Nano

In this work, a novel electrochemical sensor was presented for Tanshinone IIA determination. The as-prepared electrode was prepared by electrodepositing a reduced graphene oxide film onto a carbon paste electrode modified with gold nanoparticles, which combined the advantages of both gold nanoparticles and electrochemically reduced graphene oxide. It was characterized with scanning electron microscopy and cyclic voltammetry. The electrochemical behavior of Tanshinone IIA at the modified electrode was investigated for the first time. Results revealed that the modified electrode can effectively increase response toward Tanshinone IIA by significantly enhancing the redox peak currents and decreasing the peak-to-peak separation. Under the optimized conditions, the modified electrode showed a linear voltammetric response to Tanshinone IIA at concentrations ranging from $5.0\times 10^{-8}$mol L${}^{-1}$ to $1.0\times 10^{-5}$mol L${}^{-1}$, with a detection limit of $1.0\times 10^{-8}$mol L${}^{-1}$ ($S∕N=3$). The proposed method was successfully applied in determination of Tanshinone IIA in pharmaceutical samples with satisfactory results.

Polypyrrole/chitosan (PPC) spherical dark nanoparticles surrounded by shadow spheres were fabricated through in situ oxidative polymerization of pyrrole in presence of chitosan (CS) using ferric chloride (FeCl₃) as oxidant and evaluated as a carrier for some amino-quinazolinone derivatives (I–IV). The loading of amino-quinazolinone derivatives (I–IV) into the core–shell nanoparticles were investigated by thermal gravimetric analysis (TGA). Quinazolinone derivatives (I–IV) loaded nanoparticles showed inter-connected sphere in necklace-like morphology, rods or filaments depending on the functional groups in quinazolinone derivatives. The release of quinazolinone derivatives from PPC nanoparticles was pH sensitive. The antimicrobial activity of loaded PPC nanoparticles against gram positive and gram negative bacteria was higher than CS and PPC nanoparticles. The results revealed that new generation of nanoparticles loaded with quinazolinone represent a potential platform to target breast cancer cell line (MCF7), Ehrlich ascites carcinoma (EAC) cells and liver cancer cells (HEPG2) in comparison with PPC and quinazolinone derivatives.

Nitrogen-doped HTiNbO₅ nanosheet (N-HTiNbO₅-NS) aggregation was successfully obtained through a series of process, including preparation of nitrogen-doped precursor (N-KTiNbO₅), proton-exchange of N-KTiNbO₅ and exfoliation of N-HTiNbO₅. The structures of the as-prepared samples are characterized by means of powder X-ray diffraction (XRD), Scan electron microscopy (SEM), Transmission electron microscopy (TEM), N₂ adsorption-desorption isotherms UV-visible diffuse reflectance spectroscopy (UV-Vis-DRS), Laser Raman spectroscopy (LRS), X-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis-differential scanning calorimetry (TG-DSC). The catalytic activities of the as-prepared samples are evaluated by the photocatalytic degradation of methylene blue (MB) aqueous solution under visible light irradiation. The results reveal that N-HTiNbO₅-NS due to the large specific surface area and brilliant visible light response exhibits a relatively excellent photocatalytic activity in the decomposition of MB under visible light irradiation.

SO₂ is one of the major pollutants in the atmosphere. N-doped microporous carbon spheres (NCS) have been demonstrated to be effective for SO₂ adsorption. Here we report the synthesis of monodispersed NCS by the extended Stöber method with urea resorcinol-formaldehyde resins as carbon source, urea as nitrogen source and ammonia as catalyst in an ethanol-water mixed solvent. The obtained carbon spheres show a uniform diameter of around 550nm, specific surface area of 476m²g${}^{-1}$, micropores pore volume of 0.20cm³g${}^{-1}$ and nitrogen doping. The NCS manifest special performance for SO₂ capture with capability of 75.34mgg${}^{-1}$ and good cycling stability, due to the large surface area, abundant micropores and nitrogen functionality.

Graphene loaded hexagonal CuS/Ag₂S nanoplates have been successfully synthesized. Scanning electron microscopy and transmission electron microscopy observations show that hexagonal CuS/Ag₂S nanoplates are tightly anchored onto graphene. The experimental results show that these nanocomposites have a highly visible-light photocatalytic performance. The high visible photocatalytic activities can be attributed to direct photoinduced interfacial charge transfer in the hexagonal CuS/Ag₂S nanoplates and the further electrons transfer from CuS/Ag₂S to graphene.

A superoxide anion radical (O${}_2^{•-})$ nonenzymatic electrochemical sensor based on PtRuCu ternary alloy nanoparticles/electrochemically reduced graphene oxide (ERGO) composite modified glassy carbon electrode (PtRuCu/ERGO/GCE) was developed. ERGO and PtRuCu/ERGO composites were characterized by scanning electron microscopy. The prepared PtRuCu/ERGO/GCE showed remarkable performance toward the electrocatalytic reduction of (O${}_2^{•-})$. The sensor possessed a high sensitivity of 1725$\mu$A$\cdot$mM${}^{-1}\cdot$cm${}^{-2}$, a wide linear range of 7.5–330$\mu$M ($R^2=$0.993) and a low detection limit of 0.7$\mu$M ($S$/$N=3$), as well as excellent selectivity, reproducibility and stability, which can be attributed to the synergistic effect of ERGO and PtRuCu ternary alloy nanoparticles. Therefore, the prepared sensor is promising for electrochemical determination of O${}_2^{•-}$.

New monolithic nitrogen-containing microporous cellular activated carbon was successfully prepared from phenol-urea-formaldehyde (PUF) organic foam for CO₂ and H₂ adsorption and was characterized by thermogravimetric analysis (TG), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), a mechanical testing machine, N₂-sorption and H₂/CO₂ sorption. The carbon yield was approximately 50% for carbonization and the burn off for activation ranged from 40% to 56%, which linearly increased with activation time. The macroporosity corresponded to the connected network of cells with diameters ranging from 100$\mu$m to 600$\mu$m, and the pinholes in the cell walls had diameters ranging from 1$\mu$m to 2$\mu$m. The micro/mesoporosity is located at the inner surface of the cells. Thus, higher adsorption kinetics than usual from activated carbon are expected. The developed carbon with the highest $S_{\mathrm{\text{BET}}}$ (1674 m²/g) and highest $V_{\mathrm{\text{DR}}}$ (0.86cm³/g) contained 1.5% nitrogen, had a CO₂ adsorption capacity of 3.53mmol/g at 298K, and had an H₂ adsorption capacity of 1.9wt.% at 77K, both at atmospheric pressure (1 bar), which were among the best in activated carbons from physical activation.

An electrochemical sensor for the rapid, selective and sensitive detection of Pb${}^{2+}$ was developed using polypyrrole-graphene (PPY-rGO) nanocomposite by electrochemical synthesis. The PPY-rGO-modified electrode possessed a large effective area because of unique 3D porous architectures, and it displayed excellent selectivity for the determination of Pb${}^{2+}$. The response of Pb${}^{2+}$ on the nanocomposite-modified electrode was evaluated, and the relevant parameters were optimized by square wave anodic stripping voltammetry (SWASV). The stripping response was highly linear ($R^2=0.987$) over a Pb${}^{2+}$ concentration range of $5\times 10^{-9}$mol/L to $7.5\times 10^{-7}$mol/L, with a detection limit of $4.7\times 10^{-11}$mol/L (3$\sigma$ method). Furthermore, its applicability was validated for the determination of Pb${}^{2+}$ levels using spiked tap water at different concentrations. The polyporous structure, satisfactory reproducibility, long-term stability and simple synthesis endow the PPY-rGO nanocomposite a promising application in the determination of Pb${}^{2+}$.

In this proposed work, an extensive study on the linearity performance of underlap AlInN/GaN double gate metal oxide semiconductor high electron mobility transistors (MOS-HEMT) has been analyzed using 2D Sentaurus TCAD simulation. Specifically a brief comparison is made on the linearity and intermodulation distortion characteristics of the proposed device due to variation of barrier layer thickness from 2 nm to 6 nm. Various parameters such as transconductance ($g_m)$, second-order transconductance ($g_{m2}$), third-order transconductance ($g_{m3}$), second-order voltage intercept point (VIP2), third-order voltage intercept point (VIP3), third-order input intercept point (IIP3) and third-order intermodulation distortion (IMD3) of underlap AlInN/GaN double gate metal oxide semiconductor high electron mobility transistors (MOS-HEMT) are discussed. The simulated results obtained confirms that by careful optimization of barrier layer thickness linearity characteristics of this proposed device can be improved, which can be suitable for analog and circuit applications.

Electric field enhanced approach has been used to synthesize different copper hydroxide morphologies as high-performance supercapacitors electrode materials. Employing this efficient, simple and low cost method, various shapes such as rod, flower and cube with an average grain size of 30nm to 1$\mu$m were obtained on the copper substrate. The results revealed that applied electric field considerably accelerates the formation time of nanostructures from several days to close to 1min, where some of the desired nanostructures were obtained even in 1s. The electrochemical properties of different morphologies were compared using cyclic voltammograms and charge/discharge tests and electrochemical impedance spectroscopy. The obtained results demonstrated that the two types of fabricated structures showed high maximum areal and specific capacitance of 42mF/cm² and 178F/g at scan rate of 20mVs${}^{-1}$, respectively, which make them excellent and promising electrode materials for supercapacitors.

Burkitt’s lymphoma is a highly proliferative B-cell malignancy characterized by MYC oncogene translocation. Intensive short-cycle chemotherapy could effectively improve the outcome of this disease. However, drug resistance limits the treatment of refractory/relapsed disease. Thus, we constructed and investigated a novel cadmium–tellurium quantum dot conjugated with doxorubicin and gambogic acid (DOX/GA-CdTe QDs) for cancer cell combined treatment in Raji, a Burkitt’s lymphoma cell line. Results showed that DOX/GA-CdTe QDs could significantly improve anti-tumor effects compared with drugs alone in the Raji cell line. Flow cytometry, transmission electron micrographs and overexpression of Beclin1 and LC3 II/I showed that apoptosis and autophagy were involved in the process. However, DOX/GA-CdTe QDs did not cause cell cycle arrest, whereas DOX alone or combined with GA could cause apparent G2/M phase arrest. Hence, the novel DOX/GA-CdTe QDs offer a promising approach of drug delivery into cancer cells.

Aligned carbon nanotubes (ACNTs) have very unique properties that made them applicable as electrode material for energy storage devices. ACNTs were grown directly on substrates by catalytic chemical vapor deposition (CVD). Cobalt, thermally-oxidized aluminum and ethanol were used as catalyst, catalyst-support and carbon feedstock, respectively. Optimum catalytic and reaction conditions were investigated by varying the CVD processing temperature and time. CVD processing temperature of 725${}^{\circ }$C and processing time at 10min showed the optimum CNT alignment with thickness of above 2$\mu$m. Other than the effect of catalyst particle diameter, formation of amorphous carbon at the top of CNTs observed by SEM is suggested as another factor that influences the growth mechanism of ACNTs. The CVD processing parameter and the interaction between small carbon patches are supposed to be built after dehydrogenation of the first carbonaceous molecules and the catalyst nanoparticle surface considered as the hidden factors behind the growth results.

An efficient N-doped reduced graphene oxide (N-RGO)/Ag₃PO₄ nanocomposite with enhanced photocatalytic activity has been prepared through a facile solution-based approach. Since N-RGO could offer more sites for the anchoring of Ag₃PO₄ nanoparticles, and effectively promote the charge carriers separation and transfer due to its high electrical conductivity, the photocatalytic activity of N-RGO/Ag₃PO₄ nanocomposite is much higher than bare Ag₃PO₄ and N-RGO in the degradation of phenol pollutant under simulated solar light irradiation. The mechanism for the photocatalytic process was also investigated. The excellent photocatalytic performance makes the N-RGO/Ag₃PO₄ nanocomposite a promising photocatalyst for organic pollutant treatment.