207 research outputs found
A novel route to phase formation of cobalt oxyhydrates using KMnO4 as an oxidizing agent
We have first succeefully synthesized the sodium cobalt oxyhydrate
superconductors using KMnO4 as a de-intercalating and oxidizing agent. It is a
novel route to form the superconductive phase of NaxCoO2.yH2O without resorting
to the commonly used Br2/CH3CN solution. The role of the KMnO4 is to
de-intercalate the Na+ from the parent compound Na0.7CoO2 and oxidize the Co
ion as a result. The higher molar ratio of KMnO4 relative to the sodium content
tends to remove more Na+ from the parent compound and results in a slight
expansion of the c-axis in the unit cell. The superconducting transition
temperature is 4.6-3.8 K for samples treated by the aqueous KMnO4 solution with
the molar ratio of KMnO4 relative to the sodium content in the range of 0.3 and
2.29.Comment: 10 pages, 3 figure
Magnetic and Metal-Insulator Transitions in beta-Na0.5CoO2 and gamma-K0.5CoO2 -NMR and Neutron Diffraction Studies-
Co-oxides beta-Na0.5CoO2 and gamma-K0.5CoO2 have been prepared by the Na
de-intercalation from alpha-NaCoO2 and by the floating-zone method,
respectively. It has been found that successive phase transitions take place at
temperatures Tc1 and Tc2 in both systems. The appearance of the internal
magnetic field at Tc1 with decreasing temperature T indicates that the
antiferromagnetic order exists at T < Tc1, as in gamma-Na0.5CoO2. For
beta-Na0.5CoO2, the transition temperatures and the NMR parameters determined
from the data taken for magnetically ordered state are similar to those of
gamma-Na0.5CoO2, indicating that the difference of the stacking ways of the
CoO2 layers between these systems do not significantly affect their physical
properties. For gamma-K0.5CoO2, the quantitative difference of the physical
quantities are found from those of beta- and gamma-Na0.5CoO2. The difference
between the values of Tci (i = 1 and 2) of these systems might be explained by
considering the distance between CoO2 layers.Comment: 8 pages, 14 figures, 1 Tabl
Precise Control of Band Filling in NaxCoO2
Electronic properties of the sodium cobaltate NaxCoO2 are systematically
studied through a precise control of band filling. Resistivity, magnetic
susceptibility and specific heat measurements are carried out on a series of
high-quality polycrystalline samples prepared at 200 C with Na content in a
wide range of 0.35 =< x =< 0.70. It is found that dramatic changes in
electronic properties take place at a critical Na concentration x* that lies
between 0.58 and 0.59, which separates a Pauli paramagnetic and a Curie-Weiss
metals. It is suggested that at x* the Fermi level touches the bottom of the
a1g band at the gamma point, leading to a crucial change in the density of
states across x* and the emergence of a small electron pocket around the gamma
point for x > x*.Comment: 4 pages, 5 figures, submitted to J. Phys. Soc. Jp
Effect of Na content and hydration on the excitation spectrum of the cobaltite Na_xCoO_2 yH_2O
We report on a Raman scattering study on the superconducting cobaltite
as function of Na content and hydration (x1/3,
3/4 and y0, 2/3, 4/3). The observed phonon scattering and scattering
continua are analyzed in terms of lattice strain due to the structural misfit
and disorder. Hydration, due to the intercalation of one or two layers,
releases a part of this strain. Our Raman data suggest a connection between
disorder on the partly occupied Na sites, the split off of the level
from the other states of and superconductivity.Comment: 10 pages, 4 figures, for further information see
http://www.peter-lemmens.d
Low phospholipid associated cholelithiasis: association with mutation in the MDR3/ABCB4 gene
Low phospholipid-associated cholelithiasis (LPAC) is characterized by the association of ABCB4 mutations and low biliary phospholipid concentration with symptomatic and recurring cholelithiasis. This syndrome is infrequent and corresponds to a peculiar small subgroup of patients with symptomatic gallstone disease. The patients with the LPAC syndrome present typically with the following main features: age less than 40 years at onset of symptoms, recurrence of biliary symptoms after cholecystectomy, intrahepatic hyperechoic foci or sludge or microlithiasis along the biliary tree. Defect in ABCB4 function causes the production of bile with low phospholipid content, increased lithogenicity and high detergent properties leading to bile duct luminal membrane injuries and resulting in cholestasis with increased serum gamma-glutamyltransferase (GGT) activity. Intrahepatic gallstones may be evidenced by ultrasonography (US), computing tomography (CT) abdominal scan or magnetic resonance cholangiopancreatography, intrahepatic hyperechogenic foci along the biliary tree may be evidenced by US, and hepatic bile composition (phospholipids) may be determined by duodenoscopy. In all cases where the ABCB4 genotyping confirms the diagnosis of LPAC syndrome in young adults, long-term curative or prophylactic therapy with ursodeoxycholic acid (UDCA) should be initiated early to prevent the occurrence or recurrence of the syndrome and its complications. Cholecystectomy is indicated in the case of symptomatic gallstones. Biliary drainage or partial hepatectomy may be indicated in the case of symptomatic intrahepatic bile duct dilatations filled with gallstones. Patients with end-stage liver disease may be candidates for liver transplantation
Interfacial Profile and Propagation of Frontal Photopolymerization Waves
We investigate the frontal photopolymerization
of a thiol–ene
system with a combination of experiments and modeling, focusing on
the interfacial conversion profile and its planar wave propagation.
We spatially resolve the solid-to-liquid front by FT-IR and AFM mechanical
measurements, supplemented by differential scanning calorimetry. A
simple coarse-grained model is found to describe remarkably well the
frontal kinetics and the sigmoidal interface, capturing the effects
of UV light exposure time (or dose) and temperature, as well as the
front position and resulting patterned dimensions after development.
Analytical solutions for the conversion profile enable the description
of all conditions with a single master curve in the moving frame of
the front position. Building on this understanding, we demonstrate
the design and fabrication of gradient polymer materials, with tunable
properties <i>along</i> the direction of illumination, which
can be coupled with lateral patterning by modulated illumination or
grayscale lithography
Cholangiocarcinoma 2020: the next horizon in mechanisms and management
| Cholangiocarcinoma (CCA) includes a cluster of highly heterogeneous biliary malignant
tumours that can arise at any point of the biliary tree. Their incidence is increasing globally,
currently accounting for ~15% of all primary liver cancers and ~3% of gastrointestinal malignancies.
The silent presentation of these tumours combined with their highly aggressive nature and
refractoriness to chemotherapy contribute to their alarming mortality, representing ~2% of all
cancer-related deaths worldwide yearly. The current diagnosis of CCA by non-invasive approaches
is not accurate enough, and histological confirmation is necessary. Furthermore, the high
heterogeneity of CCAs at the genomic, epigenetic and molecular levels severely compromises
the efficacy of the available therapies. In the past decade, increasing efforts have been made to
understand the complexity of these tumours and to develop new diagnostic tools and therapies
that might help to improve patient outcomes. In this expert Consensus Statement, which is
endorsed by the European Network for the Study of Cholangiocarcinoma, we aim to summarize
and critically discuss the latest advances in CCA, mostly focusing on classification, cells of origin,
genetic and epigenetic abnormalities, molecular alterations, biomarker discovery and treatments.
Furthermore, the horizon of CCA for the next decade from 2020 onwards is highlighted
Dynamic relocalization of NHERF1 mediates chemotactic migration of ovarian cancer cells toward lysophosphatidic acid stimulation
NHERF1/EBP50 (Na+/H+ exchanger regulating factor 1; Ezrin-binding phosphoprotein of 50 kDa) organizes stable protein complexes beneath the apical membrane of polar epithelial cells. By contrast, in cancer cells without any fixed polarity, NHERF1 often localizes in the cytoplasm. The regulation of cytoplasmic NHERF1 and its role in cancer progression remain unclear. In this study, we found that, upon lysophosphatidic acid (LPA) stimulation, cytoplasmic NHERF1 rapidly translocated to the plasma membrane, and subsequently to cortical protrusion structures, of ovarian cancer cells. This movement depended on direct binding of NHERF1 to C-terminally phosphorylated ERM proteins (cpERMs). Moreover, NHERF1 depletion downregulated cpERMs and further impaired cpERM-dependent remodeling of the cell cortex, suggesting reciprocal regulation between these proteins. The LPA-induced protein complex was highly enriched in migratory pseudopodia, whose formation was impaired by overexpression of NHERF1 truncation mutants. Consistent with this, NHERF1 depletion in various types of cancer cells abolished chemotactic cell migration toward a LPA gradient. Taken together, our findings suggest that the high dynamics of cytosolic NHERF1 provide cancer cells with a means of controlling chemotactic migration. This capacity is likely to be essential for ovarian cancer progression in tumor microenvironments containing LPA
Expert consensus document:Cholangiocarcinoma: current knowledge and future perspectives consensus statement from the European Network for the Study of Cholangiocarcinoma (ENS-CCA)
Cholangiocarcinoma (CCA) is a heterogeneous group of malignancies with features of biliary tract differentiation. CCA is the second most common primary liver tumour and the incidence is increasing worldwide. CCA has high mortality owing to its aggressiveness, late diagnosis and refractory nature. In May 2015, the "European Network for the Study of Cholangiocarcinoma" (ENS-CCA: www.enscca.org or www.cholangiocarcinoma.eu) was created to promote and boost international research collaboration on the study of CCA at basic, translational and clinical level. In this Consensus Statement, we aim to provide valuable information on classifications, pathological features, risk factors, cells of origin, genetic and epigenetic modifications and current therapies available for this cancer. Moreover, future directions on basic and clinical investigations and plans for the ENS-CCA are highlighted
Intrahepatic cholangiocarcinoma: A single-cell resolution unraveling the complexity of the tumor microenvironment
International audienc
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