Journal of Applied Physical Science International

A NOVEL APPROACH OF PURE AND Ni2+, Ca2+ AND Mg2+ DOPED CERIA QUANTUM DOTS WITH ENHANCED PHOTOCATALYTIC ACTIVITY

V. MOHANA — 2019-11-19

Cerium oxide quantum dots are known to catalyze the decomposition of reactive oxygen species such as the superoxide radical and hydrogen peroxide. Herein, we examine the superoxide dismutase (SOD) of pure (CeO₂) and several transition metal ions (Ni²⁺, Ca²⁺ and Mg²⁺) doped CeO₂ quantum dots were synthesized using the sol-gel method in an air atmosphere. The systematically characterized to let on its structure, optical and photocatalytic properties were studied using various techniques. The X-ray diffraction (XRD) analysis indicates that the particles are in cubic structure. The mean size of the nanoparticles calculated through Scherrer equation is in the range of 6–13 nm. The absorption spectra of all the samples are blue shifted from the bulk ceria.The high photocatalytic efficiency was reached in all doped ceria quantum dots compared to pure ceria. Especially, Mg²⁺ doped ceria yielded higher photocatalytic efficiency compared to others.

ON PROGNOSIS OF GROWTH OF FILMS FROM GAS PHASE WITH ACCOUNT NATURAL CONVECTION AND CHANGES IN THE RATE OF CHEMICAL INTERACTION BETWEEN MATERIALS

E. L. PANKRATOV — 2019-10-04

In this paper, using the recently introduced analytical approach for the analysis of mass and heat transfer during film growth in reactors for epitaxy from the gas phase, these processes are analyzed taking into account natural convection and possibility of changing the rate of chemical interaction between reagents. As a result of the analysis the conditions under which the homogeneity of the grown epitaxial layers increases with a change in the values of the parameters of the growth process were formulated. Another actual result of this paper is development of analytical approach for prognosis of mass and heat transport with account spatial and temporal dependences of parameters of considered processes and at the same time with account their nonlinearity.

CRESCEIAALATA FLOWER EXTRACT AS REDUCING CATALYST FOR GREEN SYNTHESIS OF Au/Ag BIMETALLIC NANO MEDICINE AND ITS ANTIBACTERIAL ACTIVITIES

C. JEEVARATHINAM — 2019-11-19

The green fabrication of metal nanoparticles by using botanical extracts is significantly important for increasing research attention in nanotechnology, since it does not require high energy inputs or the production of highly toxic chemicalbyproducts. Here, silver (Ag), gold (Au) and their bimetallic (Ag/Au) nanoparticles (NPs) were green synthesized using the Crescentiaalata aqueous flower extract. Metal NPs were studied by spectroscopic (UV–visible spectroscopy, fluorescence spectroscopy, FT-IR spectroscopy, XRD and EDX) and microscopic (AFM and TEM) analysis. AFM and TEM showed that Ag and Au NPs had triangular and spherical morphologies, with an average size of 20 nm. Bimetallic Ag/Au NPs showed spherical shapes with an average size of 10 nm. Ag and Ag/Au bimetallic NPs showed high antibacterial and antibiofilm activities towards Gram-positive and Gram-negative bacteria. Overall, the proposed synthesis route of Ag, Au and Ag/Au bimetallic NPs can be exploited by the pharmaceutical industry to develop drugs effective in the fight against microbic infections.

USING LOUDSPEAKER DIAPHRAGM FOR DETERMINING THE SOUND LEVEL OF DIFFERENT IMPEDANCE

A. P. ALFA — 2020-02-26

This paper work describes a study of a loudspeaker sound level and its modes of vibration using different impedance. Results obtained show that diaphragms that utilize a flat or shallow height produce higher frequencies, as opposed to deeper heights which are better for lower frequencies. In other to get the similar sound level, 4 ohms require more while 8 ohms require less powerful amplifier to arrive at the same maximum output when compared to 16 ohms. The lower the impedance the higher the power handle and the lower the sensitivity numbers. 4 ohms speakers place a significantly heavier demand on power amplifier as compared to 8ohms because of their lower impedance, twice as much current will flow through a 4 ohms speaker as compared to the 8 ohms and 16 ohms respectively. For a given volume setting, also comparing the three cones with different impedance, it was observed and evident that the 16 ohms impedance cone when mounted on the same rated permanent magnet produced the highest sound for low power drive as measured by the sound level meter when compared with the other two cones.

A MATHEMATICAL MODEL ON THE USE OF VIBRATION TO REDUCE MACRO-FOULING IN A SPHERICAL MEMBRANE WITH TENSION

SHEILA J. KIPROTICH — 2019-10-25

Fouling is the accumulation of unwanted materials on the solid surfaces to the detriment of function .The use of filters and sieves is applicable in domestic and industrial sectors and the efficiency of filtration membranes is hindered by fouling. Fouling is caused by high solute deposited on the contact surface of the membrane. This can be reduced through bubbling, aeration, and most effectively by induced vibrations which generates 3-D wave equations in spherical co-ordinates with respect to the transverse motion and oscillation of the vibrating membrane. This study will develop a mathematical model of vibration in reducing macro fouling in a circular membrane with tension. The model equation will be solved using separation of variables. The expected results will be determined analytical solution for the 3-D wave equation, giving determined effects of oscillation on the rate of fouling. These results will indicate threshold values that are necessary to eliminate fouling.