Densitometric Determination of Embelin in Lysimachia punctata

JPC – Journal of Planar Chromatography – Modern TLC - Athin layer chromatographic method with densitometric UV detection at λ = 285 nm has been developed for quantification of...     

Classification of generic 3-dimensional Lagrangian singularities with (Z2) l -symmetries

The paper provides the complete list of local models forZ ₂ ^l -invariant generic germs of Lagrangian submanifolds of dimension ≦3. Classification is done directly for genrating functions of Lagrangian submanifolds and contains both elementary singularities and non-elementary ones with continuous moduli. The results demonstrate, in particular, that in contrast to the non-equivariant case the classification of equivariant Lagrangian singularities is not subordinated to the classification of symmetric functions up to the right equivariant equivalences.     

Linear Automorphisms that are Symplectomorphisms

Let K be the field of real or complex numbers. Let (X K²ⁿ,) be a symplectic vector space and take 0 < k < n,N =. Let L₁,...,L_N X be 2k-dimensionallinear subspaces which are in a sufficiently general position.It is shown that if F : X X is a linear automorphism whichpreserves the form ^k on all subspaces L₁,...,L_N, then F is an_k-symplectomorphism (that is, F^* = _k, where ). In particular, if K = R and k is odd then F mustbe a symplectomorphism. The unitary version of this theoremis proved as well. It is also observed that the set A_l,2r ofall l-dimensional linear subspaces on which the form has rank 2r is linear in the Grassmannian G(l,2n), that is, there isa linear subspace L such that A_l,2r = L G(l, 2n). In particular,the set A_l,2r can be computed effectively. Finally, the notionof symplectic volume is introduced and it is proved that itis another strong invariant.     

Synthesis of betulin derivatives and the determination of their relative lipophilicities using reversed‐phase thin‐layer chromatography

A series of superlipophilic or highly lipophilic semisynthetic betulin derivatives was prepared and their relative lipophilicity was measured by reversed‐phase thin‐layer chromatography (RP‐TLC) at different pH values using 1,4‐dioxane–acetate buffer mixtures as mobile phases. Cholesterol, 17β‐estradiol and pure betulin were used as the reference compounds. Linear relationships were found between R_M values and 1,4‐dioxane concentrations in the mobile phases. LogP values were also calculated with computer programs ACD/LogP (ChemSketch 11.0, Advanced Chemistry Development Inc.) and ClogP (Daylight Chemical Information Systems Inc.). The empirical and theoretical data were compared, and the R_M0 values correlated well with logP. Two of the synthesized betulin derivatives are reported for the first time. Copyright © 2009 John Wiley & Sons, Ltd.     

Polynomial symplectomorphisms

Let be the field of real or complex numbers. Let (X ²ⁿ, )be a symplectic affine space. We study the group of polynomialsymplectomorphisms of X. We show that for an arbitrary k thegroup of polynomial symplectomorphisms acts k-transitively onX. Moreover, if 2 l 2n – 2 then elements of this groupcan be characterized by polynomial automorphisms which preservethe symplectic type of all algebraic l-dimensional subvarietiesof X.     

Quantification of Saponins in Different Plant Parts of Lysimachia L. Species by validated HPTLC—Densitometric Method

JPC – Journal of Planar Chromatography – Modern TLC - Quantitative high-performance thin-layer chromatography (HPTLC) analysis of triterpene saponins in different parts of eight...     

Local geometry of constitutive sets

Reduction in the category of general constitutive sets is defined and the generic stable models for reduced constitutive sets are derived. In the context of symmetric smooth constitutive sets, the corresponding infinitesimal stability properties are studied and the examples of classical systems encountered in physics are given.     

Response of brassinosteroid-treated oilseed rape cotyledons to infection with the wild type and HR-mutant of <Emphasis Type="Italic">Pseudomonas syringae</Emphasis> or with <Emphasis Type="Italic">P. fluorescence</Emphasis>

The aim of the study has been to determine the protection effect of brassinosteroid (BR₂₇) in oilseed rape cotyledons against infection by an incompatible wild type of, a hypersensitive response mutant of and saprophytic Pseudomonas bacteria. In this paper, membrane permeability, PSII efficiency and metabolic activity were analysed. The following strains of Pseudomonans were used: P. syringae pv. syringae (Ps), P. syringae pv. syringae hrcC mutant (Pm) and P. fluorescence (Pf). The study was carried out using two cultivars of spring oilseed rape (Brassica napus L.): ‘Licosmos’ and ‘Huzar’. Pre-treatment of cotyledons with BR₂₇ caused about 50–70% increase in ion leakage for both cultivars. However, BR₂₇ significantly decreased ion leakage from cotyledons inoculated with Ps in both cultivars. Infection with Ps and Pf caused disturbances of energy flow in PSII by lowering its efficiency in rape cotyledons. We noted insignificant impact of 24-epibrassinolide on PSII efficiency if compared to absolute control, but generally it had a positive effect in plants infected with bacteria. The values of heat flow in all treatments, except for cotyledons infected with Ps, decreased during 20 h after inoculation. However, the curves of heat flow for Ps-infected cotyledons showed a completely different pattern with at least two peaks. BR₂₇ pre-treated cotyledons infected with Ps had higher heat flow in comparison to Ps infected ones. BR₂₇ treatment did not change specific enthalpy of cotyledon growth (Δgh) for both cultivars if compared with absolute control. However, infection with Ps markedly increased Δgh values by about 200% for both cultivars. We suggested protective action of BR₂₇ in oilseed rape cotyledons after bacterial infection with Pseudomonas.