Journal articles on the topic 'Composite-order groups'
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ZHOU, Fu-Cai, Jian XU, Lan-Lan WANG, Chen CHEN, and Fu-Xiang LI. "A Group Signature in the Composite Order Bilinear Groups." Chinese Journal of Computers 35, no. 4 (November 16, 2012): 654–63. http://dx.doi.org/10.3724/sp.j.1016.2012.00654.
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WILDON, MARK. "Permutation groups containing a regular abelian subgroup: the tangled history of two mistakes of Burnside." Mathematical Proceedings of the Cambridge Philosophical Society 168, no. 3 (May 27, 2019): 613–33. http://dx.doi.org/10.1017/s0305004119000033.
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AbstractA group K is said to be a B-group if every permutation group containing K as a regular subgroup is either imprimitive or 2-transitive. In the second edition of his influential textbook on finite groups, Burnside published a proof that cyclic groups of composite prime-power degree are B-groups. Ten years later, in 1921, he published a proof that every abelian group of composite degree is a B-group. Both proofs are character-theoretic and both have serious flaws. Indeed, the second result is false. In this paper we explain these flaws and prove that every cyclic group of composite order is a B-group, using only Burnside’s character-theoretic methods. We also survey the related literature, prove some new results on B-groups of prime-power order, state two related open problems and present some new computational data.
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Wang, Biao, Xue Wang, Futang Hu, Xiangyu Wang, Zhongji Yang, Xiuyu Zhu, Gen Li, and Keliang Wang. "Study on the Properties of Compound Surfactants with PO Groups." Energies 17, no. 2 (January 20, 2024): 513. http://dx.doi.org/10.3390/en17020513.
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The compound surfactant system has considerable development prospects for improving oil recovery. A synergistic effect can be achieved through the orderly arrangement of the two surfactants on the interface, which can make up for the performance defects of a single surfactant. In this paper, the effects of the number of propylene oxides (PO) in composite surfactants on interfacial tension and emulsion stability were systematically studied. The results showed that the solubility of composite surfactants was significantly improved under high-salinity conditions by adding anionic–nonionic surfactants to a single anionic surfactant. The interfacial tension of composite surfactants shows a V-shaped change of first decreasing and then increasing with the increase in PO groups. As the number of PO groups increases, the emulsion first increases and then decreases. Among the series of composite surfactants, LBAS/C12PO10S has the lowest interfacial tension, reaching the order of 10−3 mN/m, and the emulsion formed by it exhibits superior stability. This indicates that the synergistic effect of the two surfactants can be improved by adjusting the number of PO groups. Furthermore, the LBAS/C12PO10S composite system can be mixed with crude oil to form Winsor III microemulsion, which has great potential for application in enhanced oil recovery via chemical flooding.
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Okazaki, Hiroyuki, Hiroshi Yamazaki, and Yasunari Shidama. "Isomorphisms of Direct Products of Finite Commutative Groups." Formalized Mathematics 21, no. 1 (January 1, 2013): 65–74. http://dx.doi.org/10.2478/forma-2013-0007.
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Summary We have been working on the formalization of groups. In [1], we encoded some theorems concerning the product of cyclic groups. In this article, we present the generalized formalization of [1]. First, we show that every finite commutative group which order is composite number is isomorphic to a direct product of finite commutative groups which orders are relatively prime. Next, we describe finite direct products of finite commutative groups
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Janko, Zvonimir. "Finite 2-groups all of whose maximal cyclic subgroups of composite order are self-centralizing." Journal of Group Theory 10, no. 1 (January 26, 2007): 1–4. http://dx.doi.org/10.1515/jgt.2007.001.
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LU, GONGRU, BING-LIN YOUNG, and XINMIN ZHANG. "A SCHEME FOR COMPLEMENTARITY AND HIGGS PHASE ANALYSES." Modern Physics Letters A 05, no. 08 (March 30, 1990): 531–42. http://dx.doi.org/10.1142/s0217732390000615.
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We introduce a simple dynamical scheme to supplement the complementarity and Higgs phase analyses of composite models with semi-simple metacolor groups. The critical couplings which signal the dynamical breakdown of the various simple groups contained in the metacolor semi-simple group determine the order of appearance of the condensates of the simple groups. Together with the Higgs phase analysis, it helps to determine the global symmetry of the fermion composite. The global symmetry group will eventually be gauged to form the low energy dynamical symmetry group of the composite.
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Kim, Mijoo, Deuk-Won Jo, Shahed Al Khalifah, Bo Yu, Marc Hayashi, and Reuben H. Kim. "Shear Bond Strength of Composite Diluted with Composite-Handling Agents on Dentin and Enamel." Polymers 14, no. 13 (June 30, 2022): 2665. http://dx.doi.org/10.3390/polym14132665.
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This in vitro study aimed to examine the shear bond strength of composite on the dentin and enamel substrates when mixed with different composite-handling agents (CHAs). Eighty extracted molars were embedded into acrylic resin and sectioned sagittally. On the prepared specimens, four groups of resin mixtures were bonded onto the enamel or dentin surfaces—composite only, composite mixed with Composite Wetting Resin (CWR), composite mixed with Brush and Sculpt (BS), and composite mixed with Modeling Resin (MR). All groups were prepared by mixing at a 1:1 ratio by weight. Each specimen was subjected to the shear bond strength test. After the test, adhesive or cohesive failures were examined at the fractured sites. Data were analyzed using one-way and two-way analysis of variance (ANOVA) and the Tukey post hoc test. All composite groups mixed with CHAs displayed a reduced shear bond strength on dentin and enamel substrates compared to composite alone (p < 0.05). The shear bond strength on dentin decreased in the following order: CWR > BS > MR. A similar pattern was observed on enamel, except that there was no statistically significant difference between BS and MR. Statistically significant interactions between resin mixtures and substrates were found (p < 0.001). On the dentin substrate, adhesive failure dominated while adhesive/cohesive failure dominated on the enamel substrate. Conclusions: The shear bonding strength of composite decreases when mixed with CHAs on both dentin and enamel substrates.
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Cheng-an, Tao, Zhang Hao, Wang Fang, Zhu Hui, Zou Xiaorong, and Wang Jianfang. "Mechanical Properties of Graphene Oxide/Polyvinyl Alcohol Composite Film." Polymers and Polymer Composites 25, no. 1 (January 2017): 11–16. http://dx.doi.org/10.1177/096739111702500102.
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Graphene oxide (GO) was served as mechanical strengthening to prepare GO/Polyvinyl Alcohol(PVA) composite film. This was accomplished in order to explore the influence of contents of GO on the tensile strength and failure strain of GO/PVA composite film. The results showed that as the GO content increased, the tensile strength of the composite film became greater rapidly at first, and then decreased gradually. When the GO content was 20%, the film had its maximum tensile strength (59.6 MPa). This is over 500% of the tensile strength of pure PVA film. The failure strain of GO/PVA composite film decreased rapidly as the GO content increased. The enhancement mechanism of the composite can be explained by the existence of multi-hydrogen bonds between the hydroxyl (-OH) groups of PVA and oxygen-containing functional groups of GO.
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Drushlyak, M., and T. Lukashova. "Non-periodic groups with the restrictions on the norm of cyclic subgroups of non-prime order." Matematychni Studii 58, no. 1 (October 31, 2022): 36–44. http://dx.doi.org/10.30970/ms.58.1.36-44.
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One of the main directions in group theory is the study of the impact of characteristic subgroups on the structure of the whole group. Such characteristic subgroups include different $\Sigma$-norms of a group. A $\Sigma$-norm is the intersection of the normalizers of all subgroups of a system $\Sigma$. The authors study non-periodic groups with the restrictions on such a $\Sigma$-norm -- the norm $N_{G}(C_{\bar{p}})$ of cyclic subgroups of non-prime order, which is the intersection of the normalizers of all cyclic subgroups of composite or infinite order of $G$. It was proved that if $G$ is a mixed non-periodic group, then its norm $N_{G}(C_{\bar{p}})$ of cyclic subgroups of non-prime order is either Abelian (torsion or non-periodic) or non-periodic non-Abelian. Moreover, a non-periodic group $G$ has the non-Abelian norm $N_{G}(C_{\bar{p}})$of cyclic subgroups of non-prime order if and only if $G$ is non-Abelian and every cyclic subgroup of non-prime order of a group $G$ is normal in it, and $G=N_{G}(C_{\bar{p}})$.Additionally the relations between the norm $N_{G}(C_{\bar{p}})$ of cyclic subgroups of non-prime order and the norm $N_{G}(C_{\infty})$ of infinite cyclic subgroups, which is the intersection of the normalizers of all infinite cyclic subgroups, in non-periodic groups are studied. It was found that in a non-periodic group $G$ with the non-Abelian norm $N_{G}(C_{\infty})$ of infinite cyclic subgroups norms $N_{G}(C _{\infty})$ and $N_{G}(C _{\bar{p}})$ coincide if and only if $N_{G}(C _{\infty})$ contains all elements of composite order of a group $G$ and does not contain non-normal cyclic subgroups of order 4.In this case $N_{G}(C_{\bar {p}})=N_{G}(C_{\infty})=G$.
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Bonilla, ED, RG Stevenson, AA Caputo, and SN White. "Microleakage Resistance of Minimally Invasive Class I Flowable Composite Restorations." Operative Dentistry 37, no. 3 (May 1, 2012): 290–98. http://dx.doi.org/10.2341/11-106-l.
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SUMMARY Minimally invasive flowable composite Class I restorations are widely used. However, flowable composites are characterized by low filler contents, modified resin formulations, low moduli of elasticity, low viscosity, generally poor mechanical properties, and decreased long-term stability. The purpose of this study was to compare the microleakage resistance of a wide variety of flowable composites used with their manufacturers' recommended bonding systems to that of a long-used and widely studied microhybrid composite when placed as minimally invasive occlusal restorations. Molar teeth were prepared in a standardized manner, restored, artificially aged, stained, sectioned, evaluated, and analyzed. Microleakage varied substantially, by a whole order of magnitude, among the material groups tested. The control group, a conventional microhybrid composite material, leaked significantly less than all the flowable composite groups. Microleakage varied very slightly among measurement site locations. Tiny microscopic bubbles were seen within many of the flowable composite specimens, as were a few voids.
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Wang, Xiqing, Atif Muhmood, Haizhong Yu, Yuqi Li, Wenying Fan, and Pengjiao Tian. "Unveiling the Potential of Novel Struvite–Humic Acid Composite Extracted from Anaerobic Digestate for Adsorption and Reduction of Chromium." Catalysts 12, no. 7 (June 22, 2022): 682. http://dx.doi.org/10.3390/catal12070682.
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A novel struvite–humic acid composite (S–HA) was derived from an anaerobic digestate and evaluated for the adsorption and reduction of chromium [Cr (VI)] in this study. The results indicated that the struvite–humic acid composite (S–HA) contains higher contents of oxygen-containing and aromatic functional groups (47.05% and 34.13%, respectively) and a higher specific surface area (19.3 m2 g−1). These special characteristics of S–HA contributed to its higher adsorption capacity (207.69 mg g−1 and 254.47 mg g−1 for pseudo-first and second-order kinetic models, respectively) for chromium. Furthermore, XPS analysis showed that a portion of the bonded Cr (VI) was reduced to Cr (III) by carboxyl and hydroxyl functional groups, which oxidized and changed into ketone and phenol functional groups. Based on the findings, it was concluded that the phosphate–humic acid composite has an outstanding chromium adsorptive and reduction capacity. However, more research is needed to fully understand the potential of the struvite–humic acid composite for chromium adsorption and reduction.
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Ayres, APA, R. Hirata, BM Fronza, BB Lopes, GMB Ambrosano, and M. Giannini. "Effect of Argon Plasma Surface Treatment on Bond Strength of Resin Composite Repair." Operative Dentistry 44, no. 2 (March 1, 2019): E75—E82. http://dx.doi.org/10.2341/18-050-l.
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SUMMARY Objectives: This study evaluated the effect of argon plasma treatment (PLA) and its combination with sandblasting (SAN), silanization (SIL), and hydrophobic bonding resin (HBR) application on the micro-shear bond strength of water-aged restorative resin composite to a newly placed composite, simulating restoration repair. Methods and Materials: Forty-five light-cured composite plates (20-mm long × 20-mm wide × 4-mm thick) were fabricated using a hybrid composite and stored at 37°C in distilled water for six months. The aged composite surfaces were treated according to the following experimental groups, varying both treatment and order of application: 1) SAN + SIL + HBR (control), 2) SAN + PLA for 30 seconds + SIL + HBR, 3) SAN + SIL + PLA + HBR, 4) PLA + SIL + HBR, 5) PLA + SIL, 6) PLA + HBR, 7) SIL + PLA + HBR, 8) SIL + PLA, and 9) PLA. After the surface treatments, four fresh resin composite cylinders (1.5-mm high × 1.5-mm diameter) of the same composite were built on each aged composite surface using a silicone mold. After water storage for 24 hours or one year, the specimens were submitted to shear bond strength testing. Data were statistically analyzed by two-way analysis of variance and Tukey's test (5%). Results: Groups 1, 2, and 4 presented significantly higher bond strength means at 24 hours, although group 4 did not differ from group 7. Groups 5, 8, and 9 demonstrated significantly lower means than the other groups. Even though groups 1 and 2 had a significant bond strength reduction after 1 year, they still demonstrated higher bond strength at one year of storage. Conclusions: While PLA application combined with surface treatment methods demonstrated high bond strength results, this treatment alone was not as beneficial as other methods that included SAN, SIL and HBR.
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Kaneko, Kosuke, Kosuke Yamashita, Daiki Fujioka, Kimiyoshi Kaneko, Kiyomi Fuchigami, Takeshi Hashishin, and Tomonori Hanasaki. "Electrorheological Effect of Gold Nanoparticles Coated with Fluorescent Mesogenic Groups Dispersed in Nematic Liquid Crystal." Crystals 11, no. 2 (February 16, 2021): 192. http://dx.doi.org/10.3390/cryst11020192.
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The electrorheological (ER) properties of composite materials consisting of a nematic liquid crystal (LC) and gold nanoparticles (GNPs) coated with bistolane-based mesogenic groups were studied. The GNPs were coated by normal alkyl chains and the fluorescent LC compounds, of which the molecular structure was similar to that of the LC matrix. The dispersity of the GNPs in the nematic LC was investigated by polarizing optical microscopy (POM). In order to improve the ER effect of the composite, a simple strategy was investigated from the viewpoint of a material design in surface-modified GNPs by lateral substitution of the mesogenic groups. The presence of the GNPs in the nematic LC led to a slightly enhanced ER effect compared to that observed for only the nematic LC. This study demonstrates the potential of a hybrid system consisting of LCs and GNPs to yield a larger ER effect.
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Moslemi, Masoumeh, Faezeh Fotouhi Ardakani, Fatemeh Javadi, Zahra Khalili Sadrabad, Zahra Shadkar, and Mohammad Saeid Shadkar. "Evaluation of Er,Cr:YSGG Laser Effect on Microshear Bond Strength of a Self-Adhesive Flowable Composite in the Dentin of Permanent Molar: An In Vitro Study." Scientifica 2016 (2016): 1–5. http://dx.doi.org/10.1155/2016/4856285.
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Aim and Background. Recently, new restorative materials such as self-adhesive flowable composites, because of their simple use and no need to bonding and etching, are considered important, particularly in pediatric dentistry. The aim of this study is to evaluate the effect of Er,Cr:YSGG laser on microshear bond strength of self-adhesive flowable composite on permanent teeth dentin in vitro.Material and Methods. In this experimental study, 40 dentin sections were prepared from healthy third molars and divided into two groups according to their surface preparation by Er,Cr:YSGG laser or without laser, only with silicon carbide paper. In each group, two groups of 10 teeth were treated with self-adhesive flowable composite (Dyad) and conventional flowable composite (acid etch and bonding). Samples were stored in normal saline and after 48 hours their bond strength was measured. The failure mode of samples was observed on stereomicroscope. In order to analyse the results, the one way ANOVA and Tukey’s test for multiple comparisons were used.Result. The maximum bond strength was related to conventional flowable composite with laser preparation group (24/21 Mpa). The lowest one was seen in Dyad composite without laser emitting (9/89 Mpa). The statistical difference between this two groups was significant (Pvalue = 0/0038). The microshear bond strength differences between Dyad composite groups with laser preparation (mean =16/427±1/79) and without laser preparation (mean =12/85±1/90) were statistically significant too (Pvalue = 0/01).Conclusion. Self-adhesive flowable composite has lower microshear bond strength than conventional flowable composite. Moreover, the laser irradiation as a surface treatment can improve this bond strength.
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Anis, Anis, Ahmed Sharshar, Saber El Hanbally, and Awad A. Shehata. "Histopathological Evaluation of the Healing Process of Standardized Skin Burns in Rabbits: Assessment of a Natural Product with Honey and Essential Oils." Journal of Clinical Medicine 11, no. 21 (October 29, 2022): 6417. http://dx.doi.org/10.3390/jcm11216417.
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Skin burns are one of the most difficult medical problems. Recently, studies have been directed towards development of natural products in order to identify effective and safe remedies. In the present study, we evaluated the efficacy of a natural composite (formulated from honey and essential oils) compared with MEBO® (0.25% β-sitosterol) and DERMAZIN® creams (1% silver-sulfadiazine) in the treatment of thermally induced skin burns. For this purpose, four burn-wounds were created on the back of male New Zealand rabbits (n = 10) using a thermal stamp under the effect of general anesthesia. Each wound represents one of the following groups: non-treated, natural composite-cream, MEBO®-cream, and silver-sulfadiazine treated groups, respectively. Treatments were applied once a day topically until one of these wounds appeared to be healed grossly. The non-treated group received no treatment. Grossly, skin burns have been healed after 28 days of the treatment in all groups except of the non-treated group. The healing efficacy of the natural composite, MEBO® and silver-sulfadiazine creams was quite similar macroscopically. However, microscopically, the epidermal layer of the composite-cream treated group was more mature than those of both MEBO® and silver-sulfadiazine creams treated groups. In conclusion, the tested composite may be a promising effective and inexpensive treatment of skin burns.
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Chatterjee, Sanjit, M. Prem Laxman Das, and R. Kabaleeshwaran. "Converting pairing-based cryptosystems from composite to prime order setting – A comparative analysis." Journal of Mathematical Cryptology 12, no. 3 (September 1, 2018): 159–90. http://dx.doi.org/10.1515/jmc-2017-0042.
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Abstract Composite order pairing setting has been used to achieve cryptographic functionalities beyond what is attainable in prime order groups. However, such pairings are known to be significantly slower than their prime order counterparts. Thus emerged a new line of research – developing frameworks to convert cryptosystems from composite to prime order pairing setting. In this work, we analyse the intricacies of efficient prime order instantiation of cryptosystems that can be converted using existing frameworks. To compare the relative efficacy of these frameworks we mainly focus on some representative schemes: the Boneh–Goh–Nissim (BGN) homomorphic encryption scheme, ring and group signatures as well as a blind signature scheme. Our concrete analyses lead to several interesting observations. We show that even after a considerable amount of research, the projecting framework implicit in the very first work of Groth–Sahai still remains the best choice for instantiating the BGN cryptosystem. Protocols like the ring signature and group signature which use both projecting and cancelling setting in composite order can be most efficiently instantiated in the Freeman prime-order projecting only setting. In contrast, while the Freeman projecting setting is sufficient for the security reduction of the blind signature scheme, the simultaneous projecting and cancelling setting does provide some efficiency advantage.
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Pramono, Edi, Candra Purnawan, Yuniawan Hidayat, Jati Wulansari, and Sayekti Wahyuningsih. "COMPOSITE OF CHITOSAN VANILIN / SULFONATED POLYSTYRENE AS POLYMER ELECTROLYTE MEMBRANES : CATIONIC EXCHANGE CAPACITY, SWELLING DEGREE AND THERMAL PROPERTIES." ALCHEMY Jurnal Penelitian Kimia 10, no. 2 (September 27, 2016): 116. http://dx.doi.org/10.20961/alchemy.10.2.55.116-129.
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Research on the preparation and characterization of sulfonated polystyrene (PST) /chitosan vanillin (KV) composite as electrolyte membranes has been conducted in order to investigate the effect of PST and KV composition to its chemical and physical properties. Polystyrene was modified by sulfonation reaction to produces PST<strong>, </strong>meanwhile chitosan was modified by schift base reaction to produces KV. The composite membranes were prepared by casting method and were characterized in order to identify the functional groups contained in the composite, the cation exchange capacity (CEC), the Swelling Degree (SD), the thermal properties and the morphology. The peak of imine vibration in the FTIR spectrum indicates that the chitosan vanilin was succesfully synthesized. Meanwhile, the peak of sulfonate vibration indicates the product of sulfonation on polystyrene. The result of CEC analysis shows that the addition of sulfonate groups on polystyrene and the addition of phenolic groups on chitosan increase the CEC value. The increasing of PST and KV concentration in membrane enhance the CEC value. However, the increasing of PST concentration in membrane composition even decrease the Swelling Degree of membranes. Meanwhile, the increasing of KV concentration increase the swelling degree of membranes. Thermal analysis shows that the thermal decomposition of membranes occurs in three stages i.e. the dehydration of water molecules, the degradation of the subtituen groups and the plasticizer and the degradation of the back bone of chitosan and polystyrene.
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Pramono, Edi, Candra Purnawan, Yuniawan Hidayat, Jati Wulansari, and Sayekti Wahyuningsih. "COMPOSITE OF CHITOSAN VANILIN / SULFONATED POLYSTYRENE AS POLYMER ELECTROLYTE MEMBRANES : CATIONIC EXCHANGE CAPACITY, SWELLING DEGREE AND THERMAL PROPERTIES." ALCHEMY Jurnal Penelitian Kimia 10, no. 2 (September 27, 2016): 116. http://dx.doi.org/10.20961/alchemy.v10i2.55.
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Research on the preparation and characterization of sulfonated polystyrene (PST) /chitosan vanillin (KV) composite as electrolyte membranes has been conducted in order to investigate the effect of PST and KV composition to its chemical and physical properties. Polystyrene was modified by sulfonation reaction to produces PST<strong>, </strong>meanwhile chitosan was modified by schift base reaction to produces KV. The composite membranes were prepared by casting method and were characterized in order to identify the functional groups contained in the composite, the cation exchange capacity (CEC), the Swelling Degree (SD), the thermal properties and the morphology. The peak of imine vibration in the FTIR spectrum indicates that the chitosan vanilin was succesfully synthesized. Meanwhile, the peak of sulfonate vibration indicates the product of sulfonation on polystyrene. The result of CEC analysis shows that the addition of sulfonate groups on polystyrene and the addition of phenolic groups on chitosan increase the CEC value. The increasing of PST and KV concentration in membrane enhance the CEC value. However, the increasing of PST concentration in membrane composition even decrease the Swelling Degree of membranes. Meanwhile, the increasing of KV concentration increase the swelling degree of membranes. Thermal analysis shows that the thermal decomposition of membranes occurs in three stages i.e. the dehydration of water molecules, the degradation of the subtituen groups and the plasticizer and the degradation of the back bone of chitosan and polystyrene.
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The, Le Cao, Vu Minh Tan, and Phan Thi Binh. "REMOVAL OF Pb2+ FROM AQUEOUS SOLUTION BY ADSORPTION ONTO COMPOSITE BASED ON EUCALYPTUS LEAF AND POLYANILINE." Vietnam Journal of Science and Technology 55, no. 1 (February 9, 2017): 54. http://dx.doi.org/10.15625/0866-708x/55/1/8360.
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Composite based on eucalyptus leaf and polyaniline (EL-PANi) was prepared by chemical polymerization method. It showed that the function groups belonging to polyaniline and eucalyptus leaf were found through IR analysis and the nanostructure of composite was explained by SEM images. The adsorption of Pb2+ was carried out onto composite in aqueous solution via varying pH, contact time, and its initial concentration. The experimental adsorption data fitted well into Freundlich adsorption isotherm model (r2 = 0.9873). The adsorption process followed pseudo-second order kinetic with r2 = 0.9995. The maximum adsorption capacity of Pb2+ onto that composite was 172.4138 mg/g by Langmuir equation and KF was 58.7527 mg/g by Freundlich one.
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Zhai, Yingxiang, Jiangtao Wang, Hao Wang, Tao Song, Weitong Hu, and Shujun Li. "Preparation and Characterization of Antioxidative and UV-Protective Larch Bark Tannin/PVA Composite Membranes." Molecules 23, no. 8 (August 19, 2018): 2073. http://dx.doi.org/10.3390/molecules23082073.
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In order to prepare functional materials for antioxidant and ultraviolet (UV)-protective green food packaging, condensed tannin, previously extracted from larch bark, was mixed with polyvinyl alcohol (PVA), and then the mixture was used to cast composite membranes. An antioxidative assay using 1,1-diphenyl-2-picrylhydrazyl (DPPH)—a free radical scavenger—and starch–potassium iodide oxidation–discoloration analyses showed that the composite membranes have good antioxidative activities. The low UV transmission and protective effect of the composite films on vitamin E indicated the UV protection ability of the composite membranes. Both larch bark tannin and PVA are rich in hydroxyl groups; scanning electron microscopy analysis demonstrated their compatibility. Also, the mechanical and crystallization properties of the composite membranes did not significantly decrease with the addition of larch bark tannin.
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Ahn, Jae Seok, Kwang Ik Son, Kwang Sung Woo, and Young Shik Shin. "Singular Behavior of Laminated Skew Composite Materials with Cross-Ply Stacking." Advanced Materials Research 538-541 (June 2012): 1640–45. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.1640.
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This study deals with effects depending on skew angles in skewed-laminated composite materials in macroscopic point of view. Based on higher-order approximation of displacements, subparametric layer-wise finite elements are used to analyze skewed-laminated composite systems. The elements have higher-order shape functions derived from the Lobatto shape functions. The modes of the elements are classified into three groups such as vertex, side, and internal modes. The vertex modes have physical meaning, while side and internal modes with respect to the increase of order of the Lobatto shape functions do not have physical meaning but improve accuracy of analysis. Therefore, fixing mesh arrangement of present analysis, the quality of the analysis can be enhanced without re-meshing work. The approach based on p-version of finite element method is implemented with three-dimensional elasticity theory, while shape functions are developed by combination of one- and two-dimensional shape functions, not using three-dimensional shape functions. Using the accurate and practical proposed technique, macroscopic behavior of skewed-laminated composite materials is investigated.
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Li, Pengchao, Baohua Zhu, Peng Li, Zhihao Zhang, Luyao Li, and Yuzong Gu. "A Facile Method to Synthesize CdSe-Reduced Graphene Oxide Composite with Good Dispersion and High Nonlinear Optical Properties." Nanomaterials 9, no. 7 (June 30, 2019): 957. http://dx.doi.org/10.3390/nano9070957.
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CdSe-reduced graphene oxide (CdSe/RGO) composites were synthesized by a hydrothermal method. CdSe/RGO composites with different mass ratios were prepared. The structure and morphology of CdSe/RGO composites were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The synthesis of CdSe/RGO complexes was successfully demonstrated by Fourier infrared (FT-IR) and Raman spectra. CdSe nanoparticles in the CdSe/RGO composite were uniformly dispersed on the graphene surface. The study found that oxygen-containing functional groups such as hydroxyl (-OH) and carboxyl (-COOH) groups in graphene played a decisive role in the dispersion of CdSe. The third-order nonlinear optical properties of CdSe/RGO composites were measured by a single beam Z-scan technique. The experimental results showed that composites exhibited two-photon absorption and self-focusing nonlinear refraction properties. Additionally, the third-order nonlinear susceptibility of the composite material was obviously enhanced, which was mainly due to the good dispersion of CdSe nanoparticles on graphene.
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Kristanti, Yulita, and Diatri Nari Ratih. "PENGARUH PENUND AAN TAHAP PENUMPATAN DENGAN RESIN KOMPOSIT PADA TEKNIK SANDWICH TERHADAP KEKUATAN TARIK PELEKATAN SEMEN IONOMER KACA DAN RESIN KOMPOSIT." Journal of Dentomaxillofacial Science 1, no. 1 (December 4, 2016): 46. http://dx.doi.org/10.15562/jdmfs.v1i1.129.
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Sandwich technique, a combination filling technique using composite resin filling material and glass ionomer cement has been widely used. In fact, such a combination filling technique need ffcf i longer time compare to filling without combination. This research was done in order to know the influence of delayed fill ; ing in sandwich technique using composite resin related to the tensile strength between glass ionomer cement and composite resin.The materials studied consist of 16 samples, that were divided into 4 groups. The first one was used as the control groupt without delaying), while group II-IVwas used as the treating groups. Each group consist of 4 samples. The difference treatment between group II-IVwas the soaking time in the artificial saliva. Group II was soaked into artificial saliva (pH5)for 1 day, group , HI for 7 days, and group IVfor 14 days. The result of this research shows that the diference among the groups involved were very significant, except between group I and group II.The longer the sample was soaked into the artificial saliva, the tensile strength tends to decrease.
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Li, Yong Feng, Chi Jiang, Duo Jun Lv, Xiao Ying Dong, and Yi Xing Liu. "Wood-Polymer Composite Prepared by In Situ Synthesis of Copolymer within Wood and its Dimensional Stability." Advanced Materials Research 150-151 (October 2010): 1–5. http://dx.doi.org/10.4028/www.scientific.net/amr.150-151.1.
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In order to improve the value-added applications of low-quality wood, a novel Wood-Polymer Composite was fabricated by in-situ synthesis of copolymer from monomers within wood porous structure. The structure was characterized with SEM and FTIR, and its dimensional stability was also tested. The SEM observations showed that copolymer filled up wood pores and contact tightly with wood matrix, indicating strong interactions between them. FTIR analysis indicated that when the monomers copolymerized in situ wood porous structure, they also reacted with wood matrix by reaction of hydroxyl groups and ester groups, indicating chemical bond between the two phases, which is agreement with SEM observations. The volume swelling efficiency and contact angle of such composite were higher than those of wood, respectively, indicating good dimensional stability involving volume swelling efficiency and contact angle. Such composite could be potentially applied in fields of construction, traffic and indoor decoration.
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Stoleriu, Simona, Sorin Andrian, Irina Nica, Andrei Victor Sandu, Galina Pancu, Alice Murariu, and Gianina Iovan. "Evaluation of Adhesive Capacity of Universal Bonding Agents Used in Direct Composite Resins Repair." Materiale Plastice 54, no. 3 (September 30, 2017): 574–77. http://dx.doi.org/10.37358/mp.17.3.4899.
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The aims of the study were to characterise the resin-resin interface when a universal bonding agent (UBA) was used in two different strategies in direct composite repair and to evaluate the bonding capacity of UBA by microleakage assessment. In study groups a micro-filled hybrid and a nano-filled hybrid composite resins were aged in order to simulate an old restorations. As a repair material was chosen the same micro-filled hybrid composite resin that was used as an old restoration. UBA was applied in etch-and-rinse and self-etch strategies and was used as an intermediate layer in repair procedure. After the repair the samples were aged again. In control groups were included non-aged, repaired composite resins samples. The resin-resin interface was characterised on SEM images and the microleakage at the interface was evaluated by dye penetration assessment. Universal bonding agent used in direct composite resins repair showed a very good adaptation to non-aged micro-filled hybrid and nano-filled hybrid composite resins. Aging by saliva storage of repaired composite resins leaded to an enlargement of resin-resin junction and a increased microleakage irrespective of the strategy (etch-and-rinse or self -etch) used for bonding agent application. Etch-and-rinse strategy for universal bonging agent application determined a better interface bonding when compared to self -etch strategy.
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Xiao, Wen Qian, Yu Mei Xiao, Xian Tao Wen, Hong Song Fan, and Xing Dong Zhang. "Preparation and Cytocompatibility of Novel Nano-HA/PLA Composite." Key Engineering Materials 330-332 (February 2007): 369–72. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.369.
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In order to prepare nano-hydroxyapatite/poly(lactide) (n-HA/PLA) composite with good interfacial interaction, some groups which could bind with Ca ions in HA crystals need to be introduced onto PLA surface. Poly(α-methacrylic acid) (PMAA) was grafted on the PLA surfaces via photooxidization and subsequent UV induced polymerization. Suspension of PMAA-PLA microparticles with an average size as 133.1nm was prepared with solvent evaporation technique. Then utilizing the action of template manipulating of PMAA-PLA microparticles, n-HA/PLA composite were synthesized. Zeta potentials measurement and SEM indicated that there were good interfacial interactions between two phases of n-HA/PLA composite. The results of cell viability confirmed that n-HA/PLA composite possessed good cytocompatibility, so the n-HA/PLA composite scaffold obtained by electrospun technology might be used as bone tissue engineering scaffold.
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Moosavi, Horieh, Marjaneh Ghavamnasiri, and Vahideh Manari. "Effect of Postoperative Bleaching on Marginal Leakage of Resin Composite and Resin-Modified Glass Ionomer Restorations at Different Delayed Periods of Exposure to Carbamide Peroxide." Journal of Contemporary Dental Practice 10, no. 6 (2009): 1–8. http://dx.doi.org/10.5005/jcdp-10-6-1.
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Abstract Aim To evaluate the effect of dental bleaching with carbamide peroxide at different exposure times on the microleakage of resin composite and resin-modified glass ionomer restorations after placement in extracted human teeth. Methods and Materials 120 Class V cavity preparations were placed at the cementoenamel junction (CEJ) of human teeth. Half of the cavities were restored with Filtek P60 resin composite(C) and the other half were restored with Fuji II LC resin-modified glass ionomer (G). Each group was randomly divided into four subgroups (n=15). Groups C1 and G1 were not bleached and stored in artificial saliva at 37°C to serve as control groups, while in Groups C2 and G2, C3 and G3, and C4 and G4 specimens were exposed to a 15% carbamide peroxide gel for one day, one week, and two weeks, respectively, following the placement of restorations. Microleakage was assessed using the dye penetration method. Data were analyzed using the Kruskal-Wallis and Wilcoxon tests (p=0.05). Results The Kruskal-Wallis test showed no significant difference among all groups of composite or glass ionomer restorations with either enamel or dentinal margins with regard to microleakage (p>0.05). The Wilcoxon test revealed more marginal leakage in the enamel/ glass ionomer margins than the enamel/ composite margins (p<0.05). In comparisons within each group, the Wilcoxon test showed there was more microleakage in dentinal margins of composite restorations than in the enamel margins in the test groups (p<0.05). The dentinal margins of the glass ionomer in control groups showed more leakage than the enamel margins, but after the bleaching procedure all experimental groups showed statistically similar microleakage in both the enamel and dentinal margins (p>0.05). Conclusions Postoperative bleaching with carbamide peroxide could increase microleakage in the dentinal margins of composite and the enamel margins of resin-modified glass ionomer restorations. Clinical Significance Rebonding of resin composite restorations should be considered following bleaching with 15% carbamide peroxide in order to reseal the margins. Resin-modified glass ionomer is not suitable as a filling material before bleaching because of its susceptibility to increased microleakage. Citation Moosavi H, Ghavamnasiri M, Manari V. Effect of Postoperative Bleaching on Marginal Leakage of Resin Composite and Resin-Modified Glass Ionomer Restorations at Different Delayed Periods of Exposure to Carbamide Peroxide. J Contemp Dent Pract [Internet]. 2009 Nov; 10(6):009-016. Available from: http://www.thejcdp. com/journal/view/volume10-issue6-moosavi.
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Moosavi, Horieh, Marjaneh Ghavamnasiri, and Vahideh Manari. "Effect of Postoperative Bleaching on Marginal Leakage of Resin Composite and Resin-Modified Glass Ionomer Restorations at Different Delayed Periods of Exposure to Carbamide Peroxide." Journal of Contemporary Dental Practice 10, no. 6 (2009): 9–16. http://dx.doi.org/10.5005/jcdp-10-6-9.
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Abstract Aim To evaluate the effect of dental bleaching with carbamide peroxide at different exposure times on the microleakage of resin composite and resin-modified glass ionomer restorations after placement in extracted human teeth. Methods and Materials 120 Class V cavity preparations were placed at the cementoenamel junction (CEJ) of human teeth. Half of the cavities were restored with Filtek P60 resin composite(C) and the other half were restored with Fuji II LC resin-modified glass ionomer (G). Each group was randomly divided into four subgroups (n=15). Groups C1 and G1 were not bleached and stored in artificial saliva at 37°C to serve as control groups, while in Groups C2 and G2, C3 and G3, and C4 and G4 specimens were exposed to a 15% carbamide peroxide gel for one day, one week, and two weeks, respectively, following the placement of restorations. Microleakage was assessed using the dye penetration method. Data were analyzed using the Kruskal-Wallis and Wilcoxon tests (p=0.05). Results The Kruskal-Wallis test showed no significant difference among all groups of composite or glass ionomer restorations with either enamel or dentinal margins with regard to microleakage (p>0.05). The Wilcoxon test revealed more marginal leakage in the enamel/ glass ionomer margins than the enamel/ composite margins (p<0.05). In comparisons within each group, the Wilcoxon test showed there was more microleakage in dentinal margins of composite restorations than in the enamel margins in the test groups (p<0.05). The dentinal margins of the glass ionomer in control groups showed more leakage than the enamel margins, but after the bleaching procedure all experimental groups showed statistically similar microleakage in both the enamel and dentinal margins (p>0.05). Conclusions Postoperative bleaching with carbamide peroxide could increase microleakage in the dentinal margins of composite and the enamel margins of resin-modified glass ionomer restorations. Clinical Significance Rebonding of resin composite restorations should be considered following bleaching with 15% carbamide peroxide in order to reseal the margins. Resin-modified glass ionomer is not suitable as a filling material before bleaching because of its susceptibility to increased microleakage. Citation Moosavi H, Ghavamnasiri M, Manari V. Effect of Postoperative Bleaching on Marginal Leakage of Resin Composite and Resin-Modified Glass Ionomer Restorations at Different Delayed Periods of Exposure to Carbamide Peroxide. J Contemp Dent Pract [Internet]. 2009 Nov; 10(6):009-016. Available from: http://www.thejcdp. com/journal/view/volume10-issue6-moosavi.
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QUINTAS, Adriana Ferreira, Marco Antonio BOTTINO, Maximiliano Piero NEISSER, and Maria Auxiliadora Junho de ARAÚJO. "Effect of the surface treatment of plain carbon fiber posts on the retention of the composite core: an in vitro evaluation." Pesquisa Odontológica Brasileira 15, no. 1 (March 2001): 64–69. http://dx.doi.org/10.1590/s1517-74912001000100012.
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This study aims to evaluate the role of surface treatments performed on plain carbon fiber posts, in relation to serrated carbon fiber posts, in the retention of the composite core. Fifty carbon fiber posts received surface treatments in order to verify their influence on the retention of the core material. An acrylic resin mold was developed in order to precisely fit the post, leaving a machined space to accommodate a self-curing composite resin. After the surface treatment, a primer was applied on the coronal portion of all posts, which were then dried. They were fitted to the mold and received a 3 mm composite core. All specimens were thermocycled and then stored in distilled water for a week. Tension test was performed at a speed of 0.5 mm/min until there was lack of adhesion or fracture of the core. The conclusions were: a) the values of retention related to aluminum oxide spray (group A), depth cutter diamond burs (group C) and posts with machined coronal portion (group D) were comparable to those of serrated posts (group E), although no statistically significant difference between these groups was found; b) the mean values of core retention in group B (medium grit diamond burs) were statistically lower than those of other groups.
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He, Shaojian, Zhongrui Lu, Wenxu Dai, Kangning Yang, Yang Xue, Xiaoyang Jia, and Jun Lin. "Anchoring Water Soluble Phosphotungstic Acid by Hybrid Fillers to Construct Three-Dimensional Proton Transport Networks." Membranes 11, no. 7 (July 15, 2021): 536. http://dx.doi.org/10.3390/membranes11070536.
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Phosphotungstic acid (HPW)-filled composite proton exchange membranes possess high proton conductivity under low relative humidity (RH). However, the leaching of HPW limits their wide application. Herein, we propose a novel approach for anchoring water soluble phosphotungstic acid (HPW) by polydopamine (PDA) coated graphene oxide and halloysite nanotubes (DGO and DHNTs) in order to construct hybrid three-dimensional proton transport networks in a sulfonated poly(ether ether ketone) (SPEEK) membrane. The introduction of PDA on the surfaces of the hybrid fillers could provide hydroxyl groups and secondary amine groups to anchor HPW, resulting in the uniform dispersion of HPW in the SPEEK matrix. The SPEEK/DGO/DHNTs/HPW (90/5/5/60) composite membrane exhibited higher water uptake and much better conductivity than the SPEEK membrane at low relative humidity. The best conductivity reached wass 0.062 S cm−1 for the composite membrane, which is quite stable during the water immersion test.
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Mahadevan, S., and X. Liu. "Probabilistic Optimum Design of Composite Laminates." Journal of Composite Materials 32, no. 1 (January 1998): 68–82. http://dx.doi.org/10.1177/002199839803200104.
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This paper proposes a procedure for the optimum design of composite laminates under probabilistic considerations. The problem is formulated to consider the minimization of laminate weight as the objective function and the reliability requirements as the constraints. Both system-level and element-level reliabilities are considered. The first-order reliability method (FORM) is used to estimate the reliability of each ply group, and system reliability is computed based on series or parallel system assumptions. The Tsai-Wu strength criterion is adopted to derive the limit state function of individual ply groups in the laminate. The gradient and sensitivity information of the objective function and the constraints with respect to the design variables are obtained by using sensitivity analysis based on the composite plate theory. Thus the proposed procedure brings together modern concepts of reliability analysis, composite laminate behavior and nonlinear optimization to develop a rational and practical procedure for the optimum design of composite laminates. Numerical examples are presented to demonstrate the effectiveness of the proposed method.
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Liu, Yi, Yumin Huang, Aiping Xiao, Huajiao Qiu, and Liangliang Liu. "Preparation of Magnetic Fe3O4/MIL-88A Nanocomposite and Its Adsorption Properties for Bromophenol Blue Dye in Aqueous Solution." Nanomaterials 9, no. 1 (January 2, 2019): 51. http://dx.doi.org/10.3390/nano9010051.
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Metal-organic frameworks (MOFs) are considered as good materials for the adsorption of many environmental pollutants. In this study, magnetic Fe3O4/MIL-88A composite was prepared by modification of MIL-88A with magnetic nanoparticles using the coprecipitation method. The structures and magnetic property of magnetic Fe3O4/MIL-88A composite were characterized and the adsorption behavior and mechanism for Bromophenol Blue (BPB) were evaluated. The results showed that magnetic Fe3O4/MIL-88A composite maintained a hexagonal rod-like structure and has good magnetic responsibility for magnetic separation (the maximum saturation magnetization was 49.8 emu/g). Moreover, the maximum adsorption amount of Fe3O4/MIL-88A composite for BPB was 167.2 mg/g and could maintain 94% of the initial adsorption amount after five cycles. The pseudo-second order kinetics and Langmuir isotherm models mostly fitted to the adsorption for BPB suggesting that chemisorption is the rate-limiting step for this monomolecular-layer adsorption. The adsorption capacity for another eight dyes (Bromocresol Green, Brilliant Green, Brilliant Crocein, Amaranth, Fuchsin Basic, Safranine T, Malachite Green and Methyl Red) were also conducted and the magnetic Fe3O4/MIL-88A composite showed good adsorption for dyes with sulfonyl groups. In conclusion, magnetic Fe3O4/MIL-88A composite could be a promising adsorbent and shows great potential for the removal of anionic dyes containing sulfonyl groups.
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Li, Xiang Jie, Zai Gen Mu, Ping An Li, and Ju Bing Zhang. "Study on Stud Shear Connectors Subjected to Single Cyclic Loading." Advanced Materials Research 163-167 (December 2010): 2013–16. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.2013.
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In order to study the behavior of connectors used in steel-concrete composite beam subjected to single cyclic loading, three groups of studs were tested with new specimen and new method, stud’s diameter is different among each group(Φ16,Φ19,Φ22). Stud’s fatigue behavior subjected to single cyclic loading various with the diameter.
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Goulart, Marcelo, Deisi Fátima Damin, Rafael Melara, and Andréa De Azevedo Brito Conceição. "Effect of pre-heating composites on film thickness." Journal of Research in Dentistry 1, no. 4 (December 13, 2013): 274. http://dx.doi.org/10.19177/jrd.v1e42013274-280.
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Resin composite has been suggested as a luting material for aesthetic indirect restorations and temperature affects material viscosity. Reports of film thickness from new composites are important. The aim of this study was to analyze the influence of pre-heating two resin composites on its film thickness in order to use it as a luting agent for indirect restorations (inlays and onlays). Three materials were divided into 5 groups. Two resin composites, nanofilled (Z350 XT/3MESPE) and microhybrid (Opallis/FGM), pre–heated and room temperature, and a resin cement (AllCem/FGM) were tested. Following the guidelines from ISO 4049, each material (0,05mL) was pressed under 15kg between two glass plates covered with polyester film for 180 seconds. After pressed, the material was light polymerized with a LED for 40s and the film thickness measured using a digital micrometer. When testing the groups of pre-heated resin composites the material was heated (64°C) on a specific device (CalSet/AdDent) before all procedures. Data were analyzed using t-Student, ANOVA and Tukey post hoc test (α=.05). Resin cement group showed the lower film thickness mean (28,2 µm), followed by the pre-heated microhybrid (45,3 µm). The higher values were obtained with nanofilled composite. Nanofilled room temperature group presented the highest thickness (96,1 µm). Statistical difference was found between all groups. Pre-heating influenced the film thickness of both composites. In this study a microhybrid composite showed better results among resin composite groups. Although not presenting the lower film thickness, as resin cement, some composites could be used for luting indirect restorations when heated.
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Zogheib, Lucas Villaça, Jefferson Ricardo Pereira, Accácio Lins do Valle, Jonas Alves de Oliveira, and Luiz Fernando Pegoraro. "Fracture resistance of weakened roots restored with composite resin and glass fiber post." Brazilian Dental Journal 19, no. 4 (2008): 329–33. http://dx.doi.org/10.1590/s0103-64402008000400008.
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This study evaluated the fracture resistance of weakened roots restored with glass fiber posts, composite resin cores and complete metal crowns. Thirty maxillary canines were randomly divided into 3 groups of 10 teeth each: teeth without weakened roots (control); teeth with partially weakened roots (PWR) and teeth with and largely weakened roots (LWR). The control group was restored with glass fiber posts and a composite resin core. Teeth in the PWR and LWR groups were flared internally to standardized dimensions in order to simulate root weakness. Thereafter, the roots were partially filled with composite resin and restored in the same way as in the control group. The specimens were exposed to 250,000 cycles in a controlled chewing simulator. All intact specimens were subjected to a static load (N) in a universal testing machine at 45 degrees to the long axis of the tooth until failure. Data were analyzed by one-way ANOVA and Dunnett's test for multiple comparisons (p=0.05). There were statistically significant difference differences (p<0.01) among the groups (control group = 566.73 N; PWR = 409.64 N; and LWR = 410.91 N), with significantly higher fracture strength for the control group. There was no statistically significant difference (p>0.05) between the weakened groups. The results of this study showed that thicker root dentin walls significantly increase the fracture resistance of endodontically treated teeth.
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Segarceanu, Mircea, Alexandra Raluca Miron, Carmen Georgiana Lica, Ovidiu Oprea, Abbas Abdul Kadhim Klaif Rikabi, and Danut Ionel Vaireanu. "Comparative Study of Polysulfone Matrix Based Composite Membranes Designed for Fuel Cells." Revista de Chimie 69, no. 4 (May 15, 2018): 772–76. http://dx.doi.org/10.37358/rc.18.4.6198.
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In this work, the synthesis and characterization of new types of composite membranes with polysulfone matrix and ionomeric polymer electrolyte: polysulfone-sulfonated polyetherether sulfone (PSf-SPEEK) or polysulfone - poly (styrene sulfonic acid-co-vinylpyridine (PSf-PSSA), with sulfonic groups, with high performances, but especially economically viable, are studied. The composite membranes have different behavior depending upon the two ionofores. This is both due to the different temperatures of the total dehydration and to the decomposing temperature specific to each combination. The most unfavorable observation is the weight loss of PSfD-PSSA and PSfN-PSSA at temperatures under 170�C, most probably due to improper reticular degree. Nevertheless, the thermals diagrams of the composite membranes slightly differ for the same ionofore, suggesting the possibility of usage of the composite membrane on a polysulfone support - obtained from either the available or more accessible solvent. This observation is not yet valid neither from the ionic interchange nor from the conductivity point of view, since the performances of the two composites drastically differ with respect to the supports used here (PSf-D and PSf-N). Comparing the thermic performances, the recommended usage order to consider for the composite membranes is: PSfN-SPEEK = PSfD-SPEEK ] PSfD-PSSA = PSfN-PSSA.From the electrical performances point of view, the composites classify in the following order: PSfD-PSSA ]PSfN-PSSA ]] PSfD-SPEEK ] PSfN-SPEEK. At this time of research, it is difficult to establish an optimal composite membrane for fuel cell, although the composite PSfD-PSSA seems to be preferred.
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Cinelli, Francesca, Daniele Scaminaci Russo, Michele Nieri, and Luca Giachetti. "Stain Susceptibility of Composite Resins: Pigment Penetration Analysis." Materials 15, no. 14 (July 13, 2022): 4874. http://dx.doi.org/10.3390/ma15144874.
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Composite resins are considered the material of choice for esthetic direct restorations, considering both their satisfying esthetic and mechanical properties. The success of composite resin restorations depends highly on their color stability. Discoloration causes color mismatch, consequent patient dissatisfaction, and eventually additional costs for correction/replacement of the restoration. The purpose of this study was to evaluate the degree of pigment penetration within the composite resins, in order to understand how discoloration can be treated properly. Two different commercially available composite resins were compared in the study: a nano-filled composite resin and a non-homogeneous micro-hybrid composite resin. A coffee solution was used to induce staining of the materials. Subsequently, the penetration of the pigments was measured by analyzing the color from the outside to the inside of the specimen. 14 levels were analyzed starting from 0.1 mm to 3.0 mm in depth. The ANOVA test demonstrated a statistically significant difference (p < 0.0001) between test and control groups up to a depth of 1.0 mm for the nano-filled composite and up to a depth of 2.0 mm for the non-homogeneous micro-hybrid composite. The two composite resin materials, subjected to pigmenting treatment, underwent a color variation with different patterns.
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Zhang, Kai, Xifang Chen, Yuling Xiao, Rujia Liu, and Jie Liu. "Enhanced Anticorrosion Properties through Structured Particle Design of Waterborne Epoxy-Styrene-Acrylate Composite Emulsion." Coatings 11, no. 11 (November 21, 2021): 1422. http://dx.doi.org/10.3390/coatings11111422.
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In order to develop a waterborne epoxy-styrene–acrylate composite latex with a better stability and anticorrosion resistance, a novel synthetic approach has been proposed. First, modified by methyl acrylic, epoxy resin containing terminal C=C double bonds was successfully synthesized, where epoxide groups were partially retained. Then, by structural design and multi-stage seed emulsion copolymerization, a stable waterborne epoxy-styrene-acrylate composite latex composed of a modified epoxy resin acrylate polymer as the core, inert polystyrene ester as the intermediate layer, and carboxyl acrylate polymer as the shell was successfully fabricated. The structure of the obtained latex was characterized by fourier transform infrared (FTIR) and transmission electron microscopy (TEM). The stability of the composite latex was tested based on the wet gel weight, Zeta potential, and storage stability, and the corrosion resistance of the composite latex films was analyzed by electrochemical measurements and salt spray tests. The thickness of each layer of the composite latex was calculated by the temperature random multi-frequency modulation DSC (TOPEM-DSC) technique. In addition to the successful emulsion copolymerization that occurred between the modified epoxy resin and acrylate monomer, the presence of carboxyl groups in the obtained latex was evidenced, while the epoxide groups were partially retained. The anticorrosion resistance and stability of the multilayer composite latex with the intermediate layer are better than that of the conventional core-shell latex. The outstanding stability and corrosion resistance is attributed to the multilayer core-shell structure. The TOPEM-DSC approach can accurately determine the thickness of the intermediate layer in the multilayer core-shell particles and is a new strategy for characterizing the core-shell structure of polymer particles with a similar monomer composition.
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Kim, ME, and SH Park. "Comparison of Premolar Cuspal Deflection in Bulk or in Incremental Composite Restoration Methods." Operative Dentistry 36, no. 3 (May 1, 2011): 326–34. http://dx.doi.org/10.2341/10-315-l.
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SUMMARY Objectives This study examined the cuspal deflection of maxillary premolars when either a bulk filling or incremental filling technique was employed using a range of composites with different elastic moduli. Methods Four brands of composite materials, Heliomolar (HM, Ivoclar Vivadent, Schaan, Liechtenstein), Heliomolar HB (HH, Ivoclar Vivadent, Schaan, Liechtenstein), Filtec Supreme XT (FS, 3M Dental Product, St Paul, MN, USA), and Renew (RN, Bisco Inc, Schaumburg, IL, USA), as well as three filling techniques, bulk filling, two-layer incremental filling, and three-layer incremental filling methods, were used. One hundred twenty caries-free human premolars were collected and divided into four groups according to the filling material used. Each of these four groups was then subdivided into three groups according to filling method. In group 1, a bulk filling of 0.15 g of each resin was inserted and light-cured with LED light from the occlusal, mesial, and distal surfaces for 60 seconds each. Group 2 was given two horizontal increments, 0.08 g and 0.07 g, with each increment light-cured from the occlusal, mesial, and distal surfaces for 30 seconds each. In group 3, three horizontal increments of 0.05 g were used, each of which was light-cured from the occlusal, mesial, and distal surfaces for 20 seconds each. The cuspal deflection was measured using a customized cuspal deflection measuring machine for 10 minutes after initiating light polymerization. The elastic modulus of each composite resin material was measured using a three-point bending test. Two-way analysis of variance (ANOVA) with a Dunnet test was used to examine the effect of the two variables (curing methods, materials) on the amount of cuspal deflection at the 95% confidence level. In each material, groups 1, 2 and 3 were compared using one-way ANOVA and a Dunnet test at the 95% confidence level. The elastic moduli of HM, HH, FS, and RN were compared using one-way ANOVA and a Tukey test at the 95% confidence level. The relationship between the amount of cuspal deflection in each group and the elastic modulus of the composite was analyzed using a Pearson correlation test. Results The amount of cuspal deflection in HH was larger than in the other materials (HM, FS, and RN; p<0.05). There was no significant difference between HM, FS, and RN. The amount of cuspal deflection was greatest in group 1, followed in order by groups 2 and 3 (p<0.05). The amount of cuspal deflection was in the following order: group 1≥2≥3 in HM, and 1>2, 3 in HH, FS, and RN. The elastic modulus was HH>RN>FS>HM (p<0.05). There was a positive correlation between the cuspal deflection and the elastic modulus of the composite. Conclusions The incremental filling techniques reduced the amount of cuspal deflection in all composite groups with different elastic moduli. The amount of cuspal deflection showed a positive correlation with the elastic modulus of the composite.
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Behnaz, Mohammad, Kazem Dalaie, Hoori Mirmohammadsadeghi, Hamed Salehi, Vahid Rakhshan, and Farzin Aslani. "Shear bond strength and adhesive remnant index of orthodontic brackets bonded to enamel using adhesive systems mixed with TiO2 nanoparticles." Dental Press Journal of Orthodontics 23, no. 4 (August 2018): 43.e1–43.e7. http://dx.doi.org/10.1590/2177-6709.23.4.43.e1-7.onl.
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ABSTRACT Introduction: It is recently suggested that titanium dioxide (TiO2) nanoparticles can be added to bracket luting agents in order to reduce bacterial activity and protect the enamel. However, it is not known if this addition can affect the shear bond strength (SBS) below clinically acceptable levels. Therefore, this study examined this matter within a comprehensive setup. Methods: This in vitro experimental study was conducted on 120 extracted human premolars randomly divided into four groups (n=30): in groups 1 and 2, Transbond XT light-cured composite with or without TiO2 was applied on bracket base; in groups 3 and 4, Resilience light-cured composite with or without TiO2 was used. Brackets were bonded to teeth. Specimens in each group (n=30) were divided into three subgroups of 10 each; then incubated at 37°C for one day, one month, or three months. The SBS and adhesive remnant index (ARI) were calculated and compared statistically within groups. Results: The SBS was not significantly different at one day, one month or three months (p>0.05) but composites without TiO2 had a significantly higher mean SBS than composites containing TiO2 (p<0.001). The SBS of Transbond XT was significantly higher than that of Resilience (p<0.001). No significant differences were noted in ARI scores based on the type of composite or addition of TiO2 (p>0.05). Conclusions: Addition of TiO2 nanoparticles to Transbond XT decreased its SBS to the level of SBS of Resilience without TiO2; thus, TiO2 nanoparticles may be added to Transbond XT composite for use in the clinical setting.
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Sorova, I. N., and K. M. Egorova. "Lexico-semantic characteristics of composite ornithonyms in the Yakut and Altai languages." Altaistics, no. 3 (October 5, 2023): 13–23. http://dx.doi.org/10.25587/2782-6627-2023-3-13-23.
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The issues of comparative language learning are among the most relevant topics in modernlinguistics. The comparative typological method is especially important when studying the word-formationsystems of two languages in order to identify similarities and differences. Complex words actively replenishthe lexical stock of the language in all its functional varieties. There is a fairly voluminous layer of vocabularyof composite words representing the names of birds – ornithonyms. The abundance of composite words inthe Yakut and Altai languages used for naming birds, and the lack of work on their comprehensive researchand systematization indicates the need for scientific research of bird names. The purpose of this work isto study the lexical and semantic features and word-formation structures of composite words denoting thenames of birds in the Yakut and Altai languages. In order to achieve this goal, the following tasks are solved:identification of the functional meaning of composite words; consideration of the history of the study of birdnames in Turkic linguistics; systematization of bird names in the Yakut and Altai languages; establishmentof the main lexico-semantic groups, methods of formation and structural models of composite ornithonyms.This study uses a set of methods: comparative, descriptive and quantitative methods. The scientific noveltyof the work consists in the fact that the issues of comparative analysis of composite words denoting thenames of birds in the Yakut and Altai languages were not the subject of special study. The theoretical andpractical significance of the work is that its materials can be used in the study of composite ornithonyms inother Turkic languages, as well as in the development of lecture courses, seminars on vocabulary.
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Connell, J. W., J. G. Smith, and P. M. Hergenrother. "Properties of Imide Oligomers Containing Pendent Phenylethynyl Groups." High Performance Polymers 9, no. 3 (September 1997): 309–21. http://dx.doi.org/10.1088/0954-0083/9/3/009.
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As part of a programme to develop high-performance/high-temperature structural resins for aeronautical applications, imide oligomers containing pendent phenylethynyl groups were prepared, characterized, thermally cured and the cured resins evaluated as films, mouldings, adhesives and composites matrices. Initially a diamine containing a pendent phenylethynyl group (3, 5-diamino-4′-phenylethynylbenzophenone) was prepared and characterized. This compound was used to make amide acid and subsequently imide oligomers containing pendent phenylethynyl groups. In order to control the distance between reactive sites, the concentration of pendent phenylethynyl groups was varied randomly along the oligomer backbone. The amide acid oligomers in N-methyl-2-pyrrolidinone were processed into thin films, adhesive tape, carbon fibre prepreg and also converted into imide powder. After initial screening work was performed on unoriented thin films, imidized powders and neat resin mouldings to assess glass transition temperature, mechanical properties (tensile properties and fracture toughness), melt flow behaviour and processability, one particular formulation was scaled up for more comprehensive evaluation. This imide oligomer containing pendent phenylethynyl groups was fabricated into adhesive and composite specimens under 1.4 MPa for1hat 350–371 °C. Excellent mechanical properties were obtained at room temperature and 177 °C. The properties of this material are compared with those of a material of similar composition and molecular weight containing only terminal phenylethynyl groups.
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Mirdarsoltany, Mohammadamin, Alireza Rahai, and Farzad Hatami. "Experimental Investigation on the Ductility of Concrete Deep Beams Reinforced with Basalt-Carbon and Basalt-Steel Wire Hybrid Composite Bars." Shock and Vibration 2021 (July 22, 2021): 1–8. http://dx.doi.org/10.1155/2021/6866993.
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Using steel bars in corrosive conditions imposes a high cost on concrete elements. This is due to corrosion of steel bars. In order to eliminate this issue, the use of composite materials in civil engineering practices has become an area of focus because of their acceptable mechanical behavior, such as high strength, suitable durability in corrosive environmental conditions, and low weight. However, composite bars show low ductility and brittle fracture in tensile tests. These weaknesses act as a stumbling block to the widespread use of such bars in concrete elements. Therefore, a new generation of hybrid composite bars, fabricated by a combination of two or more composite fibers, has been proposed to eliminate these downsides. In this research project, six reinforced concrete beams in three groups, including beams reinforced with basalt-wire hybrid composite bars, carbon-basalt hybrid composite bars, and steel bars, have been evaluated in statistical 4-point flexural tests. The test results showed that the energy absorption rate for beams reinforced with basalt-wire hybrid bars compared to beams reinforced with steel bars was up to 93% in the statistical 4-point flexural test.
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Pinho, Luis Gustavo Nunes Dias, Gustavo Helder Vinholi, Tulio Kalife Coelho, Dimas João Rodrigues Neto, Daiane Cerutti Kopplin, and Anísio Lima Silva. "Evaluation of the fracture resistance of remaining thin-walled roots restored with different post systems." Journal of Research in Dentistry 1, no. 3 (September 1, 2013): 184. http://dx.doi.org/10.19177/jrd.v1e32013184-191.
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The purpose of this work was evaluating the fracture strength of bovine roots weakened experimentally, restored with two different techniques: internal reinforcement of root canal walls with composite resin and a cast metal post and core or anatomic post (glass fiber post associated with composite resin). Thirty bovine lower central incisive were selected and transversally sectioned, remaining 14 mm of root in order to approximate to the human maxillary central incisive. A sequence of standardized wear was used to weak the root until the walls remaining achieved from 0.5 to 0.7 mm of thickness at the cervical edge. Two groups were separated randomly (n=15) in order to test the roots reinforced with composite resin associated with cast metal post and core (CMP), or roots restored with composite resin associated to the glass fiber post (GFP). The test were applied in a Universal Test Machine (EMIC) with tangential compressive loading focused on the lingual face of core in an angle of 135° with the long axis of the tooth at a crosshead speed of 0.5 mm/min until failure occurred. The results showed that the fracture strength of remaining roots with weakened walls was influenced by the restorative technique, and the higher values of strength fractures were observed in the group of roots reinforced by composite resin associated with CMP (p<0.001) when compared to the group of roots restored with anatomic post.
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Zhang, Shouhai, Shanshan Guan, Chengde Liu, Zhenlin Wang, Danhui Wang, and Xigao Jian. "Effect of Chemical Structure on the Performance of Sulfonated Poly(aryl ether sulfone) Composite Nanofiltration Membranes." Membranes 9, no. 1 (January 2, 2019): 6. http://dx.doi.org/10.3390/membranes9010006.
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This paper discusses the effect of the chemical structure of sulfonated poly(aryl ether sulfone) on the performance of composite nanofiltration membranes. The composite nanofiltration membranes were fabricated by coating sulfonated poly(aryl ether sulfone) solution onto the top surface of poly(phthalazinone ether sulfone ketone) support membranes. Three kinds of sulfonated poly(aryl ether sulfone)s with different amounts of phthalazinone moieties, namely, sulfonated poly(phthalazinone ether sulfone) (SPPES), sulfonated poly(phthalazinone biphenyl ether sulfone) (SPPBES), and sulfonated poly(phthalazinone hydroquinone ether sulfone)s (SPPHES), were used as coating materials. The solvents used in preparing the coating solution were investigated and optimized. The separation properties, thermal stability, and chlorine resistance of composite membranes were determined. The structures and morphologies of membranes were characterized with FTIR and SEM, respectively. The membrane prepared from SPPES with more phthalazinone moiety groups showed high water flux and salt rejection. The salt rejection of composite membranes followed the order SPPES > SPPHES > SPPBES. The rejection of the three composite membranes decreased slightly with the solution temperature rising from 20 to 90 °C, while the composite membrane with SPPES as the active layer showed a higher increase in flux than others. The results indicate that SPPES composite membranes show better thermal stability than others.
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De Goes, Mario Fernando, Marcelo Giannini, Vinícius Di Hipólito, Marcela Rocha de Oliveira Carrilho, Márcia Daronch, and Frederick Allen Rueggeberg. "Microtensile bond strength of adhesive systems to dentin with or without application of an intermediate flowable resin layer." Brazilian Dental Journal 19, no. 1 (2008): 51–56. http://dx.doi.org/10.1590/s0103-64402008000100009.
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This study evaluated the effect of flowable composite resin application on the microtensile bond strength (muTBS) of adhesive systems to dentin. Occlusal surfaces of human third molars were ground to obtain flat dentin surfaces. The crown of each tooth was sectioned occluso-gingivally into four quarters with a water-cooled diamond saw. One of the following adhesive systems was applied to dentin surface in each quarter of the same tooth, following manufacturers' instructions: Scotchbond Multipurpose, Single Bond Adper Prompt and Clearfil SE Bond. Experimental and control groups received the same treatment, except for the fact that a layer of flowable composite (Filtek Flow) was placed and light-cured on top of the adhesive layer in the specimens of the experimental groups. Resin composite (Filtek Z250) crown buildups were then made on the bonded surfaces and incrementally light-cured for 20 s. The restored teeth were stored in water at 37ºC for 24 h. Each tooth quarter was serially cut in a longitudinal direction in order to obtain several bonded sticks (0.9-mm² in cross-section). Maximal microtensile stress (in MPa) at failure was recorded using a universal testing machine. Data were analyzed by two-way ANOVA and Tukey's test at 5% significance level. Placement of a low-viscosity resin to the hybridized dentin increased the muTBS for all tested adhesive systems. However, such increase was significant only for Clearfil SE Bond (p<0.05). When the restorations were placed without low-viscosity resin, Clearfil SE Bond presented higher muTBS than Adper Prompt (p<0.05). For the groups treated with flowable composite, Clearfil SE Bond produced the highest muTBS means to dentin. In conclusion, the effect of the addition of an intermediate flowable composite layer on muTBS to dentin was material-dependent and resulted in an increased adhesion for all tested materials, though with significance only for Clearfil SE Bond.
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Zhao, Jindong, Hai Tang, Jiayang Wang, and Gang Li. "Local treatment of osteoporosis with alendronate-loaded calcium phosphate cement." Chinese Medical Journal 127, no. 22 (November 20, 2014): 3906–14. http://dx.doi.org/10.3760/cma.j.issn.0366-6999.20141670.
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Background A new treatment strategy is to target specific areas of the skeletal system that are prone to clinically significant osteoporotic fractures. We term this strategy as the “local treatment of osteoporosis”. The study was performed to investigate the effect of alendronate-loaded calcium phosphate cement (CPC) as a novel drug delivery system for local treatment of osteoorosis. Methods An in vitro study was performed using CPC fabricated with different concentrations of alendronate (ALE, 0, 2, 5, 10 weight percent (wt%)). The microstructure, setting time, infrared spectrum, biomechanics, drug release, and biocompatibility of the composite were measured in order to detect changes when mixing CPC with ALE. An in vivo study was also performed using 30 Sprague-Dawley rats randomly divided into six groups: normal, Sham (ovariectomized (OVX) + Sham), CPC with 2% ALE, 5%ALE, and 10% ALE groups. At 4 months after the implantation of the composite, animals were sacrificed and the caudal vertebrae (levels 4–7) were harvested for micro-CT examination and biomechanical testing. Results The setting time and strength of CPC was significantly faster and greater than the other groups. The ALE release was sustained over 21 days, and the composite showed good biocompatibility. In micro-CT analysis, compared with the Sham group, there was a significant increase with regard to volumetric bone mineral density (BMD) and trabecular number (Tb.N) in the treated groups (P <0.05). Trabecular spacing (Tb.Sp) showed a significant increase in the Sham group compared to other groups (P <0.01). However, trabecular thickness (Tb.Th) showed no significant difference among the groups. In biomechanical testing, the maximum compression strength and stiffness of trabecular bone in the Sham group were lower than those in the experimental groups. Conclusions The ALE-loaded CPC displayed satisfactory properties in vitro, which can reverse the OVX rat vertebral trabecular bone microarchitecture and biomechanical properties in vivo.
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Sun, Xu, Jin-Feng Cui, Xiu-Jie Jia, Chuan-Wei Zhang, Fang-Yi Li, Jian-Feng Li, Jian-Yong Li, Shuai Chen, Qi Xie, and Jie Xu. "Starch and Plant Fiber Reinforced Biodegradable Composites with Open Cell Structures." Journal of Biobased Materials and Bioenergy 13, no. 4 (August 1, 2019): 438–45. http://dx.doi.org/10.1166/jbmb.2019.1868.
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In order to figure out the effect of different starches on the properties of starch-based composites, new biodegradable composites with open cell structure were prepared through thermo-cavity foam molding using four different type starches (corn starch (CS), wheat starch (WS), potato starch (PS), and sweet potato starch (SPS)) and sisal fibers as main raw materials. Mechanical properties of the biodegradable composites were tested. The order of tensile and compressive strength of the composites was as follows: SPS-based composite > CS-based composite > PS-based composite > WS-based composite. Following X-ray diffraction, the infrared spectrum analysis, scanning electron microscopy, and viscosity test were employed to gain comprehensive views on the effect of the different starch microstructures on the properties of the biodegradable composites. X-ray diffraction analysis showed that the crystalline index of the SPS and CS were lower than those of PS and WS. Amorphous starch more easily combined with the sisal fiber, which is the deep reason that the SPS-based composite had the best tensile strength. Moreover, the infrared spectrum analysis indicated that SPS molecules demonstrated more hydroxyl groups than the others. The hydroxyl group in the SPS molecules formed more hydrogen bonds with the hydroxyl group in the sisal fibers. Scanning electron microscopy images showed that SPS bonded tightly with sisal fibers uniform open cell structure in the biodegradable composites. The order of the viscosities of the different starch slurry was: WS slurry > PS slurry > CS slurry > SPS slurry. The lower the crystalline index of the starch, the larger the amorphous zone, the lower the viscosity of the starch slurry, and the better the rheological properties are. In this case, the SPS and sisal fibers can combine well, and the SPS-based composites offer improved mechanical properties.
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Kim, Myeong Jin, Ki Ho Kim, Myeong Yeol Yoo, and Joo Heon Kim. "Fabrication of Homogeneously Dispersed Nanoneedle Manganese Dioxide/Graphene Composite for High-Performance Electrode Use in Supercapacitor." Advanced Materials Research 894 (February 2014): 8–12. http://dx.doi.org/10.4028/www.scientific.net/amr.894.8.
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Two types of graphene/MnO2 composites were synthesized by different reaction procedures. R-GO/MnO2 was synthesized as follows: first, nanoneedle MnO2 was formed on the GO sheets using various functional groups (GO/MnO2). In the second stage, GO/MnO2 was reduced to graphene/MnO2 (R-GO/MnO2) via the dipping method. rGO/MnO2 was synthesized using a different reaction order: first, graphene oxide was reduced to graphene and nanoneedle MnO2 was formed on graphene sheets. Characterization indicated that the nanoneedle MnO2 structures in the R-GO/MnO2 composite were homogeneously dispersed on graphene sheets, whereas MnO2 in the rGO/MnO2 composite formed aggregates due to absence of functional groups. The R-GO/MnO2 electrode exhibited a specific capacitance as high as 327.5 Fg-1at 10 mVs-1, which was higher than that of the rGO/MnO2 electrode (229.9 Fg-1). It is anticipated that the formation of nanoneedle MnO2 on the GO surface following the reduction procedure could be a promising fabrication method for supercapacitor electrodes.
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MAZROOEI SEBDANI, MARYAM, and MOHAMMADHOSSEIN FATHI. "EVALUATION OF HYDROXYAPATITE-FORSTERITE-BIOACTIVE GLASS COMPOSITE NANOPOWDER PREPARED VIA SOL-GEL METHOD." International Journal of Modern Physics: Conference Series 05 (January 2012): 510–18. http://dx.doi.org/10.1142/s2010194512002413.
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In spite of attractive bioactivity of bioactive ceramics i.e. hydroxyapatite and bioactive glasses, their poor mechanical properties have restricted their clinical applications. To overcome these limitations, an alternative approach suggested is preparation a composite including these bioactive ceramics with others. It is expected that a ceramic reinforcement with reduced grain size below 100 nm promotes theirs. The aim of this work was fabrication and characterization of hydroxyapatite-forsterite-bioglass composite nanopowder. Novel hydroxyapatite-forsterite-bioglass composite nanopowder was synthesized by incorporation of the forsterite and bioactive glass in hydroxyapatite matrix via a sol-gel process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infrared (FTIR) spectroscopy techniques were utilized in order to evaluate the phase composition, agglomerates size distribution, morphology and particle size and functional groups of synthesized. The effects of sintering temperature and time were also investigated. Results showed that the appropriate temperature for calcination was 600°C and the particle size of composite nanopowder was about 60-70nm. The decomposition of hydroxyapatite was increased with the increase of the sintering temperature and sintering time. Obtained results indicate that prepared composite nanopowder could be a good candidate for medical applications.