Charge transfer at phthalocyanine interfaces

Using X-ray photoelectron (XPS) and X-ray absorbtion spectroscopy (XAS) we demonstrate charge transfer at an interface between two transition metal phthalocyanines, MnPc and F16CoPc, resulting in charged MnPc + and F16CoPc -, species. Density functional theory calculations reveal that a hybrid state is formed between the two types of phthalocyanines, which causes this charge transfer. For the hybrid state the Mn3dxz interacts with the Co 3dz2 orbital leading to a two-level system. Moreover, we have prepared mixed films out of this pair, which were characterized also by means of electron energy-loss spectroscopy. Our data reveal the formation of MnPc/F16CoPc charge transfer dimers in analogy to the heterojunction. The electronic excitation spectrum of these blends is characterized by a new low energy excitation at 0.6 eV

A global analysis of Y-chromosomal haplotype diversity for 23 STR loci

In a worldwide collaborative effort, 19,630 Y-chromosomes were sampled from 129 different populations in 51 countries. These chromosomes were typed for 23 short-tandem repeat (STR) loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385ab, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, GATAH4, DYS481, DYS533, DYS549, DYS570, DYS576, and DYS643) and using the PowerPlex Y23 System (PPY23, Promega Corporation, Madison, WI). Locus-specific allelic spectra of these markers were determined and a consistently high level of allelic diversity was observed. A considerable number of null, duplicate and off-ladder alleles were revealed. Standard single-locus and haplotype-based parameters were calculated and compared between subsets of Y-STR markers established for forensic casework. The PPY23 marker set provides substantially stronger discriminatory power than other available kits but at the same time reveals the same general patterns of population structure as other marker sets. A strong correlation was observed between the number of Y-STRs included in a marker set and some of the forensic parameters under study. Interestingly a weak but consistent trend toward smaller genetic distances resulting from larger numbers of markers became apparent.Peer reviewe

Charge transfer at phthalocyanine interfaces

Using X-ray photoelectron (XPS) and X-ray absorbtion spectroscopy (XAS) we demonstrate charge transfer at an interface between two transition metal phthalocyanines, MnPc and F16CoPc, resulting in charged MnPc + and F16CoPc -, species. Density functional theory calculations reveal that a hybrid state is formed between the two types of phthalocyanines, which causes this charge transfer. For the hybrid state the Mn3dxz interacts with the Co 3dz2 orbital leading to a two-level system. Moreover, we have prepared mixed films out of this pair, which were characterized also by means of electron energy-loss spectroscopy. Our data reveal the formation of MnPc/F16CoPc charge transfer dimers in analogy to the heterojunction. The electronic excitation spectrum of these blends is characterized by a new low energy excitation at 0.6 eV

Charge transfer at phthalocyanine interfaces

Using X-ray photoelectron (XPS) and X-ray absorbtion spectroscopy (XAS) we demonstrate charge transfer at an interface between two transition metal phthalocyanines, MnPc and F16CoPc, resulting in charged MnPc + and F16CoPc -, species. Density functional theory calculations reveal that a hybrid state is formed between the two types of phthalocyanines, which causes this charge transfer. For the hybrid state the Mn3dxz interacts with the Co 3dz2 orbital leading to a two-level system. Moreover, we have prepared mixed films out of this pair, which were characterized also by means of electron energy-loss spectroscopy. Our data reveal the formation of MnPc/F16CoPc charge transfer dimers in analogy to the heterojunction. The electronic excitation spectrum of these blends is characterized by a new low energy excitation at 0.6 eV

Arbeitsgruppe 'Kulturkontakte: Akkulturation, Assimilation, Aneignung - Integration'

'Die Geschichte Osteuropas ist die Geschichte multiethnischer Gesellschaften. Russland ist als Vielvoelkerreich zu imperialer Groesse gelangt. Die im Mittelalter einsetzende Reichsbildung, die Kolonialisierung der Peripherien im Osten, Sueden und Westen in der Neuzeit und die Konsolidierung als imperiale Grossmacht im 19. und 20. Jahrhundert waren mit Prozessen religioeser und ethnischer Differenzierung, der Integration und Desintegration verklammert. Die staatsoffizielle Nationalitaetenpolitik im zarischen Russland ist vorwiegend als 'Zivilisierung' des Fremden, als Uebertragung grossrussischer Identitaeten und normativer Wertbezuege auf die nichtrussischen Randzonen des Reiches betrieben worden. Die vom kolonialistischen Herrschaftsanspruch der Zaren, durch natuerliche Migration und interkulturelle Zusammentreffen ausgeloesten Kulturkontakte konnten physische Gewaltanwendung der Eroberer, die Angleichung von Kommunikationsmedien- und formen (Sprache, Schrift, Rituale) oder - wie bei den Juden des Zarenreiches - zur ethnischen und sozialen Deklassierung fuehren. Das Ziel war in jedem Fall die Aufhebung von Symbolkonkurrenzen und die uneingeschraenkte Loyalitaet gegenueber der russisch-orthodox gepraegten Autokratie. Ausnahmen bildeten importierte 'Fremde' wie die deutschen Kolonisten in Zentralrussland und der Ukraine oder die aus westlichen Staaten einwandernden Unternehmer, die der normativen Rahmensetzung des Imperiums eine eigene Symbolsprache entgegensetzten und zu Grenzgaengern zwischen konkurrierenden kulturellen und sozialen Systemen wurden. Fuer die am KFK/ SFB 485 beteiligten Teilprojekte, die sich mit osteuropaeischer Geschichte im weiteren und mit der Geschichte des russischen Imperiums im engeren Sinne befassen, gehoeren die interethnischen Kulturkontakte zu den zentralen Fragestellungen. Ausgehend von sozialen Konfigurationen im Sibirien des 18. Jahrhunderts, am Zarenhof des 18. Jahrhunderts und in Staedten des westlichen Imperiums, einschliesslich des Koenigreiches Polen, im 19. Jahrhundert bis zum Ersten Weltkrieg sind die Formen des Kulturkontakts vergleichend diskutiert worden. 'Aneignung' und 'Akkulturation' haben sich dabei als wesentliche Formen des Kulturkontakts im Zarenreich erwiesen. Die drei Beitraege fassen die Diskussion um gemeinsame und konkurrierende Begriffe und Konzepte zusammen und pruefen die Reichweite der Kulturkontakttheorie an konkreten historischen Konstellationen.' (Textauszug)SIGLEAvailable from UuStB Koeln(38)-20020107784 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Linker histone partial phosphorylation: effects on secondary structure and chromatin condensation

Linker histones are involved in chromatin higher-order structure and gene regulation. We have successfully achieved partial phosphorylation of linker histones in chicken erythrocyte soluble chromatin with CDK2, as indicated by HPCE, MALDI-TOF and Tandem MS. We have studied the effects of linker histone partial phosphorylation on secondary structure and chromatin condensation. Infrared spectroscopy analysis showed a gradual increase of β-structure in the phosphorylated samples, concomitant to a decrease in α-helix/turns, with increasing linker histone phosphorylation. This conformational change could act as the first step in the phosphorylation-induced effects on chromatin condensation. A decrease of the sedimentation rate through sucrose gradients of the phosphorylated samples was observed, indicating a global relaxation of the 30-nm fiber following linker histone phosphorylation. Analysis of specific genes, combining nuclease digestion and qPCR, showed that phosphorylated samples were more accessible than unphosphorylated samples, suggesting local chromatin relaxation. Chromatin aggregation was induced by MgCl and analyzed by dynamic light scattering (DLS). Phosphorylated chromatin had lower percentages in volume of aggregated molecules and the aggregates had smaller hydrodynamic diameter than unphosphorylated chromatin, indicating that linker histone phosphorylation impaired chromatin aggregation. These findings provide new insights into the effects of linker histone phosphorylation in chromatin condensation

Determination of the Charge Transport Mechanisms in Ultrathin Copper Phthalocyanine Vertical Heterojunctions

Bulky organic semiconductors have been widely applied on a variety of devices including transistors, sensors, and organic light-emitting diodes. Recently, the capability of producing stable ultrathin organic semiconductor-based junctions has opened the possibility of a variety of novel device concepts, including high-speed organic transistors, organic spin valves, and biosensors. In such context, the investigation of the charge transport mechanisms across ultrathin organic semiconductors is the key for the engineering of emerging organic-based technologies. Here, the charge transport mechanisms across heterojunctions based on physisorbed ultrathin copper phthalocyanine on gold are precisely determined and controlled over a wide range of temperatures and electric fields. We observe that the macroscopic electrical characteristics of Au/CuPc/Au heterojunctions are similar to what has been reported for chemisorbed molecular junctions. For instance, the transition from thermally activated transport to tunneling is verified regardless of the nature of the molecule-contact bonding. The Au/CuPc/Au heterojunction transport is dominated by charge localization sites at high temperatures and, upon cooling, a continuous transition from direct tunneling, via resonant tunneling, to field emission takes place by increasing the voltage bias. Such a continuous transition has not been reported for a hybrid metal/organic heterojunction yet. We have also determined the dielectric constant of the CuPc molecular layer via transport measurements, which allowed us to infer the possible molecule arrangements between the electrodes