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The optical properties of InGaN/GaN green light-emitting diodes (LEDs) with an undoped graded short-period superlattice (GSL) and a Si-doped GSL (SiGSL) were investigated using photoluminescence (PL) and time-resolved PL spectroscopies. For comparison, an InGaN/GaN conventional LED (CLED) without the GSL structure was also grown. The SiGSL sample showed the strongest PL intensity and the largest PL peak energy because of band-filling effect and weakened quantum- confined stark effect (QCSE). PL decay time of SiGSL sample at 10 K was shorter than those of the CLED and GSL samples. This finding was attributed to the oscillator strength enhancement by the reduced QCSE due to the Coulomb screening by Si donors. In addition, the SiGSL sample exhibited the longest decay time at 300 K, which was ascribed to the reduced defect and dislocation density. These results indicate that insertion of the Si-doped GSL structure is an effective strategy for improving the optical properties in InGaN/GaN green LEDs.

An alternative catalytic method was employed using the reduction of Pd ions on the surface of cetyltrimethylammonium bromide (CTAB) treated laponite to initiate the electroless plating of copper; the deposition features of the Pd nanoparticles produced were investigated in detail. Results indicated intercalation and reduction of Pd nanoparticles occurred at room temperature and involved interaction between the laponite and the cetyltrimethylammonium cationic templates. Organic species and amount on laponite were optimized to adjust silicate platelet interlayer distances and platelet organophilic properties. Intercalation of Pd nanoparticles occurred between the magnesium silicate layers of laponite and this was dependent on pre-treatment and impregnation times. As impregnation is a method of producing heterogeneous catalysts, we considered Pd nanoparticles on laponite templates could catalyze the electroless deposition of Cu to initiate metallization. Cu films fabricated on laponite templates exhibited excellent surface roughness (˜1.7 nm) and low resistivity (˜3.42 μ Ω). The devised approach enabled the facile formation of a network suitable for Cu metallization without causing substrate damage and produced metal surfaces with excellent flatness and resistivity.

The TiO₂/Sr4Al 14 O25:Eu 2+ ,Dy 3+ photocatalytic composite was prepared by depositing the nano-crystalline titanium dioxide layer on the long-lasting phosphor substrate of strontium aluminate, using a low-pressure chemical vapor deposition (LP-CVD). The photocatalysis characteristic was studied by examining the photodegradation of benzene (C 6 H 6 ) gas under UV, visible light illumination, and in the darkness. The photocatalytic composite of TiO₂-deposited Sr₄Al 14 O 25 :Eu 2+ ,Dy 3+ showed an active photocatalytic reactivity under UV-light as well as visible-light illumination. The mechanism of the photocatalysis reaction for the TiO₂-deposited strontium aluminate phosphor composite was interpreted in point of the energy band structure and phosphorescent emission. The coupling of nanocrystalline TiO₂ with the strontium aluminate phosphor might result in an energy band bending at the interface of TiO₂/Sr₄Al 14 O 25 :Eu 2+ ,Dy 3+ , making the titanium dioxide at the junction to be photo-reactive even in a visible wavelength region. In addition, the depth profile of Auger electron spectroscopy (AES) confirmed a possible formation of oxygen vacancies at the interface between TiO₂ and Sr₄Al 14 O 25 :Eu 2+ ,Dy 3+ . Then, oxygen defects create extra electrons which may excited subsequently to the conduction band and participate in a photocatalytic reaction, resulting in an enhancement of the photodecomposition of benzene. The LP-CVD TiO₂-strontium aluminate phosphor was also photoactive in the darkness because of light emission from the long lasting phosphor. Also, the TiO₂-deposited Sr₄Al 14 O 25 :Eu 2+ ,Dy 3+ long lasting phosphor was analyzed by a XRD (X-ray diffraction), TEM (transmission electron microscopy), UV/visible spectroscopy and AES.

Indium tin oxide (ITO) nanoparticles were coupled with NaYF4:(Gd, Si) using a TiO₂-solution impregnation method. Scanning electron microscopy confirmed that TiO₂ and ITO nanoparticles were loaded on the surface of the NaYF4:(Gd, Si) upconversion phosphor. The ultraviolet/visible spectra of the 20 wt.% ITO-NaYF4:(Gd, Si)/TiO₂ composites were extended at the absorption edges towards the UV-visible region. The 20 wt.% ITO-coupled NaYF4:(Gd, Si)/TiO₂ composites exhibited superior photocatalytic efficiency compared to only NaYF4:(Gd, Si)/TiO₂ under near-infrared (NIR) irradiation. Multi-wavelength NIR photons of γ > 760 nm from a Xe solar simulator source induced photo-activation through the NaYF4:(Gd, Si) activator centers. The three-cycle photocatalytic reusability performance of the 20 wt.% ITO-impregnated NaYF4:(Gd, Si)/TiO₂ composite was positively enhanced by up to 20% more than that of NaYF4:(Gd, Si)/TiO₂.

Copper has unique properties, such as low electrical resistivity, that are exploited in a number of applications, including an interconnect layer in integrated circuits and microelectronic devices. Etching techniques are essential for the fabrication of fine structures, devices, and circuits. This article addresses the methods of copper etching with an emphasis on approaches using ferric nitrate. Potentiodynamic polarization tests using benzotriazole as an inhibitor showed that ferric nitrate has higher inhibition efficiency than conventional etchants. This is because benzotriazole in a ferric nitrate solution is adsorbed on the copper surface to a greater extent than in a ferric chloride and cupric chloride solution, as confirmed by Fourier transform infrared analysis. Quantitative atomic force microscopy characterization showed that good surface quality with significantly lower surface roughness can be obtained from a copper film etched in a ferric nitrate solution, which has potential use in microelectronics manufacturing.

Nanomaterials with enzyme-like characteristics (nanozymes) have emerged as potential replacements for natural enzymes due to their potential to overcome several critical limitations of natural enzymes, including low stability as well as high costs in preparation and purification. Herein, we have developed hybrid nanostructures that incorporate cobalt oxide nanoparticles (Co₃O₄ NPs) and gold nanoclusters (AuNCs) through electrostatic attraction induced by simple incubation in an aqueous buffer for 2 hours. Owing to the synergistic effect of Co₃O₄ NPs and AuNCs, the constructed Co₃O₄/Au hybrid nanostructures yielded highly enhanced peroxidase-like activity and enabled rapid catalytic oxidation of a chromogenic substrate, 3,3',5,5'-tetramethylbenzidine (TMB), producing a blue colored solution depending on the amount of H₂O₂. Moreover, we observed catalytic activity of the Co₃O₄/Au hybrid over a broad pH range, especially at physiologically relevant pH in the range of 5.0-7.4, which is advantageous for applications in biological systems. Using the hybrid as peroxidase mimic, we successfully determined the level of target H₂O₂ or glucose by coupling with glucose oxidase with excellent specificity and sensitivity. Based on this study, we expect that Co₃O₄/Au hybrid nanostructures can serve as potent peroxidase mimics for the detection of clinically important target molecules.

The Fe-Ni oxide bimetallic nanoparticles (FNOBNPs) were synthesized in the liquid phase plasma (LPP) method employed an iron chloride and nickel chloride as metal precursors. The sphericalshaped FNOBNPs were synthesized by the LPP process and, the size of particles was growing along with the progression of LPP reaction. The synthesized FNOBNPs were comprised of Fe₃O₄ and NiO. Iron had a higher reduction potential than nickel and resulted in higher iron composition in the synthesized FNOBNPs. The control of molar ratio of metal precursors in initial reactant solution was found that it could be employed as a means to control the composition of the elements in FNOBNP.

Surface modification of SiO₂ supports was shown to significantly affect the properties of Pd/SiO₂ catalysts. The surface of SiO₂ can be modified by various pretreatment methods. In this study, the effect of different calcination temperatures on support surface was investigated. Pd supported on pretreated SiO₂ was characterized by H2 temperature-programmed reduction (TPR), XRD, CO chemisorption measurements, and field-emission transmission electron microscopy (FE-TEM). The silanol group (-OH), which is one of the functional groups of SiO₂, interferes with the reduction of palladium because it strongly bonds with palladium ions (-PdO) during the preparation of the catalyst. Due to the complete removal of silanol (Si-OH) groups following calcination at 700 °C, the metal reducibility was enhanced, and the catalyst pretreated at this calcination temperature exhibited the highest metal dispersion of 13.02%. Further, to confirm the catalytic activity of the prepared catalysts, hydrogenation of D-glucose was conducted. The HPLC results demonstrated that Pd/SiO₂_700 has the highest catalytic activity toward hydrogenation of D-glucose. Therefore, it was confirmed that the removal of silanol groups increase the metal dispersion and catalytic activity of Pd/SiO₂ catalyst.

Monoacrylate-poly(ethylene glycol) grafted poly(3-hydroxyoctanoate) (PEGMA- g -PHO) copolymer was obtained by UV irradiation and ibuprofen (IBU) loaded nanoparticles with PHO or PEGMA- g -PHO polymers were successfully prepared by a single emulsion process. Size of IBU-loaded nanoparticles was about 300 nm based on particle size measurement. Their shapes were spherical. To study drug release properties, IBU release from nanoparticles were performed with FBS buffer. Higher burst release of IBU was observed with the highest graft density of PEGMA groups and 100% drug release was found in 3, 6, and 12 days for PHO, PEGMA- g -PHO0.05, and PEGMA- g -PHO0.15, respectively. Our results suggest that hydrophobic PHO and more hydrophilic PEGMA- g -PHO could be regarded as good candidates of drug release carriers.

The increasing role of catalysis by noble metals coupled with their high price requires the development of cheaper and more effective catalysts, e.g., highly dispersed supported catalyst. Herein, Pd supported on Al2O3 catalysts prepared by deposition-precipitation under different conditions were subjected to X-ray diffraction, N2-physisorption, NH3/CO2 temperature programmed desorption, CO-chemisorption, and field-emission transmission electron microscopy analyses, which revealed that the size and distribution of Pd particles were influenced by Al2O3 support type (particle size and phase transition) and preparation conditions (metal precursor type, pH value, and solution temperature). The Pd/Al2O3 catalysts were prepared using type A (particle size = 3 micron) or type B (particle size = 20 nm) as a support and PdCl2 (PC) or Pd(NO3)2·2H2O (PN) as a Pd precursor, respectively. In XRD results, type A (particle size = 3 micron) Al2O3 had γ and  phase, and type B (particle size = 20 nm) Al2O3 had only thermally stable γ phase. In addition, Pd dispersion and crystallite size showed an obvious dependence on pH value, solution temperature and attractive/repulsive forces between the functional groups of Al2O3 and Pd precursors. Optimal results were obtained using PdCl2 (PC) as a Pd precursor and type B (particle size = 20 nm) as a support at 60 °C and pH 5.5.

Zinc oxide/activated carbon nanocomposites were synthesized by impregnating zinc oxide nanoparticles onto activated carbon powder using liquid phase plasma (LPP) method. Zinc oxide nanoparticles on the surface of activated carbon were fabricated rapidly by the LPP method due to reducing the zinc ion in aqueous solution. The obtained zinc oxide/activated carbon nanocomposites were characterized by XPS, HRTEM, and EDS. The amount of zinc oxide nanoparticles impregnated increased with increasing initial precursor concentration. Approximately 150~300 nm sized spherical shaped nanoparticles were uniformly dispersed on the surface of activated carbon powder.

Graphite-SiO2-TiO2 composites with optimum graphite and SiO2 loadings were prepared by a facile one-pot chemical route. The structural, morphological and physiochemical properties of the samples were investigated by analytical techniques. UV-Vis-DRS analysis confirmed light absorbance edge of composites was sharply red-shifted to the visible region with increasing graphite and SiO2 content. The prepared composites showed higher photocatalytic activity towards degradation of benzene gas under visible light. The contribution of graphite and SiO2 on the enchantment of visible light photocatalytic performance of the composites was discussed.

Polyurethane (PU) foams with controlled porosity and pore structure are prepared via judicious study on expanding process parameters for thermoplastic expandable microspheres which are compatible with PU synthetic process. Thermal and mechanical properties of PU foams are found to be generally governed by amount of the porosity. Thermal conductivity of PU foams with controlled porosity is measured at 30 °C with transient hot bridge method. The measured thermal conductivity of PU foams is estimated using theoretical models, proving the formation of spherical pore structures of expandable microspheres in PU matrix and serving as an internal porous material.

The liquid phase plasma (LPP) synthetic process has been exploited to synthesize nickel oxide nanoparticles doped TiO2 photocatalyst (NOTP) that can respond to visible light. The physicochemical properties of NOTPs were studied by several analysis instruments. The nickel oxide nanoparticles precipitated uniformly on the TiO2 powder are mostly NiO. The band gap energy of the NOTP measured was 2.99 eV, which was smaller than that of bare TiO2, 3.12 eV. The NOTP synthesized in this work showed high photoactivity under visible blue light.

The estrogenicity of octyl glucoside was studied with its preparation method using microporous zeolites. Its estrogenicity was estimated using E-assay method to confirm the possibility as non-endocrine disruptive surfactant. The octyl glucoside was synthesized from D-glucose with 1-octanol by direct glucosidation. The high conversion of D-glucose was obtained on H-FAU zeolite which has a mild acid strength. The conversion and yield were improved with increasing of acid site amount of the zeolite catalysts. The octyl glucopyranoside is more hydrophilic than nonylphenol and has a high wettability. The octyl glucosides represented extremely lower estrogenic cell proliferation compared with nonylphenol.

Here we describe the synthesis of polyurethane (PU)-based energetic nanocomposites loaded with nano-aluminum (n-Al) particles. The energetic nanocomposite was prepared by polyurethane reaction of poly(glycidyl azide-co-tetramethylene glycol) (PGT) prepolymers and IPDI/N-100 isocyanates with simultaneous catalyst-free azide-alkyne Click reaction in the presence of n-Al. Initial study carried out with various n-Al/fluorinated PGT blends and demonstrated the potential of fluorinated PGT prepolymer for an energetic PU matrix. Thermal analysis of n-Al/fluorinated PGT-based PU energetic nanocomposite was performed using DSC and TGA.

This paper proposes Fiber-Optic Localized Surface Plasmon Resonance (FO LSPR) sensor combined with a micro fluidic channel, which enables continuous supply of fluid for bio-reaction. The proposed method prevents degradation of the sensing performance due to changes in measurement conditions. The feasibility of the FO LSPR sensor with a micro fluidic channel was demonstrated by computational fluid dynamics (CFD) simulation. Also, the proposed method was assessed by measuring the output intensity of the FO LSPR sensor at various refractive index solutions. Finally, a prostate-specific antigen (PSA) immunoassay was performed to evaluate the possibility of the fabricated sensor system as a biosensor.

The nanotopological cues are emerging field of in vivo study, because it stimulates alteration of cell morphology and cell behavior such as adhesion, proliferation, differentiation, apoptosis and migration. However, it has not studies nanosurface affected cancer cell behavior, therefore, in this study, we determined that effects the silica nanobeads used as nanotopological tools on cancer cells. For synthesis of silica beads, we made it using stober method and basic amino acid (L-arginine) instead of NH4OH. We carried out rubbing beads to obtain the monolayer silica beads and it used as nanotopological cues for fabrication. It was induced changing cell morphology at 1DIV in group-II (SB-450 and SB-570). However, it was maintained in group-I (SB-118, SB-230) and group-III (SB-1450) like control. Therefore, we separated type-I and type-II surface along with area of cell adhesion and morphology. The characteristic of type-II surface was long distance between contact points, resulting in increase of tension to cells. We found that the morphology rounded up by type-II surface at 1DIV. We described that the nanosurface-induced mechanical tension is associated with alteration of morphology, thus the silica nanobeads used as nanotopological tools for cancer research.

The hybrid material consisting of multi walled carbon nanotubes (MWNTs) and poly(2-hydroxyethylmethacrylate-co-methylmethacrylate) [poly(HEMA-co-MMA)] was synthesized by a combination of RAFT and Click chemistry. In the primary stage, the copolymer poly(HEMA-co-MMA) was prepared by applying RAFT technique. Alkynyl side groups were incorporated onto the poly(HEMA-co-MMA) backbone by esterification reaction. Then, MWNTs-N3 was prepared by treating MWNTs with 4-azidobutylamine. The click coupling reaction between azide-functionalized MWNTs (MWNTs-N3) and the alkyne-functionalized random copolymer ((HEMA-co-MMA)-Alkyne) with the Cu(I)-catalyzed [3+2] Huisgen cycloaddition afforded the hybrid compound. The structure and properties of poly(MMA-co-HEMA)-g-MWNTs were investigated by FT-IR, EDX and TGA measurements. The copolymer brushes were observed to be immobilized onto the functionalized MWNTs by SEM and TEM analysis.

This paper presents a comparative study on thermal conductivity of PU composites containing open-cell nano-porous silica aerogel and closed-cell hollow silica microsphere, respectively. The thermal conductivity of PU composites is measured at 30 degrees C with transient hot bridge method. The insertion of polymer in pores of silica aerogel creates mixed interfaces, increasing the thermal conductivity of resulting composites. The measured thermal conductivity of PU composites filled with hollow silica microspheres is estimated using theoretical models, and is in good agreement with Felske model. It appears that the thermal conductivity of composites decreases with increasing the volume fraction (phi) when hollow silica microsphere (eta = 0.916) is used.

Few layer graphene sheets were synthesized from natural graphite through mechanical shear mixer in 1-butanol as solvent. The liquid phase exfoliation of graphite through the shear mixer generated incising forces for 20 minutes which changed the large amount of graphite's flake into few layer graphene. The removal of solvent from the deposited dispersion was performed immediately by keeping at the room temperature. The deposited graphene thin films were characterized by AFM, HR-TEM, XRD, FT-IR and Raman Spectroscopy. The HR-TEM results showed the formation of few layers and well dispersed graphene. The Raman spectroscopy and XRD characterization confirmed the good quality and non-oxidized state of graphene.

In addition to the development of extreme ultraviolet lithography (EUVL), studies on beyond extreme ultraviolet lithography (BEUVL), which uses radiation with a wavelength of 6.7 nm, are in progress for their application in high-volume manufacturing. The BEUV wavelength, which is much shorter than the EUV wavelength, improves the resolution of patterned features. However, suitable materials for the mask stack of BEUVL are still under development. In this study, the applicability of metallic materials, such as Ni, Co, Ir, W, and Ta, as the absorber in a binary-intensity BEUVL mask was evaluated. The mask-imaging properties were simulated by adopting a thickness that ensured a reflectivity of <1% for each material. Furthermore, we used a multilayered La/B mirror--which exhibited a high reflectivity at a wavelength of 6.7 nm--because BEUV light is absorbed by most materials, and therefore uses reflective optics as desired. The numerical aperture (NA), angle of incidence, and demagnification factor were 0.5 and 0.6, 6 degrees, and 8x, respectively. We confirmed that a line-and-space pattern with a half-pitch of 11 nm can be patterned with metallic absorbers by using a high NA.

The aim of this work is to be compared the effect of supports textural properties with pre-treatment method on dispersion of Pd particle. The CNTs were functionalized by different concentration of acid in order to obtain materials with different chemical and physical properties. The characteristics of functionalized CNTs were investigated by FT-IR and Rama spectropy. The Pd/CNTs catalysts prepared on support having the different surface properties were characterized by XRD, FE-TEM and CO-chemisorption. When pretreated 8M concentration, the CNTs has the highest amount of oxygen functional group and ID/IG ratio, in this study. Pd/CNT8M has high dispersion and small particle size. From these results, we confirmed that characteristics of Pd/CNTs catalyst such as particle size and dispersion of Pd are influenced by density of oxygen functional group and disorder of CNTs. And we have observed that acid treatment concentration of 8M is sufficient to functionalize the CNTs by introducing -COOH group of CNTs surfaces.

This work is focused on spectroscopically characterizing kinetic properties of concentric quantum-ring complexes of GaAs quantum dots. Quantum-ring (or double-ring) GaAs quantum dots, embedded in an Al0.3Ga0.7As barrier layer, were grown by a droplet epitaxy method during molecular beam epitaxy on a GaAs (001) substrate. Emission peaks of photoluminescence spectra with different excitation power, were measured as 702 nm at 0.17 mW and 690 nm at 400 mW, were blue-shifted as the excitation power increased. In addition, excitation laser power dependence of time-resolved photoluminescence of double-ring GaAs quantum dots at 10 K under 400 nm excitation wavelength was performed, revealing that photoluminescence lifetime slowly decreased in comparison to that of single disc-like quantum dots as excitation power increased, implying that carrier transfer between inner ring and outer ring could slow down the decay process. The luminescence lifetime at 10 K increased from 245 to 409 ps in the range from 0.17 to 400 mW of excitation power.

Hybrid materials of β-cyclodextrin multi-decorated halloysite nanotubes (HNTs-g-βCD) were prepared by a facile route, which showed high efficiency for catalysis and dye adsorption. Initially, the surface of halloysite nanotubes (HNTs) was modified with poly(glycidyl methacrylate) by the reversible addition fragmentation chain transfer (RAFT) polymerization of glycidyl methacrylate having epoxy groups as a monomer. Subsequently, β-cyclodextrin was conjugated with the modified HNTs to produce HNTs-g-βCD by the epoxide ring-opening reaction of mono-6-deoxy-6-hexanediamine-β-cyclodextrin. The nanocomposites were characterized by FT-IR, TGA, SEM, and TEM. The HNTs-g-βCD composites could be used as a nano adsorbent for methylene blue and a catalyst in the oxidation reaction of benzyl alcohol owing to the unique structure of β-cyclodextrin. The HNTs-g-βCD shows promiseas potential multi-functional materials by a combination of β-cyclodextrin and HNTs properties.

The removal of boron is one of the main challenges in the purification of metallurgical grade silicon destined for low-cost photovoltaic applications. However, boron is very difficult to remove in its elemental form due to its large segregation coefficient in silicon and its low vapor pressure. The removal of boron by slag treatment is today regarded as a highly promising method, but its refining efficiency is relatively low. Also, the reduction of boron by plasma treatment exhibits a high refining efficiency, but the processing cost is high due to the large amount of electricity consumed by the process. In this regard, the use of an oxidizing reactive gas in the refinement process offers some advantages both in terms of low energy consumption and promising refinement rates. Boron can be extracted in various gaseous forms as B(x)O(y) and/or B(x)H(z)O(y) phases, but the vapor pressure of B(x)H(z)O(y) is much greater than that of the other specie at a temperature of 1700 K. The present study reports a modified oxidative refining method designed to enhance the vaporization of boron as B(x)H(z)O(y) by blowing gaseous water onto the silicon melt in a segmented crucible to enhance the electromagnetic force, whereby the processing cost can be dramatically reduced due to the use of a reusable quartz crucible in a graphite crucible. An initial boron content of 13 ppm in the metallurgical grade silicon was significantly decreased to 0.3 ppm by the employment of 1.7SLM Ar + 100 ml/h H2O. Also, a mechanism capable of reducing boron based on thermodynamic considerations is proposed.

This work describes a self-assembly method of gold nanoparticles coating on the surface of silicon thin films for the anode material of lithium secondary batteries. The preparation of the silicon thin films was carried out by electron cyclotron resonance metal organic chemical vapor deposition (ECR-MOCVD) process. The obtained films were further coated with (3-aminopropyl)-trimethoxysilane (APTMS) which has a role to bind the oxygen functional groups on Si surface and the gold nanoparticles. The dispersed gold nanoparticles on the surface of silicon thin films could be prepared due to self-assembly phenomena which interact between attraction and repulsion in gold nanoparticles colloidal solution (GNCS). The use of reducing agent of sodium citrate and tannic acid in GNCS significantly affected the size of gold nanoparticle in our experimental range. Based on our experimental results, the higher reversible capacity was exhibited for the silicon that was immersed in the GNCS consisted of only sodium citrate. The GNCS consisted of both sodium citrate and tannic acid produced severe coagulated nanoparticles when deposited on the silicon surface and thus inhibited the lithium movement from electrolyte to silicon surface. Consequently, the reversible capacity of silicon anode material with coagulated gold nanoparticles coating showed the reduced performance.

We investigated the effect of Cu alloying on S poisoning of Ni surfaces and nanoparticle morphologies using ab-initio thermodynamics calculations. Based on the Cu segregation energy and the S adsorption energy, the surface energy and nanoparticle morphology of pure Ni, pure Cu, and NiCu alloys were evaluated as functions of the chemical potential of S and the surface orientations of (100), (110), and (111). The constructed nanoparticle morphology was varied as a function of chemical potential of S. We find that the Cu added to Ni for NiCu alloys is strongly segregated into the top surface, and increases the S tolerance of the NiCu nanoparticles.

We report the influences of a Si-doped graded superlattice (SiGSL) on the electrostatic discharge (ESD) characteristics of an InGaN/GaN light-emitting diode (LED). For comparison, a conventional InGaN/GaN LED (C-LED) was also investigated. The luminous efficacy for the SiGSL-LED was 2.68 times stronger than that for the C-LED at the injection current of 20 mA. The resistances estimated from current-voltage (I-V) characteristic curves were 16.5 and 8.8 Ω for the C-LED and SiGSL-LED, respectively. After the ESD treatment at the voltages of 4000 and 6000 V, there was no significant change in the I-V curves for the SiGSL-LED. Also, there was small variation in the I-V characteristics for the SiGSL-LED at the ESD voltage of 8000 V. However, the I-V curves for the C-LED were drastically degraded with increasing ESD voltage. While the light emission was not observed at the injection current of 20 mA from the C-LED sample after the ESD treatment, the emission spectra for the SiGSL-LED sample were clearly measured with the output powers of 10.47, 9.66, and 7.27 mW for the ESD voltages of 4000, 6000, and 8000 V respectively.

In this paper, we propose interface engineering between cadmium selenide/zinc sulfide (CdSe/ZnS) quantum dots (QDs) as the emissive layer (EML) and ZnO nanocrystals (NCs) as the electron transport layer (ETL) for reducing the potential barrier in QDs based light-emitting diode (QLED). The n-type ZnO NCs were effective in confining charge to the QDs EML because of their wide band gap. The ZnO NCs were synthesized using a modified sol-gel process and were applied as the ETL in QLED. For comparison, a standard QLED with Tris(8-hydroxyquinolinato)aluminium as the ETL was also fabricated. The standard QLED was shown to have a luminance of 11,240 cd/m2 and current efficiency of 2.3 cd/A. However, QLED with ZnO NCs showed a higher luminance of 28,760 cd/m2 and current efficiency of 4.9 cd/A than the reference structure, and so has more efficient charge transport. Thus, QLED with ZnO NCs not only simplified the process, but also enhanced the luminance and current efficiency by factor of two.

Pyrolytic carbon coated silicon is prepared and employ it as an anode material for lithium secondary batteries. The pyrolytic carbon coating of silicon with sucrose precursor not only provides a suitable carbon matrix but also suppresses the breaking away of Si from the current collector during the insertion and extraction of Li+. The increase of disordered carbon content leads to the increase of discharge capacity retention. The improvements of cycle stability are attributed to a decrease in the volume change of the silicon, good networking between Si particles, and good adhesion of the current collector with the active material. The nano Si combined with the disordered carbon leads to an increase of capacity retention and initial coulombic efficiency.

The electrical characteristics of quantum dots (QDs) can vary depending on the surface modulation, which can change the luminance and efficiency of electroluminescent devices. Thus, understanding surface ligand is essential in improving the performance of QDs-based light-emitting diodes (LEDs). We analyzed the performance of QDs-based LEDs with respect to the QD surface volume. On the QD surfaces, the 1.1 nm-long tryoctylphosphine oxide (TOPO) ligand with three neck-type structure was replaced with a 1.7 nm-long oleic acid (OA) ligand with a one neck-type structure to evaluate the dependence of the LED properties on the ligand length. With all other conditions being identical, the luminance and efficiency of the QDs-based LEDs with an OA ligand were approximately 1,000 cd/m2 greater and 1.5 times higher, respectively, than those of the QDs-based LEDs with a TOPO ligand. These results show that if the physical length of the surface ligand is relatively long, decreasing the surface area would result in increased injection of electrons and holes into the QDs, increasing the luminance and efficiency.

Pd/C catalysts were prepared by ion exchange in aqueous solution. Physical dispersion methods including sonication, high share mixer and stirrer were used for though high dispersion of carbon. The physical properties of the prepared Pd/C particles were investigated by BET, XRD, and FE-TEM. The dispersion of Pd nanoparticles on carbon was measured on the basis of CO adsorption capacity using a pulse technique. FE-TEM micrographs showed that Pd nano particles possessed a spherical morphology with a narrow size distribution, with particles sizes ranging from 2-25 nm. The Pd particles prepared using sonication and high share mixer are well dispersed compared to the stirrer method. In addition, metal dispersions as calculated by CO uptake were 11.3, 20.4, and 25.0% for the stirrer, sonication and high share mixer methods, respectively.

Succinic acid (SA) produced from hydrogenation of maleic anhydride (MAN) is used widely in manufacturing of pharmaceuticals, agrochemicals, surfactants and detergent, green solvent and biodegradable plastic. In this study, we performed that liquid hydrogenation of MAN to SA with 5 wt% Pd supported on activated carbon (Pd/C) at low pressure and temperature. The synthesis of SA was performed in aqueous solution while varying temperature, pressure, catalytic amount and agitation speed. We confirmed that the composition of the products consisting of SA, maleic acid (MA), fumaric acid (FA) and malic acid (MLA) depends on the process. The catalytic characteristics were analyzed by TGA, TEM.

An MDEL/TiO2 photo-catalyst hybrid system was applied, for the first time, for the production of low molecular weight heparin. The molecular weight of produed heparin decreased with increasing microwave intensity and treatment time. The abscission of the chemical bonds between the constituents of heparin by photo-catalytic reaction did not alter the characteristics of heparin. Formation of by-products due to side reaction was not observed. It is suggested that heparin was depolymerized by active oxygen radicals produced during the MDEL/TiO2 photo-chemical reaction.

The semiconductor nanocrystals (or quantum dots) have shown peculiar optical and electrical properties due to their exceptionally small size. In recent years, tremendous researches on quantum dots have been carried out. Among them, QDs as sensing media for biological assay have achieved a great progress. Recently we have reported the detection of DNAs by using fluorescence quenching of QDs after DNA hybridization. Several oligonucleotides and human genomic genes could be detected. In this report we used dual packing of polystyrene bead-quantum dots to detect different kinds of DNAs simultaneously. QDs with different emission peaks were used. Carboxylated-CdSe/ZnS QDs (emission: 525, 605 nm) could bind to microbeads of polystyrene/divinyl benzene via EDC/NHS cross-linking reaction. Polystyrene bead-QDs with different colors were packed in the channel of the microfluidic chip. The fluorescence quenching from the QDs by intercalating dye was observed after hybridization of exon 6 and 7 of p53 gene at the weir in the channel of microfluidic chip. The simultaneous fluorescence quenching of the QDs by PI and TOTO-3 were observed.

Several researches have shown that cancer is caused by genetic mutations especially in genes involved in cell growth and regulation. Ras family members are frequently found in their mutated, oncogenic forms in human tumors. Mutant RAS proteins are constitutively active, owing to reduce intrinsic GTPase activity and insensitivity to GTPase-activating protein (GAPs). In total, activating mutations in the RAS genes occur in approximately 20% of all human cancers, mainly in codon 12, 13 or 61. Activating mutations in the NRAS gene not only result in the reduction of intrinsic GTPase activity but also in the induction of resistance against molecules inducing such activity. In this paper, we reported a rapid, simple and portable method for detecting the mutant types of NRAS genes codon 12 and 61 simultaneously by using bead-quantum dots (QDs) based multi-channel microfluidic chip. Probe DNAs are conjugated to bead-QDs and packed in the pillars of channels in the microfluidic chip. After injection of target DNAs and intercalating dyes, the fluorescence quenching of QDs by intercalating dye was observed due to FRET phenomena. The platform can be effortlessly applied in other biological and clinical areas.

We report the influences of a dot-in-a-well structure with a thin GaAs layer and the thickness of a waveguide (WG) on the lasing characteristics of InAs quantum dots (QDs) based on InP. The QD laser diodes (QDLDs) consist of seven-stacked InAs QDs separated by a 10 nm-thick InGaAsP (1.15 μm, 1.15Q-InGaAsP) layer, which is further sandwiched by a 800 nm-thick 1.15Q-lnGaAsP WG (reference QDLD). For comparison, the InAs QDs were inserted into the InGaAsP (1.35 μm, 1.35Q-InGaAsP) quantum well embedded in the 1.15Q-InGaAsP matrix at the active layer. And a 2 monolayer (ML)-thick GaAs layer was additionally introduced right before the QD layer (GDWELL-LDs). Lasing emission from the reference QDLD with only the 1.15Q-InGaAsP structure was not observed at room temperature (RT). However, the lasing emission from the GDWELL-LDs was clearly observed at the wavelength of 1.46 μm at RT under continuous-wave (CW) mode. The threshold current density of the GDWELL-LD with the 800 nm-thick InGaAsP WG was measured to be 830 A/cm2, which was lower than that of the GDWELL-LD with the 200 nm-thick WG (900 A/cm2). Also, the slope efficiency of the GDWELL-LD was significantly improved with increasing thickness of the InGaAsP WG.

Sol-gel spin-coating was used to deposit ZnO seed layers onto quartz substrates, and ZnO nanorods doped with various concentrations of B (i.e., BZO nanorods) ranging from 0 to 2.0 at% were hydrothermally grown on the ZnO seed layers. The effects of B doping on the absorption coefficient, optical band gap, Urbach energy, refractive index, extinction coefficient, single-oscillator energy, dispersion energy, average oscillator strength, average oscillator wavelength, dielectric constant, and optical conductivity of the hydrothermally grown BZO nanorods were investigated. The optical band gaps were 3.255, 3.243, 3.254, 3.258, and 3.228 eV for the nanorods grwon at 0, 0.5, 1.0, 1.5 and 2.0 at% B, respectively. B doping increased the Urbach energy from 40.7 to 65.1 meV for the nanorods grown at 0 and 2.0 at% B, respectively, and significantly affected the dispersion energy, the single-oscillator energy, the average oscillator wavelength, the average oscillator strength, the refractive index, and the optical conductivity of the hydrothermally grown BZO nanorods.

To develop physically flexible electronics, high performance and mechanical stability of component materials and devices are required. For a flexible display, a backplane with flexible thin-film transistors (TFTs) must be developed. Gate insulating materials with excellent electrical and mechanical properties are highly important to the development of flexible TFTs. We investigated nanocomposite gate dielectrics composed of polyimide (PI) because of their superior thermal stability, as well as different inorganic HfO2, TiO2, and Al2O3 nanoparticles with high dielectric constants. Nanocomposite gate dielectrics of HfO2 nanoparticles and PI lowered leakage current density and increased the relative dielectric constant compared to PI solely because of a high degree of dispersion. Pentacene TFTs with HfO2 nanocomposite gate insulators also showed higher field-effect mobility (μ), smaller subthreshold swing, and an enhanced on/off current ratio (I(on/off)) compared to those of the PI gate dielectric. In addition, mechanical cyclic bending tests involving bending cycles of 2 x 10(5) time sat a bending radius of 5 mm showed improvement in electrical stability of nanocomposite gate insulators with a change in leakage current density of nanocomposite gate insulators below 30%.

During the several decades, CdO thin film has attracted many attentions as a candidate for the transparent conducting electrodes due to its high electrical conductivity and high optical transmittance. Various dopants such as F, In, Al, Sn, and Cr have been used to improve the optical and electrical properties of the film. Generally, the optical and electrical property of the thin film is dependent on its oxidation state, the amount of dopant materials, and the fabrication process. In this study, fluorine doped CdO thin films were prepared by using sol-gel process with various atomic ratios of Cd:F, and their electrical and optical properties were investigated. The precursor solution for sol-gel film was prepared with pH 5 and pH 8, and the film was annealed at 350 degrees C. X-ray diffraction pattern confirmed the cubic CdO:F phase formation, and the 10% fluorine doped film prepared with pH 8 precursor solution showed the lowest resistivity of 0.01574 Ω cm.

The structural and optical properties of Co-doped ZnO thin films prepared by a sol-gel dip-coating method were investigated. X-ray diffraction analysis showed that the thin films were grown with a c-axis preferred orientation. The position of the (002) peak was almost the same in all samples, irrespective of the Co concentration. It is thus clear that Co doping had little effect on the position of the (002) peak. To confirm that Co2+ was substituted for Zn2+ in the wurtzite structure, optical measurements were conducted at room temperature by a UV-visible spectrometer. Three absorption peaks are apparent in the Co-doped ZnO thin films that do not appear for the undoped ZnO thin film. As the Co concentration was increased, absorption related to characteristic Co2+ transitions increased because three absorption band intensities and the area underneath the absorption wells between 500 and 700 nm increased with increasing Co concentration. The optical band gap and static dielectric constant decreased and the Urbach energy and extinction coefficient increased with increasing Co concentration.

Yttrium-doped ZnO (YZO) nanorods were synthesized by hydrothermal growth on a quartz substrate with various post-annealing temperatures. To investigate the effects of post-annealing on the optical properties and parameters of the nanorods, X-ray diffractometry (XRD), photoluminescence (PL) measurement, and ultraviolet (UV)-visible spectroscopy were used. From the XRD investigation, the full width at half maximum (FWHM) and the dislocation density of the nanorods was found to increase with an increase in the post-annealing temperature. In the PL spectra, the intensity of the near band edge (NBE) emission peak in the UV region also increases with an increase in the temperature of post-annealing. The deep level emission (DLE) peak in the visible region changes with various post-annealing temperatures, and its intensity increases remarkably with post-annealing at 800 degrees C. In this paper, changes in the optical parameters of the nanorods caused by variation in the behavior of Y during post-annealing was investigated, with properties such as absorption coefficients, refractive indices, and dispersion parameters being obtained from transmittance and reflectance analysis.

Hydrothermally grown ZnO nanorods were doped with various concentrations of Sn, ranging from 0 to 2.5 at%. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), ultraviolet (UV)-visible spectroscopy, and Photoluminescence (PL) measurements were used to determine the effect of Sn doping on the structural and optical properties. In the SEM images, the nanorods have hexagonal wurtzite structure and the diameter of the nanorods increases with an increase in the Sn content. The optical parameters of the Sn-doped ZnO (SZO) nanorods such as the absorption coefficients, optical bandgaps, Urbach energies, refractive indices, dispersion parameters, dielectric constants, and optical conductivities were determined from the transmittance and reflectance results. In the PL spectra, the intensity of the NBE peak in the UV region decreases and is blue-shifted with an increase in the Sn content, while the DLE peaks of the nanorods in the visible region shift toward the low-energy region with the introduction of Sn.

This study investigated the photocatalytic behavior of titanium dioxide (TiO2)-supported on the long phosphorescent materials. Nanocrystalline TiO2 was directly deposited on the plate of alkaline earth aluminate phosphor, CaAl2O4: Eu2+, Nd3+ by a low pressure chemical vapor deposition (LPCVD). Photocatalytic reaction performance was examined with the decomposition of benzene gas by using a gas chromatography (GC) system under ultraviolet and visible light (λ > 410 nm) irradiations. The LPCVD TiO2-coated phosphors showed active photocatalytic reaction under visible irradiation. The mechanism of the photocatalytic reactivity for the TiO,-coated phosphorescent phosphor was discussed in terms of the energy band structure and phosphorescence. The coupling of TiO2 with phosphor may result in energy band bending in the junction region, which makes the TiO, crystal at the interface to be photo-reactive under visible light irradiation. The fastest degradation of ben- zene gas occurred for the TiO,-coated phosphor prepared with 1 min deposition time (-150 nm thickness). The LPCVD TiO,-coated phosphor is also photo-reactive under darkness through the light photons emitted from the CaAl2O4 phosphor. In addition, the TiO2-coated phosphorescent phosphors were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Applicability of nonlocal models to nano-beams is discussed in terms of the Eringen's nonlocal Euler-Bernoulli (EB) beam model. In literature, most work has taken the axial coordinate derivative in the Laplacian operator presented in nonlocal elasticity. This causes that the non-locality always makes the beam soften as compared to the local counterpart. In this paper, the thickness scale effect is solely considered to investigate if the nonlocal model can simulate stiffening effect. Taking the thickness derivative in the Laplacian operator leads to the presence of a surface stress state. The governing equation derived is compared to that of the EB model with the surface stress. The results obtained reveal that the nonlocality tends to decrease the bending moment stiffness whereas to increase the bending rigidity in the governing equation. This tendency also depends on the surface conditions.

Applicability of nonlocal models to nano-beams is discussed in terms of physical implications via the similarity between a nonlocal Euler-Bernoulli (EB) beam theory and a classical Rankine-Timoshenko (RT) beam theory. The nonlocal EB beam model, Eringen's model, is briefly reviewed and the classical RT beam theory is recast by the primary variables of the EB model. A careful comparison of these two models reveals that the scale parameter used to the Eringen's model has a strike resemblance to the shear flexibility in the RT model. This implies that the nonlocal model employed in literature consider the axial length scale effect only. In addition, the paradox for a cantilevered nano-beam subjected to tip shear force is clearly explained by finding appropriate displacement prescribed boundary conditions.

In this study, four different types of Nb2O5 thin layers were prepared using sol-gel process to improve energy conversion efficiency of dye sensitized solar cells (DSSCs). Nb2O5 layer was prepared on the fluorine-doped tin oxide (FTO) layer, TiO2 electrode layer, and inside of TiO2 layer, respectively. The Nb2O5 layer was used to reduce the recombination of photo induced electrons and holes. The DSSCs were assembled with platinum (Pt) coated counter electrode, ruthenium dye, and iodine based electrolyte. The photocurrent-voltage (I-V) characteristics of DSSCs with different types of Nb2O5 were studied. The efficiency depends not only on the structure of DSSCs but also on the initial compositions for the preparation of Nb2O5.

Conducting polymer composites have many interesting physical properties and important application potentials. Suitable combinations of metal nanoparticles with conductive polymers can result in composite materials having unique physical and chemical properties that can have wide application potential in diverse areas. In this work, copper nanoparticles were fabricated by electrical explosion of wire (EEW) in solution of polyacrylic acid (PAA) and ethanol. Conductive polyaniline-copper (PANI-Cu) composites have been synthesized by in-situ polymerization of aniline in the fabricated copper suspension. Optical absorption in the UV-visible region of these suspensions was measured in the range of 200-900 nm. Morphology and structure of the composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared spectra (FTIR). Pure copper nanoparticles were uniformly dispersed into the polymer matrix. Thermal stability of the composites was characterized by thermogravimetric analysis (TGA). Electrical conductivity measurements indicated that the conductivity of the composites was higher than that of pure polyaniline and increased with increasing content of copper.