971 research outputs found
Reactions of some metal ions with certain Schiff bases and their precursors
Schiff base complexes with two or three nitrogen
donor atoms have recently attracted interest in virtue of
their biological activity. 2,6-Pyridinedicarboxaldehyde
lends itself to the formation of a host of such Schiff
bases. The present work has therefore been devoted to
the investigation of the synthesis and reactions of
Schiff bases derived from 2,6-pyridinedicarboxaldehyde. (...continues
Impaired neurodevelopment by the low complexity domain of CPEB4 reveals a convergent pathway with neurodegeneration
CPEB4 is an RNA binding protein expressed in neuronal tissues including brain and spinal cord. CPEB4 has two domains: one that is structured for RNA binding and one that is unstructured and low complexity that has no known function. Unstructured low complexity domains (LCDs) in proteins are often found in RNA-binding proteins and have been implicated in motor neuron degenerative diseases such as amyotrophic lateral sclerosis, indicating that these regions mediate normal RNA processing as well as pathological events. While CPEB4 null knockout mice are normal, animals expressing only the CPEB4 LCD are neonatal lethal with impaired mobility that display defects in neuronal development such as reduced motor axon branching and abnormal neuromuscular junction formation. Although full-length CPEB4 is nearly exclusively cytoplasmic, the CPEB4 LCD forms nucleolar aggregates and CPEB4 LCD-expressing animals have altered ribosomal RNA biogenesis, ribosomal protein gene expression, and elevated levels of stress response genes such as the actin-bundling protein DRR1, which impedes neurite outgrowth. Some of these features share similarities with other LCD-related neurodegenerative disease. Most strikingly, DRR1 appears to be a common focus of several neurodevelopmental and neurodegenerative disorders. Our study reveals a possible molecular convergence between a neurodevelopmental defect and neurodegeneration mediated by LCDs
Domain walls at the spin density wave endpoint of the organic superconductor (TMTSF)2PF6 under pressure
We report the first comprehensive investigation of the organic superconductor
(TMTSF)2PF6 in the vicinity of the endpoint of the spin density wave - metal
phase transition where phase coexistence occurs. At low temperature, the
transition of metallic domains towards superconductivity is used to reveal the
various textures. In particular, we demonstrate experimentally the existence of
1D and 2D metallic domains with a cross-over from a filamentary
superconductivity mostly along the c?-axis to a 2D superconductivity in the
b?c-plane perpendicular to the most conducting direction. The formation of
these domain walls may be related to the proposal of a soliton phase in the
vicinity of the critical pressure of the (TMTSF)2PF6 phase diagram.Comment: 5 page
Upper critical field divergence induced by mesoscopic phase separation in the organic superconductor (TMTSF)2ReO4
Due to the competition of two anion orders, (TMTSF)2ReO4, presents a phase
coexistence between semiconducting and metallic (superconducting) regions
(filaments or droplets) in a wide range of pressure. In this regime, the
superconducting upper critical field for H parallel to both c* and b' axes
present a linear part at low fields followed by a divergence above a cross-over
field. This cross-over corresponds to the 3D-2D decoupling transition expected
in filamentary or granular superconductors. The sharpness of the transition
also demonstrates that all filaments are of similar sizes and self organize in
a very ordered way. The distance between the filaments and their cross-section
are estimated.Comment: 4 pages, 4 figure
Lung protection in cardio-pulmonary bypass
Since the invention of the heart-lung machine paediatric cardiac surgery
developed rapidly. For correction of complex cardiac malformations the
application of a cardio-pulmonary bypass (CPB) has become indispensable but
possible negative effects of this technique should not be neglected.
Especially, both bypassed organs i.e. heart and lung are not perfused during
the procedure and therefore are threatened by ischemia and reperfusion injury.
Additionally, CPB was developed with a non-pulsatile flow but there are
clinical observations that pulsatile flow might be superior with improved
patient outcomes. Thus, the aim of our study was to evaluate the effect of CPB
on lung structure and to assess whether different flow modalities (pulsatile
vs. non-pulsatile flow) or application of the antibiotic minocycline might be
advantageous. Thirty five piglets of four weeks age were examined and divided
into five experimental groups: control (no CPB) without or with minocycline,
CPB (non-pulsatile flow) without or with minocycline and CPB with pulsatile
flow. CPB was performed for 90 min followed by a 120 min reperfusion and
recovery phase. Thereafter, adenosine triphosphate-content of lung biopsies
and histology was carried out. We found that CPB was associated with a
significant thickening of alveolar wall accompanied by an infiltration of
neutrophil leucocytes. Moreover, markers for hypoxia, apoptosis, nitrosative
stress, inflammation and DNA damage were significantly elevated after CPB.
These cellular damages could be partially inhibited by minocycline or
pulsatile flow. Both, minocycline and pulsatile flow attenuate lung damage
after CPB
Charge Order Breaks Magnetic Symmetry in Molecular Quantum Spin Chains
Charge order affects most of the electronic properties but is believed not to
alter the spin arrangement since the magnetic susceptibility remains unchanged.
We present electron-spin-resonance experiments on quasi-one-dimensional
(TMTTF)2X salts (X= PF6, AsF6 and SbF6), which reveal that the magnetic
properties are modified below TCO when electronic ferroelectricity sets in. The
coupling of anions and organic molecules rotates the g-tensor out of the
molecular plane creating magnetically non-equivalent sites on neighboring
chains at domain walls. Due to anisotropic Zeeman interaction a novel magnetic
interaction mechanism in the charge-ordered state is observed as a doubling of
the rotational periodicity of Delta H.Comment: 9 pages, 13 figure
Adverse drug events associated with vitamin K antagonists: factors of therapeutic imbalance
Nancy El-Helou, Amal Al-Hajje, Rola Ajrouche, Sanaa Awada, Samar Rachidi, Salam Zein, Pascale SalamehClinical and Epidemiological Research Laboratory, Faculty of Pharmacy, Lebanese University, Beirut, LebanonBackground: Adverse drug events (ADE) occur frequently during treatment with vitamin K antagonists (AVK) and contribute to increase hemorrhagic risks.Methods: A retrospective study was conducted over a period of 2 years. Patients treated with AVK and admitted to the emergency room of a tertiary care hospital in Beirut were included. The aim of the study was to identify ADE characterized by a high international normalized ratio (INR) and to determine the predictive factors responsible for these events. Statistical analysis was performed with the SPSS statistical package.Results: We included 148 patients. Sixty-seven patients (47.3%) with an INR above the therapeutic range were identified as cases. The control group consisted of 81 patients (54.7%) with an INR within the therapeutic range. Hemorrhagic complications were observed in 53.7% of cases versus 6.2% of controls (P < 0.0001). No significant difference was noticed between cases and controls regarding the indication and the dose of AVK. Patients aged over 75 years were more likely to present an INR above the therapeutic range (58.2%, P = 0.049). Recent infection was present in 40.3% of cases versus 6.2% of controls (P < 0.0001) and hypoalbuminemia in 37.3% of cases versus 6.1% of controls (P < 0.0001). Treatment with antibiotics, amiodarone, and anti-inflammatory drugs were also factors of imbalance (P < 0.0001).Conclusion: Many factors may be associated with ADE related to AVK. Monitoring of INR and its stabilization in the therapeutic range are important for preventing these events.Keywords: adverse drug events, vitamin K antagonists, bleeding risks, therapeutic imbalanc
Insertion Detection System Employing Neural Network MLP and Detection Trees Using Different Techniques
by addressing intruder attacks, network security experts work to maintain services available at all times. The Intrusion Detection System (IDS) is one of the available mechanisms for detecting and classifying any abnormal behavior. As a result, the IDS must always be up to date with the most recent intruder attack signatures to maintain the confidentiality, integrity, and availability of the services. This paper shows how the NSL-KDD dataset may be used to test and evaluate various Machine Learning techniques. It focuses mostly on the NLS-KDD pre-processing step to create an acceptable and balanced experimental data set to improve accuracy and minimize false positives. For this study, the approaches J48 and MLP were employed. The Decision Trees classifier has been demonstrated to have the highest accuracy rate for detecting and categorizing all NSL-KDD dataset attacks
Ab initio studies of electronic structure of defects in PbTe
Understanding the detailed electronic structure of deep defect states in
narrow band-gap semiconductors has been a challenging problem. Recently,
self-consistent ab initio calculations within density functional theory (DFT)
using supercell models have been successful in tackling this problem. In this
paper, we carry out such calculations in PbTe, a well-known narrow band-gap
semiconductor, for a large class of defects: cationic and anionic
substitutional impurities of different valence, and cationic and anionic
vacancies. For the cationic defects, we study a series of compounds
RPb2n-1Te2n, where R is vacancy or monovalent, divalent, or trivalent atom; for
the anionic defects, we study compounds MPb2nTe2n-1, where M is vacancy, S, Se
or I. We find that the density of states (DOS) near the top of the valence band
and the bottom of the conduction band get significantly modified for most of
these defects. This suggests that the transport properties of PbTe in the
presence of impurities can not be interpreted by simple carrier doping
concepts, confirming such ideas developed from qualitative and
semi-quantitative arguments
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