Photo-Physical Behaviour of CdSe Nanocrystals/Bis(dithiocarbamate) Linker Multilayered Hybrid Systems.

Multilayered films composed by CdSe Nanocrystals (NCs) interlinked by ethylene-1,2-bis(dithiocarbamate) or adipate anions were prepared on ITO glass via layer-by-layer alternation. The films were analyzed by UV-vis, TEM, Photoluminescence (PL) emission and Pump-Probe spectroscopy. While the PL emission of the two samples present no differences, femtosecond Pump-probe experiments reveal an higher charge generation efficiency in bis(dithiocarbamate) based films than in dicarboxylate ones.

Alternate monolayers of CdSe nanocrystals and perylene tetracarboxylate: quantum dot hypersensitization for dye-sensitized solar cells.

Mono- and multilayers from CdSe nanocrystal dispersion and perylene tetracarboxylate solution are reported for the first time. The layers were investigated by UV-visible spectroscopy, cyclic voltammetry, photoconductivity, and photoelectrochemical techniques. The n-type organic semiconductor gives enhanced photoconductivity to the CdSe-NC multilayer structure. The photoactive perylene monolayer acts also as hypersensitizer of CdSe-NC structures. The perylene-modified CdSe-NC monolayer on indium tin oxide (ITO) electrode in a three-electrode photoelectrochemical cell upon illumination in the presence of oxygen generates an intense steady photocurrent as high as 10-20 times that expected from the individual contributions of perylene and CdSe-NCs. The hypersensitization mechanism is discussed on the basis of the energy level diagram of the components.

Diffusion-mediated resonant energy transfer in lanthanide-based polymer white-light-emitting diodes.

We present a single layer, polymer white light emitting diode (WOLED) based on novel organic lanthanide complexes. The device is solution processed and possesses CIE coordinates of (0.33, 0.38), corresponding to a high color purity white light emission. The electroluminescence in this diode is found to originate from both the direct charge trapping on the lanthanide complexes and from the efficient diffusion-assisted long-range energy transfer between the conductive matrix and these emissive dopants. An expression for the steady-state transfer efficiency is given, the role of excitation diffusion in the system under study is quantitatively evaluated, and the values for the singlet exciton diffusion coefficients and diffusion lengths in the host are determined.

Batch effects, water content and aqueous/organic solvent reactivity of microcrystalline cellulose samples.

The structural, morphological and surface features on two MCC powders of the same commercial type (Avicel PH 102), but coming from different countries (The Netherlands and Hong Kong) and vendors (DMV International and Mingtai Chemical Co., Ltd., respectively), have been investigated and compared, by means of the X-ray diffraction, SEM and BET and polymerization degree determination. TGA and water sorption from saturated vapor experiments have been applied to characterize and compare the MCC/water interactions of the two samples. The results were integrated by studies of preferential sorption from binary aqueous/organic solvents.

Evidence for disregulation in the control of Epstein-Barr virus latency in patients with AIDS-related complex.

Patients affected by AIDS-related complex (ARC) show several immunological abnormalities which may lead to a disregulation of immunosurveillance against viral latent infections. In this paper evidence for Epstein-Barr virus (EBV) reactivation in seven out of eight affected by persistent generalized lymphadenopathy is given. These patients showed either elevated levels of circulating EBNA-positive transformed cells or depressed EBV-specific T cell cytotoxicity, as assessed by the regression assay, or both. A direct involvement of EBV in the pathogenesis of ARC is thus suggested. Natural killer cell activity was found decreased, correlating to the evidence of circulating EBV-infected cells and of impaired EBV-specific immune control. These data provide evidence that, when specific immune mechanisms lose control on ubiquitous latent viruses, the risk for reactivation becomes higher. In the case of EBV, direct evidence of this event is provided by the emergence in the peripheral blood of clones of infected cells with unlimited growth potential.

Abnormal expansions of polyclonal large to small size granular lymphocytes: reactive or neoplastic process?

Morphological, immunologic, and functional properties of peripheral blood cells from two patients with chronic proliferations of granular lymphocytes are described. Cells from both patients showed a heterogeneous pattern from both a morphological and immunologic standpoint, indicating a polyclonal, rather than a monoclonal, expansion of these cells. In fact, both large and small-to-medium-sized granular lymphocytes were observed, and different percentages of positivity were found in the analysis with a large panel of monoclonal antibodies. Serologic and histologic features support the hypothesis that this lymphocytosis could be secondary to bacterial or viral infections rather than a primary event, suggesting that these patients may have chronic reactive immunoregulatory disorders.

Chronic granulomatous disease in two sisters.

Two sisters with chronic granulomatous disease (CGD) have been studied. The diagnosis was suggested by the histopathological findings from the spleen and lymph nodes of the proband and confirmed by the low values obtained in the following tests performed on polymorphonuclear leukocytes (PMN): chemiluminescence, nitroblue tetrazolium (NBT) reduction, killing of Staphylococcus aureus, and O2- production. NADPH oxidase activity was not detected in the homogenates of the patients' PMN but cytochrome b was normally present. In addition, PMN depolarization induced by phorbol-myristate acetate was absent, thus suggesting a defect of the activation mechanism of the respiratory enzyme. The normal depolarization induced by ouabain indicated that the membrane polarity regulated by the Na/K pump in the patients' cells was not affected. The low, but not completely absent, respiratory activity of the patients' PMN could suggest an X-linked mode of inheritance with incomplete Lyonization. From a clinical point of view, one sister had mild symptoms whereas the other was almost symptomless, thus confirming once more the heterogeneity of CGD syndrome.