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Brown adipose tissue (BAT) burns fatty acids for heat production to defend the body against cold (1,2) and has recently been shown to be present in humans (3-5). Triglyceride-rich lipoproteins (TRLs) transport lipids in the bloodstream, where the fatty acid moieties are liberated by the action of lipoprotein lipase (LPL) (6). Peripheral organs such as muscle and adipose tissue take up the fatty acids, whereas the remaining cholesterol-rich remnant particles are cleared by the liver (6). Elevated plasma triglyceride concentrations and prolonged circulation of cholesterol-rich remnants, especially in diabetic dyslipidemia, are risk factors for cardiovascular disease (7-11). However, the precise biological role of BAT for TRL clearance remains unclear. Here we show that increased BAT activity induced by short-term cold exposure controls TRL metabolism in mice. Cold exposure drastically accelerated plasma clearance of triglycerides as a result of increased uptake into BAT, a process crucially dependent on local LPL activity and transmembrane receptor CD36. In pathophysiological settings, cold exposure corrected hyperlipidemia and improved deleterious effects of insulin resistance. In conclusion, BAT activity controls vascular lipoprotein homeostasis by inducing a metabolic program that boosts TRL turnover and channels lipids into BAT. Activation of BAT might be a therapeutic approach to reduce elevated triglyceride concentrations and combat obesity in humans., Although white adipose tissue is a specialized lipid storage organ for excess calories, BAT contains large amounts of mitochondria to dissipate chemical energy. Upon cold-stimulated activation by nervous input, BAT [...]

Despite the increasing use of semiconductor nanocrystals (quantum dots, QDs) with unique size-controlled optical and chemical properties in (bio)analylical detection, bio-sensing and fluorescence imaging and the obvious relevance of reliable values of fluorescence quantum yields for these applications, evaluated procedures for the determination of the fluorescence quantum yields ([[PHI].sub.f]) of these materials are still missing. This limits the value of literature data of QDs in comparison to common organic dyes and hampers the comparability of the performance of QDs from different sources or manufacturers. This encouraged us to investigate achievable uncertainties for the determination of [[PHI].sub.f] values of these chromophores and to illustrate common pitfalls exemplarily for differently sized water-soluble CdTe QDs. Special attention is dedicated to the colloidal nature and complicated surface chemistry of QDs thereby deriving procedures to minimize uncertainties related to these features.

A systematic experimental study of the CdTe nanocrystals' synthetic procedure supported by a calculation of the concentration of various Cd-thiolate complexes during the synthesis as a function of pH, concentration of Cd-salt, and the concentration ratio of Cd to ligand is reported. A numerical calculation demonstrated a clear correlation between the concentration of CdL (where L is ([SC[H.sub.2]Coo].sup.2-] in the initial solution and the photoluminescence quantum efficiency of the resulting CdTe nanocrystals.

A study was conducted to investigate the evolution of the specific features in the cyclic voltammetric curves of ZnSe nanocrystals (NCs) as a function of their photochemical treatment. The results demonstrate that cyclic voltammetry is a powerful method for probing surface states of semiconductor NCs as well as for monitoring the evolution of these states during photochemical processing.

Buffers used for the indirect immunofluorescence labeling of cells were tested with several fractions of the size-selective precipitation of thioglyconic acid (TGA) and mercaptopropionic acid (MPA)- stabilized particles were mixed with different buffers that had defined concentration. The results show the possibility of the use of water-soluble, thiol-capped QDs for immunofluorescence labeling using the commonly used buffers.

The inter-nanocrystals (NCs) interactions among pristine assemblies, electrostatically mixed assemblies, and covalently linked NCs assemblies of CdTe NCs stabilized with thioamine and thio acid surfactants were compared. The spectral overlaps between the adsorption and emission curves, the PL red shift, the PL decay curves, and the calculated FRET revealed that covalently linked NCs have the strongest inter-NCs interaction, while CdTe(TGA) NCs act as the most efficient donors.

Several distinct oxidation and reduction peaks in the voltammograms were demonstrated by electrochemical studies of thiol-capped CdTe nanocrystals inaqueous solution with the peak positions being dependent on the size of the nanocrystals. An extraordinary behavior is found for the oxidation peak observed at less positive potentials.

The charge transport in nanoparticulate ZnO layers held at different potentials is studied by analyzing the anodic transient photocurrents. The results reveal that the effective diffusion constant for the electron transport through ZnO film held at positive potentials is calculated to be 1.7 x 10(super -4) cm(super 2)/s which is in good agreement with diffusion constants.

Interactions in semiconductor nanocrystal assemblies are studied on films of the cluster crystal compounds Cd17S4(SCH2CH2OH)(sub 26) and Cd32S14(SCH2CH(CH3)OH)(sub 36) prepared by spin coating. The redshift of the transition energy is explained by dipole-dipole interactions of the semiconductor nanocrystals in the films.

The synthesis of thiol-capped crystalline CdSe nanoparticles in aqueous solution using mercaptoalcohols and mercapto acids as stabilizers has been undertaken. The CdSe nanoparticles were synthesized by adding NaHSe solutions to N2-saturated Cd(ClO4)2*6H2O solutions at pH 11.2 in the presence of the thiol stabilizers. The particle size was determined by the type of stabilizer and by the postpreparative size-selective precipitation. The particles were observed to be in the size quantization regime as compared with bulk CdSe. Second electronic transitions were also resolved for the smallest nanoparticles.

The enhancement of the fluorescence quantum yield of CdTe nanocrystals by surface modification has been studied. CdTe nanocrystals have been prepared in aqueous solution by reacting Cd2+ with NaHTe and thioglycolic acid. The clusters start to crystallize and exhibit a narrow band of emission under reflux conditions. It has been observed that a shell of cadmium thioglycolic acid is formed around the CdTe core. The maximum quantum yield at room temperature has been measured to be 18% when the pH value of the CdTe solution is 4.5 by using thioglycolic acid.

The synthesis of high-quality cadmium phosphide quantum dots with emission wavelength maxima is described. Photoelectrochemical investigations have shown that the cadmium phosphide QD-derivatized electrodes have shown an optical response and that photocurrents of several nanoamperes per square centimeter are obtained upon illumination.

The Langmuir-Blodgett deposition of a colloidal crystal on top of a thin film containing CdTe nanocrystals are used to fabricate a light source on the surface of a slab of 2+1-dimensional photonic crystal. The findings from the study explain the changes in the emission spectrum in terms of the acceleration of the radiative recombination due to the increase in the local field strength at photonic bandgap resonance and changes in the emission diagram due to the wavelength dependence of the topology of the local field pattern.

The synthesis and characterization of monodisperse SnS nanocrystals and shape control are described. The studies have shown the ability to link the nanocrystals to conducting substrates and detect their optoelectric response.

Several studies are conducted to explain the design, characterization, as well as the applications of the ordered macroporous bimetallic nanostructures. The findings suggest that nanomaterials can be widely used as catalysts, photonic crystals, sensors and substrates in surface-enhanced Raman scattering (SERS).

The aqueous synthesis and post preparative treatment of thiol-stabilized ZnSe colloidal nanocrystals (2-3 nm in size) have been studied. The ZnSe (S) nanocrystals obtained were used for the fabrication of UV-blue-emitting layer-by-layer assembled films with a PL maximum at ca. 390 nm.

New approaches to synthesize photostable thiol-capped CdTe nanocrystals are reported. Some advantages of thiol-capping in comparison to conventional organometallic synthises of quantum dots are discussed.

The state-of-art preparations and standard characterization methods of semiconductor nanocrystals are discussed. The development of more complex nanoheterostructures is reported and their structural and electronic properties are highlighted.