157 research outputs found
Localized Crystallization of Calcium Phosphates by Light-Induced Processes
No full textMedical treatment options for bones and teeth can be significantly enhanced by taking control over the crystallization of biomaterials like hydroxyapatite in the healing process. Light-induced techniques are particularly interesting for this approach as they offer tremendous accuracy in spatial resolution. However, in the field of calcium phosphates, light-induced crystallization has not been investigated so far. Here, proof of principle is established to successfully induce carbonate-hydroxyapatite precipitation by light irradiation. Phosphoric acid is released by a photolabile molecule exclusively after irradiation, combining with calcium ions to form a calcium phosphate in the crystallization medium. 4-Nitrophenylphosphate (4NPP) is established as the photolabile molecule and the system is optimized and fully characterized. A calcium phosphate is crystallized exclusively by irradiation in aqueous solution and identified as carbonate apatite. Control over the localization and stabilization of the carbonate apatite is achieved by a pulsed laser, triggering precipitation in calcium and 4NPP-containing gel matrices. The results of this communication open up a wide range of new opportunities, both in the field of chemistry for more sophisticated reaction control in localized crystallization processes and in the field of medicine for enhanced treatment of calcium phosphate containing biomaterials
TIME RESOLVED DYNAMICS OF ELECTRONIC EXCITATIONS IN
No full text S. Minemoto, J. M\""{u}ller, G. Gantef\""{o}r, H. J. M\""{u}nzer, J. Boneberg, and P. Leiderer, Phys. Rev. Lett. accepted for publicationAuthor Institution: Universit\""at KonstanzExperiments have been performed an the ultrafast electron dynamics of mass selected cluster anions. The setup consists of a pulsed arc cluster ion source (PACIS), a time-of-flight mass spectrometer, a magnetic-bottle-type time of flight electron spectrometer, and a femtosecond laser. Time resolved pump/probe photoelectron spectra are recorded. We present first data on . Photoelectron spectra were obtained for a set of increasing delays between pump pulse (excitation of the anion) and probe pulse (detachment of the ad-electron). Interpretation of the series of spectra yields an assignment of the involved electron states and, moreover, the lifetime of the excited state. The method is suitable to study all kinds of electronic excitation and relaxation processes in mass selected nanoparticles. [FIGURE
Angiogenesis and lymphangiogenesis are downregulated in primary breast cancer
No full textAngiogenesis and lymphangiogenesis are considered to play key roles in tumour growth, progression and metastasis. However, targeting tumour angiogenesis in clinical trials showed only modest efficacy. We therefore scrutinised the concept of tumour angiogenesis and lymphangiogenesis by analysing the expression of crucial markers involved in these processes in primary breast cancer.
Methods: We analysed the expression of angiogenic, lymphangiogenic or antiangiogenic factors, their respective receptors and specific markers for endothelial and lymphendothelial cells by quantitative real-time RT-PCR in primary breast cancer and compared the expression profiles to non-cancerous, tumour-adjacent tissues and breast tissues from healthy women.
Results: We found decreased mRNA amounts of major angiogenic and lymphangiogenic factors in tumour compared to healthy tissues, whereas antiangiogenic factors were upregulated. Concomitantly, angiogenic and lymphangiogenic receptors were downregulated in breast tumours. This antiangiogenic, antilymphangiogenic microenvironment was even more pronounced in aggressive tumours and accompanied by reduced amounts of endothelial and lymphatic endothelial cell markers.
Conclusion: Primary breast tumours are not a site of highly active angiogenesis and lymphangiogenesis. Selection for tumour cells that survive with minimal vascular supply may account for this observation in clinical apparent tumours
Superhard, conductive coatings for atomic force microscopy cantilevers
No full textBoron carbide thin films were grown by mass selected ion beam deposition using low energy 11B+ and 12C+ ions at room temperature. The amorphous films exhibit any desired stoichiometry controlled by the ion charge ratio B+/C+. Films with a stoichiometry of B4C showed the optimal combination of a high mechanical strength and a low electrical resistivity for the coating of atomic force microscopy (AFM) silicon cantilevers. The properties of such AFM tips were evaluated and simultaneous topography and Kelvin mode AFM measurements with high lateral resolution were performed on the systems (i) Au nanoparticles on a p-WS2 surface and (ii) conducting/ superconducting YBa2Cu3O72x.publishe
The extremely truncated circumstellar disc of V410 X-ray 1: A precursor to TRAPPIST-1?
No full textProtoplanetary discs around brown dwarfs and very low mass (VLM) stars offer some of the best prospects for forming Earth-sized planets in their habitable zones. To this end, we study the nature of the disc around the VLM star V410 X-ray 1, whose spectral energy distribution (SED) is indicative of an optically thick and very truncated dust disc, with our modelling suggesting an outer radius of only 0.6 au. We investigate two scenarios that could lead to such a truncation, and find that the observed SED is compatible with both. The first scenario involves the truncation of both the dust and gas in the disc, perhaps due to a previous dynamical interaction or the presence of an undetected companion. The second scenario involves the fact that a radial location of 0.6 au is close to the expected location of the H2O snowline in the disc. As such, a combination of efficient dust growth, radial migration, and subsequent fragmentation within the snowline leads to an optically thick inner dust disc and larger, optically thin outer dust disc. We find that a firm measurement of the CO J = 2-1 line flux would enable us to distinguish between these two scenarios, by enabling a measurement of the radial extent of gas in the disc.Many models we consider contain at least several Earth-masses of dust interior to 0.6 au, suggesting that V410 X-ray 1 could be a precursor to a system with tightly packed inner planets, such as TRAPPIST-1
Flotillins are involved in the polarization of primitive and mature hematopoietic cells
No full textBACKGROUND: Migration of mature and immature leukocytes in response to chemokines is not only essential during inflammation and host defense, but also during development of the hematopoietic system. Many molecules implicated in migratory polarity show uniform cellular distribution under non-activated conditions, but acquire a polarized localization upon exposure to migratory cues. METHODOLOGY/PRINCIPAL FINDINGS: Here, we present evidence that raft-associated endocytic proteins (flotillins) are pre-assembled in lymphoid, myeloid and primitive hematopoietic cells and accumulate in the uropod during migration. Furthermore, flotillins display a polarized distribution during immunological synapse formation. Employing the membrane lipid-order sensitive probe Laurdan, we show that flotillin accumulation in the immunological synapse is concomittant with membrane ordering in these regions. CONCLUSIONS: Together with the observation that flotillin polarization does not occur in other polarized cell types such as polarized epithelial cells, our results suggest a specific role for flotillins in hematopoietic cell polarization. Based on our results, we propose that in hematopoietic cells, flotillins provide intrinsic cues that govern segregation of certain microdomain-associated molecules during immune cell polarization
Single-crystalline YIG flakes with uniaxial in-plane anisotropy and diverse crystallographic orientations
No full textWe study Y3Fe5O12 (YIG) flakes that we produce via mechanical cleaving and
exfoliation of YIG single crystals. By characterizing their structural and
magnetic properties, we find that these YIG nanoflakes have surfaces oriented
along unusual crystallographic axes and uniaxial in-plane magnetic anisotropy
due to their shape, both of which are not commonly available in YIG thin films.
These physical properties, combined with the possibility of picking up the YIG
flakes and stacking them onto flakes of other van der Waals materials or
pre-patterned electrodes or waveguides, open unexplored possibilities for
magnonics and for the realization of novel YIG-based heterostructures and
devices.Comment: 13 pages, 4 figure
Febrile Temperatures Attenuate IL-1 Release by Inhibiting Proteolytic Processing of the Proform and Influence Th1/Th2 Balance by Favoring Th2 Cytokines
No full textSuper-Resolution-Chip: an in-vitro platform that enables super-resolution microscopy of co-cultures and 3D systems
No full textThe development of organs-on-a-chip platforms has revolutionized in-vitro cellular culture by allowing cells to be grown in an environment that better mimics human physiology. However, there is still a challenge in integrating those platforms with advanced imaging technology. This is extremely important when we want to study molecular changes and subcellular processes on the level of a single molecule using super-resolution microscopy (SRM), which has a resolution beyond the diffraction limit of light. Currently, existing platforms that include SRM have certain limitations, either as they only support 2D monocultures, without flow or as they demand a lot of production and handling. In this study, we developed a Super-Res-Chip platform, consisting of a 3D-printed chip and a porous membrane, that could be used to co-culture cells in close proximity either in 2D or in 3D while allowing SRM on both sides of the membrane. To demonstrate the functionality of the device, we co-cultured in endothelial and epithelial cells and used direct stochastic optical reconstruction microscopy (dSTORM) to investigate how glioblastoma cells affect the expression of the gap-junction protein Connexin43 in endothelial cells grown in 2D and in 3D. Cluster analysis of Connexin43 distribution revealed no difference in the number of clusters, their size, or radii, but did identify differences in their density. Furthermore, the spatial resolution was high also when the cells were imaged through the membrane (20-30 nm for x-y) and 10-20 nm when imaged directly both for 2D and 3D conditions. Overall, this chip allows to characterize of complex cellular processes on a molecular scale in an easy manner and improved the capacity for imaging in a single molecule resolution complex cellular organization
Análise da evidenciação das provisões e dos passivos contingentes das principais empresas do segmento de carne e derivados listadas na B3
No full textCom as alterações instituídas pelas Leis nº 11.638/07 e nº 11.941/09, a convergência das normas contábeis brasileiras ao padrão internacional se tornou indispensável. Entre as mudanças apresentadas destacou-se o tratamento dado às provisões e aos passivos contingentes. Assim, o presente estudo tem como objetivo analisar a o que é evidenciado quanto às provisões e os passivos contingentes das maiores empresas do agronegócio do Brasil que atuam no segmento de carne e derivados a partir do que estabelece o CPC-25 e nas informações destacadas na CVM entre os anos de 2012 e 2016. Para isso foi realizado uma pesquisa qualitativa, descritiva e documental. O estudo examinou as demonstrações financeiras e notas explicativas das três maiores companhias do segmento de carne e derivados listadas na B3. A coleta e análise de dados tomou por base um checklist elaborado a partir do CPC 25, o qual estabelece procedimentos para tratamento das provisões, dos passivos contingentes e ativos contingentes. Os resultados desta pesquisa demonstram que as organizações estão aplicando corretamente as exigências relacionadas às fases de reconhecimento, mensuração bem como divulgação de provisões. Porém a evidenciação dos passivos contingentes pelas empresas não é unânime. Verificou-se como item mais apresentado pelas empresas o de natureza trabalhista, seguido pelo de natureza tributária/previdenciária e cível. Conclui-se ao final da pesquisa que as companhias estudadas não seguem totalmente o recomendado no CPC-25, devendo melhorar, principalmente, o que diz respeito à divulgação de seus passivos contingentes.With the changes introduced by Laws No. 11,638 / 07 and 11,941 / 09, the convergence of Brazilian accounting standards with the international standard became indispensable. Among the changes presented was the treatment of provisions and contingent liabilities. Thus, the present study aims to analyze what is evidenced in the provisions and contingent liabilities of the largest agribusiness companies in Brazil that operate in the meat and derivatives segment, based on CPC-25 and in the CVM between the years of 2012 and 2016. For this, a qualitative, descriptive and documentary research was carried out. The study examined the financial statements and explanatory notes of the three largest companies in the meat and derivatives segment listed in B3. The collection and analysis of data was based on a checklist prepared from CPC 25, which establishes procedures for treatment of provisions, contingent liabilities and contingent assets. The results of this research demonstrate that organizations are correctly applying the requirements related to the phases of recognition, measurement and disclosure of provisions. However, the disclosure of contingent liabilities by companies is not unanimous. The item presented by the companies was labor-related, followed by tax and social security. It is concluded at the end of the research that the companies studied do not follow fully what is recommended in CPC-25, and should improve, mainly, the disclosure of their contingent liabilities
- …
