Charge induced enhancement of water adsorption on nanoparticle ions

Water and other polar molecules experience an attractive force in the inhomogeneous electric field of small molecular ions or charged nanoparticles. This charge induced attractive force increases the collision cross section, and, hence, impacts the adsorption rates compared to neutral particle interactions. While ion-molecule interactions have been studied extensively, experimental data are still lacking regarding the interaction of polar molecules with nanoparticles whose radii exceed the Langevin capture radius. Precise knowledge of this effect is crucial, e.g. for describing the formation and growth of atmospheric nanoparticles and for understanding the role of charged particles in cloud formation. We present experimental results for the charge induced enhancement of the collision cross section between H2O molecules and singly charged nanoparticles with radii between 1.4 nm and 3 nm. The enhancement factor Γ with respect to the geometrical cross section increases with decreasing particle size. We also present a new model for Γ based on Stark effect adiabatic dipole orientations, which is in excellent agreement with the experimental findings

Preferential adsorption of para and ortho water molecules on charged nanoparticles in planetary ice clouds

In the Earth mesopause, nanometer-size singly charged particles form by condensation of evaporated meteorite material. Tey exhibit an enhanced water adsorption cross section due to the strong charge-dipole-interaction. In this work, we study how the nuclear spin state of water molecules afects this enhancement and whether there are conditions that could lead to the formation of spin-polarized ice. Due to symmetry constraints on the total molecular wave function, ortho (proton spins parallel) and para (spins antiparallel) water occupy diferent rotational states, resulting in a diferent average dipole orientation in electric felds. Terefore, we expect ortho and para water to exhibit distinct ad- sorption enhancement factors onto charged nanoparticles. Based on Stark-shifs of individual rotational states of water, average dipole orientations of a molecu- lar ensemble and the resulting collision cross section was calculated for various temperatures and particle sizes. We found that in the mesosphere of the Earth (T~150K) the adsorption enhancement of ortho- and para- water is approxi- mately equal while at lower temperatures prevailing around ice giant planets and their moons, signifcant spin polarizations up to 15% occur

Transcriptional Targeting of B Cells for Induction of Peripheral CD8 T Cell Tolerance

Abstract Several mechanisms are in place to neutralize autoimmune CD8 T cells by tolerance induction. Developing self-specific CD8 T cells are eliminated in the thymus by Ag-presenting epithelial and dendritic cells (DCs). However, CD8 T cells escaping thymic central tolerance can also be inactivated by tolerance mechanisms in peripheral organs. In contrast to DCs, the role of B cells in generating CD8 T cell tolerance is not well-characterized. To investigate this question in more detail, we transcriptionally targeted Ag to B cells using B cell-specific retroviral vectors in vivo. Although Ag expression could be detected in B cells of thymus, lymph nodes, and spleen, B cells were unable to induce central tolerance of CD8 thymocytes. In contrast, in peripheral organs, we could identify clonal deletion and functional inhibition (anergy) of CD8 T cells as tolerance-inducing mechanisms. Although Ag expressed by B cells was acquired and cross-presented by DCs, B cells were also sufficient to tolerize CD8 T cells directly. These findings suggest exploitation of B cells for Ag-specific immunotherapy of CD8 T cell-mediated autoimmune diseases

Lentiviral-Mediated Transcriptional Targeting of Dendritic Cells for Induction of T Cell Tolerance In Vivo

Abstract Dendritic cells (DCs) are important APCs able to induce both tolerance and immunity. Therefore, DCs are attractive targets for immune intervention. However, the ex vivo generation and manipulation of DCs at sufficient numbers and without changing their original phenotypic and functional characteristics are major obstacles. To manipulate DCs in vivo, we developed a novel DC-specific self-inactivating lentiviral vector system using the 5′ untranslated region from the DC-STAMP gene as a putative promoter region. We show that a gene therapy approach with these DC-STAMP-lentiviral vectors yields long-term and cell-selective transgene expression in vivo. Furthermore, transcriptionally targeted DCs induced functional, Ag-specific CD4 and CD8 T cell tolerance in vivo, which could not be broken by viral immunization. Tolerized CTL were unable to induce autoimmune diabetes in a murine autoimmune model system. Therefore, delivering transgenes specifically to DCs by using viral vectors might be a promising tool in gene therapy

Modular expression analysis reveals functional conservation between human Langerhans cells and mouse cross-priming dendritic cells

Characterization of functionally distinct dendritic cell (DC) subsets in mice has fueled interest in whether analogous counterparts exist in humans. Transcriptional modules of coordinately expressed genes were used for defining shared functions between the species. Comparing modules derived from four human skin DC subsets and modules derived from the Immunological Genome Project database for all mouse DC subsets revealed that human Langerhans cells (LCs) and the mouse XCR1(+)CD8α(+)CD103(+) DCs shared the class I-mediated antigen processing and cross-presentation transcriptional modules that were not seen in mouse LCs. Furthermore, human LCs were enriched in a transcriptional signature specific to the blood cross-presenting CD141/BDCA-3(+) DCs, the proposed equivalent to mouse CD8α(+) DCs. Consistent with our analysis, LCs were highly adept at inducing primary CTL responses. Thus, our study suggests that the function of LCs may not be conserved between mouse and human and supports human LCs as an especially relevant therapeutic target

As competências do representante comercial : o ramo atacadista agropecuário

Este trabalho investiga as competências que são essenciais para o indivíduo que atua na área comercial do ramo de rações e insumos agropecuários. Para isso, fez-se necessário contextualizar a figura deste profissional, diferenciando-o do vendedor externo e inserindo-o no contexto de trabalho contemporâneo, severamente transformado pelas novas tecnologias de informação. No intuito de atingir seus objetivos, este trabalho apresenta uma investigação de natureza exploratória e qualitativa. Os dados foram coletados por meio de 3 entrevistas de profundidade, feitas com profissionais atuantes em diferentes posições na cadeia produtiva de alimentação animal. Apesar de suas limitações, a análise apresenta informações complementares e por vezes até bastante diferentes sobre as competências que – a primeira vista - acreditamos serem as mais importantes para o profissional de vendas. A investigação destas competências é de grande importância para as empresas entenderem o perfil desejado para a função de agente comercial do ramo de alimentação animal e insumos agropecuários, além de servir como um guia de desenvolvimento para os profissionais autônomos que atuam com vendas

As competências do representante comercial : o ramo atacadista agropecuário

Este trabalho investiga as competências que são essenciais para o indivíduo que atua na área comercial do ramo de rações e insumos agropecuários. Para isso, fez-se necessário contextualizar a figura deste profissional, diferenciando-o do vendedor externo e inserindo-o no contexto de trabalho contemporâneo, severamente transformado pelas novas tecnologias de informação. No intuito de atingir seus objetivos, este trabalho apresenta uma investigação de natureza exploratória e qualitativa. Os dados foram coletados por meio de 3 entrevistas de profundidade, feitas com profissionais atuantes em diferentes posições na cadeia produtiva de alimentação animal. Apesar de suas limitações, a análise apresenta informações complementares e por vezes até bastante diferentes sobre as competências que – a primeira vista - acreditamos serem as mais importantes para o profissional de vendas. A investigação destas competências é de grande importância para as empresas entenderem o perfil desejado para a função de agente comercial do ramo de alimentação animal e insumos agropecuários, além de servir como um guia de desenvolvimento para os profissionais autônomos que atuam com vendas