605 research outputs found
In-depth mesocrystal formation analysis of microwave-assisted synthesis of LiMnPO4nanostructures in organic solution
In the present work, we report on the preparation of LiMnPO4 (lithiophilite) nanorods and mesocrystals composed of self-assembled rod subunits employing microwave-assisted precipitation with processing times on the time scale of minutes. Starting from metal salt precursors and H3PO4 as phosphate source, single-phase LiMnPO4 powders with grain sizes of approx. 35 and 65 nm with varying morphologies were obtained by tailoring the synthesis conditions using rac-1-phenylethanol as solvent. The mesocrystal formation, microstructure and phase composition were determined by electron microscopy, nitrogen physisorption, X-ray diffraction (including Rietveld refinement), dynamic light scattering, X-ray absorption and X-ray photoelectron spectroscopy, and other techniques. In addition, we investigated the formed organic matter by gas chromatography coupled with mass spectrometry in order to gain a deeper understanding of the dissolution\u2013precipitation process. Also, we demonstrate that the obtained LiMnPO4 nanocrystals can be redispersed in polar solvents such as ethanol and dimethylformamide and are suitable as building blocks for the fabrication of nanofibers via electrospinning
Influence of residual ethanol concentration on the growth of Gluconacetobacter xylinus I 2281
The influence of residual ethanol on metab. of food grade Gluconacetobacter xylinum I 2281 was investigated during controlled cultivations on 35 g/l glucose and 5 g/l ethanol. Bacterial growth was strongly reduced in the presence of ethanol, which is unusual for acetic acid bacteria. Biomass accumulated only after complete oxidn. of ethanol to acetate and carbon dioxide. In contrast, bacterial growth initiated without delay on 35 g/l glucose and 5 g/l acetate. It was found that acetyl CoA was activated by the acetyl CoA synthetase (Acs) pathway in parallel with the phosphotransacetylase (Pta)-acetate kinase (Ack) pathway. The presence of ethanol in the culture medium strongly reduced Pta activity while Acs and Ack remained active. A carbon balance calcn. showed that the overall catabolism could be divided into two independent parts: upper glycolysis linked to glucose catabolism and lower glycolysis linked to ethanol catabolism. This calcn. showed that the carbon flux through the tricarboxylic cycle is lower on ethanol than on acetate. This corroborated the diminution of carbon flux through the Pta-Ack pathway due to the inhibition of Pta activity on ethanol. [on SciFinder (R)
A graph-based modelling methodology for high-pressure networks applied on waterjet machining
This paper proposes a graph-based methodology that models high-pressure networks of varioustopologies. Therefore, a mathematical modelling of a supply network for waterjet machining will be introduced. High-pressure components are assigned to homogeneous segments, each representing a local pressure state as a diïŹerential equation. Segments are subsequently interconnected along the ïŹuid ïŹow path as an algebraic equation that allocates a ïŹuid ïŹow to the interconnections, resulting in a lumped parameter model. For this purpose, a graph network description has been used to approximate the spatially distributed high-pressure system. In this way, the proposed methodology oïŹers a ïŹexible modelling to cope with diïŹerent network topologies. Moreover, a variable ïŹuid compressibility has also been introduced so that a wide operating range can be included. This modelling methodology has been applied to a supply network for waterjet machining. The resulting mathematical model has been veriïŹed by measurements from a test bench with a pressure range of 100 to 400 MPa. It was shown that a variable ïŹuid compressibility improves the modelâs accuracy and that modelling errors can be reduced in comparison to other existing methodologies
Disorder-Induced Phase Control in Superfluid Fermi-Bose Mixtures
We consider a mixture of a superfluid Fermi gas of ultracold atoms and a
Bose-Einstein condensate of molecules possessing a continuous U(1) (relative
phase) symmetry. We study the effects that a spatially random
photo-associative-dissociative symmetry breaking coupling of the systems. Such
coupling allows to control the relative phase between a superfluid order
parameter of the Fermi system and the condensate wavefunction of molecules for
temperatures below the BCS critical temperature. The presented mechanism of
phase control belongs to the general class of disorder-induced order phenomena
that rely on breaking of continuous symmetry.Comment: 4 pages, 2 figure
The challenges of ethical research with children
As especificidades da pesquisa com crianças tĂȘm ganhado visibilidade nas produçÔes acadĂȘmicas em diversas ĂĄreas de
conhecimento, com destaque para a Sociologia da InfĂąncia, principalmente a partir dos ânovos estudos sobre a infĂąnciaâ
os quais emergiram ao final da década de 1980. Essa visibilidade acontece devida a questÔes como: a discussão sobre
as imagens da infĂąncia, construĂdas socio-historicamente; o reconhecimento da condição das crianças enquanto atores
sociais, portanto, seres competentes, que atribuem significaçÔes a suas experiĂȘncias e contextos; e o reconhecimento
das crianças enquanto sujeitos de direitos, reconhecimento este pautado pela Doutrina da Proteção Integral. Permeadas
por essas questĂ”es, as pesquisas com crianças agregam a questĂŁo da Ătica nas atividades desenvolvidas na relação
pesquisador-criança. No contexto dessa discussão, este trabalho propÔe refletir sobre essas questÔes e os cuidados
éticos nesse tipo de pesquisa, considerando a condição da criança enquanto sujeito de direitos. Foi realizado um
recorte da produção acadĂȘmica representativa na ĂĄrea da Sociologia da InfĂąncia nas duas Ășltimas dĂ©cadas, identificando
quais aspectos aparecem nas preocupaçÔes dos autores, quais abordagens norteiam a discussão desses aspectos e,
principalmente, que concepção de infùncia estå presente nessa produção.The specificities of research with children have gained visibility in scientific publications in various areas of knowledge,
especially in Sociology of Childhood and the ânew studies of childhoodâ, which emerged at the end of the 1980s. This
fact is due to discussions about childhood from a socio-historical perspective; the recognition of children as social
actors and therefore able to give meaning to their experiences and contexts; and the recognition of children as
individuals entitled to rights, according to the Doutrina da Proteção Integral (Full Protection Doctrine). Therefore,
research ethics is an essential element of good research governance, especially in terms of activities related to the
relationship between the researcher and child. Accordingly, the objective of this study is to examine and explore these
issues, considering the child as an individual entitled to rights. A literature review of articles published in the last two
decades in the area of Sociology of Childhood was conducted to identify the main issues and topics addressed, the
approaches that guided the discussions and, especially, to identify the conception of childhood present in these
studies.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), Portuga
Assessing the life cycle environmental impacts of titania nanoparticle production by continuous flow solvo/hydrothermal synthesis
Continuous-flow hydrothermal and solvothermal syntheses offer substantial advantages over conventional processes, producing high quality materials from a wide range of precursors. In this study, we evaluate the âcradle-to-gateâ life cycle environmental impacts of alternative titanium dioxide (TiOâ) nanoparticle production parameters, considering a range of operational conditions, precursors, material properties and production capacities. A detailed characterisation of the nano-TiOâ products allows us, for the first time, to link key nanoparticle characteristics to production parameters and environmental impacts, providing a useful foundation for future studies evaluating nano-TiOâ applications. Five different titanium precursors are considered, ranging from simple inorganic precursors, like titanium oxysulphate (TiOS), to complex organic precursors such as titanium bis(ammonium-lactato)dihydroxide (TiBALD). Synthesis at the laboratory scale is used to determine the yield, size distribution, crystallinity and phase of the nanoparticles. The specifications and operating experience of a full scale plant (>1000 t per year) are used to estimate the mass and energy inputs of industrial scale production for the life cycle assessment. Overall, higher process temperatures are linked to larger, more crystalline nanoparticles and higher conversion rates. Precursor selection also influences nano-TiOâ properties: production from TiOS results in the largest particle sizes, while TiBALD achieves the smallest particles and narrowest size distribution. Precursor selection is the main factor in determining cradle-to-gate environmental impacts (>80% in some cases), due to the production impact of complex organic precursors. Nano-TiO2 production from TiOS shows the lowest global warming potential (GWP) (<12 kg COâ-eq. per kg TiOâ) and cumulative energy demand (CED) (<149 MJ kgÂŻÂč TiOâ) due to the low environmental impact of the precursor, the use of water as a solvent and its high yield even at lower temperatures. Conversely, the TiBALD precursor shows the highest impact (86 kg COâ-eq. per kg TiOâ and 1952 MJ kgÂŻÂč TiOâ) due to the need for additional post-synthesis steps and complexity of precursor manufacturing. The main purpose of this study is not a direct comparison of the environmental impacts of TiOâ nanoparticles manufactured utilizing various precursors under different conditions, but to provide an essential foundation for future work evaluating potential applications of nano-TiOâ and their life cycle environmental impacts
Transcendental-Phenomenological Proof and Descriptive Metaphysics
Following P.F. Strawson's reading of Kant, the majority of the literature on transcendental arguments seeks to divorce such arguments from their original Kantian context. This thesis is concerned with Mark Sacks's recent defence of transcendental arguments, which takes a different approach. A critique is given of Sacks's work and extensions and modifications of his approach are recommended. It is proposed that certain difficulties encountered by Kant's transcendentally-ideal approach can be overcome with Hegelian solutions
Policy monitoring in the EU: The impact of institutions, implementation, and quality
Policy monitoring is often seen as a crucial ingredient of policy evaluation, but theoretically informed empirical analyses of real-world policy monitoring practices are still rare. This paper addresses this gap by focusing on climate policy monitoring in the European Union, which has a relatively stringent system of greenhouse gas monitoring but a much less demanding approach to monitoring policies. It explores how institutional settings, policy implementation, and the quality of information may impact the practices and politics of policy monitoring. Drawing on quantitative regression models and qualitative interviews, it demonstrates that policy monitoring has evolved over time and is itself subject to implementation pressures, but also exhibits learning effects that improve its quality. In further developing both everyday policy monitoring practices and academic understanding of them, there is a need to pay attention to their designâspecifically, the impact of any overarching rules, the institutional support for implementation, and the criteria governing the quality of the information they deliver. In short, policy monitoring should be treated as a governance activity in its own right, raising many different design challenges
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