Iron Oxide‐Labeled Collagen Scaffolds for Non‐Invasive MR Imaging in Tissue Engineering

Non‐invasive imaging holds significant potential for implementation in tissue engineering. It can be used to monitor the localization and function of tissue‐engineered implants, as well as their resorption and remodelling. Thus far, however, the vast majority of effort in this area of research have focused on the use of ultrasmall super‐paramagnetic iron oxide (USPIO) nanoparticle‐labeled cells, colonizing the scaffolds, to indirectly image the implant material. Reasoning that directly labeling scaffold materials might be more beneficial (enabling imaging also in the case of non‐cellularized implants), more informative (enabling the non‐invasive visualization and quantification of scaffold degradation), and easier to translate into the clinic (cell‐free materials are less complex from a regulatory point‐of‐view), three different types of USPIO nanoparticles are prepared and incorporated both passively and actively (via chemical conjugation; during collagen crosslinking) into collagen‐based scaffold materials. The amount of USPIO incorporated into the scaffolds is optimized, and correlated with MR signal intensity, showing that the labeled scaffolds are highly biocompatible, and that scaffold degradation can be visualized using MRI. This provides an initial proof‐of‐principle for the in vivo visualization of the scaffolds. Consequently, USPIO‐labeled scaffold materials seem to be highly suitable for image‐guided tissue engineering applications.     

Highly Robust Indium‐Free Transparent Conductive Electrodes Based on Composites of Silver Nanowires and Conductive Metal Oxides

A hybrid approach for the realization of In‐free transparent conductive layers based on a composite of a mesh of silver nanowires (NWs) and a conductive metal‐oxide is demonstrated. As metal‐oxide room‐temperature‐processed sol–gel SnO_x or Al:ZnO prepared by low‐temperature (100 °C) atomic layer deposition is used, respectively. In this concept, the metal‐oxide is intended to fuse the wires together and also to “glue” them to the substrate. As a result, a low sheet resistance down to 5.2 Ω sq^‐1 is achieved with a concomitant average transmission of 87%. The adhesion of the NWs to the substrate is significantly improved and the resulting composites withstand adhesion tests without loss in conductivity. Owing to the low processing temperatures, this concept allows highly robust, highly conductive, and transparent coatings even on top of temperature sensitive objects, for example, polymer foils, organic devices. These Indium‐ and PEDOT:PSS‐free hybrid layers are successfully implemented as transparent top‐electrodes in efficient all‐solution‐processed semitransparent organic solar cells. It is obvious that this approach is not limited to organic solar cells but will generally be applicable in devices which require transparent electrodes.     

Assessment of Constructability Practices among General Contractors

Modern construction has been characterized as a complex and fragmented process. These characteristics have produced a decrease in the quality and cost efficiency of projects. It has been proven that this problem can be partially overcome by implementing constructability, which is based on the integration of construction knowledge into design (as was done in the past). The implementation of constructability is not easy because it represents a change in the way things have been done in the last century. Prior research has found a lack of constructability efforts among participants in the construction industry, especially general contractors. Because builders can play an important role in implementing constructability, this paper assesses constructability practices among general contractors. The data were obtained from a mailed survey. It was found that contractors applied constructability concepts and participated during the earliest phase of the projects more often than is thought. In addition, the findings showed that constructability practices differed depending on the characteristics of the organization, the type of work performed, and the type of contractual arrangement.     

Mr imaging of avascular femoral head necrosis: pre- and postoperative studies

Forty-six patients with suspected avascular necrosis of the femoral head were examined by T2- and T1-weighted sequences before and after intravenous infusion of Gd-DTPA. Both sides were involved in 12 cases. The classification was done according to Ficat [1]. In early stages and in postoperative studies a correlation of signal intensity increase after infusion of Gd-DTPA and clinical symptoms was found. Contrast enhancement of the plain low signal intensity area or of the implanted graft on T1-weighted images was assumed vascularized or vital components in seven cases of Ficat I and in 13 postoperative studies. Contrawise, in seven patients with severe postoperative symptoms we found no contrast enhancement indicating avascular regions.     

Trace Enrichment and HPLC Analysis of PAHs in Edible Oils and Fat Products,using Liquid Chromatography on Electron Acceptor Stationary Phases in Connection with Reverse Phase and Fluorescence Detection

The determination of PAHs in lipids is beset with many difficulties, resulting from the low level of individual PAHs (μg/kg), the complexity of extraction and clean-up procedures required to isolate the PAHs from the oil or the food components. The purpose of this report is to describe a new method for multi-PAHs determination in lipidic matrixes. The clean-up step is realized by Donor Acceptor Complex Chromatography (DACC) with a tetrachlorophthalimidopropyl (TCPI) modified silica. Neutral lipids and other minor components, especially tocopherols which can interfere with PAH, are eluted with a hexane/methyltertiobutylether mixture. Then, PAH are eluted with pure methylene chloride and analyzed by gradient reversed phase HPLC in combination with wavelength programmed fluorescence detection. This method allows an easy and fast quantitative recovery of aromatic compounds.     

Ankle arthrodesis in patients with rheumatoid arthritis

The results of 26 ankle arthrodeses performed for rheumatoid arthritis on 21 patients were reviewed. Tibiotalar arthrodesis was performed in 14 ankles, and tibiotalocalcaneal arthrodesis was performed in 12. External fixation was used in 20 ankles, and internal fixation was used in six. Followup was available in 24 of 26 ankles (19 patients), and averaged 5 years (range, 2-8 years). There was no pain experienced in 19 ankles; mild, occasional pain was experienced in four ankles; and moderate, daily pain was experienced in one ankle. Daily activities were limited in five patients and recreational activities were limited in 11. All patients reported some difficulty walking on uneven terrain. Nearly all patients were satisfied; two were satisfied with reservations and two were dissatisfied. Union was achieved in 25 of 26 (96%) ankles. Ankle arthrodesis is an effective operation in patients with rheumatoid arthritis. Unlike previous reports, union and complication rates in this series were comparable with rates for arthrodesis for posttraumatic and degenerative arthritis.     

Mechanical stimulation initiates intercellular Ca2+ signaling in intact tracheal epithelium maintained under normal gravity and simulated microgravity

We investigated mechanically induced cell-to-cell Ca2+ signaling in a preparation of rabbit tracheal epithelium close to its in vivo condition. We used confocal microscopy to analyze changes in intracellular free calcium concentration ([Ca2+]i) in intact ciliated tracheal mucosal explants loaded with the Ca2+-indicator dye, fluo-3. When a single cell in the epithelium was transiently stimulated with a microprobe, [Ca2+]i increased in the stimulated cell and then increased in surrounding cells. In the absence of extracellular Ca2+, the [Ca2+]i increases had a smaller amplitude and spread to fewer cells. Treatment of the cells with thapsigargin, in the presence of extracellular Ca2+, more markedly reduced the spread of elevated [Ca2+]i. These results suggest that the propagated [Ca2+]i increases are due to mobilization of Ca2+ from intracellular stores and, possibly, the influx of extracellular Ca2+. The mechanically stimulated [Ca2+]i increases were accompanied by propagated increases in ciliary beat frequency. Since microgravity has been shown to alter signal transduction, we investigated whether simulated microgravity affects the mechanically stimulated cell-to-cell Ca2+ signaling observed in tracheal epithelium. Tissues were maintained for 3-8 d in a rotating wall vessel which simulates microgravity conditions. Cells maintained in simulated microgravity exhibited mechanically induced [Ca2+]i increases not significantly different in magnitude, in speed of propagation, or in the number of cells involved, from tissue maintained at unit gravity. Our results suggest that intercellular Ca2+ signaling coordinates cellular activity, including ciliary beating, within the tracheal epithelium in vivo and that this function is not compromised in microgravity.     

Isobaric vapour-liquid equilibrium for the binary mixtures of 1-bromobutane with isomeric butanols at 40.0 and 101.3 kpa

A dynamic recirculating still was employed to measure isobaric vapour-liquid equilibrium at 40.0 and 101.3 kPa for the binary systems 1-bromobutane and each of the isomers of butanol. All mixtures show azeotropes at both pressures. The experimental VLE data are thermodynamically consistent and were correlated using Margules, Van Laar, Wilson, NRTL and UNIQUAC equations.     

Rationale for using invasive thermometry for regional hyperthermia of pelvic tumors

PURPOSE: Invasive thermometry for regional hyperthermia is time-consuming, uncomfortable, and risky for the patient. We tried to estimate the benefit/cost ratio of invasive thermometry in regional hyperthermia using the radiofrequency system BSD-2000. METHODS AND MATERIALS: We evaluated 182 patients with locally advanced pelvic tumors that underwent regional hyperthermia. In every patient a tumor-related temperature measurement point was obtained either by invasive or minimally invasive catheter measurement tracks. In the earlier period for every patient an intratumoral measurement point was decided as obligatory and intratumoral catheters were implanted intraoperatively, CT guided, or under fluoroscopy. In the later period, invasive thermometry often was avoided, if a measurement point in or near the tumor was reached by an endoluminally inserted catheter (rectal, vaginal, cervical, urethral, or vesical). For every patient side effects and complications referred to thermometry were evaluated and compared with the potential benefit of the invasively achieved temperature data. The suitability of endolumimally registered temperatures is analyzed to estimate local feasibility (specific absorption rate achieved) and local effectiveness (thermal parameters correlated with response). RESULTS: In 74 of 182 patients invasive thermometry was performed, at most CT-guided for soft tissue sarcomas and rectal recurrences. In 14 of 74 (19%) side effects such as local inflammation, pain, or abscess formation occurred that enforced removal of the catheter. However, local problems were strongly correlated with the dwell time of the catheter and nearly never occurred for dwell times less than 5 days. Fortunately, no fatal complications (e.g., bleeding or perforation) occurred during or after implantation which could be attributed to the invasive thermometry procedure. Endoluminal tumor-related temperature rises per time unit (to estimate power density) were correlated with intratumoral rises at the same patients (where both measurements were available). For a subgroup of patients pooled in two Phase II studies with rectal (n = 37) and cervical (n = 18) carcinomas thermal parameters derived from endoluminal measurements were correlated with response or local control, resp. CONCLUSIONS: If a tumor-related endoluminal temperature measurement point is available, additional invasive thermometry gives no further information to improve the power deposition pattern. For primary rectal and cervical cancer, and probably as well for prostate, bladder and anal cancer, endoluminal measurements are suitable to estimate local feasibility and effectiveness. Therefore, invasive thermometry is dispensable in the majority of patients. In some selected cases, temperature measurement in the tumor center is required to estimate the maximum temperature. In those cases, dwell time of catheters should be minimized--and it should be considered to perform invasive thermometry at the beginning (one or two heat treatments).     

Test and evaluation of a solar powered gas turbine system

This paper describes the test and the results of a first prototype solar powered gas turbine system, installed during 2002 in the CESA-1 tower facility at Plataforma Solar de Almería (PSA) in Spain. The main goals of the project were to develop a solar receiver cluster able to provide pressurized air of 1000 °C and solve the problems arising from the coupling of the receivers with a conventional gas turbine to demonstrate the operability of the system. The test set-up consists of the heliostat field of the CESA-1 facility providing the concentrated solar power, a pressurized solar receiver cluster of three modules of 400 kWth each which convert the solar power into heat, and a modified helicopter engine (OST3) with a generator coupled to the grid. The first test phase at PSA started in December 2002 with the goal to reach a temperature level of 800 °C at the combustor air inlet by the integration of solar energy. This objective was achieved by the end of this test phase in March 2003, and the system could be operated at 230 kWe power to grid without major problems. In the second test phase from June 2003 to August 2003 the temperature level was increased to almost 1000 °C. The paper describes the system configuration, the component efficiencies and the operation experiences of the first 100 h of solar operation of this very successful first test of a solar operated Brayton gas turbine system.