A Process for Preparing High Graphene Sheet Content Carbon Materials from Biochar Materials

Graphene is monolayer graphite and has higher electron mobility than silicon, high heat conduction, and special optical properties. In this study, we have attempted to use a two-step process (an acid pretreatment followed by a heat treatment) for producing high graphene sheet content (>80%) carbon materials (GSCCMs) from monocotyledonous and dicotyledonous biochar materials prepared at 350°C. The highest graphene sheet content of 83.86% is found with the CH3COOH pretreatment followed by a 1500°C heat treatment of monocotyledonous biochar materials, and its conductivity was measured at 84.69 S/cm. Therefore, preparing GSCCMs from biochar materials could highly reduce the cost

Naked Singularities in the Einstein-Euler System

In 1990, based on numerical and formal asymptotic analysis, Ori and Piran predicted the existence of selfsimilar spacetimes, called relativistic Larson-Penston solutions, that can be suitably flattened to obtain examples of spacetimes that dynamically form naked singularities from smooth initial data, and solve the radially symmetric Einstein-Euler system. Despite its importance, a rigorous proof of the existence of such spacetimes has remained elusive, in part due to the complications associated with the analysis across the so-called sonic hypersurface. We provide a rigorous mathematical proof. Our strategy is based on a delicate study of nonlinear invariances associated with the underlying non-autonomous dynamical system to which the problem reduces after a selfsimilar reduction. Key technical ingredients are a monotonicity lemma tailored to the problem, an ad hoc shooting method developed to construct a solution connecting the sonic hypersurface to the so-called Friedmann solution, and a nonlinear argument to construct the maximal analytic extension of the solution. Finally, we reformulate the problem in double-null gauge to flatten the selfsimilar profile and thus obtain an asymptotically flat spacetime with an isolated naked singularity

Sodium Diffusion through Aluminum-Doped Zeolite BEA System: Effect of Water Solvation

To investigate the effect of hydration on the diffusion of sodium ions through the aluminum-doped zeolite BEA system (Si/Al = 30), we used the grand canonical Monte Carlo (GCMC) method to predict the water absorption into aluminosilicate zeolite structure under various conditions of vapor pressure and temperature, followed by molecular dynamics (MD) simulations to investigate how the sodium diffusion depends on the concentration of water molecules. The predicted absorption isotherm shows first-order-like transition, which is commonly observed in hydrophobic porous systems. The MD trajectories indicate that the sodium ions diffuse through zeolite porous structures via hopping mechanism, as previously discussed for similar solid electrolyte systems. These results show that above 15 wt % hydration (good solvation regime) the formation of the solvation cage dramatically increases sodium diffusion by reducing the hopping energy barrier by 25% from the value of 3.8 kcal/mol observed in the poor solvation regime

Gravitational Collapse for Polytropic Gaseous Stars: Self-similar Solutions

In the supercritical range of the polytropic indices $\gamma\in(1,\frac43)$ we show the existence of smooth radially symmetric self-similar solutions to the gravitational Euler-Poisson system. These solutions exhibit gravitational collapse in the sense that the density blows-up in finite time. Some of these solutions were numerically found by Yahil in 1983 and they can be thought of as polytropic analogues of the Larson-Penston collapsing solutions in the isothermal case $\gamma=1$. They each contain a sonic point, which leads to numerous mathematical difficulties in the existence proof.Comment: 92 page

Lithium-salt mediated synthesis of a covalent triazine framework for highly stable lithium metal batteries

A new strategy for the synthesis of a covalent triazine framework (CTF‐1) was introduced based on the cyclotrimerization reaction of 1,4‐dicyanobenzene using lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) under ionothermal conditions. LiTFSI not only served as a catalyst, but also facilitated the in situ generation and homogeneous distribution of LiF particles across the framework. The hierarchical structure resulting upon integration of CTF‐LiF onto an airlaid‐paper (AP) offered unique features for lithium metal anodes, such as lithiophilicity from CTF, interface stabilization from LiF, and sufficient lithium storage space from AP. Based on this synergistic effect, the AP‐CTF‐LiF anode exhibited stable cycling performance even at a current density of 10 mA cm−

Identification and characterization of the genetic determinants for yellow fever virus infection and dissemination in Aedes aegypti

Doctor of PhilosophyDepartment of Diagnostic Medicine/PathobiologyStephen HiggsThe genetic composition of arboviruses is a critical determinant of viral infectivity and the capacity for virus dissemination in arthropod vectors. Due to concerns related to a hypothetical potential for loss of attenuation, the supression of vector infection and dissemination is a critical component for the rationale-based design of live-attenuated flavivirus vaccine candidates. The yellow fever virus (YFV) 17D vaccine virus is not only attenuated in vertebrates, but also has low infectivity for Aedes agypti mosquitoes and since it does not disseminate, it is not transmissible. Using a reverse genetics system, the mutations present in the envelope protein YFV 17D virus were characterized in Ae. aegypti to determine the role of mutations in limiting the viral infectivity and dissemination capacity. This knowledge would contribute to the rational design of live attenuated vaccines with the desirable phenotype of being nontransmissible by arthropod vectors. The upper lateral portion of the YFV 17D envelope (E) protein domain III (EDIII) habors the T380R mutation in the FG loop. Experiments demonstrated that the T380R mutation was associated with the viral infectivity phenotype for mosquitoes, but did not influence dissemination into the secondary tissues. The G52R mutation in the molecular hinge region that is located between E protein domains I (EDI) and II, significantly reduced viral infectivity for mosquitoes. In contrast, when cloned into the Asibi wildtype virus genetic backbone, the T173I mutation in the loop structure between the G0 and H0 β- strands did not attenuate viral infection and dissemination. The double mutant virus containing both the G52R and T173I mutations in the E protein, showed a similar attenuated reduced infectivity to the single G52R mutant. The M299I mutation in the linker region between EDI and EDIII resulted in a significantly lower viral infectivity at the initial phase of viral infection at 7 days post-infection in Ae. aegypti. In conclusion, the characterization on four mutations in the YFV 17D vaccine E protein have demonstrated three genetic loci, that can influence the process of YFV infection in Ae. aegypti. These results provide new knowledge and understanding which may have broad applications for the rationale design of safe flavivirus vaccines, via targeting genetic loci and introducing specific mutations that preclude infection of, and transmission by arthropod vectors

Culex tarsalis is a competent vector species for Cache Valley virus

Background: Cache Valley virus (CVV) is a mosquito-borne orthobunyavirus endemic in North America. The virus is an important agricultural pathogen leading to abortion and embryonic lethality in ruminant species, especially sheep. The importance of CVV in human public health has recently increased because of the report of severe neurotropic diseases. However, mosquito species responsible for transmission of the virus to humans remain to be determined. In this study, vector competence of three Culex species mosquitoes of public health importance, Culex pipiens, Cx. tarsalis and Cx. quinquefasciatus, was determined in order to identify potential bridge vector species responsible for the transmission of CVV from viremic vertebrate hosts to humans. Results: Variation of susceptibility to CVV was observed among selected Culex species mosquitoes tested in this study. Per os infection resulted in the establishment of infection and dissemination in Culex tarsalis, whereas Cx. pipiens and Cx. quinquefasciatus were highly refractory to CVV. Detection of viral RNA in saliva collected from infected Cx. tarsalis provided evidence supporting its role as a competent vector. Conclusions: Our study provided further understanding of the transmission cycles of CVV and identifies Cx. tarsalis as a competent vector