Biofouling on forward osmosis system

Fouling is an inevitable issue that all membrane systems have to face. The presence of membrane fouling causes membrane systems (such as reverse osmosis and forward osmosis) to suffer the increase of resistance thus reducing the efficiency of the systems. This raises concerns about the osmosis technology as it also reduces the system and membrane lifetime while increasing the maintenance costs. From previous papers and literature review, polysaccharides were found to be the main contributor to membrane fouling. The literature explains the polysaccharides that caused the membrane fouling were alginate, BSA, AHA, xanthan and others however, only alginate and xanthan were tested in this research project. The mixing interaction of other cations such as Ca2+ with some of the aforementioned polysaccharides (salt in the form of CaCl2 and NaCl were also tested to see the changes in fouling effects when both are combined. Throughout the experiments, a fixed amount of NaCl and CaCl2 and the polysaccharide were kept constant. The draw solution (NaCl mixed with DI water) was always retained to be saturated. These experiments were designed in this way to examine the differences between each polysaccharide and its combination towards fouling behaviour, since alginate and xanthan have different chemical characteristics. The results show that xanthan causes a higher resistance compared to alginate. In the case where NaCl and CaCl2 were present in the feed solution, the resistance of both polysaccharides greatly increases thus resulting in lowering the flux and ultimately decreasing the system efficiency. Out of all the experiments, the xanthan with salt resulted in highest flux decrease while the alginate only had the least flux decline (excluding the baseline experiment). Further analysis was done using the total organic carbon (TOC) and confocal laser scanning microscopy (CLSM). These examinations demonstrated the characteristics and properties of the polysaccharide layers that were formed on the membrane surface. The CLSM result was compared with the flux and resistance movement and it was found that they supported each other (and the findings were closely related). Since CLSM analysis is able to show the x, y and z dimension, the thickness can be found within each CLSM images. Therefore the thickness of the polysaccharide (fouling) layer (from CLSM images) was thick and/or dense, the (a higher resistance was achieved) higher the resistance would be and vice versa

Complete coding sequence characterization and comparative analysis of the putative novel human rhinovirus (HRV) species C and B

<p>Abstract</p> <p>Background</p> <p>Human Rhinoviruses (HRVs) are well recognized viral pathogens associated with acute respiratory tract illnesses (RTIs) abundant worldwide. Although recent studies have phylogenetically identified the new HRV species (HRV-C), data on molecular epidemiology, genetic diversity, and clinical manifestation have been limited.</p> <p>Result</p> <p>To gain new insight into HRV genetic diversity, we determined the complete coding sequences of putative new members of HRV species C (HRV-CU072 with 1% prevalence) and HRV-B (HRV-CU211) identified from clinical specimens collected from pediatric patients diagnosed with a symptom of acute lower RTI. Complete coding sequence and phylogenetic analysis revealed that the HRV-CU072 strain shared a recent common ancestor with most closely related Chinese strain (N4). Comparative analysis at the protein level showed that HRV-CU072 might accumulate substitutional mutations in structural proteins, as well as nonstructural proteins 3C and 3 D. Comparative analysis of all available HRVs and HEVs indicated that HRV-C contains a relatively high G+C content and is more closely related to HEV-D. This might be correlated to their replication and capability to adapt to the high temperature environment of the human lower respiratory tract. We herein report an infrequently occurring intra-species recombination event in HRV-B species (HRV-CU211) with a crossing over having taken place at the boundary of VP2 and VP3 genes. Moreover, we observed phylogenetic compatibility in all HRV species and suggest that dynamic mechanisms for HRV evolution seem to be related to recombination events. These findings indicated that the elementary units shaping the genetic diversity of HRV-C could be found in the nonstructural 2A and 3D genes.</p> <p>Conclusion</p> <p>This study provides information for understanding HRV genetic diversity and insight into the role of selection pressure and recombination mechanisms influencing HRV evolution.</p

Molecular Evolution of Human H1N1 and H3N2 Influenza A Virus in Thailand, 2006–2009

Annual seasonal influenza outbreaks are associated with high morbidity and mortality.To index and document evolutionary changes among influenza A H1N1 and H3N2 viruses isolated from Thailand during 2006-2009, using complete genome sequences.Nasopharyngeal aspirates were collected from patients diagnosed with respiratory illness in Thailand during 2006-2009. All samples were screened for Influenza A virus. A total of 13 H1N1 and 21 H3N2 were confirmed and whole genome sequenced for the evolutionary analysis using standard phylogenetic approaches.Phylogenetic analysis of HA revealed a clear diversification of seasonal from vaccine strain lineages. H3N2 seasonal clusters were closely related to the WHO recommended vaccine strains in each season. Most H1N1 isolates could be differentiated into 3 lineages. The A/Brisbane/59/2007 lineage, a vaccine strain for H1N1 since 2008, is closely related with the H1N1 subtypes circulating in 2009. HA sequences were conserved at the receptor-binding site. Amino acid variations in the antigenic site resulted in a possible N-linked glycosylation motif. Recent H3N2 isolates had higher genetic variations compared to H1N1 isolates. Most substitutions in the NP protein were clustered in the T-cell recognition domains.In this study we performed evolutionary genetic analysis of influenza A viruses in Thailand between 2006-2009. Although the current vaccine strain is efficient for controlling the circulating outbreak subtypes, surveillance is necessary to provide unambiguous information on emergent viruses. In summary, the findings of this study contribute the understanding of evolution in influenza A viruses in humans and is useful for routine surveillance and vaccine strain selection

Genetic variations of nucleoprotein gene of influenza A viruses isolated from swine in Thailand

<p>Abstract</p> <p>Background</p> <p>Influenza A virus causes severe disease in both humans and animals and thus, has a considerably impact on economy and public health. In this study, the genetic variations of the nucleoprotein (NP) gene of influenza viruses recovered from swine in Thailand were determined.</p> <p>Results</p> <p>Twelve influenza A virus specimens were isolated from Thai swine. All samples were subjected to nucleotide sequencing of the complete NP gene. Phylogenetic analysis was conducted by comparing the NP gene of swine influenza viruses with that of seasonal and pandemic human viruses and highly pathogenic avian viruses from Thailand (n = 77). Phylogenetic analysis showed that the NP gene from different host species clustered in distinct host specific lineages. The NP gene of swine influenza viruses clustered in either Eurasian swine or Classical swine lineages. Genetic analysis of the NP gene suggested that swine influenza viruses circulating in Thailand display 4 amino acids unique to Eurasian and Classical swine lineages. In addition, the result showed 1 and 5 amino acids unique to avian and human lineages, respectively. Furthermore, nucleotide substitution rates showed that the NP gene is highly conserved especially in avian influenza viruses.</p> <p>Conclusion</p> <p>The NP gene sequence of influenza A in Thailand is highly conserved within host-specific lineages and shows amino acids potentially unique to distinct NP lineages. This information can be used to investigate potential interspecies transmission of influenza A viruses. In addition, the genetic variations of the NP gene will be useful for monitoring the viruses and preparing effective prevention and control strategies for potentially pandemic influenza outbreaks.</p

Influenza Virus (H5N1) in Live Bird Markets and Food Markets, Thailand

A surveillance program for influenza A viruses (H5N1) was conducted in live bird and food markets in central Thailand during July 2006–August 2007. Twelve subtype H5N1 viruses were isolated. The subtype H5N1 viruses circulating in the markets were genetically related to those that circulated in Thailand during 2004–2005

Genetic characterization of 2008 reassortant influenza A virus (H5N1), Thailand

In January and November 2008, outbreaks of avian influenza have been reported in 4 provinces of Thailand. Eight Influenza A H5N1 viruses were recovered from these 2008 AI outbreaks and comprehensively characterized and analyzed for nucleotide identity, genetic relatedness, virulence determinants, and possible sites of reassortment. The results show that the 2008 H5N1 viruses displayed genetic drift characteristics (less than 3% genetic differences), as commonly found in influenza A viruses. Based on phylogenetic analysis, clade 1 viruses in Thailand were divided into 3 distinct branches (subclades 1, 1.1 and 1.2). Six out of 8 H5N1 isolates have been identified as reassorted H5N1 viruses, while other isolates belong to an original H5N1 clade. These viruses have undergone inter-lineage reassortment between subclades 1.1 and 1.2 and thus represent new reassorted 2008 H5N1 viruses. The reassorted viruses have acquired gene segments from H5N1, subclade 1.1 (PA, HA, NP and M) and subclade 1.2 (PB2, PB1, NA and NS) in Thailand. Bootscan analysis of concatenated whole genome sequences of the 2008 H5N1 viruses supported the reassortment sites between subclade 1.1 and 1.2 viruses. Based on estimating of the time of the most recent common ancestors of the 2008 H5N1 viruses, the potential point of genetic reassortment of the viruses could be traced back to 2006. Genetic analysis of the 2008 H5N1 viruses has shown that most virulence determinants in all 8 genes of the viruses have remained unchanged. In summary, two predominant H5N1 lineages were circulating in 2008. The original CUK2-like lineage mainly circulated in central Thailand and the reassorted lineage (subclades 1.1 and 1.2) predominantly circulated in lower-north Thailand. To prevent new reassortment, emphasis should be put on prevention of H5N1 viruses circulating in high risk areas. In addition, surveillance and whole genome sequencing of H5N1 viruses should be routinely performed for monitoring the genetic drift of the virus and new reassorted strains, especially in light of potential reassortment between avian and mammalian H5N1 viruses

Esterification of fatty acids from waste cooking oil to biodiesel over a sulfonated resin/PVA composite

Sulfonated cation exchange resins (s-CERs) have been widely studied as a replacement of liquid acids for the catalysis of esterification of free fatty acids (FFAs) to produce biodiesel with water as the only by-product. However, the water produced has strong affinity to sulfonate groups in s-CERs, which block the reactive sites for esterification and thus reduce the activity of a catalyst. To overcome this technical barrier, we have designed an s-CER/PVA composite by incorporating s-CER fines within a poly(vinyl alcohol) (PVA) matrix. PVA has a much stronger absorption preference for water than s-CERs and has very low selectivity for reactants (FFAs and methanol), which enables continuous removal of the produced water and liberation of reactive sulfonate sites in s-CERs for catalysis. With s-CER/PVA, FFA conversion was increased from 80.1% to 97.5% after an 8-hour reaction and the turnover frequency (TOF) was increased more than 3.3 times. The TOF of s-CER/PVA was also 2.6 times higher than that of sulfuric acid, suggesting that water-less, heterogeneous sulfonate sites are more reactive than water-blocked homogeneous ones. The reusability of s-CER/PVA was also enhanced due to the fact that the produced water that could cause deactivation of the s-CERs was largely removed by PVA