Synthesis of Silver Nanoparticles Using Ionic‐Liquid‐Based Microwave‐Assisted Extraction from Polygonum minus and Photodegradation of Methylene Blue

A green biogenic, nontoxic, high‐yielding synthetic method is introduced for the synthesis of silver nanoparticles (AgNPs) using ionic‐liquid‐based, microwave‐assisted extraction (ILMAE) from Polygonum minus . The aqueous ionic liquid (1‐butyl‐3‐methylimidazolium chloride [BMIM]Cl)‐based plant extract was used as reducing agent to reduce silver ions to AgNPs. The synthesis of AgNPs was confirmed by UV–visible spectrophotometry. Fourier transforms infrared (FTIR) spectra showed that the plant bioactive compounds capped the AgNPs. The particle size and morphology of Ag NPs were characterized by dynamic light scattering (DLS) and field emission scanning electron microscopy (FESEM), respectively. Elemental analysis was carried out by energy‐dispersive X‐ray (EDX) spectroscopy. Photodegradation studies showed that the AgNPs degraded 98% of methylene blue in 12 min.     

Calibration for Elemental Dental Tissue Analysis by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Teeth retain different elements at particular stages of life. Hence, the exposure over a selected time span may be characterized by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). A Nd:YAG laser with emission at 266?nm was coupled to a quadrupole ICP-MS for the quantitative study of historical human teeth for Sr and Ba, elements of anthropological significance. A calibration approach incorporating the experimentally derived k coefficient is reported. The coefficients were established based on the mean concentrations of the analytes determined by pneumatic nebulization ICP-MS using acid-digested calcium phosphate standards and the intensities recorded during laser ablation of corresponding standards as pellets. The k values were 0.54?±?0.05 (µg?g^?1)^?1 and 4.49?±?1.09 (µg?g^?1)^?1 for Sr and Ba, respectively. This calibration approach provided local quantitative data and demonstrated statistically significant differences in Sr concentrations in enamel and dentine.     

Elemental Analysis of Stone Fruits by Inductively Coupled Plasma Mass Spectrometry and Direct Mercury Analysis

This study reports the concentrations of eight trace essential (Zn, Mn, Cu, Ni, Cr, Co, V, and Se) and four toxic elements (Pb, As, Cd, and Hg) in commonly consumed stone fruits from South Korea. The samples were digested by microwave-induced combustion and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The concentrations of mercury were analyzed by direct mercury analysis (DMA). The analytical techniques were validated by linearity, limits of detection and quantification, precision, recovery, and for accuracy by analyzing a spinach leave-certified reference material; satisfactory results were obtained in all cases. The concentrations of essential trace elements varied considerably among the stone fruits. Generally stone fruits contained comparatively high concentrations of Zn (0.946 to 7.86?µg/g) and Mn (below the limit of detection to 1.66?µg/g), while lower contents of Cu (0.214 to 1.24?µg/g), Cr (0.032 to 0.114?µg/g), Ni (0.006 to 0.091?µg/g), Co (0.004 to 0.016?µg/g), V (below the limit of detection to 0.023?µg/g), and Se (0.0002 to 0.005?µg/g) were obtained. The concentrations (µg/g) of toxic metals were 0.007 (peach) to 0.016 (cherry) for Pb, 0.001 (plum) to 0.007 (cherry) for As, 0.002 (apricot and cherry) to 0.003 (peach) for Cd, and 0.0003 (peach) to 0.0016 (jujube) for Hg. The values for the estimated dietary intakes, target hazard quotients, and hazard indices were lower than the recommended safety limits by World Health Organization. Therefore, the analyzed stone fruits were deemed to be safe for human consumption.     

Iridium catalyzed alkylation of 2′-hydroxyacetophenone with alcohols under thermal or microwave conditions

2′-Hydroxyacetophenone was alkylated with a range of substituted benzyl and heteroaryl alcohols to afford the corresponding C-alkylated products in good yields under microwave irradiation. The C-alkylated products were reacted with bromoacetonitrile to afford 2-amino-3-benzyl 1,4-naphthoquinone derivatives in moderate yields.     

Growth mechanism of amorphous carbon by liquid plasma electrolytic deposition

The growth mechanism of amorphous carbon film by the liquid deposition process is still unclear. In this study, the influence of applied voltages on the surface morphology and microstructure of amorphous carbon films was investigated as well as the bonding probability at the film/substrate interface, and a new mechanism of film growth was proposed from the electrochemistry and non‐equilibrium thermodynamics viewpoints. The results showed that growth of amorphous carbon film involved the island groove morphology; more graphitic carbons are present within the film as the applied voltage increased. A coupling model of the growth mechanism including the ionization–absorption–dehydrogenation process and the chemical volume polymerization is highlighted. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of cold plasma process on the surface wettability of NBR and the kerosene resistance of NBR/PTFE composites

In this study, first the acrylonitrile‐butadiene rubber (NBR5080) was modified by argon (Ar), air, and oxygen plasma at low temperature, and the effect of plasma process (power, time, and pressure) on the surface properties of NBR5080, the interfacial properties, physical properties, and the mechanical properties of NBR5080/polytetrafluoroethylene (PTFE) composites were investigated. The state contact angle and the surface free energy were applied to characterize the surface wettability of NBR5080. The scanning electron microscope and the atomic force microscope were used to observe the surface morphology of the NBR5080. The chemical changes on the NBR5080 surface were verified by X‐ray photoelectron spectroscopy. The average water contact angle the NBR5080 declined obviously when NBR5080 was treated by Ar (100 W/600 s/30 Pa). The active oxygen groups were introduced onto the surface of NBR5080 by cold plasma treatment and more active group containing oxygen were observed on the samples treated by Ar plasma. The peel strength between the NBR5080 and the PTFE was increased obviously, which increased from 0 to 44.2 N?m^?1 for Ar plasma treatment. The mass and the dimension of NBR5080 increase sharply after immersing in kerosene, whereas the NBR5080/PTFE composites changed a little. The mechanical properties of NBR5080 and NBR5080/PTFE composites decreased as the immersion time in kerosene increased, but the decreased degree of NBR5080 is higher than NBR5080/PTFE composites.     

Porous product with reduced apparent density keeps good mechanical properties. Extruded composites of poly(vinyl chloride) blown under microwave irradiation

New foaming method, enhanced by microwave irradiation, was elaborated and applied to obtain porous poly(vinyl chloride) and its composites with fine cell structure. The so called “thermal runaway” effect was observed during the heating of poly(vinyl chloride) under microwave irradiation. The temperature of this effect decreases as a result of additives incorporation into polymer matrix. Microwave irradiation allowed effective heating of extruded poly(vinyl chloride) and its composites with carbon black (CB) filler, behind the extruder head and decomposing azodicarbonamide (ADC) to obtain porous products. The use of CB additive to poly(vinyl chloride) significantly increased its ability to be heated under microwave irradiation as well as improved the cell structure and decreased the apparent density of final products.Among additionally used fillers (1 wt%) the montmorillonite caused the apparent density decrease of foamed materials ca. 10%, however beneficially influenced on the quality of cells structure, giving the products with isotropic cells and the highest cell density as well as keeping the tensile strength on similar level as in the case of the materials with CB and ADC only.     

Effect of emulsification processes on the stability of Pickering emulsions stabilized by organomontmorillonites

In this paper, effect of emulsification processes on the properties of Pickering emulsions stabilized by organomontmorillonites (OMts) was studied. Results of micro-morphology and X-ray diffraction showed that the structure of OMt in emulsion depended on the emulsification processes and had an effect on the stability of emulsion. We propose a schematic diagram to reveal the relationship between emulsification processes-OMt laminates structure-stability of Pickering emulsion. In emulsion prepared by ultrasonic, OMt showed uniform dispersion, loose structure, and irregular crystalline. In emulsion prepared by vortex mixing method, OMt illustrated stacking and coagulation structure. In emulsion prepared by microwave method, OMt showed interacting structure and had a little interaction with oil/water interface, and thus the properties of emulsion prepared by microwave was weakly related to oil/water ratios. Emulsification processes had a profound effect on the structure of OMt and stability of Pickering emulsion, which can be used as a trigger to prepare emulsion for various applications.     

Using flow field-flow fractionation (Fl-FFF) for observation of salinity effect on the size distribution of humic acid aggregates

Flow field-flow fractionation (Fl-FFF) was used to investigate the effect of salinity on the size distribution of humic acid (HA) aggregates in estuarine water. In water with high salinity as estuarine water, size distributions were slightly broadened with increasing contact time between HA and estuarine water. At the longest contact times (89 days) and highest salinity value (28 psu, g kg^?1), the peak maxima were observed at 1.7 and 8.6 nm when detected at 254 nm, and at 1.9 and 9.1 nm when detected at 400 nm. In addition, Fl-FFF with an inductively coupled plasma mass spectrometry was applied to examine the effect of salinity on the size distribution of Cd, Ce, Cu, Mn and Pb-binding HA aggregates in estuarine water with different salinity values. At 1 day contact time, the peak maxima of Cd, Ce, Cu, Mn and Pb-binding HA aggregates in water with increased salinity values were increased and gave the larger breadth of size distribution. The larger size fraction of HA aggregates showed more affinity for Pb, Cd, Ce and Mn than Cu whereas the smaller size fraction of humic aggregates showed preferential binding towards Cu.     

CO2气氛苯尖端放电等离子体转化试验研究

本文研究了CO2为气化介质时,等离子体辅助煤气化过程中焦油组分苯发生的非热转化特性,建立了焦油组分苯、CO2单电极尖端放电非平衡态等离子体反应体系。通过煤气分析仪对转化反应的产物进行分析,并采用可见发射光谱技术对等离子体进行诊断。结果表明,在该反应体系中,苯转化生成的气态产物是CO与CO2的混合气,而H元素直接被氧化生成H20。能量密度对于苯转化反应起主导作用。在相同能量密度条件下,降低苯浓度也能够提高苯的转化率,但改变气速增加反应时间并不能提高苯的转化率。此外,通过光谱分析可得苯的非热转化可由CO2直接解离产生的O自由基触发。