Vol. 44 No. 2 (2012)

Oxygen plays an important role in the metabolism of cells inside the human body. The transfer of oxygen from blood to tissue takes place in capillaries through a diffusion process. The capillary-tissue region is usually represented by the so-called Krogh cylinder model, in which the distribution of the oxygen concentration in a tissue region leads to a diffusion equation with oxygen consumption rates following the Michaelis-Menten kinetics. In this paper, we restrict ourselves to the steady state case and solve the equation analytically by means of asymptotic expansion for a particular limit…

Observations and a linear wave model were used to evaluate the role of equatorial oceanic wave processes in affecting the evolution of the 2006 positive Indian Ocean Dipole (IOD), focusing on the activation phase of the event. The observations indicate the presence of upwelling equatorial waves and westward near-surface zonal currents along the equator during the activation phase of the event in August 2006. These upwelling equatorial waves (negative sea surface height anomalies) and westward zonal current anomalies contributed to significant sea surface cooling in the eastern equatorial…

This experiment was aimed at finding out the effects of usingnitrifying bacteria and Chlorella sp. and the application of a differing number of 3-dimensional cubical bamboo shelters for enhancing the growth performance of Giant Freshwater Prawns (Macrobrachium rosenbergii de Man) during the nursery phase in an indoor system. During 28 days of culture, treatment II (application of 4 shelters ~40% culture volume occupation) resulted in better prawn growth and culture performance compared to control (no shelter application) (p<0,05). At the end of the experiment, treatment II showed the highest…

The aim of this study was to identify the antifungal activity of coumarin isolated from Ageratum conyzoides L. leaves and to observe its influence on Candida albicans cells by scanning electron microscope (SEM) and transmission electron microscope (TEM). Antifungal activity testing with the disk diffusion method showed coumarin was active toward pathogenic fungus Candida albicans with an MIC value of coumarin of 125 g mL-1. The results show that this compound damaged the cell by pores formation on the cell wall. Death of cells occurred due to leakage and necrosis of cytoplasmic content.

Zeolite loaded with alkylsilane-covered titanium oxide was found to be more effective than its nonporous silica counterpart as phase-boundary catalyst (PBC) to promote epoxidation of alkenes with aqueous hydrogen peroxide. It was demonstrated that the phase-boundary catalyst system required neither stirring to make an emulsion, nor addition of a cosolvent to make a homogeneous solution to drive the reaction. However, some basic facts about them remain unclear, such as the question as to where an effective location of the active sites of PBC resides: is it on the external surface of the…

A new procedure of space-time modeling through the Invers of Autocovariance Matrix (IAcM) is proposed. By evaluating the IAcM behaviors on behalf of the Generalized Space-Time Autoregressive (GSTAR) process stationarity, we may find an appropriate model to space-time data series. This method can complete the Space-Time ACF and PACF methods for identifying space-time models. For study case, we apply the GSTAR models to the monthly tea production of some plantations in West Java, Indonesia.

Apatite-type lanthanum silicates show a great potential to be used as an electrolyte for intermediate- to low-temperature (600-700 ï‚°C) solid oxide fuel cells (ITSOFC). However, so far these materials need to be prepared using a very high-temperature method, thus there is a growing interest to prepare apatites at lower temperatures. This paper reports the synthesis of undoped La9.33Si6O26 and doped apatites (La9CaSi6O26,5, La9SrSi6O26,5, and La9BaSi6O26,5) from raw materials La2O3, Na2SiO4, BaCO3, CaCO3, and SrCO3 using a hydrothermal method. The polycrystalline apatites were obtained as a…

Chlorophyll a is the most abundant pigment on Earth responsible for trapping light energy to perform photosynthesis in green plants. This molecule has been studied for many years from different points of interest with both experimental and theoretical methods. In this study, the Restricted Hartree-Fock/Configuration Interaction Single (RHF/CIS), Time-Dependent Density Functional Theory (TDDFT), and several semi-empirical methods (CNDO/S and ZINDO) calculations were carried out to reconstruct the UV-Vis absorption spectra of chlorophyll a. To some extent, the calculation results based on the…