Search results for " Polarization"
showing 10 items of 668 documents
Pion Form Factor at BESIII
2017
Abstract At BESIII, we measured the cross section of e + e − → π + π − in the energy range between 600 and 900 MeV/c2 with a 2.93 fb−1 data set taken at the center-of-mass energy 3.773 GeV. The initial state radiation technique is used, and the total systematic uncertainty is estimated to be 0.9%. The squared form factor | F π | 2 is extracted, and comparisons are made with results from both KLOE and BaBar. The two-pion contribution to the hadronic vacuum polarization contribution to ( g − 2 ) μ is calculated to be a μ π π , LO ( 600 − 900 MeV / c 2 ) = ( 368.2 ± 2.5 s t a t . ± 3.3 s y s t . ) ⋅ 10 − 10 .
Thermal potential of ion-exchange membranes and its application to thermoelectric power generation
2016
The low efficiency and high price of thermoelectric semiconductors has generated interest in unconventional forms of thermoelectric materials. In this article, ionic thermoelectricity has been studied with commercial ion-exchange membranes for different aqueous 1:1 electrolytes. The theory of thermal membrane potential has been derived taking into account the ionic heats of transport, the non-isothermal Donnan potentials, the temperature polarization, and the thermally-induced concentration polarization of the electrolyte. Also the generated thermoelectric power has been experimentally studied. The experiments show good agreement with the theory, and suggest ways for systematic improvement …
Longitudinal spin-relaxation in nitrogen-vacancy centers in electron irradiated diamond
2015
We present systematic measurements of longitudinal relaxation rates ($1/T_1$) of spin polarization in the ground state of the nitrogen-vacancy (NV$^-$) color center in synthetic diamond as a function of NV$^-$ concentration and magnetic field $B$. NV$^-$ centers were created by irradiating a Type 1b single-crystal diamond along the [100] axis with 200 keV electrons from a transmission electron microscope with varying doses to achieve spots of different NV$^-$ center concentrations. Values of ($1/T_1$) were measured for each spot as a function of $B$.
Measurements of temperature polarization phenomena in membrane distillation channels by a thermographic technique
2014
In the present work, a recently presented experimental technique, based on the use of thermochromic liquid crystals (TLCs) and digital image processing, has been employed in order to measure the temperature and local heat transfer coefficient distribution on the membrane surface in a MD spacer-filler channel
Generalized Virasoro anomaly and stress tensor for dilaton coupled theories
2003
We derive the anomalous transformation law of the quantum stress tensor for a 2D massless scalar field coupled to an external dilaton. This provides a generalization of the Virasoro anomaly which turns out to be consistent with the trace anomaly. We apply it together with the equivalence principle to compute the expectation values of the covariant quantum stress tensor on a curved background. Finally we briefly illustrate how to evaluate vacuum polarization and Hawking radiation effects from these results.
IR fingerprints of U(VI) nitrate monoamides complexes: a joint experimental and theoretical study.
2010
Infrared spectra of 0.5 mol·L-1 uranium(VI) nitrate monoamide complexes in toluene have been recorded and compared with infrared spectra calculated by DFT. The investigated monoamides were N,N- dimethylformamide (DMF), N,N-dibutylformamide (DBF), and N,N- dicyclohexylformamide (DcHF). The validity of DFT calculations for describing uranium nitrate monoamide complexes has been confirmed as a fair agreement between experimental and calculated spectra was obtained. Furthermore, a topological analysis of the electron density has been carried out to characterize monoamide-uranium interactions. From this work, it appears that the increase of stability of uranylmonoamide complexes may be directly …
CFD simulation of a membrane distillation module channel
2009
The interest towards the use of membrane distillation (MD) processes for seawater desalination has been rising recently due to the ease of coupling MD with waste and/or solar thermal energy. Notwithstanding the flexibility of the process and its potential for further developments in membrane performances, one of the main drawbacks is the thermal efficiency reduction caused by temperature polarization. Because of such phenomenon, only a small amount of the driving force potentially available for the separation process, i.e. the temperature difference between evaporating and condensing fluids, is actually used for the separation. In order to reduce temperature polarization a study on the effe…
Cholesterol Modulates the Interaction of β-Amyloid Peptide with Lipid Bilayers
2009
The interaction of an amphiphilic, 40-amino acid beta-amyloid (Abeta) peptide with liposomal membranes as a function of sterol mole fraction (X(sterol)) was studied based on the fluorescence anisotropy of a site-specific membrane sterol probe, dehydroergosterol (DHE), and fluorescence resonance energy transfer (FRET) from the native Tyr-10 residue of Abeta to DHE. Without Abeta, peaks or kinks in the DHE anisotropy versus X(sterol) plot were detected at X(sterol) approximately 0.25, 0.33, and 0.53. Monomeric Abeta preserved these peaks/kinks, but oligomeric Abeta suppressed them and created a new DHE anisotropy peak at X(sterol) approximately 0.38. The above critical X(sterol) values coinci…
Use of the Transglutaminase Reaction To Study the Dissociation of Histone N-Terminal Tails from DNA in Nucleosome Core Particles
1997
We have recently shown that core histones are glutaminyl substrates for transglutaminase (TGase) and that when native nucleosome cores are incubated with monodansylcadaverine (DNC) as donor amine, this fluorescent probe is incorporated into Gln5 and Gln19 of H3 and in Gln22 of H2B [Ballestar et al. (1996) J. Biol. Chem. 271, 18817-18825]. In the present paper, we report that the cause by which Gln22 of H2B is modified in nucleosomes but not in the free histone is the interaction of the region containing that glutamine with DNA. We have used the specificity of the TGase reaction to study the changes induced by increasing ionic strength in the interaction between the histone N-terminal tails …
Introduction to Self-Assembled Monolayers
2015
One of the most exciting targets of molecular spintronics field is to go towards multifunctional devices where the properties can be accurately controlled and actively changed. Spin dependent hybridization at the metal/molecule interface could thus be used in the tailoring of the resistive and magnetoresistive response of spintronic devices exploiting chemistry versatility. In this new direction, Self-Assembled Monolayers (SAMs) appear as highly promising candidates since each part and function of this system can be modulated independently (like a molecular LEGO building unit). Despite highly promising, they are still scarcely investigated in the literature probably due to the difficulties …