Synthesis and Application of Stable Copper Oxide Nanoparticle Suspensions for Nanoparticulate Film Fabrication

Colloidal suspensions of copper oxide (CuO) nanoparticles were prepared by an alcothermal method, in which copper acetate was reacted with sodium hydroxide in the presence of acetic acid in ethanol at 78°C. The prepared suspension was stable for up to 1 month without stabilizers such as surfactants. Transmission electron microscopy analyses revealed that the suspension contained nanosized CuO particles of 5–10 nm size with a narrow size distribution. Nanoparticulate CuO films packed with grains smaller than 60 nm were fabricated on Si substrates by spin coating a suspension of CuO nanoparticles and subsequent heat treatment at 500°C.     

Subchronic Toxicity of Copper Oxide Nanoparticles and Its Attenuation with the Help of a Combination of Bioprotectors

In the copper metallurgy workplace air is polluted with condensation aerosols, which a significant fraction of is presented by copper oxide particles <100 nm. In the scientific literature, there is a lack of their in vivo toxicity characterization and virtually no attempts of enhancing organism’s resistance to their impact. A stable suspension of copper oxide particles with mean (±SD) diameter 20 ± 10 nm was prepared by laser ablation of pure copper in water. It was being injected intraperitoneally to rats at a dose of 10 mg/kg (0.5 mg per mL of deionized water) three times a week up to 19 injections. In parallel, another group of rats was so injected with the same suspension against the background of oral administration of a “bio-protective complex” (BPC) comprising pectin, a multivitamin-multimineral preparation, some amino acids and fish oil rich in ω-3 PUFA. After the termination of injections, many functional and biochemical indices for the organism’s status, as well as pathological changes of liver, spleen, kidneys, and brain microscopic structure were evaluated for signs of toxicity. In the same organs we have measured accumulation of copper while their cells were used for performing the Random Amplification of Polymorphic DNA (RAPD) test for DNA fragmentation. The same features were assessed in control rats infected intraperitoneally with water with or without administration of the BPC. The copper oxide nanoparticles proved adversely bio-active in all respects considered in this study, their active in vivo solubilization in biological fluids playing presumably an important role in both toxicokinetics and toxicodynamics. The BPC proposed and tested by us attenuated systemic and target organs toxicity, as well as genotoxicity of this substance. Judging by experimental data obtained in this investigation, occupational exposures to nano-scale copper oxide particles can present a significant health risk while the further search for its management with the help of innocuous bioprotectors seems to be justified.     

CuO/H2O纳米流体的池沸腾传热及预测

通过络合-沉淀法合成氧化铜纳米颗粒,制备铜颗粒的直径在40～100 nm,晶型为正六面体。利用“两步法”制备水基氧化铜纳米流体。考察了不同质量分数纳米流体的热导率、接触角变化和加热表面颗粒沉积对核沸腾传热性能的影响,并利用可视化记录沸腾过程气泡行为。结果表明：在测试质量分数范围内,传热系数随热通量增加而增大,当质量分数达到0.1%时,强化率最大为146.1%。经过分析可知纳米流体的接触角度、热导率、颗粒沉积以及颗粒扰动对水基氧化铜纳米流体强化传热作用均有影响。通过高速摄像采集质量分数0.07%纳米流体沸腾过程验证结论的可靠性。并对纳米流体核沸腾传热过程建立气泡动力学经验模型,模型计算结果与实测值相对偏差在±10%以内。     

Comparative in Vivo Assessment of Some Adverse Bioeffects of Equidimensional Gold and Silver Nanoparticles and the Attenuation of Nanosilver’s Effects with a Complex of Innocuous Bioprotectors

Stable suspensions of nanogold (NG) and nanosilver (NS) with mean particle diameter 50 and 49 nm, respectively, were prepared by laser ablation of metals in water. To assess rat’s pulmonary phagocytosis response to a single intratracheal instillation of these suspensions, we used optical, transmission electron, and semi-contact atomic force microscopy. NG and NS were also repeatedly injected intraperitoneally into rats at a dose of 10 mg/kg (0.5 mg per mL of deionized water) three times a week, up to 20 injections. A group of rats was thus injected with NS after oral administration of a “bioprotective complex” (BPC) comprised of pectin, multivitamins, some amino acids, calcium, selenium, and omega-3 PUFA. After the termination of the injections, many functional and biochemical indices and histopathological features of the spleen, kidneys and liver were evaluated for signs of toxicity, and accumulation of NG or NS in these organs was measured. From the same rats, we obtained cell suspensions of different tissues for performing the RAPD test. It was demonstrated that, although both nanometals were adversely bioactive in all respects considered in this study, NS was more noxious as compared with NG, and that the BPC tested by us attenuated both the toxicity and genotoxicity of NS.     

Morphological Control of Zirconia Nanoparticles through Combustion Aerosol Synthesis

Ceramic oxide nanoparticles produced by flame-based processes are typically agglomerated, which can limit their use in some applications. In this paper, a novel combustion synthesis method that utilizes the spraying of combustible droplets into a premixed flame to produce nanoscale crystalline particles of agglomerated and unagglomerated morphologies is described. Although the same flame-based experimental setup is used in both cases, variation in peak flame temperatures results in a corresponding variation between fractallike agglomerates and single isolated spherical particles. TEM/ED analysis shows that both classes of particles are the tetragonal crystal phase of zirconia. In the case of the unagglomerated spherical particles, results indicate that each precursor solution droplet, which acts as the feed, produces multiple spherical ceramic nanoparticles with a number mean diameter of 90 nm. The use of an inertial impaction stage in the precursor feed line to eliminate large feed droplets leads to a decrease in the number mean diameter to 60 nm, suggesting that crystalline spherical nanoparticles can be produced in a continuous flame-based process through control of the feed droplet size.     

不同体系剪切增稠液体的流变行为研究

剪切增稠液体是指其表观粘度随剪切速率增加而变大的一类流体。工业生产中,剪切增稠的出现会阻碍输送管道,破坏生产设备。针对这种情况,人们对如何降低流体粘度造成的不利影响进行了大量研究。另一方面,剪切增稠液体是“液体防弹材料”的关键组成部分,并且在减震、控制方面也具有可观的应用潜力。该文采用原生粒径为50 nm 的SiO2和80～100 nm 的 CaCO3分别作为分散相,聚乙二醇（PEG）200为分散介质,采用超声分散法制备得到不同固含量的剪切增稠液。并通过纳米粒度仪和扫描电镜对分散相粒子团聚情况进行分析;通过应力控制流变仪分别对 SiO2/PEG200和 CaCO3/PEG200悬浮分散体系的稳态流变性能进行分析。结果表明,两种体系试样在测试中均出现剪切增稠现象,并且分散相质量分数越高,剪切增稠效果越明显;而高质量分数的 SiO2/PEG200体系的粘度变化范围更大,增稠现象更为明显。     

氧化铜纳米粉体的制备工艺研究

以三水硝酸铜为反应物,氨水为络合剂,氢氧化钠为沉淀剂,乙醇水混合溶液为反应溶剂,聚乙二醇为分散剂,采用络合沉淀法,成功制备出平均粒径约20nm的氧化铜单晶纳米粉体。通过单因素实验和正交实验考察了硝酸铜溶液初始浓度、反应温度及氢氧化钠与硝酸铜物质的量比等因素对产物粒径大小的影响,利用x射线衍射（XRD）、透射电镜（TEM）和红外光谱仪（FT-IR）等对产物进行表征分析。研究结果表明,影响其粒径大小主要因素的主次顺序依次是：反应温度,硝酸铜溶液初始浓度及氢氧化钠与硝酸铜的物质的量比;优化制备工艺条件为：反应温度70℃,硝酸铜溶液初始浓度0．3mol／L,氢氧化钠与硝酸铜的物质的量比3：1,氨与硝酸铜的物质的量比5：1;氧化铜纳米粉体的红外吸收峰出现了红移和蓝移同时并存的反常现象。     

Preparation of Stabilized Nanosized Tin Oxide Particles by Hydrothermal Treatment

Stable colloidal suspensions of tin oxide (content 0.9–6.1 wt%) were synthesized by subjecting conventionally prepared tin oxide gels to hydrothermal treatment with an ammonia solution (pH 10.5) at 200°C for 3 h in an autoclave. Based on X-ray diffractometry analyses, the tin oxide crystallites after hydrothermal treatment were resistant to thermal growth at elevated temperatures, and this feature became more conspicuous as the tin oxide content of the colloidal suspension decreased. For the powder derived from a 1.8 wt% colloidal suspension, for example, the mean sizes of the tin oxide crystallites were 7.5 and 13 nm after calcination at 600° and 900°C, respectively, in comparison with corresponding values of 13.5 and 29 nm for the untreated gel-derived powder. Thin film spin-coated from the same suspension had good uniformity, packed with tin oxide grains (crystallites) of a mean size of 6 nm after calcination at 600°C. Optical determination of the tin oxide sol particle size, as well as gravimetric analysis of the dehydration from the powder samples, were conducted to determine effects of hydrothermal treatment.     

Effects of Rod‐like Particles on the Microstructure and Strength of Porous Silica Nanoparticle Composites

This study describes the results of an investigation into the effects of the addition of rod‐like silica nanoparticles on the properties of freeze‐cast and sintered bodies formed from silica nanospheres. Rod‐like silica particles with ～220 nm diameter and tunable aspect ratio from ～1 to ～12 (length/diameter) were prepared and added to aqueous suspensions containing 22 nm spherical silica particles. After freeze casting, porous composites were created with all suspensions, which is shown to be consistent with the results of a simple analysis in which the experimental freezing rate is compared with the critical rate at which the dispersed particles can no longer be expelled from the growing ice front. The composites have elongated spherical pores, and the pore size changes slightly with increasing aspect ratio of the nanorods. Finally, it was found that the rod‐like particles improve the flexural strength of the composites at both green and sintered states and this strengthening effect intensifies with increasing aspect ratio. This study provides a strategy for fabricating porous materials of improved properties and performance without compromising the porosity or changing the material composition.     

电化学方法制备氧化铜晶须

用电化学方法制备了氧化铜晶须。金属铜在含乙醇-水及毒化剂的混合碱性溶液中进行阳极氧化,煅烧后所得样品的成分和形貌用XRD和SEM方法表征。结果表明,晶须的物相是CuO和Cu2O,直径60～100nm,长度0.5～1μm,长径比8～10,同时用循环伏安法探讨了该过程的电化学行为,为晶须的制备提供了一种新的方法。     

Partially Reduced Cuprous Oxide Nanoparticles Formed in Porous Glass Reaction Fields

This paper describes the formation of cuprous oxide (Cu₂O) particles ∼10 nm in diameter and their reduction by hydrogen gas in porous glasses. Nanoparticles of Cu₂O coated with metallic copper are expected to show high third-order optical nonlinear susceptibilities (χ⁽³⁾). The porous glass is a medium in which nanoparticles can be partially reduced without forming agglomerations. Images obtained using transmission electron microscopy showed that particles with the desired core-shell structure were actually formed, even though some particles were not reduced uniformly from the surface. The χ⁽³⁾/α (α: absorbance) values in relevant conditions (10⁻¹³ esu·cm) were similar to that of copper because of the formation of a byproduct of copper nanoparticles on reduction.     

Nanoparticles and neurotoxicity

Humans are exposed to nanoparticles (NPs; diameter < 100 nm) from ambient air and certain workplaces. There are two main types of NPs; combustion-derived NPs (e.g., particulate matters, diesel exhaust particles, welding fumes) and manufactured or engineered NPs (e.g., titanium dioxide, carbon black, carbon nanotubes, silver, zinc oxide, copper oxide). Recently, there have been increasing reports indicating that inhaled NPs can reach the brain and may be associated with neurodegeneration. It is necessary to evaluate the potential toxic effects of NPs on brain because most of the neurobehavioral disorders may be of environmental origin. This review highlights studies on both combustion-derived NP- and manufactured or engineered NP-induced neuroinflammation, oxidative stress, and gene expression, as well as the possible mechanism of these effects in animal models and in humans.     

Particle characterisation in chemical looping combustion

In a chemical looping combustion process, as the oxygen carrier circulates the system, it is subjected to morphological and compositional changes such as sintering, attrition and reaction between metal oxides and fuels. These changes may cause the deactivation of the oxygen carrier to decrease over time. This research work is carried out to investigate and characterise the iron oxide and copper oxide particles used in a chemical looping combustion system after 20 reduction–oxidation cycles with 5 different fuels, (i.e. Hambach lignite coal, Hambach lignite char, activated carbon, Taldinski bituminous coal and US bituminous coal). Oxygen carriers used in this study were subjected to analyses with X-ray diffraction (XRD), inductive coupled plasma mass spectrometry (ICP-MS), scanning electron microscope (SEM) and BET surface area and full isotherm analysis.XRD analysis on these particles showed that the reduced particles were reoxidised back to their original form with trace amounts of impurities such as silicon dioxide (SiO₂) on the iron oxide particles whereas similar impurities plus copper complexes such as copper aluminate were detected on the copper oxide particles. ICP-MS analysis on these particles revealed that the concentration of the core metal elements (iron, copper and alumina) decreased after 20 reaction cycles which in turn decreased the total concentration of the metal elements in the particles. BET surface area analysis on these particles indicated that the total surface area of these particles decreased by more than 50% of their original values. Full isotherm analysis on the copper oxide particles showed that the total pore volume of the particles decreased after 20 reaction cycles even though the pore sizes of the particles increased slightly. SEM analyses showed the iron oxide particles underwent severe attrition whereas the copper oxide particles showed signs of agglomeration due to the high operating temperature.     

Carbon nanotubes and onions from carbon monoxide using Ni(acac)2 and Cu(acac)2 as catalyst precursors

New catalyst precursors (copper and nickel acetylacetonates) have been used successfully for the synthesis of carbon nanotubes and onion particles from carbon monoxide. Catalyst nanoparticles and carbon products were produced by metal-organic precursor vapour decomposition and catalytic disproportionation of carbon monoxide in a laminar flow reactor at temperatures between 705 and 1216 °C. Carbon nanotubes (CNTs) were formed in the presence of nickel particles at 923-1216 °C. The CNTs were single-walled, 1-3 nm in diameter and up to 90 nm long. Hollow carbon onion particles (COPs) were produced in the presence of copper particles at 1216 °C. The COPs were from 5 to 30 nm in diameter and consisted of several concentric carbon layers surrounding a hollow core. The results of computational fluid dynamics calculations to determine the temperature and velocity profiles and mixing conditions of the species in the reactor are presented. The mechanisms for the formation of both CNTs and COPs are discussed on the basis of the experimental and computational results.     

Influence of Filler Size on Impact Properties of PP/Elastomer/Filler Ternary Composites

Influence of filler size on impact properties for polypropylene (PP)/elastomer/filler ternary composites was investigated. Calcium carbonate (CaCO₃) particles with a diameter in the range from 120 to 1200 nm were used as a filler and polystyrene-block-poly(ethylene-butene)-block-polystyrene triblock copolymer (SEBS) was used as an elastomer. In the PP/SEBS/CaCO₃ ternary composite, CaCO₃ particles and SEBS particles were dispersed in the PP matrix separately. In the case that SEBS elastomer volume fraction was below 0.12, the impact strength improved gradually with a decrease of CaCO₃ mean diameter from 1200 to 160 nm. In the case that SEBS volume fraction was above 0.17, the impact strength improved significantly by the incorporation of CaCO₃ particles with a mean diameter in the range from 120 to 900 nm. However, the impact strength hardly improved by the incorporation of CaCO₃ particles with a mean diameter of 1200 nm.     

Modeling of ultrafine particle dispersion in indoor environments with an improved drift flux model

Ultrafine particle (sub-100 nm in diameter) can transport toxic chemicals into the human respiratory system, causing more damage to macrophage phagocytosis than micron particles do. Therefore, various computational fluid dynamics (CFD) models have been developed to help understand the transport and dispersion of these particles in indoor environments. This study is focused on an improved drift flux model that incorporates not only the effect of gravitational settling but also other mechanisms. After an experimental validation of the improved model, it was used to analyze the dispersion of different sizes of ultrafine particles in two typical types of indoor environments (mixing and displacement ventilation). It was found that mixing ventilation had higher concentrations of ultrafine particles than displacement ventilation in the zone below 1 meter, and this finding is different from micron range particles. In addition, both ventilation modes were insensitive to the particles in the range of 0.01–0.1 μm in diameter.     

Ultrafine particles cause cytoskeletal dysfunctions in macrophages: role of intracellular calcium

Background  

Particulate air pollution is reported to cause adverse health effects in susceptible individuals. Since most of these particles are derived form combustion processes, the primary composition product is carbon with a very small diameter (ultrafine, less than 100 nm in diameter). Besides the induction of reactive oxygen species and inflammation, ultrafine particles (UFP) can cause intracellular calcium transients and suppression of defense mechanisms of alveolar macrophages, such as impaired migration or phagocytosis.     

Preparation and characterization of nanosized copper (II) oxide embedded in hyper-cross-linked polystyrene: Highly efficient catalyst for aqueous-phase oxidation of aldehydes to carboxylic acids

Preparation and catalytic properties of nanosized copper (II) oxide embedded in hypercrosslinked polystyrene (HPS) were investigated in this article. The CuO@HPS nanocomposite was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), Fourier transform infrared spectroscopy (FT-IR), N₂-sorption analysis, X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy analysis (EDS), and transmission electron microscopy (TEM). The TEM analysis showed that the mean diameter of the resulted particles is ~ 4 nm.The nanocomposite was found to be efficient and durable catalyst in the oxidation of aldehydes to the corresponding carboxylic acids in water. The catalyst can be recycled and reused in 4 reaction runs.     

Platinum–Vanadium Oxide Nanotube Hybrids

The present contribution reports on the features of platinum-based systems supported on vanadium oxide nanotubes. The synthesis of nanotubes was carried out using a commercial vanadium pentoxide via hydrothermal route. The nanostructured hybrid materials were prepared by wet impregnation using two different platinum precursors. The formation of platinum nanoparticles was evaluated by applying distinct reduction procedures. All nanostructured samples were essentially analysed by X-ray diffraction and transmission electron microscopy. After reduction, transmission electron microscopy also made it possible to estimate particle size distribution and mean diameter calculations. It could be seen that all reduction procedures did not affect the nanostructure of the supports and that the formation of metallic nanoparticles is quite efficient with an indistinct distribution along the nanotubes. Nevertheless, the reduction procedure determined the diameter, dispersion and shape of the metallic particles. It could be concluded that the use of H₂PtCl₆ is more suitable and that the use of hydrogen as reducing agent leads to a nanomaterial with unagglomerated round-shaped metallic particles with mean size of 6–7 nm.     

Clusters Formation during Sedimentation of Dilute Suspensions

Abstract

Particle interactions in dilute monodispersed sedimenting suspensions of spherical particles are studied as a function of solid concentration. It is shown that in suspensions with solid concentrations below 0.83%, the interactions are too insignificant to effect the use of Stokes' law in sedimentation results. Beyond this concentration, however, a definite change in suspension behavior occurs, as particles come close enough to form clusters of varying sizes causing faster settling rates. Optimum clustering takes place around 4.5%-solid concentration, corresponding to mean interspacing of 2.2 particle diameter within suspension and giving settling rates 1.58 times faster than the Stokes' velocity for a mean particle. Clusters start breaking beyond this concentration as the sedimentation becomes more hindered and the return upward flow of liquid becomes increasingly tortuous. The probability of clusters formation and their stability as a function of particle size, concentration, and the Reynolds number of suspensions are also investigated. The studies are further extended to demonstrate the effect of “immobile” liquid within the clusters in interpreting the sedimentation results.