screw

The article gives the recommended scheme and principle of operation of the cleaner of fibrous material from large waste. The results of theoretical studies to determine the laws of motion and recommended parameters of the working bodies of the cleaning machine are presented. The results of comparative production tests of the cleaner of fibrous material from large waste are provided. The main parameters and modes of operation of the working bodies of the cleaner of fibrous material, in particular cotton, are substantiated

The methods used today for the calculation of screw compressor thermodynamic and fluid flow processes, from quasi one-dimensional thermodynamic models to three-dimensional computational fluid dynamics (CFD) procedures, require accurate identification and quantification of geometric parameters, such as volume, gradient and cross-section, leakage flow and blow-hole areas. Historically, some of the geometric characteristics have been neglected, or approximated when calculation accuracy was not essential. However, more sophisticated models may lose some of their advantages if accurate geometric characteristics are not included in them. The work presented in this paper is aimed to enhance the accuracy of geometric calculations. The usual geometric calculation procedures are given and modified where necessary. The results are compared with models generated by 3D Computer Aided Design (CAD), software packages, from which improvements in the accuracy of predictions can be demonstrated.

Cross-Laminated Timber (CLT) is an innovative industrial wood product, especially as a structural wall in order to meet the rigidity and strength requirements in multi-storey timber buildings. CLT members are assembled with metal connectors (angle bracket, joining plates, etc.) via nails, screws, dowels, etc. For energy-absorbing structural CLT connections, many experimental studies have been conducted on the effectiveness of the connections, especially for the earthquake prone regions. There is no scientific study in this context in Turkey yet. For this purpose; the performance of a full-scale CLT wall-to-floor specimen assembled with metal connection was experimentally investigated under axial tensile force due to bending moments of seismic loads. Domestic angle bracket, plates, and phosphate coated annular ring nails were used. All the displacements and strains were measured and collected during the test of the specimen, behavior of connection and the failure mode was observed. As a result, the back side deformation of CLT wall member was prevented with the plates for a longer period compared with no-plate case and the withdrawal resistance of from CLT floor increased through phosphate coated annular ring nails and extra three nails in the corner of angle bracket on the front side. Domestic metal connectors were used in the experiments to support the metal industry and the production with low cost. This study is a pioneering study in Turkiye on the experimental performance of CLT connections for the structural utilization. The results are promising, and the further experimental researches will continue for the most effective connection type.

In a prospective randomised study, the Hansson pin technique for internal fixation of fractures of the femoral neck was compared with the Uppsala screw technique. The series consisted of 115 consecutive patients, 97 women and 18 men, with a mean age of 80 years. There were 56 patients treated with Hansson pins and 59 with Uppsala screws. After one year 22 patients had died, eight in the Hansson pin group and 14 in the Uppsala screw group (p = 0.28). Twenty-four complications had occurred, 18 in the Hansson pin group and six in the Uppsala screw group (p = 0.008). After exclusion of those with complications, the patients in the Hansson pin group had significantly more pain, less mobility, and a smaller proportion were living in their own homes.

In this study, three-layer particleboards are produced from a mixture of sunflower stalks (Helianthus annuus L.) and poplar wood (Populus alba L.) at certain ratios utilizing urea-formaldehyde (UF) adhesives. Panels with a density of 0.7 g/cm 3are manufactured with the ratios of 25, 50, and 75 percent particles from sunflower stalks or poplar. For comparison, panels are solely manufactured with sunflower stalks and poplar wood. All panels are tested for physical properties (thickness swelling (TS) and water absorption (WA)) and mechanical properties (internal bond (IB), modulus of elasticity (MOE), modulus of rupture (MOR), and screw holding capacity (SHC)). Results show that all the panels provide properties required by the Turkish standards for general purpose-use particleboards. Furthermore, properties of the panels have improved with the rising percentage of poplar particles in the panels. The combination of sunflower stalks and poplar particles can be used at different ratios a...

PURPOSE: A variety of implants have been used for the fixation of scaphoid fractures, but we have found no reports on bioabsorbable screws used for this purpose. We report 6 cases of scaphoid fractures treated with bioabsorbable screws. METHODS: Six patients with ...

Object. The authors tested the ability of a resorbable cannulated lag screw composed of a polylactide copolymer to repair Type II odontoid fractures. The resorbable screw was evaluated for its ability to restore strength and stiffness to the fractured odontoid process compared with traditional titanium screws. Methods. Type II odontoid fractures were created in 14 human cadaveric C-2 vertebrae by applying a posterolaterally directed load and piston displacement was measured. Seven of these specimens were repaired using metal screws and seven were repaired using resorbable screws. Specimens were reinjured using the same mechanism as the initial fracture. Values of ultimate strength and stiffness during failure were statistically compared between metal and resorbable screws and between initial fracture and reinjury. Conclusions. The stiffness and ultimate strength during initial fracture were significantly greater than those during reinjury in specimens repaired using resorbable screw...

Conventional percutaneous iliosacral screw placement in pelvic surgery is considered to be a highly demanding operative technique with a high rate of screw malpositions, which may be associated with the risk of neurologic damage or inefficient stability. In the conventional technique, the correct entry point for the screw and the small target corridor for the iliosacral screw may be difficult to visualize using an image intensifier. We tried to find out in this study whether the positioning of percutaneous screw implantations could be optimized by evaluating the rate and grade of malpositions and whether the needed revisions could be reduced by using computer navigation and three-dimensional (3D) image intensifier. A group of 54 patients with 63 screws implanted using computer navigation was compared with 87 patients with 131 screws implanted using the conventional fluoroscopic technique. The exact screw position was controlled in a postoperative computed tomography scan, and the grade of malposition of every screw was investigated and compared. A complete intraosseous screw position was found in 42% of cases using the conventional technique and was significantly less compared with 81% using a 3D image intensifier in combination with a navigation system. Moreover, the revision rate of 1.6% was significantly less in the navigated group compared with 19% in the conventional group. The results indicate that 3D-computer navigation of the percutaneous iliosacral screw insertion can facilitate surgical performance in respect to reducing screw malposition and revision rates.

En un secador tipo tornillo transportador (SCD), se evaluo el grado de secado y la eficiencia termica en el secado de acetato de calcio dihidratado. El SCD tiene 8.66 m de longitud y 0.17 m de diametro del tornillo. Las variables del diseno factorial (niveles mixtos 2x3² ) fueron: la velocidad rotacional del tornillo (N) en dos niveles, la temperatura (T) del solido alimentado en tres niveles y el flujo de alimentacion (C) en tres niveles. Durante los experimentos la humedad inicial del solido estuvo entre 50-70%, obteniendose grados de secado hasta del 14 % y eficiencias termicas hasta del 88%. A partir de las superficies de respuesta de los anovas obtenidos en StatGraphics 5.1, se realizo la optimizacion simultanea de las dos variables de respuesta. Usando el concepto de diseno desbalanceado se encontro el optimo global (45 oC, 8 L/min y 3 rpm), que coincide con el optimo observado.

Retrospective clinical study. To report the results of surgical correction achieved by intraoperative halo-femoral traction and posterior only pedicle screw instrumentation in severe scoliosis (scoliosis greater than 100 degrees ). Although previous reports show the effectiveness of preoperative halo traction in the treatment of severe spinal deformity, the intraoperative use of halo-femoral traction in conjunction with posterior pedicle screw instrumentation has never been reported in patients with severe spinal deformity. A total of 15 consecutive patients with severe (>100 degrees) thoracic idiopathic scoliosis and/or kyphoscoliosis operated by using intraoperative halo-femoral traction and posterior only pedicle screw instrumentation were included in the study. Subjects were analyzed by age at date of examination, gender, major coronal curve magnitude, major compensatory coronal curve magnitude, major sagittal curve magnitude, shoulder imbalance, and preoperative vital capacity of the lungs. Halo-traction related complications and short- and long-term complications were noted in each case. The average age at the time of surgery was 17.8 years (range, 16-19). There were 4 males and 11 females. The average improvement was 51% in the major thoracic curve, 33% in the compensatory lumbar curve, and 53% in the major sagittal curve. The average follow-up was 56 (range, 24-96) months. Loss of correction averaged 4 degrees for major thoracic curves and 2 degrees for thoracic kyphosis based on measurements at the final follow-up date. The use of intraoperative halo-femoral traction together with the wide facet resection and posterior release gradually provide a good correction and balance maintained by pedicle screw instrumentation. Intraoperative halo-femoral traction not only elongates spinal column but also elongates the thoracic cavity improving the compromised pulmonary function.

As a fastener type, the galvanized annular ring nails are common in timber engineering. Nowadays, partially resin or fully phosphate coated annular nails are used as well. In this study, the withdrawal resistance of those nails, whose holding capacities have not been involved in the current literature, is investigated comparing with other nail types (galvanized annular and helical nails) and wood screw via experimental test results on cross-laminated timber (CLT) specimens. Each single fastener was driven perpendicularly into the surface (side face) of CLT specimen as in the wall-floor angle bracket connections. Not only the numerical values of holding capacity but also the load-displacement curves are focused in the experimental tests. Furthermore, the withdrawal energy during the pull-out of single fastener, which is not investigated so far but may have highly significant implications for metallic connections of CLT panels, was evaluated graphically. The validity of the current withdrawal models in the literature is verified by the experimental results for the nail types under consideration. Moreover, the effects of the parameters such as grain pattern, manual/gun-drive conditions are addressed in this study as well.

This girl had a history of posterior fossa decompression for Chiari malformation Type I when she was 22 months of age. When she was 6 years old she presented with neck pain on flexion and extension of her head. Magnetic resonance imaging in flexion and extension ...

Wood is a renewable source of structural material with high relative strength/weight, low energy production, which kidnaps and stores carbon in its production. The large use of wood is due to its special qualities as raw material for other products manufactured in residential construction or major works such as bridges, has been widely used in roofing for industrial and commercial buildings. Commercially there are limitations on the length of the wood, resulting from the extraction of tree trunks, thus requiring the adoption of binding elements is the use of self-tapping screws efforts required by side and which can be axial, shear, tensile or compression. Whereas in Brazil does not yet exist and the promising future of the product, this research aims to study the behavior of self-tapping screws together with Brazilian reforestation species of Pinus oocarpa and Lyptus (softwood and hardwood). Rothoblaas self-tapping screws had a good penetration in both woods without requiring pre-d...

The aim of this prospective study was to investigate and compare the results of treatment of femoral neck nonunions using a sliding compression screw (SCS) with and without subtrochanteric valgus osteotomy (SVO). Thirty-two consecutive patients with femoral neck nonunions, which sustained no osteonecrosis of the femoral head based on bone scan study, were prospectively treated with SCS with (21 patients) or without (11 patients) SVO. The indication for SCS with SVO was a femoral neck nonunion with leg shortening of more than 1.5 cm. SCS without SVO was for leg shortening of less than 1.5 cm. Seventeen patients with osteotomy and nine patients without osteotomy were followed for at least 2 years (range, 2-8 years). All femoral neck fractures healed, with a union period of 4.6+/-1.0 months (95% confidence interval, 4.1-5.1 months) for osteotomy cases and 4.6+/-1.1 months (95% confidence interval, 3.8-5.4 months) for nonosteotomy cases (p = 0.83). However, in the osteotomy group, two patients sustained osteonecrosis of the femoral head, and nonunion remained in 1 patient at the osteotomy site (complication rate, 18%; 3 of 17 patients). There were no complications in the nonosteotomy group (p = 0.26). The average lengthening achieved from osteotomy was 1.0 to 1.5 cm (p < 0.001). Using SCS without SVO to treat femoral neck nonunions can result in a very satisfactory outcome. It is thus preferred for indicated patients. SCS without SVO, however, cannot concomitantly correct a femoral neck shortening; furthermore, shortening may deteriorate because of a telescoping effect. For patients with evident shortening, therefore, combined SVO with SCS is more suitable.

ABSTRACT The motion of a rigid body is represented in every instant by rotation about, and translation along, an instantaneous screw axis known as the Mozzi axis. In this paper, the Mozzi axis concept is used to study the kinematics and handling properties of tilting vehicles. Slalom tests performed on the road with three vehicles (a super sport motorcycle, a touring motorcycle and a three-wheeled tilting vehicle) are analyzed, the angle of the Mozzi axis with the road plane and the trace of the Mozzi axis on the road plane are calculated. The influences of cone spacing and forward speed on these parameters are discussed. The geometric loci, which are described by the Mozzi trace and turn center when a tilting vehicle moves along a trajectory, are drawn and compared. The results show that the proposed method of analysis based on the Mozzi axis concept is effective in highlighting the features of slalom manoeuvres and can also be used to study other important manoeuvres.