摘要: In this article, the relations between extinction cross section and Gold nanoparticle's parameters such as dimensions have been investigated. In this work, the extinction cross section of the core-shell nanoparticles is analyzed by changing the shell material and its thickness. By this, the interesting results such as shifting resonant peak in optical response are obtained. Moreover, a new model of nanostructure is proposed in which the resonant peak of extinction cross section can be controlled by adding silicon nanoparticles and impurity in the shell. This method can be used for tuning of the scattering properties of the core-shell nanoparticle. In the following, we demonstrate that the effective epsilon properties can be used for tuning of the desired optical response in the combinational structure of the spherical nanoparticles. At the end, the effective relative epsilon is also calculated for the selected structures. The operational frequency band is selected from 300 (THz) to 900 (THz).
摘要: Co3O4 nanoparticles with biomimetic activity have been synthesized using inorganic precursor by a simple liquid precipitation method without use of any organic and assisted agents. XRD and IR results showed that the as-prepared product was well-crystalline cubic Co3O4 phase with a lattice constant of a=8.079Å. The TEM image showed that the obtained Co3O4 product possesses a spherical and rectangular shape with a diameter ranging from 10 to 20nm. The Co3O4 nanoparticles catalyzed oxidation of typical peroxidase substrate (ABTS) and 1,3,5-trimethylbenzene (TMB) to give the same color changes as microperoxidase -11( MP-11), respectively. And the catalysis by Co3O4 nanoparticles shows typical Michaelis-Menten curves similar to that of MP-11. These results demonstrate that the Co3O4 nanoparticles possess a biomimetic catalysis activity similar to that found in natural enzyme. The kinetic parameters showed Co3O4 nanoparticles had efficient catalytic activity in comparison to MP-11.The easy preparation, good stability and special properties of Co3O4nanoparticles make them the promising enzyme mimics.
摘要: pH responsive polymeric nanoparticles have emerged as a promising technology platform for targeted and controlled drug delivery in recent years. In this paper, endosomal pH-activatable doxorubicin (DOX) and core-crosslinked polymeric nanoparticles (DCNPs) were prepared and investigated for potent growth inhibition of human cancer cells in vitro. In vitro drug release studies, DOX conjugated nanoparticles with hydrazone bond showed a pH sensitive release phenomenon, that is, the releasing is significantly faster at mildly acidic condition with pH of 5.5 than that at physiological condition. Confocal laser scanning microscope (CLSM) observations revealed that DOX conjugated nanoparticles delivered and released DOX into the cytosols as well as cell nuclei of Hela cells following 6 h incubation. MTT assays demonstrated that these pH-sensitive DOX nanoparticles exhibited high antitumor effect to HeLa cells. The conjugated DOX polymeric nanoparticles may be a promising candidate as a nanoscale and pH-sensitive drug delivery vehicle for cancer therapy.
摘要: Understanding the micro-mechanical properties and the microstructure of cement-based materials under the saline lake environment in western China can provide a scientific basis for the durability design. In this study, cement pastes ((w/c=0.35) and (w/c=0.53)) were prepared and soaked in brine solution to carry out the dry-wet cycle test, the chemical composition of which is similar to saline lake solution. The micrographs of corroded regions and corrosion products were observed and analyzed under scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Micro-mechanical properties of different phases were tested by nanoindentation, and multi-peaks fitting was carried out for the experimental frequency distributions of the indentation modulus and indentation hardness by Gaussian function. In the meantime,the statistical distribution of micro-mechanical properties was summarized for the hydrates in corroded cement paste, which has included the low density calcium–silicate–hydrates (LD C-S-H gel), high density calcium–silicate–hydrates (HD C-S-H gel) and calcium hydroxide (CH). The results show that micro mechanical properties of each phase in cement paste after brine corrosion decreased significantly. In addition, the water-cement ratio has little effect on the micro mechanical properties, but much effect on volume fraction of each phase.
摘要: Electrochemical etching was carried out to produce porous silicon based on crystalline silicon n-type (100) and (111) wafers. Etching times of 10, 20, and 30 min were applied. Porous silicon layer was used as anti-reflection coating on crystalline silicon solar cells. The optimal etching time is 20 min for preparing porous silicon layers based on crystalline silicon n-type (100) and (111) wafers. Nanopores with high porosity were produced on the porous silicon layer based on crystalline silicon n-type (100) and (111) wafers with average diameters of 5.7 and 5.8 nm, respectively. Average crystallite sizes for the porous silicon layer based on crystalline silicon n-type (100) and (111) wafers were 20.57 and 17.45 nm at 20 and 30 min, respectively, due to the increase in broadening of the full width at half maximum. Photoluminescence peaks for porous silicon layers based on crystalline silicon n-type (100) and (111) wafers increased with growing porosity and a great blue shift in luminescence. The minimum effective coefficient of reflection was obtained from porous silicon layers based on the crystalline silicon n-type (100) wafer compared with n-type (111) wafer and as-grown at different etching times. Porous silicon layers based on the crystalline silicon n-type (100) wafer at 20 min etching time exhibited excellent light trapping at wavelengths ranging from 400 to 1000 nm. Thus, fabricated crystalline silicon solar cells based on porous silicon (100) anti-reflection coating layers achieved the highest efficiency at 15.50% compared to porous silicon (111) anti-reflection coating layers. The efficiency is characterized applying I-V characterization system under 100 mW/cm2 illumination conditions.
摘要: This paper presents a type of Ag/polydimethylsiloxane (Ag/PDMS) nanocomposite material for use in strain gauge element applications. In these elements, the Ag nanoparticles work as conductive elements by electron tunneling and the PDMS forms the tunneling dielectricstructure. In our experiments, the piezoresistance and piezocapacitance characteristics of these Ag/PDMS composites have been studiedunder applied rain/stress. From the results, the gauge factors for piezoresistance and piezocapacitance can reach up to 153 and 224, respectively. Also, when acting as strain elements, the Ag/PDMS composites show fine levels of repeatability and stability. The results given here prove that the material can be used to form anew type of high-sensitivity element for sensor applications. The detectionmethod used for the sensor signals also offersdiversity by including both piezoresistance and piezocapacitance.
摘要: Efficient utilization of agricultural residue is the need of today’s environment. Teff straw is one such agricultural residue which is available in high amount in east African continent particularly Ethiopia. In the present study, combination of heat and acid treatment has been used to extract nano-silica from teff straw. X-ray fluorescence (XRF) analysis showed presence of high amount of silicon dioxide (≈52%) in raw teff straw. Thermal treatment at 600°C for 4 hour increased the SiO2 concentration to ≈ 92% in its ash. Further acid treatment increased the concentration to ≈97%. Fourier transform infrared (FTIR) spectroscopy also confirmed increase in SiO2 after thermal and acid treatment. X-ray diffraction (XRD) analysis showed the silica of amorphous nature in teff straw ash before acid treatment (S-BAT) whereas crystallinity increased after acid treatment (S-AAT). Transmission electron microscopy (TEM) showed presence of uniform nano-disks shaped particles of 50 nm average particle size in acid treated teff straw ash. Compared to other agricultural residues high amount of silica availability as raw and its small diameter anatomy structure will make teff straw better source of silica material at lower heat and chemical treatment.
摘要: In this work, we introduce a synthesis method for a nanofiber membrane made of polyacrylonitrile and verify its filtration ability with micron-size particles. The polyacrylonitrile nanofiber membrane was produced by electro-spun technique with a thickness less than 0.2 mm. The filtration experimental result from micron-size particle penetration proved that after 60-min deposition, the polyacrylonitrile nanofiber membrane successfully filtrated ~99% micron-size particles in solution. We found that uniform morphology, consistent nanofiber diameter without disordered beads will lead to a better filtration performance. This finding will provide a low-cost, environmental-friendly and straightforward filtration approach for future PM2.5 elimination in an aqueous and harsh environment.
摘要: Molecular electronics seeks to decrease the cost, power consumption and size of devices, using a variety of approaches. However, few attempts have been made to address circuit simulation. The availability of common semiconductor components means they can be used for modeling and simulating molecular circuits to speed progress in molecular electronics. The present study examines the switching of a gated oligo-phenylenevinylene (OPV) molecule as a NMOS molecular transistor, resistance as an indicator of methyl molecules, and the linking of these abilities using LTspice simulation software. The circuit simulation of molecules of basic logic gates, half-adder, full-adder, and multiplier logic circuits are carried out. The numerical results may shed light on the next applications of molecular systems and make them a good, promising candidate for field-effect transistors.
摘要: The electrical properties of bottom-gate amorphous InSnZnO (a-ITZO) thin-film transistors (TFTs) with different channel thicknesses (TITZO) were investigated. The difference between front- and back-channel interface traps influence on subthreshold swing (S) and turn on voltage (Von) of a-ITZO TFTs was further analyzed using device simulation. Variations of front-channel interface traps (Naf) on S and Von were hardly dependent on TITZO. However, variations of S and Von became larger for thinner TITZO TFT when back-channel interface traps (Nabk) varied; which can be explained by considering screening length. Not only Naf but also Nabk are important factors of S and Von to achieve high performance thinner oxide TFT.