2,223 research outputs found
Wettability of amorphous and nanocrystalline Fe78B13Si9 substrates by molten Sn and Bi
The wettability of amorphous and annealing-induced nanocrystalline Fe78B13Si9 ribbons by molten Sn and Bi at 600 K was measured using an improved sessile drop method. The results demonstrate that the structural relaxation and crystallization in the amorphous substrates do not substantially change the wettability with molten Bi because of their invariable physical interaction, but remarkably deteriorate the wettability and interfacial bonding with molten Sn as a result of changing a chemical interaction to a physical one for the atoms at the interface
Carvacrol, (-)-borneol and citral reduce convulsant activity in rodents
Carvacrol, a monoterpenic phenol present in essential oils of the Labiatae family, has been used through the ages as a source of flavor in food and for medicinal purposes. Borneol is a monoterpene found in several species of Artemisia and Dipterocarpaceae, used for anxiety, pain and anesthesia in traditional Chinese. Citral, a mixture of two geometrical isomers (neral and geranial), is one of the most important compounds in some citrus oils and has central nervous system (CNS) properties. The anticonvulsant effect of carvacrol (CARV), (-)-borneol (BOR) and citral (CIT) was investigated in two animal models of epilepsy. Mice were pretreated with CARV, BOR or CIT (50, 100, and 200 mg/kg, i.p.) 30 min before pentylenetetrazole (PTZ) or maximal electroshock (MES) tests, the two most important animal epilepsy tests. The latency for development of convulsions and protection percentage was recorded. In order to investigate the involvement of GABAergic system, flumazenil was utilized. These monoterpenes, CARV in a higher, but not in a lower dose (p < 0.001), BOR and CIT in all doses (p < 0.05 or p < 0.001), were capable of promoting an increase of latency for the development of convulsions induced by PTZ. Additionally, these compounds were efficient in preventing the tonic convulsions (p < 0.05) induced by MES. However, the GABAergic neurotransmitter system might be involved, at least in BOR effects. Henceforth, our results suggest that CARV, BOR and CIT possess anticonvulsant activity effect against PTZ-induced convulsions and MES.Key words: Carvacrol, (-)-borneol, citral, anticonvulsant activit
Influence of different beverages on the force degradation of intermaxillary elastics: an in vitro study
OBJECTIVE: The aim of this study was to evaluate in vitro the effects of frequently ingested beverages on force degradation of intermaxillary elastics. MATERIAL AND METHODS: One hundred and eighty 1/4-inch intermaxillary elastics (TP Orthodontics) were immersed into six different beverages: (1) Coca-Cola(®); (2) Beer; (3) Orange juice; (4) Red wine; (5) Coffee and (6) artificial saliva (control). The period of immersion was 15 min for the first and second cycles and 30 min for the third to fifth cycles. Tensile forces were read in a tensile testing machine before and after the five immersion cycles. One-way repeated measures ANOVA was used to identify significant differences. RESULTS: Force degradation was seen in all evaluated groups and at all observation periods (p<0.05). A greater degree of degradation was present at the initial periods, decreasing gradually over time. However, no statistically significant differences were seen among groups at the same periods, showing that different groups behaved similarly. CONCLUSION: The chemical nature of the evaluated beverages was not able to influence the degree of force degradation at all observation periods
Mitochondrial echoes of first settlement and genetic continuity in El Salvador
Background: From Paleo-Indian times to recent historical episodes, the Mesoamerican isthmus played an important role in the distribution and patterns of variability all around the double American continent. However, the amount of genetic information currently available on Central American continental populations is very scarce. In order to shed light on the role of Mesoamerica in the peopling of the New World, the present study focuses on the analysis of the mtDNA variation in a population sample from El Salvador.
Methodology/Principal Findings: We have carried out DNA sequencing of the entire control region of the mitochondrial DNA (mtDNA) genome in 90 individuals from El Salvador. We have also compiled more than 3,985 control region profiles from the public domain and the literature in order to carry out inter-population comparisons. The results reveal a predominant Native American component in this region: by far, the most prevalent mtDNA haplogroup in this country (at ~90%) is A2, in contrast with other North, Meso- and South American populations. Haplogroup A2 shows a star-like phylogeny and is very diverse with a substantial proportion of mtDNAs (45%; sequence range 16090–16365) still unobserved in other American populations. Two different Bayesian approaches used to estimate admixture proportions in El Salvador shows that the majority of the mtDNAs observed come from North America. A preliminary founder analysis indicates that the settlement of El Salvador occurred about 13,400±5,200 Y.B.P.. The founder age of A2 in El Salvador is close to the overall age of A2 in America, which suggests that the colonization of this region occurred within a few thousand years of the initial expansion into the Americas.
Conclusions/Significance: As a whole, the results are compatible with the hypothesis that today's A2 variability in El Salvador represents to a large extent the indigenous component of the region. Concordant with this hypothesis is also the observation of a very limited contribution from European and African women (~5%). This implies that the Atlantic slave trade had a very small demographic impact in El Salvador in contrast to its transformation of the gene pool in neighbouring populations from the Caribbean facade
Correlating structural dynamics and catalytic activity of AgAu nanoparticles with ultrafast spectroscopy and all-atom molecular dynamics simulations
In this study, we investigated hollow AgAu nanoparticles with the goal of improving our understanding of the compositiondependent catalytic activity of theses nanoparticles. AgAu nanoparticles were synthesized via the galvanic replacement method with controlled size and nanoparticle compositions. We studied extinction spectra with UV-Vis spectroscopy and simulations based on Mie theory and the boundary element method, and ultrafast spectroscopy measurements to characterize decay constants and the overall energy transfer dynamics as a function of AgAu composition. Electronphonon coupling times for each composition were obtained from pump-power dependent pump-probe transients. These spectroscopic studies showed how nanoscale surface segregation, hollow interiors and porosity affect the surface plasmon resonance wavelength and fundamental electron-phonon coupling times. Analysis of the spectroscopic data was used to correlate electron-phonon coupling times to AgAu composition, and thus to surface segregation and catalytic activity. We have performed all-atom molecular dynamics simulations of model hollow AgAu core-shell nanoparticles to characterize nanoparticle stability and equilibrium structures, besides providing atomic level views of nanoparticle surface segregation. Overall, the basic atomistic and electron-lattice dynamics of core-shell AgAu nanoparticles characterized here thus aid the mechanistic understanding and performance optimization of AgAu nanoparticle catalysts
Inhaled tobramycin solution-associated recurrent eosinophilia and severe persistent bronchospasm in a patient with cystic fibrosis: a case report
BACKGROUND: Delivery of tobramycin by inhalation to the lungs of patients with cystic fibrosis (CF) who are infected with Pseudomonas aeruginosa has been proven to be effective and safe. The aerosol administration allows high concentrations of tobramycin to be delivered to the site of infection with limited systemic absorption. In rare patients, systemic absorption of inhaled tobramycin may be significant enough to produce toxic effects, such as renal and vestibular toxicities. CASE PRESENTATION: We report a patient with CF who developed recurrent eosinophilia and severe persistent bronchospasm following repeated administration of preservative-free tobramycin by inhalation, beginning at 16 months of age. Also, he developed similar signs and symptoms when he was administered tobramycin intravenously on one occasion at 5 1/2 years. The patient had a history of environmental allergies. Temporal sequence of his signs and symptoms after each administration of tobramycin (similar to re-challenge testing), and his improvement after discontinuation of the drug strongly suggest an adverse drug reaction. CONCLUSION: Hypersensitivity reaction should be considered in patients who develop recurrent eosinophilia and deterioration of pulmonary function following the use of tobramycin by inhalation or by intravenous administration
Detection of atherosclerotic cardiovascular disease influences the perceived need for aggressive lipid management
Background and aims Overt atherosclerotic cardiovascular disease (ASCVD) warrants aggressive lipid lowering. Imaging for ambiguous symptoms suggesting ischemia or for clarification of CV risk in asymptomatic individuals often uncovers previously unknown ASCVD. Guidelines do not provide clear recommendations for aggressive lipid lowering in such cases. We explored physicians' perception, as influenced by tests that detect ASCVD, regarding appropriateness of getting to lipid goals and for theoretically accessing proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i). Methods A questionnaire was developed including cases of low to high CV risk, chronic kidney disease (CKD) or type 2 diabetes mellitus (T2DM). Each case was considered with or without angina symptoms and, in turn, whether testing identified previously unknown advanced, early/subclinical or no ASCVD. Synthesis of responses was facilitated by using a scale for perceived appropriateness from 1 (lowest) to 9 (highest). Results Getting to goal and, if not achieved by statins and/or ezetimibe, accessing PCSK9i was considered appropriate in patients with T2DM with preclinical or advanced ASCVD, patients with moderate or high CV risk and advanced ASCVD, patients with CKD or low CV risk with angina symptoms and advanced ASCVD. For most of the remaining cases adding PCSK9i was considered only possibly appropriate. Conclusions Physicians' perception of appropriateness for achieving lipid goals, including access to PCSK9i, is markedly influenced by detection of previously unknown ASCVD. Since these commonly encountered scenarios do not clearly meet current indications for PCSK9i, our data identify pressing areas requiring further research
Non-L\'evy mobility patterns of Mexican Me'Phaa peasants searching for fuelwood
We measured mobility patterns that describe walking trajectories of
individual Me'Phaa peasants searching and collecting fuelwood in the forests of
"La Monta\~na de Guerrero" in Mexico. These one-day excursions typically follow
a mixed pattern of nearly-constant steps when individuals displace from their
homes towards potential collecting sites and a mixed pattern of steps of
different lengths when actually searching for fallen wood in the forest.
Displacements in the searching phase seem not to be compatible with L\'evy
flights described by power-laws with optimal scaling exponents. These findings
however can be interpreted in the light of deterministic searching on heavily
degraded landscapes where the interaction of the individuals with their scarce
environment produces alternative searching strategies than the expected L\'evy
flights. These results have important implications for future management and
restoration of degraded forests and the improvement of the ecological services
they may provide to their inhabitants.Comment: 15 pages, 4 figures. First version submitted to Human Ecology. The
final publication will be available at http://www.springerlink.co
The decay Bs -> mu+ mu-: updated SUSY constraints and prospects
We perform a study of the impact of the recently released limits on BR(Bs ->
mu+ mu-) by LHCb and CMS on several SUSY models. We show that the obtained
constraints can be superior to those which are derived from direct searches for
SUSY particles in some scenarios, and the use of a double ratio of purely
leptonic decays involving Bs -> mu+ mu- can further strengthen such
constraints. We also discuss the experimental sensitivity and prospects for
observation of Bs -> mu+ mu- during the sqrt(s)=7 TeV run of the LHC, and its
potential implications.Comment: 30 pages, 21 figures. v2: Improved discussion of constraints from B
-> tau nu, references adde
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