Thorium sorption onto magnetite and ferrihydrite in acidic conditions

Sorption of Th(IV) onto two-line ferrihydrite and magnetite in NaClO₄ solutions has been studied as a function of pH and ionic strength revealing that sorption onto both solids increases with pH while it is independent on ionic strength. Sorption capacity of both solids is high, the maximum sorption (almost 100% of Th(IV)) occurs at pH higher than 3.5 for ferrihydrite, and higher than 3.0 for magnetite. Sorption variation with pH was modeled with three different models using the FITEQL 4.0 code: non-electrostatic model, constant capacitance model, and diffuse-double layer model. In all cases, good fit to the experimental data is obtained with one-species: a corner-sharing bidentate-mononuclear surface complex, (FeO)₂Th²⁺, which coincides with the surface complex postulated on these solids surface in previous spectroscopic studies; however, the monodentate species FeOThOH²⁺ also gives a satisfactory fit. Under the experimental conditions of the present study, any effect of possible thorium colloid formation is negligible.     

Radiosynthesis and biodistribution of [^18F]-tetracosactide using a semi-automated [^18F]SFB production module

In order to prepare a specific melanocortin type 2 receptor (MC2R) ligand, b1-24-corticotrophin was pre-pared in one-step reaction with [18F] SFB and b-1-24-corticotrophin pharmaceutical solution (1 mg/mL, pH=6.5). [18F]SFB was prepared in a semi-automated module in two steps with an overall radiochemical yield of 47% to EOB (not-decay corrected) in 90 min. The 18F-labeled intermediates and 18F-labeled peptide was checked by RTLC and HPLC. The results show that the radiochemical purity is >95% and the yield to EOB (not-decay corrected) is 29% for final 18F-labeled peptide at optimized conditions. Preliminary in vivo studies in normal mice were performed to deter-mine biodistribution of the 18F-labeled peptide for 150 min. The results show that the major tracer uptake is consistent with the natural distribution of MC2R receptors in mammals. Testes/blood and testes/muscle ratios for 18F-labeled peptide at 150 min were 184 and 1.56, respectively, and adipocyte/blood and adipocyte/muscle ratios at 120 min were 221 and 142, respectively. The data support the specific receptor binding of the radiolabeled peptide as reported for MC2R receptor accumulation in adipocytes and testes and demonstrates the retention of biological activity of the pep-tide. This tracer can be used in detection of MC2R distribution in malignancies and sex organ diseases.     

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY STUDIES OF SEDIMENTS DERIVED FROM VISBROKEN RESIDUES: STABILITY STUDIES.

The ¹H and ¹³C n.m.r analysis of the sediments derived from visbroken short residues (150°C+) obtained at different severity levels is reported. The nature of sediments and structural changes during visbreaking and on storage at ambient conditions are related to the processing characteristics of the residual fuel oils. The possible relationship between storage stability and processing conditions is also discussed.     

Predicting the performance and NOx emissions of a turbocharged spark-ignition engine generator fueled with biogases and hydrogen addition under down-boosting condition

The characteristics of an engine generator fueled with methane-based biogas and its blend with hydrogen (H₂) were numerically investigated using a one-dimensional cycle simulation and the fractional factorial design of experiment method. Based on the experimental results, the numerical model was validated and calibrated under various excess air ratio (EAR), boost pressure, spark timing, and biogas composition conditions. The conventional and current optimization methods, maximum brake torque (MBT), and minimum input fuel (MIF) conditions, were compared in terms of engine performance, NO_x emission, and generating efficiency. Under MBT conditions, although higher torque and mass fraction burned (MFB) could be achieved, boosting degradation was evident at the optimum MBT timing. On the contrary, under MIF conditions with down-boosting, reduced NO_x formation and improved generating efficiency could be achieved, but was accompanied by an MFB decrease. Moreover, the reduced MFB could be enhanced by H₂ addition and spark-timing control. Compared to MBT, MIF optimization had advantages in terms of generating efficiency, NO_x emission reduction, and spark-timing control, and could avoid boosting degradation over the entire operating range for various fuel compositions.     

Generating Questions Based on Semi-Automated and End-to-End Neural Network

With the emergence of large-scale knowledge base, how to use triple information to generate natural questions is a key technology in question answering systems. The traditional way of generating questions require a lot of manual intervention and produce lots of noise. To solve these problems, we propose a joint model based on semi-automated model and End-to-End neural network to automatically generate questions. The semi-automated model can generate question templates and real questions combining the knowledge base and center graph. The End-to-End neural network directly sends the knowledge base and real questions to BiLSTM network. Meanwhile, the attention mechanism is utilized in the decoding layer, which makes the triples and generated questions more relevant. Finally, the experimental results on SimpleQuestions demonstrate the effectiveness of the proposed approach.     

基于MOSFET PDE模型的射频电路仿真算法研究

研究了基于 MOSFET偏微分方程 (PDE)模型的电路仿真算法 ,并提出一种求解 PDE的快速算法。当MOSFET PDE模型用于射频 (RF)电路仿真时 ,系统方程为一个耦合系统 ,包括偏微分方程 (PDE)、常微分方程(ODE)和代数方程 (AE)。采用一套迭代算法来求解该耦合系统。将上述的模型和算法用于一个压控振荡器(VCO)的瞬态特性仿真 ,模拟结果与理论分析相符。     

间接蒸发冷却技术用于纺织空调的可行性分析

间接蒸发冷却技术通过直接从自然环境中获取冷量对空气进行等湿降温,具有节能、经济、环保的优点.介绍了间接蒸发冷却的主要形式、特点及工作原理,根据纺织生产中空气调节的实际要求,结合理论,探讨了间接蒸发冷却技术在棉纺织厂细纱车间与转杯纺车间空气调节中应用的可行性,提出了具体的实施方案,并指出了应注意的问题.     

针织成品布上有机硅柔软剂的去除

有机硅柔软剂具有优良的滑爽性、柔软性和成膜性,已大量应用于高档针织布的染整生产中,但有机硅柔软剂化学性质稳定,对纤维表面的吸附能力强,特别是针织成品布上的有机硅柔软剂,用普通方法很难去除,造成针织布复染和回修困难。笔者经过多年大生产实践,有针对性地提出了解决方法。     

酸性磷铵料浆流变行为的研究（Ⅰ）

对磷铵酸性料浆的流动性及流变机理进行了研究。揭示湿法磷酸氨化过程中粘度随中和度变化的规律。当料浆含水量逐渐降低时 ,随磷铵晶体的析出 ,料浆逐渐由牛顿型流体向非牛顿型流体转变 ,剪切变稀的现象逐渐明显 ,而温度升高料浆粘度则降低。     

Origin of rate bistability in Mn–O/Al2O3 catalysts for carbon monoxide oxidation: role of the Jahn–Teller effect

Peculiarities in catalytic activity in carbon monoxide oxidation as well as some structure, electronic and magnetic properties of the three oxide catalysts, Mn³⁺–O/Al₂O₃ (1), Mn³⁺–O–Fe/Al₂O₃ (Mn-substituted spinel, 2) and -Fe₂O₃/Al₂O₃ (3), were studied by kinetic measurements and by Mössbauer spectroscopy. The catalysts 1 and 2 showed a kinetic bistability with a sharp transition towards more reactive state at 200°C (ignition point). In contrast, for catalyst 3, at 200–250°C, the behavior of reaction rate against temperature did not display noticeable hysteresis. On cooling the catalysts 1 and 2, extinction was observed at about 170 and 120°C, respectively, i.e., at 30–80°C lower than the corresponding ignition points. Proximity of activation energy for the high and low activity (15–19 kJ/mol) for both Mn-containing catalysts suggests an increase in the number of active sites at high temperature with no changes in the reaction mechanism. The considerable difference between Mn-containing catalysts 1, 2 and Fe-containing catalyst 3 may be caused by Jahn–Teller (JT) type distortions of the oxygen polyhedron around Mn³⁺. A significant spontaneous axial bond stretching within the local polyhedron seems to diminish Mn–O binding energy, facilitate the participation of surface oxygen species, O_S, in the oxidation of CO by a redox mechanism and promote oxygen vacancies at the surface that would cause considerable effect on the activity. An increase in the width of the counterclockwise hysteresis loop for the catalyst 2 compared to the catalyst 1 indicates that clusters of mixed spinel provide more active sites and more labile O_S species than clusters of the binary Mn oxide.