Abstract: The free electron lifetime is a key factor in determining the performance of a dye-sensitized solar cells (DSCs). Open-circuit voltage-decay (OCVD) suggested by Zaban is a useful technique to provide continuous reading of the electron lifetime as a function of device’s open-circuit voltage (Voc), but the data processing has never been studied in order to get high accuracy electron lifetime value from the high resolution decaying voltage data. In this manuscript, we introduce the variable rank differential smoothing (VRDS) technique in the electron lifetime data processing. We find it can lessen data loss and give highly accurate electron lifetime value in the range of Voc decaying. We also get the effective recombination order values based on the VRDS technique, which indicate different potential processes due the two different values. These results show the detail kinetics information and microscopic device physic characteristics, which are very important to understand the device working mechanism and meaningful for realizing higher performance solar cells.
Abstract: We have used density functional theory to study adsorption of caffeine and nicotine on carbon based nanostructures. The effect of caffeine and nicotine molecules on the electronic properties of α-graphyne, biphenylene carbon, and (4,0) nanotube based on α-graphyne were studied. It was found that caffeine and nicotine molecules were adsorbed strongly on these sheets and nanotube. The charges were transferred from molecules to the sheets and nanotube. Because of adsorption of these donor molecules, biphenylene carbon, α-graphyne sheet and nanotube become n-type semiconductors. Sensitivity of the electronic properties of these sheets and nanotube to adsorption of caffeine and nicotine indicate the carbon based nanostructures can be used for detection of caffeine and nicotine molecules.
Abstract: Prion protein has drawn great attention due to its pathological potential to prion diseases. Discriminate and detection of the trace quantities PrPSc is an important measure for prion disease diagnosis at the presymptomatic stage. In this study, we developed a novel sandwich surface plasmon resonance (SPR) assay for the detection of PrPSc, involving bare gold surfaces and bare gold nanoparticles. PrPSc can be captured by the SPR sensing surface via a surface assisted coupling reaction between its intra-molecular disulfide bond and the gold atoms, while PrPC cannot bind to the gold surface strongly. The gold nanoparticles were proved to amplify the SPR detection signals via the coupling of their localized surface plasmon (LSP) with the propagating plasmon on the SPR gold surface. Our results confirmed that the bare SPR gold surface successfully captured the PrPSc from the solution with a LOD of 0.5ng/mL and a linear detection range from 0.5ng/mL to 500ng/mL. Injecting the gold nanoparticles after PrPSc yielded a dramatic enhancement of signal, with a lower LOD of 0.001ng/mL and a linear detection range from 0.001ng/mL to 10ng/mL. The gold nanoparticles permitted 4 to 322-fold increase of the signals. The required detection time was controlled in 15 min. PrPC, cys-protein G and their mixtures with PrPSc, were also detected via this sandwich SPR detection assay. Atomic force microscope (AFM) was used to evaluate the surface morphology of the SPR gold substrate after the detection. All the obtained results suggested that this novel SPR sandwich detection assay in our work was efficient, sensitive and specific for the detection of trace PrPSc
Abstract: This paper presents single walled carbon nanotube (SWCNT) interconnects with air as dielectric medium. We treat CNT interconnects as a discrete (fractal) media for the first time where continuum based differential equations fail to capture the physics at nanoscale and hence, we use discrete partial differential equations in this work. We have analyzed the effect of air gaps (AG) on performance factors like temperature dependent resistance R(T) of CNTs and hence the R(T)C delay of the interconnects. We have first calculated the temperature coefficient of resistance (TCR) of CNTs and analyzed the trend of changing resistance at different ambient temperatures. The R(T)C delay shows that CNT/AG interconnects can operate satisfactorily up to 500K. We then compare the R(T)C delay with ITRS predictions from 17nm to 8nm technology nodes. We have also calculated the chip area used by CNT/air-gap interconnects and found that they take up to 83% lesser area than the conventional Cu/low-k interconnects.
Abstract: In this work, we have investigated the adsorption behavior of the CN radicals on electronic properties of BC2N nanotube (BC2NNT) by means of the B3LYP hybrid density functional method using 6-31G(d) basis set. The results show that CN radicals can be chemically adsorbed on the nanotube. Based on the energy analysis, the most stable position of CN radical on the nanotube is C1 site. Also, the C-side complexes are more stable than the N-side complexes. We investigated the effects of CN radicals adsorption on the electronic properties of the BC2N nanotube. According to our calculations, band gap energy of the BC2NNT decreases with increasing the number of CN radicals. It is predicted that the conductivity and reactivity of nanotube increase by increasing the number of CN radicals. Based on the NBO analysis, in all complexes charge transfer occurs from nanotube to CN radical. The AIM results show that, the Xtube…YCN interaction has covalent nature. Generally, The BC2N nanotube can be used to as sensor for nanodevice applications.
Abstract: In the present study, visible light active CuS/CdS nanocomposites of various compositions (1%, 2% and 3%) were synthesized via wet impregnation method and these photocatalysts were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and UV-visible diffuse reflectance spectroscopy (DRS). The photocatalytic degradation efficiency of the synthesized photocatalysts was evaluated from the degradation of methylene blue (MB) under the visible light irradiation. Among all compositions, a 1% CuS/CdS nanocomposite showed about 89.5% degradation in 90 min than the pure CuS, CdS and other composites. Photoluminescence and photoelectrochemical measurements indicated that the 1% CuS/CdS nanocomposite greatly enhanced the charge generation and restrained the recombination of photogenerated electron-hole pairs. A possible mechanism of photocatalytic degradation has been proposed.
Abstract: In this research, the possibility of applying multilayer multielement super hard coatings by Cathodic Arc is investigated. More precisely the structure of the coating consisting of quaternary CrAlSiN and ternary AlSiN layers is examined by electron microscopy, X-ray diffraction and X-ray photoelectron microscopy analytical methods. The as-deposited samples were found to have distinguishable layers. The CrAlSiN layer is characterized by an extra sequence of repeated nanolayers. The AlSiN layer consisted of nanosized grains having a preferential orientation. Finally the surface layer was found to contain a solid solution of CrxAl1-xN, while Si3N4was identified only by XPS most probably due to its amorphous structure.
Abstract: Activated carbons (ACs) were successfully prepared using plane tree seed (PTS) as a cheap and renewable raw material. The plane tree seeds were firstly treated combining magnetic (MM) and ultrasonic mixing (USM) during 0.5, 1 and 3 h in 1 M, 3 M and 6 M of H3PO4 solutions, and then activated at 260 °C during 20 h (low temperature hydrothermal carbonization–low HTC) in above mentioned solutions of the same molarity. The influence of combined mixing and activation processes on physical, structural and morphological properties, and their optimization was studied by X-ray powder diffraction (XRPD), Raman spectroscopy, nitrogen adsorption-desorption isotherms, fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis.
Abstract: In this work Differential Transform Method (DTM) is used to study the buckling behavior of the single walled carbon nanotube (SWCNT). The critical buckling load is being found out up to fourth degree accuracy for different boundary conditions, i.e. Clamped-Clamped, Simply Supported at ends, Clamped Hinged, and Clamped Free. Effect of different nonlocal parameters, different L/d ratio on critical buckling load is being discussed. The DTM is implemented for the nonlocal SWCNT analysis and this yields results with high degree of accuracy. Further, present method can be applied to linear and nonlinear problems.
Abstract: The almost monodisperse ellipsoid-like CeO2 nanostructures with rugged surface and many pores have been synthesized by a smart hydrothermal technique. Various techniques have been applied to investigate the CeO2 nanostructures, including XRD, SEM, XPS, Raman scattering, UV-vis and Photoluminescence (PL) spectra. The results showed that the ellipsoid-like CeO2 have a fluorite cubic structure and there are Ce3+ ions and oxygen vacancies existing in surface of samples. It is also found that there is a red-shifting in the band gap of the materials compared to bulk one, which is mainly attributed to the influences of the Ce3+ ions, oxygen vacancies and the morphology of the materials. The photoluminescence measurement indicated that the ellipsoid-like CeO2 samples exhibit excellent optical properties at room temperature, which can be reasonably explained for the influences of the concentration of oxygen vacancies and Ce3+ ions.