Orientations of overdamped magnetic nanorod-gyroscopes

Overdamped magnetic nanorod-gyroscopes driven by a rotating magnetic field undergo a series of reorientations when sedimenting on top of a surface in a viscous liquid. By changing the amplitude and the rotation frequency of the driving magnetic field, the nanorod-gyroscope either synchronizes or desynchronizes with the field and rotates either around its long or short axis. The different regimes of motion are explained theoretically by coupling the nanorod-gyroscopes motion to the creeping flow equations of the surrounding fluid. It is shown that friction anisotropy plays an important role for the orientation of the nanorod-gyroscopes.     

Reaktionen mit Thio-bis-formamidinen

Reactions with Thio-bis-formamidines N,N,N′-Trisubstituted S-(4-amino-s-triazin-2-yl)-isothioureas 3 are prepared in good yields form trisubstituted thio-bis-formamidine-hydrochlorides 1 and esters of cyanimidocarboxylic acids 2 . In aqueous alkali solutions compounds 1 react with β-dicarbonyl compounds under rearrangement to yield substituted N-(pyrimidin-2-yl)-thioureas 4 and 5 .     

Polymerization of cyclic monomers. VII. Synthesis and radical polymerization of 1,3‐bis[(1‐alkoxycarbonyl‐2‐vinylcyclopropane‐1‐yl)carboxy]benzenes

1,3‐Bis[(1‐alkoxycarbonyl‐2‐vinylcyclopropane‐1‐yl)carboxy]benzenes 1 [RO: CH₃O (a), C₂H₅O (b)] were synthesized by the esterification of the corresponding 1‐alkoxycarbonyl‐2‐vinylcyclopropane‐1‐carboxylic acids with resorcinol. The structure of the new vinylcyclopropanes was confirmed by elemental analysis and infrared (IR), ¹H nuclear magnetic resonance (¹H‐NMR), and ¹³C nuclear magnetic resonance (¹³C‐NMR) spectroscopy. The radical polymerization of difunctional 2‐vinyl‐cyclopropanes in bulk with 2,2′‐azoisobutyronitrile (AIBN) results in hard, transparent, crosslinked polymers. During the bulk polymerization of the crystalline bis[(1‐methoxycarbonyl‐2‐vinylcyclopropane‐1‐yl)carboxy]benzene 1a, an expansion in volume of about 1% took place. The radical solution polymerization of 1a resulted in a soluble polymer with pendant 2‐vinylcyclopropane groups. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1775–1782, 1999     

Application of a Technofunctional Caseinate Hydrolysate to Replace Surfactants in Ice Cream

There is a demand for a clean label of ice cream in the food industry. To meet this requirement, alternative surfactants and hydrocolloids without an additive number have to be found. Here, a caseinate hydrolysate with improved interfacial properties was investigated as such an additive. Replacing only the surfactant resulted in ice cream characteristics, comparable to using a commercial emulsifier (INS 472b). Thus, a clean labeling of the surfactant using this hydrolysate is possible. By contrast, replacing the hydrocolloid additionally led to an unfavorable ice cream texture and stability.     

Heat propagation in thermally conductive polymers of PA6 and hexagonal boron nitride

Thermally conductive polymers offer new possibilities for the heat dissipation in electric and electronic components, for example, by a three‐dimensional shaping of the heat sinks. To face safety regulations, improved fire performance of those components is required. In contrast to unfilled polymers, those materials exhibit an entirely different thermal behavior. To investigate the flammability, a phosphorus flame retardant was incorporated into thermally conductive composites of polyamide 6 and hexagonal boron nitride. The flame retardant decreased the thermal conductivity only slightly. However, the burning behavior changed significantly, due to a different heat propagation, which was investigated using a thermographic camera. An optimum content of hexagonal boron nitride for a sufficient thermal conductivity and fire performance was found between 20 and 30 vol%. The improvement of the fire performance was due to a faster heat release out of the pyrolysis zone and an earlier decomposition of the flame retardant. For higher contents of hexagonal boron nitride, the heat was spread faster within the part, promoting an earlier ignition and increasing the decomposition rate of the flame retardant.     

A ¹⁸F-labeled fluorobutyl-substituted spirocyclic piperidine derivative as a selective radioligand for PET Imaging of sigma₁ receptors

In this study, we synthesized and evaluated a new spirocyclic piperidine derivative 3 , containing a 4‐fluorobutyl side chain, as a PET radioligand for neuroimaging of σ₁ receptors. In vitro, compound 3 displayed high affinity for σ₁ receptors (K_i=1.2 nM ) as well as high selectivity. [¹⁸F] 3 radiosynthesis was performed from the corresponding tosylate precursor, with high radiochemical yield (45–51 %), purity (>98 %), and specific activity (>201 GBq μmol^?1). Metabolic stability of [¹⁸F] 3 in the brain of CD‐1 mice was verified, and no penetration of peripheral radiometabolites into the cerebral tissue was observed. Results of ex vivo autoradiography revealed that the distribution of [¹⁸F] 3 in the brain corresponded to regions with high σ₁ receptor density. The highest region‐specific total‐to‐nonspecific ratio was determined in the facial nucleus (4.00). Biodistribution studies indicated rapid and high levels in brain uptake of [¹⁸F] 3 (2.2 % ID per gram at 5 min p.i.). Pre‐administration of haloperidol significantly inhibited [¹⁸F] 3 uptake into the brain and σ₁ receptor‐expressing organs, further confirming in vivo target specificity.