Helical assembly of azobenzene-conjugated carbohydrate hydrogelators with specific affinity for lectins

Carbohydrate-mediated interactions are involved in various biological processes via specific molecular assembly and recognition. Such interactions are enhanced by multivalent effects of the sugar moieties, and thus supramolecular sugar-assembly, i.e., spontaneous association of glycoamphiphiles, is a promising approach to tailor glycocluster formation. In this study, novel sugar-decorated nanofibers were successfully prepared by self-assembly of low molecular weight hydrogelators composed of azobenzene and disaccharide lactones. Circular dichroism measurement of the as-prepared hydrogels indicated that the azobenzene amphiphile containing a lactose moiety possessed (R)-chirality, while the maltose-azobenzene conjugate exhibited (S)-chirality, even though the cellobiose-conjugated azobenzene existed in an achiral form. This suggests that the chiral orientation of the chromophoric azobenzene depended on both the glycosidic linkages and the steric arrangement of hydroxyl groups in the conjugated carbohydrates. Lectin-binding and cell adhesion assays revealed that the nonreducing ends of the conjugated sugar moieties were exposed on the surfaces of self-assembled nanofibrous hydrogels, allowing them to be effectively recognized by the corresponding lectins. In addition, photoisomerization of azobenzene under ultraviolet irradiation induced the sol-gel transitions of the hydrogels. These results demonstrate that the reversibly transformed fibrous glycohydrogels show potential for application as carbohydrate-decorated scaffolds for cell culture engineering.     

Advantages and Potential of Lipid‐Membrane‐Incorporating Fullerenes Prepared by the Fullerene‐Exchange Method

Lipid‐membrane‐incorporating C₆₀ and C₇₀ (LMIC₆₀ and LMIC₇₀) were prepared by the fullerene‐exchange reaction from the γ‐cyclodextrin cavity to vesicles (we call this method the “exchange method”). An advantage of this method is that the ratios of [C₆₀]/[lipids] and [C₇₀]/[lipids] can be arbitrarily controlled by adjusting the ratios of the fullerenes and liposome. The maximum ratio (30 mol %) obtained was approximately 14 and 100 times higher than those achieved for LMIC₆₀ and LMIC₇₀, respectively, that were prepared by the classical method, which we call the “premixing method” (dissolving lipids and C₆₀ or C₇₀ in chloroform, followed by concentration and extraction with water). Furthermore, the stabilities and photodynamic activities of the LMIC₆₀ and LMIC₇₀ solutions prepared by the exchange method were shown to be much higher than those prepared by the premixing method. That is, the exchange method was found to be superior to the premixing method as a preparative method of LMIC₆₀ and LMIC₇₀ for applications in photomedical and photomaterials chemistry.     

Thermal rectification in nonmetallic solid junctions: Effect of Kapitza resistance

Based on Fourier's law for heat conduction, we investigate the asymmetric heat flow in two segment rods of nonmetallic materials. Specifically, we study the effect of the Kapitza resistance at the boundary of the segments on the thermal rectification. To understand basic features of the rectification, we first develop analytical calculation for the heat currents in an ideal rod of a macroscopic length. Explicitly, this is made by assuming that the thermal conductivity of each constituent has a power-law dependence on temperature and also assuming the continuity of temperature at the boundary. Then, we introduce the temperature jump at the boundary due to the Kapitza resistance and show that this effect on the thermal rectification becomes significant as the length of the rod decreases typically to submillimeters. In particular, we find that the temperature jump yields a finite rectification even when no asymmetry is predicted in the heat currents from the continuity of temperature at the junction. The obtained results have an important implication for the analysis of the thermal rectification of a rod consisting of semiconductors Ge and Si.     

Abnormalities of cerebral blood flow in multiple sclerosis: A pseudocontinuous arterial spin labeling MRI study

Arterial spin labeling (ASL) is a noninvasive technique that can measure cerebral blood flow (CBF). To our knowledge, there is no study that examined regional CBF of multiple sclerosis (MS) patients by using this technique. The present study assessed the relationship between clinical presentations and functional imaging data in MS using pseudocontinuous arterial spin labeling (pCASL). Twenty-seven patients with MS and 24 healthy volunteers underwent magnetic resonance imaging and pCASL to assess CBF. Differences in CBF between the two groups and the relationships of CBF values with the T2-hyperintense volume were evaluated. Compared to the healthy volunteers, reduced CBF was found in the bilateral thalami and right frontal region of the MS patients. The volume of the T2-hyperintense lesion was negatively correlated with regional CBF in some areas, such as both thalami. Our results suggest that demyelinated lesions in MS mainly have a remote effect on the thalamus and that the measurement of CBF using ASL could be an objective marker for monitoring disease activity in MS.     

Stopping powers of Al,Ti, Cu,Zr, Rh,Ag, Ta and Au for 26 MeV alpha particles and Z3 1 correction

Abstract

Stopping powers of Al, Ti, Cu, Zr, Rh, Ag, Ta and Au for 26 MeV alpha particles have been measured using a surface barrier silicon detector with an accuracy of 0.35%. The stopping powers for alpha particles divided by 4 have been compared with the stopping powers for 6.500 MeV protons of the same velocity. Experimental magnitudes of the Z ³ ₁ correction which is contained in the Bethe-Bloch stopping formula were extracted using the alpha-proton difference. Using the experimental Z ³ ₁ corrections thus obtained and the experimental Z ³ ₁ corrections of the previous paper, parameters of γ and b which appear in the theory of Ashley, Ritchie and Brandt for the Z ³ ₁ correction have been determined with exactly the same method as the previous paper as γ = 1.336 and b = 1.32. The magnitude of the Z ³ ₁ correction calculated by the theory of Ashley, Ritchie and Brandt using these parameters have been compared with those obtained by other authors.     

Synthesis and Properties of Thieno[3,2‐b]thiophene Derivatives for Application of OFET Active Layer

A series of thieno[3,2‐b]thiophene derivatives having styryl groups were synthesized via short steps and characterized by UV–vis absorption spectra and cyclic voltammetry. Based on these results, we found that the introduction of long chain alkyl groups to the terminal styryl groups leads to narrower HOMO–LUMO gaps and higher HOMO energy levels than the unalkylated styryl substituted molecules. Organic field–effect transistor (OFET) devices using these derivatives as the active layer were fabricated by a vacuum deposition process. It was demonstrated that these devices showed a relatively high hole mobility up to 3.5 × 10⁻² cm²/Vs. These devices also showed a good stability, namely their mobilities did not decrease over 100 days in air. Therefore, these facts suggested that the introduction of long‐chain alkylated styryl groups is an effective way to improve the hole mobilities in OFETs. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:25–35, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21059     

Organocatalyzed anodic oxidation of aldehydes

A method for the catalytic formation of electroauxiliaries and subsequent anodic oxidation has been developed. The process interfaces N-heterocyclic carbene-based organocatalysis with electro-organic synthesis to achieve direct oxidation of catalytically generated electroactive intermediates. We demonstrate the applicability of this method as a one-pot conversion of aldehydes to esters for a broad range of aldehyde and alcohol substrates. Furthermore, the anodic oxidation reactions are very clean, producing only H(2) gas as a result of cathodic reduction.     

Monoterpene glucosides from Ziziphora clinopodioides (Labiatae)

Three new monoterpene glucosides, ziziphoroside A (1), B (2), and C (3), together with fifteen known compounds were isolated from the whole herb of Z. clinopodioides. The structures of new compounds were determined primarily from 1D-, 2D-NMR and circular dichroism (CD) spectroscopic analyses. The isolated compounds were evaluated for their inhibitory activity against nitric oxide (NO) production by lipopolysaccharide (LPS) and interferon (IFN)-γ activated macrophages, RAW 264.7. Shizonepetoside A (8) and flavones (11, 12, 13) showed potent inhibitory activity against NO production.