The purpose of this paper was to compare two different testing conditions during the acquisition of biomechanical load spectra for handball shoes. Subjects performed two typical handball activities, ...i.e. feints and jump shots, either under ‘plain conditions’ (group I) or ‘close-to-reality conditions’ (group II). While subjects of group II performed their tasks with a handball and an obstacle in front of them that simulated a defense player, subjects of group I performed their tasks without any additional items. In total, 19 experienced amateur handball players provided written informed consent and participated. Kinematics and kinetics were recorded using an optoelectronic measurement system and a force plate. Biomechanical load spectra, which can be used to synthesize mechanical simulations for characterization of handball shoes, were evaluated from normalized vertical ground reaction forces, forefoot bending angles and temporal spatial parameters. Statistical tests such as one-way analysis of variance were conducted to test for significant differences between both groups. The results showed that the mean of maximum vertical ground reaction forces between both groups was significantly different for feints (2.2 body weight vs. 2.5 body weight) and jump shots (2.7 body weight vs. 3.1 body weight) with higher values for group II. The maximum bending angles during feints were not significantly different (17.6° vs. 17.2°), whereas the angles during jump shots were significantly different between both conditions (32.2° vs. 22.2°). In conclusion, subjects of group II showed higher effort in performing their tasks compared to subjects of group I. Therefore, the authors suggest that the acquisition of biomechanical load spectra should be performed under real conditions or at least ‘close-to-reality conditions’.
The purpose of this paper was to mechanically characterize handball shoes using biomechanical evaluated load spectrums. In the first step a biomechanical study with 15 experienced amateur handball ...players was conducted. Within this study the kinematics and kinetics of three typical handball activities, namely sprint, feint and jump shot, were evaluated using an optoelectronic measurement system and a force plate. After determining typical biomechanical load spectrums for handball activities from the collected data, in a second step a sample of nine handball shoes size UK 8 were mechanically tested to characterize their cushioning properties.
Die Dissertation liefert Grundlagen zur Entwicklung
eines neuartigen Farbwerkes für Offsetdruckmaschinen.
Basierend auf den experimentellen Untersuchungen zum
rheologischen Verhalten der verwendeten ...Versuchsfarbe
und zu ihrem Zerstäubungsverhalten wird der
Farbfilmbildungsprozess aus zerstäubter Offsetdruckfarbe
experimentell bestimmt. Der Farbfilmbildungsprozess
wird anschließend rechnergestützt simuliert und die
Ergebnisse mit den experimentell gewonnenen Daten
verglichen. Abschließend wird ein erstes Sprühfarbwerkskonzept
an einer Labordruckmaschine umgesetzt und die damit hergestellten
Druckproben mit Druckproben des konventionellen Walzenfarbwerks
der gleichen Druckmaschine verglichen. Die Ergebnisse
weisen die prinzipielle Eignung eines Sprühfarbwerks
in einer Offsetdruckmaschine nach.
Die Dissertation liefert Grundlagen zur Entwicklung
eines neuartigen Farbwerkes für Offsetdruckmaschinen.
Basierend auf den experimentellen Untersuchungen zum
rheologischen Verhalten der verwendeten ...Versuchsfarbe
und zu ihrem Zerstäubungsverhalten wird der
Farbfilmbildungsprozess aus zerstäubter Offsetdruckfarbe
experimentell bestimmt. Der Farbfilmbildungsprozess
wird anschließend rechnergestützt simuliert und die
Ergebnisse mit den experimentell gewonnenen Daten
verglichen. Abschließend wird ein erstes Sprühfarbwerkskonzept
an einer Labordruckmaschine umgesetzt und die damit hergestellten
Druckproben mit Druckproben des konventionellen Walzenfarbwerks
der gleichen Druckmaschine verglichen. Die Ergebnisse
weisen die prinzipielle Eignung eines Sprühfarbwerks
in einer Offsetdruckmaschine nach.
Introduction Local application of growth factors to stimulate wound and fracture healing is attracting increasing interest. We studied the effect of local application of a potent angiogenic growth ...factor, basic fibroblast growth factor (bFGF), on resistance to local infection after soft tissue trauma.
Methods For in-vitro and in-vivo experiments, we used recombinant human bFGF. The in-vitro investigations were performed by isolation of human leukocyte fractions, cytokine analysis, phagocytosis assay, flow cytometry, and LDH assay. For the in-vivo investigation, a paired comparison of infection rates was carried out on Sprague-Dawley rats after standardized, closed soft tissue trauma and local, percutaneous bacterial inoculation of different concentrations of Staphylococcus aureus (2 × 104 to 2 × 107 colony-forming units (cfu)). The lower leg was treated with 1, 10 or 100 ng bFGF (16 animals for each concentration) and without bFGF (16 animals).
Results Cytotoxic reactions due to the concentrations of bFGF used could be excluded in the in-vitro tests since incubations of isolated peripheral blood mononuclear cells (PBMCs) with increasing concentrations of bFGF for 24 h did not lead to an increase in the release of lactate dehydrogenase in the culture supernatants compared to corresponding control incubations without any bFGF added. A significant increase in cytokine release was observed after the co-incubation of PBMCs with 100 or 200 ng of the same bFGF that was used for the animal experiments. Furthermore, the capacity of phagocytes in whole blood to phagocytose bacteria was suppressed in the presence of 100 ng exogenously added bFGF. We found continuously reduced granulocytic phagocytosis in FGF-supplemented blood compared to non-supplemented blood.
In the in-vivo investigation, the infection rate for the group without bFGF was 0.25. In the groups with 1, 10 and 100 ng bFGF, the infection rates were 0.5, 0.7 and 0.8, respectively. A dose-dependent increase in infection rate was observed after local application of bFGF, compared to the untreated control group. The difference in infection rates for the groups in which 10 and 100 ng bFGF was used, relative to the group without bFGF, was statistically significant.
Interpretation If these initial results are confirmed for other potent angiogenic growth factors, then the local use of growth factors for stimulation of wound and bone healing-a main focus of current research in traumatology-will have to be reconsidered and preceded with a strict evaluation of the risks and benefits.
Purpose: The etiology of local posttraumatic infection in the locomotor system depends on the amount, virulence and pathogenicity of the inoculated microorganisms and the local/systemic host damage ...due to the type and extent of the accident or iatrogenic trauma. The relative effect of these factors remains unclear. In particular, it is still unclear today whether––in presence of microorganisms––soft tissue damage and its pathophysiological consequences lead to infection after soft tissue trauma, or whether the bacterial contamination is the primarily cause for posttraumatic infection. The aim of the project was to gain information on the consequences of a soft tissue injury in terms of resistance to local infection. Since clinical populations are too heterogeneous, the problem was investigated in a standardized, reduced (no surgery or implants) experimental in vivo model.
Method: In female Sprague–Dawley-rats with a standardized closed soft tissue trauma to the tibialis anterior muscle (group I:
n=13) or without (group II:
n=13), we compared the incidence of local infection after a pairwise local, percutaneously injected bacterial challenge with various concentrations of
Staphylococcus aureus (2×10
4–2×10
6 colony forming units, CFU). The standardized closed soft tissue trauma was created by application of a specially designed, computer controlled impact device. The contaminated soft tissue and the underlying bone were removed under sterile conditions after five days and quantitatively evaluated for bacterial growths. Infection was defined as positive bacterial growth at the soft tissue and/or bone. A stepwise experimental design with an “up-and-down” dosage technique was used to adjust the bacterial challenge in the area of the ID50 (50% infection dose). Statistical evaluation of the difference between the infection rates of both groups was performed by two-sided fisher exact test (
p<0.05).
Results: The overall infection rate was 46%. For the group with soft tissue trauma the ID50 was 1.32×10
5 CFU and 1.05×10
6 CFU for the group without soft tissue trauma. The infection rate was 69% (9 of 13 animals) for the group with soft tissue trauma and 23% (3 of 13 animals) for the group without soft tissue trauma. This difference is statistically significant (
p=0.047).
Conclusions: The infection rate after a standardized closed soft tissue injury was significantly higher and the ID50 lower than without soft tissue trauma. Our results demonstrate that in presence of microorganisms it is not primarily the bacterial contamination but rather the soft tissue damage and its pathophysiological consequences resulting in decreased infection resistance that secondarily lead to infection.
Hysteresis behaviour of highly elastic multigraft copolymers with a polyisoprene (PI) backbone and branched polystyrene (PS) arms has been interpreted by applying the extended non-affine tube model ...of filler reinforced rubber elasticity (dynamic flocculation model), which takes into account that conformational fluctuations in bulk networks are strongly suppressed by packing effects. Originally, this model was developed to describe hyperelasticity of unfilled networks, and later, stress softening and hysteresis of filler reinforced elastomer materials like carbon black and silica filled rubbers. The evaluation of stress softening is obtained via pre-strain dependent hydrodynamic amplification of the rubber matrix by a fraction of rigid filler clusters with virgin filler–filler bonds. The filler-induced hysteresis is described by a cyclic breakdown and re-aggregation of the residual fraction of more soft filler clusters with already broken filler–filler bonds. We show, for the first time that the developed concept is in fair agreement with experimental stress–strain data of superelastic PI–PS multigraft copolymers. Depending on the PS-content and their functionality multigraft copolymers form microphase separated structures according to the constituting block copolymer concept, where the PS arms act as multi-domains in a PI matrix. The adaptation of the model is based on the assumption that the PS-domains are acting similar to filler clusters. The obtained microscopic material parameters appear reasonable for the description of the structure and mechanical properties of multigraft copolymers.
Comparison of infection resistance after local bacterial challenge associated with two different designs for fixation implants: the conventional dynamic compression plate (DCP) and the point contact ...fixator (PC-Fix).
Randomized, prospective study in experimental animals. Grouped sequential experimental procedure. Observation time was twenty-eight days, with twenty animals per group.
Following surgery, animals were kept without restrictions in individual hutches.
Forty White New Zealand rabbits. Thirty-eight animals, nineteen per group, were included in the final evaluation.
Under sterile conditions, specially manufactured titanium DCP or PC-Fix of identical dimensions were fixed to rabbit tibiae. After wound closure, different concentrations of Staphylococcus aureus, between 2 x 10(4) and 2 x 10(8) colony-forming units (CFU), were inoculated percutaneously at the implant site.
Implants, underlying bone, and surrounding soft tissues were removed under sterile conditions and quantitatively evaluated for bacterial growth. Infection was defined as positive bacterial growth at the bone-implant interface.
The overall infection rate was 45 percent. The infection dose of 50 percent (ID50) was 7.08 x 10(5) CFU for the DCP group and 8.51 x 10(6) CFU for the PC-Fix group. The infection rate was 63 percent (twelve of nineteen animals) for the DCP group and 26 percent (five of nineteen animals) for the PC-Fix group. This difference was statistically significant (p = 0.022).
After local bacterial challenge, we found a statistically significant difference in the infection rates depending on the implant design. The higher infection resistance associated with the PC-Fix design seems to be related to the reduced contact area at the bone-implant interface.
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