Displaying publications 41 - 60 of 378 in total

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  1. Fulltext AN INVESTIGATION OF KENAF PLANT FIBRES AS REINFORCEMENTS IN INTERWOVEN KENAF/POLYETHYLENE TEREPHTHALATE (PET)/EPOXY HYBRID GREEN COMPOSITES
    NURUL AIMI NADIA IBRAHIM, MOHAMAD AWANG, SURIANI MAT JUSOH
    UMT Journal of Undergraduate Research, 2020;2(2):23-32.
    MyJurnal
    Renewable materials have some bearing on the environment and have since increased research works related to polymer composites. This work was conducted to investigate the effects of interwoven kenaf fibres and the use of kenaf fibres in composites. In this research, interwoven between kenaf and polyethylene terephthalate (PET) was prepared and epoxy was used as the polymer matrix to form composites. The kenaf fibre composites with various kenaf fibre contents (2, 5, 8, and 10 wt %) interwoven with (PET) fibres were prepared by using open mould method. The properties of kenaf/PET/epoxy composites (KPTE) were studied. The kenaf fibre composites characterization was determined based on their mechanical properties, water absorption, morphology and thermal properties. The tensile strength test was performed using Testometric machine. The finding shows that the strength increases as the amount of kenaf fibres in the composites increases. The composites with 10% kenaf fibres interwoven PET displayed the highest tensile strength (85.3 ± 2.9 MPa) while unfilled epoxy show the lowest tensile strength (64.1 ± 16.5 MPa). The addition of kenaf fibres minimally increases the water absorption up to about 1.4%. The increases of kenaf fibres also reduces the overall thermal stability of the composites compared to the PET and epoxy resin composites. The morphology properties of KPTE composites support the tensile properties surface of the composites. This study assists to propose the kenaf fibres as a potential filler for properties improvements in epoxy-based composites contributing to the development of another environment-friendly material.
    Matched MeSH terms: Surface Properties
  2. Evaluation of the color stability of temporary materials produced with CAD/CAM
    Kul E, Abdulrahim R, Bayındır F, Matori KA, Gül P
    Dent Med Probl, 2021 5 14;58(2):187-191.
    PMID: 33982454 DOI: 10.17219/dmp/126745
    BACKGROUND: If a temporary restoration is in the esthetic area and needs to be worn for a long time, the color stability of temporary materials becomes an important factor.

    OBJECTIVES: The aim of this in vitro study was to evaluate the long-term effects of various staining solutions on the color stability of different temporary materials produced with the computer-aided design and computer-aided manufacturing (CAD/CAM) technology.

    MATERIAL AND METHODS: In the study, the following materials were used: VITA CAD-Temp® (group 1); Ceramill® Temp (group 2); and Telio® CAD (group 3). Forty disk-shaped specimens (10 mm in diameter, 2 mm in thickness) of each material (N = 120) were produced with a CAD/CAM system. Staining solutions - of tea (A), of coffee (B) and cola (C) - and distilled water (D, control) were used, and color was evaluated before and after storing the samples in the solutions. Measurements were taken with a spectrophotometer and the color parameters (L*, a*, b*, and ΔE) were calculated according to the Commission internationale de l'éclairage system (CIELab). The results were evaluated with the two-way analysis of variance (ANOVA) and Tukey's tests (α = 0.05).

    RESULTS: Clinically perceivable (ΔE00 > 0.8) and statistically significant (p < 0.001) color differences were detected in all specimens. The highest ΔE00 value was found in the Ceramill Temp specimens. In addition, the highest ΔE00 values were noted for the specimens stored in cola and the coffee solution for all groups. The lowest ΔE00 value was observed for the groups stored in the tea solution.

    CONCLUSIONS: Clinically perceivable color changes were observed in all the specimens kept in the solutions. Color changes were greater for cola and coffee as compared to tea.

    Matched MeSH terms: Surface Properties
  3. Fulltext Observation of cotton-like bismuth oxide (β-Bi2O2.5) prepared via pulsed laser ablation deposition
    Waje, Samaila Bawa, Noorhana Yahya, Irmawati Ramli
    Pertanika Journal of Science & Technology, 2009;17(2):-.
    MyJurnal
    Monoclinic bismuth oxide (α-Bi2O3) nanoparticles were prepared via precipitation method and
    irradiated with a pulsed laser forming thin films. Their phase and surface morphological properties
    were investigated using x-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron
    microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM). The XRD
    analysis shows the phase transformation to a partially crystalline tetragonal phase β-Bi2O3 thin film.
    The SEM micrograph of the nanoparticles, with an average crystal size of 72 nm, was seen to form
    a thin film with a peculiar structure, coined as “cotton-like”, is attributed to the high surface energy
    absorbed by the nanoparticles during ablation. The HR-TEM micrograph shows the particulate with
    a clearly defined interlayer spacing.
    Matched MeSH terms: Surface Properties
  4. Fulltext Effects of process temperature and time on the properties of microwave plasma nitrided Ti-6Al-4V alloy
    Yusuf, Y., Juoi, J.M., Rosli, Z.M., Kwan, W.L., Mahamud, Z.
    Pertanika Journal of Science & Technology, 2013;21(1):45-58.
    MyJurnal
    Titanium alloy (e.g. Ti-6Al-4V) has an excellent combination of properties. However in many cases,
    the application is limited because of the poor wear property. In this work, a surface modification
    (plasma nitriding) is carried out to improve the surface properties of Ti-6Al-4V, as a treatment prior to a hardcoating deposition, leading to a duplex coating system. This is an effort to improve the surface and near surface property of Ti-6Al-4V. Plasma nitriding is performed utilizing microwave plasma method in 25% Ar- 75% N2 atmosphere at temperatures of 600°C and 700°C for different processing times (1, 3 and 5 hours). The phase and microstructure of plasma nitrided substrate were characterized by using X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The plasma nitrided Ti-6Al-4V properties (surface roughness, surface hardness and case depth) were determined using profilometer and microhardness, respectively. Results obtained showed a significant increase on the surface hardness of Ti-6Al-4V. This is due to the formation of TiN and Ti2N phases in the form of compound layer. Besides, it shows that the diffusion of nitrogen into the Ti-6Al-4V substrate produces case depth up to 130 µm and this contributes to the improvement of the near surface hardness due to the changes in the microstructures. It was also found that the surface hardness and surface roughness increased with the increases in the process temperature and times.
    Matched MeSH terms: Surface Properties
  5. Fulltext Effects of soil burial on properties of linear density polyethylene (LDPE)/ thermoplastic sago starch (TPSS) blends
    Hanafi Ismail, Rohani Abdul Majid, Razaina Mat Taib
    Pertanika Journal of Science & Technology, 2011;19(1):189-197.
    MyJurnal
    Linear density polyethylene (LDPE)/thermoplastic sago starch (TPSS), blended with and without the addition of compatibilizer [Polyethylene-grafted-Maleic Anhydride, (PE-g-MA)] were prepared for soil burial test. The test was conducted in the natural soil environment for 3 and 6 months. Different loading of TPSS (10, 20, 30, 40, and 50 wt. %) were used in this study. After soil burial, the blends were evaluated for their tensile properties and scanning electron microscopy (SEM) to observe the surface morphology properties after the test. For LDPE/TPSS, it was observed that the tensile strength decreased with the increase of soil burial time, as well as Young modulus and elongation at break (EB). The LDPE/TPSS/PE-g-MA also showed the same trend for the tensile properties, but with higher properties as compared to uncompatibilized blends. The tensile properties also decreased with the increase in the TPSS loading for both the LDPE/TPSS and LDPE/TPSS/PE-g-MA. Meanwhile,
    the scanning electron microscopy (SEM) on the blend surfaces after the soil burial test showed that degradability increased with the increase in the exposure time as well as the TPSS loading.
    Matched MeSH terms: Surface Properties
  6. Corrosion and surface modification on biocompatible metals: A review
    Asri RIM, Harun WSW, Samykano M, Lah NAC, Ghani SAC, Tarlochan F, et al.
    Mater Sci Eng C Mater Biol Appl, 2017 Aug 01;77:1261-1274.
    PMID: 28532004 DOI: 10.1016/j.msec.2017.04.102
    Corrosion prevention in biomaterials has become crucial particularly to overcome inflammation and allergic reactions caused by the biomaterials' implants towards the human body. When these metal implants contacted with fluidic environments such as bloodstream and tissue of the body, most of them became mutually highly antagonistic and subsequently promotes corrosion. Biocompatible implants are typically made up of metallic, ceramic, composite and polymers. The present paper specifically focuses on biocompatible metals which favorably used as implants such as 316L stainless steel, cobalt-chromium-molybdenum, pure titanium and titanium-based alloys. This article also takes a close look at the effect of corrosion towards the implant and human body and the mechanism to improve it. Due to this corrosion delinquent, several surface modification techniques have been used to improve the corrosion behavior of biocompatible metals such as deposition of the coating, development of passivation oxide layer and ion beam surface modification. Apart from that, surface texturing methods such as plasma spraying, chemical etching, blasting, electropolishing, and laser treatment which used to improve corrosion behavior are also discussed in detail. Introduction of surface modifications to biocompatible metals is considered as a "best solution" so far to enhanced corrosion resistance performance; besides achieving superior biocompatibility and promoting osseointegration of biocompatible metals and alloys.
    Matched MeSH terms: Surface Properties
  7. Fulltext Review of titanate coupling agents and their application for dental composite fabrication
    Elshereksi NW, Ghazali M, Muchtar A, Azhari CH
    Dent Mater J, 2017 Sep 26;36(5):539-552.
    PMID: 28652551 DOI: 10.4012/dmj.2016-014
    Silane is a dominant coupler that is widely used in dentistry to promote adhesion among the components of dental composites. Silica-based fillers can be easily silanized because of their similarly ordered structure. However, silane is hydrolytically degraded in the aqueous oral environment and inefficiently bonds to non-silica fillers. Thus, the development of hydrolytically stable dental composites is an important objective in the research on dental materials. Titanate coupling agents (TCAs) exhibit satisfactory interfacial bonding, enhanced homogeneous filler dispersion, and improved mechanical properties of the composites. Titanates also provide superior hydrolytic stability in wet environments, which should be considered in fabricating dental composites. The addition of a small amount of titanates can improve the resistance of the composites to moisture. This paper reviews the effects of the instability of silanes in moisture on the performance of dental composites and presents TCAs as alternative couplers to silanes for fabricating dental composites.
    Matched MeSH terms: Surface Properties
  8. Enhancing the biocompatibility of the polyurethane methacrylate and off-stoichiometry thiol-ene polymers by argon and nitrogen plasma treatment
    Chen TF, Siow KS, Ng PY, Majlis BY
    Mater Sci Eng C Mater Biol Appl, 2017 Oct 01;79:613-621.
    PMID: 28629060 DOI: 10.1016/j.msec.2017.05.091
    Our studies focused on improving the biocompatibility properties of two microfluidic prototyping substrates i.e. polyurethane methacrylate (PUMA) and off-stoichiometry thiol-ene (OSTE-80) polymer by Ar and N2plasma treatment. The contact angle (CA) measurement showed that both plasma treatments inserted oxygen and nitrogen moieties increased the surface energy and hydrophilicity of PUMA and OSTE-80 polymer which corresponded to an increase of nitrogen to carbon ratios (N/C), as measured by XPS, to provide a conducive environment for cell attachments and proliferation. Under the SEM observation, the surface topography of PUMA and OSTE-80 polymer showed minimal changes after the plasma treatments. Furthermore, ageing studies showed that plasma-treated PUMA and OSTE-80 polymer had stable hydrophilicity and nitrogen composition during storage in ambient air for 15days. After in vitro cell culture of human umbilical vein endothelial cells (HUVECs) on these surfaces for 24h and 72h, both trypan blue and alamar blue assays indicated that PUMA and OSTE-80 polymer treated with N2plasma had the highest viability and proliferation. The polar nitrogen moieties, specifically amide groups, encouraged the HUVECs adhesion on the plasma-treated PUMA and OSTE-80 surfaces. Interestingly, PUMA polymer treated with Ar and N2plasma showed different HUVECs morphology which was spindle and cobblestone-shaped respectively after 72h of incubation. On the contrary, a monolayer of well-spread HUVECs formed on the Ar and N2plasma-treated OSTE-80 polymers. These variable morphologies observed can be ascribed to the adherence HUVECs on the different elastic moduli of these surfaces whereby further investigation might be needed. Overall, Ar and N2plasma treatment had successfully altered the surface properties of PUMA and OSTE-80 polymer by increasing its surface energy, hydrophilicity and chemical functionalities to create a biocompatible surface for HUVECs adhesion and proliferation.
    Matched MeSH terms: Surface Properties
  9. Isolation and characterization of microcrystalline cellulose from roselle fibers
    Kian LK, Jawaid M, Ariffin H, Alothman OY
    Int J Biol Macromol, 2017 Oct;103:931-940.
    PMID: 28549863 DOI: 10.1016/j.ijbiomac.2017.05.135
    In this study, microcrystalline cellulose (MCC) was extracted from roselle fiber through acid hydrolysis treatment and its properties were compared with those of commercially available MCC. The physicochemical and morphological characteristics, elemental composition, size distribution, crystallinity and thermal properties of the obtained MCC were analyzed in this work. Fourier transform infrared spectroscopy (FTIR) analysis provided clear evidence that the characteristic peak of lignin was absent in the spectrum of the MCC prepared from roselle fiber. Rough surface and slight aggregation of MCC were observed by scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) analysis showed that pure MCC with small quantities of residues and impurities was obtained, with a similar elemental composition to that of commercial MCC. A mean diameter of approximately 44.28μm was measured for MCC by using a particle size analyzer (PSA). X-ray diffraction (XRD) showed the crystallinity increased from 63% in roselle pulp to 78% in roselle MCC, the latter having a slightly higher crystallinity than that of commercial MCC (74%). TGA and DSC results indicated that the roselle MCC had better thermal stability than the roselle pulp, whereas it had poorer thermal stability in comparison with commercial MCC. Thus, the isolated MCC from roselle fibers will be going to use as reinforcing element in green composites and may be a precursor for future roselle derived nanocellulose, and thus a promising subject in nanocomposite research.
    Matched MeSH terms: Surface Properties
  10. Functionalized glycolipids for potential bioconjugation of vesicles
    Tabandeh M, Goh EW, Salman AA, Heidelberg T, Duali Hussen RS
    Carbohydr Res, 2018 Nov;469:14-22.
    PMID: 30196011 DOI: 10.1016/j.carres.2018.08.016
    Two azide-terminated oligoethylene oxide spacered glycolipids have been synthesized, and their assembly behavior has been studied in comparison to the corresponding base surfactants. The results suggest potential of the Guerbet lactoside-based compound for targeted drug delivery, while a coiling of the ethylene oxide linker disfavors the application of the glucoside.
    Matched MeSH terms: Surface Properties
  11. Atomic force microscopy as a tool for asymmetric polymeric membrane characterization
    Abdul Wahab Mohammad, Lim YP, Indok Nurul Hasyimah Mohd Amin, Rafeqah Raslan, Hilal N
    Sains Malaysiana, 2011;40.
    Atomic force microscopy (AFM) has a wide range of applications and is rapidly growing in research and development. This powerful technique has been used to visualize surfaces both in liquid or gas media. It has been considered as an effective tool to investigate the surface structure for its ability to generate high-resolution 3D images at a subnanometer range without sample pretreatment. In this paper, the use of AFM to characterize the membrane roughness is presented for commercial and self-prepared membranes for specific applications. Surface roughness has been regarded as one of the most important surface properties, and has significant effect in membrane permeability and fouling behaviour. Several scan areas were used to compare surface roughness for different membrane samples. Characterization of the surfaces was achieved by measuring the average roughness (Ra) and root mean square roughness (Rrms) of the membrane. AFM image shows that the membrane surface was composed entirely of peaks and valleys. Surface roughness is substantially greater for commercial available hydrophobic membranes, in contrast to self-prepared membranes. This study also shows that foulants deposited on membrane surface would increase the membrane roughness.
    Matched MeSH terms: Surface Properties
  12. Investigation of indentation size effect and R-curve behaviour of Li2O-SiO2 and Li2O-2SiO2 glass ceramics
    Alao AR, Mohd Azhari MA
    J Mech Behav Biomed Mater, 2021 12;124:104842.
    PMID: 34555624 DOI: 10.1016/j.jmbbm.2021.104842
    Indentation size effect (ISE) and R-curve behaviour of Li2O-SiO2 and Li2O-2SiO2 glass ceramics are investigated using micro-indentation and indentation-strength (IS) techniques, respectively. Vickers micro-indentations were applied on both materials at the load of 0.10-19.6 N to determine the load influence on the measured hardness. For the IS-measured fracture toughness, the load ranged from 1.96 to 19.6 N. The hardness decreased with increasing load by 20% and 18% on Li2O-SiO2 and Li2O-2SiO2 glass ceramics, respectively, indicating the ISE behaviour on both materials. The fracture toughness increased with the load by 27% and 59% on Li2O-SiO2 and Li2O-2SiO2 glass ceramics, respectively, signifying the R-curve behaviour. The ISE behaviour of both materials was analysed using the Meyer's, Hays-Kendall (HK), proportional specimen resistance (PSR), Nix-Gao (NG), modified PSR (MPSR) and elastic plastic deformation (EPD) models while the R-curve behaviour was analysed by the fractional power law. The Meyer's index of both materials was less than 2, strongly confirming the ISE existence. The HK, PSR and NG models were only suitable to determine intrinsic Vickers hardness for Li2O-2SiO2 glass ceramic while the MPSR and EPD models were successful for both materials. The fractional power law gave higher R-curve steepness for Li2O-2SiO2 than Li2O-SiO2 glass ceramics. Also, material and brittleness indices predicted, respectively, higher quasi-plasticity and better machinability for Li2O-2SiO2 than Li2O-SiO2 glass ceramics indicating superior performance in the former to the latter. Finally, this study presents a new significant insight into the micro-mechanisms of fracture tolerance behaviour of these glass ceramics which is critical to their functional performance as structural ceramics.
    Matched MeSH terms: Surface Properties
  13. Omnidirectional Shape Memory Effect via Lyophilization of PEG Hydrogels
    Chen D, Xia X, Wong TW, Bai H, Behl M, Zhao Q, et al.
    Macromol Rapid Commun, 2017 Apr;38(7).
    PMID: 28196300 DOI: 10.1002/marc.201600746
    Device applications of shape memory polymers demand diverse shape changing geometries, which are currently limited to non-omnidirectional movement. This restriction originates from traditional thermomechanical programming methods such as uniaxial, biaxial stretching, bending, or compression. A solvent-modulated programming method is reported to achieve an omnidirectional shape memory behavior. The method utilizes freeze drying of hydrogels of polyethylene glycol networks with a melting transition temperature around 50 °C in their dry state. Such a process creates temporarily fixed macroporosity, which collapses upon heating, leading to significant omnidirectional shrinkage. These shrunken materials can swell in water to form hydrogels again and the omnidirectional programming and recovery can be repeated. The fixity ratio (R f ) and recovery ratio (R r ) can be maintained at 90% and 98% respectively upon shape memory multicycling. The maximum linear recoverable strain, as limited by the maximum swelling, is ≈90%. Amongst various application potentials, one can envision the fabrication of multiphase composites by taking advantages of the omnidirectional shrinkage from a porous polymer to a denser structure.
    Matched MeSH terms: Surface Properties
  14. Effects of aqueous humor hydrodynamics on human eye heat transfer under external heat sources
    Tiang KL, Ooi EH
    Med Eng Phys, 2016 Aug;38(8):776-84.
    PMID: 27340100 DOI: 10.1016/j.medengphy.2016.05.011
    The majority of the eye models developed in the late 90s and early 00s considers only heat conduction inside the eye. This assumption is not entirely correct, since the anterior and posterior chambers are filled aqueous humor (AH) that is constantly in motion due to thermally-induced buoyancy. In this paper, a three-dimensional model of the human eye is developed to investigate the effects AH hydrodynamics have on the human eye temperature under exposure to external heat sources. If the effects of AH flow are negligible, then future models can be developed without taking them into account, thus simplifying the modeling process. Two types of external thermal loads are considered; volumetric and surface irradiation. Results showed that heat convection due to AH flow contributes to nearly 95% of the total heat flow inside the anterior chamber. Moreover, the circulation inside the anterior chamber can cause an upward shift of the location of hotspot. This can have significant consequences to our understanding of heat-induced cataractogenesis.
    Matched MeSH terms: Surface Properties
  15. Catalytic microwave pyrolysis of oil palm fiber (OPF) for the biochar production
    Hossain MA, Ganesan PB, Sandaran SC, Rozali SB, Krishnasamy S
    Environ Sci Pollut Res Int, 2017 Dec;24(34):26521-26533.
    PMID: 28948458 DOI: 10.1007/s11356-017-0241-6
    Microwave pyrolysis of oil palm fiber (OPF) with three types of Na-based catalysts was experimentally investigated to produce biochar. Sodium hydroxide (NaOH), sodium chloride (NaCl), and sodium carbonate (Na2CO3) with purity 99.9% were selected for this investigation. Microwave muffle reactor (Model: HAMiab-C1500) with a microwave power controller including a microwave generator was used to perform the microwave pyrolysis. OPF particles were used after removing foreign materials, impurities, and dust. Microwave power ranges from 400 to 900 W, temperature ranges from 450 to 700 °C, and N2 flow rates ranges from 200 to -1200 cm3/min were used along with all three Na-based catalysts for this investigation. Lower microwave power, temperature, and N2 flow rate have been found favorable for higher yield of biochar. NaOH is to be found as the more suitable catalyst than NaCl and Na2CO3 to produce biochar. A maximum biochar yield (51.42 wt%) has been found by using the catalysts NaOH at N2 flow rate of 200 cm3/min. One sample of the biochar (maximum yield without catalysts) was selected for further characterization via thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), BET surface area, Fourier transform infrared spectroscopy (FTIR), and ultimate and proximate analysis. SEM and BET surface area analysis showed the presence of some pores in the biochar. High percentage of carbon (60.24 wt%) was also recorded in the sample biochar. The pores and high percentage of carbon of biochar have significant impact on soil fertilization by increasing the carbon sequestration in the soil. It assists to slow down the decomposition rate of nutrients from soil and therefore enhances the soil quality.
    Matched MeSH terms: Surface Properties
  16. Fulltext Surface profile analysis of laminated transfemoral prosthetic socket fabricated with different ratios of epoxy resin and acrylic resin
    Zainuddin NAMN, Razak NAA, Karim MSA, Osman NAA
    Sci Rep, 2023 Feb 15;13(1):2664.
    PMID: 36792914 DOI: 10.1038/s41598-022-21990-y
    Acrylic and epoxy are common types of resin used in fabricating sockets. Different types of resin will affect the internal surface of a laminated socket. This paper is to determine the best combination of ratio for epoxy and acrylic resin for a laminated prosthesis socket and to evaluate the surface profile analysis of different combinations of laminated prosthetic sockets for surface roughness. Transfemoral sockets were created using various resin-to-hardener ratios of 2:1, 3:1, 3:2, 2:3, and 1:3 for epoxy resin and 100:1, 100:2, 100:3, 100:4, and 100:5 for acrylic resin. Eight layers of stockinette consisting of four elastic stockinette and four Perlon stockinette were used. A sample with a size of 4 cm × 6 cm was cut out from the socket on the lateral side below the Greater Trochanter area. The Mitutoyo Sj-210 Surface Tester stylus was run through the sample and gave the Average Surface Roughness value (Ra), Root Mean Square Roughness value (Rq), and Ten-Point Mean Roughness value (Rz). Epoxy resin shows a smoother surface compared to acrylic resin with Ra values of is 0.766 µm, 0.9716 µm, 0.9847 µm and 1.5461 µm with 3:2, 3:1, 2:1 and 2:3 ratio respectively. However, for epoxy resin with ratio 1:3, the resin does not cure with the hardener. As for acrylic resin the Ra values are 1.0086 µm, 2.362 µm, 3.372 µm, 4.762 µm and 6.074 µm with 100: 1, 100:2, 100:5, 100:4 and 100:3 ratios, respectively. Epoxy resin is a better choice in fabricating a laminated socket considering the surface produced is smoother.
    Matched MeSH terms: Surface Properties
  17. 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: Surface Properties
  18. Fulltext Polyelectrolytes ability in reducing atrazine concentration in water: surface effects
    Mohd Amin MF, Heijman SG, Lopes SI, Rietveld LC
    ScientificWorldJournal, 2014;2014:162157.
    PMID: 25197693 DOI: 10.1155/2014/162157
    This paper reports on the direct ability of two positively charged organic polyelectrolytes (natural-based and synthetic) to reduce the atrazine concentration in water. The adsorption study was set up using multiple glass vessels with different polymer dosing levels followed by ultrafiltration with a 1 kDa membrane. The addition of polymers exhibited a capability in reducing the atrazine concentration up to a maximum of 60% in surface-to-volume ratio experiments. In the beginning, the theoretical L-type of the isotherm of Giles' classification was expected with an increase in the dosage of the polymer. However, in this study, the conventional type of isotherm was not observed. It was found that the adsorption of the cationic polymer on the negatively charged glass surface was necessary and influential for the removal of atrazine. Surface-to-volume ratio adsorption experiments were performed to elucidate the mechanisms and the polymer configuration. The glass surface area was determined to be a limiting parameter in the adsorption mechanism.
    Matched MeSH terms: Surface Properties*
  19. Fulltext Effect of multipath laser shock processing on microhardness, surface roughness, and wear resistance of 2024-T3 Al alloy
    Kadhim A, Salim ET, Fayadh SM, Al-Amiery AA, Kadhum AA, Mohamad AB
    ScientificWorldJournal, 2014;2014:490951.
    PMID: 24737973 DOI: 10.1155/2014/490951
    Laser shock processing (LSP) is an innovative surface treatment technique with high peak power, short pulse, and cold hardening for strengthening metal materials. LSP is based on the application of a high intensity pulsed laser beam (I > 1 GW/cm(2); t < 50 ns) at the interface between the metallic target and the surrounding medium (a transparent confining material, normally water) forcing a sudden vaporization of the metallic surface into a high temperature and density plasma that immediately develops inducing a shock wave propagating into the material. The shock wave induces plastic deformation and a residual stress distribution in the target material. In this paper we study the increase of microhardness and surface roughness with the increase of laser pulse energy in 2024-T3 Al alloy. The influence of the thickness of the confining layer (water) on microhardness and surface roughness is also studied. In addition, the effect of LSP treatment with best conditions on wear behaviors of the alloy was investigated.
    Matched MeSH terms: Surface Properties/radiation effects
  20. Scanning electron microscopic assessment on surface morphology of preserved human amniotic membrane after gamma sterilisation
    Ab Hamid SS, Zahari NK, Yusof N, Hassan A
    Cell Tissue Bank, 2014 Mar;15(1):15-24.
    PMID: 23187886 DOI: 10.1007/s10561-012-9353-x
    Human amniotic membrane that has been processed and sterilised by gamma irradiation is widely used as a biological dressing in surgical applications. The morphological structure of human amniotic membrane was studied under scanning electron microscopy (SEM) to assess effects of gamma radiation on human amniotic membrane following different preservation methods. The amniotic membrane was preserved by either air drying or submerged in glycerol before gamma irradiated at 15, 25 and 35 kGy. Fresh human amniotic membrane, neither preserved nor irradiated was used as the control. The surface morphology of glycerol preserved amnion was found comparable to the fresh amniotic membrane. The cells of the glycerol preserved was beautifully arranged, homogonous in size and tended to round up. The cell structure in the air dried preserved amnion seemed to be flattened and dehydrated. The effects of dehydration on intercellular channels and the microvilli on the cell surface were clearly seen at higher magnifications (10,000×). SEM revealed that the changes of the cell morphology of the glycerol preserved amnion were visible at 35 kGy while the air dried already changed at 25 kGy. Glycerol preservation method is recommended for human amniotic membrane as the cell morphological structure is maintained and radiation doses lower than 25 kGy for sterilization did not affect the appearance of the preserved amnion.
    Matched MeSH terms: Surface Properties/radiation effects
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