Combined spectroscopic characterization of electron transfer at hybrid CuPcF(16)/GaAs semiconductor interfaces

We characterize photoinduced charge injection at the interface between a fluorinated copper phthalocyanine (CuPcF(16)) film deposited over a GaAs(100) wafer by means of pump-probe spectroscopy combined with ultraviolet photoemission spectroscopy (UPS) and electromodulated transmission spectroscopy. UPS characterization of the hybrid interface demonstrates that the CuPcF(16) 's lowest unoccupied molecular level (LUMO) is almost aligned with the GaAs conduction band. Upon photoexcitation of the hybrid interface with 150 fs pulses we observe an efficient photoinduced electron transfer from CuPcF(16) to GaAs. The evolution of interfacial CuPcF(16) charges appear to be strongly influenced by energy level alignment at the GaAs/CuPcF(16) heterojunction.     

ON THE MECHANISM OF CARBON CLUSTERS FORMATION UNDER LASER IRRADIATION. THE CASE OF DIAMOND GRAINS AND SOLID C60 FULLERENE

It is shown by FT-ICR (Fourier transform ion cyclotron resonance) mass spectrometry that carbon clusters considered to be the superior homologues of C₆₀ fullerene are formed by laser irradiation of both synthetic diamond grains or from pure C₆₀ fullerene crystals. The surfaces of the laser irradiated diamond or C₆₀ have been examined by Raman spectroscopy. In the case of diamond the Raman spectrum suggests the superficial formation of mixed carbon nanostructures consisting of disordered graphite, fullerenic nanostructures, onion-like carbon nanostructures and diamond-like carbon. Based on the Raman spectra of the surface and on data taken from the phase diagram of carbon, it is shown that the graphitization is needed in order to produce fullerenes from diamond under laser ablation conditions. In the case of C₆₀ fullerene, it is shown by Raman spectroscopy that the laser irradiation of the crystals causes initially their photopolymerization and after further irradiation their transformation into disordered graphite. Based on these results and on a literature survey on the formation of fullerenes from more than 15 completely different substrates, it is concluded that fullerenes are formed always when laser ablation leads to a graphitization of the laser-irradiated substrate. Some astrochemical implications of the conclusions have been discussed.     

Successful Long-Term Central Venous Access

Daily home hemodialysis (DHHD) requires simple, vascular access to minimize patients' discomfort but also to guarantee tolerance and long-term efficiency. The arteriovenous fistula is not ideal for DHHD because of the double puncture required every day; in addition, the rate of dysfunction is probably greater because of the more frequent use. Central venous catheters may be a good alternative to the arteriovenous fistula as long-term vascular access for DHHD. In this study we report our experience with the internal jugular vein two-catheter access for long-term dialysis and evaluate its possible use for DHHD. Since 1988, Tesio's twin catheters have been positioned in 908 patients with exhausted peripheral vascular bed. In all patients hemodialysis could be performed a few minutes after the surgical procedure. The survival rate of catheters, in a selected group of 46 patients, at 1, 2, and 5 years was, respectively, 92%, 87%, and 82%. The mean blood flow was 282±29 mL/min at 1 month, 286±36 mL/min at 1 year, and 274±37 mL/min at 5 years. Venous pressure in the inlet side was 102±31 mm Hg at 1 month, 126±36 mm Hg at 1 year, and 132±58 mm Hg at 5 years. Catheter clotting was treated either with thrombolytic agents or with catheter (one or both) replacement. Sepsis was treated with systemic antibiotic therapy or catheter removal. Data support the potential role of the internal jugular vein two-catheter system for DHHD.     

Histone deacetylase. A key enzyme for the binding of regulatory proteins to chromatin

Stone and urine composition were analysed in 75 men and 40 women with recurrent calcium oxalate stone disease (group R) and in 48 men and 19 women who had formed only one calcium-oxalate-containing stone (group S). Patients who had developed stones with a large fraction of calcium phosphate were significantly more frequent in group R than in group S. There was furthermore a higher excretion of calcium and higher calcium oxalate supersaturation levels in patients with stones containing more than 25% calcium phosphate. It was concluded from these observations that the calcium phosphate content of renal stones might be a useful factor in predicting the future course of the disease.     

Magnetic resonance imaging and invasive evaluation of development of heart failure in transgenic mice with myocardial expression of tumor necrosis factor-alpha

The intestine is a large endocrine organ, but the dependence of colon cancer on hormones remains unknown. We show here that neurotensin, a paracrine/endocrine peptide in the gut, and the neurotensin receptor antagonist SR 48692 control colon cancer cell growth in vitro and in vivo by interacting with receptors that are ectopically expressed in colon cancers. In cell culture, neurotensin stimulates the growth of human colon cancer cell lines (SW480, SW620, HT29, HCT116 and Cl.19A) expressing the neurotensin receptor NTR1 but does not change the growth of Caco2 cells, which do not express NTR1. In SW480 cells, neurotensin is active in the 10(-10) to 10(-6) M concentration range (ED50 = 0.47 nM) while the neurotensin fragment (I-II) is inactive. Neurotensin also enhances the cellular cloning efficiency of SW480 cells in soft agar by inducing a 50% increase of colony formation. This effect is blocked by SR 48692, which alone does not alter colony formation. Subcutaneous delivery of neurotensin (0.54 micromol/kg every 24 hr) by osmotic pumps to nude mice that have been xenografted with SW480 cells results in a significant increase of tumor volume, i.e., up to 255% of control at day 20 of treatment. SR 48692 administered alone (1.7 micromol/kg every 24 hr) by daily i.p. injections reduces the development of tumors formed by xenografting SW480 cells in nude mice. A significant mean reduction of tumor volume of 38% is observed during the 22-day period of treatment. SR 48692 alone is also active at reducing tumor volume after xenografting HCT116 cells in nude mice. Our results support the notion that colon cancer growth may be dependent on blood-borne neurotensin and suggest that non-peptide neurotensin antagonists, such as SR 48692, may be useful for the development of novel therapeutic strategies of colon cancer.     

An algorithmic analysis of DNA structure

Bilinearity, complementarity and antiparallelism of the double stranded DNA structure are proved, in a general and abstract setting, as requirements of an efficient duplication algorithm for ‘mobile strings’.     

Characterization of a 0.13 μm CMOS Link Chip using Time Resolved Emission (TRE)

The Picosecond Imaging Circuit Analysis (PICA) technique using the Superconducting Single-Photon Detector (SSPD) allows the detailed characterization of pulse width variations along the delay chain of a high speed Self Timing Interface (STI). Pulses gradually shrink and finally disappear along the delay chain.     

Inflorescence-specific genes from Arabidopsis thaliana encoding glycine-rich proteins

Genomic and cDNA clones for three inflorescence-specific genes from Arabidopsis thaliana were isolated and characterized. The genes are tandemly organized in the genome on a 10 kb fragment. The expression of these genes is coordinately regulated in a developmental and organ-specific pattern. They are expressed predominantly in anthers at the later stage of flower development. The primary structure of the encoded gene products exhibits comparable features consisting of a hydrophobic domain at the N-terminal region followed by repeated glycine-rich motifs. Little homology is observed either between the glycine-rich domain of the three genes or with previously described glycine-rich proteins from other plant species.