Evidences for magicity in superdeformed shapes

Many empirical evidences that point to the existence of preferred magic nucleon numbers for superdeformed (SD) shapes are presented in this paper. We use a simple premise based on the 4-parameter formula fitted using observed γ-rays of SD bands. In particular, plots of γ-ray energy ratios, nuclear softness parameter values and the number of SD bands for given N and Z are used to pinpoint the magicity (N, Z numbers) that are most favoured as the SD magic numbers. This analysis also leads to several new predictions on the occurrence of SD bands specially in neutron-rich nuclei.     

ON SELECTIVE HARVESTING OF TWO COMPETING FISH SPECIES IN THE PRESENCE OF ENVIRONMENTAL FLUCTUATION

ABSTRACT. The present paper deals with a problem of selective harvesting of two competing fish species in a randomly fluctuating environment. The environmental parameters are assumed to be perturbed by white noise characterized by a Gaussian distribution with mean zero and unit spectral density. The dynamic behavior of the stochastic system is studied and the fluctuations in population are measured both analytically and numerically by computer simulation.     

An efficient approach for the synthesis of novel methyl sulfones in acetic acid medium and evaluation of antimicrobial activity

A series of nine methyl sulphones ( 3a –3 i ) starting from the aldehydes ( 1a–1i ) were synthesized in two consecutive steps. In the first step, preparation of allyl alcohols ( 2a–2i ) from their corresponding aldehydes by the reaction of sodium borohydride in methanol at room temperature is reported. Finally, methyl sulphones are synthesized by condensing sodium methyl sulfinates with allyl alcohols in the presence of BF ₃ .Et ₂ O in acetic acid medium at room temperature for about 2–3 h. The reaction conditions are simple, yields are high (85%–95%), and the products were obtained with good purity. All the synthesized compounds were characterized by their ¹ H, ¹³ C NMR, and mass spectral analysis. All the title compounds were screened for antimicrobial activity. Among the compounds tested, the compound 3f has inhibited both Gram positive and Gram negative bacteria effectively and compound 3i has shown potent antifungal activity. These promising components may help to develop more potent drugs in the near future for the treatment of bacterial and fungal infections.     

Size-independent peak shift between normal and upconversion photoluminescence in MPA-capped CdTe nanoparticles

In this article, we report size-dependent measurement of the shift in peak of upconversion photoluminescence spectra compared to that of normal photoluminescence using a 800 nm femtosecond laser and its second harmonic. It has been shown that the upconversion photoluminescence is always red-shifted compared to that of normal PL in all the samples. By measuring the power-dependent upconversion photoluminescence (UCPL), it has been shown that the origin of UCPL from MPA-capped CdTe nanoparticles is mainly of two-photon absorption     

Thermal birefringence-compensated linear intracavity frequency doubled Nd:YAG rod laser with 73 ns pulse duration and 160 W green output power

In a thermally birefringence-compensated linear cavity configuration, ～160 W of average green power by intracavity frequency doubling of AO Q-switched Nd:YAG/LBO-based laser is demonstrated. The corresponding optical to optical conversion efficiency is estimated to be ～ 12.7%. The pulse repetition rate is 20 kHz with the individual pulse duration of 73 ns. The beam quality parameter is measured to be 18.     

Cold beam of isotopically pure Yb atoms by deflection using 1D-optical molasses

We demonstrate the generation of an isotopically pure beam of laser-cooled Yb atoms by deflection using 1D-optical molasses. Atoms in a collimated thermal beam are first slowed using a Zeeman slower. They are then subjected to a pair of molasses beams inclined at 45^° with respect to the slowed atomic beam. The slowed atoms are deflected and probed at a distance of 160 mm. We demonstrate the selective deflection of the bosonic isotope ¹⁷⁴Yb and the fermionic isotope ¹⁷¹Yb. Using a transient measurement after the molasses beams are turned on, we find a longitudinal temperature of 41 mK.     

Measurement of copper vapour laser-induced deformation of dielectric-coated mirror surface by Michelson interferometer

A Michelson interferometer-based technique has been used to measure the deformation of dielectric-coated mirror, caused by an incident repetitive pulsed laser beam with high average power. Minimum measurable deformation of 17 nm is reported.     

Tunable third-harmonic probe for non-degenerate ultrafast pump–probe measurements

In this article, we report a method to achieve a precisely tunable highly stable probe beam generation for performing pump–probe experiment around a given wavelength by tilting a sum frequency generation (SFG) crystal angle. The width of the generated third-harmonic beam is of the order of 2 nm throughout the tunable range. This method of probe beam generation has its application in isolating contributions from closely separated excitation states.