8 research outputs found
Sonication time effect towards stability of Al2O3/PAG and SiO2/PAG Nanolubricants / A.A.M. Redhwan..[et al.]
No full textUltrasonication is the act of applying sound force to agitate particles in a sample with the frequency of more than 20 kHz. It is an external vibration induced during preparation of nanolubricant that helps the particles to overcome the van der Waals force bonding. Nanolubricant prepared is intended to be used in automotive air conditioning (AAC) system to improve its performance. In this work, stability of Al2O3/Polyalkylene glycol (PAG) and SiO2/PAG nanolubricants of 0.2 % volume concentrations with different sonication time were investigated. Five samples for each nanolubricant were prepared by two-step method process with variation of sonication time from zero to two hours’ time with half an hour interval. The stability tests were done by visual sedimentation and UV-vis spectrometer. The optimum sonication time found to be one and half hours and two hours for Al2O3/PAG and SiO2/PAG nanolubricants respectively. Both nanolubricants were found stable for more than two weeks’ period
Thermal conductivity enhancement of Al
No full textNanolubricant been introduced in compressor might improve the performance of automotive air conditioning system. Prior testing of the nanolubricant enhancement performance, thermal conductivity of Al2O3/PAG and SiO2/PAG nanolubricants has to be investigated and compared. Al2O3 and SiO2 nanoparticles first been dispersed in Polyalkylene Glycol (PAG) for different volume concentrations. KD2 Pro was used in determining the thermal conductivity of the nanolubricant. The experimental results showed that the thermal conductivity of the Al2O3/PAG and SiO2/PAG nanolubricants increased by volume concentration but decreased by temperature. The highest thermal conductivity was observed to be 0.153 W.(m · K)−1 and enhancement of 1.04 times higher than the base lubricant for Al2O3 with 1.0 volume concentration. Finally regression equations were developed in order to estimate the thermal conductivity for these nanolubricants
Thermo-physical properties of metal oxides composite Nanolubricants / N.N.M. Zawawi...[et al.]
No full textThermal conductivity and viscosity of the different combination of composite nanolubricants for 0.02% volume concentrations at a temperature range of 30 to 80 oC were investigated. Al2O3, SiO2 and TiO2 nanoparticles were dispersed in the Polyalkylene Glycol (PAG 46) lubricant using the two-step method of preparation. Thermal conductivity and viscosity were measured using KD2 Pro Thermal Properties Analyzer and LVDV-III Rheometer, respectively. The result shows that the thermal conductivity and viscosity of composite nanolubricants decrease with temperature. Composite nanolubricants behaved as Newtonian in the range of the temperatures studied. The most optimum combination of composite nanolubricant is Al2O3-SiO2/PAG as it yields higher enhancement in thermal conductivity but lower in viscosity
Improvement of Nanofluid stability using 4-Step UV-Vis Spectral Absorbency Analysis / M.Z. Sharif...[et al.]
No full textThe most challenging matters for the utilization of nanofluid into a certain system is its stability. The nanofluid with undesirable stability will damage the system due to fouling, and settlement from the base fluid. In addition, unstable nanofluid will have a lower thermal performance enhancement. An improved method, 4-Step UV-Vis spectral absorbency analysis has been suggested to improve the stability of the nanofluid. SiO2 nanoparticles were dispersed in the PAG lubricant by using the two-step preparation method. The stabilization methods of the SiO2/PAG were done by using the suggested method. The result indicates that all nanofluid shows good stability in stationary position even after 30 days. The absorbance of every three concentration decreased compared to their respective initial absorbance, but maintained for specific value at over 70 % compared to the initial absorbance even after 30 days
Tribology Investigation of Automotive Air Condition (AAC) compressor by using Al2O3/PAG Nanolubricant / A.R.M. Aminullah...[et al.]
No full textLubrication is a requisite for any mechanical equipment that moved to avoid wear of sliding parts and enhance the equipment operation consistency. The objective of this study was to seek a new improved automotive air conditioning (AAC) compressor lubricant to enhanced AAC performances. The type of compressor is piston type, Sanden SD 7H10,that normally used by Malaysia compact car. The tribological investigation was focusing on Coefficient of friction and wear rate. The wear rate and coefficient of friction (COF) of Alumina/Polyalkylene glycol (Al2O3/PAG) nanolubricant were evaluated employing reciprocating test conditions to replicate a piston ring/cylinder liner contact following the ASTM G 181-11 Standard. Al2O3 nanoparticle was dispersed in PAG lubricant for volume concentrations between 0.006 to 0.014 vol %. Al2O3/PAG nanolubricant with 0.010 % vol. concentration showed the best reduction of frictional power loss. The enhancement of power saving due to frictional losses was up to 7.59 % compared to pure PAG lubricant. Furthermore, the wear rate of piston liner A.R.M. Aminullah et. al. reduced by 33.39 %. Al2O3 nanoparticles in this circumstances, performed as a solid lubricant to reduce wear. These results show potential approach to enhance the AAC performance, save automotive fuel and elongated the life span for AAC compressor
The worldwide antibiotic resistance and prescribing in european children (ARPEC) point prevalence survey : Developing hospital-quality indicators of antibiotic prescribing for children
No full textObjectives: Previously, web-based tools for cross-sectional antimicrobial point prevalence surveys (PPSs) have been used in adults to develop indicators of quality improvement. We aimed to determine the feasibility of developing similar quality indicators of improved antimicrobial prescribing focusing specifically on hospitalized neonates and children worldwide. Methods: A standardized antimicrobial PPS method was employed. Included were all inpatient children and neonates receiving an antimicrobial at 8:00 am on the day of the PPS. Denominators included the total number of inpatients. A web-based application was used for data entry, validation and reporting. We analysed 2012 data from 226 hospitals (H) in 41 countries (C) from Europe (174H; 24C), Africa (6H; 4C), Asia (25H; 8C), Australia (6H), Latin America (11H; 3C) and North America (4H). Results: Of 17 693 admissions, 6499 (36.7%) inpatients received at least one antimicrobial, but this varied considerably between wards and regions. Potential indicators included very high broad-spectrum antibiotic prescribing in children of mainly ceftriaxone (ranked first in Eastern Europe, 31.3%; Asia, 13.0%; Southern Europe, 9.8%), cefepime (ranked third in North America, 7.8%) and meropenem (ranked first in Latin America, 13.1%). The survey identified worryingly high use of critically important antibiotics for hospital-acquired infections in neonates (34.9%; range from 14.2% in Africa to 68.0% in Latin America) compared with children (28.3%; range from 14.5% in Africa to 48.9% in Latin America). Parenteral administration was very common among children in Asia (88%), Latin America (81%) and Europe (67%). Documentation of the reasons for antibiotic prescribing was lowest in Latin America (52%). Prolonged surgical prophylaxis rates ranged from 78% (Europe) to 84% (Latin America). Conclusions: Simple web-based PPS tools provide a feasible method to identify areas for improvement of antibiotic use, to set benchmarks and to monitor future interventions in hospitalized neonates and children. To our knowledge, this study has derived the first global quality indicators for antibiotic use in hospitalized neonates and children
The worldwide antibiotic resistance and prescribing in european children (ARPEC) point prevalence survey: Developing hospital-quality indicators of antibiotic prescribing for children
No full textObjectives: Previously, web-based tools for cross-sectional antimicrobial point prevalence surveys (PPSs) have been used in adults to develop indicators of quality improvement. We aimed to determine the feasibility of developing similar quality indicators of improved antimicrobial prescribing focusing specifically on hospitalized neonates and children worldwide. Methods: A standardized antimicrobial PPS method was employed. Included were all inpatient children and neonates receiving an antimicrobial at 8:00 am on the day of the PPS. Denominators included the total number of inpatients. A web-based application was used for data entry, validation and reporting. We analysed 2012 data from 226 hospitals (H) in 41 countries (C) from Europe (174H; 24C), Africa (6H; 4C), Asia (25H; 8C), Australia (6H), Latin America (11H; 3C) and North America (4H). Results: Of 17 693 admissions, 6499 (36.7%) inpatients received at least one antimicrobial, but this varied considerably between wards and regions. Potential indicators included very high broad-spectrum antibiotic prescribing in children of mainly ceftriaxone (ranked first in Eastern Europe, 31.3%; Asia, 13.0%; Southern Europe, 9.8%), cefepime (ranked third in North America, 7.8%) and meropenem (ranked first in Latin America, 13.1%). The survey identified worryingly high use of critically important antibiotics for hospital-acquired infections in neonates (34.9%; range from 14.2% in Africa to 68.0% in Latin America) compared with children (28.3%; range from 14.5% in Africa to 48.9% in Latin America). Parenteral administration was very common among children in Asia (88%), Latin America (81%) and Europe (67%). Documentation of the reasons for antibiotic prescribing was lowest in Latin America (52%). Prolonged surgical prophylaxis rates ranged from 78% (Europe) to 84% (Latin America). Conclusions: Simple web-based PPS tools provide a feasible method to identify areas for improvement of antibiotic use, to set benchmarks and to monitor future interventions in hospitalized neonates and children. To our knowledge, this study has derived the first global quality indicators for antibiotic use in hospitalized neonates and children. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved
Obtenção de nano-emulsões de Curcuma longa l. e sua aplicação em bebida aquosa
No full textCurcumin counteracts various pathologies such as cancer and neurodegenerative diseases. However, its solubility is low in aqueous solutions limiting its application. This study seeks to obtain an oil-in-water (O/W) stable emulsion based on Curcuma longa (ORC) oleoresin and to apply it in an aqueous beverage as an alternative to the use of artificial colorants such as tartrazine. Two types of emulsion were formulated: with oleoresin (ORC) and commercial curcumin 75% (CCC), characterized by percentage curcumin retention (%CR), total phenol content (TPC), physical stability and particle size by transmission electron microscopy (TP), then applied in aqueous beverages, characterized by %CR, TP and turbidity (T). Stable nanoemulsions were obtained for EORC and ECC with TP of 10,201nm and 13,847 nm, %CR of 67,136 and 81.991% and TPC of 35,466 and 36,128 mg EAG/L emulsion respectively. In beverages, the %CR for EORC and ECC was 80,014 and 20,048%, TP of 5,732nm and 5,309 nm respectively. The beverage with EORC presented higher turbidity compared to ECC and tartrazine (Control). Beverages were stable over time, but EORC presented higher %CR, which can be a potential alternative as a colorant and antioxidant in aqueous beverages.La curcumina contrarresta diversas patologías como el cáncer y enfermedades neurodegerativas. Sin embargo, su solubilidad es baja en soluciones acuosas limitando su aplicación. Este estudio busca obtener una emulsión estable aceite en agua (O/W) a base de oleorresina de Cúrcuma longa (ORC) y aplicarla en una bebida acuosa como alternativa al uso de colorantes artificiales como la tartrazina. Se formularon dos tipos de emulsión: con oleorresina (EORC) y curcumina comercial 75% (ECC), se caracterizaron mediante porcentaje de retención de curcumina (%CR), contenido de fenoles totales (TPC), estabilidad física y tamaño de partícula mediante microscopía electrónica de trasmisión (TP), luego se aplicaron en bebidas acuosas, caracterizadas por % CR, TP y turbidez (T). Se obtuvieron nanoemulsiones estables para EORC y ECC con TP de 10,201 nm y 13,847 nm, %CR de 67,136 y 81,991% y TPC de 35,466 y 36,128 mg EAG/L emulsión respectivamente. En las bebidas, el %CR para EORC y ECC fue de 80,014 y 20,048%, TP de 5,732 nm y 5,309 nm respectivamente. La bebida con EORC presentó mayor turbidez en comparación a ECC y tartrazina (control). Se obtuvieron bebidas estables en el tiempo, pero EORC presentó mayor %CR, la cual puede ser una alternativa potencial como colorante y antioxidante en bebidas acuosas.A curcumina contrapõe-se a várias patologias como o câncer e doenças neurodegenerativas. Contudo, a sua solubilidade é baixa em soluções aquosas limitando a sua aplicação. Este estudo procura obter uma emulsão estável óleo-em-água (O/W) à base de Curcuma longa (ORC) e aplicá-la em uma bebida aquosa como alternativa ao uso de corantes artificiais, como a tartrazina. Foram formulados dois tipos de emulsão: com oleoresina (ORC) e curcumina comercial 75% (CCC), caracterizada pela percentagem de retenção de curcumina (%CR), teor total de fenol (TPC), estabilidade física e tamanho das partículas por microscopia electrónica de transmissão (TP), depois aplicada em bebidas aquosas, caracterizada pela %CR, TP e turbidez (T). Foram obtidas nanoemulsões estáveis para EORC e ECC com TP de 10,201 nm e 13,847nm, %CR de 67,136 e 81,991% e TPC de 35,466 e 36,128 mg EAG/L emulsão, respectivamente. Nas bebidas, a %CR para EORC e ECC foi de 80,014 e 20,048%, TP de 5,732 nm e 5,309 nm, respectivamente. A bebida com EORC apresentou maior turbidez em comparação com ECC e tartrazina (Control). As bebidas foram estáveis ao longo do tempo, mas a EORC apresentou %CR mais elevada, que pode ser uma alternativa potencial como corante e antioxidante em bebidas aquosa
