Influence of sub-cooling on the energy performance of two ecofriendly R22 alternative refrigerants

In this study, the effects of sub-cooling on the various refrigeration cycle performance parameters using the alternative refrigerants (R432A and R433A) as working fluids were evaluated theoretically and compared with those obtained using the baseline refrigerant (R22). The results obtained showed that the thermodynamic properties of R432A and R433A matched those of R22 and they could be used as substitute for R22. The two alternative refrigerants exhibited very high thermal conductivity with average values of 59.3% and 58.0% higher than that of R22, respectively. Their condenser duties are also better than that of R22, which shows that they could perform very well as refrigerants in heat pump systems. They exhibited higher coefficient of performance (COP) and higher relative capacity index (RCI) than R22. The average COPs obtained for R432A and R433A were 12.9 and 16.7% higher than that of R22. They also exhibited lower power per ton of refrigeration (PPTR) than that of R22, but R433A emerged as the most energy efficient refrigerant among all the investigated refrigerants with average reduction in PPTR of 28.5% higher than that of R22. Generally, incorporation of sub-cooling heat exchanger in thesystem, greatly improved the performance of the system; it increased the  COP, reduced the compressor energy input and the specific power consumption of the system. The two alternative refrigerants, consistently exhibited better performance than R22 in sub-cooling heat exchanger refrigeration system. R433A performed better than both R22 and R432A in that the highest RCI, COP, reduction in energy input, reduction in PPTR and lowest discharge temperature were obtained using R433A in the system.Keywords: Sub-cooling, energy, performance, eco-friendly, R22 alternative

DEVELOPMENT AND PERFORMANCE EVALUATION OF A RICE DE-STONING MACHINE USING VIBRATING SIEVES

A rice de-stoning machine using vibrating sieves was designed, fabricated with locally sourced materials and tested. The performance of the machine was evaluated and the results obtained showed that the feed regulator opening has significant effects on the de-stoning rate, de-stoning efficiency and rice losses. The best performance was obtained at feed regulator opening of 20 mm. Above 20 mm opening, the higher the feed regulator opening the higher the de-stoning rate and grain losses, and the lower the de-stoning efficiency. The average capacity of the machine was found to be 31.84 g/sec. and the average efficiency also was 98.3%.     &nbsp

Assessment of Ground Water Quality in Emohua Lga, Rivers State, Nigeria

The physico-chemical and microbial quality of ground water in Emohua, Rivers State were examined between December – February, 2015. Five commercial borehole from 5 different communities were analyzed for various physico-chemical parameters using standard methods. Electrical conductivity ranged from 10-97 µS/cm with mean value of 32.8±3.2 µS/cm, pH ranged from 6.34 – 6.6 with a mean value of 6.48±1.1, turbidity 0-34 with mean value of 1.02±0.1, alkalinity 4-8 mg/L with mean value of 5.6±0.5 mg/L, dissolved oxygen averaged 8.0±2.5 mg/L, biological oxygen demand 3.36-13.28 mg/L with a mean value of 6.912±0.6 mg/L, chemical oxygen demand 18.40-32.40 mg/L, with a mean value of 28.96±3.8 mg/L and temperature 24.6-25.70C with a mean value of 25.180C. Total hardness raged from 4-40 mg/L with mean value of 18.8 mg/L, total dissolved solids ranged from 40-80 with mean value of 32±2.5 mg/L and total suspended solids ranged from 20-140 with mean value of 44±3.1 mg/L. Values of microbial analysis ranged from 15-460 ml for faecal coliform count while total coliform count ranged from 7-43 ml. Some parameters were within SON/FEPA/WHO permissible limits. Only Borehole (B4) showed levels within WHO standard for total and faecal coliform but had the least and highest DO and BOD values respectively. More appropriate treatment is required before the consumption of water from boreholes based on the results of the present study. Regulatory authorities should supervise properly water being sold to the public to avoid long term accumulative health problems. Keywords: Borehole water, communities, physico-chemical and microbial properties

PREVALENCE OF CTX-M-PRODUCING GRAM-NEGATIVE UROPATHOGENS IN SOKOTO, NORTH-WESTERN NIGERIA

Objective: Infections of the urinary tract remains one of the most common bacterial infections with many implicated organisms being Gram-negative, which are increasingly resistant to antimicrobial agents. The aim of the study was to evaluate the resistance of ESBL producing Gram-negative enterobacteriaceae to commonly prescribed antibiotics and the prevalence of CTX-M genes from these isolates using polymerase chain reaction (PCR). Methods: The isolates were collected from urine over a period of 4 mo and studied, and were identified using Microgen Identification Kit (GN-ID). Susceptibility testing was performed by the modified Kirby Bauer disc diffusion method, and results were interpreted according to Clinical and Laboratory Standard Institute (CLSI). Extended-Spectrum Beta-Lactamase (ESBL) production was detected by the double-disc synergy test (DDST). Molecular characterization was based on the isolates that were positive for the phenotypic detection of ESBL. Results: Sixty one (61) isolates of Gram-negative uropathogens were identified. Of these, 19 (31.2%) were E. coli, 15 (24.6%) were Salmonella arizonae, Klebsiella pneumoniae were 7 (11.5%), Klebsiella oxytoca were 3 (4.9%), Enterobacter gergoviae were 6 (9.8%), 4 (6.6%) were Citrobacter freundii, 4 (6.6%) were Serratia marscence, and 1 (1.6%) were Enterobacter aerogenes, Proteus mirabilis, and Edwardsiella tarda each. Analysis of the bacterial susceptibility to antibiotics revealed most of them to be generally resistant to cotrimoxazole (73.3%), nalidixic acid (66.7%), norfloxacin (53.5%), ciprofloxacin (50.5%), gentamicin (48.6%), amoxicillin/clavulanate (45%), and the least resistant was displayed in nitrofurantoin (30%). Of the 15 ESBL producers, 11 (73.3%) were harbouring bla CTX-M genes. Conclusion: The study revealed a high susceptibility to nitrofurantoin, whereas susceptibility to cotrimoxazole was lowest. It further portrays a high prevalence of enterobacteriaceae isolates harbouring bla CTX-M genes in Sokoto metropolis

Experimental Analysis of the Performance of the Eco-Friendly R510A and R600a Refrigerants in a Retrofitted Vapour Compression Refrigerating System

Halocarbon refrigerants have been scheduled for total phase out because they contributed significantly to the two major global environmental problems - ozone layer depletion and global warming.In this study, the performances of the environmentally friendly R510A and R600a in a retrofitted domestic refrigerating system were investigated experimentally and compared with the performance of R134a. The results obtained showed that R510A has the lowest discharge pressure with an average value of 13.4 % lower than that of R134a. The average pressure ratios of R510A and R600a were 16.91 and 12.17 %, respectively, lower than that of R134a.The Volumetric Cooling Capacity obtained for R510A was 5.34 % higher than that of R134a. R510A and R600a exhibited higher refrigerating effect and Coefficient of Performance (COP) than R134a.The average COPs for R510A and R600a were 22.26 and 3.06 %, respectively, higher than that of R134a. Generally, R510A and R600a performed better than R134a and they can be used as retrofit substitute refrigerants for R134a in the existing domestic refrigerators. The best performance was obtained from the use of R510A in the retrofitted system

Paravertebral block with lignocaine-bupivacaine mixture in goats

Loco-regional anaesthesia and sedation protocols are becoming more popular in ruminant. This research compared some effects of xylazine or acepromazine in combination with lignocaine-bupivacaine mixture for paravertebral nerve block in goats. Twenty adult, apparently healthy West African Dwarf goats were randomly allocated to two groups (five males and five females each). Each group received either xylazine (0.05 mg/kg) + 2 % lignocaine (2mg/kg) – 0.5 % bupivacaine (0.95 mg/kg) mixture (XLB) or acepromazine (0.05 mg/kg) + lignocaine-bupivacaine mixture (ALB). Clinical parameters were recorded immediately (0 minutes) and at 10-minute intervals for an hour and 24 hours. Venipuncture was carried out via jugular vein for haematology before administration of drug (B0), 30 minutes (B30), 60 minutes (B60) and 24 hours (B24). Data was analyzed using descriptive statistics and presented as mean and standard deviation at a significance level of 0.05. The onset of deep sedation following administration of acepromazine was 31.5 ± 0.97, while it was 2.90 ± 0.57 for xylazine. Acepromazine significantly (P < 0.05) reduced the rectal temperatures (RT) of the goats within the first 20 minutes and significantly reduced the respiratory rates of the goats when compared to xylazine. None of the drugs significantly altered the heart rate of the goats. None of the changes in haematological parameters was statistically significant across the sampling time frame. However, red cell parameters (Packed cell volume, red blood cell count, and haemoglobin concentration) and Lymphocyte count were significantly depressed after XLB administration. All the haematological changes were restored to pre-anaesthetic values after 24hours. This study demonstrates that xylazine can be a beneficial alternative and desirable for emergencies in minor ruminant sedation

Relationship between Ponderal Index, Mid-Arm Circumference/ Head Circumference Ratio and Clinical Assessment of Nutritional Status Score (CANSCORE) in the Determination of Nutritional Status of Newborn at Birth in Nigeria

Background: Early and accurate assessment of the nutritional status of newborns is important to many clinicians because of the potential immediate and late sequelae of malnutrition.Objective: To assess the relationship between different methods of assessing the nutritional status of neonates.Methods: Subjects were consecutive, live, singleton, full term neonates delivered in the hospital. The birth weights, Ponderal index, Mid arm circumference/head circumference ratio, birth weight for gestational age using intrauterine growth charts and Clinical Assessment of Fetal Nutritional Status Score (CANSCORE) were used to determine the nutritional status in the first 24 hours of life.Results: Of 386 subjects, 172 (44.6%) were males and 214 (55.4%) females. Nutritional status assessment using various indices showed the following prevalence of malnutrition: using birth weights, 54 (14.0%) were LBW; MAC/HC ratio showed 56 (14.5%), with PI, 64(16.6%), weight for gestational age, 112(29.0%) were SGA and CANSCORE showed 90(23.3%) as malnourished among the babies.MAC/HC showed a better specificity and had a more positive correlation than PI when compared to CANSCORE whilst PI showed a better sensitivity than MAC/HC when evaluated against CANSCORE.Conclusions: Prevalence of FM is high in this study. Intrauterine growth charts and CANSCORE appeared to identify more babies with FM than other methods. CANSCORE in this study has revealed the rising trend in the prevalence of FM when compared with other studies with similar methodology. Early routine assessment of the nutritional status of newborns should be carried out so as to reduce the risk of increased morbidity and mortality associated with fetal malnutrition

Top management characteristics and firm's international diversification activities: evidence from a developing nation

Recent trend shows that foreign investment has increased rapidly, and raises a question as to whether managerial characteristics impact international diversification, as claimed by the Uppsala internationalisation process theory. This paper investigates the relationship between top management team's characteristics and firm's Outward Foreign Direct Investment, that is, international diversification. This study focuses on 83 of the top 100 largest Malaysian multinational firms. The entropy measure is used as the proxy for level of international diversification. Age, international experience, educational level and functional background are proxies reflecting the management's cognitive abilities and competencies. The findings showed that age and functional background have significant positive influence on the level of international diversification. In addition, the results also suggested there is a reasonable support for upper echelons theory and Uppsala internationalisation process theory

DEVELOPMENT OF A SOLAR BOX FOR COOKING AND WATER HEATING

Solar cooking is the utilisation of direct insolation harnessed from the sun as energy source in cooking and water heating. In this study, a device for solar collection and direct utilisation for cooking and water heating was developed. The device consisted of two boxes a smaller box 600 mm × 600 mm × 460 mm insulated with coconut coir of thermal conductivity 0.295Wm-1) -1 placed within a larger box 700 mm × 700 mm ×500 mm. The direct solar insolation (Is), stagnation temperature of the device (Ts), ambient temperature (Ta) andthe wind velocity (V) were measured in accordance with ASHRAE standards. The regression procedure of Mini Tab (v.16) was used to relate the cooker temperature (Tc) with Is, Ts, Ta, and V. The presence of the heat storage unit made it possible to cook beyond 15:00 hours up until 18:00 hours local time while the hot water from the dispensing unit attained temperature of about 650c for most days of testing at about 13:00 ± 0:40 hours and gradually dropped to about 50℃ ± 5℃ by 19:00 hours local tim