Gap symmetry and intrinsic intraplane pinning of untwinned YBa2Cu3O7 single crystals

The interplane (cb) and intraplane (ab) anisotropy of untwinned YBa₂ Cu₃0₇ single crystals has been investigated by means of the torque magnetometry. To extract the reversible and irreversible components, the torque was measured as a function of increasing angle as well as decreasing angle. The interplane irreversible torque _irr shows two-fold peaks at _c =90 ° and270 ° (of half width11 ° at77 K) due to the well-known intrinsic interplane pinning. A novel intrinsic pinning has been discovered in the intraplane irreversible torque, i.e., _irr shows four-fold peaks of half width20° at77 K when _a =0 °, 90 °, 180 ° and270 °. We argue that the intrinsic intraplane pinning comes from the four-fold nature of the gap parameter.     

Active phase of calcium oxide used as solid base catalyst for transesterification of soybean oil with refluxing methanol

For developing a process of biodiesel production with environmental benignity, much interest has been focused on solid base catalysts such as calcium oxide for transesterification of vegetable oils with methanol. In this paper, the active phase of calcium oxide was investigated by characterizing the catalyst collected after achieving the conversion of edible soybean oil into its methyl ester at reflux of methanol in a glass batch reactor. Calcium oxide combined with the by-produced glycerol, so that calcium diglyceroxide was a major constituent of the collected catalyst. The absence of calcium methoxide was clear from the spectrum of solid-state ¹³C-NMR. The chemical change of calcium oxide was not observed, when the yield of FAME reached 30%. The collected catalyst was not as active as the fresh one (calcium oxide), but was reused without any deactivation. In order to identify the active phase of the collected catalyst, we prepared calcium diglyceroxide by immersion of calcium oxide with refluxing methanol in the presence of glycerol. Calcium diglyceroxide prepared as the reference sample was as active as the collected catalyst in the transesterification, and was tolerant to air-exposure.     

Does Vortex Lattice of YBa2Cu3O6.94 in H⊥c Melt Below Intrinsic-Pinning Irreversibility Line?

Vortex lattice melting in the Hc configuration of an YBa ₂ Cu ₃ O _6.94 single crystal has been investigated by means of the ac susceptibility – i and the magnetic torque . The melting transition of vortex lattice occurs in Hc, too. Since the torque curve shows a sharp peak in the irreversible torque at _c 90° due to intrinsic pinning at lower temperatures, we can determine the irreversibility line for the intrinsic pinning. The melting transition in the Hc configuration appears at temperatures where the intrinsic-pinning peak is absent. We consider that the intrinsic pinning does not affect the nature of the vortex melting transition in the Hc configuration.     

Superconducting MgB2 Thin Film Detector for Neutrons

The superconducting neutron detector using high-quality ¹⁰B-enriched MgB₂ thin films at higher operating temperatures has been proposed, where a resistance change induced by the nuclear reaction of neutron and ¹⁰B in MgB₂ is used to detect a neutron. Cold neutrons from a nuclear research reactor irradiated the MgB₂ detector, and the output voltage was clearly observed through a low-noise amplifier by using a digital oscilloscope. The out-of-equilibrium thermodynamics was investigated by means of the time-dependent Ginzburg-Landau equations by using the Earth Simulator.      

A 41-year-old woman with protein S deficiency and diffuse proliferative lupus nephritis: is protein S deficiency associated with a hyperinflammatory response?

A 41-year-old woman with complete protein S (PS) deficiency who developed diffuse proliferative lupus nephritis is reported. She was referred to our hospital with nephrotic syndrome and thrombocytopenia. Her medical history included colorectostomy and amputation of the extremities because of repeated thrombotic episodes during her teens without any evidence of systemic lupus erythematosus. The diagnosis of PS deficiency was made from the patient's clinical course, undetectable serum PS in either the active or inactive form, normal protein C activity, and no evidence of the antiphospholipid syndrome. However, there was no definitive family history. A depressed level of complements and a positive antinuclear acid antibody suggested a diagnosis of systemic lupus erythematosus. The patient had a rapidly progressive course and died of disseminated intravascular coagulation. An autopsy showed generalized thrombotic lesions and diffuse proliferative lupus nephritis on both ordinal light and immunoperoxidase microscopy. Our observations suggest that PS-deficient patients may have a hyperinflammatory response.     

Anisotropy in Superconductivity and Magnetism of PrFeAsO1−δ Single Crystal

The magnetic torque of a high-quality PrFeAsO_1?δ single crystal has been investigated at temperatures from 2 to 200 K in 1 and 5 T. The superconducting anisotropy in PrFeAsO_1?δ can well be approximated by the single-band Kogan torque theory. The superconducting anisotropy of PrFeAsO_1?δ determined by analyzing the torque curve is weakly dependent upon changing temperature. The magnetism contribution to the torque from magnetic Pr ions becomes appreciable compared to the superconducting component. We argue that the Pr ions in the superconducting PrFeAsO_1?δ single crystal show an antiferromagnetic spin ordering at 14 K. The spin structure thus reduced from the torque measurements is different from what neutron diffraction measurements predicted using polycrystalline specimen.     

Position Dependent Response of Superconducting MgB2 Neutron Detectors Studied by Pulsed Laser Irradiation

The MgB₂ detector consists of 200?nm thick MgB₂ thin film meander structure of 3?μm line width protected by 300?nm thick SiO layer. The electrical connections were provided by 150?nm thick Nb. The devices were placed in a 4?K refrigerator to investigate the behavior at temperatures below T _c. The position-dependent response of the MgB₂ detector can be investigated by scanning a laser spot with the aid of the XYZ piezo-driven stage and an optical fiber with a focusing lens. We found that the inhomogeneity in a detector is very critical to specify the detection efficiency since the detector has the sensitivity only in a narrow temperature regime near T _c.     

Calcium oxide as a solid base catalyst for transesterification of soybean oil and its application to biodiesel production

In order to study solid base catalyst for biodiesel production with environmental benignity, transesterification of edible soybean oil with refluxing methanol was carried out in the presence of calcium oxide (CaO), -hydroxide (Ca(OH)₂), or -carbonate (CaCO₃). At 1 h of reaction time, yield of FAME was 93% for CaO, 12% for Ca(OH)₂, and 0% for CaCO₃. Under the same reacting condition, sodium hydroxide with the homogeneous catalysis brought about the complete conversion into FAME. Also, CaO was used for the further tests transesterifying waste cooking oil (WCO) with acid value of 5.1 mg-KOH/g. The yield of FAME was above 99% at 2 h of reaction time, but a portion of catalyst changed into calcium soap by reacting with free fatty acids included in WCO at initial stage of the transesterification. Owing to the neutralizing reaction of the catalyst, concentration of calcium in FAME increased from 187 ppm to 3065 ppm. By processing WCO at reflux of methanol in the presence of cation-exchange resin, only the free fatty acids could be converted into FAME. The transesterification of the processed WCO with acid value of 0.3 mg-KOH/g resulted in the production of FAME including calcium of 565 ppm.     

Identification of kakusei,a Nuclear Non-Coding RNA,as an Immediate Early Gene from the Honeybee,and Its Application for Neuroethological Study

The honeybee is a social insect that exhibits various social behaviors. To elucidate the neural basis of honeybee behavior, we detected neural activity in freely-moving honeybee workers using an immediate early gene (IEG) that is expressed in a neural activity-dependent manner. In European honeybees (Apis mellifera), we identified a novel nuclear non-coding RNA, termed kakusei, as the first insect IEG, and revealed the neural activity pattern in foragers. In addition, we isolated a homologue of kakusei, termed Acks, from the Japanese honeybee (Apis cerana), and detected active neurons in workers fighting with the giant hornet.     

Evidence for vortex lattice melting and softening in untwinned YBa2Cu3O7 single crystal

Real part of the ac susceptibility X₁ of an untwinned YBa₂ Cu₃O₇ single crystal jumps at the onset temperature in the narrow width (0.1 K in 0.7 T), suggesting the first-order melting transition. A sharp X₁ dip and a sharp X peak can be interpreted as synchronous trapping of vortices due to lattice softening prior to melting. At lower temperatures, the X₁-X₁ chart shows a single-parameter behavior while the melting occurs as a strong deviation from this.