Pressure effects in PrT2B2C (T = Co, Ni, Pt): Applied and chemical pressure

High-pressure electrical resistivity, r(T), measurements on intermetallic Pr(Co, Ni, Pt)2B2C compounds were performed down to 2K. At room pressure the r(T) in a-b direction curves for the non superconducting Pr(Co, Ni)2B2C compounds exhibit magnetic correlations at about 10 and 4 K, respectively. At low temperatures, PrCo2B2C shows a large spin-dependent electron scattering in comparison to PrNi2B2C. Under applied pressure the magnetic scattering tends to be suppressed more effectively in PrCo2B2C than in PrNi2 B2C. The low temperature behavior of r(T,P) for PrNi2B2C and PrCo2B2C suggests a spin fluctuations mechanism. In the other hand PrPt2B2C compound shows superconductivity at about 6 K and under pressure its superconducting transition temperature tends to be degraded at a rate dTc/dP = -0.34 K/GPa, as expected in compounds with transition metals. The experimental results in Co, Ni and Pt based compounds are analyzed from the point of view of the external and chemical internal pressure effects

A structural modeling approach for the understanding of initiation and elongation of ALS-linked superoxide dismutase fibrils

Familial amyotrophic lateral sclerosis caused by mutations in copper-zinc superoxide dismutase (SOD1) is characterized by the presence of SOD1-rich inclusions in spinal cords. It has been shown that a reduced intra-subunit disulfide bridge apo-SOD1 can rapidly initiate fibrillation forming an inter-subunits disulfide under mild, physiologically accessible conditions. Once initiated, elongation can proceed via recruitment of either apo or partially metallated disulfide-intact SOD1 and the presence of copper, but not zinc, ions inhibit fibrillation. We propose a structural model, refined through molecular dynamics simulations, that, taking into account these experimental findings, provides a molecular explanation for the initiation and the elongation of SOD1 fibrils in physiological conditions. The model indicates the occurrence of a new dimeric unit, prone to interact one with the other due to the presence of a wide hydrophobic surface and specific electrostatic interactions. The model has dimensions consistent with the SOD1 fibril size observed through electron microscopy and provides a structural basis for the understanding of SOD1 fibrillation

Produktion af biogas fra husdyrgødning og afgrøder i økologisk landbrug

Formålet med undersøgelsen har været at samle erfaringer med biogasproduktion, næringstofflow og energiproduktion af økologisk græs, triticale, vikke, lupin, kvæggylle og dybstrøelse fra kvægstalde

Zinc ion coordination as a modulating factor of the ZnuA histidine-rich loop flexibility: a molecular modeling and fluorescence spectroscopy study

ZnuA is the soluble component of the high-affinity ZnuABC zinc transporter belonging to the ATP-binding cassette-type periplasmic Zn-binding proteins. The zinc transporter ZnuABC is composed by three proteins: ZnuB, the membrane permease, ZnuC, the ATPase component and ZnuA, the soluble periplasmic metal-binding protein which captures Zn and delivers it to ZnuB. The ZnuA protein contains a charged flexible loop, rich in histidines and acidic residues, showing significant species-specific differences. Various studies have established that this loop contributes to the formation of a secondary zinc binding site, which has been proposed to be important in the acquisition of periplasmic Zn for its delivery to ZnuB or for regulation of zinc uptake. Due to its high mobility the structure of the histidine-rich loop has never been solved by X-ray diffraction studies. In this paper, through a combined use of molecular modeling, mutagenesis and fluorescence spectroscopy, we confirm the presence of two zinc binding sites characterized by different affinities for the metal ion and show that the flexibility of the loop is modulated by the binding of the zinc ions to the protein. The data obtained by fluorescence spectroscopy have then be used to validate a 3D model including the unsolved histidine-rich loop

Potential distribution in deformed ZnO nanowires

AbstractThe potential distribution in a deformed ZnO nanowire relies upon its piezoelectric and semiconductive properties. Here we systematically investigate the influence of different parameters on the equilibrium potential distribution. In particular we calculate the electric potential distribution when thermodynamic equilibrium among free charge carriers is achieved for nanowires under different doping concentrations (n or p type), different applied forces, and different geometric configurations. We show that doping concentration is the parameter that mostly affects the magnitude and distribution of the piezoelectric potential

UWB FastlyTunable 0.550 GHz RF Transmitter based on Integrated Photonics

Currently, due to the 6G revolution, applications ranging from communication to sensing are experiencing an increasing and urgent need of software-defined ultra-wideband (UWB) and tunable radio frequency (RF) apparatuses with low size, weight, and power consumption (SWaP). Unfortunately, the coexistence of ultra-wideband and software-defined operation, tunability and low SWaP represents a big issue in the current RF technologies. Recently, photonic techniques have been demonstrated to support achieving the desired features when applied in RF UWB transmitters, introducing extremely wide operation and instantaneous bandwidth, tunable filtering, tunable photonics-based microwave mixing with very high port-to-port isolation, and intrinsic immunity to electromagnetic interferences. Moreover, the recent advances in photonics integration also allow to obtain very compact devices. In this article, to the best of our knowledge, the first example of a complete tunable software-defined RF transmitter with low footprint (i.e. on photonic chip) is presented exceeding the state-of-the-art for the extremely large tunability range of 0.5-50 GHz without any parallelization of narrower-band components and with fast tuning (< 200 s). This first implementation represents a breakthrough in microwave photonics