Flux and fluence dependence of disorder produced during implantation of 11B in silicon

The flux and fluence dependence of disorder produced in silicon during the implantation of ¹¹B has been investigated at room temperature, -50°C. and -120°C. Implantations were carried out with 200 keV ¹¹B ions using current densities in the range from 0.06μA/cm² to 15μA/cm², and the disorder monitored by measuring the energy spectra of backscattered protons which were incident on the sample at 450 keV parallel to a (110) axis. Significant differences in the dependence of the disorder on ¹¹B flux and fluence were observed between the implantations performed at room temperature and those carried out at the two lower temperatures.     

Threshold Visual Cryptography Schemes with Specified Whiteness Levels of Reconstructed Pixels

In 1994, Naor and Shamir introduced an unconditionally secure method for encoding black and white images. This method, known as a threshold visual cryptography scheme (VCS), has the benefit of requiring no cryptographic computation on the part of the decoders. In a -VCS, a share, in the form of a transparency, is given to ">n users. Any ">k users can recover the secret simply by stacking transparencies, but ">k-1 users can gain no information about the secret whatsoever.In this paper, we first explore the issue of contrast, by demonstrating that the current definitions are inadequate, and by providing an alternative definition. This new definition motivates an examination of minimizing pixel expansion subject to fixing the VCS parameters ">h and ">l. New bounds on pixel expansion are introduced, and connections between these bounds are examined. The best bound presented is tighter than any previous bound. An analysis of connections between (2, ">n) schemes and designs such as BIBD's, PBD's, and (">r, )-designs is performed. Also, an integer linear program is provided whose solution exactly determines the minimum pixel expansion of a (2, ">n)-VCS with specified ">h and >l.     

Formation of inclusion organoactinide complexes with boron-containing macrocycles

Reaction of the organoactinide complexes (C5Me5)2AnMe2 (An = Th, U) with catecholborane yields an inclusion complex where the actinide is encapsulated inside a 15-membered, hexaoxo, trianionic macrocycle built from alternating catechol and catecholborate fragments. In the presence of LiOH, a dimer of two encapsulated actinide macrocycles is formed. The X-ray molecular structure for all the complexes is presented.     

Aluminium und Aluminiumlegierungen

Ohne Zusammenfassung     

Solvent effects in the polymerization of propylene catalyzed by octahedral complexes

The effect of solvents (toluene, dichloromethane, and hexane) was studied on the polymerization of propylene with the octahedral complexes bis(trimethylsilyl)benzamidinate titanium dichloride(a), bis(acetylacetonate) titanium dichloride(b), and bis(diethylamino) titanium di‐2‐(diphenylphosphanylamino)pyridine as catalytic precursors and methylalumoxane as the cocatalyst. For comparison, the polymerization was also performed in plain liquid propylene without the addition of any solvent. The obtained polymers were fractionated by refluxing hexane. The activity of the complexes and the molecular weights and tacticities of the whole polymers and their different fractions were the studied parameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4505–4516, 2005     

Variational problems with obstacles and integral constraints

Various problems in mathematics and physics can be formulated in terms of a variational problem with obstacles and integral constraints, e.g. finding a surface of minimal area with prescribed volume in a bounded region.We are concerned with the regularity of solutions of variational problems: We show that the minima of a variational integral under all Sobolewfunctions with prescribed boundary values, lying between two obstacles, and fulfilling some integral constraints, are bounded and Hölder-continuous. We do not assume any differentiability or convexity of the integrand, but only a Caratheodory and a growth condition.This research has been supported by the Sonderforschungsbereich 72 of the Deutsche Forschungsgemeinschaft.     

Ein Verfahren zur Berechnung der Dampfzusammensetzung von ternären flüssigen Systemen

A simple method for calculating the vapor composition in ternary liquid systems is described and experimentally verified. Starting from the differential equation derived for curves of constant relative fugacity of two components (_ik=const) a relation is derived for the estimation of these curves in the concentration triangle. The _ik-values are determined as the finite points of curves _ik=const from the data of the vapor-liquid composition of the binary systems.

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Mit 3 Abbildungen     

Zur Berechnung des Dampf—Flüssigkeits-Gleichgewichtes in ternären flüssigen Systemen

A simple method for predicting ternary vapor—liquid equilibria is presented and experimentally verified. The method is based on the solution of algebraic equations derived by the integration of the differential equations characterizing the dependence of the equilibrium properties of the ternary system on the state variables with the assumption that the partial derivates enter as constants. The values of the partial derivates are approximately evaluated from the binary experimental data.     

Orchestrating the Biosynthesis of an Unnatural Pyrrolysine Amino Acid for Its Direct Incorporation into Proteins Inside Living Cells

We here report the construction of an E. coli expression system able to manufacture an unnatural amino acid by artificial biosynthesis. This can be orchestrated with incorporation into protein by amber stop codon suppression inside a living cell. In our case an alkyne‐bearing pyrrolysine amino acid was biosynthesized and incorporated site‐specifically allowing orthogonal double protein labeling.