Hierarchical Macroporous Polymers: Synthesis and Characterisation

This thesis describes the production of two types of hierarchical macroporous polymers using the emulsion templating technique. The first are those with a hierarchy of macroporous, defined as the efficient packing of pores with multi-modal pore size distributions. The second are macroporous polymers containing a hierarchical particulate network, defined by an interconnected particle network within the polymer matrix. In the first section of the thesis, macroporous hierarchy was achieved using 3 different methods. In the first method, the properties of surfactant stabilised high internal phase emulsion (HIPE) were optimised by varying selected emulsification parameters such as the surfactant concentration and stirring rate. The Finite Element Method (FEM) was subsequently used to qualitatively compare and validate the effect of pore hierarchy on the Young’s modulus of macroporous polymers. It was believed that the hierarchical arrangement of macropores facilitated the load transfer during compression, which improved its mechanical properties. The second method involved the use of a mixed surfactant and particle emulsifier system to prepare w/o HIPEs. The mixture of surfactants and particles in the emulsion produced synergistic effects which resulted in a hierarchical macroporous arrangement after polymerisation. The hierarchical porous materials prepared using this method showed high gas permeabilities while maintaining high crush strengths and Young’s moduli compared to ‘conventional’ poly(merised)HIPEs. The improvement in mechanical strength despite the high interconnectivity was attributed to the efficient packing of macropores in a hierarchical configuration. The third approach was to mechanically-froth viscous air in w/o emulsion templates. A bio-based monomer, acrylated epoxidised soyabean oil (AESO) was chosen as a component of the continuous phase of the emulsion for its high viscosity and ability to trap air bubbles during mechanical frothing. Medium Internal Phase Emulsions (MIPEs) containing varying concentrations of AESO were mechanically frothed to incorporate air bubbles, prior to polymerisation. This was found to generate a multi-modal distribution of droplets and air bubbles which polymerised into hierarchical foams with high porosities of up to 81%. In the second section of the thesis, a hierarchical particulate network within the polymer matrix of a porous material was produced using Pickering HIPEs stabilised by varying the concentrations of thermally reduced graphene oxide (rGO) flakes. Macroporous nanocomposites containing 0.006 vol.% of rGO had a conductivity of 1.2 10-5 Sm-1, demonstrating the presence of an interconnected, conducting rGO network within the polymer matrix. The rGO-network created an additional level of hierarchy in these macroporous materials which also improved the overall mechanical properties (viscoelastic properties, Young’s modulus and crush strength).Open Acces

Plasma lipoprotein subfraction concentrations are associated with lipid metabolism and age-related macular degeneration

10.1194/jlr.M073684Journal of Lipid Research5891785-179

Prevalence of microvascular complications in newly diagnosed type 2 diabetes mellitus in primary healthcare clinics

Introduction: Delayed diagnosis of type 2 diabetes mellitus (T2D) increases the risk of presenting late with microvascular complications due to untreated long-standing hyperglycaemia. This study aimed to determine the prevalence of microvascular complications in newly diagnosed T2D patients in primary healthcare clinics. Methods: This was a cross-sectional study carried out in three government primary healthcare clinics in the state of Selangor, Malaysia. Malaysian aged 18 years and above with newly diagnosed T2D (≤ 6 months of diagnosis) were invited to participate in the study. Data collected included the sociodemographic characteristic and the clinical profile (weight, height, waist circumference, blood pressure, lipid, glycaemic, urine albumin, microalbuminuria and renal profile). The assessment of nephropathy, peripheral neuropathy and retinopathy were performed using standard protocol. Multivariate logistic regression analysis was used to identify the significant factors that contribute to the presence of microvascular complications. Results: A total of 162 newly diagnosed patients were recruited. The majority was women (64%). The mean age was 51 (SD 11) years. About one-third of the patients (27.7%) had developed at least one microvascular complication. Nephropathy was the commonest microvascular complication (19.2%), followed by peripheral neuropathy (8.6%) and retinopathy (6.5%). Poor glycaemic control was found to be a significant factor contributing to the presence of microvascular complications (OR 5.8, 95%CI:1.466, 23.288). Conclusion: There is a high prevalence of microvascular complications among the newly diagnosed T2D. There is a need to develop appropriate strategies to increase the awareness and early detection of T2D

Challenges of Learning English in 21st Century: Online vs. Traditional During Covid-19

Free online resources are user-friendly technologies which have become available through the Internet in recent years and gaining popularity during Covid-19. Since learners use smartphones, free online resources are easily accessible. Books are portable, but learners find it somewhat difficult to learn English language via books which may only be available in the classroom context, whereas free online resources are easily accessed. The purpose of this study is to identify learners’ perception learning English via free online resources and traditional learning. Quantitative and qualitative methods were employed in the present study. Twenty-five international pre-elementary intensive English students took part in this study. It was found that learners perceived the free online resources as valuable tools for learning English in relation to reading, conversation, and vocabulary and also free online resources help promote free learning norms in learning the English language. The learners also had constructive attitudes towards free online resources. Free online resources always provide a motivating learning environment, enhance learners’ analytical and critical thinking skills, and encourage social interaction between teachers and learners, learners and their peers, and learners and other participants

Medication adherence, its associated factors and implication on glycaemic control in patients with type 2 diabetes mellitus: A cross-sectional study in a Malaysian primary care clinic

Introduction: Medication adherence and metabolic control remain suboptimal among patients with diabetes mellitus in Malaysia despite the clear benefits of reduced vascular complications and mortality risk. This study examined the factors associated with medication adherence and glycaemic control in patients with type 2 diabetes mellitus in a primary care clinic. Methods: This cross-sectional study was conducted in a public health clinic in Pagoh, Johor, among 386 patients recruited via systematic random sampling. Data were obtained using a validated 7-item structured questionnaire, glycated haemoglobin (HbA1c) test and medical record review. Logistic regression analysis was performed to determine the factors associated with medication adherence. Results: The mean patient age was 60.04±10.75 years, and the mean HbA1c level was 8.3±2.0%. Approximately 60.3% of the participants were adherent to their medication, and an increasing age was significantly associated with medication nonadherence (adjusted odds ratio [OR]: 0.959; confidence interval [CI]: 0.934–0.985). Medication adherence (adjusted OR: 2.688; CI: 1.534–4.708) and use of combined oral medications (adjusted OR: 5.604; CI: 3.078–10.203), combined oral medications with insulin (adjusted OR: 23.466; CI: 8.208–67.085) and insulin only (adjusted OR: 6.528; CI: 1.876–22.717) were associated with good glycaemic control. Older age (adjusted OR: 0.954; CI: 0.923–0.986) and Malay ethnicity (adjusted OR: 0.284; CI: 0.101–0.794) were associated with poor glycaemic control. Conclusion: Suboptimal medication adherence and glycaemic control are prevalent in primary care settings, especially among elderly patients. Counselling should be targeted to patients and their caretakers to improve medication adherence and optimise metabolic control

Genome of a thermophilic bacterium Geobacillus sp. TFV3 from Deception Island, Antarctica

Thermophilic microorganisms have always been an important part of the ecosystem, particularly in a hot environment, as they play a key role in nutrient recycling at high temperatures where most microorganisms cannot cope. While most of the thermophiles are archaea, thermophiles can also be found among some species of bacteria. These bacteria are very useful in the fundamental study of heat adaptation, and they are also important as potential sources of thermostable enzymes and metabolites. Recently, we have isolated a Gram-positive thermophilic bacterium, Geobacillus sp. TFV3 from a volcanic soil sample from Deception Island, Antarctica. This project was undertaken to analyze the genes of this thermophilic Antarctic bacterium and to determine the presence of thermal-stress adaptation proteins in its genome. The genome of Geobacillus sp. TFV3 was first purified, sequenced, assembled, and annotated. The complete genome was found to harbor genes encoding for useful thermal-stress adaptation proteins. The majority of these proteins were categorized under the family of molecular chaperone and heat shock protein. This genomic information could eventually provide insights on how the bacterium adapts itself towards high growth temperatures

Epidemiology and risk factors for Carbapenemase-Producing Enterobacteriaceae carriage in the hospital: a population-based nested case-control study

Objective: This study aims to study the epidemiology of Carbapenemase-producing Enterobacteriaceae (CPE) in Hong Kong. / Methods: This is a longitudinal population-based study reporting monthly CPE incidence rate and a nested case-control study for identifying risk factors for CPE carriage. The cases were patients with at least one CPE positive genotypic test, while the controls were randomly selected from the cohort with negative tests. Up to four controls per case were matched by sex, age group, and admission year-month. The independent risk factors were identified from a conditional logistic regression with potential covariates. / Results: From 1st January 2008 to 31st December 2019, 8,588 patients received CPE genotyping tests, and 2,353 had at least one positive result. Class B carbapenemase was the predominant enzyme in the samples (78.6%). The incidence rate increased from 0.04 in 2015 to 1.62 in 2019 per 10,000 person-year. In the nested case-control study, 1709 cases and 6664 controls were matched. Previous use of any beta-lactam antibiotics [Odds ratio:1.37 (1.22-1.53), p<.001] was found as an independent risk factor for carriage of CPE. / Conclusion: The carriage of CPE was found with an increasing trend in Hong Kong. Previous use of any beta-lactam antibiotics is a risk factor for CPE. / Summary: The incidence rate of Carbapenemase-producing Enterobacteriaceae is increasing in Hong Kong, with the predominant enzyme of class B carbapenemase. With multivariable conditional logistic regression, the previous use of any beta-lactam antibiotics was found as an independent risk factor for CPE carriage

Analyses of expressed sequence tags (ESTs) from panicles of the indica rice cultivar MR84 during grain filling stages and molecular characterisation of ADP-glucose pyrophosphorylase small subunit

Rice grain filling is a critical factor that affects yield. In this study, we analyzed the transcripts from rice panicles of the indica rice cultivar MR84 during reproductive and grain filling stages by using expressed sequence tag (EST) approach. Subtractive hybridizations were conducted using three pools of mRNA encompassing panicle initiation, booting, heading, flow­ering, pollination, fertilization, early/mid and late grain developmental phases. A total of 2366 clones were obtained from these subtractive hybridizations and 718 of them were sequenced. Approximately 36% of the sequenced cDNAs from rice panicles during panicle initiation to heading encoded for pollen allergens, whereas, the remaining ESTs encoded proteins involved in metabolism, transportation, gene expression and other functions. Most of the ESTs from heading to milk stage were storage proteins or involve in metabolisms, whereas, majority of the gene sequences from milk stage to maturation encoded putative storage proteins (61 %) e.g. glutelins and prolamins. Starch is the main component of rice seed dry weight and its biosynthesis largely drives rice yield. Herein, a partial cDNA sequence (I-AGPS1) for the plastidial form of ADP-glucose pyrophosphory­lase small subunit, which is involved in the rate-limiting step of starch biosynthesis in higher plants, was isolated from MR84. This gene was preferentially expressed in the grains of milk and dough stage, but unlike its homolog from japonica cultivar, was undetected in rice leaves