Displaying publications 81 - 100 of 176 in total

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  1. Fulltext Effects of resin cements on hardness and thickness around titanium post: an intraradicular assessment
    Lim, Siau Peng, Fazal Reza, Zaihan Ariffin
    Archives of Orofacial Sciences, 2011;6(2):1-10.
    MyJurnal
    The purpose of this study was to evaluate hardness (indicator for polymerization) and thickness of two types of resin cement at coronal, middle and apical level of tooth root canal. Ten extracted maxillary incisors were instrumented and post space was prepared for cementation of titanium post. Samples were divided into two groups and each group was cemented either of the two types of resin cements; Panavia F [dual-cured (PF)] and Rely X Luting 2 [self-cured (RL)]. The teeth were longitudinally sectioned; hardness and thickness was measured using Vickers hardness tester and a microscope (Leica DMLM). SEM observations along the cement line at the 3 different root levels were performed. Statistical analysis was performed to test significance of differences in hardness and thickness of the two types of cement (t-test; p= 0.05) and at different levels of the same type (one-way ANOVA followed by multiple comparison; p= 0.05). Significant difference of hardness was found at the apical level between the two groups and between the coronal and apical level of PF (p0.05). Moreover, voids were more obvious within the dual-cured group of cement. Dual-cured resin cement was found to be less polymerized than self-cured type at apical level. Increased thicknesses of resin cements in comparison to post space size were observed in both groups. Use of metallic post with resin cements needs further evaluation.
    Matched MeSH terms: Hardness
  2. The existence of butterfly effect and its impact on the dentinal microhardness and crack formation after root canal instrumentation
    Lin GSS, Ghani NRNA, Noorani TY
    Odontology, 2021 Jul;109(3):672-678.
    PMID: 33458795 DOI: 10.1007/s10266-021-00589-1
    To compare the microhardness and crack formation in root dentine presented with butterfly effect in lower premolars. Sixty mature lower premolars were selected and divided into the control and experimental groups. Teeth in the experimental group were instrumented up to size 30/.04. The roots were cut horizontally into twelve parts of 1-mm-thick cross-section and were numbered accordingly. They were divided into coronal, middle, and apical root sections. Sections were then viewed under a microscope to determine the presence of butterfly effect and subsequently scored. 8 teeth from both control and experimental groups with the highest and lowest score were selected. Crack formation was inspected and classified into four different types of cracks. Microhardness test was performed using a Vickers hardness test. Higher frequency of butterfly effect was found in the apical root section and root dentine with butterfly effect were harder mesiodistally. The middle and apical root sections with butterfly effect were harder than the coronal section. No significant difference of dentine hardness between the control and experimental groups. Cracks only occurred in the experimental group and presented in buccolingual direction with a higher rate of Type 1 and Type 2 cracks. Prevalence of butterfly effect in lower premolars increased from coronal to apical with increased hardness mesiodistally. More buccolingual cracks were found in radicular dentine with butterfly effect and most of them exhibited Type 1 and Type 2 cracks. Roots of lower premolar with butterfly effect may be susceptible to a higher rate of vertical root fracture in buccolingual direction, especially after root canal treatment. Thus, special attention should be given not to overload instruments during root canal preparation.
    Matched MeSH terms: Hardness; Hardness Tests
  3. Fulltext New Experimental Zirconia-Reinforced Rice Husk Nanohybrid Composite and the Outcome of Its Surface Roughness and Microhardness in Comparison with Commercialized Nanofilled and Microhybrid Composite Resins
    Lin GSS, Ghani NRNA, Ismail NH, Singbal K, Noorani TY, Mamat N
    Contemp Clin Dent, 2021 03 20;12(1):21-27.
    PMID: 33967533 DOI: 10.4103/ccd.ccd_298_20
    Background: An ideal composite resin should demonstrate smooth surface after polishing and high hardness value to provide long-term success. Thus, this study aimed to compare the surface roughness and microhardness of new experimental zirconia-reinforced rice husk nanohybrid composite (Zr-Hybrid) with commercialized nanofilled (Filtek-Z350-XT) and microhybrid composite (Zmack-Comp) resins before and after artificial ageing.

    Methods: One hundred and eighty standardized disc samples were prepared, of which ninety samples each were used for surface roughness and microhardness test, respectively. They were divided equally into: Group 1 (Filtek-Z350-XT), Group 2 (Zmack-Comp), and Group 3 (Zr-Hybrid). For surface roughness test, all samples were polished with aluminium oxide discs and further subdivided into aged and unaged subgroups, in which composite samples in aged subgroups were subjected to 2500 thermal cycles. Next, all the samples were subjected to surface roughness test using a contact stylus profilometer. As for microhardness test, all the aged and unaged samples were tested using a Vickers hardness machine with a load of 300 kgf for 10 s and viewed under a digital microscope to obtain microhardness value. Data were analyzed using two-way ANOVA followed by post hoc Tukey's honestly significant difference and paired sample t-test with significance level set at P = 0.05.

    Results: In both the aged and unaged groups, Zr-Hybrid showed statistically significantly lower surface roughness (P < 0.05) than Filtek-Z350-XT and Zmack-Comp, but no statistically significant difference was noted between Filtek-Z350-XT and Zmack-Comp (P > 0.05). A similar pattern was noted in microhardness test, whereby Zr-Hybrid showed the highest value (P < 0.05) followed by Filtek-Z350-XT and lastly Zmack-Comp. Besides, significant differences in surface roughness and microhardness were noted between the aged and unaged groups.

    Conclusion: Zr-Hybrid seems to demonstrate better surface roughness and microhardness value before and after artificial ageing.

    Matched MeSH terms: Hardness
  4. Mechanical properties of Bitumen Quenched dual phase steel
    M.O.H. Amuda, T.A. Olaniyan, L.O. Osoba, E.T. Akinlabi
    Sains Malaysiana, 2017;46:743-753.
    The mechanical properties of Dual Phase Steel (DPS)-duplex structure-produced by quenching in pre-heated bitumen have been investigated. Medium carbon steels intercritically heated at different temperatures and holding times were quenched in hot bitumen. Optical and scanning electron microscopy characterisation of the duplex structure showed extensive network of fibrous martensite in a ferritic matrix with occasional presence of polygonal martensite. The duplex phase structure exhibited continuous yielding dynamics, improving the tensile and hardness values by about 42 and 35%, respectively, relative to the normalised structure. But, the elongation and impact values decreased by about 42 and 50%, respectively, when compared to the normalised structure. These values are similar to those obtained in duplex structure produced using conventional oil quenching. The tensile fractured surface showed transition between a predominantly cleavage mode in the lower annealing temperature to a mixed mode in the upper bound of the annealing temperature. These findings suggest that pre-heated bitumen can be exploited for the production of DPSs.
    Matched MeSH terms: Hardness
  5. Comparison of Disintegrant-addition Methods on the Compounding of Orodispersible Tablets
    Mahesparan VA, Bin Abd Razak FS, Ming LC, Uddin AH, Sarker MZI, Bin LK
    Int J Pharm Compd, 2020 3 21;24(2):148-155.
    PMID: 32196477
    Orodispersible tablets disintegrate rapidly (within 3 minutes) in the oral cavity and release the medicament before swallowing. The mode of disintegrant addition might affect the properties of orodispersible tablets. The objective of this study was to formulate and evaluate orodispersible tablets by studying different modes of disintegration addition with varying concentrations of disintegrants. The wet granulation method was used to produce the orodispersible tablets. Two methods of disintegration addition were compared (i.e., intragranular, extragranular). Three disintegrants (i.e., cornstarch, sodium starch glycolate, crospovidone) were used at three levels (5%, 10%, and 15%) in the study. The formulations were tested for the powder flowability (angle of repose) and characterized physically (hardness, weight, thickness, friability, disintegration time). The mangosteen pericarp extract was used as a model active pharmaceutical ingredient to be incorporated into the optimum formulation. It was observed that the extragranular method produced granules with better flowability compared to that of the intragranular method. Crospovidone was found as the most efficient disintegrant among the three. The optimum formulation selected was one with the highest concentration of crospovidone (15%), which showed the fastest disintegration time. The mode of disintegrant addition into the orodispersible tablets formulation was found to show a marked difference in the disintegration, as well as other physical characteristics of the orodispersible tablets where the extragranular mode of addition showed better property, which caused the orodispersible tablets to disintegrate the fastest.
    Matched MeSH terms: Hardness
  6. Fulltext Comparative evaluation of application of different fluoride varnishes on artificial early enamel lesion: An in vitro study
    Majithia U, Venkataraghavan K, Choudhary P, Trivedi K, Shah S, Virda M
    Indian J Dent Res, 2016 Sep-Oct;27(5):521-527.
    PMID: 27966511 DOI: 10.4103/0970-9290.195642
    INTRODUCTION: In an attempt to manage noncavitated carious lesions noninvasively through remineralization, a range of novel fluoride varnishes with additional remineralizing agents have been made available for clinical application.

    AIM AND OBJECTIVES: The aim of this study was to compare and evaluate the remineralization potential of three commercially available varnishes on artificial enamel lesions.

    MATERIALS AND METHODS: This in vitro study involves eighty intact enamel specimens prepared from premolars extracted for orthodontic purposes. After specimen preparation, the eighty samples were divided randomly into two groups (n = 40) for measurement of baseline surface Vickers microhardness and baseline calcium/phosphorus ratio (% weight) through EDAX testing. Thereafter, the specimens were subjected to demineralization for 96 h to induce initial enamel lesions and the measurements were repeated. Following demineralization, each of the two groups was divided randomly into four subgroups (n = 10) from which one was used as the control group and the others three were allotted to each of the three test varnishes. After varnish application, all the specimens were subjected to a pH cycling regimen that included alternative demineralization (3 h) and remineralization (21 h) daily, for 5 consecutive days. The Vickers microhardness and EDAX measurements were then repeated.

    RESULTS: One-way ANOVA and post hoc Tukey's tests were conducted for multiple group comparison. All the three commercially available varnishes were capable of remineralizing initial enamel lesions that were induced artificially. No difference was noted in the remineralizing efficacy of the varnishes despite their different compositions. MI Varnish™ (casein phosphopeptide-amorphous calcium phosphate fluoride varnish) showed slightly better recovery in surface microhardness as compared to the other two varnishes.

    CONCLUSION: All the varnishes used in this in vitro study are capable of reversing early enamel lesions.
    Matched MeSH terms: Hardness/drug effects
  7. Physical properties and microstructure of butter cake added with Persea americana Puree
    Marina AM, Nurhanan AR, Wan Rosli WI, Nurul Ain O
    Sains Malaysiana, 2016;45:1105-1111.
    The effect of addition of avocado (Persea americana) puree on the physical and microstructure of butter cake was studied.
    Butter cakes were made by replacing butter with 10, 30 and 50% of avocado puree. Physical properties including batter
    specific gravity, volume, colour and image analysis of cellular structure of the crumb were analyzed. Texture profile
    analysis was determined using texture analyzer. The results showed that with the increased amount of avocado puree,
    the batter specific gravity increased while volume of the cakes reduced. The texture profile analysis showed that the cakes
    became harder as the amount of avocado puree increased, while cohesiveness was not affected. The cellular structure of
    the crumb exhibited a decrease in the number of air cells while the average cell size increased with addition of avocado
    puree. The colour analysis showed that the cake crumb became darker as the aavocado puree was increased.
    Matched MeSH terms: Hardness
  8. Some mechanical properties of a highly cross-linked, microwave-polymerized, injection-molded denture base polymer
    Memon MS, Yunus N, Razak AA
    Int J Prosthodont, 2001 May-Jun;14(3):214-8.
    PMID: 11484567
    PURPOSE: The impact strength and the flexural properties of denture base materials are of importance in predicting their clinical performance upon sudden loading. This study compares the impact and transverse strengths and the flexural modulus of three denture base polymers.
    MATERIALS AND METHODS: The investigation included a relatively new microwave-polymerized polyurethane-based denture material processed by an injection-molding technique, a conventional microwave-polymerized denture material, and a heat-polymerized compression-molded poly(methyl methacrylate) (PMMA) denture material. Impact strength was determined using a Charpy-type impact tester. The transverse strength and the flexural modulus were assessed with a three-point bending test. The results were subjected to statistical analysis using a one-way analysis of variance and the Scheffé test for comparison.
    RESULTS: The impact strength of the microwave-polymerized injection-molded polymer was 6.3 kl/m2, while its flexural strength was 66.2 MPa. These values were lower than those shown by the two compression-molded PMMA-based polymers. The differences were statistically significant. The flexural modulus of the new denture material was 2,832 MPa, which was higher than the conventional heat-polymerized polymer but was comparable to the other microwave-polymerized PMMA-based polymer. The difference in the flexural modulus was statistically significant.
    CONCLUSION: In terms of the impact and flexural strengths, the new microwave-polymerized, injection-molded, polyurethane-based polymer offered no advantage over the existing heat- and microwave-polymerized PMMA-based denture base polymers. However, it has a rigidity comparable to that of the microwave-polymerized PMMA polymer.
    Matched MeSH terms: Hardness
  9. Fulltext A comparison of staining resistant of two composite resins
    Mior Azrizal M. Ibrahim, Wan Zaripah Wan Bakar, Adam Husein
    Archives of Orofacial Sciences, 2009;4(1):13-16.
    MyJurnal
    Composite resins Amaris is claimed to have hydrophobic effect which minimizes the staining intake. This study is to investigate the colour stability of Amaris compared to Filtek Z250 in coffee solution. Sixty discs of composite resins Filtek Z250 (3M ESPE) and Amaris (Voco) with diameter of 5mm and depth of 2mm were fabricated by packing in a drinking straw and sectioned with hard tissue cutter (Exakt, Japan). The surfaces of the specimens were polished with Sof-Lex disc before each group of the samples is immersed in coffee solution. They were kept in the solution for 4 days at 370C and assessed at the period of 2 hours, 1 day, 2 days, 3 days, and 4 days. The staining was assessed visually and recorded using Lobene (1968) Stain Index and score was given accordingly. The colour changes of both groups were not statistically significant (p
    Matched MeSH terms: Hardness
  10. Fulltext Application of various mechanical treatments for meat tenderization
    Mohamad Afifi Ismail, Gun Hean Chon, Mohammad Rashedi Ismail-Fitry
    Journal of Advanced Research Design, 2018;45(1):43-51.
    MyJurnal
    Meat tenderness is an important quality attribute that influences consumer acceptance. The application of mechanical treatment by mean to reduce toughness of meat cuts has gained much interest recently, with an intention to make use the lower grade meat cuts. This review deliberates the function, mechanism and numerous types of mechanical work in meat tenderization. The mechanical work employs to make meat softer by loosening the muscle structure and disrupting muscle cell. Previous studies have thoroughly examined the use of mechanical treatment (such as massaging, tumbling, and grinding) as an effective meat tenderization technique. Besides that, current research on newly emerging processing technology such as highpressure process (HPP) also shows potential to be explored. The application of mechanical work has shown impressive outcomes by reducing the shear force value that represents hardness of meat. The present paper also described the physical, biochemical and the structural changes of the meat. Finally, the improvements in the meat tenderness by using various type of mechanical work are presented in this paper.
    Matched MeSH terms: Hardness
  11. Fulltext Semisolid metal processing techniques for nondendritic feedstock production
    Mohammed MN, Omar MZ, Salleh MS, Alhawari KS, Kapranos P
    ScientificWorldJournal, 2013;2013:752175.
    PMID: 24194689 DOI: 10.1155/2013/752175
    Semisolid metal (SSM) processing or thixoforming is widely known as a technology that involves the formation of metal alloys between solidus and liquidus temperatures. For the procedure to operate successfully, the microstructure of the starting material must consist of solid near-globular grains surrounded by a liquid matrix and a wide solidus-to-liquidus transition area. Currently, this process is industrially successful, generating a variety of products with high quality parts in various industrial sectors. Throughout the years since its inception, a number of technologies to produce the appropriate globular microstructure have been developed and applied worldwide. The main aim of this paper is to classify the presently available SSM technologies and present a comprehensive review of the potential mechanisms that lead to microstructural alterations during the preparation of feedstock materials for SSM processing.
    Matched MeSH terms: Hardness
  12. Fulltext 3D Printing of UV-Curable Polyurethane Incorporated with Surface-Grafted Nanocellulose
    Mohan D, Sajab MS, Kaco H, Bakarudin SB, Noor AM
    Nanomaterials (Basel), 2019 Dec 03;9(12).
    PMID: 31817002 DOI: 10.3390/nano9121726
    The recognition of nanocellulose has been prominent in recent years as prospect materials, yet the ineffectiveness of nanocellulose to disperse in an organic solvent has restricted its utilization, especially as a reinforcement in polymer nanocomposite. In this study, cellulose has been isolated and defibrillated as cellulose nanofibrils (CNF) from oil palm empty fruit bunch (EFB) fibers. Subsequently, to enhance its compatibility with UV-curable polyurethane (PU)-based resin, the surface hydrophilicity of CNF has been tailored with polyethylene glycol (PEG), as well as reduced graphene oxide (rGO). The dispersibility of reinforced modified CNF in UV-curable PU was examined through the transmittance interruption of resin, chemical, and mechanical properties of the composite printed using the stereolithographic technique. Evidently, the enhanced compatibility of modified CNF and UV-curable PU was shown to improve the tensile strength and hardness of the composites by 37% and 129%, respectively.
    Matched MeSH terms: Hardness
  13. Fulltext Effects of two cycle heat treatment on the microstructure and hardness of Ductile Iron
    Mohd Faizul Idham, Bulan Abdullah, Khalissah Muhammad Yusof
    Pertanika Journal of Science & Technology, 2017;25(103):99-106.
    MyJurnal
    Austempering is one of the trendiest heat treatment processes to promote the strength and toughness of ductile iron. However, such practice is complex because it involves using aqueous solutions as quenchant (salt bath solution). This study was conducted to analyse the heat treatment of the combination processes of annealing-austenitising and evaluate the correlation between microstructure constituent and hardness of the ductile iron. Ductile iron samples in form of double cylinder was produced by conventional CO2 sand casting method. The new heat treatment process was started by annealed at 873 K for 1.8 ks before being oil quenched. Subsequently, the samples were austenitised at austenitising temperatures 1123 K, 1173 K and 1223 K for 3.6 ks respectively before being immediately oil quenched to room temperature. A series of microstructure analysis tests, including optical microscopy and X-ray diffraction (XRD) was applied. Vickers microhardness tester was used to measure the hardness for each microstructure constituent. The results showed that ductile iron matrix transforms to martensitic during heat treatment of annealing-austenitising combination processes, which in turn contributes to increasing microhardness of martensite and the bulk hardness of ductile iron.
    Matched MeSH terms: Hardness
  14. Bioactivity and mechanical stability of Ti-6Al-4V implants superplastically embedded with hydroxyapatite in rats
    Mohd Khalid H, Jauhari I, Mohamad Wali HA, Abdulrazzaq Mahmod S
    Biomed Mater, 2017 01 25;12(1):015019.
    PMID: 28120816 DOI: 10.1088/1748-605X/aa4f8b
    In this in vivo study, Sprague Dawley (SD) rats were used to investigate the bioactivity as well as the microstructural and mechanical properties of Ti-6Al-4V samples embedded with hydroxyapatite (HA) using two different coating methods-superplastic embedment (SPE) and superplastic deformation (SPD). The HA layer thickness for the SPE and SPD samples increased from 249.1  ±  0.6 nm to 874.8  ±  13.7 nm, and from 206.1  ±  5.8 nm to 1162.7  ±  7.9 nm respectively, after 12 weeks of implantation. The SPD sample exhibited much faster growth of newly formed HA compared to SPE. The growth of the newly formed HA was strongly dependent on the degree of HA crystallinity in the initial HA layer. After 12 weeks of implantation, the surface hardness value of the SPE and SPD samples decreased from 661  ±  0.4 HV to 586  ±  1.3 HV and from 585  ±  6.6 HV to 425  ±  86.9 HV respectively. The decrease in surface hardness values was due to the newly formed HA layer that was more porous than the initial HA layer. However, the values were still higher than the substrate surface hardness of 321  ±  28.8 HV. Wear test results suggest that the original HA layers for both samples were still strongly intact, and to a certain extent the newly grown HA layers also were strongly bound with the original HA layers. This study confirms the bioactivity and mechanical stability of the HA layer on both samples in vivo.
    Matched MeSH terms: Hardness Tests
  15. Fulltext The influence of sulphuric acid concentration on hard anodising process on powder metallurgy Al-Mg
    Mohd Nazree Derman, Mohd Nasuha Abd Halim, Shaiful Rizam Shamsudin
    Journal of Nuclear and Related Technologies, 2009;2009(1):224-229.
    MyJurnal
    The hardcoat anodising process was done by using different concentration of H2SO4 from 0% to 20%. The 90 volt of anodising process was applied by using Al foil as cathode materials. The surface changes on PM Al-Mg resulted by hardcoat anodising was characterised by XRD measured. Surface hardness was measured by Micro-Vickers hardness machine. The experiment found different XRD pattern between anodised PM Al-Mg samples. The study was found by that the optimum value for H2SO4 concentration was 15 % H2SO4 and result 26 μm thickness, 5.07% of mass changes and HVN 105.4 hardness. The hardcoat anodising was affected to the XRD pattern for PM Al-Mg.
    Matched MeSH terms: Hardness
  16. Effect of grain size and grain content on the hardness and drillability of rock
    Mou Y, Yingfeng-Meng, Gao L, Lin H, Yufei-Li
    Sains Malaysiana, 2014;43:81-87.
    It is well-known that the characteristics of hardness and drillability are influenced by microstructure of rock. In this study, rock properties were analyzed on grain size and grain content. Coarse-grain and fine-grain sandstones were tested under successive indentation condition. Eighteen groups of sandstone and shale were employed for the drillability test. Indentation tests results showed that grain size influenced the low point of residual hardness, the crushing depth and volume and grain content influenced the peak point of hardness. The drillability values of shale increased with increasing contents of clay and quartz. Meanwhile, drillability values of sandstone increased with increasing content of quartz, but decreased with increasing content of clay. Therefore, these preliminary studies show great potential applications for selecting suitable bit type and formulating drilling program as a function of rock microstructure and crushing rock method for bit in the oil drilling.
    Matched MeSH terms: Hardness
  17. Influence of Weather on Hardness and Surface Roughness of Maxillofacial Elastomeric Materials
    Mousa MA
    J Contemp Dent Pract, 2020 Jun 01;21(6):678-682.
    PMID: 33025938
    AIMS: The purpose of this study was to assess the influence of hot and dry weather on the hardness and surface roughness of four different maxillofacial silicone elastomeric materials (MFSEM) including two room-temperature vulcanized (RTV) and two high-temperature vulcanized (HTV) materials.

    MATERIALS AND METHODS: Eighty test specimens were fabricated according to the manufacturer's instructions into rectangular test specimens. The hardness and surface roughness were tested, after 6 months of exposure to natural hot and dry weather. The hardness was measured through the International Rubber Hardness Degree (IRHD) scale using an automated hardness tester. The surface roughness was measured using a novel 3D optical noncontact technique using a combination of a light sectioning microscope and a computer vision system. Statistical Package for Social Sciences software SPSS/version 24 was used for analysis and a comparison between two independent variables was done using an independent t test, while more than two variables were analyzed, F test (ANOVA) to be used followed by a post hoc test to determine the level of significance between every two groups.

    RESULTS: The hot and dry weather statistically influenced the hardness and surface roughness of MFSEM. Cosmesil M-511 showed the least hardness in test groups while A-2000 showed the hardest material (p < 0.05). A-2000 showed significant changes from rough in case of nonweathered to become smoother in weather followed by A-2186 (p < 0.05). Cosmesil M-511 showed the roughest material.

    CONCLUSION: Cosmesil M-511 showed the least hard MFSEM after outdoor weathering while A-2000, the highest and least material showed hardness and surface roughness, respectively.

    CLINICAL IMPLICATION: A-2000 had a high IRHD scale hardness. This makes this material more suitable for the replacement of ear and nose defects. Cosmesil M-511 is soft and easily adaptable material that makes the material more appropriate for the replacement of small facial defect with undercut area to be easily inserted and removed. Whilst A-2000 is smoother and finer in test specimens after weathering, Cosmesil M-511 became rougher after weathering.

    Matched MeSH terms: Hardness
  18. Fulltext Comparative Study of Aromatic and Cycloaliphatic Isocyanate Effects on Physico-Chemical Properties of Bio-Based Polyurethane Acrylate Coatings
    Mudri NH, Abdullah LC, Aung MM, Salleh MZ, Awang Biak DR, Rayung M
    Polymers (Basel), 2020 Jul 03;12(7).
    PMID: 32635384 DOI: 10.3390/polym12071494
    Crude jatropha oil (JO) was modified to form jatropha oil-based polyol (JOL) via two steps in a chemical reaction known as epoxidation and hydroxylation. JOL was then reacted with isocyanates to produce JO-based polyurethane resin. In this study, two types of isocyanates, 2,4-toluene diisocyanate (2,4-TDI) and isophorone diisocyanate (IPDI) were introduced to produce JPUA-TDI and JPUA-IPDI respectively. 2,4-TDI is categorised as an aromatic isocyanate whilst IPDI is known as a cycloaliphatic isocyanate. Both JPUA-TDI and JPUA-IPDI were then end-capped by the acrylate functional group of 2-hydroxyethyl methacrylate (HEMA). The effects of that isocyanate structure were investigated for their physico, chemical and thermal properties. The changes of the functional groups during each synthesis step were monitored by FTIR analysis. The appearance of urethane peaks was observed at 1532 cm-1, 1718 cm-1 and 3369 cm-1 while acrylate peaks were detected at 815 cm-1 and 1663 cm-1 indicating that JPUA was successfully synthesised. It was found that the molar mass of JPUA-TDI was doubled compared to JPUA-IPDI. Each resin showed a similar degradation pattern analysed by thermal gravimetric analysis (TGA). For the mechanical properties, the JPUA-IPDI-based coating formulation exhibited a higher hardness value but poor adhesion compared to the JPUA-TDI-based coating formulation. Both types of jatropha-based polyurethane acrylate may potentially be used in an ultraviolet (UV) curing system specifically for clear coat surface applications to replace dependency on petroleum-based chemicals.
    Matched MeSH terms: Hardness
  19. Fulltext Degradation effects of dietary solvents on microhardness and inorganic elements of computer-aided design/computer-aided manufacturing dental composites
    Munusamy SM, Helen-Ng LC, Farook MS
    BMC Oral Health, 2024 Feb 01;24(1):162.
    PMID: 38302972 DOI: 10.1186/s12903-024-03905-7
    BACKGROUND: Computer-aided design/computer-aided manufacturing (CAD/CAM) dental composites were introduced with superior mechanical properties than conventional dental composites. However, little is known on effects of dietary solvents on microhardness or inorganic elemental composition of CAD/CAM composites.

    OBJECTIVES: The objectives of this study were to evaluate the degradation effects of each dietary solvent on the microhardness of the different CAD/CAM dental composites and to observe the degradation effects of dietary solvent on the inorganic elements of the dental composites investigated.

    METHODS: Fifty specimens with dimensions 12 mm x 14 mm x 1.5 mm were prepared for direct composite (Filtek Z350 XT [FZ]), indirect composite (Shofu Ceramage [CM]), and three CAD/CAM composites (Lava Ultimate [LU], Cerasmart [CS], and Vita Enamic [VE]). The specimens were randomly divided into 5 groups (n = 10) and conditioned for 1-week at 37°C in the following: air (control), distilled water, 0.02 N citric acid, 0.02 N lactic acid and 50% ethanol-water solution. Subsequently, the specimens were subjected to microhardness test (KHN) using Knoop hardness indenter. Air (control) and representative postconditioning specimens with the lowest mean KHN value for each material were analyzed using energy dispersive X-ray spectroscopy (EDX). Statistical analysis was done using one-way ANOVA and post hoc Bonferroni test at a significance level of p = 0.05.

    RESULTS: Mean KHN values ranged from 39.7 ± 2.7 kg/mm2 for FZ conditioned in 50% ethanol-water solution to 79.2 ± 3.4 kg/mm2 for VE conditioned in air (control). With exception to LU, significant differences were observed between materials and dietary solvents for other dental composites investigated. EDX showed stable peaks of the inorganic elements between air (control) and representative postconditioning specimens.

    CONCLUSIONS: The microhardness of dental composites was significantly affected by dietary solvents, except for one CAD/CAM composite [LU]. However, no changes were observed in the inorganic elemental composition of dental composites between air (control) and 1-week postconditioning.

    Matched MeSH terms: Hardness
  20. The effects of tapioca, wheat, sago and potato flours on the physicochemical and sensory properties of duck sausage
    Muthia, D., Nurul, H., Noryati, I.
    International Food Research Journal, 2010;17(4):877-884.
    MyJurnal
    This study evaluated the effects of different flours (tapioca, wheat, sago and potato) on the physicochemical properties of duck sausage. The examined physicochemical properties included proximate composition, cooking yield, color (lightness, redness and yellowness), folding, texture profile (hardness, elasticity, cohesiveness, gumminess and chewiness) and sensory properties. The study found that different flours have no effect on the cooking yield of duck sausage. The tapioca formulation showed a mid-range lightness value, folding score and textural properties. Duck sausages made with wheat flour had higher protein content and lightness value and a harder texture. Sausages made with potato flour had a darker color, the lowest folding scores and a softer texture. The addition of sago flour resulted in a higher folding score, greater elasticity and increased overall acceptability of sausage due to higher scores for texture and juiciness. These results show that the properties of duck sausage are influenced by the type of flour used.
    Matched MeSH terms: Hardness
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