Synthesis and Characterization of Tannin Based Porous Cation Exchange Resins from Cassia auriculata (Ranawara)

Tannins are one of the most abundant compounds in the nature. Naturally tannins have ion exchanging capability. Conversely, tannins are highly water soluble compounds, thus natural tannins cannot be used as ion exchangers. In this study, tannins extracted from Cassia auriculata (Ranawara) were used to synthesise renewable tannin based porous cation exchange resin systems. Essentially, the applicability of these resin systems as an ion exchange resin were considered. Identification of the Tannin was carried out by using ferric chloride test, nitrous acid test and acid butanol tests. Total polyphenolic content of Cassia auriculata was 13.30% (w/w) and it was calculated by using Folin-ciocalteau method. Tannin-Formaldehyde resin was prepared, and the ion exchange capacity was measured. Then the Tannin-Formaldehyde resin was sulfonated to increase the ion exchange capacity by refluxing with concentrated H2SO4. Then, the ion exchange capacity of the resin was further increased by introducing a porous structure using virgin coconut oil as the porogenic agent. Ion exchange capacity, solubility, Fourier transform infrared spectroscopy and scanning electron microscopy analysis were used to characterise the resin systems. The modified resin with high fraction of surfactant contains mostly open porous structures and it has the highest IEC (0.9550 meq/g) among the synthesized resin systems.Keywords: Cassia auriculata (Ranawara), porous tannin-formaldehyde cation exchange resin, ion exchange capacity, FTIR, SE

Relational Agency as a Dialectic of Belonging and Not Belonging within the Social Ecology of Plantation Life in Sri Lanka

We argue that lived spaces play a crucial role in influencing how people can or cannot enact their agency. Based on an interpretive ethnographic study of work in a large Sri Lankan tea plantation and drawing on the conceptual lenses of relational agency and social ecology, we explore how workers experience their ability to act agentically in relation to their social circumstances and examine the personal and social consequences. In doing so, we extend conceptualizations of relational agency as a dialectic of belonging and not belonging within a social ecology – an ongoing flow of intertwined activities and ways of being and relating to each other that create and reproduce social orders and forms of accountability

Thermal Analysis of Cellulose Fibres Extracted from Locally Available Rice Straw

Agriculture sector plays a vital role in Sri Lankan economy. Although the country is moving towards industrialisation, the agricultural sector still contributes substantially to both foreign exchange earnings and GDP. Paddy is cultivated in almost all parts of the country, except at very high altitudes. In 2018, around 3.9 million metric tonnes of paddy was harvested across the country from both Yala and Maha seasons. Rice straw is a by-product from the paddy cultivation and identified as agricultural production residue that is generated in equal or greater quantities than the rice itself with no commercial interest. Therefore, it is of ecological and economical point of view to discover an advantageous utilization of this material. Agricultural crop residues are rich in lignocellulosic materials with cellulose as the principle constituent. Study on the thermal properties of rice straw fibers are important in order to estimate their industrial applications. In this study, cellulose fibers were extracted from rice straw (BG352) via a series of chemical treatments. The structure and chemical composition of cellulose fibers were investigated using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Thermal stability of each sample was determined using TGA SDT Q600 simultaneous thermal analyser (TA instruments, Delaware, USA). Analysis of individual samples was carried out at a constant heating rate of 10 °C/min between ambient temperature to 700o C in a nitrogen atmosphere. FTIR analysis of fibers demonstrate that the chemical purification treatment results in sequential and complete removal of hemicellulose (1729 cm-1, carbonyl stretching), lignin (1516 cm-1, aromatic skeletal vibrations) and silica (796 cm-1 and 466 cm-1, Si–O–Si stretching). XRD results also reveal the removal of lignin (shoulder peak at 16.4o) and hemicellulose (weak peak at 34.76o) from rice straw thus, confirms the final product as cellulose. Three endothermic peaks were observed in thermogravimetric analysis. Initially a small weight loss was observed around 100o C due to the low molecular weight components in the fibers and the evaporation of remained moisture. Hemicellulose pyrolysis was occurred around 260o C. A resistant increase in cellulose was observed due to the removal of almost all hemicelluloses from the rice straw. Pyrolysis of lignin in rice straw started at 200o C and persisted till 700o C. Further, a significant difference between the contents of the residues were remained which indicated that the thermal stability of cellulose was visibly improved. Based on the results obtained, the extracted cellulose fibers from locally available rice straw could be used to produce textiles, composites, all kinds of paper and paper boards, photographic films, moisture proof coatings for food packaging and other fibrous products similar to those produced from the synthetic fibers. Using rice straw as a source of high-quality fibrous applications will add value to the rice crops, mitigate concerns regarding burning or disposing of rice straw, and provide an environmentally friendly alternative to replace the synthetic fibers currently in use.Keywords: Sri Lankan rice straw, Cellulose fibers, Chemical treatment, Thermal decomposition, Thermal propertie

Characteristics of community acquired and hospital acquired methicillin resistant Staphylococcus aureus isolates in the National Hospital of Sri Lanka

Introduction and Objectives: Highly virulent community acquired methicillin resistant Staphylococcus aureus (MRSA) strains emerged recently causing infections in healthy young adults without predisposing factors. This descriptive cross-sectional study was conducted to compare socio-demography of patients and microbiology and molecular characteristics of Community acquired (CA) and Hospital acquired (HA) methicillin resistant S. aureus strains isolated at the National Hospital of Sri Lanka.Methods and Results: Antimicrobial susceptibility test and Panton Valentine Leukocidine (PVL) gene detection was carried out on 100 MRSA isolates. CDC epidemiological criteria were used for differentiation of CA and HA MRSA. Of those 100 isolates, 21(21%) were CA-MRSA and 79(79%) were HA-MRSA. Patients did not show any significant difference in acquiring CA MRSA and HA MRSA in relation to their age, sex and gender except ethnicity. The majority of these isolates were from pus samples. CA-MRSA isolates were significantly more sensitive to ciprofloxacin, fusidic acid, tetracycline, cotrimoxazole, and gentamicin compared with HA-MRSA isolates (p&lt;0.001). Inducible, constitutive clindamycin resistance (p&lt;0.001) and multidrug resistant phenotypes were significantly higher (p&lt;0.001) among patients with HA-MRSA infection. All isolates were susceptible to glycopeptides, rifampicin and linezolid. Mupirocin resistance was seen in 6% and all isolates came from patients who harboured HA-MRSA strains (p&lt;0.338). The PVL gene (P&lt;0.001) was present in 20 (95.2%) of CA-MRSA isolates.Conclusion: This study highlights the importance of accurate differentiation of CA and HA MRSA using epidemiological, microbiological and molecular characteristics. Further, awareness of the existence of these types will optimise individual treatment strategies.</p

Fabrication of Nanofibrillated Cellulose (NFC) Based Composite Materials for Engineering Applications

Nanomaterials play an important role as modern engineering materials for various engineering, medical and biological applications today. Nanocellulose is a natural polymeric fiber that has a minimum of one dimension within the nanometer scale and exhibits a potential as a reinforcement agent for various materials. Nanocellulose can be extracted from plant materials such as agricultural, agro-industrial and forestry wastes. They are divided into two main classes as nanofibrillated cellulose (NFC) and nanocrystalline cellulose (NCC). Compared to NCC, NFC has gained a considerable attention because of the interesting properties including high mechanical properties, reinforcing ability and aspect ratio. Combination of NFC with synthetic polymer materials is an interesting area in the polymer-based researches to enhance mechanical and thermal properties of the composite. These natural plant based composites deplete the environmental pollution created by traditional synthetic polymers. Polypropylene is a widely used thermoplastic material in engineering composite applications as a matrix material. The objective of this research was to fabricate a polypropylene and NFC based composite material. In nature, NFC is hydrophilic and polypropylene is hydrophobic. Therefore, modification of NFC surface is necessary to prepare a nanocomposite with a better performance. In the present research analyzed the mechanical, thermal, water absorption and processability properties of polypropylene-NFC-based composite with up to 5 wt.% loading of unmodified silane (Si-69) and silane (Si-69) surface modified NFC reinforced composites. The characterization of raw materials and the composites were performed using SEM, FTIR, XRD, TGA and DTA techniques. In addition, the mechanical properties of composites were evaluated by using a universal testing machine and hardness tester. Further, the melt flow rate and water absorption properties of the developed products were evaluated using standard test methods. The best thermal resistance and mechanical properties were given by the 3.5 wt.% of silane surface modified NFC loaded polypropylene composite including tensile strength (28 MPa), hardness (78 Shore D) and impact strength (4 kJ m-2) and these values are 7%, 13%, and 86% higher than that of the pure polypropylene respectively. In addition, the composite sample has the intermediate level of water absorption (0.1 wt. %) and processability (21.1 g/10 min) with respect to all the other fabricated samples including pure polypropylene. The prepared nanocomposite material can be used for many engineering applications such as packaging, constructions, automotive and aerospace as a sustainable material.Keywords: Nanofibrillated cellulose, Polypropylene, Surface modification, Nanocomposit

Using Social Media to Promote STEM Education: Matching College Students with Role Models

STEM (Science, Technology, Engineering, and Mathematics) fields have become increasingly central to U.S. economic competitiveness and growth. The shortage in the STEM workforce has brought promoting STEM education upfront. The rapid growth of social media usage provides a unique opportunity to predict users' real-life identities and interests from online texts and photos. In this paper, we propose an innovative approach by leveraging social media to promote STEM education: matching Twitter college student users with diverse LinkedIn STEM professionals using a ranking algorithm based on the similarities of their demographics and interests. We share the belief that increasing STEM presence in the form of introducing career role models who share similar interests and demographics will inspire students to develop interests in STEM related fields and emulate their models. Our evaluation on 2,000 real college students demonstrated the accuracy of our ranking algorithm. We also design a novel implementation that recommends matched role models to the students.Comment: 16 pages, 8 figures, accepted by ECML/PKDD 2016, Industrial Trac

Extraction and Characterisation of Cellulose Materials from Sri Lankan Agricultural Waste

Agriculture is a key sector of Sri Lankan economy today. Sri Lanka’s main food crop is rice. Rice is cultivated mainly in two seasons in the country. Rice production is the predominant form of agriculture which occupies 0.77 million hectares of the total cultivated area in Sri Lanka. Nevertheless, generation of enormous amounts of agricultural residues such as rice straw during rice production has become inevitable According to the statistics it is revealed that one ton of rice paddy produces 290 kg of rice straw. Regardless of these large amounts, rice straw is frequently abolished by open field burning by majority of farmers. However, recent researchers have reported that rice straw burning can be lethal towards human health due to the noxious emissions which cause various forms of environmental pollution. Hence, identifying the means of generating value added products by utilisation of rice straw has become a necessity today. Rice straw is a lingo cellulosic biomass which consists of biopolymers of cellulose, hemicellulose and lignin. Cellulose is the mostly abundant organic polymer on earth that can be identified as one of the most demanded advanced materials in engineering applications such as bio composites production. Therefore, developing a method to isolate cellulose from rice straw would be a convenient means of value addition to the agricultural waste. This research work is based on developing an environmentally friendly, efficient method to synthesise cellulose from rice straws of the most frequently cultivated hybrid rice variety (BG352) in Sri Lanka. BG 352 rice variety is cultivated in most of the areas in Sri Lanka today. High purity cellulose was extracted from rice straw by the removal of non-cellulosic materials. This chemical purification process consisted of dewaxing, delignification and hemicellulose and silica removal treatments. FTIR spectroscopy was used to verify the formation of pure cellulose during the extraction process. Further, morphology of extracted cellulose was studied by SEM analysis. It revealed that isolated cellulose was mostly in the form of fibers with diameters ranging from 2-8μm. This research showed that BG352 variety averagely has 16.1 wt.% wax, 38.2 wt.% lignin, 3.9% wt. hemicellulose and 12.3 wt.% silica content. Ultimately, average cellulose yield from rice straws of BG352 variety was observed as 30 wt.%. This extraction process can be used to synthesis the cellulose from Sri Lankan agricultural waste to convert it into a value added product.Keywords: Rice straw, Agricultural waste, Cellulose, Lignocellulosic, Biopolyme

Modeling of longitudinal polytomous outcome from complex survey data - application to investigate an association between mental distress and non-malignant respiratory diseases

<p>Abstract</p> <p>Background</p> <p>The data from longitudinal complex surveys based on multi-stage sampling designs contain cross-sectional dependencies among units due to clustered nature of the data and within-subject dependencies due to repeated measurements. Special statistical methods are required to analyze longitudinal complex survey data.</p> <p>Methods</p> <p>Statistics Canada's longitudinal National Population Health Survey (NPHS) dataset from the first five cycles (1994/1995 to 2002/2003) was used to investigate the effects of demographic, social, life-style, and health-related factors on the longitudinal changes of mental distress scores among the NPHS participants who self-reported physician diagnosed respiratory diseases, specifically asthma and chronic bronchitis. The NPHS longitudinal sample includes 17,276 persons of all ages. In this report, participants 15 years and older (n = 14,713) were considered for statistical analysis. Mental distress, an ordinal outcome variable (categories: no/low, moderate, and high) was examined. Ordered logistic regression models based on the weighted generalized estimating equations approach were fitted to investigate the association between respiratory diseases and mental distress adjusting for other covariates of interest. Variance estimates of regression coefficients were computed by using bootstrap methods. The final model was used to predict the probabilities of prevalence of no/low, moderate or high mental distress scores.</p> <p>Results</p> <p>Accounting for design effects does not vary the significance of the coefficients of the model. Participants suffering with chronic bronchitis were significantly at a higher risk (OR_adj= 1.37; 95% CI: 1.12-1.66) of reporting high levels of mental distress compared to those who did not self-report chronic bronchitis. There was no significant association between asthma and mental distress. There was a significant interaction between sex and self-perceived general health status indicating a dose-response relationship. Among females, the risk of mental distress increases with increasing deteriorating (from excellent to very poor) self-perceived general health.</p> <p>Conclusions</p> <p>A positive association was observed between the physician diagnosed self-reported chronic bronchitis and an increased prevalence of mental distress when adjusted for important covariates. Variance estimates of regression coefficients obtained from the sandwich estimator (i.e. not accounting for design effects) were similar to bootstrap variance estimates (i.e. accounting for design effects). Even though these two sets of variance estimates are similar, it is more appropriate to use bootstrap variance estimates.</p

Ethnicity and incidence of Hodgkin lymphoma in Canadian population

<p>Abstract</p> <p>Background</p> <p>Research has shown that ethnicity is a significant predictor of Hodgkin lymphoma (HL). Variations in cancer incidence among ethnic groups in the same country can lead to important information in the search for etiological factors. Other risk factors important in the etiology of HL are medical history and exposure to pesticides. In this report we investigated the association between ethnicity and HL in the presence of medical history, and exposure to pesticides.</p> <p>Methods</p> <p>The data resulting from a matched population-based case-control study conducted in six provinces of Canada (Ontario, Quebec, Manitoba, Saskatchewan, Alberta, and British Columbia) was analyzed to determine whether or not there was any association between ethnicity and incidence of HL when adjusted for personal medical history and pesticide exposure. Information on ethnicity, personal medical history, and pesticide exposure was collected by questionnaires via mail on 316 men diagnosed with HL; and on 1506 controls. A conditional logistic regression was utilized and results were presented as odds ratios and 95% confidence intervals.</p> <p>Results</p> <p>In our study population, the distribution of ethnic groups was: 38.5% North American, 15% British, 8.4% Western European, 8.2% Eastern European, 1.7% Asian, 1.4% Scandinavian and 27% of other ethnic origin. Compared to North Americans (i) the risk of HL was greater among the Eastern European descendents (Odds Ratio (OR_adj): 1.82; 95% confidence interval (CI): 1.02, 3.25) and Western European (OR_adj: 1.62; 95% CI: 0.95–2.76) descent population (borderline significance at 5% level); and (ii) the risk of HL was lower in Asian descents. Diagnosis with measles (OR_adj: 0.72, 95% C.I.: 0.53–0.98) and/or positive history of allergy desensitization shots (OR_adj: 0.55, 95% C.I.: 0.30–0.99) were negatively associated with the incidence of HL, while diagnosis with acne (OR_adj: 2.12, 95% C.I.: 1.19–3.78), shingles (OR_adj: 2.41, 95% C.I.: 1.38–4.22) and positive family history of cancer (OR_adj: 1.93, 95% C.I.: 1.40–2.65) increased the risk of HL. Exposure to individual herbicide dichlorprop showed an increased risk of HL (OR_adj: 6.35, 95% C.I.: 1.56–25.92).</p> <p>Conclusion</p> <p>In Canada, compared to North Americans descendents, the risk of HL was significantly greater among the Eastern European and Western European descent population. Our results related to association between ethnicity and HL support the findings reported by other researchers. Our data showed that subjects who were diagnosed with measles or had allergy desensitization shots negatively associated with the incidence of HL; and other medical conditions, ever diagnosed with acne, and positive family history of cancer were positively associated with the incidence of HL.</p