Search

The liquid-phase chemical kinetics of a cell culture basal medium during treatment by an argon-fed, non-equilibrium atmospheric-pressure plasma source were investigated using real-time ultraviolet absorption spectroscopy and colorimetric assays. Depth- and time-resolved NO2− and NO3− concentrations were strongly inhomogeneous and primarily driven by convection during and after plasma–liquid interactions. H2O2 concentrations determined from deconvolved optical depth spectra were found to compensate for the optical depth spectra of excluded reactive species and changes in dissolved gas content. Plasma-activated media remained weakly basic due to NaHCO3 buffering, preventing the H+-catalyzed decomposition of NO2− seen in acidic plasma-activated water. An initial increase in pH may indicate CO2 sparging. Furthermore, the pH-dependency of UV optical depth spectra illustrated the need for pH compensation in the fitting of optical depth data.

A systematic study on the structure and stability of zinc doped gold clusters has been performed by density functional theory calculations. All the lowest-energy isomers found have a planar structure and resemble pure gold clusters in shape. Stable isomers tend to equally delocalize valence s electrons of the constituent atoms over the entire structure and maximize the number of Au–Zn bonds in the structure. This is because the Au–Zn bond is stronger than the Au–Au bond and gives an extra σ-bonding interaction by the overlap between vacant Zn 4p and valence Au 6s(5d) orbitals. No three-dimensional isomers were found for Au5Zn+ and Au4Zn clusters containing six delocalized valence electrons. This result reflects that these clusters have a magic number of delocalized electrons for two-dimensional systems. Calculated vertical ionization energies and dissociation energies as a function of the cluster size show odd–even behavior, in agreement with recent mass spectrometric observations [Tanaka et al., J. Am. C...

We report the measurement of the photoabsorption spectrum of Li3O using resonance-enhanced two-photon ionization spectroscopy in the energy range between 0.7 and 2.75 eV. Ab initio geometry optimization calculations at the CCSD(T)/6-311+G(d) level of theory are carried out, resulting in a stable D3h ground state symmetry for Li3O. Vertical excitation energies are computed from the CCSD(T) potential, and the flatness of the potential energy surface is analyzed. A comparison of the recorded absorption spectrum with the theoretical predictions allows an assignment of all the observed bands and excited states in terms of a D3h ground state structure. It is argued that the width of the bands is governed by the flat-bottomed shape of the potential energy surface.

High-quality epitaxial thin films of Co-doped anatase TiO 2 ~Co:TiO2) were grown epitaxially on SrTiO3 ~001! substrates by using pulsed laser deposition with in-situ reflection high-energy electron diffraction. The oxygen partial pressure, PO2, during the growth was systematically varied. As PO2 decreased, the growth behavior altered from a two-dimensional layer-by-layer-like growth to a three-dimensional island-like pattern. Electrical conductivity and saturation magnetization increased, seemingly consistent with the picture of carrier-induced ferromagnetism. However, we also found that the spatial distribution of Co ions became highly nonuniform and the chemical state of Co ions changed from ionic to metallic. All of these PO2 dependences, even including the transport and the magnetic properties, can be explained in terms of the formation of cobalt clusters, whose existence was clearly demonstrated by transmission‐electron‐microscope studies. Our work clearly indicates that the cobalt clustering will result in the room-temperature ferromagnetism observed in our Co:TiO2 films. To check the possible spin polarization of carriers in Co:TiO2 films, we also fabricated a heterojunction composed of a ferromagnetic Co:TiO2, an insulating SrTiO3, and a ferromagnetic half-metallic ~La,Ba!MnO3 layer. When the magnetic field was varied, we could not observe any changes in its I‐V characteristic curves, which suggests that there might be little spin-polarization effect in the anatase Co:TiO 2 layer. © 2003 American Institute of Physics. @DOI: 10.1063/1.1568524#

Oxalate was synthesized in the glucose solution by irradiation with non-equilibrium atmospheric pressure plasma (NEAPP), in which the NEAPP plume contacted the solution surface, via the generation of several intermediate organic products such as gluconic acid. A thermodynamically unstable phase of calcium oxalate dihydrate crystallized rapidly during incubation of a NEAPP-irradiated glucose solution that contained calcium ions and was buffered at neutral pH. Longer irradiation times increased the growth rate and the number of seed crystals.

Density functional theory (DFT) calculations at the Becke three parameter hybrid functional with the Lee–Yang–Parr nonlocal correlation functional (B3LYP)/6-311+G(d,p) level are performed to study the stability and structures of lithium-excess lithium hydroxide clusters Lin(OH)n−1 (n=2–5). These small clusters are stable toward the dissociation to liberate one lithium atom and each of the clusters has structural isomers differing in the stability. The result of calculations implies that the most stable isomer of the clusters with n=2 and 3 have a “hyperlithiated” electronic structure, in which the excess electron fully delocalizes over all of the lithium atoms in the cluster, while the most stable isomer of the clusters with n=4 and 5 in which the excess electron localizes on a specific site has a “segregated” electronic structure composed of the metallic and ionic parts. Vertical ionization energies of the isomers of these clusters calculated by ab initio MO theory at the coupled cluster singles and doub...

Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

Two independent ovarian cancer cell lines and fibroblast controls were treated with nonequilibrium atmospheric pressure plasma (NEAPP). Most ovarian cancer cells were detached from the culture dish by continuous plasma treatment to a single spot on the dish. Next, the plasma source was applied over the whole dish using a robot arm. In vitro cell proliferation assays showed that plasma treatments significantly decreased proliferation rates of ovarian cancer cells compared to fibroblast cells. Flow cytometry and western blot analysis showed that plasma treatment of ovarian cancer cells induced apoptosis. NEAPP could be a promising tool for therapy for ovarian cancers.

Ionization efficiency curves (IECs) were measured for Lin(OH)n−1 (n=2–5) clusters generated by reactions of laser-ablated lithium metal with water vapor, using photoionization time-of-flight mass spectrometry. The measured IECs are well-reproduced with a simulation involving Franck–Condon factors, enabling to identify the global-minimum structure of the clusters predicted in our theoretical study [Tanaka et al., J. Chem. Phys. 113, 1821 (2000)]. Hyperlithiated structures (HLS), in which an excess electron is delocalized, are identified for the cluster with n=2 and 3, while electron-localized or segregated structure (ELS) are for those with n=3–5. Adiabatic ionization energies were determined as 4.053±0.003 eV for HLS of Li2OH, 3.687±0.003 eV for HLS of Li3(OH)2, 4.133±0.003 eV for ELS of Li3(OH)2, and 3.418±0.009 eV for ELS of Li4(OH)3. The ionization energy of Li5(OH)4 was determined as 3.60±0.11 eV by a linear extrapolation of IEC. For Li3(OH)2, the energetics of two lowest-energy isomers is discussed b...