Displaying publications 41 - 60 of 112 in total

Abstract:
Sort:
  1. PVA-PEG physically cross-linked hydrogel film as a wound dressing: experimental design and optimization
    Ahmed AS, Mandal UK, Taher M, Susanti D, Jaffri JM
    Pharm Dev Technol, 2018 Oct;23(8):751-760.
    PMID: 28378604 DOI: 10.1080/10837450.2017.1295067
    The development of hydrogel films as wound healing dressings is of a great interest owing to their biological tissue-like nature. Polyvinyl alcohol/polyethylene glycol (PVA/PEG) hydrogels loaded with asiaticoside, a standardized rich fraction of Centella asiatica, were successfully developed using the freeze-thaw method. Response surface methodology with Box-Behnken experimental design was employed to optimize the hydrogels. The hydrogels were characterized and optimized by gel fraction, swelling behavior, water vapor transmission rate and mechanical strength. The formulation with 8% PVA, 5% PEG 400 and five consecutive freeze-thaw cycles was selected as the optimized formulation and was further characterized by its drug release, rheological study, morphology, cytotoxicity and microbial studies. The optimized formulation showed more than 90% drug release at 12 hours. The rheological properties exhibited that the formulation has viscoelastic behavior and remains stable upon storage. Cell culture studies confirmed the biocompatible nature of the optimized hydrogel formulation. In the microbial limit tests, the optimized hydrogel showed no microbial growth. The developed optimized PVA/PEG hydrogel using freeze-thaw method was swellable, elastic, safe, and it can be considered as a promising new wound dressing formulation.
    Matched MeSH terms: Rheology
  2. Superabsorbent hydrogel from oil palm empty fruit bunch cellulose and sodium carboxymethylcellulose
    Salleh KM, Zakaria S, Sajab MS, Gan S, Kaco H
    Int J Biol Macromol, 2019 Jun 15;131:50-59.
    PMID: 30844455 DOI: 10.1016/j.ijbiomac.2019.03.028
    A green regenerated superabsorbent hydrogel was fabricated with mixtures of dissolved oil palm empty fruit bunch (EFB) cellulose and sodium carboxymethylcellulose (NaCMC) in NaOH/urea system. The formation of hydrogel was aided with epichlorohydrin (ECH) as a crosslinker. The resultant regenerated hydrogel was able to swell >80,000% depending on the NaCMC concentrations. The hydrogel absorbed water rapidly upon exposure to water up to 48 h and gradually declined after 72 h. The crosslinked of covalent bond of COC between dissolved EFB cellulose (EFBC) with NaCMC was confirmed with Attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy. Crystallinity and thermal stability of the hydrogel samples were depended on the concentrations of NaCMC, crosslinking, and swelling process. The strength and stability of crosslinked network was studied by examining the gel fraction of hydrogel. This study explored the swelling ability and probable influenced factors towards physical and chemical properties of hydrogel.
    Matched MeSH terms: Rheology
  3. Observations of acoustic streaming fields around an oscillating ultrasonic file
    Ahmad M, Roy RA, Kamarudin AG
    Endod Dent Traumatol, 1992 Oct;8(5):189-94.
    PMID: 1302678
    The steady acoustic streaming generated around straight and precurved oscillating ultrasonic files driven by the Piezon-Master 400 unit was examined in the free field and in small channels using a stereomicroscope. In addition, the effect of file-wall contact on streaming production was also investigated. The results indicated that the ultrasonic files can generate acoustic streaming both in the free field and in the small channel. Higher velocity streaming was observed when smaller size files were employed and when the file was precurved. Light file-wall contact did not totally inhibit streaming while severe file-wall contact inhibited movement of the file and, as a result, no streaming was observed. The positions and length scales of the streaming vortices appeared to be influenced by the presence of boundaries. In the free field, two rows of vortices were situated along the sides of the file while in the small channel, the vortices were positioned above the surface of the file. These results indicated that it is possible for acoustic streaming to occur in a confined space as in a root canal provided that severe file-wall contact is avoided. It is therefore recommended that light filing or allowing the file to freely vibrate during some stage of treatment should be carried out in order to generate streaming in the root canal.
    Matched MeSH terms: Rheology
  4. Effects of ultraviolet irradiation on the physicochemical and functional properties of gum arabic
    Kuan YH, Bhat R, Senan C, Williams PA, Karim AA
    J Agric Food Chem, 2009 Oct 14;57(19):9154-9.
    PMID: 19757813 DOI: 10.1021/jf9015625
    The impact of ultraviolet (UV) irradiation on the physicochemical and functional properties of gum arabic was investigated. Gum arabic samples were exposed to UV irradiation for 30, 60, 90, and 120 min; gum arabic was also treated with formaldehyde for comparison. Molecular weight analysis using gel permeation chromatography indicated that no significant changes occurred on the molecular structure on the samples exposed to UV irradiation. Free amino group analysis indicated that mild UV irradiation (30 min) could induce cross-linking on gum arabic; this result was comparable with that of samples treated with formaldehyde. However, viscosity break down was observed for samples exposed to UV irradiation for longer times (90 and 120 min). All irradiated and formaldehyde-treated samples exhibited better emulsification properties than unirradiated samples. These results indicate that UV-irradiated gum arabic could be a better emulsifier than the native (unmodified) gum arabic and could be exploited commercially.
    Matched MeSH terms: Rheology
  5. Effects of κ-carrageenan on rheological properties of dually modified sago starch: Towards finding gelatin alternative for hard capsules
    Fakharian MH, Tamimi N, Abbaspour H, Mohammadi Nafchi A, Karim AA
    Carbohydr Polym, 2015 Nov 5;132:156-63.
    PMID: 26256336 DOI: 10.1016/j.carbpol.2015.06.033
    Composite sago starch-based system was developed and characterized with the aim to find an alternative to gelatin in the processing of pharmaceutical capsules. Dually modified (Hydrolyzed-Hydroxypropylated) sago starches were combined with κ-carrageenan (0.25, 0.5, 0.75, and 1%). The rheological properties of the proposed composite system were measured and compared with gelatin as reference material. Results show that combination of HHSS12 (Hydrolysed-hydroxypropylated sago starch at 12h) with 0.5% κ-carrageenan was comparable to gelatin rheological behavior in pharmaceutical capsule processing. The solution viscosity at 50 °C and sol-gel transition of the proposed composite system were comparable to those of gelatin. The viscoelastic moduli (G' and G") for the proposed system were lower than those of gelatin. These results illustrate that by manipulation of the constituents of sago starch-based composite system, a suitable alternative to gelatin can be produced with comparable properties and this could find potential application in pharmaceutical capsule industry.
    Matched MeSH terms: Rheology
  6. Comparison of physicochemical and functional properties of duck feet and bovine gelatins
    Kuan YH, Nafchi AM, Huda N, Ariffin F, Karim AA
    J Sci Food Agric, 2017 Mar;97(5):1663-1671.
    PMID: 27465360 DOI: 10.1002/jsfa.7970
    BACKGROUND: Previous studies have indicated that duck feet are a rich source of gelatin extractable from avian sources. In this study, the physicochemical and functional properties of avian gelatin extracted from duck feet (DFG) with acetic acid were compared with those of commercial bovine gelatin (BG).

    RESULTS: The yield of DFG obtained in this study was 7.01 ± 0.31%. High-performance liquid chromatography analysis indicated that the imino acid content was slightly lower for DFG compared with BG (P < 0.05). Differences in molecular size and amino acids between DFG and BG were also observed. The isoelectric points of DFG and BG were at pH 8 and 5 respectively, and the overall protein solubility of BG was higher than that of DFG. Gels prepared from BG exhibited higher bloom strength, viscosity and clarity and were darker in colour compared with DFG gels (P < 0.05). The gelling and melting points of BG were 21.8 and 29.47 °C respectively, while those of DFG were 20.5 and 27.8 °C respectively. BG exhibited slightly better emulsifying and foaming properties compared with DFG.

    CONCLUSION: Although some differences between DFG and BG were observed, the disparities were small, which indicates that DFG could be exploited commercially as an alternative source of gelatin. © 2016 Society of Chemical Industry.

    Matched MeSH terms: Rheology
  7. Investigation of the possibility of using waste cooking oil as a rejuvenating agent for aged bitumen
    Zargar M, Ahmadinia E, Asli H, Karim MR
    J Hazard Mater, 2012 Sep 30;233-234:254-8.
    PMID: 22818590 DOI: 10.1016/j.jhazmat.2012.06.021
    The ageing of the bitumen during storage, mixing, transport and laying on the road, as well as in service life, are the most important problems presented by the use of bitumen in pavements. This paper investigates the possibility of using waste cooking oil (WCO), which is a waste material that pollutes landfills and rivers, as an alternative natural rejuvenating agent for aged bitumen to a condition that resembles the original bitumen. With this target, the physical and chemical properties of the original bitumen, aged bitumen and rejuvenated bitumen were measured and compared by the bitumen binder tests - softening point, penetration, Brookfield viscosity, dynamic shear rheometer and Fourier transform infrared spectroscopy. In addition, the behaviour of the WCO rejuvenated bitumen is investigated and compared with virgin bitumen after using the rolling thin film oven ageing process. In general, the results showed that using 3-4% of WCO the aged bitumen group 40/50 was rejuvenated to a condition that closely resembled the physical, rheological properties of the original bitumen (80/100), however, there was a difference in the tendency to ageing between the WCO rejuvenated bitumen and the virgin bitumen during mixing, transport and laying on the road.
    Matched MeSH terms: Rheology
  8. Curcumin-laden hyaluronic acid-co-Pullulan-based biomaterials as a potential platform to synergistically enhance the diabetic wound repair
    Shah SA, Sohail M, Minhas MU, Khan S, Hussain Z, Mahmood A, et al.
    Int J Biol Macromol, 2021 Aug 31;185:350-368.
    PMID: 34171251 DOI: 10.1016/j.ijbiomac.2021.06.119
    Injectable hydrogel with multifunctional tunable properties comprising biocompatibility, anti-oxidative, anti-bacterial, and/or anti-infection are highly preferred to efficiently promote diabetic wound repair and its development remains a challenge. In this study, we report hyaluronic acid and Pullulan-based injectable hydrogel loaded with curcumin that could potentiate reepithelization, increase angiogenesis, and collagen deposition at wound microenvironment to endorse healing cascade compared to other treatment groups. The physical interaction and self-assembly of hyaluronic acid-Pullulan-grafted-pluronic F127 injectable hydrogel were confirmed using nuclear magnetic resonance (1H NMR) and Fourier transformed infrared spectroscopy (FT-IR), and cytocompatibility was confirmed by fibroblast viability assay. The CUR-laden hyaluronic acid-Pullulan-g-F127 injectable hydrogel promptly undergoes a sol-gel transition and has proved to potentiate wound healing in a streptozotocin-induced diabetic rat model by promoting 93% of wound closure compared to other groups having 35%, 38%, and 62%. The comparative in vivo study and histological examination was conducted which demonstrated an expeditious recovery rate by significantly reducing the wound healing days i.e. 35 days in a control group, 33 days in the CUR suspension group, 21 days in unloaded injectable, and 13 days was observed in CUR loaded hydrogel group. Furthermore, we suggest that the injectable hydrogel laden with CUR showed a prompt wound healing potential by increasing the cell proliferation and serves as a drug delivery platform for sustained and targeted delivery of hydrophobic moieties.
    Matched MeSH terms: Rheology
  9. Purification, characterization and comparative studies of spray-dried bacterial cellulose microparticles
    Amin MC, Abadi AG, Katas H
    Carbohydr Polym, 2014 Jan;99:180-9.
    PMID: 24274495 DOI: 10.1016/j.carbpol.2013.08.041
    Bacterial cellulose (BC) is a biopolymer with significant potential for the development of novel materials. This work aimed to prepare and characterize BC powders from nata de coco, and assess the possible enhancement of the powder properties by spray drying. Therefore, BC powders prepared by acid treatment and mechanical processing were spray-dried, and characterized according to their morphology, flowability, thermal stability, water retention capacity, and compared with commercial microcrystalline cellulose (MCC). The powders redispersibility and suspensions rheology were also evaluated. SEM showed that spray-dried BC microparticles exhibited semispherical shape and had flow rate of 4.23 g s(-1) compared with 0.52 g s(-1) for MCC. Particle size analysis demonstrated that spray-dried BC microparticles could be redispersed. TGA showed that BC samples had higher thermal stability than MCC. Water retention capacities of BC samples were greater than MCC. These findings provide new insight on the potential applications of spray-dried BC as a promising pharmaceutical excipient.
    Matched MeSH terms: Rheology
  10. Fulltext Natural convection heat transfer in an oscillating vertical cylinder
    Khan I, Ali Shah N, Tassaddiq A, Mustapha N, Kechil SA
    PLoS One, 2018;13(1):e0188656.
    PMID: 29304161 DOI: 10.1371/journal.pone.0188656
    This paper studies the heat transfer analysis caused due to free convection in a vertically oscillating cylinder. Exact solutions are determined by applying the Laplace and finite Hankel transforms. Expressions for temperature distribution and velocity field corresponding to cosine and sine oscillations are obtained. The solutions that have been obtained for velocity are presented in the forms of transient and post-transient solutions. Moreover, these solutions satisfy both the governing differential equation and all imposed initial and boundary conditions. Numerical computations and graphical illustrations are used in order to study the effects of Prandtl and Grashof numbers on velocity and temperature for various times. The transient solutions for both cosine and sine oscillations are also computed in tables. It is found that, the transient solutions are of considerable interest up to the times t = 15 for cosine oscillations and t = 1.75 for sine oscillations. After these moments, the transient solutions can be neglected and, the fluid moves according with the post-transient solutions.
    Matched MeSH terms: Rheology
  11. Fulltext Effect of temperature and concentration on rheological properties pomelo juice concentrates
    Luqman Chuah, A., Russly A.R., Keshani, S.
    International Food Research Journal, 2012;19(2):553-562.
    MyJurnal
    Rheology is the science of deformation and flow behavior of fluid. Knowledge of rheological properties of fluid foods and their variation with temperature and concentration have been globally important for industrialization of food technology for quality, understanding the texture, process engineering application, correlation with sensory evaluation, designing of transport system , equipment design (heat exchanger and evaporator ), deciding pump capacity and power requirement for mixing. The aim of this study was to determine the rheological behavior of pomelo juice at different concentrations (20-60.4%) and temperatures (23-60°C) by using a rotational rotational Haake Rheostress 600 rheometer. Pomelo juice was found to exhibit both Newtonian and Non-Newtonian behavior. For lower concentration the Newtonian behavior is observed while at higher concentration Non-Newtonian behavior was observed. Standard error (SE) method was selected on the basis to carry out the error analysis due to the best fit model. For the four models the values of SE show that the Herschel-Bulkley and Power Law models perform better than the Bingham and Casson models but Herschel-Bulkley model is true at higher concentration. The rheological model of pomelo juice, incorporating the effects of concentration and temperature was developed. The master-curve was investigated for comparing data from different products at a reference temperature of 40°C. Multiple regression analysis indicated Master-Curve presents good agreement for pomelo juice at all concentrations studied with R2>0.8.
    Matched MeSH terms: Rheology
  12. Haruan (Channa striatus) incorporated palm-oil creams : formulation and stability studies
    Sheikh KA, Baie SH, Khan GM
    Pak J Pharm Sci, 2005 Jan;18(1):1-5.
    PMID: 16431376
    Topical emulsions stabilized with non-ionic emulsifiers have been an attractive alternative as vehicles for drug delivery, particularly for the patients suffering from dermatological problems. Haruan (a natural wound healer) creams were formulated with different types of emulsifiers (Tween 80 and Span 80) using different grades of Malaysian Palm-oleins (DFPL 56, 60, 62 and 65). The stability (at room temperature and accelerated stability testing) of the various creams was evaluated at different temperatures (5, 25 and 45 degrees C) for a period of 6 months by measuring changes in droplet size, viscosity and percentage oil separation. The emulsifier type and concentration showed pronounced effect on the physicochemical properties of the cream, whereas storage time did not. This study suggested that the choice of emulsifiers and concentration of haruan extract are the most important factors in the stability of the haruan creams.
    Matched MeSH terms: Rheology
  13. Fulltext Study of Cationic and Nonionic Mixed Micelles with NaBr and 3,5-Cl2C6H3CO2Na by Use of Probe Nucleophilic Reaction of Piperidine with Ionized Phenyl Salicylate
    Fagge II, Khalid K, Noh MAM, Yusof NSM, Zain SM, Khan MN
    J Oleo Sci, 2018 Jan 01;67(1):55-66.
    PMID: 29238023 DOI: 10.5650/jos.ess17033
    Behaviors of cationic and nonionic mixed micelles in the form of hexadecyltrimethylammonium bromide (HDABr) and hexadecyltrimethylammonium bromide-Polyethylene glycol hexadecyl ether (C16E20), in the presence of inert salts (NaBr and 3,5-dichlorosodium benzoate), by the use of reaction probe between Pp and ionized PhSH (Pp = piperidine and PhSH = phenyl salicylate), has been reported in this work. The values of RXBr (RXBr denotes ion exchange constants obtained in the presence of micelles of different structural features) or KXBr (KXBr denotes ion exchange constants obtained in the presence of micelles of the same structural features) for 3,5-Cl2C6H3CO2- were almost the same at three different [HDABr]T (0.006, 0.010 and 0.015 M). The average value of RXBr or KXBr determined, in the presence of pure HDABr micelles, using semi empirical kinetic (SEK) method appeared to be almost 2½-fold larger (RXBr or KXBr = 198) than that in the presence of mixed HDABr-C16E20 micelles (RXBr or KXBr = 78). Rheological measurements indicated the existence of wormlike/twisted micelles and vesicle at 0.015 M pure HDABr, various [3,5-Cl2C6H3CO2Na], and 25 and 35℃ whereas there were evidence of only spherical micelles in the presence of mixed HDABr-C16E20 ([HDABr]T = 0.015 M and [C16E20]T = 0.006 M) at both temperatures.
    Matched MeSH terms: Rheology
  14. Development of biofilm-targeted antimicrobial wound dressing for the treatment of chronic wound infections
    Ng SF, Leow HL
    Drug Dev Ind Pharm, 2015;41(11):1902-9.
    PMID: 25758412 DOI: 10.3109/03639045.2015.1019888
    It has been established that microbial biofilms are largely responsible for the recalcitrance of many wound infections to conventional antibiotics. It was proposed that the efficacy of antibiotics could be optimized via the inhibition of bacterial biofilm growth in wounds. The combination of antibiofilm agent and antibiotics into a wound dressing may be a plausible strategy in wound infection management. Xylitol is an antibiofilm agent that has been shown to inhibit the biofilm formation. The purpose of this study was to develop an alginate film containing xylitol and gentamicin for the treatment of wound infection. Three films, i.e. blank alginate film (SA), alginate film with xylitol (F5) and alginate film with xylitol and gentamicin (AG), were prepared. The films were studied for their physical properties, swelling ratio, moisture absorption, moisture vapor transmission rate (MVTR), mechanical and rheology properties, drug content uniformity as well as in vitro drug release properties. Antimicrobial and antibiofilm in vitro studies on Staphylococcus aureus and Pseudomonas aeruginosa were also performed. The results showed that AG demonstrates superior mechanical properties, rheological properties and a higher MVTR compared with SA and F5. The drug flux of AG was higher than that of commercial gentamicin cream. Furthermore, antimicrobial studies showed that AG is effective against both S. aureus and P. aeruginosa, and the antibiofilm assays demonstrated that the combination was effective against biofilm bacteria. In summary, alginate films containing xylitol and gentamicin may potentially be used as new dressings for the treatment of wound infection.
    Matched MeSH terms: Rheology
  15. Fulltext Assessment of Polyacrylamide Based Co-Polymers Enhanced by Functional Group Modifications with Regards to Salinity and Hardness
    Akbari S, Mahmood SM, Tan IM, Ghaedi H, Ling OL
    Polymers (Basel), 2017 Nov 27;9(12).
    PMID: 30965947 DOI: 10.3390/polym9120647
    This research aims to test four new polymers for their stability under high salinity/high hardness conditions for their possible use in polymer flooding to improve oil recovery from hydrocarbon reservoirs. The four sulfonated based polyacrylamide co-polymers were FLOCOMB C7035; SUPERPUSHER SAV55; THERMOASSOCIATIF; and AN132 VHM which are basically sulfonated polyacrylamide copolymers of AM (acrylamide) with AMPS (2-Acrylamido-2-Methylpropane Sulfonate). AN132 VHM has a molecular weight of 9⁻11 million Daltons with 32 mol % degree of sulfonation. SUPERPUSHER SAV55 mainly has about 35 mol % sulfonation degree and a molecular weight of 9⁻11 million Daltons. FLOCOMB C7035, in addition, has undergone post-hydrolysis step to increase polydispersity and molecular weight above 18 million Daltons but it has a sulfonation degree much lower than 32 mol %. THERMOASSOCIATIF has a molecular weight lower than 12 million Daltons and a medium sulfonation degree of around 32 mol %, and also contains LCST (lower critical solution temperature) type block, which is responsible for its thermoassociative characteristics. This paper discusses the rheological behavior of these polymers in aqueous solutions (100⁻4500 ppm) with NaCl (0.1⁻10 wt %) measured at 25 °C. The effect of hardness was investigated by preparing a CaCl₂-NaCl solution of same ionic strength as the 5 wt % of NaCl. In summary, it can be concluded that the rheological behavior of the newly modified co-polymers was in general agreement to the existing polymers, except that THERMOASSOCIATIF polymers showed unique behavior, which could possibly make them a better candidate for enhanced oil recovery (EOR) application in high salinity conditions. The other three polymers, on the other hand, are better candidates for EOR applications in reservoirs containing high divalent ions. These results are expected to be helpful in selecting and screening the polymers for an EOR application.
    Matched MeSH terms: Rheology
  16. Pectin as a rheology modifier: Origin, structure, commercial production and rheology
    Chan SY, Choo WS, Young DJ, Loh XJ
    Carbohydr Polym, 2017 Apr 01;161:118-139.
    PMID: 28189220 DOI: 10.1016/j.carbpol.2016.12.033
    Pectins are a diverse family of biopolymers with an anionic polysaccharide backbone of α-1,4-linked d-galacturonic acids in common. They have been widely used as emulsifiers, gelling agents, glazing agents, stabilizers, and/or thickeners in food, pharmaceutical, personal care and polymer products. Commercial pectin is classified as high methoxy pectin (HMP) with a degree of methylation (DM) >50% and low methoxy pectin (LMP) with a DM <50%. Amidated low methoxy pectins (ALMP) can be obtained through aminolysis of HMP. Gelation of HMP occurs by cross-linking through hydrogen bonds and hydrophobic forces between the methyl groups, assisted by a high co-solute concentration and low pH. In contrast, gelation of LMP occurs by the formation of ionic linkages via calcium bridges between two carboxyl groups from two different chains in close proximity, known as the 'egg-box' model. Pectin gels exhibit Newtonian behaviour at low shear rates and shear-thinning behaviour when the shear rate is increased. An overview of pectin from its origin to its physicochemical properties is presented in this review.
    Matched MeSH terms: Rheology
  17. Effect of cream fermentation on microbiological, physicochemical and rheological properties of L. helveticus-butter
    Ewe JA, Loo SY
    Food Chem, 2016 Jun 15;201:29-36.
    PMID: 26868544 DOI: 10.1016/j.foodchem.2016.01.049
    The primary objective of this study was to evaluate the physicochemical and rheological properties of butter produced by Lactobacillus helveticus fermented cream. The incorporation of putative probiotic - the L. helveticus, to ferment cream prior to butter production was anticipated to alter the nutritional composition of butter. Changes in crude macronutrients and the resultant modification relating to textural properties of butter induced upon metabolic activities of L. helveticus in cream were focused in this research. Fermented butter (LH-butter) was produced by churning the cream that was fermented by lactobacilli at 37 °C for 24 h. Physicochemical analysis, proximate analysis and rheology properties of LH-butter were compared with butter produced using unfermented cream (control). LH-butter showed a significantly (P<0.05) higher fat content and acid value; lower moisture and ash; and was softer than the control. Cream fermentation modified nutritional and textural properties of butter in which LH-butter contained higher health beneficial unsaturated fatty acids than the control and thus rendered the product softer. Its enrichment with probiotics could thus further enhance its functional property.
    Matched MeSH terms: Rheology
  18. Experimental investigation of the flow of bile in patient specific cystic duct models
    Al-Atabi M, Chin SB, Luo XY
    J Biomech Eng, 2010 Apr;132(4):041003.
    PMID: 20387966 DOI: 10.1115/1.4001043
    Three-dimensional scaled-up transparent models of three human cystic ducts were prepared on the basis of anatomical specimens. The measurement of pressure drop across the cystic duct models and visualization of the flow structures within these ducts were performed at conditions replicating the physiological state. The flow visualization study confirmed the laminar nature of the flow of bile inside the cystic duct and values of pressure drop coefficient (Cp) decreased as the Reynolds number (Re) increased. The three tested models showed comparable behavior for the curve of Reynolds number versus the pressure drop coefficient. The results show that the tested cystic ducts have both increased pressure drop and complicated flow structures when compared with straight conduits. High resistance in a cystic duct may indicate that the gallbladder has to exert large force in expelling bile to the cystic duct. For patients with diseased gallbladder, and even in healthy persons, gallbladder is known to stiffen with age and it may lose its compliance or flexibility. A high resistance cystic duct coupled with a stiffened gallbladder may result in prolonged stasis of bile in the gallbladder, which is assumed to encourage the formation of gallstones.
    Matched MeSH terms: Rheology/methods
  19. Self-healing of poly(2-hydroxyethyl methacrylate) hydrogel through molecular diffusion
    Sirajuddin N, Md Jamil M
    Sains Malaysiana, 2015;44:811-818.
    Synthetic materials that are capable of healing upon damage are being developed at a rapid pace because of their
    many potential applications. Here, new healing chemically cross-linked hydrogel of poly(2-hydroxyethyl methacrylate)
    (pHEMA) was prepared. The healing hydrogel was achieved by heating above its glass transition (Tg
    ). The intermolecular
    diffusion of dangling chain and the chain slippage led to healing of the gel. The peaks in attenuated total reflectance
    (ATR) confirmed that hydrogel was formed while rheological studies had determined the minimum for healing temperature
    is 48.5o
    C. The results showed that ratio stress of the healable hydrogel can reach until 92 and 91% of first and second
    healing cycle, respectively. The morphology of the sample was carried out to evaluate the self-property of hydrogel.
    Matched MeSH terms: Rheology
  20. Porous alumina-hydroxyapatite composites through protein foaming-consolidation method
    Sopyan I, Fadli A, Mel M
    J Mech Behav Biomed Mater, 2012 Apr;8:86-98.
    PMID: 22402156 DOI: 10.1016/j.jmbbm.2011.10.012
    This report presents physical characterization and cell culture test of porous alumina-hydroxyapatite (HA) composites fabricated through protein foaming-consolidation technique. Alumina and HA powders were mixed with yolk and starch at an adjusted ratio to make slurry. The resulting slip was poured into cylindrical shaped molds and followed by foaming and consolidation via 180 °C drying for 1 h. The obtained green bodies were burned at 600 °C for 1 h, followed by sintering at temperatures of 1200-1550 °C for 2 h. Porous alumina-HA bodies with 26-77 vol.% shrinkage, 46%-52% porosity and 0.1-6.4 MPa compressive strength were obtained. The compressive strength of bodies increased with the increasing sintering temperatures. The addition of commercial HA in the body was found to increase the compressive strength, whereas the case is reverse for sol-gel derived HA. Biocompatibility study of porous alumina-HA was performed in a stirred tank bioreactor using culture of Vero cells. A good compatibility of the cells to the porous microcarriers was observed as the cells attached and grew at the surface of microcarriers at 8-120 cultured hours. The cell growth on porous alumina microcarrier was 0.015 h(-1) and increased to 0.019 h(-1) for 0.3 w/w HA-to-alumina mass ratio and decreased again to 0.017 h(-1) for 1.0 w/w ratio.
    Matched MeSH terms: Rheology
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links