1,367 research outputs found
Food waste materials appear efficient and low-cost adsorbents for the removal of organic and inorganic pollutants from wastewater
In recent studies, the adsorption capacity of several food waste materials has been assessed by performing adsorption experiments in heterogeneous operating conditions. In a latest study, the efficiency of such food waste materials for the removal of metals and metalloids from complex multi-element
solutions was evaluated in homogeneous experimental conditions, which allowed comparing the adsorption capacities of the individual adsorbents. Considering the high efficiency of the examined low-cost adsorbents for the removal of inorganic pollutants, preliminary studies were conducted in our lab for assessing the potential of the investigated food waste materials to adsorb volatile organic compounds from a real polluted matrix of leachate. Some recent
studies have shown the efficiency of low cost materials for the removal of industrial organic dyes, polycyclic aromatic hydrocarbons and phenolic compounds. However, the food waste adsorbents’ efficiency for the removal of volatile organic compounds was not investigated. Our preliminary studies showed good adsorption capacities of the examined food waste materials for aliphatic and aromatic hydrocarbons. Therefore, it is worth to carry out further studies about volatile organic compounds’ removal by food waste adsorbents
Thermodynamics of Paracrystalline Silicon
Fluctuation microscopy experiments have shown that the as-deposited structure of amorphous silicon thin films is paracrystalline. A paracrystal consists of small (< 3 nm in diameter) topologically crystalline grains separated by a disordered matrix. Here the authors consider the thermodynamics of paracrystalline silicon as a function of the grain size and the temperature. They offer a simple model that qualitatively explains the observed metastability of the ordered structure at low temperature (300 K), the relaxation towards a more disordered structure at intermediate temperatures (600 K), and the recrystallization at high temperatures (1,000 K)
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An ITPR1 gene deletion causes SCA15 and 16; a genetic, clinical and radiological description
Spinocerebellar ataxia (SCA) 15/16 is an autosomal dominantly inherited, almost pure cerebellar ataxia, which shows slow or no progression. (It has been designated variably SCA15 and SCA 16; we refer to it here as SCA15/16 to avoid confusion). Deletions in the inositol 1, 4, 5-triphosphate receptor 1 (ITPR1) on chromosome 3 have been shown to cause SCA15/16 in six families worldwide to date, with one further Japanese family identified as having an ITPR1 point mutation. We present a previously unreported SCA15/16 kindred. We describe the clinical phenotype of the family in detail; affected subjects display a remarkably slow, almost pure cerebellar syndrome. We also present genetic analyses for all subjects and longitudinal MRI data for one affected subject. Genetic analysis shows a deletion of 346,487bp in ITPR1 (the second largest ITPR1 deletion reported to date), suggesting SCA15 is due to a loss of ITPR1 function, and western blotting of lymphoblastoid cell line protein confirms reduced ITPR1 protein levels. Serial MRIs show progressive midline cerebellar atrophy with mild inferior parietal and temporal cortical volume loss in the absence of clinical disease progression. We believe that genetic testing for SCA15/16 should become a routine DNA screen available in all Neurogenetics clinics, which is likely to lead to an increased rate of the diagnosis. Familiarity with the phenotype is therefore important for all neurologists
Intrinsic thermal vibrations of suspended doubly clamped single-wall carbon nanotubes
We report the observation of thermally driven mechanical vibrations of
suspended doubly clamped carbon nanotubes, grown by chemical vapor deposition
(CVD). Several experimental procedures are used to suspend carbon nanotubes.
The vibration is observed as a blurring in images taken with a scanning
electron microscope. The measured vibration amplitudes are compared with a
model based on linear continuum mechanics.Comment: pdf including figures, see:
http://www.unibas.ch/phys-meso/Research/Papers/2003/NT-Thermal-Vibrations.pd
Quantum Effects in the Mechanical Properties of Suspended Nanomechanical Systems
We explore the quantum aspects of an elastic bar supported at both ends and
subject to compression. If strain rather than stress is held fixed, the system
remains stable beyond the buckling instability, supporting two potential
minima. The classical equilibrium transverse displacement is analogous to a
Ginsburg-Landau order parameter, with strain playing the role of temperature.
We calculate the quantum fluctuations about the classical value as a function
of strain. Excitation energies and quantum fluctuation amplitudes are compared
for silicon beams and carbon nanotubes.Comment: RevTeX4. 5 pages, 3 eps figures. Submitted to Physical Review Letter
Viscous damping of nanobeam resonators: humidity, thermal noise and the paddling effect
The nanobeam resonator is the key mechanical component in the
nano-electromechanical system. In addition to its high frequency originating
from its low dimension, the performance is significantly influenced by the
circumstances, especially at nanoscale where a large surface area of the
material is exposed. Molecular dynamics simulations and theoretical analysis
are used for a quantitative prediction on the damping behavior, such as the
critical damping condition and lifetime, of nanobeam resonators that directly
maps the fluid-structure properties and interaction information into dynamical
behaviors. We show here how the humidity defines the critical damping condition
through viscous forces, marking the transition from under-damping to
over-damping regime at elevated humidity. Novel phenomena such as the thermal
fluctuation and paddling effects are also discussed.Comment: 15 pages, 5 figure
Characterization of defect structures in nanocrystalline materials by X-ray line profile analysis
X-ray line profile analysis is a powerful alternative tool for determining dislocation densities, dislocation type, crystallite and subgrain size and size-distributions, and planar defects, especially the frequency of twin boundaries and stacking faults. The method is especially useful in the case of submicron grain size or nanocrystalline materials, where X-ray line broadening is a well pronounced effect, and the observation of defects with very large density is often not easy by transmission electron microscopy. The fundamentals of X-ray line broadening are summarized in terms of the different qualitative breadth methods, and the more sophisticated and more quantitative whole pattern fitting procedures. The efficiency and practical use of X-ray line profile analysis is shown by discussing its applications to metallic, ceramic, diamond-like and polymer nanomaterials
Quantum theory of electromechanical noise and momentum transfer statistics
A quantum mechanical theory is developed for the statistics of momentum
transferred to the lattice by conduction electrons. Results for the
electromechanical noise power in the semiclassical diffusive transport regime
agree with a recent theory based on the Boltzmann-Langevin equation. All
moments of the transferred momentum are calculated for a single-channel
conductor with a localized scatterer, and compared with the known statistics of
transmitted charge.Comment: 10 pages, 2 figure
Extinctions and Correlations for Uniformly Discrete Point Processes with Pure Point Dynamical Spectra
The paper investigates how correlations can completely specify a uniformly
discrete point process. The setting is that of uniformly discrete point sets in
real space for which the corresponding dynamical hull is ergodic. The first
result is that all of the essential physical information in such a system is
derivable from its -point correlations, . If the system is
pure point diffractive an upper bound on the number of correlations required
can be derived from the cycle structure of a graph formed from the dynamical
and Bragg spectra. In particular, if the diffraction has no extinctions, then
the 2 and 3 point correlations contain all the relevant information.Comment: 16 page
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