9,724 research outputs found
Fabrication and testing of a multifunctional SiO2@ZnO core-shell nanospheres incorporated polymer coating for sustainable marine transport
We report the development of a coating system relying on the incorporation of SiO2@ZnO coreshel nanospheres in polyurethane media as a novel approach to achieve longevity and sustainability in marine transport. This polymeric coating showed significant improvement in surface abrasion resistance, the transition from a hydrophilic state to a hydrophobic state (~125.2± 2°), improved antifungal, antibacterial and antialgae effects which make the proposed
coating ideal to protect steel surfaces against biofouling. To substantiate our claims, we performed X-Ray diffraction, Transmission electron microscopy, Fourier transform infrared spectroscopy, scanning acoustic microscopy, Thermogravimetric analysis (TGA), contact angle measurements, antimicrobial (antialgal, antibacterial, antifungal) tests and Taber abrasion tests (ASTM D1044 and D4060) to highlight the mechanical and biological functionality as well as the bonding configuration of this coating. The wear analysis of the Taber abraded coating using SEM and optical microscopy showed significant improvement in the adhesion and shear resistance achieved by the SiO2@ZnO core-shell nanospheres incorporated PU coating which was a contrasting feature
compared to using PU alone. The overall investigations we performed led us to find out that the addition of 4% (wt.) SiO2@ZnO core-shell nanoparticles to the PU media deposited on the low carbon steel surface demonstrated remarkable antimicrobial performance with almost no bacterial growth, significant reductions in growth for algae to about 9.2% and fungus to about 10.2%
Study of Radiative Leptonic D Meson Decays
We study the radiative leptonic meson decays of D^+_{(s)}\to
\l^+\nu_{\l}\gamma (\l=e,\mu,\tau), and D^0\to
\l^+\l^-\gamma () within the light front quark model. In the standard
model, we find that the decay branching ratios of , and
are (), (), and
(), and that of D^0\to\l^+\l^-\gamma (\l=e,\mu) and
are and ,
respectively.Comment: 23 pages, 6 Figures, LaTex file, a reference added, to be published
in Mod. Phys. Lett.
Effects of Hot-Pressing Parameters and Wax Content on the Properties of Fiberboard Made from Paper Mill Sludge
Primary sludge combined with 20% secondary sludge was used for the manufacture of fiberboard. A factorial design was carried out to determine the effects of panel density, pressing temperature and time, and wax level on the panel properties of fiberboard. Two levels were employed for each of the four variables, and the panel dimensional stability and mechanical properties were analyzed using Design-Expert software. The statistical analysis indicated that internal bonding (IB) was significantly affected by panel density, pressing temperature, and their interaction. Pressing time and wax level were not directly related to IB. Similarly, modulus of rupture (MOR) was dependent strongly on panel density, pressing temperature, and their interaction, but was not affected by pressing time and wax level. The effect of panel density on modulus of elasticity (MOE) was as strong as on MOR, but the effect of pressing temperature was weaker on MOE than on MOR. MOE was also related to pressing time, but not to wax level. Thickness swelling (TS) was not affected by panel density, but it was significantly dependent on pressing temperature and time. Unexpectedly, wax level did not have significant impact on TS
Extraction and Antioxidant Activity of Phenolic Compounds from Okra Flowers
Purpose: To investigate the extraction and antioxidant activity of phenolic compounds from Okra flowers.Methods: The phenolic compounds in Okra flowers was obtained by traditional solvent extraction method and determined by Folin-Ciocalteu (FC) method. The extraction was optimized using response surface methodology (RSM). The antioxidant activity of the obtained extract was determined by 1,1- diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and reducing power assays.Results: The optimal extraction conditions were as follows: extraction time, 2.5 h; ethanol concentration, 59.16 %; extraction temperature, 73.91 °C; and liquid-solid ratio, 20 mL/g. The mean total phenolics yield under the optimum conditions was 40.77±0.83 mg GAE /g material, which is near the predicted value of 44.20 mg GAE /g material. The total phenolics of the extract was an effective scavenger in quenching DPPH radicals. A linear correlation between the concentration of the total phenolics extract and reducing power was observed with a correlation coefficient (r2) of 0.9973.Conclusion: Using RSM, the extraction of total phenolics in okra flowers has been optimized. The extract exhibits a strong DPPH radical scavenging activity and reducing power, which makes it a potential functional ingredient in the food and pharmaceutical industries.Keywords: Okra flowers, Extraction, Response surface methodology, Phenolics, Antioxidan
A systematic study of Zr and Sn isotopes in the Relativistic Mean Field theory
The ground-state properties of Zr and Sn isotopes are studied within the
relativistic mean field theory. Zr and Sn isotopes have received tremendous
attention due to various reasons, including the predicted giant halos in the
neutron-rich Zr isotopes, the unique feature of being robustly spherical in the
region of Sn Sn and the particular interest of Sn
isotopes to nuclear astrophysics. Furthermore, four (semi-) magic neutron
numbers, 40, 50, 82 and 126, make these two isotopic chains particularly
important to test the pairing correlations and the deformations in a
microscopic model. In the present work, we carry out a systematic study of Zr
and Sn isotopes from the proton drip line to the neutron drip line with
deformation effects, pairing correlations and blocking effects for nuclei with
odd number of neutrons properly treated. A constrained calculation with
quadrupole deformations is performed to find the absolute minimum for each
nucleus on the deformation surface. All ground-state properties, including the
separation energies, the odd-even staggerings, the nuclear radii, the
deformations and the single-particle spectra are analyzed and discussed in
detail.Comment: the final version to appear in Modern Physics Letters A. more
figures, discussions, and references added. the data remain unchange
Shock Induced Order-disorder Transformation in Ni3Al
The Hugoniot of Ni3Al with L12 structure is calculated with an equation of
state (EOS) based on a cluster expansion and variation method from first
principles. It is found that an order-disorder transition occurs at a shock
pressure of 205GPa, corresponding to 3750K in temperature. On the other hand,
an unexpected high melting temperature about 6955K is obtained at the same
pressure, which is completely different from the case at ambient pressure where
the melting point is slightly lower than the order-disorder transition
temperature, implying the high pressure phase diagram has its own
characteristics. The present work also demonstrates the configurational
contribution is more important than electronic excitations in alloys and
mineral crystals within a large range of temperature, and an EOS model based on
CVM is necessary for high pressure metallurgy and theoretical Earth model.Comment: 14 pages, 5 figure
Characterisation of individual aerosol particles collected during a haze episode in Incheon, Korea using the quantitative ED-EPMA technique
A quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), called low-Z particle EPMA, was used to analyse individual aerosol particles collected in Incheon, Korea on 13–18 October 2008 (a typical haze episode occurred from 15 to 18 October). Overall 3600 individual particles in PM<sub>2.5-10</sub> and PM<sub>1.0-2.5</sub> fractions from 12 aerosol samples collected on haze and non-haze days were analysed. The analysed particles were classified, based on their X-ray spectral data together with their secondary electron images. The major particle types included organic carbon (OC), elemental carbon (EC), sea-salt, mineral dust (such as aluminosilicate, SiO<sub>2</sub>, CaCO<sub>3</sub>/CaMgCO<sub>3</sub>, etc.), (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>/NH<sub>4</sub>HSO<sub>4</sub>-containing, K-containing, Fe-rich and fly ash particles. Their relative number abundance results showed that OC particles were significantly increased while sea-salts and mineral dust particles were significantly decreased (especially in PM<sub>1.0-2.5</sub> fraction) when haze occurred. For the other particle types (except Fe-rich particles in PM<sub>2.5-10</sub> fraction), there were no significant differences in their relative abundances between haze and non-haze samples. On non-haze days, the nitrate-containing reacted sea-salt and mineral dust particles in PM<sub>1.0-2.5</sub> fraction significantly outnumbered the sulfate-containing ones, whereas it was the reverse on haze days, implying that on haze days there were special sources or formation mechanisms for fine aerosol particles (≤2.5 μm in aerodynamic diameter). The emission of air pollutants from motor vehicles and stagnant meteorological conditions, such as low wind speed and high relative humidity, might be responsible for the elevated level of OC particles on haze days
Insight into mechanics of AFM tip-based nanomachining: bending of cantilevers and machined grooves
Atomic force microscope (AFM) tip-based nanomachining is currently the object of intense research investigations. Values of the load applied to the tip at the free end of the AFM cantilever probe used for nanomachining are always large enough to induce plastic deformation on the specimen surface contrary to the small load values used for the conventional contact mode AFM imaging. This study describes an important phenomenon specific for AFM nanomachining in the forward direction: under certain processing conditions, the deformed shape of the cantilever probe may change from a convex to a concave orientation. The phenomenon can principally change the depth and width of grooves machined, e.g. the grooves machined on a single crystal copper specimen may increase by 50% on average following such a change in the deformed shape of the cantilever. It is argued that this phenomenon can take place even when the AFM-based tool is operated in the so-called force-controlled mode. The study involves the refined theoretical analysis of cantilever probe bending, the analysis of experimental signals monitored during the backward and forward AFM tip-based machining and the inspection of the topography of produced grooves
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