Assessment of Perturbative Explicitly Correlated Methods for Prototypes of Multiconfiguration Electronic Structure

The performance of the [2]S and [2]R12 universal perturbative corrections that account for one- and many-body basis set errors of single- and multiconfiguration electronic structure methods is assessed. A new formulation of the [2]R12 methods is used in which only strongly occupied orbitals are correlated, making the approach more amenable for larger computations. Three model problems are considered using the aug-cc-pVXZ (X = D,T,Q) basis sets: the electron affinity of fluorine atom, a conformational analysis of two Si2H4structures, and a description of the potential energy surfaces of the X 1Σg+, a 3Πu, b 3Σg-, and A1Πu states of C2. In general, the [2]R12 and [2]S corrections enhance energy convergence for conventional multireference configuration interaction (MRCI) and multireference perturbation theory (MRMP2) calculations compared to their complete basis set limits. For the electron affinity of the F atom, [2]R12 electron affinities are within 0.001 eV of the experimental value. The [2]R12 conformer relative energy error for Si2H4 is less than 0.1 kcal/mol compared to the complete basis set limit. The C2 potential energy surfaces show nonparallelity errors that are within 0.7 kcal/mol compared to the complete basis set limit. The perturbative nature of the [2]R12 and [2]S methods facilitates the development of a straightforward text-based data exchange standard that connects an electronic structure code that can produce a two-particle density matrix with a code that computes the corrections. This data exchange standard was used to implement the interface between the GAMESS MRCI and MRMP2 codes and the MPQC [2]R12 and [2]S capabilities

The Change of Teleost Skin Commensal Microbiota Is Associated With Skin Mucosal Transcriptomic Responses During Parasitic Infection by Ichthyophthirius multifillis

Teleost skin serves as the first line of defense against invading pathogens, and contain a skin-associated lymphoid tissue (SALT) that elicit gut-like immune responses against antigen stimulation. Moreover, exposed to the water environment and the pathogens therein, teleost skin is also known to be colonized by diverse microbial communities. However, little is known about the interactions between microbiota and the teleost skin mucosal immune system, especially dynamic changes about the interactions under pathogen infection. We hypothesized that dramatic changes of microbial communities and strong mucosal immune response would be present in the skin of aquatic vertebrate under parasite infection. To confirm this hypothesis, we construct an infected model with rainbow trout (Oncorhynchus mykiss), which was experimentally challenged by Ichthyophthirius multifiliis (Ich). H & E staining of trout skin indicates the successful invasion of Ich and shows the morphological changes caused by Ich infection. Critically, increased mRNA expression levels of immune-related genes were detected in trout skin from experimental groups using qRT-PCR, which were further studied by RNA-Seq analysis. Here, through transcriptomics, we detected that complement factors, pro-inflammatory cytokines, and antimicrobial genes were strikingly induced in the skin of infected fish. Moreover, high alpha diversity values of microbiota in trout skin from the experimental groups were discovered. Interestingly, we found that Ich infection led to a decreased abundance of skin commensals and increased colonization of opportunistic bacteria through 16S rRNA pyrosequencing, which were mainly characterized by lose of Proteobacteria and increased intensity of Flavobacteriaceae. To our knowledge, our results suggest for the first time that parasitic infection could inhibit symbionts and offer opportunities for other pathogens' secondary infection in teleost skin

Electromagnetic Wave Theory and Applications

Contains table of contents for Section 3, reports on nine research projects and a list of publications.National Aeronautics and Space Administration Contract 958461U.S. Navy - Office of Naval Research Grant N00014-92-J-1616University of California/Jet Propulsion Laboratory Contract 960408U.S. Army - Corps of Engineers/Cold Regions Research and Engineering Laboratory Contract DACA89-95-K-0014Mitsubishi CorporationU.S. Navy - Office of Naval Research Agreement N00014-92-J-4098Federal Aviation AdministrationDEMACOJoint Services Electronics Program Grant DAAHO4-95-1-003

Electromagnetic Wave Theory and Applications

Contains table of contents for Section 3, reports on ten research projects and a list of publications.National Aeronautics and Space Administration Contract 958461U.S. Navy - Office of Naval Research Grant N00014-92-J-1616U.S. Navy - Office of Naval Research Grant N00014-89-J-1019U.S. Navy - Office of Naval Research Grant N00014-90-J-1002U.S. Army Cold Regions Research and Engineering Laboratory Contract PACA89-95-K-0014Mitsubishi Corporation Agreement Dated 8/31/95U.S. Navy - Office of Naval Research Grant N00014-92-J-4098U.S. Federal Aviation Administration Grant 94-G-007DEMACO Corporation Contract DEM-95-MIT-55Joint Services Electronics Program Contract DAAH04-95-1-003

An algebraic proof of generalized Wick theorem

The multireference normal order theory, introduced by Kutzelnigg and Mukherjee [J. Chem. Phys. 107, 432 (1997)] , is defined explicitly, and an algebraic proof is given for the corresponding contraction rules for a product of any two normal ordered operators. The proof does not require that the contractions be cumulants, so it is less restricted. In addition, it follows from the proof that the normal order theory and corresponding contraction rules hold equally well if the contractions are only defined up to a certain level. These relaxations enable us to extend the original normal order theory. As a particular example, a quasi-normal-order theory is developed, in which only one-body contractions are present. These contractions are based on the one-particle reduced density matrix

Preparation of low-oxygen titanium powder by magnesiothermic reduction of TiO2 in KCl–MgCl2–YCl3 molten salt

The Kroll process is currently the only effective method in industry to produce sponge titanium with a low-oxygen concentration (500 ppm). However, it has several limitations, such as a long processing time, low efficiency, and high energy consumption, resulting in the high production cost of titanium. To reduce the production cost, a method to prepare low-oxygen titanium powder by magnesiothermic reduction of TiO2 in KCl–MgCl2–YCl3 molten salt was designed. The thermodynamic calculation results showed that it was feasible to prepare titanium powder by the magnesiothermic reduction of TiO2 at 1073, 1173, and 1273 K. In addition, the deoxidation limits of Mg under Mg/MgCl2/YCl3/YOCl equilibrium were 3, 12, and 38 ppm at 1073, 1173, and 1273 K, respectively. The experimental results showed that titanium powder with a high oxygen concentration of approximately 10,000 ppm was obtained when the reduction was conducted in KCl–MgCl2 molten salt (i.e., the activity of YCl3 (aYCl3) was 0). Low-oxygen titanium powder was prepared with the addition of YCl3 in the molten salt and formed yttrium oxychloride (YOCl) (TiO2 (s) + 2Mg (l) + 2YCl3 (l) = Ti (s) + 2MgCl2 (l) + 2YOCl (s)). Moreover, at 1173 K, when the activity of YCl3 (aYCl3) was 1, titanium powder with an oxygen concentration as low as 150 ppm was obtained. Based on these results, a novel process for preparing low-oxygen titanium powder was designed. The proposed process is fast and highly efficient, and its future application in industry is anticipated

Assessment of Perturbative Explicitly Correlated Methods for Prototypes of Multiconfiguration Electronic Structure

The performance of the [2]S and [2]R12 universal perturbative corrections that account for one- and many-body basis set errors of single- and multiconfiguration electronic structure methods is assessed. A new formulation of the [2]R12 methods is used in which only strongly occupied orbitals are correlated, making the approach more amenable for larger computations. Three model problems are considered using the aug-cc-pVXZ (X = D,T,Q) basis sets: the electron affinity of fluorine atom, a conformational analysis of two Si2H4structures, and a description of the potential energy surfaces of the X 1Σg+, a 3Πu, b 3Σg-, and A1Πu states of C2. In general, the [2]R12 and [2]S corrections enhance energy convergence for conventional multireference configuration interaction (MRCI) and multireference perturbation theory (MRMP2) calculations compared to their complete basis set limits. For the electron affinity of the F atom, [2]R12 electron affinities are within 0.001 eV of the experimental value. The [2]R12 conformer relative energy error for Si2H4 is less than 0.1 kcal/mol compared to the complete basis set limit. The C2 potential energy surfaces show nonparallelity errors that are within 0.7 kcal/mol compared to the complete basis set limit. The perturbative nature of the [2]R12 and [2]S methods facilitates the development of a straightforward text-based data exchange standard that connects an electronic structure code that can produce a two-particle density matrix with a code that computes the corrections. This data exchange standard was used to implement the interface between the GAMESS MRCI and MRMP2 codes and the MPQC [2]R12 and [2]S capabilities.Reprinted (adapted) with permission from Journal of Chemical Theory and Computation 10 (2014): 90, doi:10.1021/ct4006773. Copyright 2014 American Chemical Society.</p