Treatment of posttraumatic cubitus varus in children and adolescents. Supracondylar humeral osteotomy using radial external fixation

OBJECTIVE Precise adaptable fixation of a supracondylar humerus osteotomy with a radial/lateral external fixator to correct posttraumatic cubitus varus. INDICATIONS Acquired, posttraumatic cubitus varus as a result of a malhealed and unsatisfactorily treated supracondylar humerus fracture. Idiopathic, congenital cubitus varus (very seldom) if the child (independent of age and after complete healing) is cosmetically impaired; stability of the elbow is reduced due to malalignment (hyperextension); secondary problems and pain (e. g., irritation of the ulnar nerve) are expected or already exist; or there is an explicit wish of the child/parents (relative indication). CONTRAINDICATIONS In principle there are no contraindications provided that the indication criteria are filled. The common argument of age does not represent a contraindication in our opinion, since angular remodeling at the distal end of the humerus is practically nonexistent. SURGICAL TECHNIQUE Basically, the surgical technique of the radial external fixator is used as previously described for stabilization of complex supracondylar humeral fractures. With the patient in supine position, the arm is placed freely on an arm table. Using a 4-5 cm long skin incision along the radial, supracondylar, the extracapsular part of the distal humerus is prepared, whereby great caution regarding the radial nerve is advised. In contrast to the procedure used in radial external fixation for supracondylar humeral fracture treatment, two Schanz screws are always fixed in each fragment at a distance of 1.5-2 cm. The osteotomy must allow the fragment to freely move in all directions. The proximal and distal two Schanz screws are then connected with short 4 mm carbon or stainless steel rods. These two rods are connected with each other over another rod using the tub-to-tub technique. Now the preliminary correction according the clinical situation can be performed and the clamps are tightened. Anatomical axis and function are checked. If these are radiologically and clinically perfect, all clamps are definitively tightened; if the alignment or the function is not perfect, then further adjustments can be made. POSTOPERATIVE MANAGEMENT Due to the excellent stability, further immobilization not necessary. Immediate functional follow-up treatment performed according to pain. RESULTS Adequate healing is usually expected within 6 weeks. At this time the external fixator can be removed in the fracture clinic. Because the whole operation is performed in an extraarticular manner and the mobility of the elbow is not affected, deterioration of function has never been observed. Also regarding the cosmetic/anatomical situation, good results are expected because they were already achieved intraoperatively.

Cytotoxicity evaluation of polymer-derived ceramics for pacemaker electrode applications.

Ceramics are known to be chemically stable, and the possibility to electrically dope polymer-derived ceramics makes it a material of interest for implantable electrode applications. We investigated cytotoxic characteristics of four polymer-derived ceramic candidates with either electrically conductive or insulating properties. Cytotoxicity was assessed by culturing C2C12 myoblast cells under two conditions: by exposing them to material extracts and by putting them directly in contact with material samples. Cell spreading was optically evaluated by comparing microscope observations immediately after the materials insertion and after 24 h culturing. Cell viability (MTT) and mortality (LDH) were quantified after 24-h incubation in contact with the materials. Comparison was made with biocompatible positive references (alumina, platinum, biocompatible stainless steel 1.4435), negative references (latex, stainless steel 1.4301) and controls (no material present in the culture wells). We found that the cytotoxic properties of tested ceramics are comparable to established reference materials. These ceramics, which are reported to be very stable, can be microstructured and electrically doped to a wide range of conductivity and are thus excellent candidates for implantable electrode applications including pacemakers.

Biomechanical comparison between bicortical pin and monocortical screw/polymethylmethacrylate constructs in the cadaveric canine cervical vertebral column.

OBJECTIVE To compare biomechanical stiffness of cadaveric canine cervical spine constructs stabilized with bicortical stainless steel pins and polymethylmethacrylate (PMMA), monocortical stainless steel screws with PMMA, or monocortical titanium screws with PMMA. STUDY DESIGN Biomechanical cadaver study. ANIMALS Eighteen canine cervical vertebral columns (C2-C7) were collected from skeletally mature dogs (weighing 22-32 kg). METHODS Specimens were radiographed and examined by dual energy X-ray absorptiometry. Stiffness of the unaltered C4-C5 intervertebral motion unit was measured in extension, flexion and lateral bending using non-destructive 4-point bend testing. Specimens were then stabilized by (1) bicortical stainless steel pins/PMMA, (2) monocortical stainless steel screws/PMMA, or (3) monocortical titanium screws/PMMA. Mechanical testing was repeated and stiffness data from unaltered specimens and the 3 treatment groups were compared. RESULTS All 3 surgical methods significantly increased stiffness of the C4-C5 motion unit compared with the unaltered specimen (P < .001 for all treatments), but stiffness was not significantly different among the 3 fixation groups (P = .578). CONCLUSIONS In this model, monocortical screw fixation (with stainless steel or titanium screws) was biomechanically equivalent to bicortical fixation.

An assessment of differences in pediatric dental services provided for a Medicaid population when compared to a federally subsidized (military) clinic

Reimbursement for dental services performed for children receiving Medicaid is reimbursed per service while dental treatment for military dependents provided at a military installation is neither directly reimbursable to those providing the care nor billed to those receiving the care. The purpose of this study was to compare pediatric dental services provided for a Medicaid population to a federally subsidized military facility to compare treatment choices and subsequent costs of care. It was hypothesized that differences in dental procedures for Medicaid and military dependent children would exist based upon treatment philosophy and payment method. A total of 240 records were reviewed for this study, consisting of 120 Medicaid patients at the University of Texas Health Science Center at San Antonio (UTHSCSA) and 120 military dependents at Wilford Hall Medical Center (WHMC), Lackland Air Force Base, San Antonio. Demographic data and treatment information were abstracted for children receiving dental treatment under general anesthesia between 2002 and 2006. Data was analyzed using the Wilcoxon rank sum test, Kruskal-Wallis test, and Fisher's exact test. The Medicaid recipients treated at UTHSCSA were younger than patients at WHMC (40.2 vs. 49.8 months, p<.001). The university also treated significantly more Hispanic children than WHMC (78.3% vs. 30.0%, p<.001). Children at UTHSCSA had a mean of 9.5 decayed teeth and were treated with 2.3 composite fillings, 0 amalgam fillings, 5.6 stainless steel crowns, 1.1 pulp therapies, 1.6 extractions, and 1.0 sealant. Children at WHMC had a mean of 8.7 decayed teeth and were treated with 1.4 composite fillings, 0.9 amalgam fillings, 5.6 stainless steel crowns, 1.7 pulp therapies, 0.9 extractions, and 2.1 sealants. The means of decayed teeth, total fillings, and stainless steel crowns were not statistically different. UTHSCSA provided more composite fillings (p<.001), fewer amalgam fillings (p<.001), fewer pulp therapies (p <.001), more extractions (p=.01), and fewer sealants (p<.001) when compared to WHMC. Age and gender did not effect decay rates, but those of Hispanic ethnicity did experience more decay than non-Hispanics (9.5 vs. 8.6, p=.02). Based upon Texas Medicaid reimbursement rates from 2006, the cost for dental treatment at both sites was approximately $650 per child. The results of this study do not support the hypothesis that Medicaid providers provide less conservative therapies, which would be more costly, care when compared to a military treatment center. ^

Influencia de cuatro alternativas de crianza en roble sobre el color, la composición polifenológica y las características organolépticas de vinos Malbec y Cabernet Sauvignon

Los costos de las barricas, por el tipo de cambio en la Argentina, son inaccesibles para muchas bodegas. Debido a esto, muchas de ellas utilizan sistemas alternativos de crianza, no conociendo claramente las consecuencias y los fenómenos que ocurren con el uso de estos sistemas. El objetivo del trabajo fue evaluar la composición polifenólica, el color y los caracteres sensoriales de vinos tratados con distintos sistemas de crianza en madera. Para ello se utilizaron métodos espectofotométricos rápidos y fácilmente realizables en bodega. Los tra tamientos a los cuales se sometió el vino fueron: barrica de roble americano de primer uso, barrica de más de cinco años de uso reacondicionada, vasija de acero inoxidable con “dominó" de roble en dosis comúnmente usadas en el medio, vasija de acero inoxidable con “dominó" de roble en dosis equivalentes a la superficie de contacto de la barrica y vino sin madera tomado como testigo. El ensayo se realizó con vinos cosecha 2007 de las variedades Malbec y Cabernet Sauvignon y el tiempo de crianza fue de 10 meses. Los resultados mostraron que en ninguna de las variedades los tratamientos con barricas obtuvieron mayor nivel de polimerización que el resto de los tratamientos ni tampoco los sistemas con agregado de fragmentos de roble superaron en polimerización al vino sin madera. Por otro lado, sólo en la variedad Cabernet Sauvignon la barrica nueva superó en intensidad de color al vino sin madera. En cambio, los tratamientos con roble favorecieron la copigmentación y los copigmentos inhibieron la polimerización, haciendo más lenta la formación de uniones tanino- antocianos pero también protegiendo el color y evitando oxidaciones, esta situación podría explicar los resultados contradictorios entre distintos autores. En el aspecto sensorial los vinos en barricas no obtuvieron mayor intensidad de color ni menor astringencia que los vinos con agregado de roble y tampoco estos últimos lograron diferencias con el vino testigo. Por otro lado en ambas variedades, la barrica nueva y el tratamiento con alta dosis de dominó de roble tuvieron la mayor intensidad aromática con descriptores como vainilla y chocolate aunque la alternativa de crianza con “dominó" estuvo muy ligada al descriptor “tabla". La barrica reacondicionada mostró el mayor nivel del descriptor betún y en el tratamiento testigo se detectaron aromas de reducción. El tratamiento con dominó de roble en dosis comerciales se encontró más ligado a los aromas frutados.

Abundance of microplankton in the eastern Mediterranean Sea in April 2008 during SES_GR2

The dataset is based on samples taken from 12 stations in Northern Aegean Sea, Southern Aegean Sea, Ionian Sea and Libyan Sea during August-September 2008. 12 Niskin bottles (8lt) made by PVC with rubber coated o rings and stainless steel ss springs. Seawater samples (150 mL) were collected from selected depths of the water column (2, 20, 50, 75, 100 m) for the identification and enumeration of phytoplankton cells (>= 5 µm). The samples were fixed with Lugol solution and concentrated to 25 mL by sedimentation. Phytoplankton species abundance was determined with an inverted light microscope (OLYMPUS IX70) according to the Utermohl method (Utermohl, 1958).

Abundance of microplankton in the eastern Mediterranean Sea in March and April 2008 during SES_GR1

The dataset is based on samples taken from 12 stations in Southern Aegean Sea, Northern Aegean Sea, Ionian Sea and Libyan Sea during March-April 2008. 12 Niskin bottles (8lt) made by PVC with rubber coated o rings and stainless steel ss springs. Seawater samples (150 ml) were collected from selected depths of the water column (2, 20, 50, 75, 100 m) for the identification and enumeration of phytoplankton cells (>=5 µm). The samples were fixed with Lugol solution and concentrated to 25 ml by sedimentation. Phytoplankton species abundance was determined with an inverted light microscope (OLYMPUS IX70) according to the Utermohl method (Utermohl, 1958).

Development of Robotized Laser Welding Applications for Joining Thin Sheets

Laser Welding (LW) is more often used in manufacturing due to its advantages, such as accurate control, good repeatability, less heat input, opportunities for joining of special materials, high speed, capability to join small dimension parts etc. LW is dedicated to robotized manufacturing, and the fabrication cells are using various level of flexibility, from specialized robots to very flexible setups. This paper features several LW applications using two industrially-scaled manufacturing cells at UPM Laser Centre (CLUPM) of Polytechnical University of Madrid (Universidad Politécnica de Madrid). The one dedicated to Remote Laser Welding (RLW) of thin sheets for automotive and other sectors uses a CO2 laser of 3500 W. The second has a high flexibility, is based on a 6-axis ABB robot and a Nd:YAG laser of 3300 W, and is meant for various laser processing methods, including welding. After a short description of each cell, several LW applications experimented at CLUPM and recently implemented in industry are briefly presented: RLW of automotive coated sheets, LW of high strength automotive sheets, LW vs. laser hybrid welding (LHW) of Double Phase steel thin sheets, and LHW of thin sheets of stainless steel and carbon steel (dissimilar joints). The main technological issues overcame and the critical process parameters are pointed out. Conclusions about achievements and trends are provided.

Pasarela peatonal sobre el río Ulla, provincia de Lugo (Galicia)

Se trata de un proyecto de pasarela peatonal colgante sobre el río Ulla, de aproximadamente 36 metros de luz. La especial belleza del área natural en que se situará llevó a la opción de un diseño claro y sencillo para lograr su integración en el lugar. Se busca que la pasarela pase lo más desapercibida posible y deje el protagonismo para el entorno, el río y la naturaleza misma. La difícil accesibilidad de la zona condicionó el diseño y los procedimientos constructivos a adoptar. Se optó por una tipología de pasarela colgante de cables de acero, tablero de madera de castaño y soportes de madera laminada cilíndrica, sobre unos estribos de hormigón armado parcialmente ocultos gracias a su integración en la topografía del lugar. El diseño modular del tablero, construido a base de piezas prefabricadas de madera de castaño que se ensamblan entre sí, permite el montaje en seco mediante avance del tablero sin necesidad de cimbra. Su diseño con dos capas cruzadas de entablado solidarizadas proporciona al conjunto un comportamiento estructural similar al de una placa maciza de madera. This is the project of a suspension footbridge over the Ulla River. It has a span of about 36 meters. The beauty of the natural surroundings where it is located guided the design to the option of a clear and simple proposal with the aim of achieving an integrated project for the area. The footbridge tries to be as invisible as possible with the purpose of maintaining the natural quality of the river and its surroundings. The difficult access to the area conditioned the design and the construction procedures chosen. A suspension footbridge with stainless steel cables, chestnut timber deck and cylindrical glulam piles was designed in the end. The reinforced concrete abutments are partially concealed thanks to their integration in the topography of the area. The deck is built of prefabricated chestnut timber modules that can be joined together at the construction site and can be assembled without the necessity of scaffolding over the river. The design of the deck, with two crossed layers of chestnut boards screwed down together, permits a structural behaviour similar to a solid wooden slab.

An Experimental and Numerical Study of Ballistic Impacts on a Turbine Casing Material at Varying Temperatures

An experimental and numerical study of ballistic impacts on steel plates at various temperatures (700ºC, 400ºC and room temperature) has been carried out. The motivation for this work is the blade‐off event that may occur inside a jet engine turbine. However, as a first attempt to understand this complex loading process, a somewhat simpler approach is carried out in the present work. The material used in this study is the FV535 martensitic stainless steel, which is one of the most commonly used materials for turbine casings. Based on material test data, a Modified Johnson‐Cook (MJC) model was calibrated for numerical simulations using the LS‐DYNA explicit finite element code (see Figure 1). To check the mesh size sensitivity, 2D axisymmetric finite element models with three different mesh sizes and configurations were used for the various temperatures. Two fixed meshes with 64 and 128 elements over the 2mm thick plate and one mesh with 32 elements over the thickness with adaptive remeshing were used in the simulations. The formation of adiabatic shear bands in the perforation process has been found critical in order to achieve good results. Adiabatic shear bands are formed by the temperature rise due to the accumulation of plastic strain during impact (see Figure 2). The influence of the thermal softening in the plastic model has hence been analyzed for the room temperature impact tests, where the temperature gradient is highest

Flow and fracture behaviour of high performance alloys

Based on our needs, that is to say, through precise simulation of the impact phenomena that may occur inside a jet engine turbine with an explicit non-linear finite element code, four new material models are postulated. Each one of is calibrated for four high-performance alloys that can be encountered in a modern jet engine. A new uncoupled material model for high strain and ballistic is proposed. Based on a Johnson-Cook type model, the proposed formulation introduces the effect of the third deviatoric invariant by means of three different Lode angle dependent functions. The Lode dependent functions are added to both plasticity and failure models. The postulated model is calibrated for a 6061-T651 aluminium alloy with data taken from the literature. The fracture pattern predictability of the JCX material model is shown performing numerical simulations of various quasi-static and dynamic tests. As an extension of the above-mentioned model, a modification in the thermal softening behaviour due to phase transformation temperatures is developed (JCXt). Additionally, a Lode angle dependent flow stress is defined. Analysing the phase diagram and high temperature tests performed, phase transformation temperatures of the FV535 stainless steel are determined. The postulated material model constants for the FV535 stainless steel are calibrated. A coupled elastoplastic-damage material model for high strain and ballistic applications is presented (JCXd). A Lode angle dependent function is added to the equivalent plastic strain to failure definition of the Johnson-Cook failure criterion. The weakening in the elastic law and in the Johnson-Cook type constitutive relation implicitly introduces the Lode angle dependency in the elastoplastic behaviour. The material model is calibrated for precipitation hardened Inconel 718 nickel-base superalloy. The combination of a Lode angle dependent failure criterion with weakened constitutive equations is proven to predict fracture patterns of the mechanical tests performed and provide reliable results. A transversely isotropic material model for directionally solidified alloys is presented. The proposed yield function is based a single linear transformation of the stress tensor. The linear operator weighs the degree of anisotropy of the yield function. The elastic behaviour, as well as the hardening, are considered isotropic. To model the hardening, a Johnson-Cook type relation is adopted. A material vector is included in the model implementation. The failure is modelled with the Cockroft-Latham failure criterion. The material vector allows orienting the reference orientation in any other that the user may need. The model is calibrated for the MAR-M 247 directionally solidified nickel-base superalloy.

Fracture propagation and stress corrosion in the case of dissimilar laser hybrid welded joints

The paper addresses the fracture propagation and stress corrosion behaviour of laser hybrid welds achieved between low carbon steel and stainless steel thin sheets. The crack propagation within these overmatched in strength welds was investigated by crack tip opening displacement (CTOD) on CT specimens notched transverse to the weld. A Digital Image Correlation System was used to qualify and estimate the initial crack length obtained by fatigue. The results are associated with the fractographic examinations of various regions of laser hybrid joints. Stress corrosion behaviour of the joint is also discussed.

Tolerancia al daño de acero inoxidable austeno-ferrítico trefilado con resistencia de acero de pretensar

En este trabajo se determina la tolerancia al daño de un acero inoxidable austeno-ferrítico trefilado hasta obtener resistencia propias del acero de pretensado. Para ello se han realizado ensayos de fractura sobre alambres con secciones transversales debilitadas por fisuras de fatiga propagadas desde la superficie exterior. La medida de la tolerancia al daño adoptada es la curva empírica carga de rotura-profundidad de fisura. Para valorar cuantitativamente los resultados, se utilizan las curvas de dos aceros de pretensar eutectoides, respectivamente fabricados por trefilado y por tratamiento térmico de templado y revenido, así como un modelo elemental de colapso plástico por tracción para alambres fisurados. La microestructura austeno-ferrítico de los alambres inoxidables adquiere una marcada orientación en la dirección de trefilado, que induce una fuerte anisotropía de fractura en los alambres y condiciona su mecanismo macroscópico de colapso a tracción cuando están Asurados. Para observar este mecanismo se ha utilizado la técnica VIC-2D de adquisición y análisis computerizado de imágenes digitales en ensayos mecánicos, aplicándola a ensayos de fractura a tracción realizados con probetas planas de alambre inoxidable trefilado Asuradas transversalmente. Damage tolerance of a high strength cold-drawn ferritic-austenitic stainless steel is assessed by means of tensile fracture tests of cracked wires. A fatigue crack was transversally propagated from the wire surface. The damage tolerance curve of the wires results from the empirical failure load when given as a function of crack depth. As a consequence of cold drawing, the wire microstructure is orientated along its longitudinal axis and anisotropic fracture behavior is found at macrostructural level at the tensile failure of the cracked specimens. An in situ optical technique known as video image correlation VIC-2D was used to get an insight into this failure mechanism by tensile testing transversally fatigue cracked plañe specimens extracted from the cold-drawn wires. Additionally, the experimentally obtained damage tolerance curve of the cold-drawn ferritic-austenitic stainless steel wires is compared with that of the two types of high strength eutectoid wires currently used as prestressing steel for concrete. An elementary plástic collapse model for tensile failure of surface cracked wires is used to assess the damage tolerance curves.

Overall and local mechanical behaviour of dissimilar laser welded joints

The present investigation addresses the overall and local mechanical performance of dissimilar joints of low carbon steel (CS) and stainless steel (SS) thin sheets achieved by laser welding in case of heat source displacement from the weld gap centreline towards CS. Microstructure characterization and residua! strain scanning, carried out by neutron diffraction, were used to assess the joints features. It was found that the heat source position influences the base metals dilution and the residua! stress field associated to the welding process; the transverse residual stress is smaller than for the longitudinal component, of magnitudes close to the parent CS yield strength. Furthermore, compressive transverse residual stresses were encountered at the SS-weld interface. The tensile behavior of the joint different zones assessed by using a video-image based system (VIC-2D) reveals that the residual stress field, together with the positive difference in yield between the weld metal and the base materials protects the joint from being piastically deformed. The tensile loadings of flat transverse specimens generate the strain localization and failure in CS, far away from the weld.En este trabajo se exponen los resultados de una investigacion sobre el comportamiento mecanico de soldaduras disimiles acero inoxidable-acero al carbono, realizadas para unir chapas delgadas, desplazando la fuente de calor del eje longitudinal de la union soldada por laser sobre el acero al carbono. Se han determinado las caracteristicas microestructurales de la union soldada, las tensiones residuales generadas (mediante difraccion de neutrones) y las curvas tension-deformacion locales y globales, mediante medidas locales de deformacion empleando el sistema VIC-2D "video image correlation". El desplazamiento de la fuente de calor infiuye en la dilution de los metales base y el campo de tensiones residuales asociado al proceso de soldeo; las tensiones residuales medidas en direction longitudinal se aproximan al limite elastico del acero al carbono, mientras que las tensiones residuales transversales son menores, e incluso de compresion. El ensayo a traccion de la union soldada revela que las tensiones residuales y la diferencia de limite elastico entre los metales base y la soldadura propician que la rotura se produzca por inestabilidad plastica del acero al carbono, lejos de la soldadura, sin que la union plastifique.

Electrophoretic Deposition of Transparent ZnO Thin Films from Highly Stabilized Colloidal Suspensions

The parameters that control the stability of ZnO-nanoparticles suspensions and their deposition by electrophoretic deposition were studied, so as to organize the assembly and compaction of nanoparticles. The addition of cationic polyelectrolyte - Polyethylenimine (PEI) - with different molecular weights was investigated, in order to study their effectiveness and the influence of the molecular weight of the organic chain on suspensions dispersion. It was found that PEI with the highest molecular weight provided better dispersion conditions. Cathodic EPD was performed under previously optimized suspensions conditions and over electropolished stainless steel substrates. Experimental results showed that the EPD process in these conditions allows obtaining dense transparent ZnO thin films. Deposition times and intensities were optimized by analyzing the resulting thin films characteristics. Finally, the deposits were characterized by FE-SEM, AFM, and different spectroscopic techniques.