Choice Of Spacers Research Articles

Clinical evaluation of a new technique for custom-made spacers in septic two-stage revision of total hip arthroplasties.

In septic two-stage revision surgery, success depends on numerous factors. Key steps are the procedure of ex- and reimplantation and the choice of spacer in the interim phase. The latter is still a matter of debate. Recently, we showed the microbial non-inferiority of a spacer technique using prosthetic cemented implants with an individualized antibiotic mixture in the cement applying a mechanically inferior cementation method. The aim of the present study was to evaluate the clinical results of these spacers in view of either an endofemoral or a transfemoral procedure. Our collective consisted of 86 patients (45 endofemoral and 41 transfemoral procedures). The collective was analyzed with respect to complications, reinfection rate and clinical status at the end of the interim phase. Results of an endofemoral and transfemoral approach were compared. With a median Staffelstein-Score of 60 (range 31-81) at the end of the interim phase, the first clinical results are promising. The reinfection-free rate after a median follow-up of 50months was 90%. Spacer-related complications occurred in 8% of the total collective. Comparing the endo- and transfemoral procedure, there were no statistical differences in complications or regarding the clinical and infectiological outcome. In this study, we were able to show good clinical results for the presented spacer technique. With no relevant difference in outcome, the decision for an endofemoral or transfemoral technique can be based on technical deliberations. Further prospective comparative studies are necessary to show the clinical benefit of this procedure.

New Technique for Custom-Made Spacers in Septic Two-Stage Revision of Total Hip Arthroplasties.

The choice of spacer in the interim phase of two-stage revision hip arthroplasty is crucial. Conventional concepts like a Girdlestone situation, handformed or preformed bone cement spacers show complications like soft-tissue contractions, abrasion of bone cement particles, dislocation, breakage and a low level of mobility in the interim phase. To address these disadvantages, the senior author developed a new technique for custom-made spacers in septic two-stage revision of total hip arthroplasties using prosthetic implants with individualized antibiotic mixture in the cement applying a mechanical inferior cementation method. The aim of this study was to evaluate the results of these spacers with respect to their non-inferiority in terms of reinfection and survival-rate of the new implant and to describe the complications associated with this procedure. Our collective consisted of 130 patients with a median follow-up of nearly five years. With a reinfect-free rate of 92% and a spacer-related complication rate of 10% (8% articular dislocation, 1% periprosthetic joint fracture, 1% breakage), this procedure seems to be safe and superior regarding complications compared to conventional concepts. Further studies are necessary to show the clinical benefit of this procedure.

Design and analysis of GaAs/AlAs asymmetric spacer layer tunnel diodes for high-frequency detection

Abstract In the present work, we have systematically investigated the design of Asymmetric SPAcer-layer Tunnel (ASPAT) diodes using numerical modeling employing SILVACO Atlas software. After reproducing and validating physical models using experimental data obtained from fabricated ASPAT diodes, a developed SILVACO model was used to evaluate the effect of different structure designs on two key parameters, namely the junction resistance and curvature coefficient at zero bias. The impact of the variation in the spacer layers thicknesses, emitter, collector, their doping profile, and the barrier width was thoroughly explored. It was found that the spacers and the barrier thickness are the most critical design parameters affecting the junction resistance and curvature coefficient. The insertion of an InxGa1-xAs QW layer adjacent to the AlAs barrier, combined with the appropriate choice of spacers and AlAs barrier thicknesses, contributed to an increase in the curvature coefficient by a factor of three while maintaining a low junction resistance. The cut-off frequency of a 4 × 4 μm2 ASPAT device is predicted to be > 500 GHz at zero bias. A comprehensive study is presented to guide researchers working on ASPAT devices, providing valuable prediction for appropriate design parameters toward maximizing the microwave/mm-wave device performance.

Research progress of two-stage revision for periprosthetic joint infection after hip and knee arthroplasties

To summarize the research progress of two-stage revision for periprosthetic joint infection (PJI) after hip and knee arthroplasties. The related literature on two-stage revision for PJI was summarized, and the new progress in the choice of spacers, systemic antibiotic therapy, and risk factors were analyzed. Two-stage revision is a common way to treat infection after hip and knee arthroplasties. The types of spacers used in the one-stage operation are diverse and each has its own advantages and disadvantages. Non-articular spacers are mainly used for the patients with poor soft tissue conditions around the joints and severe bone defects. But the joint mobility is not good after the placement of the spacer. Articular spacers can restore the affected joint movement after operation, which is beneficial to the joint mobility after two-stage operation. The use of antibiotics is an indispensable part of the treatment process, and the effectiveness of short-term antibiotic treatment is similar to long-term treatment. Identifying the relevant risk factors that influence the prognosis of the two-stage revision can help preoperative management and reduce the recurrence rate of infection. There are still controversies about the choice of spacers and systemic antibiotic therapy during the two-stage revision and treatment of PJI. The factors affecting the prognosis of the two-stage revision need to be explored and the further high-quality research is needed.

ESR study of molecular orientation and dynamics of TEMPO derivatives in CLPOT 1D nanochannels.

The molecular orientations and dynamics of 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) radical derivatives with large substituent groups at the 4-position (4-X-TEMPO) in the organic one-dimensional nanochannels within the nanosized molecular template 2,4,6-tris(4-chlorophenoxy)-1,3,5-triazine (CLPOT) were examined using ESR. The concentrations of guest radicals, including 4-methoxy-TEMPO (MeO-TEMPO) or 4-oxo-TEMPO (TEMPONE), in the CLPOT nanochannels in each inclusion compound (IC) were reduced by co-including 4-substituted-2,2,6,6-tetramethylpiperidine (4-R-TEMP) compounds at a ratio of 1 : 30-1 : 600. At higher temperatures, the guest radicals in each IC underwent anisotropic rotational diffusion in the CLPOT nanochannels. The rotational diffusion activation energy, Ea , associated with MeO-TEMPO or TEMPONE in the CLPOT nanochannels (6-7 kJ mol(-1) ), was independent of the size and type of substituent group and was similar to the Ea values obtained for TEMPO and 4- hydroxy-TEMPO (TEMPOL) in our previous study. However, in the case in which TEMP was used as a guest compound for dilution (spacer), the tilt of the rotational axis to the principal axis system of the g-tensor, and the rotational diffusion correlation time, τR , of each guest radical in the CLPOT nanochannels were different from the case with other 4-R-TEMP. These results indicate the possibility of controlling molecular orientation and dynamics of guest radicals in CLPOT ICs through the appropriate choice of spacer. Copyright © 2016 John Wiley & Sons, Ltd.

Accelerated ageing and durability of double-glazed sealed insulating window panes and impact on heating demand in buildings

A crucial property for double-glazed sealed insulating window panes is to maintain their thermal insulating properties and thus low U-values. However, degradation and thus subsequent reduction or loss of low-conductance gas concentration may occur in the sealed glazing units by their exposure to outdoor climate.The choice of spacers is important to keep as low thermal transport through the window panes as possible, i.e. low U-value. In addition, the type of spacers may also influence their durability and resistance towards ageing, which hence may be characterized by the low-conductance noble gas concentration, e.g. argon, krypton or xenon. Ageing and degradation of window panes may lead to a decreased or total loss of noble gas concentration and hence subsequent increased heating energy demand in buildings.Thus, several double-glazed sealed insulating window panes, with aluminium spacers and Super Spacers, have been subjected to accelerated ageing by climate ageing and elevated temperature ageing. The durability and ageing of the sealed window panes have been studied and characterized by their spacer type and gas concentration. Furthermore, the decrease of gas concentration in sealed insulating window panes and the impact on the energy performance and in particular heating demand of buildings have been investigated.

The role of spacers on the self-assembly of DNA aptamer-amphiphiles into micelles and nanotapes

The self-assembly of single-stranded DNA (ssDNA) aptamer-amphiphiles was influenced by the choice of spacer used to link the hydrophobic tail and aptamer headgroup. Aptamer-amphiphiles without spacers or with hydrophilic spacers formed globular micelles while amphiphiles with hydrophobic spacers formed bilayer nanotapes, which are the first such structures formed by DNA-amphiphiles.

Concept for High-Low Temperature Resistance Arrangement within Multilayer Flexible Composite Materials

The multilayer flexible composite (MFC) materials are extensively used in space environment, polar environment, volcano adventure, and so on as light weight insulation protection systems between room (20 ± 2°C) and high (150 ± 5°C)-low (-110 ± 5°C) operating temperature. A new concept for high-low temperature resistance arrangement is presented in this article considering heat load contributions. The main advantages of this concept consist of the structure of the materials and the choice of spacers. The structure of the MFC material consists of outer fabric, inner fabric, and a number of thin shields separated by spacers. The thermal properties of multilayer reflecting shields with different thickness of reflecting shields, different layers, different combination structures, different spacers, and different contact states were discussed in this article. The reflecting shield (6 µm polyester film + 0.03 µm aluminum film + 8 µm polyester film) is the most ideal, and polyester mesh (down added into the mesh) is the most effective spacer with thermal insulation close to the ideal condition. Finally the thin shields and spacers are chosen, and then the optimal structure of the MFC materials is obtained with respect to insulation thickness and flexibility of the material.

Computer-assisted choice of discrete spacers for anionic isotachophoresis separations

In isotachophoresis (ITP), the sample constituents migrate, depending on their concentrations in the loaded sample, either in fully developed zones or in the boundary layers between the zones of constituents of the corresponding effective mobilities. The latter (spike) migration mode is analytically beneficial in selective detections of trace analytes, especially, when appropriately chosen discrete spacers minimize detection interferences due to matrix constituents. To facilitate a search for suitable mixtures of discrete spacers, a two-step calculation procedure was developed in this work. Using a pool of discrete spacers consisting of 42 anionic and zwitterionic constituents, this procedure was shown effective in the anionic ITP separations performed at pH=6.5–10.0. Besides the predictions of the migration orders, it was helpful in identifying the spacing constituents that could cause resolution problems due to an uncertainty with which pH of the leading electrolyte solution is known. The ionic mobility and p K a data, taken for the spacing constituents from the literature and the ones obtained from the ITP experiments carried out in this work, were used in the calculations performed in a context with the choice of spacers. Although the data obtained from the ITP experiments provided better results, small uncertainties with which they were acquired (attributable to fluctuations in the experimental conditions) set practical limits in the calculation based choice of multi-component mixtures of the spacing constituents.

Photoinduced energy and electron transfer processes in rigidly bridged dinuclear Ru/Os complexes

In an attempt to elucidate the role played by the various factors—distance, geometry, electronic nature of the bridging ligand—which control the occurrence of intercomponent electronic energy and electron transfer in dinuclear systems, several photophysical studies have been reported. In this contribution we discuss the photoinduced energy and electron transfer processes occurring in rigid systems containing ruthenium and/or osmium metal units prepared in our laboratories, and compare them with the results obtained with compounds described by other authors. The choice of spacers, connections, chelating sites, and metal units used to construct photoactive systems is described.