Ca(2+)-induced folding of a chiral ditopic receptor based on a Pybox ligand and enhancement of anion recognition

A chiral Pybox ligand bearing two urea units was developed for a Ca(2+)-induced folding ligand. 1:1 Ca(2+) complexation of the Pybox ligand afforded chiral foldamer formation with coordination of the urea carbonyls to Ca(2+). The halide-ion affinity of the foldamer was enhanced compared to Ca(2+)-free Pybox ligands.     

Effects of fullerene encapsulation on structure and photophysical properties of porphyrin-linked single-walled carbon nanotubes

Fullerene-encapsulating single-walled carbon nanotubes (C(60)@SWNT) linked with porphyrins by a short bridge have been prepared for the first time. Steady state and time-resolved spectroscopies demonstrated the initial formation of an exciplex state, followed by a charge-separated state.     

An in situ quick XAFS spectroscopy study on the formation mechanism of small gold nanoparticles supported by porphyrin-cored tetradentate passivants

We previously reported that a porphyrin-cored tetradentate passivant, which has two disulfide straps over one face of the porphyrin plane, can produce monolayer-protected gold nanoparticles, 2-4 nm in size, by the one-pot reduction of HAuCl(4) in DMF. The resulting nanoparticles are smaller than those prepared using the same S/Au molar ratio of a monodentate passivant. To examine the formation mechanism of small gold nanoparticles, the formation of gold nanoparticles in the presence of porphyrin-cored tetradentate passivants or a structurally related monodentate passivant was studied by time-resolved quick X-ray absorption fine structure spectroscopy. The results demonstrated that all of Au ions in solution are reduced to compose small Au clusters, i.e. nuclei, just after the NaBH(4) reduction of HAuCl(4) in both cases, but their size varied with the initial S/Au molar ratios and structure of the passivants. Thus, the size of Au nuclei was kinetically controlled by the passivants. Interestingly, the porphyrin-cored tetradentate passivant could stabilize smaller gold nanoparticles, 2-4 nm in size, but it was less efficient in trapping the Au nuclei formed at a very early stage, in comparison to the monodentate passivant.     

Ruthenium-catalyzed regio- and stereoselective addition of carboxylic acids to aryl and trifluoromethyl group substituted unsymmetrical internal alkynes

The regio- and stereoselective addition of carboxylic acids to aryl and trifluoromethyl group substituted unsymmetrical internal alkynes has been accomplished: the Ru(3)(CO)(12)/3PPh(3) catalyst system has effectively catalyzed the reaction to afford the trifluoromethyl group substituted (E)-enol esters with high regio- and stereoselectivities.     

Ion-selective Marangoni instability coupled with the nonlinear adsorption/desorption rate

An oil/water interface containing bis(2-ethylhexyl)phosphate and Ca(2+) or Fe(3+) exhibits spontaneous Marangoni instability associated with the fluctuation in interfacial tension. This instability rarely appears for oil/water systems with Mg(2+), Sr(2+), Ba(2+), Cu(2+), or Co(2+). The same ion selectivity is observed for n-heptane and nitrobenzene despite their significant differences in density, viscosity, and the dielectric constant of oil. We studied this instability under acidic pH conditions to avoid the neutralization reaction effects. The result of the equilibrium interfacial tension and the extraction ratio of cations indicates that a large number of oil-soluble complexes form at the interfaces of Ca(2+)-containing systems and probably for Fe(3+)-containing systems. The results obtained by oscillating drop tensiometry and Brewster angle microscopy indicate that desorption, rather than adsorption, is more significant to the onset of instability and that the resulting complex tends to form aggregates in the interface. This aggregation gives the nonlinear desorption rate of the oil-soluble complex. Then, exfoliation of the aggregating matter occurs, which triggers the Marangoni instability. The induced convection removes the oil-soluble complex accumulated at the interface, creating a renewed interface, which is necessary for the successive occurrence of the Marangoni instability. For the other cations, the oil-soluble compounds are insignificant, and they rarely form aggregates. In such cases, adsorption/desorption proceeds without instability.     

Evidence of Improvement in Various Impairments by Exercise Interventions in Patients with Knee Osteoarthritis: A Systematic Review and Meta-analysis of Randomized Clinical Trials

Purpose: To investigate improvement in various impairments by exercise interventions in patients with knee osteoarthritis (OA). Methods: We collected data on randomized controlled trials (RCTs) comparing the effects of exercise intervention with those of either nonintervention or psychoeducational intervention in patients with knee OA. Data on pain, stiffness, muscle strength, range of motion, flexibility, maximal oxygen uptake, and position sense were synthesized. The Grading of Recommendations Assessment, Development, and Evaluation system was used to determine the quality of the evidence. Results: Thirty-three RCTs involving 3,192 participants were identified. Meta-analysis provided highquality evidence that exercise intervention improves maximal oxygen uptake, and moderate-quality evidence that exercise intervention also improves pain, stiffness, knee extensor and flexor muscle strength, and position sense. The evidence that exercise intervention improves knee extension and flexion range of motion was deemed as undetermined-quality. Conclusion: In patients with knee OA, improvement in pain, stiffness, muscle strength, maximal oxygen uptake, and position sense with the use of exercise intervention can be expected. Although the quality of evidence of the effect of exercise intervention on range of motion was inconclusive, exercise intervention should be recommended for patients with knee OA to improve various impairments.     

Advanced in Development IR Modulators of Ferroelectric Liquid Crystals Utilizing Transient Light Scattering Effects

Abstract

The highly efficient IR-modulation has been achieved using LC electro-optic elements. Experimental infrared modulator elements have been fabricated and demonstrated utilizing the transient light scattering effect of ferroelectric liquid crystal with asymmetric waveform voltage drive. The new elements performed 80%, 50%, 40% and 25% modulation degree in the 632.8nm, 2, 3-5 and 8-12 μm region. And we observed micro domain structure under the scattering state by a polarizing microscope to understand the mechanism of the domain switching. In addition, we evaluated properties of the scattering angular and temperature dependence quite important for the design of optics for the application in the infrared range.     

DNA Damage and Apoptosis Induced by Photosensitization of 5,10,15,20-Tetrakis (N-methyl-4-pyridyl)-21H,23H-porphyrin via Singlet Oxygen Generation

Cancer photodynamic therapy (PDT) requires photosensitizers that efficiently and selectively destroy tumor cells. We investigated 5,10,15,20-tetrakis ( N -methyl-4-pyridyl)-21 H ,23 H -porphyrin (TMPyP) as a potential cancer treatment. Confocal fluorescence microscopy showed that TMPyP was localized in the nuclei, whereas 5-aminolevulinic acid (ALA)-derived protoporphyrin IX (PPIX) was localized diffusely in the cytoplasm of human leukemia (HL-60) cells. In HL-60 cells under UVA irradiation, TMPyP effectively induced apoptosis. Moreover, 8-oxo-7,8-dihydro-2'-deoxyguanosine, an oxidative product of 2'-deoxyguanosine, was accumulated in the DNA of cells treated with photoirradiated TMPyP, whereas only small amounts were observed in ALA-treated cells in the presence of UVA light. TMPyP and UVA caused extensive damage at every guanine residue in DNA fragments obtained from the human p 53 tumor suppressor gene and the c-Ha- ras -1 proto-oncogene, whereas PPIX induced little DNA damage under these conditions. Electron spin resonance spectroscopy using a singlet oxygen (¹O₂) probe and D₂O showed that photoexcited TMPyP generated ¹O₂. These results suggest that photoexcited TMPyP reacts with oxygen to generate ¹O₂, which in turn, oxidizes guanine residues. Taken together, the results demonstrated that TMPyP was localized in the nucleus where it was photosensitized to induce DNA damage, suggesting that TMPyP may have clinical utility as a nucleus-targeted PDT.     

Novel coupling reaction between sulfonyl azide and N,N,N',N'-tetramethylthiourea

The synthesis of sulfonylguanidines from N,N,N',N'-tetramethylthiourea and sulfonyl azides is described. This method serves as an alternative route for generating sulfonylguanidines via the use of stable starting materials.