Shear strength in friction welded joint of poplar wood impregnated with copper-based wood preservative

Environmentally friendly processes are of great interest and considerably needed due to the worldwide problem of pollution. Linear vibration welding of timber structural elements provides new opportunities to potentially achieve structural joints. Mechanically induced vibrational wood fusion welding is shown to be due mostly to the melting and flowing of some amorphous, cells-interconnecting polymer material in the structure of wood, mainly lignin, but also hemicelluloses. In this study, poplar (Populus euramericana) samples were impregnated with alkaline copper quat (ACQ) in order to enhance welding performance. Chemical changes of the impregnated and welded specimens were characterized by FT-IR techniques. A decrease in the proportion of unoxidized phenolic groups in the lignin were observed by FT-IR and the decreased joint strength observed is impregnated wood. After impregnation, shear strength decreased by 37 % to 54 %. The X-ray CT-scanning results revealed that the average density of the poplar wood (368 kg/m3) increased to 710 kg/m3 by welding

Primjena metode konačnih elemenata za modeliranje drvno-plastičnih kompozita ojačanih vlaknima za uporabu u konstrukciji namještaja s polukrutim vezovi

In this study, control samples of pine (Pinus slyvestris L.), beech (Fagus orientalis L.) and oak (Quercus petreae L.) species were obtained by using fi ber reinforced finger corner joints. Teknobont 200 epoxy and polyvinyl (PVAc) adhesives were used as glue. Bearing in mind the critical loads that may affect their use, experimental samples were tested under diagonal loads. Experimental samples were also analyzed by a computer program using the finite element method (FEM). Finally, experimental data were compared with the results of FEM. The comparisons clearly showed that experimental results and finite element solutions (SAP2000 V17) including semi-rigid connections are in good agreement. As a structural analysis program in furniture engineering designs, FEM can be preferred in terms of reliability and cost.U radu se prikazuju rezultati istraživanja uzoraka borovine (Pinus slyvestris L.), bukovine (Fagus orientalis L.) i hrastovine (Quercus petreae L.) spojenih kutnim zupčastim spojevima i ojačanih vlaknima. Kao ljepilo upotrijebljeno je epoksidno ljepilo Teknobont 200 i polivinilacetatno ljepilo (PVAc). Imajući na umu opterećenja koja se pojavljuju tijekom uporabe, eksperimentalni su uzorci ispitivani pri dijagonalnim opterećenjima. Uzorci su također analizirani računalnim programom primjenom metode konačnih elemenata (FEM). Eksperimentalni podatci i podatci dobiveni FEM analizom uspoređeni su te se jasno može vidjeti da se ti podatci za polukrute vezove podudaraju. Glede pouzdanosti i troškova, kao strukturnom programu analize u dizajniranju namještaja prednost se može dati FEM analizi

Analiza kompozita od kopolimera stirena i anhidrida maleinske kiseline (SMA) punjenih pregrijanim drvom metodom konačnih elemenata

The computer aided three dimensional static analyses of the specimens was done by using the Finite Element Method (FEM) and obtained data was compared with actual test data. The aim of this study is to compare the deformation/stress analyses with FEM analysis results of styrene maleic anhydride (SMA) copolymer composites. The heat treated wood/SMA copolymer composites were produced from different loadings (from 10 to 30 wt. %) of heat treated and untreated eastern white pine wood flours (Pinus strobus L.). All formulations of wood flour/SMA copolymer composites were produced by melt compounding through injection molding. The deformation/stress results obtained from the experimental solutions are very close to the results obtained from the numerical solutions (SAP2000 V17). As a result, it can be said that it is beneficial to use the FEM in the engineering design approach after the data obtained by the experimental solutions as meaningful values after application of the FEM.Računalom potpomognuta trodimenzionalna statička analiza uzoraka provedena je metodom konačnih elemenata (FEM). Dobiveni su podatci uspoređeni sa stvarnim ispitnim podatcima. Cilj rada bio je usporediti analizu deformacija/naprezanja s rezultatima FEM analize kompozita od kopolimera stirena i anhidrida maleinske kiseline (SMA). Kompoziti od pregrijanog drva i SMA kopolimera bili su izrađeni s različitim udjelom (od 10 do 30 % težine) drvnog brašna od pregrijanoga i nepregrijanog drva američkog borovca (Pinus strobus L.). Sve formulacije kompozita od drvnog brašna i SMA kopolimera bile su izrađene injekcijskim prešanjem. Rezultati deformacija i naprezanja dobiveni eksperimentalno vrlo su slični rezultatima dobivenim računskim putem (SAP200 V17). Može se zaključiti da je analiza metodom konačnih elementa, kombinirana s eksperimentalno dobivenim podatcima, korisna u inženjerskom projektiranju

Savojna svojstva lameliranog drva izrađenoga od topolovine i GFRP-a

In this study, 4 layers of 5 mm thick slats obtained by sawing method from poplar wood were used. Plain woven GRFP with low density and grammage of 100 g/m2 (Type 1) and plain woven GRFP with high density and grammage of 200 g/m2 (Type 2) were placed and glued between each layer. Polyvinyl acetate (PVAc-D4), Polyurethane (PU) and dual-component Epoxy (L285-resin and H285-hardener) adhesives were used for gluing the layers. Strength values (bending and modulus of elasticity) between the obtained layers were investigated. As a result of the study, it was determined that epoxy glue has higher strength than polyurethane and polyvinyl acetate glues; Type 2 plain woven fabric has higher strength than Type 1 plain woven fabric; and parallel load to the glue line results in higher performance than perpendicular load to the glue line.U radu se prikazuje istraživanje lameliranog drva izrađenoga od piljenjem proizvedenih topolovih platica debljine 5 mm složenih u četiri sloja. Između svakog sloja zalijepljena je plošno tkana GRFP tkanina male gustoće i površinske mase 100 g/m2 (tip 1) i plošno tkana GRFP tkanina velike gustoće i površinske mase 200 g/m2 (tip 2). Za lijepljenje drva i tkanine upotrijebljena su ova ljepila: polivinilacetatno (PVAc-D4), poliuretansko (PU) i dvokomponentno epoksidno (L285-mola i H285-otvrdnjivač). Istražene su vrijednosti čvrstoće (savijanje i modul elastičnosti) te je utvrđeno da epoksidno ljepilo ima veću čvrstoću nego poliuretansko i polivinilacetatno ljepilo. Nadalje, tkanina tipa 2 ima veću čvrstoću od tkanine tipa 1, a djelovanjem sile paralelno sa sljubnicom dobivena su bolja svojstva nego pri djelovanju sile okomito na sljubnicu

Triboelektrična i hidrofobna svojstva funkcionaliziranih lignoceluloznih materijala

In the development of sustainable products, lignocellulosic materials with hydrophobic properties can be functionalized and used as reinforcement, especially in bio-composite materials, as well as in various applications such as packaging, water-repellent and self-renewing materials. This study is aimed to improve the surface properties and triboelectric properties of wood materials. Functionalized wood veneers were prepared by impregnating 3 different wood veneers (beech, mahogany and oak) with 5 different chemical solutions (cationic cellulose, cationic starch, polyethyleneimine, sodium alginate and carboxymethyl cellulose). Structural characterization of the functional wood materials obtained was investigated by Fourier-transform infrared spectroscopy (FT-IR) technique, wettability and surface properties were examined by contact angle measurements, and morphological properties were examined by scanning electron microscopy (SEM). The triboelectric properties of the devices prepared using functionalized wood materials were investigated. As a result, it was determined that the hydrophobic properties of wood materials were improved and showed triboelectric properties. It demonstrates that functionalized wood materials can be used to power low-power electronic devices.U razvoju održivih proizvoda lignocelulozni materijali hidrofobnih svojstava mogu se funkcionalizirati i upotrebljavati kao ojačivači u biokompozitnim materijalima ili mogu imati različitu primjenu u ambalaži te u vodoodbojnim i samoobnavljajućim materijalima. Cilj ovog istraživanja bio je pronaći način poboljšanja površinskih i triboelektričnih svojstava drvnih materijala. Za istraživanje je pripremljen funkcionalizirani furnir od tri različite vrste drva (bukovine, mahagonija i hrastovine), impregniran s pet različitih kemijskih otopina (kationskom celulozom, kationskim škrobom, polietileniminom, natrijevim alginatom i karboksimetilcelulozom). Karakterizacija strukture dobivenih funkcionaliziranih drvnih materijala provedena je Furierovom infracrvenom spektroskopijom (FT-IR), kvašenje i svojstva površine istražena su mjerenjem kontaktnog kuta, a morfološka svojstva ispitana su skenirajućim elektronskim mikroskopom (SEM). Nadalje, istražena su triboelektrična svojstva uređaja izrađenih od funkcionaliziranih drvnih materijala. Utvrđeno je da se funkcionalizirani drvni materijali mogu primijeniti za napajanje uređaja male snage

Graphene-based hybrid for enantioselective sensing applications

Chirality is a major field of research of chemical biology and is essential in pharmacology. Accordingly, approaches for distinguishing between different chiral forms of a compound are of great interest. We report on an efficient and generic enantioselective sensor that is achieved by coupling reduced graphene oxide with γ-cyclodextrin (rGO/γ-CD). The enantioselective sensing capability of the resulting structure was operated in both electrical and optical mode for of tryptophan enantiomers (D-/L-Trp). In this sense, voltammetric and photoluminescence measurements were conducted and the experimental results were compared to molecular docking method. We gain insight into the occurring recognition mechanism with selectivity toward D- and L-Trp as shown in voltammetric, photoluminescence and molecular docking responses. As an enantioselective solid phase on an electrochemical transducer, thanks to the different dimensional interaction of enantiomers with hybrid material, a discrepancy occurs in the Gibbs free energy leading to a difference in oxidation peak potential as observed in electrochemical measurements. The optical sensing principle is based on the energy transfer phenomenon that occurs between photoexcited D-/L-Trp enantiomers and rGO/γ-CD giving rise to an enantioselective photoluminescence quenching due to the tendency of chiral enantiomers to form complexes with γ-CD in different molecular orientations as demonstrated by molecular docking studies. The approach, which is the first demonstration of applicability of molecular docking to show both enantioselective electrochemical and photoluminescence quenching capabilities of a graphene-related hybrid material, is truly new and may have broad interest in combination of experimental and computational methods for enantiosensing of chiral molecules

Adult posterior urethral valve: a case report

Introduction: Posterior urethral valve (PUV) is a congenital obstructive defect of the male urethra with an incidence of 1/8,000 to 1/25,000 live births. PUV is the most common cause of lower urinary tract obstruction in neonates. The diagnosis of PUV is usually made early, and PUV cases have rarely been detected in adults

Characterization of heat treated wood filled stryene maleic anhdride (SMA) composite Yazar:MUSTAFA ZOR

Tez, 24.01.2019 tarihine kadar yazarı tarafından kısıtlanmıştırBu çalışmada; köpüklendirilmiş strien maleik anhidrit (SMA) polimerine belirli oranlarda ısıl işlem uygulanmış veymut çamı (Pinus strobus) (%10, %20, %30, %40 ve %50) katılarak çift vidalı ektrüzyon sayesinde mühendislik malzemesi olan odun unu destekli SMA ko-polimer kompozit malzemesi elde edilmiştir. Belirli oranlarda hazırlanan bu kompozitte ısıl işlemli odun unu destekli SMA kompozitlerinde karışım oranı ve malzeme karakterizasyon analizleri yapılarak deformasyon sonuçları elde edilmiştir. Deneysel verilerin karşılaştırılmasında sonlu elemanlar metodu (FEM) kullanılarak deformasyon sonuçları karşılaştırılmıştır. Isıl işlem uygulamasının kompozitlerde yoğunluk testi üzerine sonuçlarına göre, odun unu dolgu oranı artmasıyla gruplar arasında ciddi bir fark görülmemiştir. Boyutsal kararlılık analizi sonucuna göre, ısıl işlem uygulanmış odun unu destekli SMA kompozitleri, ısıl işlem uygulanmamış odun unu destekli SMA kompozitlerine göre daha az boyutsal değişim göstermiştir. Hızlandırılmış yaşlandırma testi analizine göre, ısıl işlem dolgu oranı arttıkça malzemede renk değişimi farkı ciddi oranda fazlalaşmaktadır. Bu yüzden %10 dolgu oranındaki malzemeler en az renk değişmi sonucunu göstermiştir. Kompozitlerin mekanik test sonuçlarına göre, ısıl işlem uygulanmış odun unu destekli SMA kompozitlerinde hem eğilmede hem de çekme direncinin her ikisinde en iyi değeri %30 dolgu oranındaki TP grubu göstermiştir. TGA sonuçlarına göre, ısıl işlem uygulanmış odun unu destekli SMA kompozitlerinin, ısıl işlem uygulanmamış SMA kompozitlerine göre daha ısıl kararlılığa sahip olduğu görülmüştür. Morfolojik analiz sonuçlarına göre, tüm gruplarda, ısıl işlem uygulanmış odun unu ile SMA polimeri arasında zayıf etkileşimler görülmektedir. Reolojik analiz sonuçlarına göre, kompozitlerin dinamik vizkositesi düşük frekansta önemli bir artış göstermektedir. Sonlu elemanlar metodu deformasyon analizi sonucuna göre, deneysel çözümlerinden elde edilen sonuçların, sayısal çözümlerden (SAP2000) elde edilen sonuçlara oldukça yakın olduğu görülmektedir. Sonuç olarak, deneysel bulgular ile elde edilen verilerin, sonlu elemanlar yönteminin uygulanmasından sonra anlamlı değerler elde edilmiş olup, sonlu elemanlar metodunun mühendislik tasarımı yaklaşımında kullanılmasının faydalı olacağı söylenebilir.In this study, wood fıller SMA copolymer, engineering material, has been obtained through twin screw extruder adding the specific rate heat treated pine wood (10%, 20%, 30%, 40%, and 50%) to foamed SMA polymer. Deformation results have been achieved by analyzing of the mixing rate and the material characterization in heat treated wood-SMA composites prepared in specific rates. In comparasion of the experimental results, deformation results were compared with finite element method (FEM). According to density results, there is no significant diffence between the groups as a result of increasing wood filler rate. According to dimensional stability results, heat treated wood SMA composites have less dimensional changes than wood SMA composites. According to the accelerated weathering test results, colour changes developed when heat-treated filler rate is increased in this material. So, materials in 10% filler rate show minumum colour changes. According to the mechanical test results, TP group in 30% filler rate has the best results both in the flexural and the tensile strength. According to the TGA results, heat- treated wood SMA composites have more thermal stabile than wood SMA composites. According to the morpholojical results, it has been indicated a weak interaction between the heat-treated wood and SMA polymer among all groups. According to the reological analysis, the dynamic viscosity of composites has showed a significant increase at low frequencies. According to the deformation analysis result of FEM, it can be seen that the results obtained from the experimental solution are very close to the results obtained from the numerical solutions. As a result, it can be said that it is beneficial to use the FEM in the engineering design approach after the data obtained by the experimental solutions obtained meaningful values after application of the FEM

Utilization of heat treated wooden material in the production of garden sitting furniture with the aid of engineering design principles

Bu çalışmada; karaçam (Pinus nigra L.), sarıçam (Pinus slyvestris L.), doğu ladini (Picea orientalis L.), ırocco (Choropher excelsa) ve dişbudak (Fraxinus excelsior L.) odunlarından hazırlanan T-tipi lamba zıvana ayak-kayıt birleştirmelerinin mekanik performansları üzerine, ağaç türü, birleştirme tipi ve ısıl işlem muamelesinin etkileri araştırılmıştır. 5 ağaç türü x 2 birleştirme tipi (açık zıvana ve kör zıvana) x 2 ısıl işlem özelliği x 2 yükleme tipi (eğilme direnci ve çekme direnci) x 6 tekerrür olmak üzere toplam 240 adet T-tipi birleştirme örnekleri hazırlanmıştır. Eğilme deneyi sonuçlarına göre; ısıl işlem uygulanmış örneklerde iğne yapraklı ağaç türlerinden Sarıçam türü açık zıvanalı birleştirmeleri, yapraklı ağaç türlerinden Irocco türü kör zıvanalı birleştirmeleri yüksek eğilme direnci değerleri göstermiştir. Birleştirme yerindeki sertlik değerinde, en yüksek performansı Karaçam türü kör zıvanalı birleştirme ile Sarıçam türü açık zıvanalı birleştirme göstermiştir. Birleştirme yeri rijitlik analizinde, en yüksek performansı Karaçam türü kör zıvanalı birleştirme göstermiştir. Çekme deneyi sonuçlarına göre, ısıl işlem uygulanmış örneklerde iğne yapraklı ağaç türlerinden Karaçam türü kör zıvanalı birleştirmeleri, yapraklı ağaç türlerinden Irocco türü açık zıvanalı birleştirmeleri yüksek çekme direnci değerleri göstermiştir. Sonuç olarak, ısıl işlem uygulanmış bahçe oturma mobilya konstrüksiyonlarında kullanılacak olan ağaç malzemelerin mekanik performansları açısından hem eğilme hem de çekme direnci etkileşimleri incelendiğinde, ağaç türü, birleştirme tipi ve ısıl işlemin T-tipi lamba zıvana ayak-kayıt birleştirmelerinin üzerinde etkili olduğu bulunmuştur. Genel olarak bakıldığında, üretilecek olan bahçe oturma mobilya konstrüksiyonlarında, karaçam türü kör zıvanalı birleştirmeler kullanıma daha uygun görülmektedir.In this study, the effect of heat-treatment, wood and joint type on mechanical performance of T-type mortise and tenon post-rail joints prepared using Black pine (Pinus nigra L.), Scotch pine (Pinus slyvestris L.), Oriental Spruce (Picea orientalis L.), Iroko (Choropher excelsa) and Ash (Fraxinus excelsior L.) was investigated. Total of 240 T-type joint specimens including 5 wood material x 2 joint types (mortise-tenon and blind mortise-tenon) x 2 heat-treatment properties x 2 test types (bending strength and tension strength) x 6 replicates were prepared. According to bending strength results, the maximum bending strength was found in Iroko (hardwood) for blind mortise and tenon joints and Scotch pine (softwood) for mortise and tenon joints. In terms of joint stiffness, the maximum performance in joint stiffness was determined for Black pine for blind mortise and tenon joints and Scotch pine (softwood) for mortise and tenon joints. In analyzes of joint rigidity, the maximum performance was found in Black pine for blind mortise and tenon joints. The results of tension test showed that the maximum value of tension strength was obtained in Black pine (softwood) for blind mortise and tenon joints and Iroko (hardwood) for mortise and tenon joints. Mechanical performance of heat-treated wood material used to produce garden sitting furniture in terms of both tension and bending interactions were investigated. It was found that heat-treatment, wood and joint type had a significant effect on T-type mortise and tenon post-rail joints. In general, for garden sitting furniture constructions to be produced with heat-treated Black pine was found to be suitable using with blind mortise and tenon joints

Grice'ın işbirliği ilkesi ve onun alt ilkelerinin Türkçe ve İngilizce akademik yazılardaki bağdaşıklık sorunlarının incelenmesinde kullanılması.

Coherence in written discourse has been a problematic concept for many English Language Teachers when teaching to write in English. It is considered as a crucial part of academic written discourse, which students are expected to master to be able to pursue their academic studies. This study aims to examine how much the coherence-related difficulties/problems of Turkish EFL students in writing English essays are related to writing Turkish essays. The subjects for this study were chosen from the upper-intermediate level students at the Preparatory Program of Istanbul Bilgi University. For a detailed understanding of the nature of the coherence-related difficulties/problems of students’ Turkish and English essays, this study suggests a pragmatic analysis, involving the use of Grice’s Cooperative Principle and maxims and sub-maxims of Cooperation. This study was conducted in the middle of 2005-2006 Academic Year with the participation of 20 students who were chosen randomly. Each student was asked to write an essay in English on a given topic from their weekly program. Threeweeks later, the same students were asked to write essays on the same topic in Turkish. Thus, 20 English essays and 20 Turkish essays (i.e., Total 40 essays) were collected as data for this study. The essays were rated for coherence by three different raters. All English essays were analyzed by one monolingual Americanrater and one bilingual (Turkish and English) rater. Similarly, all Turkish essays were analyzed by one monolingual Turkish rater and the same bilingual (Turkish and English) rater. The coherence ratings showed that there is a positive significant correlation between the coherence judgments of monolingual raters and the bilingual rater, which means that both monolingual raters and the bilingual rater agree on the similar coherence judgments. Next, the essays were analyzed in light of the Gricean Maxims to find the violations of each maxim in each essay by the researcher. In the comparison of maxim violations and the coherence judgments of the raters, the maxim of Relation was found to be the most significant maxim that affected the coherence judgments of the raters both for Turkish and English essays. In addition, Manner maxim was significant for Turkish essays and Quantity maxim was significant for English essays. However, in the comparison of the violation of individual maxims in Turkish and English essays, the violation of Relation maxim in English essays was found to correlate with the violation of Relation, Quality and Quantity maxims in Turkish essays. Similarly, violation of Manner maxim in English essays was also found to correlate with the violation of Quantity and Relation maxims. On the other hand, the violation of Manner maxim in Turkish essays was found to correlate with the violation of Quantity maxim in English essays. In conclusion, by looking at these relationships between Turkish essays and English essays, it may be argued that students may have inadequacies in writing skills or may lack some writing skills in Turkish, which may cause inadequacies in English academic writing skills. However, this study suggests the same study be replicated in different contexts and with larger sample sizes, similar research studies be conducted in Turkish writing instruction in the contexts of Turkish Secondary Education, and further studies be conducted on the effect of Relation and Manner maxims on other maxims.M.A. - Master of Art