The U.S.-Russia Joint Threat Assessment of Nuclear Terrorism

Nuclear terrorism is a real and urgent threat. Given the potentially catastrophic consequences, even a small probability of terrorists getting and detonating a nuclear bomb is enough to justify urgent action to reduce the risk. Al-Qaeda and North Caucasus terrorist groups have both made statements indicating that they seek nuclear weapons and have attempted to acquire them; these groups are presented together as a case study to assess nuclear terrorism as a present and future threat. (The only other terrorist group known to have systematically sought to get nuclear weapons was the Japanese cult group Aum Shinrikyo.) This study makes the case that it is plausible that a technically sophisticated group could make, deliver, and detonate a crude nuclear bomb if it could obtain sufficient fissile material. The study offers recommendations for actions to reduce this danger

Comparative analysis of DFT-vdW vs. Coulomb energies for configurational space of layered cathode material at different delithiation levels

Doping and intercalation ion disordering complicate drastically computer modeling of cathode material properties and behavior during charge-discharge processes. For layered cathode material, parameters of the energetically favored entries of compositional/configurational spaces (CCS) are known to correlate well with the CCS mean values. For the CCS (20760 configurations) of commercially used Li1-xNi0.8Co0.15Al0.05O2, a comparative analysis of electrostatic energies and those obtained using first-principles calculations was performed. Based on the Coulomb energy values, the CCS subgroups containing energetically favorable configurations (ca. 25% of the total number of CCS entries) can be identified reliably for Li deficiencies x ≤ 0.5. Further delithiation results in discrepancies between the title methods demonstrating a limited applicability of the simplified selection procedure. The most apparent reason for this is dispersion interaction which can significantly influence structure behavior and shift energetic properties of the layered cathode materials at high lithium deintercalation levels

Frequency-Response Coupling between Synchronous Areas in Europe

This paper investigates different control implementations for the frequency-response coupling between synchronous areas that feature a decentralized load-frequency control structure. The technical basics are presented, along with a 2-area benchmark system implemented in SIMULINK. Two new concepts are applied: Frequency-response delivery and frequency netting. The results show that both concepts are robust and stable. But as the frequency-response coupling affects the frequency performance in both the connecting and receiving synchronous area, the control scheme determines the overall system reliability. There are two reasonable options for the unilateral frequency-response delivery; the choice depends on the difference in the frequency restoration design between the synchronous areas. For frequency netting, only one scheme is applicable

Comparative analysis of DFT-vdW

Doping and intercalation ion disordering complicate drastically computer modeling of cathode material properties and behavior during charge-discharge processes. For layered cathode material, parameters of the energetically favored entries of compositional/configurational spaces (CCS) are known to correlate well with the CCS mean values. For the CCS (20760 configurations) of commercially used Li1-xNi0.8Co0.15Al0.05O2, a comparative analysis of electrostatic energies and those obtained using first-principles calculations was performed. Based on the Coulomb energy values, the CCS subgroups containing energetically favorable configurations (ca. 25% of the total number of CCS entries) can be identified reliably for Li deficiencies x ≤ 0.5. Further delithiation results in discrepancies between the title methods demonstrating a limited applicability of the simplified selection procedure. The most apparent reason for this is dispersion interaction which can significantly influence structure behavior and shift energetic properties of the layered cathode materials at high lithium deintercalation levels

Topology-based description of the NCA cathode configurational space and an approach of its effective reduction

Modification of existing solid electrolyte and cathode materialsis a topic of interest for theoreticians and experimentalists. In particular, itrequires elucidation of the influence of dopants on the characteristics of thestudying materials. For the reason of high complexity of theconfigurational space of doped/deintercalated systems, application of thecomputer modeling approaches is hindered, despite significant advances ofcomputational facilities in last decades. In this study, we propose a scheme,which allows to reduce a set of structures of a modeled configurationalspace for the subsequent study by means of the time-consuming quantumchemistry methods. Application of the proposed approach is exemplifiedthrough the study of the configurational space of the commercialLiNi0.8Co0.15Al0.05O2 (NCA) cathode material approximant

Topology-based description of the NCA cathode configurational space and an approach of its effective reduction

Modification of existing solid electrolyte and cathode materialsis a topic of interest for theoreticians and experimentalists. In particular, itrequires elucidation of the influence of dopants on the characteristics of thestudying materials. For the reason of high complexity of theconfigurational space of doped/deintercalated systems, application of thecomputer modeling approaches is hindered, despite significant advances ofcomputational facilities in last decades. In this study, we propose a scheme,which allows to reduce a set of structures of a modeled configurationalspace for the subsequent study by means of the time-consuming quantumchemistry methods. Application of the proposed approach is exemplifiedthrough the study of the configurational space of the commercialLiNi0.8Co0.15Al0.05O2 (NCA) cathode material approximant

Delithiated states of layered cathode materials: doping and dispersion interaction effects on the structure

Here we present results of density functional theory (DFT) study of delithiated structures of layered LiNiO2 (LNO, Li12Ni12O24 model) cathode material and its doped analogue LiNi0.833Co0.083Al0.083O2 (N10C1A1, Li12Ni10CoAlO24 model). The paper is aimed at independent elucidation of doping and dispersion interaction effects on the structural stability of cathode materials studied. For this purpose, the LNO and N10C1A1 configurational spaces consisting of 87 and 4512 crystallographically independent configurations (obtained starting from 2×2×1 supercell of R-3m structure of LNO) are optimized within a number of DFT models. Based on a comparison of the calculated dependencies for the lattice parameters with the results of in situ neutron diffraction experiments, the most pronounced effect of cathode material stabilization is due to the dispersion interaction. In turn, the doping effect is found to affect cathode structure behavior at the latest stages of delithiation only

Removal of extra sequences with I-SceI in combination with CRISPR/Cas9 technique for precise gene editing in Drosophila

The CRISPR/Cas9 system has recently emerged as a powerful tool for functional genomic studies and has been adopted for many organisms, including Drosophila. Previously, an efficient two-step strategy was developed to engineer the fly genome by combining CRISPR/Cas9 with recombinase-mediated cassette exchange (RMCE). This strategy allows the introduction of designed mutations into a gene of interest in vivo. However, the loxP or frt site remains in the edited locus. Here, we propose a modification of this approach for rapid and efficient seamless genome editing with CRISPR/Cas9 and site-specific recombinase-mediated integration (SSRMI) combined with recombination between homologous sequences induced by the rare-cutting endonuclease I-SceI. The induced homological recombination leads to the removal of the remaining extraneous sequences from the target locus

Delithiated states of layered cathode materials: doping and dispersion interaction effects on the structure

Here we present results of density functional theory (DFT) study of delithiated structures of layered LiNiO2 (LNO, Li12Ni12O24 model) cathode material and its doped analogue LiNi0.833Co0.083Al0.083O2 (N10C1A1, Li12Ni10CoAlO24 model). The paper is aimed at independent elucidation of doping and dispersion interaction effects on the structural stability of cathode materials studied. For this purpose, the LNO and N10C1A1 configurational spaces consisting of 87 and 4512 crystallographically independent configurations (obtained starting from 2×2×1 supercell of R-3m structure of LNO) are optimized within a number of DFT models. Based on a comparison of the calculated dependencies for the lattice parameters with the results of in situ neutron diffraction experiments, the most pronounced effect of cathode material stabilization is due to the dispersion interaction. In turn, the doping effect is found to affect cathode structure behavior at the latest stages of delithiation only