Reversible hydrogen absorption in sodium intercalated fullerenes

The hydrogen absorption of sodium intercalated fullerenes (Na_xC₆₀) was determined and compared to pure fullerenes (C₆₀). Up to 3.5 mass% hydrogen can reversibly be absorbed in Na_xC₆₀ at 200 °C and a hydrogen pressure of 200 bar. The absorbed amount of hydrogen is significantly higher than for the case when only the sodium would be hydrogenated (∼1 mass% for x = 10). At 200 bar the onset of hydrogen absorption is observed at 150 °C. At a pressure of 1 bar hydrogen the major desorption starts at 250 °C and is completed at 300 °C (heating rate 1 °C min⁻¹). This absorption and desorption temperatures are significantly reduced compared to pure C₆₀, either due to a catalytic reaction of hydrogen on sodium or due to the negatively charged C₆₀. The hydrogen ab/desorption is accompanied by a partial de/reintercalation of sodium. A minor part of the hydrogen is ionically bonded in NaH and the major part is covalently bonded in C₆₀H_x. The sample can be fully dehydrogenated and no NaH is left after desorption. In contrast to C₆₀, where the fullerene cages for high hydrogen loadings are destroyed during the sorption process, the Na_xC₆₀ sample stays intact. The samples were investigated by X-ray, in-situ neutron powder diffraction and infrared spectroscopy. Na_xC₆₀ was synthesized by reacting sodium azide (NaN₃) with C₆₀ (molar ratio of Na:C₆₀ is 10:1).     

Structure and characterization of poly[(vinylidene fluoride)‐co‐hexafluoropropene]–(dibutyl phthalate) blends

Blends of poly[(vinylidene fluoride)‐co‐hexafluoropropene] with dibutyl phthalate were examined by wide‐ and small‐angle X‐ray scattering, differential scanning calorimetry and dynamic mechanical spectroscopy, in order to study the influence of amount of plasticizer and the crystallization rate on the crystallinity and lamellar morphology of the copolymer. The dibutyl phthalate seems, at least for the cooling and heating rates used, simply to dilute the crystalline phase without affecting the amount of polymer that is able to crystallize. Furthermore, the small‐angle X‐ray scattering technique points out that the plasticizer mostly enters the amorphous phase either outside or inside the lamellar stacks. © 2001 Society of Chemical Industry     

Regulation of T helper cell differentiation in vivo by soluble and membrane proteins provided by antigen-presenting cells

The aim of this study was to test whether the nature of the antigen-presenting cell (APC) can influence the Th1/Th2 balance in vivo. Our data show that dendritic cells (DC), pulsed extracorporeally with antigen, induced the development of cells secreting IL-2, IFN-gamma and IL-4 upon antigen rechallenge in vitro. Priming with peritoneal macrophages sensitized cells that produced IL-4 but not IFN-gamma. To identify the factors involved in T helper development, mice were primed with APC with or without treatment with neutralizing antibodies to costimulatory molecules or cytokines. Our results indicate that priming with DC or macrophages is strictly dependent on the CD28-CTLA4/B7 interaction. Of note, CD86 provides the initial signal to induce naive T cells to become IL-4 producers, whereas CD80 is a more neutral differentiation signal. IL-12, released by the DC, appears as a potent and obligatory inducer of differentiation for IFN-gamma-producing cells. IL-6, although produced by both APC populations, is necessary to direct activation of the Th2-type response by macrophages but not by DC.     

Barley β-Glucans-Containing Food Enhances Probiotic Performances of Beneficial Bacteria

Currently, the majority of prebiotics in the market are derived from non-digestible oligosaccharides. Very few studies have focused on non-digestible long chain complex polysaccharides in relation to their potential as novel prebiotics. Cereals β-glucans have been investigated for immune-modulating properties and beneficial effects on obesity, cardiovascular diseases, diabetes, and cholesterol levels. Moreover, β-glucans have been reported to be highly fermentable by the intestinal microbiota in the caecum and colon, and can enhance both growth rate and lactic acid production of microbes isolated from the human intestine. In this work, we report the effects of food matrices containing barley β-glucans on growth and probiotic features of four Lactobacillus strains. Such matrices were able to improve the growth rate of the tested bacteria both in unstressed conditions and, importantly, after exposure to in vitro simulation of the digestive tract. Moreover, the effect of β-glucans-containing food on bacterial adhesion to enterocyte-like cells was analyzed and a positive influence on probiotic-enterocyte interaction was observed.     

A low power Ku phase locked oscillator in low cost 130 nm CMOS technology

This paper reports on a Ku low-power integer-N phase locked oscillator designed to investigate the potentialities of a low-cost 130 nm CMOS technology for video broadcasting and radiometry applications. The design and the characterization of the prototype are described and the main performances are reported and compared to literature. The PLO generates an output tone in the 14.2 GHz–15.1 GHz frequency range. The phase noise is −68.9 dBc/Hz for an offset frequency of 100 kHz from a 15 GHz carrier, and can be enhanced of about 20 dB. The circuit core sinks 23.7 mA from 1.2 V supply.     

Toluene-induced oxidative stress in several brain regions and other organs

The in vivo dose-response relationship between toluene and reactive oxygen species (ROS) formation in rat brain, liver, kidney, and lung, and the time-course of these effects has been characterized. The rate of oxygen radical formation was measured using the probe 2',7'-dichlorofluorescin diacetate. In vivo exposure to various doses of toluene (0.5, 1.0, and 1.5 g/kg ip) elicited a dose-dependent elevation of ROS generation within crude mitochondrial fractions obtained from rat lung and kidney, and within crude synaptosomal fractions from cerebellum. ROS formation in crude mitochondrial fractions from liver, and crude synaptosomal fractions from striatum and hippocampus, reached a maximum value at relatively low doses of toluene. Of the brain regions, the hippocampus had the highest induced levels of ROS. In vivo exposure to a single dose of toluene (1.5 g/kg ip), revealed that toluene-induced ROS reached a peak within 2 h, which correlated directly with measured toluene blood levels. This elevated oxidative activity was maintained throughout the next 24 h, even though blood values of toluene decreased to negligible amounts. These results demonstrate that exposure to toluene results in broad systemic elevation in the normal rate of oxygen radical generation, with such effects persisting in the tissues despite a rapid decline in toluene blood levels. Acute exposure to toluene may lead to extended ROS-related changes, and this may account for some of the clinical observations made in chronic toluene abusers.     

Transduction of the SkBr3 breast carcinoma cell line with the HOXB7 gene induces bFGF expression, increases cell proliferation and reduces growth factor dependence

Several melanomas, carcinomas, glioblastomas and leukemias showed coordinated expression of HOXB7 and bFGF with exception of the SkBr3 mammary carcinoma that was negative for both. Transduction of HOXB7 gene into SkBr3 cells, induced bFGF expression, increased growth rate, independence from serum withdrawal and ability to form colonies in semisolid medium. ELISA assay showed that most of bFGF was associated to cell lysate when cells were cultured at 1% serum whereas in cells kept to 10% serum bFGF was detected both within cell lysate or secreted into cell supernatants. Antisense oligos to bFGF inhibited the growth of cells cultured in 1%, indicating that beside the possible activation of additional genes other than bFGF by HOXB7 transduction, only bFGF induction accounts for the observed results. Moreover, since inhibition of cell proliferation occurred in cells kept in 1% but not 10% serum, a bFGF intracrine loop appears operative in serum starved SkBr3/HOXB7 cells. Also, these results further indicate bFGF as target of HOXB7.