MECHANICAL AND THERMAL PROPERTIES OF NANO-AL2O3/NYLON 6 COMPOSITES

Nano-Al₂O₃-reinforced monomer casting nylon (NA/MCN) composites were prepared by using in situ polymerization. The average molecular weight of the matrix nylon was measured using gel permeation chromatography. The thermal-mechanical properties of the NA/MCN composites were characterized by thermo-dynamic mechanical analysis, and the results were compared with micro-Al₂O₃-reinforced nylon (MA/MCN) composites. A tensile property test was conducted to investigate the mechanical properties of neat nylon and composites. Experimental results showed that the average molecular weight of the matrix nylon filled with nano-alumina had little change and was higher than that with micro-alumina. The glass transition temperature (T_g) and storage moduli of NA/MCN composites were higher than that of neat nylon. During the experiment, it was also found that the tensile strength increased up to 52% when 3 wt.% of nano-Al₂O₃ particles were added. The thermal and tensile properties of NA/MCN composites were better than those of the MA/MCN composites when the same weight percentage of Al₂O₃ particles was used.     

Healthy campus by open space design: Approaches and guidelines

This paper examines the architectural and landscape design strategies and intentions for green, open spaces facilities targeting stress alleviation for learning environments such as those of university campuses in a compact urban setting. Literature reviews provide three prevailing perspectives for physical design pedagogical operatives: healing gardens where greenery and plants produce restorative effects; flexible spaces that accommodate functional needs of different activities; and green buildings that incorporate open space as a catalyst for integrated eco-system. Corresponding design approaches (landscape design, spatial design and green design) are scrutinized by case study. A comparison of two university campuses with different urban contexts is conducted to identify challenges and opportunities for applying these design approaches. For a compact campus, high-dense surroundings may limit the size of an open space and may handicap circulation and accessibility; on the other side, a small open space may provide its users more intimate contact with natural restorative elements and also a more controllable microclimate for physical comfort. A healthy campus should encompass diverse open spaces to satisfy different purposes. Finally, a framework that integrates the three approaches is combined to produce a sustainable design rubric.     

Host-specific 16S rRNA gene markers of Bacteroidales for source tracking of fecal pollution in the subtropical coastal seawater of Hong Kong

This study investigated the diversity of Bacteroidales communities in the feces of eight host species in Hong Kong (subtropical Asia), including human (in the form of sewage), cow, pig, horse, cat, dog, rabbit and rat. The analysis of terminal restriction fragment length polymorphism (TRFLP) in the 16S rRNA genes revealed significant differences in Bacteroidales communities among all host species, with the exception of dog and cat. Manual examination of TRFLP profiles resulted in six terminal restriction fragments (TRFs) that were potentially specific to the sewage (one TRF), cow (three TRFs) or pig (two TRFs) samples. All six TRFs were (1) present in 100% of the samples of the respective target host, (2) absent in other hosts or present only in low frequency and low intensity, and (3) verified for sizes using in silico digestion of DNA sequences in clone libraries. The six TRFs could reliably indicate the source of fecal contaminations in natural seawater amended with sewage, cow or pig fecal samples. In field tests conducted for two polluted and one unpolluted coastal site, the sewage-specific TRF was detected in all seawater samples of the sites known to be impacted by raw and treated sewage. However, only two of three cow-specific TRFs were detected for the two polluted sites, which also received fecal input from feral cows. No pig-specific TRF was detected, although one of the coastal sites was chronically polluted by pig farm run-offs. Nevertheless, the total absence of the six potentially host-specific TRFs in the seawater of an unpolluted site demonstrated the specificity of the TRFs as gene markers in indicating actual pollution.     

Design, assembly and reliability of large die and fine-pitch Cu/low-k flip chip package

This paper reports the design, assembly and reliability assessment of 21 × 21 mm² Cu/low-k flip chip (65 nm node) with 150 μm bump pitch and high bump density. To reduce the stress from the solder bump pad to low-k layers, Metal Redistribution Layer (RDL) and Polymer Encapsulated Dicing Lane (PEDL) are applied to the Cu/low-k wafer. Lead-free Sn2.5Ag, high-lead Pb5Sn and Cu-post/Sn37Pb bumps are evaluated as the first-level interconnects. It is found that the flip chip assembly of high-lead bumped test vehicle requires the right choice of flux and good alignment between the high-lead solder bumps and substrate pre-solder alloy to ensure proper solder bump and substrate pre-solder alloy wetting. Joint Electron Device Engineering Council (JEDEC) standard reliability is performed on the test vehicle with different first-level interconnects, underfill materials and PEDL.By integrating PEDL to the Cu/low-k chip, the reliability performance of the flip chip package has been improved by almost two times. This paper has demonstrated Moisture Sensitivity Test-Level 2 (MST-L2) qualified large die and fine-pitch Cu/low-k flip chip package. The presented results are significant for the development of flip chip packaging technologies for future advanced Cu/low-k generations.     

A comparative study on the energy policies in Japan and Malaysia in fulfilling their nations’ obligations towards the Kyoto Protocol

Global warming and the associated changes in the world climate pattern have been accepted world wide as the gravest threat to humanity in the 20th century. To mitigate the impacts of global warming, the Kyoto Protocol was established in 1997 with the objective of reducing global greenhouse gases (GHGs) emission, in particular carbon dioxide (CO₂), by 5.2% below 1990 levels. Developed nations that ratified the Protocol are committed to GHG reduction targets while developing nations are encouraged to reduce GHG emissions on a voluntary basis. Since most of the GHGs emissions come from the energy sector, energy policy plays an important role in fulfilling the Kyoto Protocol obligations. This year marks the beginning of the commitment period for the 2012 Kyoto Protocol. In this case, it would be worthwhile to compare the energy policies in Malaysia and Japan as these nations move towards fulfilling their obligations towards the Kyoto Protocol; bearing in mind that both countries ratified the Protocol, but that Japan commits a reduction target of 6% while Malaysia bears no obligation. Based on the comparison, recommendations were made on how a developing nation like Malaysia could adopt the policies implemented in Japan to suit local conditions and contribute significantly to GHG reduction.     

Growth and Characterizations of GaN-Based LEDs Grown on Wet-Etched Stripe-Patterned Sapphire Substrates

The material and electrical properties of GaN-based light-emitting diodes (LEDs) grown on wet-etched stripe-patterned substrates were investigated. Footprint-like patterns, located directly above the inclined groove sidewalls, were found on the as-grown LED surface. Cross-sectional transmission electron microscopy (TEM) showed that ‘tumor’-like structures with poor crystal quality were initiated on the inclined sidewalls, seeding dislocation bundles in the subsequently grown crystal. The high dislocation density slowed down the growth above the inclined sidewall, resulting in the uneven morphology. The fabricated devices showed over 30% enhancement in light output power as a result of improvements in both internal and extraction efficiencies.     

Precipitation and growth of zinc sulfide nanoparticles in the presence of thiol-containing natural organic ligands

In sulfidic aquatic systems, metal sulfides can control the mobility and bioavailability of trace metal pollutants such as zinc, mercury, and silver. Nanoparticles of ZnS and other metal sulfides are known to exist in oxic and anoxic waters. However, the processes that lead to their persistence in the aquatic environment are relatively unknown. The objective of this study was to evaluate the importance of dissolved natural organics in stabilizing nanoparticulate ZnS that precipitates under environmentally relevant conditions. Precipitation and growth of ZnS particles were investigated in the presence of dissolved humic acid and low-molecular weight organic acids that are prevalent in sediment porewater. Dynamic light scattering was used to monitor the hydrodynamic diameter of particles precipitating in laboratory solutions. Zn speciation was also measured by filtering the ZnS solutions (< 0.2 microm) and using anodic stripping voltammetry to confirm that Zn was coordinated to sulfide during the precipitation experiments and not to the dissolved organic ligands. X-ray photoelectron spectroscopy and electron microscopy were used to confirm that amorphous particles containing Zn and S were precipitating in the suspensions. Observed growth rates of ZnS particles varied by orders of magnitude, depending on the type and concentration of organic ligand in solution. In the presence of humic acid and thiol-containing ligands (cysteine, glutathione, and thioglycolate), observed growth rates decreased by 1-3 orders of magnitude relative to controls without the ligands. In contrast, growth rates of the particles were consistently within 1 order of magnitude of the ligand-free control when oxygen- and amine-containing ligands (oxalate, serine, and glycolate) were present Furthermore, particle growth rates decreased with an increase in thiol concentration and increased with NaNO3 electrolyte concentration. These studies suggest that specific surface interactions with thiol-containing organics may be one factor that contributes to the persistence of naturally occurring and anthropogenic nanoparticles of ZnS and other metal sulfides in the aquatic environment.     

An evaluation of the psychometric properties of the Smoking Self-Efficacy Questionnaire (SEQ-12) among Chinese cardiac patients who smoke

Smoking cessation can reduce both morbidity and mortality among patients who have heart disease. China has the largest number of smokers in the world, and most smokers have low motivation to quit. Regular smoking cessation services are almost nonexistent in China, and little is known about the psychometric properties of instruments in assessing smoking self-efficacy in Chinese, whose cultures differ greatly from those of Westerners. The present study tested the psychometric properties of the Chinese version of the Smoking Self-Efficacy Questionnaire (SEQ-12) among 1,841 Chinese smokers who had heart disease, including (a) factorial structure using confirmatory factor analysis, (b) reliability with Cronbach's alpha, (c) concurrent validity, and (d) predictive validity of successful quitting. Confirmatory factor analysis of the SEQ-12 revealed a modified two-factor model that provided a good fit to the data; item 6 ("urge to smoke") was an indicator for the external stimuli subscale rather than for the internal stimuli subscale. Internal consistency coefficients (.77 for external stimuli and .88 for internal stimuli) were acceptable. Baseline self-efficacy scores were significantly associated positively with stage of readiness to quit, and negatively with cigarettes smoked per day and Fagerstrom Test for Nicotine Dependence (FTND) score. Multivariate logistic regression analysis showed that successful quitting at 1 month and at 3 months were predicted by higher external stimuli score, fewer cigarettes smoked per day, lower FTND scores, and being in the intervention group. We concluded that the Chinese version of the SEQ-12 is a valid and reliable instrument for Chinese cardiac patients who smoke. The SEQ-12 can be used to assess smokers' self-efficacy so that appropriate smoking cessation interventions can be provided.     

Daily intake of thiamine correlates with the circulating level of endothelial progenitor cells and the endothelial function in patients with type II diabetes

Our objective was to determine the relationships between levels of different dietary nutrients intake with circulating endothelial progenitor cells (EPC) and vascular endothelial function in type II diabetic patients. We studied the daily dietary nutrients intake, the numbers of circulating CD34(+)/KDR(+) EPC and CD133(+)/KDR(+) EPC and brachial artery flow-mediated dilation (FMD) in 88 diabetic patients without prior cardiovascular diseases and 91 sex- and age-matched controls. Compared with controls, diabetic patients had lower CD133(+)/KDR(+) EPC count (48.3 +/- 5.2 vs. 84.6 +/- 7.6/microL, p < 0.001), CD34(+)/KDR(+) EPC count (311 +/- 41 vs. 412 +/- 36/microL, p = 0.045), and FMD (2.54 +/- 0.37% vs. 5.46 +/- 0.47%, p < 0.001). After adjusted for age, sex, smoking history, body weight, hemoglobin A1c level, total calorie intake, other dietary vitamin intake, use of antihypertensives, and lipid lowering agents, a higher intake of thiamine was significantly associated with a higher level of circulating CD34(+)/KDR(+) EPC (beta = 0.49, p = 0.028) and CD133(+)/KDR(+) EPC (beta = 0.45, p = 0.037) in diabetic patients, but not in controls. Furthermore, an increased intake of thiamine from 1st to 4th quartile in diabetic patients independently predicted an absolute increase in FMD by 1.29% (p = 0.026, relative increase = 63.5%). This study demonstrated that daily thiamine intake was positively correlated with the circulating number of EPCs and FMD in patients with type II diabetes, independent of other dietary nutrients intake.