Effects of polarization on the band-structure of delafossite transparent conductive oxides

We use hybrid functionals and restricted self-consistent GW, state-of-the-art theoretical approaches for quasiparticle band structures, to study the electronic states of delafossite Cu(Al,In)O$_2$, the first p-type and bipolar transparent conductive oxides. We show that self-consistent GW gives remarkably wider band gaps than all the other approaches used so far. Accounting for polaronic effects in the GW scheme we recover a very nice agreement with experiments. Furthermore, the modifications with respect to the Kohn-Sham bands are strongly k-dependent, which makes questionable the common practice of using a scissor operator. Finally, our results support the view that the low energy structures found in optical experiments, and initially attributed to an indirect transition, are due to intrinsic defects in the samples.Comment: publishe

Influence of isothermal and cyclic oxidation on the apparent interfacial toughness in thermal barrier coating systems

In thermal barrier coatings (TBCs), the toughness relative to the interface lying either between the bond coat (BC) and the Thermal Grown Oxide (TGO) or between the TGO and the yttria stabilized zirconia topcoat (TP) is a critical parameter regarding TBCs durability. In this paper, the influence of aging conditions on the apparent interfacial toughness in Electron Beam-Physical Vapor Deposition (EB-PVD) TBCs is investigated using a specifically dedicated approach based on Interfacial Vickers Indentation (IVI), coupled with Scanning Electron Microscopy (SEM) observations to create interfacial cracks and measure the extent of crack propagation, respectively

A continuous optimization framework for hybrid system identification

International audienceWe propose a new framework for hybrid system identification, which relies on continuous optimization. This framework is based on the minimization of a cost function that can be chosen as either the minimum or the product of loss functions. The former is inspired by traditional estimation methods, while the latter is inspired by recent algebraic and support vector regression approaches to hybrid system identification. In both cases, the identification problem is recast as a continuous optimization program involving only the real parameters of the model as variables, thus avoiding the use of discrete optimization. This program can be solved efficiently by using standard optimization methods even for very large data sets. In addition, the proposed framework easily incorporates robustness to different kinds of outliers through the choice of the loss function

Nonlinear Hybrid System Identification with Kernel Models

CDROM DOI: 10.1109/CDC.2010.5718011International audienceThis paper focuses on the identification of nonlinear hybrid systems involving unknown nonlinear dynamics. The proposed method extends the framework of [1] by introducing nonparametric models based on kernel functions in order to estimate arbitrary nonlinearities without prior knowledge. In comparison to the previous work of [2], which also dealt with unknown nonlinearities, the new algorithm assumes the form of an unconstrained nonlinear continuous optimization problem, which can be efficiently solved for moderate numbers of parameters in the model, as is typically the case for linear hybrid systems. However, to maintain the efficiency of the method on large data sets with nonlinear kernel models, a preprocessing step is required in order to fix the model size and limit the number of optimization variables. A support vector selection procedure, based on a maximum entropy criterion, is proposed to perform this step. The efficiency of the resulting algorithm is demonstrated on large-scale experiments involving the identification of nonlinear switched dynamical systems

Feasibility of luminescent multilayer sol-gel thermal barrier coating manufacturing for future applications in through-thickness temperature gradient sensing

This paper investigates the feasibility of manufacturing sol-gel multilayer thermal barrier coatings (TBC) functionalized with different lanthanide ions Ln3 + having distinct photo-luminescence emission wavelengths (Ln = Sm, Eu, Dy, Er, Tm) for future applications in temperature gradient sensing. Ln3 + doped 9.75 mol% yttria stabilized zirconia (YSZ) powders were produced to study the effect of activator concentration on luminescence intensity and host matrix crystal structure. Self-quenching was found to limit the maximum signal-to-noise ratio achievable with Sm3 +, Dy3 +, Er3 + and Tm3 + activators, which was not the case for Eu3 + in the 1–10 mol% range. The increase in activator was found to affect the crystal structure of YSZ. A solution was proposed that suppressed this effect while significantly increasing the luminescence intensity of all activators. Finally a TBC sensor prototype integrating Eu3 +, Er3 + and Dy3 + doped layers distributed throughout the thickness was successfully deposited by a dip-coating sol-gel process and showed promising through-thickness luminescence sensing capabilities

Optimized sol–gel thermal barrier coatings for long-term cyclic oxidation life

New promising thermal barrier coatings (TBCs) processed by the sol–gel route are deposited onto NiPtAl bond coated superalloy substrates usingthe dip and/or spray coating technique. In this study, the optimization of the process, including an appropriate heat treatment prone to densifythe yttria-stabilized-zirconia (YSZ) top-coat and leading to the sintering and the development of a resulting crack network, is investigated. Inparticular, relevant information on internal strain evolution during the heat treatment are obtained using in situ synchrotron X-rays diffraction andconfirm a stabilization of the TBC through the occurrence of the micro-cracks that beneficially releases the in-plane sintering stress. Such TBCs aresubsequently reinforced using additional material brought within the cracks using sol–gel spray coating. The effect of various process parameters,such as the pre-oxidation of the bond-coat, on the sol gel TBCs consolidation and their cyclic oxidation resistance enhancement, is presented.Reinforced sol–gel TBCs are successfully oxidized up to more than one thousand 1 h-cycles at 1100◦C, without any detrimental spallation

Experimental transmission to a calf of an isolate of Spanish classical scrapie

Multiple theories exist regarding the origin of bovine spongiform encephalopathy (BSE). An early and prominent theory proposed that BSE was the result of the adaptation of sheep scrapie to cattle. The reports to date indicate that the distribution of the pathological prion protein (PrPSc) in experimental bovine scrapie is largely restricted to the central nervous system (CNS). Here, we describe pathological findings in a calf intracerebrally inoculated with a Spanish classical scrapie isolate. While clinical disease was observed 30 months after inoculation and PrPSc was detected in the CNS, the corresponding phenotype differed from that of BSE. Immunohistochemistry and PMCA also revealed the presence of PrPSc in the peripheral nerves, lymphoid tissues, skeletal muscle and gastrointestinal tract, suggesting centrifugal spread of the scrapie agent from the brain. To the best of our knowledge, this is the first report describing the detection of PrPSc in tissues other than the CNS after experimental transmission of scrapie to cattle

Processing thermal barrier coatings via sol-gel route: crack network control and durability

Thermal barrier coatings (TBC) processed by sol–gel route are deposited onto NiPtAl bond coated superalloy substrates. A crack microstructure, if well controlled, is adequate to get satisfactory thermo-mechanical behaviour when the TBC is cyclically oxidized. This paper deals with the adjustment of the properties of the microcracked network which is inherent to the process by changing the formulation of the sol and by adding a reinforcement step. The objective is to reduce the size and depth of the surface cracks network. This network controls the release of thermo-mechanical stress in the layers and reduces detrimental propagation of cracks that could result in the spallation of the coatings during engine operation. Several physico-chemical characterizations were performed, associated to image analyses to (i) evaluate the cracks distribution (depth, length and width), in the case of two dispersants, and (ii) to estimate their influence on the performances of TBC systems. Characterizations by cyclic oxidation were carried out using a cyclic oxidation instrumented rig to monitor on a real time basis the crack propagation and spallation. Correlations between the cracked network parameters and the lifetime of the TBC are proposed in this paper

Early Toxicities After High Dose Rate Proton Therapy in Cancer Treatments

Background: The conventional dose rate of radiation therapy is 0.01-0.05 Gy per second. According to preclinical studies, an increased dose rate may offer similar anti-tumoral effect while dramatically improving normal tissue protection. This study aims at evaluating the early toxicities for patients irradiated with high dose rate pulsed proton therapy (PT). Materials and methods: A single institution retrospective chart review was performed for patients treated with high dose rate (10 Gy per second) pulsed proton therapy, from September 2016 to April 2020. This included both benign and malignant tumors with ≥3 months follow-up, evaluated for acute (≤2 months) and subacute (>2 months) toxicity after the completion of PT. Results: There were 127 patients identified, with a median follow up of 14.8 months (3-42.9 months). The median age was 55 years (1.6-89). The cohort most commonly consisted of benign disease (55.1%), cranial targets (95.1%), and were treated with surgery prior to PT (56.7%). There was a median total PT dose of 56 Gy (30-74 Gy), dose per fraction of 2 Gy (1-3 Gy), and CTV size of 47.6 ml (5.6-2,106.1 ml). Maximum acute grade ≥2 toxicity were observed in 49 (38.6%) patients, of which 8 (6.3%) experienced grade 3 toxicity. No acute grade 4 or 5 toxicity was observed. Maximum subacute grade 2, 3, and 4 toxicity were discovered in 25 (19.7%), 12 (9.4%), and 1 (0.8%) patient(s), respectively. Conclusion: In this cohort, utilizing high dose rate proton therapy (10 Gy per second) did not result in a major decrease in acute and subacute toxicity. Longer follow-up and comparative studies with conventional dose rate are required to evaluate whether this approach offers a toxicity benefit