Dual-tracer fluorescence thermometry measurements in a heated channel

The exponential growth of component density in microelectronics has renewed interest in compact and high heat flux thermal management technologies that can handle local heat fluxes exceeding 1 kW/cm². Accurate and spatially resolved thermometry techniques that can measure liquid-phase temperatures without disturbing the coolant flow are important in developing new heat exchangers employing forced-liquid and evaporative cooling. This paper describes water temperature measurements using dual-tracer fluorescence thermometry (DFT) with fluorescein and sulforhodamine B in laminar Poiseuille flow through polydimethyl siloxane-glass channels heated on one side. The major advantage of using the ratio of the signals from these two fluorophores is their temperature sensitivity of 4.0–12% per °C—a significant improvement over previous DFT studies at these spatial resolutions. For an in-plane spatial resolution of 30 μm, the average experimental uncertainties in the temperature data are estimated to be 0.3°C.     

Adsorption behavior of natural anthocyanin dye on mesoporous silica

Because of its non-toxicity, naturally occurring anthocyanin is potentially suitable as a colorant for foods and cosmetics. To the wider use of the anthocyanin, the immobilization on the inorganic host for an easy handling as well as the improvement of the stability is required. This study is focused on the adsorption of significant amount of the natural anthocyanin dye onto mesoporous silica, and on the stability enhancement of the anthocyanin by the complexation. The anthocyanin has successfully been adsorbed on the HMS type mesoporous silica containing small amount of aluminum. The amount of the adsorbed anthocyanin has been increased by modifying the pore wall with n-propyl group to make the silica surface hydrophobic. The light fastness of the adsorbed anthocyanin has been improved by making the composite with the HMS samples containing aluminum, although the degree of the improvement is not so large. It has been proposed that incorporation of the anthocyanin molecule deep inside the mesopore is required for the further enhancement of the stability.     

Lamellare Struktur von Poly(tetraoxan), das durch strahleninduzierte Polymerisation im Festzustand erhalten wurde

Ohne Zusammenfassung     

Asymmetric synthesis of γ-alkayl-α-methylene-γ-butyrolactones via 1,6-remote induction using 2-[(tributylstannyl) methyl]propenamides

Reaction of chiral 2-[(tributylstannyl)methyl]propenamides with aldehydes proceeded with 1,6-asymmetric induction to give, after hydrolysis, α,-methylene-γ-butyrolactones in enantiomeric excesses as high as 80%.     

A general method for the synthesis of 3,4-epoxy-2-methylenealkanoic acid derivatives using dianion of N-phenyl-2-(phenylsulfonylmethyl)-propenamide

A general procedure has been developed for the synthesis of 3,4-epoxy-2-methylenealkanoic acid derivatives using dianion of N-phenyl-2-(phenylsulfonylmethyl)propenamide and aldehydes.     

Structural changes on hot-rolling of polyethylene. I. Crystallite orientation and lamellar deformation

The crystallite orientation and lamellar deformation produced by hot-rolling in polyethylene have been investigated. In the lightly rolled stage, the [110]^* axis of polyethylene crystals orientates in the plane perpendicular to the rolling direction and the c axis becomes aligned with the rolling direction. In the heavily rolled stage the a, b, and c axes coincide with the macroscopic directions in the sample. These orientational changes are interpreted in terms of a slip mechanism. Small-angle x-ray scattering (SAXS) investigations of hot-rolled polyethylene show the following. (1) There are two kinds of lamellar structures; one in which inclined lamellae give a four-point diagram in the SAXS photograph and another in which lamellar normals are oriented around the rolling direction even at the lightly rolled stage. The latter structure is attributed to the mechanism of unfolding and recrystallization. (2) The chain-fold length in the original structure remains unchanged in the lamellae up to a roll ratio of four although the apparent long period decreases. This is explained by inclination of polymer chains in the lamellae. Further rolling aligns the polymer chains with the rolling direction and the fold length decreases.     

Enantioselective alkylation using a new C3 symmetric amine-based chiral phase-transfer catalyst

A new C₃ symmetric amine-based chiral phase-transfer catalyst was synthesized. Application of the chiral PTC (1 mol%) in the alkylation of a tert-butyl glycinate-benzophenone Schiff base under mild reaction conditions provided an alkylated product with up to 58% enantiomeric excess.     

N- and O-arylation of pyridin-2-ones with diaryliodonium salts: base-dependent orthogonal selectivity under metal-free conditions

Metal-free N- and O-arylation reactions of pyridin-2-ones as ambident nucleophiles have been achieved with diaryliodonium salts on the basis of base-dependent chemoselectivity. In the presence of N,N-diethylaniline in fluorobenzene, pyridin-2-ones were very selectively converted to N-arylated products in high yields. On the other hand, the O-arylation reactions smoothly proceeded with the use of quinoline in chlorobenzene, leading to high yields and selectivities. In these methods, a variety of pyridin-2-ones in addition to pyridin-4-one and a set of diaryliodonium salts were accepted as suitable reaction partners.

The metal-free N- and O-arylation reactions of pyridin-2-ones with diaryliodonium salts were achieved on the basis of base-dependent chemoselectivity.