Delivered by Ingenta. that mechanical properties of PVA-HA-Silk composite hydrogel are enhanced with the adding of HA

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1 Mterils Express Copyright 2013 y Amerin Sientifi Pulishers All rights reserved. Printed in the United Sttes of Ameri /2013/3/265/008 doi: /mex Strt-up frition properties of poly(vinyl lohol)/nno-hydroxyptite/silk omposite hydrogel Ki Chen 1, Dekun Zhng 2,, nd Songqun Wng 1 1 Shool of Mehnil nd Eletril Engineering, Chin University of Mining nd Tehnology, Xuzhou , Chin 2 Shool of Mterils Siene nd Engineering, Chin University of Mining nd Tehnology, Xuzhou , Chin ABSTRACT Poly(vinyl lohol)/nno-hydroxyptite/silk omposite hydrogel ws synthesized y repeted freezing nd thwing with polyvinyl lohol (PVA), nno-hydroxyptite (HA) nd silk. Frition tests etween PVA-HA-Silk omposite hydrogel nd ovine knee IP: rtiulr rtilge On: St, were 07 performed Apr :31:40 on Miro-triometer. Strt-up frition mehnism of PVA-HA-Silk omposite Copyright: hydrogel Amerin ws investigted Sientifi under Pulishers different onditions. The results demonstrted tht mehnil properties of PVA-HA-Silk omposite hydrogel re enhned with the dding of HA Delivered y Ingent nd silk nd strt-up frition oeffiient dereses with the inrese of silk. Norml displement nd strt-up frition oeffiient inrese with the inrese of ontt lods nd ontt time. Temperture nd lurition solution hve less impt on norml displement. The liquid flowility of PVA-HA-Silk omposite hydrogel is improved with the inrese of temperture, whih uses the derese of strt-up frition oeffiient. In 25% ovine serum solution, proteins form oundry film on frition surfe to derese frition effetively. Keywords: Polyvinyl Alohol, Nno-Hydroxyptite, Silk, Composite Hydrogel, Frition Properties. 1. INTRODUCTION Artiulr rtilge plys n importnt role in hrterizing nd mintining the lne of synovil joint. However, n ute trum, osteorthritis nd ongenitl or quired joint diseses my use rtilge dmge nd the dmged rtilge nnot e repired euse of vsulr nd neurl nture. 1 Therefore, the joint replement is n effetive tretment to reuild the funtions of joint, suh s knee or hip, whih n provide pin relief nd inresed moility. Ultr high moleulr weight polyethylene (UHMWPE) is reserhed nd used extensively s replement mterils. But suessful joint rthroplsties of UHMWPE n mintin only 30 yers due to the exessive wer of UHMWPE prostheti leds to one Author to whom orrespondene should e ddressed. Emil: dkzhng@umt.edu.n dissolution, septi loosening nd used filure of the prostheti replement eventully. 2 4 Artifiil rtilge is onsidered s n idel implnted mteril to solve the prolem. The primry funtions of rtiulr rtilge re supporting nd redistriuting the high level of mehnil lods. It is pivotl for rtifiil rtiulr rtilge to possess oth mehnil nd frition properties to funtion nd lod-ering in vivo. Due to similr properties, PVA hydrogels hve een onsidered s n idel rtifiil rtilge implnted mteril nd the reserh of hydrogels for repiring dmged rtiulr rtilge hs inresed in reent yers. 5 PVA hydrogel, hydrophili mteril of miroellulr struture, ws investigted widely s rtifiil rtiulr rtilge replement mteril euse of its high visoelstiity, the mehnil properties of sorption nd exudtion fluids similr to nturl rtilge. 6 8 Biotive Mter. Express, Vol. 3, No. 3,

2 Mterils Express Strt-up frition properties of PVA/HA/silk omposite hydrogel Chen et l. HA n effetively improve the mehnil property nd ioomptiility of PVA hydrogel The surfe deformtion of PVA hydrogel helps to form liquid film lurition in the frition interfe nd redues the frition oeffiient of the omposite hydrogel under lod. Silk hs good ioomptiility nd low degrdtion, exellent mehnil properties, whih n improve mehnil properties of omposite hydrogel s reinforing phse. 14 The prepring method nd the mehnil properties of PVA-HA-Silk omposite hydrogel were preliminry disussed in our previous works However, strt-up frition properties nd the reltions mong strt-up frition properties nd preprtion prmeters, ontt lods, sliding speeds, ontt time, tempertures nd lurints of PVA-HA-Silk omposite hydrogel hve not een investigted in these studies. In this pper, in order to reserh strt-up frition properties of PVA-HA-Silk omposite hydrogel, omposite hydrogels with different PVA-HA- Silk rtios were prepred y repeted freezing nd thwing nd the strt-up frition properties were investigted under different experimentl onditions. 2. EXPERIMENTAL DETAILS 2.1. Smple Preprtion ws nturl reovery t lest 1hinovine serum efore IP: On: St, 07 experiment. Apr :31:40 Copyright: Amerin Sientifi Pulishers The lower speimen (size ws 20 mm PVA (Polymeriztion degree of 1750 ± 50, Sinophrm Delivered y 15 Ingent mm 1.5 mm) ws PVA-HA-Silk omposite hydrogel Chemil Regent Co., Ltd.), n-ha (C 10 (PO 4 6 (OH) 2, with nylon mtrix nd ws swelled for 48 h in deionized Nnjing Emperor Nno Mteril Co., Ltd.) nd silk of wter efore experiment. A5 qulity grde were hosen s the rw mteril. First, Bovine knee rtiulr rtilge ws onded on the metl degummed silk ws mehnilly roken out 1 mm lok of 8 mm onneted with jig y pin. Jig, pin 2 mm. 15 Seond, ultrsoni virtion ws used to mke nd metl lok ws set in the sme line (Fig. 1). The silk dispersed in deionized wter. When they were evenly lower speimen ws fixed in the vessel. The vessel ws distriuted, n-ha nd PVA were dded into the solution. filled with ovine serum of 25% onentrtion nd the The totl weight of the eker nd the solution ovine knee rtiulr rtilge nd PVA-HA-Silk ompos- were weighed nd reorded. Then they were put into ite hydrogel were ompletely immersed in ovine serum. eletroni onstnt temperture wter th t 95 C. As First, speimens ontted for some time. Then the lower heting nd stirring onstntly, the evporting moisture speimen ws fixed nd the upper speimen slid. Norml would eventully led to the onentrtion of PVA solution signifintly higher thn the initil onentrtion. So experiment repeted three times. Support lod rnge of displements nd tngentil fores were determined. Eh the evported wter needs to e supplemented to ensure rtiulr surfe is out MP in the ourse of the onentrtion of PVA solution. The PVA solution ws the mpign of the ovine knee. The ontt lods of the stirred onstntly until it ws ompletely dissolved. Then the eker ws tken from the wter th to the ultrsoni virtion (30 min, 25 C). After 2 h 3 h, PVA-HA-Silk Sensor omposite solution ws lid in the ir to deerte, then poured into the mold nd frozen t 20 Tool holder C for 10 h Jig 12 h in the low temperture freezer. The speimens were Cylinder indenter tken out nd thwed for 2 hours t room temperture Solution Speimen (25 C) for the next freezing proess. The ove freezingthwing proess ws repeted for 9 times. 15 In this wy, PVA-HA-Silk omposite hydrogel speimens with different mixture rtios were prepred respetively. Four kinds of PVA-HA-Silk omposite hydrogel of the optiml Tle I. Four kinds of PVA-HA-silk omposite hydrogel. Speimen Freezingno. PVA (%) HA (%) Silk (%) thwing yles mehnil properties were seleted y orthogonl experiment of PVA-HA-Silk. 15 Their prmeters re shown in Tle I Strt-Up Frition Properties UMT-II multi-funtionl miro-frition test mhine ws used to mesure the strt-up frition oeffiient of PVA- HA-Silk omposite hydrogel. The upper speimen ws fresh ovine knee rtiulr rtilge nd the surfe ws smooth (size of 8 mm 1.5 mm). The ottom surfe of rtilge ws plnished y polishing mhine. Then the rtilge ws put into physiologil sline nd kept in 20 C temperture ox. 16 Mrounds 17 onfirmed tht mehnil properties of the rtilge in the low temperture of 20 C re ffeted. The speimen of rtilge Vessel Fig. 1. Experimentl setup for frition oeffiient testing of PVA-HAsilk omposite hydrogel. 266 Mter. Express, Vol. 3, 2013

3 Strt-up frition properties of PVA/HA/silk omposite hydrogel Chen et l. Mterils Express Tle II. Experimentl prmeters for frition testing of -PVA-HA-silk omposite hydrogel. Influening ftors Experimentl onditions Contt lod (N) 30, 40 Slide speed (mm/s) 1, 4, 7 Contt time (min) 1/60, 1/2, 1, 3, 10, 45 Environmentl temperture ( C) 25, 30, 37 Lurition onditions Bovine serum of 25% dilution, hyluroni id solution experiment re 30 N nd 40 N ording to the ontt stresses of 0.58 MP nd 0.8 MP The test prmeters re shown in Tle II. inreses with the ontt re of frition surfe inresing euse the surfe of PVA-HA-Silk omposite hydrogel is prone to deform t lods. The frition oeffiient egins to derese fter 10.4 mm euse PVA-HA-Silk omposite hydrogel hs strin hysteresis. 22 The deformtion reovery is ompleted when the frition oeffiient dereses to the minimum. The tngentil deformtion is out 0.8 mm from the urve. Then ovine knee rtiulr rtilge slides in the opposite diretion. The frition oeffiient inreses rpidly to the mximum nd then redues Influene of Preprtion Prmeters 3. RESULTS AND DISCUSSION 3.1. The Strt-Up Frition Mehnism Figure 2 shows norml displement nd frition oeffiient for PVA15%-HA2%-Silk0.6% omposite hydrogel during sliding. The initil slide position ws referene zero position nd the upwrd diretion ws positive diretion (Fig. 3()). When the upper speimen slides to 1.8 mm from 0 mm, the frition oeffiient will rise rpidly nd reh the mximum ( m ). The norml deformtion of the sliding Silk improves mehnil properties nd triologil PVA-HA-Silk omposite hydrogel IP: is lrge nd the initil On: St, 07 Apr :31:40 slide is similr to the liming proess Copyright: until theamerin frition Sientifi Pulishers properties of omposite hydrogel s reinforing Ingent phse. Therefore, the strt-up frition Delivered y oeffiient oeffiient rehes m (Fig. 3()). When ovine knee rtiulr rtilge slides off the deformtion zone, frition oeffiient dereses (Fig. 3()). The upper speimen ompletely pssed through the slope of the groove in the lower speimen 16 nd the norml displement rehes the mximum t 10 mm (Fig. 3(d)). Then the upper speimen slides k nd PVA-HA- Silk omposite hydrogel restores the originl deformtion. However, PVA-HA-Silk omposite hydrogel is visoelsti mteril. The fritionl resistne of the frition pir Figure 4 shows norml displement nd frition oeffiient of four formuls PVA-HA-Silk omposite hydrogel (Tle I). The results re showed in Tle III. Mehnil properties of PVA-HA-Silk omposite hydrogel re improved with the dding of HA nd silk nd the strt-up frition oeffiient of PVA-HA-Silk omposite hydrogel dereses with the inrese of silk. However, with the inrese of HA, strt-up frition oeffiient inreses euse HA hs oervtion funtion to form reltively lrger prtiles nd hinder the of PVA15%-HA2.0%-Silk1.0% omposite hydrogel is the minimum. () () Noml Displement/mm tngentil deformtion Sliding displement/mm of deep Fig. 2. Vrition urves of norml displement nd frition oeffiient for PVA-HA-silk omposite hydrogel during sliding (30 N, 1 minute, 4 mm/s, 25% ovine serum, 37 C). Frition oeffiient () (d) Fig. 3. Strt-up frition mehnism of PVA-HA-silk omposite hydrogel. Mter. Express, Vol. 3,

4 Mterils Express Strt-up frition properties of PVA/HA/silk omposite hydrogel Chen et l. Nonml Displement/mm : PVA15%-HA2%-Silk0.6% : PVA15%-HA2%-Silk1.0% d Frition offiient 0.10 : PVA15%-HA3%-Silk0.6% d: PVA15%-HA3%-Silk1.0% d Fig. 4. Vrition urves of norml displement nd frition oeffiient of different ompound PVA-HA-silk omposite hydrogel (30 N, 1 min, 4 mm/s, 37 C, 25% ovine serum). Tle III. Norml displement nd strt-up frition oeffiient of four groups PVA-HA-silk omposite hydrogel. Speimen no. Z m (mm) m IP: On: St, 07 Apr :31:40 Copyright: Amerin Sientifi 3.5. Influene Pulishers of Contt Time Delivered y Ingent 3.3. Influene of Contt Lod The ovine knee rtiulr rtilge moves upwrd with the slide nd the norml displements inrese with inresing ontt lods s shown in Figure 5(). This is euse the lrger deformtion of PVA-HA-Silk omposite hydrogel leds to lrger displement with inresing ontt lod. Figure 5() shows tht frition oeffiient inreses with the inrese of ontt lod. The ovine knee rtiulr rtilge slides on pre-deformtion zone of the PVA- HA-Silk omposite hydrogel in initil stge. The norml displement nd the frition oeffiient inreses with the inrese of ontt lod fter the ovine knee rtiulr rtilge slides off the pre-deformtion zone. Contt re of the ovine knee rtiulr rtilge nd the PVA- HA-Silk omposite hydrogel inreses with the inresing lod. The PVA-HA-Silk omposite hydrogel hs lrge deformtion fter long time ompression nd the ontt depth inreses. Then the frition oeffiient inreses with inresing sliding resistne etween the ovine knee rtiulr rtilge nd PVA-HA-Silk omposite hydrogel Influene of Sliding Speed Norml displement nd frition oeffiient with sliding displement hnges for PVA15%-HA2%-Silk1.0% omposite hydrogel t different sliding speeds re shown in Figure 6 nd Tle IV. The lrger the sliding speed resulted in lower moving-up speed of norml displement nd smller the norml displement when the sliding ended. At the initil pre-deformtion zone, greter the tngentil resistne need to e overome when the speimen slides. Therefore, the strt-up frition oeffiient inreses with inresed sliding speed. Frition oeffiient nd norml displement with sliding displement hnges for PVA15%-HA2%-Silk1.0% omposite hydrogel t different ontt time re shown in Figure 7. The norml displement of the upper speimen is negtive vlue t the ontt time of 1 s nd 30 s (Tle V), suggesting tht dropping of the upper Norml Displement/mm :30N ---:40N () Norml displement Frition oeffiient () Frition oeffiient Fig. 5. Vrition urves of norml displement nd frition oeffiient for PVA-HA-silk omposite hydrogel t different ontt lods (1 min, 4 mm/s, 37 C, 25% ovine serum). 268 Mter. Express, Vol. 3, 2013

5 Strt-up frition properties of PVA/HA/silk omposite hydrogel Chen et l. Mterils Express :1mm/s ---:4mm/s ---:7mm/s 0.14 Norml Displement/mm 0.01 Frition oeffiient Sliding displement/mm () Norml displement Sliding displement/mm () Frition oeffiient Fig. 6. Vrition urves of norml displement nd frition oeffiient for PVA-HA-silk omposite hydrogel t different sliding speeds (30 N, 1 min, 37 C, 25% ovine serum). Tle IV. Norml displement nd strt-up frition oeffiient t different slide speed. Slide speed (mm/s) Z m (mm) m speimen upon the elongted ontt time. In the eginning, the pre-deformtion zone of the lower speimen is smll due to the short ontt time. However, the lower speimen ontinued to deform upon the dropping IP: On: St, 07 Apr :31:40 Copyright: Amerin Sientifi of the upper Pulishers speimen, expressed s the negtive norml Ingent displement. Suh deformtion inreses with the Delivered y inrese of ontt time. Therefore, the lower speimen Norml Displement/mm :1s ---:30s ---:1min ---d:3min ---e:10min ---f:45min d e f Frition oeffiient Fig. 7. Vrition urves of norml displement nd frition oeffiient for PVA-HA-silk omposite hydrogel t different ontt time (30 N, 4 mm/s, 37 C, 25% ovine serum). Mter. Express, Vol. 3,

6 Mterils Express Strt-up frition properties of PVA/HA/silk omposite hydrogel Chen et l. Tle V. Norml displement nd strt-up frition oeffiient t different ontt time. Contt time (min) Z m (mm) m 1/ / Tle VI. Norml displement nd strt-up frition oeffiient t different environmentl temperture. Environmentl temperture ( C) Z m (mm) m Influene of Lurint deformtion zone, the tngentil resistne nd required time of sliding off the pre-deformtion zone inreses with the elongted ontt time, leding to mximized frition oeffiient Influene of Temperture With the inresing of the temperture, the norml displement hs no signifint hnge nd strt-up frition oeffiient dereses in Figure 8 (Tle VI). PVA-HA- Silk omposite hydrogel is iphsi mteril of liquid nd solid phse. Solid phse hs gret impt on the norml displement. However, the physil properties of solid phse re mintined when the temperture inrese from 25 Cto37 C. So the norml displement IP: hs no signifint hnge. But the liquid flowility Copyright: of PVA-HA-Silk Amerin Sientifi teins in 25% Pulishers ovine serum, whih form oundry film On: St, 07 theapr 25% 2018 ovine 20:31:40 serum (Tle VII). There re lot of pro- omposite hydrogel is enhned with the inresedelivered of tem- y on Ingent the frition surfe of PVA-HA-Silk omposite hydro- perture nd the surfe luriting film of PVA-HA-Silk omposite hydrogel is esily formed. Therefore, the strtup frition oeffiient dereses. The essene of the lurint in the humn ody is mixture of plsm nd hyluroni id. 23 Hyluroni id (IC) is hin polymer, whih determines the visosity of the lurint. When it is preipitted y eti id, the lurint visosity is redued to the vlue equivlent to the visosity of wter. Ftors ffeting the visosity of the lurint inlude the onentrtion of hlyluroni id, hyluroni id degree of polymeriztion, lurint type nd onentrtion of the slt nd the lurint ph nd temperture. Compred with other ftors, temperture hs less effet on lurint visosity. 24 It n e seen from Figure 9 tht two kinds of lurint hve no signifint impt on the norml displement, ut the strt-up frition oeffiient in the hyluroni id is signifintly higher thn the strt-up frition oeffiient in gel to derese frition effetively. Therefore, strt-up frition oeffiient of PVA-HA-Silk omposite hydrogel in the 25% ovine serum is signifintly lower :25 ---:30 ---: Norml Displement/mm Frition oeffiient Fig. 8. Vrition urves of norml displement nd frition oeffiient for PVA-HA-silk omposite hydrogel t different tempertures (30 N, 4 mm/s, 1 min, 25% ovine serum). 270 Mter. Express, Vol. 3, 2013

7 Strt-up frition properties of PVA/HA/silk omposite hydrogel Chen et l. Mterils Express 0 ---:ovine serum ---:hyluroni id 0.20 Norml Displement/mm Frition oeffiient Fig. 9. Vrition urves of norml displement nd frition oeffiient for PVA-HA-silk omposite hydrogel t different lurints (30 N, 4 mm/s, 1 min, 37 C). Tle VII. Norml displement nd strt-up frition oeffiient t different lurition onditions. Lurition onditions Z m (mm) m Bovine serum of 25% dilution Hyluroni id solution CONCLUSION HA nd silk n improve mehnil properties of PVA- HA-Silk omposite hydrogel nd silk improves triologil properties of omposite hydrogel s reinforing phse. Strt-up frition oeffiient of PVA15%, HA2.0%, Silk1.0% is the minimum. Norml displement nd strtup frition oeffiient inreses with the inresing of ontt lods, ontt time euse of pre-deformtion zone inresing. Temperture nd lurition solution hve less impt on norml displement. The liquid flowility of PVA-HA-Silk omposite hydrogel is reinfored with the inrese of temperture nd the surfe luriting film of PVA-HA-Silk omposite hydrogel is esily formed. Proteins in 25% ovine serum form oundry film on the frition surfe of PVA-HA-Silk omposite hydrogel to derese frition effetively. Aknowledgments: This reserh is supported y Speilized Reserh Fund for the Dotorl Progrm of Higher Edution (Grnt No ), the Triology Siene Fund of Stte Key Lortory of Triology (SKLTKF12A06) nd A Projet Funded y the Priority Ademi Progrm Development of Jingsu Higher Edution Institutions (PAPD). Referenes nd Notes 1. Y. Shi nd D. S. Xiong; Mirostruture nd frition properties of PVA/PVP hydrogels for rtiulr rtilge repir s funtion of polymeriztion degree nd polymer onentrtion; Wer (In Press) (2013). IP: On: St, 07 Apr :31:40 Copyright: Amerin Sientifi Pulishers Delivered y Ingent 2. A. Chnd, A. K. Mukhopdhyy, D. Bsu, nd S. Chtterjee; Wer nd frition ehviour of UHMWPE-lumin omintion for totl hip replement; Cerm. Int. 23, 437 (1997). 3. H. J. Cho, W. J. Wei, H. C. Ko, nd C. K. Cheng; Wer ehvior of UHMWPE sliding on rtifiil hip rthroplsty mterils; Mter. Chem. Phys. 88, 9 (2004). 4. W. Wu, W. Q. Wng, D. Z. Yng, nd M. Qi; Stent expnsion in urved vessel nd their intertions: A finite element nlysis; J. Biomeh. 40, 2580 (2007). 5. A. S. Miolo, M. N. Amdo, J. S. Gonzlez, nd V. A. Alvrez; Development nd hrteriztion of poly (vinyl lohol) sed hydrogels for potentil use s n rtiulr rtilge replement; Mt. Si. Eng. C-Mter. 32, 1490 (2012). 6. B. Ji, J. Go, Y. Z. M, Z. Q. Gu, G. Q. Liu, nd H. B. Xue; Mnufture of prostheti nuleus nd nlysis of stress-relxtion properties; J. Univ. Si. Tehnol. B 27, 589 (2005). 7. Z. Q. Gu, J. M. Xio, nd X. H. Zhng; The development of kind of rtifiil rtiulr rtilge PVA hydrogel; J. Biomed. Eng. 16, 13 (1999). 8. Z. Q. Gu nd J. M. Xio; The development of rtifiil rtilge PVA hydrogel; Biomed. Mter. Eng. 8, 75 (1998). 9. Y. J. Wng, Q. Liu, Y. D. Zheng, nd G. Wu; The ompounding in situ y preipittion of poly (vinyl lohol) hydrogel with hydroxyptite nd investigtion on the struture nd properties; Chinese J. Biomed. Eng. 24, 150 (2005). 10. G. Wu, C. T. Wng, nd W. G. Zhng; The ftors of speeds nd lods on the triologil properties of PVA-H/HA omposites; J. Appl. Polym. Si. 106, 3908 (2007). 11. Y. D. Zheng, Y. J. Wng, X. F. Chen, Q. Liu, nd G. Wu; Chrteriztion nd properties of poly (vinyl lohol)/hydroxylptite hydrogels prepred y ompound in situ with sol-gel method; Chem. Res. Chinese U. 26, 1735 (2005) 12. J. K. Ktt, M. S. Mrolongo, nd A. M. Lowrnn; Frition nd wer hrteristis of PVA/PVP hydrogels s syntheti rtiulr rtilge, Proeedings of the IEEE 30th Annul Northest Bioengineering Conferene, Springfield, MA, USA, April (2004). 13. H. Nno, S. Hosokw, nd S. Mori; Reltion etween moleulr struture of gels nd frition properties under low lod in wter; Jpn. J. Appl. Phys. 46, 968 (2001). 14. D. K. Zhng, H. R. Cheng, Y. Q. Shen, nd S. R. Ge; Reserh on the frition properties of strt-up for PVA-silk omposite hydrogel; J. Chin. U. Min. Tehnol. 37, 819 (2008). Mter. Express, Vol. 3,

8 Mterils Express Strt-up frition properties of PVA/HA/silk omposite hydrogel Chen et l. 15. D. K. Zhng, K. Chen, L. Wu, D. G. Wng, nd S. R. Ge; Synthesis nd hrteriztion of PVA-HA-silk omposite hydrogel y orthogonl experiment; J. Bioni. Eng. 9, 234 (2012). 16. S. H. Qin, S. R. Ge, nd Q. L. Wng; The fritionl oeffiient of ovine knee rtiulr rtilge; J. Bioni. Eng. 3, 79 (2006). 17. A. Mrounds, M. Ujihir, nd T. Ssd; Influene of ding durtion on the strt-up rtilge; J. Bone. Joint. Surg. 50, 166 (1968). 18. S. H. Qin nd Q. L. Wng; Reserh on frition ehvior from ovine knee rtiulr rtilge; Triology 26, 397 (2006). 19. J. Pikrd, E. Inghm, nd J. Egn; Investigtion into the effet of proteoglyn moleules on the triologil properties of rtilge joint tissues; P. I. Meh. Eng. H. 212, 177 (1998). 20. Z. M. Jim, J. Pikrd, nd H. Forster; Fritionl ehvior of ovine rtiulr rtilge; Biorheology 37, 57 (2000). 21. R. J. Covert, R. D. Ott, nd D. N. Ku; Frition hrteristis of potentil rtiulr rtilge iomteril; Wer 255, 1064 (2003). 22. K. S. Anseth, C. N. Bowmn, nd L. B. Pepps; Mehnil properties of hydrogels nd their experimentl determintion; Biomterils 17, 1647 (1996). 23. D. V. Dvies; Properties of synovil fluid; Pro. Instn. Meh. Engrs. 181, 25 (1966). 24. A. G. Ogston nd J. E. Stnier; The dimensions of the prtile of the hyluroni id omplex in synovil fluid; Biohemil. J. 49, 585 (1951). Reeived: 29 My Revised/Aepted: 4 August IP: On: St, 07 Apr :31:40 Copyright: Amerin Sientifi Pulishers Delivered y Ingent 272 Mter. Express, Vol. 3, 2013

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Broken rice facts. Physical and Functional Characteristics of Broken Rice Kernels. Parboiling Process. May 23, Production of broken rice 14-10% My 23, 218 Physil nd Funtionl Chrteristis of Broken Rie Kernels Broken rie fts Redued eonomi vlue Undesirle Inevitle Ree M. Brue University of Arknss Advisor: Dr. Griffiths G. Atungulu Inexpensive Affets