559 research outputs found

    Effects of drying methods of lamellas used in multilayer parquet manufacturing on surface roughness and bonding strength

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    The objective of this study is to determine surface roughness and bonding (tensile shear) strength of lamellas (top layer of multilayer parquet) which were cut away from green lumber and dried by different types of drying methods. Also, finding out the most convenient manufacturing method as surface roughness, bonding strength properties was aimed by comparing results with surface roughness and bonding strength of lamellas, which were cut away from dry lumber as seen in practice. Flat sawn green lamellas with 5 and 2 mm thicknesses, which were cut away from Iroko lumber by means of thin cutting frame saw, were dried with 3 different drying methods such as drying in lumber drying kiln, jet ventilated automatic veneer roller dryer and veneer press dryer. Effect of drying temperature on surface roughness and bonding strength was also determined by applying 3 different drying temperatures as 60, 100 and 140°C in jet ventilated automatic veneer roller dryer. In addition, lamellas with the same thicknesses were manufactured from dry lumber by means of the same thin cutting frame saw mentioned above. As the result of analysis of variance showed, differences between test groups were determined as surface roughness. Consequently, effect of drying method on surface roughness was found. Also, surface roughness values were determined to be increasing as drying temperature increases when drying in veneer roller dryer. Surface roughness values of lamellas dried in lumber drying kiln were found to be higher than those cut away from the dry lumber as expected. Differences exist between test groups as bonding strength was determined by means of analysis of variance. The biggest bonding strength was found in lamella group which were cut away from dry lumber and mentioned as comparison group. It was found that no relation existed between bonding strength and temperature increase drying in veneer roller dryer. Also, it was determined that no significant relation was found between surface roughness and bonding strength as the result of correlation analysis. Conclusively, it was found that lamella manufacturing method, cutting away from dry lumber, was the most convenient method for obtaining the best bonding strength in multilayer parquet production.Key words: Drying method, multilayer parquet, surface roughness, bonding strength

    Symmetry classification of third-order nonlinear evolution equations. Part I: Semi-simple algebras

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    We give a complete point-symmetry classification of all third-order evolution equations of the form ut=F(t,x,u,ux,uxx)uxxx+G(t,x,u,ux,uxx)u_t=F(t,x,u,u_x, u_{xx})u_{xxx}+G(t,x,u,u_x, u_{xx}) which admit semi-simple symmetry algebras and extensions of these semi-simple Lie algebras by solvable Lie algebras. The methods we employ are extensions and refinements of previous techniques which have been used in such classifications.Comment: 53 page

    Adhesive Fragment Reattachment after Orthodontic Extrusion: A Case Report

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    In the treatment of crown fractures, adhesive fragment reattachment provides a good alternative to other restorative techniques, offering several advantages. The present paper reports a case in which the treatment of a cervical crown fracture was accomplished by reattaching the tooth fragment with a flowable resin composite. Orthodontic root extrusion was performed with a modified Hawley appliance prior to fragment reattachment. The clinical and radiographic results after 2.5 years were successful

    Turkish Paediatric Dentists’ Knowledge, Experiences and Attitudes Regarding Child Physical Abuse

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    Objectives Numerous studies have shown that the education of health professionals is essential to effectively respond to child abuse. The present study aimed to evaluate Turkish paediatric dentists\u27 knowledge, experiences and attitudes regarding child physical abuse. Materials and methods An electronic questionnaire was e‐mailed to 518 paediatric dentists. Participants’ knowledge of diagnostic indicators of child physical abuse, and their past experiences, attitudes and self‐assessment of educational needs were evaluated. Results The response rate was 40.9% (n = 212). Participants who completed their undergraduate education before 1997 received significantly less education on child physical abuse than participants who completed their education more recently (P \u3c 0.001). Although statistically insignificant, participants who completed their doctorate/specialty training after 2012 received increased education on child physical abuse (P = 0.06). Of the participants, 43.9% suspected physical abuse; however, only 12.7% reported it. ‘I did not know where and how to report’ was the most common reason for not reporting physical abuse. The rate of suspicion was higher among dentists from state hospitals or oral health centres (P \u3c 0.05). Of the participants, 70.3% did not know about the legal sanctions for delay in or not reporting suspected cases. Only 15.6% assessed themselves as competent to diagnose and report physical abuse. Almost all of them acknowledged their need for more education on this topic. Conclusion Turkish paediatric dentists’ educational needs for diagnosing and reporting of child physical abuse cases should be met

    Nonlinear Evolution Equations Invariant Under Schroedinger Group in three-dimensional Space-time

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    A classification of all possible realizations of the Galilei, Galilei-similitude and Schroedinger Lie algebras in three-dimensional space-time in terms of vector fields under the action of the group of local diffeomorphisms of the space \R^3\times\C is presented. Using this result a variety of general second order evolution equations invariant under the corresponding groups are constructed and their physical significance are discussed

    Comprehensive analysis of RGU photometry in the direction to M5

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    The RGU-photographic investigation of an intermediate latitude field in the direction to the Galactic center is presented. 164 extra-galactic objects, identified by comparison of Minnesota and Basel charts, are excluded from the program. Also, a region with size 0.104 square-degrees, contaminated by cluster (M5) stars and affected by background light of the bright star HD 136202 is omitted. Contrary to previous investigations, a reddening of E(B−V)=0.046E(B-V)=0.046, corresponding to E(G-R)=0.07 mag is adopted. The separation of dwarfs and evolved stars is carried out by an empirical method, already applied in some of our works. A new calibration for the metallicity determination is used for dwarfs, while the absolute magnitude determination for stars of all categories is performed using the procedures given in the literature. There is good agreement between the observed logarithmic space density histograms and the galactic model gradients. Also, the local luminosity function agrees with Gliese's (1969) and Hipparcos' (Jahreiss & Wielen 1997) luminosity functions, for stars with 2<M(G)≀82<M(G)\leq8 mag. For giants, we obtained two different local space densities from comparison with two Galactic models, i.e. D∗(0)=6.63D^{*}(0)=6.63, close to that of Gliese (1969), and D∗(0)=6.79D^{*}(0)=6.79. A metallicity gradient, d[Fe/H]/dz=−0.20d[Fe/H]/dz= -0.20 dex/kpc, is detected for dwarfs (only) with absolute magnitudes 4<M(G)≀64<M(G)\leq6, corresponding to a spectral type interval F5-K0.Comment: 17 pages, including 13 figures and 3 tables, accepted for publication in PAS

    Symmetries and Lie algebra of the differential-difference Kadomstev-Petviashvili hierarchy

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    By introducing suitable non-isospectral flows we construct two sets of symmetries for the isospectral differential-difference Kadomstev-Petviashvili hierarchy. The symmetries form an infinite dimensional Lie algebra.Comment: 9 page

    The effect of carob (Ceratonia siliqua) bean extract on male New Zealand White rabbit semen

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    [EN] The carob tree (Ceratonia siliqua) grows naturally in the Mediterranean region. The empiric use of carob cures for their aphrodisiac properties is very common in Turkey. Thus, the experiment was conducted to determine the effects of carob bean extracts on some reproductive parameters in male New Zealand White rabbits. During the adaptation period (stage 1), 6-8 mo old rabbits were trained in semen collection for 30 d. At the beginning of the treatment period (stage 2), rabbits were assigned randomly to 2 groups of 8 animals each. For a period of 49 d (1 spermatogenesis duration), one group was treated with a daily oral dose (10 mL) of carob extract and the other group received the corresponding volume of tap water. Semen was collected weekly. Semen samples taken at week 1 and 7 were analysed separately. At the beginning of stage 2, no differences were observed in the volume and pH of the ejaculate, sperm concentration, percentage of motility, percentage of live spermatozoa, percentage of sperm plasma membrane integrity, plasma concentration of testosterone, and seminal plasma protein levels between the control and carob extract treated animals. Similarly, at the end of stage 2, there were no differences in the volume and pH of the ejaculate, motility percentage, the percentage of live spermatozoa, percentage of sperm plasma membrane integrity, and the seminal plasma protein levels between the control and the carob extract treated animals. However, sperm concentration (P<0.05), plasma concentration of testosterone (P<0.05), and percentage of change in spermatozoa concentration (P<0.02) between groups were affected at the end of stage 2. The data suggested that the use of carob cures prepared by boiling carob fruit could have beneficial influences on sperm concentration in rabbits.Ata, A.; Yildiz-Gulay, O.; GĂŒngör, S.; Balic, A.; Gulay, M. (2018). The effect of carob (Ceratonia siliqua) bean extract on male New Zealand White rabbit semen. World Rabbit Science. 26(3):209-215. doi:10.4995/wrs.2018.10154SWORD209215263Abd El-Ghany M.A. 2007. The relation of antioxidants and sodium nitrite on the oxidation reduction system and reproductive ability of male rats. Egypt J. Nutr., 2: 33-64.Agnes V.F., Akbarsha M.A. 2003. Spermatotoxic effect of aflatoxin B1 in the albino Mouse. Food. Chem. Tox., 41: 119-130. https://doi.org/10.1016/S0278-6915(02)00171-0Amico F.P., Source E.G. 1997. Medical plants and phytotheraphy in Mussomeli area (Caltenisseta, Scily, Italy). Fitoterapia, 68: 143-159.Ata A., Hatipoglu F.S., Yildiz-Gulay O., Gulay M.S. 2007. Protective role of ascorbic acid on subacute sperm toxicity in male New Zealand White Rabbits treated with endosulfan. Drug Chem. Toxicol., 30: 181-195. https://doi.org/10.1080/01480540701374896Ayaz F.A., Torun H., Ayaz S., Correia P.J., Alaiz M., Sanz C., Gruz J., Strand M. 2007. Determination of chemical composition of Anatolian carob pod (Ceratonia siliqua L.), Sugars, amino and organic acids, minerals and phenolic compounds. J. Food Quality, 30: 1040-1055. https://doi.org/10.1111/j.1745-4557.2007.00176.xFeng P., Li TL., Guan Z.X., Franklin R.B., Costello L.C. 2002. Direct effect of zinc on mitochondrial apoptogenesis in prostate cells. Prostate, 52: 311-318. https://doi.org/10.1002/pros.10128Hala M.A.W. 2011. Protective effect of Nigella sativa, linseed and celery oil against testicular toxicity induced by sodium valproate in male rats. J. Am. Sci., 7: 687-693.Inouce M., Suzuki R., Koide T., Sakaguchi N., Ogihera Y., Yabu Y. 1994. Antioxidant, gallic acid, induces apaptosis in HL- 60RG cells. Biochem. Res. Commun., 204: 898-904. https://doi.org/10.1006/bbrc.1994.2544Karkacier M., Artik N. 1995. Determination of physical properties, chemical composition and extraction conditions of carob bean (Ceratonia siliqua L.). Gida, 20: 131-136.Katsiya G.V., Todua T.N., Gorlushkin V.M., Chirkov A.M., Goncharov N.P. 1989. Effect of immobilization stress on the gonadotropic function of the hypophysis in male hamadryas baboons (Papio hamadryas). Biol. Medit., 107: 231-234.Marakis S. 1996. Carob bean in food and feed: current status and future potentials: a critical appraisal. J. Food Sci. Technol., 33: 365-383.Merzouki A., Ed-Derfoufi F., El Allau A., Molero-Mesas J. 1997. Wild medicinal plants used by local Bouhmed population (Morocco). Fitoterapia, 68: 444-460.Rickard I.J., Holopainen J., Helama S., Helle S., Russell A.F., Lummaa V. 2010. Food availability at birth limited reproductive success in historical humans. 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Antihyaluronidase action of ellagic acid effectively prevents polyspermy as a result of suppression of the acrosome reaction induced by sperm-zona interaction during in vitro fertilization of porcine oocytes. J. Reprod. Develop., 53: 755-764. https://doi.org/10.1262/jrd.18173Turk G., Sonmez M., Aydin M., Yuce A., Gur S., Yuksel M., Aksu E.H., Aksoy H. 2008. Effects of pomegranate juice consumption on sperm quality, spermatogenic cell density, antioxidant activity and testosterone level in male rats. Clin. Nutr., 27: 289-296. https://doi.org/10.1016/j.clnu.2007.12.006WĂŒrsch P. 1979. Influence of tannin-rich carob pod fiber on the cholesterol metabolism in the rat. J. Nutr., 109: 685-692. https://doi.org/10.1093/jn/109.4.685Zago M.P., Oteiza P.I. 2001. The antioxidant properties of zinc: interactions with iron and antioxidants. Free Rad. Biol. Med., 31: 266-274. https://doi.org/10.1016/S0891-5849(01)00583-

    Primary Molar Pulpotomies with Different Hemorrhage Control Agents and Base Materials: A Randomized Clinical Trial

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    Objective: To evaluate the clinical and radiographical success of primary molar pulpotomies which used 15.5% ferric sulfate (FS) or 1.25% sodium hypochlorite (NaOCl) for hemostasis and zinc oxide-eugenol (ZOE) and calcium hydroxide (CH) pastes as base materials. Methods: In 29 healthy children, 80 primary molars were randomly allocated to one of the study groups: Group 1: FS-ZOE, Group 2: FS-CH, Group 3: NaOCl-ZOE, and Group 4: NaOCl-CH. After hemostasis with the respective solutions, pulp stumps and floor of the pulp chambers were covered with either ZOE or CH pastes. All teeth were restored with stainless steel crowns. Follow-up examinations were carried out at 1, 3, 6, and 12 months. Results: One tooth in Group 1 and two teeth in Group 4 were extracted because of pain and periapial pathosis at sixth month. After 12 months, clinical success rates of pulpotomies in Groups 1-4 were 95%, 100%, 100%, and 89.5%, respectively. The differences were not significant (P = 0.548). Radiographic success rates for Groups 1-4 were 80%, 88.9%, 78.9%, and 84.2%, respectively. No statistically significant difference was found (P = 0.968). Pain on percussion was the most observed clinical finding. However, internal root resorption was the most common radiological finding and it was observed significantly more in mandibular primary molars (P \u3c 0.05). Conclusion: Both ZOE and CH can be preferred as base materials after hemostasis achieved by the use of 15.5% FS or 1.25% NaOCl in primary tooth pulpotomy

    Group-invariant solutions of a nonlinear acoustics model

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    Based on a recent classification of subalgebras of the symmetry algebra of the Zabolotskaya-Khokhlov equation, all similarity reductions of this equation into ordinary differential equations are obtained. Large classes of group-invariant solutions of the equation are also determined, and some properties of the reduced equations and exact solutions are discussed.Comment: 14 page
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