783 research outputs found
Ionok kölcsönhatĂĄsai biolĂłgiailag aktĂv molekulĂĄkkal Ă©s szigetelĆ nano-strukturĂĄkkal = Interactions of Ions with Biologically Active Molecules and Nano Structures
Az ionterelĂ©s jelensĂ©gĂ©t elsĆkĂ©nt mutattuk ki Al2O3 anyagĂș nanokapillĂĄrisokon az ATOMKI ECR ionforrĂĄsĂĄnĂĄl. EgyszerƱ modelleket ĂĄllĂtottunk fel a jelensĂ©g Ă©rtelmezĂ©sĂ©re. KĂ©t dimenziĂłban tanulmĂĄnyoztuk a kilĂ©pĆ ionok szögeloszlĂĄsĂĄt Ă©s jelentĆs UV foton kibocsĂĄtĂĄst figyeltĂŒnk meg a kapillĂĄrisokbĂłl az ion - felĂŒlet kölcsönhatĂĄsok eredmĂ©nyekĂ©ppen. Kb. 55 mikron hosszĂș Ă©s 10 mikron ĂĄtmĂ©rĆjƱ kapillĂĄrisokat ĂĄllĂtottunk elĆ PMMA mƱanyagbĂłl, de ionterelĂ©st ilyen kis ĂĄtmĂ©rĆ-hossz arĂĄnynĂĄl nem lehetett kimutatni. KĂŒlföldi egyĂŒttmƱködĂ©sben vizsgĂĄltuk PET polimer anyagĂș kapillĂĄrisokon az ionterelĂ©shez vezetĆ feltöltĆdĂ©s dinamikĂĄjĂĄt Ă©s kimutattuk az idĆlegesen kialakulĂł feltöltött szigetek jelenlĂ©tĂ©t a kapillĂĄrisok belsejĂ©ben. VizsgĂĄltuk biolĂłgiai szempontbĂłl fontos, kis molekulĂĄk ionbombĂĄzĂĄs hatĂĄsĂĄra törtĂ©nĆ szĂ©ttöredezĆdĂ©sĂ©t, nagy Ă©s kis ĂŒtközĂ©si energiĂĄkon itthon Ă©s francia egyĂŒttmƱködĂ©sben. MegmĂ©rtĂŒk a kĂŒlönbözĆ molekulatöredĂ©kek szög- Ă©s energiaeloszlĂĄsĂĄt. Kis energiĂĄkon anizotrĂłpiĂĄk jelentek meg, melyek a lövedĂ©k ion utĂłhatĂĄsainak valamint direkt mag-mag ĂŒtközĂ©seknek tulajdonĂthatĂłk. Az aszimmetrikus vĂzmolekula esetĂ©ben ezektĆl eltĂ©rĆ tĂpusĂș anizotrĂłpia is megjelent, orientĂĄciĂłs effektusokra utalva a szĂ©ttöredezĆdĂ©st elĆidĂ©zĆ elektron befogĂĄsi folyamatokban. A hasonlĂł szerkezetƱ H2S molekula esetĂ©n nem talĂĄltunk ilyen tĂpusĂș anizotrĂłpiĂĄt. A szĂ©ttöredezĆdĂ©s mĂłdja minden vizsgĂĄlt molekulĂĄnĂĄl erĆsen fĂŒggött a lövedĂ©kion töltĂ©sĂ©tĆl, elmĂ©letileg egyelĆre nem tisztĂĄzott okokbĂłl. | We observed the ion guiding phenomena in Al2O3 capillaries for the first time at the ECR ion source in ATOMKI. We developed simple models in order to explain the phenomena. The angular distribution of the transmitted ions was studied in two dimensions. Significant UV emission was observed as a result of ion-surface interactions. Nanocapillaries with a length of 55 micron and a diameter of ~10 micron were produced of PMMA polymer. At this aspect ratio ion guiding was not found. We studied the charging-up dynamics of PET polymer capillaries within an international collaboration. Evidence for temporary, charged patches developing in the capillaries has been found. We studied ion impact induced fragmentation of small molecules of biological relevance at low and high impact energies at our institute and in French collaboration. The energy and angular distributions of the different molecule fragments were measured. Anisotropies have been found at low energies due to post collision and binary encounter effects. Another type of anisotropy was found for the asymmetric H2O molecule indicating the presence of orientation effects in the electron capture processes that lead to fragmentation. For H2S with a similar structure, such anisotropy was not found. The way of fragmentation strongly depends on the projectile charge for all the investigated molecules. This is not fully understood theoretically
Coloring Cantor sets and resolvability of pseudocompact spaces
Let us denote by the statement that , i.e. the Baire space of weight , has a coloring
with colors such that every homeomorphic copy of the Cantor set
in picks up all the colors.
We call a space {\em -regular} if it is Hausdorff and for every
non-empty open set in there is a non-empty open set such that
. We recall that a space is called {\em feebly
compact} if every locally finite collection of open sets in is finite. A
Tychonov space is pseudocompact iff it is feebly compact.
The main result of this paper is the following.
Theorem. Let be a crowded feebly compact -regular space and be
a fixed (finite or infinite) cardinal. If holds for all
then is -resolvable, i.e. contains
pairwise disjoint dense subsets. (Here is the smallest
cardinal such that does not contain many pairwise
disjoint open sets.)
This significantly improves earlier results of van Mill , resp.
Ortiz-Castillo and Tomita.Comment: 8 page
Pinning Down versus Density
The pinning down number of a topological space is the smallest
cardinal such that for any neighborhood assignment
there is a set with for all . Clearly, c.
Here we prove that the following statements are equivalent:
(1) for each cardinal ;
(2) for each Hausdorff space ;
(3) for each 0-dimensional Hausdorff space .
This answers two questions of Banakh and Ravsky.
The dispersion character of a space is the smallest
cardinality of a non-empty open subset of . We also show that if
then has an open subspace with and
, moreover the following three statements are equiconsistent:
(i) There is a singular cardinal with , i.e.
Shelah's Strong Hypothesis fails;
(ii) there is a 0-dimensional Hausdorff space such that
is a regular cardinal and ;
(iii) there is a topological space such that is a regular
cardinal and .
We also prove that
for any locally compact Hausdorff space ;
for every Hausdorff space we have and
implies ;
for every regular space we have and moreover implies
Anti-Urysohn spaces
All spaces are assumed to be infinite Hausdorff spaces. We call a space
"anti-Urysohn" AU in short iff any two non-emty regular closed sets in it
intersect. We prove that
for every infinite cardinal there is a space of size
in which fewer than many non-empty regular closed
sets always intersect;
there is a locally countable AU space of size iff .
A space with at least two non-isolated points is called "strongly
anti-Urysohn" SAU in short iff any two infinite closed sets in it
intersect. We prove that
if is any SAU space then ;
if then there is a separable, crowded,
locally countable, SAU space of cardinality ; \item if Cohen reals are added to any ground model then in the extension there
are SAU spaces of size for all ;
if GCH holds and are uncountable regular
cardinals then in some CCC generic extension we have ,
, and for every cardinal there is an SAU space of cardinality .
The questions if SAU spaces exist in ZFC or if SAU spaces of cardinality can exist remain open
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