INVESTIGATIONS OF INITIAL AND LATER DEFORMATION OF THE FIBROCARTILAGINOUS TISSUE OF THE TEMPOROMANDIBULAR DISK

INTRODUCTION: Already in the nineteenth century anatomists began to study, using various simple devices available at the time, the elasticity of the menisci, their hardness and behavior under various mechanical stresses. The aim of the present investigation was to study for the first time the elasticity, hardness and resistance to tearing of the connective fibers in the structure of the temporomandibular joint meniscus, with direct applications in the medical field and in dental clinics. METHODS: The material under study consisted of 52 pieces obtained from cadavers of various ages immediately after death considering that human cartilaginous tissue suffers morphologic alterations only several days after death, it being resistant to hypoxia. The method and the technique used to obtain the pieces are original, employing instruments from oral and maxillofacial surgery, orthopedics and neurosurgery. After being obtained, the pieces were subjected to mechanical stress of one kg./sq mm by means of a ‘Shore A’ Scleroscope obtained from the Department of Materials Strength of the Technical University in Cluj-Napoca. RESULTS: In the interpretation of the results obtained and in the recordings made concerning the relationship in time between initial and later deformation, as well as variations in elasticity depending on age at the initial deformation, the main theories on deformable bodies and the mechanical trial of the materials were considered in the light of the fundamental calculus relations offered by the theory of elasticity and plasticity of bodies. CONCLUSIONS: The analysis of all the results revealed that the temporo- mandibular joint disk behaves like an elastic-plastic material, it bears enormous compression forces and its elasticity varies inversely proportional to age, if the compression time remains constant

Pervin Abla

Mahmut Yesari'nin Yeni Ses'te tefrika edilen Pervin Abla adlı romanıArşivdeki eksikler nedeniyle romanın tam metni verilememiştir

Перераспределение направления трещин гидравлического разрыва пласта с помощью оптимизации системы поддержания пластового давления

В данной статье описывается технология для контроля направления распространения трещин при проведении гидравлического разрыва пласта. С этой целью был проведен анализ уже имеющихся технологий. Представлено собственное решение для перераспределения направления трещины с помощью оптимизации системы поддержания пластового давления

Molecular dynamics parameter maps by 1H Hahn echo and mixed-echo phase-encoding MRI

Residual dipolar couplings and averaged correlation time maps in soft matter were obtained by mixed echo phase-encoding solid imaging (MIPSI). Use of the mixed echo in soft matter NMR imaging experiments has two crucial advantages: the signal intensity is recovered with a weak incoherence losses, and second, the intervals during which the phase-encoding evolution due to the magnetic field gradients takes place can be chosen to be much larger than with all other spin echo experiments and hence, a higher special resolution can be achieved. The parameter maps are compared to those obtained by the Hahn-echo phase-frequency encoding method. For both MRI methods the density operator formalism is applied in the average Hamiltonian approximation to describe the encoding of the spin echoes by the molecular motions. The results of preliminary experiments are presented

Fouling Behavior of Microstructured Hollow Fiber Membranes in Dead-End Filtrations: Critical Flux Determination and NMR Imaging of Particle Deposition\ud

The fouling behavior of microstructured hollow fibers was investigated in constant flux filtrations of colloidal silica and sodium alginate. It was observed that the fouling resistance increases faster with structured fibers than with round fibers. Reversibility of structured fibers’ fouling was similar during silica filtrations and better in sodium alginate filtrations when compared with round fibers. The deposition of two different silica sols on the membranes was observed by NMR imaging. The sols had different particle size and solution ionic strength and showed different deposition behaviors. For the smaller particle-sized sol in deionized solution (Ludox-TMA), there was more deposition within the grooves of the structured fibers and much less on the fins. For the alkali-stabilized sol Bindzil 9950, which had larger particles, the deposition was homogeneous across the surface of the structured fiber, and the thickness of the deposit was similar to that on the round fiber. This difference between the deposition behavior of the two sols is explained by differences in the back diffusion, which creates concentration polarization layers with different resistances. The Ludox sol formed a thick polarization layer with very low resistance. The Bindzil sol formed a slightly thinner polarization layer; however, its resistance was much higher, of similar magnitude as the intrinsic membrane resistance. This high resistance of the polarization layer during the Bindzil sol filtration is considered to lead to quick flow regulation toward equalizing the resistance along the fiber surface. The Ludox particles were trapped at the bottom of the grooves as a result of reduced back diffusion. The fouling behavior in sodium alginate filtrations was explained by considering the size-dependent deposition within the broad alginate size distribution. The better reversibility of fouling in the structured fibers is thought to be the result of a looser deposit within the grooves, which is more easily removed than a compressed deposit on the round fiber