“锥形嵌套"结构CNx纳米管的生长机理及拉曼光谱研究

在氮气、氢气以及氯化铵热解产生的氨气环境下,以钴作为催化剂,在780℃—940℃温度范围内使二甲苯与二茂铁受热分解,合成了CNx纳米管.在高分辨率透射电子显微镜下观察,合成的纳米管呈现“锥形嵌套”的形貌特征.从不同结构的分子面形成能的角度探讨了CNx纳米管的催化生长机理.不同温度下所制备样品的拉曼光谱研究表明,ID/IG值可以反映氮的掺杂所带来的纳米管结晶有序程度的降低,并通过G带向高波数移动证实了氮的掺杂.     

Effect of material selection and background impurity on interface property and resulted CIP-GMR performance

In this paper, we investigated the effect of background base pressure, wafer-transferring time between process modules, and stack layer material selection on the current-in-plane giant magneto-resistive (CIP-GMR) interface properties and the resulted CIP-GMR performance. Experimental results showed that seed layer/AFM interface, AFM/pinned layer (PL) interface, pinned layer/Ru interface, and reference layer (RL)/Cu spacer interface are among the most critical ones for a CIP-GMR device. By reducing the background impurity level (water moisture and oxygen), optimizing the wafer process flow sequence, and careful stack-layer material selection, such critical interfaces in a CIP-GMR device can be preserved. Consequently, a much robust GMR performance control can be achieved.     

Tetramethylguanidinium‐polyallylamine (Tmg‐PA): A new class of nonviral vector for efficient gene transfection

Highly toxic polyallylamine (PA) was reacted with a varying amount of a novel linker, 6‐(N,N,N′,N′‐tetramethylguanidinium chloride) hexanoic acid (Tmg‐HA), to prepare a series of tetramethylguanidinium‐PA (Tmg‐PA) polymers, which were used as vectors for gene transfection. The extent of attachment of the linker, Tmg‐HA, to the PA backbone was determined by 2,4,6‐trinitrobenzene sulfonic acid assay. The modified polymers (Tmg‐PAs), when complexed with pDNA, exhibited good condensation ability. The nanoparticles, so formed, were characterized by their size and zeta potential and were subsequently evaluated for their toxicity and transfection ability on various mammalian cells, viz., HeLa, CHO, and HEK 293 cells. Mobility shift assay revealed that on increasing the percent substitution of Tmg‐HA onto PA (from Tmg‐PA1 to Tmg‐PA6), relatively higher amounts of modified polymers were required to retard the mobility of a fixed amount of DNA. Besides, Tmg‐PA polymers provided sufficient protection (ca. 84–88%) to bound DNA against nucleases and one of the formulations, Tmg‐PA2 (ca. 15% substitution) displayed the highest transfection efficiency outcompeting the commercial transfection reagent, Lipofectamine? with minimal cytotoxicity. More impressively, the transfection efficiency increased despite recording a decrease in the buffering capacity of the grafted polymers suggesting that buffering capacity is not the sole parameter in determining the gene delivery efficiency of a vector system. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Imidazole derivatives as the organic precursor of ZnO nano particle

N₁-Hydroxy-2,4,5-trisubstituted imidazoles were synthesized starting from 1,2-diketones. The crystal structure of 4,5-dimethyl-2-(3-nitrophenyl)-1H-imidazol-1-ol has been determined. An unusual intermolecular hydrogen bonding through the association of water molecule has been reported. These imidazole derivatives can be thought of as the organic precursor for the synthesis of zinc oxide nano particles.     

Dependence of electrical performance on structural organization in polymer field effect transistors

Organic semiconductors (OSCs) are strong contenders for use in printed, flexible electronics. Although organic electronic materials have been studied for many years, the physics of charge transport is still under investigation. This is in part due to variability resulting from the large variety of molecules that can be synthesized and inconsistency in electrical characterization due to device and processing conditions. Molecular ordering in OSCs is known to alter the charge transport characteristics and attention to long range and short range ordering provides clues as to the nature of transport pathways. Here, we study ordered regioregular poly(3‐hexylthiophene‐2,5‐diyl) films carefully prepared to obtain a set of three samples with incrementally increasing order on identical transistor architectures. Ordering was characterized using a variety of short and long range techniques to probe the coherence and number of crystallites formed during processing, and the correlation between these different measures of order are quantified. We observe three changes in transistor behavior that show a shift from non‐ideal to more textbook‐like characteristics with increasing order: reduction of the contact resistance, shift to field‐independent mobility, and a shift from a diode‐like (S‐shaped) to linear response at low lateral fields. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1063–1074     

MORPHOLOGY OF POLYURETHANES REVISITED BY COMPLEMENTARY AFM AND TEM

Cast, segmented polyetherurethanes with 30 and 50% hard-segment content (HSC), respectively, were studied by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Multi-phase segregation was observed in both samples on two levels (micro and nano) of structural organization. Spherulites with a prominent radial structure, built of branched fibrils and globules, were captured on the micrometer level. The use of AFM enabled us to investigate the nanostructure in the polyurethanes studied here. In the sample with low (30%) HSC, nano-scale phase separation was observed by AFM in areas outside the crystalline aggregates. The morphology in these domains exhibited short, rodlike hard domains embedded in the matrix of the soft segments. The other sample (50% HSC) contained four identifiable morphological features. These included spherulites, globules, bundles of lamellae, and nanophase-separated, rodlike hard domains, embedded in the soft-segment matrix.

The globules did not have any internal structure visible by AFM down to the nanometer scale. We speculate that the globules form as a result of macro-phase segregation, due to incompatibility of the reactants, during synthesis and may thus be identified as pockets of free hard segments. The AFM phase imaging has been very useful to observe the bundles of lamellae and the nanoscale phase-separated structures, which were not captured by TEM, due to large differences in AFM phase signal contrast between the hard and the soft domains.     

TEM Imaging of Mass-selected Polymer Molecules

Polyethylene glycol (PEG) molecules with masses below 1300amu are electrosprayed (ES) from solution, mobility-selected at high resolution in a differential mobility analyzer (DMA), collected on a grid and imaged by transmission electron microscopy (ES–DMA–TEM). The DMA resolves individual n-mers, and selects only one out of the many present in the original sample. Ion identity is established from parallel mass spectra (ES-MS). The images reveal spherical particles 1.46nm in diameter, in good agreement with the known ion mass and bulk density. The DMA-selection technique opens new paths for the study of very small particles.     

高橡胶含量透明MBS合成及其对PVC的改性

高橡胶含量透明ＭＢＳ合成及其对ＰＶＣ的改性高南，肖贵斌，胡伟军（上海大学化学系上海嘉定２０１８００）关键词　ＭＢＳ树脂，ＰＶＣ树脂，乳液聚合，塑料增韧，透射电镜ＭＢＳ（甲基丙烯酸甲酚－丁二烯－苯乙烯）树脂具有复杂的多相结构，可用作硬质聚氯乙烯（ＰＶＣ...     

TEM01模式激光对两能级原子的作用力研究

推导了两能级原子在稳态和小速度一阶微扰近似下的受力矢量方程，并分析表明ＴＥＭ０１模光场以原子的作用力中存在旋涡力，对在大正失谐δ〉〉Ω０〉〉Г和ｚ〈〈ｚ０＝ｋｗ＾２／λ条件下的ＴＥＭ０１模行波和驻波场中原子的受力进行了分析，对行波场，自发辐射对原子运动的影响很大，但在ｒ〈〈λ区域内原子受到横向囚禁力；对驻波场，自发辐射的影响可以忽略，考虑在ｚ方向波长范围内原子的平均受力得到的结论为：在横向，除了有