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Fulltext Nasal epithelial cells can act as a physiological surrogate for paediatric asthma studies

Thavagnanam S, Parker JC, McBrien ME, Skibinski G, Shields MD, Heaney LG

PLoS One, 2014;9(1):e85802.
PMID: 24475053 DOI: 10.1371/journal.pone.0085802

Differentiated paediatric epithelial cells can be used to study the role of epithelial cells in asthma. Nasal epithelial cells are easier to obtain and may act as a surrogate for bronchial epithelium in asthma studies. We assessed the suitability of nasal epithelium from asthmatic children to be a surrogate for bronchial epithelium using air-liquid interface cultures.
Fulltext Subtype distribution of Blastocystis isolates in Sebha, Libya

Abdulsalam AM, Ithoi I, Al-Mekhlafi HM, Al-Mekhlafi AM, Ahmed A, Surin J

PLoS One, 2013;8(12):e84372.
PMID: 24376805 DOI: 10.1371/journal.pone.0084372

BACKGROUND: Blastocystis is a genetically diverse and a common intestinal parasite of humans with a controversial pathogenic potential. This study was carried out to identify the Blastocystis subtypes and their association with demographic and socioeconomic factors among outpatients living in Sebha city, Libya.
METHODS/FINDINGS: Blastocystis in stool samples were cultured followed by isolation, PCR amplification of a partial SSU rDNA gene, cloning, and sequencing. The DNA sequences of isolated clones showed 98.3% to 100% identity with the reference Blastocystis isolates from the Genbank. Multiple sequence alignment showed polymorphism from one to seven base substitution and/or insertion/deletion in several groups of non-identical nucleotides clones. Phylogenetic analysis revealed three assemblage subtypes (ST) with ST1 as the most prevalent (51.1%) followed by ST2 (24.4%), ST3 (17.8%) and mixed infections of two concurrent subtypes (6.7%).
BLASTOCYSTIS: ST1 infection was significantly associated with female (P = 0.009) and low educational level (P = 0.034). ST2 was also significantly associated with low educational level (P= 0.008) and ST3 with diarrhoea (P = 0.008).
CONCLUSION: Phylogenetic analysis of Libyan Blastocystis isolates identified three different subtypes; with ST1 being the predominant subtype and its infection was significantly associated with female gender and low educational level. More extensive studies are needed in order to relate each Blastocystis subtype with clinical symptoms and potential transmission sources in this community.
Fulltext Optimal homotopy asymptotic method for flow and heat transfer of a viscoelastic fluid in an axisymmetric channel with a porous wall

Mabood F, Khan WA, Ismail AI

PLoS One, 2013;8(12):e83581.
PMID: 24376722 DOI: 10.1371/journal.pone.0083581

In this article, an approximate analytical solution of flow and heat transfer for a viscoelastic fluid in an axisymmetric channel with porous wall is presented. The solution is obtained through the use of a powerful method known as Optimal Homotopy Asymptotic Method (OHAM). We obtained the approximate analytical solution for dimensionless velocity and temperature for various parameters. The influence and effect of different parameters on dimensionless velocity, temperature, friction factor, and rate of heat transfer are presented graphically. We also compared our solution with those obtained by other methods and it is found that OHAM solution is better than the other methods considered. This shows that OHAM is reliable for use to solve strongly nonlinear problems in heat transfer phenomena.
Fulltext The significance of HIV 'blips' in resource-limited settings: is it the same? analysis of the treat Asia HIV Observational Database (TAHOD) and the Australian HIV Observational Database (AHOD)

Kanapathipillai R, McManus H, Kamarulzaman A, Lim PL, Templeton DJ, Law M, et al.

PLoS One, 2014;9(2):e86122.
PMID: 24516527 DOI: 10.1371/journal.pone.0086122

INTRODUCTION: Magnitude and frequency of HIV viral load blips in resource-limited settings, has not previously been assessed. This study was undertaken in a cohort from a high income country (Australia) known as AHOD (Australian HIV Observational Database) and another cohort from a mixture of Asian countries of varying national income per capita, TAHOD (TREAT Asia HIV Observational Database).
METHODS: Blips were defined as detectable VL (≥ 50 copies/mL) preceded and followed by undetectable VL (<50 copies/mL). Virological failure (VF) was defined as two consecutive VL ≥50 copies/ml. Cox proportional hazard models of time to first VF after entry, were developed.
RESULTS: 5040 patients (AHOD n = 2597 and TAHOD n = 2521) were included; 910 (18%) of patients experienced blips. 744 (21%) and 166 (11%) of high- and middle/low-income participants, respectively, experienced blips ever. 711 (14%) experienced blips prior to virological failure. 559 (16%) and 152 (10%) of high- and middle/low-income participants, respectively, experienced blips prior to virological failure. VL testing occurred at a median frequency of 175 and 91 days in middle/low- and high-income sites, respectively. Longer time to VF occurred in middle/low income sites, compared with high-income sites (adjusted hazards ratio (AHR) 0.41; p<0.001), adjusted for year of first cART, Hepatitis C co-infection, cART regimen, and prior blips. Prior blips were not a significant predictor of VF in univariate analysis (AHR 0.97, p = 0.82). Differing magnitudes of blips were not significant in univariate analyses as predictors of virological failure (p = 0.360 for blip 50-≤1000, p = 0.309 for blip 50-≤400 and p = 0.300 for blip 50-≤200). 209 of 866 (24%) patients were switched to an alternate regimen in the setting of a blip.
CONCLUSION: Despite a lower proportion of blips occurring in low/middle-income settings, no significant difference was found between settings. Nonetheless, a substantial number of participants were switched to alternative regimens in the setting of blips.
Fulltext Spatial structure of seagrass suggests that size-dependent plant traits have a strong influence on the distribution and maintenance of tropical multispecies meadows

Ooi JL, Van Niel KP, Kendrick GA, Holmes KW

PLoS One, 2014;9(1):e86782.
PMID: 24497978 DOI: 10.1371/journal.pone.0086782

Seagrass species in the tropics occur in multispecies meadows. How these meadows are maintained through species co-existence and what their ecological drivers may be has been an overarching question in seagrass biogeography. In this study, we quantify the spatial structure of four co-existing species and infer potential ecological processes from these structures.
Fulltext Analyses of hypomethylated oil palm gene space

Low ET, Rosli R, Jayanthi N, Mohd-Amin AH, Azizi N, Chan KL, et al.

PLoS One, 2014;9(1):e86728.
PMID: 24497974 DOI: 10.1371/journal.pone.0086728

Demand for palm oil has been increasing by an average of ∼8% the past decade and currently accounts for about 59% of the world's vegetable oil market. This drives the need to increase palm oil production. Nevertheless, due to the increasing need for sustainable production, it is imperative to increase productivity rather than the area cultivated. Studies on the oil palm genome are essential to help identify genes or markers that are associated with important processes or traits, such as flowering, yield and disease resistance. To achieve this, 294,115 and 150,744 sequences from the hypomethylated or gene-rich regions of Elaeis guineensis and E. oleifera genome were sequenced and assembled into contigs. An additional 16,427 shot-gun sequences and 176 bacterial artificial chromosomes (BAC) were also generated to check the quality of libraries constructed. Comparison of these sequences revealed that although the methylation-filtered libraries were sequenced at low coverage, they still tagged at least 66% of the RefSeq supported genes in the BAC and had a filtration power of at least 2.0. A total 33,752 microsatellites and 40,820 high-quality single nucleotide polymorphism (SNP) markers were identified. These represent the most comprehensive collection of microsatellites and SNPs to date and would be an important resource for genetic mapping and association studies. The gene models predicted from the assembled contigs were mined for genes of interest, and 242, 65 and 14 oil palm transcription factors, resistance genes and miRNAs were identified respectively. Examples of the transcriptional factors tagged include those associated with floral development and tissue culture, such as homeodomain proteins, MADS, Squamosa and Apetala2. The E. guineensis and E. oleifera hypomethylated sequences provide an important resource to understand the molecular mechanisms associated with important agronomic traits in oil palm.
Fulltext Shifting baselines on a tropical forest frontier: extirpations drive declines in local ecological knowledge

Kai Z, Woan TS, Jie L, Goodale E, Kitajima K, Bagchi R, et al.

PLoS One, 2014;9(1):e86598.
PMID: 24466163 DOI: 10.1371/journal.pone.0086598

The value of local ecological knowledge (LEK) to conservation is increasingly recognised, but LEK is being rapidly lost as indigenous livelihoods change. Biodiversity loss is also a driver of the loss of LEK, but quantitative study is lacking. In our study landscape in SW China, a large proportion of species have been extirpated. Hence, we were interested to understand whether species extirpation might have led to an erosion of LEK and the implications this might have for conservation. So we investigated peoples' ability to name a selection of birds and mammals in their local language from pictures. Age was correlated to frequency of forest visits as a teenager and is likely to be closely correlated to other known drivers of the loss of LEK, such as declining forest dependence. We found men were better at identifying birds overall and that older people were better able to identify birds to the species as compared to group levels (approximately equivalent to genus). The effect of age was also stronger among women. However, after controlling for these factors, species abundance was by far the most important parameter in determining peoples' ability to name birds. People were unable to name any locally extirpated birds at the species level. However, contrary to expectations, people were better able to identify extirpated mammals at the species level than extant ones. However, extirpated mammals tend to be more charismatic species and several respondents indicated they were only familiar with them through TV documentaries. Younger people today cannot experience the sights and sounds of forest animals that their parents grew up with and, consequently, knowledge of these species is passing from cultural memory. We suggest that engaging older members of the community and linking the preservation of LEK to biodiversity conservation may help generate support for conservation.
Fulltext Ohmic-rectifying conversion of Ni contacts on ZnO and the possible determination of ZnO thin film surface polarity

Saw KG, Tneh SS, Tan GL, Yam FK, Ng SS, Hassan Z

PLoS One, 2014;9(1):e86544.
PMID: 24466144 DOI: 10.1371/journal.pone.0086544

The current-voltage characteristics of Ni contacts with the surfaces of ZnO thin films as well as single crystal (0001) ZnO substrate are investigated. The ZnO thin film shows a conversion from Ohmic to rectifying behavior when annealed at 800°C. Similar findings are also found on the Zn-polar surface of (0001) ZnO. The O-polar surface, however, only shows Ohmic behavior before and after annealing. The rectifying behavior observed on the Zn-polar and ZnO thin film surfaces is associated with the formation of nickel zinc oxide (Ni1-xZnxO, where x = 0.1, 0.2). The current-voltage characteristics suggest that a p-n junction is formed by Ni1-xZnxO (which is believed to be p-type) and ZnO (which is intrinsically n-type). The rectifying behavior for the ZnO thin film as a result of annealing suggests that its surface is Zn-terminated. Current-voltage measurements could possibly be used to determine the surface polarity of ZnO thin films.
Fulltext RNA-Seq analysis provides insights for understanding photoautotrophic polyhydroxyalkanoate production in recombinant Synechocystis Sp

Lau NS, Foong CP, Kurihara Y, Sudesh K, Matsui M

PLoS One, 2014;9(1):e86368.
PMID: 24466058 DOI: 10.1371/journal.pone.0086368

The photosynthetic cyanobacterium, Synechocystis sp. strain 6803, is a potential platform for the production of various chemicals and biofuels. In this study, direct photosynthetic production of a biopolymer, polyhydroxyalkanoate (PHA), in genetically engineered Synechocystis sp. achieved as high as 14 wt%. This is the highest production reported in Synechocystis sp. under photoautotrophic cultivation conditions without the addition of a carbon source. The addition of acetate increased PHA accumulation to 41 wt%, and this value is comparable to the highest production obtained with cyanobacteria. Transcriptome analysis by RNA-seq coupled with real-time PCR was performed to understand the global changes in transcript levels of cells subjected to conditions suitable for photoautotrophic PHA biosynthesis. There was lower expression of most PHA synthesis-related genes in recombinant Synechocystis sp. with higher PHA accumulation suggesting that the concentration of these enzymes is not the limiting factor to achieving high PHA accumulation. In order to cope with the higher PHA production, cells may utilize enhanced photosynthesis to drive the product formation. Results from this study suggest that the total flux of carbon is the possible driving force for the biosynthesis of PHA and the polymerizing enzyme, PHA synthase, is not the only critical factor affecting PHA-synthesis. Knowledge of the regulation or control points of the biopolymer production pathways will facilitate the further use of cyanobacteria for biotechnological applications.
Fulltext Severity-based adaptation with limited data for ASR to aid dysarthric speakers

Mustafa MB, Salim SS, Mohamed N, Al-Qatab B, Siong CE

PLoS One, 2014;9(1):e86285.
PMID: 24466004 DOI: 10.1371/journal.pone.0086285

Automatic speech recognition (ASR) is currently used in many assistive technologies, such as helping individuals with speech impairment in their communication ability. One challenge in ASR for speech-impaired individuals is the difficulty in obtaining a good speech database of impaired speakers for building an effective speech acoustic model. Because there are very few existing databases of impaired speech, which are also limited in size, the obvious solution to build a speech acoustic model of impaired speech is by employing adaptation techniques. However, issues that have not been addressed in existing studies in the area of adaptation for speech impairment are as follows: (1) identifying the most effective adaptation technique for impaired speech; and (2) the use of suitable source models to build an effective impaired-speech acoustic model. This research investigates the above-mentioned two issues on dysarthria, a type of speech impairment affecting millions of people. We applied both unimpaired and impaired speech as the source model with well-known adaptation techniques like the maximum likelihood linear regression (MLLR) and the constrained-MLLR(C-MLLR). The recognition accuracy of each impaired speech acoustic model is measured in terms of word error rate (WER), with further assessments, including phoneme insertion, substitution and deletion rates. Unimpaired speech when combined with limited high-quality speech-impaired data improves performance of ASR systems in recognising severely impaired dysarthric speech. The C-MLLR adaptation technique was also found to be better than MLLR in recognising mildly and moderately impaired speech based on the statistical analysis of the WER. It was found that phoneme substitution was the biggest contributing factor in WER in dysarthric speech for all levels of severity. The results show that the speech acoustic models derived from suitable adaptation techniques improve the performance of ASR systems in recognising impaired speech with limited adaptation data.
Fulltext Design and characterization of a 52K SNP chip for goats

Tosser-Klopp G, Bardou P, Bouchez O, Cabau C, Crooijmans R, Dong Y, et al.

PLoS One, 2014;9(1):e86227.
PMID: 24465974 DOI: 10.1371/journal.pone.0086227

The success of Genome Wide Association Studies in the discovery of sequence variation linked to complex traits in humans has increased interest in high throughput SNP genotyping assays in livestock species. Primary goals are QTL detection and genomic selection. The purpose here was design of a 50-60,000 SNP chip for goats. The success of a moderate density SNP assay depends on reliable bioinformatic SNP detection procedures, the technological success rate of the SNP design, even spacing of SNPs on the genome and selection of Minor Allele Frequencies (MAF) suitable to use in diverse breeds. Through the federation of three SNP discovery projects consolidated as the International Goat Genome Consortium, we have identified approximately twelve million high quality SNP variants in the goat genome stored in a database together with their biological and technical characteristics. These SNPs were identified within and between six breeds (meat, milk and mixed): Alpine, Boer, Creole, Katjang, Saanen and Savanna, comprising a total of 97 animals. Whole genome and Reduced Representation Library sequences were aligned on >10 kb scaffolds of the de novo goat genome assembly. The 60,000 selected SNPs, evenly spaced on the goat genome, were submitted for oligo manufacturing (Illumina, Inc) and published in dbSNP along with flanking sequences and map position on goat assemblies (i.e. scaffolds and pseudo-chromosomes), sheep genome V2 and cattle UMD3.1 assembly. Ten breeds were then used to validate the SNP content and 52,295 loci could be successfully genotyped and used to generate a final cluster file. The combined strategy of using mainly whole genome Next Generation Sequencing and mapping on a contig genome assembly, complemented with Illumina design tools proved to be efficient in producing this GoatSNP50 chip. Advances in use of molecular markers are expected to accelerate goat genomic studies in coming years.
Fulltext CoryneBase: Corynebacterium genomic resources and analysis tools at your fingertips

Heydari H, Siow CC, Tan MF, Jakubovics NS, Wee WY, Mutha NV, et al.

PLoS One, 2014;9(1):e86318.
PMID: 24466021 DOI: 10.1371/journal.pone.0086318

Corynebacteria are used for a wide variety of industrial purposes but some species are associated with human diseases. With increasing number of corynebacterial genomes having been sequenced, comparative analysis of these strains may provide better understanding of their biology, phylogeny, virulence and taxonomy that may lead to the discoveries of beneficial industrial strains or contribute to better management of diseases. To facilitate the ongoing research of corynebacteria, a specialized central repository and analysis platform for the corynebacterial research community is needed to host the fast-growing amount of genomic data and facilitate the analysis of these data. Here we present CoryneBase, a genomic database for Corynebacterium with diverse functionality for the analysis of genomes aimed to provide: (1) annotated genome sequences of Corynebacterium where 165,918 coding sequences and 4,180 RNAs can be found in 27 species; (2) access to comprehensive Corynebacterium data through the use of advanced web technologies for interactive web interfaces; and (3) advanced bioinformatic analysis tools consisting of standard BLAST for homology search, VFDB BLAST for sequence homology search against the Virulence Factor Database (VFDB), Pairwise Genome Comparison (PGC) tool for comparative genomic analysis, and a newly designed Pathogenomics Profiling Tool (PathoProT) for comparative pathogenomic analysis. CoryneBase offers the access of a range of Corynebacterium genomic resources as well as analysis tools for comparative genomics and pathogenomics. It is publicly available at http://corynebacterium.um.edu.my/.
Fulltext Judging the difference between attractiveness and health: does exposure to model images influence the judgments made by men and women?

Stephen ID, Perera AT

PLoS One, 2014;9(1):e86302.
PMID: 24466014 DOI: 10.1371/journal.pone.0086302

Recent research has shown facial adiposity (apparent weight in the face) to be a significant predictor of both attractiveness and health, thus making it an important determinant of mate selection. Studies looking at the relationship between attractiveness and health have shown that individuals differentiate between the two by preferring a lower weight for attractiveness than for health in female faces. However, these studies have either been correlational studies, or have investigated weight perceived from only the face. These differences have been discussed with regard to sociocultural factors such as pressure from parents, peers and also media, which has been seen to have the highest influence. While exposure to media images has been shown to influence women's own-body image, no study has yet directly tested the influence of these factors on people's preferred weight in other women's bodies. Here we examine how a short exposure to images of models influences men's and women's judgments of the most healthy looking and attractive BMI in Malaysian Chinese women's bodies by comparing differences in preferences (for attractiveness and health) between groups exposed to images of models of varying attractiveness and body weight. Results indicated that participants preferred a lower weight for attractiveness than for health. Further, women's but not men's preferred BMI for attractiveness, but not health, was influenced by the type of media images to which they were exposed, suggesting that short term exposure to model images affect women's perceptions of attractiveness but not health.
Fulltext Inhibition of oxidative stress and lipid peroxidation by anthocyanins from defatted Canarium odontophyllum pericarp and peel using in vitro bioassays

Khoo HE, Azlan A, Ismail A, Abas F, Hamid M

PLoS One, 2014;9(1):e81447.
PMID: 24416130 DOI: 10.1371/journal.pone.0081447

Canarium odontophyllum, also known as CO, is a highly nutritious fruit. Defatted parts of CO fruit are potent sources of nutraceutical. This study aimed to determine oxidative stress and lipid peroxidation effects of defatted CO pericarp and peel extracts using in vitro bioassays. Cell cytotoxic effect of the CO pericarp and peel extracts were also evaluated using HUVEC and Chang liver cell lines. The crude extracts of defatted CO peel and pericarp showed cytoprotective effects in t-BHP and 40% methanol-induced cell death. The crude extracts also showed no toxic effect to Chang liver cell line. Using CD36 ELISA, NAD(+) and LDL inhibition assays, inhibition of oxidative stress were found higher in the crude extract of defatted CO peel compared to the pericarp extract. Hemoglobin and LDL oxidation assays revealed both crude extracts had significantly reduced lipid peroxidation as compared to control. TBARS values among defatted CO pericarp, peel, and cyanidin-3-glucoside showed no significant differences for hemoglobin and LDL oxidation assays. The protective effects of defatted CO parts, especially its peel is related to the presence of high anthocyanin that potentially offers as a pharmaceutical ingredient for cardioprotection.
Fulltext The correlates of body composition with heart rate recovery after step test: an exploratory study of Malaysian adolescents

Abu Hanifah R, Mohamed MN, Jaafar Z, Mohsein NA, Jalaludin MY, Majid HA, et al.

PLoS One, 2013;8(12):e82893.
PMID: 24349388 DOI: 10.1371/journal.pone.0082893

BACKGROUND: In adults, heart rate recovery is a predictor of mortality, while in adolescents it is associated with cardio-metabolic risk factors. The aim of this study was to examine the relationship between body composition measures and heart rate recovery (HRR) after step test in Malaysian secondary school students.
METHODS: In the Malaysian Health and Adolescents Longitudinal Research Team (MyHEART) study, 1071 healthy secondary school students, aged 13 years old, participated in the step test. Parameters for body composition measures were body mass index z-score, body fat percentage, waist circumference, and waist height ratio. The step test was conducted by using a modified Harvard step test. Heart rate recovery of 1 minute (HRR1min) and heart rate recovery of 2 minutes (HRR2min) were calculated by the difference between the peak pulse rate during exercise and the resting pulse rate at 1 and 2 minutes, respectively. Analysis was done separately based on gender. Pearson correlation analysis was used to determine the association between the HRR parameters with body composition measures, while multiple regression analysis was used to determine which body composition measures was the strongest predictor for HRR.
RESULTS: For both gender groups, all body composition measures were inversely correlated with HRR1min. In girls, all body composition measures were inversely correlated with HRR2min, while in boys all body composition measures, except BMI z-score, were associated with HRR2min. In multiple regression, only waist circumference was inversely associated with HRR2min (p=0.024) in boys, while in girls it was body fat percentage for HRR2min (p=0.008).
CONCLUSION: There was an inverse association between body composition measurements and HRR among apparently healthy adolescents. Therefore, it is important to identify cardio-metabolic risk factors in adolescent as an early prevention of consequent adulthood morbidity. This reiterates the importance of healthy living which should start from young.
Fulltext Eating behaviour among multi-ethnic adolescents in a middle-income country as measured by the self-reported Children's Eating Behaviour Questionnaire

Loh DA, Moy FM, Zaharan NL, Mohamed Z

PLoS One, 2013;8(12):e82885.
PMID: 24349385 DOI: 10.1371/journal.pone.0082885

Escalating weight gain among the Malaysian paediatric population necessitates identifying modifiable behaviours in the obesity pathway.
Fulltext Influence of lifestyle factors on mammographic density in postmenopausal women

Brand JS, Czene K, Eriksson L, Trinh T, Bhoo-Pathy N, Hall P, et al.

PLoS One, 2013;8(12):e81876.
PMID: 24349146 DOI: 10.1371/journal.pone.0081876

BACKGROUND: Mammographic density is a strong risk factor for breast cancer. Apart from hormone replacement therapy (HRT), little is known about lifestyle factors that influence breast density.
METHODS: We examined the effect of smoking, alcohol and physical activity on mammographic density in a population-based sample of postmenopausal women without breast cancer. Lifestyle factors were assessed by a questionnaire and percentage and area measures of mammographic density were measured using computer-assisted software. General linear models were used to assess the association between lifestyle factors and mammographic density and effect modification by body mass index (BMI) and HRT was studied.
RESULTS: Overall, alcohol intake was positively associated with percent mammographic density (P trend = 0.07). This association was modified by HRT use (P interaction = 0.06): increasing alcohol intake was associated with increasing percent density in current HRT users (P trend = 0.01) but not in non-current users (P trend = 0.82). A similar interaction between alcohol and HRT was found for the absolute dense area, with a positive association being present in current HRT users only (P interaction = 0.04). No differences in mammographic density were observed across categories of smoking and physical activity, neither overall nor in stratified analyses by BMI and HRT use.
CONCLUSIONS: Increasing alcohol intake is associated with an increase in mammography density, whereas smoking and physical activity do not seem to influence density. The observed interaction between alcohol and HRT may pose an opportunity for HRT users to lower their mammographic density and breast cancer risk.
Fulltext Pathogenicity of a microsporidium isolate from the diamondback moth against Noctuid moths: characterization and implications for microbiological pest management

Ghani IA, Dieng H, Abu Hassan ZA, Ramli N, Kermani N, Satho T, et al.

PLoS One, 2013;8(12):e81642.
PMID: 24349104 DOI: 10.1371/journal.pone.0081642

Due to problems with chemical control, there is increasing interest in the use of microsporidia for control of lepidopteran pests. However, there have been few studies to evaluate the susceptibility of exotic species to microsporidia from indigenous Lepidoptera.
Fulltext Enzymatic characterization of insecticide resistance mechanisms in field populations of Malaysian Culex quinquefasciatus say (Diptera: Culicidae)

Low VL, Chen CD, Lee HL, Tan TK, Chen CF, Leong CS, et al.

PLoS One, 2013;8(11):e79928.
PMID: 24278220 DOI: 10.1371/journal.pone.0079928

There has been no comprehensive study on biochemical characterization of insecticide resistance mechanisms in field populations of Malaysian Culex quinquefasciatus. To fill this void in the literature, a nationwide investigation was performed to quantify the enzyme activities, thereby attempting to characterize the potential resistance mechanisms in Cx. quinquefasciatus in residential areas in Malaysia.
Fulltext Comparative reliability studies and analysis of Au, Pd-coated Cu and Pd-doped Cu wire in microelectronics packaging

Chong Leong G, Uda H

PLoS One, 2013;8(11):e78705.
PMID: 24244344 DOI: 10.1371/journal.pone.0078705

This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (Pd) coated Cu and Pd-doped Cu wires used in fineline Ball Grid Array (BGA) package. Intermetallic compound (IMC) thickness measurement has been carried out to estimate the coefficient of diffusion (Do) under various aging conditions of different bonding wires. Wire pull and ball bond shear strengths have been analyzed and we found smaller variation in Pd-doped Cu wire compared to Au and Pd-doped Cu wire. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of Cu. The obtained weibull slope, β of three bonding wires are greater than 1.0 and belong to wearout reliability data point. Pd-doped Cu wire exhibits larger time-to-failure and cycles-to-failure in both wearout reliability tests in Highly Accelerated Temperature and Humidity (HAST) and Temperature Cycling (TC) tests. This proves Pd-doped Cu wire has a greater potential and higher reliability margin compared to Au and Pd-coated Cu wires.

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