Statistical similarity between the compression of a porous material and earthquakes

It has been long stated that there are profound analogies between fracture experiments and earthquakes; however, few works attempt a complete characterization of the parallelisms between these so separate phenomena. We study the Acoustic Emission events produced during the compression of Vycor (SiO2). The Gutenberg-Richter law, the modified Omori's law, and the law of aftershock productivity are found to hold for a minimum of 5 decades, are independent of the compression rate, and keep stationary for all the duration of the experiments. The waiting-time distribution fulfills a unified scaling law with a power-law exponent close to 2.45 for long times, which is explained in terms of the temporal variations of the activity rate.Comment: 4 pages and a bit more, 4 figure

Simulación de propiedades mecánicas demulticapas de Zr/ZrN y TiN/ZrNempleando el método de elementos finitos

In this work mechanical properties of Zr/ZrN and TiN/ZrN multilayers varying the bilayerd number in 1, 2, 5 and 10, that is, multilayer periods of 2, 1, 0.4 y 0.2 μm, with thickness constant of 2 μm in a ratio 1:1 y 1:3 were studied. For the simulation the ANSYS software was employed, based on the finite elements method. Strain–stress curves, the hardness and Young’s Modulus were obtained as function of the bilayer numbers. According, the analysis carried out, the TiN/ZrN bilayers with 1:3 ratio presented the highest hardness (31±1 GPa) regarding the others and a Young’s modulus approximately of 460 GPa. Results obtained from the mechanical properties simulations of materials |based on Ti and Zr, by using methods like finite elements are promising in the new materials field, in order to predict their performance in industrial and technological applications as hard coatings grown on several tools and machine pieces and from this way reducing the production costs. Moreover, simulations presented in this work can be extended to systems composed by other materials with great utilization.PACS: 47.11.Fg, 73.21.Ac, 87.15.La, 81.40.Lm, 81.70.Bt, 81.70.PgMSC: 76M10En este trabajo se presenta el estudio de propiedades mecánicas de multicapas de Zr/ZrN y TiN/ZrN variando el número de bicapas en 1, 2, 5 y 10, es decir, períodos de 2, 1, 0,4 y 0,2 μm, con espesor constante de 2 μm en una relación de 1:1 y 1:3. Para esta simulación se empleó el software ANSYS, el cual se basa en el método de elementos finitos. Se obtuvieron curvas de Esfuerzo– Deformación, dureza y módulo de Young en función del número de bicapas. De acuerdo al análisis realizado, las bicapas de TiN/ZrN con relación 1:3 presentan mayor dureza (31±1 GPa) en relación a los demás sistemas y un módulo de Young de aproximadamente 460 GPa. Los resultados de las simulaciones de las propiedades mecánicas de materiales basados en Ti y Zr, empleando métodos como el de elementos finitos, son prometedores en el campo de los nuevos materiales para predecir su desempeño en aplicaciones tecnológicas e industriales como recubrimientos duros sobre diferentes herramientas y piezas de maquinaria y así disminuir costos de producción. Además, las simulaciones presentadas en este trabajo pueden extenderse a sistemas compuestos de otros materiales de gran utilidad.PACS: 47.11.Fg, 73.21.Ac, 87.15.La, 81.40.Lm, 81.70.Bt, 81.70.PgMSC: 76M1

Simulación de propiedades mecánicas demulticapas de Zr/ZrN y TiN/ZrNempleando el método de elementos finitos

This paper presents the study of mechanical properties of multilayers of Zr / ZrN and TiN / ZrN by varying the number of bilayers in 1, 2, 5 and 10, that is, periods of 2, 1, 0.4 and 0.2 μm, with a constant thickness of 2 μm in a ratio of 1: 1 and 1: 3. For this simulation, the ANSYS software was used, which is based on the finite element method. Effort curves were obtained - Deformation, hardness and Young's modulus depending on the number of bilayers. According to the analysis performed, the TiN / ZrN bilayers with a 1: 3 ratio have greater hardness (31 ± 1 GPa) in relation to the other systems and a Young's modulus of approximately 460 GPa. The results of the simulations of the mechanical properties of Ti and Zr-based materials, using methods such as finite elements, are promising in the field of new materials to predict their performance in technological and industrial applications such as hard coatings on different tools and pieces of machinery and thus reduce production costs. In addition, the simulations presented in this work can be extended to systems composed of other useful materials.En este trabajo se presenta el estudio de propiedades mecánicas de multicapas de Zr/ZrN y TiN/ZrN variando el número de bicapas en 1, 2, 5 y 10, es decir, períodos de 2, 1, 0,4 y 0,2 μm, con espesor constante de 2 μm en una relación de 1:1 y 1:3. Para esta simulación se empleó el software ANSYS, el cual se basa en el método de elementos finitos. Se obtuvieron curvas de Esfuerzo– Deformación, dureza y módulo de Young en función del número de bicapas. De acuerdo al análisis realizado, las bicapas de TiN/ZrN con relación 1:3 presentan mayor dureza (31±1 GPa) en relación a los demás sistemas y un módulo de Young de aproximadamente 460 GPa. Los resultados de las simulaciones de las propiedades mecánicas de materiales basados en Ti y Zr, empleando métodos como el de elementos finitos, son prometedores en el campo de los nuevos materiales para predecir su desempeño en aplicaciones tecnológicas e industriales como recubrimientos duros sobre diferentes herramientas y piezas de maquinaria y así disminuir costos de producción. Además, las simulaciones presentadas en este trabajo pueden extenderse a sistemas compuestos de otros materiales de gran utilidad

Scale-invariant avalanche dynamics in the temperature-driven martensitic transition of a Cu-Al-Be single crystal

We have combined high sensitivity, extra-low differential temperature scanning rate calorimetry, and acoustic emission (AE) measurements to study avalanches during the cubic ↔ 18R martensitic transition of a Cu-Al-Be single crystalline shape memory alloy. Both AE and calorimetry corroborate a good power-law behavior for cooling with an exponent É≃1.6. For heating, a slope is observed in the maximum likelihood curves, which confirms that our data are affected by an exponential cutoff. An effective energy exponent, É∼1.85, and a cutoff, λ-1=0.115(38)×10-3aJ, were determined by fits of power-laws with exponential damping. The long tail observed in the lowerature region by calorimetric measurements suggests the existence of significant elastic effects that constrain the progress of the transformation at low temperatures. While thermodynamic features such as transformation enthalpy and entropy are those expected for Cu-based shape-memory alloys undergoing a cubic ↔ 18R transition, the critical behavior deviates from the corresponding behavior expected from this symmetry change. These deviations are a consequence of the elastic hardening induced by the interplay of the transformation with dislocation jamming, which has the effect of effectively reducing the number of pathways connecting the parent and martensitic phas

Statistical Similarity between the Compression of a Porous Material and Earthquakes

It has long been stated that there are profound analogies between fracture experiments and earthquakes; however, few works attempt a complete characterization of the parallels between these so separate phenomena. We study the acoustic emission events produced during the compression of Vycor (SiO2). The Gutenberg-Richter law, the modified Omori's law, and the law of aftershock productivity hold for a minimum of 5 decades, are independent of the compression rate, and keep stationary for all the duration of the experiments. The waiting-time distribution fulfills a unified scaling law with a power-law exponent close to 2.45 for long times, which is explained in terms of the temporal variations of the activity rate

Statistical similarity between the compression of a porous material and earthquakes

It has been long stated that there are profound analogies between fracture experiments and earthquakes; however, few works attempt a complete characterization of the parallelisms between these so separate phenomena. We study the Acoustic Emission events produced during the compression of Vycor (SiO&sub&2&/sub&). The Gutenberg-Richter law, the modified Omori's law, and the law of aftershock productivity hold for a minimum of 5 decades, are independent of the compression rate, and keep stationary for all the duration of the experiments. The waiting-time distribution fulfills a unified scaling law with a power-law exponent close to 2.45 for long times, which is explained in terms of the temporal variations of the activity rate

Extensive experience of disease control with gefitinib and the role of prognostic markers

Traditionally, the efficacy of an anticancer agent has been measured by response rate. With the development of biological molecular-targeted agents, which have a different mechanism of action from conventional agents, it may be appropriate to consider alternative criteria that reflect the positive effect of these biological agents on disease control, palliation, symptom improvement and quality of life. One such targeted agent is the orally active epidermal growth factor receptor tyrosine kinase inhibitor gefitinib (‘Iressa’, ZD1839). This article reviews the clinical experience of patients with advanced/metastatic non-small-cell lung cancer, who have received gefitinib as part of a clinical trial or through the ‘Iressa’ Expanded Access Programme. Disease-control rates of ∼50% were observed in some Expanded Access Programme series, comparable with results obtained from Phase II trials. Symptom improvement was also reported. Information that will help identify those patients most likely to respond to treatment will become increasingly important. Therefore, the possible role of prognostic markers and the relationship between epidermal growth factor receptor status and response to gefitinib has been investigated. No clear association between epidermal growth factor receptor expression and response was observed. Future studies of other biomarkers in the epidermal growth factor receptor pathway should help to identify which patients are likely to benefit most from gefitinib

Epicure: a European epidemiological study of patients with an advanced or metastatic Urothelial Carcinoma (UC) having progressed to a platinum-based chemotherapy

Background: Platinum-based systemic chemotherapy is considered the backbone for management of advanced urothelial carcinomas. However there is a lack of real world data on the use of such chemotherapy regimens, on patient profiles and on management after treatment failure. Methods: Fifty-one randomly selected physicians from 4 European countries registered 218 consecutive patients in progression or relapse following a first platinum-based chemotherapy. Patient characteristics, tumor history and treatment regimens, as well as the considerations of physicians on the management of urothelial carcinoma were recorded. Results: A systemic platinum-based regimen had been administered as the initial chemotherapy in 216 patients: 15 in the neoadjuvant setting, 61 in adjuvant therapy conditions, 137 in first-line advanced setting and 3 in other conditions. Of these patients, 76 (35 %) were initially considered as cisplatin-unfit, mainly because of renal impairment (52 patients). After platinum failure, renal impairment was observed in 44 % of patients, ECOG Performance Status ≥ 2 in 17 %, hemoglobinemia 30 % patients). The most frequent all-settings second anticancer therapy regimen was vinflunine (70 % of single-agent and 42 % of all subsequent treatments), the main reasons evoked by physicians (>1 out of 4) being survival benefit, safety and phase III evidence. Conclusion: In this daily practice experience, a majority of patients with urothelial carcinoma previously treated with a platinum-based therapy received a second chemotherapy regimen, most often a single agent after an initial chemotherapy in the advanced setting and preferably a cytotoxic combination after a neoadjuvant or adjuvant chemotherapy. Performance Status and prior response to chemotherapy were the main drivers of further treatment decisions

Virtual Multidisciplinary Tumor Boards: A Narrative Review Focused on Lung Cancer

To date, the virtual multidisciplinary tumor boards (vMTBs) are increasingly used to achieve high-quality treatment recommendations across health-care regions, which expands and develops the local MTB team to a regional or national expert network. This review describes the process of lung cancer-specific MTBs and the transition process from face-to-face tumor boards to virtual ones. The review also focuses on the project organization's description, advantages, and disadvantages. Semi-structured interviews identified five major themes for MTBs: current practice, attitudes, enablers, barriers, and benefits for the MTB. MTB teams exhibited positive responses to modeled data feedback. Virtualization reduces time spent for travel, allowing easier and timely patient discussions. This process requires a secure web platform to assure the respect of patients’ privacy and presents the same unanswered problems. The implementation of vMTB also permits the implementation of networks especially in areas with geographical barriers facilitating interaction between large referral cancer centers and tertiary or community hospitals as well as easier access to clinical trial opportunities. Studies aimed to improve preparations, structure, and conduct of MTBs, research methods to monitor their performance, teamwork, and outcomes are also outlined in this article. Analysis of literature shows that MTB participants discuss 5–8 cases per meeting and that the use of a vMTB for lung cancer and in particular stage III NSCLC and complex stage IV cases is widely accepted by most health professionals. Despite still-existing gaps, overall vMTB represents a unique opportunity to optimize patient management in a patient-centered approach