Identification of exfoliated monolayer hexagonal boron nitride films with a digital color camera under white light illumination.

Optical microscopy with white light illumination has been employed when obtaining exfoliated monolayer hexagonal boron nitride (1L hBN) films from a large number of randomly placed films on a substrate. However, real-time observation of 1L hBN using a color camera under white light illumination remains challenging since hBN is transparent in the visible wavelength range. The poor optical constant of 1L hBN films in microphotographs is significantly improved using a Si substrate coated with a SiNxthin-film (SiNx/Si). When observing hBN thin films on SiNx/Si using a color digital camera in an optical microscope under white light illumination, the clarity of the captured color images depends on the thickness of the SiNxfilm (d). For real-time direct observation, thedwas optimized based on quantitative chromatic studies tailored to Bayer filters of a color image sensor. Through image simulation, it was determined that the color difference between 1L hBN and the bare substrate is maximized atd= 59 or 70 nm, which was experimentally verified. The SiNx/Si with optimizeddvalues visualized 1L hBN films without requiring significant contrast enhancement via image processing under white light illumination in real-time. Furthermore, the captured color photographs facilitate the reliable determination of the number of layers in few-layer hBN films using the contrast of the green channel of the images.

Identification of the monolayer thickness difference in a mechanically exfoliated thick flake of hexagonal boron nitride and graphite for van der Waals heterostructures.

Exfoliated flakes of layered materials, such as hexagonal boron nitride (hBN) and graphite with a thickness of several tens of nanometers, are used to construct van der Waals heterostructures. A flake with a desirable thickness, size, and shape is often selected from many exfoliated flakes placed randomly on a substrate using an optical microscope. This study examined the visualization of thick hBN and graphite flakes on SiO2/Si substrates through calculations and experiments. In particular, the study analyzed areas with different atomic layer thicknesses in a flake. For visualization, the SiO2thickness was optimized based on the calculation. As an experimental result, the area with different thicknesses in a hBN flake showed different brightness in the image obtained using an optical microscope with a narrow band-pass filter. The maximum contrast was 12% with respect to the difference of monolayer thickness. In addition, hBN and graphite flakes were observed by differential interference contrast (DIC) microscopy. In the observation, the area with different thicknesses exhibited different brightnesses and colors. Adjusting the DIC bias had a similar effect to selecting a wavelength using a narrow band-pass filter.

Visualization of a hexagonal born nitride monolayer on an ultra-thin gold film via reflected light microscopy.

Hexagonal boron nitride (h-BN) is an important insulating layered material for two-dimensional heterostructure devices. Among many applications, few-layer h-BN films have been employed as superior tunneling barrier films. However, it is difficult to construct a heterostructure with ultra-thin h-BN owing to the poor visibility of flakes on substrates, especially on a metallic surface substrate. Since reflectance from a metallic surface is generally high, a h-BN film on a metallic surface does not largely influence reflection spectra. In the present study, a thin Au layer with a thickness of ∼10 nm deposited on a Si substrate with a thermally grown SiO2was used for visualizing h-BN flakes. The thin Au layer possesses conductivity and transparency. Thus, the Au/SiO2/Si structure serves as an electrode and contributes to the visualization of an ultra-thin film according to optical interference. As a demonstration, the wavelength-dependent contrast of exfoliated few-layer h-BN flakes on the substrate was investigated under a quasi-monochromatic light using an optical microscope. A monolayer h-BN film was recognized in the image taken by a standard digital camera using a narrow band-pass filter of 490 nm, providing maximum contrast. Since the contrast increases linearly with the number of layers, the appropriate number of layers is identified from the contrast. Furthermore, the insulating property of a h-BN flake is examined using a conductive atomic force microscope to confirm whether the thin Au layer serves as an electrode. The tunneling current through the h-BN flake is consistent with the number of layers estimated from the contrast.

Wettability Control of Gold Surfaces Modified with Benzenethiol Derivatives: Water Contact Angle and Thermal Stability.

The water wettability of Au surfaces has been controlled using various benzenethiol derivatives including 4-methylbenzenethiol, pentafluorobenzenethiol, 4-flubrobenzenethiol, 4-methoxy-benzenethiol, 4-nitrobenzenethiol, and 4-hydroxybenzenethiol. The water contact angle of the Au surface modified with the benzenethiol derivative was found to vary in the wide range of 30.9° to 88.3°. The contact angle of the modified Au films annealed was also measured in order to investigate their thermal stability. The change in the contact angle indicated that the modified surface is stable at temperatures below about 400 K. Meanwhile, the activation energy of desorption from the modified surface was estimated from the change in the contact angle. The modified Au surface was also examined using X-ray photoelectron spectroscopy.

[A case of long-term survival after resection of aortic arch for locally advanced non-small cell lung cancer with induction chemotherapy].

Our patient was a 57-year-old male with a history of esophageal cancer. He was referred to our hospital for squamous cell lung carcinoma(SCC). Chest computed tomography identified a mass in the left lung field, which was suspected to be invading the reconstructed gastric tube, left subclavian artery, common carotid artery, and distal aortic arch. He was diagnosed as primary pulmonary squamous cell carcinoma(SCC)because six years had already passed since a previous surgery for early esophageal cancer. He received three courses of induction chemotherapy including S-1/CDDP. We evaluated the therapy as a partial response. He underwent an extended resection of distal aortic arch and left subclavian artery with left upper lobectomy, and those vessels were reconstructed using prosthetic grafts. Pathological findings showed the tumor as a well differentiated SCC of pT4N0M0 at stage III A, with a residual tumor on the reconstructed gastric tube, even though the effect of induction chemotherapy was Ef2. He received three courses of S-1/CDDP after surgery. The patient has been well without recurrence for 31 months after surgery.

[Renal-salt wasting syndrome in a patient with CDDP containing chemotherapy for recurrent non-small-cell lung cancer].

Hyponatremia is one of the major side effects that occurs after CDDP-based cancer chemotherapy. However, RSWS has rarely been reported as a cause of hyponatremia occurring after chemotherapy containing CDDP. A 70-year-old female who had recurrent lung adenocarcinoma after surgery was treated with CDDP, pemetrexed and bevacizumab-containing chemotherapy. She suffered from acute-onset consciousness disturbance and hyponatremia on day 3 of chemotherapy. Although SIADH was considered at the time of onset, the patient was subsequently diagnosed with RSWS, based on observations of dehydration, high levels of urinary sodium excretion and evidence of renal tubule failure. She recovered from these conditions without any residual disability after infusion of hypertonic saline fluid on day 13 of chemotherapy. In this report, we have described RSWS, which is rare complication that may follow CDDP-based chemotherapy. It is important, but not very easy, to distinguish between SIADH and RSWS clinically for the selection of an appropriate treatment.

Polarization Raman Imaging of Organic Monolayer Islands for Crystal Orientation Analysis.

An organic semiconductor film made of diphenyl derivative dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DPh-DNTT) has high carrier mobility. However, this mobility may be greatly affected by the crystal orientation of the DPh-DNTT's first layer. Polarization Raman microscopy is widely used to quantitatively analyze the molecular orientation, and thus holds great potential as a powerful tool to investigate the crystal orientation of monolayer DPh-DNTT with high spatial resolution. In this study, we demonstrate polarization Raman imaging of monolayer DPh-DNTT islands for crystal orientation analysis. We found that the DPh-DNTT sample indicated a strong dependence of the Raman intensity on the incident polarization direction. Based on the polarization dependence, we developed an analytical method of determining the crystal orientation of the monolayer DPh-DNTT islands and experimentally confirmed that our technique was highly effective at imaging the islands' crystal orientation with a spatial resolution of a few hundred nanometers.

Esaki diodes live and learn.

We report, as the result of shelf-life tests for Esaki diodes, the observation of minute but tangible reductions in the tunnel current after the lapse of half a century. The reduction could be attributed to 0.25% widening in the tunnel path.

Crystal Orientation Imaging of Organic Monolayer Islands by Polarized Light Microscopy.

The initial stage of organic semiconductor film formation greatly affects the properties of films, which are used in organic devices including thin-film transistors and light-emitting diodes. Organic monolayer islands that are formed on a suitable substrate can be observed with a conventional optical microscope. Furthermore, the use of a polarized microscope allows the determination of the refractive index and crystal orientation of islands. Here, we report organic monolayer islands of 2,9-diphenyl-dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DPh-DNTT) deposited on a Si substrate with thermally grown SiO2 to investigate the crystal orientation of islands by polarized light microscopy. The observation of DPh-DNTT islands under polarized quasi-monochromatic light reveals that reflection intensity depends on both the crystal orientation and irradiation wavelength. A comparison between experimental and calculated reflection intensities provides an estimate of an anisotropic complex refractive index in the plane. The crossed-polarized microscopy image of a SiO2/Si substrate with DPh-DNTT islands shows that the contrast between the islands and SiO2 surface is sensitive to the angle between the polarizer and analyzer and depends on the direction of crystal orientation. The dependence of reflection contrast, which can be explained by the anisotropic extinction coefficient, is used to confirm crystal orientation.

Data on optical microscopy and vibrational modes in Diphenyl Dinaphthothienothiophene thin films.

The thin-films of 2,9-diphenyl-dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DPh-DNTT) prepared by vacuum deposition was observed by the optical microsope. By applying the dark-field mode in observation and/or image processing after imaging appropriately, morphological structure with a resolution of a few nanometers height was visualized easily and quickly. The technique can be used in a similar to atomic force microscopy, which is commonly used for imaging surface morphology. Moreover, the vibrational modes of a DPh-DNTT molecule calculated by quantum chemistry program is described as well as the comparison of the experimental Raman spectra for identification. The presented data are produced as part of the main work entitled "The Growth Mechanism and Characterization of Few-layer Diphenyl Dinaphthothienothiophene Films Prepared by Vacuum Deposition" (Hattori et al., 2019).

[A case of postoperative liver metastases from gastric cancer successfully treated with hepatic arterial infusion of paclitaxel].

A 69-year-old man underwent total gastrectomy for advanced gastric cancer in August 2001. After surgery, he was treated daily with UFT 300 mg. In October 2002, the tumor marker (CEA) increased in value, and CT revealed multiple liver metastases. Because there were no extrahepatic metastases, we attempted to use hepatic arterial injection chemotherapy. A reservoir was placed in the hepatic artery on November 12. Thereafter, intra-arterial injection of paclitaxel at 120 mg (80 mg/m2) was administered over one hour to the reservoir. This arterial injection chemotherapy was administered once weekly for 3 weeks followed by 1 week rest. After 3 courses, CEA decreased markedly and CT revealed remarkable tumor reduction which was thought to show a partial response (PR). After 6 courses, PR was continued. Adverse effects were only grade 1 alopecia and leukopenia. No major adverse effects were observed. These results suggest that hepatic arterial injection therapy with weekly paclitaxel is effective against recurrent gastric cancer with liver metastases.

Two-dimensional photonic crystal resist membrane nanocavity embedding colloidal dot-in-a-rod nanocrystals.

A novel technique for the fabrication of photonic crystal (PC) nanocavities coupled with colloidal nanocrystals is presented. A waveguiding resist membrane embedding highly emitting dot-in-a-rod nanocrystals was patterned through e-beam lithography and released through wet etching process. The proposed approach makes the PC structure independent of fabrication imperfections induced by etching steps. Micro-photoluminescence spectra revealed degenerated resonant modes (Q-factor approximately 700) whose fabrication-induced spectral splitting is comparable to the full width at half-maximum of the peaks. Active nanocavities tunable from visible to infrared spectral range on GaAs or Si substrates can be easily implemented by this technique.