Instaliranje opreme i mjernih postupaka pri određivanju hidrauličke vodljivosti jelovine

For a hydraulic conductor, through which liquid flows, hydraulic conductance (K, ml·s-1·MPa-1) is defined as the ratio of pressure difference at the inlet and outlet to the fluid amount passing through the hydraulic conductor in a unit time period. This property is one of the key functions of the wood, and is obtained by the flow rate (F – Flow, ml·s-1) along the wood sample divided by the pressure difference driving the flow (DP, MPa). This study aimed to establish a test setup to determine the hydraulic conductance values of Uludağ Fir (Abies bornmulleriana Mattf.). A test setup was established to measure the amount of water that flows in samples and pressure difference in characterized capillary tubes. In addition, calibration of the test apparatus is explained in detail. Fir wood samples taken from Yedigoller, which is affiliated to Kale Operation Chieftainship and Bolu Forest Regional Directorate, of 4 mm in diameter and 3 cm in length were prepared and hydraulic conductance measurements were performed, and the results are presented in this article. The installed test setup was used to obtain the following information about trees: operation of the hydraulic conduction system, the amount of needed water, seasonal effects and stress-related changes.Hidraulička vodljivost (K, ml·s-1·MPa-1) definira se kao omjer količine tekućine koja prolazi u određenom vremenu hidrauličkim vodičem i razlike tlaka na ulazu i izlazu vodiča. To je svojstvo jedna od ključnih funkcija drva, a njegova se veličina određuje mjerenjem brzine protoka (F – protok, ml·s-1) uzduž uzorka drva zbog razlika tlakova (DP, MPa). Cilj ovog istraživanja bio je instaliranje mjernog sustava za određivanje hidrauličke vodljivosti jelovine (Abies bornmulleriana Mattf.). Postavkama mjerenja utvrđena je količina vode koja teče u uzorcima jelovine i razlika tlaka u karakterističnim kapilarama. Usto je detaljno objašnjeno kalibriranje ispitne opreme. Uzorci jelovine na kojima su provedena mjerenja hidrauličke vodljivosti bili su promjera 4 mm i duljine 3 cm i uzeti su s područja Yedigoller, a rezultati ispitivanja prikazani su u ovom radu. Instaliranim mjernim sustavom dobivene su ove informacije o stablima: djelovanje sustava hidrauličke vodljivosti u drvu, količina potrebne vode, utjecaji godišnjih doba i promjene povezane sa stresom

CHANGES IN THE CHEMICAL STRUCTURE OF THERMALLY TREATED WOOD

Changes in the chemical structure of hornbeam and uludag fir woods during thermal treatment were investigated at three temperatures (170, 190, and 210 oC) and three durations (4, 8, and 12 hours). After thermal treatment, the extents of degradation in the chemical structure of the samples were determined, and the effects on the chemical composition of hornbeam wood and uludag fir wood were investigated. The data obtained were analyzed using variance analysis, and Tukey’s test was used to determine the changes in the chemical structure of uludag fir and hornbeam woods. The results showed that heating wood permanently changes several of its chemical structures and that the changes are mainly caused by thermal degradation of wood polymers. It was found that decreasing of the cellulose and holocelluloses ratio had a favorable effect on the interaction of the wood with moisture. According to the obtained results, hornbeam wood is affected more than uludag fir wood. For each wood, the maximum decreases of holocellulose and α-cellulose were found at 210oC for 12 hours, and the maximum increase of lignin occurred at the same treatment combination

The density, compression strength and surface hardness of heat treated hornbeam (Carpinus betulus ) wood

The heat treatment of wood is an environment-friendly method for wood preservation. The heat treatment process only uses steam and heat, and no chemicals or agents are applied to the material during the process. Tests have shown no harmful emissions are apparent when working with the ma-terial. This process improves wood’s resistance to decay and its dimensional stability. In this study, the density, compression strength and hardness of heat treated hornbeam (Carpinus betulus L.) wood were investigated. Wood specimens that had been conditioned at 65% relative humidity and 20 ºC were subjected to heat treatment at 170, 190, and 210 ºC for 4, 8, and 12 hrs. After heat treatment, compression strength and hardness were determined according to TS 2595 and TS 2479. The results showed that the decreases of compression strength and hardness were related to the extent of density loss. Both compression strength and hardness decreased with the increasing temperatures and durations of the heat treatment. While the maximum density loss observed was 16.12% at 210 ºC and 12 hour, at these heat-treatment conditions, the compression strength approximately decreased 30% and hardness values in tangential, radial, and longitudinal directions approximately decreased by 55%, 54%, and 38%, respectively. Hence, it was concluded that there might be a relationship between changes of these wood properties.

CT Findings of Patients with Small Bowel Obstruction due to Bezoar: A Descriptive Study

Purpose. The aim of this study was to present the computed tomography (CT) findings of bezoars that cause obstruction in the small bowel and to emphasize that some CT findings can be considered specific to some bezoar types. Materials and Methods. The records of 39 patients who underwent preoperative abdominal CT and subsequent operation with a diagnosis of intestinal obstruction due to bezoars were retrospectively analyzed. Results. In total, 56 bezoars were surgically removed from 39 patients. Bezoars were most commonly located in the jejunum (n=26/56, 46.4%). Sixteen (41.0%) patients had multiple bezoar locations in the gastrointestinal tract. Common CT findings in all patients were a mottled gas pattern and a focal ovoid or round intraluminal mass with regular margins and a heterogeneous internal structure. Furthermore, some CT findings were determined to be specific to bezoars caused by persimmons. Conclusions. Preoperative CT is valuable in patients admitted with signs of intestinal obstruction in geographic regions with a high bezoar prevalence. We believe that the correct diagnosis of bezoars and the identification of their number and location provide a great advantage for all physicians and surgeons. In addition, some types of bezoars have unique CT findings, and we believe that these findings may help to establish a diagnosis

Kompoziti visoke gustoće na bazi polietilena ojačani toplinski modificiranim drvom

This study investigated the effect of untreated and heat-treated ash and black pine wood flour concentrations on the selected properties of high density polyethylene (HDPE) composites. HDPE and wood flour were used as thermoplastic matrix and filler, respectively. The blends of HDPE and wood fl our were compounded using single screw extruder and test samples were prepared through injection molding. Mechanical properties like tensile strength (TS), tensile modulus (TM), elongation at break (EatB), fl exural strength (FS), fl exural modulus (FM) and impact strength (IS) of manufactured composites were determined. Wood fl our concentrations have significantly increased density, FS, TM and FM and hardness of composites while reducing TS, EatB and IS. Heat-treated ash and black pine fl our reinforced HDPE composites had higher mechanical properties than untreated ones. Composites showed two main decomposition peaks; one coming from ash wood flour (353-370 °C) and black pine wood fl our (373-376 °C), the second one from HDPE degradation (469-490 °C). SEM images showed improved dispersion of heat-treated ash and black pine wood flour. The obtained results showed that both the untreated and heat-treated ash/black pine wood flour have an important potential in the manufacture of HDPE composites.U radu je opisano istraživanje utjecaja koncentracije drvnog brašna od nemodifi ciranog i toplinski modificiranog drva jasena i crnog bora na odabrana svojstva kompozita visoke gustoće na bazi polietilena (HDPE). HDPE i drvno brašno upotrijebljeni su kao termoplastična matrica i punilo. Mješavine HDPE-a i drvnog brašna pripremljene su uz pomoć ekstrudera s jednim vijkom, a ispitni su uzorci izrađeni injekcijskim prešanjem. Istraživanjem su određena mehanička svojstva proizvedenih kompozita poput vlačne čvrstoće (FS), modula elastičnosti pri vlačnom ispitivanju (FM), istezanja pri lomu (EatB), čvrstoće na svijanje (FS), modula elastičnosti pri tlačnom ispitivanju (FM) i udarne čvrstoće (IS). Koncentracije drvnog brašna značajno su povećale gustoću, tvrdoću, FS, TM i FM, a smanjile TS, EatB i IS. HDPE kompoziti ojačani drvnim brašnom od toplinski modifi ciranog drva jasena i crnog bora imali su bolja mehanička svojstva od kompozita ojačanih drvnim brašnom od nemodifi ciranog drva jasena i crnog bora. Kompoziti su pokazali dva glavna područja razgradnje: prvo, razgradnju drvnog brašna drva ariša (353 – 370 °C) i drvnog brašna drva crnog bora (373 – 376 °C) te, drugo, razgradnju HDPE-a (469 – 490 °C). SEM slike potvrdile su poboljšanu raspodjelu drvnog brašna od toplinski modifi ciranog drva jasena i crnog bora. Rezultati su pokazali da drvno brašno od nemodifi ciranoga i toplinski modifi ciranog drva jasena i crnog bora imaju velik potencijal u proizvodnji HDPE kompozita

Türkiye’deki Bazı Ağaç Türü Odunlarının Fiziksel Özellikleri Üzerine Yapılan Araştırmaların Değerlendirilmesi

Bu çalışmada, 1951-2015 yılları arasında Türkiye’deki bazı ağaç türü odunlarının, bazı fiziksel özelliklerine ait yapılmış çalışmalar incelenmiştir. Bunun için literatür taramasında Uluslaraarası indesksli taranan dergiler ve Ormancılık Araştırma Enstitüsü dergileri, Orman Fakültesi dergileri, Mühendislik dergileri, TUBİTAK Turkish Journal Of Agriculture And Forestry, Yükseköğretim tez arşivindeki Yüksek Lisans ve Doktora tezleri temel alınarak araştırma yapılmıştır. Araştırmalarda hiçbir işleme tabi tutulmadan yalın haldeki odunun, Odun-Su İlişkileri, Ağırlık-Hacim İlişkileri, Elektriksel Özellikler ve Akustik Özelliklere ait fiziksel özelliklerini ortaya koyan çalışmalar değerlendirmeye alınmıştır. Yapılan çalışmalardan elde edilen sonuçlar, tablolar halinde, kapsamlı bir çalışmayla ortaya konmuştur. Birimlerde birliği sağlamak için SI sistemine göre N/mm2 kullanılarak okuyuculara kolaylık sağlanmıştır