37 research outputs found
Nucleon Charge and Magnetization Densities from Sachs Form Factors
Relativistic prescriptions relating Sachs form factors to nucleon charge and
magnetization densities are used to fit recent data for both the proton and the
neutron. The analysis uses expansions in complete radial bases to minimize
model dependence and to estimate the uncertainties in radial densities due to
limitation of the range of momentum transfer. We find that the charge
distribution for the proton is significantly broad than its magnetization
density and that the magnetization density is slightly broader for the neutron
than the proton. The neutron charge form factor is consistent with the Galster
parametrization over the available range of Q^2, but relativistic inversion
produces a softer radial density. Discrete ambiguities in the inversion method
are analyzed in detail. The method of Mitra and Kumari ensures compatibility
with pQCD and is most useful for extrapolating form factors to large Q^2.Comment: To appear in Phys. Rev. C. Two new figures and accompanying text have
been added and several discussions have been clarified with no significant
changes to the conclusions. Now contains 47 pages including 21 figures and 2
table
DNA from Plant leaf Extracts: A Review for Emerging and Promising Novel Green Corrosion Inhibitors.
With growing global awareness and concern for environmental protection through
the use of less hazardous and environmentally-friendly extracts of plant origin,
there has been a plethora of green corrosion inhibitors research with far reaching
contributions to the science of corrosion prevention and control. Attention has
increasingly turned towards green corrosion inhibitors, compounds of natural
origin with anti-oxidant activity towards metals and their alloys. Green inhibitors
have been investigated for their corrosion and adsorption properties with good
results. The findings from these research works provide evidence of the
adsorption behavior of green inhibitors which was confirmed by the adsorption
isotherms that were proposed. Adsorption is the first step of any surface reaction
and since corrosion is a surface phenomenon the effectiveness of green corrosion
inhibitors is related to their ability to adsorb on metal surfaces. This review
proposes the potential of plant dna as an emerging and promising novel inhibitor
for mild steel. It begins with a list of plants that have been used in studies to
determine corrosion inhibition properties and moves on to establish the adsorption
behavior of bio macromolecules; protein, polysaccharides (chitosan) and dna. It
reviews studies and investigation of dna interaction and adsorption on inorganic
surfaces before focusing on the use of salmon (fish) sperm dna and calf thymus
gland dna as green corrosion inhibitors for mild steel. It concludes that plant dna
is a promising candidate for green corrosion inhibitor given the similarity between
the plant and animal dna structure and function, and the fact that the use of plant
is more environmentally sustainable than animal-based produc
Redes epóxi/amina alifáticas com perspectivas para aplicações cardiovasculares. Propriedades biológicas in vitro
Este trabalho descreve as propriedades biológicas in vitro de três redes epoxídicas à base do éter diglicidílico do glicerol (DGEG) curadas com poli(oxipropileno) diamina (D230), isoforona diamina (IPD) e 4,4'-diamino-3,3'-dimetil-diciclohexilmetano (3DCM). As interações biológicas entre os polímeros e o sangue foram estudadas por ensaios biológicos in vitro. Estudos de adsorção de proteínas, adesão de plaquetas, atividade do lactato desidrogenase (LDH) e propriedades de tromboresistência estão apresentados. Os ensaios de adsorção de proteínas na superfície dos polímeros mostrou que as redes epoxídicas adsorvem mais albumina do que fibrinogênio. Os resultados relacionados à adesão de plaquetas, atividade do lactato hidrogenase e propriedades de tromboresistência indicaram que as redes DGEG/IPD e DGEG/3DCM exibem comportamento hemocompatível. Desta maneira, assumimos que estes polímeros epoxídicos são materiais compatíveis com o sangue
High energy angular distribution measurements of the exclusive deuteron photodisintegration reaction
The Effect of Radiolabeling of Human Fibrinogen on Its Adsorption Behaviour on a Polystyrene Surface
Human fibrinogen (HFB) was labeled with different radioactive labels (Technetium -99m and Iodine -125) in various ways. Characterization by chromatographic and electrophoretic methods did not show differences between the labeled and the nonlabeled proteins. The effect of the label and the labeling method on the adsorption behaviour of 99(m)Tc and 125I labeled HFB at a polystyrene surface was investigated. In all cases labeled HFB showed preferential adsorption as compared to nonlabeled HFB. The preferential adsorption was expressed in terms of a factor Φ, which will be 1, when no preferential adsorption occurs. 99(m)Tc - and 125I - HFB showed Φ values from 1.48 - 1.88. It is concluded that only meaningful adsorption experiments with labeled proteins can be performed when the possible occurrence of preferential adsorption has been investigated by appropriate methods. The results of prior work on protein adsorption at biomaterials using radiolabeled proteins have to be reconsidered.</p
Interactions of Apolipoproteins AI, AII, B and HDL, LDL, VLDL with Polyurethane and Polyurethane-PEO Surfaces
The lipoproteins
(HDL, LDL, VLDL) are important components of blood
present in high concentration. Surprisingly, their role in blood-biomaterial
interactions has been largely ignored. In previous work apolipoprotein
AI (the main protein component of HDL) was identified as a major constituent
of protein layers adsorbed from plasma to biomaterials having a wide
range of surface properties, and quantitative data on the adsorption
of apo AI to a biomedical grade polyurethane were reported. In the
present communication quantitative data on the adsorption of apo AI,
apo AII and apoB (the latter being a constituent of LDL and VLDL),
as well as the lipoprotein particles themselves (HDL, LDL, VLDL),
to a biomedical segmented polyurethane (PU) with and without an additive
containing poly(ethylene oxide) (material referred to as PEO) are
reported. Using radiolabeled apo AI, apo AII, and apoB, adsorption
levels on PU from buffer at a protein concentration of 50 μg/mL
were found to be 0.34, 0.40, and 0.14 μg/cm<sup>2</sup> (12,
23, and 0.25 nmol/cm<sup>2</sup>) respectively. Adsorption to the
PEO surface was <0.02 μg/cm<sup>2</sup> for all three apolipoproteins
demonstrating the strong protein resistance of this material. In contrast
to the apolipoproteins, significant amounts of the lipoproteins were
found to adsorb to the PEO as well as to the PU surface. X-ray photoelectron
spectra, following exposure of the surfaces to the lipoproteins, showed
a strong phosphorus signal, confirming that adsorption had occurred.
It therefore appears that a PEO-containing surface that is resistant
to apolipoproteins may be less resistant to the corresponding lipoproteins