Solar UV irradiation and dermal photoaging.

The skin is increasingly exposed to ambient UV-irradiation thus increasing risks for photooxidative damage with long-term detrimental effects like photoaging, characterized by wrinkles, loss of skin tone and resilience. Photoaged skin displays alterations in the cellular component and extracellular matrix with accumulation of disorganized elastin and its microfibrillar component fibrillin in the deep dermis and a severe loss of interstitial collagens, the major structural proteins of the dermal connective tissue. The unifying pathogenic agents for these changes are UV-generated reactive oxygen species (ROS) which deplete and damage non-enzymatic and enzymatic antioxidant defense systems of the skin. As well as causing permanent genetic changes, ROS activate cytoplasmic signal transduction pathways in resident fibroblasts that are related to growth, differentiation, senescence and connective tissue degradation. This review focuses on the role of UV-induced ROS in the photodamage of the skin resulting in clinical and biochemical characteristics of photoaging. In addition, the relationship of photoaging to intrinsic aging of the skin will be briefly discussed. A decrease in the overall ROS load by efficient sunscreens or other protective agents may represent promising strategies to prevent or at least minimize ROS-induced photoaging.     

"Flexiball" toolkit: a modular approach to self-assembling capsules.

We report the synthesis and characterization of new, self-assembling molecular capsules. The modular strategy makes use of glycoluril building blocks available in multigram amounts combined with aromatic spacer elements. The lengthy syntheses encountered with earlier generations of capsules are avoided, and several capsules of nanometer dimensions are now accessible. Single bond attachments between spacers and glycoluril modules result in monomers as dimeric capsules that are less rigid than their earlier counterparts. The host-guest properties of the homo- and heterodimeric capsules were studied using a combination of NMR and ESI-mass spectrometry. They show a less pronounced selectivity for guests of different sizes, and their increased flexibility prevents self-assembly when no rigidifying elements are present on the central spacer unit. Some of the new capsules bear inwardly directed, secondary amide N-H protons. These can be further functionalized, as shown by their methylation to give tertiary analogues. The structures hold broader implications for the placement of functional groups on concave molecular surfaces.     

Phase Transitions and Critical Behaviour of Binary Liquid Mixtures

Summary.  Compared to the simple one-component case, the phase behaviour of binary liquid mixtures shows an incredibly rich variety of phenomena. In this contribution we restrict ourselves to so-called binary symmetric mixtures, i.e. where like-particle interactions are equal (Φ₁₁(r) = Φ₂₂(r)), whereas the interactions between unlike fluid particles differ from those of likes ones (Φ₁₁(r) ≠ Φ₁₂(r)). Using both the simple mean spherical approximation and the more sophisticated self-consistent Ornstein-Zernike approximation, we have calculated the structural and thermodynamic properties of such a system and determine phase diagrams, paying particular attention to the critical behaviour (critical and tricritical points, critical end points). We then study the thermodynamic properties of the same binary mixture when it is in thermal equilibrium with a disordered porous matrix which we have realized by a frozen configuration of equally sized particles. We observe – in qualitative agreement with experiment – that already a minute matrix density is able to lead to drastic changes in the phase behaviour of the fluid. We systematically investigate the influence of the external system parameters (due to the matrix properties and the fluid–matrix interactions) and of the internal system parameters (due to the fluid properties) on the phase diagram. Received June 27, 2001. Accepted July 2, 2001     

On the Photochemical Proton Expulsion Capability of Fringelite D – A Model of the Protist Photosensory Pigments of the Stentorin and Blepharismin Types

Summary.  Using simultaneous two-photon excitation of fringelite D and a fluorescence indicator embedded in a vesicle system it was demonstrated that after excitation a proton was transferred from the pigment to the indicator similarly as recently documented for hypericin. Semiempirical AM1 calculations were used to show that the radical species formed by electron transfer from the excited pigment state constitutes an acid which is therefore well suited for intermolecular proton transfer. Accordingly, this process constitutes a suited candidate for the primary photoprocess in the signal transduction cascade of the photosensory pigments of the stentorin and blepharismin type. Received April 26, 2000. Accepted May 16, 2000     

On the elastic symmetries of growing mixed-mode cracks

Many continuum damage mechanics models for quasi-brittle materials are based on the reduction of stiffness due to elliptical crack or penny-shaped microcracks in the material. Because of this a numerical study of growing elliptical cracks in a unit cube is undertaken with the help of an FEM simulation.The propagation of the crack is governed by the principle of maximum driving force [1]. For each propagation step the tensor of elasticity is calculated and its symmetries are analyzed. It will be shown that the elastic symmetry in each step is close to orthotropy and can be approximated by an elliptical crack. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A generalization of Cahn-Hilliard inpainting for grayvalue images

The Cahn-Hilliard equation has its origin in material sciences and serves as a model for phase separation and phase coarsening in binary alloys. A new approach in the class of fourth order inpainting algorithms is inpainting of binary images using the Cahn-Hilliard equation. We will present a generalization of this fourth order approach for grayvalue images. This is realized by using subgradients of the total variation functional within the flow, which leads to structure inpainting with smooth curvature of level sets. We will present some numerical examples for this approach and analytic results concerning existence and convergence of solutions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Processed Cheeses Made With and Without Peptization. Submicroscopic structure and thermodynamic characteristics

The osteoporosis is regarded as a widespread disease all over the world. In the prevention therapy of this disease there is a primary role of the daily calcium intake with the proper Ca:P ratio (1:1–1:2). The primary source of Ca for people the dairy products are implied, from which only the processed cheeses have inadequate ratio of Ca:P. In cheeses processed without peptization developed in the Hungarian Dairy Research Institute (HDRI) the Ca:P ratio meets the requirements (1.5:1), moreover these products can be enriched with Ca. In this study we used both processing technologies. The electronmicroscopic photographs demonstrate the differences clearly. The traditionally processed cheese (with peptization) has a 'spongy’ structure well known from literature, while a space-net can be seen resulting from the casein-filamentous hydrocolloid interaction in the structure of heat-treated cheese without peptization. DSC curves are the same in the temperature range 0–40°C, showing endotherm melting process in two well-distinguished temperature interval (0–20 and 22–40°C). They are different in the temperature interval 40–100°C: in the case of processed cheese with peptization the gel-sol transformation gives a higher endotherm peak in a narrow temperature range, while for heat-treated cheese without peptization this temperature range is wider with a lower endotherm peak. Both electronmicroscopic and DSC investigations have proved that contrary to the traditionally processed cheese where the structure is formed by the linked peptized protein, in the heat- processed cheese without peptization the frame-forming element is the huge hydrocolloid molecule interacted with the protein. The enthalpy change is substantially lower at the disintegration of the latter structure. This revised version was published online in July 2006 with corrections to the Cover Date.     

Status of the SHIPTRAP Project: A Capture and Storage Facility for Heavy Radionuclides fromSHIP

The ion trap facility SHIPTRAP is being set up to deliver very clean and cool beams of singly-charged recoil ions produced at the SHIP velocity filter at GSI Darmstadt. SHIPTRAP consists of a gas cell for stopping and thermalizing high-energy recoil ions from SHIP, an rf ion guide for extraction of the ions from the gas cell, a linear rf trap for accumulation and bunching of the ions, and a Penning trap for isobaric purification. The progress in testing the rf ion guide is reported. A transmission of about 93(5)% was achieved. This revised version was published online in July 2006 with corrections to the Cover Date.