Interaction of hydrated metals with chemically modified hexagonal boron nitride quantum dots: wastewater treatment and water splitting.

The electronic and adsorption properties of chemically modified square hexagonal boron nitride quantum dots are investigated using density functional theory calculations. The free energy and frequency calculations show that all the boron nitride flakes are stable before/after modification and metal adsorption. Edge modification significantly enhances the stability and interactivity of the flake. For instance, the free energy of binding decreases from -6.5 eV in the hydrogenated flake to -7.1 eV in the pristine one and the dipole moment increases from 4.5 D to 53.7 D, respectively. A wide spectrum of band gaps can also be achieved, where the band gap can be smoothly varied from ∼6 eV in edge fluorinated flakes to 0.2 in sulfurated ones. Six hydrated metals, Cd, Co, Cr, Cu, Fe, and Zn, are considered for adsorption by the flakes. The transition metals are highly selected by the flakes while heavy metals are weakly adsorbed. All hydrated metals are physically adsorbed by the edge and surface of hydrogenated flakes except Cu, which is chemically adsorbed. Chemical groups or elements attached to the flake strongly enhance the adsorption strength; the adsorption energy of hydrated Cr on the surface increases from 0.6 eV to 8.6 eV after attaching two COOH groups to the surface. Hydrogen evolution has also been observed through the adsorption process. The calculated low overpotential for the oxygen evolution reaction (0.52 V) and hydrogen adsorption strength (0.11 eV) for the hydrogen evolution reaction indicate that boron nitride quantum dots are not only potential candidates for the removal of different metals from wastewater but also for efficient water splitting.

Slater Insulator in Iridate Perovskites with Strong Spin-Orbit Coupling.

The perovskite SrIrO_{3} is an exotic narrow-band metal owing to a confluence of the strengths of the spin-orbit coupling (SOC) and the electron-electron correlations. It has been proposed that topological and magnetic insulating phases can be achieved by tuning the SOC, Hubbard interactions, and/or lattice symmetry. Here, we report that the substitution of nonmagnetic, isovalent Sn^{4+} for Ir^{4+} in the SrIr_{1-x}Sn_{x}O_{3} perovskites synthesized under high pressure leads to a metal-insulator transition to an antiferromagnetic (AF) phase at T_{N}≥225 K. The continuous change of the cell volume as detected by x-ray diffraction and the λ-shape transition of the specific heat on cooling through T_{N} demonstrate that the metal-insulator transition is of second order. Neutron powder diffraction results indicate that the Sn substitution enlarges an octahedral-site distortion that reduces the SOC relative to the spin-spin exchange interaction and results in the type-G AF spin ordering below T_{N}. Measurement of high-temperature magnetic susceptibility shows the evolution of magnetic coupling in the paramagnetic phase typical of weak itinerant-electron magnetism in the Sn-substituted samples. A reduced structural symmetry in the magnetically ordered phase leads to an electron gap opening at the Brillouin zone boundary below T_{N} in the same way as proposed by Slater.

Long-range spin current driven by superconducting phase difference in a josephson junction with double layer ferromagnets.

We theoretically study spin current through ferromagnet (F) in a Josephson junction composed of s-wave superconductors and two layers of ferromagnets. Using quasiclassical theory, we show that the long-range spin current can be driven by the superconducting phase difference without a voltage drop. The origin of this spin current is due to spin-triplet Cooper pairs (STCs) formed by electrons of equal spin, which are induced by the proximity effect inside the F. We find that the spin current carried by the STCs exhibits long-range propagation in the F even where the Josephson charge current is practically zero. We also show that this spin current persists over a remarkably longer distance than the ordinary spin current carried by spin polarized conduction electrons in the F. Our results thus indicate the promising potential of Josephson junctions based on multilayer ferromagnets for spintronics applications with long-range propagating spin current.

Charge transfer in heterostructures of strongly correlated materials.

In this work, recent theoretical investigations by the authors in the area of oxide multilayers are briefly reviewed. The calculations were carried out using model Hamiltonians and a variety of non-perturbative techniques. Moreover, new results are also included here. They correspond to the generation of a metallic state by mixing insulators in a multilayer geometry, using the Hubbard and double-exchange models. For the latter, the resulting metallic state is also ferromagnetic. This illustrates how electron or hole doping via transfer of charge in multilayers can lead to the study of phase diagrams of transition metal oxides in the clean limit. Currently, these phase diagrams are much affected by the disordering standard chemical doping procedure, which introduces quenched disorder in the material.

Concomitant increases in serum growth hormone and hypothalamic somatostatin in rats after injection of gamma-aminobutyric acid, aminooxyacetic acid, or gamma-hydroxybutyric acid.

gamma-Aminobutyric acid (GABA; 50 or 500 microgram/10 microliter) was injected into the right lateral ventricle of urethane- or pentobarbital-anesthetized male rats. The animals were decapitated 15 min after injection. Serum GH and hypothalamic somatostatin (SRIF) concentration were measured by specific RIAs. Intraventricular GABA caused a dose-related increase in GH and SRIF. In another study, aminooxyacetic acid (5 or 20 mg) was injected ip into urethane-anesthetized rats. Aminooxyacetic acid at 20 mg produced a significant increase in both serum GH and hypothalamic SRIF. Furthermore, 12.5 mg gamma-hydroxybutyric acid (GHB) injected ip into urethane- or pentobarbital-anesthetized rats elicited a significant increase in both serum GH and hypothalamic SRIF. Pretreatment with 20 mg L-dopa produced decreases in the GHB-induced serum GH increase and in hypothalamic SRIF in pentobarbital-anesthetized rats. These results show that GABA and GHB stimulated GH secretion, which was accompanied by increased hypothalamic SRIF. Thus, the GH release induced by GABA or GHB may be partly involved in inhibiting the release of hypothalamic SRIF. As the GHB-induced GH release was inhibited by L-dopa, the stimulatory effect of GHB on GH secretion might be mediated by inhibition of the dopaminergic mechanism.

Anaphylactic shock after synthetic adrenocorticotropin-(1-18) in a patient with isolated adrenocorticotropin and beta-lipotropin deficiency.

A 58-yr-old woman had frequent hypoglycemic attacks, undetectable levels of plasma cortisol, ACTH, and beta-lipotropin, and deficient responses of these hormones after insulin induced-hypoglycemia and metyrapone. Her GH responses to arginine infusion were normal as were her gonadotropin responses to LRH. Her TSH and PRL responses to TRH were abnormally high. Anaphylactic shock occurred after the injection of either synthetic ACTH-Z-(1-24) (Cortrosin-Z) or ACTH-(1-18) (Acthormone). She had received two prior injections of synthetic ACTH-Z-(1-24) 2 months earlier. Circulating anti-ACTH antibody was found in her plasma by radioimmunological methods, but this antibody did not prevent corticosterone production by ACTH in an in vitro ACTH bioassay system. The pathogenic significance of this antibody in the ACTH deficiency is doubtful, and the etiology of the isolated ACTH and beta-LPH deficiency is not clear.

Stimulatory effects of gamma-hydroxybutyric acid on growth hormone and prolactin release in humans.

A dose of 2.5 g of gamma-hydroxybutyric acid (GHB) was administered intravenously to 6 healthy male volunteers. A significant increase in plasma GH was observed at 30, 45, 60 and 90 min after injection. The plasma prolactin level increased significantly at 45 and 60 min after GHB injection. These responses were not found after the saline vehicle injection in the same subjects. It is conceivable that GHB could modify the release of serotonin from the nerve terminals and then stimulate the release of GH and prolactin.

Ferromagnetic, A-type, and charge-ordered CE-type states in doped manganites using jahn-teller phonons

The two-orbital model for manganites with both noncooperative and cooperative Jahn-Teller phonons is studied at hole density x = 0.5 using Monte Carlo techniques. The phase diagram is obtained by varying the electron-phonon coupling and the t(2g)-spins exchange. The insulating CE-type charge- and orbital-ordered state with the z-axis charge stacking observed in narrow-bandwidth manganites is stabilized in the simulations. Its charge gap Delta(CO) is much larger than the critical temperature k(B)T(CO). Metalliclike A-type and ferromagnetic states are also obtained in the same framework, and the phase boundaries among them have first-order characteristics.

Magnetic domains and stripes in a spin-fermion model for cuprates

Monte Carlo simulations applied to a model of interacting fermions and classical spins show the existence of antiferromagnetic spin domains and charge stripes upon hole doping. The stripes have a filling of approximately 1/2 hole per site, and they separate spin domains with a pi phase shift among them. The observed stripes run either along the x or y axes. No particular boundary conditions or external fields are needed to stabilize these structures. When magnetic incommensurate peaks are observed at momentum pi(1,1-delta), charge incommensurate peaks appear at (0,2delta). The charge fluctuations responsible for the stripe formation also induce a pseudogap in the density of states.

Giant cluster coexistence in doped manganites and other compounds

Computational studies of models for manganese oxides show the generation of large coexisting metallic and insulating clusters with equal electronic density, in agreement with the recently discovered micrometer-sized inhomogeneities in manganites. The clusters are induced by disorder on exchange and hopping amplitudes near first-order transitions of the nondisordered strongly coupled system. The random-field Ising model illustrates the qualitative aspects of our results. Percolative characteristics are natural in this context. The conclusions are general and apply to a variety of compounds.

Dietary gamma-linolenic acid dose-dependently modifies fatty acid composition and immune parameters in rats.

gamma-linolenic acid (GLA) has been reported to improve several inflammatory disorders through regulation of eicosanoid production. However, since GLA is a precursor of arachidonic acid, it may bring about increasing tissue arachidonic acid levels with subsequent pro-inflammatory events. To explore this possibility, we examined the effect of high-dose GLA acid on the fatty acid profile of immune cells, leukotriene B4 production by peritoneal exudate cells and immunoglobulin productivity of mesenteric lymph node lymphocytes of Sprague-Dawley rats. Male rats were fed 10% fat diets containing graded levels, 0, 20, 40 and 60% of GLA for 3 weeks. The results showed the distinction in activity of metabolizing GLA between immune cells and liver. Thus, in immune cells such as mesenteric lymph node and spleen lymphocytes and peritoneal exudate cells, more dihomo-gamma-linolenic acid was found than in the liver. Leukotriene B4 production by peritoneal exudate cells was significantly suppressed when fed the highest level of GLA suggesting a lower risk of allergic reaction. Moreover, immunoglobulin productivity in mesenteric lymph node lymphocytes was promoted by dietary GLA. The present study indicates that a high dose of GLA may exert anti-inflammatory effects through suppression of leukotriene B4 release and strengthening of gut immune system, thus ameliorating allergic reaction.

Therapeutic effect of neuraminidase-treated LAK cells on liver metastasis of Colon 26.

To improve the lymphokine-activated killer (LAK) cell therapy for liver metastasis, two methods which enhance accumulation of LAK cells in the liver were examined for their effects on the liver metastasis of Colon 26 cancer cells in BALB/c mice. Distribution of LAK cells in the mice was examined by the 51Cr labeling method. Portal vein infusion of LAK cells or tail vein infusion of neuraminidase treated-LAK (N-LAK) cells showed an augmented accumulation of infused cells in the liver. In the first experiment, LAK cells (5 x 10(7) cells) were infused in the portal vein or tail vein at days 3 and 7 after the inoculation of 5 x 10(4) tumor cells and 1 x 10(4) units of IL-2 were given three times a day from day 3 to day 7. The portal infusion of LAK cells produced a greater reduction of liver metastases compared with the peripheral infusion. In the second experiment, 5 x 10(7) LAK cells or N-LAK cells were infused via the tail vein on days 1 and 3, and 1 x 10(4) units of IL-2 were given once a day from day 1 to day 5 after the inoculation of 1 x 10(4) tumor cells. The therapeutic effect of N-LAK cells was greater than non-treated LAK cells on the number of metastatic lesions and the survival time of mice. Since access to the human portal vein is difficult and risky in clinical situation, peripheral infusion of N-LAK cells is preferable.

Specificity of cultured anterior pituitary cells in detecting corticotropin releasing factor(s): the effect of biologically active peptides and neurotransmitter substances on ACTH release in pituitary cell cultures.

Biologically active peptides and neurotransmitter substances were added to anterior pituitary cell cultures to examine the presence of corticotropin releasing factor (CRF)-like activity. Hypothalamic extract (HE) induced significant dose-related increase of ACTH, and the lowest effective dose was 0.01 HE/ml. Other tested substances including luteinizing hormone-releasing hormone, thyrotropin releasing hormone, melanocyte stimulating hormone release inhibiting factor, somatostatin, substance P, neurotensin, beta-endorphin. leu-enkephalin, met-enkephalin, bradykinin, norepinephrine, dopamine, serotonin, acetylcholine, histamine, gamma-amino butyric acid or gamma-hydroxy butyric acid showed no CRF-like activity. Relatively high doses of lysine vasopressin, arginine vasopressin and angiotensin II increased the release of ACTH in pituitary cell cultures, but the maximal ACTH response was markedly less than with HE. These results indicate that cultured anterior pituitary cells are sensitive and fairly specific in detecting CRF(s) comparing with other detecting procedures.

Suppression of hepatic natural killer activity by liver metastasis of cancer and restoration of killer activity by oral administration of a Basidomycetes-derived polysaccharide, PSK.

PSK (Krestin) is a protein-bound polysaccharide with antitumor and immunomodulatory activity. In this study, the effects of the oral administration of PSK were investigated on the natural killer (NK) activity of liver-associated lymphocytes and their subfractions separated by density gradient centrifugation, in WKAH rats with liver metastasis of KDA hepatoma. PSK was administered orally, at a dose of 500 mg/kg once a day for 3 weeks. The NK activity of nonparenchymal liver cells (NPLC) and their subfractions, including large granular lymphocytes (LGL), was markedly augmented by this treatment. The effects of oral PSK were also examined in CDF1 mice with liver metastases of Colon 26 adenocarcinoma; the survival of tumor-bearing mice was prolonged and both metastatic foci and liver weight were decreased. These results suggest that PSK may be effective for the suppression of liver metastasis through activation of liver-associated NK cells.

A perifusion method for examining arginine vasopressin (AVP) release from hypothalamo-neurohypophyseal system.

A perifusion method has been developed using rat hypothalamo-neurohypophyseal system (HNS) or neural lobe to investigate the control mechanism of arginine vasopressin (AVP) release. A specific radioimmunoassay (RIA) for AVP was developed to measure AVP in perifusion medium employing anti-AVP serum which was obtained by immunizing rabbits. At a final dilution of 1/12,000, the antiserum showed less than 0.66 and 0.01% cross reactivity with lysine-vasopressin and oxytocin, respectively. But it did not cross reacted with other peptide hormones. The lowest detectable level of vasopressin was 0.5 pg/tube. The intra-assay coefficient of variation averaged 10.4%. The dilution curve of perifused medium was well paralled to the standard curve of AVP assay. AVP release from HNS or neural lobe gradually declined to the stable level in 90-120 min after the initiation of perifusion. Good repeatability of the AVP release from neural lobe was recognized by repeated stimulation with 10 min perifusion of 60 mM KCl at every 60 min. HNS released AVP in dose related manner to the osmotic challenge of sodium or glucose, and AVP release was stimulated from HNS by prostaglandin E2, but not by dopamine. These results show that the perifusion methods using AVP-RIA is a useful method to examine the AVP release from HNS or neural lobe.

Combined therapy with interleukin 2 and indomethacin in mice inoculated with MH134 hepatoma.

The antitumor effects of indomethacin and interleukin 2 (IL-2) were studied in C3H/HeJ mice inoculated with MH134 hepatoma cells. Combined treatment with indomethacin and IL-2 augmented natural killer (NK) cells in mice with MH134-induced peritoneal carcinomatosis, and the survival of the treated mice was significantly longer than the non-treated mice. In animals with subcutaneous MH134 tumors, the combined therapy with indomethacin and IL-2 significantly suppressed tumor growth and induced complete regression of the tumor in three out of five mice. These results suggest that indomethacin and IL-2 therapy could be effective on human gastrointestinal cancer cells as well.

[A case of pituitary hyperplasia associated with primary hypothyroidism].

A thirteen-year-old girl was admitted complaining of short stature and anemia. The low titers of her serum T3 and T4 and the abnormally high TSH level represented primary hypothyroidism. Although she had normal sellar size, CT demonstrated an intra- and suprasellar round mass with homogeneous enhancement. With thyroid replacement therapy the enhanced mass diminished on CT within 5 months, and her symptoms regressed. Twelve cases with radiological diminution of pituitary mass or visual field improvement after thyroid replacement therapy are reviewed. They were considered to be pituitary hyperplasia, rather than pituitary adenoma, caused by long-standing untreated hypothyroidism. In four of them, the pituitary mass on CT was diminished after the therapy. Characteristic CT findings of pituitary hyperplasia, including our case, was a round isodensity mass with homogeneous enhancement in the midline of the pituitary region. In the experimental studies, pituitary hyperplasia is based on the feedback mechanism of hypothalamic-pituitary-thyroid axis, and ultimately autonomous pituitary adenoma may occur. Pituitary mass with hypothyroidism, visual field defect, amenorrhea or galactorrhea tend to be mistaken for prolactinoma or non-functioning adenoma with pituitary hypothyroidism. Thorough endocrinological examination must be carried out. The first choice of treatment for this type of pituitary mass should be thyroid replacement therapy. If there is no improvement of visual field, no regression of pituitary mass on CT, or continuing high TSH levels, then pituitary surgery must be considered.

[Effect of UFT by oral administration using a murine hepatic metastasis model].

We examined the antitumor effect of UFT, a 5-FU derivative using a hepatic metastasis model in mice. BALB/c and CDF1 mice were given orally UFT (30 mg/kg, 50 mg/kg daily or 120 mg/kg every other day) for 20 days after inoculation of colon-26 tumor cells into the portal vein. The number of metastatic nodules and the weight of the liver decreased significantly in all groups of UFT treatment. The therapeutic effect with 50 mg/kg UFT was better than those with the other doses. NK and LAK activities of spleen cells obtained from UFT-treated tumor bearing mice were not significantly different from the untreated control. IL-1 and IL-2 production of the spleen cells were also not significantly changed by the treatment with UFT. These results suggested that the oral administration of UFT represents an antitumor effect against hepatic metastasis in mice without sever suppression of the host immune system.

[A case of Meckel's diverticulum with ulcer followed up by X-ray examination].

Meckel's diverticulum with ulcer was reported. A 76-year-old man visited our hospital with melena. X-ray examination of the small intestine by double contrast method demonstrated a diverticulum with ulcer of the ileum. This case was followed up by X-ray examination.

Anisotropic two-dimensional electron gas at the LaAlO3/SrTiO3 (110) interface.

The observation of a high-mobility two-dimensional electron gas between two insulating complex oxides, especially LaAlO3/SrTiO3, has enhanced the potential of oxides for electronics. The occurrence of this conductivity is believed to be driven by polarization discontinuity, leading to an electronic reconstruction. In this scenario, the crystal orientation has an important role and no conductivity would be expected, for example, for the interface between LaAlO3 and (110)-oriented SrTiO3, which should not have a polarization discontinuity. Here we report the observation of unexpected conductivity at the LaAlO3/SrTiO3 interface prepared on (110)-oriented SrTiO3, with a LaAlO3-layer thickness-dependent metal-insulator transition. Density functional theory calculation reveals that electronic reconstruction, and thus conductivity, is still possible at this (110) interface by considering the energetically favourable (110) interface structure, that is, buckled TiO2/LaO, in which the polarization discontinuity is still present. The conductivity was further found to be strongly anisotropic along the different crystallographic directions with potential for anisotropic superconductivity and magnetism, leading to possible new physics and applications.