X-ray crystal monochromators exposed to white-beam X-rays in third-generation synchrotron light sources are subject to thermal deformations that must be minimized using an adequate cooling system. A new approach was used to measure the crystal shape profile and slope of several cryogenically cooled (liquid nitrogen) silicon monochromators as a function of beam power in situ and under heat load. The method utilizes multiple angular scans across the Bragg peak (rocking curve) at various vertical positions of a narrow-gap slit downstream from the monochromator.
View Article and Find Full Text PDFJ Cataract Refract Surg
June 2013
Purpose: To compare the visual and aberrometric outcomes of 2 aspheric toric intraocular lenses (IOLs).
Setting: Fatebenefratelli e Oftalmico Hospital, Milan, Italy.
Design: Prospective randomized comparative study.
The vibrational dynamics of a permanently densified silica glass is compared to the one of an α-quartz polycrystal, the silica polymorph of the same density and local structure. The combined use of inelastic x-ray scattering experiments and ab initio numerical calculations provides compelling evidence of a transition, in the glass, from the isotropic elastic response at long wavelengths to a microscopic regime as the wavelength decreases below a characteristic length ξ of a few nanometers, corresponding to about 20 interatomic distances. In the microscopic regime the glass vibrations closely resemble those of the polycrystal, with excitations related to the acoustic and optic modes of the crystal.
View Article and Find Full Text PDFDisrupting inositol 1,4,5-trisphosphate (IP3) receptor (IP3R)/B-cell lymphoma 2 (Bcl-2) complexes using a cell-permeable peptide (stabilized TAT-fused IP3R-derived peptide (TAT-IDP(S))) that selectively targets the BH4 domain of Bcl-2 but not that of B-cell lymphoma 2-extra large (Bcl-Xl) potentiated pro-apoptotic Ca(2+) signaling in chronic lymphocytic leukemia cells. However, the molecular mechanisms rendering cancer cells but not normal cells particularly sensitive to disrupting IP3R/Bcl-2 complexes are poorly understood. Therefore, we studied the effect of TAT-IDP(S) in a more heterogeneous Bcl-2-dependent cancer model using a set of 'primed to death' diffuse large B-cell lymphoma (DL-BCL) cell lines containing elevated Bcl-2 levels.
View Article and Find Full Text PDFWe report a study on the temperature dependence of the core-electron excitation spectra of CO2 and N2, performed using non-resonant inelastic X-ray scattering spectroscopy. The spectra were measured at two temperatures (300 K and 850 K) and at high pressure (40 bar). For CO2 a clear temperature dependence was observed at the C and O near-edge regions.
View Article and Find Full Text PDFJ Chem Phys
February 2013
We present x-ray photon correlation spectroscopy measurements of the atomic dynamics in a Zr(67)Ni(33) metallic glass, well below its glass transition temperature. We find that the decay of the density fluctuations can be well described by compressed, thus faster than exponential, correlation functions which can be modeled by the well-known Kohlrausch-Williams-Watts function with a shape exponent β larger than one. This parameter is furthermore found to be independent of both waiting time and wave-vector, leading to the possibility to rescale all the correlation functions to a single master curve.
View Article and Find Full Text PDFPurpose: To investigate the effects of the androgen testosterone propionate (TP), on regeneration of the recurrent laryngeal nerve (RLN) after unilateral crush injury using assessment of vocal fold mobility (VFM) as a measure of behavioral recovery.
Methods: 48 adult male rats underwent standardized crush injury of left RLN and received treatment in the form of 2 silastic capsules containing TP or controls receiving a blank capsule (untreated). Direct laryngoscopic assessment of vocal cord mobility was performed before, immediately following and 1, 2, 3, 4, 5 or 6 weeks post injury.
We report a detailed analysis of the dynamic structure factor of glassy sorbitol by using inelastic X-ray scattering and previously measured light scattering data [B. Ruta, G. Monaco, F.
View Article and Find Full Text PDFWe use x-ray photon correlation spectroscopy to investigate the structural relaxation process in a metallic glass on the atomic length scale. We report evidence for a dynamical crossover between the supercooled liquid phase and the metastable glassy state, suggesting different origins of the relaxation process across the transition. Furthermore, using different cooling rates, we observe a complex hierarchy of dynamic processes characterized by distinct aging regimes.
View Article and Find Full Text PDFThe characterization questionnaire is inspired by Q-sort methodologies (i.e. qualitative sorting).
View Article and Find Full Text PDFThe mechanism of the allylation of aldehydes in the presence of allyltrichlorosilane employing the commercially available (R)-methyl p-tolyl sulfoxide as a Lewis base has been investigated. The combination of kinetic measurements, conductivity analysis and quantum chemical calculations indicates that the reaction proceeds through a dissociative pathway in which an octahedral cationic complex with two sulfoxides is involved. The lack of turnover is ascribed to the formation of neutral sulfurane derivatives.
View Article and Find Full Text PDFBiochem Biophys Res Commun
November 2012
Several members of the anti-apoptotic Bcl-2-protein family, including Bcl-2, Bcl-X(L) and Mcl-1, directly bind and regulate the inositol 1,4,5-trisphosphate receptor (IP(3)R), one of the two main intracellular Ca(2+)-release channel types present in the endoplasmic reticulum. However, the molecular determinants underlying their binding to the IP(3)R remained a matter of debate. One interaction site for Bcl-2 was proposed in the central part of the modulatory domain [Y.
View Article and Find Full Text PDFIntroduction: The transition from paternalistic medicine to a healthcare culture centred on the patient's decision making autonomy presents problems of communication and understanding. Chronic respiratory failure challenges patients, their families and caregivers with important choices, such as invasive and non-invasive mechanical ventilation and tracheostomy, which, especially in the case of neuromuscular diseases, can significantly postpone the end of life.
Material And Methods: A 7-item questionnaire was administered to 100 patients with advanced COPD, neuromuscular diseases and pulmonary fibrosis, all of them on oxygen therapy and receiving day-hospital treatment for respiratory failure.
J Phys Condens Matter
October 2012
The electronic structure of FeSe(1-x)Te(x) chalcogenide superconductors has been studied by x-ray emission (XES) and x-ray absorption (XAS) as a function of Te substitution. The Fe Kβ XES spectra reveal a relatively low spin state for Fe in FeSe(1-x)Te(x) superconductors, persisting in the whole range of Te substitution. The Fe K-edge high-resolution XAS shows systematic spectral changes due to the evolving hybridization between the Fe 3d (4p) and chalcogen p (d) orbitals.
View Article and Find Full Text PDFCell Mol Life Sci
April 2013
Anti-apoptotic Bcl-2-family members not only neutralize pro-apoptotic proteins but also directly regulate intracellular Ca(2+) signaling from the endoplasmic reticulum (ER), critically controlling cellular health, survival, and death initiation. Furthermore, distinct Bcl-2-family members may selectively regulate inositol 1,4,5-trisphosphate receptor (IP3R): Bcl-2 likely acts as an endogenous inhibitor of the IP3R, preventing pro-apoptotic Ca(2+) transients, while Bcl-XL likely acts as an endogenous IP3R-sensitizing protein promoting pro-survival Ca(2+) oscillations. Furthermore, distinct functional domains in Bcl-2 and Bcl-XL may underlie the divergence in IP3R regulation.
View Article and Find Full Text PDFBoth the ab initio expression of the current density within the ipsocentric approach and conjugated circuit models indicate that placing an unsaturated hydrocarbon inside a [4n]annulene, in such a way that outgoing C-H bonds are substituted by C-C bonds to alternating carbon atoms of the annulene, leads to an homologue altan-molecule whose perimeter is expected to preserve the paratropic circulation of the parent annulene. Computations of current on the novel altan-corannulene and altan-coronene revealed unprecedented patterns of three contra-rotating paratropic/diatropic/paratropic circulations. Graph-theoretical methods have been used to highlight the peculiar topology of these altan-molecules.
View Article and Find Full Text PDFObjectives: The aim of this study was to highlight the increasing chance of Western physicians encountering patients (both immigrants and expatriates/travelers) seeking help for loiasis.
Methods: We describe three cases of imported loiasis observed at two hospitals in Italy and France, and present a review of all previously published cases in the medical literature in the last 25 years (1986-2011). The search was performed using PubMed and Scopus databases using the terms "Loa loa" AND "loiasis".
Background: Damage to the inferior alveolar nerve (IAN) during the extraction of impacted mandibular third molars in close proximity to the mandibular canal is a postoperative complication that most frequently occurs in patients 40 years and older.
Methods: The authors evaluated the postoperative complications of 43 coronectomies of impacted mandibular third molars in 37 patients (17 men and 20 women, mean age [standard deviation] 31 [2] years). The authors used cone-beam computed tomographic images to determine that all of the teeth that underwent a coronectomy were in close proximity to the IAN.
X-ray Raman scattering (XRS) provides a bulk-sensitive method of measuring the extended X-ray absorption fine structure (EXAFS) of soft X-ray absorption edges. Accurate measurements and data analysis procedures for the determination of XRS-EXAFS of polycrystalline diamond are described. The contributions of various angular-momentum components beyond the dipole limit to the atomic background and the EXAFS oscillations are incorporated using self-consistent real-space multiple-scattering calculations.
View Article and Find Full Text PDFPurpose: To compare higher-order aberrations (HOAs) and optical quality in eyes implanted with AcrySof SN60TT toric intraocular lens (IOL) or with non-toric AcrySof SN60AT IOL (Alcon Laboratories, Inc., Fort Worth, TX).
Methods: This was a prospective, consecutive, nonrandomized, interventional, comparative study.
Calculations of nuclear magnetic shielding polarizabilities of the P-hexahelicene and 8,9-difluoro-P-hexahelicene molecules have been accomplished at the CTOCD-DZ2/6-31G(d,p) level. Pseudoscalars of the nuclear magnetic shielding polarizability are the largest reported so far for second-row atoms. The rf voltage generated by the rotating chiral electric polarization, induced by the permanent magnetic dipole moment of the (19)F nuclei of the 8,9-difluoro-P-hexahelicene and by the spectrometer's magnetic field, is predicted to be ≈10 nV, that is, detectable with modern equipments.
View Article and Find Full Text PDFWe report x-ray photoemission spectroscopy results on (Ga,Mn)As films as a function of both temperature and Mn doping. Analysis of Mn 2p core level spectra reveals the presence of a distinct electronic screening channel in the bulk, hitherto undetected in more surface sensitive analysis. Comparison with model calculations identifies the character of the Mn 3d electronic states and clarifies the role, and the difference between surface and bulk, of hybridization in mediating the ferromagnetic coupling in (Ga,Mn)As.
View Article and Find Full Text PDFObjective: (1) Explain the need for an animal model to study intracranial injuries to the facial nerve. (2) Describe various techniques attempted to identify and crush the intracranial segment of the facial nerve in a rat model. (3) Describe in detail a successful rat model of intracranial facial nerve crush injury.
View Article and Find Full Text PDFThe interpretation of the oxygen near-edge spectrum of water has been debated intensively. We present new measurements of the temperature dependence of the spectrum and perform a van't Hoff analysis for the pre-edge intensity. Many microscopical and thermodynamic properties of liquid water have been described in the literature in terms of mixture models, which presume the existence of two distinct species with different local structures.
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