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Background: Coronary flow velocity reserve (CFVR) is used to evaluate the severity of epicardial and intramyocardial coronary artery disease. Collateral flow to an adjacent compromised myocardial territory may influence the CFVR of a specific artery. Methods: To assess the impact of collateral flow on CFVR, we measured CFVR and assessed perfusion area (PA) with myocardial contrast echocardiography in the right coronary arteries of 18 patients with total/subtotal occlusion of the left anterior descending coronary artery before and after angioplasty. A total of 10 patients had well-developed collaterals emerging from the right coronary artery (group I) and 8 patients did not (group II). Using a Doppler-tipped guidewire, we measured CFVR, which is defined as the ratio of papaverine-induced hyperemic average peak velocity of coronary flow to baseline. Results: Before angioplasty of the left anterior descending coronary artery, CFVR was significantly reduced in group I compared with group II (2.35 +/- 0.47 vs 3.26 +/- 0.54, P < .01). Baseline average peak velocity in group I before angioplasty was significantly greater than that after angioplasty (23.7 +/- 11.6 vs 19.2 +/- 9.7 cm/s, P < .05). After angioplasty, CFVR immediately increased in group I to 3.46 +/- 0.54 (P < .001). The increase in CFVR was well correlated with the decrement in PA after angioplasty (r = 0.883, P < .001). Conclusion: The CFVR of an artery that supplies extensive collaterals is limited because of an elevation in the baseline resting flow velocity. This restriction in CFVR improves proportionally with decreases in PA that occurs after angioplasty of the ipsilateral coronary artery. These data suggest that PA, in addition to coronary artery structure, influences CFVR.

Hemophilia is considered suitable for gene therapy because it is caused by a single gene abnormality, and therapeutic coagulation factor levels may vary across a broad range. Recent success of hemophilia B gene therapy with an adeno‐associated virus (AAV) vector in a clinical trial showed the real prospect that, through gene therapy, a cure for hemophilia may become a reality. However, AAV‐mediated gene therapy is not applicable to patients with hemophilia A at present, and neutralizing antibodies against AAV reduce the efficacy of AAV‐mediated strategies. Because patients that benefit from AAV treatment (hemophilia B without neutralizing antibodies) are estimated to represent only 15% of total patients with hemophilia, the development of basic technologies for hemophilia A and those that result in higher therapeutic effects are critical. In this review, we present an outline of gene therapy methods for hemophilia, including the transition of technical developments thus far and our novel techniques.

Summary. Background:Transplantation of cells overexpressing a target protein represents a viable gene therapeutic approach for treating hemophilia. Here, we focused on the use of autologous mesenchymal stem cells (MSCs) expressing coagulation factor for the treatment of coagulation factor VIII (FVIII) deficiency in mice.

Diffuse optical remission spectra from the mammalian neocortex at visible wavelengths contain spectral features originating from the mitochondria. A new algorithm is presented, based on analytically relating the first differential of the attenuation spectrum to the first differential of the chromophore spectra, that can separate and calculate the oxidation state of cytochrome c as well as the absolute concentration and saturation of hemoglobin. The algorithm is validated in phantoms and then tested on the neocortex of the rat during an anoxic challenge. Implementation of the algorithm will provide detailed information of mitochondrial oxygenation and mitochondrial function in physiological studies of the mammalian brain.

Background: Hemophilia A is a congenital bleeding disorder caused by a deficiency of coagulation factor VIII. Approximately 30% of hemophilia A patients develop inhibitors against FVIII following replacement therapy. We have reported that neonatal exposure of FVIII antigen can induce antigen-specific immune tolerance by interferon-γ (IFN-γ)-dependent T-cell anergy in hemophilia A mice. Objective: The thymus plays crucial roles in self-tolerance, with negative selection of self-reactive effector T cells and positive selection of self-reactive regulatory T cells. We investigated the possibility of the induction of antigen-specific immune tolerance by intrathymic injection of FVIII in hemophilia A mice. Methods: Hemophilia A mice were injected with recombinant FVIII into the thymus under real-time high-resolution image guidance. Results: Anti-FVIII inhibitory antibody titers in mice challenged with intravenous administration of FVIII were significantly lower in mice (n = 22) that had received thymic FVIII injection than in mice (n = 18) without thymic injection (9.4 ± 2.3 vs. 122.5 ± 27.6 BU mL−1, respectively, P=0.00078). The CD4+T cells from thymic-injected mice could not proliferate or produce interleukin (IL)-2, IL-12 and IFN-γ in response to FVIII. The CD4+CD25+T cells generated from thymic-treated mice but not from naïve mice efficiently suppressed the in vitroproliferative response of CD4+T cells and blocked the in vivodevelopment of anti-FVIII antibodies in the adoptive transfer. Conclusion: These data suggest that intrathymic administration of FVIII could result in immune tolerance by induction of FVIII-specific regulatory T cells.

Objective:The main objective was to study the relationships of the molecular defects in 38 dysfibrinogens with their fibrin networks. Methods and results:Scanning electron microscopic analyses revealed that all the fibrins formed under the same conditions had networks composed of either normal thickness fibers or thin fibers, accompanied by a variety of alterations in the network structure and characteristics. We classified these fibrin networks into five classes, designated normal, less-ordered, porous A, porous B and lace-like networks. The dysfibrinogens with defects in fibrinopeptide A release or the E:D binding sites formed normal or less-ordered networks, while those with defects in the D:D association formed porous A networks composed of many tapered terminating fibers, despite having fibers of normal width, and containing many pores or spaces. The porous B and lace-like networks were composed of highly branched thin fibers because of defects in the lateral association among protofibrils, and the major difference between them was the porosity of the porous B networks. All the porous B networks were easily damaged by mechanical stress, whereas the lace-like networks retained high resistance to such stress, indicating that the network strength was not dependent on the fiber width, but on the porosity that led to fragility of the network. Conclusion:Impairment of the D:D association is the major disturbing factor that leads to the formation of porous fibrin networks. The porosity may be introduced by severe impairment of the D:D association, as well as the lateral association, as has often been observed by extra glycosylation or defects in Ca2+binding.

Objectives:Although the concept of aspirin resistance is extensively reported in medical literature, its precise mechanisms and clinical outcomes are largely unknown. In this study, we examined individual thromboxane biosynthesis and platelet aggregation in aspirin‐treated patients, and whether the results of a platelet aggregation test influenced clinical outcomes. Results:Subjects taking 81 mg of aspirin (n = 50) and controls (n = 38) were evaluated for platelet aggregation and platelet cyclooxygenase‐1 (COX‐1) activity by measuring collagen‐induced thromboxane B2production. For aggregometry, both light transmission (LT) and laser‐light scattering methods were employed to quantitatively evaluate aggregate sizes and numbers. Aspirin treatment resulted in the inhibition of collagen‐induced platelet aggregation, particularly the transition from small to large platelet aggregates. Although platelet COX‐1 activity seemed to be uniformly inhibited in all patients, platelet aggregation studies showed great inter‐individual differences; variation in platelet COX‐1 activity only accounted for 6–20% of the individual aggregations. Factor analysis revealed the existence of a common factor (other than platelet COX‐1) that explained 48.4% of the variations in platelet aggregation induced by collagen, adenosine diphosphate (ADP), and collagen‐related peptide. We then prospectively enrolled 136 aspirin‐treated patients in our study, and we found that being in the upper quartile level of LT, or with large aggregate formation induced by collagen, was an independent risk factor for developing cardiovascular events within 12 months [hazard ratio (HR) = 7.98, P = 0.008 for LT; HR = 7.76, P = 0.007 for large aggregates]. On the other hand, the existence of diabetes mellitus was an independent risk factor for overall outcomes (HR 1.30–11.9, P = 0.015–0.033). Conclusions:Aspirin resistance expressed as unsuppressed platelet COX‐1 activity is a rare condition in an out‐patient population. Other factor(s) affecting collagen‐induced platelet aggregation may influence early outcomes in aspirin‐treated patients.

A novel type of organic−inorganic hybrid zeolite has been successfully synthesized, in which lattice oxygen atoms are partially superseded by methylene groups. Various types of hybrid materials with the LTA, MFI, and *BEA structures are obtained from an organosilane in which a methylene group bridges two silicon atoms under synthesis conditions similar to those for conventional zeolites. The presence of a methylene group in the framework is demonstrated by ²⁹Si and ¹³C MAS NMR and IR, although the Si−C bonds are partially cleaved during the hydrothermal synthesis to give rise to terminal methyl groups. The organic framework is thermally stable enough to remain after the combustion of the occluded organic structure directing agents (SDAs). The thermal stability of the organic framework is much higher than that in amorphous materials synthesized from the same silicon source and is dependent on the zeolite structures. The SDA-free materials not only show microporosity like ordinary zeolites but also exhibit distinctively high lipophilicity/hydrophobicity in a shape-selective way. These findings clearly indicate that these materials are not physical mixtures of conventional inorganic zeolites and amorphous organic-containing materials but contain true organic−inorganic hybrid zeolites.

Hydrodehalogenation of CBrClF2, CCl2F2, CHClF2, and CH2F2 with hydrogen has been studied in the gas phase and over supported Pd catalysts in a tubular alumina reactor. During gas-phase reactions, selectivity to CH2F2 is low for the hydrodehalogenation of CBrClF2, CCl2F2, and CHClF2. CHClF2 is the primary product for the hydrodehalogenation of CBrClF2 and CCl2F2, whereas C2F4 is the major product for the hydrodehalogenation of CHClF2. Over Pd/C catalysts, CH2F2 is the primary product, with selectivities generally over 60% for the hydrodehalogenation of CBrClF2, CCl2F2, and CHClF2. Halocarbons and hydrogen compete for the available surface sites on Pd, and it is suggested that the rate-limiting step during the catalytic hydrodehalogenation of the four halocarbons involves the cleavage of C−halogen bonds, that is, C−Br in CBrClF2, C−Cl in CCl2F2 and CHClF2, and C−F in CH2F2.

Bronchial asthma is a complicated and diverse disorder affected by genetic and environmental factors. It is widely accepted that it is a Th2-type inflammation originating in lung and caused by inhalation of ubiquitous allergens. The complicated and diverse pathogenesis of this disease is yet to be clarified. Functional genomics is the analysis of whole gene expression profiling under given condition, and microarray technology is now the most powerful tool for functional genomics. Several attempts to clarify the pathogenesis of bronchial asthma have been carried out using microarray technology, providing us some novel pathogenic mechanisms of bronchial asthma as well as the information of gene expression profiling. In this article, we review the outcomes of these analyses by the microarray approach as applied to bronchial asthma.

Inhibitory antibody formation is the most serious complication of factor (F)VIII replacement therapy in hemophilia A patients. FVIII‐deficient mice were used to study new approaches for induction of immune tolerance. Neither antiFVIII inhibitory antibodies nor antiFVIII IgGs were observed in 13 of 14 adult mice that received 0.05 U g−1body weight of human FVIII intravenously within 24 h after birth and repeated injections as adults. In contrast, high FVIII antibody titers (>50 Bethesda Units mL−1) developed in seven of 13 mice injected on day 3 postpartum and in all adult mice not treated neonatally. One of nine mice and three of 17 mice developed high‐titer antiFVIII inhibitory antibody when they were treated initially with 2‐fold (0.1 U g−1body weight) and 10‐fold higher doses (0.5 U g−1body weight) FVIII on day 0, respectively. A human FVIII‐specific T‐cell proliferative response was absent in splenocytes from neonatally treated mice. The tolerance was FVIII specific because antitoxoid antibodies developed after immunization with tetanus toxoid. Splenocytes failed to proliferate or produce interferon (IFN)‐γ in response to FVIII stimulation, yet still secreted interleukin‐2. A proliferative response was restored with exogenous IFN‐γ or interleukin‐12, suggesting that lack of inhibitor to FVIII was due to IFN‐γ‐dependent anergy. Thus, exposure on day 0 to physiological levels of FVIII antigen might be important for induction of immune tolerance. This immune tolerance model may provide a basis for new approaches to prevention of FVIII inhibitors during replacement therapy.

After screening for species‐specific antihuman factor (F)IX monoclonal antibodies, we found that antibody 3A6 did not bind to cynomolgus FIX. The 3A6 epitope was found to include Ala262 of human FIX. The 3A6 antibody was used as a catching antibody in an enzyme immunoassay (EIA) for specific detection of human FIX in cynomolgus macaque plasma. No significant increase of substrate hydrolysis was observed when EIA buffer containing cynomolgus macaque plasma was subjected to the 3A6‐based EIA. Addition of up to 30% cynomolgus macaque plasma or canine plasma to the assay did not alter detection of human FIX. Three cynomolgus macaques were injected with human FIX (10 U kg−1; i.v.) and the circulating human FIX was quantified in the macaque plasma. The FIX level in the circulation increased to 470 ± 37.6 ng mL−1at 1 h after the injection and gradually decreased to 1.79 ± 1.1 ng mL−1by day 5, which is approximately 0.06% of the normal human plasma FIX concentration. These data suggest that the cynomolgus macaque can be used as a primate model for studying hemophilia B gene therapy by transduction of macaque organs with vectors to express human FIX in vivoand detection of human FIX using the 3A6 monoclonal antibody.

This paper reports the catalytic pyrolysis of CBrClF2 over γ-Al2O3 and β-AlF3 in a plug-flow reactor operated at atmospheric pressure and within the temperature window of 523−673 K. The results indicate a very high conversion of halon 1211, in excess of 90% for γ-Al2O3 and 60−80% for β-AlF3, over the entire temperature range. Halon 1301 (CBrF3) and CFC 13 (CClF3) are the main pyrolysis products, although their yields vary with temperature and catalyst type. If accepted by regulators, this process offers a reaction pathway for converting stockpiled halon 1211 into more widely used halon 1301. A mechanistic interpretation of the results is proposed, including the reaction pathways and the transformations taking place in the catalysts. The mechanism involves the initial activation of the catalysts, which is reflected by the formation of the surface aluminum fluoride species identified by XRD analysis. This species then facilitates the halogen exchange between Br and Cl in CBrClF2 and F in the catalyst framework, leading to the formation of CBrF3 and CClF3. It is also proposed that two minor species (CBr2F2 and CCl2F2) are formed by dismutation of CBrClF2.

Congenital hypofibrinogenemia, fibrinogen Tottori II, caused by a nonsense mutation in the fibrinogen Bβ chain gene, was found in a 68-year-old Japanese female. The plasma fibrinogen level was 99.2 mg dL−1as determined by the thrombin time method. No overt molecular abnormalities were observed in purified patient fibrinogen by SDS–PAGE analysis. After sequencing all exons and exon–intron boundaries of three fibrinogen genes, we found a heterozygous single point mutation of T→G at position 3356 of the patient fibrinogen Bβ chain gene. This nucleotide mutation results in a nonsense mutation (TAT sequence for Bβ 41Tyr to TAG sequence for a translation termination signal). The mutation was confirmed by polymerase chain reaction-restriction fragment length polymorphism analysis, since this nucleotide mutation results in a new NheI recognition sequence at this position. These data indicated that the nonsense mutation of the fibrinogen Bβ chain gene caused a truncated fibrinogen Bβ chain, which may not be assembled in the fibrinogen molecule.

A novel polysilane having a tetraphenylporphyrin (TPP) side chain was synthesized. Intramolecular charge transfer between the σ-conjugated main chain and TPP side chain was investigated by the pulse radiolysis technique. The excess electrons are intramolecularly transferred to the TPP side chain with an apparent rate of electron transfer of >10⁸ s^-1, although a hole in the σ-conjugated main chain of the polysilanes is not transferred to the TPP side chain.

The intramolecular electronic excitation transfer in dithiaanthracenophane (DTA) in THF solution has been investigated by probing the fluorescence anisotropy decay with a femtosecond up-conversion method. In DTA, two anthracene rings are known to be stacked parallel, but with nearly orthogonal orientation. There appeared a damped oscillation of an apparent period of 1.2 ± 0.2 ps and a damping time constant of 1.0 ± 0.1 ps. It has been found that the oscillatory behavior is consistent with the recurrence motion of an excitation between two anthracene moieties, from a theoretical analysis following a manner of Wynne and Hochstrasser (Wynne, K.; Hochstrasser, R. M. J. Raman Spectrosc. 1995, 26, 561). The magnitude of the dipole−dipole energy transfer interaction is estimated to be 40 cm^-1 which is in an acceptable agreement with the experimental value (29 cm^-1) deduced from the oscillation period. In comparison with the similar case of 2,2‘-binaphthyl (BN) reported by Zhu et al. (Zhu, F.; Galli, C.; Hochstrasser, R. M. J. Chem. Phys. 1993, 98, 1042), the electronic dephasing time T2‘ is significantly longer in DTA (1.0 ps) than in BN (0.2 ps). The longer dephasing time in DTA can be explained as arising from a much more fixed and rigid dimeric conformation than in BN.

Cyclophane derivatives were irradiated with an ArF excimer laser in the gas phase. No triplet states, fluorescence, or cation radicals were observed in the transient spectra. The CH2−CH2 bonds dissociated, forming corresponding xylylenes by a two-photon process. The bond dissociations were explained in terms of a multiphoton reaction of hot molecules formed by an internal conversion. In addition, a slow rise of xylylene that originated in the single photon dissociation process of hot cyclophane was observed in the case of methyl-substituted paracyclophanes under low pressure conditions. The specific reaction rates of the dissociations of highly strained paracyclophanes were well explained by a statistical reaction theory, if a simple consideration of strain energy was made in the calculations.

A homologous series of zincporphyrin (ZnP)-pyromellitimide (Im)-C60 linked triads where the pyromellitimide (Im) moiety is incorporated as an intermediate acceptor between the above two chromophores with a linkage of different spacers, ZnP-Im-CH2-C60, ZnP-Im-C60, and ZnP-CH2-Im-C60 as well as the reference dyads (ZnP-Im-CH2-ref, ZnP-Im-ref, and ZnP-CH2-Im-ref) have been prepared to investigate linkage dependence of photoinduced electron transfer (ET) and back ET to the ground state in the triads. Time-resolved transient absorption spectra of the triads measured by picosecond laser photolysis as well as the fluorescence lifetimes in THF reveal the occurrence of photoinduced ET from the singlet excited state of the ZnP to the Im moiety to give the initial charge-separated state, i.e., the zincporphyrin radical cation (ZnP^•+)-imide radical anion (Im^•-) pair, followed by a charge shift (CSH) to produce the final charge-separated state, the ZnP^•+-C60^•- pair. The rate constants of photoinduced ETs in ZnP-Im-C60 (1.8 × 10¹⁰ s^-1) and ZnP-Im-CH2-C60 (1.3 × 10¹⁰ s^-1) in THF are much larger than those in ZnP-CH2-Im-C60 (2.9 × 10⁹ s^-1) and ZnP-CH2-Im-ref (1.9 × 10⁹ s^-1). The larger charge separation (CS) rates in the former case are ascribed to the relatively strong electronic coupling because of the absence of a methylene linkage between the ZnP and the Im moieties in ZnP-Im-C60 and ZnP-Im-CH2-C60 as compared to the triad and dyad with the methylene linkage. The transient absorption spectra of the final charge-separated state, the ZnP^•+-C60^•- pair, have been also measured by nanosecond laser photolysis. It has been found that the rate constants of charge recombination (CR) of ZnP^•+-Im-C60^•- are temperature independent, but that the CR rate constants of ZnP^•+-Im-CH2-C60^•- exhibit an Arrhenius-like temperature dependence with an activation energy of 0.13 eV which corresponds to the energy difference between ZnP^•+-Im^•--CH2-C60 and ZnP^•+-Im-CH2-C60^•-. This indicates that the relatively strong electronic coupling without methylene linkage in ZnP-Im-C60 results in the preference of the tunneling superexchange ET over the sequential ET in the CR process which requires the thermal activation to reach the higher energy state (i.e., ZnP^•+-Im^•--C60), whereas the sequential ET predominates in the triads with the methylene linkage.

AbstractBackground: Dehydration, starvation, and enhanced blood coagulability may occur during labor. Methods: We studied 60 women who gave birth vaginally to a healthy singleton infant at term. Sampling of urine and blood specimens was performed on admission to the hospital with labor pains and just after birth. Paired samples were available from 50 women for urine analysis and 29 women for blood analysis. Total fluid intake (oral and intravenous) during labor was recorded. Changes in various parameters in the urine and blood in relation to the total fluid intake were analyzed. Results: Osmolality and creatinine concentration in the urine, red blood cell count, hemoglobin concentration, hematocrit value, thrombinantithrombin III complex, plasmin-α2-plasmin inhibitor complex and D dimer significantly increased during labor. Ketone bodies were absent in the urine in 84% (42/50) of women on admission to the hospital whereas these were present in 74% (37/50) of women just after delivery (p < 0.01). The degree of these changes appeared to be smaller with an increase in fluid intake. Conclusion: Concentrated urine, hemoconcentration, starvation, and activation of the thrombogenic and fibrinolytic system occur in parturient women. Sufficient fluid intake during labor may ameliorate these unfavorable changes.

Both charge-transfer absorption and emission have been observed in porphyrin-linked fullerene where the C60 moiety is closely located on the porphyrin plane. Electron-transfer parameters including reorganization energies, free energy changes, and electronic coupling matrix elements were determined by analyzing the charge-transfer absorption and emission in benzene. The reorganization energy is estimated as 0.23 ± 0.11 eV, which is the smallest value among inter- and intramolecular donor−acceptor systems ever reported and is comparable to the smallest ones for the primary charge separation in the photosynthetic reaction center. The results clearly show that fullerenes combined with porphyrins are potential components for constructing artificial photosynthetic systems.

Photoinduced processes in zinc porphyrin−C60 dyad (ZnP−C60) in different organic solvents have been investigated by fluorescence lifetime measurements and pico- and nanosecond time-resolved transient absorption spectroscopies. Irrespective of the solvent polarity, the charge-separated state (ZnP^•+−C60^•-) is formed via photoinduced electron transfer from the excited singlet state of the porphyrin to the C60 moiety. However, the resulting charge-separated state decays to different energy states depending on the energy level of the charge-separated state relative to the singlet and triplet excited states of the C60 moiety. In nonpolar solvents such as benzene (εs = 2.28), the charge-separated state undergoes charge recombination to yield the C60 singlet excited state, followed by intersystem crossing to the C60 triplet excited state, since the energy level of the charge-separated state is higher than that of the C60 singlet excited state (1.75 eV). More polar solvents such as anisole (εs = 4.33) render the energy level of the charge-separated state lower than the C60 singlet excited state, resulting in the direct formation of the C60 triplet excited state (1.50 eV) from the charge-separated state, formed by the photoinduced charge separation from the porphyrin to the C60 singlet excited state as well as from the porphyrin excited singlet state to the C60. In polar solvents such as benzonitrile (εs = 25.2), where the energy level of the charge-separated state (1.38 eV) is low compared with the C60 triplet excited state, the charge-separated state, produced upon excitation of the both chromophores, decays directly to the ground state. Such solvent dependence of charge recombination processes in ZnP−C60 can be rationalized by small reorganization energies of porphyrins and fullerenes in electron-transfer processes.

The effect of a new quinolone antibacterial agent, grepafloxacin, on the production of cytokines was investigated using lipopolysaccharide-stimulated human peripheral blood cells. Grepafloxacin 1-30 mg/L inhibited the production of interleukin 1alpha (IL-1alpha) and IL-1beta, and the expression of IL-1alpha, IL-1beta, tumour necrosis factor alpha (TNFalpha), IL-6 and IL-8 mRNA. These results suggest that the inhibitory effect of grepafloxacin is exerted, in part, at the gene transcription level.

Self-assembled monolayers of ferrocene−porphyrin−C60 triads on gold electrodes were prepared to mimic photosynthetic electron transfer events where efficient conversion of light to chemical energy takes place via the long-lived, charge-separated state with a high quantum yield. Adsorbed amounts of the triads on the gold electrodes, estimated from the charge of the anodic peak of the ferrocene, are comparable to those of the well-ordered porphyrin−alkanethiols and C60−alkanethiols on gold electrodes. The results, together with blocking experiments using a redox probe, indicate that the triad molecules are well-packed with an almost perpendicular orientation on the gold surface. The monolayer thickness obtained using X-ray reflectivity analysis is consistent with the structural model of the monolayer. Photoelectrochemical studies were carried out in a standard three-electrode system using the gold electrodes modified with the self-assembled monolayers of the triads. Stable cathodic photocurrents were observed in the presence of electron carriers such as oxygen and/or methyl viologen in the electrolyte when the modified gold electrodes were illuminated with a monochromic light. A photoinduced multistep electron-transfer mechanism is proposed for the photoelectrochemical cells. Thus, vectorial electron transfer or partial charge transfer occurs from the excited singlet state of the porphyrin to the C60, followed by the successive charge shift from the ferrocene to the porphyrin cation radical, to produce the ferrocene cation radical and the C60 anion radical. The C60 anion radical gives an electron to the counter electrode via the electron carriers in the electrolyte solution, whereas electron transfer takes place from the gold electrode to the ferrocene cation radical, resulting in the recovery of the initial state and the generation of the overall electron flow. The artificial photosynthetic cells show the highest quantum efficiency (20−25%) ever reported for photoinduced multistep electron transfer at monolayer-modified metal electrodes and across artificial membranes using donor−acceptor linked molecules. The result indicates clearly that C60 acts as an excellent electron acceptor as well as an electron mediator in artificial photosynthetic membranes. The molecule-based methodology will provide a new direction for the development of solar energy conversion and molecular devices.

Disulfides, with a systematic series of alkyl spacers containing porphyrins at both terminals, were prepared to investigate the effect of the spacer length on the structure and photoelectrochemical properties of self-assembled monolayers (SAMs) of the porphyrins on a gold electrode. The structure of the SAMs was studied using ultraviolet (UV)−visible absorption spectroscopy in transmission mode, cyclic voltammetry, UV−visible ellipsometry, and fluorescence spectroscopy. These measurements showed that as the length of the spacers increases, the SAMs tend to form highly ordered structures on the gold electrodes. In addition, the structures of the monolayers vary depending on the even and odd number of the methylene spacers (n). From these measurements a porphyrin dimer model is proposed in that the two porphyrins take J-aggregate-like partially stacked structures in the monolayers. Photoelectrochemical studies were carried out in argon-saturated Na2SO4 aqueous solution containing methyl viologen as an electron carrier using the modified gold working electrode, a platinum wire counter electrode, and a Ag/AgCl reference electrode. The quantum yield increases in a zigzag fashion with an increase in the spacer length up to n = 6 and then starts decreasing slightly as the chain lengths become longer. A plausible explanation for the photocurrent trend comes from the following points:  (i) there are two competitive deactivation pathways for the excited singlet state of the porphyrin dimer, i.e., the quenching by the electrode via energy transfer and by the electron carrier via electron transfer, (ii) the porphyrin aggregation enhances the rate of nonradiative pathway in the excited state, and (iii) the electron transfer rate from the gold electrode to the resulting porphyrin cation radical decreases with an increase of the spacer lengths. These results will provide basic information for the construction of molecular assembly with photoactive function on surface.

Abstract: Anovelmethod for deriving the migration length (Lm) on a semiconductor surface is discussed. Lm is the most important parameter but it has not been precisely investigated for narrow-stripe selective-MOVPE. Lm can be deduced from the relationship between the (111) B-facet length and the (100)-facet length in the edge-growth region formed at the side of SiO2 masks. The two lengths have a linear relationship, so Lm on (100) surface can be obtained from an extrapolation of this relationship. This method was used to evaluate Lm for many kinds of the growth conditions. The maximum Lm and the precursors’ incorporation life-time were also deduced using the proposed method.