578 research outputs found
The effect of ultrafine WO3 nanoparticles on the organization of thylakoids enriched in photosystem II and energy transfer in photosystem II complexes
In this work, a new approach to construct self-assembled hybrid systems based on natural PSII-enriched thylakoid membranes (PSII BBY) is demonstrated. Superfine m-WO3 NPs (≈1–2 nm) are introduced into PSII BBY. Transmission electron microscopy (TEM) measurements showed that even the highest concentrations of NPs used did not degrade the PSII BBY membranes. Using atomic force microscopy (AFM), it is shown that the organization of PSII BBY depends strongly on the concentration of NPs applied. This proved that the superfine NPs can easily penetrate the thylakoid membrane and interact with its components. These changes are also related to the modified energy transfer between the external light-harvesting antennas and the PSII reaction center, shown by absorption and fluorescence experiments. The biohybrid system shows stability at pH 6.5, the native operating environment of PSII, so a high rate of O2 evolution is expected. In addition, the light-induced water-splitting process can be further stimulated by the direct interaction of superfine WO3 NPs with the donor and acceptor sides of PSII. The water-splitting activity and stability of this colloidal system are under investigation
Crystallographically oriented magnetic ZnFe2O4 nanoparticles synthesized by Fe implantation into ZnO
In this paper, a correlation between structural and magnetic properties of Fe
implanted ZnO is presented. High fluence Fe^+ implantation into ZnO leads to
the formation of superparamagnetic alpha-Fe nanoparticles. High vacuum
annealing at 823 K results in the growth of alpha-Fe particles, but the
annealing at 1073 K oxidized the majority of the Fe nanoparticles. After a long
term annealing at 1073 K, crystallographically oriented ZnFe2O4 nanoparticles
were formed inside ZnO with the orientation relationship of
ZnFe2O4(111)[110]//ZnO(0001)[1120]. These ZnFe2O4 nanoparticles show a
hysteretic behavior upon magnetization reversal at 5 K.Comment: 21 pages, 7 figures, accepted by J. Phys. D: Appl. Phy
Proteome-wide analysis of protein lipidation using chemical probes: in-gel fluorescence visualisation, identification and quantification of N-myristoylation, N- and S-acylation, Ocholesterylation, S-farnesylation and S-geranylgeranylation
Protein lipidation is one of the most widespread post-translational modifications (PTMs) found in nature, regulating protein function, structure and subcellular localization. Lipid transferases and their substrate proteins are also attracting increasing interest as drug targets because of their dysregulation in many disease states. However, the inherent hydrophobicity and potential dynamic nature of lipid modifications makes them notoriously challenging to detect by many analytical methods. Chemical proteomics provides a powerful approach to identify and quantify these diverse protein modifications by combining bespoke chemical tools for lipidated protein enrichment with quantitative mass spectrometry–based proteomics. Here, we report a robust and proteome-wide approach for the exploration of five major classes of protein lipidation in living cells, through the use of specific chemical probes for each lipid PTM. In-cell labeling of lipidated proteins is achieved by the metabolic incorporation of a lipid probe that mimics the specific natural lipid, concomitantly wielding an alkyne as a bio-orthogonal labeling tag. After incorporation, the chemically tagged proteins can be coupled to multifunctional ‘capture reagents’ by using click chemistry, allowing in-gel fluorescence visualization or enrichment via affinity handles for quantitative chemical proteomics based on label-free quantification (LFQ) or tandem mass-tag (TMT) approaches. In this protocol, we describe the application of lipid probes for N-myristoylation, N- and S-acylation, O-cholesterylation, S-farnesylation and S-geranylgeranylation in multiple cell lines to illustrate both the workflow and data obtained in these experiments. We provide detailed workflows for method optimization, sample preparation for chemical proteomics and data processing. A properly trained researcher (e.g., technician, graduate student or postdoc) can complete all steps from optimizing metabolic labeling to data processing within 3 weeks. This protocol enables sensitive and quantitative analysis of lipidated proteins at a proteome-wide scale at native expression levels, which is critical to understanding the role of lipid PTMs in health and disease
Fuzzy-based forest fire prevention and detection by wireless sensor networks
Forest fires may cause considerable damages both in ecosystems and lives.
This proposal describes the application of Internet of Things and wireless
sensor networks jointly with multi-hop routing through a real time and dynamic
monitoring system for forest fire prevention. It is based on gathering and
analyzing information related to meteorological conditions, concentrations of
polluting gases and oxygen level around particular interesting forest areas.
Unusual measurements of these environmental variables may help to prevent
wildfire incidents and make their detection more efficient. A forest fire risk
controller based on fuzzy logic has been implemented in order to activate
environmental risk alerts through a Web service and a mobile application. For
this purpose, security mechanisms have been proposed for ensuring integrity and
confidentiality in the transmission of measured environmental information.
Lamport's signature and a block cipher algorithm are used to achieve this
objective
Regionalização Da Saúde: (in)visibilidade E (i)materialidade Da Universalidade E Integralidade Em Saúde No Trânsito De Institucionalidades
Regionalization is a strategy of organization and integration of services in national health systems, in a path to be followed toward comprehensiveness and universal access. However, its principles are still invisible in Brazilian society, and the forms of management in health regions are questioned, as well as its actual effects on the construction of health as a right. This article is dedicated to such questioning and falls as a production aiming to denature processes and enable the emergence of events put into invisibility because of the “discursive formations” of health regionalization. This study comprises the regionalization process of Ceará’s health system since the 1990s. This is a qualitative study that examines the reports of 23 state managers of health, as well as the documentary narratives related to this issue. This study aims to build “bundles of relations”, articulating the subjects and institutions in the production of “knowledge-power and truth-power”, according to Foucault’s reference, and in dialogue with public health authors. The regionalization of Ceará points to a reform of the health sector, delegating the management and provision of services to the Social Organization and to the consortium, on procedural and productive contracting, strengthening the “entrepreneurship” of health and thus affecting the production of comprehensiveness and universality. We conclude that the Unified Health System's constitutional stratum is undergoing a breaking process, forging another “regime of comprehensiveness and universality”, that can be observed in the fact that the Unified Health System is between institutionalities, and in the change from the right to health care to customer right in a reductionist shift. © 2016, UNIV SAOPAULO. All rights reserved.25490291
Magnetic enhancement of CoZnFeO spinel oxide by mechanical milling
We report the magnetic properties of mechanically milled
CoZnFeO spinel oxide. After 24 hours milling of the
bulk sample, the XRD spectra show nanostructure with average particle size
20 nm. The as milled sample shows an enhancement in magnetization and
ordering temperature compared to the bulk sample. If the as milled sample is
annealed at different temperatures for the same duration, recrystallization
process occurs and approaches to the bulk structure on increasing the annealing
temperatures. The magnetization of the annealed samples first increases and
then decreases. At higher annealing temperature ( 1000C) the system
shows two coexisting magnetic phases {\it i.e.}, spin glass state and
ferrimagnetic state, similar to the as prepared bulk sample. The room
temperature M\"{o}ssbauer spectra of the as milled sample, annealed at
300C for different durations (upto 575 hours), suggest that the observed
change in magnetic behaviour is strongly related with cations redistribution
between tetrahedral (A) and octahedral (O) sites in the spinel structure. Apart
from the cation redistribution, we suggest that the enhancement of
magnetization and ordering temperature is related with the reduction of B site
spin canting and increase of strain induced anisotropic energy during
mechanical milling.Comment: 14 pages LaTeX, 10 ps figure
Interacting spin-2 fields in three dimensions
Using the frame formulation of multi-gravity in three dimensions, we show
that demanding the presence of secondary constraints which remove the
Boulware-Deser ghosts restricts the possible interaction terms of the theory
and identifies invertible frame field combinations whose effective metric may
consistently couple to matter. The resulting ghost-free theories can be
represented by theory graphs which are trees. In the case of three frame
fields, we explicitly show that the requirement of positive masses and energies
for the bulk spin-2 modes in AdS is consistent with a positive central
charge for the putative dual CFT.Comment: 26 pages, 3 figures, v2: minor changes, matches published versio
Thermal relaxation of magnetic clusters in amorphous Hf_{57}Fe_{43} alloy
The magnetization processes in binary magnetic/nonmagnetic amorphous alloy
Hf_{57}Fe_{43} are investigated by the detailed measurements of magnetic
hysteresis loops, temperature dependence of magnetization, relaxation of
magnetization and magnetic ac susceptibility, including a nonlinear term.
Blocking of magnetic moments at lower temperatures is accompanied with the slow
relaxation of magnetization and magnetic hysteresis loops. All of the observed
properties are explained with the superparamagnetic behaviour of the single
domain magnetic clusters inside the nonmagnetic host, their blocking by the
anisotropy barriers and thermal fluctuation over the barriers accompanied by
relaxation of magnetization. From magnetic viscosity analysis based on thermal
relaxation over the anisotropy barriers it is found out that magnetic clusters
occupy the characteristic volume from 25 up to 200 nm3 . The validity of the
superparamagnetic model of Hf_{57}Fe_{43} is based on the concentration of iron
in the Hf_{100-x}Fe_{43} system that is just below the threshold for the long
range magnetic ordering. This work throws more light on magnetic behaviour of
other amorphous alloys, too
Space-time defects and teleparallelism
We consider the class of space-time defects investigated by Puntigam and
Soleng. These defects describe space-time dislocations and disclinations
(cosmic strings), and are in close correspondence to the actual defects that
arise in crystals and metals. It is known that in such materials dislocations
and disclinations require a small and large amount of energy, respectively, to
be created. The present analysis is carried out in the context of the
teleparallel equivalent of general relativity (TEGR). We evaluate the
gravitational energy of these space-time defects in the framework of the TEGR
and find that there is an analogy between defects in space-time and in
continuum material systems: the total gravitational energy of space-time
dislocations and disclinations (considered as idealized defects) is zero and
infinit, respectively.Comment: 22 pages, no figures, to appear in the Class. Quantum Gravit
- …