3,993 research outputs found
On how good DFT exchange-correlation functionals are for H bonds in small water clusters: Benchmarks approaching the complete basis set limit
The ability of several density-functional theory (DFT) exchange-correlation
functionals to describe hydrogen bonds in small water clusters (dimer to
pentamer) in their global minimum energy structures is evaluated with reference
to second order Moeller Plesset perturbation theory (MP2). Errors from basis
set incompleteness have been minimized in both the MP2 reference data and the
DFT calculations, thus enabling a consistent systematic evaluation of the true
performance of the tested functionals. Among all the functionals considered,
the hybrid X3LYP and PBE0 functionals offer the best performance and among the
non-hybrid GGA functionals mPWLYP and PBE1W perform the best. The popular BLYP
and B3LYP functionals consistently underbind and PBE and PW91 display rather
variable performance with cluster size.Comment: 9 pages including 4 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.htm
Efficacy and Residue Comparisons between Two Slow-release Formulations of Fluridone
Residue profiles and efficacy of Avast and Sonar, two slow
release pellet formulations of fluridone {1-methyl-3-phenyl-5-
[3-(trifluoromethyl)phenly]-4(1H)-pyridinone}, were compared
in outdoor tanks. Hydrilla (Hydrilla verticillata (L.f.)
Royle) and southern naiad (Najas guadalupensis (Sprengel)
Magnus) were treated with a split application of 6, 12, 18 and
24 μg/l a.i. fluridone and the concentrations of both formulations
compared over a 134-day period. Both pellet formulations
exhibited very similar residues over time for each
respective treatment, resulted in peak concentrations of fluridone
40 to 50 days after application, and effectively and
similarly controlled southern naiad and hydrilla at all rates
tested by 92 days after initial application. (PDF contains 3 pages.
Self-Organized Dynamical Equilibrium in the Corrosion of Random Solids
Self-organized criticality is characterized by power law correlations in the
non-equilibrium steady state of externally driven systems. A dynamical system
proposed here self-organizes itself to a critical state with no characteristic
size at ``dynamical equilibrium''. The system is a random solid in contact with
an aqueous solution and the dynamics is the chemical reaction of corrosion or
dissolution of the solid in the solution. The initial difference in chemical
potential at the solid-liquid interface provides the driving force. During time
evolution, the system undergoes two transitions, roughening and
anti-percolation. Finally, the system evolves to a dynamical equilibrium state
characterized by constant chemical potential and average cluster size. The
cluster size distribution exhibits power law at the final equilibrium state.Comment: 11 pages, 5 figure
Sensitivity of nonlinear photoionization to resonance substructure in collective excitation
Collective behaviour is a characteristic feature in many-body systems, important for developments in fields such as magnetism, superconductivity, photonics and electronics. Recently, there has been increasing interest in the optically nonlinear response of collective excitations. Here we demonstrate how the nonlinear interaction of a many-body system with intense XUV radiation can be used as an effective probe for characterizing otherwise unresolved features of its collective response. Resonant photoionization of atomic xenon was chosen as a case study. The excellent agreement between experiment and theory strongly supports the prediction that two distinct poles underlie the giant dipole resonance. Our results pave the way towards a deeper understanding of collective behaviour in atoms, molecules and solid-state systems using nonlinear spectroscopic techniques enabled by modern short-wavelength light sources
Investigation of complete and incomplete fusion in Li+Sn reaction around Coulomb barrier energies
The complete and incomplete fusion cross sections for Li+Sn
reaction were measured using online and offline characteristic -ray
detection techniques. The complete fusion (CF) cross sections at energies above
the Coulomb barrier were found to be suppressed by 26 \% compared to the
coupled channel calculations. This suppression observed in complete fusion
cross sections is found to be commensurate with the measured total incomplete
fusion (ICF) cross sections. There is a distinct feature observed in the ICF
cross sections, i.e., -capture is found to be dominant than
-capture at all the measured energies. A simultaneous explanation of
complete, incomplete and total fusion (TF) data was also obtained from the
calculations based on Continuum Discretized Coupled Channel method with short
range imaginary potentials. The cross section ratios of CF/TF and ICF/TF
obtained from the data as well as the calculations showed the dominance of ICF
at below barrier energies and CF at above barrier energies.Comment: 9 pages, 8 figure
Detection of Food-Borne Pathogens Using Nanozyme Technology
The recurrent outbreak of E. coli necessitates the need of rapid and sensitive technology to detect bacteria in the food samples. E. coli O157:H7 is infectious at very low CFU counts (10-100 viable cells). Herein, we report a unique combination of magnetic and plasmonic properties in a single nanoplatform, which have superior peroxidase-like activity. This new nanosensor platform, magneto-plasmonic nanosensor (MPnS), is composed of superparamagnetic iron oxide nanoparticles (IONPs) and gold nanoparticles (GNPs) and stabilized with polyacrylic acid polymer, providing surface -COOH functional groups. By using EDC/NHS bioconjugation chemistry, the surface of MPnS is decorated with E. coli O157:H7-specific antibodies. We compared the catalytic activities of MPnS with that of GNPs, IONPs and traditional HRP and calculated Michaelis-Menten kinetics, which showed highest catalytic activity for MPnS. The ELISA-like experiments were performed using MPnS to detect E. coli within 30 min with higher sensitivity. We extended this detection study using milk and spinach samples. Various spectrophotometric and colorimetric experimental results in the specific detection of E. coli will be detailed in this presentation
- …