22 research outputs found
Stein structures and holomorphic mappings
We prove that every continuous map from a Stein manifold X to a complex
manifold Y can be made holomorphic by a homotopic deformation of both the map
and the Stein structure on X. In the absence of topological obstructions the
holomorphic map may be chosen to have pointwise maximal rank. The analogous
result holds for any compact Hausdorff family of maps, but it fails in general
for a noncompact family. Our main results are actually proved for smooth almost
complex source manifolds (X,J) with the correct handlebody structure. The paper
contains another proof of Eliashberg's (Int J Math 1:29--46, 1990) homotopy
characterization of Stein manifolds and a slightly different explanation of the
construction of exotic Stein surfaces due to Gompf (Ann Math 148 (2):619--693,
1998; J Symplectic Geom 3:565--587, 2005). (See also the related preprint
math/0509419).Comment: The original publication is available at http://www.springerlink.co
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