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In vivo multiplexed imaging aims for noninvasive monitoring of tumors with multiple channels without excision of the tissue. While most of the preclinical imaging has provided a number of multiplexing channels up to three, Raman imaging with surface-enhanced Raman scattering (SERS) nanoparticles was suggested to offer higher multiplexing capability originating from their narrow spectral width. However, in vivo multiplexed SERS imaging is still in its infancy for multichannel visualization of tumors, which require both sufficient multiplicity and high sensitivity concurrently. Here we create multispectral palettes of gold multicore-near-infrared (NIR) resonant Raman dyes-silica shell SERS (NIR-SERRS) nanoparticle oligomers and demonstrate noninvasive and five-plex SERS imaging of the nanoparticle accumulation in tumors of living mice. We perform the five-plex ratiometric imaging of tumors by varying the administered ratio of the nanoparticles, which simulates the detection of multiple biomarkers with different expression levels in the tumor environment. Furthermore, since this method does not require the excision of tumor tissues at the imaging condition, we perform noninvasive and longitudinal imaging of the five-color nanoparticles in the tumors, which is not feasible with current ex vivo multiplexed tissue analysis platforms. Our work surpasses the multiplicity limit of previous preclinical tumor imaging methods while keeping enough sensitivity for tumor-targeted in vivo imaging and could enable the noninvasive assessment of multiple biological targets within the tumor microenvironment in living subjects.

CuInS2 (CIS) quantum dots (QDs) would be attractive alternatives to the widely-investigated QDs containing toxic elements when the quantum yield (QY) of CIS QDs becomes comparable to that of typica...

CuInS2 (CIS) nanoparticles would be attractive alternatives to replace toxic elements in widely investigated nanoparticles, when the optical properties such as the broad absorption and the luminesc...

Low-temperature Cu-Cu bonding technology plays a key role in high-density and high-performance 3D interconnects. Despite the advantages of good electrical and thermal conductivity and the potential for fine pitch patterns, Cu bonding is vulnerable to oxidation and the high temperature of the bonding process. In this study, chip-level Cu bonding using an Ag nanofilm at 150 °C and 180 °C was studied in air, and the effect of the Ag nanofilm was investigated. A 15-nm Ag nanofilm prevented Cu oxidation prior to the Cu bonding process in air. In the bonding process, Cu diffused rapidly to the bonding interface and pure Cu-Cu bonding occurred. However, some Ag was observed at the bonding interface due to the short bonding time of 30 min in the absence of annealing. The shear strength of the Cu/Ag-Ag/Cu bonding interface was measured to be about 23.27 MPa, with some Ag remaining at the interface. This study demonstrated the good bonding quality of Cu bonding using an Ag nanofilm at 150 °C.

Optical confinement effects are investigated in InGaN/GaN axial-heterostructure nanolasers. Cylindrical nanorods with GaN/InGaN/GaN structures are prepared using combined processes of top-down and bottom-up approaches. The lasing of InGaN is observed at a low threshold (1 μJ cm-2), which is attributed to an efficient carrier transfer process from GaN to InGaN. The lasing of GaN is also found in the threshold range of 10-20 μJ cm-2 with a superlinear increase in emission intensity and high quality factors (Q = 1000), implying that dual wavelengths of lasing are tunable as a function of excitation intensity. The non-classical Fabry-Pérot modes suggest strong light-matter interactions in nanorods by optical confinement effects. The polarization of lasing indicates that the non-classical modes are in the identical transverse mode, which supports the formation of exciton-polaritons in nanorods. Polariton lasing in a single axial-heterostructure nanorod is observed for the first time, which proposes small-sized light sources with low threshold, polarized light, and tunable wavelengths in a single nanorod.

Nano/micro particles are considered to be the most valuable and important functional materials in the field of materials science and engineering [...]

Overlimiting current (OLC) through electrolytes interfaced with perm-selective membranes has been extensively researched for understanding fundamental nano-electrokinetics and developing efficient engineering applications. This work studies how a network of microchannels in a nonuniform array, which mimics a natural pore configuration, can contribute to OLC. Here, micro/nanofluidic devices are fabricated with arrays of parallel microchannels with nonuniform size distributions, which are faced with a perm-selective membrane. All cases maintain the same surface and bulk conduction to allow probing of the sensitivity only by the nonuniformity. Rigorous experimental and theoretical investigation demonstrates that overlimiting conductance has a maximum value depending on the nonuniformity. Furthermore

Quantum dots (QDs) are semiconductor nanoparticles with outstanding optoelectronic properties. More specifically, QDs are highly bright and exhibit wide absorption spectra, narrow light bands, and excellent photovoltaic stability, which make them useful in bioscience and medicine, particularly for sensing, optical imaging, cell separation, and diagnosis. In general, QDs are stabilized using a hydrophobic ligand during synthesis, and thus their hydrophobic surfaces must undergo hydrophilic modification if the QDs are to be used in bioapplications. Silica-coating is one of the most effective methods for overcoming the disadvantages of QDs, owing to silica’s physicochemical stability, nontoxicity, and excellent bioavailability. This review highlights recent progress in the design, preparation, and application of silica-coated QDs and presents an overview of the major challenges and prospects of their application.

The surface-enhanced Raman scattering (SERS) technique, that uses magnetic plasmonic particles (MPPs), is an advanced SERS detection platform owing to the synergetic effects of the particles’ magnetic and plasmonic properties. As well as being an ultrasensitive and reliable SERS material, MPPs perform various functions, such as aiding in separation, drug delivery, and acting as a therapeutic material. This literature discusses the structure and multifunctionality of MPPs, which has enabled the novel application of MPPs to various biological fields.

The size-dependent band-gap energies of AgIn5S8 nanoparticles were directly measured for the first time using absorption and photoluminescence spectroscopies, which enabled an explanation of the evolution of the band-gap energy with the quantum-confinement effect in AgIn5S8 nanoparticles. The band-gap transition in steady-state and time-resolved photoluminescence spectra indicated that the stable structure of the AgIn5S8 nanoparticles was the cubic phase. The electronic band structures of the Ag–In–S nanoparticles were mainly related to the crystal structures, although the stoichiometry affected the band energies to some extent. Zn doping led to the formation of a ZnS–AgIn5S8 solid solution, as supported by the significant changes in the electronic band structures of the AgIn5S8 nanoparticles. Controlling the size and stoichiometry allowed the emission of the Ag–In–S nanoparticles to be tuned in the entire visible regime.

The photoluminescence of AgIn5S8 nanoparticles was examined to clarify the emissive relaxation processes of defect states and to explain the highly efficient photoluminescence of defect states. The large Stokes shift of the defect emission was explained by strong electron-phonon coupling in the nanoparticles. Steady-state and time-resolved photoluminescence spectroscopy indicated two emissive defect states with characteristic emission energies and lifetimes. Change of the surface-to-volume ratio in the nanoparticles affected the relative contribution of the two states, implying that defect emission in higher energy was attributable to surface-related defects. The defect emission in lower energy was attributable to intrinsic defects, which were also present in bulk. The quantum yield of the surface defects was larger than that of the intrinsic defects, which accounted for the unusually high quantum yield of AgIn5S8 nanoparticles, although the origin of emission was the defect states, not the exciton recombination found in typical semiconductor nanoparticles.

Photocatalytic CO2 conversion to fuel offers an exciting prospect for solar energy storage and transportation thereof. Several photocatalysts have been employed for CO2 photoreduction; the challenge of realizing a low-cost, readily synthesized photocorrosion-stable photocatalytic material that absorbs and successfully utilizes a broad portion of the solar spectrum energy is as yet unmet. Herein, a mesoporous p-type/n-type heterojunction material, CuxO–TiO2 (x = 1, 2), is synthesized via annealing of Cu/Cu2O nanocomposites mixed with a TiO2 precursor (TiCl4). Such an experimental approach in which two materials of diverse bandgaps are coupled provides a simultaneous opportunity for greater light absorption and rapid charge separation because of the intrinsic p–n heterojunction nature of the material. As detailed herein, this heterostructured photocatalyst demonstrates an improved photocatalytic activity. With the CO2 reduction of our optimal sample (augmented light absorption, efficacious charge separation...

Carbon nanotube (CNT) membranes are considered as next-generation membranes for desalination. Among the various types of CNT membranes, vertically aligned (VA) CNT membranes provide rapid water transport. However, when the water permeability of VA CNT membranes are compared with those of the commercial membrane, the VA CNT membranes only showed slightly higher water permeability due to their low pore densities. Additionally, the applicability of VA CNT membranes for desalination has been limited due to their larger pore sizes. Herein, we improved VA CNT membranes in terms of the desalination potential, flux enhancement, and scale-up. For the desalination potential, graphene oxide (GO) or polyamide (PA) were coated on a VA CNT membrane as a selective layer, which showed approximately 40–65% NaCl rejection, respectively. A pretreatment polyelectrolyte coating for a GO-coated VA CNT membrane increased the water permeability by approximately 50%. For the flux enhancement, the water permeability of a V...

SnO 2 thin films were deposited on fused silica substrate by pulsed laser deposition under transverse magnetic field. We have explored the effects of magnetic field and ablation laser wavelength on the optical properties of laser-induced plasma plume and structural characteristics of the deposited SnO 2 films. Optical emission from the plume was monitored using an optical fiber to examine the influence of magnetic field on the population of the excited neutral and ionic species and their decay with times after laser ablation. Also, we employed photoluminescence, x-ray diffraction, and UV-Vis absorption to characterize SnO 2 films. SnO 2 is n-type semiconducting material with a wide bandgap of 3.6 eV at room temperature. Since SnO 2 has high transparency in visible region and electric conductivity, it has diverse applications in gas sensors, solar cells, transparent conducting electrodes, and optoelectronic devices

As water quality regulations have tightened, many studies to improve wastewater treatment efficiency have been performed. In this study, magnetite powder was used to maintain a high concentration of MLSS in lab-scale wastewater treatment system. After magnetite powder injection, MLSS concentration was above 8,000 mg/L and it was 3.2 times higher than control group(2,500 mg/L). In addition, nitrogen removal efficiency and phosphorus removal efficiency comparing with the control group was increased 20.5% and 11%, respectively.

We report on the fabrication of patterned flexible graphene devices via a facile direct transfer of bi-layer graphene grown on alumina (Al2O3) substrate, and the use of Ag nanowire stickers as flexible electrodes. Patterned polydimethylsiloxane (PDMS) stamps coated with vaporized dimethylformamide (DMF) are utilized to transfer as-grown graphene directly onto a flexible polyethylene terephthalate (PET) substrate. The facile direct transfer is attributed to the enhanced adhesion of the bi-layer graphene to PDMS, due to DMF-coating, as well as the weak adhesion between the bi-layer graphene and the Al2O3 substrate. In this way, flexible patterned graphene devices have been fabricated with Ag nanowire stickers as electrodes. Stable electrical conduction characteristics were measured over repetitive bending with a bending radius down to 5 mm.

We report on the facile fabrication of an all-solid-state flexible planar-type micro-supercapacitor (MSC) array with micropatterned hybrid electrodes of graphene foam (GF)/COOH-functionalized multi-walled nanotubes (MWNT-COOH)/MnOx and its application as a power source to operate various micro-light emitting diodes ( μ -LEDs) and a SnO2 nanowire (NW) UV sensor. Composite electrodes of GF/MWNT-COOH/MnOx were simply micropatterned via reactive ion etching (RIE) with a metal mask, and used as current collectors as well as active materials. Polyvinyl alcohol-H3PO4 was used as the solid-state electrolyte. The use of the composite film electrodes increased the area specific capacitance ∼11 times compared to the MSC with just patterned GF electrodes. After 104 charge/discharge cycles, 89.5% of the initial capacitance was maintained. Furthermore, very stable performance was observed over 103 bending of the whole MSC on a polyethersulfone substrate with capacitance retention of 95.5%. For the first time, we could directly measure the UV-induced photocurrent through a SnO2 NW sensor powered by 4 MSCs connected in parallel. Fast response to UV pulses was detected for a time of more than 10 min. This work demonstrates the high application potential of our MSCs using patterned electrodes of GF/MWNT-COOH/MnOx to self-powered flexible electronic devices including NW-based sensors.

AgInS2 nanoparticles of various sizes were synthesized over a range of reaction temperature from 120 to 180 °C. The band gap energies, obtained directly from photoluminescence spectra for the first time, were well correlated to the quantum confinement effects as a function of nanoparticle size, because the band gap shift was explained by the finite-depth-well effective mass approximation. The chalcopyrite and orthorhombic phases were observed to coexist in the AgInS2 nanoparticles, although the relative population of each phase depended on the reaction temperature and time. The band gap shift of each phase was comparable, which revealed that the size was the major determinant of the change in the band gap energy. The photodynamics of the band gap states exhibited emission-wavelength dependence, which further supported the coexistence of the two phases. The contributions of each phase in the time profiles matched the relative population of each phase observed in the steady-state photoluminescence spectra.

The photophysical properties of CuInxGa1-xS2 (CIGS) thin films, prepared by solution-based coating methods, are investigated to understand the correlation between the optical properties of these films and the electrical characteristics of solar cells fabricated using these films. Photophysical properties, such as the depth-dependent band gap and carrier lifetime, turn out to be at play in determining the energy conversion efficiency of solar cells. A double grading of the band gap in CIGS films enhances solar cell efficiency, even when defect states disturb carrier collection by non-radiative decay. The combinational stacking of different density films leads to improved solar cell performance as well as efficient fabrication because a graded band gap and reduced shunt current increase carrier collection efficiency. The photodynamics of minority-carriers suggests that the suppression of defect states is a primary area of improvement in CIGS thin films prepared by solution-based methods.

In the current work, stable prenucleated PbS quantum dots (QDs) with a sub-nanometer (0.8 nm) size have been successfully synthesized via a systematically designed experiment. A detailed analysis of critical nucleation, growth, and stability for such ultrasmall prenucleated clusters is done. The experimental strategy is based on controlled concentration, temperature and injection of respective precursors, thus enabling us to control nucleation rate and separation of stable sub-nanometer PbS QDs with size 0.8 nm. Significantly, by providing additional thermal energy to sub-nanometer PbS QDs, we achieved the fully nucleated cubic crystalline structure of PbS with size of around 1.5 nm. The size and composition of the prenucleated QDs are investigated by sophisticated tools like X-ray photoelectron spectroscopy (XPS) and medium energy ion scattering (MEIS) spectroscopy which confirms the synthesis of PbS with Pb2+ rich surface while the UV-Vis spectroscopy and X-ray diffraction (XRD) data suggests an alternative crystallization path. Non-classical nucleation theory is employed to substantiate the growth mechanism of prenucleated PbS QDs.

Direct contact membrane distillation (DCMD) is a membrane distillation (MD) configuration where feed and distillate directly contact with a hydrophobic membrane. Depending on its operating conditions, the hydraulic pressures of the feed and distillate may be different, leading to adverse effects on the performance of the DCMD process. Nevertheless, little information is available on how hydraulic pressure affects the efficiency of DCMD. Accordingly, this paper investigates the effect of external hydraulic pressure on the process efficiency of DCMD. Gas permeabilities of MD membranes were measured to analyze the effect of membrane compaction by external pressure. Mass transfer coefficients were calculated using experimental data to quantitatively explain the pressure effect. Experiments were also carried out using a laboratory-scale DCMD set-up. After applying the pressure, the cross-sections and surfaces of the membranes were examined using a scanning electron microscope (SEM). Results showed that the membrane structural parameters such as porosity and thickness were changed under relatively high pressure conditions (&gt, 30 kPa), leading to reduction in flux. The mass transfer coefficients were also significantly influenced by the hydraulic pressure. Moreover, local wetting of the membranes were observed even below the liquid entry pressure (LEP), which decreased the rejection of salts. These results suggest that the control of hydraulic pressure is important for efficient operation of DCMD process.

Gold nanoparticle (AuNP) solution prepared by laser ablation in liquid (LAL) was irradiated by ns laser pulses to investigate the wavelength dependence on the size distribution of AuNPs and long-term stability of post-irradiated AuNP solutions. We have employed 266, 355, 532, and 1064 nm lasers for post-irradiation source and found considerable wavelength dependence in the size distribution and stability of laser-generated AuNPs. Post-irradiation at 355 nm was most effective to reduce the size distribution and to enhance the stability. The classical Derjaguin–Landau–Verwey–Overbeek theory was employed to explain the anomalous stability at 355 nm.

A narrow pore size distribution is critical for most membrane separation processes even though it is difficult to achieve through conventional methods of membrane synthesis such as phase inversion. Although various technologies have been proposed for the preparation of isoporous membranes, few technologies are available for use in water treatment applications. In our previous works, we have prepared isoporous membranes using a novel technique based on soft lithography. A micro pattern of pyramid shape was applied to produce uniform pores. In this work, we aimed at the characterization of these isoporous membranes using both experimental and theoretical methods. The pore size distributions of the membranes were characterized by scanning electron microscopy image analysis. Using this image analysis technique, the pore size ranging from 2.2 to 21.4 μm could be identified. A simple theoretical model was developed to determine the pore size, porosity, and membrane resistance of the isoporous membranes....

Polyynes were prepared by liquid laser ablation of a graphite target in deionized water at different laser wavelengths (266, 355, 532, and 1064 nm) and energies (20 and 40 mJ) as well as ablation times (up to 60 min). They were identified by analyzing their ultraviolet absorption spectra and the amount of polyynes so produced turned out to increase at longer wavelength. Also, in order to investigate the effects of various physical parameters on the linear carbon chain length, we compared the branching ratios between C 6 H 2 , C 8 H 2 , and C 10 H 2 .

E-mail: ssk7185@khu.ac.krReceived November 22, 2012, Accepted January 7, 2013Polyynes were prepared by liquid laser ablation of a graphite target in deionized water at various physicalconditions such as laser power (20 and 40 mJ/pulse) and ablation wavelengths (355, 532, and 1064 nm). Theeffects of physical parameters on the linear carbon chain length were examined by analyzing the densities ofpolyynes with different carbon numbers (C

Membranes utilizing carbon nanotubes (CNTs) as their pores have been emerged as a novel technique for water and wastewater treatment. CNTs are nanometer–diameter cylinders, allowing fast transport of water molecular and other fluid due to their strong hydrophobic characteristics. A few studies have been done for developing membranes embedding single-wall or multiwall nanotubes and simulating their performance theoretically using molecular dynamics. Nevertheless, only a limited number of experimental works were attempted to analyze the transport phenomena inside the CNT membranes due to lack of techniques for quantitative interpretation of the experimental results. Accordingly, this study aimed at developing protocols to quantify the efficiency of CNT membranes and apply them for better understanding of transport mechanisms of the CNT membranes. Membranes made of vertically aligned CNTs, which has 3–5 nm inner diameter and 150∼250 μm length, were used. Special experimental techniques were applied ...

Recently due to the increase in the construction of the steel–concrete composite structures, researches on shear connector which is capable of composite behavior of two members have been widely studied. This study evaluated the behavior of Y-type perfobond rib shear connector which is superior in shear resistance and ductility than conventional perfobond rib shear connector. Also, it suggested a shear resistance equation based on the push-out test. Firstly, various types of the proposed Y-type perfobond rib shear connectors have been examined to evaluate the effect on design variables such as strength of concrete, transverse rebar, thickness of rib, and Y-shape angle. As a result, the experiment showed that the higher the concrete strength, the shear resistance increased, while ductility decreased. In addition, transverse rebar significantly impacted both shear resistance and ductility to increase. Moreover, as thickness of ribs increased, shear resistance increased and ductility decreased. It was also proven that Y-shape angle has an effect on shear resistance and ductility to grow. Furthermore, it was indicated that Y-type perfobond rib shear connector has higher shear resistance and ductility than the conventional perfobond rib shear connector by comparing and estimating the experimental results. Lastly, the effect of bearing resistance, transverse rebar, dowel resistance by holes, and dowel resistance by Y-shape ribs on shear resistance was estimated by regression analysis. Through the result, the shear resistance equation was suggested to predict shear resistance of Y-type perfobond shear connector.

Mg-doped ZnO thin films were deposited on Si surfaces by laser ablation of a Zn:Mg target to shed light on the effects of magnetic field in pulsed laser deposition. Both crystalline and photoluminescence properties of the Mg-doped ZnO film were dramatically enhanced by performing laser ablation under transverse magnetic field at room temperature. The ablation wavelength turned out to be crucial to bring about optimum effects of the magnetic field on the laser-induced plasma plume. Besides, cylindrically phase-separated polystyrene- b -poly(methylmethacrylate) employed as a template facilitated fabrication of bandgap-engineered ZnO nanodot arrays.

Antimony (Sb) doping of SnO 2 nanowires (NWs) was investigated for its optical and electrical effects. The low-temperature photoluminescence spectra of SnO 2 NWs varied significantly with increasing Sb content, where the temperature-dependence of the visible emission at ca. 400 nm was distinctive with Sb-doping, indicating different defect states, such as neutral and positively charged oxygen vacancies. Field effect transistors (FETs) with low-level Sb-doped SnO 2 NW channels exhibited higher mobility, charge concentration, and faster response and recovery to UV light than intrinsic SnO 2 NW FETs.

(≥ 99.0%), n-octane (≥ 99.0%). These solvents were purchased from Sigma-Aldrich and used without further purification. The surface of the graphite target was polished with 1200grade emery paper prior to laser irradiation using a Qswitched Nd:YAG laser (Continuum, Surelite I, λ = 1064 nm, pulse duration 5 ns) operated at 10 Hz. The energy of the laser was maintained at 20 mJ/pulse in order to avoid generation of splashes. The laser beam was loosely focused using a lens with a focal length of 300 mm and the typical irradiation time was 20 min. The solution was stirred during the ablation using a magnetic stirrer. The target was also continuously rotated to minimize the effect of target aging and to provide some stirring effect. The optical properties of the nascent polyynes solutions were studied at room temperature in various solvents by a UV-vis absorption spectrophotometer (Shimadzu UV1800) and normal Raman spectra were recorded by a spectrophotometer (HORIBA T64000).

We investigated the interaction between polyynes (linear carbon chains) and various metal nanoparticles (Ag, Au, and Cu) to provide insight into the optical properties of metal-polyynes systems prepared by different experimental techniques. Polyynes were produced by laser ablation in deionized water, metal nanoparticles solutions, and copper chloride solution. Metal nanoparticles complexes with polyynes were analyzed by Raman, surface-enhanced Raman scattering, and UV-vis spectroscopy.

Polyynes were formed by laser ablation of a graphite target in deionized water (H2O and D2O) and various organic solvents such as acetonitrile, n-hexane, and c-hexane and were identified by analyzing ultraviolet (UV) absorption and Raman spectra. We assigned the major UV absorption peaks that coincided with the electronic transitions corresponding to linear polyyne chains. The UV absorption peak intensities of a polyyne solution decreased as the holding temperature of the solution increased. Also, the absorption spectra of polyynes obtained by laser ablation of a graphite target at different volume fractions of H2O and D2O were examined.

Zinc oxide (ZnO) nanoparticles were prepared in neat deionized water by laser ablation with various ablation times (10–40 min), fluences (50–130 mJ/pulse), and wavelengths (1064, 532, and 355 nm). The size and shape of the nanoparticles were affected only slightly by the ablation time and fluence at a wavelength of 1064 nm, which was explained by a dynamic formation mechanism with surface charge effects. The nanoparticles formed by ablation at 355 nm had a distinctive wire-shape with a small diameter, which was attributed to a continuous fragmentation and formation mechanism.

Optical properties of zinc oxide (ZnO) nanoparticles prepared in supercritical methanol and supercritical water were investigated. Interstitial zinc and oxygen vacancy were the major defects in the ZnO nanoparticles synthesized in supercritical methanol. The addition of oleic acid as a surface modifier resulted in the isolation of the nanoparticles and the removal of interstitial zinc. Lasing was observed with sharp longitudinal modes and a superlinear increase in the emission intensity of the ZnO nanowires synthesized in supercritical water. The band gap renormalization due to the electron–hole plasma induced a red-shift in the emission band, whereas the individual longitudinal modes were blue-shifted due to a change in refractive index.

Biomolecular transport in nanofluidic confinement offers various means to investigate the behavior of biomolecules in their native aqueous environments, and to develop tools for diverse single-molecule manipulations. Recently, a number of simple nanofluidic fabrication techniques has been demonstrated that utilize electrospun nanofibers as a backbone structure. These techniques are limited by the arbitrary dimension of the resulting nanochannels due to the random nature of electrospinning. Here, a new method for fabricating nanofluidic systems from size-reduced electrospun nanofibers is reported and demonstrated. As it is demonstrated, this method uses the scanned electrospinning technique for generation of oriented sacrificial nanofibers and exposes these nanofibers to harsh, but isotropic etching/heating environments to reduce their cross-sectional dimension. The creation of various nanofluidic systems as small as 20 nm is demonstrated, and practical examples of single biomolecular handling, such as DNA elongation in nanochannels and fluorescence correlation spectroscopic analysis of biomolecules passing through nanochannels, are provided.

(a) Photoluminescence spectrum of the ZnO powders ob-tained with a He-Cd laser (325 nm). Inset shows the transmission electron microscopy (TEM) image of the ZnO powders used for the measurements. (b) Emission spectrum of the ZnO powders obtained by intensive excitation of fundamentals, such as 800, 750, and 710 nm. The dotted line indicates the band gap of ZnO. (c) Refractive index and its difference related term as a function of the wavelength.

The authors successfully obtained high quality ZnO thin films by growing them at room temperature (RT) and postannealing by rapid thermal annealing (RTA). The thin films were grown by pulsed laser deposition on Si (100) substrates at RT, and RTA was performed under various temperatures and ambient conditions. Based on the UV emission to visible emission ratio in RT photoluminescence (PL) spectra, the optimum film was obtained at annealing temperature ∼700 °C in an ambient of Ar, N2, or O2 at 0.1 Torr, while the optimum annealing temperature was above 1100 °C in the air ambient at atmospheric pressure. The morphology and structure of the films in different RTA conditions were investigated by using field emission scanning electron microscopy and grazing incidence x-ray diffraction, and were discussed in conjunction with the PL data.

ZnO thin films were grown on Si (100) substrates by pulsed laser deposition using a ZnO target. The substrate temperature was varied in the range of room temperature to 800°C, and the oxygen partial pressure of 0.1333 Pa (1 mTorr) to 1333 Pa (10 Torr). The properties of the resulting films were investigated by photoluminescence (PL), grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM). Based on the ultraviolet (UV, ∼380 nm) to visible emission ratio in the PL spectrum, the optimum growth conditions were determined to be 600°C and 133.3 Pa (1 Torr), respectively. The oxygen 1 s peak in the XPS spectrum was decomposed into two peaks. The peak at lower binding energy increased in intensity with the oxygen partial pressure from 0.1333 Pa (1 mTorr) to 133.3 Pa (1 Torr) while the other peak decreased. The GIXRD curve at the optimum condition showed strong two peaks (002 and (103). A strong correlation between the (103) peak intensity and the UV emission intensity was found.

High-performance concrete (HPC) as a promising construction material has been widely used in infrastructures and high-rise buildings etc. However, its pretty high autogenous shrinkage (AS) especially in its early age becomes one of the key problems endangering long-time durability of HPC structures. This paper carried out the early age AS research of large scaled HPC column specimens by embedded Fiber Bragg-Grating (FBG) strain sensor. Temperature compensation for FBG strain sensor by thermocouple was also attempted in this paper, and the results were reasonable and acceptable comparing with the result compensated by FBG temperature sensor. Reinforcement influence, size effect and temperature effect on HPC AS were also analyzed respectively in this paper.

The experimental extinction spectrum of 38 nm long silver nanorods grown in the 22 nm pores of an anodic aluminum oxide (AAO) template is theoretically analyzed, using the discrete dipole approxima...

We fabricated hexagonal arrays of Co/Pt nanodots on Si surfaces by pulsed laser deposition (PLD) using cylindrically phase-separated polystyrene-b-poly(methylmethacrylate) (PS-b-PMMA) diblock copolymer thin films as templates after the removal of PMMA. The size and the separation of the nanodots were 23 and 40 nm, respectively, and the density of the nanodots was 1.5 x 10(11)/cm2. The magnetic properties of nanodot arrays measured by vibrating sample magnetometer were compared with those of PLD grown film. The films showed magnetic anisotropy with an easy axis in the in-plane direction, whereas no noticeable anisotropy was observed for nanodot arrays. In addition, the saturation magnetization (Ms) of both the Co/Pt nanodots and the film increased with the Pt content.

One-dimensional gold nanorods were synthesized from gold decahedrons in the presence of silver ions by a systematic overgrowth approach. Both the diameters and lengths of the nanorods were independently varied by using distinct-sized decahedrons and gold precursor concentrations. The key factors of anisotropic growth are three-dimensional decahedral seed structures and energetic differentiation of the distinct facets. A series of copper and silver underpotential deposition (UPD) experiments confirmed that the silver components were mainly located on the Au(100) facets, which constitute the side walls of the nanorods. The growth mechanism of the gold nanorods could be clarified by an arbitrary elongation of the decahedral seeds and selective restriction of the {100} growth by silver UPD. Low temperature growth without silver generated very long nanowires by preferential adsorption of poly(vinyl pyrrolidone) on the {100} surface.

The roles of coordinating ligands (TOPO, OA, HDA, and TDPA) for the synthesis of ZnO nanoparticles are investigated. Various shapes (hexagonal cone, hexagonal plate, and rod) and sizes (5-100 nm) of ZnO nanoparticles are prepared in relation to the coordinating ligands. The hexagonal shapes (≤ 100 nm) are synthesized with TOPO and OA, while smaller size nanorods (5 × 30 nm) are with TOPO and TDPA. The relative intensities of two distinctive emission bands centered at 385 and 500 nm, which are related to the exciton and defect states, respectively, depend on the crystal qualities of ZnO nanoparticles affected by the coordinating ligands. The intense UV emissions with the reduced visible emissions are found in the monodisperse nanoparticles such as hexagonal cones and nanorods, suggesting that the monodispersity as well as the crystallinity is closely related to the coordinating ligands. The blue-shift of photoluminescence and absorption edge is observed in the nanorods, because the sizes of the nanorods are in the quantum confinement regime.

Photoluminescence (PL) of zinc oxide (ZnO) nanorods with an average thickness of 5 nm and a length of 30 nm is blue-shifted compared to the bulk due to quantum confinement effects. The exciton states remain relatively stable at a high carrier density due to a smaller exciton size and an enhanced exciton binding energy in the quantum confined nanorods, whereas the electron-hole plasma states are formed in the bulk at the similar carrier density. A linear dependence of the PL intensity on the excitation intensity also corroborates the assumption that the stable exciton states are responsible for the undisturbed emission at a high carrier density.