Journal of Mathematical and Fundamental Sciences
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Prediction Limits for Poisson INAR(1) Process
Get PDFWe discuss the problem of deriving an estimative prediction limit as well as a simulation-based improved prediction limit for a future realization from the stationary, first-order Poisson INAR(1) process. An assessment of these limits was carried out by calculating their coverage probability, conditional on the last observation. It was found that while an estimative prediction limit may always be calculated, an improved prediction limit may not be obtained due to its discreteness and expectation to obtain a coherent prediction
The Synthesis of Alginate-Capped Silver Nanoparticles under Microwave Irradiation
Get PDFSynthesis of silver nanoparticles (Ag-NP) was successfully performed within a few minutes by microwave irradiation of the precursor salt (AgNO3) and alginate mixed solution in one pot. Herein, alginate molecules acted as both a reducing and stabilizing agent for the preparation of the silver nanoparticles. The obtained nanoparticles were characterized by ultraviolet-visible (UV-Vis) spectroscopy, particle size analysis (PSA), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The pH and concentration ratio of the alginate/metal precursor salt greatly influenced the particle size and its distribution of Ag-NP. The higher the pH the higher the nucleation rate and the larger the electrostatic stabilization, while both of them were responsible for producing a smaller particle size and a narrower size distribution. A higher concentration ratio also yielded a smaller particle size and a narrower size distribution, but above the optimum ratio, the trend was conversely changed due to the reducing capability of the alginate, which was dominant above the optimum ratio, thus creating a high density of nuclei, allowing aggregation to occur. A lower ratio not only led to a higher tendency to produce larger particles, but also a higher probability of anisotropic particle shape formation due to the lack of reducing capability of the alginates
Some Basic Properties of Completely Prime Ideals in Near Rings
Get PDFIn this investigation we studied completely prime, weakly completely prime, quasi completely prime and weakly quasi completely prime ideals in near-rings. Some characterizations of completely prime and weakly completely prime ideals were obtained. Moreover, we investigated relationships between completely prime and weakly completely prime ideals in near-rings. Finally, we obtained necessary and sufficient conditions for a weakly completely prime ideal to be a completely prime ideal
Pb-free Radiation Shielding Glass Using Coal Fly Ash
Get PDFIn this work, Pb-free shielding glass samples were prepared by themelt quenching technique using subbituminous fly ash (SFA) composed ofxBi2O3 : (60-x)B2O3 : 10Na2O : 30SFA (where x = 10, 15, 20, 25, 30 and 35 by wt%). The samples were investigated for their physical and radiation shielding properties. The density and hardness were measured. The results showed that the density increased with the increase of Bi2O3 content. The highest value of hardness was observed for glass sample with 30 wt% of Bi2O3 concentration. The samples were investigated under 662 keV gamma ray and the results were compared with theoretical calculations. The values of the mass attenuation coefficient (μm), the atomic cross section (σe) and the effective atomic number (Zeff) were found to increase with an increase of the Bi2O3 concentration and were in good agreement with the theoretical calculations. The best results for the half-value layer (HVL) were observed in the sample with 35 wt% of Bi2O3 concentration, better than the values of barite concrete. These results demonstrate the viability of using coal fly ash waste for radiation shielding glass without PbO in the glass matrices
Decay Resistance of Medium Density Fibreboard (MDF) Made from Pineapple Leaf Fiber
Get PDFMedium density fiberboard (MDF) production is increasing due to the development of manufacturing technologies. MDF products are utilized for traditional wood applications that require fungal resistance. This study investigated some of the important biodegradation properties of MDF composite board made from renewable biomass from pineapple leaf fiber (Ananas comosus). The variable factors were type of board and type of resin. Two different types of board with a target density of 0.8 g/cm3 were manufactured. The boards were prepared in three layers of about 1:1:1 weight ratio in crossoriented and unidirectional pattern, using low molecular weight (LM) phenol formaldehyde (PF) resin type PL-3725 and high molecular weight (HM) PF resin type PL-2818 for impregnation and adhesive purposes. Decay resistance (white and brown rot fungi) of the MDF was evaluated to assess its biological performance. In this study, fiber orientation had no effect on the decay resistance to white and brown rot fungi of the specimens. However, a slight increase was found for the mass loss of the low molecular weight PF resin board specimens compared with the mixed low and high molecular PF resin board specimens. The total resin content of 20% of the type I boards prohibits degradation by decay
Effect of Board Type on Some Properties of Bamboo Strandboard
Get PDFThe objective of this study was to evaluate the properties of bamboo strandboard (OSB) by comparing different board types and strand-lengths. Bamboo strandboards with nominal dimensions of 37 mm by 37 mm by 12 mm and target density 0.65 g/cm3 were manufactured using moso bamboo (Pyllostachys pubescent Mezel) and MDI resin to produce two types of strandlength. Two types of strand length and MDI resin were used to produce three types of strandboard. The bending properties and dimensional stability of the strandboards were evaluated according to the Japanese Industrial Standard (JIS) for particleboard. The results of this experiment indicate that the bending properties and internal bond strength were affected by both board type and strand-length. The distribution of resin inside the 80 mm strandboard was less homogenous than in the 50 mm strandboard, which affects the internal bond strength. Thickness swelling of the RAND board was the highest and linear stability was affected substantially by strand alignment. The RAND board and cross-oriented 3LAY board effectively restrained linear expansion in the direction perpendicular to the strand alignment. A cross-oriented core may be the most effective way to reduce dimensional change and bending property values in perpendicular directions
Subclasses of Bi-Univalent Functions of Complex Order Based on Subordination Conditions Involving Wright Hypergeometric Functions
Get PDFIn this paper, we introduce and investigate a new subclass of bi-univalent functions Σ of complex order dened in the open unit disk, which are associated with hypergeometric functions and satisfying subordinate conditions. Furthermore, we nd estimates on the Taylor-Maclaurin coecients | a2 | and | a3 | for functions in the new subclass. Several (known or new) consequences of the results are also pointed out
Phosphate Solubilizing Bacteria Adaptive to Vinasse
Get PDFMicroorganisms identified as phosphate solubilizing bacteria (PSB) adaptive to vinasse were successfully screened from sugarcane soil from an agriculatural estate in Jatiroto. By conducting a screening on Pikovskaya's agar medium (PAM), we found that five different isolates were detected as PSB (pvk-5a, pvk-5b, pvk-6b, pvk-7a, and pvk-8a). Of the five isolates only three could be grown and were found to be adaptive to vinasse based medium without any nutrients added (pvk-5a, pvk-5b and pvk-7a). The three isolates were characterized as coccus and Gram negative with no endospores detected. We suggest that these three isolates can be used as biofertilizer agent to support organic farming
The Potency of Trigonaâs Propolis Extract as Reactive Oxygen Species Inhibitor in Diabetic Mice
Get PDFHyperglycemia has been proven to increase oxidative stress due to the production of reactive oxygen species (ROS) that exceed the capabilities of the natural antioxidant defenses, causing a deficiency in insulin receptors and insulin resistance. In this study, the effect of propolis on ROS was observed. Fifty five (55) male mice (Mus musculus SW.) were divided into 5 groups, i.e. KN (normal control), KDM (diabetes control), and P1, P2, P3. Propolis solution 50, 100 and 175 mg/kg bw was given to groups P1, P2 and P3 respectively, while distilled water was given to groups KN and KDM by oral gavage for 21 days. Density of ROS was measured every 7 days, while measurement of plasma insulin was carried out every 3 days. The results show that the density of ROS in the groups treated with propolis was lower than in the KDM group. However, the plasma insulin levels in the propolis groups were higher than in the KDM group. It was concluded that propolis can decrease ROS density and causes an increase in plasma insulin levels