微波强化制备银基蒙脱土研究

在微波强化条件下通过离子交换法制备了银基蒙脱土(Ag-MMT),与传统溶液离子交换法相比具有反应时间短、工艺简单、能耗少和阳离子交换容量高的优点。系统的研究了微波强化时间、硝酸银溶液浓度和微波功率等对Ag-MMT的银离子负载量的影响,并在模拟体液环境中测定了Ag-MMT中Ag+缓释性能,用傅里叶转换红外光谱(FT-IR)对材料进行了分析和表征。     

Controlled synthesis of monodisperse silver nanocubes via a solvothermal method

Silver nanostructures have been synthesized via a simple solvothermal method by adding sodium sulfide (Na₂S) into the solution. The morphologies of products are controlled by the concentration of Ag₂S formed in the initial stage. A low-concentration Ag₂S (12.5 ~ 50 μM) acts as the catalysis, leading to the formation of silver nanocubes with controllable sizes. However, a high-concentration Ag₂S (100 μM) mainly acts as the controlling agent. It facilitates the synthesis of silver nanowires. Reaction conditions, the reaction temperature and the molar ratio of the repeating unit of PVP to AgNO₃ (R), have also been investigated. A possible mechanism is proposed to interpret the synthesis of silver nanocubes and nanowires. Finally, our results indicate that this strategy provides a simple route to prepare silver nanocubes with adjustable sizes.     

微波辅助快速合成水溶性CdTe/CdSe核壳量子点

以巯基乙酸(TGA)作为稳定剂,用微波辅助法快速合成了水溶性CdTe/CdSe核壳量子点.比较了传统水热法和微波辅助法制备的量子点性能,研究了加热温度、反应物配比及CdTe量子点浓度对CdTe/CdSe核壳量子点的性能影响.研究结果表明,核壳结构的CdTe/CdSe量子点比单一的CdTe量子点具有更优异的光致发光强度和...     

Rapid synthesis of highly stable silver nanoparticles and its application for colourimetric sensing of cysteine

A modified green approach for the synthesis of stable silver nanoparticles (AgNPs) using tea leaf extract is described. The method involves the reduction of silver salt by the polyphenols present in the green tea leaf extract and requires no additional capping/stabilising agents. Compared to other biogenic methods for the synthesis of AgNPs, the uniqueness of the approach described here lies in its simplicity, low-cost, and rapid synthesis rate; the reaction being completed within 10–15 min at room temperature. The reaction was carried out in alkaline medium without stirring and heating, and requires no special cleaning or drying of the glassware used. The synthesised AgNPs were characterised by UV–Vis spectroscopy and transmission electron microscopy (TEM). The results showed that AgNPs with a strong surface plasmon resonance peak around 410 nm and particle size in the 5–30 nm range were prepared. The synthesised AgNPs show excellent chemical stability for more than six months in aqueous solution. Additionally, we showed that the as-synthesised AgNPs can be used as highly selective colorimetric and optical sensors for the detection of cysteine. Thus, with a simple synthesis strategy, and enhanced stability, these green-tea-functionalised AgNPs have the potential for further applications as biosensors and antimicrobial agents.     

Facile and scalable synthesis of a highly hydroxylated water-soluble fullerenol as a single nanoparticle

A water-soluble polyhydroxylated fullerene, i.e. a fullerenol, with 44 hydroxyl groups and 8 secondary bound water molecules, C₆₀(OH)₄₄·8H₂O (estimated average structure), has been synthesized in a facile one step reaction from pristine C₆₀ by hydroxylation with hydrogen peroxide in the presence of a phase-transfer catalyst, tetra-n-butylammonium hydroxide (TBAH), under organic/aqueous bilayer conditions. The fullerenol exhibited high water solubility, up to 64.9 mg/mL, under neutral (pH = 7) conditions. Dynamic light-scattering (DLS) analysis showed a narrow particle size distribution, of 1–2 nm, indicating that the fullerenol had high dispersion properties in water. The results of particle size analyses, which both focused on a single nanoregion and were conducted using a novel induced grating (IG) method and a scanning probe microscope (SPM), were consistent with the DLS results. A plausible reaction mechanism, which includes fullerene oxide intermediates detected by liquid chromatography-mass spectrometry (LC-MS), has been proposed.     

Synthesis of silver nanoparticles using N 1, N 2-diphenylbenzamidine by microwave irradiation method

Silver nanoparticles have been prepared under microwave irradiation from a solution of silver nitrate in the presence of N ¹,N ²-diphenylbenzamidine (DPBA) or simply amidine without any stabilizing agent. Different morphologies of silver colloids with charming colors could be obtained using N ¹,N ²-diphenylbenzamidine (DPBA). The structures of silver colloids were determined by TEM. UV-Vis spectroscopy was used to follow the reaction process and to characterize the optical properties of the resultant silver colloids. The influence of unconventional reducing agent on the morphology of silver was investigated.     

基于微波辐照合成类石墨烯氮化碳的研究进展

类石墨烯氮化碳具有与石墨烯非常相似的结构特征,已在光催化、润滑等领域表现出极优越的性能,成为二维纳米功能材料领域的新热点。本文重点介绍了基于微波辐照合成类石墨烯氮化碳的研究进展,并通过与氧化刻蚀、液相超声剥离、热聚合等传统合成方法的比较,分析了微波合成在制备效率、效果上的优势;并指出采用高功率微波设备和石墨粉、短切碳纤维等对微波具有强烈响应的微波吸收剂,通过增强能量传递与吸收效率,强化微波电磁场环境下合成反应的非稳态程度,有助于提高合成效率、效果,并获取得到特殊形态、结构的新产物。     

One-pot synthesis of highly luminescent CdTe quantum dots by microwave irradiation reduction and their Hg2+-sensitive properties

A facile one-pot microwave irradiation reduction route has been developed for the synthesis of highly luminescent CdTe quantum dots using Na₂TeO₃ as the Te source in an aqueous environment. The synthesis parameters of this simple and rapid approach, including the reaction temperature and time, the pH of the reaction solution and the molar ratio of the 3-mercaptopropionic acid (MPA) stabilizer to Cd²⁺, have considerable influence on the particle size and photoluminescence quantum yield of the CdTe quantum dots. The photoluminescence quantum yield of CdTe quantum dots prepared using relatively short reaction times (10–40 min) reached 40%–60% (emission peaks at 550–640 nm). Furthermore, the resulting products could be used as fluorescent probes to detect Hg²⁺ ions in aqueous media. The response was linearly proportional to the concentration of Hg²⁺ ion in the range 8.0×10⁻⁹ mol/L to 2.0×10⁻⁶ mol/L with a detection limit of 2.7×10⁻⁹ mol/L. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users.     

Solid-state synthesis of cubic ZnTe nanocrystals using a microwave plasma

Cubic ZnTe nanocrystals were produced from 1:1 and 1.8:1 molar ratios of Zn:Te by a 900 W microwave plasma. The phase was detected using X-ray diffraction (XRD), which are in accordance with those of the simulations, and selected area electron diffraction (SAED). Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the products were nanocrystals with different orientations, including three longitudinal optical (LO) vibrations at 205, 410 and 620 cm^? 1 and a transverse optical (TO) vibration at 166 cm^? 1. Their green emissions were detected at 562 nm (2.21 eV) using luminescence spectrophotometry.     

Green synthesis,characterisation and bioactivity of plant‐mediated silver nanoparticles using Decalepis hamiltonii root extract

Consistent search of plants for green synthesis of silver nanoparticles (SNPs) is an important arena in Nanomedicine. This study focuses on synthesis of SNPs using bioreduction of silver nitrate (AgNO₃) by aqueous root extract of Decalepis hamiltonii. The biosynthesis of SNPs was monitored by UV–vis analysis at absorbance maxima 432 nm. The fluorescence emission spectra of SNPs illustrated the broad emission peak 450–483 nm at different excitation wavelengths. The surface characteristics were studied by scanning electron microscope and atomic force microscopy, showed spherical shape of SNPs and dynamic light scattering analysis confirmed the average particle size 32.5 nm and the presence of metallic silver was confirmed by energy dispersive X‐ray. Face centred cubic structure with crystal size 33.3 nm was revealed by powder X‐ray diffraction. Fourier transform infrared spectroscopy indicated the biomolecules involved in the reduction mainly polyols and phenols present in root extracts were found to be responsible for the synthesis of SNPs. The stability and charge on SNPs were revealed by zeta potential analysis. In addition, on therapeutic forum, the synthesised SNPs elicit antioxidant and antimicrobial activity against Bacillus cereus, Bacillus licheniformis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus.Inspec keywords: silver, nanoparticles, nanomedicine, antibacterial activity, biomedical materials, nanofabrication, particle size, microorganisms, ultraviolet spectra, visible spectra, fluorescence, scanning electron microscopy, atomic force microscopy, light scattering, X‐ray diffraction, X‐ray chemical analysis, Fourier transform infrared spectra, molecular biophysics, electrokinetic effectsOther keywords: phenols, zeta potential analysis, therapeutic forum, antioxidant activity, antimicrobial activity, Bacillus cereus, Bacillus licheniformis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Ag, polyols, biomolecules, Fourier transform infrared spectroscopy, powder X‐ray diffraction, crystal size, face centred cubic structure, energy dispersive X‐ray analysis, metallic silver, particle size, dynamic light scattering analysis, spherical shape, atomic force microscopy, scanning electron microscopy, surface characteristics, excitation wavelengths, fluorescence emission spectra, UV‐visible analysis, biosynthesis, silver nitrate bioreduction, nanomedicine, Decalepis hamiltonii aqueous root extract, bioactivity, plant‐mediated silver nanoparticles, green synthesis     

Coupling matrix synthesis of cross-coupled microwave filters using a hybrid optimisation algorithm

A hybrid optimisation algorithm that synthesises coupling matrices for cross-coupled microwave filters is presented. A binary encoded genetic algorithm is combined at regular intervals with a sequential quadratic programming local search method to form a hybrid, exploiting the speed of the local search, while maintaining diversity with the genetic algorithm. The genetic algorithm uses the stochastic uniform selection technique and a multiple point crossover operator. A compact, efficient cost function requiring only the determinant and a cofactor of the coupling matrix is used as the basis of the optimisation algorithm. Optimisation algorithms simplify the process of synthesising coupling matrices, compared with analytical synthesis. However, algorithms that use only local search methods cannot be guaranteed to find a global minimum. This hybrid method aims to extend the range of coupling matrices that can be synthesised by optimisation, while maintaining the speed of search. A coupling matrix for a tenth order coupling matrix for a dual band symmetric filter and a seventh order asymmetric filter are synthesised to verify the method.     

High yield synthesis of PbS nanocubes using one-step solid-state reaction in the presence of an anionic surfactant

PbS nanocubes have been synthesized by one-step solid-state reaction between Pb(DS)₂ (DS: dodecylsulfate anion) and Na₂S·9H₂O. The nanocrystals were characterized by X-ray powder diffraction, Transmission electron microscopy, UV–vis absorption spectrum and X-ray photoelectron spectra. The research showed that the functionized surfactant lead dodecyl sulfate (LDS) played an important role in the formation of PbS nanocubes.     

Controlled synthesis and growth of perfect platinum nanocubes using a pair of low-resistivity fastened silicon wafers and their electrocatalytic properties

Perfect platinum (Pt) nanocubes with high density have been synthesized by controlled reduction of hexachloroplatinic acid in the presence of H₂SO₄ and HCl, employing a pair of low-resistivity fastened silicon (FS) wafers at room temperature. The presence of the additive charges (induced by prior etching of the silicon surface with HF to remove any SiO₂ layer) between the interfaces of the FS surface results in a high charge density and facilitates fast deposition of Pt nanoparticles via electroless plating. The charge density, stirring time, and homogeneity of the aqueous solution influenced the geometrical shapes of the Pt nanoparticles. The parameters were finely tuned in order to control the nucleation and growth rates and obtain perfect Pt nanocubes. The perfect Pt nanocubes were single crystalline with exposed {100} facets. Per equivalent Pt surface areas, the perfect Pt nanocubes showed enhanced catalytic activity relative to truncated Pt nanocubes or spherical Pt nanoparticles for the electrooxidation of liquid feed fuels such as methanol and ethanol. Moreover, there a strong correlation was observed between the optical, electrical, thermal, magnetic, and catalytic properties of the perfect Pt nanocubes which should lead to a variety of technological applications of these materials.     

Synthesis of highly ordered and hydrothermally stable mesoporous materials using sodium silicate as a precursor

Highly ordered mesoporous silica and aluminosilicate materials with extremely high hydrothermal stability have been synthesized successfully at a high hydrothermal treatment temperature of 200 °C by using inexpensive sodium silicate and sodium aluminate as the silica source and alumina source, respectively. The resultant mesoporous materials possess a hexagonal mesostructure and extraordinary stability towards the steam treatment at 800 °C for 2 h. In addition, the direct incorporation of Al into the mesoporous framework can further enhance the hydrothermal stability of ordered mesoporous materials. Our contribution provides a commercially important approach to synthesize ordered mesoporous materials with highly hydrothermal stability, which may find potential applications for the catalytic cracking in the petroleum industry.     

Green synthesis of highly stabilized nanocrystalline silver particles by a non-pathogenic and agriculturally important fungus T. asperellum

A controlled and up-scalable biosynthetic route to nanocrystalline silver particles with well-defined morphology using cell-free aqueous filtrate of a non-pathogenic and commercially viable biocontrol agent Trichoderma asperellum is being reported for the first time. A transparent solution of the cell-free filtrate of Trichoderma asperellum containing 1?mM AgNO(3) turns progressively dark brown within 5?d of incubation at 25?°C. The kinetics of the reaction was studied using UV-vis spectroscopy. An intense surface plasmon resonance band at ～410?nm in the UV-vis spectrum clearly reveals the formation of silver nanoparticles. The size of the silver particles using TEM and XRD studies is found to be in the range 13-18?nm. These nanoparticles are found to be highly stable and even after prolonged storage for over 6 months they do not show significant aggregation. A plausible mechanism behind the formation of silver nanoparticles and their stabilization via capping has been investigated using FTIR and surface-enhanced resonance Raman spectroscopy.     

Surfactant free rapid synthesis of hydroxyapatite nanorods by a microwave irradiation method for the treatment of bone infection

Mesoporous nanocrystalline hydroxyapatite (nHAp) rods of size 40-75 nm long and 25 nm wide (resembling bone mineral) were synthesized under microwave irradiation without using any surfactants or modifiers. The surface area and average pore size of the nHAp were found to be 32 m(2) g(-1) and 4 nm, respectively. Rifampicin (RIF) and ciprofloxacin (CPF) loaded nHAp displayed an initial burst followed by controlled release (zero order kinetics). Combination of CPF and RIF loaded nHAp showed enhanced bacterial growth inhibition against Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli) compared to individual agent loaded nHAp and pure nHAp. In addition, decreased bacterial adhesion (90%) was observed on the surface of CPF plus RIF loaded nHAp. The biocompatibility test toward MG63 cells infected with micro-organisms showed better cell viability and alkaline phosphatase activity (ALP) for the combination of CPF and RIF loaded nHAp. The influence on cell viability of infected MG63 cells was attributed to the simultaneous and controlled release of CPF and RIF from nHAp, which prevented the emergence of subpopulations that were resistant to each other. Hence, apart from the issue of the rapid synthesis of nHAp without surfactants or modifiers, the simultaneous and controlled release of dual drugs from nHAp would be a simple, non-toxic and cost-effective method to treat bone infections.     

Fast and simple reduction of graphene oxide in various organic solvents using microwave irradiation

The fabrication of graphene has been widely studied and chemical reduction is considered the most suitable approach to achieve large-scale production and graphene functionalization due to its versatility of chemical routes. We report here a fast and simple reduction of graphene oxide in various organic solvents using microwave irradiation. The reduction can be completed in several minutes, and the oxygen content and conductivity (10,000 S/m) of the reduced graphene oxide were comparable to the previously reported results which reported between 1 hr and 24 hrs for the reduction. We also found that an amide group containing a solvent like NMP or DMF reduced graphene oxide (GO) more effectively than did other solvents. Further, free radicals generated from NMP significantly enhanced deoxygenation of graphene oxide. Moreover, this approach is a non-toxic and environmentally-friendly method to obtain highly conductive reduced GO for a wide range of applications including graphene-based composites, batteries, and electrodes for super-capacitors.     

Rapid biologically one-step synthesis of stable bioactive silver nanoparticles using Osage orange (Maclura pomifera) leaf extract and their antimicrobial activities

Synthesis of nanoparticles by using natural products as reducing and stabilizing agents have been widely used in various fields especially medicine, primarily because of its lower cost, simplicity, and less toxic byproducts. In the present work, silver nanoparticles (Ag NPs) were rapidly synthesized from silver nitrate in a green one-step synthesis by the aqueous extracts of Osage orange (Maclura pomifera) leaf as a reducing and stabilizing agent simultaneously. The effects of pH, extract quantity, and silver salt concentration were investigated to determine the optimum conditions of green synthesis of Ag NPs. The synthesized Ag NPs were characterized by different techniques including UV–Visible (UV–Vis) absorption spectroscopy, X-ray diffraction (XRD), Fourier transform Infrared (FT-IR) Spectroscopy, and Transmission Electron Microscopy (TEM). The Ag NPs showed surface plasmon resonance centered at 415?nm. The XRD pattern and TEM analysis revealed spherical, stable, and uniform Ag NPs with the average particle size of about 12?nm. The FT-IR spectroscopy showed that mainly hydroxyl functional groups, as both the reducing and stabilizing agent are responsible for silver nanoparticles synthesis. The antimicrobial activity of the synthesized Ag NPs showed a significant microbicidal effect on all clinical isolates especially, Gram-negative bacteria and fungi. These results suggest that such stable and uniform Ag NPs can be synthesized rapidly and simply for clinical as well as pharmaceutical applications.     

Ensuring stable operation of ferroelectric microwave devices in a broad temperature range

Several approaches to ensuring stable operation of controlled ferroelectric microwave devices in a broad temperature range are considered. A new method is proposed for electrical compensation of the temperature dependence of the parameters of ferroelectric devices.