Stability of porphyrin-calix[4]arene complexes analyzed by electrospray ionization mass spectrometry

The stability of some porphyrin-calix[4]arene sodium-ion complexes were determined by a collision-activated decomposition (CAD) method utilizing electrospray ionization mass spectrometry (ESI-MS). Comparing the values of E(1/2), the collision energy at which the relative intensity of the complex ion is 0.5, we found that the porphyrin-calix[4]arene complex with the higher value of E(1/2) corresponded to that with the larger association constant (Kass), as measured by 1H-NMR in CDCl3. Both our ESI-MS and NMR studies proved that the number of hydrogen bonds and the rigidity of the calix[4]arene stabilized the complex. The ESI-MS technique could be successful in screening the binding affinity in host-guest systems with a small amount of sample.     

Evaluation of thallium-201 myocardial emission computed tomography based on a comparison with postmortem findings

The correlative study of myocardial perfusion assessed by 201Tl myocardial ECT with the pathological finding of the heart was performed in 10 autopsied cases with mean age of 77 years old (range: 60-90 y). In 6 cases with myocardial infarction (MI) 7 perfusion defects were observed, that was, 3 in anteroseptal wall, 1 in anterolateral wall and 3 in posterior wall on the images of SPECT. Seven MIs were also found in postmortem examination. Six MIs were observed at autopsy corresponding to perfusion defect on SPECT images. In one myocardial perfusion defect at inferoposterior portion on SPECT, a non-transmural MI was found at anteroseptum. In one case with valvular disease a false positive result was obtained at posterior wall where neither myocardial necrosis nor fibrosis was observed at autopsy. This case had aortic stenosis due to bicuspid aortic valve by autopsy. The ventricle was divided into 16 segments in each of 4 short axial images to evaluate extent of MI. SPECT for extent of MI showed sensitivity of 81.9%, specificity of 96.0% and diagnostic accuracy of 92.5%. False negative segment was apt to be observed at the surrounding of non-transmural MI or basal half of left ventricle (LV) with transmural MI, while false positive segment was at posterior portion of basal half of LV. It was concluded that myocardial ECT was useful for evaluation of the site and extent of MI.     

Lactone and cyclic ether analogues of platelet-activating factor. Synthesis and biological activities

Six-membered lactone and tetrahydropyran analogues of platelet-activating factor (PAF), 4-11, and related antagonistic derivatives 41-46 were synthesized. None of the delta-lactones 4-7 showed PAF-like activities, while the corresponding cyclic ethers 8, 9 and 11 were slightly active. Some of the cyclic antagonists showed more potent inhibitory activities than the open chain antagonist CV-3988 against platelet aggregation (rabbit platelet-rich plasma, IC50) and hypotension (rat, ID50) induced by C16-PAF: e.g. dl-3-[6-[O-(trans-3-heptadecylcarbamoyloxytetrahydropyran-2- yl)methyl]phosphonoxy]hexylthiazolium (inner salt) (41d) (IC50 5.5 x 10(-7) M, ID50 0.046 mg/kg, i.v.); dl-3-[5-[O-(cis-3-heptadecylcarbamoylthiotetrahydropyran-2- yl)methyl]phosphonoxy]pentylthiazolium (inner salt) (43c) (IC50 5.7 x 10(-7) M, ID50 0.076 mg/kg, i.v.).     

Synthesis of a “molecular rope curtain”: Preparation and characterization of a sliding graft copolymer with grafted poly(ethylene glycol) side chains by the “grafting onto” strategy

A sliding graft copolymer (SGC) with poly(ethylene glycol) (PEG) side chains was prepared by ester formation between terminal carboxyl groups of oxidized PEG methyl ether with molecular weight of 2000 (mPEG2000‐COOH) and hydroxyl groups of a polyrotaxane consisting of PEG and cyclodextrins (CDs). Formation of the SGC structure was confirmed by ¹H NMR, attenuated total reflectance Fourier‐transformed infrared, and gel permeation chromatography. The SGC was soluble in good solvents of PEG and insoluble in poor solvents of PEG. Estimation of the number of grafted mPEG chains suggested a “rope‐curtain” like structure, in which an mPEG chain is connected to each CD ring. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Vanadium-catalyzed green oxidation of benzylic alcohols in water under air atmosphere

The oxidation of alcohols using catalytic amounts of metal complexes is highly attractive from the viewpoint of green chemistry principles. However, examples of metal complex-catalyzed oxidations of alcohols with O₂ using water as the solvent are still rare, and precious metals, high-pressure O₂ or air, and a stoichiometric amount of base are often required. In this study, it was found that an oxovanadium-4,4′-t-Bubpy (4,4′-di-tert-butyl-2,2′-bipyridyl) complex exhibited high catalytic activity in the oxidation of benzhydrols under an atmosphere of O₂ in water as the sole solvent. Interestingly, this catalytic oxidation method could be applied to the gram-scale aerobic oxidation of alcohols in water under the atmosphere.     

Flow Rate Prediction for a Semi-permeable Membrane at Low Reynolds Number in a Circular Pipe

Transport in Porous Media - A concise and accurate prediction method is required for membrane permeability in chemical engineering and biological fields. As a preliminary study on this topic, we...     

Silicon-Based Integrated Optic Pressure Sensor Using Intermodal Interference between TM-Like and TE-Like Modes

In this paper, a silicon-based integrated optic pressure sensor using an intermodal interference between the fundamental TM-like and TE-like modes is described. The sensor consists of a micromachined rectangular diaphragm and a straight polystyrene optical waveguide passing over the diaphragm. Its sensitivity is theoretically known to be strongly dependent on the position of the waveguide over the diaphragm. To experimentally investigate such dependence, we fabricated a sensor with a 1.2 mm ×10 mm ×20 μm diaphragm, over which waveguides were placed at 50 μm intervals. The measured phase sensitivity was 98 mrad/kPa for the waveguide nearest to the diaphragm edge. The measurement was also carried out for the other waveguides. As theoretically expected, the largest sensitivity was obtained for the waveguide nearest to the edge.     

Femtosecond laser-induced stimulation of a single neuron in a neuronal network

We demonstrated the stimulation of neurons at a single-cell level in cultured neuronal network by a focused femtosecond laser. When the femtosecond laser was focused on a neuron loaded with a fluorescent calcium indicator, the fluorescence intensity immediately increased at the laser spot, suggesting that intracellular Ca²⁺ increases in the neuronal cell due to the femtosecond laser irradiation. The probability of Ca²⁺ elevation at the laser spot depended on the average laser power, irradiation time, and position of the focal point along the optical axis, indicating that the femtosecond laser activates neurons because of multiphoton absorption. Moreover, after laser irradiation of a single neuron cultured on multielectrode arrays, the evoked electrical activity of the neurons was demonstrated by electrophysiological systems, which concluded that the focused femtosecond laser could achieve stimulating a single neuron in a neuronal network with high spatial and temporal resolution.     

Nanometric summation architecture based on optical near-field interaction between quantum dots

A nanoscale data summation architecture is proposed and experimentally demonstrated based on the optical near-field interaction between quantum dots. Based on local electromagnetic interactions between a few nanometric elements via optical near fields, we can combine multiple excitations at a certain quantum dot, which allows construction of a summation architecture. Summation plays a key role for content-addressable memory, which is one of the most important functions in optical networks.     

Fibrous and helical calcite crystals induced by synthetic polypeptides containing o-phospho-L-serine and o-phospho-L-threonine

The modification of CaCO(3) crystal growth by synthetic L-Ser(PO(3)H(2)) and L-Thr(PO(3)H(2)) containing polypeptides is described. The amino acids Gly, L-Glu, L-Asp, L-Ser, L-Ala, and L-Lys induced rhombohedral calcite with a rough surface. Dipeptides, Xaa-L-Ser(PO(3)H(2)) (Xaa = Gly, L-Glu, L-Asp, L-Ser, L-Ala and L-Lys) induced vaterite crystals in the lower [Ca(2+)]. On the other hand, L-Ser(PO(3)H(2))-containing polypeptides formed spherical vaterite and fibrous calcite. The characteristic helical calcite was found in the presence of copoly[L-Ser(PO(3)H(2))(75)L-Asp(25)] or poly[L-Ser(PO(3)H(2))(3)-L-Asp]. Fibrous calcite, spherical vaterite, and helical calcite crystals were subjected to XRD and EDX analysis. XRD revealed the specific faces of these crystals. EDX spectra and surface analysis visualized the localization of the polypeptides and CaCO(3) components. Together with TEM and SAED data, we propose hypothetical growth mechanisms for the fibrous and helical calcite crystals.