阳离子超细颜料色浆含量及电泳电压对阴极电泳漆效果的影响

为了改善阴极电泳漆漆膜的色泽、牢度、平滑度、致密与均匀度等性能,以有机颜料(P.Y.83)、十八烷基二甲基苄基氯化铵、去离子水制备了阳离子水性超细颜料色浆,并将其加入阴极电泳漆。探讨了阳离子水性超细颜料色浆含量及电压大小对漆膜外观、电沉积量及得色量的影响。结果表明:槽液电导率随着超细颜料色浆含量增加而增大;超细颜料色浆含量从4%增大到20%时,漆膜电沉积量从11.05g/m2增大到71.45 g/m2,K/S值从10.538 4增大11.053 7;超细色浆含量过大,影响漆膜外观的平整性;在较低电压范围内,漆膜光滑、平整,电沉积量、得色量随着电泳电压的增大而逐渐增大;电泳的电压过高时,漆膜粗糙,出现气泡、橘皮等现象,电沉积量急剧增大,得色量急剧下降。

超细负离子粉末在PP中分散性的研究

采用不同偶联剂表面处理环己烷-负离子粉末溶胶,通过离心沉降的方法研究了表面处理对负离子粉末表面性质的影响,并考察了聚丙烯／负离子粉末共混物的纺丝性能。结果表明,选择单烷氧型钛酸酯类偶联剂质量分数8％时,经过处理后负离子粉末与聚合物基体界面结合状况得到改善,微粒的分散性较好,表面处理效果最好。纺丝时组件压力上升情况得到明显改善,且纺丝状况比较稳定。

超细钙钛矿复合氧化物的制备和性能研究

钙钛矿型复合氧化物(ABO3)具有稳定的结构和较好的热稳定性,是一类被视为能够替代传统贵金属控制汽车尾气净化催化剂的新型三效催化剂.

超细羽绒粒子对三种不同染料吸附动力学研究

采用超细粉体加工技术制备了超细羽绒粒子,并对其粒径、孔结构等进行了表征。将制备的超细羽绒粒子应用于染料废水的处理,研究其对模拟染料废水溶液中酸性大红3R、直接耐酸大红4BS、还原大红R的吸附性能。结果表明:超细羽绒粒子的平均粒径是2.34±0.26μm,且具有良好的孔结构,其中以大孔为主,而且孔径分布较宽。动力学研究结构表明伪二级动力学方程可更好地描述超细羽绒粒子对酸性大红3R、直接耐酸大红4BS、还原大红R染料的吸附行为。

悬浮聚合法制备负离子聚合物微球的研究

以聚氨酯(PU)增稠的甲基丙烯酸甲酯(MMA)为分散剂、硅烷偶联剂KH-570为表面改性剂,通过球磨法利用偶联剂对超细负离子粉表面进行有机官能团改性,并制得悬浮性良好的分散料浆,再以此为分散相、水为连续相、聚乙烯醇(PVA)为分散稳定剂、过氧化苯甲酰(BPO)为引发剂,通过悬浮聚合制备包含有超细负离子粉末的聚合物微球。对微球制备过程中相关因素的分析结果表明:随着分散阶段搅拌速度的增大,微球粒径减小、负离子粉包覆率降低;聚氨酯含量的适当增加可以相应提高微球中负离子粉的有效含量;当搅拌转速为550r/min、BPO含量为1.4%、PVA浓度4.3%、PU加入量5.0%时,可以制得平均粒径25μm、负离子粉包覆率较好的聚合物微球。

Average cluster sizes and cluster size distributions of superfine nickel particles in light media

Effects of shear rates on average cluster sizes (ACSs) and cluster size distributions (CSDs) in uni- and bi-systems of partly charged superfine nickel particles were investigated by Brownian dynamics, and clustering properties in these systems were compared with those in non-polar systems. The results show that the ACSs in bi-polar systems are larger than those in the non-polar systems. In uni-polar systems the behavior of clustering property differs: at the lower ionic concentration (10%), repulsive force is not strong enough to break clusters, but may greatly weaken them. The clusters are eventually cracked into smaller ones only when concentration of uni-polar charged particles is large enough. In this work, the ionic concentration is 20%. The relationship between ACS and shear rates follows power law in a exponent range of 0.176-0.276. This range is in a good agreement with the range of experimental data, but it is biased towards the lower limit slightly.

Mitochondrial superoxide anions induced by exogenous oxidative stress determine tumor cell fate: an individual cell-based study

Objective: Reactive oxygen species(ROS) are involved in a variety of biological phenomena and serve both deleterious and beneficial roles. ROS quantification and assessment of reaction networks are desirable but difficult because of their short half-life and high reactivity. Here, we describe a pro-oxidative model in a single human lung carcinoma SPC-A-1 cell that was created by application of extracellular H2O2 stimuli. Methods: Modified microfluidics and imaging techniques were used to determine O2·- levels and construct an O2^·- reaction network. To elucidate the consequences of increased O2^·- input, the mitochondria were given a central role in the oxidative stress mode, by manipulating mitochondria-interrelated cytosolic Ca2+ levels, mitochondrial Ca^2+ uptake, auto-amplification of intracellular ROS and the intrinsic apoptotic pathway. Results and conclusions: Results from a modified microchip demonstrated that 1 mmol/L H·-2 O2 induced a rapid increase in cellular O2 levels(>27 vs.>406 amol in 20 min), leading to increased cellular oxidizing power(evaluated by ROS levels) and decreased reducing power(evaluated by glutathione(GSH) levels). In addition, we examined the dynamics of cytosolic Ca^2+ and mitochondrial Ca^2+ by confocal laser scanning microscopy and confirmed that Ca^2+ stores in the endoplasmic reticulum were the primary source of H2O2-induced cytosolic Ca^2+ bursts. It is clear that mitochondria have pivotal roles in determining how exogenous oxidative stress affects cell fate. The stress response involves the transfer of Ca^2+ signals between organelles,ROS auto-amplification, mitochondrial dysfunction, and a caspase-dependent apoptotic pathway.

Regulation of superoxide flashes by transient and steady mitochondrial calcium elevations

The mitochondria play essential roles in both intracellular calcium and reactive oxygen species signaling.As a newly discovered universal and fundamental mitochondrial phenomenon,superoxide flashes reflect transient bursts of superoxide production in the matrix of single mitochondria.Whether and how the superoxide flash activity is regulated by mitochondrial calcium remain largely unknown.Here we demonstrate that elevating mitochondrial calcium either by the calcium ionophore ionomycin or by increasing the bathing calcium in permeabilized HeLa cells increases superoxide flash incidence,and inhibition of the mitochondrial calcium uniporter activity abolishes the flash response.Quantitatively,the superoxide flash incidence is correlated to the steady-state mitochondrial calcium elevation with 1.7-fold increase per 1.0?F/F0 of Rhod-2 signal.In contrast,large mitochondrial calcium transients(e.g.,peak△F/F0~2.8,duration^2 min)in the absence of steady-state elevations failed to alter the flash activity.These results indicate that physiological levels of sustained,but not transient,mitochondrial calcium elevation acts as a potent regulator of superoxide flashes,but its mechanism of action likely involves a multi-step,slow-onset process.

The cytotoxicity of oxidized multi-walled carbon nanotubes on macrophages

Carbon nanotubes(CNTs) have been developed for medical and biotechnological applications in the past decades. Their widespread applications make it important to understand their potential hazards to human and the environment. In this study, the possible toxicological effects of the oxidized multi-walled carbon nanotubes(O-MWCNTs) were assessed on RAW 264.7 macrophages in vitro. Several toxicological endpoints, such as cell viability, the release of LDH and IL-8, GSH/GSSG ratio, intracellular calcium concentration and ultrastructural changes in cell morphology, were carried out. The results showed that O-MWCNTs had very limited effects on oxidative stress, cellular toxicity and apoptosis. Transmission electron microscope clearly demonstrates RAW 264.7 macrophages engulfed plenty of O-MWCNTs, and some of them resided in the cytoplasm, while the morphology was not altered by O-MWCNTs. As the control, the pristine MWCNTs(p-MWCNTs) show higher cytotoxicity than O-MWCNTs, damaging cell viability and inducing cell apoptosis. All these toxicological data are of benefit to more wide applications of O-MWCNTs in the future.