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Cytotoxicity of nanomaterials on living systems is known to be affected by their size, shape, surface chemistry, and other physicochemical properties. Exposure to a well‐characterized subpopulation of specific nanomaterials is therefore desired to reveal more detailed mechanisms. This study develops scalable density gradient ultracentrifugation sorting of highly dispersed single‐walled carbon nanotubes (SWNTs) into four distinct bands based on diameter, aggregation, and structural integrity, with greatly improved efficiency, yield, and reproducibility. With guarantee of high yield and stability of four SWNT fractions, it is possible for the first time, to investigate the structure‐dependent bioeffects of four SWNT fractions. it is possible Among these, singly‐dispersed integral SWNTs show no significant effects on the mitochondrial functions and hypoxia. The aggregated integral SWNTs show more significant effects on the mitochondrial dysfunction and hypoxia compared to the aggregated SWNTs with poor structure integrity. Then, it is found that the aggregated integral SWNTs induced the irregular mitochondria respiratory and pro‐apoptotic proteins activation, while aggregated SWNTs with poor structure integrity greatly enhanced reactive oxygen species (ROS) levels. This work supports the view that control of the distinct structure characteristics of SWNTs helps establish clearer structure‐bioeffect correlation and health risk assessment. It is also hoped that these results can help in the design of nanomaterials with higher efficiency and accuracy in subcellular translocation.  相似文献   
3.
The paper describes the consequences of progressive damage in architectural high performance concrete when exposed to different heating treatments. Specimens were tested for uniaxial compressive, direct, and indirect tensile strengths at ambient conditions approximately one day after the exposure to the high temperature. Modifications in the microstructure, porosity, and pore size distribution of the fire deteriorated specimens were identified using scanning electron microscopy and mercury intrusion porosimetry techniques. Test results revealed no significant variations in the mechanical strengths for specimens exposed to temperatures up to 250 °C. Per contra, significant damage was observed for higher temperature, 500 °C and 750 °C, treatments, similar to that of ordinary concrete made with similar aggregates. Based on X-ray diffraction analysis, photocatalytic properties of the concrete were lost at 750 °C.  相似文献   
4.
We report on morphosynthesis techniques that have been employed to tune polyamine film nanoarchitectures and on their resulting morphologies. Specific layers discussed include films of aniline/Laponite clay and aniline solution processed with V2O5 catalyst. Synthesis approaches examined include films generated in-situ (glass templating), solution based drop casting, and mechanochemical grinding. Surface topography results suggest that these approaches provide dimensionality control of the polyaniline morphology. Surface images of the mechanochemically ground polyaniline/Laponite nanocomposite layer reveal interfacial contact which is promising for potential heterojunction solar cell designs.  相似文献   
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A variety of dibutyltin polyethers have been synthesized employing the interfacial polymerization technique. The products are polymers with degrees of polymerization ranging from 60 to 390. Infrared spectral and mass spectral results are consistent with the proposed structure. The products show good inhibition of a variety of cancer cells including those associated with bone, breast, prostrate, and lung cancers. Some also show good viral inhibition of the HSV-1 (herpes simplex) and Vaccina (small pox) viruses with those derived from electron rich hydroquinone derivative being most active. Hydroquinone-derived polymers containing electron withdrawing groups exhibit inhibition of a variety of gram positive and gram negative bacteria.  相似文献   
6.
《Fire Safety Journal》2005,40(5):411-424
In order to explain the detailed cause of the fire and explosion of asphalt–salt mixture (ASM) that happened at a nuclear wastes processing plant in Japan on March 11, 1997, a special experiment device was designed to prepare the ASM samples under different feeding rate of the waste and in different concentration of phosphate in the waste. The structure and diameter distribution of salt particles in the ASMs were examined by using a scanning electron microscope, the specific surface area of the salt particles was measured by the BET method, and the reactivity of ASMs was measured by using a heat flux calorimeter (C80). It was found that both the concentration of phosphate in the waste and the feeding rate of the waste have great influences on the structure of salt particles and the reactivity of the ASM. Most of the salt particles in the ASM are porous and have larger specific surface area when prepared at low feeding rate of the waste containing phosphate, which causes the ASM has lower onset temperature and self-accelerating decomposition temperature (SADT).  相似文献   
7.
Organotin polyamine ethers containing acyclovir in their backbone were synthesized in moderate to high yield employing the aqueous interfacial polycondensation system. The products are high molecular weight polymers. Infrared spectroscopy of the products shows new bands characteristic of the formation of Sn–N and Sn–O bonds consistent with the proposed structure. MALDI-TOF MS below 2000 Da shows the presence of organotin and acyclovir units containing these two moieties. The products show moderate inhibition of a number of cancer cell lines and exhibit the ability to inhibit a number of viruses, particularly the herpes simplex virus-1 and varicella zoster virus that are responsible for herpes, chicken pox and shingles.  相似文献   
8.
Anisotropic conductive adhesive film (ACF) can be preheated by microwave (MW) radiation in order to reduce the bonding time for flip-chip technology. Due to sluggish and nonuniform curing kinetics at the beginning of the curing reaction, thermal curing of epoxy is more time consuming. Therefore, MW radiation may be more effective, due to its uniform heating rate during the cycle. In this paper, MW preheating (for 1–4 sec) of ACF prior to final bonding has been applied to determine the electrical and mechanical performance of the bond. Powers of 80 and 240 W MW were used to study the effect of the MW preheating. A final bonding time of 6–7 sec can be used for flip chip on flex bonding instead of 10–15 sec (standard time for flip chip bonding) for MW preheating time and power used in this study. The contact resistance (as low as 0.01) is low in these samples, whereas the standard resistance is 0.017 ohm (bonded at 180°C for 10 sec without prior MW preheating). The shear forces at breakage were satisfactory (0.167–0.183 KN) for the samples bonded for 6–7 sec with MW preheating. This is very close and even higher than the standard sample (0.173 KN). For MW preheating power of 80 W and sweeping time of 2 sec, final bonding at 6 sec can also be used because of its low contact resistance (0.019 ohm). Scanning electron microscope (SEM) investigation of microjoints and fracture surface shows uneven distribution of conductive particles and thick bond lines in samples bonded for 5 sec (with MW preheating). Samples treated with MW radiation (80 W and 2–3 sec time) serve as evidence that well-distributed particles along with thin bond lines cause low contact resistance and high joint strength.  相似文献   
9.
Although assistive technology provides a promising means to accommodate for barriers to independence and self-determination for people with mental retardation, such devices are underutilized by this population. The Arc conducted a national survey of the use of assistive technology by people with mental retardation. In four of five areas, the percentage of individuals who used a device was under 10%. In two of these areas, the percentage of individuals who might benefit from a device exceeded the percentage who used a device, and in a third area, the percentage using devices was nearly equal to those who did not use but might benefit from a device. Availability and cost were reported as primary barriers. Suggestions were made to address these issues.  相似文献   
10.
Analysis of customer interactions for electronic customer relationship management (e-CRM) can be performed by way of using data mining (DM), optimization methods, or combined approaches. The microeconomic framework for data mining addresses maximizing the overall utility of an enterprise where transaction of a customer is a function of the data available on that customer. In this paper, we investigate an alternative problem formulation for the catalog segmentation problem. Moreover, a self-adaptive genetic algorithm has been developed to solve the problem. It includes clever features to avoid getting trapped in a local optimum. The results of an extensive computational study using real and synthetic data sets show the performance of the algorithm. In comparison with classical catalog segmentation algorithms, the proposed approach achieves better performance in Fitness and CPU-time.  相似文献   
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