Coupling Of The B1g Phonon To The Anti-Nodal Electronic States of Bi2Sr2Ca0.92Y0.08Cu2O(8+delta)

Angle-resolved photoemission spectroscopy (ARPES) on optimally doped Bi2Sr2Ca0.92Y0.08Cu2O(8+delta) uncovers a coupling of the electronic bands to a 40 meV mode in an extended k-space region away from the nodal direction, leading to a new interpretation of the strong renormalization of the electronic structure seen in Bi2212. Phenomenological agreements with neutron and Raman experiments suggest that this mode is the B1g oxygen bond-buckling phonon. A theoretical calculation based on this assignment reproduces the electronic renormalization seen in the data.Comment: 4 Pages, 4 Figures Updated Figures and Tex

Doping dependence of the coupling of electrons to bosonic modes in the single-layer high-temperature Bi2Sr2CuO6 superconductor

A recent highlight in the study of high-Tc superconductors is the observation of band renormalization / self-energy effects on the quasiparticles. This is seen in the form of kinks in the quasiparticle dispersions as measured by photoemission and interpreted as signatures of collective bosonic modes coupling to the electrons. Here we compare for the first time the self-energies in an optimally doped and strongly overdoped, non-superconducting single-layer Bi-cuprate (Bi2Sr2CuO6). Besides the appearance of a strong overall weakening, we also find that weight of the self-energy in the overdoped system shifts to higher energies. We present evidence that this is related to a change in the coupling to c-axis phonons due to the rapid change of the c-axis screening in this doping range.Comment: 4 pages, 3 figure

Screening of different Fusarium species to select potential species for the synthesis of silver nanoparticles

Eleven different Fusarium species were isolated from various infected plant materials and screened to select a potential species for the synthesis of silver nanoparticles. All the isolates were identified on the basis of cultural and microscopic characteristics using Fusarium identification keys. For the confirmation of preliminary identified isolates of Fusarium species, online BLAST analysis was carried out. All the eleven species demonstrated the ability for synthesis of silver nanoparticles. This was confirmed by UV-Vis spectroscopy, which gave characteristic peak around 420 nm. Further confirmation of silver nanoparticles was carried out using nanoparticles tracking analysis (NTA), zeta potential, photon correlation spectroscopy (PCS), powder X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The smallest size of silver nanoparticles was synthesized by F. oxysporum (3-25 nm) and largest size silver nanoparticles were synthesized by F. solani (3-50 nm).Onze diferentes espécies de Fusarium foram isoladas a partir de vários materiais vegetais infectados e selecionados para escolher uma espécie potencialmente importante para a síntese de nanopartículas de prata. Todos os isolados foram identificados com base nas características de cultivo e microscópicas usando as chaves de identificação de Fusarium. Para a confirmação e identificação preliminar dos isolados de espécies de Fusarium, a análise BLAST on-line foi utilizada. Das espécies isoladas onze mostraram a capacidade para a síntese de nanopartículas de prata. A síntese de nanopartículas de prata foi confirmada por espectroscopia de UV-Vis que monstrou um pico característico em torno de 420 nm. Além disso, a confirmação da síntese de nanopartículas de prata foi realizada utilizando a análise de rastreamento de nanoparticulas (nanoparticle tracking analysis-NTA), medidas de potencial zeta, espectroscopia de correlação de fótons (PCS), difratometria de raios X de pó (XRD), e microscopia eletrônica de transmissão (TEM). As menores nanopartículas de prata foram sintetizadas por F. oxysporum (3-25 nm), enquanto as maiores foram obtidas com F. solani (3-50 nm).19741982Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Fully Gapped Single-Particle Excitations in the Lightly Doped Cuprates

The low-energy excitations of the lightly doped cuprates were studied by angle-resolved photoemission spectroscopy. A finite gap was measured over the entire Brillouin zone, including along the d_{x^2 - y^2} nodal line. This effect was observed to be generic to the normal states of numerous cuprates, including hole-doped La_{2-x}Sr_{x}CuO_{4} and Ca_{2-x}Na_{x}CuO_{2}Cl_{2} and electron-doped Nd_{2-x}Ce_{x}CuO_{4}. In all compounds, the gap appears to close with increasing carrier doping. We consider various scenarios to explain our results, including the possible effects of chemical disorder, electronic inhomogeneity, and a competing phase.Comment: To appear in Phys. Rev.

Structural origin of apparent Fermi surface pockets in angle-resolved photoemission of Bi2_2Sr2−x_{2-x}Lax_xCuO6+δ_{6+\delta}

We observe apparent hole pockets in the Fermi surfaces of single-layer Bi-based cuprate superconductors from angle-resolved photoemission (ARPES). From detailed low-energy electron diffraction measurements and an analysis of the ARPES polarization-dependence, we show that these pockets are not intrinsic, but arise from multiple overlapping superstructure replicas of the main and shadow bands. We further demonstrate that the hole pockets reported recently from ARPES [Meng et al, Nature 462, 335 (2009)] have a similar structural origin, and are inconsistent with an intrinsic hole pocket associated with the electronic structure of a doped CuO$_2$ plane. The nature of the Fermi surface topology in the enigmatic pseudogap phase therefore remains an open question.Comment: 5 pages, 4 figure

A recurrent epidermoid cyst of the spleen: report of a case and literature review

BACKGROUND: Splenic cysts are rare disease. Epidermoid cysts of the spleen belong to the primary nonparasitic splenic cysts group. They are an unusual event in surgical practice. Usually, epidermoid cysts occur in children and young female. Most often, they are asymptomatic, but they may present with abdominal discomfort. CASE PRESENTATION: We are reporting a rare case of a 23-year-old female came to our attention with history of intermittent pain and previously undergone two times to laparoscopic decapsulation of the cyst in others institutions. During hospitalization, serum and intracystic levels of tumor marker CA19-9 increased. Enhanced CT of the abdomen showed recurrent large cyst in the upper pole of the spleen with satellite nodules. Laparotomic total splenectomy was performed. Histopathological and immunoreactive examinations were executed, and they revealed stratified squamous epithelium on the inner surface of cystic wall, which was positive for EMA, CEA, and CA19-9. The diagnosis of epidermoid cyst was confirmed. CONCLUSIONS: Recently, the surgical approach is changing towards conservative treatments in order to save the spleen in young patients for immunological reasons. Sometimes, this target is not achievable. In such circumstances, like recurrent large cyst, anomalous anatomical relationship to the surrounding tissues, total splenectomy is safe and necessary

Configuration of anchorage holes affects fixation of the acetabular component in cemented total hip replacement - a finite element study

Our survey of current practice among UK orthopaedic surgeons shows wide variations in fixation techniques. The aim of this study is to investigate the effect of drilling different configurations of anchorage holes in the acetabulum on implant stability. To avoid variables that could incur during in-vitro testing, we used commercially-available COSMOS finite element analysis package to investigate the stress distributions, deformations, and strains on the cement mantle when drilling three large anchorage holes and six smaller ones, with straight and rounded cement pegs. The results, which are in line with our in-vitro studies on simulated reconstructed acetabulae, indicate better stability of the acetabular component when three larger holes than six smaller holes are drilled and when the necks of the anchorage holes are rounded. The longevity of total hip replacements could be improved by drilling three large anchorage holes, rather than many smaller ones, as initially proposed by Charnley

Gedanken experiments with Casimir forces, vacuum energy, and gravity

Gedanken experiments are used to explore properties of quantum vacuum energy that are currently challenging to explore experimentally. A constant lateral Casimir force is predicted to exist between two overlapping finite parallel plates at 0 K, otherwise it would be possible to extract an arbitrary amount of energy from the quantum vacuum. A rigid unpowered object cannot be accelerated by the quantum vacuum because of the translational symmetry of space. By considering systems in which vacuum energy and other forms of energy are exchanged, we demonstrate that a change {\Delta}E in vacuum energy, whether positive or negative with respect to the free field, corresponds to an equivalent inertial mass and equivalent gravitational mass {\Delta}M={\Delta}E/c^2. We consider the possibility of a gravitational shield, and show that, if it exists, the energy to operate it would have to cancel the net energy extracted from the gravitational field, otherwise we could extract an arbitrary amount of energy from the field.Comment: 24 pages, 3 figure