Abstract: This work applies combination of Direct Tunneling model and BSIM4 based ITAT model to explain the leakage of electrons from charged nanocrystals to p-type silicon substrate in data retention condition, for an ultra-thin tunnel oxide, low voltage programmable silicon nanocrystal based flash gate stack. Basic expressions of these models are modified to incorporate the nanocrystals related charge leakage in idle mode. The concept is supported by simulating these models and comparing them with the experimental data. Transition of electrons is considered as a result of Direct Tunneling and their trapping de-trapping via water related hydrogen traps. However, it is found that modified ITAT mechanism is the dominant one. Flat-band voltage shift profile fits accurately with the model with an extrapolated 10 years device lifetime without memory closure. 3 nm thick tunnel oxide and 100 nm sized nanocrystal fabrication with Electron Beam Lithography are main features of the devices.
Abstract: Biocompatibility of tin selenide quantum dots was achieved by the incorporation of 3-mercaptopropionic acid (3-MPA) as a capping agent, which also improved the stability and the solubility of the material. The UV-Vis spectrophotometric analysis of the quantum dots revealed a broad absorption band at ~ 330 nm (with a corresponding band gap, Eg, value of 3.75 eV), which is within the range of values expected for quantum dots materials. The 3-mercaptopropionic acid-capped tin selenide (3-MPA-SnSe) quantum dots were used to develop an electrochemical biosensor for indinavir, which is a protease inhibitor antiretroviral (ARV) drug. The biosensor was prepared by the self-assembly of L-cysteine on a gold electrode that was functionalised with 3-MPA-SnSe quantum dots, followed by cross-linking with cytochrome P450-3A4 (CYP3A4) using 1-ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The electrocatalytic properties of the biosensor included a characteristic cyclic voltammetric reduction peak at-380 mV, which was used to detect the response of the biosensor to indinavir. The sensor performance parameters included response time and limit of detection (LOD) values of 11 s and 3.22 pg/mL, respectively. The test concentration range studied (0.014 – 0.066 ng/mL) gave a linear calibration plot for indinavir, and it was lower than the physiological plasma concentration index (i.e. maximum plasma concentrations, Cmax,) of indinavir (5 - 15 ng/mL) normally observed 8 h after intake. This indicates that the biosensor can be very useful in the case of ultra-rapid metabolisers where very low Cmax values are expected
Abstract: Silver nanoparticles were synthesized at 293÷353 K temperature range by NaBH4 and HCOOH solutions with low concentration at polyethyleneglycol having average molecular weight of 40000 and 200 kDa gum arabic medium. Obtained silver nanoparticles were studied using methods of X-ray diffraction, UV-Vis, FTIR spectroscopy, scanning electron microscope. It was determined that sizes of silver nanoparticles which stabilize at polymer medium vary from 12 to 26 nm range depending on mole ratio, temperature and reduction medium of initial substances. It was shown by FTIR-spectroscopy that -OH and -COOH groups in polymer take an active part in stabilization of silver nanoparticles. It was determinated by UV-Vis study of silver nanoparticles containing polymer composition in aqueous condition that 412 nm which is specific to silver atoms do not change sharply for 4-5 days.
Abstract: TiSe2 nanobelts/nanoplates have been successfully fabricated through a facile and environment-friendly pressureless sintered process using micro-sized Ti and Se elements as raw materials. The morphology and structure of the as-prepared TiSe2 products were investigated by X-ray diffractometer, scanning electron microscopy, transmission electron microscopy and high resolution transmission electron microscopy. The experimental results indicated that the morphology of TiSe2 products were strongly dependent on the reaction temperature and reaction time. As the reaction temperature was set at 600°C and 800°C, long belts-like and plates-like structures of as-prepared TiSe2 products could be observed, respectively. However, a mixture of nanobelts and nanoplates could be obtained at a reaction temperature of 700°C. It was also found that the reaction time played a crucial role in obtaining the homogeneous distribution nanoparticles, therefore, reasonable reaction process and formation mechanisms of as-prepared TiSe2 nanoparticles were proposed. Moreover, the tribological properties of the TiSe2 nanobelts/nanoplates were investigated. The test results showed that the addition of TiSe2 nanoparticles could improve the tribological properties of base oil. Furthermore, the friction coefficient of base oil containing TiSe2 nanoplates was lower and more stable than those of TiSe2 nanobelts and pure base oil.
Abstract: A novel signaling technique for on-chip carbon nanotube interconnect aiming a higher bitrate in the range of Terahertz (THz) with low power dissipation, employing the current mode signal transportation is proposed in this paper. The technique exploits the combined advantages of current mode signaling and carbon nanotube. Using the equivalent circuit model, the transfer function is derived for the current mode carbon nanotube interconnect. Current mode signaling through carbon nanotube interconnect is simulated in MATLAB and HSPICE to study its efficiency and performance. The results are compared with the existing voltage mode CNT, current mode copper and optical interconnect. The proposed current mode signaling for carbon nanotube interconnect achieves 102 times lesser power delay product and 90% lesser delay than voltage mode. It exhibits lesser delay, 1000 times in local and 1.2 times in global and lesser power delay product by the factor of 1000 as compared with optical interconnect.
Abstract: High-shear mixing was demonstrated as an effective approach for the green synthesis of ultrathin g-C3N4 nanosheets with excellent photocatalytic performance. The resultant nanosheets were characterized in terms of morphology, crystal structure, electronic structure and photocatalytic behavior. It was found that the g-C3N4 nanosheets mainly consist of one C-N layer with a thickness about 0.7 nm. The products show a band gap of 2.6 eV and exhibit high photocatalytic activities with almost 4 times higher than their bulk counterparts toward RhB degradation. With the yield as high as 20 %, the present simple route may be qualified as a promising candidate for the mass production of high quality g-C3N4 nanosheets.
Abstract: In this paper, a gate-all-around junctionless tunnel field effect transistor (JL-TFET) based on carbon nanotube (CNT) material is introduced and simulated. The JL-TFET is a CNT-channel heavily n-type-doped junctionless field effect transistor (JLFET) which utilizes two insulated gates (Control-Gate, P-Gate) with two different metal workfunctions in order to treat like tunnel field effect transistor (TFET). In this design, the privileges of JLTFET and TFET are mixed together. The numerical comparative study on the performance characteristics of JL-TFET and conventional p-i-n TFET demonstrated that the proposed JL-TFET has a higher ON-state current driveability (ION), a larger ON/OFF-current ratio (ION/IOFF), a lower drain induced barrier lowering (DIBL), a shorter delay time (τ), and also a superior cut-off frequency (ƒT). Moreover, in order to further performance improvement of proposed JLTFET, three novel device structures namely as junctionless linear descending gate workfunction TFET (JL-LDWTFET), junctionless linear ascending gate workfunction TFET (JL-LAWTFET) and junctionless triple metal gate TFET (JL-TMGTFET) are proposed by gate workfunction engineering approach. According to simulation results, the JL-TMGTFET with the gate composed of three segments of different work functions shows excellent characteristics with high ION/IOFF ratio, a superior ambipolar characteristic, a shorter delay time and a better cut-off frequency compared to conventional p-i-n TFET and other proposed junctionless-based features. All the simulations are done with the full quantum mechanical simulator for a channel length of 60-nm using nonequilibrium Green’s function (NEGF) method.
Abstract: Inherently benefiting from the natural nanosize graphene-structure in raw asphalt material. Asphalt-derived graphene quantum dots ( GQDs ) are prepared through, a facile route, one-step chemical oxidation of cheap petroleum asphalt. The as-prepared GQD sample may be well dissolved in water with a good homogeneous size at an average diameter of 2.44 nm, luminescing bright green light by excitation of 365 nm with a high quantum yield up to 16.13%. Furthermore, they are much smaller and thinner than most of the reported GQDs, presenting excellent fluorescent properties, such as excitation-tuned photoluminescence and good resistance to photobleaching. They are much smaller and thinner than most of the reported GQDs
Abstract: Template/spin-coating method was presented for fabricating single-layer nano-pillar array polymethylmethacrylate (SL-PMMA) and double-layer nano-pillar array polymethylmethacrylate (DL-PMMA) membranes. The different mass ratio of PMMA/DiMethyl Formamide (DMF) solution was dripped on single-layer porous anodic alumina (SL-PAA) or double-layer porous anodic alumina (DL-PAA) membrane and spun at 4000rpm speed for 30 seconds. The SL-PAA and DL-PAA membranes had been put into vacuum oven at 150°C for 2 hours, before SL-PMMA and DL-PMMA were removed. Experimental results show that the regularity degree of PAA fabricated in OAS/PAS is higher than that of PAA fabricated in PAS by two-step anodization method. The ordered pores and clear double-layer outline can be observed from the surface and cross-section FESEM images of DL-PAA membranes. When the content of PMMA in mixture solution is 20 wt%, the top shape of nano-pillars is convex, because the solution was completely filled in the pore of SL-PAA, and the length of nano-pillars is equal to the height of pore of PAA. However, the top pore amount on nano-pillars at ascending speed 20°C per minute is more than that of at ascending speed 10°C per minute. The PMMA membranes with ordered mid-hollow and porous nano-pillars will have wide application prospect in biosensors, chemical sensors, microcapsules fabrication fields due to many advantages such as simple operation, low cost, high specific surface area, etc.
Abstract: In this study, the antimicrobial growth inhibition and mechanistic activities of silver (Ag NPs), zinc oxide (ZnO NPs), and copper (Cu NPs) nanoparticles were investigated in presence of medicinal plant extracts of Tribulus Terrestris. The extract in different concentrations (5, 10, 20, and 30%) along with nanoparticles suspension mixture was used for antimicrobial activity testing against some human pathogenic microorganisms. Among the bacterial strains tested, Escherichia coli and Proteus sp were most susceptibile at 30% concentration followed by moderate activity against Morganella sp, Entrococcus Faecalis, Staphylococcus aureus, and Candida albicans. Tribulus Terrestris had no effect on Acetobacter sp and Streptococcus agalactia. The nanoparticles used in the present investigation have shown excellent antimicrobial activity in the presence of Tribulus Terrestris, hence they can be used as potent sources for antibacterial agents.