Search

The influence of Hf additions on the glass-forming ability (GFA), phase formation and mechanical properties of Cu50HfxZr50-x (x = 2,5,10,20 at.%) alloys has been systematically investigated. We report on a distinct correlation between phase formation and GFA of Cu50Zr50-based alloys. Increasing additions of Hf reduce the thermal stability of the high-temperature B2 Cu(Hf,Zr) phase, while the thermal stability of the corresponding undercooled melt is enhanced. The GFA of these alloy series gradually raises up to 10 at.% Hf, whereas at 20 at.%Hf, the GFA is drastically lowered, since the B2 Cu(Hf,Zr) phase becomes unstable and the precipitation of the low-temperature equilibrium phases is favoured. This interrelation determines the microstructure and results in the formation of Cu-Hf-Zr-based bulk metallic glass composites. These composites not only show appreciable macroscopic plastic strain, but also high yield strength. Keywords: Metallic glasses, Glass-forming ability, Composites, Continuous cooling transformation (CCT) diagram, Mechanical properties

Structural heterogeneities in monolithic metallic glasses, i.e. free volume variations or stress/strain fields, are known to be pivotal for their plasticity but the mechanisms how they affect irreversible deformation remain poorly understood. We show that flash-annealing is a capable tool for modifying the free volume content and its distribution, which creates non-affine stress fields in a monolithic CuZr-based bulk metallic glass. Rather than the overall free volume, μm-scale regions of relaxed and rejuvenated glass govern plastic deformation. Complementary molecular dynamics simulations underpin the importance of the interfaces between relaxed and rejuvenated volumes for shear band proliferation. Not only can we reach unmatched states of metastability in metallic glasses with the present approach but also better understand the mechanisms underlying plasticity in monolithic but structurally heterogeneous metallic glasses.

This study investigates the effect, that replacing Zr in a glass-forming Cu47.5Zr47.5Al5 alloy by Sc (0–2 at.%) has on the phase formation as well as on the thermal and mechanical properties. Even though it is not reflected in the thermal data, the glass-forming ability (GFA) is significantly reduced. This originates from the increased tendency to precipitate the shape-memory phase B2 CuZr(Sc), which, in turn, promotes the formation of bulk metallic glass (BMG) matrix composites. Sc appears to be very effective in stabilizing the B2 crystals because it forms the stable B2 CuSc phase with a similar lattice constant like B2 CuZr. By adjusting the casting parameters, the composite microstructure of Cu47.5Zr46.5Al5Sc1 can be controlled to a certain extent. The yield strength and the plasticity of the present composites depend on the crystalline volume fraction. In-situ high-energy X-ray diffraction reveals that deformation proceeds in three stages: (i) martensitic transformation of the B2 phase, (ii) yielding of the amorphous phase and continuing martensitic transformation, (iii) completion of the phase transformation and plastic deformation of all phases. Our work suggests that Sc is a promising candidate to adjust the microstructure and, thus, the mechanical properties of CuZr-based composites consisting of a glassy matrix and shape-memory crystals.

Compact specimens were produced by selective laser melting (SLM) from glass-forming Zr52.5Cu17.9Ni14.6Al10Ti5 powder. Below a critical energy density of Ecrit = 15 J/mm3 fully glassy samples were obtained. When the energy density is higher, the metastable big cube phase, stabilized by oxygen, precipitates next to other crystalline phases. We introduce density contour maps to identify the process window, which allows obtaining fully glassy samples with a high relative density of up to 98.5%. The systematic parameter variation illustrates the importance of laser power for obtaining dense SLM parts. Moreover, the distribution of pores in the present alloy is rather sensitive to the scanning strategy. The compressive strength of the SLM samples is comparable to values measured for as-cast glasses and even a distinct plastic strain is found. Finally, scaffolds were produced and high-energy X-ray diffraction proves that they are fully glassy irrespective of differences in the local cooling rates. Our experiments contribute to better understanding the behaviour of Zr52.5Cu17.9Ni14.6Al10Ti5 during SLM and for making glass-forming alloys progressively more accessible to laser-based additive manufacturing in order to overcome the intrinsic size limitation of bulk metallic glasses. Keywords: Selective laser melting, Metallic glass, Porosity, Mechanical properties, High-energy X-ray diffraction

Two shape-memory alloys with the nominal compositions (in wt.%) Cu–11.85Al–3.2Ni–3Mn and Cu–11.35Al–3.2Ni–3Mn–0.5Zr were prepared by selective laser melting (SLM). The parameters were optimised to identify the process window, in which almost fully dense samples can be obtained. Their microstructures were analysed and correlated with the shape-memory behaviour as well as the mechanical properties. Suction-cast specimens were also produced for comparison. Mainly, β 1′ martensite forms in all samples, but 0.5 wt.% of Zr stabilises the Y phase (Cu2AlZr), and its morphology depends on the thermal history and cooling rate. After annealing, the Y phase is primarily found at the grain boundaries hampering grain coarsening. Due to the relative high cooling rates applied here, Zr is mostly dissolved in the martensite in the as-prepared samples and it has a grain-refining effect only up to a critical cooling rate. The Zr-containing samples have increased transformation temperatures, and the Y phase seems to be responsible for the jerky martensite-to-austenite transformation. All the samples are relatively ductile because they mostly fracture in a transgranular manner, exhibiting the typical double yielding. Selective laser melting allows the adjustment of the transformation temperatures and the mechanical properties already during processing without the need of a subsequent heat treatment.

In order to obtain metastable β-type bulk metallic glass composites (BMGCs), understanding the thermodynamic stability of the β phase is crucial. The interface between β-Ti and the supercooled liquid in BMGCs is revealed to play an important role on stabilizing metastable β-Ti during solidification. Additional interfacial energy hampers the formation of α-Ti laths at the interface, and the critical cooling rate required to suppress the transformation from β-Ti to α-Ti in BMGCs is reduced. The result implies that metastable β-Ti in BMGCs is prone to precipitate ω-Ti rather than α-Ti, which is significant on understanding the microstructures of β-type BMGCs.

In this paper, we present a thorough stress analysis of the Cu Zr metallic-glass composite with embedded B2 particles subject to a martensitic transformation. Within the framework of the Eshelby theory, we are able to explain, in a quantitative manner, (1) the formation of three types of shear bands with distinct morphologies as observed experimentally in the severely deformed Cu Zr metallic-glass composite and (2) the work hardening ability of the Cu Zr metallic-glass composite as related to the coupled effects of elastic back stress and elastic mismatch caused by the martensitic transformation. Furthermore, we also discuss the issues about the stress affected zone of the individual B2 phase and the stability of the crystalline–amorphous interface. Given the general agreement between the theoretical and experimental findings, we believe that the outcome of our current work can lead to a deeper understanding of the transformation-induced plasticity in the Cu Zr based metallic glass composites, which should be very useful to the design of the metallic-glass composites with improved ductility.

Bei der Begutachtung des Rotatorenmanschettenschadens der Schulter lag bisher der Fokus auf der Analyse des Unfallgeschehens mit der Kernaussage, dass bestimmte Unfallablaufe „geeignet“ sind, eine Verletzung an der Rotatorenmanschette zu verursachen, andere wiederum nicht. Trotz vielfaltiger wissenschaftlicher Erkenntnisse uber die Entstehung der Erkrankung der Sehnenplatte der Rotatorenmanschette gibt es keine neuen Ergebnisse daruber, unter welchen Bedingungen es zur isolierten oder kombinierten Verletzung einer gesunden Sehne an der Schulter kommt. Im Blick auf grundsatzliche Urteile des Bundessozialgerichtes aus 2005, 2006 und 2012 ist im Bereich der gesetzlichen Unfallversicherung die arztliche Begutachtung des Rotatorenmanschettenschadens vorrangig an den tatsachlichen und individuellen medizinischen Befunden zu orientieren. Dies setzt voraus, dass der Gutachter den aktuellen wissenschaftlichen Kenntnisstand der Analyse der medizinischen Befundtatsachen zugrunde legt. Nur dann kann er dem Befund einen Wert beimessen, den dieser fur die Beantwortung der Fragestellung hat. Diese Arbeit ubermittelt die Rechtsgrundlagen fur die Begutachtung und das derzeitige medizinische Wissen um die Schadigung der Rotatorenmanschette der Schulter.

Verfugbare Daten uber die Inzidenz von Komplikationen nach schulterarthroskopischen Eingriffen sind unvollstandig, zumal Entitaten wie Low-grade-Infektionen bisher unzureichend definiert und untersucht sind. Diese konnen sich klinisch z. B. als protrahierte Schmerzsymptomatik oder Schultersteife ohne eindeutige paraklinische Infektparameter prasentieren. Neben einer Ubersicht der verfugbaren Literatur beschreibt der vorliegende Artikel einen diagnostischen und therapeutischen Algorithmus zur Therapie von Low-grade-Infektionen der Schulter nach schulterarthroskopischen Eingriffen.

The Ti 36.2 Zr 30.3 Cu 8.3 Fe 4 Be 21.2 (at.%) bulk metallic glass (BMG) exhibits a regular micrometer-sized pattern in the transmission electron microscope (TEM) after ion milling. Quantitative energy-dispersive X-ray spectroscopy (EDX) results show that the compositions in the bright and dark regions are distinctly different, and the compositions gradually change with the contrast of the pattern. In the intermediate regions (with grey contrast) preferential crystallization is observed and this confirms that microscale heterogeneities exist in the ion-milled TEM specimens. On the contrary, the specimens prepared by focused ion beam and by electrolytic thinning show featureless microstructures in the TEM. Moreover, EDX results and the secondary ion mass spectroscopy show that the constituent elements are homogeneously distributed. An ion milling-induced compositional fluctuation mechanism is proposed, and the partial devitrification can be explained based on this mechanism. The present findings may lead to a deeper understanding of the occurrence of micrometer-sized heterogeneities in BMGs induced by ion milling.

In this work, the effect of Si additions on the glass-forming ability (GFA) and the mechanical behaviour of a Ti42.5Cu42.5Ni7.5Zr7.5 alloy is investigated. An optimum GFA occurs for addition of 0.5 at% Si and it is explained based on a balance between two factors: an increased thermal stability of the supercooled liquid and the detrimental effect of Ti5Si3 on vitrification. On rapid cooling, composites consisting mainly of the cubic B2 phase and glass can form. Their plasticity increases with increasing Si additions without sacrificing their high yield strength. A characteristic core–shell microstructure is formed in the rod with 2 at% Si, for which the combination of an amorphous outer surface and a refined dendritic structure in the centre gives rise to a composite with enhanced mechanical properties.

In the present work, the wetting behaviour of the Cu–GaX (X = 10–30 wt.%) liquid alloys on 304L steel was investigated in vacuum at temperatures between 1123 and 1373 K. Contact angle and surface tension measurements were performed using the sessile drop setup. In general, the Cu–GaX (X = 10–30 wt.%) alloys show good or even excellent wetting on 304L steel. However, the wetting mechanism strongly depends on the Ga content. While for Ga-poor alloys secondary wetting occurs, there is a partial dissolution of steel grains combined with an austenite-to-ferrite transformation for larger Ga contents. Cu penetrates along the grain boundaries of the substrate and provides a path for Ga diffusion into the steel. The dissolution of steel grains at the interface is suggested to be responsible for slowing down of the spreading at elevated temperatures. Understanding these interrelations between microscopic and macroscopic effects is important for the development of new Cu-based liquid alloys containing Ga, especially for applications involving steels. Keywords: Brazing, Reactive wetting, Gallium, Copper, Steel, Phase transformation

The effects of minor Ti addition on the thermal stability of B2 CuZr phase, the microstructure and the martensitic transformation (MT) in Cu 50 Zr 50−x Ti x (x = 0, 2.5, 7.5 and 10 at%) alloys were investigated. It was found that the crystallization products, i.e. Cu 10 Zr 7 and Cu(Ti, Zr) 2 , of Cu–Zr–Ti amorphous alloys transform to B2 CuZr phase at high temperatures. The corresponding eutectoid transformation temperature gradually increases with increasing Ti content, implying the decrease of the thermodynamic stability of the B2 CuZr phase. The microstructures of Cu–Zr–Ti martensitic alloys were proven to contain B2 CuZr, CuZr martensite, Cu 10 Zr 7 , Cu(Ti, Zr) 2 , and ZrTiCu 2 crystals. Dilatometric measurements reveal that the MT temperature reduces with increasing Ti content, which would be of electronic nature. With increasing thermal cycles, the MT temperature gradually decreases while the reverse MT temperature increases, which results from the enhancement of the dislocation density, the partial decomposition of the equiatomic CuZr crystals and the partially reversible MT.

This present article summarizes established and current developments and aspects of rotator cuff surgery. Achieved milestones as well as current approaches are presented and assessed with respect to their clinical and radiographic impact. Despite biomechanical and technical improvements in modern rotator cuff repair techniques, re-defect and re-tearing rates could not be fully eliminated. Meanwhile, the importance of biological processes around successful tendon-bone reintegration has been increasingly recognized. Hence, this article presents the current scientific standing regarding biological growth factors, platelet-rich plasma and rotator cuff augmentation techniques (with allogenic/autologous grafts). In summary, there are clear biomechanical advantages as well as many promising approaches to biological augmentation; however, the latter have not yet been transferred into regular clinical application.

The glass formation in the Ti–Cu system is revisited by means of the predictive γ* and λ + Δh1/2 amorphization criteria. Rapidly solidified ribbons of six selected compositions were investigated and in order to improve the glass-forming ability (GFA) minor amounts of Si were added to the best glass former predicted, Cu54Ti46. A series of (Cu0.54Ti0.46)100−xSix (x = 0.5, 1, 2) ribbons and rods with a diameter of 1 mm were prepared and analysed regarding their phase formation and thermal stability. For the alloy with the maximum GFA, (Cu0.54Ti0.46)99Si1, the critical diameter for glass formation is below 1 mm. Nevertheless, a good correlation was found between the experimentally determined GFA of the alloys and the prediction given by the λ+(Δh)1/2 and γ* criteria. The addition of Si decreases the liquidus temperature and promotes the precipitation of the Cu4Ti3 phase instead of γ-TiCu.

Reconstruction of tendon integrity to maintain glenohumeral joint centration and hence to restore shoulder functional range of motion and to reduce pain.Isolated or combined full-thickness subscapularis tendon tears (≥upper two-thirds of the tendon) without both substantial soft tissue degeneration and cranialization of the humeral head.Chronic tears of the subscapularis tendon with higher grade muscle atrophy, fatty infiltration, and static decentration of the humeral head.After arthroscopic three-sided subscapularis tendon release, two double-loaded suture anchors are placed medially to the humeral footprint. Next to the suture passage, the suture limbs are tied and secured laterally with up to two knotless anchors creating a transosseous-equivalent repair.The affected arm is placed in a shoulder brace with 20° of abduction and slight internal rotation for 6 weeks postoperatively. Rehabilitation protocol including progressive physical therapy from a maximum protection phase to a minimum protection phase is required. Overhead activities are permitted after 6 months.While previous studies have demonstrated superior biomechanical properties and clinical results after double-row compared to single-row and transosseous fixation techniques, further mid- to long-term clinical investigations are needed to confirm these findings.

Three different Cu–Zr–Co alloys, namely Cu 40 Zr 37.5 Co 22.5 , Cu 42.5 Zr 45 Co 12.5 and Cu 49 Zr 49 Co 2 , were obtained by rapid cooling. The microstructure and phase formation of as-cast rods with diameters of 2 mm are compared with those of the respective ingots. An increasing Co content stabilises the B2 CuZr phase and leads to the precipitation of a ternary Cu–Zr–Co phase. The variation of the cooling rate affects the size of the B2 dendrites as well as the volume fraction and the morphology of the interdendritic phases. The mechanical properties were determined in compression and all alloys show a certain plastic deformability despite the presence of several binary and ternary intermetallic phases. The deformation mechanisms are discussed on the basis of the microstructures and the constituent phases.

By modifying the cooling rate, a Cu 50 Zr 45 Ti 5 alloy with various structures was developed. A fully glassy rod and specimens with different sizes and volume fractions of nanocrystals were produced. The relationship between the structure and mechanical properties of the Cu 50 Zr 45 Ti 5 alloy was investigated. The different structures result in a transition of the deformation mechanism from being dominated by shear banding to being governed by dislocation action accompanied by shear band formation. These different plastic deformation mechanisms were discussed in the framework of self-organized critical behavior.

A dendrite reinforced metallic glass matrix composite: Ti48Zr20Be15V12Cu5 exhibits distinguished work hardening during dynamic plastic flow, accompanied by the ultimate strength of 2700 MPa and the maximum fracture strain of 10.6%. The large plasticity is macroscopically accommodated by the “ductile framework”, microscopically characterized by multiple dislocations and severe lattice distortion within dendrites. To our knowledge, the present results are the first to get a distinguished work-hardening capacity and to elucidate the flow mechanism of in-situ dendrite reinforced metallic glass matrix composites upon dynamic compression.

Hintergrund: Die diffuse Peritonitis ist ungeachtet moderner chirurgischer und intensivmedizinischer Therapieverfahren eine Erkrankung mit hoher Morbiditat und Mortalitat. Ziel dieser Arbeit war es, im eigenen Krankengut den Stellenwert der Relaparotomie „on demand“ (ROD) bei Patienten mit diffuser Peritonitis kritisch zu evaluieren. Patienten und Ergebnisse: In einer retrospektiven Untersuchung wurden die Therapieverlaufe von 231 Patienten mit diffuser Peritonitis analysiert. Diese wiesen einen durchschnittlichen Mannheimer Peritonitis-Index (MPI) von 25,3 auf. Die Gesamtletalitat im untersuchten Kollektiv betrug 14,3 %. Bei 214 Patienten gelang wahrend der Indexoperation eine suffiziente Fokussanierung, sodass diese im Rahmen des ROD-Konzepts weiterbehandelt wurden. Bei 178 dieser Patienten bestand keine Notwendigkeit einer Reoperation, wahrend 36 dieser Patienten im weiteren Verlauf relaparotomiert wurden. Die Letalitat dieser beiden Subgruppen betrug 9 % (keine Relaparotomie) bzw. 27 % (Relaparotomie). Schlussfolgerung: Anhand des untersuchten Kollektivs zeigt sich, dass das Konzept der Relaparotomie „on demand“ nach effektiver Herdsanierung und entsprechender suffizienter Lavage im klinischen Alltag sinnvoll und praktikabel ist. Allerdings besteht weiterhin die dringliche Notwendigkeit, Parameter zu identifizieren, welche die Selektion von Patienten zur Relaparotomie vereinfachen.

Starting from the brittle Cu46Zr46Al8 bulk metallic glass (BMG), the effect of substituting Al by Ti on the glass-forming ability (GFA) and the mechanical properties is systematically investigated. The supercooled liquid region (ΔTx), the reduced glass transition temperature (Trg=Tg/Tliq) and the γ parameter (γ=Tx/(Tg+Tliq)) tend to decrease with increasing Ti content in the present Cu46Zr46Al8−xTix (0≤x≤8) alloys. An increasing distance from the eutectic point might be the origin of the reduced GFA after the Ti addition. At the same time, the Ti additions significantly increase the plasticity of the respective alloys. The Cu46Zr46Ti3.2Al4.8 bulk glassy alloy is found to have the largest plastic strain in compression of around 12% and a fracture strength up to 1950 MPa while the Ti-free Cu46Zr46Al8 BMG exhibits values of 0% and 1754 MPa, respectively. The statistics of the serrated flow behavior, which is closely related with the dynamics of shear bands, are also investigated. The macroscopic and microscopic mechanisms, which contribute to the enhancement of malleability, are analyzed.

We report on the effect of Al and Co alloying in vitreous Cu50Zr50 on local deformation and serrated flow as a model for relating the size and localization of shear transformation zones (STZ) to Poisson ratio and strain-rate sensitivity of metallic glasses. Alloying with Al results in significant variations in mechanical performance, in particular, in Young's modulus, hardness and strain-rate sensitivity. Increasing strain-rate sensitivity with increasing degree of alloying indicates a reduced tendency for shear localization. In parallel, a gradual transition from inhomogeneous to homogeneous plastic flow is observed. Using a statistical analysis of the shear stress associated with the initiation of the first pop-in in the load-displacement curve during spherical indentation, the activation volume for plastic flow at the onset of yielding is reported. This analysis is employed for experimental evaluation of the compositional dependence of activation barrier, size and distribution of STZs. It is demonstrated that the STZ size does not change significantly upon Al alloying and encompasses a local volume of around 22–24 atoms. However, the barrier energy density for the initiation of a single STZ progressively increases. The broader distribution of STZs impedes their accumulation into larger-size flow units, leading to a lower number and reduced size of serrations in the load-displacement curve. On the contrary, lower barrier energy densities enable a larger quantity of STZs to be activated simultaneously. These STZs can easily percolate into large flow units, promoting plastic flow through their interaction. We employ Poisson's ratio as an indicator for plasticity to shown that this interpretation can be transferred to other types of metallic glasses. That is, larger flow units were found for metallic glasses with higher Poisson ratio and more pronounced plasticity, while the flow units in alloys with very low Poisson ratio and high brittleness are significantly reduced in size and more homogeneously distributed throughout the material.

Due to their inherent metastability, metallic glasses crystallize upon thermal activation, which involves nucleation and growth. It is debatable, however, whether steady-state kinetics of crystal nucleation and growth apply when glasses are heated quickly. We partially devitrified a CuZr-based bulk metallic glass at heating rates in the range of 0.08–180 K s −1 . Immediate quenching after heating preserves the partially transformed microstructure and allows direct observation of crystallite sizes and numbers. The crystallization reaction changes from eutectic to polymorphic at high heating rates and uniformly dispersed metastable shape-memory crystals precipitate in the glass. A beneficial side effect of this microstructure is a strongly enhanced room-temperature deformability. The analysis of crystal populations suggests that the nucleation rate on fast heating is effectively lower than in the steady state. At the later stage of crystallization by flash-annealing, the glass sample is traversed by a thermal front that migrates almost ten times faster than the crystal-liquid interface in levitation experiments. This phenomenon is related to the high population of crystals already present. Flash-annealing, thus, not only permits tailoring of BMG composites to overcome the intrinsic brittleness of monolithic BMGs, but also permits study of the fundamental crystallization processes in highly undercooled melts.

The glass-forming ability (GFA), the thermal stability and the crystallization behavior of Cu46Zr46Ag8 metallic glass and the thermal stability of the competing metastable B2 CuZr phase were investigated in order to fabricate the corresponding shape memory bulk metallic glass (BMG) composites based on a new prediction strategy. A rather large supercooled liquid region and a relatively low liquid fragility indicate a quite high thermal stability of the present glass. With the addition of Ag to Cu50Zr50 alloy, it becomes more difficult for the metastable B2 phase to decompose into the room-temperature equilibrium phases and to transform into martensitic phases during quenching. Based on these insights, a Cu46Zr46Ag8 BMG and its composites with different volume fractions of in situ precipitated B2 crystals were fabricated by carefully controlling the casting process. The BMG composites exhibit a larger plasticity and obvious work hardening compared to the monolithic BMG, which can be attributed to the formation of multiple shear bands and a deformation-induced martensitic transformation (MT) within the B2 crystals.

Based on thermal stability investigations, a new parameter has been introduced in order to evaluate the formation tendency of different sized CuZr-based metastable alloys with the precipitation of B2 CuZr [26] . To verify our prediction further, a Cu 46.25 Zr 44.25 Al 7.5 Er 2 alloy was prepared and its bulk metallic glass composites (BMGCs) with larger dimensions containing B2 CuZr precipitates were successfully fabricated by rapid quenching method. The composites exhibit macroscopically detectable compressive plastic strain and obvious work hardening, resulting from a deformation-induced martensitic transformation and the multiplication of shear bands. The plastic deformability of Cu 46.25 Zr 44.25 Al 7.5 Er 2 BMGCs is relatively lower than that of Cu 42.5 Zr 42.5 Al 5 BMGCs, most probably due to the intrinsic brittleness of Cu 46.25 Zr 44.25 Al 7.5 Er 2 metastable alloys and/or the inhomogeneous distribution of B2 CuZr in the amorphous matrix.

In this work, the effect of cobalt on the phase formation and mechanical properties of rapidly solidified Cu50−xCoxZr50 (x = 2, 5, 10, and 20 at. pct) alloys was investigated. CuZr martensite forms in the case of low Co contents (x = 2 and 5 at. pct), while in the alloys with 10 and 20 at. pct Co, the B2 phase is stable even at room temperature. The deformation behavior of the rods under compressive loading depends strongly on the microstructure and, thus, on the alloy composition. Cobalt affects the fracture strength of the as-cast samples, and deformation is accompanied by two yield stresses for high Co-content alloys, which undergo deformation-induced martensitic transformation.

In this work, a criterion considering the topological instability ( λ ) and the differences in the electronegativity of the constituent elements (Δ e ) was applied to the Al–La and Al–Ni–La systems in order to predict the best glass-forming compositions. The results were compared with literature data and with our own experimental data for the Al–La–Ni system. The alloy described in the literature as the best glass former in the Al–La system is located near the point with local maximum for the λ ·Δ e criterion. A good agreement was found between the predictions of the λ ·Δ e criterion and literature data in the Al–La–Ni system, with the region of the best glass-forming ability (GFA) and largest supercooled liquid region (Δ T x ) coinciding with the best compositional region for amorphization indicated by the λ ·Δ e criterion. Four new glassy compositions were found in the Al–La–Ni system, with the best predicted composition presenting the best glass-forming ability observed so far for this system. Although the λ ·Δ e criterion needs further refinements for completely describe the glass-forming ability in the Al–La and Al–La–Ni systems, the results demonstrated that this criterion is a good tool to predict new glass-forming compositions.

Cu50−xCox Zr50 (x = 0, 0.5, 1, 2, 3, 4 and 5 at.%) alloys were cast in a cylindrical copper mold by a suction casting device. In order to investigate the thermal behavior of the as-cast rods, the samples were heated from 313 to 573 K and then cooled down to about 253 K. The structure of the samples was studied by X-ray diffraction and optical microscopy. Thermal cycling measurements were also done for alloys with 2, 3, 4 and 5 at.% cobalt. It was found that increasing the cobalt content decreases martensite (Ms) and austenite (As) start temperatures, while it increases the temperature region in which austenite is stable. Thermal cycling measurements revealed that by increasing the number of cycles, the austenite start temperature increases while martensite start temperature shifts to lower temperatures.

Das Schultereckgelenk ist masgeblich an der Kraftubertragung zwischen oberer Extremitat und Thorax beteiligt. Aufgrund seiner anatomischen Besonderheiten und extremen mechanischen Beanspruchungen unterliegt es fruhzeitigen degenerativen Veranderungen, die zunachst magnetresonanztomographisch, spater auch nativradiologisch erfasst werden konnen. Therapeutisch wegweisend ist daher die klinische Untersuchung, um symptomatische von asymptomatischen Schultereckgelenkarthrosen zu unterscheiden. Differenzialdiagnostisch mussen begleitende Pathologien im Subakromialraum oder Glenohumeralgelenk abgegrenzt werden. Hierzu werden lokale Infiltrationstests angewendet. Scheitern konservative Therapiemasnahmen, ist das Ziel der operativen Behandlung die Entlastung des Gelenks mit Resektion arthrotischer Anteile und Behebung des schmerzhaften Kontakts der knochernen Gelenkpartner unter weitestgehender Aufrechterhaltung der ligamentaren Stabilitat. Hierbei hat sich die arthroskopische Resektion der lateralen Klavikula als ein Standardverfahren etabliert. Der vorliegende Artikel stellt diagnostische Masnahmen, operative Techniken und deren Resultate sowie potenzielle Komplikationen vor.

Ti-based bulk metallic glasses (BMGs) with large compressive plasticity were developed in the Ti-rich part of Vitreloy series BMGs (Ti65–x Zr x Cu9Ni8Be18 alloys with x = 0, 5, 10, 15, and 20). The current materials exhibit high fracture strength reaching ~2.3 GPa and plastic strains up to ~8.3 pct after partial substitution of Zr by Ti. The plasticity of the investigated alloys strongly depends on the Zr content, which affects the elastic constants, such as Poisson’s ratio and shear modulus. This, in turn, has an impact on the shear transformation zone (STZ) volume and, hence, on the shear banding of the glasses.

tator cuff tears are common soft tissue injuries of the musculoskeletal system that heal by formation of repair tissue and may lead to high retear rates and joint dysfunction. In particular, tissue from chronic, large tendon tears is of such degenerative nature that it may be prone to retear after surgical repair. Besides several biomechanical approaches, biologically based strategies such as application of growth factors may be promising for increasing cell activity and production of extracellular tendon matrix at the tendon-to-bone unit. As a precondition for subsequent experimental growth factor application, the aim of the present study was to establish and characterize a human rotator cuff tendon cell culture.Long head biceps (LHB)- and supraspinatus muscle (SSP)- tendon samples from donor patients undergoing shoulder surgery were cultivated and examined at the RNA level for expression of collagen type-I, -II and -III, biglycan, decorin, tenascin-C, aggrecan, osteocalcin, tenomodulin and scleraxis (by Real-time PCR). Finally, results were compared to chondrocytes and osteoblasts as control cells.An expression pattern was found which may reflect a human rotator cuff tenocyte-like cell culture. Both SSP and LHB tenocyte-like cells differed from chondrocyte cell cultures in terms of reduced expression of collagen type-II (p≤0.05) and decorin while higher levels of collagen type-I were seen (p≤0.05). With respect to osteoblasts, tenocyte-like cells expressed lower levels of osteocalcin (p≤0.05) as well as tenascin C, biglycan and collagen type-III. Expression of scleraxis, tenomodulin and aggrecan was similar between all cell types.This study represents a characterization of tenocyte-like cells from the human rotator cuff as close as possible. It helps analyzing their biological properties and allows further studies to improve production of tendon matrix and osteofibroblastic integration at the tendon-bone unit following tendon repair.

Rotator cuff avulsion fractures represent rare lesions in younger individuals and are caused by different trauma mechanisms. The present article outlines current concepts regarding diagnosis, indications, and surgical approaches to the treatment of greater and lesser tuberosity fractures, as discussed in the international literature. Modified arthroscopic double-row rotator cuff repair techniques allow for the anatomical reduction and retention of fragments and the treatment of concomitant intra-articular lesions at the same time. Moreover, the article provides practical hints on different surgical repair techniques, their respective limitations and results from the literature.

CD95 (APO-1/Fas) and CD137 (ILA/4-1BB) are members of the tumour necrosis factor receptor family, and both are involved in induction of apoptosis in lymphocytes. Contrary to the case of CD95, apoptosis by CD137 is caused by cross-linking of the respective ligand rather than the receptor. Nothing is known so far about the mechanism of CD137-induced cell death. Here, we show that immobilized CD137 protein induces expression of CD95 in resting primary T and B lymphocytes. However, induction of apoptosis by CD137 is independent of CD95, because: (1) antagonistic anti-CD95 antibody fragments do not block CD137-induced apoptosis; and (2) CD137, but not anti-CD95, can induce apoptosis in resting lymphocytes.

The correlation between the microstructure and mechanical behavior during tensile loading of Ti68.8Nb13.6Al6.5Cu6Ni5.1 and Ti71.8Nb14.1Al6.7Cu4Ni3.4 alloys was investigated. The present alloys were prepared by the non-equilibrium processing applying relatively high cooling rates. The microstructure consists of a dendritic bcc β-Ti solid solution and fine intermetallic precipitates in the interdendritic region. The volume fraction of the intermetallic phases decreases significantly with slightly decreasing the Cu and Ni content. Consequently, the fracture mechanism in tension changes from cleavage to shear. This in turn strongly enhances the ductility of the alloy and as a result Ti71.8Nb14.1Al6.7Cu4Ni3.4 demonstrates a significant tensile ductility of about 14% combined with the high yield strength of above 820 MPa already in the as-cast state. The results demonstrate that the control of precipitates can significantly enhance the ductility and yet maintaining the high strength and the low Young's modulus of these alloys. The achieved high bio performance (ratio of strength to Young's modulus) is comparable (or even superior) with that of the recently developed Ti-based biomedical alloys.

Despite modern surgical and intensive-care concepts, diffuse peritonitis remains a major source of high morbidity and mortality. The aim of this study was to critically evaluate the value of relaparotomy on demand (ROD) for patients with diffuse peritonitis.In a retrospective analysis, the clinical course of 231 patients with diffuse peritonitis was analysed. The mean Mannheim Peritonitis Index (MPI) was 25.3. Overall lethality in this cohort was 14.3 %. In 214 patients, source control was successful during the index operation, and these patients were treated according to an on-demand strategy. For 178 of these patients, there was no demand for a relaparotomy, whereas 36 of these patients required further surgical interventions. Lethality for these subgroups was 9 % (no relaparotomy) and 27 % (relaparotomy), respectively.This retrospective analysis confirms that an on-demand strategy is reasonable and feasible after successful source control and lavage. However, it still remains of clinical importance to identify parameters that may assist in selecting those patients who require a relaparotomy.

The aim of this study was to evaluate the clinical and radiological results of 37 consecutive patients (Ø age 37.9; 4♀, 33♂) following arthroscopically assisted and image intensifier-controlled AC joint reconstruction using the double TightRope™ technique for acute AC joint separations grade V according to Rockwood.After 12 months 30 patients with a mean age of 38.8 years (range 18.6-65.8 years) could be included. The postoperative assessment included the Subjective Shoulder Value (SSV), Constant Score (CS), and Taft Score (TF) as well as radiological evaluation using bilateral stress views and bilateral Alexander views for determining vertical and horizontal AC joint instability.The clinical scores reached 91.4±9.8% for SSV, 87.8±5.2 for CS, and 10.1±2.1 points for TF. The initial coracoclavicular distance (CCD) was 22.1±5.6 mm and could be reduced to 8.6±2.8 mm postoperatively (p0.05). The CCD increased at final follow-up to 12.8±2.4 mm. The difference of the CCD compared to the contralateral side was initially 13.7±4.8 mm; postoperatively it was 0.3±3.0 mm with an increase at final follow-up to 3.6±3.5 mm. A posterior instability on the Alexander view occurred in 53.3% of patients. A correlation between inferior clinical results and horizontal instability could be detected. Only one patient was slightly tender to palpation at the AC joint.Following arthroscopic AC joint stabilization using the double TightRope™ technique, despite partial recurrent instability, favorable clinical results can be expected.

The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7. 6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22. 1±0. 9 μm and a relative momentum resolution σp/p=(4. 83±0. 16)×10-4 GeV-1×pT have been measured for high momentum tracks. © 2010 CERN for the benefit of the ATLAS collaboration.

For the interpretation of the results of long term irradiation experiments in the presence of air it is necessary to know about the penetration of oxygen into the plastic material in the course of time. Therefore the oxygen permeability of two thermoset plastics (made from two unsaturated polyester resin thermosetting moulding compounds) was measured in the temperature range 20–60°C. For the Typ 802, the following data were generated at 23°C: permeability coefficient P =3.08 × 10 -15 cm 3 ·cm⧸cm 2 ·s·Pa, diffusion coefficient D=1.03×10 -8 cm 2 ⧸s, solubility coefficient S =3.00×10 -7 cm 3 ⧸cm 3 ·Pa. The permeability of two thermoset phenol-formaldehyde plastics and one melamine-formaldehyde plastic was found to be immeasurably small, i.e. P -17 cm 3 ·cm⧸ cm 2 · s ·,Pa at 60°C. For discs of 4mm thickness made from the polyester plastics, oxygen concentration profiles were calculated which are built up in the course of time during storage in air at 23°C. For both other materials the profiles were estimated by assuming P =3×10 -17 at 60°C and the activation energy and the solubility being the same as in the case of polyester plastics.