Perpendicular Traction Research Articles

Optimizing cutaneous excisions on extremities: a comparative review of elliptical closure and S-plasty techniques

This review elucidates the comparative applications of elliptical closures and S-plasty or “lazy s” in the excision of cutaneous neoplasms on the extremities. The article completes an analysis of closure techniques by discussing their merits, limitations, and optimal applications based on their orientation and tension dynamics. It also provides a detailed guide on suture placement and specific intraoperative maneuvers associated with the S-plasty to enhance surgical outcomes. The S-plasty, preferred for its diminished suture line tension and adaptability to convex areas, is analyzed against traditional relaxed skin tension lines and the emerging biodynamic excisional skin tension (BEST) lines. The review underscores the BEST lines’ role in minimizing perpendicular traction and their impact on improved surgical outcomes on the extremities. It also addresses the challenges of excessive traction along wound margins and the consequential suboptimal healing outcomes, emphasizing the importance of appropriate tension management. This review also compares the stability, efficiency, and esthetic outcomes of the S-plasty with elliptical excisions, highlighting the S-plasty’s superior ability to distribute tensile forces evenly, thus reducing the risk of scar-related complications. It also discusses the benefits of using BEST lines for tension vector dispersion coupled with the design of an S-plasty, even when relaxed skin tension line favors a horizontal orientation. Furthermore, the review elaborates on the procedural execution of the S-plasty, emphasizing the importance of precise suture placement and selecting suitable suture materials and techniques to ensure optimal wound edge perfusion. The overarching theme is the prioritization of technique based on specific anatomic considerations and the surgeon’s expertise to ensure the most effective and beneficial cutaneous excisions on the extremities.

Oriented Strand Board panels of residual reforestation wood with Al2O3 nanoparticles

The application of metal oxide nanoparticles (Al2O3) in Oriented Strand Board (OSB) panels has been studied as a way to provide greater efficiency in heat transfer rate during the thermopressing process, thus contributing to the polymerization process of the resin used in particle agglomeration. Studies on the subject, however, are still scarce and require further study in order to optimize the production process of OSB panels. Therefore, this study evaluated medium density OSB panels (650 kg/m3) of reforestation residual wood shaped with 13% castor oil-based polyurethane resin with 1% of commercially sourced Al2O3 nanoparticles and manufactured in the laboratory via the proteic sol-gel method. Microstructural analysis of the nanoparticles was performed to verify their dispersion within the resin; qualitative analysis of nanoparticles was performed with X-ray diffraction (XRD); and analysis by High Resolution Transmission Electron Microscopy (HRTEM) was performed to study commercially sourced and laboratory-produced nanoparticles. After analyzing the results, the panels were produced with commercial aluminum oxide nanoparticles and characterized by physical (thickness swelling) and mechanical (static bending and perpendicular traction) tests, according to current normative documents. The results indicated that commercial aluminum oxide nanoparticles provided better performance in microstructural and qualitative analysis, in addition to provide a better efficiency in the resin curing stage, causing an increase in the values of physical-mechanical properties in the transverse direction for the modulus of rupture (69.15%) and internal bond of the wood particles (53.57%).

Using miriti petiole to produce particleboards

This study aimed to use the petiole residues of miriti to partially replace pine wood and evaluate the effects of this incorporation on the physical and mechanical properties of the particleboards. Panels were produced with 0, 25, 50, and 75% of miriti in partial replacement of wood and 12% of urea-formaldehyde adhesive. The chemical-physical properties of miriti residues showed potential particleboard production as they were similar to those of pinewood. For the physical properties, the panels were classified as low density. There was an increase in the compression ratio and, consequently, in the hygroscopicity . For the mechanical properties, it was observed that the modulus of elasticity (MOE) and modulus of rupture (MOR) did not show any statistical differences. For perpendicular traction (PT), there was a significant reduction in 50%. Considering a general analysis of the physical and mechanical properties, up to 40% of mirti can be substituted, as in this situation they meet the properties mentioned in CS-236-66, except for PT for commercialization of the panels.

Bone tunnel placement influences shear stresses at the coracoid process after coracoclavicular ligament reconstruction: a finite element study and radiological analysis

IntroductionCoracoid fractures after arthroscopic treatment of acromioclavicular (AC) joint separations lead to poor clinical outcomes. In this study, different configurations of bone tunnels in the lateral clavicle and coracoid were examined concerning the amount of stress induced in the coracoid.MethodsAn authentic 3D finite element model of an ac joint was established. Three 2.4 mm bone tunnels were inserted in the lateral clavicle, which were situated above, medially and laterally of the coracoid. Then, two 2.4 mm bone tunnels were inserted in the latter, each simulating a proximal and a distal suture button position. Von Mises stress analyses were performed to evaluate the amount of stress caused in the coracoid process by the different configurations. Then, a clinical series of radiographs was examined, the placement of the clavicle drill hole was analyzed and the number of dangerous configurations was recorded.ResultsThe safest configuration was a proximal tunnel in the coracoid combined with a lateral bone tunnel in the clavicle, leading to an oblique traction at the coracoid. A distal bone tunnel in the coracoid and perpendicular traction as well as a proximal tunnel in the coracoid with medial traction caused the highest stresses. Anatomical placement of the clavicle drill hole does lead to configurations with smaller stresses.ConclusionThe bone tunnel placement with the smallest amount of shear stresses was found when the traction of the suture button was directed slightly lateral, towards the AC joint. Anatomical placement of the clavicle drill hole alone was not sufficient in preventing dangerous configurations.Level of evidenceControlled laboratory study.

Technological characterization of particleboards constituted with pistachio shell (Pistacia vera) and Pinus oocarpa wood

The objective of this work was to produce and characterize particleboards manufactured with pine wood and pistachio shell. Three mix proportions of 25, 50 and 75% were used, and for the control, panels manufactured with 100% pistachio shell were adopted. The panels were produced with a nominal density of 0.75 g cm-3. The properties analyzed were: apparent density, water absorption, thickness swelling, modulus of rupture, modulus of elasticity and perpendicular traction. The chemical characterization of the particles showed that the extractives content of pistachio was higher than the content obtained for pine wood. There was no significant difference for physical properties and all values obtained for IE 24 h, of panels composed of a mixture of particles (T1, T2 and T3) were contemplated by the Brazilian standard. Significant differences were found for mechanical properties, as well as a decrease in strength. The MOR of the panels made up of 25% pistachio and 75% pine wood showed a satisfactory value, as the standard requires a minimum value of 11.00 MPa and the panels reached an average value of 11.38 MPa. For perpendicular traction, the T1 and T2 treatment panels met the standard requirement, reaching values above 0.35 Mpa.

Ecological panels as an alternative for waste from mechanical processing of Amazonian species

The wood residues resulting from the operational phases in companies in the forestry market are normally considered by-products and, therefore, are discarded or reused for energy production, however, this material has a greater potential, such as the generation of new products through agglutination, which may generate a new segment in the wood industry, causing competition between products of native and planted species. This research aimed to develop agglomerated panels using residues of two tree species from the Amazon (Dinizia excelsa Ducke and Manilkara huberi (Ducke) Chevalier) and a mixture of commercial Amazonian species of high density, with the purpose of greater added value and a possible solution to reduce the negative environmental impacts of carbon emissions. The experimental design consisted of three treatments with five repetitions in each. Experimental panels were produced with a nominal density of 0.80 g/cm³, using castor oil-based resin with 10% percentages. The panels were pressed with a pressure of 10 MPa, temperature of 100ºC and with a pressing time of 10 minutes. The evaluations of the results obtained were compared with the ANSI A208.1 / 2009 standard and with the literature on agglomerated panels of tropical species. In physical properties, the panels showed compliance with the values found in the literature, however, they are outside the standard of the norm. Regarding the mechanical properties, the MOR values classify the panels in the medium to high density standard in accordance with the standard. The results of the MOE are superior to those of the existing literature, with emphasis on the perpendicular traction that presents values consistent with the literature. The machining evaluations carried out according to ASTM D 1666-11 / 2011, show a good quality in the finish. In general analysis and in compliance with the regulations, all panels have economic viability and potential for industrialization.

Mechanical analysis of bamboo and agro-industrial residue one-layer particleboard

A high-density particleboard composed of peanut shells (Arachis hypogaea L.), an agro-industrial residue, and bamboo wastes of the species Dendrocalamus giganteus (branches and apical part), bonded with a two-component polyurethane resin based on castor oil (Ricinus communis L.) in the proportion of 12% of the particleboard mass, was produced. Four types of specimens were prepared according to the percentage of peanut shells: 0%, 10%, 20%, and 30%. Mechanical characteristics were evaluated through the flexural strength tests for modulus of rupture, modulus of elasticity, perpendicular traction, and screw pull resistance. The particleboard reached an average density of 917.2 kg/m3, meaning that it could be classified as high-density particleboard. The results of the mechanical tests indicated that the specimens containing a mixture in the proportion of 90% bamboo and 10% peanut hull presented the best mechanical strength. The experiment produced particleboards with a satisfactory mechanical physical performance that met the standards ABNT NBR 14.810-2 and ANSI A208-1, supporting the use of the peanut shell residue in the manufacture of particleboards to be used in internal environments and allowing the applicability of this residue through additional value.

Valorization of wood shavings waste for the production of wood particulate composites

The aim of this work was to evaluate the physical and mechanical properties of particleboards using particles from wood shaving at three urea-formaldehyde adhesive contents: 6, 9 and 12% (dry mass basis). The particleboards were produced with nominal density of 0.70 g.cm-3, pressing cycle with temperature of 160 °C, pressure of 3.92 MPa and time of 8 minutes. The properties of water absorption (WA), thickness swelling (TS), both after 2 and 24 hours, apparent density, compression ratio, perpendicular traction, modulus of elasticity (MOE) and modulus of rupture (MOR) in static bending, Janka hardness and screw withdrawal resistance were evaluated. The results of the tests indicated that with the increase of the adhesive content from 6 to 12%, there was no significant statistical difference for the average values of apparent density and compression ratio, being 0.621 g.cm-3 and 1.234, respectively, and the WA and the TS are decreased after 2 and 24 hours. There was a gain of 93% for the MOR property and 64% for the MOE property with the increase of the adhesive content. For perpendicular traction, the highest mean value was 0.67 MPa, referring to the panels with 12% of adhesive. For Janka hardness, the treatments with contents of 9 and 12% of adhesive presented the highest average values being of 21.60 and 25.26 MPa, respectively. In general, the use of wood shavings is feasible for the production of particleboards with a 12% adhesive content. Keywords: Mechanical resistance; Dimensional stability; Particleboards.

Production and evaluation of particleboard made of sawdust and sugarcane bagasse with polyurethane resin based on castor oil

Among the goals for sustainable development in Brazil, studies have been conducted to better use of industrial and agricultural waste to promote adequate final disposal of these and generate new materials that minimize the exploitation and use of natural resources. In this work, the proposal is to make and evaluate boards with nominal density of 0.80 g.cm-3 using sugar cane bagasse, sawdust and polyurethane resin derived from castor oil. Thus, three treatments with different percentages of particles and 10% of PU-castor were proposed for the preparation of boards that were pressed with a pressure of 50 kgf.cm-2, a temperature of 100°C and a pressing time of ten minutes. The boards were evaluated for their physical properties (density, moisture content and swelling) and mechanical (static flexure and perpendicular traction) according to NBR 14810: 2-2013 and presented average values density of 936 to 937 kg.m-3, swelling after 24 hours of 5.0 to 7.2%, modulus of resistance to static bending of 22 to 23 MPa and perpendicular traction of 0.71 to 0.87 MPa. The results obtained with the tests indicate the great potential of use of sugarcane bagasse and sawdust to produce boards of high density particles.

PROPERTIES OF PARTICLEBOARD PANELS MADE OF SUGARCANE PARTICLES WITH AND WITHOUT HEAT TREATMENT

ABSTRACT The objective of this work was to determine the properties of particleboard panels made of “in natura” sugarcane bagasse particles, heated at 250 °C for 5 minutes. Various particle proportions were utilized to produce the panels and their properties were compared with that of a panel made of Pinus sp. The panels were produced with 8% tannin formaldehyde adhesive, and 0.5% paraffin emulsion, being pressed at 32 kgf.cm-2 for 10 minutes at 180 ° C. It was determined the basic density of the “in natura” and heat-treated particles, their chemical composition, as well as the compression ratio necessary to obtain panels with density equal to 0.75 g.cm-3. The basic density of the panels, hygroscopic equilibrium humidity, thickness swelling, linear expansion, water vapor adsorption, modulus of elasticity and rupture, perpendicular traction, screw pullout, and Janka hardness were determined. The basic densities of Pinus particles and sugarcane bagasse without and with heat treatment were 0.46, 0.27 and 0.30 g.cm-3, respectively. The average specific mass of the panels was 0.74 g.cm-3 with no significant difference between them. Generally, panels made of sugarcane particles were less hygroscopic and dimensionally more stable than panels made of Pinus particles. However, the perpendicular tensile strength, screw pullout and Janka hardness of these panels were higher than for the Pinus panels. The heat treatment of sugarcane bagasse particles resulted in better mechanical properties of perpendicular traction and Janka hardness. In general, the panels are within the limits set by ANSI A208.1. It is therefore possible to replace panels made of Pinus particles for the ones made of sugarcane bagasse, provided that at least 25% of the particles are heat treated for 5 minutes at 250 ° C.

Production of Structural Particleboard of Mimosa Scabrella Benth With Lignin Phenol-formaldehyde Resin

ABSTRACT The objective of this work was to evaluate the feasibility of using lignin-phenol-formaldehyde resin in the production of Mimosa scabrella Benth (bracatinga) structural particleboard. The boards were produced with nominal specific mass of 0.75 and 0.95 g/cm3, 10% and 12% of phenol-formaldehyde and lignin-phenol-formaldehyde resins, with 10 and 12 min of pressing time. The boards quality was evaluated by means of the following physical-mechanical tests: specific mass, compression ratio, water absorption and thickness swelling after 2 and 24 hours soaking, perpendicular traction, static bending and screw pulling. Positive interactions of specific mass, resin content and pressing time were observed in the properties of the boards produced. The evaluation of the properties results based on the requirements of EN 312 (type P5) standard indicated the feasibility of using lignin-phenol-formaldehyde resin in the production of particleboard of Mimosa scabrellla for structural applications.

Finite Element Comparison of 10 Orthodontic Microscrews with Different Cortical Bone Parameters

Unlike standard dental implants, the stabilization of orthodontic microscrews removed after treatment is done without osseointegration and achieved by several components: cortical bone thickness (CBT), microscrew geometry, and drilling depth. The purpose of this study was to evaluate 10 different microscrews and the influence of their geometric parameters with different CBT and drilling depths. The influence of geometric parameters in cortical bone was analyzed with a series of computational simulations with finite element models to obtain von Mises stresses and deformations in the microscrew when loaded with a perpendicular traction force of 1 N and considering the angle of incidence as a random parameter. There was variability in the angle of incidence, with less clinical influence. Biomechanical parameters such as microscrew diameter, CBT, and drilling depth had significant influences on the results. At a drilling distance of 8 mm, narrow microscrews (Abso Anchor 1.2) showed maximum von Mises stress of 500.698 MPa and maximum deformation in the shank of 0.08549 mm. Microscrews with a diameter of 1.5 mm (Dentaurum, Jeil, Mondeal, Tekka, Spider) showed von Mises stresses ranging from 56.97 to 136 MPa and deformation between 0.0062055 and 0.0476 mm. Microscrews with a diameter of 2.0 mm (Jeil, Mondeal, Tekka) showed von Mises stresses ranging from 17.172 to 54.861 MPa and deformation of 0.000172 to 0.0161 mm. The shape and geometry of an orthodontic microscrew are highly important in its behavior. Optimal characteristics of a microscrew would include a diameter of 2.0 mm, a cylindric shape, a short and wide head, a short and wide shank, and threads of an appropriate size.

Three Dimensional Traction Forces Exerted by Migrating Amoeboid Cells

There is still a lack of information regarding the mechanical aspects of cell migration and the quantification of the traction forces is essential to completely understand the migration process. Most of the methods developed to measure traction forces exerted by cells moving over flat substrates assume that the vertical forces exerted by the cells are negligible and they only exert tangential forces to the substrate. Now we have developed a method to determine the cellular traction forces exerted perpendicular to the substrate in addition to the in-plane forces. We measure the 3D substrate deformation by tracking the displacements of fluorescent marker beads embedded in the substrate. The traction forces exerted by the cells are obtained by solving analytically the elastostatic equation for a linearly elastic medium using the previously measured deformation of the substrate. In order to understand the role of specific cytoskeletal components in the organization of the three-dimensional stresses we are using Dictyostelium Discoideum cells, we study mutants with contractility and actin-crosslinking defects and compare these mutants with Wild type cells. We are looking at Myosin II null and Cortexillin null mutants to quantify the role that these proteins play in the mechanics of cell motility. We find that the three cell lines studied push on the substrate near the center of the cell and pull up near the periphery. The magnitude of the perpendicular forces is comparable to the magnitude of the tangential forces to the substrate; therefore this perpendicular component cannot be neglected. Our measurements indicate that the effects of mutations on the tangential and perpendicular traction forces to the substrate are different. Therefore, it suggests that the generation of the perpendicular and tangential traction forces is possibly controlled by two different mechanisms.

Propriedades de chapas tipo OSB, fabricadas com partículas acetiladas de madeiras de Eucalyptus grandis, Eucalyptus urophylla, Eucalyptus cloeziana e Pinus elliottii

Este trabalho teve como objetivo avaliar as propriedades de chapas de 0riented Strand Board (OSB), fabricadas com flocos de madeira de Eucalyptus grandis, Eucalyptus urophylla e Eucalyptus cloeziana e oriundas dos Municípios de Ponte Alta e Três Marias, no Estado de Minas Gerais. As massas específicas básicas das três espécies de eucaliptos das duas regiões foram, respectivamente: Ponte Alta (0,55; 0,61; e 0,70 g/cm³) e Três Márias (0,56; 0,58; e 0,69 g/cm³). Quando necessário, para manter as massas específicas das chapas próximas de 0,70 g/cm³ foram acrescentadas às partículas de madeira de eucalipto partículas de madeira de Pinus elliottii, oriundo da cidade de Viçosa, com massa específica de 0,45 g/cm³. Os flocos foram gerados nas dimensões médias de 90,00 x 20,00 x 0,46 mm. O adesivo utilizado foi o fenol-formaldeído, na proporção de 8% de sólidos, em relação à massa seca de partículas. Parte dos flocos de eucaliptos foram acetilados. As chapas foram prensadas à temperatura de 170 °C e 32 kgf/cm² de pressão. As propriedades das chapas foram determinadas segundo as normas da ABNT NBR 14810-3 (2002) e ASTM-D 1037 (1991). Os resultados foram comparados utilizando-se as normas ANSI/A - 208.1 (1993) e CSA 0437-93 (1993). As chapas contendo partículas acetiladas foram mais estáveis e adsorveram menos umidade. Na tração perpendicular, observou-se que as chapas contendo 100% de flocos acetilados apresentaram resultados inferiores ao estipulado pela norma CSA O437-0/93 (1993). A resistência ao arrancamento de parafuso, módulo de ruptura (paralelo e perpendicular) e compressão longitudinal (perpendicular), foi reduzida pela acetilação nas chapas contendo 100% dos flocos acetilados. As espécies que apresentaram, numericamente, as maiores médias para resistência mecânica foram: Eucalyptus grandis não acetilado (dureza Janka) e Eucalyptus cloeziana misturado com Pinus sp (módulo de ruptura). Somente a resistência à compressão longitudinal foi afetada pela região de origem da madeira. Os painéis fabricados com madeira de Eucalyptus urophylla, oriunda do Município de Três Marias, tiveram médias inferiores aos das chapas feitas com a mesma espécie, porém oriundas do Município do Rio Doce.

Arthroscopic relationship of the axillary nerve to the shoulder joint capsule: An anatomic study

Twelve right shoulders in fresh cadavers were dissected to determine the relation of the axillary nerve to the shoulder capsule and glenoid. Needles transfixed the nerve to the capsule and into the shoulder joint. Arthroscopy was performed to determine the location of the needles on the glenoid clock. The needles were then removed and the position of the shoulder changed to determine the effect on the position of the axillary nerve. The axillary nerve was held to the shoulder capsule with loose areolar tissue in the zone between 5 and 7 o'clock and was close to the glenoid in the neutral position, in extension, and in internal rotation. With shoulder abduction, external rotation, and perpendicular traction, the capsule became taut and the axillary nerve moved away from the glenoid. Abduction, external rotation, and perpendicular traction increase the zone of safety during arthroscopic anterioinferior capsulotomy adjacent to the glenoid between the 5 and 7 o'clock positions.

Tensile bond between bone and titanium: a reappraisal of osseointegration.

When Branemark in the 1970s established the term osseointegration, this implied a direct chemical bond between a titanium implant and bone. However, ultrastructural studies seemed not to support this idea, and osseointegration came to be defined as the absence of interfering fibrous tissue. Titanium was therefore described as bioinert rather than bioactive. We now demonstrate mechanically a chemical bond between bone and titanium, using unloaded cp titanium plates, similar to those used in previous studies on prosthetic loosening. Tensile force can be transmitted only by chemical bonds. Bone-bonding was therefore evaluated by a detachment test. The plates were developed so that a flat titanium surface touched traumatized bone and the rest of the detachable part had no contact with surrounding tissue. The titanium plates were either polished and sterilized in an autoclave or treated in 4 M NaOH and then heated to 600 degrees C according to Yan et al. (1996). After 4 weeks, the plates were separated from the bone by a perpendicular traction force. The detaching load of the untreated titanium plates never exceeded 0.03 MPa, whereas with treatment it increased to median 0.8 MPa, with bone remaining attached to parts of the plates after detachment. Our findings confirm that a chemical bond can be obtained within 4 weeks with the described pretreatment. It may occur also without treatment, after a longer implantation time.

The use of somatosensory evoked potentials for detection of neuropraxia during shoulder arthroscopy

With the increase in the use of shoulder arthroscopy in the past decade, there has been an increased awareness of complications. Reports of the occurrence of transient neuropraxia indicate an incidence of 10%-30%. The recording of somatosensory evoked potentials (SEP) for the study and functional monitoring of the sensory pathway is well accepted as a reproducible method of monitoring peripheral nerve and spinal cord function during surgery. SEPs were recorded during shoulder arthroscopy in 20 patients to monitor the musculocutaneous nerve, ulnar nerve, and either the median or radial nerve. In all 20 cases, abnormal SEPs of the musculocutaneous nerve were demonstrated. In 16 cases, this was produced upon initial joint distention, and in 15 cases, by traction; in 11, by longitudinal traction of greater than or equal to 12 lb, and in six by perpendicular traction of greater than or equal to 7 lb. In 10 patients, there were varying combinations of median, ulnar, and radial nerve involvement. There were two cases of clinical neuropraxia in this series. One resolved in 24 h and one in 48 h. The conclusion is that there is a real potential for neurologic damage during shoulder arthroscopy and that the musculocutaneous nerve is the most vulnerable. Factors responsible include joint distention, excessive traction, and extravasation of fluid. The use of SEPs provides a reliable means for monitoring the neurologic status of the extremity during shoulder arthroscopy.