Recent Studies of Heterogeneous and Homogeneous Reduction–Oxidation Reactions of U(IV) Ions in Nitric Acid and TBP Phases

The results from some of our recent investigations of actinide redox reactions in nitric acid and tributyl phosphate phases are reviewed, including the oxidation of U(IV) by HNO3 and HNO2 and by Np(VI) and Np(V) in 30 % TBP and by Np(VI) in HNO3. The unusual interactions between U(IV), Tc(VII) and NH3OH+ in HNO3 are also discussed. Finally, the photocatalytic heterogeneous reduction of U(VI) by a colloidal semiconductor is presented

The electrochemistry of phenothiazine derivatives

Methylene blue derivatives (MBDs) such as methylene blue (MB -), 1-methyl methylene blue (1MMB) and 1,9-dimethyl-methylene blue (DMMB) have potential use as drugs within photodynamic therapy (PDT). Knowing the redox properties of MBDs will help in understanding the way in which MBDs interact with a range of biological systems. In this work, the electrochemical behaviour of MBDs at various solution pHs have been studied for the first time on gold microdisc electrodes using steady state and non-steady state cyclic voltammetric methods. Steady-state studies The reduction of MBDs is an ECE(CC) process where the C steps are protonation reactions. The number (m) of W participating in the overall electrode process increases from 1 to 2 or 3 with decreasing pH although the profile is different among MBDs. The half-wave potential (E 112) of each methylene blue derivative (MBD) shifts to more negative potential with increasing pH values. The E 112 of MBD at the same pH shifts to more cathodic potentials with an increasing number of -CH 3 substituent, indicating that the thermodynamic facility of MB, lMMB and DMMB reduction decreases with increasing the number of -CH3 substituents. The reduction products of MBDs depend strongly on pH, sweep rate, and sweep potential limit, as well as number of -CH 3 substituents. Non-steady state studies The redox behaviour of MBDs under non-steady-state conditions is complicated. Their common characteristics are that (i) the initial reduction of MBD is a diffusion controlled process; (ii) the onset potentials for MBD reduction shift to more negative potentials with increasing pH and number of CH 3 substituents; (iii) the facility of observation of the charge transfer complex increases with increasing pH; (vi) the charge transfer complex can be further reduced at more cathodic potentials; and (v) the amounts of charge transfer complex and leuco form depend on sweep rate and sweep potential window. They also have some differences among the electrochemical behaviour of the three drugs, such as, some anodic and cathodic processes may occur in one of MBDs, and some may not. Possible mechanisms for the electroreduction of MBDs are suggested and discussed in the light of the effect of pH and potential sweep rate on the reaction products

Coordination Control Method Suitable for Practical Engineering Applications for Distributed Power Flow Controller (DPFC)

To control multiple series units of distributed power flow controller (DPFC), a hierarchical control method is proposed. This coordination control system consists of a coordination controller and multiple series unit controllers. According to the demand of power flow ordered by a dispatch center, the corresponding series-compensated voltage is calculated by a high-level controller and transferred to each series unit controller. Comparing the targeted compensated voltage with actual injected voltage, the modulation signal of the converter will be modified to change the power flow accurately. The DPFC system model is built in Power Systems Computer Aided Design/ Electromagnetic Transients including DC (PSCAD/EMTDC). The simulation result indicates that the proposed hierarchical control method is effective and can be considered as an option for practical engineering applications in the future

D-PMU and 5G-Network-Based Coordination Control Method for Three-Phase Imbalance Mitigation Units in the LVDN

Three-phase imbalance is a long-term issue existing in low-voltage distribution networks (LVDNs), which consequently has an inverse impact on the safe and optimal operation of LVDNs. Recently, the increasing integration of single-phase distributed generations (DGs) and flexible loads has increased the probability of imbalance occurrence in LVDNs. To overcome the above challenges, this paper proposes a novel methodology based on the concept of “Active Asymmetry Energy-Absorbing (AAEA)” utilizing loads with a back-to-back converter, denoted as “AAEA Unit” in this paper. AAEA Units are deployed and coordinated to actively absorb asymmetry power among three phases for imbalance mitigation in LVDNs based on the high-precision, high-accuracy, and real-time distribution-level phasor measurement unit (D-PMU) data acquisition system and the 5th generation mobile networks (5G) communication channels. Furthermore, the control scheme of the proposed method includes three control units. Specifically, the positive-sequence control unit is designed to maintain the voltage of the DC-capacitor of the back-to-back converter. Likewise, the negative-sequence and zero-sequence control units are expected to mitigate the imbalanced current components. A simple imbalanced LVDN is modeled and tested in Simulink/Matlab (MathWorks, US). The obtained results demonstrate the effectiveness of the proposed methodology

The Micro-Optical Ring Electrode: development of a thin ring electrode for spectrophotoelectrochemistry

The Micro-Optical Ring Electrode (MORE) is a novel photoelectrochemical device based on a ring microelectrode and using the insulating material interior to the ring electrode as a light guide. Thin rings exhibit high rates of material flux to the electrode surface, facilitating the detection of short lived photogenerated solution intermediates. To exploit this advantage, we have prepared MOREs with (ring inner radius)/(ring outer radius) values in excess of 0.999. Such MOREs have been used in a study of the photoelectrochemical behaviour of (Ru(bipy)32+ ) in the presence of Fe3+ quenching agent. The spectral dependence of the MORE photocurent response has been investigated and found to correspond to the singlet-to-singlet, metal-to-ligand charge transfer band of the UV-visible spectrum of Ru(bipy)32+. A value of the Stern-Volmer constant for the quenching of photoexcited Ru(bipy)32+ by Fe3+ has been obtained using the MORE. The value obtained (1.59 m3 mol-1 ) compares favourably with the value obtained from fluorescence measurements (0.9 m3 mol-1)

The applications of photocatalytic waste minimisation in nuclear fuel processing

Nuclear fuel processing has two main waste management requirements: (1) the disposal of waste organic solvent (secondary waste) generated by solvent extraction processes during the separation and purification of uranium and plutonium in nuclear fuel and materials processing; and (2) the management of the small fractions of U and Pu that are inseparable during reprocessing (primary waste). Environmental impact associated with fuel use and reprocessing can be minimised by addressing either of these requirements.Semiconductor particles and films may act as efficient photocatalysts for a range of environmentally and industrially useful reactions including heavy metal recovery from effluent streams by manipulation of the metal valence state. The manipulation of actinide metal ion oxidation states plays an important role in nuclear fuel and materials processing. Thus, this review explores the potential use of heterogeneous photocatalysis in actinide valence state control in the context of actinide photochemistry and minimised primary and secondary waste management requirements in the plutonium-uranium reduction extraction (PUREX) nuclear fuel processing route.Criteria are defined for the selection of heterogeneous semiconductor catalysts and sacrificial charge scavengers for use within reprocessing scenarios and two main applications discussed: (1) the photocatalytic control of the neptunium ion oxidation state and consequent separation of Np from Pu and U; and (2) the photocatalytic control of U and Pu ion oxidation states and their consequent separation from each other. A quantum efficiency, phi, of 0.27 is reported for the photocatalytic reduction of the Pu(IV) simulant, Ce4+ to Ce3+ at PH 0. The high value of phi is attributed to both the forward and reverse charge transfer processes occurring via a dynamic quenching mechanism. Yields of 100% are reported for the reductions of UO22+ to U4+ and Ce4+ to Ce3+

Enhancing the thermal and mechanical properties of epoxy resins by addition of a hyperbranched aromatic polyamide grown on microcrystalline cellulose fibers

In this study, microcrystalline cellulose fibers (MCFs) derived from sisal were treated with a hyperbranched aromatic polyamide (HBAP). The modified sisal fibers were used to produce composites with epoxy resins. Firstly the MCFs were treated with a silane coupling agent, then a HBAP was grown on the modified surface. The HBAP-MCFs were used to reinforce epoxy resins. The HBAP-MCF/epoxy composites were studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and mechanical properties analysis. The results show that the HBAP-MCFs enhanced the thermal and mechanical properties of the epoxy resin. For instance, the impact strength, tensile strength, Young's modulus and toughness of the HBAP-MCF/epoxy composites with 2.0 wt% HBAP-MCFs were 32.1 kJ m(-2), 59.4 MPa, 695 MPa, and 4.37 MJ m(-3). These values represent improvements of 83.4%, 34.7%, 25%, and 178.3%, respectively, compared to a neat epoxy resin. Moreover, the addition of HBAP-MCFs produced composites with higher thermal degradation temperatures and glass transition temperatures. The HBAP-MCF swere effective in improving the thermal and mechanical properties due to a strong affinity between the fillers and the matrix

Colorectal cancer patients with low abundance of KRAS mutation may benefit from EGFR antibody therapy.

Epidermal growth factor receptor monoclonal antibody was approved for treatment of metastatic colorectal cancer patients carrying KRAS wild type DNA. However, recent studies showed that patients with KRAS G13D mutation may benefit from EGFR antibody therapy. In this study we tried to explore whether the abundance of KRAS mutation could affect the efficacy of EGFR antibody therapy. We firstly established a PNA-PCR method which could calculate the percentage of KRAS mutation in total DNA and proved its ability on 47 colorectal cancer samples bearing KRAS mutations. Then we analyzed the correlation between the abundance of KRAS mutations and efficacy of EGFR antibody therapy in another 35 metastatic colorectal cancer patients. We proved that PNA-PCR assay could calculate the abundance of KRAS mutation and the percentage of mutant DNA in tumor cells varied a lot (10.8%∼98.3%) on the 47 colorectal cancer patients. The efficacy of EGFR antibody correlated with the abundance of KRAS mutations: in the KRAS mutation less than 30% group, the disease control rate was 44.4% (4/9); the disease control rate of 30∼80% group was 5.6% (1/18) and the >80% group was 12.5% (1/8) (P = 0.038). In summary, our study showed that PNA-PCR method could easily detect the percentage of KRAS mutation in tumor cells and colorectal cancer patients with low abundance of KRAS mutation might benefit from EGFR antibody therapy

A Novel Optimization Method for a Multi-Year Planning Scheme of an Active Distribution Network in a Large Planning Zone

Electric power distribution networks plays a significant role in providing continuous electrical energy to different categories of customers. In the context of the present advancements, future load expansion in the active distribution networks (ADNs) poses the key challenge of planning to be derived as a multi-stage optimization task, including the optimal expansion planning scheme optimization (EPSO). The planning scheme optimization is a multi-attribute decision-making issue with high complexity and solving difficulty, especially when it involves a large-scale planning zone. This paper proposes a novel approach of a multi-year planning scheme for the effective solution of the EPSO problem in large planning zones. The proposed approach comprises three key parts, where the first part covers two essential aspects, i.e., (i) suggesting a project condition set that considers the elements directly related to a group of specific conditions and requirements (collectively referred to as conditions) to ADN planning projects; and (ii) Developing a condition scoring system to evaluate planning projects. The second part of our proposed scheme is a quantization method of correlativity among projects based on two new concepts: contribution index (CI) and dependence index (DI). Finally, considering the multi-year rolling optimization, a detailed mathematical model of condition evaluation and spatiotemporal optimization sequencing of ADN planning projects is developed, where the evaluation and optimization are updated annually. The proposed model has been successfully validated on a practical distribution network located in Xiantao, China. The investigated case study and comparisons verify the various advantages, suitability, and effectiveness of the proposed planning scheme, consequently saving more than 10% of the investment compared with the existing implemented scheme