bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Highly Luminescent LaPO4:Eu3+/LaPO4 One-Dimensional Core/Shell Heterostructures
Authors: Bu Wenbo , Shi Jianlin
Published: April 2020

Highly luminescent LaPO4:Eu3+/LaPO4 one-dimensional (1D) core/shell heterostructures were successfully synthesized by a mild and simple self-aggregation process under refluxing or hydrothermal conditions. The resulting 1D core/shell heterostructures
were characterized using a variety of techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS) to demonstrate successful
coating by the crystalline LaPO4. In addition, a possible formation mechanism for this core/shell heterostructure was proposed. Finally, the photoluminescence property of the LaPO4:Eu3+/LaPO4 1D core/shell heterostructures was investigated in detail,
which illustrates that the core/shell heterostructures remarkably increase the luminescence efficiency because the LaPO4 shells effectively eliminate surface trap-states and suppress the energy quenching in the energy-transfer processes.
One-Dimensional Rare Earth Compounds and Complexes: Preparation and Improved Photoluminescence Properties
Authors: Song Hongwei , Pan Guohui , Bai Xue , Li Suwen , Yu Hongquan , Zhang Hui
Published: April 2020

One-dimensional nanosized phosphors demonstrate special structural and photoluminescence properties, which have application potential in some optical fields. In this article, we present our recent progress on preparation and luminescence properties of some one-dimensional rare earth
compounds and complexes, the core–shell oxide nanowires prepared by a two-step hydrothermal route, the nanowires of some inorganic compounds doped with rare earths and rare earth complexes/PVP composites prepared by the electrospinning method, and the rare earth complexes in the SBA-15
mesoporous molecule sieves. In these systems, some novel or improved photoluminescence properties are observed such as improved luminescence quantum yield, thermal stability and/or photostability, and depressed thermal effect in upconversion luminescence.
Multicolor Up-Conversion Emissions of Tm3+/Er3+/Yb3+ Tri-Doped YF3 Phosphors
Authors: Cao Chunyan , Qin Weiping , Zhang Jisen , Zhang Jishuang , Wang Yan , Jin Ye , Wei Guodong , Wang Guofeng , Wang Lili
Published: April 2020

Tm3+/Er3+/Yb3+ tri-doped yttrium fluoride (YF3) phosphors were prepared by a facile hydrothermal method. X-ray topographic analysis found that the phosphors were crystallized products. Their sizes and morphologies were characterized by scanning
electron microscopy (SEM, Hitachi S-4800), which indicated that most of the YF3 phosphors were hundreds of nanometers in size. Up-conversion (UC) spectra were recorded under 980-nm diode laser excitation at room temperature with a fluorescence spectrometer (Hitachi F-4500). Plenty
of UC emissions of Tm3+ and Er3+ were observed from ultraviolet to red. For Tm3+ ions, a five-photon process (∼291 nm and ∼347 nm), a four-photon process (∼362 nm and ∼452 nm), and a three-photon process (∼475 nm) were identified in the
UC spectra. The UC emissions from the Er3+ were: ∼380 nm, ∼408 nm, ∼521 nm, ∼537 nm, and ∼652 nm. Therefore, cyan-white light can be observed by the naked eye at 980-nm excitation, even under low excitation power density. By comparing the UC spectra of the phosphors
annealed at different temperatures, we found that the intensity of the UC luminescence increased as annealing temperature increased. Furthermore, the spectral dependencies on Tm3+ doped concentrations were studied. The energy transfer processes and fluorescence dynamics in the tri-doped
system are currently being investigated.
Effect of Mechanical Milling on Photoluminescence of γ-Alumina Nanoparticles
Authors: Luo Jinsong , Liu Shufeng , Wang Lidan , Fan Yi , Zhang Ligong , Zhang Peiping , An Linan
Published: April 2020

The effect of mechanical alloying on the photoluminescence behavior of γ-Al2O3 nanopowder was studied. Two emission peaks centered at 343 and 378nm and a broad emission band ranging between 400–600 nm have been observed. It is found that the
intensity of the two emission peaks decreases with ball-milling time, while that the broad band remains un-change. These results suggested that the two peaks are resulted from the surface defects that analogs of F+ centers, while the broad band is resulted from impurity.
Structural Phase Transition of Tungsten-Doped Vanadium Dioxide Nanopowders Prepared by Thermolysis
Authors: Peng Zifei , Jiang Wei , Liu Heng
Published: April 2020

Tungsten-doped vanadium dioxide (VO2) nanopowders were prepared by thermolysis of (NH4)5[(VO)6(CO3)4(OH)9] · 10H2O at low temperature, with active white powdery tungstic acid used as a substitutional
dopant. The composition and microstructure of the powders were examined by X-ray diffraction, transmission electron microscope, and differential scanning calorimetry. The change in electrical resistance due to the S–M transition was measured from 0 to 150 °C by the four-probe method.
Hysteresis loops and differential scanning calorimetry analysis of the samples indicated that the phase-transition temperature of VO2 nanopowders was 67.15 °C. For tungstendoped VO2 nanopowders, the temperature was reduced to 26.46 °C. After sintering the nanopowders,
Tc rose from 26.46 °C to 34.85 °C with the sizes increasing to the bulk. A significant direct correlation between particle size and Tc was confirmed. The results indicated that white powdery tungstic acid is exceptionally effective as a dopant for reducing transition
temperature.
Hydrothermal Synthesis and Size-Enhanced Chromaticity of Sr2ZnSi2O7:Eu3+ Nanoparticles
Authors: Wan Junxi , Yao Youwei , Tang Guoyi , Qian Yitai
Published: April 2020

Red phosphor Sr2ZnSi2O7:Eu3+ nanoparticles with an average diameter of 20 nm were successfully synthesized via a low-temperature hydrothermal route in order to understand the underlying relationship between size and luminescent properties.
The nanometer-sized particles result in a distinct improvement in chromaticity and a high quenching concentration. According to emission spectra, the relative intensity of the 5D0 → 7F2 to 5D0 → 7F1
transitions in nanometer-sized phosphors is higher than that of the corresponding bulk material. The better chromaticity results from the more distorted lattices and relatively lower crystal symmetry around the Eu3+ ions, which is ascribed to the large surface area due to the nanometer
size of the phosphor. Moreover, the nanometer-sized Sr2ZnSi2O7:Eu3+ red phosphor exhibits a shorter fluorescent lifetime and a blue-shift in excitation spectra compared to that of its bulk counterpart. These results indicate that size-induced enhancement
of luminescent properties is an efficient way to obtain red phosphors with better chromaticity.
Attachment of Functionalized Single-Walled Carbon Nanotubes (SWNTs) to Silicon Surfaces
Authors: Zeng Liling , Pattyn Nancy , Barron Andrew R.
Published: April 2020

Single-walled carbon nanotubes (SWNTs) were functionalized by direct fluorination and subsequent reaction with 6-aminohexanoic acid for water-soluble carboxylic acid functionalized SWNTs (AHA-SWNTs). Both of the compounds were used as precursors to attach SWNTs to APTES coated silicon
surfaces. AHA-SWNTs in aqueous solution were reacted with APTES self-assembled monolayers (SAMs) with coupling reagents N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS). The surface coverage is a function of concentration of AHA-SWNTs,
solvent and coupling method. While for the fluorinated SWNTs (F-SWNTs), direct addition of F-SWNTs to preformed APTES SAMs at 90 °C shows essentially no reaction, in contrast to the one-pot reaction of F-SWNTs with APTES molecules in the presence of SWNTs on a silicon substrate. This reaction
route provides a convenient method to attach SWNTs to silicon surfaces.
Crystal Form and Phase Structure of Poly(vinylidene fluoride)/Polyamide 11/Clay Nanocomposites by High-Shear Processing
Authors: Li Yongjin , Iwakura Yuko , Shimizu Hiroshi
Published: April 2020

Polyamide 11 (PA11)/clay, Poly(vinylidene fluoride) (PVDF)/clay and PVDF/PA11/clay nanocomposites were prepared by melt processing using a high shear extruder. Two types of organoclay with different modified alkyl tails and different polarities were used for PA11 and PVDF nanocomposites.
PA11 nanocomposites derived from an organoclay having one alkyl tail show a well-exfoliated morphology but no crystal form transformation, whereas those derived from an organoclay having two alkyl tails give a little worse clay dispersion with the clear α to γ crystal
form transition with the addition of the clay. In contrast, the PVDF composites derived from the two organoclays result in a poor dispersion. In addition, PVDF/PA11 blend nanocomposites with a novel morphology have been fabricated using the high-shear extruder. It was found that the clay platelets
were selectively dispersed in the PA11 phase with the size of larger than 200 nm, while no clay platelets were located in the PVDF phase and in the PA11 nanodomains with the size of smaller than 200 nm. Moreover, the addition of organoclay shows significant effects on the phase structure of
PVDF/PA11 blends.
Nonisothermal Crystallization Kinetics of Poly(ethylene terephthalate) Nanocomposites
Authors: Bandyopadhyay Jayita , Sinha Ray Suprakas , Bousmina Mosto
Published: April 2020

This article reports the nonisothermal crystallization kinetics of poly(ethylene terephthalate) (PET) nanocomposites. The non-isothermal crystallization behaviors of PET and the nanocomposite samples are studied by differential scanning calorimetry (DSC). Various models, namely the
Avrami method, the Ozawa method, and the combined Avrami-Ozawa method, are applied to describe the kinetics of the non-isothermal crystallization. The combined Avrami and Ozawa models proposed by Liu and Mo also fit with the experimental data. Different kinetic parameters determined from these
models prove that in nanocomposite samples intercalated silicate particles are efficient to start crystallization earlier by nucleation, however, the crystal growth decrease in nanocomposites due to the intercalation of polymer chains in the silicate galleries. Polarized optical microscopy
(POM) observations also support the DSCresults. The activation energies for crystallization has been estimated on the basis of three models such as Augis–Bennett, Kissinger and Takhor methods follow the trend PET/2C20A<PET/1.3C20A<PET, indicating incorporation of organoclay enhance
the crystallization by offering large surface area.
Nanosurface-Confined Anisotropic Growth and Magnetism of Ellipsoidal α-Fe Nanogranules
Authors: Hun Huh Seung , Yeoul Kim Chang , Hyung Riu Doh , Taguchi Yosuke , Nakajima Atsushi
Published: April 2020

We have investigated the nanosurface-confined anisotropic growth of ordered-ellipsoidal Fe nanogranules when an Fe plume was deposited at a slanting angle onto an anodized aluminum oxide (AAO) film. Layer-by-layer growth was also investigated. This growth is driven by two critical factors:
(1) a new rhombic AAO cell and (2) the slanting deposition of the Fe plume. During slanting deposition, the rhombic AAO cell induces strong restrictions in the nucleation site, growth direction, and granular size; therefore, the degree of freedom during growth is restricted. The magnetic dipoles
of the ordered Fe nanogranules are placed along the long axis of the ellipsoid at an angle of 180° (antiparallel) due to the demagnetizing field, shape anisotropy, and magnetic dipole-to-dipole interactions.
Tubular-Shaped Nanocarbons Prepared from Polyaniline Synthesized by a Self-Assembly Process and Their Electrical Conductivity
Authors: Kyotani Mutsumasa , Goto Hiromasa , Suda Kiyoshi , Nagai Takuro , Matsui Yoshio , Akagi Kazuo
Published: April 2020

A tubular-shaped polyaniline less than 5 μm in length and 170 nm in outer diameter was synthesized by a self-assembly process using D-camphorsulfonic acid as a dopant. A tubular-shaped nanocarbon was prepared from the tubular-shaped polyaniline by means of pyrolysis at 1000
°C in argon gas. The structural and electrical properties of the resultant tubular-shaped nanocarbons were investigated using Raman scattering spectrum, X-ray diffraction measurements, scanning and transmission electron microscopes, and a low resistivity meter. The tubular-shaped nanocarbons
are very short in length and are an amorphous state. The short length and amorphous tubular-shaped nanocarbon were crystallized to some extent by heat-treatment at 2600 °C. The tubular-shaped nanocarbons mentioned in this work are appropriate for mass production, compared to the well-known
multi-walled carbon nanotubes. The electrical conductively of the tubular-shaped polyaniline was remarkably improved by the carbonization and was enhanced by the heat-treatment.
Luminescent Lanthanide Nanoparticles as Labels in DNA Microarrays for Quantification of Methyl Tertiary Butyl Ether Degrading Bacteria
Authors: Son Ahjeong , Nichkova Mikaela , Dosev Dosi , Kennedy Ian M. , Hristova Krassimira R.
Published: April 2020

We report application of lanthanide nanoparticles for DNA quantification in a microarray platform as a substitute for conventional organic fluorophores. A non-PCR based DNA microarray assay for quantifying bacteria capable of biodegrading methyl tertiary-butyl ether (MTBE) was demonstrated.
Probe DNA was immobilized on a glass surface, hybridized with biotinylated target DNA and subsequently incubated with Neutravidin-biofunctionalized nanoparticles. The fluorescence spot intensities, measured by a commercial laser scanner, show a linear relationship (R2 = 0.98)
with bacterial 16S rDNA over a range of target DNA concentrations, while the background fluorescence remained low. In addition, nanoparticles fluorescence shows a stronger intensity than Quasar570 (Cy3). Present sensitivity of the assay is 10 pM of target DNA. The selectivity of the DNA-nanoparticle-probes
to discriminate a non-target DNA with two base pairs mismatch in the 16S rDNA gene sequence was shown. The use of Eu:Gd2O3 nanoparticles as biolabels provides a relatively non-toxic, inexpensive, rapid and sensitive alternative to the materials currently used in DNA microarrays.
Effect of Carbon Concentration on the Optical Properties of Nanocrystalline Diamond Films Deposited by Hot-Filament Chemical Vapor Deposition Method
Authors: Wang Linjun , Liu Jianmin , Ren Ling , Su Qingfeng , Shi Weimin , Xia Yiben
Published: April 2020

With reducing diamond grain size to nano-grade, the increase of grain boundaries and non-diamond phase will result in the change of the optical properties of chemical vapor deposition (CVD) diamond films. In this paper, the structure, morphology and optical properties of nanocrystalline
diamond (NCD) films, deposited by hot-filament chemical vapor deposition (HFCVD) method under different carbon concentration, are investigated by SEM, Raman scattering spectroscopy, as well as optical transmission spectra and spectroscopic ellipsometry. With increasing the carbon concentration
during the film deposition, the diamond grain size is reduced and thus a smooth diamond film can be obtained. According to the data on the absorption coefficient in the wavelength range from 200 to 1100 nm, the optical gap of the NCD films decreases from 4.3 eV to 3.2 eV with increasing the
carbon concentration from 2.0% to 3.0%. From the fitting results on the spectroscopic ellipsometric data with a four-layer model in the photon energy range of 0.75–1.5 eV, we can find the diamond film has a lower refractive index (n) and a higher extinction coefficient (k) when the carbon
concentration increases.
A Photoluminescence Study of Film Structure in CdTe Nanoparticle Thin Films
Authors: Gardner H. C. , Gallardo D. E. , Dunn S. , Gaponik N. , Eychmüller A.
Published: April 2020

The layer-by-layer deposition of thin films of CdTe nanoparticles and three different polyelectrolytes has been investigated. Photoluminescence spectra were used to monitor the energy transfer properties within the films. As the number of bilayers in a thin film was increased a decrease
in the energy of the light emitted was observed. The wavelength change is a two-stage process. Deposition of the first one to two bi-layers of a thin film produced a sharp energy change (626 nm to 637 nm with the addition of a single bi-layer) whereas deposition of subsequent bi-layers produced
a more gradual energy change (642 nm–646 nm with the addition of 5 bi-layers). A space-filling mechanism is suggested to account for these changes; smaller nanoparticles penetrate the earlier levels of a thin film and increase the inter-particle energy transfer opportunities within the
layers.
Nano-Polycrystalline Vanadium Oxide Thin Films Prepared by Pulsed Laser Deposition
Authors: Wang Y. L. , Li M. C. , Chen X. K. , Wu G. , Yang J. P. , Wang R. , Zhao L. C.
Published: April 2020

Nano-polycrystalline vanadium oxide thin films have been successfully produced by pulsed laser deposition on Si(100) substrates using a pure vanadium target in an oxygen atmosphere. The vanadium oxide thin film is amorphous when deposited at relatively low substrate temperature (500
°C) and enhancing substrate temperature (600–800 °C) appears to be efficient in crystallizing VOx thin films. Nano-polycrystalline V3O7 thin film has been achieved when deposited at oxygen pressure of 8 Pa and substrate temperature of 600
°C. Nano-polycrystalline VO2 thin films with a preferred (011) orientation have been obtained when deposited at oxygen pressure of 0.8 Pa and substrate temperatures of 600–800 °C. The vanadium oxide thin films deposited at high oxygen pressure (8 Pa) reveal a mix-valence
of V5+ and V4+, while the VOx thin films deposited at low oxygen pressure (0.8 Pa) display a valence of V4+. The nano-polycrystalline vanadium oxide thin films prepared by pulsed laser deposition have smooth surface with high qualities of
mean crystallite size ranging from 30 to 230 nm and Ra ranging from 1.5 to 22.2 nm. Relative low substrate temperature and oxygen pressure are benifit to aquire nano-polycrystalline VOx thin films with small grain size and low surface roughness.
Preparation of Polypyrrole Nanoparticles in Reverse Micelle and Its Application to Glucose Biosensor
Authors: Ren Xiangzhong , Zhao Qi , Liu Jianhong , Liang Xun , Zhang Qianling , Zhang Peixin , Luo Zhongkuan , Gu Yi
Published: April 2020

Polypyrrole nanoparticles were successfully synthesized in cetyltrimethyl ammonium bromide (CTAB)/hexanol/water reverse micelle. The morphology and particle size of the obtained nanoparticles were characterized with transmission electron microscope (TEM) and scanning electron microscopy
(SEM). Glucose biosensors were formed with glucose oxidase (GOx) immobilized in conducting composite material consisting of polypyrrole nanoparticles and ethyl cellulose. The effects of reaction conditions such as molar ratio of polypyrrole nanoparticles to ethyl cellulose, working voltage,
glucose concentration, temperature and solution pH on the electrochemical response of the GOx electrode were studied. Experimental results showed that the linear range of GOx electrode was 1.0 × 10−6∼6 × 10−3 mol/L and the detection limit was
1.0 × 10−7 mol/L. The electrode exhibited fine repeatability and selectability, and its lifetime was greater than one month. AFM showed that the surface of conducting composite material-glucose oxidase electrode's presents uniform granular after washing paraffin wax
with cyclohexane, which was favorable for enzyme-catalyzed reaction.
Preparation of Immobilized Nano-Columnar TiO2 Grains by Chemical Vapor Deposition
Authors: Huang Hong-Hsin
Published: April 2020

Nano-columnar TiO2 grains are prepared and immobilized by chemical vapor deposition using TiCl4, H2 and O2 at low temperature. The structure of TiO2 is analyzed by X-ray diffraction (XRD), the morphology is observed by scanning
electron microscopy (SEM) and the adhesion is estimated by measuring the critical load in scratch test. Results show that the structure of TiO2 films depend on the deposition temperature changing from amorphous, anatase, rutile, and both anatase and rutile phases as prepared at
temperatures of 200, 300, 400 and 500 °C, respectively. The nano-columnar TiO2 grains are formed in both rutile and anatase phases, while it could be only rutile phase by increasing TiCl4 flow rate. The morphologies of TiO2 changes from smooth to nano-columnar
grains as the deposition temperature increased from 200 to 400 °C. Excellent adhesion strength of crystalline TiO2 was obtained and it could be improved by increasing the TiCl4 flow rate in range of 0.3–0.6 sccm, where the critical load of TiO2 increases
from 17 to 21 N.
The Ti-B-N System: Nanocomposite nc-TiN/a-(TiB2, BN) and Nano-Multilayer nc-TiN/a-TiBN Thin Films
Authors: Lu Y. H. , Chu K. , Shen Y. G.
Published: April 2020

The nanostructures and mechanical properties of nanocomposite nc-TiN/a-(TiB2, BN) and nanostructured multilayers nc-TiN/a-TiBN were investigated using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), microindentation, and stress measurements.
It was found that the monolayer Ti-B-N thin films consisted of nanometer-sized crystalline (nc-) Ti(N, B) embedded into amorphous (a-) (TiB2, BN) matrix. When B content was below ∼16 at.%, two different-sized nanocrystallites with mean grain sizes of ∼3 and 9 nm respectively
were embedded in a-TiB2. With increasing B incorporation (>∼27 at.%), more uniform nanograins was embedded a-(TiB2, BN). Incorporation of B not only decreased the size of nanocrystallites, but also gave rise to twinning deformation in nanocrystallites. A maximum
hardness of ∼44 GPa was achieved at B content of 19 at.%. It was also found that the nanostructure and mechanical behaviors of nc-TiN/a-TiBN multilayers was dependent on the modulation length (bilayer thickness Λ). Decrease of Λ made the preferred orientation of nc-TiN gradually
transform from (200) to (111). A maximum hardness of ∼30 GPa was achieved at Λ = 1.8 nm. Deflection from this Λ value decreased hardness. By contrast, the residual compressive stress value monotonically increased with decrease of Λ. The enhancement of the hardness
was due to the coherent stresses and the structural barriers to dislocation motion in the interface.
Remanence and Switching Sensitivity in Nanodot Magnetic Arrays
Authors: Gawrónski Przemysław , Kułakowski Krzysztof
Published: April 2020

New results are reported of the computer simulations on the magnetic behaviour of magnetic arrays of nanoscopic dots, placed in cells of the square lattice. We show that the remanence magnetization Mr decreases with the array size. For arrays 50 × 50, we investigate
also the stability of the magnetic structure of an array in an oscillating magnetic field. The damage spreading technique reveals that this stability increases with the standard deviation σ of the switching field of individual elements of the array. On the other hand, Mr
decreases with σ. An optimalization of the system (large Mr and large stability) can then be reached at some intermediate value of σ.
Very Thin Poly-SiC Films for Micro/Nano Devices
Authors: Fu Xiao-An , Noh Sangsoo , Chen Li , Mehregany Mehran
Published: April 2020

We report characterization of nitrogen-doped, very thin, low-stress polycrystalline silicon carbide (poly-SiC) films suitable for fabricating micro/nano devices. The poly-SiC films are deposited on 100 mm-diameter (100) silicon wafers in a large-scale, hot-wall, horizontal LPCVD furnace
using SiH2Cl2 and C2H2 as precursors and NH3 as doping gas. The deposition temperature and pressure are fixed at 900 °C and 4 Torr, respectively. The deposition rate increases substantially in the first 50 minutes, transitioning to
a limiting value thereafter. The deposited films exhibit (111)-orientated polycrystalline 3C-SiC texture. HR-TEM indicates a 1 nm to 4 nm amorphous SiC layer at the SiC/silicon interface. The residual stress and the resistivity of the films are found to be thickness dependent in the range
of 100 nm to 1 μm. Films with thickness less than 100 nm suffer from voids or pinholes. Films thicker than 100 nm are shown to be suitable for fabricating micro/nano devices.
Light-Driven Novel Properties of TiO2-Modified Polypropylene-Based Nanocomposite Films
Authors: Kubacka A. , Cerrada M. L. , Serrano C. , Fernández-García M. , Ferrer M. , Fernández-García M.
Published: April 2020

Nanocomposite films obtained by TiO2 incorporation into a polypropylene (PP) polymer matrix were prepared via a straightforward melting process. The structural characteristics of the nanocomposite materials were examined by a multitechnique approach showing the outstanding
morphological uniformity of the films. TiO2 incorporation into the polymer matrix renders self-sterilized and self-degradable materials which showed an impressive performance against gram-positive, gram-negative, coccus and yeast micro-organisms. Optimization of the novel properties
of TiO2-PP nanocomposite films is reached with a 2 wt% of oxide content loading. The physico-chemical bases of this optimum are discussed.
Preparation of Fullerene (C60) Based SiO2 Sonogel Hybrid Composites: UV Laser Induced Photo-Polymerization, Morphological, and Optical Properties
Authors: Morales-Saavedra Omar G. , Castañeda Rosalba , Bañuelos J. Guadalupe , Carreón-Castro Ma. del Pilar
Published: April 2020

Fullerene (C60) spheres were successfully embedded by diffusion into a catalyst-free SiO2 sonogel network. By this method, homogeneous and stable solid state hybrid samples suitable for optical characterization were produced. Due to the high porosity exhibited
by the sonogel matrix on the nanometric length-scale, the preparation of several C60 doped composites with variable dopant concentrations was achieved. The obtained bulk hybrids were irradiated with a pulsed Kr-F laser system in order to induce photo-polymerization of the implanted
C60 guest molecules at optimal experimental conditions established according to the pulsed laser photoacoustic technique (LPAT). The adequate purity level displayed by the sonogel route allowed us to perform optimal optical characterizations of these composites (reference hybrids
and photo-polymerized samples) in order to evaluate their photo-physical properties for potential photonic applications. In this work the sonolysis process used to prepare amorphous catalyst-free SiO2:C60 sonogel hybrids and their linear and nonlinear optical (NLO) properties
are extensively discussed. UV-VIS absorption-, Photo Luminescent (PL)-, and Raman-spectroscopies in conjunction with nonlinear optical limiting (OL) measurements, gave experimental evidence of the inclusion of C60 molecules within the sonogel environment, the laser induced photo-polymerization
process and the induced changes of the optical and NLO-properties. Results are discussed in combination with atomic force microscopy (AFM) studies in order to explore the surface morphology of these samples.
Enhanced Thermal Conductivity of Nanofluids Diagnosis by Molecular Dynamics Simulations
Authors: Teng Kuo-Liang , Hsiao Pai-Yi , Hung Shih-Wei , Chieng Ching-Chang , Liu Ming-Shen , Lu Ming-Chang
Published: April 2020

Molecular Dynamics simulations are performed to calculate the thermal conductivity of nanofluids, and to understand the fundamental physics of the enhancement of thermal conductivity observed in experiments. Based on the analysis, intermolecular interactions between copper–copper
atoms, layer structure surrounding nanoparticles, convection effect induced by the Brownian motion of copper atoms, as well as particle–particle interactions are identified and confirmed on the enhancement using Green-Kubo method in thermal conductivity.
A Penalty Method to Model Particle Interactions in DNA-Laden Flows
Authors: Trebotich D. , Miller G. H. , Bybee M. D.
Published: April 2020

We present a hybrid fluid-particle algorithm to simulate flow and transport of DNA-laden fluids in microdevices. Relevant length scales in microfluidic systems range from characteristic channel sizes of millimeters to micron scale geometric variation (e.g., post arrays) to 10 nanometers
for the length of a single rod in a bead-rod polymer representation of a biological material such as DNA. The method is based on a previous fluid-particle algorithm in which long molecules are represented as a chain of connected rods, but in which the physically unrealistic behavior of rod
crossing occurred. We have extended this algorithm to include screened Coulombic forces between particles by implementing a Debye-Hückel potential acting between rods. In the method an unsteady incompressible Newtonian fluid is discretized with a second-order finite difference method
in the interior of the Cartesian grid domain; an embedded boundary volume-of-fluid formulation is used near boundaries. The bead-rod polymer model is fully coupled to the solvent through body forces representing hydrodynamic drag and stochastic thermal fluctuations. While intra-polymer interactions
are modeled by a soft potential, polymer-structure interactions are treated as perfectly elastic collisions. We demonstrate this method on flow and transport of a polymer through a post array microchannel in 2D where the polymer incorporates more realistic physical parameters of DNA, and compare
to previous simulations where rods are allowed to cross. We also show that the method is capable of simulating 3D flow in a packed bed micro-column.
Stiffness and Thickness of Boron-Nitride Nanotubes
Authors: Song J. , Wu J. , Huang Y. , Hwang K. C. , Jiang H.
Published: April 2020

We establish an analytic approach to determine the tensile and bending stiffness of a hexagonal boron-nitride (h-BN) monolayer and singleand multi-wall boron-nitride nanotubes (BNNTs) directly from the interatomic potential. Such an approach enables one to bypass atomistic simulations
and to give the tensile and bending stiffness in terms of the parameters in the potential. For single- and multi-wall BNNTs, the stiffness also depends on the (inner most or outer most) wall radius and the number of the walls. The thickness of h-BN monolayer is also discussed.
Method of Submerged Stokeslets for Slip Flow About Ensembles of Particles
Authors: Zhao Shunliu , Povitsky Alex
Published: April 2020

A boundary singularity method with submerged Stokeslets is applied to the low Reynolds number flows about a set of spheres. Newtonian fluid is considered with no slip or partial slip boundary conditions at the wall. The validity of the method for Stokes flows about representative sets
of spheres is investigated. The considered cases include (i) a uniform flow about a stationary set of particles typical for filtration and chemical vapor deposition, (ii) a flow induced by particles moving toward each other typical for self-assembly processes and (iii) a flow induced by spinning
particles typical for micro-pump applications. The dependence of the flowfield on the number of Stokeslets is investigated in order to establish the needed number of Stokeslets. Comparison of flow field for the no-slip (Kn = 0) and partial-slip boundary conditions (Kn = 0.1)
shows that the partial slip at the particles' surface significantly affect the velocity field and pressure distribution.
Ordered Arrays of Magnetic Metal Nanotubes and Nanowires Encapsulated with Carbon Tubes
Authors: Gao Cuiling , Tao Feifei , Lin Weiwei , Xu Zheng , Xue Ziling
Published: April 2020

The ordered arrays of magnetic metal (including Fe, Co and Ni) nanotubes and nanowires encapsulated with carbon tubes are controllably synthesized by employing the array of C tubes as second-order template and combining with electrodeposition technique. The wall thickness and diameter
of carbon nanotubes are uniform along the whole tubes; also the wall thickness of inner metal nanotubes is adjustable from 25 nm to solid nanowires. These composite structures are characterized by X-ray diffractometer (XRD), energy-dispersive spectrometry (EDS), Raman scattering spectrum,
transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The magnetic properties show that coaxial nanotubes and nanocables composite arrays all exhibit magnetic anisotropy with the easy direction perpendicular to axis of the metal nanotubes or nanowires except the Ni@C
coaxial nanotubes array that has no preferable magnetization axis.
Dependence of Luminescence Efficiency of CdSe Quantum Dots on Chemical Environments
Authors: Jose Rajan , Ishikawa Mitsuru , Thavasi Velmurugan , Baba Yoshinobu , Ramakrishna Seeram
Published: April 2020

Dependence of photoluminescence (PL) efficiency (ΦPL) of CdSe quantum dots (QDs) on coordinating solvents, precursors, and dispersing solvents was investigated. The ΦPL of CdSe QDs was ∼0.05 when synthesized at 120 °C using the precursors, cadmium
acetate (CdAc) and trioctylphosphine selenide (TOPSe) in trioctylphosphine (TOP). The ΦPL was increased from 0.05 to ∼0.1 when coordinating solvents, trioctylphosphine oxide (TOPO) and hexadecylamine (HDA), were added to the above reaction mixture. The ΦPL
was dramatically increased from ∼0.1 to ∼0.7 when CdAc was replaced by cadmium stearate (CdSt). The ΦPL of CdSe QDs synthesized using cadmium stearate (CdSt)/TOPSe/TOP/TOPO was measured in butanol, chloroform, hexane, and toluene and found that the ΦPL
is strong dispersing solvent-dependent. The DFT analysis at b3lyp/lanl2dz level on the interaction of CdSe QDs with chemical environments showed that oxygen-containing molecules interact strongly with CdSe compared to non-oxygen containing molecules and could influence the ΦPL.
Purification of Laser Synthesized SWCNTs by Different Methods: A Comparative Study
Authors: Matlhoko Letlhogonolo , Pillai Sreejarani K. , Ray Suprakas Sinha , Augustyn Willem G. , Moodley Mathew
Published: April 2020

A comparison of different purification procedures for single walled carbon nanotubes (SWCNTs) synthesized by laser-vapourization has been presented. The methods involved gas-phase oxidation by calcination, liquid-phase oxidation by H2O2, hydrothermal treatment
and acid refluxing in HCl. Sample purity is documented with Raman spectroscopy, Transmission electron microscopy, Scanning electron microscopy and thermogravimetric analysis. Multi-spot analyses were done to check the homogeneity of the purified samples. Different purification processes produced
SWCNT material with purity in the range of 48–78%. Raman and TEM results suggested that prolonged calcination results in selective etching of larger diameter nanotubes. SEM and TGA analyses showed increase in density of SWCNTs with better oxidation resistance after purification.
Development of Nanostructured EuAl2O4 Phosphors with Strong Long-UV Excitation
Authors: Hirata Gustavo A. , Bosze Eric J. , McKittrick Joanna
Published: April 2020

Fueled by the need to develop novel materials for applications in solid state white-emitting lamps we have improved a new low-cost, clean and efficient technique to produce high luminescence phosphors with strong excitation in the long-UV range (350–400 nm) which makes them useful
for applications in GaN-based solid state lamps. In this work, pressurized combustion synthesis has been successfully used to develop EuAl2O4 (europium aluminate), a new green photoluminescent material with monoclinic structure. The combustion synthesis reaction conditions
can be adjusted to produce either the AlEuO3 orthorhombic phase at low pressures (0.1 MPa), or the new monoclinic EuAl2O4 phase, which is apparently more thermodynamically favorable at higher combustion reaction pressures (1.4 MPa). The luminescent material
is a high surface area powder (∼50 m2/g) composed mainly of nanostructured needles and plates with 5–10 nm in diameter and 100–150 nm in length. A broad emission peak centered at 530 nm with a decay time of 1.5∼2 ms is obtained at the maximum excitation wavelength
λexc = 370 nm.
Removal of Cryptosporidium Parvum by Silica Coated with Functionalized Self-Assembled Monolayers
Authors: Majewski Peter J. , Chan Chiu Ping
Published: April 2020

This study focuses a novel method to remove the human pathogens cryptosporidium parvum from water by silica particles coated with functionalized self-assembled monolayers. The results of this investigation clearly show that the pathogen can efficiently and completely be removed at pH
ranges of drinking water by stirring the coated particles in the contaminated water for up to 60 min and finally filtrating the powder. The removal is believed to be caused by electrostatic attraction and immobilization of pathogen on the surface of the particles. At higher pH vales, even
chemisorption may occur.
Growth and Luminescence of N Doped TiO2 Nanowires
Authors: Maestre D. , Cremades A. , Gregoratti L. , Piqueras J.
Published: April 2020

Titanium oxide nanowires have been grown by thermal treatment of pressed TiN powder under argon or N2 flow. It has been found that two-step treatments at two different temperatures, 400 °C and 800 °C, lead to the growth of nanowires all over the sample surface. The
nanowires are of single crystalline rutile structure. Energy dispersive X-ray spectroscopy and photoelectron spectroscopy measurements show that the oxide nanostructures contain N from the starting nitride. The mechanism of N incorporation into the oxide and its possible effect on the luminescence
are discussed.
Kinematic Study of Refraction Properties of a ZnSe-ZnTe Dielectric Grating
Authors: Reyes J. C. Salcedo
Published: April 2020

The plane wave expansion method is applied to determine the thickness of the ZnSe-ZnTe slabs in a semi-infinite dielectric grating in such a way that the maximum reflectivity of the system is obtained. In this way the potential of the ZnSe-ZnTe system for applications in CdSe ultra
thin quantum well based monolithic II–VI Vertical Cavity Surface Emitting Laser for the green spectral region is demonstrated. A kinematic analysis of the thickness-dependent refraction at the boundary between a ZnSe-ZnTe semi-infinite one dimensional photonic crystal and a homogeneous
material in transverse magnetic polarization and oblique incidence case is presented.
Ti, Ni and TiNi Nanoparticles Physically Synthesized by Ar+ Beam Milling
Authors: Castro A. Torres , Cuéllar E. López , Yacamán M. José , Méndez U. Ortiz
Published: April 2020

When the size of a particle decreases around 100 nm or less, there is a change in properties from those shown in the bulk material. In this work ∼3 nm nanoparticles of Ni, Ti and TiNi bimetallic are produced using physical vapor deposition (PVD). Nanoparticles are characterized
by High Resolution Transmission Electron Microscopy (HRTEM), High Angle Annular Dark Field (HAADF), Electron Diffraction (ED). The results show that all nanoparticles maintain the same crystal structure of bulk material but a change in their lattice parameter is produced.
Severe Historical Droughts Carved on Rock in the Yangtze
Authors: Qin Jun , Shi Ailin , Ren Guoyu , Chen Zhenghong , Yang Yuda , Zou Xukai , Zhang Panfeng
Published: April 2020

The White Crane Ridge (WCR) Rock Fish, now submerged under the backwater of the Three Gorges Reservoir in the Yangtze River, are affirmed as one of the earliest hydrologic observations ever made in any large river in the world. The usually in-water monument provides highly valuable historical records of severe droughts in the upper Yangtze over the last 1,200 years. This article updated the historical drought chronology previously developed based on the WCR inscriptions, which can be applied in assessment of extreme climatic and hydrological risks, and also made a preliminary analysis of changes of the severe drought frequency during the last thousand years in the upper Yangtze. The analysis shows that the severe droughts occurred more frequently during the Medieval Climate Anomaly (MCA), relatively less so during the Little Ice Age (LIA), and once again more often under the background of modern global warming. It was suggested that a generally warmer Euro-Asian continent during the MCA was in favor of the stronger East Asian summer monsoon, and the resulting less precipitation and more severe droughts of the Yangtze and the lower water level at the Three Gorges area on the centennial scale, and vice versa for the period of the LIA. The results would help in understanding the causes and mechanisms of the regional climate change and variability, and also in taking measures in the fields of the watershed management to cope with the long-term change in climatic and hydrologic droughts.
Toward Monitoring Short-Term Droughts Using a Novel Daily Scale, Standardized Antecedent Precipitation Evapotranspiration Index
Authors: Li Jun , Wang Zhaoli , Wu Xushu , Xu Chong-Yu , Guo Shenglian , Chen Xiaohong
Published: April 2020

Recent events across many regions around the world have shown that short-term droughts (i.e., daily or weekly) with sudden occurrence can lead to huge losses to a wide array of environmental and societal sectors. However, the most commonly used drought indices can only identify drought at the monthly scale. Here, we introduced a daily scale drought index, that is, the standardized antecedent precipitation evapotranspiration index (SAPEI) that utilizes precipitation and potential evapotranspiration and also considers the effect of early water balance on dry/wet conditions on the current day. The robustness of SAPEI is first assessed through comparison with two typical monthly indices [Palmer drought severity index (PDSI) and standardized precipitation evapotranspiration index (SPEI)] and soil moisture, and then applied to tracking short-term droughts during 1961–2015 for the Pearl River basin in south China. It is demonstrated that SAPEI performs as well as SPEI/self-calibrating PDSI at the monthly scale but outperforms SPEI at the weekly scale. Moreover, SAPEI is capable of revealing daily drought conditions, fairly consistent with soil moisture changes. Results also show that many of the historical short-term droughts over the Pearl River basin have multiple peaks in terms of severity, affected area, and intensity. The daily scale SAPEI provides an effective way of exploring drought initiation, development, and decay, which could be conducive for decision-makers and stakeholders to make early and timely warnings.
Sensitivities of the WRF Lightning Forecasting Algorithm to Parameterized Microphysics and Boundary Layer Schemes
Authors: McCaul Eugene W. , Priftis Georgios , Case Jonathan L. , Chronis Themis , Gatlin Patrick N. , Goodman Steven J. , Kong Fanyou
Published: April 2020

The Lightning Forecasting Algorithm (LFA), a simple empirical procedure that transforms kinematic and microphysical fields from explicit-convection numerical models into mapped fields of estimated total lightning flash origin density, has been incorporated into operational forecast models in recent years. While several changes designed to improve LFA accuracy and reliability have been implemented, the basic linear relationship between model proxy amplitudes and diagnosed total lightning flash rate densities remains unchanged. The LFA has also been added to many models configured with microphysics and boundary layer parameterizations different from those used in the original study, suggesting the need for checks of the LFA calibration factors. To assist users, quantitative comparisons of LFA output for some commonly used model physics choices are performed. Results are reported here from a 12-member ensemble that combines four microphysics with three boundary layer schemes, to provide insight into the extent of LFA output variability. Data from spring 2018 in Nepal–Bangladesh–India show that across the ensemble of forecasts in the entire three-month period, the LFA peak flash rate densities all fell within a factor of 1.21 of well-calibrated LFA-equipped codes, with most schemes failing to show differences that are statistically significant. Sensitivities of threat areal coverage are, however, larger, suggesting substantial variation in the amounts of ice species produced in storm anvils by the various microphysics schemes. Current explicit-convection operational models in the United States employ schemes that are among those exhibiting the larger biases. For users seeking optimum performance, we present recommended methods for recalibrating the LFA.
Friedman at 50: Is It Still the Social Responsibility of Business to Increase Profits?
Authors: Ramanna Karthik
Published: April 2020

Fifty years ago Milton Friedman famously argued that the social responsibility of business is to increase its profits, which today are at record highs. And, as public institutions falter, business is now offering to step into the void. We must resist this (further) intrusion of business into the public sphere, as it will further depreciate civic institutions. The business of business is business, and so it should be. Business’ track record in public politics has been to engineer the rules of the game to its own advantage.
Théorisation du spirituel à partir de l’analyse de pratiques des Intervenants en soins spirituels au Québec : un modèle original à six dimensions
Authors: Cherblanc Jacques , Jobin Guy
Published: April 2020

Ce texte présente une partie des résultats d’une recherche menée auprès des Intervenants et intervenantes en soins spirituels du Québec (ISS) qui travaillent dans les établissements de santé et de services sociaux du Québec. Il présente l’analyse des récits de pratique et de journées typiques de 23 ISS aux profils et pratiques diversifiés. Les ISS sont les successeurs des aumôniers ou animateurs de pastorale hospitalière, aussi appelés chaplains, et ont pour particularité de devoir offrir des services de soins spirituels à tout usager de l’institution de santé, quelle que soit son appartenance ou non à une organisation religieuse. C’est ainsi qu’ils offrent un accompagnement « spirituel » et non « religieux », cette distinction étant fondamentale pour eux. Or, pour démontrer leur pertinence et leur « utilité », les ISS doivent actuellement faire montre de la particularité de leur travail d’accompagnement spirituel (par rapport à la psychologie ou au travail social, par exemple), mais aussi de leur capacité à le faire quelles que soient les croyances du patient. Pour ce faire, ils ont élaboré un savoir pratique, basé sur leur expérience auprès des patients et des soignants, et ont, pour ce faire, élaboré une théorisation du spirituel pratiqué, présentée dans cet article. Cette théorie du spirituel pratiqué qui émerge de la pratique des ISS est constituée de six dimensions : les rituels, l’appartenance, les valeurs, la transcendance, l’identité et le sens.
Disaggregating “China, Inc.”: The Hierarchical Politics of WTO Entry
Authors: Tan Yeling
Published: April 2020

How does state structure affect responses to globalization? This article examines why some parts of the Chinese state enacted more liberalizing policies than others in response to World Trade Organization (WTO) entry. It shows that, despite single-party rule, China’s WTO-era policy trajectories were neither top-down nor monolithic. Instead, central and subnational governments diverged in their policy responses. The study identifies three competing economic strategies from which these responses are drawn: market-replacing (directive), market-shaping (developmental), and market-enhancing (regulatory). The analysis uses an original dataset of Chinese industry regulations from 1978 to 2014 and employs machine learning methods in text analysis to identify words associated with each strategy. Combining tariff, industry, and textual data, the article demonstrates that the divergent strategies adopted by central and subnational governments are driven by each unit’s differential accountability to the WTO and by the diversity of that unit’s industrial base.