Processing parallel-disk viscometry data in the presence of wall slip

Leong, Yee-Kwong,Campbell, Graeme R.,Yeow, Y. Leong,Withers, John W. The Korean Society of Rheology 2008 Korea-Australia rheology journal Vol.20 No.2

This paper describes a two-step Tikhonov regularization procedure for converting the steady shear data generated by parallel-disk viscometers, in the presence of wall slip, into a shear stress-shear rate function and a wall shear stress-slip velocity functions. If the material under test has a yield stress or a critical wall shear stress below which no slip is observed the method will also provide an estimate of these stresses. Amplification of measurement noise is kept under control by the introduction of two separate regularization parameters and Generalized Cross Validation is used to guide the selection of these parameters. The performance of this procedure is demonstrated by applying it to the parallel disk data of an oil-in-water emulsion, of a foam and of a mayonnaise.

Cervical Pneumatocele as Delayed Manifestation of Tracheal Injury after Thyroidectomy: Case Series and Literature Review

Jia Ern Leong,Wai Leong Kok,Yee Ling Tan,Balwinder Singh Mann,Sadhana Mahamad 대한갑상선-내분비외과학회 2021 The Koreran journal of Endocrine Surgery Vol.21 No.1

Delayed manifestation of surgical emphysema as cervical pneumatocele post thyroid surgery is rare and unexpected that which needs to be managed appropriately. Herein we report three cases of delayed tracheal injury presenting with persistent subcutaneous emphysema, without acute respiratory distress. All three cases were managed surgically. Possible risk factors were discussed alongside hypotheses on the mechanisms of delayed tracheal injury and recommendations to prevent such complications. The management algorithm was summarized after the literature review. While surgical management is definitive, the non-surgical approach can also be a reasonable option, but requires a longer hospital stay.

Processing parallel-disk viscometry data in the presence of wall slip

Yee-Kwong Leong,Graeme R. Campbell,Y. Leong Yeow,John W. Withers 한국유변학회 2008 Korea-Australia rheology journal Vol.20 No.2

This paper describes a two-step Tikhonov regularization procedure for converting the steady shear data generated by parallel-disk viscometers, in the presence of wall slip, into a shear stress-shear rate function and a wall shear stress-slip velocity functions. If the material under test has a yield stress or a critical wall shear stress below which no slip is observed the method will also provide an estimate of these stresses. Amplification of measurement noise is kept under control by the introduction of two separate regularization parameters and Generalized Cross Validation is used to guide the selection of these parameters. The performance of this procedure is demonstrated by applying it to the parallel disk data of an oil-in-water emulsion, of a foam and of a mayonnaise.

Biocompatibility of two experimental scaffolds for regenerative endodontics

Leong, Dephne Jack Xin,Setzer, Frank C.,Trope, Martin,Karabucak, Bekir The Korean Academy of Conservative Dentistry 2016 Restorative Dentistry & Endodontics Vol.41 No.2

Objectives: The biocompatibility of two experimental scaffolds for potential use in revascularization or pulp regeneration was evaluated. Materials and Methods: One resilient lyophilized collagen scaffold (COLL), releasing metronidazole and clindamycin, was compared to an experimental injectable poly(lactic-co-glycolic) acid scaffold (PLGA), releasing clindamycin. Human dental pulp stem cells (hDPSCs) were seeded at densities of $1.0{\times}10^4$, $2.5{\times}10^4$, and $5.0{\times}10^4$. The cells were investigated by light microscopy (cell morphology), MTT assay (cell proliferation) and a cytokine (IL-8) ELISA test (biocompatibility). Results: Under microscope, the morphology of cells coincubated for 7 days with the scaffolds appeared healthy with COLL. Cells in contact with PLGA showed signs of degeneration and apoptosis. MTT assay showed that at $5.0{\times}10^4$ hDPSCs, COLL demonstrated significantly higher cell proliferation rates than cells in media only (control, p < 0.01) or cells co-incubated with PLGA (p < 0.01). In ELISA test, no significant differences were observed between cells with media only and COLL at 1, 3, and 6 days. Cells incubated with PLGA expressed significantly higher IL-8 than the control at all time points (p < 0.01) and compared to COLL after 1 and 3 days (p < 0.01). Conclusions: The COLL showed superior biocompatibility and thus may be suitable for endodontic regeneration purposes.

MALAYSIA'S CONCEPTIONS OF SECURITY SELF-RESILIENCE, SOVEREIGNTY AND REGIONAL DYNAMICS

Leong, Ho Khai The Institute for Far Eastern Studies Kyungnam Uni 1998 ASIAN PERSPECTIVE Vol.22 No.3

The Malaysian conceptions of security are influenced by the country's political and social variables. Its conceptions of security have been dominated by political and policy elite who were mostly of the dominant United Malays National Organization (UMNO). The historical development and social configuration of the country have made Malay-dominance an inescapable theme in political life. While economic development and growth in the last decade, coupled with more liberal policies embodied in Prime Minister Mahathir's Vision 2020, have replaced the once all-prevailing focus of ethnic conflicts, the latter nevertheless has great influence over the ways competing groups view security matters. In general, Malaysia's conception of security combines the uniqueness of the country's physical configurations, its historical and colonial experiences, the ethnic and cultural make-up of its population, and its pragmatic policies dealing with contemporary changes in the regional and international environments. No doubt military and political security has been a constant concern and rightly so, but the interests of Malaysia cannot be defined exclusively in terms of military and political security. The contributions by the Malavsian policial elite are their holistic, expansive and comprehensive views of what constitute contemporary security concerns. From the standpoint of Malaysian leaders, it is the preoccupation with the ultimately the reconstruction of self-resilience and regional economic linkages that will, for a long time to come, continue to direct the country's attitude towards security.

Relooking "Look Back": A student`s Attempt at Problem Solving using Polya`s Model

( Leong Yew Hoong ),( Dindyal Jaguthsing ),( Toh Tin Lam ),( Quek Khiok Seng ),( Tay Eng Guan ) 한국수학교육학회 2011 수학교육 학술지 Vol.2011 No.1

Against the backdrop of half a century of research in mathematics problem solving, Polya`s last stage is especially conspicuous-by the scarcity of research on it! Much of the research focused on the first three stages (e.g., Francisco & Maher 2005; Taylor & Mcdonald, 2007), with little or no successful attempts at following through with the subjects. In this paper, we describe a case study of how the innovation of a "Practical Worksheet" within a new paradigm of a "Mathematics Practical" enabled a high-achieving student to push beyond getting a solution for a problem to extending, adapting and generalising his solution. The findings from this study indicate promise in achieving the learning of Polya`s model with notable success in the fourth stage, Look Back.

Professional Development of Mathematics teachers: The Replacement Unit Strategy

( Leong Yew Hoong ) 한국수학교육학회 2016 수학교육 학술지 Vol.2016 No.3

Preparation of antibacterial TiO₂ particles by hybridization with azelaic acid for applications in cosmetics

Leong, Hui Jun,Oh, Seong-Geun THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.66 No.-

<P><B>Abstract</B></P> <P>To apply as the antimicrobial agent in cosmetics, azelaic acid, a skin lightening material with anti-inflammatory and antimicrobial properties, has been employed to functionalize TiO<SUB>2</SUB> microspheres. Prior to the functionalization process, TiO<SUB>2</SUB> microspheres were modified with NaOH to introduce hydroxyl groups on the surface of TiO<SUB>2</SUB> as chemical binders. Hybridization was performed by condensation reaction between hydroxyl groups introduced on the surface of TiO<SUB>2</SUB> by hydroxylation process and the hydroxyl groups of azelaic acid. The azelaic acid-TiO<SUB>2</SUB> composites showed high antimicrobial activities towards both gram positive and gram negative bacterial strains, which are <I>Staphylococcus aureus and Escherichia coli</I>.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Identification of the mechanism for dehalorespiration of monofluoroacetate in the phylum Synergistota

Leong Lex E. X.,Denman Stuart E.,Kang Seungha,Mondot Stanislas,Hugenholtz Philip,McSweeney Chris S. 아세아·태평양축산학회 2024 Animal Bioscience Vol.37 No.2

Objective: Monofluoroacetate (MFA) is a potent toxin that blocks ATP production via the Krebs cycle and causes acute toxicity in ruminants consuming MFA-containing plants. The rumen bacterium, Cloacibacillus porcorum strain MFA1 belongs to the phylum Synergistota and can produce fluoride and acetate from MFA as the end-products of dehalorespiration. The aim of this study was to identify the genomic basis for the metabolism of MFA by this bacterium. Methods: A draft genome sequence for C. porcorum strain MFA1 was assembled and quantitative transcriptomic analysis was performed thus highlighting a candidate operon encoding four proteins that are responsible for the carbon-fluorine bond cleavage. Comparative genome analysis of this operon was undertaken with three other species of closely related Synergistota bacteria. Results: Two of the genes in this operon are related to the substrate-binding components of the glycine reductase protein B (GrdB) complex. Glycine shares a similar structure to MFA suggesting a role for these proteins in binding MFA. The remaining two genes in the operon, an antiporter family protein and an oxidoreductase belonging to the radical S-adenosyl methionine superfamily, are hypothesised to transport and activate the GrdB-like protein respectively. Similar operons were identified in a small number of other Synergistota bacteria including type strains of Cloacibacillus porcorum, C. evryensis, and Pyramidobacter piscolens, suggesting lateral transfer of the operon as these genera belong to separate families. We confirmed that all three species can degrade MFA, however, substrate degradation in P. piscolens was notably reduced compared to Cloacibacillus isolates possibly reflecting the loss of the oxidoreductase and antiporter in the P. piscolens operon. Conclusion: Identification of this unusual anaerobic fluoroacetate metabolism extends the known substrates for dehalorespiration and indicates the potential for substrate plasticity in amino acid-reducing enzymes to include xenobiotics. Objective: Monofluoroacetate (MFA) is a potent toxin that blocks ATP production via the Krebs cycle and causes acute toxicity in ruminants consuming MFA-containing plants. The rumen bacterium, <i>Cloacibacillus porcorum</i> strain MFA1 belongs to the phylum Synergistota and can produce fluoride and acetate from MFA as the end-products of dehalorespiration. The aim of this study was to identify the genomic basis for the metabolism of MFA by this bacterium.Methods: A draft genome sequence for <i>C. porcorum</i> strain MFA1 was assembled and quantitative transcriptomic analysis was performed thus highlighting a candidate operon encoding four proteins that are responsible for the carbon-fluorine bond cleavage. Comparative genome analysis of this operon was undertaken with three other species of closely related Synergistota bacteria.Results: Two of the genes in this operon are related to the substrate-binding components of the glycine reductase protein B (GrdB) complex. Glycine shares a similar structure to MFA suggesting a role for these proteins in binding MFA. The remaining two genes in the operon, an antiporter family protein and an oxidoreductase belonging to the radical S-adenosyl methionine superfamily, are hypothesised to transport and activate the GrdB-like protein respectively. Similar operons were identified in a small number of other Synergistota bacteria including type strains of <i>Cloacibacillus porcorum, C. evryensis</i>, and <i>Pyramidobacter piscolens</i>, suggesting lateral transfer of the operon as these genera belong to separate families. We confirmed that all three species can degrade MFA, however, substrate degradation in <i>P. piscolens</i> was notably reduced compared to <i>Cloacibacillus</i> isolates possibly reflecting the loss of the oxidoreductase and antiporter in the <i>P. piscolens</i> operon.Conclusion: Identification of this unusual anaerobic fluoroacetate metabolism extends the known substrates for dehalorespiration and indicates the potential for substrate plasticity in amino acid-reducing enzymes to include xenobiotics.

Ultrasound Breast Elastographic Evaluation of Mass-Forming Ductal Carcinoma-in-situ with Histological Correlation - New Findings for a Toothpaste Sign

Leong, Lester Chee Hao,Sim, Llewellyn Shao-Jen,Jara-Lazaro, Ana Richelia,Tan, Puay Hoon Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.5

Background: It is unclear as to whether the size ratio elastographic technique is useful for assessing ultrasound-detected ductal carcinoma-in-situ (DCIS) masses since they commonly lack a significant desmoplastic reaction. The objectives of this study were to determine the accuracy of this elastographic technique in DCIS and examine if there was any histopathological correlation with the grey-scale strain patterns. Materials and Methods: Female patients referred to the radiology department for image-guided breast biopsy were prospectively evaluated by ultrasound elastography prior to biopsy. Histological diagnosis was the gold standard. An elastographic size ratio of more than 1.1 was considered malignant. Elastographic strain patterns were assessed for correlation with the DCIS histological architectural patterns and nuclear grade. Results: There were 30 DCIS cases. Elastographic sensitivity for detection of malignancy was 86.7% (26/30). 10/30 (33.3%) DCIS masses demonstrated predominantly white elastographic strain patterns while 20/30 (66.7%) were predominantly black. There were 3 (10.0%) DCIS masses that showed had a co-existent bull's-eye sign and 7 (23.3%) other masses had a co-existent toothpaste sign, a strain pattern that has never been reported in the literature. Four out of 4/5 comedo DCIS showed a predominantly white strain pattern (p=0.031) while 6/7 cases with the toothpaste sign were papillary DCIS (p=0.031). There was no relationship between the strain pattern and the DCIS nuclear grade. Conclusions: The size ratio elastographic technique was found to be very sensitive for ultrasound-detected DCIS masses. While the elastographic grey-scale strain pattern should not be used for diagnostic purposes, it correlated well with the DCIS architecture.