Volatility of Simulated High-Level Nuclear Waste Glass by Thermogravimetric Analysis

The volatilities of simulated, high-level nuclear waste glasses have been measured using thermogravimetric analysis (TGA). These volatilities were measured in the region of the glass transition temperature ( T _g) of the waste glasses, which is between 450° and 500°C. These data were obtained because the Waste Acceptance Preliminary Specifications require that no foreign materials be released into the canistered waste form upon heating of the canister to this glass transition temperature. In fact, all of the waste glass samples studied actually exhibited a net weight gain upon heating. This weight gain was shown to be due to oxygen uptake through oxidation of FeO. Powdered glass samples did show a small weight loss which was smaller in magnitude than the weight gain and was associated with water desorption. No true volatility was detected to the level of sensitivity (0.01 wt%) of the TGA instrument. This converts to a sensitivity of 330 μ g/m² of glass surface and a corresponding minimum value of 41 mg of volatiles for each Defense Waste Processing Facility conistered waste form. TGA experiments carried out at higher temperatures (800°C) revealed that organic concentrations in the waste glasses are less than 0.01 wt%. Thus, these results demonstrate that the Defense Waste Processing Facility will be able to comply with the Waste Acceptance Preliminary Specifications on the exclusion of foreign materials from the canistered waste forms, after exposure to T _g.     

几种光谱方法(FTIR、FT-Raman,NMR)在橡胶分析中的应用

综述了傅里叶变换红外光谱 ,傅里叶变换拉曼光谱以及核磁共振波谱在橡胶结构的定性、定量分析中的应用     

用固体核磁技术分析PE 100管材料的抗熔垂性

用固体核磁技术分析了2种具有不同抗熔垂性能的聚乙烯管材料的凝聚态结构与流变性能。管材树脂的抗熔垂性能与其核磁迟豫特性紧密相关,好的抗熔垂性能对应更长的纵向迟豫时间。抗熔垂性能好的双峰管材料的重均分子量更高,高相对分子质量部分的含量更多。     

Synthesis and characterization of soluble (porphyrinato)iron(II) polymers

The use of (tetrakis(4-hexylphenyl)porphyrinato)Fe(II) in polymerization reactions with bidentate ligands such as 9,10-diisocyanoanthracene and 1,4-diisocyanobenzene led to well-defined stacked polymers1 and2 which are still soluble in common organic solvents such as chloroform, dichloromethane, and tetrahydrofurane. They have been completely characterized by¹H-NMR and UV/vis spectropscopy in solution, even allowing end-group analysis for determination of the average degree of polymerization, yieldingn=10 andn=5 for1 and2, respectively. Mößbauer and IR spectroscopy further established the strong Fe-CN bonding reflected by very small isomer shifts and quadrupole splittings (E _Q0.2 mm s^–1) and a large decrease in the IR stretching frequency (v _CN60 cm^–1). The axially stacked polymers exhibit semiconducting properties only upon doping.Presented at the 5th International Symposium on Macromolecule-Metal Complexes (MMV), Summer 1993 in Bremen, Germany.     

Surface plasmon resonance evaluation of various aminoglycoside-RNA hairpin interactions reveals low degree of selectivity

Aminoglycoside antibiotics, which are able to selectively bind to RNA, are considered to be an important lead in RNA-targeting drug discovery. In this study, surface plasmon resonance (SPR) was employed to explore the interaction of aminoglycosides with known tobramycin-binding RNA hairpins (aptamers) and an unrelated RNA hairpin. It was established that aminoglycosides have multiple interactions with RNA hairpins. Unexpectedly, the different hairpins showed comparable affinity for a set of related aminoglycosides. The observed absence of selectivity presents an extra hurdle in the discovery of novel aminoglycosides as specific drugs that target defined RNA hairpins.     

Chaos in parametric resonance flow at water-mercury interface

In the electrochemical system with liquid-liquid interface, intense local convections by the resonance with potential pulses take place. Therefore, with laser beam scattering, temporal movement of the water-mercury interface was observed. As a result, the scattering efficiency showed non-linear oscillation.

Such non-linear response could be controlled by potential pulse height. As the potential height was increased, new scattering peaks in the oscillation emerged, which was expected of a kind of bifurcation phenomenon. From these results, phase portrait, Poincarè section, correlation dimension of the strange attractor and the largest Lyapunov exponent of the trajectories were obtained. Consequently, it was concluded that all the parameters indicate chaotic behavior of the resonance flow.     

Enhancement in magnetic permeability of Ni-Co-Zn ferrites using CuO doping for RF and microwave devices

Novel soft magnetic ferrite materials will play a crucial role in next-generation trillion-dollar sensor technologies related to 5G communications and internet of things as these materials can achieve improved wireless power/signal transfer efficiency with high operation frequency. In this work, Ni_0.4Co_0.25Zn_0.35Fe₂O₄ ferrites with high permeability and low magnetic loss were prepared for RF and microwave device applications. Composition and microstructure control is crucial to obtain the desired magnetic and loss properties. CuO dopant (x = 0 wt% to 20 wt%) were employed during the synthesis of Ni_0.4Co_0.25Zn_0.35Fe₂O₄ ferrite specimens to modify the microstructures, thus improving the magnetic properties of the ferrites. High value of measured relative permeability (μ’ of 4-10) and relatively low magnetic loss tangent ( of 0.01-0.1) has been achieved at frequency range between 100 and 800 MHz. Addition of CuO, especially up to 3 wt%, can cause a significant increase in permeability. Real part of the permeability of 3.87 and 10.9 has been achieved for undoped and 3 wt% CuO doped specimens, while noticeable reduction in magnetic losses has been observed for the doped sample measured at 400 MHz. The resonance frequency of synthesized ferrites has also been shifted into GHz range, when higher concentration of CuO dopants (>5 wt%) were employed.     

核电工程项目调试工期的影响因素与优化

调试启动工作是核电工程项目进度控制中非常重要的环节,对整个工程的顺利投入运行有着重要的作用。如果调试工期过长,则会导致核电工程不能按期交付使用,从而对整个核电工程的进度造成影响。主要探讨了核电工程项目调试工期的影响因素和优化措施。     

Variable temperature13C MAS NMR of KFe2Mn(CO)12 in the solid state and as aCatalyst precursor on a carbon support

Variable temperature¹³C MAS NMR spectra are reported for¹³CO-enriched KFe₂Mn(CO)₁₂ as a solid and also as dispersed clusters on a carbon support. The spectrum of KFe₂Mn(CO)₁₂ at 300 K agrees with the proposed structure for this cluster and shows that the cluster is static. Two bridging carbonyl resonances are clearly resolved and, by comparison with¹³C MAS NMR spectra of Mn₂(CO)₁₀ and Fe₂(CO)₉, all terminal resonances for the cluster can be assigned. When the cluster is supported on carbon, two broad resonances are observed at room temperature which are assignable to KFe₂Mn(CO)₁₂ and a decomposition product, Mn₂(CO)₁₀. The carbonyl ligands in both supported clusters are completely averaged, and KFe₂Mn(CO)₁₂ on the carbon surface demonstrates fluxional behavior similar to that observed for the cluster in solution. For this fluxional process, activation energies of 0.6 kcal/mol and 0.5 kcal/mol are estimated for carbon-supported KFe₂Mn(CO)₁₂ and Mn₂(CO)₁₀, respectively.     

受限波兹曼机联合稀疏近似的脑功能检测模型

人脑功能连通性检测是神经科学研究的重要技术．使用受限制波兹曼机（RestrictedBoltzmannMachine,RBM）对大量多被试功能磁共振（functionalMagneticResonanceImaging,fMRI）数据进行建模可以检测人脑功能连接,但是不能有效检测单被试数据的功能连接．本文研究一种新颖的融合了稀疏近似与RBM技术的脑功能连通性检测模型,该模型充分利用fMRI数据的稀疏性,采用稀疏近似理论对fMRI数据进行空间域稀疏近似压缩,然后使用RBM建立模型,以检测脑功能连通性．实验结果表明,该融合模型可以有效地提取单被试数据的脑功能时间域混合模型及其相应的脑功能图谱,解决了RBM在单被试数据分析上的瓶颈．