69 research outputs found
Impedance-Based Water-Quality Monitoring Using the Parallel-Plate Method
The application of electromagnetic (EM) waves to measure the electrical properties (dielectric constant and loss tangent) of materials is a well-known approach. The electrical properties can be used to indirectly measure several physical properties of solutions in water such as the concentration and chemical composition of contaminants in water, as a representative of the liquid phase in soil. A capacitive method of measuring dielectric properties of solutions is proposed to detect and determine low-concentration chemical and biological contaminations in water. The primary objective of this project is to design a low-cost sensor that would require small volumes of samples to detect low concentrations of dissolved contaminants in water. A forward model was developed using a finite-element method (FEM) to simulate the experimental setup (EXP). A calibration function was also developed to minimize deviations between FEM and EXP results for benchmark/reference solutions with known dielectric properties. The validated, calibrated forward model was then inverted to calculate the electrical properties of unknown solutions using the corresponding EXP results
Nuclear matter at high density: Phase transitions, multiquark states, and supernova outbursts
Phase transition from hadronic matter to quark-gluon matter is discussed for
various regimes of temperature and baryon number density. For small and medium
densities, the phase transition is accurately described in the framework of the
Field Correlation Method, whereas at high density predictions are less certain
and leave room for the phenomenological models. We study formation of
multiquark states (MQS) at zero temperature and high density. Relevant MQS
components of the nuclear matter can be described using a previously developed
formalism of the quark compound bags (QCB).
Partial-wave analysis of nucleon-nucleon scattering indicates the existence
of 6QS which manifest themselves as poles of -matrix. In the framework of
the QCB model, we formulate a self-consistent system of coupled equations for
the nucleon and 6QS propagators in nuclear matter and the G-matrix. The
approach provides a link between high-density nuclear matter with the MQS
components and the cumulative effect observed in reactions on the nuclei, which
requires the admixture of MQS in the wave functions of nuclei kinematically.
6QS determine the natural scale of the density for a possible phase
transition into the MQS phase of nuclear matter. Such a phase transition can
lead to dynamic instability of newly born protoneutron stars and dramatically
affect the dynamics of supernovae. Numerical simulations show that the phase
transition may be a good remedy for the triggering supernova explosions in the
spherically symmetric supernova models. A specific signature of the phase
transition is an additional neutrino peak in the neutrino light curve. For a
Galactic core-collapse supernova, such a peak could be resolved by the present
neutrino detectors. The possibility of extracting the parameters of the phase
of transition from observation of the neutrino signal is discussed also.Comment: 57 pages, 22 figures, 7 tables; RevTeX 4; submitted to Phys. Atom.
Nuc
Measurement of prompt hadron production ratios in collisions at 0.9 and 7 TeV
The charged-particle production ratios , , ,
, and are measured with the LHCb detector using of collisions delivered by the LHC at TeV and
at TeV. The measurements are performed as a
function of transverse momentum and pseudorapidity . The
production ratios are compared to the predictions of several Monte Carlo
generator settings, none of which are able to describe adequately all
observables. The ratio is also considered as a function of rapidity
loss, , and is used to constrain models of
baryon transport.Comment: Incorrect entries in Table 2 corrected. No consequences for rest of
pape
Azidothymidine promotes free radical generation by activated macrophages and hydrogen peroxide-iron-mediated oxidation in a cell-free system.
AbstractAzidothymidine (AZT) and AZT monophosphate (AZT-MP) in concentrations as low as 10 and 50 μM, respectively, promote oxidation of chemically deacetylated 2′,7′-dichlorodihydrofluorescein (DCDHF) to 2′,7′-dichlorofluorescein (DCF) by rat peritoneal macrophages activated with latex. Cells were incubated with AZT and AZT-MP for 18 h, washed out from residual AZT or AZT-MP and activated with latex for 30 or 60 min in the presence of DCDHF. Latex-activated cells oxidize DCDHF extracellularly due to release of hydrogen peroxide and low-molecular iron complexes, which is verified using catalase, desferal and the peroxidase inhibitor sodium azide. AZT and AZT-MP increase DCDHF oxidation due to additional release of hydrogen peroxide as demonstrated by catalase inhibition of DCDHF oxidation and direct H2O2 measurement. Thymidine and thymidine phosphates did not show any effect on macrophage activation. In separate experiments we evaluated the in vitro prooxidant activity of AZT, AZT-MP, AZT triphosphate (AZT-TP), AZT glucuronide (GAZT) and 3′-amino-3′-deoxythymidine (AMT) in a cell-free system using the hydrogen peroxide-iron-mediated oxidation of DCDHF. Under these conditions, AZT and AZT phosphates exhibit a prooxidant effect in concentrations as low as 100 μM. Furthermore, GAZT is a less effective prooxidant and AMT acts like an antioxidant. Thymidine did not show any effect
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