Cardinality of height function’s range in case of maximally many rectangular islands — computed by cuts

We deal with rectangular m×n boards of square cells, using the cut technics of the height function. We investigate combinatorial properties of this function, and in particular we give lower and upper bounds for the number of essentially different cuts. This number turns out to be the cardinality of the height function’s range, in case the height function has maximally many rectangular islands.     

Cyclodextrin knowledgebase a web-based service managing CD-ligand complexation data

Cyclodextrins are cyclic oligosaccharides that are able to form water-soluble inclusion complexes with small molecules. Because of their complexing ability, they are widely applied in food, pharmaceutical and chemical industries. In this paper we describe the development of a free web-service, Cyclodextrin KnowledgeBase: (http://www.cyclodextrin.net). The database contains four modules: the Publication, Interaction, Chirality and Analysis Modules. In the Publication Module, almost 50,000 publication details are collected that can be retrieved by text search. In the Interaction and Chirality Modules relevant literature data on cyclodextrin complexation and chiral recognition are collected that can be retrieved by both text and structural searches. Moreover, in the Analysis Module, the geometries of small molecule-cyclodextrin complexes can be predicted using molecular docking tools in order to explore the structures and interaction energies of the inclusion complexes. Complex geometry prediction is made possible by the built-in database of 95 cyclodextrin derivatives, where the 3D structures as well as the partial charges are calculated and stored for further utilization. The use of the database is demonstrated by several examples.     

Iridium–Ruthenium Cluster Complexes with SnPh<Subscript>3</Subscript> Ligands from the Reaction of IrRu<Subscript>3</Subscript>(CO)<Subscript>13</Subscript>(μ-H) with HSnPh<Subscript>3</Subscript>

The reaction of IrRu₃(CO)₁₃(μ-H), 1 with HSnPh₃ in hexane solvent at reflux has provided the new mixed metal cluster compounds Ir₂Ru₂(CO)₁₁(SnPh₃)(μ-H)₃, 2 and IrRu₃(CO)₁₁(SnPh₃)₃(μ-H)₄, 3 containing SnPh₃ ligands. Compound 2 which was obtained in low yield (3%) contains one SnPh₃, two iridium atoms and two ruthenium atoms. The increase in the number of iridium atoms must have resulted from a metal–metal exchange process. The major product 3 (19% yield) contains an open cluster of one iridium and three ruthenium atoms with three SnPh₃ ligands and four hydride ligands. Both compounds were characterized structurally by single crystal X-ray diffraction analysis.     

A quantum chemical study on the reaction of 1-aryl-1,2-dihydrophosphinine oxides with dimethyl acetylenedicarboxylate

A β-oxophosphorane/ylide (2a) and an oxaphosphete (3a), the product and the possible intermediate of an inverse Wittig type reaction of 1-(2,4,6-triisopropylphenyl-)1,2-dihydrophosphinine oxide with dimethyl acetylenedicarboxylate were studied by quantum chemical calculations. The reaction of the title reagents following either a traditional [4 + 2] cycloaddition protocol to afford phosphabicyclo[2.2.2]octadiene 5 or a novel route yielding eventually β-oxophosphorane/ylide 2 was evaluated by energy calculations. The mechanism for the formation of intermediate 3a₂ was refined by HF/6-31G* transition state calculations. Analysis of the HOMO-LUMO orbitals of the reagents justified the reactivity experienced.     

Aqueous chemistry of the vanadium(III) (V(III)) and the V(III)-dipicolinate systems and a comparison of the effect of three oxidation states of vanadium compounds on diabetic hyperglycemia in rats

The aqueous vanadium(III) (V(III)) speciation chemistry of two dipicolinate-type complexes and the insulin-enhancing effects of V-dipicolinate (V-dipic) complexes in three different oxidation states (V(III), V(IV), and V(V)) have been studied in a chronic animal model system. The characterization of the V(III) species was carried out at low ionic strength to reflect physiological conditions and required an evaluation of the hydrolysis of V(III) at 0.20 M KCl. The aqueous V(III)-dipic and V(III)-dipic-OH systems were characterized, and complexes were observed from pH 2 to 7 at 0.2 M KCl. The V(III)-dipic system forms stable 1:2 complexes, whereas the V(III)-dipic-OH system forms stable 1:1 complexes. A comparison of these complexes with the V-pic system demonstrates that a second ligand has lower affinity for the V(III), presumably reflecting bidentate coordination of the second dipic(2)(-) to the V(III). The thermodynamic stability of the [V(III)(dipic)(2)](-) complex was compared to the stability of the corresponding V(IV) and V(V) complexes, and surprisingly, the V(III) complexes were found to be more stable than anticipated. Oral administration of three V-dipicolinate compounds in different oxidation states {H[V(III)(dipic)(2)H(2)O].3H(2)O, [V(IV)Odipic(H(2)O)(2)].2H(2)O, and NH(4)[V(V)O(2)dipic]} and the positive control, VOSO(4), significantly lowered diabetic hyperglycemia in rats with streptozotocin-induced diabetes. The diabetic animals treated with the V(III)- or V(IV)-dipic complexes had blood glucose levels that were statistically different from those of the diabetic group. The animals treated with the V(V)-dipic complex had the lowest blood glucose levels of the treated diabetic animals, which were statistically different from those of the diabetic group at all time points. Among the diabetic animals, complexation to dipic increased the serum levels of V after the administration of the V(V) and V(IV) complexes but not after the administration of the V(III) complex when data are normalized to the ingested dose of V. Because V compounds differing only in oxidation state have different biological properties, it is implied that redox processes must be important factors for the biological action of V compounds. We observe that the V(V)-dipic complex is the most effective insulin-enhancing agent, in contrast to previous studies in which the V(IV)-maltol complex is the most effective. We conclude that the effectiveness of complexed V is both ligand and oxidation state dependent.     

Homogeneous catalytic aminocarbonylation of iodoalkenes and iodobenzene with amino acid esters under conventional conditions and in ionic liquids

Amino acid methyl esters were used as amine nucleophiles in palladium catalysed aminocarbonylation of iodobenzene and iodoalkenes (1-iodo-cyclohexene and 17-iodo-androst-16-ene). 2-Oxo-carboxamide type derivatives can be isolated as a result of double CO insertion by using iodobenzene as a substrate at elevated carbon monoxide pressure. On the contrary, carboxamides of expected structure were obtained exclusively in excellent yields in the whole pressure range by using iodoalkenes. The aminocarbonylation of 17-iodo-androst-16-ene in [bmim][PF₆] or [bmim][BF₄] (where bmim=1-butyl-3-methyl-imidazolium cation) ionic liquids was also carried out and the ionic liquid-catalyst mixtures have been reused several times with only a small loss of activity.     

Unexpected chlorination of angularly annelated [2.2]paracyclophanes during DDQ oxidation

DDQ treatment of the Diels-Alder products 1 unexpectedly led to chloroderivatives 2. Chlorination did not occur during DDQ treatment of the fully aromatised compounds 3. These results point out that DDQ acted as an oxidant and source of chlorine.     

Replica field theory and renormalization group for the Ising spin glass in an external magnetic field

We use the generic replica symmetric cubic field theory to study the transition of short-range Ising spin glasses in a magnetic field around the upper critical dimension. A novel fixed point is found from the application of the renormalization group. In the spin-glass limit, this fixed point governs the critical behavior of a class of systems characterized by a single cubic parameter. For this universality class, the spin-glass susceptibility diverges at criticality, whereas the longitudinal mode remains massive. The third mode, however, behaves unusually. The physical consequences of this unusual behavior are discussed, and a comparison with the conventional de Almeida-Thouless scenario is presented.     

Convergence chromatographic determination of camphor in the essential oil of Tanacetum parthenium L.

Feverfew (Tanacetum parthenium L., Asteraceae) is a perennial medicinal plant which has been used to alleviate the symptoms of migraine, headache and rheumatoid arthritis and possesses numerous pharmacological activities. An ultra‐high‐performance supercritical fluid chromatographic method (UHPSFC) was developed and validated in accordance with the International Conference on Harmonization guidelines in order to determine the camphor content of the volatile oil, which was accurate, precise, robust and selective. The method was validated for specificity, accuracy (100.2%), repeatability and intermediate precision, linearity (r² > 0.999), limit of detection (2.055 μg/mL), limit of quantification (6.228 μg/mL) and robustness. The common range of accuracy and linearity was between 0.125 and 1.000 mg/mL. Steam distillation was carried out in order to study the essential oil yield of three different T. parthenium L. samples originating from Hungarian medicinal herb collections. The camphor content of the essential oils from the aerial parts of feverfew samples from different origin was compared. Although the composition of the essential oil is well reported, a validated quantitative UHPSFC method for the determination of the constituents is presented herein for the first time.