ZnO nanomaterials with controlled size, shape and surface chemistry are required for applications in diverse areas, such as optoelectronics, photocatalysis, biomedicine and so on. Here, we report on ZnO nanostructures with rod-like and spherical shapes prepared via laser ablation in liquid using a laser with millisecond-long pulses. By changing laser parameters (such as pulse width and peak power), the size or aspect ratio of such nanostructures could be tuned. The surface chemistry and defects of the products were also strongly affected by applied laser conditions. The preparation of different structures is explained by the intense heating of liquid media caused by millisecond-long pulses and secondary irradiation of already-formed nanostructures.

Abstract. The work analyzes the anti-icing performance of flat aluminum surfaces coated with widely used alkyl-group based layers of octadecyltrimethoxysilane, fluorinated alkylsilane and stearic acid as they are subjected to repeated icing/deicing cycles. The wetting properties of the samples upon long-term immersion in water are also evaluated. The results demonstrate that smooth aluminum surfaces grafted with alkyl groups are prone to gradual degradation of their hydrophobic and icephobic properties, which is caused by interaction and reactions with both ice and liquid water. This implies that alkyl-group based monolayers on aluminum surfaces are not likely to be durable icephobic coatings unless their durability in contact with ice and/or water is significantly improved.

The effect of atmospheric gases on the ionization energy (I) of titanyl phthalocyanine thin film was investigated by an apparatus of photoemission yield spectroscopy developed for the measurements of I for the same specimen both in vacuum and under gaseous atmosphere. It was found that the value of I is affected by the exposure to various ambient gases (i.e., air, nitrogen, and oxygen of 1 atm, and water vapor corresponding to 27% relative humidity at 300 K), and that the effect strongly depends on the gas. The ionization energies in vacuum could be determined as the onset I0 of the cube-root plot of the photoemission yield as a function of photon energy. When the sample was exposed to gases, the cube-root plot still gives an onset, but often a long tail at the low-energy side with another onset It was also observed. The first exposure to air did not affect both I0 and It much, while the following evacuation-exposure cycles caused mostly reversible decrease and increase of I0 and It by about 0.2 and 0.4 eV, respectively. Among the examined constituent gases of air, nitrogen was found to hardly affect both I0 and It except for the small temporal decrease by 0.06 eV at the first exposure. Similar trends of the change of I0 and It with those for air were found for oxygen, with the amplitudes of mostly reversible change being 0.1 eV for I0 and 0.2 eV for It. Overlapped with these changes, a slow decrease of both I0 and It, was also observed with a slope of 0.01 eV per day. For water, the trends were mostly similar with O2, except that (1) the first exposure to water vapor showed small and large changes in I0 (0.03 eV increase) and It (0.4 eV decrease) and (2) the amplitudes of the mostly reversible change of I0 (0.3 eV) and It (0.05 eV) were much larger and smaller than those for O2, respectively. A long-term decrease was also observed with a slope of 0.04 eV per day. These results indicate that the atmospheric effect by ambient air on I is mainly caused by water vapor, although oxygen also makes significant contribution. Since the observed trends are rather complex, there seem to be multiple factors affecting I, which is the energy difference between the vacuum level and the highest occupied molecular orbita. Possible microscopic mechanisms of the observed variation of I on these levels are also discussed in terms of the energy change in these levels.

Biological applications where nanoparticles are used in a cell environment with laser irradiation are rapidly emerging. Investigation of the localized heating effect due to the laser irradiation on the particle is required to preclude unintended thermal effects. While bulk temperature rise can be determined using macroscale measurement methods, observation of the actual temperature within the nanoscale domain around the particle is difficult and here we propose a method to measure the local temperature around a single gold nanoparticle in liquid, using white light scattering spectroscopy. Using 40-nm-diameter gold nanoparticles coated with thermo-responsive polymer, we monitored the localized heating effect through the plasmon peak shift. The shift occurs due to the temperature-dependent refractive index change in surrounding polymer medium. The results indicate that the particle experiences a temperature rise of around 10 degrees Celsius when irradiated with tightly focused irradiation of ~1 mW at 532 nm.

We report plasmonic nanoparticle enhanced photocatalysis on titanium dioxide (TiO 2) in the deep-UV range. Aluminum (Al) nanoparticles fabricated on TiO 2 film increases the reaction rate of photocatalysis by factors as high as 14 under UV irradiation in the range of 260-340 nm. The reaction efficiency has been determined by measuring the decolorization rate of methylene blue applied on the TiO 2 substrate. The enhancement of photocatalysis shows particle size and excitation wavelength dependence, which can be explained by the surface plasmon resonance of Al nanoparticles. V

The dielectric constant of indium in the deepultraviolet (DUV) region satisfies the conditions for localized surface plasmon resonance with low absorption loss. We report that indium acts as an agent of efficient surface-enhanced resonance Raman scattering (SERRS) in the DUV. Indium-coated SERRS substrates were prepared by depositing indium on fused silica glass substrates with control of the deposition thickness to tailor the plasmon resonance in the DUV. With excitation at 266 nm, SERRS was observed from thin adenine films deposited on the indiumcoated substrates, and the signal intensity was up to 11 times higher than that of a bare fused silica glass substrate. FDTD calculations showed that an enhanced electromagnetic field can be locally generated on the indium-coated substrates. Considering the volume of the enhanced field region in the excitation spot, we estimated the average enhancement factor to be 10 2 or higher. Our results indicate that indium is a promising and easy-to-use metal for efficiently exciting DUV-SERRS of samples containing a small number of molecules. KEYWORDS: indium, surface-enhanced resonance Raman scattering, localized surface plasmon resonances, deep-ultraviolet S urface-enhanced Raman scattering (SERS) is useful for label-free, nondestructive detection and analysis of samples containing a small number of molecules, 1−3 even single molecules. 4,5 Since its discovery in 1974, 6 SERS research has resulted in a large number of papers, exceeding 11 000, 7 mostly related to visible or near-infrared (NIR) light excitation. Recently, small but growing efforts have been made to extend SERS to the deep-ultraviolet (DUV) region. DUV excitation makes SERS more powerful for high S/N measurement of a small number of molecules. The advantages of DUV excitation are notable when measuring aromatic compounds such as nucleotide bases 8 and aromatic amino acid residues, 9 which are essential in biology. The scattering efficiency of these molecules is up to 10 6 times higher with DUV excitation compared with visible and NIR excitation 10 due to the resonance Raman effect. Additionally, DUV excitation can be used to distinguish Raman bands from native fluorescence of a sample in a spectrum. 11Furthermore, since the light-scattering efficiency is inversely proportional to the fourth power of the wavelength, DUV excitation can give a 10−100 times stronger Raman scattering signal from any off-resonance molecule than visible and NIR excitation can.Resonance excitation of localized surface plasmon polaritons (LSPPs) in metals is required for SERS.12−15 Silver and gold, metals commonly used for SERS, cannot support the excitation of LSPPs in the DUV. 16 To extend SERS to the DUV, it is essential to explore DUV plasmonic metals, in which surface plasmons are resonantly excited by DUV light. So far, aluminum is recognized as the only reliable and efficient DUV plasmonic metal.16−32 The usefulness of aluminum as a medium of LSPPs in the DUV was first demonstrated in 2007 via extraordinary optical tran...

The effect of liquid medium and its pressure on the photoluminescence of ZnO nanoparticles prepared via laser ablation of Zn targets in various water-ethanol mixtures is studied. As the ethanol content increases, the photoluminescence of the product changes, while metallic zinc is observed to emerge in nanomaterials prepared in ethanol-rich environments. The applied pressure had a less profound effect, mainly affecting materials produced in water or water-ethanol, and much less those generated in pressurized ethanol. Tuning the reactivity of the liquid and pressurizing it during laser ablation is demonstrated to be promising for tailoring the emission properties of the product.

Platelet adhesion to vascular subendothelium, mediated in part by interactions between collagen and glycoprotein VI (GPVI) complexed with Fc receptor γ-chain, is crucial for thrombus formation. Antiplatelet therapy benefits patients with various thrombotic and ischemic diseases, but the safety and efficacy of existing treatments are limited. Recent data suggest GPVI as a promising target for a novel antiplatelet therapy, for example, GPVI-specific Abs that deplete GPVI from the surface of platelets. Here, we characterized GPVI-specific autoAbs (YA-Abs) from the first reported patient with ongoing platelet GPVI deficiency caused by the YA-Abs. To obtain experimentally useful human GPVI-specific mAbs with characteristics similar to YA-Abs, we generated human GPVI-specific mouse mAbs and selected 2 representative mAbs, mF1201 and mF1232, whose binding to GPVI was inhibited by YA-Abs. In vitro, mF1201, but not mF1232, induced human platelet activation and GPVI shedding, and mF1232 inhibited collagen-induced human platelet aggregation. Administration of mF1201 and mF1232 to monkeys caused GPVI immunodepletion with and without both significant thrombocytopenia and GPVI shedding, respectively. When a human/mouse chimeric form of mF1232 (cF1232) was labeled with a fluorescent endocytosis probe and administered to monkeys, fluorescence increased in circulating platelets and surface GPVI was lost. Loss of platelet surface GPVI mediated by cF1232 was successfully reproduced in vitro in the presence of a cAMP-elevating agent. Thus, we have characterized cAMP-dependent endocytosis of GPVI mediated by a human GPVI-specific mAb as what we believe to be a novel antiplatelet therapy.