Influence of light-exposure methods and depths of cavity on the microhardness of dual-cured core build-up resin composites

Objective: The purpose of this study was to evaluate the Knoop hardness number (KHN) of dual-cured core build-up resin composites (DCBRCs) at 6 depths of cavity after 3 post-irradiation times by 4 light-exposure methods. Material and Methods: Five specimens each of DCBRCs (Clearfil DC Core Plus [DCP] and Unifil Core EM [UCE]) were filled in acrylic resin blocks with a semi-cylindrical cavity and light-cured using an LED light unit (power density: 1,000 mW/cm2)at the top surface by irradiation for 20 seconds (20 s), 40 seconds (40 s), bonding agent plus 20 seconds (B+20 s), or 40 seconds plus light irradiation of both sides of each acrylic resin block for 40 seconds each (120 s). KHN was measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours, 24 hours, and 7 days post-irradiation. Statistical analysis was performed using repeated measures ANOVA and Tukey's compromise post-hoc test with a significance level of

Mutational and biochemical analysis of Lactobacillus reuteri glucansucrase enzymes

α-Glucaan homopolysachariden worden door glucansucrase enzymen van melkzuurbacteriën gesynthetiseerd uit sucrose, en gebruikt als biologisch verdikkingsmiddel in de voedingsmiddelenindustrie, als bloedplasmavervanger in medische toepassingen, en als scheidingsmatrix in wetenschappelijk onderzoek. Echter, de α-glucanen geproduceerd door glucansucrasen zijn ook belangrijke pathogene factoren in tandbederf. Met behulp van specifieke remmers van glucansucrase enzymen zou tandbederf wellicht kunnen worden bestreden. In dit proefschrift hebben we het glucansucrase polysacharide syntheseproces in meer detail bestudeerd door de structuren van de initieel door het GTFA enzym van Lactobacillus reuteri 121 uit sucrose gevormde oligosachariden te karakteriseren. Uit deze gedetailleerde structuuranalyse bleek dat GTFA vooral lineaire oligosachariden synthetiseerde door verlenging van sucrose met een keten van glucose residuen met alternerende (α1→4) en (α1→6) bindingen. In dit PhD project werd een semi-rationele mutagenese benadering toegepast voor de modificatie van het glucansucrase GTF180 enzym, mogelijk gemaakt door de recentelijk opgehelderde kristalstructuur van het enzym. Dit stelde ons in staat om de essentiële gebieden voor bindingstype specificiteit en reactie specificiteit in het glucansucraseeiwit te identificeren. Verschillende residuen van domein B (L938, L940 en A978) en residuen van domein A (D1028, N1029, D1085, R1088 en N1089) bleken belangrijk te zijn voor bindingstype specificiteit. Residuen A978, D1028, D1085 en R1088 bleken betrokken te zijn bij de vorming van vertakkingen. Residuen N1029 en L981 zijn essentieel voor de transglycosyleringsreactie. De verkregen resultaten verschaffen nieuwe inzichten in de structuur-functie relaties van glucansucrase GTF180, met name in zijn bindingstype specificiteit, reactie specificiteit en enzymactiviteit

Joint Power Splitting and Secure Beamforming Design in the Wireless-powered Untrusted Relay Networks

In this work, we maximize the secrecy rate of the wireless-powered untrusted relay network by jointly designing power splitting (PS) ratio and relay beamforming with the proposed global optimal algorithm (GOA) and local optimal algorithm (LOA). Different from the literature, artificial noise (AN) sent by the destination not only degrades the channel condition of the eavesdropper to improve the secrecy rate, but also becomes a new source of energy powering the untrusted relay based on PS. Hence, it is of high economic benefits and efficiency to take advantage of AN compared with the literature. Simulation results show that LOA can achieve satisfactory secrecy rate performance compared with that of GOA, but with less computation time.Comment: Submitted to GlobeCom201

Surface morphology and mechanical properties of conventional and selfadhesive resin cements after aqueous aging

The stable long-term performance of resin cement under oral environmental conditions is a crucial factor to obtain a satisfactory success of the allceramic dental restoration. Objective: This study aimed at evaluating and comparing the surface morphology and mechanical property of conventional and self-adhesive resin cement after aqueous aging. Materials and Methods: Disc-shaped specimens of 3 conventional (C1: Multilink N, C2: Duolink, C3: Nexus 3) and 3 self-adhesive (S1: Multilink Speed, S2: Biscem, S3: Maxcem) types of resin cements were subjected to irradiation. After 24 h, the Knoop microhardness of each resin cement was evaluated. The specimens were immersed separately in distilled water and maintained at 37°C. A total of 5 specimens of each resin cement were collected at the following time intervals of immersion: 1, 6, 12 and 18 months. The samples were used to evaluate the Knoop parameters of microhardness, sorption and solubility. The surface morphology of the specimens after 18 months of immersion was observed by scanning electron microscopy. The sorption and solubility data were analyzed by two-way ANOVA. The Knoop microhardness was tested by the ANOVA repeated measures (P<0.05). Results: The sorption and solubility parameters of C1 and S1 exhibited significant fluctuations during the aqueous aging. The hardness of the S1 and S2 specimens decreased significantly after an 18-month water immersion. The S1, S2 and S3 specimens indicated higher filler exposure and stripping and apparent pores and cracks compared to specimens C1, C2 and C3, respectively. Conclusion: The surface of selfadhesive resin cements is more susceptible to aqueous damage than that of the conventional resin cements

Influence of light-exposure methods and depths of cavity on the microhardness of dual-cured core build-up resin composites

Objective: The purpose of this study was to evaluate the Knoop hardness number (KHN) of dual-cured core build-up resin composites (DCBRCs) at 6 depths of cavity after 3 post-irradiation times by 4 light-exposure methods. Material and Methods: Five specimens each of DCBRCs (Clearfil DC Core Plus [DCP] and Unifil Core EM [UCE]) were filled in acrylic resin blocks with a semi-cylindrical cavity and light-cured using an LED light unit (power density: 1,000 mW/cm2) at the top surface by irradiation for 20 seconds (20 s), 40 seconds (40 s), bonding agent plus 20 seconds (B+20 s), or 40 seconds plus light irradiation of both sides of each acrylic resin block for 40 seconds each (120 s). KHN was measured at depths of 0.5, 2.0, 4.0, 6.0, 8.0, and 10.0 mm at 0.5 hours, 24 hours, and 7 days post-irradiation. Statistical analysis was performed using repeated measures ANOVA and Tukey\u27s compromise post-hoc test with a significance level of p0.05). In DCP, and not UCe, at 24 hours and 7 days post-irradiation, the B+20 s method showed significantly higher KHN at all depths of cavity, except the depth of 0.5 mm (p<0.05). Conclusion: KHN depends on the light-exposure method, use of bonding agent, depth of cavity, post-irradiation time, and material brand. Based on the microhardness behavior, DCBRCs are preferably prepared by the effective exposure method, when used for a greater depth of cavity

Proses Pembelajaran Saksofon untuk Pemula di Sekolah Musik Indonesia Yogyakarta

Lembaga musik non formal khususnya di bidang pembelajaran saksofon kini semakin banyak, salah satu lembaga non formal yang menawarkan program pembelajaran saksofon yaitu Sekolah Musik Indonesia Yogyakarta yang berlokasi di jalan C. Simanjuntak. Pada pembelajaran saksofon tentunya terdapat suatu proses dan beberapa kendala baik dari faktor internal maupun eksternal, yang akhirnya mengarah terhadap bagaimana proses pembelajaran saksofon di Sekolah Musik Indonesia Yogyakarta dan apa saja kendala-kendala dalam proses pembelajaran saksofon di Sekolah Musik Indonesia yogyakarta. Pada proses pembelajaran terdapat metode yang merupakan suatu cara yang digunakan untuk mencapai suatu tujuan yang telah ditetapkan. Metode pembelajaran saksofon untuk pemula yang digunakan yaitu metode menurut George M. Bundy “The Selmer Elementary” dan metode menurut Hendry Linderman “Method for Saxophone”, adapun metode pembelajaran lainnya yang digunakan pada proses pembelajaran saksofon di Sekolah Musik Indonesia Yogyakarta sangatlah bervariasi sehingga proses pembelajaran tidak membosankan. Metode pengajaran secara umum yang digunakan yaitu metode eksperimen, tugas, diskusi, demonstrasi, tanya jawab, latihan, dan ceramah. Pada proses pembelajaran saksofon terdapat beberapa kendala baik dari faktor internal maupun eksternal yaitu meliputi lingkungan, guru, metode, kurikulum, program, materi, sarana dan prasarana. Namun di Sekolah Musik Indonesia Yogyakarta proses pembelajaran saksofon berjalan cukup baik walaupun terdapat beberapa kendala. Kata Kunci: Proses pembelajaran, Saksofon, Sekolah Musik Indonesia Yogyakart

Biochemical characterization of two GH70 family 4,6-α-glucanotransferases with distinct product specificity from Lactobacillus aviarius subsp. aviarius DSM 20655

Nine GtfB-like 4,6-α-glucanotransferases (4,6-α-GTs) (represented by GtfX of L. aviarius subsp. aviarius DSM 20655) were identified to show distinct characteristics in conserved motifs I-IV. In particular, the "fingerprint" Tyr in motif III of these nine GtfB-type 4,6-α-GTs was found to be replaced by a Trp. In L. aviarius subsp. aviarius DSM20655, a second GtfB-like protein (GtfY), containing the canonical GtfB Tyr residue in motif III, was located directly upstream of GtfX. Biochemical characterization revealed that both GtfX and GtfY showed GtfB-like 4,6-α-GT activity, cleaving (α1→4) linkages and catalyzing the synthesis of (α1→6) linkages. Nonetheless, they differ in product specificity; GtfY only synthesizes consecutive (α1→6) linkages, yielding linear α-glucan products, but GtfX catalyzes the synthesis of (α1→6) linkages predominantly at branch points (22%) rather than in linear segments (10%). The highly branched α-glucan produced by GtfX from amylose V is resistant to digestion by α-amylase, offering great potential as dietary fibers

Gluco-oligomers initially formed by the reuteransucrase enzyme of Lactobacillus reuteri 121 incubated with sucrose and malto-oligosaccharides

<p>The probiotic bacterium Lactobacillus reuteri 121 produces a complex, branched (1 -> 4, 1 -> 6)-alpha-d-glucan as extracellular polysaccharide (reuteran) from sucrose (Suc), using a single glucansucrase/glucosyltransferase (GTFA) enzyme (reuteransucrase). To gain insight into the reaction/product specificity of the GTFA enzyme and the mechanism of reuteran formation, incubations with Suc and/or a series of malto-oligosaccharides (MOSs) (degree of polymerization (DP2-DP6)) were followed in time. The structures of the initially formed products, isolated via high-performance anion-exchange chromatography, were analyzed by matrix-assisted laser-desorption ionization time-of-flight mass spectrometry and 1D/2D H-1/C-13 NMR spectroscopy. Incubations with Suc only, acting as both donor and acceptor, resulted in elongation of Suc with glucose (Glc) units via alternating (alpha 1 -> 4) and (alpha 1 -> 6) linkages, yielding linear gluco-oligosaccharides up to at least DP similar to 12. Simultaneously with the ensemble of oligosaccharides, polymeric material was formed early on, suggesting that alternan fragments longer than DP similar to 12 have higher affinity with the GTFA enzyme and are quickly extended, yielding high-molecular-mass branched reuteran (4 x 10(7) Da). MOSs (DP2-DP6) in the absence of Suc turned out to be poor substrates. Incubations of GTFA with Suc plus MOSs as substrates resulted in preferential elongation of MOSs (acceptors) with Glc units from Suc (donor). This apparently reflects the higher affinity of GTFA for MOSs compared with Suc. In accordance with the GTFA specificity, most prominent products were oligosaccharides with an (alpha 1 -> 4)/(alpha 1 -> 6) alternating structure.</p>