Investigating Atomic Details of the CaF2_2(111) Surface with a qPlus Sensor

The (111) surface of CaF$_2$ has been intensively studied with large-amplitude frequency-modulation atomic force microscopy and atomic contrast formation is now well understood. It has been shown that the apparent contrast patterns obtained with a polar tip strongly depend on the tip terminating ion and three sub-lattices of anions and cations can be imaged. Here, we study the details of atomic contrast formation on CaF$_2$(111) with small-amplitude force microscopy utilizing the qPlus sensor that has been shown to provide utmost resolution at high scanning stability. Step edges resulting from cleaving crystals in-situ in the ultra-high vacuum appear as very sharp structures and on flat terraces, the atomic corrugation is seen in high clarity even for large area scans. The atomic structure is also not lost when scanning across triple layer step edges. High resolution scans of small surface areas yield contrast features of anion- and cation sub-lattices with unprecedented resolution. These contrast patterns are related to previously reported theoretical results.Comment: 18 pages, 9 Figures, presented at 7th Int Conf Noncontact AFM Seattle, USA Sep 12-15 2004, accepted for publication in Nanotechnology, http://www.iop.or

Flavonol-Derivate in Formen der Gattung Vitis

In einem ersten Ansatz, dem weitere Absicherungen und Identifizierungen durch Isolierung größerer Substanzmengen folgen sollen, wurden die Blätter von vier Rebenformen auf ihren Flavonoidgehalt hin untersucht. Vergleichschromatogramme zeigen, daß einige Hauptflavonoide in allen vier Rebenformen vorkommen; darüber hinaus unterscheiden sie sich jedoch durch zahlreiche weitere Spurenverbindungen. In Bestätigung bisheriger Arbeiten wurden als Hauptaglykone Quercetin und das in geringerer Konzentration vorliegende Kämpferol nachgewiesen. Bisher für die Reben nicht angegeben ist Myricetin, das in den von uns untersuchten Proben vorkommt. Zwei weitere Aglyka lassen sich derzeit noch nicht dünnschichtchromatographisch identifizieren.Alle Aglyka liegen in glykosidischer Bindung vor. Wir konnten bestätigen, daß Glucoside und Rhamnoglucoside in der Rebe vorliegen. Jedoch machen diese Verbindungen keineswegs die Hauptmasse der Glykoside in diesen Pflanzen aus. Die Hauptmenge des Quercetins und Kämpferols liegt in Form von Glucuroniden vor. Myricetin scheint allerdings nicht an der Glucuronid-Fraktion beteiligt zu sein. Es befindet sich im wesentlichen in der Glucosid-Fraktion. Die, Untersuchungen zur endgültigen Bestätigung dieser Befunde und zur Analyse weiterer Begleitsubstanzen werden fortgesetzt.Flavonol compounds in some members of the genus VitisThe flavonoid compounds of four vines (Vitis riparia, Vitis vinifera cvs. Riesling and Sylvaner, hybrid Sbl. 5-24-20) have been investigated. Beyond the known main aglycons quercetin and kaempferol we identified myricetin as a third component and showed the presence of two additional minor aglycons, which are not yet identified.All aglycons are present as glycosides. The glucosides and rhamnoglucosides of quercetin and kaempferol, described by other authors, and of myricetin are present, but ortly as minor components. The major amount of the flavonoids has been found as 3-glucuronides. The investigations will be continued

Evidence for Potassium Carbonate Crystallites on Air-Cleaved Mica Surfaces

Ostendorf F, Schmitz C, Hirth S, Kühnle A, Kolodziej JJ, Reichling M. Evidence for Potassium Carbonate Crystallites on Air-Cleaved Mica Surfaces. Langmuir. 2009;25(18):10764-10767.Air-cleaved mica surfaces exhibit a high density of nanometer or micrometer size particles that have been ascribed to potassium carbonate formed as it reaction product of carbonaceous gases with potassium ions. Unambiguous evidence for this assignment has, however, never been presented. We study air-cleaved mica surfaces by high-resolution noncontact atomic force microscopy (NC-AFM) in ultrahigh vacuum to reveal the detailed structure of such precipitates on the surface. Among a large number of irregularly shaped surface structures, we find flat, hexagonally shaped islands exhibiting two different patterns on their surfaces, namely a rectangular atomic corrugation pattern and a hexagonal moire Structure. The unit cell of the rectangular pattern corresponds to the dimensions of the potassium carbonate bulk structure and is found on high crystallites. The moire structure solely appears on very flat islands and is caused by the interference of the potassium carbonate lattice periodicity and the lattice periodicity of the underlying mica substrate. Both results strongly point to the presence of potassium carbonate crystallites on air-cleaved mica surfaces

How flat is an air-cleaved mica surface?

Ostendorf F, Schmitz C, Hirth S, Kühnle A, Kolodziej JJ, Reichling M. How flat is an air-cleaved mica surface? Nanotechnology. 2008;19(30):305705.Muscovite mica is an important mineral that has become a standard substrate, due to its easy cleavage along the {001} planes, revealing a very flat surface that is compatible with many biological materials. Here we study mica surfaces by dynamic atomic force microscopy (AFM) operated in the non-contact mode (NC-AFM) under ultra-high vacuum (UHV) conditions. Surfaces produced by cleaving in UHV cannot be imaged with NC-AFM due to large surface charges; however, cleavage in air yields much less surface charge and allows for NC-AFM imaging. We present highly resolved NC-AFM images of air-cleaved mica surfaces revealing a rough morphology originating from a high density of nanometre-sized particles. Among these particles, we find regularly shaped structures indicating the growth of crystallites on the surface. The contamination layer cannot be removed by degassing in UHV; even prolonged heating at a temperature of 560 K under UHV conditions does not yield an atomically flat surface

Transition Radiation Spectroscopy with Prototypes of the ALICE TRD

We present measurements of the transition radiation (TR) spectrum produced in an irregular radiator at different electron momenta. The data are compared to simulations of TR from a regular radiator.Comment: 4 pages, 5 Figures, Proceedings for "TRDs for the 3rd millennium" (Sept. 4-7, 2003, Bari, Italy

Formulacija i evaluacija monolitnih matriksnih polimernih filmova za transdermalnu isporuku nitrendipina

The objective of the present work was to develop a suitable transdermal drug delivery system for nitrendipine. Polymeric films of nitrendipine were prepared by the film casting technique (glass ring) on mercury substrate. They were evaluated for physicochemical parameters, in vitro release and ex vivo permeation (heat separated human epidermis). Release of the drug from the films followed anomalous transport (0.5 < n < 1). Polymeric combination containing Eudragit RL 100:PVP K 30 in 4:6 ratio showed the best results. Maximum drug release and skin permeability coefficient in 48 h were 85.8 % and 0.0142 cm h-1, respectively, in formulation C3 (Eudragit RL 100: Plasdone S 630; 4:6) and 88.0 % and 0.0155 cm h-1, respectively, in formulation D3 (Eudragit RL 100: PVP K 30; 4:6). FTIR and TLC studies indicated no drug and polymer interaction.Cilj rada bio je razvoj transdermalnog sustava nitrendipina. Polimerni filmovi nitrendipina pripravljeni su metodom lijevanja (stakleni prsten) na podlozi od žive. Ispitivani su fizičkokemijski parametri, in vitro oslobađanje i ex vivo permeacija (toplinom odvojena humana epiderma). Oslobađanje lijeka iz filmova slijedilo je anomalni transport (0,5 < n < 1). Najbolji rezultati postignuti su kombinacijom polimera Eudragit RL 100 i PVP K 30 u omjeru 4:6. Maksimalno oslobađanje ljekovite tvari i najbolji koeficijent permeacije kroz kožu tijekom 48 h bio je 85,8 %, odnosno 0,0142 cm h1 za formulaciju C3 (Eudragit RL 100 : Plasdone S 630; 4:6) i 88,0 %, odnosno 0,0155 cm h1 za formulaciju D3 (Eudragit RL 100 : PVP K 30; 4:6). FTIR i TLC ukazuju na to da nema interakcije između ljekovite tvari i polimera

Amelioration of Carcinogen-Induced Toxicity in Mice by Administration of a Potentized Homeopathic Drug, Natrum Sulphuricum 200

To examine if a potentized homeopathic drug, Natrum Sulphuricum 200 (Nat Sulph-200) has protective potentials against hepatocarcinogenesis, liver tumors were induced in mice through chronic feeding of P-dimethylaminoazobenzene (p-DAB; initiator of hepatocarcinogenesis) and phenobarbital (PB; promoter). Mice were divided into five sub-groups: fed normal low protein diet (Gr. I, normal control); fed normal low protein plus alcohol-200 (vehicle of the homeopathic remedy) (Gr. II); fed diet mixed with 0.06% p-DAB plus 0.05% PB (Gr. III); fed diet and carcinogens like Gr.III, plus alcohol 200 (positive control for drug fed mice) (Gr. IV) and fed diet and carcinogens like Gr. III, plus Natrum Sulphuiricum-200 (Gr. V; drug fed). Mice were sacrificed at day 7, 15, 30, 60, 90 and day 120 for study of cytogenetical endpoints like chromosome aberrations (CA), micronuclei (MN), mitotic index (MI) and sperm head anomaly (SHA) and biochemical toxicity parameters like aspartate amino transferase (AST), alanine amino transferase (ALT), acid (AcP) and alkaline (AlkP) phosphatases, lipid peroxidation (LPO) and reduced glutathione (GSH) content. Less number of liver tumors were observed in Gr. V (drug fed) mice. Administration of Nat Sulph 200 reduced genomic damage, activities of AcP, AlkP, AST, ALT, LPO and increased GSH content. Therefore, independent replication of the study by others is encouraged