Electronic spectra of dye solutions. I. The mirror image rule

The main assumptions of the quasi-molecule model of electronic spectra of liquid dye solutions are presented. The derived analytical expressions of the spectra account for the solvatochromic effects present in the solution. Based on the obtained spectral profiles of some coumarins in alcohol, new criteria for the validity of the mirror image rule are formulated.     

Hypothalamic FTO is associated with the regulation of energy intake not feeding reward

Background  

Polymorphism in the FTO gene is strongly associated with obesity, but little is known about the molecular bases of this relationship. We investigated whether hypothalamic FTO is involved in energy-dependent overconsumption of food. We determined FTO mRNA levels in rodent models of short- and long-term intake of palatable fat or sugar, deprivation, diet-induced increase in body weight, baseline preference for fat versus sugar as well as in same-weight animals differing in the inherent propensity to eat calories especially upon availability of diverse diets, using quantitative PCR. FTO gene expression was also studied in organotypic hypothalamic cultures treated with anorexigenic amino acid, leucine. In situ hybridization (ISH) was utilized to study FTO signal in reward- and hunger-related sites, colocalization with anorexigenic oxytocin, and c-Fos immunoreactivity in FTO cells at initiation and termination of a meal.     

Structural,thermal, and electrical properties of carbonaceous films containing palladium nanocrystals

Carbonaceous films containing Pd nanocrystals can be applied as active layers in gas sensor applications. In this article we show results of studies of C-Pd films, obtained with two different methods: (1) physical and (2) physical + chemical deposition. First type of film prepared by physical vapor deposition (PVD) process was composed of fullerenes, amorphous carbon, and palladium nanograins. In the second method PVD film was modified in chemical vapor deposition (CVD) process forming a foam-like structure. Both types of films were studied by SEM, TEM, TGA, and electrical characterization (measurement of resistivity versus composition of gaseous hydrocarbons mixture).     

Band shape analysis of electronic spectra of polar dye solutions

A semiclassical theory of electronic spectra of polar dye solutions is presented and analytical expressions of the spectra are given. A quasi-molecular approach is applied and the quasi-molecule model of the spectra previously published is reanalyzed. It is assumed that a large-amplitude motion plays a key role in the broadening of the spectra of polar dye solutions. An energy-level diagram of a quasi-molecule, considered as a dye molecule with its nearest neighborhood, is presented. In addition, the energy of reorientation in going from a Franck-Condon to an equilibrated state is determined. The orientation energy is equal to that part of the excitation energy given by the difference of the excited Franck-Condon state of a quasi-molecule from that of its equilibrated excited state. It is shown that after excitation, not only is excess vibrational, but also part of the electrostatic interaction energy is transferred to the surroundings. This energy may be obtained directly from absorption and fluorescence spectra of polar dye solutions. Experimental verification is performed on several coumarin solutions. The mean value for the reorientation energy in this case is found to be 645 cm_–1.     

Determination of solidus and liquidus temperatures by means of a Perkin-Elmer 1B differential scanning calorimeter

A Perkin-Elmer 1B DSC apparatus was used to test the O'Neill expression for the melting interval of pure compounds on samples of organic compounds 1–10 mg in weight. On the basis of O'Neill's model, an expression for the melting interval of solid solutions,T, has been derived. The difference betweenT andT ₁ – T _s (T ₁ andT _s = =liquidus and solidus temperatures) is discussed. A simple procedure for the determination of solidus and liquidus temperatures from DSC data is proposed.

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Zusammenfassung Ein Perkin-Elmer DSC-Gerät 1B wurde zur Prüfung des O'Neillschen Ausdruckes für den Schmelzbereich reiner Verbindungen an Proben organischer Verbindungen von 1–10 mg eingesetzt. Auf Grund des O'Neill-schen Modells wurde ein Ausdruck für den Schmelzbereich fester Lösungen,T, abgeleitet. Der Unterschied zwischenT undT ₁ – T _s (T ₁,T _s =Flüssig- und Fest-Temperaturen) wird erörtert. Eine einfache Methode zur Bestimmung von Fest- und Flüssigphasentemperaturen aus DSC-Daten wird vorgeschlagen.

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1 — ' , 1–10 . ' . T -T , T _c — . .

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Heat capacities of diphenyl,p-terphenyl andp-quaterphenyl from 180 K to their melting points

The heat capacities of diphenyl,p-terphenyl andp-quaterphenyl from 180 K to their melting points were measured with a Perkin-Elmer DSC 1B scanning calorimeter. Anomalies were observed in the heat capacity curves forp-terphenyl (from 400 K to the melting point) andp-quaterphenyl (from 190 to 260 K, and from 450 to 540 K). It is assumed that the anomalies near the melting points of the compounds under consideration could be related both to modification of the motion of the phenyl rings (external or/and internal) and to change in the motion of the molecules as a whole (diffusion phase).

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Zusammenfassung Die Wärmekapazitäten von Diphenyl,p-Terphenyl undp-Quaterphenyl wurden im Bereich von 180 K bis zum Schmelzpunkt der Verbindungen mit einem Perkin-Elmer DSC 1B Scanning-Kalorimeter gemessen. Anomalien der Wärmekapazitätskurven wurden beip-Terphenyl (von 400 K bis zum Schmelzpunkt) und beip-Quaterphenyl (von 190–260 K und von 450–540 K) beobachtet. Es wird angenommen, daß die Anomalien nahe der Schmelzpunkte der betreffenden Verbindungen auf Veränderungen der Bewegung der Phenylringe (äußere und/oder innere) und der Moleküle an sich (Diffusionsphase) zurückzuführen sind.

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- 1 , - - 180 . - 400 , - — 190 260 450 540 ., ( ), ( ).

     

Spectrophotometric bioanalytical flow-injection system for control of hemodialysis treatment

A spectrophotometric flow-injection analysis (FIA) system for monitoring clinical hemodialysis is demonstrated. The role of a dialysate urea detector incorporated in this bioanalytical system is played by an optical flow-through biosensor based on Prussian Blue film with chemically linked urease forming a monomolecular layer of the enzyme. This pH-enzyme optode-FIA system is useful for the selective determination of post-dialysate urea in the range of concentration corresponding to its level in real clinical samples (2-16 mmol l(-1)). This bioanalytical system allows the analysis of about 15 samples of spent dialysate per hour. The operational and storage stabilities of the applied biosensor are longer than 2 weeks and 2 months, respectively. Clinical evaluation of the bioanalytical system was performed.     

Influence of high vacuum annealing treatment on some properties of carbon nanotubes

Carbon nanotubes (CNTs) were synthesized using a chemical vapour deposition (CVD) method. The properties of CNTs before and after vacuum annealing treatment were studied using scanning electron microscopy (SEM), scanning tunneling microscopy/spectroscopy (STM/STS) and thermogravimetric analysis (TG). Field emission characteristics of the raw and vacuum heated (up to 650°C) carbon nanotube films (CNTFs) were measured in a diode system. Emissive properties of the CNTFs depend on an annealing process during which structural changes in the nanotube walls take place. The structural changes, related to saturation of dangling bonds, influence a rate of oxidation process and also improve the emissive field properties.     

Ferrocene Derivative in 1,3 Dipolar Cycloaddition Reaction to Fullerene C60

Journal of Thermal Analysis and Calorimetry - Properties of FeC60 solid samples were investigated by X-ray diffraction, 57Fe Mössbauer spectroscopy and magnetic measurements in order to...