Extractables and leachables

Siow Leng SIM 한국생물공학회 2015 한국생물공학회 학술대회 Vol.2015 No.10

Stabilization of Polymer-Hydrogel Capsules via Thiol–Disulfide Exchange

Chong, Siow-Feng,Chandrawati, Rona,Stä,dler, Brigitte,Park, Jeongju,Cho, Jinhan,Wang, Yajun,Jia, Zhongfan,Bulmus, Volga,Davis, Thomas P.,Zelikin, Alexander N.,Caruso, Frank WILEY-VCH Verlag 2009 Small Vol.5 No.22

<P>Polymer hydrogels are used in diverse biomedical applications including drug delivery and tissue engineering. Among different chemical linkages, the natural and reversible thiol–disulfide interconversion is extensively explored to stabilize hydrogels. The creation of macro-, micro-, and nanoscale disulfide-stabilized hydrogels commonly relies on the use of oxidizing agents that may have a detrimental effect on encapsulated cargo. Herein an oxidization-free approach to create disulfide-stabilized polymer hydrogels via a thiol–disulfide exchange reaction is reported. In particular, thiolated poly(methacrylic acid) is used and the conditions of polymer crosslinking in solution and on colloidal porous and solid microparticles are established. In the latter case, removal of the core particles yields stable, hollow, disulfide-crosslinked hydrogel capsules. Further, a procedure is developed to achieve efficient disulfide crosslinking of multilayered polymer films to obtain stable, liposome-loaded polymer-hydrogel capsules that contain functional enzymatic cargo within the liposomal subcompartments. This approach is envisaged to facilitate the development of biomedical applications of hydrogels, specifically those including fragile cargo.</P> <B>Graphic Abstract</B> <P>Polymer-hydrogel capsules are stabilized via disulfide linkages whereby crosslinking relies on the thiol–disulfide exchange without the use of oxidizing agents (see image). The method permits the formation of hollow capsules as well as functional capsosomes, hydrogel capsules subcompartmentalized with enzyme-loaded liposomes, without the loss of activity of liposome-encapsulated enzymes. <img src='wiley_img/16136810-2009-5-22-SMLL200900906-content.gif' alt='wiley_img/16136810-2009-5-22-SMLL200900906-content'> </P>

The Relative Efficacy of Recasts and Prompts on Past Tense Use of ESL Learners

Choo Siow Chin,Siti Zaidah Zainuddin,Stefanie Pillai 아시아테플 2019 The Journal of Asia TEFL Vol.16 No.2

The objective of the study is twofold: to investigate the effects of corrective feedback (CF) on the accuracy of past tense use, and to compare the relative effectiveness of recasts and prompts on the accuracy of past tense use. The participants of the study consisted of 105 secondary school ESL learners in Malaysia. The target structure of CF was the regular and irregular past forms. CF was provided contingent upon the occurrence of past tense errors according to the type of corrective feedback (i.e., recasts, prompts and no corrective feedback) assigned to participants. By employing a pre-post- and delayed- post-test design, learning outcomes were measured by means of an oral production test (OPT), a written production test (WPT) and an untimed grammaticality judgment test (GJT). The results revealed that participants, regardless of type of corrective feedback, showed both short-term and long-term gains in accuracy of past tense use. However, on the delayed effects of CF, the findings suggest that the effects of prompts may be more durable compared to recasts or control. It was found that the effectiveness of corrective feedback was also affected by other mediating factors, including learners’ proficiency level, prior knowledge and the morphological structure of the target linguistic feature.

Bridging Thrombolysis versus Direct Mechanical Thrombectomy in Stroke Due to Basilar Artery Occlusion

Isabel Siow,Benjamin Y.Q. Tan,Keng Siang Lee,Natalie Ong,Emma Toh,Anil Gopinathan,Cunli Yang,Pervinder Bhogal,Erika Lam,Oliver Spooner,Lukas Meyer,Jens Fiehler,Panagiotis Papanagiotou,Andreas Kastrup 대한뇌졸중학회 2022 Journal of stroke Vol.24 No.1

Background and Purpose Mechanical thrombectomy (MT) is an effective treatment for patients with basilar artery occlusion (BAO) acute ischemic stroke. It remains unclear whether bridging intravenous thrombolysis (IVT) prior to MT confers any benefit. This study compared the outcomes of acute BAO patients who were treated with direct MT versus combined IVT plus MT. Methods This multicenter retrospective cohort study included patients who were treated for acute BAO from eight comprehensive stroke centers between January 2015 and December 2019. Patients received direct MT or combined bridging IVT plus MT. Primary outcome was favorable functional outcome defined as modified Rankin Scale 0–3 measured at 90 days. Secondary outcome measures included mortality and symptomatic intracranial hemorrhage (sICH). Results Among 322 patients, 127 (39.4%) patients underwent bridging IVT followed by MT and 195 (60.6%) underwent direct MT. The mean±standard deviation age was 67.5±14.1 years, 64.0% were male and median National Institutes of Health Stroke Scale was 16 (interquartile range, 8 to 25). At 90-day, the rate of favorable functional outcome was similar between the bridging IVT and direct MT groups (39.4% vs. 34.4%, P=0.361). On multivariable analyses, bridging IVT was not associated with favorable functional outcome, mortality or sICH. In subgroup analyses, patients with underlying atherosclerosis treated with bridging IVT compared to direct MT had a higher rate of favorable functional outcome at 90 days (37.2% vs. 15.5%, P=0.013). Conclusions Functional outcomes were similar in BAO patients treated with bridging IVT versus direct MT. In the subgroup of patients with underlying large-artery atherosclerosis stroke mechanism, bridging IVT may potentially confer benefit and this warrants further investigation.

Thermal Ageing Studies of Sintered Micron-Silver (Ag) Joint as a Lead-Free Bonding Material

K. S. Siow,S. T. Chua 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.9

The sintered silver (Ag) joint has proven to be a suitable die-attach material to be used under the operating conditions of widebandgap semiconductors because of its high melting point and high thermal and electrical conductivities. However, to bondreliably, a sintered Ag joint needs a suitable metallized substrate (e.g. gold or silver) and the application of pressure duringsintering. Hence, we investigated the evolving microstructure (i.e. the importance of pore shape factor) and shear strengthof micron-Ag joints bonded without pressure on copper, Ag-plated substrate, and direct-bond copper (DBC) thermally agedat 300 °C for 1000 h. The DBC substrate maintained die-shear strength better because its coefficient of thermal expansionmatched those of the sintered Ag and Si dies. Regardless of substrate, micron-Ag joints showed a decrease of large pores(> 0.16 μm2) and an increase of spherical pore shapes during the aging period. These favourable changes maintained themechanical integrity of the micron-Ag joints. This evolving microstructure of the sintered Ag joint provides guidelines forpackaging engineers to consider as part of their selection of metallizations and substrates for power electronic packaging.

Insights for Improving Road Safety:Focusing on Vehicle Accidents in Daegu Metropolitan City

Mee Qi Siow,Yang Sok Kim,Mi Jin Noh,Choong Kwon Lee,Sang Ill Moon,Jae Ho Shin 한국스마트미디어학회 2023 스마트미디어저널 Vol.12 No.11

Road accidents not only caused loss of human lives but also costed 3% of gross domestic product in most of the countries. The road accidents pose significant challenges to public safety and urban transportation management. There is a need to identify the high-risk area of accidents along with the critical day of week and vulnerable time period in order to implement effective preventive measures and optimizing the resource allocation. We collected 5,012 accident data from 대구교통종합정보. This study identified the high-risk locations, days of week, and time periods for accidents in Daegu and estimated the conditional probabilities of accidents occurring based on combinations of location, day of the week, and time period. The result is visualized in the form of dashboard in Tableau. This study holds substantial practical significance for urban planners, transportation authorities, and policymakers in Daegu to strategically allocate resources for traffic management, law enforcement, and targeted safety campaigns.

Empowering Agriculture: Exploring User Sentiments and Suggestions for Plantix, a Smart Farming Application

Mee Qi Siow,한무명초,Yu Na Lee,Seon Yeong Yu,Mi Jin Noh,Yang Sok Kim (사)한국스마트미디어학회 2023 스마트미디어저널 Vol.12 No.10

Farming activities are transforming from traditional skill-based agriculture into knowledge-based and technology-driven digital agriculture. The use of intelligent information and communication technology introduces the idea of smart farming that enables farmers to collect weather data, monitor crop growth remotely and detect crop diseases easily. The introduction of Plantix, a pest and disease management tool in the form of a mobile application has allowed farmers to identify pests and diseases of the crop using their mobile devices. Hence, this study collected the reviews of Plantix to explore the response of the users on the Google Play Store towards the application through Latent Dirichlet Allocation (LDA) topic modeling. Results indicate four latent topics in the reviews: two positive evaluations (compliments, appreciation) and two suggestions (plant options, recommendations). We found the users suggested the application to additional plant options and additional features that might help the farmers with their difficulties. In addition, the application is expected to benefit the farmer more by having an early alert of diseases to farmers and providing various substitutes and a list of components for the remedial measures.

Exploring the Impact of Pesticide Usage on Crop Condition: A Causal Analysis of Agricultural Factors

Mee Qi Siow,Yang Sok Kim,Mi Jin Noh,Mu Moung Cho Han (사)한국스마트미디어학회 2023 스마트미디어저널 Vol.12 No.10

Human lifestyle is affected by the agricultural development in the last 12,000 years ago. The development of agriculture is one of the reasons that global population surged. To ensure sufficient food production for supporting human life, pesticides as a more effective and economical tools, are extensively used to enhance the yield quality and boost crop production. This study investigated the factors that affect crop production and whether the factors of pesticide usage are the most important factors in crop production using the dataset from Kaggle that provides information based on crops harvested by various farmers. Logistic regression is used to investigate the relationship between various factors and crop production. However, the logistic regression is unable to deal with predictors that are related to each other and identifying the greatest impact factor. Therefore, causal discovery is applied to address the above limitations. The result of causal discovery showed that crop condition is greatly impacted by the estimated insects count, where estimated insects count is affected by the factors of pesticide usage. This study enhances our understanding of the influence of pesticide usage on crop production and contributes to the progress of agricultural practices.

A Review of Brain-derived Neurotrophic Factor as a Candidate Biomarker in Schizophrenia

Milawaty Nurjono,Jimmy Lee,Siow-Ann Chong 대한정신약물학회 2012 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.10 No.2

Brain-derived neurotrophic factor (BDNF), a neurotrophin known to be responsible for development, regeneration, survival and maintenance of neurons has been implicated in the pathophysiology of schizophrenia. This review seeks to complement previous reviews on biological roles of BDNF and summarizes evidence on the involvement of BDNF in the pathophysiology of schizophrenia with an emphasis on clinical relevance. The expressions of BDNF were altered in patients with schizophrenia and were found to be correlated with psychotic symptomatology. Antipsychotics appeared to have differential effects on expression of BDNF but did not restore BDNF expression of patients with schizophrenia to normal levels. In addition, evidence suggests that BDNF is involved in the major neurotransmitter systems and is associated with disruptions in brain structure, neurodevelopmental process, cognitive function, metabolic and immune systems commonly associated with schizophrenia. Besides that, BDNF has been demonstrated to be tightly regulated with estrogen which has also been previously implicated in schizophrenia. Evidence gathered in this review confirms the relevance of BDNF in the pathophysiology of schizophrenia and the potential utility of BDNF as a suitable biomarker for diagnostic and prognostic purposes for disease outcome and other co-morbidities. However, further investigations are warranted to examine the specificity of BDNF in schizophrenia compared to other neurodegenerative disorders and other neuropsychiatric illness. Longitudinal prospective studies will also be of added advantage for evaluation of prognostic utility of BDNF in schizophrenia.

Intimate Partner Violence in Cambodia: Is Women’s Empowerment a Protective Factor?

Chiew Way Ang,Siow Li Lai 숙명여자대학교 아시아여성연구원 2022 Asian Women Vol.38 No.3

One of the key agendas of the Sustainable Development Goals is to eliminate all forms of discrimination and violence against women and girls. Intimate Partner Violence (IPV) is a human rights violation that has severe health, social, and economic consequences. While there is a sizable body of literature on IPV in South Asia, research on this topic in Southeast Asia is lacking. This study examines whether women’s empowerment is protective against physical, sexual, and emotional IPV in Cambodia, the least developed country in Southeast Asia, and where IPV is higher than in its regional peers. Despite the Cambodian government’s commendable efforts to uplift women’s status, there was an increase in all forms of IPV among married women between 2005 and 2014: from 17.5% to 23.9% for emotional abuse, 11.9% to 14.9% for physical violence, and 2.5% to 4.8% for sexual violence. There was also evidence of the intergenerational transmission of physical violence against women. The data for this study were obtained from the 2014 Cambodia Demographic and Health Survey. A total of 3,223 married women aged 15–49 years were interviewed for the domestic violence module. Cross-tabulations, the Chi-square/Fisher’s exact test, and binary logistic regression were used to examine the association between women’s empowerment and the three different forms of IPV. Household decision-making power, attitude against wife beating, higher education (of both women and husbands), women’s earnings, delayed marriage, and having fewer children were associated with less IPV. Men’s controlling and drinking behaviors are risk factors for IPV in Cambodia. More efforts must be made to raise the educational level of the population, provide more job and earnings opportunities, and promote gender equality in the family and society to eradicate IPV.