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We study a low-temperature on-surface reversible chemical reaction of oxygen atoms to molecules in ultrahigh vacuum on the semiconducting rutile TiO2(110)-(1 × 1) surface. The reaction is activated...

Transition-metal chalcogenides (TMCs) materials have attracted increasing interest both for fundamental research and industrial applications. Among all these materials, two-dimensional (2D) compounds with honeycomb-like structure possess exotic electronic structures. Here, we report a systematic study of TMC monolayer AgTe fabricated by direct depositing Te on the surface of Ag(111) and annealing. Few intrinsic defects are observed and studied by scanning tunneling microscopy, indicating that there are two kinds of AgTe domains and they can form gliding twin-boundary. Then, the monolayer AgTe can serve as the template for the following growth of Te film. Meanwhile, some Te atoms are observed in the form of chains on the top of the bottom Te film. Our findings in this work might provide insightful guide for the epitaxial growth of 2D materials for study of novel physical properties and for future quantum devices., 16 pages, 5 figures

[BACKGROUND & AIMS] Primary biliary cholangitis (PBC) is a chronic liver disease in which autoimmune destruction of the small intra-hepatic bile ducts eventually leads to cirrhosis. Many patients have inadequate response to licensed medications, motivating the search for novel therapies. Previous genome-wide association studies (GWAS) and meta-analyses (GWMA) of PBC have identified numerous risk loci for this condition, providing insight into its aetiology. We undertook the largest GWMA of PBC to date, aiming to identify additional risk loci and prioritise candidate genes for in silico drug efficacy screening. [METHODS] We combined new and existing genotype data for 10, 516 cases and 20, 772 controls from five European and two East Asian cohorts. [RESULTS] We identified 56 genome-wide significant loci (20 novel) including 46 in European, 13 in Asian, and 41 in combined cohorts; and a 57th genome-wide significant locus (also novel) in conditional analysis of the European cohorts. Candidate genes at newly identified loci include FCRL3, INAVA, PRDM1, IRF7, CCR6, CD226, and IL12RB1, each having key roles in immunity. Pathway analysis reiterated the likely importance of pattern recognition receptor and TNF signalling, Jak-STAT signalling, and differentiation of TH1 and TH17 cells in the pathogenesis of this disease. Drug efficacy screening identified several medications predicted to be therapeutic in PBC, some well-established in the treatment of other autoimmune disorders. [CONCLUSIONS] This study has identified additional risk loci for PBC, provided a hierarchy of agents that could be trialled in this condition, and emphasised the value of genetic and genomic approaches to drug discovery in complex disorders. [Lay summary] Primary biliary cholangitis (PBC) is a chronic liver disease that eventually leads to cirrhosis. In this study, we analysed genetic information from 10, 516 people with PBC and 20, 772 healthy individuals recruited in Canada, China, Italy, Japan, UK, or USA. We identified several genetic regions associated with PBC. Each of these regions contains several genes. For each region, we used diverse sources of evidence to help us choose the gene most likely to be involved in causing PBC. We used these ‘candidate genes’ to help us identify medications that are currently used for treatment of other conditions, which might also be useful for treatment of PBC., 原発性胆汁性胆管炎のゲノムワイド関連解析 --国際メタ解析による新規疾患感受性遺伝子と治療薬候補の同定--. 京都大学プレスリリース. 2021-06-28.

Anti-relaxation surface coatings can reduce collisions between alkali-metal atoms and cell walls, thereby prolonging the spin-polarization lifetime of alkali-metal atoms. This phenomenon can considerably improve the performance of quantum sensors. Researchers have focused on the surface topography and composition of anti-relaxation coatings in alkali-metal vapor cells and on methods that provide an increase in the relaxation time of alkali metals. We proposed a novel method to characterise the coating performance of alkali-metal cells by directly measuring the energy dissipation during collisions between the anti-relaxation coating surface and atoms in the cell. We found that the interactions between alkali-metal atoms and the anti-relaxation coating resemble elastic collisions, which can be indirectly characterised by the energy dissipation during interactions between an atomic force microscopy tip and atoms. In addition, we confirmed that the energy dissipation between collisions is positively correlated with the relaxation characteristics of alkali metals at various temperatures. This discovery is of great significance as it can be utilised to characterise the anti-relaxation coating performance of alkali-metal cells by directly analysing the energy dissipation of anti-relaxation coatings instead of measuring the relaxation time.

Analysis of environmentally sensitive materials is essential for developing and optimizing nanostructured photochemical materials and devices. Photoinduced force microscopy (PiFM) is a promising local spectroscopic technique to visualize nanoscale local optical responses by measuring the optical forces between the scanning tip and sample. In this study, we examined isolated single quantum dots (QDs) with ligands on a gold substrate via PiFM under ultra-high vacuum to characterize the QD adsorption state on the basis of the optical force. The strong self-consistent optical interaction through the tip-substrate plasmonic gap induced by laser light modulates the PiFM image depending on QD crystal existence in the gap. This observation clarified the QD absorption situation on the substrate, and the crystal position in the QDs was determined even though the ligand walls covered the crystal. This insight concerning force spectroscopy can aid further research on the photochemistry of nanostructured materials and molecular spectroscopy.

This study describes shelter operations by public health nurses (PHNs) in Kesennuma City, located near the epicenter of the Great East Japan Earthquake, which occurred on March 11, 2011. The data were semi-structured interviews with 10 PHNs, 2 nutritionists, and 2 general administrators conducted from July 2013 to January 2014. All transcripts were analyzed using the constructivist grounded theory approach. We identified two operating methods for shelters: shelters stationed by PHNs in the Old City, and shelters patrolled by PHNs in the merged district. These methods were compared using four themes. In emergency situations, &ldquo, operational periods,&rdquo, a predetermined short term for a leader to perform his/her duties responsibly, could be adopted for relatively small organizations on the frontline. PHNs must not only attempt to operate shelters on their own but also encourage residents to manage the shelters as well. Moreover, human resource allocation should be managed independently of personal factors, as strong relationships between shelter residents would sometimes disturb the flexibility of the response. Even when a situation requires PHNs to stay in shelters, frequent collecting of information and updating the plan according to response progress will help to maintain effective shelter operations.

Understanding oxygen adsorption and dissociation on the five-fold coordinated titanium (Ti5c) site of the rutile TiO2 surface is important in clarifying chemical reaction processes. Accordingly, three different configurations of molecularly adsorbed O2, including parallel side-on, inclined side-on and end-on configurations, and their dissociation were directly observed with atomic resolution at 78 K by atomic force microscopy. Our results experimentally demonstrated that the three adsorbed O2 configurations could be changed by electric field stimulation. The initial configurations of the adsorbed O2 and transition of O2 configurations were related to their coverage. On the other hand, the tunneling current stimulation could dissociate these O2 species, indicating that they are precursors for the O adatom (Oad). It is proposed that the effect of electric field stimulation contributes to the transition of these three adsorbed O2 configurations, and the effect of the tunneling current is the main factor for the dissociation of the adsorbed O2. In addition, based on the atomic contrast and height histograms of Oad, different charge states of Oad were observed, which could coexist on the surface region. The present study demonstrates an intuitional observation of O2 adsorption and dissociation on the Ti5c site, and thus is expected to be useful to understand the surface reactions on the oxide surface.

The atomic structure of a three-dimensional Au nanocluster on a TiO

We studied the O2 dissociated state under the different O2 exposed temperatures with atomic resolution by scanning probe microscopy (SPM) and imaged the O adatom by simultaneous atomic force microscopy (AFM)/scanning tunneling microscopy (STM). The effect of AFM operation mode on O adatom contrast was investigated, and the interaction of O adatom and the subsurface defect was observed by AFM/STM. Multi-channel exploration was performed to investigate the charge transfer between the adsorbed O and the TiO2(110) by obtaining the frequency shift, tunneling current and local contact potential difference at an atomic scale. The tunneling current image showed the difference of the tunneling possibility on the single O adatom and paired O adatoms, and the local contact potential difference distribution of the O-TiO2(110) surface institutively revealed the charge transfer from TiO2(110) surface to O adatom. The experimental results are expected to be helpful in investigating surface/interface properties by SPM.

We present a theoretical study of the measurements of photoinduced force microscopy (PiFM) for composite molecular systems. Using the discrete dipole approximation, we calculate the self-consistent response electric field of the entire sample including the PiFM tip, substrate, and composite molecules. We demonstrate a higher sensitivity for the PiFM measurement on resonant molecules than by the previously obtained tip-sample distance dependency $z^{-4}$ owing of the multifold enhancement of the field between the localized electric field induced at the tip-substrate nanogap and the molecular polarization. The enhanced localized electric field induced at the tip-substrate nanogap in PiFM allows high-resolution observation of the forbidden optical electronic transition in dimer molecules. We investigated the wavelength dependence of PiFM for dimer molecules and obtained images at incident light wavelengths corresponding to allowed and forbidden transitions. We reveal that these PiFM images drastically change with the frequency-dependent spatial structures of the localized electric field vectors and resolve different types of nanoparticles beyond the resolution for the optically allowed transitions. This study demonstrates that PiFM provides multifaceted information based on microscopic interactions between nanomaterials and light.

For the first time, the charge states of adsorbed oxygen adatoms on the rutile TiO2(110)-1×1 surface are successfully measured and deliberately manipulated by a combination of noncontact atomic force microscopy and Kelvin probe force microscopy at 78 K under ultrahigh vacuum and interpreted by extensive density functional theory modeling. Several kinds of single and double oxygen adatom species are clearly distinguished and assigned to three different charge states: Oad-/2Oad-, Oad2-/2Oad2-, and Oad--Oad2-, i.e., formal charges of either one or two electrons per atom. Because of the strong atomic-scale image contrast, these states are clearly resolved. The observations are supported by measurements of the short-range force and local contact potential difference as a function of the tip-sample distance as well as simulations. Comparison with the simulations suggests subatomic resolution by allowing us to resolve the rotated oxygen p orbitals. In addition, we manage to reversibly switch the charge states of the oxygen adatoms between the Oad- and Oad2- states, both individually and next to another oxygen, by modulating the frequency shift at constant positive voltage during both charging and discharging processes, i.e., by the tip-induced electric field of one orientation. This work provides a novel route for the investigation of the charge state of the adsorbates and opens up novel prospects for studying transition-metal-oxide-based catalytic reactions.

The charge state of Au nanoclusters on oxidized/reduced rutile TiO

We investigated a method to obtain a stable contrast mode on the TiO2(110) surface. The stable contrast rate is approximately 95% with a W-coated Si cantilever, which demonstrates that a stable tip apex plays an important role to obtain the real geometry of the surface during atomic force microscopy measurement. Information related to surface structure and tunnelling current on the TiO2(110) surface can be obtained by the W-coated Si cantilever. It is possible to investigate the electronic structure and surface potential on the TiO2(110) surface with atomic resolution. In particular, the proposed method could be widely applied to investigate the catalytic activity and the mechanism of a catalytic reaction by a metal-coated tip in the future.

The hydroxyl defects on rutile TiO2 surface play an important role in surface chemical reactions and understanding the catalytic reactions due to its excess electrons. In this work, the reaction be...

Clarifying the atomic configuration of step edges on a rutile TiO2 surface is crucial for understanding its fundamental reactivity, and the direct observation of atomic step edges is still a challenge. AFM is a powerful tool for investigating surface structures with true atomic resolution, and it provides the opportunity to resolve the real structure of step edges with improved techniques. In this work, we successfully imaged the atomic configuration of 〈001〉 and 〈1−11〉 step edges on the surface of rutile TiO2(110)-(1 × 1), and we present the direct observation of oxygen vacancies along the 〈1−11〉 step edges, indicating that one 〈1−11〉 step edge site corresponds to one oxygen vacancy using AFM. We also made use of the simultaneous AFM/STM measurements to explore the electronic structure of step edges, which enhanced the evidence of oxygen vacancies existing along the 〈1−11〉 step edges and further demonstrated that the 〈001〉 step edge was terminated by an O row. The effect of the reduced 〈1−11〉 step edges was explored by probing the O2 adsorption and the nucleation behavior of gold clusters. It was found that oxygen vacancies along the 〈1−11〉 step edges could contribute to O2 dissociative adsorption and there was no obvious difference compared with the oxygen vacancies on the flat terrace. The reduced step edge and terrace likewise acted as nucleation and growth sites for gold atoms/nanoparticles, in line with previous reports. The present study provides a complete characterization of the atomic configuration of the step edges on the TiO2(110) surface and plays an important role in investigating the surface chemistry of metal oxides.

The hydrogen on the surface or in the subsurface of rutile TiO2 play an important role in the surface chemical reactions and understanding the catalytic reactions due to its excess electrons. In this work, we have systematically explored the nature of hydrogen atom by atomic force microscopy (AFM)/scanning tunneling microscopy (STM) and investigated the behaviors and mechanism of hydrogen atom desorption and transfer between the surface and subsurface by Kelvin probe force spectroscopy (KPFS). The atomic contrast of surface hydrogen (Hsurf) and subsurface hydrogen (Hsub) are clearly identified by dynamic and static STM. The Hsub-Hsub interactions are systematically investigated, demonstrating the unusual no-repulsive effect of species with the same polarity. Importantly, the reversible hydrogen atom transfer between the sample surface and subsurface was successfully manipulated by KPFS performance, and mechanism of hydrogen transfer proceeds was proposed that force field together with electric field between the tip-sample space reduce the height and width of barrier resulting in the hydrogen atom transfer. The present study is expected to provide some new insights into the nature and manipulation of hydrogen atom and is useful to design the new catalyst of metal oxide.

The strain has been employed for controlled modification of electronical and mechanical properties of two-dimensional (2D) materials. However, the thermal strain-engineered behaviors of the CVD-grown MoS2have not been systematically explored. Here, we investigated the strain-induced structure and properties of CVD-grown triangular MoS2flakes by several advanced atomic force microscopy. Two different kinds of flakes with sharp-corner or vein-like nanostructures are experimentally discovered due to the size-dependent strain behaviors. The critical size of these two kinds of flakes can be roughly estimated at ∼17μm. Within the small flakes, the sharp-corner regions show specific strain-modified properties due to the suffering of large tensile strain. While in the large MoS2flakes, the complicated vein-like nanoripple structures were formed due to the interface slipping process under the larger tensile strain. Our work not only demonstrates the size-specific strain behaviors of MoS2flakes but also sheds light on the artificial design and preparation of strain-engineered nanostructures for the devices based on the 2D materials.

In atomic force microscopy (AFM), high-frequency components consisted in dynamic tip-sample interaction have been recently demonstrated as a promising technique for exploring more extensive material properties. Here we present an exploratory study of high harmonic atomic force microscopy by force-spectroscopy and high harmonic imaging. Since these components are very weak compared to the fundamental response, we firstly designed a high harmonic cantilever by tuning the second order flexural resonance frequency to an integer 6 times of its fundamental mode (i.e. ω2=6ω1). Moreover, it is verified that high harmonic can discern extra features than topographies on different samples with amplitude/frequency modulation (AM/FM) dynamic AFM mode. In AM mode, the first resonance amplitude and 6th harmonic amplitude were discussed. The 6th harmonic is more sensitive than the first order response. In FM mode, it is noted that the decaying rate of the 6th harmonic frequency is approximately 6 multiples to the slope of the fundamental frequency shift when the tip approaches to the surface of sample. This non-destructive method was also adopted to investigate the local interlayer coupling and intercalation in the two-dimensional graphene films tentatively.

Measuring vector quantities in nanoscale systems is challenging — often only scalar magnitudes can be experimentally obtained. Now, a multi-frequency atomic force microscopy method for probing the 3D force response of a Ge(001) surface is reported. Probing physical quantities on the nanoscale that have directionality, such as magnetic moments, electric dipoles, or the force response of a surface, is essential for characterizing functionalized materials for nanotechnological device applications1,2,3. Currently, such physical quantities are usually experimentally obtained as scalars. To investigate the physical properties of a surface on the nanoscale in depth, these properties must be measured as vectors. Here we demonstrate a three-force-component detection method, based on multi-frequency atomic force microscopy on the subatomic scale4,5,6,7,8,9 and apply it to a Ge(001)-c(4 × 2) surface. We probed the surface-normal and surface-parallel force components above the surface and their direction-dependent anisotropy and expressed them as a three-dimensional force vector distribution. Access to the atomic-scale force distribution on the surface will enable better understanding of nanoscale surface morphologies, chemical composition and reactions10,11, probing nanostructures via atomic or molecular manipulation12,13, and provide insights into the behaviour of nano-machines on substrates14,15.

We study a low-temperature on-surface reversible chemical reaction of oxygen atoms to molecules in ultrahigh vacuum on the semiconducting rutile TiO

Interfacial engineering, such as molecule intercalation, can modify properties and optimize performance of van der Waals heterostructures and their devices. Here, we investigated the pristine and water molecule intercalated heterointerface of niobium disulphide (NbS

We developed a versatile Quasi-finite-element scanning method to analyse the concentration and homogeneity of the ensembles of nitrogen-vacancy (NV−) centres in block diamonds. In this method, 13 μ m × 13 μ m area of the bulk diamond with high-density NV− centres was divided into small pieces at the nanoscale by using a focused light beam. The concentration of NV− centres was obtained and imaged through the fluorescence intensity of each pixel by employing a home-built spectrometer. In addition, global and local homogeneities were introduced to evaluate the NV− centre distribution. NV− centres in a specific pixel exhibited preferred direction growth peaks attributed to the diamond crystal orientation. Moreover, the uniformity of NV− centres was not proportional to the electron irradiation duration, but an optimal time was observed. This study can be beneficial for enhancing the sensitivities of bulk magnetometry based on confocal systems.

Recently, we achieved atomic-resolution optical imaging with near-field scanning optical microscopy using photon-induced force detection. In this technique, the surface photovoltage of the silicon-tip apex induced by the optical near field on the surface is measured as the electrostatic force. We demonstrated atomicresolution imaging of the near field on the α-Al2O3 (0001) surface of a prism. We investigated the spatial distribution of the near field by scanning at different tip-sample distances and found that the atomic corrugation of the near-field signal was observed at greater distances than that of the atomic force microscopy signal. As the tip-sample distance increased, the normalized signal-to-noise ratio of the near field is in a gradual decline almost twice that of the frequency shift (Δf).

Strain engineering plays a vital role in controlling the physical properties of two-dimensional (2D) materials. However, the nanomechanical behavior of atomically thin 2D crystals under strain has not been completely understood. Here, strain-induced hierarchical ripple nanostructures in triangular MoS2 flakes were investigated by advanced atomic force microscopy and optical spectral measurements. The hierarchical nanoripples exhibited a threefold radial pattern, and their mechanical, electronic, and optical spectra characteristics were significantly modified due to the suffering from large tensile strain. Structure evolution of these hierarchical nanoripples was further discussed based on the geometry and thickness of MoS2 flakes, and we attributed the curtain effect at the limit of a single atomic layer. Our study will be beneficial in designing nanomechanical structures and prototype electromechanical devices with 2D materials.

We experimentally observed the dynamic behavior of OH on the Ti site (OHt) of TiO2(110) at 78 K in detail by atomic force microscopy (AFM). OHt was imaged as a dimer shape or a fuzzy round shape corresponding to the motion of OHt that OHt swings along the [1–10] direction. The frequency of swing positively responds to the applied bias voltage between the tip and the sample, and it is proposed that the applied bias voltage decreases the barrier of the OHt transition between two or more equilibrium states. Such specific response of OHt to the applied bias voltage can be used as the fingerprint. In addition, the atomic contrast of O adatom (Oad) and OHt is compared with the contrast of other surface species by AFM, and it is demonstrated that the contrast of Oad and OHt is similar to the contrast of the surface defects due to the effect of tip apex polarity. H atom desorption of OHt is performed by Kelvin probe force spectroscopy, and it is resulted from the reduction of barrier width together with the tunneling electron excitation. The present study is expected to be useful to explore the property of H-involved species and the surface reactions on the oxide surface by AFM.

The chemical and physical processes on surfaces are significantly influenced by the surface potential of materials. When using the frequency modulation Kelvin probe force microscopy (FM-KPFM), which has been widely used for measuring the surface potential distribution with high spatial resolution, it is very difficult to distinguish the surface potential due to the surface state from that due to the bulk state, because the charge transfer between the surface and bulk states occurs at a low-frequency ac bias voltage in the kHz range. Here, we propose a heterodyne FM-KPFM method using a high-frequency ac bias voltage in the MHz range to distinguish the surface and bulk states. This method is based on the heterodyne effect between the mechanical cantilever oscillation and the oscillating electrostatic force. For the first time, we succeeded in achieving the atomic-resolution imaging of the surface potential on an O-rich TiO2(110) surface using the electrostatic interaction in the MHz range. Furthermore, we could measure the upward and downward band bending on the surface at the atomic scale.

Oxygen adatom on rutile TiO2(1 1 0)-(1 × 1) surface was imaged by atomic force microscopy (AFM) with atomic resolution. The atomic contrast inversion of oxygen adatom is dependent on tip-sample distance and can be obtained in both constant frequency shift and constant height mode. The origin of contrast inversion was analyzed, combining the effect of adsorbed species, feedback loop and tip apex structure. Experimental frequency shift versus distance curves around O adatom show that there is a turning-point in the constant frequency shift mode and a cross-point in the constant height mode. The repulsive force is thought to contribute to the contrast inversion of oxygen adatom. The present results show the origin of contrast inversion of oxygen adatom on rutile TiO2(1 1 0)-(1 × 1) surface and illustrate the importance of tip-height for the atomic contrast inversion of the surface adsorbate on the metal oxide surface.

The development of practical applications of the magnetometer based on ensemble of nitrogen-vacancy centers has been impeded by the large size of the system. In this paper, we present an integrated and miniaturized magnetic field sensor with a volume of approximately 10 cm3. Compared to the previous design, with the fluorescence waveguide excitation and collection structure, both the optical excitation system and collection system are integrated into a compact device by combining the optical fiber, so that it can be a handheld sensing head. We demonstrated experimentally that this sensor head enables the optically detected magnetic resonance measurements with or without the external magnetic field. Subsequently, we verified that the magnetic-field sensitivity is approximately 67 , and projected the photon shot noise limited sensitivity to be 2.04 . This novel system has considerable performance regarding previous designs while greatly reducing dimensions.

Transition-metal-oxide as a typical model surface for investigating the catalytic mechanism has been widely studied. Over the past years, the TiO2 properties have been reported. It is commonly accepted that the catalytic activity of reduced TiO2 is related to its defects, with the accompanying excess electrons leading to n-type conductivity. It is realized that subsurface charge is of key importance for the redox chemistry of TiO2 (110).Subsurface charge is explored by atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). Subsurface charge exerts an additional attractive force on the scanning AFM tip, resulting in the relative retraction of tip motion in order to keep a constant frequency shift. As a result, the subsurface charged region is imaged as protrusion in an AFM topographic image. The height of bright hillock is mainly distributed in three different ranges, which means that the subsurface charges are at three different subsurface layers. The AFM results show such subsurface charges repel the electropositive oxygen vacancy, hydrogen atoms and step edges. It is obvious that there is not only an Ov depletion zone but also the subsurface charge free region in the proximity of the \begin{document}$\left\langle {001} \right\rangle $\end{document} and \begin{document}$\left\langle {1\bar 11} \right\rangle$\end{document} step edge.The KPFM image indicates that the subsurface charges are the positive charges. which is consistent with common sense. After oxygen exposure, it is found that the oxygen adatom is electronegative, but it is absent in the vicinity of positive subsurface charges. Irrespective of adsorbate being electropositive or electronegative, an adsorbate-free zone generally exists in the proximity of the charged region. Obviously, the present study is expected to provide some insights into clarifying the nature of subsurface charge and improving catalytic design.

For the first time, the charge states of adsorbed oxygen adatoms on the rutile TiO

Clarifying the atomic configuration of step edges on a rutile TiO2 surface is crucial for understanding its fundamental reactivity, and the direct observation of atomic step edges is still a challenge. AFM is a powerful tool for investigating surface structures with true atomic resolution, and it provides the opportunity to resolve the real structure of step edges with improved techniques. In this work, we successfully imaged the atomic configuration of 001 and 1-11 step edges on the surface of rutile TiO2(110)-(1 × 1), and we present the direct observation of oxygen vacancies along the 1-11 step edges, indicating that one 1-11 step edge site corresponds to one oxygen vacancy using AFM. We also made use of the simultaneous AFM/STM measurements to explore the electronic structure of step edges, which enhanced the evidence of oxygen vacancies existing along the 1-11 step edges and further demonstrated that the 001 step edge was terminated by an O row. The effect of the reduced 1-11 step edges was explored by probing the O2 adsorption and the nucleation behavior of gold clusters. It was found that oxygen vacancies along the 1-11 step edges could contribute to O2 dissociative adsorption and there was no obvious difference compared with the oxygen vacancies on the flat terrace. The reduced step edge and terrace likewise acted as nucleation and growth sites for gold atoms/nanoparticles, in line with previous reports. The present study provides a complete characterization of the atomic configuration of the step edges on the TiO2(110) surface and plays an important role in investigating the surface chemistry of metal oxides.

In photoinduced force microscopy (PiFM), amplitude modulation techniques, such as direct mode, and heterodyne amplitude modulation techniques have been used to detect the photoinduced force. These amplitude modulation techniques are affected by other forces because the resonance frequency of a cantilever shifts and non-conservative force damp the cantilever motion. Here, we investigate and propose the heterodyne frequency modulation technique (heterodyne-FM) for reduction of the influence of the other forces and photothermal force. Heterodyne-FM PiFM enabled the acquisition of PiFM images and force spectra without those artifacts. Using the heterodyne-FM technique, we succeed to visualize and evaluate photoinduced force between a tip and a quantum dot on gold surface.

In the variant of atomic force microscopy (AFM) known as photoinduced force microscopy (PiFM), amplitude-modulation techniques have been used to detect the photoinduced force. In such approaches the signal is also affected by other forces, which damp the motion of the probe's cantilever. This study proposes a heterodyne (sideband-detection) $f\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}q\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}y$-modulation technique that enables one to obtain the photoinduced force without artifacts from the photothermal force and the changes in the resonance frequency of the cantilever, and thus to realize true optical imaging at the nanoscale.

We have carried out high-speed imaging of the topography and local contact potential difference (LCPD) on rutile TiO

The surface potential distribution measured using Kelvin probe force microscopy (KPFM) is influenced by the contact potential difference (CPD) between the tip and surface, the stray capacitance of the cantilever, and fixed monopole charges on the surface and tip. The interpretation of atomic-scale KPFM contrast studies has been controversial. Here, we investigate the contrast mechanism in KPFM with atomic resolution. First, the effect of stray capacitance on potential measurements is explored in the FM-, AM-, and heterodyne AM-KPFM modes. The distance dependence of the modulated electrostatic force in AM-KPFM is much weaker than that in FM- and heterodyne AM-KPFM, and the stray capacitance of the cantilever, which strongly affects potential measurements in AM-KPFM, is almost completely eliminated in FM- and heterodyne AM-KPFM. The very small local contact potential difference (LCPD) corrugation in AM-KPFM is attributed to an artefact induced by the topographic feedback. Next, an investigation of the LCPD on a TiO2 (110)-1 × 1 surface and atom-dependent bias-distance spectroscopic mapping are performed. The LCPD of TiO2 (110) is dominated not only by the permanent surface dipole between the tip apex atom and the surface, but also by the dipoles induced by the chemical interaction between the tip and sample. Finally, we propose a new multiple-image method for obtaining the frequency shift, tunneling current, and LCPD images. For the first time, we obtain three images on a TiO2(110) surface with atomic resolution at 78 K. The LCPD has a higher value on a defect site than on the nearby O rows because excess electrons caused by surface defects are delocalized on the nearby Ti rows. The multiple-image method can be used to investigate the charge transfer phenomena between nanoparticles and surface sites and to elucidate the mechanisms of catalytic reactions.

CONTEXT The roles of adult daycare services during disaster evacuations in the relationships with community resilience are unknown. The initial 72 hours after a disaster are crucial because people in the disaster area depend on their own efforts or the resources available at the moment until the arrival of external support. OBJECTIVE To clarify the evacuation-related decision making of the administrators of adult daycare services within 72 hours after the Great East Japan Earthquake and to describe the roles of adult daycare services during the month following the earthquake. DESIGN Qualitative study using semistructured interviews. The transcribed interviews were analyzed anonymously through an inductive qualitative content analysis using ATLAS.ti. SETTING Kesennuma City, Miyagi Prefecture. PARTICIPANTS Eleven key informants (3 primary care providers and 8 administrators) from 8 institutions. RESULTS Immediately after the disaster, 6 institutions implemented shelter-in-place. The evacuation behaviors of the adult daycare institutions were diverse, but each institution was transformed repeatedly within 72 hours. With respect to evacuation decision making, the primary issues involved whether to go to mandatory evacuation sites. However, after 3 days, the institutions relocated from these sites to other places. During a period of approximately 1 month, 7 institutions managed the evacuation of service users and care providers. The expanded institutional roles were as follows: "confirming the safety of the users' families," "substituting residential facilities," and "imposing leadership during the evacuation." CONCLUSIONS If institutions choose to shelter-in-place, it should be sustained for as long as possible. Sufficiently planned stores of food and water to accommodate daytime users are needed. Institutions that employ shelter-in-place as an evacuation plan should maintain close contact with local governments. Furthermore, local governments should predetermine how to manage these institutions in the event of a disaster. To build community resilience for disasters, developing linkage with private organizations' resilience is beneficial.

We propose a new multi-image method for obtaining the frequency shift, tunneling current and local contact potential difference (LCPD) on a TiO

Interfacial engineering, such as molecule intercalation, can modify properties and optimize performance of van der Waals heterostructures and their devices. Here, we investigated the pristine and water molecule intercalated heterointerface of niobium disulphide (NbS2) on hexagonal boron nitride (h-BN) (NbS2/BN) using advanced atomic force microscopy (AFM), and observed the metal-insulator transition (MIT) of first layer (1L-) of NbS2 induced by water molecule intercalation. In pristine sample, interfacial charge transfers were confirmed by the direct detection of trapped static charges at the post-exposed h-BN surface, produced by mechanically peeling off the 1L-NbS2 from the substrate. The interfacial charge transfers facilitate the intercalation of water molecules at the heterointerface. The intercalated water layers make a MIT of 1L-NbS2, while the pristine metallic state of the following NbS2 layers remains preserved. This work is of great significance to help understand the interfacial properties of 2D metal/insulator heterostructures and can pave the way for further preparation of an ultrathin transistor.