Pinning potential in highly performant CaKFe4As4 superconductor from DC magnetic relaxation and AC multi-frequency susceptibility studies

We have investigated the pinning potential of high-quality single crystals of superconducting material CaKFe4As4 having high critical current density and very high upper critical field using both magnetization relaxation measurements and frequency-dependent AC susceptibility. Preliminary studies of the superconducting transition and of the isothermal magnetization loops confirmed the high quality of the samples, while temperature dependence of the AC susceptibility in high magnetic fields show absolutely no dependence on the cooling conditions, hence, no magnetic history. From magnetization relaxation measurements were extracted the values of the normalized pinning potential U*, which reveals a clear crossover between elastic creep and plastic creep. The extremely high values of U*, up to 1200 K around the temperature of 20 K lead to a nearly zero value of the probability of thermally-activated flux jumps at temperatures of interest for high-field applications. The values of the creep exponents in the two creep regimes resulted from the analysis of the magnetization relaxation data are in complete agreement with theoretical models. Pinning potentials were also estimated, near the critical temperature, from AC susceptibility measurements, their values being close to those resulted (at the same temperature and DC field) from the magnetization relaxation data.

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.

In-plane and out-of-plane properties of a BaFe2As2 single crystal

Anisotropy of transport and magnetic properties of parent compounds of iron based superconductors is a key ingredient of superconductivity. In this work, we investigate in-plane and out-of-plane properties, namely thermal, electric, thermoelectric transport and magnetic susceptibility in a high quality BaFe₂As₂ single crystal of the 122 parent compound, using a combined experimental and theoretical approach. Combining the ab initio calculation of the band structure and the measured in-plane and out-of-plane resistivity, we evaluate the scattering rates which turn out to be strongly anisotropic and determined by spin excitations in the antiferromagnetic state. The observed anisotropy of thermal conductivity is discussed in terms of anisotropy of sound velocities which we estimate to be [Formula: see text]. Remarkably, we find that thermal conductivity is characterized by a sizeable electronic contribution at low temperature, which is ascribed to the high purity of our crystal.

A multi-throughput multi-organ-on-a-chip system on a plate formatted pneumatic pressure-driven medium circulation platform

This paper reports a multi-throughput multi-organ-on-a-chip system formed on a pneumatic pressure-driven medium circulation platform with a microplate-sized format as a novel type of microphysiological system. The pneumatic pressure-driven platform enabled parallelized multi-organ experiments (i.e. simultaneous operation of multiple multi-organ culture units) and pipette-friendly liquid handling for various conventional cell culture experiments, including cell seeding, medium change, live/dead staining, cell growth analysis, gene expression analysis of collected cells, and liquid chromatography-mass spectrometry analysis of chemical compounds in the culture medium. An eight-throughput two-organ system and a four-throughput four-organ system were constructed on a common platform, with different microfluidic plates. The two-organ system, composed of liver and cancer models, was used to demonstrate the effect of an anticancer prodrug, capecitabine (CAP), whose metabolite 5-fluorouracil (5-FU) after metabolism by HepaRG hepatic cells inhibited the proliferation of HCT-116 cancer cells. The four-organ system, composed of intestine, liver, cancer, and connective tissue models, was used to demonstrate evaluation of the effects of 5-FU and two prodrugs of 5-FU (CAP and tegafur) on multiple organ models, including cancer and connective tissue.

Reappraisal of the taxonomy of Streptococcus suis serotypes 20, 22 and 26: Streptococcus parasuis sp. nov

In order to clarify the taxonomic position of serotypes 20, 22 and 26 of Streptococcus suis , biochemical and molecular genetic studies were performed on isolates (SUT-7, SUT-286T, SUT-319, SUT-328 and SUT-380) reacted with specific antisera of serotypes 20, 22 or 26 from the saliva of healthy pigs as well as reference strains of serotypes 20, 22 and 26. Comparative recN gene sequencing showed high genetic relatedness among our isolates, but marked differences from the type strain S. suis NCTC 10234T, i.e. 74.8–75.7 % sequence similarity. The genomic relatedness between the isolates and other strains of species of the genus Streptococcus , including S. suis, was calculated using the average nucleotide identity values of whole genome sequences, which indicated that serotypes 20, 22 and 26 should be removed taxonomically from S. suis and treated as a novel genomic species. Comparative sequence analysis revealed 99.0–100 % sequence similarities for the 16S rRNA genes between the reference strains of serotypes 20, 22 and 26, and our isolates. Isolate STU-286T had relatively high 16S rRNA gene sequence similarity with S. suis NCTC 10234T (98.8 %). SUT-286T could be distinguished from S. suis and other closely related species of the genus Streptococcus using biochemical tests. Due to its phylogenetic and phenotypic similarities to S. suis we propose naming the novel species Streptococcus parasuis sp. nov., with SUT-286T ( = JCM 30273T = DSM 29126T) as the type strain.

Normal-state charge dynamics in doped BaFe₂As₂: roles of doping and necessary ingredients for superconductivity

In high-transition-temperature superconducting cuprates and iron arsenides, chemical doping plays an important role in inducing superconductivity. Whereas in the cuprate case, the dominant role of doping is to inject charge carriers, the role for the iron arsenides is complex owing to carrier multiplicity and the diversity of doping. Here, we present a comparative study of the in-plane resistivity and the optical spectrum of doped BaFe₂As₂, which allows for separation of coherent (itinerant) and incoherent (highly dissipative) charge dynamics. The coherence of the system is controlled by doping, and the doping evolution of the charge dynamics exhibits a distinct difference between electron and hole doping. It is found in common with any type of doping that superconductivity with high transition temperature emerges when the normal-state charge dynamics maintains incoherence and when the resistivity associated with the coherent channel exhibits dominant temperature-linear dependence.

Development of a high power supercontinuum source in the 1.7 μm wavelength region for highly penetrative ultrahigh-resolution optical coherence tomography

We developed a high power supercontinuum source at a center wavelength of 1.7 μm to demonstrate highly penetrative ultrahigh-resolution optical coherence tomography (UHR-OCT). A single-wall carbon nanotube dispersed in polyimide film was used as a transparent saturable absorber in the cavity configuration and a high-repetition-rate ultrashort-pulse fiber laser was realized. The developed SC source had an output power of 60 mW, a bandwidth of 242 nm full-width at half maximum, and a repetition rate of 110 MHz. The average power and repetition rate were approximately twice as large as those of our previous SC source [20]. Using the developed SC source, UHR-OCT imaging was demonstrated. A sensitivity of 105 dB and an axial resolution of 3.2 μm in biological tissue were achieved. We compared the UHR-OCT images of some biological tissue samples measured with the developed SC source, the previous one, and one operating in the 1.3 μm wavelength region. We confirmed that the developed SC source had improved sensitivity and penetration depth for low-water-absorption samples.

A 6-week oral gavage toxicity study of a novel galacto-oligosaccharide in juvenile rats

A novel galacto-oligosaccharide (GOS) was administered by gavage to groups (10 males and 10 females) of Sprague-Dawley specific pathogen-free rats for 6 weeks from day 4 after birth at doses of 0, 500, 1000, or 2000 mg/kg/day. Each pup was subjected to a variety of observations to examine for development effects/changes after birth: general condition, clinical signs, functional examinations, grip strength and spontaneous movement, body weight and feed consumption, external differentiation, ophthalmological examination, urinalysis (including water consumption), hematology, blood chemistry, necropsy, organ weight, and histopathology. During the study period, no deaths occurred in any group and there were no observed effects from administration of GOS. Therefore, it was concluded that GOS had no effects on the development of animals 4 days after birth. Since, there were no abnormalities due to administration of GOS in the macroscopic examination, organ weight or histopathology of the reproductive organs or differentiation (incisor eruption and eyelid opening) of males or females, it was concluded that repeated oral administration of GOS at 2000 mg/kg/day for 6 weeks from day 4 after birth hadno effects on postnatal development. The no observed effect level of GOS by repeated oral administration for 6 weeks from day 4 after birth was 2000 mg/kg/day for both males and females under the conditions of this study.

Evaluating the masticatory function after mandibulectomy with colour-changing chewing gum

The aim of this study was to clarify the usefulness of colour-changing gum in evaluating masticatory performance after mandibulectomy. Thirty-nine patients who underwent mandibulectomy between 1982 and 2010 at Kobe University Hospital were recruited in this study. There were 21 male and 18 female subjects with a mean age of 64·7 years (range: 12-89 years) at the time of surgery. The participants included six patients who underwent marginal mandibulectomy, 21 patients who underwent segmental mandibulectomy and 12 patients who underwent hemimandibulectomy. The masticatory function was evaluated using colour-changing chewing gum, gummy jelly and a modified Sato's questionnaire. In all cases, the data were obtained more than 3 months after completing the patient's final prosthesis. The colour-changing gum scores correlated with both the gummy jelly scores (r = 0·634, P < 0·001) and the total scores of the modified Sato's questionnaire (r = 0·537, P < 0·001). In conclusion, colour-changing gum is a useful item for evaluating masticatory performance after mandibulectomy.

Anisotropy of the in-plane resistivity of underdoped Ba(Fe(1-x)Co(x))2As2 superconductors induced by impurity scattering in the antiferromagnetic orthorhombic phase

We investigated the in-plane resistivity anisotropy for underdoped Ba(Fe(1-x)Co(x))(2)As(2) single crystals with improved quality. We demonstrate that the anisotropy in resistivity in the magnetostructural ordered phase arises from the anisotropy in the residual component which increases in proportion to the Co concentration x. This gives evidence that the anisotropy originates from the impurity scattering by Co atoms substituted for the Fe sites, rather than the so far proposed mechanisms such as the anisotropy of Fermi velocities of reconstructed Fermi surface pockets. As doping proceeds to the paramagnetic-tetragonal phase, a Co impurity transforms to a weak and isotropic scattering center.

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-T_c cuprates, because anisotropic evolution of a d-wave-like superconducting gap with underdoping has been difficult to formulate along with a critical temperature T_c. Here we show that a nodal-gap energy 2Δ_N closely follows 8.5 k_BT_c with underdoping and is also proportional to the product of an antinodal gap energy Δ^* and a square-root superfluid density √P_s for Bi₂Sr₂CaCu₂O_8+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 T_c.

In conventional superconductors, the critical temperature is proportional to the superconducting energy gap, but this is not so in unconventional superconductors. Anzai et al. identify an alternative relationship involving nodal and antinodal gaps in an underdoped cuprate superconductor.

Effect of Co doping on the in-plane anisotropy in the optical spectrum of underdoped Ba(Fe(1-x)Co(x))2As2

We investigate the anisotropy in the in-plane optical spectra of detwinned Ba(Fe(1-x)Co(x))(2)As(2). The optical conductivity spectrum of BaFe(2)As(2) shows appreciable anisotropy in the magnetostructural ordered phase, whereas the dc (ω = 0) resistivity is nearly isotropic at low temperatures. Upon Co doping, the resistivity becomes highly anisotropic, while the finite-energy intrinsic anisotropy is suppressed. It is found that anisotropy in resistivity arises from anisotropic impurity scattering due to the presence of doped Co atoms, and it is extrinsic in origin. The intensity of a specific optical phonon mode is also found to show striking anisotropy in the ordered phase. The anisotropy induced by the Co impurity and that observed in the optical phonon mode are hallmarks of the highly polarizable electronic state in the ordered phase.

Phase competition in trisected superconducting dome

A detailed phenomenology of low energy excitations is a crucial starting point for microscopic understanding of complex materials, such as the cuprate high-temperature superconductors. Because of its unique momentum-space discrimination, angle-resolved photoemission spectroscopy (ARPES) is ideally suited for this task in the cuprates, where emergent phases, particularly superconductivity and the pseudogap, have anisotropic gap structure in momentum space. We present a comprehensive doping- and temperature-dependence ARPES study of spectral gaps in Bi(2)Sr(2)CaCu(2)O(8+δ), covering much of the superconducting portion of the phase diagram. In the ground state, abrupt changes in near-nodal gap phenomenology give spectroscopic evidence for two potential quantum critical points, p = 0.19 for the pseudogap phase and p = 0.076 for another competing phase. Temperature dependence reveals that the pseudogap is not static below T(c) and exists p > 0.19 at higher temperatures. Our data imply a revised phase diagram that reconciles conflicting reports about the endpoint of the pseudogap in the literature, incorporates phase competition between the superconducting gap and pseudogap, and highlights distinct physics at the edge of the superconducting dome.

(Pro)renin receptor is associated with angiogenic activity in proliferative diabetic retinopathy

AIMS/HYPOTHESIS

The renin-angiotensin system (RAS) potentially has a role in the development of end-organ damage, and tissue RAS activation has been suggested as a risk factor for diabetic retinopathy. We have recently shown significant involvement of (pro)renin receptor ([P]RR) in retinal inflammation in a rodent model of early diabetes. In this study we aim to elucidate the (P)RR-associated pathogenesis of fibrovascular proliferation, a late-stage angiogenic complication in human diabetic retinopathy.

METHODS

Vitreous fluids from 23 eyes of patients with proliferative diabetic retinopathy (PDR) and 16 eyes of controls with non-diabetic, idiopathic macular diseases (macular hole and epiretinal membrane) were collected. Protein levels of soluble (P)RR were measured by ELISA, and immunofluorescence was performed to assess the localisation of (P)RR and related molecules in fibrovascular tissues from PDR eyes.

RESULTS

(P)RR immunoreactivity was detected in neovascular endothelial cells, colocalised with prorenin, phosphorylated extracellular signal-regulated kinase (ERK) and vascular endothelial growth factor (VEGF). Prorenin application to human retinal microvascular endothelial cells significantly upregulated mRNA expression of VEGF, especially the VEGF165 isoform, which was abolished by (P)RR or ERK signalling blockade. Proteases known to cleave (P)RR, including furin, were positive in endothelial cells in fibrovascular tissues. Protein levels of soluble (P)RR in vitreous fluids were higher in PDR eyes than in non-diabetic control eyes, and correlated significantly with vitreous prorenin and VEGF levels and the vascular density of fibrovascular tissues.

CONCLUSIONS/INTERPRETATION

Our data using human samples provide the first evidence that (P)RR is associated with angiogenic activity in PDR.

Evidence for the importance of extended Coulomb interactions and forward scattering in cuprate superconductors

The prevalent view of the high-temperature superconducting cuprates is that their essential low-energy physics is captured by local Coulomb interactions. However, this view been challenged recently by studies indicating the importance of longer-range components. Motivated by this, we demonstrate the importance of these components by examining the electron-phonon (e-ph) interaction with acoustic phonons in connection with the recently discovered renormalization in the near-nodal low-energy (~8-15 meV) dispersion of Bi(2)Sr(2)CaCu(2)O(8+δ). By studying its nontrivial momentum and doping dependence we conclude a predominance of forward scattering arising from the direct interplay between the e-ph and extended Coulomb interactions. Our results thus demonstrate how the low-energy renormalization can provide a pathway to new insights into how these interactions interplay with one another and influence pairing and dynamics in the cuprates.

Lateral Grain Growth in the Excimer Laser Crystallization of Poly-Si

We have succeeded in obtaining nondoped, thin poly-Si film (thickness ∼500Å) with excellent crystallinity and large grain size (Maximum grain size ∼4.5 μ m) by an excimer laser annealing Method, which offers the features of low-temperature processing and a short processing time. The grain size distribution shrinks in the region around 1.5 μ m and this poly-Si film exhibits a strong (111) crystallographic orientation. Poly-Si thin film transistors using these films show quite a high field effect mobility of 440cm2/V · s below 600°C process.

24 EFFECT OF CULTURE OF SEMEN IN A LOW PRESSURE CONDITION AT ROOM TEMPERATURE ON VIABILITY AND CAPACITATION STATUS OF BOAR SPERM

Sperm are affected by physical conditions, such as centrifugation and temperature. The objective of this study was to examine the effect of a low atmospheric pressure on viability and capacitation status of boar sperm during semen preservation at room temperature. Sperm-rich fraction from Berkshire boars was diluted at cells mL–1 with modified Modena containing 20% seminal fluid after washing with centrifugation (300 × g for 35 min at room temperature) in a Percoll gradient (45%/90%). The sperm suspension was stored at a pressure of 0.5 or 1.0 atmospheres in the dark at room temperature (25°C). Following storage for 4 h or 4 days, the semen samples were analysed for viability, intracellular calcium level, and acrosome status of the sperm. Viability and intracellular calcium level of sperm were assessed by flow cytometry following staining with SYBR-Green/PI and Furo-3/PL, respectively. Sperm status associated with capacitation and acrosome reaction was analysed by CTC-assay under fluorescence microscope. Statistical analyses of data from 4 or 5 replicated trials were carried out by ANOVA and with a Bonferroni-Dunn post hoc test (significance, P < 0.05). Viability of sperm was not different (P = 0.50) between 2 pressures (0.5 and 1.0 atm) 4 h and 4 days after the start of storage (94.6% v. 95.6% and 92.7% v. 94.3%, respectively). Although the percentage of live sperm with high intracellular calcium levels drastically increased (P < 0.01) 4 days after the start of storage (20.2% v. 23.4%) compared with 4 h of storage (5.5% v. 4.9%), there were no differences between sperm stored in 0.5 and 1.0 atm at 4 h (P = 0.80) and 4 days of storage (P = 0.40). After 4 h of storage, there were no differences in the percentage of intact (93.3% v. 94.7%), capacitated (5.5% v. 4.3%), and acrosome-reacted sperm (1.5% v. 1.5%) between sperm stored in 0.5 and 1.0 atm. After 4 days of storage, however, the percentage of intact sperm decreased when the sperm suspension was cultured in 0.5 atm (71.8%) compared with 1.0 atm (88.5%), and the incidence of capacitated sperm increased (14.3% v. 7.8%, respectively), whereas there was no difference in the acrosome-reacted cells. These results demonstrate that the status of sperm associated capacitation is stimulated in a low atmospheric pressure without any effects of the viability of sperm, during storage for 4 days.

Doping-dependent nodal fermi velocity of the high-temperature superconductor Bi2Sr2CaCu2O(8+δ) revealed using high-resolution angle-resolved photoemission spectroscopy

The improved resolution of laser-based angle-resolved photoemission spectroscopy (ARPES) allows reliable access to fine structures in the spectrum. We present a systematic, doping-dependent study of a recently discovered low-energy kink in the nodal dispersion of Bi2Sr2CaCu2O(8+δ) (Bi-2212), which demonstrates the ubiquity and robustness of this kink in underdoped Bi-2212. The renormalization of the nodal velocity due to this kink becomes stronger with underdoping, revealing that the nodal Fermi velocity is nonuniversal, in contrast with assumed phenomenology. This is used together with laser ARPES measurements of the gap velocity (v2) to resolve discrepancies with thermal conductivity measurements.

Neurodegenerative influence of oxidative stress in the retina of a murine model of diabetes

AIMS/HYPOTHESIS

Diabetic retinopathy is a progressive neurodegenerative disease, but the underlying mechanism is still obscure. Here, we focused on oxidative stress in the retina, and analysed its influence on retinal neurodegeneration, using an antioxidant, lutein.

METHODS

C57BL/6 mice with streptozotocin-induced diabetes were constantly fed either a lutein-supplemented diet or a control diet from the onset of diabetes, and their metabolic data were recorded. In 1-month-diabetic mice, reactive oxygen species (ROS) in the retina were measured using dihydroethidium and visual function was evaluated by electroretinograms. Levels of activated extracellular signal-regulated kinase (ERK), synaptophysin and brain-derived neurotrophic factor (BDNF) were also measured by immunoblotting in the retina of 1-month-diabetic mice. In the retinal sections of 4-month-diabetic mice, histological changes, cleaved caspase-3 and TUNEL staining were analysed.

RESULTS

Lutein did not affect the metabolic status of the diabetic mice, but it prevented ROS generation in the retina and the visual impairment induced by diabetes. ERK activation, the subsequent synaptophysin reduction, and the BDNF depletion in the diabetic retina were all prevented by lutein. Later, in 4-month-diabetic mice, a decrease in the thickness of the inner plexiform and nuclear layers, and ganglion cell number, together with increase in cleaved caspase-3- and TUNEL-positive cells, were avoided in the retina of lutein-fed mice.

CONCLUSIONS/INTERPRETATION

The results indicated that local oxidative stress that has a neurodegenerative influence in the diabetic retina is prevented by constant intake of a lutein-supplemented diet. The antioxidant, lutein may be a potential therapeutic approach to protect visual function in diabetes.

Spin-related current suppression in a semiconductor quantum dot spin-diode structure

We experimentally study the transport features of electrons in a spin-diode structure consisting of a single semiconductor quantum dot (QD) weakly coupled to one nonmagnetic and one ferromagnetic (FM) lead, in which the QD has an artificial atomic nature. A Coulomb stability diamond shows asymmetric features with respect to the polarity of the bias voltage. For the regime of two-electron tunneling, we find anomalous suppression of the current for both forward and reverse bias. We discuss possible mechanisms of the anomalous current suppression in terms of spin blockade via the QD-FM interface at the ground state of a two-electron QD.