Bamboo fibers with high mechanical properties can be a sustainable alternative to synthetic fiber... more Bamboo fibers with high mechanical properties can be a sustainable alternative to synthetic fibers for application in fiber reinforced polymer composites. The first aim of this study is to evaluate the dependence of mechanical properties of Dendrocalamus asper, known as bamboo Petung from Indonesia, on physical properties of the culm, including culm diameter, wall thickness, height, moisture content and specific density. Correlations between mechanical properties including tensile strength, modulus of rupture and modulus of elasticity in flexure and tension and culm physical properties have been studied. The results demonstrate that specific density is directly correlated with all these mechanical properties of bamboo while the moisture content values are correlated only with value of modules of rupture. Although wall thicknesses value of the culm are correlated with all of the mechanical properties studied, the culm diameter was only correlated with modulus of rupture and modulus of elasticity in flexure. Therefore, measurements of the culm geometry and specific density of raw bamboo have the potential for rapid, non-destructive evaluations of the quality of the bamboo, particularly in nurseries and forests where there is limited access to testing facilities. The second aim of this study is to evaluate whether such tests allow for an evaluation of the mechanical potential of the bamboo for production of high performance bamboo fiber reinforced polymer composites. Use of these formulas is illustrated through a case study of bamboo composite reinforcement for structural concrete. Pull-out tests and beam testing using this composite successfully validate the usefulness of this strategy for sustainable construction.
Transparent exopolymer particles (TEP) are a class of particulate extracellular polymeric substan... more Transparent exopolymer particles (TEP) are a class of particulate extracellular polymeric substances bigger than 0.4 µm which are ubiquitous in most marine and freshwater environments. Because of their unique physicochemical properties, interest in the role of TEP in membrane fouling has significantly increased. In this study, the potential contribution of TEP and their precursors (<0.4 µm) to reverse osmosis (RO) membrane biofouling in the NEWater plant which is high-grade reclaimed water has been investigated. To measure the bio-adhesive effect of TEP and their precursors, a preliminary study was performed by growing biofilms of Pseudomonas aeruginosa as a model microorganism on surfaces conditioned with water samples from different stages of the NEWater process. The results showed a significant increase in biofilm formation on surfaces conditioned with higher amounts of pseudo-TEP precursors as a class TEP materials smaller than 0.4 µm but bigger than 0.2 µm. Our findings indicate the bio-adhesive effect of pseudo-TEP precursors in the early stages of biofilm formation on RO membranes. Therefore, pre-filtration of smaller size TEP materials prior to the RO membrane could potentially mitigate the biofouling in desalination plants.
and spp. are significant contributors to the global waterborne disease burden. Waterways used as ... more and spp. are significant contributors to the global waterborne disease burden. Waterways used as sources of drinking water and for recreational activity can become contaminated through the introduction of fecal materials derived from humans and animals. Multiple studies have reported the occurence or concentrations of these pathogens in the environment. However, this information has not been comprehensively reviewed. Quantitative microbial risk assessment (QMRA) for and can be beneficial, but it often relies on the concentrations in environmental sources reported from the literature. A thorough literature review was conducted to develop an inventory of reported and concentrations in wastewater and surface water available in the literature. This information can be used to develop QMRA inputs. and (oo)cyst concentrations in untreated wastewater were up to 60,000 oocysts L and 100,000 cysts L, respectively. The maximum reported concentrations for and in surface water were 8400 oocysts ...
Applied and environmental microbiology, Jan 15, 2018
This study evaluated the geospatial distribution of fecal indicator bacteria (FIB) (i.e., , spp.)... more This study evaluated the geospatial distribution of fecal indicator bacteria (FIB) (i.e., , spp.) and the alternative fecal indicator pepper mild mottle virus (PMMoV) in tropical freshwater environments under different land use patterns. Results show that the occurrence and concentration of microbial fecal indicators were higher for urban than for parkland-dominated areas, consistent with land use weightage. Significant positive correlations with traditional FIB indicate that PMMoV is a suitable indicator of fecal contamination in tropical catchments waters (0.549 ≤ rho ≤ 0.612; < 0.01). PMMoV exhibited a strong significant correlation with land use weightage (rho = 0.728; < 0.01) compared to traditional FIB (rho = 0.583; < 0.01). In addition, chemical tracers were also added to evaluate the potential relationships with microbial fecal indicators. The relationships between diverse variables (e.g., environmental parameters, land use coverage, and chemical tracers) and the oc...
Stormwater contamination can threaten the health of aquatic ecosystems and human exposed to runof... more Stormwater contamination can threaten the health of aquatic ecosystems and human exposed to runoff via nutrient and pathogen influxes. In this study, the concentrations of 11 bacterial pathogens and 47 antibiotic resistance genes (ARGs) were determined by using high-throughput microfluidic qPCR (MFQPCR) in several storm drain outfalls (SDOs) during dry and wet weather in Tampa Bay, Florida, USA. Data generated in this study were also compared with the levels of fecal indicator bacteria (FIB) and sewage-associated molecular markers (i.e., Bacteroides HF183 and crAssphage markers) in same SDOs collected in a recent study (Ahmed et al., 2018). Concentration of FIB, sewage-associated markers, bacterial pathogens and many ARGs in water samples were relatively high and SDOs may be potentially hotspots for microbial contamination in Tampa Bay. Mean concentrations of culturable E. coli and Enterococcus spp. were tenfold higher in wet compared to dry weather. The majority of microbiological ...
Extraction of viral DNA/RNA from environmental samples as part of the analytical procedure in qua... more Extraction of viral DNA/RNA from environmental samples as part of the analytical procedure in quantifying waterborne viruses, is of great importance. In this study, two commercially available kits were compared to assess their performance, the MO BIO PowerViral Environmental DNA/RNA Isolation kit and the Qiagen QIAamp Viral RNA Mini kit. A performance assessment of extraction kits for detecting and quantifying six human enteric viruses as the commonest waterborne pathogens and one plant virus as an alternative fecal indicator has been carried out using quantitative PCR (qPCR). Water samples were collected from seven sites in Singapore during March and April 2015. In general, a strong association was observed between two different viral DNA/RNA extraction kits and detection frequency of targets (P = 0.017). The Qiagen kit showed higher extraction efficiency than the MoBio kit. However, in terms of quantification, a significant difference was only observed in the occurrences of NoV GI...
Hepatitis A virus (HAV) infection has caused substantial morbidity and economic losses to human s... more Hepatitis A virus (HAV) infection has caused substantial morbidity and economic losses to human society, presenting a major public health problem in many parts of the world. Despite the capability for low-concentration detection, current PCR-based techniques are limited by the requirement of specialized lab equipment, trained personnel and a relatively large time-commitment. The need for a prompt in-field quantitative identification of HAV in real samples has led us to develop a chemiluminescent fibre optic genosensor system. In this study, a two-probe sandwich-type hybridization process was implemented on the tip of a fibre optic with an area of 0.12mm(2). After optimization of the probes and the working conditions, we showed that the biosensor was able to work for both cDNA and RNA with a relatively large signal/noise ratio and a good sensitivity. An excellent specificity was also confirmed by screening with a broad range of other pathogen samples. The nucleic acid probes method w...
Bamboo fibers with high mechanical properties can be a sustainable alternative to synthetic fiber... more Bamboo fibers with high mechanical properties can be a sustainable alternative to synthetic fibers for application in fiber reinforced polymer composites. The first aim of this study is to evaluate the dependence of mechanical properties of Dendrocalamus asper, known as bamboo Petung from Indonesia, on physical properties of the culm, including culm diameter, wall thickness, height, moisture content and specific density. Correlations between mechanical properties including tensile strength, modulus of rupture and modulus of elasticity in flexure and tension and culm physical properties have been studied. The results demonstrate that specific density is directly correlated with all these mechanical properties of bamboo while the moisture content values are correlated only with value of modules of rupture. Although wall thicknesses value of the culm are correlated with all of the mechanical properties studied, the culm diameter was only correlated with modulus of rupture and modulus of elasticity in flexure. Therefore, measurements of the culm geometry and specific density of raw bamboo have the potential for rapid, non-destructive evaluations of the quality of the bamboo, particularly in nurseries and forests where there is limited access to testing facilities. The second aim of this study is to evaluate whether such tests allow for an evaluation of the mechanical potential of the bamboo for production of high performance bamboo fiber reinforced polymer composites. Use of these formulas is illustrated through a case study of bamboo composite reinforcement for structural concrete. Pull-out tests and beam testing using this composite successfully validate the usefulness of this strategy for sustainable construction.
Transparent exopolymer particles (TEP) are a class of particulate extracellular polymeric substan... more Transparent exopolymer particles (TEP) are a class of particulate extracellular polymeric substances bigger than 0.4 µm which are ubiquitous in most marine and freshwater environments. Because of their unique physicochemical properties, interest in the role of TEP in membrane fouling has significantly increased. In this study, the potential contribution of TEP and their precursors (<0.4 µm) to reverse osmosis (RO) membrane biofouling in the NEWater plant which is high-grade reclaimed water has been investigated. To measure the bio-adhesive effect of TEP and their precursors, a preliminary study was performed by growing biofilms of Pseudomonas aeruginosa as a model microorganism on surfaces conditioned with water samples from different stages of the NEWater process. The results showed a significant increase in biofilm formation on surfaces conditioned with higher amounts of pseudo-TEP precursors as a class TEP materials smaller than 0.4 µm but bigger than 0.2 µm. Our findings indicate the bio-adhesive effect of pseudo-TEP precursors in the early stages of biofilm formation on RO membranes. Therefore, pre-filtration of smaller size TEP materials prior to the RO membrane could potentially mitigate the biofouling in desalination plants.
and spp. are significant contributors to the global waterborne disease burden. Waterways used as ... more and spp. are significant contributors to the global waterborne disease burden. Waterways used as sources of drinking water and for recreational activity can become contaminated through the introduction of fecal materials derived from humans and animals. Multiple studies have reported the occurence or concentrations of these pathogens in the environment. However, this information has not been comprehensively reviewed. Quantitative microbial risk assessment (QMRA) for and can be beneficial, but it often relies on the concentrations in environmental sources reported from the literature. A thorough literature review was conducted to develop an inventory of reported and concentrations in wastewater and surface water available in the literature. This information can be used to develop QMRA inputs. and (oo)cyst concentrations in untreated wastewater were up to 60,000 oocysts L and 100,000 cysts L, respectively. The maximum reported concentrations for and in surface water were 8400 oocysts ...
Applied and environmental microbiology, Jan 15, 2018
This study evaluated the geospatial distribution of fecal indicator bacteria (FIB) (i.e., , spp.)... more This study evaluated the geospatial distribution of fecal indicator bacteria (FIB) (i.e., , spp.) and the alternative fecal indicator pepper mild mottle virus (PMMoV) in tropical freshwater environments under different land use patterns. Results show that the occurrence and concentration of microbial fecal indicators were higher for urban than for parkland-dominated areas, consistent with land use weightage. Significant positive correlations with traditional FIB indicate that PMMoV is a suitable indicator of fecal contamination in tropical catchments waters (0.549 ≤ rho ≤ 0.612; < 0.01). PMMoV exhibited a strong significant correlation with land use weightage (rho = 0.728; < 0.01) compared to traditional FIB (rho = 0.583; < 0.01). In addition, chemical tracers were also added to evaluate the potential relationships with microbial fecal indicators. The relationships between diverse variables (e.g., environmental parameters, land use coverage, and chemical tracers) and the oc...
Stormwater contamination can threaten the health of aquatic ecosystems and human exposed to runof... more Stormwater contamination can threaten the health of aquatic ecosystems and human exposed to runoff via nutrient and pathogen influxes. In this study, the concentrations of 11 bacterial pathogens and 47 antibiotic resistance genes (ARGs) were determined by using high-throughput microfluidic qPCR (MFQPCR) in several storm drain outfalls (SDOs) during dry and wet weather in Tampa Bay, Florida, USA. Data generated in this study were also compared with the levels of fecal indicator bacteria (FIB) and sewage-associated molecular markers (i.e., Bacteroides HF183 and crAssphage markers) in same SDOs collected in a recent study (Ahmed et al., 2018). Concentration of FIB, sewage-associated markers, bacterial pathogens and many ARGs in water samples were relatively high and SDOs may be potentially hotspots for microbial contamination in Tampa Bay. Mean concentrations of culturable E. coli and Enterococcus spp. were tenfold higher in wet compared to dry weather. The majority of microbiological ...
Extraction of viral DNA/RNA from environmental samples as part of the analytical procedure in qua... more Extraction of viral DNA/RNA from environmental samples as part of the analytical procedure in quantifying waterborne viruses, is of great importance. In this study, two commercially available kits were compared to assess their performance, the MO BIO PowerViral Environmental DNA/RNA Isolation kit and the Qiagen QIAamp Viral RNA Mini kit. A performance assessment of extraction kits for detecting and quantifying six human enteric viruses as the commonest waterborne pathogens and one plant virus as an alternative fecal indicator has been carried out using quantitative PCR (qPCR). Water samples were collected from seven sites in Singapore during March and April 2015. In general, a strong association was observed between two different viral DNA/RNA extraction kits and detection frequency of targets (P = 0.017). The Qiagen kit showed higher extraction efficiency than the MoBio kit. However, in terms of quantification, a significant difference was only observed in the occurrences of NoV GI...
Hepatitis A virus (HAV) infection has caused substantial morbidity and economic losses to human s... more Hepatitis A virus (HAV) infection has caused substantial morbidity and economic losses to human society, presenting a major public health problem in many parts of the world. Despite the capability for low-concentration detection, current PCR-based techniques are limited by the requirement of specialized lab equipment, trained personnel and a relatively large time-commitment. The need for a prompt in-field quantitative identification of HAV in real samples has led us to develop a chemiluminescent fibre optic genosensor system. In this study, a two-probe sandwich-type hybridization process was implemented on the tip of a fibre optic with an area of 0.12mm(2). After optimization of the probes and the working conditions, we showed that the biosensor was able to work for both cDNA and RNA with a relatively large signal/noise ratio and a good sensitivity. An excellent specificity was also confirmed by screening with a broad range of other pathogen samples. The nucleic acid probes method w...
Uploads
Papers by Nazanin Saeidi