Displaying publications 1 - 20 of 116 in total

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  1. Abdul Rahim Samsuddin, Abdul Ghani Rafek, Umar Hamzah, Suharsono, Khairul Anuar Mohd Nayan
    Analisis spektrum gelombang permukaan (SASW) adalah kaedah seismos yang menggunakan ciri serakan gelombang Rayleigh yang merambat pada lapisan bahan bagi memperolehi profil halaju gelombang ricih. Kaedah SASW merupakan satu kaedah insitu tanpa musnah untuk pencirian tapak geoteknik yang lebih kos efektif berbanding kaedah konvensyenal secara penggerudian. Dalam kajian ini sebanyak 20 stesen yang terdiri daripada 13 tapak kajian telah dipilih. Perisian (WINSASW 2.0) telah digunakan dalam proses penyongsangan untuk menghasilkan profil halaju gelombang ricih melawan kedalaman. Profil-profil ini kemudian dianalisis secara berasingan bagi memperolehi beberapa parameter geologi kejuruteraan jasad batuan seperti kekukuhan, nilai Penanda Mutu Batuan (RQD), anisotropi dan sifat kebolehkorekan. Analisis data SASW dijalankan dengan menganggap bahawa jasad batuan adalah homogen dan isotrop serta mengandungi pelbagai intensiti ketakselanjaran yang mempengaruhi perambatan halaju gelombang permukaan. Pengukuran sifat kedinamikan tanah dijalankan dengan menggunakan halaju gelombang ricih dan nilai ketukan N daripada Ujian Penusukan Piawai (NSPT) dalam lubang gerudi. Satu persamaan linear baharu, Vs = 4.44 NSPT + 213.84 yang mengaitkan halaju gelombang ricih dan NSPT telah diperolehi. Satu persamaan empirik telah dikemukakan bagi mengukur nilai Penanda Mutu Batuan (RQD) berasaskan halaju gelombang ricih yang diperolehi daripada kaedah SASW dan halaju daripada ujian ultrasonik. Persamaan ini memberikan hasil yang perbezaannya kurang daripada 10% berbanding data RQD daripada lubang gerudi. Analisis keanisotropan jasad batuan dijalankan menggunakan halaju gelombang ricih yang diperolehi berdasarkan kaedah SASW yang diukur dalam empat arah. Plot nisbah halaju gelombang ricih - halaju ultrasonik melawan halaju ultrasonik telah digunakan untuk menentukan sifat kebolehkorekan jasad batuan. Sebanyak lima kelas lengkungan kebolehkorekan jasad batuan telah dapat dikemukakan iaitu lengkungan Mudah korek, Mudah koyak, Susah koyak, Pemecah hidraulik dan Peletupan.
    Matched MeSH terms: Composite Resins
  2. Samsuzzaman M, Islam MT, Mandeep JS, Misran N
    ScientificWorldJournal, 2014;2014:804068.
    PMID: 24696661 DOI: 10.1155/2014/804068
    This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS.
    Matched MeSH terms: Composite Resins/economics; Composite Resins/chemistry*
  3. Chour RG, Moda A, Arora A, Arafath MY, Shetty VK, Rishal Y
    J Int Soc Prev Community Dent, 2016 Aug;6(Suppl 2):S166-70.
    PMID: 27652251 DOI: 10.4103/2231-0762.189761
    Satisfactory composite restoration depends upon its smooth finish, quality of polishing agents, type of composite material used, and its composition. The present study evaluated the effect of different polishing systems on the surface roughness of composite resin.
    Matched MeSH terms: Composite Resins
  4. Jamia Azdina Jamal, Azmira Akmal Sateri, Khairana Husain, Ibrahim Jantan, Mohd. Shahidan Mohamad Arshad
    MyJurnal
    The water decoction of Labisia pumila var. alata is used traditionally in childbirth, as well as for the treatment of flatulence, dysentery, dysmenorrhoea and join pains. This study was carried out to determine the best method and optimum parameters of aqueous axtraction of the leaves and roots of this species. The laboratory methos esed were maceration, ddecoction, reflux and Saxhlet, whereas the parameters studied were temperature, duration and pH of axtraction. The yields and thin layer chromatographic profiles of the freeze-dried extracts were analysed. The study showed that in general the percentage yields of the water soluble extracts were higher for the roots than the leaves, as well as the extracts obtained from heating than those obtained at room temperature. The most effective extraction parameters for L. pumila var. alata were as follows:maceration (25 C, at least 6 hr), decoction (60 C, not exceeding 10 min) and reflux (100 C, not exceeding 4 hr). Saxhlet method was found to be the least effective. The pH analysis had shown the possibility of degradation of some of the phytochemicals at extreme pH values of 1,2 and 14.
    Matched MeSH terms: Composite Resins
  5. Norbahiah Misran, Farizah Ansarudin, Mohammad Tariqul Islam
    Teknik reka bentuk untuk meningkatkan gandaan bagi menambah baik prestasi antena tompok mikrojalur konvensional dibincangkan. Kaedah suapan prob tersongsang jalur lebar bagi antena tompok mikrojalur berbilang lubang alur bertindan dicadangkan. Reka bentuk tersebut menggabungkan beberapa teknik kontemporari iaitu kaedah suapan prob, struktur tompok tersongsang dan tompok berbilang lubang alur bertindan. Kesan komposit daripada penyatuan pelbagai teknik ini dan dengan memperkenalkan bentuk elemen tompok yang baru, memberikan profil yang rendah, jalur lebar yang lebih luas, gandaan tinggi dan elemen antena yang padat. Keputusan menunjukkan peningkatan gandaan di mana gandaan maksimum adalah 11.42 dBi. Reka bentuk ini sesuai untuk aplikasi tata susunan terutama untuk stesen tapak.
    Matched MeSH terms: Composite Resins
  6. Suparta W, Baharudin Yatim, Mohd. Alauddin Mohd. Ali
    Kajian ini dijalankan untuk mencirikan kepelbagaian kelakuan cuaca dalam lapisan bawah dan atas atmosfera, terutama kebergantungannya kepada keadaan di dalam troposfera dan ionosfera pada enam stesen yang berbeza di UKM Bangi, Selangor. Pengukuran adalah berasaskan pemonitoran jangka pendek wap air bolehmendak (PWV) dalam troposfera dan jumlah kandungan elektron (TEC) dalam ionosfera menggunakan penerima GPS Bumi. Data PWV, TEC dan pengukuran meteorologi permukaan adalah dicerap bermula 12 November sehingga 7 Disember 2007. Hasil pemonitoran menunjukkan bahawa kedua-dua profil kebolehubahan PWV dan TEC memperlihatkan kitaran harian. Purata harian PWV dan TEC adalah tinggi, masing-masing dengan nilai ~42 mm dan ~35 TECU. Perubahan kedua-duanya didapati dipengaruhi aktiviti Matahari.
    Matched MeSH terms: Composite Resins
  7. Lim TW, Tan SK, Li KY, Burrow MF
    J Evid Based Dent Pract, 2023 Dec;23(4):101911.
    PMID: 38035903 DOI: 10.1016/j.jebdp.2023.101911
    OBJECTIVES: The aim of this systematic review was to evaluate the survival and complication rates of resin composite laminate veneers.

    METHODS: Randomized controlled trials and cohort studies with a minimum 2-year follow-up assessing survival and complication rates of resin composite laminate veneers on permanent dentition from 1998 to May 2022. Literature searches were conducted in MEDLINE (PubMed), Scopus, and the Cochrane Central Register of Controlled Trials electronic databases. References cited in the related reviews and included full-text articles were also hand-searched to further identify potentially relevant studies.

    RESULTS: A total of 827 articles were identified. Twenty-two studies were considered for full-text review after the title and abstract screening stage. After exclusion, 7 studies (3 randomized controlled trials and 4 cohort studies) were included in the systematic review. Three published scales were adopted for the quality and risk of bias assessment. At the survival rate threshold, the overall heterogeneity (I2) for randomized controlled trials was 50.5% (P = .108). The overall pooled survival rate of the randomized controlled trials was 88% (95% CI: 81%-94%), with the mean follow-up time ranging from 24 to 97 months. Surface roughness, color mismatch, and marginal discoloration were the most reported complications.

    CONCLUSION: Resin composite laminate veneers demonstrated moderately high survival rates for the entire sample and the direct laminate veneer group demonstrated higher survival rates than the indirect approach. Most of the complications were regarded as clinically acceptable with or without reintervention.

    Matched MeSH terms: Composite Resins*
  8. Mohd Shahminan Ibrahim, Wen, Yap Kai, Gonzalez, Maria Angela Garcia, Noor Azlin Yahya
    Ann Dent, 2020;27(1):41-49.
    MyJurnal
    This study compared the surface roughness of selected tooth coloured restorative materials that were polished according to manufacturers’ instructions and Sof-Lex. It also assessed the surface roughness of polished materials after thermocycling.Filtek Z350XT, Beautifil-Bulk Restorative and Cention N, were used in this study. A stainless steel mould (10mm diameter x 2mm height) was used to fabricate 75 cylindrical specimens: 15 Filtek Z350XT (FZ), 30 Beautifil-Bulk Restorative (BB) and 30 Cention N (CN). All 15 FZ specimens were polished with Sof-Lex. Fifteen BB and CN specimens were polished according to manufacturers’ instructions. The remaining fifteen BB and CN specimens were polished using Sof-Lex. All the specimens were subjected to thermocycling (1000 cycles). Surface roughness was assessed quantitatively with profilometry after specimen preparation (Mylar stage), polishingand thermocycling. Data were analysed using SPSS version 25.0 at α=0.05. When polished according to manufacturers’ instructions, BB had the lowest mean surface roughness (Ra) values (0.13±0.01μm) followed sequentially by CN (0.14±0.03μm) and FZ (0.15±0.02μm). The differences were not statistically significant. When polished with Sof-Lex, BB exhibited the smoothest surface (0.116±0.03μm) followed sequentially by and FZ (0.150±0.02μm) and CN (0.157±0.02μm). Thermocycling caused an increase in the Ra. The differences were statistically significant. All materials tested had Ra values below the threshold value of 0.2 μm at Mylar stage and after polishing with their recommended polishing system and Sof-Lex. Thermocycling produced rougher surfaces that did not exceed the threshold Ra value. Polishability was material dependent.
    Matched MeSH terms: Composite Resins
  9. Wan Zaimi W, Anuar Ishak
    Sains Malaysiana, 2012;41:1263-1270.
    Dalam makalah ini, masalah aliran genangan dalam bendalir mikrokutub terhadap permukaan mencancang yang telap dengan fluks haba boleh ubah dipertimbangkan. Dengan menggunakan penjelmaan keserupaan, persamaan asas yang menakluk aliran bendalir dan pemindahan haba dijelmakan kepada satu set persamaan perbezaan biasa. Persamaan yang dijelmakan tertakluk kepada syarat-syarat sempadan yang berkaitan kemudiannya diselesaikan secara berangka menggunakan kaedah tembakan. Kesan parameter sedutan/semburan fw ke atas profil halaju dan suhu serta pekali geseran kulit dan nombor Nusselt setempat diperoleh dan dibincangkan. Keputusan berangka menunjukkan bahawa penyelesaian dual wujud dalam kedua-dua aliran membantu dan aliran menentang.
    Matched MeSH terms: Composite Resins
  10. Mohd Zuki Salleh, Roslinda Nazar
    Penyelesaian berangka bagi masalah aliran lapisan sempadan olakan bebas mantap terhadap silinder bulat mengufuk yang dijanakan oleh pemanasan Newtonan, iaitu pemindahan haba dari permukaan berkadar langsung dengan suhu permukaan setempat, dipertimbangkan. Persamaan lapisan sempadan terjelma diselesaikan secara berangka dengan suatu skim berangka beza terhingga tersirat yang dikenali sebagai kaedah kotak Keller. Penyelesaian berangka diperoleh bagi pekali geseran kulit, pekali pemindahan haba setempat, suhu dinding serta profil halaju dan suhu. Ciri-ciri aliran dan pemindahan haba bagi suatu julat nilai nombor Prandtl yang besar dianalisis dan dibincangkan.
    Matched MeSH terms: Composite Resins
  11. Jogad N, Patil PG, Gade V, Patil S
    J Prosthet Dent, 2015 Sep;114(3):458-9.
    PMID: 26047801 DOI: 10.1016/j.prosdent.2015.04.005
    Matched MeSH terms: Composite Resins/economics*
  12. Talib R
    J Nihon Univ Sch Dent, 1993 Sep;35(3):161-70.
    PMID: 8246037
    Dental composite resins are widely used in dental practice and are continually being developed in order to obtain better products. To gain full benefit from these materials, it is important for the clinician to understand their properties. The following is a review of the more common characteristics of composites in current use.
    Matched MeSH terms: Composite Resins/chemistry*
  13. Yew HZ, Berekally TL, Richards LC
    Aust Dent J, 2013 Dec;58(4):468-77.
    PMID: 24320904 DOI: 10.1111/adj.12099
    The aim of this study was to evaluate colour stability upon exposure to spices of a nano-filled and a micro-hybrid resin composite finished either with Sof-Lex™ discs (SLD) or against plastic strips (PS).
    Matched MeSH terms: Composite Resins*
  14. May Z, Alam MK, Mahmud MS, Rahman NAA
    PLoS One, 2020;15(11):e0242022.
    PMID: 33186372 DOI: 10.1371/journal.pone.0242022
    Damage assessment is a key element in structural health monitoring of various industrial applications to understand well and predict the response of the material. The big uncertainty in carbon fiber composite materials response is because of variability in the initiation and propagation of damage. Developing advanced tools to design with composite materials, methods for characterizing several damage modes during operation are required. While there is a significant amount of work on the analysis of acoustic emission (AE) from different composite materials and many loading cases, this research focuses on applying an unsupervised clustering method for separating AE data into several groups with distinct evolution. In this paper, we develop an adaptive sampling and unsupervised bivariate data clustering techniques to characterize the several damage initiations of a composite structure in different lay-ups. An adaptive sampling technique pre-processes the AE features and eliminates redundant AE data samples. The reduction of unnecessary AE data depends on the requirements of the proposed bivariate data clustering technique. The bivariate data clustering technique groups the AE data (dependent variable) with respect to the mechanical data (independent variable) to assess the damage of the composite structure. Tensile experiments on carbon fiber reinforced composite laminates (CFRP) in different orientations are carried out to collect mechanical and AE data and demonstrate the damage modes. Based on the mechanical stress-strain data, the results show the dominant damage regions in different lay-ups of specimens and the definition of the different states of damage. In addition, the states of the damage are observed using Scanning Electron Microscope (SEM) analysis. Based on the AE data, the results show that the strong linear correlation between AE and mechanical energy, and the classification of various modes of damage in all lay-ups of specimens forming clusters of AE energy with respect to the mechanical energy. Furthermore, the validation of the cluster-based characterization and improvement of the sensitivity of the damage modes classification are observed by the combined knowledge of AE and mechanical energy and time-frequency spectrum analysis.
    Matched MeSH terms: Composite Resins/chemistry*
  15. Ang Y, Tan CG, Yahaya N
    Dent Mater J, 2021 May 29;40(3):584-591.
    PMID: 33328396 DOI: 10.4012/dmj.2020-213
    This study aimed to investigate the effect of various framework designs on the failure of posterior fiber reinforced composite (FRC) bridges and assess the post crack performances of the repaired prostheses. Thirty samples were prepared into three different groups of framework designs: cuspal support (CS), anatomic features (AF) and circular reinforcement (CR). All specimens were subjected to static loading test and acoustic emission analysis. Significant differences were found in the load and time of initial failures among the three groups (p<0.001). CS was identified as the optimum framework design. Samples with composite delamination at the pontic site were selected and repaired with a clinically simplified protocol. Significant differences were also observed between the repaired and original FRC bridges (p=0.01). The performance of these prostheses was highly dependent on the framework design and the perspective of repairing FRC bridges may warrant future investigations.
    Matched MeSH terms: Composite Resins*
  16. 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: Composite Resins*
  17. Abd Wahab MH, Bakar WZ, Husein A
    J Conserv Dent, 2011 Oct;14(4):387-90.
    PMID: 22144809 DOI: 10.4103/0972-0707.87207
    Porcelain from prosthesis such as crown or bridge can be fractured if exposed to trauma; and, can be repaired at chairside using composite resin.
    Matched MeSH terms: Composite Resins
  18. Wong KJ, Johar M, Koloor SSR, Petrů M, Tamin MN
    Polymers (Basel), 2020 Sep 22;12(9).
    PMID: 32971855 DOI: 10.3390/polym12092162
    It is necessary to consider the influence of moisture damage on the interlaminar fracture toughness for composite structures that are used for outdoor applications. However, the studies on the progressive variation of the fracture toughness as a function of moisture content M (%) is rather limited. In this regard, this study focuses on the characterization of mode II delamination of carbon/epoxy composites conditioned at 70 °C/85% relative humidity (RH). End-notched flexure test is conducted for specimens aged at various moisture absorption levels. Experimental results reveal that mode II fracture toughness degrades with the moisture content, with a maximum of 23% decrement. A residual property model is used to predict the variation of the fracture toughness with the moisture content. Through numerical simulations, it is found that the approaches used to estimate the lamina and cohesive properties are suitable to obtain reliable simulation results. In addition, the damage initiation is noticed during the early loading stage; however, the complete damage is only observed when the numerical peak load is achieved. Results from the present research could serve as guidelines to predict the residual properties and simulate the mode II delamination behavior under moisture attack.
    Matched MeSH terms: Composite Resins
  19. Yin, Ping W., L., C-Khai, Hamidah, A., Nur Maya Sabrina, T., Muaatamarulain, M., Geok, Chin T.
    Medicine & Health, 2020;15(2):124-139.
    MyJurnal
    Empat subkumpulan molekul teras medulloblastoma yang mempunyai profil transkripsi dan nilai prognostik yang berbeza diperkenalkan baru-baru ini. Kajian ini bertujuan untuk menentukan varian histologi dan subkumpulan molekul medulloblastoma melalui aplikasi imunohistokimia (YAP-1 dan beta catenin) sebagai penanda surrogate di populasi kami, di samping menghubungkan varian histologi dan subkumpulan molekul ini dengan parameter klinikopatologi. Kami telah melibatkan seramai tujuh belas pesakit medulloblastoma yang berusia empat bulan hingga 14.3 tahun dari tahun 2002 hingga 2017. Histologi klasik (76.5%) adalah histologi medulloblastoma yang paling umum, diikuti oleh varian sel besar/ anaplastik (LCA) (17.6%) dan desmoplastik/nodular (DN) (59%). Subkumpulan molekul yang paling kerap adalah tumor bukan SHH/WNT (64.7%), diikuti oleh tumor SHH (35.3%). Di antara tumor SHH, 66.7% adalah histologi klasik dan selebihnya 33.3% adalah varian LCA. Yang menariknya, satu kes yang menunjukkan histologi DN memaparkan imunonegativiti kepada YAP-1 dan beta catenin, dan tergolong kepada subkumpulan molekul bukan SHH/WNT. Majoriti (88.2%) medulloblastoma berada di lokasi pertengahan ventrikel keempat, termasuk varian DN. Dianggarkan tiga tahun kelangsungan hidup bebas penyakit (DFS) dan survival keseluruhan (OS) masing-masing adalah 60% dan 86.7%. Umur 5 cm, histologi LCA dan kumpulan berisiko tinggi adalah berkorelasi terbalik dengan DFS. Bayi
    Matched MeSH terms: Composite Resins
  20. 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: Composite Resins
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