Assessing identity, phenotype, and fate of endothelial progenitor cells

From the paradigm shifting observations of Harvey, Malpighi, and van Leeuwenhoek, blood vessels have become recognized as distinct and dynamic tissue entities that merge with the heart to form a closed circulatory system.1 Vessel structures are comprised predominantly of a luminal layer of endothelial cells that is surrounded by some form of basement membrane, and mural cells (pericytes or vascular smooth muscle cells) that make up the vessel wall. In larger more complex vessel structures the vessel wall is composed of a complex interwoven matrix with nerve components. Understanding the cellular and molecular basis for the formation, remodeling, repair, and regeneration of the vasculature have been and continue to be popular areas for investigation. The endothelium has become a particularly scrutinized cell population with the recognition that these cells may play important roles in maintaining vascular homeostasis and in the pathogenesis of a variety of diseases.2 Although it has been known for several decades that some shed or extruded endothelial cells enter the circulation as apparent contaminants in the human blood stream,3 only more recent technologies have permitted the identification of not only senescent sloughed endothelial cells,4 but also endothelial progenitor cells (EPCs), which have been purported to represent a normal component of the formed elements of circulating blood5 and play roles in disease pathogenesis.6–9 Most citations refer to an article published in 1997 in which Asahara and colleagues isolated, characterized, and examined the in vivo function of putative EPCs from human peripheral blood as a major impetus for generating interest in the field.10 This seminal article presented some evidence to consider emergence of a new paradigm for the process of neovascularization in the form of postnatal vasculogenesis. Since publication of that article, interest in circulating endothelial cells, and particularly EPCs, has soared, and one merely has to type the keyword search terms, endothelial progenitor cell, to recover more than 8984 articles including 1347 review articles in PubMed (as of June 2008). What can we possibly add in the form of another EPC review that will be considered of significant value for the reader? We will attempt to review some of the early article in the field and reflect on how information in those articles was gradually derivatized into perhaps more conflicting rather than unifying concepts. We will also attempt to concisely address some of the important determinants and principles that are now leading to a new understanding of what functionally constitutes an EPC and outline some of the current measures used to identify, enumerate, and quantify these cells. Finally, we give our opinion of the best definition for an EPC based on some comparative analyses performed primarily in human subjects

Effects of Commercial Diazinon and Imidacloprid on Microbial Urease Activity in Soil and Sod

Diazinon [O,O-diethyl O-2-isopropyl-6-methyl(pyrimidine-4-yl) phosphorothioate] and imidacloprid [1-(1-[6-chloro-3-pyridinyl]methyl)-N-nitro-2-imidazolidinimine] are applied to lawns for insect control simultaneously with nitrogenous fertilizers such as urea, but their potential effect on urease activity and nitrogen availability in turfgrass management has not been evaluated. Urease activity in enzyme assays, washed cell assays, and soil slurries was examined as a function of insecticide concentration. Intact cores from field sites were used to assess the effect of insecticide application on urease activity in creeping bentgrass (Agrostis palustris Huds.) and bluegrass (Poa pratensis L.) sod. Bacterial urease fromBacillus pasteurii and plant urease from jack bean [Canavalia ensiformis (L.) DC.] were unaffected by the insecticides. Both insecticides inhibited the growth of Proteus vulgaris, a urease-producing bacterium, but only diazinon significantly reduced urease activity in washed cells; neither insecticide inhibited urease activity in sonicated cells. Neither diazinon nor imidacloprid inhibited urease activity in Woolper soil (fine, mixed, mesic Typic Argiudoll) slurries, but diazinon slightly inhibited urease activity in Maury soil (fine, mixed, semiactive, mesic Typic Paleudalf) slurries. Imidacloprid had no effect on urease activity in creeping bentgrass or bluegrass sod at up to 10 times the commercial application rate. Diazinon briefly, but significantly, reduced urease activity in bluegrass sod. Co-application of imidacloprid and urea appears to be benign with respect to urease activity in soil and sod. Diazinon, in contrast, appears to have a significant, short-term, inhibitory effect on the microbial urease-producing community, but that effect depends on soil type

Effects of Commercial Diazinon and Imidacloprid on Microbial Urease Activity in Soil and Sod

Diazinon [O,O-diethyl O-2-isopropyl-6-methyl(pyrimidine-4-yl) phosphorothioate] and imidacloprid [1-(1-[6-chloro-3-pyridinyl]methyl)-N-nitro-2-imidazolidinimine] are applied to lawns for insect control simultaneously with nitrogenous fertilizers such as urea, but their potential effect on urease activity and nitrogen availability in turfgrass management has not been evaluated. Urease activity in enzyme assays, washed cell assays, and soil slurries was examined as a function of insecticide concentration. Intact cores from field sites were used to assess the effect of insecticide application on urease activity in creeping bentgrass (Agrostis palustris Huds.) and bluegrass (Poa pratensis L.) sod. Bacterial urease fromBacillus pasteurii and plant urease from jack bean [Canavalia ensiformis (L.) DC.] were unaffected by the insecticides. Both insecticides inhibited the growth of Proteus vulgaris, a urease-producing bacterium, but only diazinon significantly reduced urease activity in washed cells; neither insecticide inhibited urease activity in sonicated cells. Neither diazinon nor imidacloprid inhibited urease activity in Woolper soil (fine, mixed, mesic Typic Argiudoll) slurries, but diazinon slightly inhibited urease activity in Maury soil (fine, mixed, semiactive, mesic Typic Paleudalf) slurries. Imidacloprid had no effect on urease activity in creeping bentgrass or bluegrass sod at up to 10 times the commercial application rate. Diazinon briefly, but significantly, reduced urease activity in bluegrass sod. Co-application of imidacloprid and urea appears to be benign with respect to urease activity in soil and sod. Diazinon, in contrast, appears to have a significant, short-term, inhibitory effect on the microbial urease-producing community, but that effect depends on soil type

SiNx:Tb3+--Yb3+, an efficient down-conversion layer compatible with a silicon solar cell process

SiN x : Tb 3+-Yb 3+, an efficient down-conversion layer compatible with silicon solar cell process Abstract Tb 3+-Yb 3+ co-doped SiN x down-conversion layers compatible with silicon Photovoltaic Technology were prepared by reactive magnetron co-sputtering. Efficient sensitization of Tb 3+ ions through a SiN x host matrix and cooperative energy transfer between Tb 3+ and Yb 3+ ions were evidenced as driving mechanisms of the down-conversion process. In this paper, the film composition and microstructure are investigated alongside their optical properties, with the aim of maximizing the rare earth ions incorporation and emission efficiency. An optimized layer achieving the highest Yb 3+ emission intensity was obtained by reactive magnetron co-sputtering in a nitride rich atmosphere for 1.2 W/cm${}^2$ and 0.15 W/cm${}^2$ power density applied on the Tb and Yb targets, respectively. It was determined that depositing at 200 {\textdegree}C and annealing at 850 {\textdegree}C leads to comparable Yb 3+ emission intensity than depositing at 500 {\textdegree}C and annealing at 600 {\textdegree}C, which is promising for applications toward silicon solar cells.Comment: Solar Energy Materials and Solar Cells, Elsevier, 201

Organising Collective Action for Effective Environmental Management and Social Learning in Wales

The paper explored key factors that might lead to successful agri-environmental social learning and collective action in order to deliver landscape-scale resource management within agri-environment schemes. Using the theory of collective action as an analytical framework the paper examined findings from in-depth interviews with 20 members of two co-operative initiatives in Wales and two participatory workshops. Consideration of the theory helped in understanding how individuals come together to provide public goods, and the conditions that make this activity a success. Factors of importance for organising and delivering collective agri-environment schemes were: locally adaptable engagement strategies; working with group members previously known to each other; institutional arrangements that limited group size and which allowed groups to develop their own solutions and implementation rules; and external support offering the services of a local facilitator and funding for both planning and management stages. A clear finding from the research was the extent to which both business and social confidence can grow within such groups which opens up further development opportunities. The paper identifies key factors that could be used to encourage and enhance the success of co-operative groups in delivering landscape-scale agri-environment schemes. The research findings identify appropriate mechanisms for the design and delivery of collective agri-environment schemes and environment management in the UK, which can also be applied to other parts of Europe

Reconstruction Control of Magnetic Properties during Epitaxial Growth of Ferromagnetic Mn_3-δGa on Wurtzite GaN(0001)

Binary ferromagnetic Mn_3-δGa (1.2<3-δ≤1.5) crystalline thin films have been epitaxially grown on wurtzite GaN(0001) surfaces using rf N-plasma molecular beam epitaxy. The film structure is face-centered tetragonal with CuAu type-I (L1_0) ordering with (111) orientation. The in-plane epitaxial relationship to GaN is nearly ideal with [11̅ 0]_MnGa∥[11̅ 00]_GaN and [112̅ ]_MnGa∥[112̅ 0]_GaN. We observe magnetic anisotropy along both the in-plane and out-of-plane directions. The magnetic moments are found to depend on the Mn/(Mn+Ga) flux ratio and can be controlled by observation of the surface reconstruction during growth, which varies from 1×1 to 2×2 with increasing Mn stoichiometry

Collective Action for Effective Environmental Management and Social Learning in Wales

Increasingly it is recognised that land management at a landscape‐scale can deliver greater public good benefits than at the individual farm scale. Collective agri‐environment schemes are one mechanism for achieving this land management, but such schemes are in the early stages of development in the UK and uncertainty exists as to their appropriate design and delivery. This paper is based on two research projects undertaken in Wales to identify key factors that might lead to successful agri‐environmental co‐operation. The research involved in‐depth analysis of three existing farmer co‐operatives in Wales, including face to face interviews and participatory workshops. Using the theory of collective action as an analytical framework, the paper identifies key factors that could be used to encourage and enhance the success of co‐operative groups in delivering landscape‐scale schemes. Of importance were: locally adaptable engagement strategies; working with group members previously known to each other; institutional arrangements that limited group size and which allowed groups to develop their own solutions and implementation rules; and external support offering the services of a local facilitator and funding for both planning and management stages. A clear finding from the research was the extent to which both business and social confidence can grow within such groups which opens up further development opportunities. Improving the farming community’s capacity to co‐operate will have far‐reaching benefits for all public good provision and diversification activities

An analysis of civil aviation industry safety needs for the introduction of liquid hydrogen propulsion technology

Over the next few decades air travel is predicted to grow, with international agencies, manufacturers and governments predicting a considerable increase in aviation use. However, based on current fuel type, International Civil Aviation Organization (ICAO) project emissions from aviation are estimated to be seven to ten times higher in 2050 than in 1990. These conflicting needs are problematic and have led to the EU Flightpath 2050 targeting dramatic emissions reductions for the sector (75% CO2, 90% NOX by 2050). One proposed solution, decreasing carbon emissions without stunting the increase in air travel, is hydrogen propulsion; a technology with clear environmental benefits. However, enabling the safe application of this fuel to aviation systems and industrial infrastructure would be a significant challenge. High-profile catastrophic incidents involving hydrogen, and the flammable and cryogenic nature of liquid hydrogen (LH2) have led to its reputation as a more dangerous substance than existing or alternative fuels. But, where they are used (in industry, transport, energy), with sufficient protocols, hydrogen can have a similar level of safety to other fuels. A knowledge of hazards, risks and the management of these becomes key to the integration of any new technology. Using assessments, and a gap analysis approach, this paper examines the civil aviation industry requirements, from a safety perspective, for the introduction of LH2 fuel use. Specific proposed technology assessments are used to analyze incident likelihood, consequence impact, and ease of remediation for hazards in LH2 systems, and a gap analysis approach is utilized to identify if existing data is sufficient for reliable technology safety assessment. Outstanding industry needs are exposed by both examining challenges that have been identified in transport and industrial areas, and by identifying the gaps in current knowledge that are preventing credible assessment, reliable comparison to other fuels and the development of engineering systems. This paper demonstrates that while hydrogen can be a safe and environmentally friendly fuel option, a significant amount of work is required for the implementation of LH2 technology from a mass market perspective

Thin-film hermeticity: A quantitative analysis of diamond-like carbon using variable angle spectroscopic ellipsometry

The purpose of this paper is twofold. First, we report on the successful application of variable angle spectroscopic ellipsometry to quantitative thin-film hermeticity evaluation. Secondly, it is shown that under a variety of film preparations and moisture introduction conditions water penetrates only a very thin diamondlike carbon (DLC) top surface-roughness region. Thus DLC is an excellent candidate for use as protective coatings in adverse chemical and aqueous environments