Study Of Phasing Distribution Characteristics Of Reflectarray Antenna Using Different Resonant Elements

There has been much interest recently in developing reflectarray antenna due to the combination of some of the best features between the parabolic reflector and phased array antennas. This paper presents the study of the relationship between phasing distribution characteristics and the bandwidth of different resonant reflectarray elements. The gradient characteristics of different elements of patch, dipole and ring printed on a grounded dielectric substrate have been investigated at X-band frequency range using CST computer model. The preliminary simulated results generated from CST computer model demonstrate that ring elements contribute the highest reflection loss performance of 1.74 dB compared to the other two element of dipoles and patches. The attainable static linear phase range of 177o for ring elements is shown to offer a trade off between the static phase range and the bandwidth of the reflectarray elements. In measurement ring element also contribute the highest reflection loss performance of 2.95 dB compared to other two elements

Persepsi industri hospitaliti terhadap golongan pekerja berkeperluan khas (masalah pendengaran)

Kerjaya merupakan salah satu keperluan bagi setiap manusia samada golongan normal mahupun golongan berkeperluan khas. Kerjaya merupakan laluan bagi manusia untuk mencari sumber pendapatan untuk memastikan kelangsungan hidup. Namun, terdapat isu berkaitan pengangguran terhadap golongan berkeperluan khas. Oleh itu kajian ini dilaksanakan untuk mengenal pasti persepsi industri hospitaliti terhadap golongan berkeperluan khas (masalah pendengaran) serta mengenal pasti cabaran yang dihadapi oleh industri dalam pengambilan pekerja berkeperluan khas (masalah pendengaran). Selain itu kajian ini juga dijalankan untuk mengenal pasti keperluan kriteria yang diharapkan oleh industri hospitaliti. Kajian ini melibatkan 28 syarikat di bawah sektor hospitaliti yang terdapat di sekitar Batu Pahat dan Muar, Johor. Seramai 88 orang majikan yang terdiri daripada pengurus, penyelia, ketua-ketua bahagian dan pekerja yang terlibat dengan pekerja berkeperluan khas (masalah pendengaran) adalah responden dalam kajian ini. Kajian ini menggunakan borang soal selidik sebagai instrument kajian. Data yang diperoleh dianalisis menggunakan kaedah deskriptif menggunakan perisian SPSS (Statistic Package for the Social Science) versi 16.0. Hasil dapatan menunjukkan tahap penerimaan industri hospitaliti terhadap golongan pekerja berkeperluan khas (masalah pendengaran) berada pada tahap sederhana

Adsorption of methylene blue by imperata cylindrica: Reaction optimization by response surface methodology (RSM)

Imperata Cylindrica (IC) is a solid waste that is readily available throughout the year known as one of the most important weed in the world and frequently causes major disposal issues. As a result, using IC as a low-cost adsorbent is beneficial from both, economic and environmental standpoint to remove colors from wastewater of textile industry. This work studies the reaction optimization of methylene blue (MB) removal using IC by response surface methodology (RSM). The RSM experiments were designed with 4 independent variables (initial adsorbent dosage, initial pH, initial dye concentration, and initial temperature) and 1 response variable (percent removal of MB). According to the pareto figure, the initial pH demonstrated the greatest impact on the percent removal of MB. The RSM data predicted the optimum condition of MB removal up to 86.61% using IC, by utilizing adsorbent dosage of 1.458 g/L, at 42 oC, initial pH of 6.8 and MB concentration of 235 ppm. The chacterization analysis revealed the physicochemical properties of IC in the adsoprtion process

Isolation and characterization of a molybdenum-reducing and glyphosate-degrading Klebsiella oxytoca strain Saw-5 in soils from Sarawak

Bioremediation of pollutants including heavy metals and xenobiotics is an economic and environmentally friendly process. A novel molybdenum-reducing bacterium with the ability to utilize the pesticide glyphosate as a carbon source is reported. The characterization works were carried out utilizing bacterial resting cells in a microplate format. The bacterium reduces molybdate to Mo-blue optimally between pH 6.3 and 6.8 and at 34oC. Glucose was the best electron donor for supporting molybdate reduction followed by lactose, maltose, melibiose, raffinose, d-mannitol, d-xylose, l-rhamnose, l-arabinose, dulcitol, myo-inositol and glycerol in descending order. Other requirements include a phosphate concentration at 5.0 mM and a molybdate concentration between 20 and 30 mM. The molybdenum blue exhibited an absorption spectrum resembling a reduced phospho-molybdate. Molybdenum reduction was inhibited by mercury, silver, cadmium and copper at 2 ppm by 45.5, 26.0, 18.5 and 16.3%, respectively. Biochemical analysis identified the bacterium as Klebsiella oxytoca strain Saw-5. To conclude, the capacity of this bacterium to reduce molybdenum into a less toxic form and to grow on glyphosate is novel and makes the bacterium an important instrument for bioremediation of these pollutants

Modest serum creatinine elevation affects adverse outcome after general surgery

Modest serum creatinine elevation affects adverse outcome after general surgery.BackgroundModest preoperative serum creatinine elevation (1.5 to 3.0 mg/dL) has been recently shown to be independently associated with morbidity and mortality after cardiac surgery. It is important to know if this association can be applied more broadly to general surgery cases.MethodsMultivariable logistic regression analyses of 46 risk variables in 49,081 cases from the Veterans Affairs National Surgical Quality Improvement Program, undergoing major general surgery from 10/1/96 through 9/30/98.ResultsThirty day mortality and several cardiac, respiratory, infectious and hemorrhagic morbidities were significantly (P < 0.001) higher in patients with a serum creatinine>1.5 mg/dL. With multivariable analysis, the adjusted odds ratio for mortality for patients with a serum creatinine of 1.5 to 3.0 mg/dL was 1.44 [95% confidence interval (95% CI) 1.22 to 1.71] and for creatinine>3.0 mg/dL was 1.93 (95% CI 1.51 to 2.46). The adjusted odds ratio for morbidity (one or more postoperative complications) for patients with a serum creatinine of 1.5 to 3.0 mg/dL was 1.18 (95% CI 1.06 to 1.32) and for creatinine>3.0 mg/dL was 1.19 (95% CI 0.99 to 1.43). Further stratification and recursive partitioning of creatinine levels revealed that a serum creatinine level>1.5 mg/dL was the approximate threshold for both increased morbidity and mortality.ConclusionsModest preoperative serum creatinine elevation (>1.5 mg/dL) is a significant predictor of risk-adjusted morbidity and mortality after general surgery. A preoperative serum creatinine of 1.5 mg/dL or higher is a readily available marker for potential adverse outcomes after general surgery

Effects of elevated temperature on high performance concrete incorporating of metakaolin and garnet

Durability has become one of the major indicators to dictate a good quality of concrete. Rapid growing in construction leads to the demand of high strength concrete which can bear high stress and high resistance towards any hazard and harsh environment thus providing a safe structure. High performance concrete (HPC) has been identified as one of the advanced types of concrete that can fulfill the criteria. Hence, in this study resistance towards elevated temperature of HPC incorporating 10% of metakaolin as part of cementitious material and 50% of garnet as part of replacement of fine aggregates were investigated. Samples of HPC with metakaolin and garnet (HPCMG) and HPC with metakaolin (HPCM) were exposed to different heating temperature of 200°C, 400°C, 600°C and 800°C for duration of one hour. The changes of physical in color and the appearances of cracks in all samples were closely observed. In addition, compressive strength tests according to BS1881-116:1983 and percentage of weight loss for all the samples were also monitored in this study. Results showed that as the temperature increased, significance losses of compressive strength were detected for both HPCMG and HPCM. At the temperature of 800°C, HPCMG degenerated 86.8% of its strength compared to 71.8% for HPCM. As temperature increased, weight loss of HPCM indicated higher reading compared to HPCMG. Major changes of the physical appearances were also detected in both HPCM and HPCGM samples such as cracks and increment in gap width on the samples. This summarized that HPCM has better fire resistance compared to HPCMG

Newly isolated alkane hydroxylase and lipase producing Geobacillus and Anoxybacillus species involved in crude oil degradation

Isolation and studies of novel, crude oil biodegrading thermophilic strains may provide a wider knowledge in understanding their role in petroleum degradation. In this study, the screening of ten new thermophilic strains revealed that all strains were alkane hydroxylase producers and seven of them produced lipase concurrently. Three best strains were characterized and identified through 16S rRNA sequence analysis as Geobacillus sp. D4, Geobacillus sp. D7, and Anoxybacillus geothermalis D9 with GenBank accession numbers MK615934.1, MK615935.1, and MK615936.1, respectively. Gas chromatography (GC) analysis showed that all three strains were able to breakdown various compounds in crude oil such as alkanes, toxic poly-aromatic hydrocarbons (PAHs), organosulfur, carboxylic acids, alkene, resins, organosilicon, alcohol, organochlorine, and ester. For the first time, alkane hydroxylase and lipase activity as well as crude oil degradation by A. geothermalis species were reported. Geobacillus sp. D7 is the best alkane degrader followed by A. geothermalis D9 and Geobacillus sp. D4 with 17.3%, 13.1%, and 12.1% biodegradation efficiency (BE%), respectively. The potential of thermophiles isolated can be explored further for bioremediation of sites polluted by petroleum and oil spills