Direct calculation of time varying Aharonov-Bohm effect

The Aharonov-Bohm effect (ABE) for steady magnetic fields is a well known phenomenon. However, if the current in the infinite solenoid that creates the magnetic field is time-dependent, that is in the presence of both magnetic and electric fields, there is no agreement whether the effect would be present. In this note, we try to investigate time varying ABE by a direct calculation in a set-up with a weak time dependent magnetic field. We find that the electric field arising out of the time-varying magnetic field in the path of the electrons does not enter the action integral but only changes the path of the electron from the source to the slits and then on to the detector. We find a frequency dependent AB phase shift. At low frequencies the result smoothly approaches the one for a constant field as the frequency tends towards zero. On the other hand, for high frequencies such that the AB-phase induced in the path of the wave packet oscillates rapidly, the net effect will be very small which is borne out by our results.     

Calibration Curve with Improved Limit of Detection for Cadmium in Soil: An Approach to Minimize the Matrix Effect in Laser-Induced Breakdown Spectroscopic Analysis

The present article describes a working or combined calibration curve in laser-induced breakdown spectroscopic analysis, which is the cumulative result of the calibration curves obtained from neutral and singly ionized atomic emission spectral lines. This working calibration curve reduces the effect of change in matrix between different zone soils and certified soil samples because it includes both the species' (neutral and singly ionized) concentration of the element of interest. The limit of detection using a working calibration curve is found better as compared to its constituent calibration curves (i.e., individual calibration curves). The quantitative results obtained using the working calibration curve is in better agreement with the result of inductively coupled plasma–atomic emission spectroscopy as compared to the result obtained using its constituent calibration curves.     

Infrared emissions, visible up-conversion, thermoluminescence and defect centres in Er3Al5O12 phosphor obtained by solution combustion reaction

The Er₃Al₅O₁₂ phosphor powders were prepared using the solution combustion method. Formation and homogeneity of the Er₃Al₅O₁₂ phosphor powders have been verified by X-ray diffraction and energy-dispersive X-ray analysis respectively. The frequency up-conversion from Er₃Al₅O₁₂ phosphor powder corresponding to the ²H_9/2 → ⁴I_15/2, ²H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2, ⁴F_9/2 → ⁴I_15/2 and the infrared emission (IR) due to the ⁴I_13/2 → ⁴I_15/2 transitions lying at ∼410, ∼524, ∼556, 645–680 nm and at ∼1.53 μm respectively upon excitation with a Ti-Sapphire pulsed/CW laser have been reported. The mechanism responsible for the frequency up-conversion and IR emission is discussed in detail. Defect centres induced by radiation were studied using the techniques of thermoluminescence and electron spin resonance. A single glow peak at 430°C is observed and the thermoluminescence results show the presence of a defect center which decays at high temperature. Electron spin resonance studies indicate a center characterized by a g-factor equal to 2.0056 and it is observed that this center is not related to the thermoluminescence peak. A negligibly small concentration of cation and anion vacancies appears to be present in the phosphor in accordance with the earlier theoretical predictions.     

An Efficient Synthesis of 1,5-Thiadiazepines and 1,5-Benzodiazepines by Microwave-Assisted Heterocyclization

A novel and efficient method for the synthesis of substituted thiazepines and diazepines has been developed. A simple one-pot reaction of chalcones 1a–f with 1-amino-2-mercapto-5-phenyl-1,3,4-triazole and o-phenylenediamine in the presence of a catalytic amount of sodium acetate under microwave irradiation gave 2-(3,8-diphenyl-7,8-dihydro[1,2,4]triazolo[3,4-b][1,3,4]thiadiazepin-6-yl)phenoles 2a–f and 2-(2-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)phenoles 3a–f, respectively. The structure of all the synthesized compounds was elucidated on the basis of elemental analysis, IR, ¹H and ¹³C NMR, and mass spectral data.