Optimization of sol-gel synthesized preceramic polymer precursors for fabrication of high purity boron carbide (B4C) powders

Boron Carbide (B4C), due to its high hardness and elastic modulus, superior chemical stability, low density and high neutron absorption cross section, is well suited to a variety of industrial applications such as blasting nozzles, wire-drawing dies, powdered metal and ceramic forming dies, vehicle armour, bulletproof vest, nuclear reactor control rods and neutron absorbing shielding. The current fabrication techniques of boron carbide powders such as carbothermal reduction, direct synthesis from elements, vapour-phase reduction, and magnesiothermic reduction require expensive equipment and starting materials. For this reason, in recent years studies focused on the development of low-temperature synthesis techniques to reduce the production cost of boron carbide as well as to get better control over composition and particle morphology

Delay in Diagnosis of Intestinal Obstruction in a Patient with Familial Mediterranean Fever

Familial Mediterranean Fever (FMF) is a recurrent disease characterized by inflammatory process effecting synovial membranes such as peritoneum, pericardium and joints. It usually presents with acute abdominal pain. Intestinal obstruction secondary to adhesions may be observed in FMF patients. Sometimes diagnosing intestinal obstruction can be a challenging problem. We were presented a patient with FMF and adhesive intestinal obstruction. He was operated on after 10 days of symptoms. Delay in diagnosis and treatment of the case discussed with literature review

Processing of surface modified nano boron carbide (B4C) containing flexible composites as shielding materials

Aims: The main aim of the work is to synthesize nano boron carbide using cost effective modified sol-gel technique and then functionalize the obtained nanoparticles surface so that they can be homogeneously distributed within flexible polymeric matrices for radiation shielding purposes. Methods: Different starting chemicals were used in sol gel technique to obtain nano boron carbide (B4C) particles with controlled size and morphology. Surface modification with various functional groups was conducted on the synthesized particles and final coated B4C particles were embedded within the polymers using high shear mixing process in the form of thin sheets and plates. Results: It was shown first that nano boron carbide particles can be obtained by a novel modified sol gel technique using nano elemental boron which results in obtaining stoichiometric boron carbide. Surface modified B4C with functional groups resulted in the excellent distribution within polymeric matrices leading to the improvement in both mechanical and shielding properties. Conclusions: Size and morphology controlled B4C can improve the mechanical and shielding properties of polymer based composites. The final obtained composite materials are considered to be suitable candidate for lightweight radiation shielding materials

Response of seeds and pollen of Onobrychis viciifolia and Onobrychis oxyodonta var. armena to NaCl stress

Sainfoin (Onobrychis viciifolia Scop.) is an important forage legume crop with 52 species adapted to dry and poor soils in Turkey, but little is known about the effects of salinity on germination and seedling growth in arid and semiarid regions suffering from salinity problem. The seeds and pollen of two species of sainfoin O. viciifolia and O. oxyodonta var. armena (Syn: O. armena) were exposed to 0, 5, 10, 20 and 30 dS m-1 of NaCl under in vivo and in vitro conditions and evaluated for germination under salt stress by comparing germination percentage, mean germination time, root and shoot length, fresh and dry seedling weight and dry matter. Increased salinity levels generally resulted in decrease in all traits except time to germination, dry seedling weight and dry matter, which increased at high salinity levels. O. viciifolia seeds germinated and grew more rapidly compared to O. armena seeds under NaCl stress. No decrease in germination and seedling growth up to 10 dS m-1 was recorded. On the other hand, there was a clear difference for germination and seedling growth between in vivo and in vitro conditions. Lower values were obtained from in vitro experiments; suggesting that mineral salts, sucrose and agar may have resulted in higher osmotic potential inhibiting germination and seedling growth of species compared in vivo conditions. Decrease in pollen germination with increasing salinities was very sharp, indicating that pollen germination had higher sensitive to salinity. But, pollen grains of O. armena germinated rapidly compared to O. viciifolia. The results emphasize that in vivo experiments could be used for screening of NaCl tolerance in sainfoin cultivars without expensive chemicals and sophisticated equipments, but pollen germination is more appropriate for its wild relatives

A comparison of fuzzy multicriteria decision making methods for intelligent building assessment

The methodology, Multicriteria Decision Making (MCDM), refers to finding the best alternative from all of the feasible alternatives in the presence of multiple, usually conflicting, decision criteria. Nowadays, intelligent buildings’ performance that is increasingly evidenced in building design and construction has been analyzed by using MCDM techniques. Intelligent buildings (IBs) are also under assessment according to their IB related characteristics and actual circumstances as a MCDM problem. In this paper, two most known MCDM methodologies, Analytic Hierarchy Process (AHP) and TOPSIS (Technique for Order Preference by Similarity to Ideal Solution), are used for intelligent building assessment under fuzzy environment for dealing with the evaluations’ uncertainty and imprecision in which the expert's comparisons that are represented as fuzzy numbers. For this aim, three intelligent building alternatives for a business centre in Istanbul are evaluated by using these two fuzzy MCDM methods and the obtained ranking results are compared

Haber Oyunları: Deneyimlenebilir Gerçeklik, Ludenik Haber Okuma, Amaç ve Normların Çatışması

Gazetecilik, bilgi ve iletişim teknolojilerinin gelişmesine bağlı olarak medya üretim çeşitliliğinin yakınsaklığından etkilenmektedir. Üretim ilişkilerinin katılımcı kültürü benimsemesi ve transmedya hikaye anlatıcılığının gazetecilik formlarında etkili olması haber anlatısını da dönüştürmüştür. Bu kapsamda eğlence (hazcı) ve bilgi edinme (faydacı) ihtiyaçlarının sektörel yakınsaklığı, haber oyunlarının üretimine ortam sağlamıştır. Bu derleme çalışmanın amacı gazetecilik motivasyonları ile oyun motivasyonlarının disiplinlerarası ilişkiler içerisinde ortaya çıkardığı haber oyunları; ludenik haber okuma teorisi ile temellendirerek üretim ve tüketim ilişkileri, anlatı yapısı, zamansallık, etik kaygılar, ideolojik şüpheler ve merhamet yorgunluğu kavramlarıyla tartışmaktır. Gazetecilik için yeni bir anlatı biçimi olan haber oyun üretim ortamlarında örtüşen amaçlar ve çatışan normlar bir aradadır. Bu anlamda alanyazında yer alan araştırmalarda haber oyunlarının; haberciliğe getireceği yenilik ve okuyucuya sağlayabileceği kazanımların, gerçeklik ve merhamete dair şüpheler ile karşı karşıya kalabileceği görülmüştür. Bu şüphelere rağmen haber oyunları, oyunların eğlenceli ya da deneyimlenebilir unsurlarını haber anlatısına dahil ederek ve gazeteciliğin niteliğini koruyarak, içerikteki titizliği biçimsel çekicilikle birleştiren etkili bir içerik üretim yoluna dönüşebilir

Evaluation of Semicircular Canal Functions by the Video Head Impulse Test (vHIT) in Individuals with Motion Sickness

Background: In the occurrence of motion sickness, the functioning of the vestibular system in harmony has an important role. Aim/Objective: To evaluate the effectiveness of the vestibular system in individuals with motion disease with the Video Head Impulse Test (vHIT) device, which evaluates the vestibulo-ocular reflex (VOR). Materials and Methods: Thirty individuals with motion sickness (21 females, 9 males) and 30 healthy individuals (11 females, 19 males) without any vestibular complaints were examined with the vHIT device. All participants were older than 18 years. Results: It was observed that VOR gain values of the individuals with motion disease were significantly lower than those of the healthy individuals. Asymmetry values of the individuals with motion disease in all semicircular canals were higher than those of the healthy individuals; however, this difference was statistically significant only in the anterior semicircular canal. Conclusion and Significance: The observation of low gain values in all semicircular canals in individuals with motion sickness suggested that individuals with motion sickness may experience dysfunction in the sensory organelles in the vestibular system. Studies with larger case series and audiological test batteries will help us better understand motion sickness. Keywords: Motion sickness; vestibular; vHIT DOI: 10.7176/JHMN/79-05 Publication date:August 31st 202

The effect of periosteum on the union of the autoclaved bone graft-host bone: Experimental study in rabbits

Amaç: Bu çalışmada tavşan radius kemiğinden alınan otolog segmenter kemik greftinin otoklavda bekletilerek intramedüller tespitle alındığı yere tekrar yerleştirilmesi ve periost dokusu ile bütünleşmesinin iyileşmeye etkisi incelendi. Gereç ve yöntemler: On altı erişkin tavşanda sol radiusun orta bölümünden 15 milimetre uzunluğunda kemik parça çıkarıldı. Çıkarılan kemikler 120 °C’de 15 dakika otoklavize edildi ve intramedüller Kirschner telleriyle yerine tekrar tespit edildi. Tavşanlar iki eşit gruba ayrıldı ve birinci gruptaki sekiz tavşanın greft-alıcı kemik birleşim bölgesi periost flebiyle örtülürken, ikinci gruptaki diğer sekiz tavşanın greft-alıcı kemik birleşim bölgesinde periost dokusu kullanılmadı. Cerrahi işlem sonrası 2, 4, 6. ve 8. haftalarda düz grafiler çekildi. Sekizinci haftanın sonunda elde edilen radyolojik bulgular Yang’ın modifiye radyolojik sayılama yöntemiyle değerlendirildi. Bulgular: Radyolojik bulgular 8. haftada birinci grupta (ort. 10.94) ikinci gruba (ort. 6.06) göre daha fazla kallus dokusuyla, daha erken ve daha fazla iyileşme elde edildiğini gösterdi. Fark istatistiksel olarak anlamlı bulundu (p=0.04, <0.05). Sonuç: Periost yaması kolay uygulanabilen ve greftalıcı bölgenin iyileşmesini hızlandıran biyolojik bir dokudur. Periost yama tekniği greft-alıcı kemik bölgesinin iyileşmesinde etkili bir yöntemdir ve bu teknik, yapısal allogreftlere uygulanmaya değer bulunmuştur

Low temperature synthesis and characterization of high purity nano boron carbide (B4C) structures

Boron carbide (B4C) is accepted as an important engineering material due to its high melting point, high hardness, high Young's modulus, excellent radiation (neutron) absorption properties and low thermal conductivity. Although different methods, such as high temperature carbothermic reduction and chemical vapor decomposition, have been used to synthesize boron carbide, a low cost technique that provides high purity B4C with no residual carbon, is required by industry. Therefore, in the present study, synthesis of high purity, high crystallinity nanostructured boron carbide particles with various morphologies, is proposed using a modified low-temperature sol gel process. The effects of starting chemicals, calcination and sintering temperature/time on the formation of B4C structures, morphology and stoichiometry were reported. Detail characterization studies including TEM, XRD, NMR and DTA were used to support the results on the formation of stoichiometric boron carbide with high crystallinity at low temperatures