Tracking mesenchymal stem cells with iron oxide nanoparticle loaded poly(lactide-co-glycolide) microparticles

Monitoring the location, distribution and long-term engraftment of administered cells is critical for demonstrating the success of a cell therapy. Among available imaging-based cell tracking tools, magnetic resonance imaging (MRI) is advantageous due to its noninvasiveness, deep penetration, and high spatial resolution. While tracking cells in preclinical models via internalized MRI contrast agents (iron oxide nanoparticles, IO-NPs) is a widely used method, IO-NPs suffer from low iron content per particle, low uptake in nonphagocytotic cell types (e.g., mesenchymal stem cells, MSCs), weak negative contrast, and decreased MRI signal due to cell proliferation and cellular exocytosis. Herein, we demonstrate that internalization of IO-NP (10 nm) loaded biodegradable poly(lactide-co-glycolide) microparticles (IO/PLGA-MPs, 0.4-3 μm) in MSCs enhances MR parameters such as the r(2) relaxivity (5-fold), residence time inside the cells (3-fold) and R(2) signal (2-fold) compared to IO-NPs alone. Intriguingly, in vitro and in vivo experiments demonstrate that internalization of IO/PLGA-MPs in MSCs does not compromise inherent cell properties such as viability, proliferation, migration and their ability to home to sites of inflammation.     

Iron chalcogenide superconductors at high magnetic fields

Iron chalcogenide superconductors have become one of the most investigated superconducting materials in recent years due to high upper critical fields, competing interactions and complex electronic and magnetic phase diagrams. The structural complexity, defects and atomic site occupancies significantly affect the normal and superconducting states in these compounds. In this work we review the vortex behavior, critical current density and high magnetic field pair-breaking mechanism in iron chalcogenide superconductors. We also point to relevant structural features and normal-state properties.     

An analysis of silver candlesticks from a casting point of view： originals, copies, forgeries

Collecting silver artefacts has traditionally been a very popular hobby.Silver is addictive,therefore the number of potential collectors and investors appears to grow each year.Unfortunately,increases in the interest and buying potentials resulted in a number of forgeries manufactured and introduced to the open antique market.The items such as early silver candlesticks dictate a very high price,for many high quality fakes show very good appearances and matching similarities with originals.Such copies are tr...     

Life-long learning for psychologists: Current status and a vision for the future.

As a profession we are committed to maintaining and enhancing our competence as psychologists in order to most effectively serve the public throughout our careers. While this is a widely shared commitment among psychologists, there is considerably less consensus regarding how best to accomplish this goal. This dilemma is examined from the ethical, educational and legal perspectives. The American Psychological Association (APA) Ethics Code clearly articulates that competence is an ethical duty, although there is little guidance provided in the code as to how to meet this standard. As a profession we have tended to focus on the construct of life-long learning and we have incorporated this principle into our education and training standards. In fact, APA accreditation requires that doctoral programs inculcate this value into our foundational training. The majority of Psychology Licensing Boards have addressed this issue through the endorsement of mandatory continuing education requirements that primarily focus on hours and the content or structure of approved programs. Potential limitations to our ability to effectively self-assess our professional training needs are discussed and several innovative models are presented for integrating effective self-assessment and continuing education. Three invited experts provide commentaries that further explore the challenges and dilemmas posed by the ethical, legal and professional duty to maintain and enhance competence throughout our professional careers. These commentaries broaden the considerations, provide practical suggestions from other professions and provide a vision for the future. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The rayleigh range of gaussian schell-model beams

Abstract

The concept of the Rayleigh range, well known in the theory of coherent beams, is generalized to a class of partially coherent beams. Curves are presented which show the dependence of the Rayleigh range on the spot size of the beam and on the spectral degree of coherence of the light in the plane of the waist.     

Propagation of Gaussian Schell-model Beams in Dispersive and Absorbing Media

Abstract

The spectral properties and the coherence properties of Gaussian Schell-model beams, propagating in dispersive and absorbing media, are discussed. Unlike in free space, the ratio of the transverse spectral correlation length to the beam width is found to increase on propagation. Consequently upon propagation the beam becomes spatially more coherent at each frequency. Numerical results for the spectrum and for the degrees of spectral and of temporal coherence of the field are presented for some selected values of the beam parameters and for several values of the propagation distance. Propagation in a gain medium is also briefly discussed.     

Modeling and Prediction of Two-Phase Microgap Channel Heat Transfer Characteristics

A detailed analysis of microchannel/microgap heat transfer data for two-phase flow of refrigerants and dielectric liquids, gathered from the open literature and sorted by the Taitel and Dukler flow regime mapping methodology, is performed. Annular flow is found to be the dominant regime for this thermal transport configuration and to grow in importance with decreasing channel diameter. A characteristic M-shaped heat transfer coefficient variation with quality (or superficial velocity) for the flow of refrigerants and dielectric liquids in miniature channels is identified. The inflection points in this M-shaped curve are seen to equate approximately with flow regime transitions, including a first maximum at the transition from Bubble to Intermittent flow and a second maximum at moderate qualities in Annular flow, just before local dryout begins. The predictive accuracy of five classical two-phase heat transfer correlations for miniature channel flow is examined. Selecting the best fitting of the classical correlations for each of the flow regime categories is seen to yield predictive agreement with regime-sorted heat transfer coefficients that does not depart significantly from the agreement found in large pipes and channels.     

High-throughput approach to the catalytic combustion of diesel soot

A methodology for the evaluation of diesel soot oxidation catalysts by high-throughput (HT) screening was developed. The optimal experimental conditions (soot amount, catalyst/soot ratio, type of contact, composition and flow rate of gas reactants) ensuring a reliable and reproducible detection of light-off temperatures in a 16 parallel channels reactor were set up. The temperature profile measured in the catalyst/soot bed under TPO conditions when the exothermic combustion of soot takes place was shown to provide an accurate measurement of the ignition. Its reproducibility and relevance were checked. The results obtained with a reference noble metal free catalyst (La_0.8Cr_0.8Li_0.2O₃ perovskite) agree very well with literature data. Qualitative mechanistic features could be derived from these experiments, stressing the likely limiting step of oxygen transfer from catalyst surface to soot particulates to ignite the soot combustion. Ceria material was shown to be more appropriate than perovskite one. From an HT screening of a large diverse library (over 100 mixed oxides catalysts) under optimized conditions, about 10 new formulations were found to perform better than selected noble metal free reference materials.     

Screening for organic phosphorus compounds in aquatic sediments by liquid chromatography coupled to ICP-AES and ESI-MS/MS

The structures of organic phosphorous (P) compounds in aquatic sediments are to a large extent unknown although these compounds are considered to play an important role in regulating lake trophic status. To enhance identification of these compounds, a liquid chromatography (LC) method for their separation was developed. The stationary phase was porous graphitic carbon (PGC), and the mobile phases used in the gradient elution were compatible with both inductive coupled plasma atomic emission spectroscopy (ICP-AES) and electrospray ionization tandem mass spectrometry (ESI-MS/MS). With LC-ICP-AES, eight different P containing peaks could be observed in the P chromatogram indicating that at least eight different P compounds were separated. With the setup of an information dependent acquisition (IDA) with ESI-MS/MS, the mass over charge ( m/ z) of compounds containing a phosphate group (H 2PO 3 (-), m/ z 97) could be measured and further fragmentation experiments gave additional information on the structure of almost 40 separated P compounds, several were verified to be nucleotides. ICP-AES was very suitable in the development of the LC method and allowed screening and quantification of P compounds. The presented LC-ESI-MS/MS technique was able to identify several sediment organic P compounds.