Home About us Contact | |||
Functional Stability (functional + stability)
Selected AbstractsShape Memory Materials: Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis and Unprecedented Functional Stability (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Mater. On page 1917, R. Zarnetta et al. report that for the reversible martensitic transformation in shape memory alloys the compatibility at the austenite/martensite interface is directly related to the width of the thermal hysteresis and to the functional stability. A "perfect" compatibility results in the growth of twinless martensite (blue) within the austenite (red), as shown in the TEM image for a Ti50Ni39Pd11 shape memory alloy (image provided courtesy of R. Delville). [source] Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis and Unprecedented Functional StabilityADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Robert Zarnetta Abstract Improving the functional stability of shape memory alloys (SMAs), which undergo a reversible martensitic transformation, is critical for their applications and remains a central research theme driving advances in shape memory technology. By using a thin-film composition-spread technique and high-throughput characterization methods, the lattice parameters of quaternary Ti,Ni,Cu,Pd SMAs and the thermal hysteresis are tailored. Novel alloys with near-zero thermal hysteresis, as predicted by the geometric non-linear theory of martensite, are identified. The thin-film results are successfully transferred to bulk materials and near-zero thermal hysteresis is observed for the phase transformation in bulk alloys using the temperature-dependent alternating current potential drop method. A universal behavior of hysteresis versus the middle eigenvalue of the transformation stretch matrix is observed for different alloy systems. Furthermore, significantly improved functional stability, investigated by thermal cycling using differential scanning calorimetry, is found for the quaternary bulk alloy Ti50.2Ni34.4Cu12.3Pd3.1. [source] A putative role for cell cycle-related proteins in microtubule-based neuroplasticityEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2009Stefanie Schmetsdorf Abstract Cyclins and cyclin-dependent kinases (Cdks) are the main components that control the orderly progression through cell cycle. In the mature nervous system, terminally differentiated neurons are permanently withdrawn from cell cycle, as mitotic quiescence is essential for the functional stability of the complexly wired neuronal system. Recently, we characterized the expression and colocalization of cyclins and Cdks in terminally differentiated pyramidal neurons. The functional impact of the expression of cell cycle-related proteins in differentiated neurons, however, has not been elucidated yet. In the present study, we show by immunoelectron microscopy and immunobiochemical methods an association of cyclins and Cdks with the microtubule network. Cyclins D, E, A and B as well as Cdks 1, 2 and 4 were also found to be associated with the microtubule-associated protein tau. Cyclin/Cdk complexes, in addition, exhibit kinase activity towards tau. In vitro, downregulation of cyclins and Cdks by a siRNA approach and by pharmacological inhibition promotes neurite extension. Taken together, these results indicate that the expression of cell cycle-related proteins in terminal differentiated neurons is associated with physiological functions beyond cell cycle control that might be involved in microtubule-based mechanisms of neuroplasticity. [source] Unusual stability of human neuroglobin at low pH , molecular mechanisms and biological significanceFEBS JOURNAL, Issue 23 2009Paola Picotti Neuroglobin (Ngb) is a recently discovered globin that is predominantly expressed in the brain, retina and other nerve tissues of human and other vertebrates. Ngb has been shown to act as a neuroprotective factor, promoting neuronal survival in conditions of hypoxic,ischemic insult, such as those occurring during stroke. In this work, the conformational and functional stability of Ngb at acidic pH was analyzed, and the results were compared to those obtained with Mb. It was shown by spectroscopic and biochemical (limited proteolysis) techniques that, at pH 2.0, apoNgb is a folded and rigid protein, retaining most of the structural features that the protein displays at neutral pH. Conversely, apoMb, under the same experimental conditions of acidic pH, is essentially a random coil polypeptide. Urea-mediated denaturation studies revealed that the stability displayed by apoNgb at pH 2.0 is very similar to that of Mb at pH 7.0. Ngb also shows enhanced functional stability as compared with Mb, being capable of heme binding over a more acidic pH range than Mb. Furthermore, Ngb reversibly binds oxygen at acidic pH, with an affinity that increases as the pH is decreased. It is proposed that the acid-stable fold of Ngb depends on the particular amino acid composition of the protein polypeptide chain. The functional stability at low pH displayed by Ngb was instead shown to be related to hexacoordination of the heme group. The biological implications of the unusual acid resistance of the folding and function of Ngb are discussed. [source] Shape Memory Materials: Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis and Unprecedented Functional Stability (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Mater. On page 1917, R. Zarnetta et al. report that for the reversible martensitic transformation in shape memory alloys the compatibility at the austenite/martensite interface is directly related to the width of the thermal hysteresis and to the functional stability. A "perfect" compatibility results in the growth of twinless martensite (blue) within the austenite (red), as shown in the TEM image for a Ti50Ni39Pd11 shape memory alloy (image provided courtesy of R. Delville). [source] Identification of Quaternary Shape Memory Alloys with Near-Zero Thermal Hysteresis and Unprecedented Functional StabilityADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Robert Zarnetta Abstract Improving the functional stability of shape memory alloys (SMAs), which undergo a reversible martensitic transformation, is critical for their applications and remains a central research theme driving advances in shape memory technology. By using a thin-film composition-spread technique and high-throughput characterization methods, the lattice parameters of quaternary Ti,Ni,Cu,Pd SMAs and the thermal hysteresis are tailored. Novel alloys with near-zero thermal hysteresis, as predicted by the geometric non-linear theory of martensite, are identified. The thin-film results are successfully transferred to bulk materials and near-zero thermal hysteresis is observed for the phase transformation in bulk alloys using the temperature-dependent alternating current potential drop method. A universal behavior of hysteresis versus the middle eigenvalue of the transformation stretch matrix is observed for different alloy systems. Furthermore, significantly improved functional stability, investigated by thermal cycling using differential scanning calorimetry, is found for the quaternary bulk alloy Ti50.2Ni34.4Cu12.3Pd3.1. [source] Immunohistochemical Study of HLA-G Expression in Lung Transplant RecipientsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 6 2009O Brugière Human leukocyte antigen-G (HLA-G), a nonclassical HLA class I protein, promotes immune tolerance of solid-organ allografts, yet its role in lung transplantation (LTx) is unknown. We examined the expression of HLA-G in lung allografts through immunohistochemistry by a cross-sectional study of 64 LTx recipients, classified into four groups (stable patients, acute rejection [AR], bronchiolitis obliterans syndrome [BOS] and symptomatic viral shedders). A marked expression of HLA-G in bronchial epithelial cells (BEC) was frequently observed in stable recipients (n = 18/35 [51%]), but not in patients with AR (n = 14) or with BOS (n = 8). HLA-G was also expressed by 4 of 7 symptomatic viral shedders. In addition, HLA-G-positive patients from the stable group (n = 35) experienced lower incidence of resistant AR and/or BOS during long-term follow-up, as compared with their HLA-G-negative counterparts. Finally, in vitro data showed that interferon-,, a cytokine present in lung allograft microenvironment, upregulated HLA-G mRNA and protein expression in primary cultured human BEC. We conclude that HLA-G expression in the bronchial epithelium of lung allograft is elevated in some LTx recipients in association with their functional stability, suggesting a potential role of HLA-G as a tolerance marker. [source] Uncovering microbial communities: Does functional stability require community stability?BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2008Article first published online: 26 NOV 200 No abstract is available for this article. [source] |