Hybridization of Bogoliubov Quasiparticles between Adjacent CuO_{2} Layers in the Triple-Layer Cuprate Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{10+δ} Studied by Angle-Resolved Photoemission Spectroscopy.

Hybridization of Bogoliubov quasiparticles (BQPs) between the CuO_{2} layers in the triple-layer cuprate high-temperature superconductor Bi_{2}Sr_{2}Cu_{2}Cu_{3}O_{10+δ} is studied by angle-resolved photoemission spectroscopy (ARPES). In the superconducting state, an anticrossing gap opens between the outer- and inner-BQP bands, which we attribute primarily to interlayer single-particle hopping with possible contributions from interlayer Cooper pairing. We find that the d-wave superconducting gap of both BQP bands smoothly develops with momentum without an abrupt jump in contrast to a previous ARPES study. Hybridization between the BQPs also gradually increases in going from the off nodal to the antinodal region, which is explained by the momentum dependence of the interlayer single-particle hopping. As possible mechanisms for the enhancement of the superconducting transition temperature, the hybridization between the BQPs as well as the combination of phonon modes of the triple CuO_{2} layers and spin fluctuations represented by a four-well model are discussed.

Publisher Correction: A New Landscape of Multiple Dispersion Kinks in a High-Tc Cuprate Superconductor.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A New Landscape of Multiple Dispersion Kinks in a High-T c Cuprate Superconductor.

Conventional superconductivity is caused by electron-phonon coupling. The discovery of high-temperature superconductors raised the question of whether such strong electron-phonon coupling is realized in cuprates. Strong coupling with some collective excitation mode has been indicated by a dispersion "kink". However, there is intensive debate regarding whether the relevant coupling mode is a magnetic resonance mode or an oxygen buckling phonon mode. This ambiguity is a consequence of the energy of the main prominent kink. Here, we show a new landscape of dispersion kinks. We report that heavily overdoping a Bi2Sr2CaCu2O8+δ superconductor results in a decline of the conventional main kink and a rise of another sharp kink, along with substantial energy shifts of both. Notably, the latter kink can be ascribed only to an oxygen-breathing phonon. Hence, the multiple phonon branches provide a consistent account of our data set on the multiple kinks. Our results suggest that strong electron-phonon coupling and its dramatic change should be incorporated into or reconciled with scenarios for the evolution of high-T c superconductivity.

Anisotropy of the superconducting gap in the iron-based superconductor BaFe2(As(1-x)P(x))2.

We report peculiar momentum-dependent anisotropy in the superconducting gap observed by angle-resolved photoemission spectroscopy in BaFe2(As(1-x)P(x))2 (x = 0.30, Tc = 30 K). Strongly anisotropic gap has been found only in the electron Fermi surface while the gap on the entire hole Fermi surfaces are nearly isotropic. These results are inconsistent with horizontal nodes but are consistent with modified s ± gap with nodal loops. We have shown that the complicated gap modulation can be theoretically reproduced by considering both spin and orbital fluctuations.

Relation between the nodal and antinodal gap and critical temperature in superconducting Bi2212.

An energy gap is, in principle, a dominant parameter in superconductivity. However, this view has been challenged for the case of high-Tc cuprates, because anisotropic evolution of a d-wave-like superconducting gap with underdoping has been difficult to formulate along with a critical temperature Tc. Here we show that a nodal-gap energy 2ΔN closely follows 8.5 kBTc with underdoping and is also proportional to the product of an antinodal gap energy Δ(*) and a square-root superfluid density √Ps for Bi2Sr2CaCu2O8+δ, using low-energy synchrotron-radiation angle-resolved photoemission. The quantitative relations imply that the distinction between the nodal and antinodal gaps stems from the separation of the condensation and formation of electron pairs, and that the nodal-gap suppression represents the substantial phase incoherence inherent in a strong-coupling superconducting state. These simple gap-based formulae reasonably describe a crucial part of the unconventional mechanism governing Tc.

Enhanced superconducting gaps in the trilayer high-temperature Bi2Sr2Ca2Cu3O(10+δ) cuprate superconductor.

We report the first observation of the multilayer band splitting in the optimally doped trilayer cuprate Bi2Sr2Ca2Cu3O(10+δ) (Bi2223) by angle-resolved photoemission spectroscopy. The observed energy bands and Fermi surfaces are originated from the outer and inner CuO2 planes (OP and IP). The OP band is overdoped with a large d-wave gap around the node of Δ0∼43 meV while the IP is underdoped with an even large gap of Δ0∼60 meV. These energy gaps are much larger than those for the same doping level of the double-layer cuprates, which leads to the large Tc in Bi2223. We propose possible origins of the large superconducting gaps for the OP and IP: (1) minimal influence of out-of-plane disorder and a proximity effect and (2) interlayer tunneling of Cooper pairs between the OP and IP.

Energy-dependent enhancement of the electron-coupling spectrum of the underdoped Bi2Sr2CaCu2O(8+δ) superconductor.

We have determined the electron-coupling spectrum of superconducting Bi2Sr2CaCu2O(8+δ) from high-resolution angle-resolved photoemission spectra by two deconvolution-free robust methods. As hole concentration decreases, the coupling spectral weight at low energies ≲15 meV shows a twofold and nearly band-independent enhancement, while that around ∼65 meV increases moderately, and that in ≳130 meV decreases leading to a crossover of dominant coupling excitation between them. Our results suggest the competition among multiple screening effects, and provide important clues to the source of sufficiently strong low-energy coupling, λ(LE)≈1, in an underdoped system.

Isotopic fingerprint of electron-phonon coupling in high-Tc cuprates.

Angle-resolved photoemission spectroscopy with low-energy tunable photons along the nodal direction of oxygen isotope substituted Bi(2)Sr(2)CaCu(2)O(8+delta) reveals a distinct oxygen isotope shift near the electron-boson coupling "kink" in the electronic dispersion. The magnitude (a few meV) and direction of the kink shift are as expected due to the measured isotopic shift of phonon frequency, and are also in agreement with theoretical expectations. This demonstrates the participation of the phonons as dominant players, as well as pinpointing the most relevant of the phonon branches.

Direct observation of the mass renormalization in SrVO3 by angle resolved photoemission spectroscopy.

Band dispersions and Fermi surfaces of the three-dimensional Mott-Hubbard system SrVO3 are directly observed by angle-resolved photoemission spectroscopy. An observed spectral weight distribution near the Fermi level (E(F)) shows cylindrical Fermi surfaces as predicted by band-structure calculations. By comparing the experimental results with calculated surface electronic structures, we conclude that the obtained band dispersion reflects the bulk electronic structure. The enhanced effective electron mass obtained from the energy band near E(F) is consistent with the bulk thermodynamic properties and hence with the normal Fermi-liquid behavior of SrVO3.

[The Denial and Awareness Scale (DAS)].

Focusing on denial of drinking problems and raising awareness are two important treatment tasks at the initial stage of alcoholism treatment. However, an objective and clinically practical measure to assess patients' and family members' denial and awareness of alcohol-related problems has not yet been available. The DAS (Denial and Awareness Scale by Aro Ino and Shigeo Tatsuki) was developed in order to predict prognosis and evaluate treatment outcomes of alcoholism patients. The preliminary (DAS-1) patient scale was administered to 370 alcoholism patients. Their family members responded to the DAS-1 family member subscales. The abstinence period was then triangulated among the patient, a family member, and treatment staff members. For the purpose of the current study, 218 responses were used for item analyses and prediction of abstinence periods. Stepwise regression analyses of preliminary (DAS-1) sub-scales demonstrated that several sub-scales significantly predicted abstinence periods. After factor-analytic item re-classification of DAS-I items, DAS-2 was constructed. DAS-2 sub-scales were then regressed onto abstinence periods by a backward stepwise regression method. The analysis using the entire complete sample (N = 189) where both patients and their family members' responses were available demonstrated significantly that "Patient's Awareness" increased abstinence periods while "Family Troubled Feelings" decreased it, and that "Patient's Awareness" also galvanized "Changes in Patient's Mindset". Additional analyses were conducted in order to examine if predictive values of DAS-2 subscales differ according to varying stages of abstinence periods among the study subjects. The results showed that different sets of subscales predicted the abstinence periods depending on the treatment stages, i.e., abstinence within 1 year, 2 years, 3 years, and 4 years. These findings corresponded with the authors' clinical experiences. The current study produced several regression prediction equations utilizing the DAS-2. Further evaluation studies shall examine the effectiveness of the DAS-based prediction/prognosis of the abstinence period of alcoholism patients.

[Cooperative medical care by physicians of general hospitals and psychiatrists of an alcoholism treatment unit in Mie Prefecture].

Clinical practice of psychiatric liaison with physicians is the first step for an early treatment of alcohol dependence. Screening patients with alcohol dependence in general hospitals, carrying out intervention, and referring them to psychiatric specialists are running smoothly by the cooperation of member of the Mie Association for the Study of Alcohol-related Diseases. This association is being conducted by managers constituted of doctors, nurses, and medical social workers and the meeting is held every 6 months at district general hospitals to achieve three objectives; 1) evoking a sense of responsibility for alcoholic patients in the mind of general hospital staffs, 2) developing a network for psychiatric liaison with physicians to care patients of their alcohol dependence, and 3) keeping up activities of the association. We have already held the regular meeting 12 times, and prepared pamphlets for screening alcohol misuse and for early intervention. A course for learning skills of early intervention in this summer won the favor of participants. Through case conference of alcoholism and full accounts of the experiences given by recovered patients or their families, meeting attendants know patients' distress, families' sorrow, and their delight brought by the recovery, and are motivated to assist patients with alcohol dependence. Thus, "Spirit to Spirit" is a keyword to develop a network of the cooperative medical care for supporting patients with alcohol dependence. Referral of alcoholic patients to psychiatrists and/or psychiatric liaison therapy is promoted by a reliable, faithful, and face to face relationship between physicians and psychiatrists. Physicians' learning the skill for early intervention in alcohol dependence is followed by an increase in referral of patients to psychiatrists, and which suggests the importance of providing teaching and training of medical care for alcohol dependence to medical staffs including doctors of emergency care units, orthopedics, obstetrics, and dentistry. Therefore, systematic tools for screening alcohol dependence in general practice, and for referring patients to psychiatrics after brief intervention are needed to be prepared under the leadership of a learned society. Popularizing the skill of brief intervention in general medical practice is also indispensable for advising alcoholic patients about changing their drinking pattern or abstinence.

Angle-resolved photoemission study of insulating and metallic Cu-O chains in PrBa2Cu3O7 and PrBa2Cu4O8

We compare the angle-resolved photoemission spectra of the hole-doped Cu-O chains in PrBa2Cu3O7 (Pr123) and in PrBa2Cu4O8 (Pr124). While, in Pr123, a dispersive feature from the chain takes a band maximum at k(b) (momentum along the chain) approximately pi/4 and loses its spectral weight around the Fermi level, it reaches the Fermi level at k(b) approximately pi/4 in Pr124. Although the chains in Pr123 and Pr124 are approximately 1/4 filled, they show contrasting behaviors: While the chains in Pr123 have an instability to charge ordering, those in Pr124 avoid it and show an interesting spectral feature of a metallic coupled-chain system.

Preparation and antimicrobial activity of micacocidin.

Micacocidin (3), a Zn-free derivative of micacocidin A (1), was prepared to evaluate its antimicrobial activity in comparison with 1 and to obtain a starting material for chemical modification of 1. The structure of 3, quite unlike those of any previously known antimicrobial agents, was elucidated by 1-D and 2-D homonuclear and heteronuclear NMR and mass spectroscopy. Micacocidin (3) thus prepared exhibited weak or no antibacterial activity except against Mycoplasma species, i.e. 3 showed stronger activity than 1. It is noteworthy that 3 displayed high activity against fungi such as Candida, Aspergillus and Trichophyton species.

Before-discharge intervention method in the treatment of alcohol dependence.

BACKGROUND: Alcoholics have the fundamental problem of denying dependence on alcohol and minimizing their alcohol-related problems. Therapeutic interventions often fail to help alcoholics become aware of their drinking problem and remain in long-range treatment programs, which is a prerequisite for recovery from alcohol dependence. METHODS: Inpatients were assigned to either group 1 or 2 depending on which day of the week they were admitted to the hospital. A newly developed structured intervention method (Before-Discharge Intervention Method, or BDIM) was employed with select (nonrandomized) hospitalized alcoholics in group 1 and their family members before the patients were discharged from the hospital. None of the patients in group 2 received the BDIM. With this intervention method, the alcoholic's family members delivered to him or her verbal messages that conveyed concern about the alcoholic's problem drinking, their observations of the alcoholic's past episodes of drinking problems, and wishes and support for abstinence. Unless patients died during hospitalization or would not be able to attend the hospital follow-up clinic and local self-help groups (Danshukai) after discharge, outcome evaluations were carried out on all patients in groups 1 and 2 during two calendar months, 3 months after the last BDIM patient left the hospital. Outcome measures included patient's and family members' attendance at hospital outpatient follow-up sessions and self-help group meetings, and patient's abstinence. RESULTS: Family members' attendance at hospital follow-up sessions and/or self-help group meetings was significantly higher in group 1 than in group 2. Among the three subgroups of discharged patients in either group 1 or 2-that is, those who lived with their spouse, those who lived with someone other than their spouse, and those who lived alone-only those in group 1 who lived with their spouse did significantly better than their counterparts in group 2 in three treatment outcome measures. However, patients' maintenance of abstinence was significantly better only when they and their family members both attended hospital outpatient follow-up sessions and/or self-help group meetings. We noted no other statistically significant difference between groups 1 and 2 in any of the other two subgroups of discharged or patients in any of the three treatment outcome variables. Irrespective of the BDIM, patients who lived alone did significantly more poorly than either those who lived with their spouse or those who lived with someone other than their spouse in terms of attendance at hospital follow-up sessions and local self-help group meetings and abstinence. CONCLUSIONS: This intervention method can help the alcoholic face the reality of his or her drinking problems and alcohol dependence and thus remain longer in long-range rehabilitation programs, which is a prerequisite for successful recovery from alcohol dependence.

Evidences for adduct formation between intracellular non-protein thiols and nitroazoles possessing an alpha,beta-unsaturated carbonyl side chain and the effects on radiosensitization of hypoxic cells.

Reactivity of a number of nitroazole derivatives bearing an alpha,beta-unsaturated carbonyl group on the side chain toward non-protein thiols (NPSH) was examined both in the phosphate buffer solution and in the biological system. These alpha,beta-unsaturated compounds reacted with NPSH, such as glutathione (GSH) and L-cysteine (Cys), in the buffer solution to afford the 1,4-addition products. The reaction gave a second-order rate constant. The adducts of methyl 4-(2'-nitroimidazol-1'-yl)crotonate (1) with GSH and Cys were isolated and characterized as two diastereomers (7a,b and 8a,b) in ca. 1:1 ratio, respectively. Similarly, exposure of EMT6/KU cells to 1 at 1.0 mM for 1 h resulted in depletion of the intracellular NPSH by more than 80%. Over 50% of the depleted NPSH was attributed to the formation of the conjugated diastereomeric adducts. On the other hand, incubation of EMT6/KU cells with 1 at 1.0 mM under hypoxic conditions before X-ray irradiation caused concurrently a sharp reduction of the shoulder of the dose-survival curves (reduced the extrapolation number (n) from 8.0 to ca. 1.0) and an increase in the slope (decreased the mean lethal dose (Do) to ca. 50% of the control level). The observed effects of 1 on the dose-survival curves were due to the NPSH depletion through the Michael addition occurred in the cellular system. A fairly linear relationship was obtained between the n value and the reduced intracellular NPSH level. It indicated that the shoulder effect of the dose-survival curves of hypoxic cells should be the result of the NPSH depletion by the alpha,beta-unsaturated carbonyl group attached to the nitroazoles.

Functional polymorphism of -141C Ins/Del in the dopamine D2 receptor gene promoter and schizophrenia.

Several studies showed the density of D2 receptors was elevated in postmortem brains from schizophrenics. Genes which operate at the level of gene activation may be associated with the pathogenesis of schizophrenia. Arinami et al. [(1997) Human Molecular Genetics 6, 577-582] found a polymorphism in the 5'-flanking region of the D2 receptor gene designated as -141C Ins/Del. The promoter activity by luciferase assay of a plasmid containing the -141C Ins allele was higher than in the one containing the -141C Del allele. In addition, the -141C Ins allele frequency was significantly higher in schizophrenics than in control subjects. We replicated the -141C Ins/Del polymorphism in 170 schizophrenics and 121 healthy control subjects. The number of schizophrenics with the -141C Ins/Ins genotype was significantly higher than that of control subjects (P = 0.038). The frequency of the -141C Ins allele was significantly increased in the schizophrenics compared with the control subjects (P = 0.042). The mean age of onset for the patients with -141C Ins/Del was significantly lower than that for the patients with -141C Ins/Ins (P = 0.029). There was no association between the genotype and either positive symptoms or the response to antipsychotic medication. Our results suggest that the -141C Ins/Del polymorphism may affect the susceptibility to schizophrenia.

Analysis of the 5'-flanking promoter region of the 5-HT2A receptor gene in schizophrenia.

We studied the 5'-flanking promoter region comprising positions -1441 to +128 of the 5-HT2A receptor gene in 95 schizophrenics and 100 unrelated normal control subjects. The genes encoding the 5-HT2A receptor exons and the adjoining introl regions had already been studied in these subjects, but no disease specific polymorphism was found (Ishigaki et al., 1996). The DNA fragments were amplified by means of the polymerase chain reaction (PCR), and then analyzed by the single-stranded conformation polymorphism (SSCP) and sequencing methods. One patient had a substitution, from A to G, at position -668, and a 5 nucleotide deletion of TACTT at positions -646 to -642, however, the patient also had a normal sequence on the other allele. SSCP analysis showed that the other schizophrenics and the control subjects did not have any polymorphism in the 5'-flanking promoter region of the 5-HT2A receptor gene.

Three CAG trinucleotide repeats on chromosome 6 (D6S1014, D6S1015, and D6S1058) are not expanded in 30 families with schizophrenia.

Since 1991, more than five neuro-genetic disorders have been recognized to be caused by trinucleotide repeat expansions, and the list of such disease should grow. The diseases are characterized clinically by the phenomenon of anticipation, i.e., worsening of the disease phenotype in successive generations with increasing trinucleotide repeat expansion. The presence of anticipation in familial schizophrenia has been suggested. Several studies have provided supportive evidence that the suceptability locus for schizophrenia is on chromosome 6. Therefore, we analyzed three CAG trinucleotide repeat clones D6S1014, D6S1015, and D6S1058 on chromosome 6, which are polymolphic in 30 families with schizophrenia. No unusually, long alleles that would suggest abnormal expansion of more than 35 trinucleotide repeats were observed for these genes. Also, no statistically significant differences were found between the offspring and parental generations of affected subjects or between the affected and unaffected subjects in families with schizophrenia.