Phononic Crystal Made of Multilayered Ridges on a Substrate for Rayleigh Waves Manipulation

International audienceWe present a phononic crystal to achieve efficient manipulation of surface acoustic waves (SAW). The structure is made of finite phononic micro-ridges arranged periodically in a substrate surface. Each ridge is constructed by staking silicon and tungsten layers so that it behaves as one-dimensional phononic crystal which exhibits band gaps for elastic waves. The band gap allows the existence of resonance modes where the elastic energy is either confined within units in the free end of the ridge or the ones in contact with the substrate. We show that SAW interaction with localized modes in the free surface of the ridge gives rise to sharp attenuation in the SAW transmission while the modes confined within the ridge/ substrate interface cause broad band attenuations of SAW. Furthermore, we demonstrate that the coupling between the two kinds of modes within the band gap gives high SAW transmission amplitude in the form of Fano like peaks with high quality factor. The structure could provide an interesting solution for accurate SAW control for sensing application for instance

Knockout of Vdac1 activates hypoxia-inducible factor through reactive oxygen species generation and induces tumor growth by promoting metabolic reprogramming and inflammation

BACKGROUND: Mitochondria are more than just the powerhouse of cells; they dictate if a cell dies or survives. Mitochondria are dynamic organelles that constantly undergo fusion and fission in response to environmental conditions. We showed previously that mitochondria of cells in a low oxygen environment (hypoxia) hyperfuse to form enlarged or highly interconnected networks with enhanced metabolic efficacy and resistance to apoptosis. Modifications to the appearance and metabolic capacity of mitochondria have been reported in cancer. However, the precise mechanisms regulating mitochondrial dynamics and metabolism in cancer are unknown. Since hypoxia plays a role in the generation of these abnormal mitochondria, we questioned if it modulates mitochondrial function. The mitochondrial outer-membrane voltage-dependent anion channel 1 (VDAC1) is at center stage in regulating metabolism and apoptosis. We demonstrated previously that VDAC1 was post-translationally C-terminal cleaved not only in various hypoxic cancer cells but also in tumor tissues of patients with lung adenocarcinomas. Cells with enlarged mitochondria and cleaved VDAC1 were also more resistant to chemotherapy-stimulated cell death than normoxic cancer cells. RESULTS: Transcriptome analysis of mouse embryonic fibroblasts (MEF) knocked out for Vdac1 highlighted alterations in not only cancer and inflammatory pathways but also in the activation of the hypoxia-inducible factor-1 (HIF-1) signaling pathway in normoxia. HIF-1α was stable in normoxia due to accumulation of reactive oxygen species (ROS), which decreased respiration and glycolysis and maintained basal apoptosis. However, in hypoxia, activation of extracellular signal-regulated kinase (ERK) in combination with maintenance of respiration and increased glycolysis counterbalanced the deleterious effects of enhanced ROS, thereby allowing Vdac1 (-/-) MEF to proliferate better than wild-type MEF in hypoxia. Allografts of RAS-transformed Vdac1 (-/-) MEF exhibited stabilization of both HIF-1α and HIF-2α, blood vessel destabilization, and a strong inflammatory response. Moreover, expression of Cdkn2a, a HIF-1-target and tumor suppressor gene, was markedly decreased. Consequently, RAS-transformed Vdac1 (-/-) MEF tumors grew faster than wild-type MEF tumors. CONCLUSIONS: Metabolic reprogramming in cancer cells may be regulated by VDAC1 through vascular destabilization and inflammation. These findings provide new perspectives into the understanding of VDAC1 in the function of mitochondria not only in cancer but also in inflammatory diseases

Young children's understanding of disabilities: the influence of development, context and cognition

Throughout Europe, educational support for children with disabilities has moved towards a model of inclusive education. Such policy changes mean that for all children there will be an increased likelihood of working with and encountering children with differing disabilities and difficulties. Previous research had indicated that children had poorly differentiated views of developmental differences. The present study investigated children?s representations of different disabilities. Seventy-nine 8-9 and 10-11 year old Greek children from an urban school and a rural school completed an attitudes toward school inclusion rating scale and a semi-structured interview. Responses to the attitude scale provided generally positive views of educational inclusion. However, children were less positive about activities that might directly reflect upon themselves. Children?s responses in the interviews indicated that they were developing rich representations of differences and diversities. Children had the greatest understanding of sensory and physical disabilities, followed by learning disabilities. There was limited knowledge of dyslexia and hyperactivity and no child was familiar with the term autism. Both groups of children identified a range of developmental difficulties, with older children being more aware of specific learning disabilities, their origin and impact. Results are discussed in terms of children?s developing knowledge systems and the implications for educational practices

Osteonecrosis of the jaw induced by clodronate, an alkylbiphosphonate: case report and literature review.

ERMAInternational audiencePURPOSE: To report on a case of osteonecrosis of the jaw (ONJ) in a patient treated with clodronate, an alkylbiphosphonate, and to draw attention to the risk of ONJ following treatment with all biphosphonates, whether they are alkyl- or amino-biphosphonates. CASE REPORT: Beginning at age 58 years, a female patient took clodronate for almost 13 years for a metastatic bone cancer. She also underwent chemotherapy and radiotherapy. Three months after the end of biphosphonate therapy, she suffered from toothache, and tooth 27 (left maxillary second molar) was extracted. A maxillary focus of osteitis with an oral sinus communication was discovered, and a maxillofacial denture prosthesis was grafted in September 2006. Some days later, the patient consulted her dentist for an ulceration of the oral cavity floor in front of tooth 33 (left mandibular canine) extending to the left inferior side of the lip. In October 2006, teeth 33 and 34 (left mandibular first premolar) were extracted. No secondary infection occurred. A complete healing was only observed 3 months after the last extraction. ONJ due to alkylbiphosphonate treatment was diagnosed as bone reconstruction and mucous cicatrisation were delayed. METHODS: A systematic review was carried out to identify all cases of alkylbiphosphonate-induced ONJ by searching the Medline and Cochrane databases using 'osteonecrosis of the jaw', 'jaw diseases', 'osteonecrosis', 'diphosphonate', 'biphosphonate' (amino-, alkyl- or the international nonproprietary name) as the main search items. The search was limited to English- and French-language articles published between 1966 and February 2010. RESULTS: Our search identified 27 cases of alkylbiphosphonate-induced ONJ in the literature. Among these cases, only ten patients were on alkylbiphosphonate monotherapy; in the other cases, aminobiphosphonates had also been used. The clinical presentation of the alkylbiphosphonate-induced ONJ was similar to that most often encountered with aminobiphosphonate treatment. The duration of exposure before onset was higher with alkylbiphosphonates than with aminobiphosphonates, and dental procedures before ONJ were frequent. CONCLUSION: Osteonecrosis of the jaw has been widely reported with various aminobiphosphonates, but data on the role of alkylbiphosphonates are scarce. As these latter drugs are less potent, a high cumulative dose through long-term exposure would appear to be necessary and would favour ONJ. Although the degree of risk for ONJ occurrence in patients on alkylbiphosphonates remains uncertain, it would be wise to reconsider carefully the indications for using these agents and to apply preventive measures as is currently done for aminobiphosphonates

Growth and toxic gas sensing properties of poly(urethaneimide) thin films

In this work we present a study on the growth and the gas sensing properties of poly(urethane imide) thin films. We first deeply characterized by atomic force microscopy (AFM) the nanostructuration of the poly(urethane imide) holding different amine groups. We further studied the interaction between highly toxic gases such as hexamethyleneimine (HMI) and pyridine and the polymer by using an unconventional method based on Quartz Crystal Microbalance (QCM) measurement. We showed for the first time that weak interactions, i.e. hydrogen bonding between the gas molecules and the polymer film allow the diffusion of the gas molecule deep in the polymeric film and the recovery of the film once the gas molecules leave the sensor. This first work paves a new way for the design of a completely recoverable sensor able to detect highly toxic gases for environmental concern

Nano-particle mass sensing using phononic pillars

International audienceIn this work, we investigate the sensitivity of a pillar based metasurface in order to understand the behavior of the system in real tests conditions where the mass perturbation will not be homogeneous on all the system. The structure we study is composed in stacking alternate layers of Silica and Tungsten and presents a torsional resonant mode which presents a high quality factor and a high mass sensitivity, in a case of a homogeneous perturbation. In a case of a non-homogeneous mass-perturbation over the pillars, each pillar gives a contribution to the signal perturbation under the form of a shifted peak. These results show that each pillar gives a contribution to the output signal and that the high quality factor of the structure allows to distinguishing the different perturbations