Mathematical Modeling Using Sturm-Liouville System of Differential Equations to Physical Problems

A few exactly solvable electrical conductivities useful in electromagnetic induction studies for Maxwell equations without displacement current have been evaluated by using Sturm-Liouville system of differential equations of the second order. A few solvable conductivities for the well-known Bessel, Stokes equations have also been presented Keywords: Bessel, Stokes, Maxwell, equations, conductivities, magnetotellurics, electric field, magnetic field, induction

Balance Instability And Vibration On A 6 Mw Induction Motor Rotor

Case Studypg. 338-35

Full Speed String Test On LM6000PF Gas Turbine Driven Refrigeration Compressors

LectureChevron Australia, as part of the Wheatstone Project, constructed a two train liquefied natural gas (LNG) facility and domestic gas plant at the Ashburton North Strategic Industrial Area, 12 kilometers west of Onslow on the Pilbara coast of Western Australia. A driver selection study was performed based on the ConocoPhillips Optimized Cascade® natural gas liquefaction process. Details of this driver selection study are covered by Shah et al [1]. This driver study evaluated a variety of project-specific parameters and resulted in the selection of a General Electric LM6000 PF aeroderivative gas turbine. The final decision to use the LM6000 engine was based on a detailed technology qualification program. Following the completion of the technology qualification, a detailed risk mitigation plan was developed. The plan was incorporated into the purchase order of the equipment and, subsequently, incorporated into the equipment manufacturer’s Failure Mode Effects Analysis (FMEA) process. The risk mitigation plan highlighted extensive testing requirements during the full-load, full-speed (FLFS) string test. This paper covers the details of the FLFS testing that was performed in the fourth quarter of 2013

IHMCIF: An Extension of the PDBx/mmCIF Data Standard for Integrative Structure Determination Methods

IHMCIF (github.com/ihmwg/IHMCIF) is a data information framework that supports archiving and disseminating macromolecular structures determined by integrative or hybrid modeling (IHM), and making them Findable, Accessible, Interoperable, and Reusable (FAIR). IHMCIF is an extension of the Protein Data Bank Exchange/macromolecular Crystallographic Information Framework (PDBx/mmCIF) that serves as the framework for the Protein Data Bank (PDB) to archive experimentally determined atomic structures of biological macromolecules and their complexes with one another and small molecule ligands (e.g., enzyme cofactors and drugs). IHMCIF serves as the foundational data standard for the PDB-Dev prototype system, developed for archiving and disseminating integrative structures. It utilizes a flexible data representation to describe integrative structures that span multiple spatiotemporal scales and structural states with definitions for restraints from a variety of experimental methods contributing to integrative structural biology. The IHMCIF extension was created with the benefit of considerable community input and recommendations gathered by the Worldwide Protein Data Bank (wwPDB) Task Force for Integrative or Hybrid Methods (wwpdb.org/task/hybrid). Herein, we describe the development of IHMCIF to support evolving methodologies and ongoing advancements in integrative structural biology. Ultimately, IHMCIF will facilitate the unification of PDB-Dev data and tools with the PDB archive so that integrative structures can be archived and disseminated through PDB

PDBe: improved accessibility of macromolecular structure data from PDB and EMDB

© 2015 The Authors. Published by OUP. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1093/nar/gkv1047The Protein Data Bank in Europe (http://pdbe.org) accepts and annotates depositions of macromolecular structure data in the PDB and EMDB archives and enriches, integrates and disseminates structural information in a variety of ways. The PDBe website has been redesigned based on an analysis of user requirements, and now offers intuitive access to improved and value-added macromolecular structure information. Unique value-added information includes lists of reviews and research articles that cite or mention PDB entries as well as access to figures and legends from full-text open-access publications that describe PDB entries. A powerful new query system not only shows all the PDB entries that match a given query, but also shows the 'best structures' for a given macromolecule, ligand complex or sequence family using data-quality information from the wwPDB validation reports. A PDBe RESTful API has been developed to provide unified access to macromolecular structure data available in the PDB and EMDB archives as well as value-added annotations, e.g. regarding structure quality and up-to-date cross-reference information from the SIFTS resource. Taken together, these new developments facilitate unified access to macromolecular structure data in an intuitive way for non-expert users and support expert users in analysing macromolecular structure data.The Wellcome Trust [88944, 104948]; UK Biotechnology and Biological Sciences Research Council [BB/J007471/1, BB/K016970/1, BB/M013146/1, BB/M011674/1]; National Institutes of Health [GM079429]; UK Medical Research Council [MR/L007835/1]; European Union [284209]; CCP4; European Molecular Biology Laboratory (EMBL). Funding for open access charge: The Wellcome Trust.Published versio

Outcome of the First wwPDB Hybrid / Integrative Methods Task Force Workshop

Structures of biomolecular systems are increasingly computed by integrative modeling that relies on varied types of experimental data and theoretical information. We describe here the proceedings and conclusions from the first wwPDB Hybrid/Integrative Methods Task Force Workshop held at the European Bioinformatics Institute in Hinxton, UK, on October 6 and 7, 2014. At the workshop, experts in various experimental fields of structural biology, experts in integrative modeling and visualization, and experts in data archiving addressed a series of questions central to the future of structural biology. How should integrative models be represented? How should the data and integrative models be validated? What data should be archived? How should the data and models be archived? What information should accompany the publication of integrative models

Community recommendations on cryoEM data archiving and validation

In January 2020, a workshop was held at EMBL-EBI (Hinxton, UK) to discuss data requirements for the deposition and validation of cryoEM structures, with a focus on single-particle analysis. The meeting was attended by 47 experts in data processing, model building and refinement, validation, and archiving of such structures. This report describes the workshop’s motivation and history, the topics discussed, and the resulting consensus recommendations. Some challenges for future methods-development efforts in this area are also highlighted, as is the implementation to date of some of the recommendations.The workshop was supported by funding to PDBe and EMDB by the Wellcome Trust (grant No. 104948/Z/14/Z awarded to GJK, SV and AP) and by the European Molecular Biology Laboratory. Travel was supported by the PDBe, EMDB, RCSB PDB, PDBj, BMRB and EMDR. RCSB PDB is jointly funded by the National Science Foundation (grant No. DBI1832184); the US Department of Energy (grant No. DESC0019749); and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health (grant No. R01GM133198). PDBj is funded by JST-NBDC and BMRB by the National Institute of General Medical Sciences (NIGMS) of the National Institutes of Health (NIH) (grant No. R24GM150793). EMDR was funded by the NIGMS of the NIH (grant No. R01GM079429).Peer reviewe

Theoretical Investigation of Charge Transfer in Metal Organic Frameworks for Electrochemical Device Applications

For electrochemical device applications metal organic frameworks (MOFs) must exhibit suitable conduction properties. To this end, we have performed computational studies of intermolecular charge transfer in MOFs consisting of hexa-Zr^IV nodes and tetratopic carboxylate linkers. This includes an examination of the electronic structure of linkers that are derived from tetraphenyl benzene <b>1</b>, tetraphenyl pyrene <b>2</b>, and tetraphenyl porphyrin <b>3</b> molecules. These results are used to determine charge transfer propensities in MOFs, within the framework of Marcus theory, including an analysis of the key parameters (charge transfer integral <i>t</i>, reorganization energy λ, and free energy change Δ<i>G</i>⁰) and evaluation of figures of merit for charge transfer based on the chemical structures of the linkers. This qualitative analysis indicates that delocalization of the HOMO/LUMO on terminal substituents increases <i>t</i> and decreases λ, while weaker binding to counterions decreases Δ<i>G</i>⁰, leading to better charge transfer propensity. Subsequently, we study hole transfer in the linker <b>2</b> containing MOFs, <b>NU-901</b> and <b>NU-1000</b>, in detail and describe mechanisms (hopping and superexchange) that may be operative under different electrochemical conditions. Comparisons with experiment are provided where available. On the basis of the redox and catalytic activity of nodes and linkers, we propose three possible schemes for constructing electrochemical devices for catalysis. We believe that the results of this study will lay the foundation for future experimental work on this topic

The effect of the magnitude and direction of the dipoles of organic cations on the electronic structure of hybrid halide perovskites

We present ab initio calculations (DFT and SOC-G0W0) of the optoelectronic properties of different hybrid-halide perovskites, namely X-PbI3 (X = methylamonimum, formamidinium, guanidinium, hydrazinium, and hydroxylammonium). These calculations shed new light on how the substitution of different organic cations in the material influences its optoelectronic properties. Our simulations show a significant modification of the lattice parameter and band gap of the material upon cation substitution. These modifications are not only due to steric effects but also due to electrostatic interactions between the organic and inorganic parts of the material. In addition to this, we demonstrate how the relative orientations of neighboring cations in the material modify the local electrostatic potential of the system and its fundamental band gap. This change in the band gap is accompanied by the formation of localized and spatially separated electronic states. These localized states modify the carrier mobility in the materials and can be a reason for the formation and recombination of the charge carriers in these very promising materials.</p

Theoretical investigation of intramolecular magnetic interaction through an ethylenic coupler

We show that an ethylenic coupler provides a very strong intramolecular magnetic interaction. A recently synthesized nitronyl nitroxide derivative, D-NIT2, is investigated by ab initio quantum chemical methods. The broken symmetry approach yields a coupling constant -541 K that is in good agreement with the observed value in solid state. © 2005 American Chemical Society