Time-wavelength two-dimensional femtosecond fluorescence imaging

We report a new femtosecond time-resolved fluorescence spectrometer that enables us to observe fluorescence intensity as a time-wavelength two-dimensional image in a single measurement. This method utilizes a time-to-space conversion technique and fluorescence sum-frequency mixing with a femtosecond gate pulse. It provides a fluorescence image covering temporal and spectral spans of approximately 2 ps and approximately 60 nm, respectively. Calibration of the time and intensity axes of the image is made by use of a long-lived dye fluorescence. The two-dimensional fluorescence image of beta-carotene obtained demonstrates the high potential of this method for quantitative studies of ultrafast excited-state dynamics.     

Comparison of monomeric and polymeric chiral stationary phases

Two-type polymeric chiral stationary phases (pCSPs) were prepared by surface grafting of chiral acryl-type monomers on a silica gel surface modified with 3-(trimethoxysilyl)propylmethacrylate. The prepared pCSPs were characterized by IR, Fr-Raman, scanning electron microscopy, and elemental analysis. In addition, two-type monomeric chiral stationary phases (mCSPs) were also prepared. The racemic analytes were separated using the prepared mCSPs and pCSPs. The separation factor (alpha) and capacity factor (k1) of the racemic analytes for the pCSP and mCSP were compared. The alpha and k1 values of the mCSP were higher than those of the pCSP.     

Synthesis of 2-substituted 3-nitro-1,2-dihydropyridines by heterocyclic annulation reactions of a sec-nitrodienamine with aldehyde compounds

The reaction of a sec-nitrodienamine 3 with aldehyde compounds afforded 2-substituted 3-nitro-1,2-dihydropyridines 5, providing a heterocyclic annulation reaction.     

Nanocellulose-containing cellulose ether composite films prepared from aqueous mixtures by casting and drying method

Cellulose - A TEMPO-oxidized cellulose nanofibril (TEMPO-CNF)/water dispersion was mixed with an aqueous solution of hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), methyl cellulose...     

Bioinformatics and Functional Analyses Implicate Potential Roles for EOGT and L-fringe in Pancreatic Cancers

Notch signaling receptors, ligands, and their downstream target genes are dysregulated in pancreatic ductal adenocarcinoma (PDAC), suggesting a role of Notch signaling in pancreatic tumor development and progression. However, dysregulation of Notch signaling by post-translational modification of Notch receptors remains poorly understood. Here, we analyzed the Notch-modifying glycosyltransferase involved in the regulation of the ligand-dependent Notch signaling pathway. Bioinformatic analysis revealed that the expression of epidermal growth factor (EGF) domain-specific O-linked N-acetylglucosamine (EOGT) and Lunatic fringe (LFNG) positively correlates with a subset of Notch signaling genes in PDAC. The lack of EOGT or LFNG expression inhibited the proliferation and migration of Panc-1 cells, as observed by the inhibition of Notch activation. EOGT expression is significantly increased in the basal subtype, and low expression of both EOGT and LFNG predicts better overall survival in PDAC patients. These results imply potential roles for EOGT- and LFNG-dependent Notch signaling in PDAC.     

Conjugated Oligomers and Polymers Sheathed with Designer Side Chains

Conjugated polymers (CPs) are often referred to as molecular wires because of their quasi one‐dimensional electronic wavefunctions delocalized along the polymer chains. However, in the solid state, CPs tend to self‐assemble through π‐stacking, which greatly attenuates the one‐dimensional nature. By molecular design, CPs can be molecularly insulated just like electric power cords, resulting in so‐called “insulated” molecular wires (IMWs). In this Focus Review, we will discuss their unique photophysical, electronic, and mechanical properties which originate from the absence of π‐stacking.     

Total Synthesis of Ellagitannins through Regioselective Sequential Functionalization of Unprotected Glucose

Short total syntheses of natural glycosides (ellagitannins) were performed through sequential and regioselective functionalization of the hydroxy groups of unprotected glucose. The key reactions are β‐selective glycosidation of a gallic acid derivative by using unprotected glucose as a glycosyl donor and catalyst‐controlled regioselective introduction of a galloyl group into the inherently less reactive hydroxy group of the glucoside.     

Mechanofluorochromism of 1‐Alkanoylaminopyrenes

To create a new series of mechanofluorochromic materials and to elucidate the mechanism of the phenomenon of mechanofluorochromism, 1‐alkanoylaminopyrenes including 1‐acetylaminopyrene (AAPy), 1‐octanoylaminopyrene (OAPy), and 1‐stearoylaminopyren (SAPy) were prepared. It was found that these materials exhibited mechanofluorochromism with emission colors in the crystalline samples changing reversibly from bluish purple to yellowish green, which could be induced by mechanical grinding. X‐ray crystal structure analysis, electronic absorption, and fluorescence spectroscopies, as well as fluorescence lifetime analysis and powder X‐ray diffraction analysis of AAPy suggested that the present mechanofluorochromism was caused by developing crystal defects through grinding. Intermolecular hydrogen bonds were suggested to play an important role in the occurrence of mechanofluorochromism, suppressing the face‐to‐face overlapping of pyrene moieties to form excimers in the pristine crystal.     

Vertical distributions of global fallout 137Cs and 14C in a Japanese forest soil profile and their implications for the fate and migration processes of Fukushima-derived 137Cs

Vertical distributions of global fallout ¹³⁷Cs and ¹⁴C were investigated in a Japanese forest soil in 2001. Even 38 years after the fallout, ¹³⁷Cs was still observed mostly in the uppermost 5 cm. A preferential accumulation of ¹³⁷Cs was found in a 1-cm-thick transition layer between organic-rich A and underlying B horizons. This unique observation indicated that ¹³⁷Cs migrated through the A horizon at a rate of 0.20 % year⁻¹ and the transition layer acted as a barrier for ¹³⁷Cs migration to deeper layers. The vertical distributions of ¹³⁷Cs and ¹⁴C were significantly correlated, suggesting a coupled downward migration of ¹³⁷Cs and organic matter on a time scale of decades, along the same physical pathways.

     

Calculation of optical trapping forces on a dielectric sphere in the ray optics regime produced by a radially polarized laser beam

We calculated the optical trapping forces on a microscopic particle in the ray optics regime for the case where a radially polarized laser beam is applied. A higher axial trapping efficiency than for a circularly polarized doughnut beam was predicted due to the large p polarization component. Three-dimensional optical trapping was expected for particles with a larger index of refraction and for objectives with a smaller numerical aperture.