Haruo Saito

Bio: Haruo Saito is an academic researcher from University of Tokyo. The author has contributed to research in topics: Facial nerve & Endolymphatic hydrops. The author has an hindex of 13, co-authored 104 publications receiving 696 citations.

Antidiuretic hormone (ADH) and endolymphatic hydrops.

Abstract: Plasma antidiuretic hormone (p-ADH) concentrations were determined with a radioimmunoassay, using a reversed-phase C18 silica column, in 300 patients with vertigo, dizziness and/or deafness; 119 of them had a diagnosis of Meniere's disease. The p-ADH level was significantly elevated in patients with Meniere's disease and others with endolymphatic hydrops, e.g. cochlear Meniere's disease or delayed hydrops. By contrast, the p-ADH level was not so high in cases without the endolymphatic hydrops. The increase in the p-ADH level was closely linked to vertigo attacks, the glycerol test results and an enhanced negative summating potential (-SP) in electrocochleogram (ECochG). These results lead to the assumption that disorders of ADH-dependent hormonal control in the inner ear may constitute the possible mechanism underlying vertiginous attacks and deafness in patients with endolymphatic hydrops.

Pressure relationship between perilymph and endolymph associated with endolymphatic infusion

Abstract: The pressure difference between the perilymph and the endolymph following infusion of artificial endolymph into the endolymphatic space was studied in guinea pigs. Both the perilymphatic and the endolymphatic pressures were measured simultaneously with use of two sets of a servo-nulling system. Endolymphatic infusion caused pressure increases in both the endolymphatic and the perilymphatic spaces, but no measurable pressure difference between them. Soon after the endolymphatic infusion, both pressures returned nearly to the initial levels. We conclude that 1) the endolymphatic and the perilymphatic pressures are very closely related, and 2) if a physiologically significant pressure difference exists between endolymph and perilymph in endolymphatic hydrops, it is below the resolving power of the methods used in this study (+/- 0.1 mm Hg).

Poly[bis(phenethyl-ammonium) [di-bromido-plumbate(II)]-di-μ-bromido]].

Abstract: Crystals of the title compound, {(C6H5C2H4NH3)2[PbBr4]}n, were grown at room temperature from a solution in N,N-dimethyl­formamide (DMF) using nitro­methane as the poor solvent. This perovskite-type organic–inorganic hybrid compound consists of well ordered sheets of corner-sharing disordered PbBr6 octa­hedra separated by bilayers of phenethyl­ammonium cations. The octa­hedra are rotated and tilted due to N—H⋯Br hydrogen bonds with the ammonium groups, generating a superstructure in the unit cell similar to that of the tetra­chloridoplumbate (C6H5C2H4NH3)2[PbCl4].

Pressure relationship between perilymph and endolymph in guinea pigs

Abstract: The pressure difference between the perilymph and the endolymph was studied in guinea pigs, using two sets of a servo-nulling system. Asphyxia caused characteristic pressure changes both in the perilymph and in the endolymph, but no pressure difference was seen between them. When the perilymphatic space wag opened to the atmosphere, asphyxia did not cause such dynamic pressure changes either on the perilymph or the endolymph. An increase in the perilymphatic pressure induced by the infusion of artificial cerebrospinal fluid into the subarachnoid space resulted in an increase in the endolymphatic pressure, but no pressure difference between the endolymph and the perilymph was evident, regardless of the patency of the vestibular aqueduct. The authors conclude that the endolymphatic pressure is dependent on the perilymphatic pressure and there is no pressure difference between them.

Two-Dimensional Lead(II) Halide-Based Hybrid Perovskites Templated by Acene Alkylamines: Crystal Structures, Optical Properties, and Piezoelectricity.

Abstract: A series of two-dimensional (2D) hybrid organic–inorganic perovskite (HOIP) crystals, based on acene alkylamine cations (i.e., phenylmethylammonium (PMA), 2-phenylethylammonium (PEA), 1-(2-naphthyl)methanammonium (NMA), and 2-(2-naphthyl)ethanammonium (NEA)) and lead(II) halide (i.e., PbX42–, X = Cl, Br, and I) frameworks, and their corresponding thin films were fabricated and examined for structure–property relationship. Several new or redetermined crystal structures are reported, including those for (NEA)2PbI4, (NEA)2PbBr4, (NMA)2PbBr4, (PMA)2PbBr4, and (PEA)2PbI4. Non-centrosymmetric structures from among these 2D HOIPs were confirmed by piezoresponse force microscopy—especially noteworthy is the structure of (PMA)2PbBr4, which was previously reported as centrosymmetric. Examination of the impact of organic cation and inorganic layer choice on the exciton absorption/emission properties, among the set of compounds considered, reveals that perovskite layer distortion (i.e., Pb–I–Pb bond angle between adj...

The 2D Halide Perovskite Rulebook: How the Spacer Influences Everything from the Structure to Optoelectronic Device Efficiency.

Abstract: Two-dimensional (2D) halide perovskites have emerged as outstanding semiconducting materials thanks to their superior stability and structural diversity. However, the ever-growing field of optoelectronic device research using 2D perovskites requires systematic understanding of the effects of the spacer on the structure, properties, and device performance. So far, many studies are based on trial-and-error tests of random spacers with limited ability to predict the resulting structure of these synthetic experiments, hindering the discovery of novel 2D materials to be incorporated into high-performance devices. In this review, we provide guidelines on successfully choosing spacers and incorporating them into crystalline materials and optoelectronic devices. We first provide a summary of various synthetic methods to act as a tutorial for groups interested in pursuing synthesis of novel 2D perovskites. Second, we provide our insights on what kind of spacer cations can stabilize 2D perovskites followed by an extensive review of the spacer cations, which have been shown to stabilize 2D perovskites with an emphasis on the effects of the spacer on the structure and optical properties. Next, we provide a similar explanation for the methods used to fabricate films and their desired properties. Like the synthesis section, we will then focus on various spacers that have been used in devices and how they influence the film structure and device performance. With a comprehensive understanding of these effects, a rational selection of novel spacers can be made, accelerating this already exciting field.

Structural origins of broadband emission from layered Pb–Br hybrid perovskites

Abstract: Through structural and optical studies of a series of two-dimensional hybrid perovskites, we show that broadband emission upon near-ultraviolet excitation is common to (001) lead-bromide perovskites. Importantly, we find that the relative intensity of the broad emission correlates with increasing out-of-plane distortion of the Pb–(μ-Br)–Pb angle in the inorganic sheets. Temperature- and power-dependent photoluminescence data obtained on a representative (001) perovskite support an intrinsic origin to the broad emission from the bulk material, where photogenerated carriers cause excited-state lattice distortions mediated through electron–lattice coupling. In contrast, most inorganic phosphors contain extrinsic emissive dopants or emissive surface sites. The design rules established here could allow us to systematically optimize white-light emission from layered hybrid perovskites by fine-tuning the bulk crystal structure.