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Revisiting Wohler's method (1824), Cs-doped tungsten bronzes were synthesized by reducing Cs-polytungstate at high temperature, and were pulverized into nanoparticles for determining their optical properties. The high-temperature reduced Cs4W11O35 crystals absorbed strongly in the near-infrared, providing an improved luminous transparency with a less-bluish tint than normal Cs0.32WO3−y synthesized in a reductive atmosphere. The high-temperature reduction caused an orthorhombic-to-hexagonal phase transformation and a nonmetal–metal transition, which was monitored by spectrophotometry, X-ray diffraction, and X-ray photoelectron spectroscopy measurements, assisted by a first-principles analysis using a DFT+U method. The high-temperature reduction of Cs4W11O35 is concluded to decrease the number of W deficiencies and produce oxygen vacancies, releasing both free and trapped electrons into the conduction band and thereby activating the near-infrared absorption. The comparatively narrow bandgap of Cs4W11O35 was identified as the origin of the less-bluish tint of the produced Cs tungsten bronzes.

The origin of low conductivity and high near-infrared absorption observed in sputtered Cs-polytungstate (CPT) thin films was studied using x-ray photoelectron spectroscopy (XPS), thermal desorption spectroscopy (TDS), and first-principles calculations. The film's resistivity was directly correlated with the intensity of XPS W5+4f peaks, and the mobility of the conduction band (CB) electrons was evaluated as 1.27 × 10−7 cm2 V−1 s−1, both implying the dominance of W5+-trapped electrons in the CB. The presence of H2O residue in the films was detected from XPS O 1s and TDS spectra, suggesting that the incorporation of water upon film deposition induced numerous W/Cs defects reported in Part I. The two representative types of optical profiles were reproduced by first-principles calculations with W-deficient CPT and H2O-incorporated pyrochlore, respectively. We conclude that water-induced W/Cs defects annihilated free electrons in the films, causing loss of conductance and plasma reflection, whereas W5+-trapped electrons generated by O and W vacancies underwent polaronic excitations that generated large near-infrared absorption.

Sputtered thin films with strong near-infrared absorption and high visible transmission and electrical resistivity (≥102 Ω cm) have been obtained using highly conductive cesium tungsten bronze targets. The origin of the low electrical conductivity and high near-infrared absorption of the films has been investigated by focusing on internal defects and reported in two parts. In Paper I, the optical and electrical properties of the films and their microstructural characterization using x-ray diffraction and high-resolution transmission electron microscopy are presented. Abundant planar W and Cs defects were found on hexagonal prismatic planes that locally expanded the defect plane and triggered the hexagonal-to-orthorhombic crystallographic transition. These cationic defects diminished conduction electrons and suppressed electrical conduction, whereas oxygen vacancies generated W5+-trapped electrons to activate polaronic excitations for strong near-infrared absorption.

High transparency in the visible region is desired to manufacture solar control films and glasses for various applications. To improve the visible light transparency of LaB6 nanoparticles which exhibit strong absorption in the near-infrared region, the substitution of La with Ca is investigated using first-principles calculations. Among the numerous atomic replacement configurations in CaxLa1–xB6, all 762 structures existing in the supercells that are up to 8 times the primitive cell are comprehensively evaluated, and the most stable ground structures in CaxLa1–xB6 are deduced. The optical properties of the ground structures are derived by performing high-precision calculations using the HSE06 functional, which reveal that CaxLa1–xB6 with 0 < x < 1/4 is preferred as a solar shielding material with improved visible transparency. This method is effective for the investigation of the effect of substitutional elements in composite compounds on their physical properties.

Near-infrared (NIR) absorption in solar-control LaB6 nanoparticles (NPs) is derived from the localized surface plasmon resonance (LSPR) at 1.3 eV, and accompanies an unclarified subpeak at 1.8 eV. As an origin of this subpeak, a disk-like particle shape of LaB6 NP has recently been proposed, besides the previously-proposed, milling-derived LaO phase. A series of heating experiments at 200–850 °C in air for LaB6 NPs pulverized with different media beads have been made, followed by x-ray diffraction and transmission electron microscopy observations, to clarify that LaB6 NPs oxidizes to amorphous phases B2O3 and La–B–O at 450–600 °C, and crystallize to LaB3O6 at 650–750 °C, without forming LaO or La2O3. Dielectric functions of LaO have been derived by first-principles calculations using sX-LDA, and Mie scattering calculations have been made for various sizes, shapes, and the ensembles, showing that LaO NPs, if existed, should exhibit an excessively-broadened absorption band with a blunt LSPR peak at 2.1 eV buried in several interband-transition absorptions at 1.2–4.0 eV. These analyses confirm that the observed 1.8 eV subpeak could not originate from LaO and support the nonspherical shape of NPs as the origin of the subpeak.

Cesium-doped tungsten bronze, CsxWO3 (CWO), has the property of absorbing near-infrared (NIR) light and transmitting visible light and is used as an NIR shielding material for window glasses. However, the NIR shielding ability of CWO deteriorates with color bleaching in a high-temperature and high-humidity environment, thus limiting its applications. Decolorization is induced by the desorption of Cs in the presence of H2O. This reaction was investigated based on first-principles molecular dynamics calculations and the potential–pH diagram. The results clarified the mechanism of the Cs desorption reaction from a microscopic viewpoint. Furthermore, a countermeasure to suppress the Cs desorption, which employs the steric hindrance effect of cation substitutions with large ions on the surface, was proposed.

LaB6 nanoparticles are widely used as solar control materials for strong near-infrared absorption and high visible transparency. In order to elucidate the origin of this unique optical property, first-principles calculations have been made for the energy-band structure and dielectric functions of R(III)B6 (R(III) = Sc, Y, La, Ac). On account of the precise assessment of the energy eigenvalues of vacant states in conduction band by employing the screened exchange method, as well as to the incorporation of the Drude term, dielectric functions and various physical properties of LaB6 have been reproduced in excellent agreement with experimental values. Systematic examinations of dielectric functions and electronic structures of the trivalent metal hexaborides have clarified the origin of the visible transparency and the near-infrared plasmon absorption of R(III)B6 nanoparticles.

To elucidate the mechanism of low-energy optical properties of Cs-doped hexagonal tungsten bronzes (Cs-HTBs), energy band structures and dielectric functions were derived via first-principle calculation using the DFT + U method. The calculated dielectric functions agreed well with the experimental values, and the 1.6-eV peak in the imaginary part of the dielectric function appeared only when oxygen vacancies were introduced into a perfect crystal. With the introduction of oxygen vacancies, localized states were formed in the lower part of the conduction band. The near-infrared absorption of Cs-HTB thus comprised localized surface plasmon resonance due to free electrons supplied by Cs and polaron absorption due to localized electrons supplied by oxygen vacancies.

In Cs-doped hexagonal tungsten bronzes (Cs-HTBs), X-ray diffraction–Rietveld analysis has revealed that an increase in the alkali dopant and oxygen vacancies (VO) elongate the c-axis, contract the a-axis, and decrease the deviations of the W–O distance and W coordinates from those of a regular WO6 octahedron. These structural changes are interpreted as a destabilization of pseudo-Jahn–Teller (PJT) distortion by electron donation from Cs+ and VO. A dramatic difference is observed in the destabilization efficiency between the donated electrons from Cs+ and VO, suggesting that the former and latter electrons should be delocalized and localized, respectively. First-principles density functional theory calculations using optB86b-vdW functionals reproduced the behavior of c-axis elongation and a-axis contraction by Cs doping. The projected orbital density of states indicates that the Cs-derived electrons are donated to W-5dyz and W-5dzx orbitals to extend along the c-axis, whereas the VO-derived electrons are donated to W-5dxy and W-5dx2−y2 orbitals to strongly localize in the a–b plane. In HTBs, an anisotropic increase and decrease in the t2g* antibonding electrons from the doped alkali are concluded to induce the anisotropic structural change in PJT distortions.In Cs-doped hexagonal tungsten bronzes (Cs-HTBs), X-ray diffraction–Rietveld analysis has revealed that an increase in the alkali dopant and oxygen vacancies (VO) elongate the c-axis, contract the a-axis, and decrease the deviations of the W–O distance and W coordinates from those of a regular WO6 octahedron. These structural changes are interpreted as a destabilization of pseudo-Jahn–Teller (PJT) distortion by electron donation from Cs+ and VO. A dramatic difference is observed in the destabilization efficiency between the donated electrons from Cs+ and VO, suggesting that the former and latter electrons should be delocalized and localized, respectively. First-principles density functional theory calculations using optB86b-vdW functionals reproduced the behavior of c-axis elongation and a-axis contraction by Cs doping. The projected orbital density of states indicates that the Cs-derived electrons are donated to W-5dyz and W-5dzx orbitals to extend along the c-axis, whereas the VO-derived electrons are d...

Optical properties of lightly absorbing LaB6 nanoparticles (NPs) derived from mechanical pulverization have been studied using the effective medium theory (EMT). EMT calculations are found to agree with observed optical profiles remarkably if both Drude and bound-electron terms of dielectric functions are modified for NPs from bulk values. In LaB6 NPs, the imaginary part of dielectric functions increases and the energy of initial rise in joint density of states redshifts as compared to bulk values. Origin of these behaviors has been examined in terms of lattice defects, in addition to the conventional intrinsic size effects. Lattice defects in LaB6 NPs have been identified as modest lattice expansion using x-ray diffraction and transmission electron microscopy. The observed lattice expansion is found to decrease the band gap by decreasing the anti-bonding energy of La-5d/B-2p hybridized orbitals by first-principles calculations using sX-LDA. It is concluded that, unlike conventional belief, dielectric fun...

The incidence of Meniere's disease was investigated in patients with vertigo or dizziness who visited Kitasato University Hospital from 1985 to 1991. Of a total of 3, 222, Meniere's disease was diagnosed in 251 patients (7.8%). The male female ration was 1 : 1.73.Seventy patients with Meniere's disease were classified into 5 groups, depending on the duration of the disease. Both ears were affected in 12 (17.1 %) of the 70, but in 4 (33.3%) of the 12 patients with more than 15 years of disease.Of the 70 patients 67 were treated conservatively, and 3 surgically. The frequency of vertigo attacks and the degree of hearing impairment during the past year in each group were compared. No vertigo attack was experienced in 13 (24.1 %) of the 70. In 49 patients the average number of vertigo attack was 4.5 in the past year.Adequate therapy is most desirable within one year after the onset of Meniere's disease, because the frequency of vertigo attacks and the hearing level can be best controlled when therapy is started less than one year after the onset.

The origin of nystagmus, and the neurological symptoms and signs in 5 patients with Wallenberg's syndrome were related to the site and extension of lesions revealed by MRI. The relationship between nystagmus and a lesion in the neural structure, especially in the vestibular nucleus, was studied.1. Pure rotatory nystagmus was observed in 3 of the 5 patients, rotatory nystagmus with dissociated vertical movements like a see-saw in one, and no nystagmus in one.2. Nystagmus towards the side of the lesion was observed in one patient and nystagmus towards the contralateral side in 3.3. MRI did not reveal any lesions at the level of the lateral vestibular nucleus in any of the patients.4. Two patients, who had lesions in the medial and or inferior vestibular nucleus, did not complain of vertigo. On the contrary, 3, who had no lesions in the vestibular nuclei, complained of vertigo or dizziness. Therefore, it was supposed that a lesion adjacent to the vestibular nuclei associated with preservation of the vestibular nuclei might cause vertigo.5. Both skew deviation of the eyes and head tilt phenomenon were observed only in patients with no preservation of the medial and or inferior vestibular nucleus.6. Recording of eye movements with a CCD camera was very helpful in the analysis of nystagmus and in the follow-up studies of these patients.

We compared the effectiveness of 2 different therapies in elderly patients with benign paroxysmal positional vertigo.Eighteen patients were treated with an anti-vertigo drug and 18 with vestibular training (VT) and the same drug. They were classified into Group "B" and "VT + B", respectively.The background factors, such as age, severity in symptoms, degree of disturbance in examinations, et, were similar in the 2 groups.Vertigo, dizziness, unsteadiness in Mann's test and positional nystagmus improved significantly more in Group "VT+B" than in Group "B". The global judgment in each group revealed that both marked and moderate improvement was significantly higher in Group "VT+B" than in Group "B" (P

In order to evaluate the effectiveness of various therapies for vertigo at-tacks associated with tinnitus and hearing loss in Meniere's disease, the standard of both AAOO in 1972 and AAO-HNS in 1985 for the evaluation have been used in the United States and in Japan. The efficacy of treatment to prevent or decrease vertigo attacks and the duration of observation to evaluate it are the two main points discussed because the recurrence of attacks causes great suffering and it may make a hearing loss irreversible.There is often need to evaluate conservative treatment even soon after the start of therapy in order to judge whether the treatment is suitable for the patient. The modified evaluation method of AAO-HNS, which compares the mean numbers of attacks during the same intervals before and after the start of treatment is proposed in this study. This method can be useful both for short observation times less than 2.5 years and for long times of 3 or 5 years or more.

A case of cavernous hemangioma in the internal auditory canal was reported. The chronology of this case was similar as one of Ménière's disease. The neurotological findings in this case were no specific findings to differentiate cavernous hemangioma from acoustic neurinoma. The high-resolution computed tomography (HRCT) revealed calcium stippling in the lesions, whereas magnetic resonance imaging (MRI) demonstrated a low signal intensity on both T1- and T2-weighted images. Comparison of HRCT and MRI findings is most useful for differential diagnosis of intracanalicular tumors.

Positional nystagmus of the direction changing type, especially nystagmus towards the side of the upper ear in the lateral head position, is considered to appear in patients with disorders of the central nervous system. However, it might also occur in patients with peripheral vestibular disturbances.The pathogenesis of nystagmus directed towards the upper ear side remains obscure because controversial results have been reported in several papers.This paper discribes two patients with positional nystagmus directed towards the upper ear side, which was provoked after a short latency in both lateral head positions and disppeared within a few days. In both patients neurological and neurootological examinations indicated the presence of peripheral vestibular disorders.A fragment of statoconia adhering temporarily to the cupula of the lateral semicircular canal might be the cause of the nystagmus in our two patients.

Vestibular neuronitis is a peripheral vestibular disease of unknown etiology, in which severe vertigo attacks associated with disequilibrium usually start without any cochlear signs such as tinnitus or deafness after acute upper respiratory inflammation. It is generally accepted that the disease has a good prognosis beacause both subjective sensation and objective disequilibrium gradually improve and no recurrence of attacks is noticed.However, some patients complain of a transient dizzy sensation induced by quick body motion and disequilibrium during standing or walking, especially in darkness, a long time after the onset.Follow-up studies were carried out in six patients with vestibular neuronitis for 1 to 2 years after the beginning of the disease. Canal paresis was revealed by caloric tests in all six, it was bilateral in one. Five had transient diz-ziness and or unsteadiness during quick body movements 1 to 2 years after the onset of the disease. ENG studies revealed spontaneous nys-tagmus with eyes closed in two patients more than 2 years after the onset. The residual symptoms of dizziness and disequilibrium during body motion in vestibular neuronitis were assumed to be caused by prolonged failure in the acquisition of central vestibular compensation. Physical exercises were ordered in 2 patients, but complete recovery was not achieved.Disturvance of activities of daily living (ADL) are also discussed.

It seems acceptable that pathological brain stem lesions exist in the patient with Neuro-Behçet disease (NB). However, only few reports have been published in this field. We report the neuro-otological findings in 33 patients who fulfilled the diagnostic criteria of Behçet disease completely or incompletely. The patients were classified into 2 groups: one is group of NB and the other is a group of Behçet disease without NB (non-NB). Furthermore, the latter was divided into 2 subgroups of patients with dysequilibrium and patients with normal equilibrium. They underwent equilibrium function tests, such as body balance test, gaze test, spontaneous and positional nystagmus test, eye tracking test (ETT) and optokinetic pattern test (OKP) by using electro-nystagmography (ENG). The following results were obtained. 1. Cerebellar and brain stem lesions were confirmed in all cases of NB group. 2. Most cases (6 of 8 cases) in the subgroup of dysequilibrium of the non-NB group showed peripheral vestibular disturbance. The other two patients were diagnosed to be vertebro-basilar insufficiency (VBI) and vascular Behçet disease with CNS disorder, respectively. 3. Nine of 13 patients in the normal equilibrium subgroup of the non-NB group were diagnosed to be neuro-otologically normal. However, we found two patients with peripheral vestibular disturbance and CNS disorder associated with hearing disturbance of the retrocochlear origin, respectively. 4. The neuro-otological examination is assumed to be useful to diagnose neuro-Behçet disease, to reveal the lesion site and the state of dysequilibrium in patients with Behçet disease.

Opsoclonus was analyzed in two patients with acute encephalitis in the initial, extreme and recovery stages and the ENG and VTR findings were compared.In the initial stage ocular oscillation was mainly in the horizontal direction, with an amplitude of 5-30 degrees and a frequency of 7-8 Hz. It started suddenly several days after the patients developed fatigue and fever. A series of 1-10 beats of eye movements with some pause of various durations was repeated.Head rolling from side to side with a small amplitude was sometimes accompanied by eye oscillations. The patients had oscillopsia and an unsteady and staggering gait.The extreme stage started a few days after the initial stage. There was typical opsoclonus, consisting of multidirected but mainly vertical or diagonal oscillations of the eyes. The amplitude was large and reached 80 degrees. The frequency varied from 3-9 Hz. There were almost no pauses. The patients were unable to sit up, and their heads trembled in the same direction as the eye movements. Myoclonic jerks and ataxia of the trunk and extremities were maximum.In the recovery stage, the eye oscillations gradually decreased, and flutter-like oscillations (FLO) appeared. They were mainly horizontal, 5-20 degrees in amplitude, and their frequencies were 7-8 Hz. Pauses of various durations followed each series of 1-10 beats. The patients were able to stand and walk.Opsoclonus was triggered in all three stages by visual fixation, intention to move the eyes, mental excitation and sound stimulation.

Nystagmus towards the upper ear in both lateral head positions is usually considered to appear in patients with central nervous system lesions, especially those in the brain stem or cerebellar posterior vermis. However, its pathogenesis is still obscure, since several reports have suggested that such positional nystagmus may occur in patients with peripheral vestibular disturbances.This report describes a patient with positional nystagmus of this type after head trauma. X-ray examination revealed temporal bone fracture. The origin of positional nystagmus in this case was thought to be a peripheral vestibular lesion because the nystagmus was transient and there was no clinical evidence of any disturbance of the central nervous system. Seven cases of such positional nystagmus seen during the last 3 years in Kitasato University Hospital are summarized. Positional nystagmus towards the upper ear is assumed to be an important sign of central nervous system disturbance, but it may occur with peripheral vestibular lesions. It is necessary in the latter case for the positional nystagmus to disappear in the course of time, and other vestibular and neurological findings may indicate the character of the peripheral vestibular disturbance.

The incidence of Menière's disease was investigated in a total of 3222 patients with vertigo or dizziness who had visited Kitasato University Hospital during 1985-1991. Two hundred and fifty-one of the cases (7.8%) were found to suffer from Menière's disease and the male:female ratio was 1:1. Seventy cases of Menière's disease with complete records were classified into five groups, depending on the duration of the illness since its onset. Both ears were affected in 12 (17.1%) of the patients but in 4 (33.3%) of prolonged 12 patients having more than 15 years after the onset. All 70 patients had been treated conservatively, except for 3 who had undergone surgery. Frequency of vertiginous attacks and hearing impairment during the last year in each group were retrospectively compared with those of the other groups. No vertiginous attacks were experienced in 13 (24.1%) cases. The average number of vertigo attacks during the last year was 4.5 per year in 49 cases. Adequate therapy is desirable within one year after the onset of Menière's disease: the results showed the frequency of vertiginous attacks to be lowest and hearing levels to be best in the first group who were treated less than one year after the onset, in comparison with the other prolonged cases.