazol/oxadiazol-2-yl-sulfanyl)-4-quinolone-3-carboxylic acids from 7-chloro-6-fluoro-4-quinolone-3-carboxylic acid and 5-substituted 1,3,4-thiadiazoles/oxadiazoles on basic alumina under microwave activation is described. All compounds were screened for their in vitro antibacterial activity against B. lichenformis, 2689, K. aerogens 2281, S. typhimurium 2501, E. herbicola 2491, and P. vulgaris 2027 and found to possess activities comparable to that of the standard drug norfloxacin.     

TLC Based Method for Standardization of Pongamia pinnata (Karanj) Using Karanjin as Marker

Pongamia pinnata Linn. (Papilionaceae) seeds have gained great commercial and industrial importance owing to their high oil content. Presently, there is no appropriate TLC based method available for standardization of P. pinnata. A simple, robust and reproducible TLC method for the determination of Karanjin is reported in the seeds of P. pinnata. The method involves separation of components by TLC on pre-coated silica gel G 60 F₂₅₄ plates developed on toluene: ethyl acetate (7:3 v/v) and detection at 260 nm in absorbance mode. The sensitivity of the method was found to be 100 ng. The linearity range was 50–300 ng. Four samples of P. pinnata from different geographical locations were tested for their karanjin content using the developed method. The proposed method was found to be robust, precise, and accurate, it therefore holds potential for detection, monitoring and quantification of karanjin in Pongamia pinnata.

     

Systematic investigation of hexadecapole collectivity in even-even nuclei

Energies of the first 2⁺, 3⁻ and 4⁺ states of even-even nuclei are plotted against proton and neutron number. Using this systematics, shell effects and the corresponding quadrupole and hexadecapole collectivity and deformation effects are compared and contrasted. Also, the correspondingB(E2),B(E3) andB(E4) values are plotted against neutron number and their very different systematics compared. Among the new results are the presence of hexadecapole collectivity at the 82 proton and neutron closed shells and the presence of the maximum values ofB(E4) at neutron numbers 10, 90–92 and 140–146. Finally, the systematics of the hexadecapole (K=4⁺) vibrations is compared with that of the quadrupole (K=2⁺) gamma vibrations in the quadrupole deformed rare earth region. This research has been supported by the National Sciences and Engineering Research Council of Canada at McMaster University and by the Department of Atomic Energy, Government of India, at Banaras Hindu University.     

Study of thermal lensing effects in a copper vapor laser

The thermal lensing effect of the Copper Vapor Laser (CVL) was studied by considering both its windows and the active medium. The equivalent combined focal length of the active medium and windows was measured to be 52 mts under operating conditions for a 35W CVL. The variation of focal length with the operating parameters was studied.     

Low temperature magnetic properties of Cr0.25Co0.25Zn0.5Fe2O4 nano particles

Low temperature Mössbauer and AC susceptibility have been used to study relaxation phenomena in nano-sized particles of Cr_0.25Co_0.25Zn_0.5Fe₂O₄. From these studies, the energy density constant for this system has been estimated to be 4 x 10⁶ erg/cm³. Cation distribution has also been determined and the observed results are correlated to calculated relaxation times.     

Synthesis of novel spiroazetidinones by selective lactam‐carbonyl cleavage in 1‐aryl/cyclohexyl‐3,3‐diphenyl‐1′‐(diphenylacetyl)spiro[azetidin‐2,3′‐indoline]‐2′,4‐diones

Titled compounds undergo selective N‐C cleavage on treatment with sodium hydroxide in ethanol affording a series of novel isatin‐based spiroazetidinones.     

X-ray photoelectron spectroscopy of boron implanted 4145 steel surface

The near-surface region of 4145 steel following boron implantation was investigated by x-ray photoelectron spectroscopy (XPS). The steel surface was implanted with¹¹B⁺ ions to a constant dose of 1.0×10¹⁷ ions cm^–2 at energies of 30 and 135 keV. The XPS spectrum of the implanted surface showed a shift in the B(1s) level towards the higher binding energy. The observed 188.0 eV binding energy of the B(1s) level was found to be in good agreement with the characteristic binding energy of the B(1s) level corresponding to iron boride (Fe₂B). Hence the increase in surface hardness reported previously is related to the formation of an iron boride layer in the near-surface region known for its hardening capabilities.     

Quasi-invariants and generalized Killing vectors-II

We consider here the problem of the existence of a quasi-invariant which is linear in the momenta for Hamiltonians in three degrees of freedom. We show that such quasi-invariants are more constrained in their structure than in the two degrees of freedom case. We also show that some of these quasi-invariants have to be interpreted as ‘pseudo-translations’, i.e., as translations in a non-orthogonal system of coordinates.     

Brans-Dicke cosmological exact solution in a radiation-filled Robertson-Walker universe

Considering a Robertson-Walker line element, exact solutions are obtained for radiation-filled cosmological differential equations of Brans-Dicke theory with the assumption that the radius of curvatureQ of the universe varies directly as thenth power of time. The solution is found to be valid for closed space only and the coupling constantw of the scalar tensor theory is necessarily negative. The radius of curvature of increases linearly with respect to the age of the universe, while the gravitational constantk varies directly as the square of the radius of the universe. The solution obtained is in contradiction to Dirac's hypothesis, in which the gravitational constant should decrease with time in an expanding universe.