Repositional-fixation ring for surgical treatment of acetabular fractures (preliminary results of static tests)

BACKGROUND: Currently, several types of designs of support rings of M. Muller, Burch-Schneider, rings of the company Protek (Switzerland), implanted in the BB are widely used, which are used in the surgical treatment of long-standing fractures of the BB, as a rule, as a device that strengthens the walls of the BB. AIM: Study of the deformation properties of the repositional-fixing ring. MATERIALS AND METHODS: For carrying out mechanical tests, a ring with an external diameter of 52 mm was made by the method of sequential sintering using additive technologies by the company Konmet LLC, Moscow. Laboratory mechanical tests were carried out by the Testing Laboratory of Medical Devices and Materials of the N.N. Priorov National Medical Research Center of Traumatology and Orthopedics. RESULTS: As a result of static testing of the ring for compression, tension, torsion, and joint stretching and twisting of the edges of the ring connector, its deformation properties are studied. Load corresponding to the deformation of 2 mm, kN: compression 0.180; tension 0.061; torsion (torque corresponding to the angle of rotation of 5 degrees, Nm) 2.653; joint tension with twisting of the edges of the ring connector (load corresponding to the deformation of 10 mm, kN) 0.048. CONCLUSION: The results of the initial study of the deformation behavior of the ring structure show that it is necessary to refine the ring design and further study the deformation and strength characteristics of the ring.

To Estimate the Importance of Wharton’s Jelly in the Growth of the Foetus – A Light Microscopic Study

BACKGROUND Human umbilical cord contains two arteries and one vein with their tunica intima and tunica media layers. The role of tunica adventitia is fulfilled by Wharton’s jelly, a mucoid connective tissue. The function of Wharton’s jelly is to prevent the vessels from compression and torsion which is essential for foetal development. The purpose of the study was to estimate the importance of Wharton’s jelly in the growth of the foetus. METHODS Umbilical cord tissue collected from each case was immediately put in 10 % formalin for fixation. Slides were then stained with Haematoxylin and Eosin. These slides were then read under light microscopy and measurements were taken using a photomicrograph. Wharton’s jelly area was calculated by subtracting the total vessel area from the umbilical cord area. RESULTS The histological measurements of umbilical vessels include the external diameter, lumen diameter, wall thickness, thickness of tunica intima and tunica media, and the area. The mean area of the umbilical cord was 35.73 ±23.04 mm2 (Mean ± SD) and the mean area of the Wharton’s jelly was 29.74 ± 19.26 mm2. There was a significant difference in the external diameter and wall thickness of the umbilical artery. Analyses showed that there was a significantly (P < 0.01) increased external diameter and wall thickness of umbilical artery in normal cases, compared to single umbilical artery cases. CONCLUSIONS There was a significant positive correlation between the gestational age and the external diameter of the umbilical cord. There was a significant difference in the external diameter of the umbilical cord between SUA cases (4.45 mm) and the other foetuses with normal umbilical cord (6.53 mm). There was a significantly increased external diameter, lumen diameter, wall thickness and area of umbilical vein in normal cases, compared to single umbilical artery cases. There was a significantly increased area of umbilical cord and area of Wharton’s jelly in normal umbilical cord foetuses than foetuses with a single umbilical artery. KEY WORDS Foetus, Umbilical Cord, Wharton’s Jelly, Umbilical Artery, Umbilical Vein, Light Microscopy

Large Scale Structures in Elevated Jet Normal to Crossflow

Transverse jet from elevated source is found in various environmental and industrial field which include smoke exhausting from stack into atmosphere and sewage water disposal in deep-ocean. The experiment is carried out in water tunnel using flow visualization and Laser Doppler Velocimetry. Analysis has been performed for axisymmetric round jet of aspect ratio of 9.0 with the velocity ratio varying up to 2.5 at Reynolds number (based on free stream crossflow velocity and jet external diameter) of 1000. Result shows the formation of different jet shear layer vortices with varying velocity ratio are: (i) clockwise-downwash vortices (velocity ratio less than 0.3), (ii) delayed-regular-clockwise vortices (between 0.3 to 0.7), (iii) regular-clockwise vortices (between 0.7 to 1.4) at the lee side of the jet shear layer, (iv) irregular-anticlockwise vortex at the upstream along with clockwise vortices at the lee side of the jet shear layer that together forms mushroom vortices (between 1.4 to 1.9) and (v) regular-mushroom vortices (above 1.9). The other vortices found are stack-end vortex (less than 0.9) in the wake near free end, upright vortices (above 0.9) in jet-wake and hairpin vortices (between 0.3 to 0.6) in downstream which is the stretched part of evolving shear layer.

The impact of the catheter to vein ratio on peripheral intravenous cannulation success, a post-hoc analyses

Background Intravenous cannulation is usually the first procedure performed in modern healthcare, although establishing peripheral intravenous access is challenging in some patients. The impact of the ratio between venous diameter and the size of the inserted catheter (catheter to vein ratio, CVR) on the first attempt success rate can be of added value in clinical. This study tries to give insight into the consideration that must be made when selecting the target vein and the type of catheter, and proved the null hypothesis that an optimal CVR would not be associated with increased first attempt cannulation success. Methods This was a post-hoc analyses on adult patients admitted for peripheral intravenous cannulation. Intravenous cannulation was performed according to practice guidelines, by applying the traditional landmark approach. The CVR was calculated afterwards for each individual patient by dividing the external diameter of the inserted catheter by the diameter of the target vein, which was multiplied by 100%. Results In total, 610 patients were included. The median CVR was 0.39 (0.15) in patients with a successful first attempt, whereas patients with an unsuccessful first attempt had a median CVR of 0.55 (0.20) (P<0.001). The optimal cut-off point of the CVR was 0.41. First attempt cannulation was successful in 92% of patients with a CVR<0.41, whereas as those with a CVR>0.41 had a first attempt success rate of 65% (P<0.001). Conclusion This first introduction of the CVR in relation to cannulation success should be further investigated. Although, measuring the venous diameter or detection of a vein with a specific diameter prior to cannulation may increase first attempt cannulation success.

Predictions of formability parameters in tube hydroforming process

The objective of this study is to improve the bulging and minimize the thinning ratio to enhance manufacturing of components in Industries. Tube hydroforming is an advanced manufacturing technology used for making intricate and complex tubular parts which required less cycle time. This research focuses on hydroforming process, formability and process parameters design to replace the conventional tube bending, welding and cutting operations. The prediction of parameters is done by applying numerical and experimental approach. During experimentation the pressurized fluid is used to deform the tubes in a plastic deformation. In this study, two types of grade materials are used such as AISI304 and AISI409L of 57.15 mm external diameter with 1.5 mm thickness in the form of electric resistance welded tubes to measure stain path, thinning and bulge height. However, it is observed that the internal pressure and L/D ratio are effective parameters in both numerical analysis and experimentation. In axial feed condition, it is observed that 16.3% thinning in weld region and 44.6% thinning in base metal region, whereas, in fixed feed condition, it is observed that 7.7% thinning in weld region and 18.6%thinning in base metal region for L/D = 1 and L/D = 3 respectively. The numerical analysis with experimental results shows a very good match. It is seen that the axial feed leads to better formability with fixed feed condition because in axial feed condition material supplies towards the center of the bulge tube. The feasibility of the hydroforming process for manufacturing of AISI304 and AISI409L grade material as per the requirements of the industries is also checked. The maximum bulging is observed in L/D = 2 by comparing with the other ratios. This process can be effectively used for AISI304 grade material because the formability is better than AISI409L. Article highlights The strain path measured and predicted at necking point for ERW tube in both weld and base metal. Thinning is measured during bulging of tube under the axial and fixed feed condition. For L/D = 1 ratio observed strain distribution in unidirectional and L/D = 2, 3 observed in plane strain and bidirectional respectively.

Zaczyny cementowe z dodatkiem nanorurek węglowych do uszczelniania otworów wiertniczych o wysokiej temperaturze i ciśnieniu złożowym (150°C, 90 MPa)

The article presents the results of the influence of carbon nanotubes on the mechanical parameters of cement stones under high temperature and pressure conditions (150°C, 90 MPa). The tests used multi-walled carbon nanotubes (MWCNTs) with an external diameter of 10–20 nm and a length of 10–30 μm. Cement slurries contained 0.1% of CNTs bwoc (by the weight of cement). Laboratory tests of cement slurries were carried out at the Oil and Gas Institute – National Research Institute. The tests were carried out under conditions of increased pressure and temperature at 150°C, 90 MPa. Cement slurries were prepared on the basis of class G drilling cement. Developing recipes were guided by the requirements to be met by cement slurry for the cementing of casing in the conditions of high temperature and reservoir pressures. The densities of tested slurries ranged from 1900 kg/m3 to 2250 kg/m3 (slurries with the addition of hematite). The cement slurries were tested for density, fluidity, rheological parameters, filtration and thickening time. Compressive strength tests and measuring adhesion were carried out after 2, 7, 14 and 28 days. Cement slurry recipes with very good technological parameters were developed and after curing (after 28 days of hydration) had very high values of compressive strength, reaching up to 45 MPa. Cements were characterized by high values of adhesion to pipes reaching up 7 MPa after 28 days. The research showed significant information about possible applications of carbon nanotubes to modify the cement slurry under conditions of high temperature and pressure. The conducted tests confirmed that the addition of even small amounts of CNTs improves the mechanical parameters of the cement stone compared to the base sample without such addition, and also reduces the thickening time of cement slurries and reduces filtration. It is investigated that CNTs addition increases the viscosity and yield point of cement slurry. As a result, slurries with the addition of MWCNTs will more effectively displace the mud from the borehole and significantly affect the quality of cementation.

EFFECT OF TEMPERATURE ON THE MECHANICAL BEHAVIOR OF THE HUMAN AORTA AND CAROTID ARTERIES

INTRODUCTION Temperature affects the mechanical behavior of the arteries, a fact that intervenes in their function, both in physiology and in pathological states. The aim of the study is to analyze the mechanical response in the arteries (aorta and carotids) to changes in temperature. MATERIAL AND METHODS The thermo-mechanical behavior of human arteries (26 primitive carotids and 26 thoracic aortas) from cadaveric organ donors has been studied. The tests were carried out in a passive state, without electrical or chemical activation of the vessels. Pressurization tests were carried out at 4 different temperatures (17, 27, 37 and 42ºC) correlating internal pressure-external diameter of the vessels. The thermo-mechanical analysis was evaluated using the pressure-diameter curves at different temperatures, for this the coefficient of thermal expansion (α = (ΔD / D) / ΔT) and the Hayashi stiffness (β), exponential equation (Pressure / Diameter ratio). RESULTS The effect of temperature on arterial behavior is maximum when the curves refer to the initial diameter of the vessel at 0 mmHg for each temperature. At low pressures, the coefficient of dilation is negative, while above a certain threshold pressure (different for each type of artery), the coefficient of dilation becomes positive. CONCLUSIONS The stiffness of the vessels is manifested in the slope of the pressure-diameter curves and decreases with increasing temperature. The coefficient of thermal expansion is a function of the internal pressure to which the arteries are subjected.

Multimodale Bronchoskopie in der Rundherddiagnostik: Gewinnbringende Kombinationen ausloten

There are cases of peripheral lung nodules that are difficult to approach despite using ancillary diagnostic devices during multimodal bronchoscopy. The use of ultrathin bronchoscopes has shown superiority over standard thin bronchoscopes. We retrospectively evaluated whether substitution of the thin-bronchoscope by the ultrathin device during multimodal bronchoscopy improves lesion ultrasound visualization and diagnostic yield in patients with difficult-to-approach pulmonary lesions. The study comprised 44 out of 338 patients that underwent multimodal bronchoscopy at Matsusaka Municipal Hospital. The thin-bronchoscope with an external diameter of 4 mm was substituted by the ultrathin-bronchoscope with an external diameter of 3 mm when the radial endobronchial ultrasound showed that the probe position was not within the target lesion. The median diameter of the pulmonary tumors was 17.5 mm (range: 6.0–5.2.0 mm). The endobronchial ultrasound showed the probe’s position adjacent to the lesion in 12 cases and no visible lesion in 32 cases using a thin-bronchoscope. However, the endobronchial ultrasound views changed from adjacent to the lesion to within the lesion in nine cases, from no visible lesion to within the lesion in 17 cases, and from no visible lesion to adjacent to the lesion in nine cases after bronchoscope substitution. After substitution, the diagnostic yield was 80.8% in cases with the radial probe within the target lesion, 72.7% in cases with the probe adjacent to the target lesion, and 0% in cases with no visible lesion. The overall diagnostic yield was 65.9% after bronchoscope substitution. The substitution of the thin bronchoscope by the ultrathin device on a need basis improves the position of the radial endobronchial ultrasound probe and diagnostic yield of pulmonary lesions during multimodal diagnostic bronchoscopy.

Physicochemical characterization of natural fibers obtained from seed pods of Ceiba aesculifolia

Characterization of Ceiba aesculifolia (CA) fibers by various techniques is herein reported. The seed pods were collected, and the fibers surrounding the seeds were characterized or treated in an oven at 100 °C prior to characterization by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis coupled with a differential scanning calorimeter (TGA-DSC). The SEM micrographs showed that the natural material is comprised of tubes of external diameter of approximately 27 μm and a mean wall thickness of about 0.62 μm. The results also indicated that the tubes begin to decompose at approximately 220 °C.

Evaluation of Bonding Gap Control Methods for an Epoxy Adhesive Joint of Carbon Fiber Tubes and Aluminum Alloy Inserts

The aim of this paper is to compare two methods of epoxy adhesive bond gap control: one with a geometrical (mechanical) solution and the other with glass beads, which have the diameter of the desired bond gap and are mixed with an epoxy adhesive. The adhered materials were carbon fiber composite tubes and aluminum alloy inserts, which were used as wishbones in a suspension system of a motorsport vehicle. It was assumed that the gap thickness would be equal to 0.2 mm and the length of a bond would be 30 mm. The internal diameter of the tubes was 14 mm and 18 mm, whereas the inserts’ external diameter was 13.6 mm and 17.6 mm. Their surface has been subjected to mechanical treatment with sand paper starting from 240 grit up to 400. The adhesives used were EA 3425 and EA 9466 cured at 80 °C for 2 h. The results showed that the glass beads method provides more consistent and better results as compared to the geometrical (mechanical) method. Further study in the area of fatigue and interfacial failure modes could be useful.