15 results on '"Koh, Ct"'
Search Results
2. The Inhaled Steroid Treatment As Regular Therapy in Early Asthma (START) study 5-year follow-up: effectiveness of early intervention with budesonide in mild persistent asthma
- Author
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BUSSE WW, PEDERSEN S, PAUWELS RA, TAN WC, CHEN YZ, LAMM CJ, Eckmayr J, Riedler J, Wurzinger G, Ott G, Zarkovic J, Schulheim A, Götz M, Schinko H, Thomüller I, de Backer W, van Bever H, Verleden G, de Boeck C, Aumann J, Vincken W, Dab I, de Vuyst P, de Jonghe M, Casimir G, Joos G, de Baets F, Bogaerts Y, Halloy JL, Bartsch P, Thiriaux J, Pohunek P, Rybníćek O, Skopková O, Pavelková L, Broź P, Ohnutková E, Novotná B, Baly J, Krćmová I, Kuralová Z, Koćí T, Honomichlová H, Kaśák V, Panzner P, Vondra V, Némećková J, Seberová E, Sykora T, Vít P, Turzíková J, Sörensen T, Neldam S, Peter J, Kludt J, Hansen UB, Knudsen T, Schultz PJ, Rost D, Jensen F, Kinnula V, Saarelainen P, Eho Remes M, Valovirta E, Venho KK, Kokko E, Järvinen M, Toljamo T, Taivainen A, Kava T, Herrala J, Kuusela AL, Nordgren P, Syvänen P, Godard P, Rufin P, Anton M, Aubert JP, Grosclaude M, Brambilla C, Archaud P, Racineux JL, Muir JF, Albertini M, Le Roux P, Simmons A, Bartuschka B, von Berg A, Bergmann V, Berns J, Bisping Arnold A, Blum HC, Garanin G, Brückner OJ, Burbach P, Sudhoff H, Feldmann M, Schmoller T, Wozny HW, Galaske R, Huptas M, Kaecke J, Köcher V, Laule Peschel M, Lohr E, Goldberg J, Drescher T, Reeh W, Rabe U, Rehn L, Scheffler NK, Steinmetz KO, Stutz PM, Weber HH, Uhde C, Ullner R, Vehar H, Krohn EU, Orosz M, Devai A, Uhereczky G, Rajkay K, Gönczi F, Györi E, Dobra G, Puha K, Sztancsik Z, Gömöri K, Dolinay T, Bittera I, Palinkasi S, Cseke Z, Bisits M, Bjämer D, Holme JI, Langhammer A, Hunstad K, Holmboe JH, Grangård E, Solberg DA, Grönneröd TA, Salkowitsch MB, Oymar K, Iversen K, Szczeklik A, Chyrek Borowska S, Mincewicz G, Malaczynska T, Latos T, Obtulowicz K, Emeryk A, Gorski P, Nowak D, Szmidt M, Alkiewicz J, Ziolo G, Spychalski L, Chmielewska Szewczyk D, Nowacka K, Pirozynski M, Prokurat H, Boznanski A, Malolepszy J, Rogala E, Kozielski J, Eriksson UL, Wahlestedt H, Selberg M, Larsson R, Rignér K, Alm B, Aronsson M, Winnergård I, Lagerwall M, Martinsons U, Berlin L, Rydberg B, Weston D, Johnson ME, Barrett C, Siafakas N, Mantzourani E, Orphanidou D, Trakopoulos G, Tzannes S, Kotsovoulou V, Dimadi M, Amfilochiou A, Priftis K, Papageorgiou Saxoni F, Christaki P, Tsanakas I, Paraskevi M, Bousmoukilia S, Spiropoulos K, Anthrakopoulos M, Roussos C, Bentur Alkouby L, Heimer D, Tal A, Horowitz I, Soferman R, Katz Y, Stav D, Weiler Z, Bibi H, Rottem M, Mandelberg A, Geller C, Roizin H, Weiler Ravell D, Kramer MR, Schwartz Y, Rossi A, Foresi A, Giuntini C, Bisetti A, Scoditti S, Tranfa C, Zacchello F, Giovannini M, Boner A, Fabbri LM, Girbino G, Barberio G, Cacciari E, Montefort S, Parascandalo R, Pato R, de Lourdes Chieira M, Moreira C, Chieira DS, Brito U, Borges FD, Marques AC, Figueiredo MM, Dias F, de Almeida AB, Cesar Ramos J, Valente MJ, Pereira JD, Nunes C, Riberio MF, Marques A, Carvalho MQ, de Azevedo MV, de Almeida AR, Pinto JA, Matos Mde F, Afonso A, Dos Santos JM, Fernandez CV, Agustin IC, Bejarano JM, Santos AA, Font ET, Huet EH, Lorente TL, Pujol MM, Munoz AP, Aineto PS, Forns SB, Areu JB, Casan P, Garcia JM, Rodriguez AV, Segura PA, Gil RS, Ciscar CP, Garcia JF, Jimenez TV, Gonzalez JI, Andres FQ, Bueno TA, Baticon CO, Miguel CR, Garcia FD, Hernando HV, Vina AL, Matia RA, Cumplido AS, Andueza MC, Cabra MS, Navarro PL, Rodriguez FA, Li JH, Landry D, O'Keefe D, Muram BF, Conter HS, Tweel D, Peters SD, Adelglass J, Baker JW, Berger WE, Bernstein DI, Blake KV, Amelong P, Casale TB, Charous BL, Chervinsky P, Condemi JJ, Cook D, Creticos PS, de Graff AC Jr, Smith T, Ellis MH, Grossman J, Halverson PC, Galant S, Hollingsworth H, Jackson C, Jacobs RL, Welch M, Kraemer MJ, Leflein J, Lemanske RF, Liebhaber MI, Lockey R, Kelly B, Mendelson L, Nayak A, Pearlman DS, Ruff M, Schwartz B, Scott MB, Shapiro GG, Silk HJ, Skoner DP, Stoloff S, Swamy KN, Atkins FM, Szefler SJ, Vandewalker M, Wald J, Weinstein SF, Wong DA, Wu F, Goldstein S, Murthy KC, Dolmann A, Gene R, Casas JC, Piovano C, Segal E, Balanzat AM, Taborda J, Truganti A, Teper A, Garrood J, Patel MJ, Hogan C, Russel G, Zhu YJ, Cao L, Liu SY, Miao JZ, Ding DJ, Yao WZ, Liu YN, Chen P, Kong SQ, Pang L, Sun B, Li ZM, Li GS, Chen PL, Zhu Q, Zhang TX, Wang XH, Wei S, Deng WW, Zhou X, Ji YY, Luo WT, Li Q, Zhu HR, Sheng JY, Ma JY, Zhang DP, Ji CZ, Xia XR, Zhang ZY, Yin KS, Yiang J, Li Y, Tang PW, Liu FG, Wang HP, Zhong NS, Rong ZS, Tang YC, Lin CY, Liu JS, Liu HZ, Cai DM, Yang JC, Ma QF, Mangunnegoro H, Wijono CA, Tobing NH, Rahajoe NN, Sugito, Surjanto E, Hisyam B, Alsagaff H, Santosa G, Kim YY, Park CS, Kim MK, Cho YJ, Choi DC, Jee YK, Mohan J, Yogeswery S, Wong SL, Kuan GL, Koh CT, Quah BS, de Bruyne J, Liam CK, Avila MM, Cuevas F, Chavaje N, Topete LA, Badillo I, Ponce M, Merida JC, Espinosa AG, Ledezma JM, García JA, Morales GG, Gomez JM, Martinez FJ, Ramos JE, Dorantes JR, Gonzalez CC, Vera JG, Bayardo RG, Melendez AP, Loyola CB, Suárez MA, de Guia T, Balgos A, Bautista N, Realiza T, Diaz D, Yu C, Mendoza Wi JA, Juaneza R, Bigornia R, Mansukhani P, Cacanindin DN, Wah LB, Hon YK, Yau OY, Moh CO, Tang WY, Dippenaar YD, Kirsten DL, Maraschin EF, Ossip MS, Visser SS, Mouton WL, Mercer M, Cassim KM, Macleod AH, Bateman ED, Leaver R, Morison A, Nel H, von Delft KH, Vermeulen JH, Weinberg EG, Lund RJ, Weber HC, Kuo SH, Kuo HP, Wang JL, Hsiue TR, Wang JH, Ching CD, Vangveeravong M, Pothiratana C, Trakultivakorn M, Kongpanichkul A, Thamanavat B, Fuangtong R, Suntornlohanakul S, Youngchaiyud P, Teeratakulpisarn J, Boonsawat W, Viriyachaiyo V, Direkwattanachai C, Visitsunthorn N., MIRAGLIA DEL GIUDICE, Michele, Busse, Ww, Pedersen, S, Pauwels, Ra, Tan, Wc, Chen, Yz, Lamm, Cj, Eckmayr, J, Riedler, J, Wurzinger, G, Ott, G, Zarkovic, J, Schulheim, A, Götz, M, Schinko, H, Thomüller, I, de Backer, W, van Bever, H, Verleden, G, de Boeck, C, Aumann, J, Vincken, W, Dab, I, de Vuyst, P, de Jonghe, M, Casimir, G, Joos, G, de Baets, F, Bogaerts, Y, Halloy, Jl, Bartsch, P, Thiriaux, J, Pohunek, P, Rybníćek, O, Skopková, O, Pavelková, L, Broź, P, Ohnutková, E, Novotná, B, Baly, J, Krćmová, I, Kuralová, Z, Koćí, T, Honomichlová, H, Kaśák, V, Panzner, P, Vondra, V, Némećková, J, Seberová, E, Sykora, T, Vít, P, Turzíková, J, Sörensen, T, Neldam, S, Peter, J, Kludt, J, Hansen, Ub, Knudsen, T, Schultz, Pj, Rost, D, Jensen, F, Kinnula, V, Saarelainen, P, Eho Remes, M, Valovirta, E, Venho, Kk, Kokko, E, Järvinen, M, Toljamo, T, Taivainen, A, Kava, T, Herrala, J, Kuusela, Al, Nordgren, P, Syvänen, P, Godard, P, Rufin, P, Anton, M, Aubert, Jp, Grosclaude, M, Brambilla, C, Archaud, P, Racineux, Jl, Muir, Jf, Albertini, M, Le Roux, P, Simmons, A, Bartuschka, B, von Berg, A, Bergmann, V, Berns, J, Bisping Arnold, A, Blum, Hc, Garanin, G, Brückner, Oj, Burbach, P, Sudhoff, H, Feldmann, M, Schmoller, T, Wozny, Hw, Galaske, R, Huptas, M, Kaecke, J, Köcher, V, Laule Peschel, M, Lohr, E, Goldberg, J, Drescher, T, Reeh, W, Rabe, U, Rehn, L, Scheffler, Nk, Steinmetz, Ko, Stutz, Pm, Weber, Hh, Uhde, C, Ullner, R, Vehar, H, Krohn, Eu, Orosz, M, Devai, A, Uhereczky, G, Rajkay, K, Gönczi, F, Györi, E, Dobra, G, Puha, K, Sztancsik, Z, Gömöri, K, Dolinay, T, Bittera, I, Palinkasi, S, Cseke, Z, Bisits, M, Bjämer, D, Holme, Ji, Langhammer, A, Hunstad, K, Holmboe, Jh, Grangård, E, Solberg, Da, Grönneröd, Ta, Salkowitsch, Mb, Oymar, K, Iversen, K, Szczeklik, A, Chyrek Borowska, S, Mincewicz, G, Malaczynska, T, Latos, T, Obtulowicz, K, Emeryk, A, Gorski, P, Nowak, D, Szmidt, M, Alkiewicz, J, Ziolo, G, Spychalski, L, Chmielewska Szewczyk, D, Nowacka, K, Pirozynski, M, Prokurat, H, Boznanski, A, Malolepszy, J, Rogala, E, Kozielski, J, Eriksson, Ul, Wahlestedt, H, Selberg, M, Larsson, R, Rignér, K, Alm, B, Aronsson, M, Winnergård, I, Lagerwall, M, Martinsons, U, Berlin, L, Rydberg, B, Weston, D, Johnson, Me, Barrett, C, Siafakas, N, Mantzourani, E, Orphanidou, D, Trakopoulos, G, Tzannes, S, Kotsovoulou, V, Dimadi, M, Amfilochiou, A, Priftis, K, Papageorgiou Saxoni, F, Christaki, P, Tsanakas, I, Paraskevi, M, Bousmoukilia, S, Spiropoulos, K, Anthrakopoulos, M, Roussos, C, Bentur Alkouby, L, Heimer, D, Tal, A, Horowitz, I, Soferman, R, Katz, Y, Stav, D, Weiler, Z, Bibi, H, Rottem, M, Mandelberg, A, Geller, C, Roizin, H, Weiler Ravell, D, Kramer, Mr, Schwartz, Y, Rossi, A, Foresi, A, Giuntini, C, Bisetti, A, Scoditti, S, Tranfa, C, Zacchello, F, Giovannini, M, Boner, A, MIRAGLIA DEL GIUDICE, Michele, Fabbri, Lm, Girbino, G, Barberio, G, Cacciari, E, Montefort, S, Parascandalo, R, Pato, R, de Lourdes Chieira, M, Moreira, C, Chieira, D, Brito, U, Borges, Fd, Marques, Ac, Figueiredo, Mm, Dias, F, de Almeida, Ab, Cesar Ramos, J, Valente, Mj, Pereira, Jd, Nunes, C, Riberio, Mf, Marques, A, Carvalho, Mq, de Azevedo, Mv, de Almeida, Ar, Pinto, Ja, Matos Mde, F, Afonso, A, Dos Santos, Jm, Fernandez, Cv, Agustin, Ic, Bejarano, Jm, Santos, Aa, Font, Et, Huet, Eh, Lorente, Tl, Pujol, Mm, Munoz, Ap, Aineto, P, Forns, Sb, Areu, Jb, Casan, P, Garcia, Jm, Rodriguez, Av, Segura, Pa, Gil, R, Ciscar, Cp, Garcia, Jf, Jimenez, Tv, Gonzalez, Ji, Andres, Fq, Bueno, Ta, Baticon, Co, Miguel, Cr, Garcia, Fd, Hernando, Hv, Vina, Al, Matia, Ra, Cumplido, A, Andueza, Mc, Cabra, M, Navarro, Pl, Rodriguez, Fa, Li, Jh, Landry, D, O'Keefe, D, Muram, Bf, Conter, H, Tweel, D, Peters, Sd, Adelglass, J, Baker, Jw, Berger, We, Bernstein, Di, Blake, Kv, Amelong, P, Casale, Tb, Charous, Bl, Chervinsky, P, Condemi, Jj, Cook, D, Creticos, P, de Graff AC, Jr, Smith, T, Ellis, Mh, Grossman, J, Halverson, Pc, Galant, S, Hollingsworth, H, Jackson, C, Jacobs, Rl, Welch, M, Kraemer, Mj, Leflein, J, Lemanske, Rf, Liebhaber, Mi, Lockey, R, Kelly, B, Mendelson, L, Nayak, A, Pearlman, D, Ruff, M, Schwartz, B, Scott, Mb, Shapiro, Gg, Silk, Hj, Skoner, Dp, Stoloff, S, Swamy, Kn, Atkins, Fm, Szefler, Sj, Vandewalker, M, Wald, J, Weinstein, Sf, Wong, Da, Wu, F, Goldstein, S, Murthy, Kc, Dolmann, A, Gene, R, Casas, Jc, Piovano, C, Segal, E, Balanzat, Am, Taborda, J, Truganti, A, Teper, A, Garrood, J, Patel, Mj, Hogan, C, Russel, G, Zhu, Yj, Cao, L, Liu, Sy, Miao, Jz, Ding, Dj, Yao, Wz, Liu, Yn, Chen, P, Kong, Sq, Pang, L, Sun, B, Li, Zm, Li, G, Chen, Pl, Zhu, Q, Zhang, Tx, Wang, Xh, Wei, S, Deng, Ww, Zhou, X, Ji, Yy, Luo, Wt, Li, Q, Zhu, Hr, Sheng, Jy, Ma, Jy, Zhang, Dp, Ji, Cz, Xia, Xr, Zhang, Zy, Yin, K, Yiang, J, Li, Y, Tang, Pw, Liu, Fg, Wang, Hp, Zhong, N, Rong, Z, Tang, Yc, Lin, Cy, Liu, J, Liu, Hz, Cai, Dm, Yang, Jc, Ma, Qf, Mangunnegoro, H, Wijono, Ca, Tobing, Nh, Rahajoe, Nn, Sugito, Surjanto, E, Hisyam, B, Alsagaff, H, Santosa, G, Kim, Yy, Park, C, Kim, Mk, Cho, Yj, Choi, Dc, Jee, Yk, Mohan, J, Yogeswery, S, Wong, Sl, Kuan, Gl, Koh, Ct, Quah, B, de Bruyne, J, Liam, Ck, Avila, Mm, Cuevas, F, Chavaje, N, Topete, La, Badillo, I, Ponce, M, Merida, Jc, Espinosa, Ag, Ledezma, Jm, García, Ja, Morales, Gg, Gomez, Jm, Martinez, Fj, Ramos, Je, Dorantes, Jr, Gonzalez, Cc, Vera, Jg, Bayardo, Rg, Melendez, Ap, Loyola, Cb, Suárez, Ma, de Guia, T, Balgos, A, Bautista, N, Realiza, T, Diaz, D, Yu, C, Mendoza Wi, Ja, Juaneza, R, Bigornia, R, Mansukhani, P, Cacanindin, Dn, Wah, Lb, Hon, Yk, Yau, Oy, Moh, Co, Tang, Wy, Dippenaar, Yd, Kirsten, Dl, Maraschin, Ef, Ossip, M, Visser, S, Mouton, Wl, Mercer, M, Cassim, Km, Macleod, Ah, Bateman, Ed, Leaver, R, Morison, A, Nel, H, von Delft, Kh, Vermeulen, Jh, Weinberg, Eg, Lund, Rj, Weber, Hc, Kuo, Sh, Kuo, Hp, Wang, Jl, Hsiue, Tr, Wang, Jh, Ching, Cd, Vangveeravong, M, Pothiratana, C, Trakultivakorn, M, Kongpanichkul, A, Thamanavat, B, Fuangtong, R, Suntornlohanakul, S, Youngchaiyud, P, Teeratakulpisarn, J, Boonsawat, W, Viriyachaiyo, V, Direkwattanachai, C, and Visitsunthorn, N.
- Published
- 2008
3. Sleep duration trajectories and cognition in early childhood: A systematic review.
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Tham EK, Jafar NK, Koh CT, Goh DY, Broekman BF, and Cai S
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- Child, Child, Preschool, Humans, Executive Function physiology, Intelligence physiology, Child Development physiology, Cognition physiology, Sleep Duration
- Abstract
Sleep is dynamic in childhood and studies have shown the relationship between sleep and cognition in children. As the human brain is the most plastic during childhood, the study of longitudinal sleep patterns and neurocognition is an important research area. We aimed to systematically review studies that investigated sleep duration trajectories and cognition in typically-developing children. We searched four databases for articles published between 2003 to October 2023. We included observation studies of children with sleep duration trajectories as a predictor and outcomes related to cognition, memory, language, developmental milestones, intelligence or executive function. We excluded studies where children had atypical development or completed the sleep and neurocognitive assessments after six and 12 years of age respectively. Out of 752 articles identified, 511 were screened and 23 full texts were assessed. The selected studies included three single trajectory and four multiple group trajectories studies. We found associations between both types of trajectories and cognitive development. Overall, children with longer sleep trajectories or more mature sleep pattern with rapid decrease in sleep duration, had better performance scores in developmental assessment tools, and intelligence tests. Findings for language and executive functioning were mixed, whereby some studies found associations and others did not., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier Ltd. All rights reserved.)
- Published
- 2024
- Full Text
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4. Role of Asymptomatic Children in Community Severe Acute Respiratory Syndrome Coronavirus 2 Transmission.
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Lu L, Koh CT, Lim YH, Sng A, Poon KS, Tan SSY, Kao PT, Tee N, Yap HK, Lee BW, and Tambyah PA
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- Child, Family Characteristics, Female, Humans, Pregnancy, SARS-CoV-2, Schools, COVID-19, Pregnancy Complications, Infectious
- Published
- 2021
- Full Text
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5. Serosal surface small vessel vasculitis in Henoch-Schonlein purpura.
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Lee WS and Koh CT
- Abstract
Competing Interests: Declaration of Competing Interest We have no conflict of interest to declare for this case report.
- Published
- 2020
- Full Text
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6. EARLY CHALLENGES IN ISOLATION AND DE-ISOLATION OF CHILDREN DURING THE SEVERE ACUTE RESPIRATORY SYNDROME CORONAVIRUS-2 PANDEMIC.
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Chan SM, Chiong T, Chhabra M, Koh CT, Wong YL, Sng AA, and Ong HT
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- COVID-19, Child, Hospital Units, Hospitals, University, Humans, Pediatrics, SARS-CoV-2, Singapore, Betacoronavirus, Coronavirus Infections epidemiology, Pandemics, Patient Isolation methods, Pneumonia, Viral epidemiology
- Published
- 2020
- Full Text
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7. Dataset on microstructural characteristics and mechanical performance of homogeneous and functionally graded fibrous scaffolds.
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Khoo W, Chung SM, Lim SC, Low CY, Shapiro JM, and Koh CT
- Abstract
Data in this article are supplementary to the corresponding research article [1]. Morphological features of homogeneous and graded nanofibrous electrospun gelatin scaffolds were observed using scanning electron microscopy. Microstructural properties including fiber diameter and pore size were determined via image analysis, using ImageJ. Uniaxial tensile and fracture tests were performed on both homogeneous and graded scaffolds using a universal testing machine. Stress-strain curves of all scaffolds are presented. Computing software, MATLAB, was used to design fibrous networks with thickness-dependent density and alignment gradients (DAG). Finite element analysis software, Abaqus, was used to determine the effect of the number of layers on the fracture properties of DAG multilayer scaffolds., (© 2019 The Authors.)
- Published
- 2019
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8. Fracture toughness of human amniotic membranes.
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Koh CT, Tonsomboon K, and Oyen ML
- Abstract
Amnion is a membrane that surrounds and structurally protects the developing fetus during pregnancy. The rupture of amniotic membranes prior to both normal and preterm deliveries involves stretch forces acting on a biochemically triggered weak zone of the membranes. Fracture toughness is an important mechanical property describing how the membranes containing a defect resist fracture, but this property has never been investigated in amniotic membranes. In this work, the fracture toughness of many samples cut from four pieces of amniotic membrane from different mothers was examined by uniaxial and pure shear (mode I) fracture tests. The measurement was checked for dependence on the sample geometry and notch length. Results from the uniaxial tensile test show J-shaped stress-strain curves and confirm that the amniotic membrane is a nonlinear material. The measured fracture toughness of four amniotic membranes ranged from 0.96 ± 0.11 to 1.83 ± 0.18 kJ m
-2 . Despite considering the effect of the presence of the defect on mechanical property measurement, similar fracture behaviour was observed for pre-notched and unnotched specimens, indicating that the membranes were extremely tolerant to defects. This defect-tolerant characteristic provides insight into the understanding of fetal membrane rupture., Competing Interests: We declare we have no competing interests.- Published
- 2019
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9. Systematic mechanical evaluation of electrospun gelatin meshes.
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Butcher AL, Koh CT, and Oyen ML
- Subjects
- Finite Element Analysis, Microscopy, Electron, Scanning, Tissue Engineering, Gelatin analysis, Materials Testing
- Abstract
Electrospinning is a simple and efficient process for producing sub-micron fibres. However, the process has many variables, and their effects on the non-woven mesh of fibres is complex. In particular, the effects on the mechanical properties of the fibre meshes are poorly understood. This paper conducts a parametric study, where the concentration and bloom strength of the gelatin solutions are varied, while all electrospinning process parameters are held constant. The effects on the fibrous meshes are monitored using scanning electron microscopy and mechanical testing under uniaxial tension. Mesh mechanical properties are relatively consistent, despite changes to the solutions, demonstrating the robustness of electrospinning. The gel strength of the solution is shown to have a statistically significant effect on the morphology, stiffness and strength of the meshes, while the fibre diameter has surprisingly little influence on the stiffness of the meshes. This experimental finding is supported by finite element analysis, demonstrating that the stiffness of the meshes is controlled by the volume fraction, rather than fibre diameter. Our results demonstrate the importance of understanding how electrospinning parameters influence the pore size of the meshes, as controlling fibre diameter alone is insufficient for consistent mechanical properties., (Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.)
- Published
- 2017
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10. Time-dependent fracture toughness of cornea.
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Tonsomboon K, Koh CT, and Oyen ML
- Subjects
- Animals, Biomechanical Phenomena, Materials Testing, Polymers, Stress, Mechanical, Swine, Time Factors, Cornea, Corneal Injuries, Mechanical Phenomena
- Abstract
The fracture and time-dependent properties of cornea are very important for the development of corneal scaffolds and prostheses. However, there has been no systematic study of cornea fracture; time-dependent behavior of cornea has never been investigated in a fracture context. In this work, fracture toughness of cornea was characterized by trouser tear tests, and time-dependent properties of cornea were examined by stress-relaxation and uniaxial tensile tests. Control experiments were performed on a photoelastic rubber sheet. Corneal fracture resistance was found to be strain-rate dependent, with values ranging from 3.39±0.57 to 5.40±0.48kJm(-2) over strain rates from 3 to 300mmmin(-1). Results from stress-relaxation tests confirmed that cornea is a nonlinear viscoelastic material. The cornea behaved closer to a viscous fluid at small strain but became relatively more elastic at larger strain. Although cornea properties are greatly dependent on time, the stress-strain responses of cornea were found to be insensitive to the strain rate when subjected to tensile loading., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2014
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11. Failure mechanisms in fibrous scaffolds.
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Koh CT, Strange DG, Tonsomboon K, and Oyen ML
- Subjects
- Elastic Modulus, Electrochemistry, Equipment Design, Equipment Failure Analysis, Hardness, Materials Testing, Rotation, Tensile Strength, Gelatin chemistry, Nanofibers chemistry, Nanofibers ultrastructure, Polyesters chemistry, Tissue Scaffolds
- Abstract
Polymeric fibrous scaffolds have been considered as replacements for load-bearing soft tissues, because of their ability to mimic the microstructure of natural tissues. Poor toughness of fibrous materials results in failure, which is an issue of importance to both engineering and medical practice. The toughness of fibrous materials depends on the ability of the microstructure to develop toughening mechanisms. However, such toughening mechanisms are still not well understood, because the detailed evolution at the microscopic level is difficult to visualize. A novel and simple method was developed, namely, a sample-taping technique, to examine the detailed failure mechanisms of fibrous microstructures. This technique was compared with in situ fracture testing by scanning electron microscopy. Examination of three types of fibrous networks showed that two different failure modes occurred in fibrous scaffolds. For brittle cracking in gelatin electrospun scaffolds, the random network morphology around the crack tip remained during crack propagation. For ductile failure in polycaprolactone electrospun scaffolds and nonwoven fabrics, the random network deformed via fiber rearrangement, and a large number of fiber bundles formed across the region in front of the notch tip. These fiber bundles not only accommodated mechanical strain, but also resisted crack propagation and thus toughened the fibrous scaffolds. Such understanding provides insight for the production of fibrous materials with enhanced toughness., (Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)
- Published
- 2013
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12. Branching toughens fibrous networks.
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Koh CT and Oyen ML
- Subjects
- Biocompatible Materials chemistry, Biomechanical Phenomena, Computer Simulation, Cross-Linking Reagents chemistry, Elasticity, Finite Element Analysis, Humans, Materials Testing, Models, Chemical, Models, Statistical, Pressure, Shear Strength, Software, Stress, Mechanical, Collagen chemistry, Collagen Type I chemistry
- Abstract
Fibrous collagenous networks are not only stiff but also tough, due to their complex microstructures. This stiff yet tough behavior is desirable for both medical and military applications but it is difficult to reproduce in engineering materials. While the nonlinear hyperelastic behavior of fibrous networks has been extensively studied, the understanding of toughness is still incomplete. Here, we identify a microstructure mimicking the branched bundles of a natural type I collagen network, in which partially cross-linked long fibers give rise to novel combinations of stiffness and toughness. Finite element analysis shows that the stiffness of fully cross-linked fibrous networks is amplified by increasing the fibril length and cross-link density. However, a trade-off of such stiff networks is reduced toughness. By having partially cross-linked networks with long fibrils, the networks have comparable stiffness and improved toughness as compared to the fully cross-linked networks. Further, the partially cross-linked networks avoid the formation of kinks, which cause fibril rupture during deformation. As a result, the branching allows the networks to have stiff yet tough behavior., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2012
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13. Flexion creases in soles of Singaporean newborns.
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Wong JC and Koh CT
- Subjects
- Austria, Ethnicity, Female, Humans, Infant, Newborn, Male, Singapore, Dermatoglyphics
- Published
- 1984
14. Five year prospective study of plasma renin activity and blood pressure in patients with longstanding reflux nephropathy.
- Author
-
Savage JM, Koh CT, Shah V, Barratt TM, and Dillon MJ
- Subjects
- Adolescent, Adult, Child, Chronic Disease, Female, Follow-Up Studies, Humans, Hypertension etiology, Male, Prospective Studies, Pyelonephritis physiopathology, Blood Pressure, Pyelonephritis blood, Renin blood, Vesico-Ureteral Reflux complications
- Abstract
Eight of 100 normotensive children who had pyelonephritic scarring secondary to urinary infection and vesicoureteric reflux were found in an earlier study to have increased plasma renin activity (PRA). Because the risk of these patients becoming hypertensive is between 10% and 20% and because renin activity may play a part in the pathogenesis of the hypertension, PRA and blood pressure were studied in 98 of the original group after five years of follow up. Two patients could not be traced, and other factors that might influence blood pressure or PRA led us to exclude 13 others, 10 of whom were girls taking oral hormonal contraceptives. Increased PRA was found in 11 of the remaining 85 patients but not in five of the eight patients with increased PRA in the first study. Of eight children identified as hypertensive in the follow up study, only three had had increased PRA five years previously. In normal children PRA decreases with age. In the initial study this tendency was less pronounced in children with renal scars, and in the follow up study it was reversed. This was also confirmed by PRA standard deviation scores, which showed a significant increase in PRA during the five years. PRA tends to rise in patients with pyelonephritic scars as they grow older. There was no direct correlation between blood pressure and PRA, plasma creatinine concentration, or degree of scarring. Analysis of blood pressure standard deviation scores, however, suggested an excessive rise in blood pressure during the five years.
- Published
- 1987
- Full Text
- View/download PDF
15. Rhabdomyolysis in diabetic ketoacidosis.
- Author
-
Koh CT, Cowley DM, and Savage MO
- Subjects
- Child, Humans, Male, Diabetic Ketoacidosis complications, Myoglobinuria etiology
- Published
- 1981
- Full Text
- View/download PDF
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