To see the other types of publications on this topic, follow the link: Screw channel surface.
Journal articles on the topic 'Screw channel surface'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 41 journal articles for your research on the topic 'Screw channel surface.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Chayka, Yevgeniy, Viktor Zhurba, Natalia Krivtsova, Anna Khadzhidi, Pavel Voshchevoz, and Natia Ugrekhelidze. "Experimental study on vegetation removing from irrigation channels." E3S Web of Conferences 175 (2020): 09007. http://dx.doi.org/10.1051/e3sconf/202017509007.
Full textAbstract:
The parameters of the process of vegetation removing from the water surface have been justified. An experiment was conducted to determine the strength of the screw-type tool and matching the most appropriate parameters. It was established that the channel clean-up quality depends on the screw diameter. It was also investigated the influence of the screw rotation speed on the channel clean-up quality. The dependence of the cleanup quality on the flight screw pitch has been determined.
2
Kimura, Koichi, Yusuke Itamochi, and Hideki Tomiyama. "The Evaluation of Mixing Characteristics of Dulmage Screw." Advanced Materials Research 747 (August 2013): 769–72. http://dx.doi.org/10.4028/www.scientific.net/amr.747.769.
Full textAbstract:
The mixing performance of Dulmage screw was studied experimentally and numerically. In the experiment, Low density polyethylene and red colored mastebatch were mixed and extruded by using Dulmage screw or Full Flight screw. And then, the degree of color uniformity was measured on the cross-section of the extrudate. The masterbatch was distributed more uniformly on the cross-section of Dulmage screw than that of Full Flight screw. The degree of color uniformity for Dulmage screw was about two times higher than that for Full Flight screw. In the numerical analysis, the flow pattern of the masterbatch in the screw channel of Dulmage screw was visualized by means of particle tracking technique. The degree of the distribution of the masterbatch was quantified as the information entropy. The information entropy at the outlet of the screw changed periodically with the screw rotation speed. Furthermore, the masterbatch circulated between the screw surface and the barrel surface in the fin section, consequently the degree of the distribution of the masterbatch changed periodically. In case the masterbatch was distributed uniformly along the channel depth at the outlet of the fin section, the information entropy at the outlet of the screw became high. The result shows the mixing performance of Dulmage screw strongly related to the degree of the distribution of the masterbatch at the outlet of the fin section.
3
Xie, Peng Cheng, Gang Gou, Zhen Xing Wen, Yu Mei Ding, and Wei Min Yang. "Research on the Key Technology of Precision Injection Molding Equipment for Light Guide Plate." Advanced Materials Research 87-88 (December 2009): 306–10. http://dx.doi.org/10.4028/www.scientific.net/amr.87-88.306.
Full textAbstract:
The light guide plate is an important element of the LCD backlight module which demands a certain degree of transparency and uniformity of gray. The defects such as black spots and yellow surface appeared when the light guide plate was processed by domestic equipments. The main problem was caused by the plasticization unit. The Influencing factors of performance for polycarbonate (PC) special screw were discussed in this paper. The conveyance capacity of melt in the metering zone of injection screws with different flight width and channel depth was analyzed by POLYFLOW software. In order to obtain high surface hardness, corrosion resistance and smoothness of PC special screw, surface coating processing was the key point for injection molding light guide plate. Moreover, the peel strength of PC with different coating processing metallic block was tested and measured. he experimental results of the analysis showed that the nickel-tungsten alloy plating and physical vapor deposition can significantly improve stripping properties, corrosion resistance and smoothness. The influencing factors of coating and PC materials’ stripping were analyzed. Through industrial testing, the defective rate of light guide plate had been greatly reduced with physical vapor deposition compared to the screw with hard chromium plating.
4
Popa, Camelia Lacramioara, and Viorel Popa. "Graphic Method Profiling of the End Mill Cutter Generating the Screw Compressor Rotor." Applied Mechanics and Materials 658 (October 2014): 123–28. http://dx.doi.org/10.4028/www.scientific.net/amm.658.123.
Full textAbstract:
Helical rotors, components of screw compressors have different structural shapes: rotors circular front section, rotors elliptic front section or asymmetric rotors. Manufacturing rotors involves profiling a tool bordered by a revolution surface, enveloping of each helical channel. This paper proposes a method developed in AutoCAD, in order to determine the profile of end mill cutter which generates the helical channel. Graphic method is based on the principle of complementary theorems' "Substitute Circles Family Method" component of envelope surfaces theory.
5
Biyani, Rashmi, Mohsin Ali, Donald Belles, and John M. Powers. "Effect of Metal Extension of Crown in the Screw Access Channel of a Posterior Implant Abutment on the Retention of Cement Retained Prosthesis." Journal of Oral Implantology 41, no. 5 (October 1, 2015): 537–41. http://dx.doi.org/10.1563/aaid-joi-d-13-00072.
Full textAbstract:
Purpose: Reducing the height of the implant abutment due to limited interarch space decreases the surface area for retention of cemented restorations. The purpose of this in vitro study was to see whether engaging the screw access channel with metal extension compensates for the loss of retention of posterior crowns cemented on shorter abutments. Material and Methods: Four identical prefabricated abutments were mounted on implant replicas embedded in acrylic resin blocks. Three of these abutments were reduced in height by 1 mm, 2 mm, and 3 mm respectively and one was left unmodified. Two sets of base metal crowns were fabricated for each abutment, one without and one with the metal extension inside the screw access channel. The crowns were cemented using Tempbond NE. The tensile forces required to separate the cemented crowns from abutments were measured using an Instron testing machine. Statistical analysis of the data was performed using a 2-way analysis of variance and Fisher's protected least significant difference at 0.05 level of significance. Results: An increase of 24% to 261% in retentive forces was observed for the group having metal extension in the screw access channel. Statistically significant differences (P < .001) were found among 2 types of crowns and four heights of abutments. Generally, the retentive forces were reduced in magnitude as the abutment height was reduced. Conclusion: The retention of a casting cemented to posterior implant abutments is influenced by the height of the abutment and the metal extension engaging the screw access channel. The crowns made with a metal extension showed superior retention values.
6
Schoenbaum, Todd R., Yi-Yuan Chang, and Richard G. Stevenson. "Screw Access Mark for Cemented Implant Crowns: A Universal Technique to Simplify Retrievability." Journal of Oral Implantology 44, no. 1 (February 1, 2018): 71–73. http://dx.doi.org/10.1563/aaid-joi-d-17-00147.
Full textAbstract:
The use of cemented implant prostheses for partially edentulous patients continues to increase in clinical practice. One of the primary complications of the cemented implant crown is difficulty in retrieval, should the need arise. Drilling through most prosthetic materials is of little difficulty for most clinicians, but the complication lies in determining where exactly the access hole needs to be drilled. During fabrication, the location of the screw access channel is marked with a strong contrasting color stain on the surface of the prosthesis. The technique proposed here marks the location of the screw access directly on the prosthesis, thus improving the ease and predictability of future retrieval.
7
Saninsky, V. A., E. A. Fedyanov, and E. N. Nesterenko. "CALCULATION OF PARAMETERS OF CHANNEL THROTTLING OF EXPENSIVE ELEMENTS OF FIRMWARE." IZVESTIA VOLGOGRAD STATE TECHNICAL UNIVERSITY, no. 8(243) (August 28, 2020): 50–53. http://dx.doi.org/10.35211/1990-5297-2020-8-243-50-53.
Full textAbstract:
The article considers possible options for supplying coolant to the cutting and deforming teeth of multi-pronged firmware for processing deep holes. The advantages and disadvantages of each scheme are indicated. It is noted that when the lubricant-cooling liquid (coolant) is pushed through straight or screw slotted grooves made on the outer surface of the mandrel teeth, "damping pads" are created on the surface to be processed, which improve the mandrel process and reduce wear of the stitches for processing deep holes. For each of the schemes, a method for calculating the coolant flow rate is described, depending on the parameters of the slotted grooves for the coolant flow and the pressure of its supply. The ability to calculate the consumption of coolant through the cutting and deforming teeth of multi-toothed stitches allows you to correctly assign processing modes and, thereby, increase the technical and economic efficiency of mechanical processing of long pipe blanks.
8
Zitzenbacher, G., and G. R. Langecker. "A New Plasticating Model for Amorphous and Semi-crystalline Polymers in Single Screw Extruders." International Polymer Processing 20, no. 4 (August 1, 2005): 360–68. http://dx.doi.org/10.1515/ipp-2005-0064.
Full textAbstract:
Abstract Polymeric thermoplastic materials can be subdivided in amorphous and semi-crystalline ones. In contrast to semi-crystalline polymers amorphous thermoplastic materials have no defined phase transition and hence no melt enthalpy. The glass transition region describes the change of the material behaviour from the state of a rubber like to an under-cooled fluid (glassy state). Setting the melt enthalpy in the Stefan-Neumann problem zero gives no valid results for the solid bed profile. Thus this condition is unsuitable for describing the plasticating process of amorphous polymers. In this paper a new model for the plastication of amorphous and semi-crystalline polymers in single screw extruders is presented. Therefore a new calculation method for the determination of the moving velocity between the glassy solid bed and the softened film region on the barrel surface is developed. The whole enthalpy to heat up the polymer on a critical flow temperature in the screw channel is considered.
9
Zhelykh, Vasyl, Malgorzata Ulewicz, Krystyna Kozak, Olena Savchenko, and Mariana Kasynets. "Analysis of the Influence of the Heat-Absorbing Surface of an Air-Cooled Solar Collector on its Thermal and Mechanical Properties." System Safety: Human - Technical Facility - Environment 1, no. 1 (March 1, 2019): 481–89. http://dx.doi.org/10.2478/czoto-2019-0062.
Full textAbstract:
AbstractThis paper presents the analysis of existing forms of heat absorbing surfaces of air solar collectors, which gained the greatest popularity in the world. The obtained data allowed to conclude that there is a need for the development of solar collectors with air as a coolant with an improved form of heat absorber, which will reduce the operational and capital costs of solar systems and allow the efficient use of such structures in a moderate climate without additional mechanisms for the transfer of coolant. The use of computer simulation helped to compare the thermal characteristics of air-borne solar collectors of a different design. The substantiation of the expediency of installing as a heat absorber of flow turbulators in the form of a screw has been fulfilled, as well as the height of the air channel of the solar collector has been determined, in which the maximum heating of the transfer medium is observed. In addition, the loss of pressure in the air channel of the solar collector with flow turbulators was determined and the comparison of the obtained data with the values of pressure losses in the air collector of the matrix type and the air collector with V-shaped ribs was made.
10
Фоменко, Екатерина, Ekaterina Fomenko, Альберт Нугманов, and Albert Nugmanov. "Velocity Control of Visco-Elastic Materials Movement in the Cylindrical Channel of the Grinder Feed Screw of the Former." Food Processing: Techniques and Technology 49, no. 1 (June 26, 2019): 113–19. http://dx.doi.org/10.21603/2074-9414-2019-1-113-119.
Full textAbstract:
The present research features the problems of wheat processing. Wheat processing has its own specific features. For instance, the process of gluten extrusion forming is very complex since it is associated with the visco-elastic and adhesive properties of raw gluten. The article discusses the results of applying the numerical finite difference method to the Navier-Stokes equation in the case of the one-dimensional problem when a cooled viscoelastic material has to pass through circular nozzles. The paper also features the obtained surface model of velocity evolution and some averaged results for the possible automation of the process. The viscosity properties of raw gluten are variable and depend on temperature, chemical composition, and properties of the raw material. Modeling makes it possible to characterize the properties of the material and its behavior in various situations. Such research demands neither additional time nor significant costs. The authors identified patterns of movement for raw gluten in the extrusion molding unit and selected the most appropriate automation system to control the speed of its movement to the molding assembly in the grinder feed screw. The significance of the research is obvious for subsequent physical and mathematical modeling of heat and mass transfer processes of vacuum freezing and drying and granulating of gluten extrusions. The results of the research presented in the article are consistent with the available information on this topic. The present approach to solving the problem of choosing the best rational hydrodynamic regimes was applied due to the complexity of the experimental determination of velocity fields and the difficulty of analyzing the Navier-Stokes system of hydrodynamic differential equations with variable proportionality coefficients.
11
Beglyakov, V. Yu, V. V. Aksenov, I. K. Kostinets, and A. A. Khoreshok. "LOAD DIAGRAMS FOR MODELING THE PROCESS OF INTERACTION OF EXTERNAL GEOKHOD MOVE WITH A AROUND CONTUR MASSIVE ROCKS." Mining science and technology, no. 3 (February 28, 2018): 3–10. http://dx.doi.org/10.17073/2500-0632-2017-3-3-8.
Full textAbstract:
Among the reliable tunneling complexes, without which it is impossible to create conditions for such a high-performance process, as mining of mine workings are geokhods. Since the geometric parameters of the external engine and the screw channel vary, the process of interaction of the geokhod systems with the geo- environment and with each other requires mathematical modeling. Modeling allows presenting schemes of interaction with various environments: loose (viscous-mobile) and strong. The mobility of the geoenvironment provides interaction along the entire supporting surface of the blade, so increasing the blade area leads to an increase in tractive effort. In strong rocks, the interaction occurs along the supporting surface of the blade, and the free surface may not touch the rock. Thus, in the interaction of the external propeller (HP) with the geoenvironment, the blade deforms; it is possible to form a region of crushing of the rock, and taking into account the elastic deformation in determining the geometric parameters of the blade and the canal will minimize the process of forming the region of crushing; when modeling the process of interaction of the VD with the medium, the load can be considered as uniformly distributed and equal to the ultimate strength of the rock for uniaxial compression.
12
Павленко, Дмитрий Викторович, Александр Федорович Тарасов, Ян Ефимович Бейгельзимер, and Виктор Юрьевич Коцюба. "КОНСТРУКТИВНІ АСПЕКТИ ПРОЕКТУВАННЯ ТА ЕКСПЛУАТАЦІЇ ОСНАЩЕННЯ ДЛЯ ГВИНТОВОЇ ЕКСТРУЗІЇ." Aerospace technic and technology, no. 8 (December 25, 2018): 42–53. http://dx.doi.org/10.32620/aktt.2018.8.07.
Full textAbstract:
The present paper introduces a twist extrusion (TE) process and special equipment capable of processing of round and prismatic bars with uniform deformation and reports analytical, and numerical modeling of the process. It is shown that the ability to treat round bars can be achieved by design of special off-axis TE dies in which the axis of the twist surface is displaced from the central axis of the bar being processed. Analytical model developed in the present study explains why using off-axis TE dies leads to uniform deformation and how this deformation uniformity depends on the die geometry. The main conclusions made upon analytical modeling are confirmed with complement finite element simulations. The simulations also show that the main deformation mode in off-axis TE is simple shear at the intersection planes between the twist and the straight channels of the die. Features of design and operation of dies for metal working with pressure from the point of view of design features and working conditions of equipment for severe plastic deformation of blanks by TE are considered. Based on the analysis of required modes of deformation of titanium and iron-nickel alloys, the require-ments for the construction of matrices, materials for their manufacture, lubricating-technological environments, as well as the working conditions of the twist matrices. Recommendations are proposed for the development of a rational design of technological equipment for deformation of blanks by twist extrusion in a batch production. On their basis, technical solutions and constructive measures to improve the design of the tooling for the process of twist extrusion of high-strength alloys for aircraft engineering are proposed. Examples of developed various structural schemes for the implementation of twist matrices are shown. It is shown that a matrix with grooves in a screw channel evolves into a promising construction of the matrix for the realization of screw extrusion of blanks of different sections. This allows to reduce friction between the blank, the counter-blanks and the matrix. The developed equipment for severe plastic deformation by TE can be used for technological processes of processing different aviation alloys and technological process of high-effectiveness titanium materials producing from powders.
13
Kosulin, Artem V., Dmitriy V. Elyakin, Kristina D. Lebedeva, Aleksandra E. Sukhomlinova, Ekaterina A. Kozlova, and Anna E. Orekhova. "Navigation template for vertebral pedicle passage in transpedicular screw fixation." Pediatrician (St. Petersburg) 10, no. 3 (August 13, 2019): 45–50. http://dx.doi.org/10.17816/ped10345-50.
Full textAbstract:
Transpedicular screw fixation is the most established means to stabilize the spine. Present study evaluates personalized navigation templates application for vertebral pedicle passage. Navigation templates were used for inserting 35 transpedicular screws in 5 patients with spinal deformity (age 2–16). Each patient underwent computed tomography preoperatively. Acquired data was processed into a virtual 3d-model of target zone. Life size virtual pedicular probes were placed onto transpedicular trajectories determined on multiplanar cross-sections of the model. Navigation template was created by modification and union of geometric primitives. Target zone model and navigation template were made with PLA by 3D-printer. In surgery the template was placed on skeletonized posterior surface of appropriate vertebrae. After confirmation of template stability trajectories were passed to a depth of 20 mm through guiding tubes by pedicular probe. Resulting channels were controlled with ball tip feeler, and the full depth trajectories were made by free hand technique. Postoperatively screws placement accuracy was assessed by plain X-rays in each patient. Two patients (16 screws) also underwent computed tomography. In these patients screw placement accuracy was assessed by system based on 2 mm breach increments. 15 screws (93. 7%) were fully contained within the pedicle (grade 0), 1 screw breached external cortex of the pedicle by 0. 8 mm (grade 1). Efficacy and safety of navigation template for transpedicular screws insertion was demonstrated.
14
Salunke, Pravin, Sameer Futane, Sushant K. Sahoo, Mandeep S. Ghuman, and Niranjan Khandelwal. "Operative nuances to safeguard anomalous vertebral artery without compromising the surgery for congenital atlantoaxial dislocation: untying a tough knot between vessel and bone." Journal of Neurosurgery: Spine 20, no. 1 (January 2014): 5–10. http://dx.doi.org/10.3171/2013.9.spine13491.
Full textAbstract:
Object Stabilization of the craniovertebral junction (CVJ) by using lateral masses requires extensive dissection. The vertebral artery (VA) is commonly anomalous in patients with congenital CVJ anomaly. Such a vessel is likely to be injured during dissection or screw placement. In this study the authors discuss the importance of preoperative evaluation and certain intraoperative steps that reduce the chances of injury to such vessels. Methods A 3D CT angiogram was obtained in 15 consecutive patients undergoing surgery for congenital atlantoaxial dislocation. The course of the VA and its relationship to the C1–2 facets was studied in these patients. The anomalous VA was exposed intraoperatively, facet surfaces were drilled in all, and the screws were placed according to the disposition of the vessel. Results A skeletal anomaly was found in all 10 patients who had an anomalous VA. Four types of variations were noted: 1) the first intersegmental artery in 5 patients (bilateral in 1); 2) fenestration of VA in 1 patient; 3) anomalous posterior inferior cerebellar artery crossing the C1–2 joint in 1 patient; and 4) medial loop of VA in 5 patients. The anomalous vessel was dissected and the facet surfaces were drilled in all. The C-1 lateral mass screw was placed under vision, taking care not to compromise the anomalous vessel, although occipital screws or sublaminar wires were used in the initial cases. A medial loop of the VA necessitated placement of transpedicular or C-2 lateral mass screws instead of pars interarticularis screws. The anomalous vessel was injured in none. Conclusions Preoperative 3D CT angiography is a highly useful method of imaging the artery in patients with CVJ anomaly. It helps in identifying the anomalous VA or its branch and its relationship to the C1–2 facets. The normal side should be surgically treated and distracted first because this helps in opening the abnormal side, aiding in dissection. In the posterior approach the C-2 nerve root is always encountered before the anomalous vessel. The defined vascular anatomy helps in choosing the type of screw. The vessel should be mobilized so as to aid the drilling of facets and the placement of screws and spacers under vision, avoiding its injury (direct or indirect) or compression. With these steps, C1–2 (short segment) rigid fusion can be achieved despite the presence of anomalous VA.
15
Floyd, Edward R., Nicholas I. Kennedy, Adam J. Tagliero, Gregory B. Carlson, and Robert F. LaPrade. "Complex Patellofemoral Reconstruction for Recurrent Instability." Video Journal of Sports Medicine 2, no. 1 (January 2022): 263502542110353. http://dx.doi.org/10.1177/26350254211035396.
Full textAbstract:
Background: Patellofemoral instability is due to a combination of bony and soft tissue factors. While recurrent patellar dislocations are rare, evaluation and treatment of these conditions require addressing patellar height and lateralization of the tibial tubercle (TT), restraint to lateral patellar subluxation, and trochlear dysplasia. Other factors to consider are coronal limb-length alignment outside of the physiologic 5 to 8° of valgus, which may significantly alter the Q angle and contribute to lateral instability. Other ligaments around the patella contribute to soft-tissue restraint, including the medial and lateral patellotibial ligaments, patellomeniscal ligaments, and the medial quadriceps tendon femoral ligament. Patellar tilt is assessed with and without quadriceps contraction to further evaluate the patella’s relationship to the trochlear groove. The Caton-Deschamps Index, as well as patellar trochlear index (PTI), are used to measure patellar height for patella alta or baja. Technique Description: The technique is to surgically manage a patient in neutral mechanical alignment on standing limb radiographs, with moderate-to-severe DeJour type B trochlear dysplasia and a trochlear sulcus angle of around 145°, patella alta with a Caton-Deschamps Index of 1.6 and PTI of 0.22, a TT to trochlear groove (TT-TG) distance of 8 mm, and a deficient medial patellofemoral ligament (MPFL). The MPFL reconstruction is done first, with harvesting of the ipsilateral quadriceps tendon and maintenance of its distal attachment on the superior patellar pole. The quadriceps tendon graft is folded medially upon its distal attachment and fixed in this position with suture anchors. Tibial tubercle osteotomy is accomplished by spacing drill holes 2 mm apart, medially and laterally, on the TT and connecting the drill holes with an osteotome and reciprocating saw. A distalized location to secure the TT is selected and superficial bone is excised. A medial parapatellar arthrotomy is performed, and bur attachments are used to drill into the subchondral bone beneath the femoral articular surface to create a V-shaped flap of trochlear cartilage. An arthroscope is inserted under the trochlear flap during this process to visualize the appropriate depth. The trochlear flap is then secured with screws passed over guide pins to secure the flap to the desired location. Cannulated screws and washers are then used to secure the TT to its distalized and/or medialized position, with fluoroscopic verification of screw depth and location. The arthrotomy is then closed with the knee at 45°. The quadriceps graft is passed through a subretinacular channel and secured with suture anchors, adjacent to the adductor tubercle, to complete the MPFL reconstruction. Before closure, appropriate tracking and translation of the patella is verified. Results: Sulcus-deepening trochleoplasty, with or without MPFL reconstruction, has been reported to obtain satisfactory outcomes at 2 years, with close to 85% return to sport and 100% return to work, with improvements in International Knee Documentation Committee (IKDC) scores from 50.8 to 79.1 in some studies. MPFL reconstruction with tibial tubercle osteotomy (TTO) has yielded a 94.5% patient satisfaction rate in the literature. Discussion/Conclusion: In patients with recurrent patellar instability and DeJour types B-D trochlear dysplasia, MPFL reconstruction with TTO and sulcus-deepening trochleoplasty provides excellent subjective outcomes and restores patellar tracking with elimination of recurrent subluxation.
16
Bansal, Puneet, Vijay Mishra, Yashmi Jaiswal, and Gourab Das. "Evaluation of Titanium Lag Screw Osteosynthesis in the Management of Mandibular Fractures." World Journal of Dentistry 8, no. 4 (2017): 315–20. http://dx.doi.org/10.5005/jp-journals-10015-1457.
Full textAbstract:
ABSTRACT Introduction The management of facial trauma is one of the most important and demanding aspects of maxillofacial surgery. Mandible is the most movable and prominent bone of facial skeleton. The management of the injuries to the maxillofacial complex remains a challenge for oral and maxillofacial surgeons. The aim of mandibular fracture treatment is the restoration of anatomical form and function with particular care to establish occlusion. The lag screw technique was first introduced to maxillo facial surgery by Brons and Boering in 1970, who cautioned that at least two lag screws are necessary to prevent rotational movement of the fragments in oblique fractures of mandible. Aim The aim of the study was to evaluate the outcome of lag screw osteosynthesis in the management of mandibular body, symphysis, and parasymphysis fractures. Materials and methods About 15 cases presenting with mandibular oblique, sagittally displaced mandibular fractures, and requiring open reduction and internal fixation (ORIF) were selected. Titanium lag screws were placed in such a way that their axes bisect the angle between a perpendicular drawn to the fracture line and perpendicular to the bone surface. About 3 months postoperatively, follow-up was done to evaluate the duration of surgery intraoperatively, stability of fracture segments, occlusion, biting efficiency postoperatively, and record any postoperative complications with lag screw fixation technique. Results The maximum intraoperative time was 120 minutes and minimum was 40 minutes. The average intraoperative time was 72 minutes. In postoperative complications, deranged occlusion was seen in two patients; in one patient, it was due to associated condylar fracture and technical error in the placement of lag screw in another patient; but, it was not significant statistically with a p-value of 0.483 and which was managed easily by placing guiding elastics for 2 weeks in both patients. All the patients in the study showed good stability of fixation and significant increase in biting efficiency over a period of time. No postoperative complications, such as lag screw exposure, neurosensory disturbance, and malunion/nonunion were seen in any of the patients. Conclusion Titanium lag screw fixation was found to have good stability, rigidity, was inexpensive, and less time consuming in some types of mandibular fractures, though there exist few contraindications regarding its usage. This technique is a very sensitive procedure, requiring strict adherence to the lag screw placement principle and sufficient knowledge about the surgical anatomy of the mandible. Clinical significance Fixation of the anterior mandible fracture using this technique can achieve good stability and appropriate compression. The technique reduces the chances of infection due to less exposure and promotes the healing process by producing stress in the fracture lines. Lag screw showed faster improvement in terms of biting efficiency and a significant reduction in fracture gap, which is not seen in miniplate fixation. How to cite this article Bansal P, Kumar S, Mishra V, Jaiswal Y, Das G. Evaluation of Titanium Lag Screw Osteosynthesis in the Management of Mandibular Fractures. World J Dent 2017;8(4):315-320.
17
Vijimohan, Suganth Jayaraman, Syed Haque, and David Ellis. "An Alternate Technique of Applying Lag Screw for Fixation of Distal Fibula Fracture: Posterior to Anterior Interfragmentary Compression Screw." Foot & Ankle Specialist 10, no. 6 (September 12, 2017): 555–59. http://dx.doi.org/10.1177/1938640017729495.
Full textAbstract:
Ankle fractures are one of the most common lower limb fractures, representing a significant portion of the trauma workload. Marked proportion of these is isolated intraarticular lateral malleolus fractures. Anatomical reduction and rigid internal fixation using lag screw (interfragmentary screw) to provide interfragmentary compression has remained the choice of treatment in selected lateral malleolus fractures. Applying interfragmentary compression screw from anterior to the posterior surface of the fibula has been the traditional method of performing this. In this article, we describe an alternate method of applying posterior-anterior interfragmentary compression screw to the fibula fractures. We will also discuss the benefits it provides such as minimizing the chances of hardware-related peroneal tendon irritation. Further argument will focus on the mechanical benefit this will render while providing equal clinical outcome of the time tested anterior-posterior interfragmentary compression screw. Levels of Evidence: Level V: Therapeutic comparison
18
Chen, Ping, Shu Min Zhou, and Xue Qian Xu. "Elastoplastic Analysis and Optimization Design for the Tube Channel End of Screw Lock Closure Type Heat Exchanger." Applied Mechanics and Materials 741 (March 2015): 119–25. http://dx.doi.org/10.4028/www.scientific.net/amm.741.119.
Full textAbstract:
With the usage of the FEM software ANSYS, an axisymmetric model for the tube channel end of a screw lock closure type heat exchanger was built. The elastic and elastoplastic stress analyses were carried out. The variations of the stress distribution at the root of threads and the contact pressure on threads engaged surfaces were invesgated. Furthemore, an optimization design based on the elastic model for this type heat exchanger was also conducted in order to obtain reasonable structure dimensions and make full use of materials.
19
GENG, Y. L., and Z. H. SUN. "GROWTH MODES AND DEFECTS OF MANGANESE MERCURY THIOCYANATE CRYSTALS OBSERVED BY AFM." Surface Review and Letters 16, no. 01 (February 2009): 19–22. http://dx.doi.org/10.1142/s0218625x09012238.
Full textAbstract:
Growth mechanisms and defects formation of the manganese mercury thiocyanate (MMTC) crystal have been investigated by atomic force microscopy (AFM). Both screw dislocation controlled growth and 2D nucleation growth occur on the {110} faces. Stacking faults are observed among dislocation hillocks and the formation of them probably results from the different crystallization orientations of different spirals. Hollow channels are found around the nucleation islands and the formation of them is due to the instability of the interface generated by the rapid nucleation and growth speeds.
20
Michelangelli, O. P., M. Yamanoi, A. Gaspar-Cunha, and J. A. Covas. "Modelling pellet flow in single extrusion with DEM." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 225, no. 4 (October 5, 2011): 255–68. http://dx.doi.org/10.1177/0954408911418159.
Full textAbstract:
Plasticating single-screw extrusion involves the continuous conversion of loose solid pellets into a pressurized homogeneous melt that is pumped through a shaping tool. Traditional analyses of the solids conveying stage assume the movement of an elastic solid plug at a fixed speed. However, not only the corresponding predictions fail considerably, but it is also well known that, at least in the initial screw turns, the flow of loose individual pellets takes place. This study follows previous efforts to predict the characteristics of such a flow using the discrete element method. The model considers the development of normal and tangential forces resulting from the inelastic collisions between the pellets and between them and the neighbouring metallic surfaces. The algorithm proposed here is shown to be capable of capturing detailed features of the granular flow. The predictions of velocities in the cross- and down-channel directions and of the coordination number are in good agreement with equivalent reported results. The effect of pellet size on the flow features is also discussed.
21
Jiang, X. N., and D. Xu. "Surface morphology and defect formation of the {100} face of ZnCd(SCN)4crystals investigated by AFM." Journal of Applied Crystallography 36, no. 6 (November 15, 2003): 1448–51. http://dx.doi.org/10.1107/s0021889803022738.
Full textAbstract:
Surface morphology and defect formation of the prismatic {100} face of ZCTC crystals were investigated by atomic force microscopy (AFM). Both screw-dislocation-controlled growth and two-dimensional nucleation growth occur on the face at a supersaturation of 0.03. Steps advance with strong kinetic anisotropy along theb-axis direction, probably because different parts of the ZCTC molecules are exposed along different crystallographic directions. By comparing heights of elementary steps with the structure of the ZCTC crystal, it is deduced that the growth of ZCTC crystals occurs mostly by direct incorporation of monomers or dimers of ZCTC molecules into the crystal. Defects of hollow channels, negative crystals and cracks that are oriented preferentially along the direction of theborcaxis were observed. The formation of the defects is mainly related to the growth mechanism and structural features of the ZCTC crystal.
22
Dohotaru, Ion, and Maxim Casian. "Geometric Aspects and Particularities in the Functioning of a Reductor with Balls." Applied Mechanics and Materials 657 (October 2014): 500–503. http://dx.doi.org/10.4028/www.scientific.net/amm.657.500.
Full textAbstract:
Benefits of mechanism with balls are to promote their interests in different aspects in different fields of modern technology. May be remarked considerable success in screws with balls, guides, couplings etc. Are in the ascendancy searches for optimal solutions in speed-reducers with balls. One of the possible contributions to the research for technical solutions in this area is presented below. It shows the geometric particularities and configuration of a spherical ball transmission, constructive modeling and simulation of function. On an outside spherical surface of one wheel there is a sine wave path ball race. The second wheel has on an internal surface longitudinal inclined channels in which the balls are located.
23
Lim, Ji Hwan, and Minkyu Park. "Study on onset of nucleate boiling with screw tube for fusion reactor application." Nuclear Fusion 62, no. 3 (January 18, 2022): 036003. http://dx.doi.org/10.1088/1741-4326/ac44ae.
Full textAbstract:
Abstract The onset of nucleate boiling (ONB) is the point at which the heat transfer mechanism in fluids changes and is one of the thermo-hydraulic factors that must be considered when establishing a cooling system operation strategy. Because the high heat flux of several MW m−2, which is loaded within a tokamak, is applied under a one-side heating condition, it is necessary to determine a correlative relation that can predict ONB under special heating conditions. In this study, the ONB of a one-side-heated screw tube was experimentally analyzed via a subcooled flow boiling experiment. The helical nut structure of the screw tube flow path wall allows for improved heat transfer performance relative to plain tubes, providing a screw tube with a 53.98% higher ONB than a plain tube. The effects of the system parameters on the ONB heat flux were analyzed based on the changes in the heat transfer mechanism, with the results indicating that the flow rate and degree of subcooling are proportional to the ONB heat flux because increasing these factors improves the forced convection heat transfer and increases the condensation rate, respectively. However, it was observed that the liquid surface tension and latent heat decrease as the pressure increases, leading to a decrease in the ONB heat flux. An evaluation of the predictive performance of existing ONB correlations revealed that most have high error rates because they were developed based on ONB experiments on micro-channels or plain tubes and not under one-side high heat load conditions. To address this, we used dimensional analysis based on Python code to develop new ONB correlations that reflect the influence of system parameters.
24
Irmak, Rafet, Ahsen Irmak, and Gökhan Biçer. "Quadriceps Muscle Mechanical Simulator for Training of Vastus Medialis Obliquus and Vastus Lateralis Obliquus Mechanical Properties." Orthopaedic Journal of Sports Medicine 2, no. 11_suppl3 (November 1, 2014): 2325967114S0016. http://dx.doi.org/10.1177/2325967114s00166.
Full textAbstract:
Objectives: In classical anatomy quadriceps muscle has four heads. Clinical studies have demostrated 6 heads of this muscle. These heads were demostrated seperately not only by their functional properties,but also by innervation and kinesiological properties. In our previous study we have developed and demostrated electrophysiological properties of vastus medialis obliquus by an electronic patient simulator. The purpose of this study is to develop a mechanical simulator which can be used to demostrate mechanical properties of 6 heads of quadriceps muscle and the screw home mechanism. Methods: Quadriceps femoris muscle has 6 heads: rectus femoris, vastus intermedius, vastus medialis obliquus, vastus medialis longus, vastus lateralis obliquus and vastus lateralis longus. The fundamental mechanical properties of each head is seperated by insersio and angle of pull. Main design principle was to demostrate all heads with insersio and angle of pull properties. Second design principle was to demostrate the screw-home mechanism which is the result of difference in articular surfaces of medial and lateral of condyles of femur. Results: Final design of the simulator consists of three planes for demostration of angle of pull and pulling forces (patellar plane, proximal and distal planes) of each heads. On each plane channels were graved as origo and insersio for demostration of angle of pull. Distal plane was movable for demostration of pulling forces in different angels of knee flexion and extention. Also proximal plane was adjustable to demostrate different sitting and standing positions. Srew home mechanism was demostrated by specially designed hingle mechanism. Left and right side hingle mechanisms have different radii as femoral condyles and this difference can cause rotation in terminal extension as in the screw home mechanism. Conclusion: Vastus medialis obliquus, vastus lateralis obliquus and screw-home mechanism have clinical significance. We were not able to find any study which deals with training of screw home mechanism and vastus medialis obliqus and wastus lateralis obliquus muscles in the literature. The purpose of this study was to develop a simulator which can demostrate mechanical properties of vastus medialis obliquus and vastus lateralis muscles and screw home mechanism. As a result a traning simulator with stated properties was developed. In this simulator force measurement is acheived with analog dynamometers and future studies may focus on improvement of this simulator with digital force measurement.
25
Sanaboyina, Appala Raju, and Saraswathi Venkata Avula. "A Prospective Study of Management of Fracture Dislocation of Hip (PIPKIN) by Safe Surgical Dislocation (2 Years 6 Months Follow-Up in a Tertiary Hospital at Visakhapatnam)." Journal of Evidence Based Medicine and Healthcare 8, no. 26 (June 28, 2021): 2248–52. http://dx.doi.org/10.18410/jebmh/2021/420.
Full textAbstract:
BACKGROUND High velocity motor vehicle injuries are associated with hip fracture dislocations especially dash board injuries. Most commonly posterior hip dislocations are associated with occasional femoral head fractures. Computerized tomographic imaging is done to look at the congruency of the hip joint. Safe surgical dislocation or Ganz approach was described in 2001 for exposing the hip in a 360-degree view without damaging the vascularity of the femoral head. In this study, we wanted to evaluate the radiological and functional outcome using modified Merle d' Aubigne-Postel and Harris hip scoring. METHODS The current study is a prospective study in a tertiary referral centre where 8 young adult males were followed up for a period of 2 years 6 months from August 2018 to February 2021 after safe surgical dislocation and reduction with headless Herbert screws to maintain congruent hip surface. RESULTS We had 1 patient with associated chest injury requiring intercostal tube placement, while none of them had developed avascular necrosis or early arthritis. We had used modified Merle d'Aubigne-Postel and Harris hip scoring to assess the functional outcome. We had six patients with excellent results and two patients with good outcome due to occasional pain. We followed all the patients for more than 2 years. We evaluated the radiological and functional outcomes. The results are comparable to other researcher’s studies. CONCLUSIONS Safe surgical dislocation is a very good choice for fixation of femoral head fractures where the complications like early arthritis of femoral head and acetabulum are less along with preserving the vascularity of the femoral head and preventing the chances of avascular necrosis of femoral head. It also provides a good intraoperative view for handling the fracture reduction. KEYWORDS Pipkin Fracture, Ganz Approach, Safe Surgical Dislocation Hip, Herbert Screw
26
Gao, Xiangsheng, Kuan Zhang, Min Wang, Tao Zan, Peng Gao, and Chaozong Liu. "Optimization of nano coating to reduce the thermal deformation of ball screws." Nanotechnology Reviews 11, no. 1 (January 1, 2022): 438–51. http://dx.doi.org/10.1515/ntrev-2022-0029.
Full textAbstract:
Abstract To reduce the thermal deformation of ball screws, the process of nano coating preparation for coating on ball screws to reduce temperature rise and thereby thermal deformation was discussed in this article. Simultaneously, the cooling mechanism was presented. The thermal channels and the relatively even distribution of graphene in the nano coating were observed in scanning electron microscopic images. In terms of the preparation of nano coating, optimization design was carried out to obtain the optimized material ratio and nozzle flow through orthogonal experiment. The influence of design parameters of nano coating on reducing thermal deformation was also discussed. The experimental results show that the maximum temperature rise, thermal deformation, and time to reach thermal balance decreased by 12.5, 69.1, and 46.3%, respectively. The effectiveness of nano coating in reducing thermal deformation was validated experimentally.
27
Gobbi, Mauro, Francesco Ballarin, Chiara Compostella, Valeria Lencioni, Roberto Seppi, Duccio Tampucci, and Marco Caccianiga. "Physical and biological features of an active rock glacier in the Italian Alps." Holocene 24, no. 11 (August 12, 2014): 1624–31. http://dx.doi.org/10.1177/0959683614544050.
Full textAbstract:
We report on the key physical features of an active rock glacier that influence the distribution of plants and arthropods. We also perform a comparison with neighboring scree slope and alpine grassland to test whether the environmental features of the rock glacier drive the presence of specific species assemblages. Compared with scree slope and grassland, the studied rock glacier provides particular physical features that determine the presence of unique species. Plant distribution is mainly driven by grain size. Arthropod distribution is linked to grain size, with cold-adapted species found on areas with coarse-grained deep debris, which also shows a distinctive temperature regime with very low values throughout the year. On the basis of these findings, we advance the hypothesis that rock glaciers provide specific ecological conditions creating potential refugia for cold-demanding species during warm climatic periods.
28
Brown, Lee E., and David M. Hannah. "Alpine Stream Temperature Response to Storm Events." Journal of Hydrometeorology 8, no. 4 (August 1, 2007): 952–67. http://dx.doi.org/10.1175/jhm597.1.
Full textAbstract:
Abstract Despite continued interest in meteorological influences on the thermal variability of river systems, there are few detailed studies of stream temperature dynamics during storm events. This paper reports high-resolution (15 min) water column and streambed temperature data for storm events of contrasting magnitude, duration, and intensity for three streams (draining glacier, snow, and groundwater sources) across an alpine river system during summers 2002 and 2003. The results demonstrate clear spatial and temporal differences in water column and streambed thermal responses to precipitation events and streamflow peaks. Analysis of all storms across the three sites showed a decrease in water column temperature for 75% of events, with significant negative relationships between stream temperature and precipitation magnitude, precipitation intensity, and stream discharge peaks. Temperature decreases of 10.4°C were recorded, but temperature increases were less marked at up to 2.3°C. Temperature response to precipitation was dampened with increasing depth into the streambed at all sites. Spatial and temporal differences in thermal response to storm events were controlled by precipitation and stream discharge peak characteristics (above) plus antecedent basin conditions, which together determine the nature and rapidity of hydrological response. In this steep alpine basin, stream temperature variability appears to be enhanced by quick routing of precipitation to the river channel (i.e., direct precipitation/channel interception, rapid surface flow over impermeable bedrock/thin alpine soils, and subsurface flow through highly weathered scree slopes). This research highlights the need for integrated hydrometeorological research of precipitation event–hydrological response–stream temperature interactions to advance understanding of runoff generation processes driving event-scale thermal dynamics in alpine and other river systems.
29
Archavlis, Eleftherios, Lucas Serrano, Eike Schwandt, Amr Nimer, Moisés Felipe Molina-Fuentes, Tamim Rahim, Maximilian Ackermann, Angelika Gutenberg, Sven Rainer Kantelhardt, and Alf Giese. "A novel minimally invasive, dorsolateral, tubular partial odontoidectomy and autologous bone augmentation to treat dens pseudarthrosis: cadaveric, 3D virtual simulation study and technical report." Journal of Neurosurgery: Spine 26, no. 2 (February 2017): 190–98. http://dx.doi.org/10.3171/2016.7.spine16244.
Full textAbstract:
OBJECTIVE The goal of this study was to demonstrate the clinical and technical nuances of a minimally invasive, dorsolateral, tubular approach for partial odontoidectomy, autologous bone augmentation, and temporary C1–2 fixation to treat dens pseudarthrosis. METHODS A cadaveric feasibility study, a 3D virtual reality reconstruction study, and the subsequent application of this approach in 2 clinical cases are reported. Eight procedures were completed in 4 human cadavers. A minimally invasive, dorsolateral, tubular approach for odontoidectomy was performed with the aid of a tubular retraction system, using a posterolateral incision and an oblique approach angle. Fluoroscopy and postprocedural CT, using 3D volumetric averaging software, were used to evaluate the degree of bone removal of C1–2 lateral masses and the C-2 pars interarticularis. Two clinical cases were treated using the approach: a 23-year-old patient with an odontoid fracture and pseudarthrosis, and a 35-year-old patient with a history of failed conservative treatment for odontoid fracture. RESULTS At 8 cadaveric levels, the mean volumetric bone removal of the C1–2 lateral masses on 1 side was 3% ± 1%, and the mean resection of the pars interarticularis on 1 side was 2% ± 1%. The median angulation of the trajectory was 50°, and the median distance from the midline of the incision entry point on the skin surface was 67 mm. The authors measured the diameter of the working channel in relation to head positioning and assessed a greater working corridor of 12 ± 4 mm in 20° inclination, 15° contralateral rotation, and 5° lateral flexion to the contralateral side. There were no violations of the dura. The reliability of C-2 pedicle screws and C-1 lateral mass screws was 94% (15 of 16 screws) with a single lateral breach. The patients treated experienced excellent clinical outcomes. CONCLUSIONS A minimally invasive, dorsolateral, tubular odontoidectomy and autologous bone augmentation combined with C1–2 instrumentation has the ability to provide excellent 1-stage management of an odontoid pseudarthrosis. The procedure can be completed safely and successfully with minimal blood loss and little associated morbidity. This approach has the potential to provide not only a less invasive approach but also a function-preserving option to treat complex C1–2 anterior disease.
30
Wilson, Peter, Peter J. Vincent, Matt W. Telfer, and Tom C. Lord. "Optically stimulated luminescence (OSL) dating of loessic sediments and cemented scree in northwest England." Holocene 18, no. 7 (November 2008): 1101–12. http://dx.doi.org/10.1177/0959683608093538.
Full text
31
Aree, Thammarat. "Inclusion Scenarios and Conformational Flexibility of the SSRI Paroxetine as Perceived from Polymorphism of β-Cyclodextrin–Paroxetine Complex." Pharmaceuticals 15, no. 1 (January 14, 2022): 98. http://dx.doi.org/10.3390/ph15010098.
Full textAbstract:
Depression, a global mental health problem, is prevalent during the coronavirus disease 2019 (COVID-19) pandemic and can be efficiently treated by selective serotonin reuptake inhibitors (SSRIs). Our study series aims at forwarding insights on the β-cyclodextrin (β-CD)–SSRI inclusion complexes by X-ray crystallography combined with density functional theory (DFT) calculation. Here, we report a new crystal form (II) of the 1:1 β-CD–paroxetine (PXT) complex, which is inspired by the reported 2:1 β-CD–PXT complex (crystal form I), reflecting an elusive phenomenon of the polymorphism in CD inclusion complexes. The β-CD–PXT polymorphism stems from the PXT conformational flexibility, which is defined by torsion angles κ, ε around the -CH2–O- group bridging the A- and C–D-rings, of which those of PXT in I and II are totally different. While PXT (II) in an open V-shaped conformation that has the B-ring shallowly inserted in the β-CD cavity, PXT (I) in a closed U-shaped structure is mostly entirely embedded in the β-CD dimeric cavity, of which the A-ring is deeply inserted in the main β-CD cavity. However, PXT molecules in both crystal forms are similarly maintained in the CD cavity via host–guest N–H···O5/O6 H-bonds and C/O–H···π(B/C) interactions and β-CDs have similar 3D arrangements, channel (II) vs. screw-channel (I). Further theoretical explorations on the β-CD–PXT thermodynamic stabilities and the PXT conformational stabilities based on their potential energy surfaces (PESs) have been completed by DFT calculations. The 2:1 β-CD–PXT complex with the greater presence of dispersion interactions is more energetically favorable than the unimolar complex. Conversely, whereas free PXT, PXT (II) and PXT in complex with serotonin transporter are more energetically stable, PXT (I) is least stable and stabilized in the β-CD cavity. As SSRIs could lessen the COVID-19 severity, the CD inclusion complexation not only helps to improve the drug bioavailability, but also promotes the use of antidepressants and COVID-19 medicines concurrently.
32
Attal, M., S. M. Mudd, M. D. Hurst, B. Weinman, K. Yoo, and M. Naylor. "Impact of change in erosion rate and landscape steepness on hillslope and fluvial sediments grain size in the Feather River basin (Sierra Nevada, California)." Earth Surface Dynamics 3, no. 1 (March 25, 2015): 201–22. http://dx.doi.org/10.5194/esurf-3-201-2015.
Full textAbstract:
Abstract. The characteristics of the sediment transported by rivers (e.g. sediment flux, grain size distribution – GSD) dictate whether rivers aggrade or erode their substrate. They also condition the architecture and properties of sedimentary successions in basins. In this study, we investigate the relationship between landscape steepness and the grain size of hillslope and fluvial sediments. The study area is located within the Feather River basin in northern California, and studied basins are underlain exclusively by tonalite lithology. Erosion rates in the study area vary over an order of magnitude, from >250 mm ka−1 in the Feather River canyon to <15 mm ka−1 on an adjacent low-relief plateau. We find that the coarseness of hillslope sediment increases with increasing hillslope steepness and erosion rates. We hypothesise that, in our soil samples, the measured 10-fold increase in D50 and doubling of the amount of fragments larger than 1 mm when slope increases from 0.38 to 0.83 m m−1 is due to a decrease in the residence time of rock fragments, causing particles to be exposed for shorter periods of time to processes that can reduce grain size. For slopes in excess of 0.7 m m−1, landslides and scree cones supply much coarser sediment to rivers, with D50 and D84 more than one order of magnitude larger than in soils. In the tributary basins of the Feather River, a prominent break in slope developed in response to the rapid incision of the Feather River. Downstream of the break in slope, fluvial sediment grain size increases, due to an increase in flow competence (mostly driven by channel steepening) as well as a change in sediment source and in sediment dynamics: on the plateau upstream of the break in slope, rivers transport easily mobilised fine-grained sediment derived exclusively from soils. Downstream of the break in slope, mass wasting processes supply a wide range of grain sizes that rivers entrain selectively, depending on the competence of their flow. Our results also suggest that, in this study site, hillslopes respond rapidly to an increase in the rate of base-level lowering compared to rivers.
33
Ivanov, Pavel A., Aleksandr V. Kasatskiy, Nikita N. Zadneprovskiy, and Aleksandr V. Nevedrov. "A New Method of Intraoperative Reposition and Holding of Bone Fragments with Ty-Raps." Traumatology and Orthopedics of Russia 27, no. 4 (December 29, 2021): 93–98. http://dx.doi.org/10.21823/2311-2905-1664.
Full textAbstract:
Background. The quality of fractures reposition in open osteosynthesis is one of the important factors determining the outcome of treatment. Often, the reposition and fixation of bone fragments is not an easy task. The authors propose a method of reposition and temporary fixation of fragments using plastic ty-raps used in electrical work. The aim of the study is to demonstrate the possibilities of new method of intraoperative reposition and fixation of bone fragments using plastic ty-raps. Materials and Methods. Ty-raps were sterilized before the surgery in the modes intended for the preparation of polymer products. After the fragments were dissected, their reposition and fixation are carried out with the help of clamps and bone clamps. At this stage, there is a need for the use of ty-raps, since the bone clamps prevent the plate from laying on the bone. To do this, 3-4 plastic ty-raps were applied to the areas of bone free from bone clamps in the area of the fragments contact. In those places where an intact periosteum and muscles are attached to the fragment, narrow transverse channels in soft tissues are formed with the instrument to wrap the bone with a ty-rap. Then the free end of the ty-rap is passed through its lock and tightened as much as possible. After tightening all the ty-raps, the bone clamps are removed. The applied ty-raps reliably keep the bone fragments from any displacement, even when the segment rotates. A bone plate is placed on the bone surface with tightened ty-raps. Then the plate fixed to the bone with screws. The plate should be placed on the bone without strong pressing, which allows you to remove the ty-raps from under the plate at any stage of osteosynthesis. The ty-raps are removed by cutting them with a scalpel or snacking with wire cutter, then the plate is fixed to the bone with the remaining screws. Conclusion. Ty-raps have many positive properties: they are affordable, cheap, do not lose their mechanical properties after sterilization, allow you to securely hold bone fragments during reposition, X-ray negative. The method has demonstrated convenience and reliability.
34
Lucas, Julien, and Antoine Fourgeaux. "Treatment of Displaced Intra-articular Calcaneal Fractures with the Intramedullary Nail." Foot & Ankle Orthopaedics 3, no. 3 (July 1, 2018): 2473011418S0007. http://dx.doi.org/10.1177/2473011418s00079.
Full textAbstract:
Category: Trauma Introduction/Purpose: In 2010, a new closed reduction, internal fixation procedure for displaced intra-articular calcaneus fractures (DIACF) was developed with an intramedullary nail introduces through a channel in the calcaneal tuberosity. The goal was to reduce the rate of skin complications following principles of open reduction procedures. The aim of this prospective mono-centric study was to assess the occurrence of complications and the functional results using the AOFAS-AHS score. The secondary objectives were to assess first the restoration of the Böhler and Gissane angles on X-ray and shape of the calcaneus (Height, length, width) on CT scans, then thalamic reduction on 3D CT scans based on Goldzak’s global articular reduction classification. Methods: 26 Patients were included prospectively between 2014 and 2016 with analysis of X-rays and CT scans. Two were lost to follow-up and 2 patients sustained a secondary subtalar arthrodesis. After positioning a distractor and drilling, reduction was done with tamps and spatula. The nail was then introduced and locked with screws in the tuberosity and the constant fragment. After 3 weeks of non-weight bearing and 3 weeks with hindfoot off-loading shoe, full weight bearing was allowed. The functional outcome and restoration of the radiographic angles were evaluated postoperatively, at 3 months, 1 year and at the last follow-up. Global calcaneal shape and thalamic surface were evaluated postoperatively, at 1 year and at the last follow-up. The following early complications (delayed healing, infection, annoyed material, sural nerve lesion) and later complications (painful stiffness of the subtalar joint, hindfoot varus malalignment and calcaneofibular conflict) were recorded. Results: Mean follow up was 2.4 years. The mean AOFAS-AHS score was 79 ± 12 [100; 61] in the 22 patients examined. The mean Böhler angle rose from -1.29°± 18° [-35; 28] pre-operatively to 33°± 6° [22; 44] post-operatively. The mean calcaneal height index and length rose respectively from 0.44± 0,18 [0,12; 0,83] to 0.86± 0,22 [0,46; 1,1] and 82,4± 5,4 [72; 93] mm to 86,7mm ±4,6 [76; 97], and the width decreased from 49,8± 4,8 [38; 59] to 46,3± 3,7 [38; 55] mm. The Goldzak global articular reduction assessment was excellent in 39% of cases, good in 42% of cases and poor in 19% of cases. One case of deep infection was reported. Three patients needed device removal and two sustained a secondary subtalar arthrodesis. Conclusion: Our prospective study on this new device has the longest time of follow-up. The results confirm the effectiveness and the reliability over time of the procedure to restore the global shape and the thalamic surface with a low rate of complications and quick return to activities. It appears to be an excellent compromise between the respect of the principles of reduction as applied in the ORIF procedures, and the low cutaneous risk of percutaneous procedures. A subsequent study, with a larger number of patients, will enable analysis of the correlation between the radiological markers and the AOFAS-AHS.
35
Guo, Jialiang, Weichong Dong, Zhiwei Zhang, Ruipeng Zhang, Yingchao Yin, Wei Chen, Yingze Zhang, and Zhiyong Hou. "An exploratory study of pelvis anatomy to revise the bony canal used for LC2 screw insertion." BMC Musculoskeletal Disorders 23, no. 1 (March 26, 2022). http://dx.doi.org/10.1186/s12891-022-05256-2.
Full textAbstract:
Abstract Background Percutaneous screw placement, especially the insertion of LC2 screws, is technically demanding. Although the traditional LC2 bony canal spans the anterior inferior iliac spine (AIIS) to the posterior superior iliac spines (PSIS), a high perforation rate has been reported. Objection The aim of this research was to design a revised bony canal, measure the canal width and length and guide the insertion of LC2 screws for pelvic fractures. Materials and methods The plane tool in the Mimics analysis menu was used to draw a midplane connecting the midpoint between the anterior inferior spine and the PSIS upper flat region with pelvic CT data. The minimum widths of the upper, middle, lower surfaces of the tunnel and perforation rate were measured and compared. The ideal screw length was also measured along the longitudinal axis running through the midpoint of the midplane. Results The minimum widths of the upper, middle and lower surfaces of the revised canal were 3.63 mm, 7.7 mm, and 11.93 mm, respectively, in males and 5.97 mm, 9.93 mm, and 12.45 mm, respectively, in females. Significant differences were observed among the upper, middle and lower surfaces of the revised canal in male patients (P < 0.001). In female subjects, the upper canal surface was significantly different from the middle and lower canal surfaces (P < 0.001). The perforation rate was significantly decreased especially in females pelvic. The channel length passing through the midpoint of the narrowest position of the pelvis was 130.85 ± 8.02 mm in males and 124.30 ± 7.71 mm in females and was significantly different for male and female pelvises (P = 0.004). Conclusion The LC2 screw should be inserted along the intersection line of the AIIS lateral wall and the iliac body. The screw should be inserted under the line between the midpoint of the AIIS and the PSIS upper flat region to ensure accuracy of placement. LC2 screws can be more easily inserted in males than in females, and the rate of cortical perforation can be significantly decreased under the guidance of the newly proposed canal.
36
Chakravarthy, Nahushananda, Sivakumar Naganathan, Jonathan Tan Hsien Aun, Sreedhar Kalavagunta, Kamal Nasharuddin Mustapha, and Veena T. R. "EXPERIMENTAL INVESTIGATION OF CFRP STRENGTHENED I-SHAPED COLD FORMED STEEL BEAMS." Jurnal Teknologi 79, no. 5 (June 21, 2017). http://dx.doi.org/10.11113/jt.v79.10255.
Full textAbstract:
Cold formed steel differ from hot rolled steel by its lesser thickness and weight. The cold formed steel applicable in roof purlin, pipe racks and wall panels etc. Due its lesser wall thickness the cold formed steel member subjected to buckling. The enhancement of load carrying capacity of the cold formed steel member can be achieved by external strengthening of CFRP. In this study cold formed channel members connected back to back to form I shaped cross section using screws. These built up beam members were 300mm, 400mm and 500mm in length with 100mm screw spacing and edge distance of 50mm were chosen for testing. CFRP fabric cut according to length, width of built up beams and wrapped outer surface of beam using epoxy resin. Experiments were carried out in two sets firstly plain built up beams and secondly CFRP wrapped beams. The test results shows that increased load carrying capacity and reduction in deflection due to CFRP strengthening. Experimental results were compared with AISI standards which are in good agreement. Experimental results shows that CFRP strengthening is economic and reliable.
37
Jenkins, Stephen. "Forensic Issues from the Investigation of a Marine Shaft Failure." Journal of the National Academy of Forensic Engineers 38, no. 1 (July 25, 2021). http://dx.doi.org/10.51501/jotnafe.v38i1.168.
Full textAbstract:
The starboard propeller shaft of a twin-screw diesel electric rail ferry in New Zealand failed just after the ferry left port. Weather was not a factor. The ship was on a regular schedule of three sailings a day. The starboard propeller was found in 120 meters of water approximately two nautical miles from the channel — some distance from the point where power was observed to reduce to zero on the shaft. The fracture surface of the shaft showed a classic fatigue failure pattern. However, there were questions to be answered, including what initiated the failure, and why a tension failure occurred in a shaft that was primarily under compression from the reaction forces of the propeller. This paper will look at some interesting factors in the investigation, the techniques used to limit the investigation (and its cost) to relevant areas, a few of the false trails that were followed, and the processes eventually used that were the most convincing.
38
Yousif, Ahmed S., and Gary L. Solbrekken. "Analysis of Using Ferrofluid as an Interface Material in a Field Reversible Thermal Connector." Journal of Electronic Packaging 137, no. 2 (June 1, 2015). http://dx.doi.org/10.1115/1.4028958.
Full textAbstract:
The electrical functionality of an avionics chassis is limited due to heat dissipation limits. The limits arise due to the fact that components in an avionic computer boxes are packed very compactly, with the components mounted onto plug-in cards, and the harsh environment experienced by the chassis limits how heat can be dissipated from the cards. Convective and radiative heat transfer to the ambient are generally not possible. Therefore, it is necessary to have heat transferred from the components conducted to the edge of the plug-in cards. The heat then needs to conduct from the card edge to a cold block that not only holds the card in place but also removes the generated heat by some heat transfer fluid that is circulated through the cold block. The interface between the plug-in card and the cold block typically has a high thermal resistance since it is necessary for the card to have the capability to be reworkable, meaning that the card can be removed and then returned to the chassis. Reducing the thermal resistance of the interface is the objective of the current study and the topic of this thesis. The current design uses a pressure interface between the card and cold block. The contact pressure is increased through the addition of a wedgelock, which is a field-reversible mechanical connector. To use a wedgelock, the cold block has channels milled on the surface with widths that are larger than the thickness of the plug-in card and the unexpanded wedgelock. The card edge is placed in the channel and placed against one of the channel walls. A wedgelock is then placed between the card and the other channel wall. The wedgelock is then expanded by using either a screw or a lever. As the wedgelock expands, it fills in the remaining channel gap and bears against the other face of the plug-in card. The majority of heat generated by the components on the plug-in card is forced to conduct from the card into the wall of the cold block, effectively a single sided, dry conduction heat transfer path. Having started as a student design competition named RevCon Challenge, work was performed to evaluate the use of new field-reversible thermal connectors. The new design proposed by the University of Missouri utilized oil based iron nanoparticles, commonly known as a ferrofluid, as a thermal interface material. By using a liquid type of interface material, the channel gap can be reduced to a few micrometers, within machining tolerances, and heat can be dissipated off both sides of the card. The addition of nanoparticles improves the effective thermal conductivity of base fluid. The use of iron nanoparticles allows magnets to be used to hold the fluid in place, so the electronic cards may be easily inserted and removed while keeping the ferrofluid in the cold block channel. The ferrofluid-based design which was investigated has shown lower thermal resistance than the current wedgelock design. These results open the door for further development of electronic cards by using higher heat emitting components without compromising the simplicity of attaching/detaching cards from cooling plates.
39
Freeman, Andrew L., Mina S. Fahim, and Joan E. Bechtold. "Validation of an Improved Method to Calculate the Orientation and Magnitude of Pedicle Screw Bending Moments." Journal of Biomechanical Engineering 134, no. 10 (October 1, 2012). http://dx.doi.org/10.1115/1.4007629.
Full textAbstract:
Previous methods of pedicle screw strain measurement have utilized complex, time consuming methods of strain gauge application, experience high failure rates, do not effectively measure resultant bending moments, and cannot predict moment orientation. The purpose of this biomechanical study was to validate an improved method of quantifying pedicle screw bending moment orientation and magnitude. Pedicle screws were instrumented to measure biplanar screw bending moments by positioning four strain gauges on flat, machined surfaces below the screw head. Screws were calibrated to measure bending moments by hanging certified weights a known distance from the strain gauges. Loads were applied in 30 deg increments at 12 different angles while recording data from two independent strain channels. The data were then analyzed to calculate the predicted orientation and magnitude of the resultant bending moment. Finally, flexibility tests were performed on a cadaveric motion segment implanted with the instrumented screws to demonstrate the implementation of this technique. The difference between the applied and calculated orientation of the bending moments averaged (±standard error of the mean (SEM)) 0.3 ± 0.1 deg across the four screws for all rotations and loading conditions. The calculated resultant bending moments deviated from the actual magnitudes by an average of 0.00 ± 0.00 Nm for all loading conditions. During cadaveric testing, the bending moment orientations were medial/lateral in flexion–extension, variable in lateral bending, and diagonal in axial torsion. The technique developed in this study provides an accurate method of calculating the orientation and magnitude of screw bending moments and can be utilized with any pedicle screw fixation system.
40
Saha, Pulak, Sankar Debroy, and Arnab Panda. "EVALUATION OF FUNCTIONAL OUTCOME OF MODIFIED TENSION BAND WIRING AT 6 MONTHS IN ISOLATED OLECRANON FRACTURES IN ADULTS." INDIAN JOURNAL OF APPLIED RESEARCH, March 1, 2022, 72–76. http://dx.doi.org/10.36106/ijar/0302746.
Full textAbstract:
Introduction: Fractures of the olecranon account for 8 - 10 % of all fractures around the elbow joint . An uncomplicated fracture of the olecranon is considered to be a common injury. Incidence in adult population is approximately 11.5% per 1 64 100000 population .Younger individuals suffer fracture olecranon due to high energy trauma and older individuals due to simple fall . When displaced, open reduction and internal xation is usually required to obtain anatomical realignment of the articular surface and restore normal elbow function. The xation should be stable, allow active elbow exion and extension and promote union of the fracture. There are other modalities of xation of isolated olecranon fractures, such as olecranon hook plate and cannulated lag screws as well but tension band wiring is less costly and operative complications are less in non comminuted olecranon fractures. Material and methods: This prospective observational study was done over a period of 2 years on transverse and oblique fractures of olecranon. Results: the outcome of our study was favorable in support of tension band wiring in transverse and oblique fracture of olecranon in respect to union rate, early initiation of physiotherapy and nal range of motion. Conclusion: By this method post-operative immobilization in POP is greatly minimized. Thereby avoiding fracture disease.Because of rigid xation between the fracture fragments, early active and functional movements can be given to the patient reducing the chances of joint stiffness. Early initiation of physiotherapy program within 2 – 3 weeks induces compression between the fragments. This compression hastens fracture healing. Because of early union of fracture, patient is back to work earlier
41
G, Sreedhar Babu, Sekhar A.S., and Lingamurthy A. "Diagnostics of actuation system by Hadamard product of integrated motor current residuals applied to electro-mechanical actuators." International Journal of Prognostics and Health Management 10, no. 1 (November 12, 2021). http://dx.doi.org/10.36001/ijphm.2019.v10i1.2754.
Full textAbstract:
The paper presents diagnostics methodology that can identify the event of occurrence of fault in the actuator or the linkage system of the flight control actuation system driven by Linear Electromechanical Actuators (LEMA). The standard data analysis like motor current signature analysis (MCSA) is good at identifying the incipient faults within the elements of the actuators in situations where-in the actuators are driving control surfaces. But in back driven cases, where-in LEMA is driven back by control surfaces, the faults outside the LEMAs are difficult to be detected due to higher mechanical advantages of transmission elements like roller screws, gear train and linkage arms scaling down their effects before reaching the motor. One such event occurred in a ground test, wherein the jet vanes were sheared when back driven by excessive gas dynamic forces. Neither the motor current nor the LEMA position feedback data has any clue of the instance of occurrence of such shearing. The case study is discussed in detail and diagnostics solution for such failures is proposed. A new methodology to pin point the event of occurrence is arrived at based on ground static test data of four independent channels. The same is reassured for its applicability using lab experiments on three samples mimicking the failure. The method's applicability is also extended for extracting events in actual flight, by comparing the flight telemetry data with the mimicked lab level (dry runs) data. The methodology uses the analysis of LEMA motor current data to arrive at the vital diagnostic information. The current data of LEMA directly cannot be interpreted due to non-stationary nature arising from variable speed and its pulsating form because of the pulse width modulation (PWM) switching, threshold voltages and closed loop dynamics of the servo. Hence the motor current is integrated using cumulative trapezoidal method. This integrated data is spline curve fitted to arrive at residuals vector. The Hadamard product is used on the residuals vector to amplify the information and suppress the noise. Further, normalizing is done to compare data across tests and samples. With this, necessary diagnostic information was extracted from static test data. The method is extended for extracting diagnostics information from actual flight using comparison analysis of, the test data in actual environment with mimicked lab level dry runs. It is also verified for applicability in faults directly driven by actuators in lab level experiments on three samples.