Journal of nanoscience and nanotechnology最新文献

Supercapacitor with high specific capacity is desirable for various energy storage and high powerdensity applications. Though Graphene has been the preferred material for high current density, nanocomposites have been attempted to increase the specific capacitance. Hydrothermal synthesis of cadmium sulfide/graphene (CdS/G) nanocomposite with CdS nanoparticles anchored/decorated over the graphene sheets is reported. The structural studies reveal the hexagonal phase of the prepared materials. The specific surface area (BET) and porosity is found to increase upon nanocomposite formation. The electrochemical characteristics such as cyclic voltammetry (CV), GCD and EIS of the CdS/G nanocomposite have been investigated. The capacitance of CdS/G nanocomposite almost doubled to 248 Fg^-1 indicating the enhanced performance of the nanocomposite system and in addition it also showed excellent cycling stability of 74.8 percent after 1000 cycles. The supercapacitor investigated retained the initial energy density after charge-discharge, at 0.5 A/g for 1000 cycles. The graphene nanosheets increased the specific surface area and interfacial electron transfer of the composite material. It enhances the specific capacitance and cyclic stability of the supercapacitor device.

Nanoemulsions were prepared using polyglycerol esters as emulsifiers. The effects of emulsifiers, oils, and polyols on the phase behavior of nanoemulsions were analyzed by phase diagram method using caprylic acid capric triglyceride (318), mineral oil, and squalane (Squ) as oils respectively. Various factors affecting the area of the oil-in-water (O/W) nanoemulsion were investigated. The results showed that hydrophilic polyglyceryl-4 laurate was beneficial to the formation of translucent nanoemulsions, while lipophilic polyglyceryl-4 oleate could synergize the emulsification performance and was more conducive to the formation of nanoemulsions; the type of oil could affect the emulsifying ability of the emulsifier. It was found that it was beneficial to form translucent nanoemulsion when caprylic acid capric triglyceride was adopted as oil. However, it was almost impossible to form translucent nanoemulsions when mineral oil and squalane were used as oils. The addition of water-soluble jojoba ester was beneficial to the formation of O/W emulsion. In addition, glycerin can improve the polarity of the aqueous medium, enhance the affinity between emulsifiers and aqueous medium, and help to form a translucent nanoemulsion.

Enhanced permeation and retention (EPR) effect, the mechanism by which nanodrugs accumulate in tumors and acquire superior curative effect. The questions of these mechanisms occur because of limited clinical transformation of engineered nanomaterials after 30 years. The difference of EPR limits the therapeutic effect of nanodrugs in the individual patient. Evaluation of the EPR effect in the individual patient will aid in selecting patients who will accumulate higher amounts of nanotherapeutics and show better therapeutic efficacy. Based on varied TIMP1/MMP-9 in serum, an aggregation-induced emission luminogen probe was designed and constructed to detect and evaluate the EPR effect in model mouse. The result showed that the ratio of TIMP1/MMP-9 (in the range 0.2-1.2) and fluorescence intensity of the probe were negative linear correlation and the effects of BSA-rhodamine accumulation in tumor were individualized differences as well as correlated with the relative ratio of TIMP-1/MMP-9 in serum. Our data support the development of these biomarkers probes based on the personalized nanotherapy of tumor.

The increase of harmful carbon monoxide (CO) caused by incomplete combustion can affect human health even lead to suffocation. Therefore reducing the CO discharged by vehicles or factories is urgent to improve the air quality. The spinel cobalt (II, III) oxide (Co₃O₄) is an active catalyst for CO abatement. In this study, we tried to fabricate dispersing Co₃O₄ via the dispersion-precipitation method with acetic acid, formic acid, and oxalic acid as the chelating dispersants. Then, the asprepared samples were calcined at 300 ºC for 4 h to obtain active catalysts, and assigned as Co(A), Co(F) and Co(O) respectively, the amount of the dispersants used are labeled as I (0.12 mole), II (0.03 mole) and III (0.01 mole). For comparison, another CoAP sample was prepared via alkaliinduced precipitation and calcined at 300 ºC. All samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), scanning electron microscope (SEM), and nitrogen adsorption/desorption system, and the catalytic activity focused on the CO oxidation. The influence of chelating dispersant on the performance of abatement of CO was pursued in this study. Apparently, the results showed that the chelating dispersant can influence the catalytic activity of CO abatement. An optimized ratio of dispersant can improve the performance, while excess dispersant lessens the surface area and catalytic performance. The series of Co(O) samples can easily donate the active oxygen since the labile Co-O bonding and indicated the preferential performance than both Co(A) and Co(F) samples. The nanorod Co(O)-II showed preferential for CO oxidation, T₅₀ and T₉₀ approached 96 and 127 ºC, respectively. Also, the favorable durability of Co(O)-II sample maintains 95% conversion still for 50 h at 130 ºC and does not emerge deactivation.

Noble metal nanoparticles have special properties in optical, electronic, and physical chemistry due to their high surface area and volume. With the development of electronic printing technology, inkjet printing has gradually replaced traditional spin coating and blade coating, since it leads to more material savings and a faster batch production, and the pattern can be easily designed by a computer. In this study, Ag nanoparticles were prepared by a chemical reduction method. Non-toxic, environment-friendly agents were selected to fabricate a single-shape, uniform-size, crystal-form, and monodisperse product. The effects of the reducing agent ratio and the stabilizer ratio on the size, shape, and stability of the nanoparticles are discussed. The silver nanoparticles were characterized by an ultraviolet-visible spectrophotometer (UV-vis) and a transmission electron microscope (TEM). In addition, in order to prepare conductive ink that can stably disperse for a long time and that can be applied to inkjet printing on a PET flexible substrate at a lower sintering temperature, a sintering agent and a commercial surfactant were added. The experimental results show that the best addition ratio of the precursor to the reducing agent and the stabilizer is 1:6:1. The conductive silver ink was printed and treated by a70 mM NaCl solution, and the electric resistivity was 5.17×10^-4 Ω· cm.

Bio-fabrication of iron oxide nanoparticles by using different sources of plants, plant parts and microbial cells have become a great topic of interest nowadays due to its eco-friendly nature. The stabilizing and capping agents in biological sources are biocompatible, stable and non-toxic which make its use beneficial for various biomedical applications. The bacteria are able to utilize metal ions and convert them into their respective nanoparticles by secreting different biomolecules. The plants and plant parts contain different types of phytochemicals which play a key role in synthesis and bio-fabrication of nanoparticles. Iron oxide nanoparticles are known to have various applications in the fields of medicine, environment etc. This review summarizes the applications of iron oxide nanoparticles as antimicrobial agent, drug delivery agent, material for removal of heavy metals and dyes from aqueous system etc. Due to these wide applications of iron oxide nanoparticles its demand in various fields is increasing considerably. This review describes different approaches which are used for biosynthesis of iron oxide nanoparticles and their applications. The review also summarizes about the surface modification strategies of iron oxide nanoparticles by using different polymers, polyelectrolytes which can be used for in-vivo applications.

In this paper we study the Electron Statistics in Heavily Doped N Type-Intrinsic-P Type-Intrinsic structures of non-linear optical, tetragonal and opto-electronic materials in the presence of magnetic quantization. It is found taking such heavily doped structures of Cd₃As₂, CdGeAs₂, InAs, InSb, Hg_1-xCd_xTe, In_1-xGa_xAs_yP_1-y as examples that the Fermi energy (E_F) oscillates with inverse quantizing magnetic field (1/B) and increases with increasing electron concentration with different numerical magnitudes which is the signature of respective band structure. The numerical value of the Fermi energy is different in different cases due to the different values of the energy band constants.

Pristine TiO₂ and x% Ru/TiO₂ catalysts with different wt.% of Ru (x%= 1.5%, 2%, 2.5% and 3%) were synthesized using sol-gel and simple impregnation methods. Different characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), High-resolution transmission electron microscope (HR-TEM), Inductively coupled plasma-optical emission spectrometry (ICP-OES) and Thermogravimetry/Differential thermal analysis (TG/DTA) were used to study the physicochemical and morphological properties. The XRD patterns of the as-prepared pristine TiO₂ catalyst showed high crystalline nature. The HR-TEM images revealed that the Ru nanoparticles (NPs) were evenly dispersed on the TiO₂ surface. The prepared catalysts were evaluated for their catalytic activity towards the liquid phase hydrogenation of ethyl levulinate under mild reaction conditions (ambient H2 pressure). Among the various catalysts, 2.5% Ru/TiO₂ catalyst showed the maximum catalytic activity of 79% ethyl levulinate (EL) conversion with 82% selectivity of γ-valerolactone (GVL). The recyclability test revealed that the most active 2.5% Ru/TiO₂ also showed the highest stability of the catalyst under optimized experimental conditions.

The widespread application of artificial superhydrophobic material is hindered by the poor durability and regeneration of artificial superhydrophobicity. The problem is expected to be resolved by endowing the superhydrophobic material with self-similarity. Herein, Copper-based superhydrophobic material intensified by furfuryl alcohol resin (Cu/FAR) with long-term durability and high strength is developed, and the obtained Cu/FAR composite reveals excellent and durable superhydrophobicity. Moreover, it is a remarkable fact that the as-prepared superhydrophobic Cu/FAR exhibits outstanding durability and maintenance of superhydrophobicity grounded on the good self-similarity in micro-structure, chemical structure and composition both externally and internally. Consequently, the superhydrophobicity can be maintained or regenerated without difficulty even if superhydrophobic surface has been damaged or fouled accidentally. Therefore, the method provides a new thought to prepare superhydrophobic material with robust durability and outstanding maintenance.

Chitosan (CS), the only alkaline polysaccharose available in nature, has always been a promising candidate for drug delivery owing to its excellent biodegradability and biocompatibility. However, inherent solubility and polycationic properties of CS largely hinder electrospinning, which is an efficient method of fabricating nanofibers for drug carriers. To solve this problem and extend the applications of CS, polyamide/chitosan/tetraethyl orthosilicate (PA/CS/TEOS) composite nanofibers were successfully prepared as drug carriers in this study via electrospinning. The PA/CS/TEOS ratios significantly influenced the nanofiber morphology. As the content of each was increased, the beads among the membranes increased initially and then decreased, determined by scanning electron microscopy (SEM). The morphology of the optimum membranes with the ratio of 1:0.13:0.67 was smoother with less beads and uniform fiber diameter. Finally, the membranes with optimum ratios were used as carriers of ofloxacin in the study of drug release performance to identify their future feasibility, which revealed an initial fast release followed by a relatively stable release.