Epitaxial Growth of SnS₂ Ribbons on a Au–Sn Alloy Seed Film Surface

Two-dimensional metal chalcogenide film has attracted considerable interest for its use as an emerging device material for nanoelectronics. The film has been synthesized by various methods such as chemical vapor deposition, molecular beam epitaxy, and thermal vapor sulfurization. In this study, we took a new approach to synthesize tin disulfide (SnS2) by using Au–Sn alloy film as a metal seed deposited on a sapphire substrate. Multilayer SnS2 films were formed in a ribbon shape on (111)-oriented Au film and were aligned in the directions of threefold rotational symmetry. Furthermore, the SnS2 was found to have an epitaxial relationship relative to the Au film and the sapphire substrate as follows: SnS2[2̅110] || Au[101̅] || Al2O3[011̅0]. The segregation of grains consisting of a Sn-rich phase on the Au film surface and the subsequent sulfurization of these grains can be the key to the epitaxial SnS2 ribbon formation

Pauli String Partitioning Algorithm with the Ising Model for Simultaneous Measurements

We propose an efficient algorithm for partitioning Pauli strings into subgroups, which can be simultaneously measured in a single quantum circuit. Our partitioning algorithm drastically reduces the total number of measurements in a variational quantum eigensolver for a quantum chemistry, one of the most promising applications of quantum computing. The algorithm is based on the Ising model optimization problem, which can be quickly solved using an Ising machine. We develop an algorithm that is applicable to problems with sizes larger than the maximum number of variables that an Ising machine can handle (nbit) through its iterative use. The algorithm has much better time complexity and solution optimality than other existing algorithms. We investigate the performance of the algorithm using the second-generation Digital Annealer, a high-performance Ising hardware, for up to 65535 Pauli strings using Hamiltonians of molecules and the full tomography of quantum states. We demonstrate a time complexity of O(N) for N ≤ nbit and O(N2) for N > nbit for the worst case, where N denotes the number of candidate Pauli strings and nbit = 8,192 in this study. The reduction factor, which is the number of Pauli strings divided by the number of obtained partitions, can be 200 at maximum

Crystallographic Characterization and Control of Domain Structure within Individual Graphene Islands

Chemical vapor deposition of graphene on Cu foil was performed to clarify the origin of the characteristic domain structure within individual graphene islands grown on variously oriented Cu grain surfaces. While the domain structure strongly affected island shapes on Cu(111) and (101), islands grown on Cu(001) showed that they always had a four-lobed shape regardless of whether they consisted of a single domain or multiple domains. The formation of the specific shape is related to the fact that there are edges in two fast growth directions that were found to have equivalent atomic configurations for the oriented domain. Furthermore, hydrogen etching was found to preferentially act to misoriented domains within the island on Cu(001), leading to single-crystalline four-lobed island formation. Finally, we found an interesting feature in that the ratio of single-crystalline islands increased on the vicinal Cu(001) surface compared with that on the Cu(001) basal plane. Cu(111) microfacets existing on the vicinal surface may play a significant role in the nucleation stage. These findings shed new light on the graphene growth mechanism on Cu surface and may lead the way to enlarging the domain size in the complete graphene layer by means of precise control of the “intra-island” domain structures

Visualization of nasal NKp46⁺ cells by using immunohistochemistry.

<p>Frozen sections of nasal tissue obtained from 8-week-old <i>Ncr1</i>^<i>GFP/+</i> mouse were stained with 4′,6-diamidino-2-phenylindole (nucleus), anti-CD45, and anti-GFP antibodies and examined under a fluorescence microscope. Arrows indicate CD45⁺GFP(NKp46)⁺ cells. Bar, 50 μm. Data are representative of at least 3 independent experiments. a. Nasal septum. b. Nasal concha.</p

Nasal NKp46⁺ cells are NK-lineage cells.

<p>a. Flow cytometry of CD45⁺ cells from nasal passage, spleen, lung, and Nasopharynx associated lymphoid tissue (NALT) of <i>Ncr1</i>^<i>GFP/+</i> mice stained with CD3. Numbers in quadrants indicate the percentages of cells in each. Dot plot below shows percentage of GFP (NKp46)⁺ cells in CD45⁺ cells from nasal passage, spleen, lung, and NALT. b. Flow cytometry of CD3⁻NKp46⁺ cells from spleen, lung, and nasal passages stained with CD122, NK1.1, 2B4, CD49b, and CD127. Continuous lines, specific antibodies; Dashed lines, isotype-matched control antibodies. Dot plot below shows the percentage of positively stained cells. Bar, mean; n.s.; not significant (Mann-Whitney <i>U</i> test with Ryan’s multiple comparison method). Data are obtained from at least 3 independent experiments.</p

Indispensable role of nasal NK cells in influenza virus infection.

<p>a. Change of nasal NK cells after infection with PR8 1×10³ pfu/mouse intranasally. Horizontal axis, day after infection; vertical axis, percentage of nasal NK cells in CD45⁺ lymphocytes (left) or absolute count of nasal NK cells (right). *, <i>P</i> < 0.05 **, <i>P</i> < 0.01 (Mann-Whitney <i>U</i> test with Ryan’s multiple comparison method). Data are obtained from at least 3 independent experiments. b. CD69 expression of nasal NK cells after intranasal infection with influenza virus PR8 (1×10³ pfu/mouse). Histogram (left). Dashed line, naïve; solid line, day 2 after infection; bold line, day 5 after infection. Dot plot of MFI (right). Data are representative of 2 independent experiments with 4 mice. c. Nasal virus titer of mice intranasally infected with influenza virus PR8 (1×10³ pfu/mouse). Mice were injected intraperitoneally with 100 mg PK136 antibody or an isotype-matched control on days –2, 0, 2 after infection. Bar, mean; horizontal axis, day after infection; vertical axis, virus titer (pfu). Data are representative of 3 independent experiments with 4 to 6 mice in each group. n.s., not significant; *, <i>P</i> < 0.05 **, <i>P</i> < 0.01 (Mann-Whitney <i>U</i> test with Ryan’s multiple comparison method). Data are obtained from at least 3 independent experiments.</p

Nasal NK cells have a unique expression pattern of Ly49 family receptors.

<p>a, b, c. Flow cytometry of CD3⁻NKp46⁺ cells from nasal passage, spleen, and lung stained with (a) Ly49A, (b) Ly49C/F/H/I, and (c) Ly49D. Numbers in histograms indicate the percentages of positive cells. Continuous lines, specific antibodies; Dashed lines, isotype-matched control antibodies. Dot plots below shows the percentage of positively stained cells. Bar, mean; n.s., not significant; *, <i>P</i> < 0.05; **, <i>P</i> < 0.01 (Mann-Whitney <i>U</i> test with Ryan’s multiple comparison method). Data are obtained from at least 3 independent experiments.</p

Vacancy-Assisted Selective Detection of Low-ppb Formaldehyde in Two-Dimensional Layered SnS₂

A two-dimensional (2D) layered SnS2 film synthesized by the thermal-chemical vapor deposition method is utilized for detecting formaldehyde (HCHO), which causes a sick building syndrome. A back-gated field-effect transistor (FET)-based SnS2 sensor successfully detects HCHO with concentrations down to 1 ppb in a nitrogen atmosphere. Sensing measurements performed under dry air conditions also exhibit a clear response to 20 ppb of HCHO, which is more sensitive than the previously reported sensors based on other 2D-layered materials. Moreover, it is found that the sensor possesses a high selectivity for HCHO over other organic species. Theoretical calculations suggest that native sulfur vacancies existing in n-type SnS2 crystals play an important role in HCHO detection. Actually, oxygen atoms that are unexpectedly detached from HCHO molecules are found to fill the vacancies, giving rise to p-type doping in SnS2. As a result, decrease in the drain current of SnS2-FET can be found as a signal of HCHO detection. Furthermore, considering the future mass-production of sensors, we demonstrate large-scale growth of the SnS2 film by means of magnetron-sputtering deposition and subsequent annealing in a diluted hydrogen sulfide atmosphere. The sputtered film is also found to exhibit a good sensing ability to HCHO

Identification and Analysis of Natural Killer Cells in Murine Nasal Passages

<div><p>Background</p><p>Natural killer (NK) cells in the upper respiratory airways are not well characterized. In the current study, we sought to characterize and functionally assess murine nasal NK cells.</p><p>Methods</p><p>Using immunohistochemistry and flow cytometry, we compared the nasal NK cells of <i>Ncr1</i>^<i>GFP/+</i> knock-in mice, whose NK cells produced green fluorescent protein, with their splenic and pulmonary counterparts. In addition, we functionally analyzed the nasal NK cells of these mice <i>in vitro</i>. To assess the <i>in vivo</i> functions of nasal NK cells, C57BL/6 mice depleted of NK cells after treatment with PK136 antibody were nasally infected with influenza virus PR8.</p><p>Results</p><p>Immunohistochemical analysis confirmed the presence of NK cells in the lamina propria of nasal mucosa, and flow cytometry showed that these cells were of NK cell lineage. The expression patterns of Ly49 receptor, CD11b/CD27, CD62L and CD69 revealed that nasal NK cells had an immature and activated phenotype compared with that of their splenic and pulmonary counterparts. Effector functions including degranulation and IFN(interferon)-γ production after <i>in vitro</i> stimulation with phorbol 12-myristate-13-acetate plus ionomycin or IL(interleukin)-12 plus IL-18 were dampened in nasal NK cells, and the depletion of NK cells led to an increased influenza virus titer in nasal passages.</p><p>Conclusions</p><p>The NK cells of the murine nasal passage belong to the conventional NK cell linage and characteristically demonstrate an immature and activated phenotype. Despite their hyporesponsiveness <i>in vitro</i>, nasal NK cells play important roles in the host defense against nasal influenza virus infection.</p></div

Unique maturation and activation status of nasal NK cells.

<p>a. Flow cytometry of CD3⁻NKp46⁺ cells from nasal passage, spleen, and lung, and double-stained with CD11b and CD27. Numbers in quadrants indicate the percentages of cells in each. Dot plots below shows percentage of CD27^highCD11b^low cells from nasal passage, spleen, and lung. b. Flow cytometry of CD3⁻NKp46⁺ cells from spleen, lung, and nasal passages with CD62L, CD69, and CD69/CD103. The numbers in the histograms indicate the percentage of positive cells. Solid line, specific antibody; dashed line, isotype-matched control antibody. Dot plots below shows the percentage of positively stained cells. Bar, mean; n.s.; not significant; *, <i>P</i> < 0.05**, <i>P</i> < 0.01 (Mann-Whitney <i>U</i> test with Ryan’s multiple comparison method). Data are obtained from at least 3 independent experiments.</p