Study on the intermolecular interaction of C60 and simulations on the orientational properties of C60 in crystals

We developed the new intermolecular interaction model of C(60) with the quantitative accuracy for the molecular orientational properties in crystals. The energy difference (DeltaE) and the activation barrier (E(barrier)) between the two stable orientations (P and H orientations) in crystals are in the values of +14.7 and +260 meV in our model, respectively; these values are in fairly good agreement with the experimental values (DeltaE approximately +11 meV, E(barrier)=+235-+290 meV in experiments). The relaxation calculation for C(60) crystals using our model revealed that there is the reversal of the stable orientations between the P and H orientations under the high H-orientation occupancy (p(H)) in crystals, when p(H)>0.83, DeltaE<0. From the molecular dynamics calculations for C(60) crystals using our model, it is found that the phase transition is induced at T(C)=200-260 K, which is consistent with the experimental value of 260 K. Immediately below T(C), we found a great variety of molecular rotational jumps involving that between the P and H orientations every about 10(-9) s due to the thermal activation. In the high temperature phase (>T(C)), all molecules rotate irregularly like in Brownian motion involving the rotational "slumber" for approximately 10(-12)-10(-11) s.     

Convectional, sedimentary, and drying dissipative patterns of colloidal suspensions of polymer complexes of poly(acrylic acid) with poly(ethylene glycol) and poly(vinyl pyrrolidone)

Convectional, sedimentary, and drying dissipative patterns were observed at room temperature on a cover glass, a watch glass, and a Petri dish during the course of dryness of aqueous suspensions of colloidal polymer complexes of poly(acrylic acid) (HPAA) with poly(ethylene glycol) (PEG) and poly(vinyl pyrrolidone) (PVP). With increase in the molecular weight of the polymer component, the complexes showed from transparent solution stable colloidal dispersion and the sticky aggregates. HPAA25K + PVP25K complex showed bluish colors and the colloidal crystal suspension. Size of the macroscopic broad rings of HPAA25K + PEG decreased as molecular weight of PEG increased. Furthermore, the size increased sharply as the polymer concentration increased in the complex systems HPAA25K + PVP25K. Characteristic microscopic patterns appeared for HPAA + PEG and HPAA + PVP complexes.     

Miscibility of calcium chloride and sodium dodecyl sulfate in the adsorbed film and aggregates

The adsorption, micelle formation, and coagel-particle formation of sodium dodecyl sulfate in the presence of calcium chloride were studied from the viewpoint of mixed adsorption and aggregate formation of inorganic salt and surfactant. Judging from the phase diagrams of adsorption and aggregate formation, negative azeotropy takes place in the mixed adsorption and aggregate formation of calcium chloride and sodium dodecyl sulfate due to electrostatic attraction between calcium and dodecyl sulfate ions. The miscibility of calcium chloride and sodium dodecyl sulfate in the oriented states increases in the order, particle > adsorbed film > micelle. The difference in the miscibility was ascribed to the difference in geometry between the adsorbed film and micelle and to the interaction between bilayer surfaces in the particle. The particle-micelle equilibrium was thermodynamically considered by using the equilibrium composition of aggregates.     

Metabolomics Research in Periodontal Disease by Mass Spectrometry

Periodontology is a newer field relative to other areas of dentistry. Remarkable progress has been made in recent years in periodontology in terms of both research and clinical applications, with researchers worldwide now focusing on periodontology. With recent advances in mass spectrometry technology, metabolomics research is now widely conducted in various research fields. Metabolomics, which is also termed metabolomic analysis, is a technology that enables the comprehensive analysis of small-molecule metabolites in living organisms. With the development of metabolite analysis, methods using gas chromatography–mass spectrometry, liquid chromatography–mass spectrometry, capillary electrophoresis–mass spectrometry, etc. have progressed, making it possible to analyze a wider range of metabolites and to detect metabolites at lower concentrations. Metabolomics is widely used for research in the food, plant, microbial, and medical fields. This paper provides an introduction to metabolomic analysis and a review of the increasing applications of metabolomic analysis in periodontal disease research using mass spectrometry technology.     

Specific oxygen-binding to a polymer-supported N,N-disalicylidenethylenediaminocobalt complex

A polymer membrane containing N,N-disalicylidenethylenediaminocobalt (Co(salen)) was prepared. The Co(salen) supported in the polymer not only worked as a reversible and specific oxygen-adsorbent but discontinuously bound oxygen at the atmospheric oxygen partial pressure of ca. 15 cmHg to give an on-off-like oxygen-binding curve. Oxygen permeation through the Co(salen) membrane was also augmented in the higher upstream oxygen pressure region, which was caused by the specific oxygen-binding to the Co(salen) fixed in the membrane.     

Human serum albumin incorporating synthetic hemes as an O2-carrying hemoprotein: control of O2-binding ability by heme structure

Incorporation of different structured synthetic hemes, 5,10,15,20-tetraphenylporphyrinatoiron(II) derivetives with a covalently linked proximal base [FeP( 1 ) to FeP( 7 )], into human serum albumin (HSA), provides seven types of albumin-heme hybrids (HSA-FeP) with different O₂-binding abilities. An HSA host absorbs a maximum of eight FeP molecules in each case. The obtained all HSA-FePs can reversibly bind and release O₂ under physiological conditions (in aqueous media, pH 7.3, 37°C) as similar as hemoglobin and myoglobin. The difference in the fence structures did not affect the O₂-binding parameters, however the axial histidine coordination significantly increased the O₂-binding affinity, which is ascribed to the low O₂-dissociation rate constants. The most remarkable effect of the heme structure appeared in the half-lifetime (τ_1/2) of the O₂-adduct complex. The dioxygenated rHSA-FeP( 4 ) showed an unusually long lifetime (τ_1/2: 25 hr at 37°C) which is ca. 13-fold longer than that of rHSA-FeP( 1 ).     

Oxygen-carrying plasma hemoprotein “albumin-heme”: nitric oxide binding and physiological responses after administration in vivo

Recombinant human serum albumin complexed with tetraphenylporphinatoiron(II) derivative, “albumin-heme (rHSA-FeP)”, is a synthetic oxygen (O₂)-carrying plasma hemoprotein, which becomes a new class of red blood cell substitute. The UV-vis. absorption and ESR spectroscopy revealed that rHSA-FeP formed six-coordinate nitrosyl complex after exposure of nitric oxide (NO) gas. Although the NO-binding affinity of rHSA-FeP (P_1/2^NO: 1.7 × 10⁻⁶ Torr, pH 7.3, 25°C) is 9-fold higher compared to that of hemoglobin (Hb), the administration of this artificial hemoprotein solution into anesthetized rat does not induce an acute increase in blood pressure (hypertension), which is often observed in Hb-based O₂-carriers due to the depletion of NO (endothelial derived relaxing factor).     

Photon Trapping and the Enhancement of Electronic Excitation Energy Transfer Efficiency Caused by Colloidal Crystals

Summary: The efficiency of electronic excitation energy transfer from photoexcited fluorescein to rhodamine 6G is enhanced by 2.26 times in an exhaustively deionized colloidal silica suspension. This enhancement is caused by the photon trapping effects due to the Bragg reflection of colloidal crystals formed in the suspension. The lower enhancement efficiency of 1.41 times observed for rhodamine B as an acceptor is attributed to the inefficient spectral overlap between donor fluorescence and acceptor absorption bands.