THERMAL AND THERMO-MECHANICAL PROPERTIES OF GREEN MOLDING

VERSUS EXISTING MOLDING COMPOUNDS

*Gideon A. Legaspi

Physical Sciences Department, College of Science and Computer Studies,  De La Salle University – Dasmariñas, Dasmariñas, Cavite, Philippines.

ABSTRACT

The thermal and thermo-mechanical properties of dicyclopentadienyl and ortho-creso novolac-based green molding compounds (GMC) were determined and compared with analogous existing molding compounds (EMC).  The thermal stability profiles under oxidative atmosphere was determined using a Thermogravimetric Analyzer (TGA) which monitored the weight loss of the sample as it was heated from 25⁰C to ­500⁰C with a ramping rate of 10⁰C/minute. The results showed that GMC have better thermal stability than analogous EMC as shown by their higher onset temperature of degradation and lower percent weight loss.  The curing kinetics of the samples was evaluated using a Differential Scanning Calorimeter (DSC) which monitored the percent curing of the sample from 160⁰C to 200⁰C at 10⁰C intervals.  The results showed that GMC have comparable or slightly higher degree of curing than their EMC counterpart.  Lastly, the coefficient of thermal expansion (CTE) and glass transition temperature (Tg) were measured using a Thermo-mechanical Analyzer (TMA) which monitored the change in the dimension of the sample from 25⁰C to 300⁰C with a ramping rate of 10⁰C/minute.  The results showed that the CTE values of GMC were lower than the corresponding EMC while their Tg values were higher. Overall, GMC samples have better thermal and thermo-mechanical properties than their EMC counterpart.  They were therefore the better materials for semiconductor encapsulation because of their desirable characteristics aside from their non-toxic nature.

Keywords: differential scanning calorimetry, epoxy molding compounds, semiconductor encapsulation, thermogravimetry, thermo-mechanical analysis

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CRYPTOSPORIDIUM SPP. OOCYSTS AND GIARDIA SPP. CYSTS IN SELECTED

LIVESTOCK FARMS OF CAVITE, PHILIPPINES

*Jonnacar S. San Sebastián

Biological Sciences Department, College of Science and Computer Studies,  De La Salle University – Dasmariñas,   Dasmariñas, Cavite, Philippines.

ABSTRACT

Detection of Cryptosporidium and Giardia infections in livestock farms rearing hogs, cow and chicken located in Cavite was done in this study.   This is to determine the extent of occurrence of infection among the most commonly reared animals in the area.  Cryptosporidium and Giardia infections were determined using Merifluor^®Cryptosporidium/Giardia (Merifluor® C/G) direct immunofluorescent assay.  Mixtures of fecal sample were collected in the farmyards and storage heaps of 18 piggery, 10 cow barn and 12 poultry farms across geographic areas of the province.  An average oocysts/10µl preserved-stool of 4.67 ± 2.16 for drift of hogs; 4.58 ± 2.64 for herds of cow; 6.34 ± 4.21 for flocks of chicken were recorded.  There is no significant difference on the oocyst concentrations of Cryptosporidium spp. in various livestock.  While the average cysts/10µl preserved-stool were 17.08 ± 15.38 for drifts of hogs, 5.33 ± 2.50 for herd of cow and 3.50 ± 1.76 for flock of chicken.  There is a significant difference (p<0.5) on the cyst concentrations of Giardia among different livestock The established oocyst and cyst concentrations from the farm animals is low compared to the established infective dose of 132 Cryptosporidium spp. oocysts/10µl preserved-stool and 10 Giardia spp. cysts/10µl preserved-stool. However, the mere presence of Cryptosporidium oocysts spp. and Giardia spp. cysts in hogs, cow and chicken suggested that these animals could be a source of infection, and thereby may pose threat to humans.

Keywords: Cryptosporidium, Giardia, oocysts, cyst, livestock

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FUNGAL CONTAMINANTS IN AIR CONDITIONED ROOMS OF A TERTIARY INSTITUTION

AND ITS ASSOCIATION WITH ALLERGIC RHINITIS

^1*Norbel Tabo, ¹Jina Han, ¹Ehrin Papa, ²Nina Gloriani

¹Biological Sciences Department, College of Science and Computer Studies,  De La Salle University – Dasmariñas,   Dasmariñas, Cavite, Philippines.

²Department of Medical Microbiology, College of Public Health, University of the Philippines,

Manila, Philippines

ABSTRACT

This study assessed the level and composition of fungi in indoor air of air-conditioned offices and classrooms in a tertiary academic institution in Dasmariñas City, Cavite during the wet and dry seasons, including their effects on the academic community. Gravitational Petri Plate Method was used in the isolation of fungi in indoor and outdoor air samples and correlated to relative humidity and air temperature. The prevalence of allergic rhinitis in students using air conditioned classrooms was also determined. Ninety-two percent (n=180) of indoor air samples were positive to fungal contamination in which the cool, dry season had the greatest counts. Fungal colony-forming units of the indoor and outdoor were significantly correlated to relative humidity and air temperature. A significant difference in fungal counts was also detected between morning samplings and afternoon samplings. No significant difference was observed among the three areas studied, which were the offices, laboratory rooms and lecture rooms, although based on the CFU/plate, the laboratory rooms were the most contaminated. Indoor air samples recovered a total of 1,469 fungal colonies wherein Cladosporium spp. (68%) predominated, followed by Aspergillus spp. (13%) and Penicillium spp. (12%). Cladosporium spp. was the predominant fungal contaminant in the three areas.  Regarding the prevalence of allergic rhinitis in students and support staffs using air conditioned rooms, 11.2% (n=330 respondents) experienced sneezing, runny- or blocked-nose. The data on the seasonal composition and concentration of fungi may be useful for both ecology and allergy prevention and treatment.

Key Words: Assessment, Fungal Contaminants, Air Conditioned Rooms, Health Implications

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INFESTATION OF SPIRALING WHITEFLY (ALEURODICUS DISPERSUS RUSSELL) (HOMOPTERA: ALEYRODIDAE) ON PAPAYA (CARICA PAPAYA L.) AT  SEASONAL VARIATION

^1*Celeste R. Desingaño, ²Cristina C. Salibay

¹College of Arts and Sciences, Lyceum of the Philippines University- Cavite Campus, General Trias, Cavite, Philippines.

²Biological Sciences Department, College of Science and Computer Studies,  De La Salle University – Dasmariñas,   Dasmariñas, Cavite, Philippines.

ABSTRACT

This study focused on the pattern of infestation of spiraling whitefly  on ninety-one papaya plants at varying seasons. It determined the correlation of infestation of spiraling whitefly to temperature, relative humidity and number of rainy days. These environmental factors were monitored daily for six months and were correlated with the infestation rate of the spiraling whiteflies using chi-square test.  Results showed that Papaya plants were infested with spiraling whiteflies with the highest  infestation rate in May, and least in September. Temperature was relatively fair ranging between 24.8 to 25.8°C and relative humidity (RH) ranged between 85-88%.  High RH with 85% and 88% was recorded in summer, April and May, respectively compared to the expected 55% RH while low RH (85%) was recorded in August and September compared to the expected RH of 95%.   However, the mean RH (76%) for a period of six months was within the normal range.    The frequency of rainfall was high in April as compared to May to July, the expected rainy months. There was no significant correlation (p>0.05) established between infestation rate of spiraling whiteflies and temperature, relative humidity or rainfall. Hence, infestation rate was not affected by the said environmental factors.

Keywords:  humidity, infestation, spiraling whitefly, papaya, rainfall, temperature

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