Abdul Al Mortuza

In this study, we have synthesized pristine and [0.5,1.5, and 2.5] M% samarium (Sm)-incorporating α-MoO₃2D-layered nanoplates utilizing a facile hydrothermal process, and investigated the physical properties along with antibacterial effectiveness.

High energy external gamma radiation has always an impact on semiconductor material by altering its physico-chemical properties. In this paper, the effect of gamma-radiation is observed on sol-gel synthesized metastable h-MoO₃ nanorods with absorbed dose variation. The irradiated sample shows a remarkable change in their structural parameters such as average crystallite size decreased, strain, and dislocation density increased and so on are confirmed from the x-ray diffraction (XRD). Functional groups and the corresponding vibration and stretching are analyzed from the Fourier transform infrared spectroscopy (FTIR). The change in surface morphology is observed from the field emission scanning electron microscopy (FESEM) image and found no remarkable change. However, the optical band gap decreases with increasing absorbed dose and calculated 2.84 eV, 2.82 eV, 2.80 eV and 2.77 eV for 0 kGy, 40 kGy, 80 kGy, and 120 kGy, respectively by Kubelka-Munk (K-M) function from the diffuse reflectance data of UV–vis-NIR spectrophotometer.

Efficiency of dye-sensitized solar cell (DSSC) depends on several interrelated factors such as type and concentration of dye, type and thickness of photoelectrode and counter electrode. Optimized combination of these factors leads to a more efficient cell. This paper presents the effect of these parameters on cell efficiency. TiO₂nanoporous thin films of different thicknesses (5 μm to 25 μm) were fabricated on indium doped tin oxide (ITO) coated glass by doctor blading method and characterized by inverted microscope, stylus surface profiler and scanning electron microscope (SEM). Natural organic dye of different concentrations, extracted from turmeric, was prepared with ethanol solvent. Different combinations of dye concentrations and film thicknesses along with different types of carbon catalyst have been investigated by I-V characterization. The result shows that the cell made of a counter electrode catalyst material prepared by candle flame carbon combined with about 15 μm thick photoelectrode and 100 mg/mL dye in ethanol solvent, achieves the highest efficiency of 0.45 %, with open circuit voltage of 566 mV and short circuit current density of 1.02 mA/cm².

A Pico-ammeter has versatile application in the measurement of low current of nuclear detector, biological cell or tissues and to know the character of new electronic devices. But noise can be generated due to some internal and external sources such as, poor design, placement of ammeter, dust, humidity, bending of connecting wires and even the selection of electronic devices, thus the measurement goes tricky. Several design techniques, guarding, shielding, and an unconventional wiring technique can help to measure low current accurately by reducing noise. This paper describes this low current measurement problems in detail and their corresponding solutions. It also shows the comparison of different low current measurement systems (LCMS). Feedback type ammeters are more preferable than shunt ammeter and current conveyor technique. In operational amplifier selection, CMOS type op-amp is better than BJT and FET.

Zinc oxide thin films with different thicknesses were prepared on microscopic glass slides by sol-gel spin coating method, then hydrothermal process was applied to produce zinc oxide nanorod arrays. The nanorod thin films were characterized by various spectroscopic methods of analysis. From the images of field emission scanning electron microscope (FESEM), it was observed that for the film thickness up to 200 nm the formed nanorods with wurtzite hexagonal structure were uniformly distributed over the entire surface substrate. From X-ray diffraction analysis it was revealed that the thin films had good polycrystalline nature with highly preferred c-axis orientation along (0 0 2) plane. The optical characterization done by UV-Vis spectrometer showed that all the films had high transparency of 83 % to 96 % in the visible region and sharp cut off at ultraviolet region of electromagnetic spectrum. The band gap of the films decreased as their thickness increased. Energy dispersive X-ray spectroscopy (EDS) showed the presence of zinc and oxygen elements in the films and Fourier transform infrared spectroscopy (FT-IR) revealed the chemical composition of ZnO in the film.

A Conventional progressive scanning method can be used for small and medium size LED (Light Emitting Diode) dot-matrix display board. However, this conventional scanning approach has some drawbacks such as flicker, lower luminous intensity, requirement of high speed LED driver, etc., specifically for large LED dot-matrix display. This paper brings forward the analysis of scanning method clarifying the limitations of conventional scanning approach with several critical design parameters. After that, a new scanning approach, congenial to both small and large has been proposed to get over these limitations. Eventually, simulation of the mathematical models of the two methods are expounded that points to the vital design parameters constraints along with the advantages of new method. The mathematical models and analyses give understanding of system design approach to the LED driver circuit designers to estimate various design parameters.

Passivation of porous silicon (PS) by LaF3 by a novel chemical-bath technique has been investigated in this report. The porous silicon surface has been passivated with LaF3 by reacting LaCl3 with HF in the etching chamb er at roo m temperature. Without removing the porous silicon fro m the anodizing chamber LaF3 as a result of chemical reaction between LaCl3 and HF was allowed to passivate the PS surface. Several cycles of reaction that gives the various thickness of LaF3 layer on PS have been investigated. The Scanning Electron Microscopy (SEM) on the surface of LaF3/ PS/Si structure confirms the LaF3 film deposition on PS layer. The X-ray diffraction (XRD) of the deposited layer revealed a hexagonal nanocrystalline LaF3 deposition. The as-deposited thin (10-cycle) LaF3 layer contained very low concentration of lanthanum (La) and fluorine (F). The concentration of La and F started increasing with the increase in reaction cycle. But the photoluminescence (PL) of as deposited-LaF3 passivated PS was lower than that of fresh PS. Annealing the just passivated PS structure recovered the PL intensity. Experimental results show that the optimized chemical bath passivation process for the LaF3 on porous silicon could enable the porous silicon to be an important material for photonic application.