MDF atıklarının odun plastik kompozitlerin üretiminde değerlendirilmesi

Bu çalışmada, orman endüstrisinin ve mobilya fabrikalarının üretim esnasında açığa çıkan lif levha atıklarının odun plastik kompozitlerin üretiminde odun unu yerine potansiyel olarak değerlendirilmesi hedeflenmiştir. Odun plastik kompozit (OPK) üretiminde polimer matris olarak polipropilen (PP) seçilmiş ve %10 ile %50 arasında lif levha atık unu ile sekiz farklı parametrede çift vidalı ekstrüder kullanılarak pellet üretimi gerçekleştirilmiştir. Üretilen pelletlerden 25 cm x 25 cm ve 2 mm ebatlarında ASTM D4703-10’a göre sıcak pres kalıplama tekniği yöntemiyle odun plastik kompozitler üretilmiştir. Her bir karışım parametresi için üç levha üretilmiş ve bunlardan on adet çekme, eğilme ve darbe direnç test örnekleri hazırlanmıştır. Hazırlanan örneklerin çekme, eğilme ve darbe dayanımı testleri sırası ile ASTM D638, ASTM D6109 ve ASTM256’ya göre tespit edilmiştir. Kopma yüzeyleri taramalı elektron mikroskobu (SEM) ile karakterize edilmiştir. MDF unu katılım oranının artmasına bağlı olarak çekme ve darbe direnç değerlerinde belirgin düşüşler gözlenmiştir. MDF unu takviyeli kompozitlerin elastikiyet modülü ve eğilme direnci değerleri plastik keresteler için ASTM D 6662 standardında istenen değerlerin çok üstünde olup plastik kereste kullanım alanlarında kullanılabileceği sonucuna ulaşılmıştır. Anahtar kelimeler: Odun plastik kompozitler, Polipropilen, Orta yoğunlukta lif levha un

Ubrzano izlaganje polipropilenskih kompozita ojačanih pregrijanim drvom vremenskim utjecajima i otpornost na propadanje

The aim of this study was to determine the accelerated weathering and decay resistance of the heattreated wood reinforced polypropylene composites (HT-WPC). Polypropylene (PP) was used as a matrix and the heat-treated wood treated at 180 °C and 220 °C as reinforcement fi ller. The effect of three fi ller type, such as 40, 60 and 100 mesh, on the outdoor performance of composites was also investigated. The composites were prepared with twin screw extruder, and the test samples were obtained with compression molding. Lightness index (L*), color changes (ΔE*) and physical changes on the surface of the composites after the accelerated weathering, and decay resistance of the composites were investigated. According to the results, the effects of heat-treated wood on color changes were found to be more than its fi ller size, and while the fi ller loadings were increased from 5 % to 20 %, it was determined to increase the color changes of the composites. In scanning electron microscopy (SEM) images, crack formation and deterioration on the surface of the composites were determined. In FTIR spectra, no difference was determined between the composites, and all peaks were similar to each one. The addition of heattreated wood improved the antifungal effi ciency of the composite, and the mass losses decreased with the increasing of heat treatment temperature. As a result, adding heat-treated wood to PP was found to improve the outdoor performance of the HT-WPCs

The modulation of glucocorticoid receptor content by 3-O-methyl-D-glucose transport in human mononuclear leukocyte in obesity

Glucocorticoid receptors (GR) and 3-O-methyl-D glucose (3-O-MG) transport were determined in mononuclear leukocytes (MNL) from 11 abdominal obese subjects, 10 pituitary-dependent Cushing's syndrome (Cushing's disease) and 10 healthy controls. Using a whole-cell competitive binding assay and H-3-dexamethasone as tracer, MNL of abdominal obese subjects were found to have 4855+/-1389 sites/cell which was significantly lower (p0.05). These results indicated that, in abdominal obesity, the GR binding capacity in MNL is influenced by the changes in glucose transport. (J. Endocrinol. Invest. 21: 656-661, 1998) (C)1998, Editrice Kurtis

Investigating changes in the chemical constituents and dimensional stability of heat-treated hornbeam and Uludag fir wood

Changes in chemical constituents and some physical properties such as swelling and water absorption of hornbeam (Carpinus betulus L) and uludag fir (Abies bornmulleriana Mattf.) wood were investigated after heat treatment at three different temperatures (170 o C, 190 o C, and 210 o C) for three different durations (4, 8, and 12 hours) by using thermal gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectrometry. The results of TGA show that there was less weight loss in the main degradation region (300-500 o C) for the heat-treated samples as compared to untreated (control) samples. In addition, there was greater weight loss of hornbeam wood than of uludag fir wood in a similar degradation region. This difference could be due to the chemical constituents of softwoods and hardwoods. The results of FTIR spectrometry show that the chemical constituents of the hornbeam wood samples were more affected by heat treatment. All heat-treated samples exhibited lower water absorption and swelling compared to control samples. It was found that the relative decrease in swelling and water absorption for uludag fir was higher than for hornbeam. The maximum decrease in water absorption and swelling was found for both species that were heat-treated at 210 C for 12 hour

Antiphospholipid syndrome associated with malignant mesothelioma presenting with superior vena cava thrombosis: A case report

A 59-year-old woman who had dyspnea and neck swelling for 10 days was admitted to the hospital. Malignant peritoneal mesothelioma was diagnosed previously. According to the clinical findings, and laboratory and pathologic examination, the patient was found to have disseminated venous thrombosis and antiphospholipid syndrome, which is treatment-resistant autoimmune paraneoplastic syndrome

Vocal Cord Paralysis in Multifocal Motor Neuropathy: A Case Report

Multifocal motor neuropathy is characterized by slowly progressive, asymmetrical weakness of the arms without sensory loss. The disease can also cause vocal cord paralysis as it runs its course. A 34-year-old man developed progressive weakness in his hand muscles for one year and dysphonia for three weeks. Neurological examination revealed there was moderate weakness and mild muscle wasting in distal muscles of the upper limbs, predominantly in the left hand. Left laryngeal nerve palsy was also discovered during his otolaryngological examination. Nerve conduction studies revealed multiple sites of conduction block without sensory abnormalities consisting of selective involvement of motor fibers. The patient received intravenous immunoglobulin treatment after multifocal motor neuropathy diagnosis. Multifocal motor neuropathy with conduction block is rarely associated with vocal cord paralysis. This condition should be kept in mind in cases of laryngeal nerve palsy with an asymmetric motor neuropathy, as patients might benefit from immunoglobulin treatmen