Simple approach to analysis of switched-capacitor circuits with nonideal op-amps

A possible method for the simulation of nonideal op-amps with a finite gain and bandwidth by means of an equivalent SC circuit, containing ideal components, is presented. The approach is extended by the case of an op-amp with non-switched input SC building blocks.     

On the determination of the thermal diffusion factor from column measurements

A new method for experimental determination of the thermal diffusion factor _T for binary gas mixtures with a thermal diffusion column (TDC) is developed, based on A. M. Rozen's equation of TDC. The experimental results for _T are obtained in a reduced form in this approximation. An experimental reference point, determined in the same TDC with a standard gas mixture, is used for the transformation of the results for _T in absolute units. The proposed method is applicable for arbitrary gas mixtures, irrespective of the mass difference of the components.     

Physikalische und mechanische Eigenschaften von Polyester-Polyamid-bikonstituenten Fasern

In a pilot plant biconstitusent fibres with poly(ethylene terephthalate) as main component and poly(caproamid) as second component were produced. Their microstructure, their behaviour during melting and crystallization, some dynamic-mechanic and mechano-textile properties as well as some electrostatic, hygroscopic and dyeing properties were determined. The biconstituent fibres have a low capability for electrifying and tend to show a “pilling”-effect. Their dyeing abilities open possibilities for interesting dyeing effects. An aim of the investigation was to clear some changes in the physical and mechanical properties of the biconstituent fibres from the view of their fibrille-matrix-structure and from the mutual effect between the two components at the interphase.     

Induction of DNA-double-strand breaks by auger electrons from 99mTc complexes with DNA-binding ligands

The potential of certain Auger electron emitting nuclides for systemic radiotherapeutic applications has recently gained much attention. In particular, the ability of several nuclides, including 111In, 125I, and 123I, to induce DNA double-strand breaks (dsb), a good indicator of cytotoxicity, has been extensively studied. However, this ability has never previously been shown experimentally for 99mTc, which, besides the well-known gamma radiation that is used for diagnostic applications, also emits an average of 1.1 conversion electrons and 4 Auger or Coster-Kronig electrons per decay. Owing to the short range of Auger electrons, the radionuclide needs to be located very close to the DNA for dsb to occur. We synthesized two cationic 99mTcI-tricarbonyl complexes with pendant DNA binders, pyrene and anthraquinone. The X-ray crystal structures of the two complexes could be elucidated. Linear dichroism and UV/Vis spectroscopy revealed that the complex with pyrene intercalates DNA with a stability constant, K, of 1.1 x 10(6) M(-1), while the analogous complex with anthraquinone interacts with DNA in a groove-binding mode and has an affinity value of K=8.9 x 10(4) M(-1). We showed with phiX174 double-stranded DNA that the corresponding 99mTc complexes induce a significant amount of dsb, whereas non-DNA-binding [TcO4]- and nonradioactive Re compounds did not. These results indicate that the Auger electron emitter 99mTc can induce dsb in DNA when decaying in its direct vicinity and this implies potential for systemic radiotherapy with 99mTc complexes.     

Reactive Compatibilizer Precursors for LDPE/PA6 Blends, 4

Summary: The effectiveness of some thermoplastic elastomers grafted with maleic anhydride (MA) or with glycidyl methacrylate (GMA) as compatibilizer precursors (CPs) for blends of low density polyethylene (LDPE) with polyamide‐6 (PA) has been studied. The CPs were produced by grafting different amounts of MA or GMA onto a styrene‐block‐(ethylene‐co‐1‐butene)‐block‐styrene copolymer (SEBS) (KRATON G 1652), either in the melt or in solution. A commercially available SEBS‐g‐MA copolymer with 1.7 wt.‐% MA (KRATON FG 1901X) was also used. The effect of the MA concentration and of other characteristics of the SEBS‐g‐MA CPs was also studied. The specific interactions between the CPs and the blends components were investigated through characterizations of the binary LDPE/CP and PA/CP blends, in the whole composition range. It was demonstrated that the SEBS‐g‐GMA copolymers display poor compatibilizing effectiveness due to cross‐linking resulting from reactions of the epoxy rings of these CPs with both the amine and the carboxyl end groups of PA. On the contrary, the compatibilizing efficiency of the MA‐grafted elastomers, as revealed by the thermal properties and the morphology of the compatibilized blends, was shown to be excellent. The results of this study confirm that the anhydride functional groups possess considerably higher efficiency, for the reactive compatibilization of LDPE/PA blends, than those of the ethylene‐acrylic acid and ethylene‐glycidyl methacrylate copolymers investigated in previous works.

SEM micrograph of the 75/25 LD08/PA blend (with 2 phr SEBSMA1).     

High-resolution subunit detection of glutamate receptor by ultrasmall gold nanoparticles

In this study, we aimed to increase the sensitivity of protein labeling using 1.4 nm gold nanoparticles and glutamate δ2 receptor (GluD2) from the postsynaptic membrane of the Purkinje cells. The very small marker size of the particles reduces the steric hindrance between antibodies leading to a higher labeling efficiency of more than one subunit per single receptor molecule. The nanoparticles are visible in 200 kV dark‐field scanning transmission electron microscope on freeze‐fractured carbon replica of nervous tissue after plasma cleaning treatment. The different elemental composition of nanoparticles as Au nanogold or CdS quantum dot can be distinguished by energy dispersive X‐ray spectroscopy. This method ensures detection of an average of three subunits per GluD2 and often labels all four of them with 1.4 nm Au nanoparticles. It is concluded that this high‐resolution microscopic method is useful for exploring the quaternary structure of membrane proteins. Microsc. Res. Tech. 75:1159–1164, 2012. © 2012 Wiley Periodicals, Inc.     

Thermal behavior of poly(ethylene‐co‐propylene) containing carbon nanofibers

The effect of carbon nanofiber on the thermal behavior of poly(ethylene‐co‐propylene) (PEP) as revealed by differential scanning calorimetry and thermogravimetric analysis is reported. Analysis showed faster crystallization of PEP at higher temperature upon cooling with the increase of carbon nanofiber (CNF) content. The crystallization behavior changed to a single narrow crystallization peak as compared with the broad double crystallization peak of the neat polymer. This demonstrates the nucleation ability of CNF to induce crystals with more uniform distribution. The modified‐Avrami approach was used to study the crystallization behavior. We found that the crystallization rate constant increased with addition of CNFs. The dimensionality of crystal growth was found not to depend significantly on the content of CNF. Thermal degradation in air was monitored using thermogravimetric analysis and observed that the incorporation of nanofiber greater than 2.4 vol% improves thermal stability of PEP. All these results indicate that CNFs can significantly help polymer processing and increase thermal stability of polymers. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

催化逆流反应器(CH4MIN)技术及其在中国的应用潜力

通过一系列的试验，加拿大矿物与能源技术中心开发出了一项专门处理和利用煤矿矿井乏风中甲烷(甲烷体积浓度0．1％～1．0％)的技术——催化逆流反应器(CH4MIN)技术。CH4MIN技术是在催化剂的作用下，促使乏风混合气体的温度升高到足以让甲烷发生氧化，从而产生热量。通过利用这种热量达到利用乏风中甲烷的目的。本文从CH4MIN技术工作原理、试验结果分析、经济可行性分析及在中国的应用前景作了分析和论述。