Iodine(III)‐Catalyzed Rearrangements of Imides: A Versatile Route to α,α‐Dialkylated α‐Hydroxy Carboxylamides

A tertiary hydroxy group α to a carboxyl moiety comprises a key structural motif in many bioactive substances. With the herein presented metal‐free rearrangement of imides triggered by hypervalent λ³‐iodane, an easy and selective way to gain access to such a compound class, namely α,α‐disubstituted‐α‐hydroxy carboxylamides, was established. Their additional methylene bromide side chain constitutes a useful handle for rapid diversification, as demonstrated by a series of further functionalizations. Moreover, the in situ formation of an iodine(III) species under the reaction conditions was proven. Our findings clearly corroborate that hypervalent λ³‐benziodoxolones are involved in these organocatalytic reactions.     

Coherent States and Number-Phase Uncertainty Relations

The number-phase uncertainty relations arerevisited in view of the recent discovery of a propercovariant phase observable. The high-amplitude limits ofthe coherent-state expectations of the moment operators of the phase observable are determined and thebehavior of the number-phase uncertainty product in thatlimit is investigated.     

Approximating schedules for dynamic process graphs efficiently

A model for parallel and distributed programs, the dynamic process graph (DPG), is investigated under graph-theoretic and complexity aspects. Such graphs embed constructors for parallel programs, synchronization mechanisms as well as conditional branches. They are capable of representing all possible executions of a parallel or distributed program in a very compact way. The size of this representation can be as small as logarithmic with respect to the size of any execution of the program.

In a preceding paper [A. Jakoby, et al., Scheduling dynamic graphs, in: Proc. 16th Symposium on Theoretical Aspects in Computer Science STACS'99, LNCS, vol. 1563, Springer, 1999, pp. 383–392] we have analysed the expressive power of the general model and various variants of it. We have considered the scheduling problem for DPGs given enough parallelism taking into account communication delays between processors when exchanging data. Given a DPG the question arises whether it can be executed (that means whether the corresponding parallel program has been specified correctly), and what is its minimum schedule length.

In this paper we study a subclass of dynamic process graphs called -output DPGs, which are appropriate in many situations, and investigate their expressive power. In a previous paper we have shown that the problem to determine the minimum schedule length is still intractable for this subclass, namely this problem is -complete as is the general case. Here we will investigate structural properties of the executions of such graphs. A natural graph-theoretic conjecture that executions must always split into components that are isomorphic to subgraphs turns out to be wrong. We are able to prove a weaker property. This implies a quadratic upper bound on the schedule length that may be necessary in the worst case, in contrast to the general case, where the optimal schedule length may be exponential with respect to the size of the representing DPG. Making this bound constructive, we obtain an approximation to a -complete problem. Computing such a schedule and then executing the program can be done on a parallel machine in polynomial time in a highly distributive fashion.     

A four-level “Ξ-system”: Exact solvability and effective evolution operators via multiple scales

Properties of a four-level atomic system interacting with one and two modes of the electromagneticfield in a “Ξ”-configuration are investigated. By linearization of the Hamiltonians we show that the corresponding mathematical models are exactly solvable. To obtain simpler effective Hamiltonians the perturbative method of multiple scales is applied. The lowest-order corrections to the resulting effective evolution operators are also calculated.     

N‐{3‐[(2‐Ammonioethyl)amino]propyl}ethane‐1,2‐diaminium tris(trifluoromethanesulfonate): a salt of a folded triply protonated tetramine

The structure of a trifluoromethanesulfonate salt of a nontypical triply protonated linear tetramine, C₇H₂₃N₄³⁺·3CF₃SO₃⁻, with a layered crystal structure is presented. One N atom remains unprotonated. The conformation of the cation is enforced by intra‐ and intermolecular hydrogen bonds. The crystal structure is built of ca 10 Å deep layers, within which cations and anions are hydrogen bonded. Each layer is only weakly bound to its neighbours. This study shows a rare example of an unsymmetrically protonated polyamine and the relation between the lack of protonation, intramolecular hydrogen bonding and the conformation of the cation.     

Template atom transfer radical polymerization of a diaminopyrimidine‐derivatized monomer in the presence of a uracil‐containing polymer

Uracil‐derivatized monomer 6‐undecyl‐1‐(4‐vinylbenzyl)uracil and diaminopyrimidine‐derivatized monomer 2,6‐dioctanoylamido‐4‐methacryloyloxypyrimidine (DMP) were synthesized and polymerized by atom transfer radical polymerization (ATRP). A well‐defined, highly soluble, uracil‐containing polymer, poly[6‐undecyl‐1‐(4‐vinylbenzyl)uracil] (PUVU), was prepared in dioxane at 90 °C with CuBr/1,1,4,7,10,10‐hexamethyltriethylenetetramine as the catalyst and methyl α‐bromophenylacetate as the initiator. PUVU was further used as a template for the ATRP of DMP. The enhanced apparent rate constant of the DMP polymerization in the presence of PUVU indicated that the ATRP of DMP occurred along the PUVU template. The template polymerization produced a stable and insoluble macromolecular complex, PUVU/poly(2,6‐dioctanoylamido‐4‐methacryloyloxypyrimidine). An X‐ray diffraction study confirmed that the complex had strandlike domains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6607–6615, 2006     

In-trees and plane embeddings of outerplanar graphs

A notion of anin-tree is introduced. It is then used to characterize and count plane embeddings of outerplanar graphs. In-trees have also been applied in the study of independent vertex covers of faces in outerplanar graphs.This research was partially supported by the grant RP.I.09, from the Institute of Informatics, University of Warsaw. Hospitality of the Institute of Datalogy, University of Copenhagen where this research has been completed is gratefully acknowledged.     

Platinum metallodrug-protein binding studies by capillary electrophoresis-inductively coupled plasma-mass spectrometry: characterization of interactions between Pt(II) complexes and human serum albumin

Characterizing how platinum metallocomplexes bind to human serum albumin (HSA) is essential in evaluating anticancer drug candidates. Using cisplatin as a reference complex, the application of capillary electrophoresis (CE) to reliably assess drug/HSA interactions was validated. Since this complex is small compared to the size of the protein, the binding response could only be recognized when applying CE coupled to a (platinum) metal-specific mode of detection, namely inductively coupled plasma-mass spectrometry (ICP-MS). This coupling allowed for confirmation of a specific affinity of cisplatin and novel Pt complexes to HSA, measurement of the kinetics of binding reactions, and determination of the number of drug molecules attached to the protein. As the cisplatin/HSA molar ratio increased, the reaction rate became faster with a maximum on the kinetic curve appearing at about 50 h of incubation at 20 times excess of cisplatin. The reaction was characterized as a pseudo-first order reaction with the rate constant k = 0.003 min(-1) at 37 degrees C. When incubated with a 20-fold excess of cisplatin, HSA bound up to 10 mol of Pt per mol of the protein. This is indicative for a strong metal-protein coordination occurring at several HSA sites other than the only protein cysteine residue. Structural analogs of cisplatin, bearing aminoalcohol ligands, showed comparable protein binding reactivity and stoichiometry but a common equilibrium was not reached even after one week of incubation. Also apparent was a two-step mechanism of the binding reaction. Results demonstrated the suitability of CE-ICP-MS as a rapid assay for high-throughput studying of drug/HSA interactions.     

Structural assignment of organotin hydrides containing the oxazoline ligand

A series of triorganotin hydrides and diorganotin dihydrides containing the optically active 2-(4-isopropyl-2-oxazolinyl)-5-phenyl ligand have been characterized by means of the multinuclear low-temperature NMR investigations, the results of which are discussed. In the corresponding organotin hydrides values of the ¹J(¹H-^117/119Sn) couplings appeared to be temperature dependent, supporting an axial/equatorial position of the hydrogen attached to the tin.     

Prediction of adsorption of organic component and water vapour mixture onto activated carbon

A simple isotherm equation is derived for the adsorption of an organic component onto activated carbon in presence of water vapour. The theoretical results are compared with experimental data for toluene-water vapour-activated carbon, which were published byRipperger andGermerdonk [10].

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Vorhersage der Adsorption einer organischen Komponente und Wasserdampf an Aktivkohle

Zusammenfassung Es wird eine einfache Adsorptionsisotherme abgeleitet, welche die gleichzeitige Adsorption eines organischen Stoffes und Wasser an Aktivkohle beschreibt. Die theoretischen Ergebnisse werden mit experimentellen Resultaten vonRipperger undGermerdonk [10] für Toluol-Wasser-Aktivkohle verglichen.

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Symbols a _i adsorbate concentration in adsorbent, kg/kg of carbon - a _0i monolayer capacity, kg/kg of carbon - b _i kinetic parameter of theLangmuir equation - E _j adsorption energy in thej-th layer - i i-th component (1 — water vapour, 2 — organic compound) - j j-th layer - m number of layers - n number of adsorbed components - p partial pressure, Pa - p* saturation partial pressure, Pa - p _C water vapour partial pressure at begining of capillary condensation, Pa - surface coverage