The size-dependent valence and conduction band-edge energies of Cu quantum dots

Ultra-small metal particles having band gaps are regarded as a new class of functional materials. We investigated the size dependencies of the band-edge energies on Cu quantum-dots in the size range of 0.7-2.1 nm. The extremely high conduction band-edge energies owing to the strong quantum-size effects were observed for sizes below 1 nm.

Removal of hexavalent chromium from water by Z-scheme photocatalysis using TiO2 (rutile) nanorods loaded with Au core-Cu2O shell particles

All-solid-state Z-scheme photocatalysts, containing Cu₂O, TiO₂ (rutile), and Au as the electron mediator, were prepared and applied to the reduction of Cr(VI) in aqueous solutions. The Cu₂O-Au-TiO₂ composites were prepared by loading Au core-Cu₂O shell hemisphere particles on TiO₂ (rutile) nanorods using a two-step photocatalytic deposition process. Under ultraviolet-visible (UV-vis) light illumination, the Cu₂O-Au-TiO₂ composites exhibited higher photocatalytic Cr(VI) reduction activities than those exhibited by single TiO₂ (rutile) and Cu₂O. In this reaction, a precipitate containing Cr, which was considered to be Cr(OH)₃, was deposited site-selectively on the Au core-Cu₂O shell particles of the composites, indicating that the reduction site of the composite was Cu₂O, and the reaction proceeded according to the Z-scheme. The Cu₂O-Au-TiO₂ composites also exhibited photocatalytic activity under visible light illumination. The oxidation state of Cu in the Cu₂O-Au-TiO₂ composite gradually changed from Cu(I) to Cu(II) during the photocatalytic Cr(VI) reduction. However the composite maintained its high photocatalytic performance even after oxidation. The role of Au in the Cu₂O-Au-TiO₂ composite was examined by comparing the properties of the Cu₂O-Au-TiO₂ composite with those of the Cu₂O-TiO₂ composite prepared via direct Cu₂O deposition on TiO₂.

Hydrothermal Synthesis and Crystal Structure of a Mixed-Valence Bismuthate, Na3Bi3O8

Four types of bismuth oxides, Na₃Bi₃O₈, NaBiO₃, α-Bi₂O₃, and ε-Bi₂O₃, were obtained by hydrothermal reactions using NaBiO₃·nH₂O in NaOH solution. The crystal structure of a new phase (Na₃ Bi³⁺)Bi₂⁵⁺O₈ ((Na_0.75Bi_0.25)₂BiO₄) was determined by using single crystal X-ray diffraction data, and this compound was found to show a Na₂MnCl₄-related structure with a monoclinic system (space group, Pm) with the following lattice parameters: a = 5.990 (2) Å, b = 3.335 (2) Å, c = 10.108 (2) Å, and β = 91.08 (3)°. The final R-factors R₁ and wR₂ were 0.041 and 0.090 (all data), respectively. The new phase was composed of mixed valence states of Bi (Bi³⁺ and Bi⁵⁺, with a mean Bi valence of 4.30) with five distinct Bi sites, where two Bi⁵⁺ (Bi1 and Bi2) fully occupied the distorted octahedral sites and three Bi³⁺ (Bi3, Bi4, and Bi5) were statistically distributed at the split sites with Na⁺ (Na3, Na4, and Na5). The Na6 site is fully occupied. The distorted Bi⁵⁺O₆ octahedra formed one-dimensional chains via edge-sharing along the b-axis, with the chains held by Bi³⁺/Na⁺ split sites. The structural feature except for the split distribution of Bi³⁺/Na⁺ was classified as a Na₂MnCl₄-type structure. DFT calculations based on a model discounting the split distribution of Bi³⁺/Na⁺ indicated that Bi 6s and O 2p orbitals form sp hybridization at the conduction band. This new mixed valence bismuth oxide exhibited photocatalytic activity for phenol degradation under visible light irradiation. In addition to Na₃Bi₃O₈, the hydrothermal reaction using NaBiO₃·nH₂O in NaOH solution yielded micrometer-sized single crystals of an ilmenite-type NaBiO₃ and two polymorphs of bismuth oxides with monoclinic (α-Bi₂O₃) and orthorhombic (ε-Bi₂O₃) structures, depending on the reaction temperature and NaOH concentration.

Hydrothermal Synthesis and Crystal Structure of a (Ba0.54K0.46)4Bi4O12 Double-Perovskite Superconductor with Onset of the Transition Tc ∼ 30 K

A new superconducting double perovskite was successfully synthesized by a low-temperature hydrothermal reaction at 240 °C. The crystal structure refinement of this double perovskite was done by single-crystal X-ray diffraction, and it had a cubic unit cell of a = 8.5207(2) Å with space group Im3̅m (No. 229). This superconducting double-perovskite chemical composition was estimated by electron probe microanalysis and was similar to the refined data. The superconducting transition temperature of the double perovskite was ∼30 K; the electrical resistivity began to fall at ∼25 K, and zero resistivity occurred below 7 K. Moreover, temperature-dependent resistivity under various magnetic fields and isothermal magnetization measurements ensured the nature of a type II superconductor for the sample. Finally, the metallic nature of the material was investigated by a first-principles study.

Enhanced Supercapacitor Performance Based on CoAl Layered Double Hydroxide-Polyaniline Hybrid Electrodes Manufactured Using Hydrothermal-Electrodeposition Technology

Electrodes with nanosheet architectures can offer the possibility to achieve enhanced energy storage performance. Herein, we have designed and synthesized novel nanosheet structures of CoAl layered double hydroxide (LDH)-polyaniline (PANI) nanocomposite thin films by a hydrothermal-electrodeposition method. The molecular structure, crystal structure, morphology and chemical composition of the composites were characterized by FT-IR, XRD (SXRD), FESEM, and XPS, whereas their electrochemical properties were evaluated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge tests. Compared with the unmodified CoAl LDH, the CoAl LDH-PANI exhibits significantly improved the specific capacitance and cyclic stability. The composite exhibits a high specific capacitance of 528 F/g at a current density of 10 A/g and excellent cyclic stability with an increase of the specific capacitance of 42.7% after 6000 cycle tests. We revealed the degradation behavior of PANI in 1 M KOH/KCl electrolyte, and the active degradation products also further increased the total specific capacitance of the composite. The enhanced electrochemical performance of the nanocomposite can be attributed to its well-designed nanostructure and the synergistic effects of each component. By analyzing the band structure and density of states of CoAl LDH and PANI, we proposed the possible mechanism of synergistic effect in a new perspective.

Hydrothermal Synthesis of Pyrochlore-Type Pentavalent Bismuthates Ca2Bi2O7 and Sr2Bi2O7

The pyrochlore-type Ca₂Bi₂O₇ and Sr₂Bi₂O₇ have been synthesized from a low-temperature hydrothermal route using NaBiO₃·nH₂O as a starting material. The crystal structures of these compounds were refined using synchrotron powder X-ray diffraction data. The cell parameters were found to be a = 10.75021 (5) Å and 10.94132 (6) Å for Ca₂Bi₂O₇ and Sr₂Bi₂O₇, respectively. Density functional theory calculations showed the metallic band structure, but the negligible mixing of O2 2p bands with the A-site alkaline-earth-metal states and weak overlap with the conduction bands result in the semiconducting behavior.

Circumstances of La, Eu, Dy, and Yb Cations Intercalated via Ion Exchange in γ-Zirconium Phosphate

Both α- and γ-zirconium phosphate were examined for use as ion exchangers for recovery of rare earth elements. Trivalent rare earth elements can be partially substituted for protons in the interlayer space, and γ-zirconium phosphate shows a much better ion exchange competency than α-zirconium phosphate. The exchanged cation of the rare earth elements might be related to different amounts of oxygen from P-OH and H₂O, and these rare earth elements were thus positioned at a different separations from the zirconium phosphate layer. The radial structure function (RSF) curve from extended X-ray absorption fine structure data implied that the calibrated M-O distance and coordination number changed with the ionic radius. The calibrated M-O distances from RSF were 2.52, 2.42, 2.38, and 2.28 for La, Eu, Dy, and Yb, respectively. The coordination numbers of oxygen for Yb were approximately 7 and greater than 10 for La and Eu, respectively. These smaller coordination numbers for smaller cations may result from the strong interaction between the cations and the zirconium phosphate layer. The Debye-Waller factor also increased with an increase in the ionic radius. These factors show a strong relation to the coordination state of rare earth elements in the unit cell of the γ-zirconium phosphate and to the interaction strength.

Crystal Structure, Thermal Behavior, and Photocatalytic Activity of NaBiO3· nH2O

The crystal structure of NaBiO₃· nH₂O was refined using synchrotron powder X-ray diffraction and was assigned to a trigonal unit cell (space group P3̅) consisting of layered structures formed by edge-sharing BiO₆ octahedra and consisting of an interlayer composed of water molecules sandwiched between two layers of sodium atoms, perpendicular to the c axis. An intermediate phase was observed during the dehydration of the hydrated compound. Density of state calculations showed hybridization of the Bi 6s and O 2p orbitals at the bottom of the conduction bands for both the hydrated and the dehydrated phases, which narrows the band gap and promotes their photocatalytic activity in the visible region.

Formation of Uniform and High-Coverage Monolayer Colloidal Films of Midnanometer-Sized Gold Particles over the Entire Surfaces of 1.5-in. Substrates

We report a simple and facile method for fabricating monolayer colloidal films of alkanethiol-capped gold nanoparticles (AuNPs) on glass substrates. The new method consists of two sequential sonication processes. The first sonication is performed to obtain a well-dispersed state of alkanethiol-capped AuNPs in hexane/acetone in the presence of a substrate. After additional static immersion in the colloidal solution for 5 min, the substrate is subjected to sonication in hexane. By using this method, we succeeded in forming uniform and stable assemblies of midnanometer-sized AuNPs (14, 34, and 67 nm in diameter) over the entire surface of 10-mm square glass substrates in a short processing time of less than 10 min. It was also demonstrated that this method can be applied to a 1.5-in. octagonal glass substrate. The mechanism of monolayer colloidal film formation was discussed based on scanning electron microscopy observations at each preparation step. We found that the second sonication was the key process for uniform and high-surface-coverage colloidal film formation of midnanometer-sized AuNPs. The second sonication promotes the migration of AuNPs on top of the monolayer in contact with the substrate surface, decreasing both the multilayer region and the bare surface area. Eventually, a nearly perfect monolayer colloidal film is formed.

Adsorption Behavior of Rare Earth Metal Cations in the Interlayer Space of γ-ZrP

Adsorption competencies of rare earth metal cations in γ-zirconium phosphate were examined by ICP, synchrotron X-ray diffraction (SXRD), and ab initio simulation. The adsorption amounts are around 0.06-0.10 per zirconium phosphate. From the SXRD patterns of the adsorbed samples, the basal spacing estimated by c sin β increased linearly with an increasing ionic radius of rare earth metal cation, though a and b lattice constants show no change. These SXRD patterns can be classified into four groups that have different super lattices. The four superlattices have multiplicities of x131, x241, and x221 for the xabc axis, and the location of the rare earth metal cation in the original unit cell changes depending on the superlattice cell. In the x131 superlattice, Yb and Er occupied the site near the zirconium phosphate layer, though La and Ce in the x221 superlattice remained in the center position between the phosphate sheet. For the ab initio simulation of γ-ZrP with the typical rare earth metal cations (Tb, Eu, Dy, and La), the results of simulation show a similar tendency of the position estimated by SXRD refinements.

Assembly of Mid-Nanometer-Sized Gold Particles Capped with Mixed Alkanethiolate SAMs into High-Coverage Colloidal Films

We investigated the influence of the mixed n-alkanethiolate self-assembled monolayer (SAM) formed on gold nanoparticles (AuNPs: 50.0 ± 3.2 nm in diameter) on their assembly into colloidal films. Dodecanethiol and octadecanethiol were selected as the short- and long-chain alkanethiols, respectively. The mixed SAMs were formed by immersing AuNPs in a mixed alkanethiol solution at different molar ratios. Au colloidal films were fabricated on indium tin oxide substrates by our previously reported hybrid method. The composition of the two alkanethiolates in the SAM was deduced from the intensity ratio of two Raman bands at 1080 and 1105 cm(-1). The surface coverage of the colloidal films increased by forming equimolar or dodecanethiolate-dominant mixed SAMs on AuNPs instead of a pure dodecanethiolate or octadecanethiolate SAM. The highest coverage exceeded 80%. This improvement is attributed to the high dispersion stability of AuNPs covered with equimolar or dodecanethiolate-dominant mixed SAMs.

Refractive index susceptibility of the plasmonic palladium nanoparticle: potential as the third plasmonic sensing material

We demonstrate that Pd nanospheres exhibit much higher susceptibility of the localized surface plasmon resonance (LSPR) peak to medium refractive index changes than commonly used plasmonic sensing materials such as Au and Ag. The susceptibility of spherical Au nanoparticle-core/Pd-shell nanospheres (Au/PdNSs, ca. 73 nm in diameter) was found to be 4.9 and 2.5 times higher, respectively, than those of Au (AuNSs) and Ag nanospheres (AgNSs) having similar diameters. The experimental finding was theoretically substantiated using the Mie exact solution. We also showed from a quasi-static (QS) approximation framework that the high susceptibility of Pd LSPR originates from the smaller dispersion of the real part of its dielectric function than those of Au and Ag LSPR around the resonant wavelength. We conclude that the Pd nanoparticle is a promising candidate of "the third plasmonic sensing material" following Au and Ag to be used in ultrahigh-sensitive LSPR sensors.

Preparation of a titania/X-zeolite/porous glass composite photocatalyst using hydrothermal and drop coating processes

Combinations of TiO2 photocatalysts and various adsorbents have been widely studied for the adsorption and photocatalytic decomposition of gaseous pollutants such as volatile organic compounds (VOCs). Herein, a TiO2-zeolite-porous glass composite was prepared using melt-quenching and partial sintering, hydrothermal treatment, and drop coating for preparation of the porous glass support and X-zeolite and their combination with TiO2, respectively. The obtained composite comprised anatase phase TiO2, X-zeolite, and the porous glass support, which were combined at the micro to nanometer scales. The composite had a relatively high specific surface area of approximately 25 m2/g and exhibited a good adsorption capacity for 2-propanol. These data indicated that utilization of this particular phase-separated glass as the support was appropriate for the formation of the bulk photocatalyst-adsorbent composite. Importantly, the photocatalytic decomposition of adsorbed 2-propanol proceeded under UV light irradiation. The 2-propanol was oxidized to acetone and then trapped by the X-zeolite rather than being released to the atmosphere. Consequently, it was demonstrated that the micrometer-scaled combination of TiO2 and zeolite in the bulk form is very useful for achieving both the removal of gaseous organic pollutants and decreasing the emission of harmful intermediates.

Particle size dependence of the surface-enhanced Raman scattering properties of densely arranged two-dimensional assemblies of Au(core)-Ag(shell) nanospheres

We investigated the dependence of the surface-enhanced Raman scattering (SERS) activity of densely arranged two-dimensional assemblies of spherical Au(core)-Ag(shell) nanoparticles (Au/AgNSs) on the nanoparticle diameter. The size-controlled Au/AgNSs were synthesized using the Au nanosphere seed-mediated growth method without any bulky stabilizers. The diameters of the Au/AgNSs were 38, 53, and 90 nm and the ratio of the total diameter to the Au core diameter was adjusted to ca. 2.0. Extinction spectra of the colloidal solutions of these nanoparticles exhibited the prominent peak of the localized surface plasmon resonance (LSPR) of Ag and therefore the Au/AgNSs exhibited LSPR properties almost the same as Ag nanospheres. It was confirmed from SEM observation that the organic solvent-mediated liquid-liquid interface assembly technique easily generated densely arranged two-dimensional assemblies of the nanospheres. The extinction spectra of all the assemblies exhibited a prominent broad peak ranging from 500 nm to the near-infrared region, which is assigned to the longitudinal LSPR mode of the coupling nanospheres. The extinction intensity increased with increasing nanosphere diameter. The SERS activities of these assemblies were investigated using p-aminothiophenol as a probe molecule. The result revealed that the enhancement factor (EF) of the Raman signal dramatically increased upon increasing the particle diameter. The maximum EF obtained with a laser excitation wavelength of 785 nm was 1.90 × 10(6) for a nanosphere diameter of 90 nm. This renders the two-dimensional assemblies of the plasmonic Au/AgNSs promising for the development of highly sensitive SERS sensor platforms due to their strong electromagnetic effect.

Various factors affecting photodecomposition of methylene blue by iron-oxides in an oxalate solution

The effect of various factors on the photodecomposition of methylene blue (MB) by iron oxides calcined at various temperatures in various concentrations of oxalate solutions was investigated by illuminating with UV, visible and solar radiation. Iron oxides were prepared by a gel evaporation method and calcined at 200-700 degrees C. XRD showed that the as-synthesized iron oxides were amorphous, but formed maghemite (gamma-Fe(2)O(3)) at 200-400 degrees C and hematite (alpha-Fe(2)O(3)) at > or =500 degrees C. The effect of the various iron oxides, their contents, the oxalate concentration and wavelength of the light source (UV, visible and solar) were all found to strongly influence MB photodecomposition. The optimal contents of the iron oxides increased greatly from 25 to 2000 mg/L at higher calcining temperatures. The MB photodecomposition rate at each optimal iron oxide content was related to the calcining temperature in the order 700 degrees C<uncalcined<500 degrees C<400 degrees C<300 degrees C. The MB degradation was confirmed to occur by visible light illumination. Excellent photodecomposition was found at pH 2-5, but the photodegradation decreased greatly at pH>6, consistent with the presence of iron-oxalate complexes. A much higher concentration of hydroxyl radicals was generated in the present system compared with those from a commercial TiO(2) (ST-01), as determined by the coumarin method. Since this process does not require the addition of hydrogen peroxide and shows good efficiency even under solar light, it is an economically viable method for pre-treating and/or decolorizing wastewaters containing dyes.

Lymphatic invasion using D2-40 monoclonal antibody and its relationship to lymph node micrometastasis in pN0 gastric cancer

The monoclonal antibody D2-40 is a specific lymphatic endothelial markers and D2-40 staining have been applicable to evaluate lymphatic invasion in various malignant neoplasms. In the present study, we investigated lymph node micrometastasis determined by immunohistochemistry (IHC) and reverse transcription–polymerase chain reaction (RT–PCR) in all dissected lymph nodes obtained from 80 patients with node-negative gastric cancer, and analysed the relationship between micrometastasis and clinicopathological findings including lymphatic invasion of the resected primary tumour using D2-40 immunohistochemical staining. The incidence of micrometastasis determined by IHC and RT–PCR was 11.3% (nine out of 80) and 31.3% (25 out of 80), respectively. Although haematoxylin–eosin (HE) staining revealed lymphatic invasion in 11.3% (nine out of 80) of patients, D2-40 staining uncovered new invasion in 23.8% (19 out of 80) of patients. In the diagnosis of HE and D2-40 staining, the incidence of micrometastasis was significantly higher in patients with lymphatic invasion than in those without lymphatic invasion (P=0.0150 and P<0.0001, respectively). Micrometastasis correlated more closely with D2-40 than with HE staining. We demonstrated a high incidence of micrometastasis and lymphatic invasion and a correlation between them even in pN0 gastric cancer. When planning less invasive treatment, the presence of such occult cancer cells should be considered.

Infusion of maintenance fluids with glucose (Veen 3G) is superior to maltose infusion (Actit) in the rate of energy utilization in rabbits

In the present study, we examined the rates of urinary excretion of glucose and maltose after an infusion of maintenance fluid with glucose or maltose in adult rabbits. Three maintenance fluids (sugar-free, 5% glucose [Veen 3G] and 5% maltose [Actit]), which contained different sugars but were identical in electrolyte and acetate compositions and concentrations (Na: 45, K: 17, Mg: 5, Cl: 37, H2PO4: 10 and CH3COO: 20 mEq/l), were used in this study. In addition, the optimum infusion speed for maintenance therapy (10 ml/kg/h) was used. Animals were not given food or water during the 10-day period of administration. The body weights of the animals were measured every day. The concentrations of total protein, albumin, free fatty acids and glucose in the serum were measured. Urine samples for determination of glucose and maltose concentrations were collected from the 1st to 10th administrations. After infusion with 5% maltose, urinary maltose excretion decreased time-dependently, while that of glucose increased. This suggests that maltase activity time-dependently increases after infusion with maltose. In addition, total sugar was only minimally excreted into urine in the 5% glucose group compared with the 5% maltose group. Thus, the glucose infusion was superior to the maltose infusion in the rate of energy utilization. However, neither the loss of body weight nor the increase in concentration of free fatty acids in serum differed significantly among the 3 groups. In conclusion, infusion of maintenance fluid with 5% maltose results in the excretion of maltose and glucose into urine, since enzymatic hydrolysis of maltose to glucose is limited to that by maltase.

Photoreductive dehalogenation of halogenated benzene derivatives using ZnS or CdS nanocrystallites as photocatalysts

ZnS nanocrystallites (nc-ZnS) prepared in N,N-dimethylformamide (DMF) photocatalyze dehalogenation of halogenated benzenes to benzene as the final product from chlorinated benzenes and to difluorobenzenes from fluorinated benzenes in the presence of triethylamine (TEA) as an electron donor under UV light irradiation (lambda > 300 nm). When CdS nanocrystallites (nc-CdS) are used as a photocatalyst (lambda > 400 nm), halogenated benzenes are photoreductively dehalogenated, yielding trichlorobenzene from hexachlorobenzene and tetrafluorobenzene isomers from hexafluorobenzene as the final products. Photoformed electrons on nc-ZnS and nc-CdS have such negative reduction potentials that these electrons reduce polyhalogenated benzenes, leading to the successive dehalogenation. nc-ZnS exhibits higher photocatalytic activitythan nc-CdS due to the more negative potential of the electrons on nc-ZnS than that on nc-CdS. The higher activities of nc-ZnS and nc-CdS compared to their bulk forms are explained as being due to their quantum size effects and the adsorptive interaction between the substrates and the nanosized photocatalysts.

Establishment and characterization of cell lines derived from serous adenocarcinoma (JHOS-2) and clear cell adenocarcinoma (JHOC-5, JHOC-6) of human ovary

The cell lines designated JHOS-2, JHOC-5 and JHOC-6 were established from epithelial ovarian carcinomas. JHOS-2 was established from a serous adenocarcinoma of a 45-year-old Japanese woman, JHOC-5 from a recurrent tumor of a clear cell adenocarcinoma of a 47-year-old Japanese woman and JHOC-6 from a tumor of a clear cell adenocarcinoma of a 43-year-old Japanese woman. These cell lines have grown well and serial passages were successively carried out more than 20 times. The monolayer cultured cells revealed neoplastic and pleomorphic features, and grew in multilayers. Electron micrographs revealed epithelial origins that had desmosomes and tonofilaments.

Design and synthesis of cholestane derivatives bearing a cascade-type polyol and the effect of their property on a complement system in rat serum

The beta-cholestane derivatives 1a-c bearing a cascade-type polyol, were newly synthesized. The release of fluorescent marker 6-CF [5(6)-carboxyfluorescein] encapsulated in the modified liposomes prepared from 1 was dramatically faster than that in the conventional liposomes prepared from cholesterol.

Relation of abdominal and thigh adipose tissue distribution to serum lipids and glucose metabolism in obese males

Spin-echo magnetic resonance imaging (MRI) and postprocessing for fat quantification were used to examine the relationship of abdominal and thigh adipose-tissue distribution to serum lipids and glucose metabolism in obesity. Thirteen simple obese male patients and 12 non-obese male volunteers were examined by MRI, blood pressure, and fasting blood sample levels of serum lipids, glucose, immunoreactive insulin, c-peptide, HbA1C and hematocrit. Correlations of thigh visceral and subcutaneous fat areas to serum lipid levels were generally similar, but marked differences were found between relationships of thigh versus abdominal fat areas to serum lipid levels. In addition, diastolic blood pressure was significantly correlated with the fat area, especially with the abdominal visceral fat area (r=0.51, p<0.01), but not with abdominal subcutaneous fat area. The thigh muscle area was highly and inversely correlated with c-peptide (r=-0.72, p<0.01) and systolic blood pressure (r=-0.65). Differences in correlations between visceral and subcutaneous fat areas in the abdomen to metabolic parameters were found between abdominal visceral fat areas and HbA1C and between the abdominal subcutaneous fat areas and HbA1C. These findings suggest that the character of regional fat could be heterogeneous with respect to lipid and glucose metabolism and blood pressure levels in obese males.

Imaging techniques for measuring adipose-tissue distribution in the abdomen: a comparison between computed tomography and 1.5-tesla magnetic resonance spin-echo imaging

Eight subjects were examined both by abdominal X-ray computed transverse axial tomography (CT) and magnetic resonance imaging (MRI) (SE) (TR/TE, 200 ms/15 ms); another eight volunteers were subjected to three MRI scans to test the reliability of repeated measures. Correlations between fat area measures obtained by CT and by MRI for subcutaneous fat, total fat, and visceral vs. subcutaneous-fat ratio were highly significant (r = 0.93, 0.91, and 0.94, respectively; p < 0.01), and the standard errors of estimation were 9.99, 23.87, and 0.0047. The average errors of the method for different fat areas were 2.20 cm2 (intra-examination variance) and 3.75 cm2 (inter-examination variance) for visceral and 0.82 cm2 (intra-examination variance) and 1.29 cm2 (inter-examination variance) for subcutaneous fat areas, respectively. These results suggest that SE MRI is a practical approach to evaluate body fat distribution without the exposure to radiation. The reproducibility of SE MRI for the determination of fat areas is high; variation is small and acceptable. However, it is difficult to determine which estimate of fat area should be accepted when there is a discrepancy between MRI and CT measures.

Simultaneous multicompartment intracellular Ca2+ measurements in the perfused heart using 19F NMR spectroscopy

Although Ca2+ transport regulation at subcellular organelles is of great interest, only limited methodology has been available for measuring organellar [Ca2+] levels. The present study employs the 19F NMR resonance frequency of 4F-BAPTA to measure free [Ca2+]. In 4F-BAPTA loaded perfused rabbit hearts, two 19F NMR resonances were clearly observed. The frequency of one was consistent with cytosolic [Ca2+] levels. Responses to agents that after sarcoplasmic reticulum function identified the other resonance as originating from that organelle. The experiments demonstrate the utility of NMR shift indicator methodology in obtaining simultaneous multi-compartment intracellular [Ca2+] measurements and in enabling organellar [Ca2+] measurements to be made from within intact living tissue.

In vitro evaluation of antithrombogenicity of hybrid-type vascular vessel models based on analysis of the mechanism of blood coagulation

In vitro evaluation of antithrombogenicity of materials of artificial vascular vessels was carried out based on an analysis of the coagulation mechanism of blood. Coagulation of blood in tubes coated with endothelial cells (ECs) or segmented polyurethane (SPU) was measured by a rheological technique. Coagulation of blood in hybrid-type vascular vessel model tubes consisting of cultured ECs proliferated on carbon-deposited SPU was also examined. Coagulation of blood in these tubes occurred within 40 min, and appears to be due to the interaction between erythrocytes and a coagulant factor in plasma. From the in vitro evaluation test, when the time of onset of the coagulation of blood in contact with a surface of the artificial materials is longer than 20-39 min, the materials can be considered to provide an inert surface against thrombus formation and blood coagulation.

Nuclear magnetic resonance studies of cationic and energetic alterations with oxidant stress in the perfused heart. Modulation with pyruvate and lactate

The postischemic generation of oxygen-derived free radicals may contribute to myocardial reperfusion injury by affecting sarcolemmal ion transport. Recent evidence indicates that exposure to reactive oxygen intermediates induces rapid increases in myocardial cytosolic free Ca2+ (Ca2+i). The mechanism is undetermined but may involve disturbances in Na+ homeostasis. We tested this hypothesis by interleaving 23Na and 31P nuclear magnetic resonance (NMR) measurements of Na+i and high-energy phosphates in glucose-perfused rat hearts exposed to hydroxyl radicals generated from H2O2 and Fe3+. In separate experiments, K+i and Ca2+i were measured with 39K and 19F NMR, respectively. The hearts rapidly exhibited contracture. Threefold Na+i increases and substantial K+i depletion were observed. Glycolytic inhibition was indicated by rapid sugar phosphate accumulation and cellular energy depletion. Notably, however, severe functional and energetic deterioration and substantial elevation of Ca2+i occurred before substantial Na+i accumulation or K+i depletion was observed. Further experiments investigated the ability of pyruvate to scavenge H2O2 and to protect the myocardium from oxidant stress. Pyruvate (1 or 2.5 mmol/L) dramatically attenuated functional and energetic alterations and alterations in Na+i and K+i, whereas acetate (2.5 mmol/L) offered no protection. Unlike pyruvate, lactate (5 mmol/L) has little or no capacity to scavenge H2O2 but has similar protective effects. In conclusion, pyruvate effectively protects against H2O2/Fe3+, largely by direct H2O2 scavenging. Protection with lactate may involve intracellular pyruvate augmentation. Without exogenous pyruvate or lactate, myocardial Na+ homeostasis can be substantially altered by oxidant stress, possibly via cellular energy depletion. Excess Na+i accumulation may, in turn, hasten metabolic and functional deterioration, but a causal link with the initial alterations in function or Ca2+i was not supported.

23Na and 31P nuclear magnetic resonance studies of ischemia-induced ventricular fibrillation. Alterations of intracellular Na+ and cellular energy

To clarify the role of Na+i, pHi, and high-energy phosphate (HEP) levels in the initiation and maintenance of ischemia-induced ventricular fibrillation (VF), interleaved 23Na and 31P nuclear magnetic resonance spectra were collected on perfused rat hearts during low-flow ischemia (51 minutes, 1.2 mL/g wet wt). When untreated, 50% of the hearts from normal (sham) rats and 89% of the hypertrophied hearts from aorticbanded (band) rats (P < .01 versus sham) exhibited VF. Phosphocreatine content was significantly higher in sham than band hearts during control perfusion (53.3 +/- 1.6 versus 39.8 +/- 2.0 mumol/g dry wt). Before VF at 20 minutes of ischemia, Na+i accumulation was greater in hearts that eventually developed VF than in hearts that did not develop VF for both band and sham groups (144% versus 128% of control in sham; P < .005) and was the strongest metabolic predictor of VF; ATP depletion was also greater for VF hearts in the sham group. Infusion of the Na(+)-H+ exchange inhibitor 5-(N,N-hexamethylene)-amiloride prevented VF in sham and band hearts; reduced Na+i accumulation but similar HEP depletion were observed compared with VF hearts before the onset of VF. Rapid changes in Na+i, pHi, and HEP began with VF, resulting in intracellular Na+i overload (approximately 300% of control) and increased HEP depletion. A delayed postischemic functional recovery occurred in VF hearts, which correlated temporally with the recovery of Na+i. In conclusion, alterations in Na+i were associated with spontaneous VF transitions, consistent with involvement of excess Na+i accumulation in VF initiation and maintenance and with previously reported alterations in Ca2+i with VF.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effects of verapamil and adenosine treatment on high energy phosphate metabolism in ischemic and reperfused myocardium

Isolated rat hearts were subjected to retrograde perfusion to investigate the protective effects of adenosine and verapamil on the myocardium. In group 1, the perfusate was standard Krebs-Henseleit buffer solution. The perfusate was changed to Krebs-Henseleit buffer containing verapamil (100 nM) in group 2, adenosine (100 microM) in group 3 and both drugs in combination in group 4 for 30 min before ischemia and during 20 min of reperfusion. Group 2 displayed a recovery of creatine phosphate but not of ATP at the end of reperfusion. In group 4, the recovery of both ATP and creatine phosphate was significantly greater than in group 1. The coronary flow of group 4 was significantly higher than that of the other groups. Treatment with both verapamil and adenosine before and after global ischemia may protect the ischemic myocardium by improving high energy phosphate metabolism and coronary circulation.

Comparative measurement of myocardial ATP and creatine phosphate by two chemical extraction methods and 31P-NMR spectroscopy

Changes in ATP and creatine phosphate levels during early (up to 150 s) global ischaemia were determined in isolated rat hearts by two chemical extraction methods (a conventional direct perchloric acid extraction and a stepwise extraction using alcohol and perchloric acid solutions) and by qualitative 31P-NMR. No difference in the ATP level hardly changed up to 40 s of ischaemia when measured by the three methods, and slightly decreased at 150 s of ischaemia. In contrast to ATP, creatine phosphate content in the normally perfused tissue was observed to be higher by the stepwise extraction (68-73 nmol/mg protein) than by direct perchloric acid extraction (55 nmol/mg protein). The creatine phosphate rapidly decreased to about 50% of normal value at 40 s of ischaemia, and the difference in the normal creatine phosphate content using the two chemical methods disappeared with the progression of ischaemia. Thus, the creatine phosphate more rapidly decreased when observed by the stepwise method than by the other two methods in this ischaemic condition. These results suggest that (1) creatine phosphate exists in an undetermined chemical state (perhaps neither in simple soluble form nor in so-called "bound" form) in rat cardiac myocytes, and (2) the stepwise extraction method is useful to measure the content of energy metabolites and to examine the intracellular chemical state in cardiac tissues.

Flavin-photosensitized monomerization of dimethylthymine cyclobutane dimer in the presence of magnesium perchlorate

We have investigated the photosensitized monomerization of the cis,syn-cyclobutane dimer of 1,3-dimethylthymine using riboflavin tetraacetate and a 5-deazaflavin derivative as photosensitizer. Although little monomerization of the dimer is induced by photoexcitation of the flavins in the absence of any additives, the flavins can function as an efficient photosensitizer in the presence of magnesium perchlorate. Mechanistic studies involving spectroscopic, quantum-yield and flash-photolysis measurements demonstrated that the photosensitized monomerization exclusively proceeds through electron transfer from the dimer to the triplet flavins complexed with Mg2+. The effects of magnesium perchlorate are compared with those on the chloranil-photosensitized monomerization and also with the effects of HClO4 on the flavin-photosensitized reaction.

Enhanced myocardial adenylate cyclase activity in spontaneously hypertensive rats

This study was designed to clarify the state of beta-adrenergic signal transduction and the disordered level of its transduction in hypertensive hearts, using myocardium from spontaneously hypertensive rats (SHR) as a generic model of essential hypertension. Beta-adrenergic receptor binding sites and dissociation constants in the extracted membranes of adult (70-100 days of age) SHR heart were not significantly different from those of Wistar-Kyoto (WKY) rats, the non-hypertensive control. The adenylate cyclase activities stimulated by isoproterenol with GTP, NaF and forskolin were significantly higher in SHR compared to those in WKY. To determine whether differences in signal transduction are natural or are a result of hypertension, we evaluated chronotropic responses in cultured cells of fetal hearts which had not been exposed to hypertension. Fetal cardiac muscle cells of SHR were more sensitive than WKY to isoproterenol stimulation over a wide concentration range. However, there were no statistically significant differences between these two strains with respect to the density of binding sites. These results suggest that in the transduction of adrenergic signals, alterations distal to the beta-receptors are present in the adult hearts of hypertensive rats, and, that the adrenergic signal transduction is already exaggerated in the pre-hypertensive fetal stage.

Angioscopic coronary macromorphology in patients with acute coronary disorders

To investigate the pathogenesis of acute coronary disorders and to clarify what type of plaque precedes these disorders, percutaneous transluminal coronary angioscopy, by means of a new angioscope, was carried out during catheterisation in 100 consecutive patients anatomically suitable for such investigations. The quality of the angioscopic image was good enough for analysis in 84 patients (14 with acute myocardial infarction [within 8 h of onset], 16 with recent myocardial infarction [3 days-2 months since onset], 24 with old myocardial infarctions, 10 with unstable angina, and 20 with stable angina). Thrombi were observed in most patients with acute coronary disorders (all 14 with acute myocardial infarction, 9 of 10 with unstable angina). Occlusive thrombi were more common in patients with acute myocardial infarction than in those with unstable angina (11 [79%] vs 1 [10%]; p less than 0.001), whereas mural (non-occlusive) thrombi were more common in the unstable angina than in the acute myocardial infarction group (8 [80%] vs 3 [21%]; p less than 0.001). Xanthomatous ulcerated plaques or ragged irregular surfaces were seen in patients with acute coronary disorders and in those with recent myocardial infarction. Xanthomatous plaques were more common in patients with acute coronary disorders (50%) than in those with stable angina (15%) or old myocardial infarction (8%). By contrast white and smooth plaques were seen in cases of stable angina and old myocardial infarction. Angioscopy could display the intracoronary lumen more precisely than could coronary arteriography. This angioscopic study suggested that, although a thrombus overlying a rupture in the lining of the plaque was common in both unstable angina and acute myocardial infarction, the character of the thrombus may differ between these disorders, and lipid-rich xanthomatous plaque may precede rupture.