AFM probe based nano mechanical scribing of soda-lime glass

In recent years, demands for miniature components have increased due to their reduced size, weight and energy consumption. In particular, brittle materials such as glass can provide high stiffness, hardness, corrosion resistance and high-temperature strength for various biomedical and high-temperature applications. In this study, cutting properties and the effects of machining parameters on the ductile cutting of soda-lime glass are investigated through the nano-scale scratching process. In order to understand the fundamentals of the material removal mechanism at the atomic scale, such as machined surface quality, cutting forces and the apparent friction, theoretical investigation along with experimental study are needed. Scribing tests have been performed using a single crystal diamond atomic force microscope (AFM) probe as the scratching tool, in order to find the cutting mechanism of soda-lime glass in the nano-scale. The extended lateral force calibration method is proposed to acquire accurate lateral forces. The experimental thrust and cutting forces are obtained and apparent friction coefficients are deduced. The effects of feed rates and the ploughing to shearing transition of soda-lime glass have been investigated.     

Optimized processing power and trainability of neural network in numerical modeling of Al Matrix nano composites

In this research, an experimental study of reinforcing alumina nano-particles into the aluminum alloy matrix was implemented to verify the accuracy of modeling results obtained by feed forward neural networks. Artificial neural network combined with numerical technique were used to predict the various parameters of mechanical properties such as hardness, tensile and compressive yield stress, UTS and elongation percentage. Much experimentation were taken to discover a suitable number of hidden neurons, avoid detraction from the trainability and enable feed forward neural networks to solve more complex problems. The predictions were found to be consistent with experimental measurements.     

A highly porous animal bone-derived char with a superiority of promoting nZVI for Cr(VI) sequestration in agricultural soils

Paddy soil and irrigation water are commonly contaminated with hexavalent chromium [Cr(VI)] near urban industrial areas, thereby threatening the safety of agricultural products and human health. In this study, we develop a porous and high specific area bone char (BC) to support nanoscale zero-valent iron (nZVI) and apply it to remediate Cr(VI) pollution in water and paddy soil under anaerobic conditions. The batch experiments reveal that BC/nZVI exhibits a higher removal capacity of 516.7 mg/(g?nZVI) for Cr(VI) than nZVI when normalized to the actual nZVI content, which is 2.8 times that of nZVI; moreover, the highest nZVI utilization is the nZVI loading of 15% (BC/nZVI15). The Cr(VI) removal efficiency of BC/nZVI15 decreases with increasing pH (4 – 10). Coexisting ions (phosphate and carbonate) and humic acid can inhibit the removal of Cr(VI) with BC/nZVI15. Additionally, BC exhibits a strong advantage in promoting Cr(VI) removal by nZVI compared to the widely used biochar and activated carbon. Our results demonstrate that reduction and coprecipitation are the dominant Cr(VI) removal mechanisms. Furthermore, BC/nZVI15 shows a significantly higher reduction and removal efficiency as well as a strong anti-interference ability for Cr(VI) in paddy soil, as compared to nZVI. These findings provide a new effective material for remediating Cr(VI) pollution from water and soil.     

Impact of nano particles on safety and environment for fireworks chemicals

Pyrotechnic devices, commonly known as fireworks, have a huge popularity. The sonic effect produced by the fireworks mainly depends upon the chemical composition of the mixtures and the particle size. Specifically this means that the larger the particle size, the more the quantity of powder mixture is to be used. Therefore, a high quality product which can produce the expected noise level with lesser quantity of chemicals is a major challenge faced by the pyrotechnic industry. This can be achieved by adopting either of the two approaches namely, one, by changing the chemical composition or, the other, by changing the particle size. At present the particle size of the chemical composition is at the micron level. However, by converting the composition into nano size, the volume of mixture used will be greatly reduced without compromising the sound level produced. The major advantage of using nano size powders is that it is essentially environmental friendly, producing less pollution and ensuring a cleaner environment. Concurrently, the major risk in using nano size powders is that it is a fire hazard. In this paper, the pros and cons of using nano powders in the manufacture of fireworks have been analyzed, collecting data from various research works and presenting the same as a review article.     

Effects of different types of biochar on the properties and reactivity of nano zero-valent iron in soil remediation

• Biochar enhanced the mobility and stability of zero-valent iron nanoparticles. • Particle performance was best when the BC:nZVI mass ratio was 1:1. • Bagasse-BC@nZVI removed 66.8% of BDE209. The addition of nano zero-valent iron (nZVI) is a promising technology for the in situ remediation of soil. Unfortunately, the mobility and, consequently, the reactivity of nZVI particles in contaminated areas decrease due to their rapid aggregation. In this study, we determined how nZVI particles can be stabilized using different types of biochar (BC) as a support (BC@nZVI). In addition, we investigated the transport behavior of the synthesized BC@nZVI particles in a column filled with porous media and their effectiveness in the removal of BDE209 (decabromodiphenyl ether) from soil. The characterization results of N₂ Brunauer–Emmett–Teller (BET) surface area analyses, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) indicated that nZVI was successfully loaded into the BC. The sedimentation test results and the experimental breakthrough curves indicated that all of the BC@nZVI composites manifested better stability and mobility than did the bare-nZVI particles, and the transport capacity of the particles increased with increasing flow velocity and porous medium size. Furthermore, the maximum concentrations of the column effluent for bagasse–BC@nZVI (B–BC@nZVI) were 19%, 37% and 48% higher than those for rice straw–BC@nZVI (R–BC@nZVI), wood chips–BC@nZVI (W–BC@nZVI) and corn stalks–BC@nZVI (C–BC@nZVI), respectively. A similar order was found for the removal and debromination efficiency of decabromodiphenyl ether (BDE209) by the aforementioned particles. Overall, the attachment of nZVI particles to BC significantly increased the reactivity, stability and mobility of B–BC@nZVI yielded, and nZVI the best performance.     

Role of nano-additive blended biodiesel on emission characteristics of the research diesel engine

The current experimental study is aimed to analyze the influence of single-walled Carbon Nano Tubes (CNT) on the emission characteristics of neem biodiesel-fueled (NBD-fueled) diesel engine and the results compared with conventional diesel. Experiments were conducted in a single-cylinder, 4-stroke, diesel engine with an eddy current dynamometer at a constant speed of 1500 rpm. Two samples of CNT are characterized and dispersed into 100% of the NBD in a mass fraction of 50 and 100 ppm using ultrasonicator, and the physicochemical properties were measured. Experimental results indicated that by adding CNT nanoparticles in NBD reduces its NO_x, HC, CO, and smoke emission by 9.2%, 6.7%, 5.9%, and 7.8%, respectively, at all load conditions.     

纳米ZnO光催化材料的掺杂改性研究进展

纳米ZnO光催化材料的研究进展迅速,其光催化性能已接近或超过商业生产中用到的TiO_2材料(Degussa P25),而且它相比TiO_2材料更易于掺杂、更易刻蚀、在等离子体中稳定性好,未来有望在水污染治理和环境保护领域取代TiO_2光催化剂。概述了纳米ZnO光催化材料的制备、性能和掺杂改性研究进展,对纳米ZnO光催化材料的研究趋势进行了展望。     

ZnO-NPs对好氧反硝化细菌Zobellella sp. B307的致毒机制

本文以一株筛自胶州湾沉积物中的好氧反硝化细菌Zobellella sp.B307为研究对象，在短期暴露条件下，通过细菌的生长、脱氮能力，相关酶活以及代谢途径等指标的变化，研究纳米氧化锌（ZnO-NPs）对该菌株的毒性效应；结合锌离子溶出试验、CAT和ROS等氧化应激水平测定，探讨ZnO-NPs对该菌株的致毒机制.结果表明，200mg/L的ZnO-NPs会使菌株硝酸盐氮去除率降至57.53%，LDH升高至对照组的378%，ROS水平高达对照组的5.34倍，SOD活性比对照组升高了60.32%，NIR活性仅为对照组的14.46%；ZnO-NPs主要通过诱导菌株活性氧的生成使其膜通透性改变、相关酶活性下降，并使相关蛋白质、氨基酸的合成及基因表达等代谢通路受到影响，进而抑制该菌株的反硝化能力；游离锌离子的产生可能不是ZnO-NPs对菌株的主要致毒途径.     

Assessing the impact of nano- and micro-scale zerovalent iron particles on soil microbial activities: particle reactivity interferes with assay conditions and interpretation of genuine microbial effects

The effects of nano-scale and micro-scale zerovalent iron (nZVI and mZVI) particles on general (dehydrogenase and hydrolase) and specific (ammonia oxidation potential, AOP) activities mediated by the microbial community in an uncontaminated soil were examined. nZVI (diameter 12.5 nm; 10 mg g⁻¹ soil) apparently inhibited AOP and nZVI and mZVI apparently stimulated dehydrogenase activity but had minimal influence on hydrolase activity. Sterile experiments revealed that the apparent inhibition of AOP could not be interpreted as such due to the confounding action of the particles, whereas, the nZVI-enhanced dehydrogenase activity could represent the genuine response of a stimulated microbial population or an artifact of ZVI reactivity. Overall, there was no evidence for negative effects of nZVI or mZVI on the processes studied. When examining the impact of redox active particles such as ZVI on microbial oxidation-reduction reactions, potential confounding effects of the test particles on assay conditions should be considered.     

Zero-valent manganese nanoparticles coupled with different strong oxidants for thallium removal from wastewater

• Nano zero-valent manganese (nZVMn, Mn⁰) is synthesized via borohydrides reduction. • Mn⁰ combined with persulfate/hypochlorite is effective for Tl removal at pH 6-12. • Mn⁰ can activate persulfate to form hydroxyl and sulfate radicals. • Oxidation-induced precipitation and surface complexation contribute to Tl removal. • Combined Mn⁰-oxidants process is promising in the environmental field. Nano zero-valent manganese (nZVMn, Mn⁰) was prepared through a borohydride reduction method and coupled with different oxidants (persulfate (S₂O₈²⁻), hypochlorite (ClO⁻), or hydrogen peroxide (H₂O₂)) to remove thallium (Tl) from wastewater. The surface of Mn⁰ was readily oxidized to form a core-shell composite (MnO_x@Mn⁰), which consists of Mn⁰ as the inner core and MnO_x (MnO, Mn₂O₃, and Mn₃O₄) as the outer layer. When Mn⁰ was added alone, effective Tl(I) removal was achieved at high pH levels (>12). The Mn⁰-H₂O₂ system was only effective in Tl(I) removal at high pH (>12), while the Mn⁰-S₂O₈²⁻ or Mn⁰-ClO⁻ system had excellent Tl(I) removal (>96%) over a broad pH range (4–12). The Mn⁰-S₂O₈²⁻ oxidation system provided the best resistance to interference from an external organic matrix. The isotherm of Tl(I) removal through the Mn⁰-S₂O₈²⁻ system followed the Freundlich model. The Mn⁰ nanomaterials can activate persulfate to produce sulfate radicals and hydroxyl radicals. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that oxidation-induced precipitation, surface adsorption, and electrostatic attraction are the main mechanisms for Tl(I) removal resulting from the combination of Mn⁰ and oxidants. Mn⁰ coupled with S₂O₈²⁻/ClO⁻ is a novel and effective technique for Tl(I) removal, and its application in other fields is worthy of further investigation.