117,422 research outputs found
Production of PCL nanoparticles by flash nanoprecipitation for controlled release of caffeine
No full textCaffeine (CAF) is one of the most consumed drug worldwide due to its large application in food, pharmaceuticals, cosmetics and supplements; upon oral administration caffeine is cleared into the stomach in 20 minutes and absorbed into the blood within 1 hour [1]. Polycaprolactone (PCL) is biodegradable polymer extensively studied in drug delivery applications where long lasting releases are required [2]. Caffeine was encapsulated in PCL nanoparticles by exploiting the Flash nano-precitation technique which is well known method to encapsulate hydrophobic dru[3], but not yet studied on hydrophilic active principles. The nanoparticles were produced in a confined impinging jet mixer by dissolving caffeine alternatively in the solvent (acetone or in the antisolvent (water). The effect of the process parameters on the mean particle diameter and zeta potential of the nanoparticles was investigated by Dynamic Light Scattering. A novel methodology to accurately quantify drug Loading Capacity (LC) and Encapsulation Efficiency was studied and implemented. The in vitro release kinetic was assessed by dynamic dialysis method. Nanoparticle with average diameter ranging from 250 to 500 nm were successfully produced, the mean size was correlated to the flow rate. LC and EE were assessed in the range of 10-45% and 5-25% respectively. The release test showed a 1st order kinetic with a peak of caffeine in blood mimicking solution delayed to 6 hours
Relationship between oxygen content of graphene and mechanical properties of cement-based composites
No full textCement composites were realized containing graphene-based materials having different oxygen content (from 0 to 45%). It was found that the polarity of the reinforcement influences both the dispersion in water and the chemical interaction with the hydrated cement matrix, and thus the mechanical performance of the composites. In particular, the reinforcements with the highest oxygen content result aggregated while the cement with the highest strength is obtained with functionalized graphene, containing 5% oxygen, where the surface has sufficient polar groups to guarantee proper dispersion and interaction with the hydrated cement
Confocal microscopy of the skin in the diagnosis of X-linked Alport syndrome
No full textNo abstract availabl
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Low infra red laser light irradiation on cultured neural cells: effects on mitochondria and cell viability after oxidative stress
No full textAbstract Background Considerable interest has been aroused in recent years by the well-known notion that biological systems are sensitive to visible light. With clinical applications of visible radiation in the far-red to near-infrared region of the spectrum in mind, we explored the effect of coherent red light irradiation with extremely low energy transfer on a neural cell line derived from rat pheochromocytoma. We focused on the effect of pulsed light laser irradiation vis-à-vis two distinct biological effects: neurite elongation under NGF stimulus on laminin-collagen substrate and cell viability during oxidative stress. Methods We used a 670 nm laser, with extremely low peak power output (3 mW/cm2) and at an extremely low dose (0.45 mJ/cm2). Neurite elongation was measured over three days in culture. The effect of coherent red light irradiation on cell reaction to oxidative stress was evaluated through live-recording of mitochondria membrane potential (MMP) using JC1 vital dye and laser-confocal microscopy, in the absence (photo bleaching) and in the presence (oxidative stress) of H2O2, and by means of the MTT cell viability assay. Results We found that laser irradiation stimulates NGF-induced neurite elongation on a laminin-collagen coated substrate and protects PC12 cells against oxidative stress. Conclusion These data suggest that red light radiation protects the viability of cell culture in case of oxidative stress, as indicated by MMP measurement and MTT assay. It also stimulates neurite outgrowth, and this effect could also have positive implications for axonal protection.</p
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
Gabapentin treatment improves motor coordination in a mice model of progressive ataxia.
No full textNo causal treatment of ataxias is available at the moment, and so symptomatic and disease-modifying therapies are regarded as a reliable possibility for this complex group of movement disorders. In order to explore possible pharmacological strategies aimed at interfering with ataxia development or progression, we used HCN1-/- mice. Mice carrying the deletion of the gene encoding for the voltage-dependent K-channel (HCN1-/-) have a normal basic motor function, but impaired learning of the motor skills that enable mice to balance on the rotating rod. In this study we showed that the motor coordination impairment observed in HCN1-/- mice is paralleled by a decline of GABA content in the cerebellum. Treatment with the GABA mimetic gabapentin at prenatal age prevents full development of the ataxia symptom. This result could have implications for possible therapeutic strategies aimed at more effective coupling with ataxia in several neurological diseases in which this symptom develops and is prominent over time. In view of its long-lasting effect, it could be also considered as a disease-modifying drug
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