Schnelle thermometrische Siliciumbestimmung in Gu?eisen und Stahl

Zusammenfassung Es wurde eine Schnellbestimmung von Silicium in Gußeisen und Stahl mit Hilfe der Direktinjektionsenthalpimetrie ausgearbeitet. Nach Auflösen der Probe und Dehydratation der Kieselsäure mit konzentrierter Perchlorsäure wird das ausgeschiedene Kieselsäurehydrogel abfiltriert, in Kalilauge gelöst und nach dem Ansäuern mit verdünnter Fluorwasserstoffsäure als Reagens versetzt. Die Bildung des Komplexanions [SiF₆]^2– und die gleichzeitig verlaufende Ausfällung des schwerlöslichen K₂ [SiF₆] sind exotherme Reaktionen. Die freigesetzte Wärmemenge, die vom Siliciumgehalt direkt proportional abhängig ist, wird mit Hilfe eines Thermistors in Brückenschaltung gemessen. Ein Digitalanzeigegerät ermöglicht es, den Siliciumgehalt direkt in Prozent abzulesen.

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Rapid thermometric determination of silicon in cast iron and steel

Summary A method for the rapid determination of silicon by direct injection enthalpimetry in steel and cast iron was elaborated. After dissolution of the sample and dehydration of silicic acid in perchloric acid, the separated silicium oxide hydrogel is dissolved in potassium hydroxide solution and after acidifying, hydrofluoric acid reagent is added. Formation of the complex anion [SiF₆]^2– and the simultaneously proceeding precipitation of insoluble K₂SiF₆ are exothermic reactions. The amount of heat released is directly proportional to the silicon content and is measured by a thermistor. Digital display of the Wheatstone bridge millivoltmeter permits to read the Si content in the sample directly in percent.

     

Measuring Nanoscale Thermostability of Cell Membranes with Single Gold–Diamond Nanohybrids

Much of the current understanding of thermal effects in biological systems is based on macroscopic measurements. There is little knowledge about the local thermostability or heat tolerance of subcellular components at the nanoscale. Herein, we show that gold nanorod–fluorescent nanodiamond (GNR‐FND) hybrids are useful as a combined nanoheater/nanothermometer in living cells. With the use of a 594 nm laser for both heating and probing, we measure the temperature changes by recording the spectral shifts of the zero‐phonon lines of negatively charged nitrogen‐vacancy centers in FNDs. The technique allows us to determine the rupture temperatures of individual membrane nanotubes in human embryonic kidney cells, as well as to generate high temperature gradients on the cell membrane for photoporation and optically controlled hyperthermia. Our results demonstrate a new paradigm for hyperthermia research and application.     

Thermometrische Analyse von Dihydrazinophthalazinsulfat mit der TET- und DIE-Methode

Ohne Zusammenfassung

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Thermometric analysis of dihydrazinophthalazine sulphate by TET and DIE methods

     

Thermometrische Bestimmung von Alkaliborhydriden nach der TET-Methode

Ohne Zusammenfassung

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Thermometric determination of alkali boron hydrides by the TET method

     

Thermal Enhancement of Upconversion by Negative Lattice Expansion in Orthorhombic Yb2W3O12

Thermal quenching of photoluminescence represents a significant obstacle to practical applications such as lighting, display, and photovoltaics. Herein, a novel strategy is established to enhance upconversion luminescence at elevated temperatures based on the use of negative thermal expansion host materials. Lanthanide‐doped orthorhombic Yb₂W₃O₁₂ crystals are synthesized and characterized by in situ X‐ray diffraction and photoluminescence spectroscopy. The thermally induced contraction and distortion of the host lattice is demonstrated to enhance the collection of excitation energy by activator ions. When the temperature is increased from 303 to 573 K, a 29‐fold enhancement of green upconversion luminescence in Er³⁺ activators is achieved. Moreover, the temperature dependence of the upconversion luminescence is reversible. The thermally enhanced upconversion is developed as a sensitive ratiometric thermometer by referring to a thermally quenched upconversion.     

Conformational Dynamics of Monomer- versus Dimer-like Features in a Naphthalenediimide-Based Conjugated Cyclophane

The design and synthesis of an enantiomeric pair of 1,8-diethynylanthracene-bridged naphthalenediimide (NDI)-based cyclophanes ( Cyclo-NDI s) are reported. Each enantiomer of Cyclo-NDI exhibits a circularly polarized luminescence signal with a relatively large luminescence dissymmetry factor (g_lum=±8×10⁻³). We have further investigated the modulation of through-space electronic communication between co-facially oriented NDIs in a discrete Cyclo-NDI with changes in the temperature. Tuning of the electronic communication results from the conformational transformation of monomer- versus dimer-like features of Cyclo-NDI , as confirmed by UV/Vis, fluorescence, circular dichroic, and NMR spectroscopic analysis. The temperature-dependent optical response in the Cyclo-NDI through the conformational transformation could be utilized as a highly sensitive and reversible optical thermometer in a wide temperature range (100 to −80 °C).     

Thermometrische Sulfidbestimmung durch Thiosulfatbildung

Ohne Zusammenfassung

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Thermometric determination of sulphide by conversion to thiosulphate

     

Ein Thermistordetektor zur Bestimmung von Substraten an Tr?ger-gebundenen Enzymen in Durchflu?-Systemen

Ohne Zusammenfassung

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A thermistor detector for substrate determination with immobilized enzymes in flow systems