Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Durability

  • good durability
  • high durability
  • long-term durability

  • Selected Abstracts


    ARCHAEOMETRY, Issue 4 2010
    In their literary texts, some classical Roman authors such as Gaius Plinius Secundus and Marcus Vitruvius Pollio stress the importance of milling when preparing mortars. Following these indications, this work describes the effects of milling between lime (calcium hydroxide) and clay brick powder before and after the addition of water. Starting and resulting materials were investigated by XRPD, SEM/EDS, differential scanning calorimetry and thermogravimetry (DSC/TC), colorimetry, densimetry and porosimetry. Prolonged milling changes the mineralogy of the starting materials and increases their reactivity. The final lime pastes, starting from materials milled for varying periods of time, had different mineralogical and physical characteristics. These results may help to clarify the reasons for the marked differences in durability of some historical mortars. [source]

    Experimental Analysis on Performance and Durability of SOFC Demonstration Unit

    FUEL CELLS, Issue 3 2010
    M. Halinen
    Abstract A technical description and experimental analysis of a SOFC demonstration unit is presented. The unit contains most of the primary BoP-components of a complete SOFC system, except of air and fuel recirculation equipment or fuel system compressor. Natural gas is used as the fuel and electricity is supplied to the electric grid. A 5,kW power class planar SOFC stack from Research Centre Jülich is assembled to the demo unit and a long-term experiment is conducted to assess the characteristic performance and durability of different components of the unit (e.g. the SOFC stack, the fuel pre-reformer and air heat exchangers). The evolution of absolute voltage drop of the stack over time is found to be of the same magnitude when compared to short stack experiments. Thus, other system components are not observed to cause an increase in the characteristic voltage drop of the stack. Two BoP-components, the afterburner and the power conversion unit failed to operate as designed. The performance of other BoP-components i.e. fuel pre-reformer and heat exchangers were satisfactory during the test run, and no significant performance loss could be measured. [source]

    Review: Durability and Degradation Issues of PEM Fuel Cell Components

    FUEL CELLS, Issue 1 2008
    F. A. de Bruijn
    Abstract Besides cost reduction, durability is the most important issue to be solved before commercialisation of PEM Fuel Cells can be successful. For a fuel cell operating under constant load conditions, at a relative humidity close to 100% and at a temperature of maximum 75,°C, using optimal stack and flow design, the voltage degradation can be as low as 1,2,,V·h. However, the degradation rates can increase by orders of magnitude when conditions include some of the following, i.e. load cycling, start,stop cycles, low humidification or humidification cycling, temperatures of 90,°C or higher and fuel starvation. This review paper aims at assessing the degradation mechanisms of membranes, electrodes, bipolar plates and seals. By collecting long-term experiments as well, the relative importance of these degradation mechanisms and the operating conditions become apparent. [source]

    Radiation Grafted Membranes for Polymer Electrolyte Fuel Cells,

    FUEL CELLS, Issue 3 2005
    L. Gubler
    Abstract The cost of polymer electrolyte fuel cell (PEFC) components is crucial to the commercial viability of the technology. Proton exchange membranes fabricated via the method of radiation grafting offer a cost-competitive option, because starting materials are inexpensive commodity products and the preparation procedure is based on established industrial processes. Radiation grafted membranes have been used with commercial success in membrane separation technology. This review focuses on the application of radiation grafted membranes in fuel cells, in particular the identification of fuel cell relevant membrane properties, aspects of membrane electrode assembly (MEA) fabrication, electrochemical performance and durability obtained in cell or stack tests, and investigation of failure modes and post mortem analysis. The application in hydrogen and methanol fuelled cells is treated separately. Optimized styrene,/,crosslinker grafted and sulfonated membranes show performance comparable to perfluorinated membranes. Some properties, such as methanol permeability, can be tailored to be superior. Durability of several thousand hours at practical operating conditions has been demonstrated. Alternative styrene derived monomers with higher chemical stability offer the prospect of enhanced durability or higher operating temperature. [source]

    Hierarchical Porous, Self-Supporting La- and F-Codoped TiO2 with High Durability for Continuous-Flow Visible Light Photocatalysis

    Guangxiu Cao
    Hierarchical porous, self-supporting La- and F-codoped TiO2 with high durability was prepared using a simple polymer template gel. The TiO2 foams were in the anatase phase, with a specific surface area of up to 88 m2/g, and showed a network-like structure containing meso-/macropores. The macropores had a diameter of ca. 300 nm and a wall thickness of 100,300 nm, while the mesopores were narrowly distributed with a mean diameter of around 5.4 nm. The UV-vis diffuse reflection spectra of the sample showed that the presence of intraband gap states was likely responsible for its absorption of visible light. X-ray photoelectron spectroscopy revealed that La2O3 and O,Ti,F bonds were formed. The sample showed an excellent visible light photocatalytic activity and a high durability of photocatalytic activity for the degradation of methylene blue solution. [source]

    Thermochemistry and Aqueous Durability of Ternary Glass Forming Ba-Titanosilicates: Fresnoite (Ba2TiSi2O8) and Ba-Titanite (BaTiSiO5)

    Tae-Jin Park
    Barium titanosilicates are possible oxide forms for the immobilization of short-lived fission products in radioactive waste. Ba2TiSi2O8 (fresnoite) and BaTiSiO5 (Ba-titanite) samples were prepared by a solid-state synthesis. The enthalpies of formation of Ba2TiSi2O8 crystal and glass at 25°C and of BaTiSiO5 glass were obtained from drop solution calorimetry in a molten lead borate (2PbO,B2O3) solvent at 701°C. The enthalpy of formation for fresnoite composition samples from constituent oxides was exothermic and became more exothermic with increasing crystallinity. Differential scanning calorimetry revealed that the crystallization rate of the fresnoite glasses increased with increasing devitrification. A modified Product Consistency Test-Procedure B (PCT-B) was used to collect solubility data on the fresnoite and titanate phases. The tests suggest that both glassy and crystalline fresnoite exhibit favorable aqueous stability and should be explored further as radioactive waste forms for long-term storage. [source]

    Multilayer Diffusion Barrier Coatings on Poly(propylene) with Improved Temperature Durability

    Lutz Körner
    Abstract The improvement of temperature durability for autoclaving of silicon oxide (SiOx) diffusion barrier coatings on poly(propylene) (PP) by deposition of thin amorphous hydrogenated carbon-nitrogen (a-C:N:H) intermediate layers was investigated. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy revealed terminating amino and nitrile groups responsible for low compressive stress in a-C:N:H. Uniaxial tensile tests showed a higher crack onset strain (COS) for a-C:N:H of 2.7% compared to 0.7% for SiOx. Best temperature durability was achieved by a three-layer coating from a-C:N:H, an intermediate layer deposited by a mixture of N2, C2H2, hexamethyldisiloxane (HMDSO), and a SiOx layer. The oxygen transmission rate (OTR) was only increased from 6 to 22 cm3·m,2·d,1·bar,1 after exposure to 140,°C for 30 min, whereas for single SiOx barrier coatings, severe loss of barrier properties of 1,040 cm3·m,2·d,1·bar,1 was evidenced due to the formation of cracks. [source]

    Poor Performance of Corals Transplanted onto Substrates of Short Durability

    Sebastian C.A. Ferse
    Worldwide, coral reefs are degrading due to increasing anthropogenic pressures. Yet, management of reefs still falls short of effectively addressing these threats, and active restoration methods are increasingly being called for. Coral transplantation is frequently advocated as a possible means of coral reef rehabilitation. Fragments produced in coral nurseries or farms have been proposed as a potential source for transplantation, and culture media (inexpensive but non-durable materials such as wood or bamboo) may serve as transplantation substrate if placed directly in the reef. However, the performance of coral transplants attached to such substrates has not been examined yet. Here, the long-term survival of transplants attached to bamboo substrates is reported. A total of 6,164 fragments of 4 coral species (Acroporids and Pocilloporids) were monitored for up to 20 months at three sites in North Sulawesi/Indonesia. Bamboo failed as a suitable inexpensive substrate in at least two of the three sites examined. Mortality of transplants 2 years after transplantation was high in three of the four species (67,95%) and was partially linked to substrate disintegration. The results show that, in places were currents or waves threaten to dislocate transplants, a higher effort needs to be directed at a strong and durable attachment of transplanted corals. [source]

    Information, Agreement Design, and the Durability of Civil War Settlements

    Michaela Mattes
    Civil war is usually examined from the perspective of commitment problems. This approach provides considerable insight regarding which civil war agreement provisions reduce the chance of renewed fighting. Yet, additional insight can be gained by examining information asymmetries as a potential cause of civil war recurrence. We argue that significant uncertainty regarding military capabilities may persist after fighting ends and that this uncertainty may lead to the breakdown of peace. However, carefully designed peace agreements can guard against renewed civil war by calling for international monitoring, making the belligerents submit military information to third parties, and providing for verification of this information. Our empirical analysis of 51 civil war settlements between 1945 and 2005 shows that these provisions significantly reduce the risk of new civil war. Encouraging the adoption of these provisions may be a useful policy in the international community's effort to establish peace in civil-war-torn societies. [source]

    Auswirkungen der Matrixzusammensetzung auf die Dauerhaftigkeit von Betonen mit textilen Bewehrungen aus AR-Glas

    Marko Butler Dipl.-Ing.
    Baustoffe; Bewehrung; Versuche Abstract Verbundmaterialien aus Feinbetonen mit textiler Bewehrung aus alkaliresistentem Glas (AR-Glas) können ausgeprägten zeitabhängigen Veränderungen hinsichtlich des mechanischen Leistungsvermögens unterliegen. Für eine zielsichere Anwendung solcher Werkstoffe im Bauwesen sind genaue Kenntnisse über die Höhe und die Ursachen dieser Leistungsverluste unabdingbar. In diesem Artikel werden anhand von Ergebnissen aktueller Untersuchungen entscheidende Mechanismen für die Alterungsprozesse dargestellt, die aus der Zusammensetzung der Feinbetone resultieren. Dazu wurden aus verschiedenen Betonzusammensetzungen, die sich maßgeblich in ihrer Hydratationskinetik und Alkalität unterschieden, textilbewehrte Dehnkörper hergestellt und nach beschleunigter Alterung geprüft. Dehnkörper aus Feinbeton mit hoher Alkalität (das Bindemittel bestand nur aus CEM I) zeigten dramatische Einbußen bei Zugfestigkeit und Bruchdehnung. Das Leistungsvermögen von Proben aus Feinbetonen mit puzzolanisch abgepufferter Bindemittelzusammensetzung und gleichzeitig reduziertem Portlandzementklinkeranteil zeigte sich dagegen weitgehend unbeeinflusst von Alterungsprozessen. Mit Hilfe von beidseitigen Garnauszugversuchen an beschleunigt gealterten Feinbetonproben wurden die für das unterschiedliche Materialverhalten verantwortlichen Degradationsmechanismen aufgeklärt. Neben der mechanischen Prüfung wurde dazu auch die Interphase zwischen Fasern und umgebendem Feinbeton mit bildgebenden und analytischen Verfahren charakterisiert. Die festgestellten Einbußen im Leistungsvermögen des Garn-Matrix-Verbundes konnten überwiegend auf die Neubildung von ungünstig strukturierten Hydratationsprodukten in der Interphase Filament-Matrix bzw. in Filamentzwischenräumen zurückgeführt werden. Die Morphologie dieser Phase wird maßgeblich von der Bindemittelzusammensetzung bestimmt. Korrosion des AR-Glases als Schadensursache kann unter ungünstigen Umständen auch eine große Rolle spielen, ist aber bei geeigneter Matrixformulierung von untergeordneter Bedeutung. Effect of Matrix Composition on the Durability of Concretes Reinforced with Glass Fibre Fabric The mechanical performance of composites made of finegrained concrete and textile reinforcement can worsen markedly with increasing age if alkali-resistant glass (AR-glass) is used as the reinforcing material. For reliable practical applications of textile-reinforced concrete, precise knowledge as to the extent and causes of such degradation is indispensable. This paper discusses important aging mechanisms resulting from the composition of fine-grained concrete. Tensile tests on composites made of different concrete compositions distinguished from one another by their hydration kinetics and alkalinity were performed before and after accelerated aging. Composites made of concrete with high alkalinity showed dramatic losses of tensile strength and strain capacity. In contrast the mechanical performance of composites whose binders had reduced Portland cement clinker content plus added puzzolana was hardly affected by the accelerated aging. To clarify the mechanisms of degradation, yarn pullout tests were performed on specimens of equal matrix composition and age. Additionally, the morphology of the interphase between matrix and fibre was characterised using direct microscopic examination and analytical methods. The new formation of unfavourably structured products of hydration in the filament-matrix interphase and/or in the empty spaces between filaments was found to be the main reason for the performance losses observed. The morphology of these hydration products is determined to a great extent by the binder composition. Under unfavourable conditions corrosion of AR-glass can occur as well and lead to distinct composite damage. However, if the formulation of the binder is proper, bulk glass corrosion is of minor importance. [source]

    Überwachung und Analyse der Lebensdauer von Tunnelbauwerken

    Konrad Bergmeister Prof. Dipl.-Ing.
    Im Tunnelbau bildet die Überwachung der signifikanten Einwirkungs- und Strukturparameter während der Bauphase und des Betriebs die Basis für die Bewertung des Zustands und der Sicherheit des Bauwerks. Die erfassten Daten stellen des Weiteren die Grundlage zur nummerischen und mechanischen Modellbildung dar, um eine effiziente Entscheidungsfindung und Maßnahmenplanung zu gewährleisten. Die Überwachung beinhaltet die Erfassung und Bewertung der geologischen Gegebenheiten, der induzierten Auswirkungen während des Vortriebs und die kontinuierliche Kontrolle für den weiteren Betrieb und Unterhalt des Bauwerks. Methoden der Bauwerksüberwachung und Diagnose stellen aufgrund der quantitativ erfassten Systemparameter ein wesentliches Element für die Zuverlässigkeitsanalyse dar. Die geeignete Wahl von Kontroll- und Messinstrumenten ist jedoch nur einen Teilaspekt der Bauwerksüberwachung. Die Auswertung und Interpretation der erhobenen Daten, die Gegenüberstellung mit den normativen Anforderungen und Grenzwerten, die Anpassung der analytischen Modellannahmen aufgrund des Vergleichs von gemessenen und berechneten Daten zeigen die Komplexität dieses Aufgabengebietes. Monitoring and Analysis of Durability of Tunnels Monitoring continuously the decisive parameters, during both the construction and the operation phase, provides the quantitative basis for safety and condition assessment, analytical modelling and decision making. This includes evaluating the conditions and induced effects during excavation and construction, and continues during operation in terms of maintenance decision making and reliability assessment. The utilisation of monitoring devices and measurement elements is however only the start of monitoring field performance. Interpretation of the acquired data is equally important, namely the validation of compliance with normative specifications and the comparison of measured and calculated data in order to evaluate analytical model assumptions. [source]

    Chemical alteration of tephra in the depositional environment: theoretical stability modelling

    A. M. Pollard
    Abstract The study of the chemical stability of vitreous material in aqueous media is well-established. There has to date been little consideration of the implications of variations in the chemical durability of tephra in Quaternary tephrochronology. Chemical alteration can take the form of cationic leaching from the matrix, or complete destruction of the silica network, either of which could constrain the ability to chemically identify distal tephra. Here we apply established models of vitreous durability to the published chemical analyses of a large number of Icelandic tephras in order to predict their relative durabilities under equivalent conditions. This suggests that some important tephras have relatively poor chemical stability, and that rhyolitic tephras are, in general, more stable than basaltic. We conclude that tephras should be expected to show predictable differential chemical stability in the post-depositional environment. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    The sural artery patency test: A useful precaution in risky patients for the reverse sural flap

    MICROSURGERY, Issue 3 2008
    Onder Tan M.D.
    The arterial insufficiency is not rare in high risky patients for the reverse sural flap. Thus, we introduce a novel practical technique by performing intraoperative patency test to the sural artery to predetermine the arterial potential, to avoid a possible arterial insufficiency and to increase the reliability of the sural flap in these patients. We succesfully applied the reverse sural flap to seven risky patients with crushing injury, mine explosion, and diabetes, in whom the sural artery patency test was positive. The flap size varied from 8 × 5 cm to 16 × 10 cm. The major defect localization was the heel with/without sole. All flaps survived uneventfully with good contours and durabilities. The sural artery patency test obtain us to decide to safely raise the sural flap or not, and to predict the outcomes of the operative procedure in critical wounds associated with poor arterial supply. © 2008 Wiley-Liss, Inc. Microsurgery, 2008. [source]

    Selective Application of the Pediatric Ross Procedure Minimizes Autograft Failure

    David L.S. Morales MD
    ABSTRACT Objective., Pulmonary autograft aortic root replacement (Ross' operation) is now associated with low operative risk. Recent series suggest that patients with primary aortic insufficiency have diminished autograft durability and that patients with large discrepancies between pulmonary and aortic valve sizes have a low but consistent rate of mortality. Therefore, Ross' operation in these patients has been avoided when possible at Texas Children's Hospital. Our objective was to report outcomes of Ross' operation when selectively employed in pediatric patients with aortic valve disease. Methods., Between July 1996 and February 2006, 55 patients (mean age 6.8 ± 5.5 years) underwent Ross' procedure. Forty-seven patients (85%) had a primary diagnosis of aortic stenosis, three (5%) patients had congenital aortic insufficiency, and five (9%) patients had endocarditis. Forty-two (76%) patients had undergone prior aortic valve intervention (23 [55%] percutaneous balloon aortic valvotomies, 12 [29%] surgical aortic valvotomies, 12 [29%] aortic valve replacements, 2 [5%] aortic valve repairs). Fourteen (25%) patients had ,2 prior aortic valve interventions. Thirty-two patients (58%) had bicuspid aortic valves. Follow-up was 100% at a mean of 3 ± 2.5 years. Results., Hospital and 5-year survival were 100% and 98%, respectively. Morbidity included one reoperation (2%) for bleeding. Median length of hospital stay was 6 days (3 days,3 months). Six (11%) patients needed a right ventricular to pulmonary artery conduit exchange at a median time of 2.3 years. Freedom from moderate or severe neoaortic insufficiency at 6 years is 97%. Autograft reoperation rate secondary to aortic insufficiency or root dilation was 0%. Conclusions., By selectively employing Ross' procedure, outcomes of the Ross procedure in the pediatric population are associated with minimal autograft failure and mortality at mid-term follow-up. [source]

    Outcome of Pulmonary Valve Replacements in Adults after Tetralogy Repair: A Multi-institutional Study

    Thomas P. Graham Jr. MD
    ABSTRACT Objective., The purpose of this study was to assess the outcome of pulmonary valve replacement (PVR) in adults with moderate/severe pulmonary regurgitation after tetralogy repair, with particular emphasis on patient outcome, durability of valve repair, and improvement in symptomatology. Design/Setting/Patients., The project committee of the International Society of Congenital Heart Disease undertook a retrospective multi-institutional analysis of PVR. Seven centers participated in submitting data on 93 patients >18 years of age who had the operation performed and follow-up obtained. The average age of PVR was 26± years (median 27 years). Time of follow-up after replacement was 3 years (range 4 days,28 years). Outcomes/Measures/Results., Kaplan,Meier estimates of durability of PVR showed approximately 50% replacement at 11 years. There were two deaths at 6 and 12 months after valve replacement. Right ventricular (RV) size estimated by echocardiography from pre- to postoperative studies decreased in 81% (P < 0.001 testing for equal proportions), but RV systolic function increased in only 36% (P = 0.09). Ability index improved in 59% (P < 0.001) and clinical heart failure status improved in 57% with this problem before PVR. PVR did not improve arrhythmia status in a small group of patients. Conclusions., PVR is associated with low mortality, decrease in RV size and improvement in ability index, and uncertain effects on RV systolic function. Average valve durability was approximately 11 years. Criteria for PVR that will preserve RV function are not clearly identified, and management of these patients remains a difficult enterprise. [source]

    T-cell subset counting and the fight against AIDS: Reflections over a 20-year struggle

    CYTOMETRY, Issue 2 2002
    Francis Mandy
    Abstract The story of T-lymphocyte subset immunophenotyping technology is reviewed on the occasion of the 20th anniversary of CD4 T-cell enumeration. Over time, immunophenotyping has evolved into precise, reliable, but complicated and expensive technology requiring fresh blood samples. The gating technologies that were universally adapted for clinical flow cytometry for the past decade relied on rapidly deteriorating morphological scatter characteristics of leukocytes. This special issue dedicated to CD4 T-cell enumeration features most of the available new options that will have a significant impact on how this technology will be implemented within the first decade of the 21st century. In a series of original publications, including the new NIH guideline for T-cell subset enumeration, contemporary gating protocols that use immunologically logical parameters are presented as part of the more reliable and affordable immunophenotyping alternative. Some of the improvements addressed here include the costs of the assays and the capacity to monitor interlaboratory and intralaboratory performances. It is clear that an effective attack on the human immunodeficiency virus (HIV) epidemic has to embrace resource-poor regions. Reducing the cost of the assay while improving reliability and durability is a move in the right direction. Cytometry (Clin. Cytometry) 50:39,45, 2002. © 2002 Wiley-Liss, Inc. [source]

    A 52-Month Summary of Results Using Calcium Hydroxylapatite for Facial Soft Tissue Augmentation

    OBJECTIVES In this large-scale clinical review, we investigated the safety and efficacy of Radiesse, an injectable calcium hydroxylapatite (CaHA) implant, in treatment of nasolabial folds, marionette lines, and other areas of the face. METHODS After obtaining informed consent from the subjects, CaHA was injected in 1,000 patients (886 women and 114 men, ranging in age from 21 to 85 years) for a variety of facial aesthetic applications over a period of 52 months. Typically, CaHA was administered with a 27-gauge 1/2, or 1 1/4-inch needle. RESULTS The nasolabial folds were the most frequently treated site, followed by the marionette lines/oral commissure. More than 80% of patients reported persistence of results at 12 months. The most frequently reported adverse events were erythema and ecchymosis. The formation of nodules was rare and was chiefly confined to the lips. Only two patients experienced nodule formation outside the lips. CONCLUSIONS Over a period of more than 4 years, we found that CaHA performed well, with a favorable safety profile, high patient satisfaction, and good durability. [source]

    A Multicenter, 47-Month Study of Safety and Efficacy of Calcium Hydroxylapatite for Soft Tissue Augmentation of Nasolabial Folds and Other Areas of the Face

    OBJECTIVES Each soft tissue filler product has its own unique profile in terms of adverse events. In this large-scale study, we investigated the safety profile of Radiesse, an injectable calcium hydroxylapatite (CaHA) implant, in treatment of nasolabial folds and other areas of the face. We also investigated the efficacy in a subset of the larger patient group. METHODS After obtaining informed consent from the subjects, researchers injected CaHA at two treatment centers into 113 patients (100 women and 13 men, ranging in age from 26 to 78 years) for a variety of facial aesthetic applications over a period of 47 months. Seventy-five patients had a single injection session; 38 had multiple sessions. Most patients (102) received 1.0 mL of CaHA per session; 12 received 2.0 mL per session. Typically, CaHA was administered with a 27-gauge 0.5- or 1 1/4-in. needle. RESULTS Safety. Of 113 patients, only 7 reported minor adverse events that were short-term and resolved within 1 month: transient ecchymosis (3), nongranulatomous submucosal nodules of the lip (2), and inflammation and edema (2). Efficacy. Efficacy ratings were performed for a subset of patients (n=41). On a scale of 1 to 5 (1=unsatisfactory; 5=excellent), the mean patient evaluation score for look and feel of the implant was 4.6; the mean physician scores for the look and feel of the implant were 4.5 and 4.6, respectively. During the 6-month follow-up visit, patients' mean ratings of the look and feel of the implant were 4.8 and 4.9, respectively. The physician's mean ratings for the look and feel of the implant were 4.5 and 4.9, respectively. CONCLUSIONS In our study, CaHA performed well, with a favorable safety profile, high patient satisfaction (90% of patients reported very good or excellent results), and good durability. We are especially pleased with the low incidence of adverse events coupled with the favorable responses from the patients themselves due to longevity of correction. [source]

    Imiquimod Treatment of Superficial and Nodular Basal Cell Carcinoma: 12-Week Open-Label Trial

    Ketty Peris MD
    Background Imiquimod is an immune response modifier shown to be effective in basal cell carcinoma (BCC). Objective To evaluate the efficacy, tolerability, and response durability of imiquimod 5% cream in selected patients with superficial and/or nodular BCCs. Methods Seventy-five superficial and 19 nodular BCCs in 49 patients were treated with imiquimod once daily three times a week for up to 12 weeks. Results Of the 49 enrolled patients, 1 discontinued the study and 1 was lost to follow-up. After 12 weeks of treatment, a complete response occurred in 70 of 75 (93.3%) superficial BCCs and a partial response in 4 of 75 (5.3%) superficial BCCs. Ten of 19 (52.6%) nodular BCCs cleared after 12 weeks, whereas 7 (36.8%) showed partial remission. Adverse side effects were limited to local skin reactions. Recurrence was observed in 2 of 70 (2.9%) successfully treated superficial BCCs 6 and 8 months after treatment discontinuation. No recurrence was detected in 68 of 70 (97.1%) superficial BCCs and in 10 successfully treated nodular BCCs after 12 to 34 months of follow-up (mean 23 months). Conclusions In our patient population, treatment of superficial BCCs with topical imiquimod for 12 weeks produced an excellent clinical response overall, with complete remission maintained after a mean of 23 months. KETTY PERIS, MD, ELENA CAMPIONE, MD, TAMARA MICANTONIO, MD, GEORGIANA CLARE MARULLI, MD, MARIA CONCETTA FARGNOLI, MD, AND SERGIO CHIMENTI, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source]

    GLP-1: physiological effects and potential therapeutic applications

    Kasper Aaboe
    Glucagon-like peptide 1 (GLP-1) is a gut-derived incretin hormone with the potential to change diabetes. The physiological effects of GLP-1 are multiple, and many seem to ameliorate the different conditions defining the diverse physiopathology seen in type 2 diabetes. In animal studies, GLP-1 stimulates ,-cell proliferation and neogenesis and inhibits ,-cell apoptosis. In humans, GLP-1 stimulates insulin secretion and inhibits glucagon and gastrointestinal secretions and motility. It enhances satiety and reduces food intake and has beneficial effects on cardiovascular function and endothelial dysfunction. Enhancing incretin action for therapeutic use includes GLP-1 receptor agonists resistant to degradation (incretin mimetics) and dipeptidyl peptidase (DPP)-4 inhibitors. In clinical trials with type 2 diabetic patients on various oral antidiabetic regimes, both treatment modalities efficaciously improve glycaemic control and ,-cell function. Whereas the incretin mimetics induce weight loss, the DPP-4 inhibitors are considered weight neutral. In type 1 diabetes, treatment with GLP-1 shows promising effects. However, several areas need clinical confirmation: the durability of the weight loss, the ability to preserve functional ,-cell mass and the applicability in other than type 2 diabetes. As such, long-term studies and studies with cardiovascular end-points are needed to confirm the true benefits of these new classes of antidiabetic drugs in the treatment of diabetes mellitus. [source]

    Cognitive behaviour therapy with coping training for persistent auditory hallucinations in schizophrenia: a naturalistic follow-up study of the durability of effects

    D. Wiersma
    Objective: To investigate the durability of positive effects of cognitive behaviour therapy (CBT) with coping training on psychotic symptoms and social functioning. Method: Forty patients with schizophrenia or related psychotic disorders and refractory auditory hallucinations were given CBT and coping training in an integrated single family treatment programme. In a naturalistic study patients were followed after 2 and 4 years since the start of treatment. Results: The treatment improved overall burden of ,hearing voices', with a generalization into daily functioning. Improvement with regard to fear, loss of control, disturbance of thought and interference with thinking was sustained by 60% of the patients while one-third improved further. Complete disappearance of hallucinations occurred in 18% of the patients. Conclusion: CBT with coping training can improve both overall symptomatology and quality of life, even over longer periods of time, but a status of persistent disablement indicates a continuing need for mental health care. [source]

    Patterns of damage in igneous and sedimentary rocks under conditions simulating sea-salt weathering

    C. Cardell
    Abstract A saline-spray artificial ageing test was used to simulate the effects produced in granites and sedimentary rocks (calcarenites, micrites and breccia) under conditions in coastal environments. Three main points were addressed in this study: the durability of the different kinds of rock to salt decay, the resulting weathering forms and the rock properties involved in the weathering processes. For this, mineralogical and textural characterization of each of the different rocks was carried out before and after the test. The soluble salt content at different depths from the exposed surfaces was also determined. Two different weathering mechanisms were observed in the granite and calcareous rocks. Physical processes were involved in the weathering of granite samples, whereas dissolution of calcite was also involved in the deterioration of the calcareous rocks. We also showed that microstructural characteristics (e.g. pore size distribution), play a key role in salt damage, because of their influence on saline solution transport and on the pressures developed within rocks during crystallization. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Pore properties as indicators of breakdown mechanisms in experimentally weathered limestones

    Dawn T. Nicholson
    Abstract The results are reported of four experimental weathering tests , freeze , thaw, wetting and drying, slake durability and salt weathering , on five different types of limestone. Effective porosity, mercury intrusion porosimetry and scanning electron microscopy were used to evaluate changes in pore properties, while weight loss and fracture density were used to assess deterioration severity. A primary aim was to observe modifications in porosity due to weathering and to draw inferences about the internal rock deterioration mechanisms taking place. It is concluded that the five limestones not only show a wide range of resistance to weathering in general but considerable difference in resistance to particular weathering processes. Consequently, when assessing durability it is essential to consider rock properties in the context of the weathering process to which the rock is subject. The type of deterioration indicator used is also important in interpretation of durability. A variety of pore modification mechanisms operate, including changes in pore connectivity, pore infilling, and the introduction of additional void space. There are indications that changes to the internal pore structure of rocks due to weathering may be a precursor to more substantial macrodeterioration. Copyright © 2001 John Wiley & Sons, Ltd. [source]

    Developmental and Quiescent Subsidiaries in the Asia Pacific: Evidence from Hong Kong, Singapore, Shanghai, and Sydney

    ECONOMIC GEOGRAPHY, Issue 2 2003
    Jessie P. H. Poon
    Abstract: Examining "embedded" economic and social relations has become a popular theme among economic geographers who are interested in explaining the durability of place in supporting economic activities. This article explores the relationship between embeddedness and technology-oriented functions among three types of subsidiaries (regional headquarters, regional offices, and local offices) and for four cities: Hong Kong, Shanghai, Singapore, and Sydney. Using survey data from firms, we show that quiescent or branch plant-like subsidiaries, rather than developmental firms, dominate the region. But among developmental subsidiaries, returns on embeddedness are not always obvious. Embeddedness and developmental subsidiaries are most significantly correlated with manufacturing regional headquarters. However, a small group of subsidiaries (local and regional offices) also perform developmental functions, despite their relative newness and lack of embed-dedness in the region. [source]

    Capillary electrophoretic separation of biologically active amines and acids using nanoparticle-coated capillaries

    ELECTROPHORESIS, Issue 9 2008
    Yu-Fen Huang
    Abstract This manuscript describes dynamic coating of capillaries with poly(L -lysine) (PLL) and silica nanoparticles (SiO2 NPs) and use of the as-prepared capillaries for the separation of biogenic amines and acids by CE in conjunction with LIF detection. The directions of EOF are controlled by varying the outmost layer of the capillaries with PLL and SiO2 NPs, respectively. Over the pH range 3.0,5.0, the (PLL,SiO2NP)n,PLL capillaries have an EOF toward the anodic end and are more suitable for the separation of acids with respect to speed, while the (PLL,SiO2NP)n capillaries have an EOF toward the cathodic end and are more suitable for the separation of biogenic amines regarding speed and sensitivity. The separations of standard solutions containing five amines and two acids by CE with LIF detection using (PLL,SiO2NP)2,PLL and (PLL,SiO2NP)3 capillaries were accomplished within 10 and 7,min, providing plate numbers of 3.8 and 5.0×104,plates/m for 5-hydroxytryptamine (5-HT), respectively. The LODs for 5-HT and 5-hydroxyindole-3-acetic acid (5-HIAA) are 32 and 2,nM and 0.2 and 1.5,nM when using the (PLL,SiO2NP)2,PLL and (PLL,SiO2NP)3 capillaries, respectively. Identification and quantification of 5-HIAA, homovanillic acid, and DL -vanillomandelic acid in urine samples from a male before and after drinking green tea were tested to validate practicality of the present approach. The results show that the (PLL,SiO2NP)2,PLL capillary provides greater resolving power, while the (PLL,SiO2NP)3 capillary provides better sensitivity, higher efficiency, and longer durability for the separation of the amines and acids. [source]

    Direct electrochemical detection of glucose in human plasma on capillary electrophoresis microchips

    ELECTROPHORESIS, Issue 21-22 2004
    Yan Du
    Abstract We developed an electrochemical detector on a hybrid chip for the determination of glucose in human plasma. The microchip system described in this paper consists of a poly(dimethylsiloxane) (PDMS) layer containing separation and injection channels and an electrode plate. The copper microelectrode is fabricated by selective electroless deposition. The fabrication of the decoupler is performed by platinum electrochemical deposition on the metal film formed by electroless deposition. Factors influencing the performance, including detection potential, separation field strength, and buffer concentration, were studied. The electrodes exhibited good stability and durability in the analytical procedures. Under optimized detection conditions, glucose responded linearly from 10 ,M to 1 mM. Finally, glucose in human plasma from three healthy individuals and two diabetics was successfully determined, giving a good prospect for a new clinical diagnostic instrument. [source]

    Fixation of heavy contaminants of a dirty bomb attack: Studies with uranium and metal simulants

    Thomas L. McGehee
    Abstract Asphalt emulsions were evaluated as a means to immobilize radiological contaminants deposited on urban surfaces after a dirty bomb attack. Contaminated surfaces would be sprayed with thin coatings of asphalt emulsion to encapsulate the radioactive particles until the site can be safely remediated. This research investigated applications of an asphalt emulsion (Topein C, Encapco Technologies, LLC, Napa, CA) to treat (zero-valent) iron, lead, and uranium powders on various building material surfaces. Initial studies found that some of the building materials (limestone, concrete, and metal) reacted with the emulsion producing gas bubbles, which formed 0.001 to 1 cm vesicles in the cured asphalt emulsion. These vesicles, however, did not expose the building material surface, and the reaction appeared to aid in the setting of the emulsion. Powdered lead did not react with the asphalt emulsion, but iron powder and uranium did. Iron powder and the emulsion formed vesicles up to 0.5 mm (but not exposing the building material surface), while the uranium (U3O8) had a moderate reaction when compared with to the lead and iron powders. Scanning electron micrographs showed that the lead powder formed nonreactive layers adjacent to the concrete surface while iron particles were evenly distributed in the asphalt matrix due to the reaction with the asphalt, indicating that the physical and chemical reactions between the iron metal particles, asphalt, and concrete affected particle distribution in the asphalt matrix. A vertical operation sediment tube was used to determine the flowing shear stress durability of the asphalt/metal/substrate complex. The asphalt treatment with iron had no loss at the shear range tested (0.1,2.5 Pa), while the asphalt stabilized powdered lead lost 8% asphalt and lead at 2.5 Pa mean shear stress applied for 5 h. The chemical reaction between asphalt emulsion and iron increased the resistance of the asphalt/metal/substrate complex to shear when compared with lead. Some hydrogen was formed in reactions with iron, but the amount formed was well below the lower flammability limit. Treatment of uranium indicated that the emulsion was effective at reducing leaching of the uranium 10 fold. These experiments indicate that asphalt emulsions may be a viable means for containing metallic or dense radiological contaminants on common building materials. © 2007 American Institute of Chemical Engineers Environ Prog 26:94,103, 2007 [source]

    Influence of contamination on resin bond strength to nano-structured alumina-coated zirconia ceramic

    Shanchuan Zhang
    Zhang S, Kocjan A, Lehmann F, Kosma, T, Kern M. Influence of contamination on resin bond strength to nano-structured alumina-coated zirconia ceramic. Eur J Oral Sci 2010; 118: 396,403. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci The purpose of this study was to evaluate the influence of contamination and subsequent cleaning on the bond strength and durability of an adhesive resin to nano-structured alumina-coated zirconia ceramic. Zirconia ceramic disks were coated with nano-structured alumina, utilizing the hydrolysis of aluminum nitride powder. After immersion in saliva or the use of a silicone disclosing agent, specimens were cleaned with phosphoric acid etching or with tap water rinsing only. Uncontaminated specimens served as controls. Plexiglas tubes filled with composite resin were bonded with a phosphate monomer [10-methacryloxydecyl-dihydrogenphosphate (MDP)]-containing resin (Panavia 21). Subgroups of eight specimens each were stored in distilled water at 37°C, either for 3 d without thermal cycling (TC) or for 150 d with 37,500 thermal cycles from 5 to 55°C. The tensile bond strength (TBS) was determined using a universal testing machine at a crosshead speed of 2 mm min,1. The topography of the debonded surface was scrutinized for fractographic features, utilizing both optical and scanning electron microscopy. The TBS to uncontaminated nano-structured alumina-coated zirconia ceramic was durable, while contamination significantly reduced the TBS. Phosphoric acid cleaning was effective in removal of saliva contamination from the coated bonding surface but was not effective in removal of the silicone disclosing agent. Nano-structured alumina coating improves resin bonding to zirconia ceramic and eliminates the need for air-abrasion before bonding. [source]

    Ten-years degradation of resin,dentin bonds

    Masanori Hashimoto
    Hashimoto M, Fujita S, Nagano F, Ohno H, Endo K. Ten-years degradation of resin,dentin bonds. Eur J Oral Sci 2010; 118: 404,410. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci The purpose of this study was to evaluate the durability of resin,dentin bonds in 10-yr water-storage testing. Resin,dentin bonded bulk specimens were prepared using six commercially available resin adhesives. The resin,dentin bonded specimens were stored in water for 24 h (control group) or for 10 yr (experimental groups). After each storage period, the specimens were sectioned to make specimen beams and then subjected to a microtensile bond test. After the bond test, fractured surfaces were examined by scanning electron microscopy (SEM). In addition, interfacial observation of silver nanoleakage was performed using the backscatter electron mode of SEM. The bond strengths of four of the six adhesive systems tested decreased significantly after 10 yr. However, no significant bond-strength reduction was recorded for the other two systems. The interfacial observations showed water tree propagation in the bonding resin layer as a typical morphological change after aging for five of the six adhesives tested. Water tree propagation may be a symptom of degradation in the resin bonding layer of resin,dentin bonds. [source]

    Seven-year dentin bond strengths of a total- and self-etch system

    Michael F. Burrow
    The aim of this study was to determine the durability of tensile bond strengths of a conventional 3-step bonding system (Superbond D-liner Plus) and a self-etching priming bonding system (Clearfil Liner Bond II) to bovine dentin over a 7 yr period. Superficial bovine dentin finished with 600-grit SiC paper was bonded with one of the two adhesive materials. A 4 mm diameter area was bonded, covered with resin composite and stored in 37°C deionized water containing gypsum chips and 0.4% sodium azide as an antibacterial. Bonds were stressed in tension at a crosshead speed of 1 mm min,1. Mean bond strengths were observed at 1 d, at 1, 3, and 6 months, and at 1, 2, 3, 6 and 7 yr. Ten specimens were tested for the first 3 yr and 15 specimens were tested for 6 and 7 yr. The bond strength of Superbond D-liner Plus significantly decreased over the 7 yr period, whereas Liner Bond II showed a slight but, insignificant, decrease. The fracture mode changed with time for Superbond D-liner Plus, but not for Liner Bond II. It was concluded that systems which use a strong acid for demineralizing the dentin may show greater deterioration of the bond to dentin compared with a self-etching priming system. [source]