To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
We report the investigation on the properties of a novel Te precursor (i-C3H7)2Te and its effectiveness in fabricating MoTe2. The vapor pressure of the precursor was obtained by measuring the pressure as a function of its temperature in a sealed chamber. As a result it showed a high vapor pressure of 552.1 Pa at room temperature. The decomposition of the precursor was also investigated using DFT calculation. It was shown that the most likely reaction during the course of the decomposition of (i-C3H7)2Te is (i-C3H7)2Te → H2Te + 2 C3H7. The effectiveness of the precursor on the fabrication of MoTe2 was also investigated. Sputter-deposited MoO3 was tellurized in a quartz-tube furnace at the temperature up to 440°C. The resulting film showed that the 80% of the original MoO3 was tellurized to form MoTe2. It was also shown that further optimization of tellurization is required in order to prevent formation of metal Mo and elemental Te.
We report the synthesis of MoS2(1-x)Te2x by co-sputtering deposition and effect of mixture on its bandgap. The deposition was carried out at room temperature, and the sputtering power on individual MoS2 and MoTe2 targets were varied to obtain films with different compositions. Investigation with X-ray photoelectron spectroscopy confirmed the formation of Mo-Te and Mo-S bonds after post-deposition annealing (PDA), and one of the samples exhibited composition ratio of Mo:S:Te = 1:1.2:0.8 and 1:1.9:0.1 achieving 1:2 ratio of metal to chalcogen. Bandgap of MoS1.2Te0.8 and MoS1.9Te0.1 was evaluated with Tauc plot analysis from the extinction coefficient obtained by spectroscopic ellipsometry measurements. The obtained bandgaps were 1.0 eV and 1.3 eV. The resulting bandgap was lower than that of bulk MoS2 and higher than that of bulk MoTe2 suggesting mixture of both materials was achieved by co-sputtering.
Molybdenum disulfide (MoS2) thin films were fabricated by two-step chemical vapor deposition (CVD) using (t-C4H9)2S2 and the effects of temperature, gas flow rate, and atmosphere on the formation were investigated in order to achieve high-speed low-temperature MoS2 film formation. From the results of X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) investigations, it was confirmed that c-axis orientation of the pre-deposited Mo film has a significant involvement in the crystal orientation after the reaction low temperature sulfurization annealing and we successfully obtained 3 nm c-axis oriented MoS2 thin film. From the S/Mo ratios in the films, it was revealed that the sulfurization reaction proceeds faster with increase in the sulfurization temperature and the gas flow rate. Moreover, the sulfurization under the H2 atmosphere promotes decomposition reaction of (t-C4H9)2S2, which were confirmed by XPS and density functional theory (DFT) simulation.
To investigate the characteristic physical properties of the oscillating system in the intact middle ear using a high-speed camera.
We analysed the oscillation of the guinea pig stapes using a high-speed camera. The specimens were prepared so that the middle-ear structures were intact. Tones of various frequencies were delivered into the external auditory canal.
We found that the stapes showed a damped oscillation after the sound stimulation had stopped. The damped oscillation after the sound stimulation showed a specimen-specific frequency that was independent of the frequency of the stimulating sound. An injury to the bony labyrinth, which removed most of the mass from the oscillating system, attenuated the damped oscillation. Therefore, this damped oscillation is likely a passive motion, rather than a reverberation of the stimulating sound.
Analysing the passive damped oscillation may reveal the characteristic physical properties of the oscillating system in the near-intact middle ear. Further refinement of this simple and straightforward system may enhance basic and clinical research on the middle ear in a more intuitive way.
We investigated the ossicular movement in the near-intact middle ear in response to acoustic stimulation using a high-speed video camera and video analysis software program.
We have designed a good visual access to the middle ear of the guinea pig by opening the ventral wall of the otic capsule, without injuring the sound-conducting structures, from the external auditory canal to the oval window. The high-speed video camera could record analysable ossicular motion up to 4000 frames per second.
The stapes showed reciprocal movement in the same frequency as the stimulating tone, and with an amplitude proportional to the stimulating sound intensity. Injury to the tympanic membrane attenuated the stapedial motion, which was recovered to that of the control level by patch repair of the perforation.
Our experimental set-up was capable of evaluating the conductive hearing, regardless of the status of the animal's sensorineural hearing or even life. Such a video analysis may provide a powerful tool to investigate the physiology of the middle ear.
Molybdenum disulfide (MoS2), one of the transition-metal dichalcogenides, is a 2-dimensional semiconducting material that has a layered structure. Owing to excellent optical and electronic properties, the ultra-thin MoS2 film is expected to be used for various devices, such as transistors and flexible displays. In this study, we investigated the physical and chemical properties of sputtered-MoS2 film in the sub-10-nm region by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). As the results of Raman spectroscopy investigations, we observed two Raman modes, E12g and A1g, in the 2-dimensional MoS2 films. As the thickness of the MoS2 film decreased, the peak frequency difference between E12g and A1g modes increased. From the XPS investigations, we confirmed sulfur reductions from the 2-dimensional MoS2 films. Therefore, we considered that the sulfur vacancies in the MoS2 film affected the Raman peak positions. Moreover, we performed the additional sulfurization of sputtered-MoS2 films. From the XPS and Raman investigations, the quality of the sputtered-MoS2 films was improved by the additional sulfurization.
Single-crystalline organic solar cells were investigated. Rubrene single crystals made by train sublimation method were used for the active layer of the solar cells. Typical solar cell characteristics and external quantum efficiency (EQE) were observed with the film thickness of several micrometers. In spite of their large film thickness, the EQE spectra showed no screening effect, which means that absorbed photons efficiently converted to electric charges. This can be attributed to the extended exciton diffusion due to uniform and trap free characteristic of rubrene single crystal.
In this study, ZnO f ilms heavily doped with Al or Ga were grown on a polarity-controlled buffer layer using pulsed laser deposition. The films prepared using a 1 mol% Al-doped target with the buffer layer grown at 700 °C had the c(+)-face, whereas the films with the buffer layer grown at 400 °C had the c(-)-face, which means that the polarity control can be successfully carried out using the buffer layer. However, the films prepared using targets doped with more than 1 mol% Al or Ga had the c(+)-face regardless of the polarity of the buffer layer. The 1 mol% Al-doped ZnO film with the c(+)-face had lower electron concentration and higher growth rate than the film with the c(-)-face. This result indicates that the Al content in the film with the c(-)-face was larger than that in the film with the c(+)-face.
The metal abundances in the hot X-ray emitting interstellar medium (ISM) of early-type galaxies give us important information about the present metal supply into the ISM through supernovae (SNe) Ia and stellar mass loss. In addition, O and Mg abundances should reflect the stellar metallicity and enable us to directly look into the formation history of these galaxies. The XIS instrument onboard the Suzaku satellite has an improved line spread function due to a very small low-pulse-height tail below 1 keV coupled with a very low background.
The crystal structure of a clinopyroxene with composition (Na0.75Ca0.25)(Cr0.75Mg0.25)Si2O6 was refined at 100, 150, 200, 250 and 298 K. The work was performed in the context of an investigation on the low-temperature behaviour of A+M3+Si2O6 (with A dominant in Na and M = transition elements) pyroxenes in order to provide new insights concerning the phase transition and anomalies recently found in the low-temperature behaviour of NaTiSi2O6 and NaGaSi2O6 compounds. The refinements were done in the C2/c space group (wR2 between 0.048 and 0.068), and no change of symmetry was observed down to 100 K. Highly-anisotropic axial thermal expansion occurs with the scheme αb ≥ αb > αc.
The M2, M1 and T polyhedra expand with αM2 > αM1 αT as generally observed in pyroxenes. A discontinuity in the M1 polyhedral volume is observed between 200 and 250 K, similar to the one observed in NaGaSi2O6 between 190 and 235 K.
The atomic displacement parameters are scaled according to the following pattern: UM2 > UO2 > UO3 ≥ U01 > UT ≥ UM1 Comparison with previous data along the CaMgSi2O-NaCrSi2O6 join suggests significant positional disorder for the O1 oxygen, due to repulsion of the 2p orbitals of O1 and the non-bondine 3d electrons of Cr.
We used a surface-plasmon antenna to obtain small photodetectors for LSI on-chip optical interconnection by using near-field light generated by the antenna. Such near-field devices are not constrained by the diffraction limit and they offer an approach to integrated nanoscale photonic devices. A small semiconductor structure is located near the antenna to absorb the near-field light. This structure can be made as small as the Schottky depletion layer, so the separation between electrodes can be reduced to almost the size of the near-field region. We have demonstrated a “Si nano-photodiode” or plasmon photodiode that uses the near-field localized in a subwavelength region, which is usually relatively large in size because of the long absorption length for Si (˜10 μm at a wavelength of ˜800 nm). The Si nano-photodiode has a fast impulse response with a full-width at half-maximum of ˜20 ps even when the bias voltage is small (˜1 V or less). We demonstrated an on-chip optical interconnect chip to operate circuitry in an LSI chip by using waveguide-coupled Si nano-photodiodes.
This study investigated a new effective method for controlling the capsalid monogenean Neobenedenia girellae. We examined in vitro and in vivo the effect on the percentage survival of N. girellae in buffers containing different metallic ions. Decreased survival was observed in buffer solutions lacking two ions. In particular, the percentage survival of N. girellae was significantly decreased after 10 min exposure to buffer containing neither Ca2+ nor Mg2+. Transmission electron microscopic observations showed that treatment with this buffer disrupted intercellular junctions. This significant effect on percentage survival of N. girellae using Ca2+/Mg2+-free buffer was confirmed in an in vivo assay. Ca2+/Mg2+-free buffer had no effect on the condition of the host, spotted halibut Verasper variegates (Pleuronectidae). These results suggest that treatment with Ca2+/Mg2+-free buffer is a new effective control method, which could replace existing control methods.
An expedition across the Asian part of the Black Sea coast and national parks of Northern Turkey was organized in the summer of 2001 to investigate the presence of Borrelia burgdorferi sensu lato (s.l.), Lyme borreliosis agent, and Anaplasma phagocytophilum, human granulocytic ehrlichiosis agent, in wild mice. A total of 65 Apodemus flavicollis, Apodemus sylvaticus, Microtus epiroticus, Crocidura suaveolens and Mus macedonicus, were captured. Two out of 22 Apodemus sylvaticus specimens were seropositive for B. afzelii by enzyme-linked immunosorbent assay as confirmed by Western blotting, however cultures of skin and bladder samples from all small mammals in Barbour–Stoenner–Kelly's medium-II remained negative for B. burgdorferi s.l. All sera tested were negative for Anaplasma phagocytophilum by indirect immunofluorescent assay. The prevalence of B. burgdorferi s.l. and Anaplasma phagocytophilum is low in wild mice of the Asian part of Northern Turkey.
In case-control studies of complex disease genes, allele frequencies or allele positivities at candidate
loci or markers are compared between cases and controls. Although 2 × 2 contingency tables based
on allele frequency and allele positivity are generally used to perform simple statistical tests (e.g. a
comparison of two proportions and a χ2 test), little is known about the difference in power between
the two tables. In this study, we investigated the number of subjects required to obtain a power of
1 − β with a significance level of α for the allele frequency and allele positivity tables. A large
difference in the required number of subjects was found between the two tables. Allele positivity
tables were suitable for the detection of susceptibility alleles showing a dominant mode of inheritance
(MOI). On the other hand, allele frequency tables were suitable for the identification of susceptibility
alleles showing a recessive MOI or a multiplicative MOI. In the case of an additive MOI, a suitable
table was determined by combining the frequency of the susceptibility allele and the penetrance.
These results imply that there are cases in which true association is detected based on one
contingency table and is not detected based on another. A simulation analysis revealed that the type
I error rate was not much inflated under the null hypothesis of no association, even when a statistical
test was performed twice using both allele frequency and allele positivity tables. In contrast, under
the alternative hypothesis, the loss of power was marked when a test was performed once using an
unsuitable table. In conclusion, statistical tests should be performed using both tables, without
adjustment of multiplicity, in case-control studies of complex disease genes when the study objective
X-ray emission from clusters of galaxies is the most useful tool in studying mass distribution and chemical compositions in these enormously large systems. The hot intracluster medium (ICM) has been heated up to kT = 3–10 keV during the gravitational collapse, and X-ray luminosities indicate that the gas is more massive than the total galaxy mass contained in clusters by factors of 3–5. This makes ICM the dominant form of baryons in the universe. In many clusters observations indicate that ICM is in a hydrostatic equilibrium within a potential governed by the dark matter, and the cooling time is longer than the Hubble time except for the bright centers. The ICM, therefore, enables us a close look at the structure of gravitational potential. At the same time, heavy-element abundances in the ICM and their distribution are used to estimate past supernova activities and metal injection mechanism in cluster space.
The Coma cluster has been recognized as an archetype of rich and relaxed clusters, until recent ROSAT observations reveal that the intracluster medium (ICM) has a complex distribution (Briel et al. 1992; White et al. 1993). The X-ray surface brightness distribution shows a secondary peak around the galaxy NGC 4839, at 40' SW from the cluster center.
We have analyzed ASCA data of about 30 early type galaxies, and studied their X-ray emitting ISM (InterStellar Medium) properties. Our study has been motivated by the apparently very low metallicity of the ISM, which cannot easily be reconciled with theoretical predictions. By carefully examining the abundance ratios and uncertainties in the Fe-L complex, we have concluded that the ISM abundances in X-ray luminous galaxies are in fact about 1 solar. Therefore, the severe discrepancy between the ISM and stellar abundance has been relaxed. The ISM metallicity of X-ray fainter galaxies are uncertain, but at least SNe Ia contribution to the ISM abundance is smaller than in the X-ray luminous ones.
STJs are promising X-ray detectors as high energy resolution spectrometers due to the small excitation energy to break the Cooper pairs to product detectable electrons. The expected energy resolution is about 5 eV for a 6 keV incident X-rays (see review by Kraus et al. and Esposito et al.). We have developed a large area (178 × 178μm2) Nb/Al/AlOX/Al/Nb STJs (Kurakado et al. 1993) and series-connected STJs with a position resolution of 35μm for α particles (Kurakado 1997) at Nippon Steel Corporation. As a focal plane detector in future X-ray missions, we are developing STJs whose targert characteristics are; an energy resolution of 20 eV at 6keV, an effective area of 1 cm2, and position resolution of 100μm.