994 research outputs found
Role of Solvent Compatibility in the Phase Behavior of Binary Solutions of Weakly Associating Multivalent Polymers
[Image: see text] Condensate formation of biopolymer solutions, prominently those of various intrinsically disordered proteins (IDPs), is often driven by “sticky” interactions between associating residues, multivalently present along the polymer backbone. Using a ternary mean-field “stickers-and-spacers” model, we demonstrate that if sticker association is of the order of a few times the thermal energy, a delicate balance between specific binding and nonspecific polymer–solvent interactions gives rise to a particularly rich ternary phase behavior under physiological circumstances. For a generic system represented by a solution comprising multiassociative scaffold and client polymers, the difference in solvent compatibility between the polymers modulates the nature of isothermal liquid–liquid phase separation (LLPS) between associative and segregative. The calculations reveal regimes of dualistic phase behavior, where both types of LLPS occur within the same phase diagram, either associated with the presence of multiple miscibility gaps or a flip in the slope of the tie-lines belonging to a single coexistence region
Heavy fermion superconductivity and magnetic order in non-centrosymmetric
is a novel heavy fermion superconductor, crystallising in the
structure as a tetragonally distorted low symmetry variant of the
structure type. exhibits antiferromagnetic order at
K and enters into a heavy fermion superconducting state at
K. Large values of T/K and T refer to heavy quasiparticles forming Cooper pairs. Hitherto, is the first heavy fermion superconductor without a center of
symmetry.Comment: 4 pages, 4 figure
AC/DC Susceptibility of the Heavy-Fermion Superconductor CePt3Si under Pressure
We have investigated the pressure dependence of ac and dc susceptibilities of
the heavy-fermion superconductor CePt3Si (Tc= 0.75 K) that coexists with
antiferromagnetism (TN = 2.2 K). As hydrostatic pressure is increased, Tc first
decreases rapidly, then rather slowly near the critical pressure Pc = 0.6 GPa
and shows a stronger decrease again at higher pressures, where Pc is the
pressure at which TN becomes zero. A transition width and a difference in the
two transition temperatures defined in the form of structures in the
out-of-phase component of ac susceptibilities also become small near Pc,
indicating that a double transition observed in CePt3Si is caused by some
inhomogeneous property in the sample that leads to a spatial variation of local
pressure. A sudden increase in the Meissner fraction above Pc suggests the
influence of antiferromagnetism on superconductivity.Comment: 4 pages with 5 figures. This paper will be published in J. Phys. Soc.
Jp
Low field extension for magnetometers (TinyBee) used for investigations on low-dimensional superconductors with Bc1 < 5G
In this article a simple and easy to install low magnetic field extension of
the SQUID magnetometer Quantum Design MPMS-7 is described. This has been
accomplished by complementing the MPMS-7 magnet control system with a
laboratory current supply for the low magnetic field region (B \leq 200G). This
hard- and software upgrade provides a significant gain in the magnetic field
accuracy up to an order of magnitude compared with the standard instrument's
setup and is improving the resolution to better than 0.01G below 40G. The field
control has been integrated into the Quantum Design MultiVu software for a
transparent and user-friendly operation of this extension. The improvements
achieved are especially useful, when low magnetic field strengths (B < 1G) are
required at high precision. The specific advantages of this application are
illustrated by sophisticated magnetic characterisation of lowdimensional
superconductors like Sc3CoC4 and SnSe2{Co({\eta}-C5H5)2}x.Comment: 16 pages, 7 figure
Heavy-Fermions in LiV2O4: Kondo-Compensation vs. Spin-Liquid Behavior?
7Li NMR measurements were performed in the metallic spinel LiV2O4. The
temperature dependencies of the line width, the Knight shift and the
spin-lattice relaxation rate were investigated in the temperature range 30 mK <
T < 280 K. For temperatures T < 1 K we observe a spin-lattice relaxation rate
which slows down exponentially. The NMR results can be explained by a
spin-liquid behavior and the opening of a spin gap of the order 0.6 K
Transport properties of moderately disordered UCuPd
We present a detailed study on the (magneto)transport properties of as-cast
and heat treated material UCuPd. We find a pronounced sample dependence of
the resistivity of as-cast samples, and reproduce the annealing
dependence of . In our study of the Hall effect we determine a metallic
carrier density for all samples, and a temperature dependence of the Hall
constant which is inconsistent with the Skew scattering prediction. The
magnetoresistive response is very small and characteristic for spin disorder
scattering, suggesting that overall the resistivity is controlled mostly by
nonmagnetic scattering processes. We discuss possible sources for the
temperature and field dependence of the transport properties, in particular
with respect to quantum criticality and electronic localization effects.Comment: 11 pages, 9 figures, submitted PR
Probiotics in Aquaculture Review: Current Status and Application in Tambaqui Cultivation (Colossoma macropomum)
The development of aquaculture guarantees the supply of animal protein of great nutritional value, contributing to food security. Currently one of the main problems faced is the occurrence of diseases, responsible for a worldwide economic loss, equivalent to US $ 9 billion per year. Aiming to increase resistance to diseases, increasing growth rates and food efficiency in intensive crops, some strategies have been developed, one of them is the use of probiotic bacteria. These, when in contact with the digestive tract of the host generates a series of benefits, among them, the modulation of the immune system, developing defense mechanisms and increasing resistance to stress. However, there are few documented reports on the efficiency of probiotics in native species, such as tambaqui (Colossoma macropomum). This species shows some resistance to stress, through physiological mechanisms of adaptation, such as lip expansion when subjected to hypoxia situations, which added to the positive effects of using probiotics would represent an increase in its resistance. The purpose of this work is to review the literature on the use of probiotics in aquaculture in order to provide a comprehensive synthesis of the current knowledge about its use in aquaculture, with emphasis on the intensive cultivation of tambaqui
Evolution of quantum criticality in the system CeNi9Ge4
The heavy fermion system CeNi9Ge4 exhibits a paramagnetic ground state with
remarkable features such as: a record value of the electronic specific heat
coefficient in systems with a paramagnetic ground state, \gamma = C/T \simeq
5.5 J/molK^2 at 80 mK, a temperature-dependent Sommerfeld-Wilson ratio,
R=\chi/\gamma, below 1 K and an approximate single ion scaling of the
4f-magnetic specific heat and susceptibility. These features are related to a
rather small Kondo energy scale of a few Kelvin in combination with a
quasi-quartet crystal field ground state. Tuning the system towards long range
magnetic order is accomplished by replacing a few at.% of Ni by Cu or Co.
Specific heat, susceptibility and resistivity studies reveal T_N \sim 0.2 K for
CeNi8CuGe4 and T_N \sim 1 K for CeNi8CoGe4. To gain insight whether the
transition from the paramagnetic NFL state to the magnetically ordered ground
state is connected with a heavy fermion quantum critical point we performed
specific heat and ac susceptibility studies and utilized the \mu SR technique
and quasi-elastic neutron scattering.Comment: 8 pages, 3 figures, will be published in J.Phys.: Conf. Series
(Proceedings of the International & Interdisciplinary Workshop on Novel
Phenomena in Intergrated Comples Sciences: From Living to Non-living Systems,
Japan, held in Kyoto, October 11-14, 2010
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