211At on gold nanoparticles for targeted radionuclide therapy application.

Targeted alpha therapy (TAT) is a methodology that is being developed as a promising cancer treatment using the α-particle decay of radionuclides. This technique involves the use of heavy radioactive elements being placed near the cancer target area to cause maximum damage to the cancer cells while minimizing the damage to healthy cells. Using gold nanoparticles (AuNPs) as carriers, a more effective therapy methodology may be realized. AuNPs can be good candidates for transporting these radionuclides to the vicinity of the cancer cells since they can be labeled not just with the radionuclides, but also a host of other proteins and ligands to target these cells and serve as additional treatment options. Research has shown that astatine and iodine are capable of adsorbing onto the surface of gold, creating a covalent bond that is quite stable for use in experiments. However, there are still many challenges that lie ahead in this area, whether they be theoretical, experimental, and even in real-life applications. This review will cover some of the major developments, as well as the current state of technology, and the problems that need to be tackled as this research topic moves along to maturity. The hope is that with more workers joining the field, we can make a positive impact on society, in addition to bringing improvement and more knowledge to science.

C2H4 adsorption on Cu(210), revisited: bonding nature and coverage effects.

With the aid of density functional theory (DFT)-based calculations, we investigate the adsorption of C2H4 on Cu(210). We found two C2H4 adsorption sites, viz., the top of the step-edge atom (S) and the long bridge between two step-edge atoms (SS) of Cu(210). The step-edge atoms on Cu(210) block the otherwise active terrace sites found on copper surfaces with longer step sizes. This results in the preference for π-bonded over di-σ-bonded C2H4. We also found two stable C2H4 adsorption orientations on the S- and SS-sites, viz., with the C2H4 C[double bond, length as m-dash]C bond parallel (fit) and perpendicular (cross) to [001]. Furthermore, we found that the three peaks observed in previous temperature programmed desorption (TPD) experiment [Surf. Sci., 2011, 605, 934-940] could be attributed to C2H4 in the S-fit or S-cross, S-fit and S-cross-fit (S-cross and S-fit configurations that both exist in the same unit cell) configurations on Cu(210).

Supersonic molecular beam experiments on surface chemical reactions.

The interaction of a molecule and a surface is important in various fields, and in particular in complex systems like biomaterials and their related chemistry. However, the detailed understanding of the elementary steps in the surface chemistry, for example, stereodynamics, is still insufficient even for simple model systems. In this Personal Account, I review our recent studies of chemical reactions on single-crystalline Cu and Si surfaces induced by hyperthermal oxygen molecular beams and by oriented molecular beams, respectively. Studies of oxide formation on Cu induced by hyperthermal molecular beams demonstrate a significant role of the translational energy of the incident molecules. The use of hyperthermal molecular beams enables us to open up new chemical reaction paths specific for the hyperthermal energy region, and to develop new methods for the fabrication of thin films. On the other hand, oriented molecular beams also demonstrate the possibility of understanding surface chemical reactions in detail by varying the orientation of the incident molecules. The steric effects found on Si surfaces hint at new ways of material fabrication on Si surfaces. Controlling the initial conditions of incoming molecules is a powerful tool for finely monitoring the elementary step of the surface chemical reactions and creating new materials on surfaces.

Directions of chemical change: experimental characterization of the stereodynamics of photodissociation and reactive processes.

This perspective article aims at accounting for the versatility of some current experimental investigations for exploring novel paths in chemical reactions. It updates a previous one [Phys. Chem. Chem. Phys., 2005, 5, 291] and is limited to work by the authors. The use of advanced molecular beam techniques together with a combination of modern tools for specific preparation, selection and detection permits us to discover new trends in reactivity in the gas phase as well as at interfaces. We specifically discuss new facets of stereodynamics, namely the effects of molecular orientation and alignment on reactive and photodissociation processes. Further topics involve roaming paths and triple fragmentation in photodissociation probed by imaging techniques, chirality effects in collisions and deviations from Arrhenius behavior in the temperature dependence of chemical reactions.

The effects of alloying and segregation for the reactivity and diffusion of oxygen on Cu3Au(111).

We report results of the segregation induced by the adsorption of O2 and the barrier of the formation of Cu2O in Cu3Au(111) with an experimental and theoretical approach. Oxidation by a hyperthermal O2 molecular beam (HOMB) was investigated by X-ray photoemission spectroscopy in conjunction with a synchrotron light source. From the incident-energy dependence of the measured O-uptake curve, dissociative adsorption of O2 is less effective on Cu3Au(111) than on Cu(111). The dissociative adsorption is accompanied by the Cu segregation on Cu3Au(111) as well as on Cu3Au(100) and Cu3Au(110). The obvious growth of Cu2O for a 2.3 eV HOMB cannot be observed and it suggests that the Au-rich protective layers prevent the diffusion of O atoms into the bulk. The theoretical approach based on density functional theory indicates that O adsorption shows the same behavior on Cu3Au(111) and on Cu(111). For the diffusion case, the barrier to diffuse into the subsurface in segregated Cu3Au(111) is higher than in Cu(111). This indicates that the segregated Au-rich layer in Cu3Au(111) works as a protective layer.

Initial stages of Cu3Au(111) oxidation: oxygen induced Cu segregation and the protective Au layer profile.

We report results of our experimental and theoretical studies on the Au concentration profile of Cu3Au(111) during oxidation by a hyperthermal O2 molecular beam at room temperature, using X-ray photoemission spectroscopy (XPS), in conjunction with synchrotron radiation (SR), and density functional theory (DFT). Before O2 exposure, we observe strong Au segregation to the top layer, i.e., Au surface enrichment of the clean surface. We also observe a gradual Cu surface enrichment, and Au enrichment of the second and third (subsurface) layers, with increasing O coverage. Complete Cu segregation to the surface occurs at 0.5 ML O surface coverage. The Au-rich second and third layers of the oxidized surface demonstrate the protective layer formation against oxidation deeper into the bulk.

Patterns of Reacted Adatoms in Adsorption of Acetonitrile on Si{111}-(7 × 7).

We report on the covalent binding of acetonitrile (CH3CN) on Si{111}-(7 × 7) at ∼300 K studied by scanning tunneling microscopy, thermal desorption spectroscopy, and first-principles theoretical calculations. The site-specific study makes it possible to unravel the site-by-site and step-by-step kinetics. A polarized CH3CN prefers to adsorb on the faulted half more frequently compared to on the unfaulted half. Moreover, a molecular CH3CN adsorbs four-times more preferably on the center adatom-rest atom (CEA-REA) pair than on the corner adatom-rest atom (COA-REA) pair. Such site selectivity, the number ratio of reacted-CEA/reacted-COA, depends on the number of reacted adatoms in the half-unit cell. The site selectivity and the resulting reacted-adatom patterns are understood well by considering a simple model. In this simple model, the molecular adsorption probability changes step-by-step and site-by-site with increasing reacted adatoms. Furthermore, our theoretical calculations are overall consistent with the experimental results. The site-selectivity of the adsorption of CH3CN on Si{111}-(7 × 7) is explained well by the chemical reactivity depending on the local conformation, the local density of states, and the interaction between polarized adsorbates.

[Impact of migraine on family members: an investigation by Impact of Migraine on Partners and Adolescent Children (IMPAC)].

Using the Japanese version of the Impact of Migraine on Partners and Adolescent Children (IMPAC) and Family Question prepared based on IMPAC, we investigated the impact of migraine on family members from the perspectives of both patients and their family members. Our results showed that migraine had an impact on the family members living with the patients in Japan as well, and the perception of migraine differed partially between patients and their family members. We also found that the Japanese version of the IMPAC showed a correlation with existing instruments to evaluate impact of migraine, indicating its validity. The application of this study's findings in clinical practice could help alleviate the disease burden of migraine on patients and their family members.

The effect of step geometry in copper oxidation by hyperthermal O2 molecular beam: Cu(511) vs Cu(410).

Steps are known to be often the active sites for the dissociation of O(2) molecules and the nucleation sites of oxide films since they provide paths for subsurface migration and oxygen incorporation. In order to unravel the effect of their morphology on the oxidation of Cu surfaces, we present here a detailed investigation of the O(2) interaction with Cu(511) and compare it with previous results for Cu(410), a surface exhibiting terraces of similar size and geometry but different step morphology. As for Cu(410) we find, by x-ray photoemission spectroscopy performed with synchrotron radiation, that Cu(2)O formation gradually starts above half a monolayer oxygen coverage and that the ignition of oxidation can be lowered to room temperature by dosing O(2) via a supersonic molecular beam at hyperthermal energy. The oxidation rate for Cu(511) comes out to be lower than for Cu(410) at normal incidence, about the same when the O(2) molecules impinge towards the ascending step rise, but higher when they hit the surface along trajectories even slightly inclined towards the descending step rise. These findings can be rationalized by a collision induced absorption mechanism.

Relationships between the gonial angle and mandibular ramus morphology in dentate subjects: a panoramic radiophotometric study.

Analysis of dental panoramic radiographs (DPRs) is an indispensable diagnostic tool for dental implants both pre and post operation. Many studies on linear and angular morphometry of the mandibular body have been conducted, but those on the mandibular ramus have not yet been reported. The purpose of this study was to investigate the differences in the morphometric parameters of the mandibular ramus between high and low gonial angles (GAs) on DPRs as well as between genders, and to determine the relationships between GA and variables of the mandibular ramus morphometry. The DPRs of 156 dentate subjects (78 for each gender) with more than 15 teeth present, a mean age of 49.54 years, and a mean number of teeth of 26.20 were examined. The films were divided into the following 2 groups of GA: less than 120° (low gonial angle, LGA) and more than 125° (high gonial angle, HGA) in both the right and left sides. The parameters for Ar'-Go, MaF-Go, RW, and RD in the LGA group were significantly larger than those in the HGA group in both men and women, but that for the ramus angle (RA) was significantly smaller in the LGA group than in the HGA group. Significant gender differences in the 2 GA groups were recognized with respect to the Ar'-Go, MaF-Go, RW, and RD parameters. Significant negative low and moderate correlations were found between GA and the Ar'-Go, MaF-Go, RW, and RD variables, whereas significant positive low correlation was found between GA and the RA variable. Within the limits of this study, the analysis of the mandibular ramus morphometry on DPRs in terms of GA size and gender was found to be useful for devising a highly predictive and strategic plan for implant-supported oral rehabilitation.

Probing Copper and Copper-Gold Alloy Surfaces with Space-Quantized Oxygen Molecular Beam.

The orientation and motion of reactants play important roles in reactions. The small rotational excitations involved render the reactants susceptible to dynamical steering, making direct comparison between experiments and theory rather challenging. Using space-quantized molecular beams, we directly probed the (polar and azimuthal) orientation dependence of O2 chemisorption on Cu(110) and Cu3Au(110). We observed polar and azimuthal anisotropies on both surfaces. Chemisorption proceeded rather favorably with the O-O bond axis oriented parallel (vs perpendicular) to the surface and rather favorably with the O-O bond axis oriented along [001] (vs along [1̅10]). The presence of Au hindered the surface from further oxidation, introducing a higher activation barrier to chemisorption and rendering an almost negligible azimuthal anisotropy. The presence of Au also prevented the cartwheel-like rotations of O2.

Kinetics and dynamics in physisorption of CH3Cl on HOPG: surface temperature and molecular orientation dependence.

We report a study of kinetics and dynamics in physisorption of CH(3)Cl on a highly-oriented pyrolytic graphite (HOPG). Thermal energy atom scattering (TEAS) was used to probe the kinetics of thermal CH(3)Cl adsorption on HOPG during the coverage evolution. The desorption energy of CH(3)Cl on HOPG changes from 0.25 to 0.30 eV with increasing surface coverage, suggesting the attractive interaction between CH(3)Cl molecules on the surface. On the other hand, the oriented molecular beam scattering was used to monitor the dynamical interaction of CH(3)Cl with HOPG at zero coverage, demonstrating that the CH(3)Cl scattering intensity depends on the molecular orientation of the incident CH(3)Cl. The observed steric preference is not sensitive to the surface temperature. These results suggest that the moderate anisotropy in the interaction potential induces the molecular-orientation dependence of energy dissipation during the transient trapping into the physisorption well.

Revisit of XPS Studies of Supersonic O2 Molecular Adsorption on Cu(111): Copper Oxides.

We report the X-ray photoemission spectroscopy (XPS) characterization of the bulk Cu2O(111) surface and "8" and "29" oxide structures on Cu(111) prepared using a 0.5 eV O2 supersonic molecular beam. We propose a new structural model for the "8" oxide structure and also confirm the previously proposed model for the "29" oxide structure on Cu(111), based on the O 1s XPS spectra. The detection angle dependence of the O 1s spectra supports that the nanopyramidal model is more preferable for the (√3 × âˆš3)R30° Cu2O(111). We also report electronic excitations that O 1s electrons suffer.

Interface atom mobility and charge transfer effects on CuO and Cu2O formation on Cu3Pd(111) and Cu3Pt(111).

We bombarded [Formula: see text] and [Formula: see text] with a 2.3 eV hyperthermal oxygen molecular beam (HOMB) source, and characterized the corresponding (oxide) surfaces with synchrotron-radiation X-ray photoemission spectroscopy (SR-XPS). At [Formula: see text], CuO forms on both [Formula: see text] and [Formula: see text]. When we increase the surface temperature to [Formula: see text], [Formula: see text] also forms on [Formula: see text], but not on [Formula: see text]. For comparison, [Formula: see text] forms even at [Formula: see text] on Cu(111). On [Formula: see text], [Formula: see text] forms only after [Formula: see text], and no oxides can be found at [Formula: see text]. We ascribe this difference in Cu oxide formation to the mobility of the interfacial species (Cu/Pd/Pt) and charge transfer between the surface Cu oxides and subsurface species (Cu/Pd/Pt).

Steric effects in the scattering of oriented CH3Cl molecular beam from a Si(111) surface.

We report results of a study on steric effects appearing in the scattering of an oriented CH(3)Cl molecular beam from Si(111) at surface temperatures > or = 300 K. Data presented here show that the scattered CH(3)Cl beam intensity measured at fixed scattering angles clearly depends on the initial molecular (CH(3)Cl) orientation toward the Si surface. The scattered CH(3)Cl beam intensity for the CH(3)-end collision is larger than that for the Cl-end collision, suggesting that strong anisotropy of the interaction potential induces the molecular-orientation-dependent energy dissipation during transient trapping into a shallow potential well.

Adsorption of Acetonitrile on Si(111)-(7 × 7).

The adsorption of acetonitrile (CH3CN) on Si(111)-(7 × 7) at a room temperature has been investigated using scanning tunneling microscopy (STM) and first-principles calculations. The site-specific information on adsorption enables us to understand the site-by-site and step-by-step adsorption mechanism. From theoretical simulations, the most stable configuration of CH3CN on Si(111)-(7 × 7) is found to be a molecularly chemisorbed CH3CN with the carbon and nitrogen atoms of CN bonded to the rest atom and adatom on the Si surface, respectively. Some chemisorption-induced features in the STM topographic image are assigned based on the theoretical calculations.

Steric effects in the scattering of oriented CH3Cl molecular beam from a graphite surface: weak interaction of physisorption.

We report results of a study on steric effects appearing in the scattering of an oriented CH(3)Cl molecular beam from highly oriented pyrolytic graphite (HOPG) surface at 300 K. Data presented here show that the scattered CH(3)Cl beam intensity measured at a fixed scattering angle clearly depends on the initial molecular orientation toward the HOPG surface. The scattered CH(3)Cl beam intensity for the CH(3)-end collision is larger than that for the Cl-end collision, suggesting that strong anisotropy of the interaction potential induces the molecular-orientation-dependent energy dissipation during transient trapping into the physisorption well.

Kinetics of oxygen adsorption and initial oxidation on Cu(110) by hyperthermal oxygen molecular beams.

Oxygen adsorption and subsequent oxide formation on Cu(110) using a hyperthermal oxygen molecular beam (HOMB) were investigated using X-ray photoelectron spectrometry. The O-uptake curves, which were determined from the evolution of the O-1s peaks, indicate that simple Langmuir type kinetics can describe dissociative adsorption of O(2) with an incident energy (E(i)) below 0.5 eV under Theta < or = 0.5 ML. The reaction order dependence on E(i) implies two competing dissociation mechanisms, trapping-mediated and directly activated adsorption. Oxidation at Theta > or = 0.5 ML proceeds rather effectively using highly energetic HOMB at E(i) > or = 1.0 eV. The azimuthal dependence of the sticking probability during the effective oxidation using HOMB incidence suggests that the added rows, which consist of the Cu-O structure, shade the reactive hollow sites in the trough where oxygen penetrates into the subsurface. The surface Cu(2)O formed with highly energetic HOMB incidence decomposes with desorbing subsurface oxygen even at room temperature, demonstrating that HOMB can induce a metastable surface structure that cannot be produced in the thermal equilibrium process.

Quantitative Multilayer Cu(410) Structure and Relaxation Determined by QLEED.

Industrially relevant catalytically active surfaces exhibit defects. These defects serve as active sites; expose incoming adsorbates to both high and low coordinated surface atoms; determine morphology, reactivity, energetics, and surface relaxation. These, in turn, affect crystal growth, oxidation, catalysis, and corrosion. Systematic experimental analyses of such surface defects pose challenges, esp., when they do not exhibit order. High Miller index surfaces can provide access to these features and information, albeit indirectly. Here, we show that with quantitative low-energy electron diffraction (QLEED) intensity analyses and density functional theory (DFT) calculations, we can visualize the local atomic configuration, the corresponding electron distribution, and local reactivity. The QLEED-determined Cu(410) structure (Pendry reliability factor RP ≃ 0.0797) exhibits alternating sequences of expansion (+) and contraction (-) (of the first 16 atomic interlayers) relative to the bulk-truncated interlayer spacing of ca. 0.437 Å. The corresponding electron distribution shows smoothening relative to the bulk-determined structure. These results should aid us to further gain an atomic-scale understanding of the nature of defects in materials.

High-resolution electron energy loss spectroscopy study of O-Cu(410).

We have investigated oxygen adsorption on Cu(410) by high-resolution electron energy loss spectroscopy, dosing O2 with a supersonic molecular beam at different surface temperatures and for different angles of incidence and beam energies or by backfilling. In the investigated crystal temperature range (127 < T < 570 K), adsorption is always dissociative. Depending on T, impact energy, and angle of incidence, the oxygen atoms end up in different adsorption configurations, characterized by different vibrational signatures. In particular, at grazing incidence when only the step edge is exposed to O2, the adatoms end up initially preferentially at the step edge. An ordered overlayer forms at half monolayer coverage when the adsorbate is mobile. Oxide patches develop eventually for large exposures performed by backfilling and at high crystal temperature.