Search results for "Open"
showing 10 items of 3963 documents
The challenge of the predatory open-access publishing outbreak
2019
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An Infrequent Case of Fire in the Operating Room During Open Surgery of a Tracheobronchopleural Fistula
2005
Malocclusion characteristics amongst individuals with autism spectrum disorder: a systematic review and meta‑analysis
2022
Abstract Background To estimate the prevalence of malocclusion in individuals with autism spectrum disorders (ASD) and to assess the relationship between ASD and malocclusion. Methods We searched electronic databases including PubMed, Scopus, Web of Science, Cochrane, Embase, SciELO LILACS, Proquest, OpenGrey and Google Scholar. There were no language or publication dates restrictions. Two researchers independently performed selection, data extraction and quality assessment. Quality assessment and risk of bias were evaluated through the Newcastle–Ottawa scale and ROBINS-E tool. Meta-analyses using random effect models were used to estimate pooled measures of prevalence of malocclusion chara…
Quantum state engineering using one-dimensional discrete-time quantum walks
2017
Quantum state preparation in high-dimensional systems is an essential requirement for many quantum-technology applications. The engineering of an arbitrary quantum state is, however, typically strongly dependent on the experimental platform chosen for implementation, and a general framework is still missing. Here we show that coined quantum walks on a line, which represent a framework general enough to encompass a variety of different platforms, can be used for quantum state engineering of arbitrary superpositions of the walker's sites. We achieve this goal by identifying a set of conditions that fully characterize the reachable states in the space comprising walker and coin, and providing …
Scope and Limitations of Baird's Theory on Triplet State Aromaticity: Application to the Tuning of Singlet–Triplet Energy Gaps in Fulvenes
2007
Utilizing Baird's theory on triplet state aromaticity, we show that the singlet-triplet energy gaps (DeltaE(ST)) of pentafulvenes are easily varied through substitution by as much as 36 kcal mol(-1). This exploits the fact that fulvenes act as aromatic chameleons in which the dipoles reverse on going from the singlet ground state (S(0)) to the lowest pipi* triplet state (T1); thus, their electron distributions are adapted so as to achieve some aromaticity in both states. The results are based on quantum chemical calculations with the OLYP density functional theory method and the CASPT2 ab initio method, as well as spectroscopic determination of DeltaE(ST) by triplet sensitization. The findi…
Some New Copolymers by Ionic Polymerization
1980
In the first part the cationic polymerization of a homologous series of cyclic ether–acetals with ring sizes of 11, 14, and 17 atoms is described. During the polymerization of triethylene glycol formal (TGF) an equilibrium is reached and besides high polymers cyclic oligomers are formed. The oligomers and the polymers are built up of a regular sequence of one oxymethylene unit and three oxyethylene units –[–(OCH2) (OC2H4)3–]–x. They are therefore be labelled a “sequenced copolymer.” The equilibrium concentrations of the cyclic oligomers with a polymerization degree from 2 to 15 follow the Jacobson–Stockmayer equation. The 14- and 17-membered monomers POC and HOC forms cyclic oligomers and h…
Theoretical Study on the Photo-Oxidation and Photoreduction of an Azetidine Derivative as a Model of DNA Repair
2021
Photocycloreversion plays a central role in the study of the repair of DNA lesions, reverting them into the original pyrimidine nucleobases. Particularly, among the proposed mechanisms for the repair of DNA (6-4) photoproducts by photolyases, it has been suggested that it takes place through an intermediate characterized by a four-membered heterocyclic oxetane or azetidine ring, whose opening requires the reduction of the fused nucleobases. The specific role of this electron transfer step and its impact on the ring opening energetics remain to be understood. These processes are studied herein by means of quantum-chemical calculations on the two azetidine stereoisomers obtained from photocyc…
Experimental and Theoretical Studies of Nonclassical d 0 Cyclopentadienyl Polyhydride Complexes of Molybdenum and Tungsten
1998
Low-temperature protonation of compounds Cp{sup *}MH{sub 5}(PMe{sub 3}) (M = Mo, 1; W, 2) by HBF{sub 4}{center_dot}Et{sub 2}O in CD{sub 2}Cl{sub 2} or CDFCl{sub 2} affords the thermally unstable hexahydride derivatives [Cp{sup *}MH{sub 6}(PMe{sub 3})]{sup +} (M = Mo, 3; W, 4). The corresponding protonation of 1- and 2-d{sup 5} affords 3- and 4-d{sup 5}, respectively. The {Delta}{delta} on going from H{sub 6} to HD{sub 5} is small for both compounds, but positive for 3 and negative for 4, and no isotopic perturbation of resonance (IPR) is observed. The T{sub 1min} at 400 MHz for [Cp{sup *}MH{sub 6}(PMe{sub 3})]{sup +} apparently doubles on going from Mo to W (52 ms for 3 and approximately 10…
Untargeted Antifungal Treatment Strategies for Invasive Candidiasis in Non-neutropenic Critically Ill Patients: Current Evidence and Insights
2017
Purpose of Review: The purpose of this study was to provide an overview and insights on important new concepts on untargeted antifungal treatment strategies, namely prophylaxis pre-emptive and empiric treatments for the management of invasive candidiasis (IC) in non-neutropenic critically ill patients. Recent Findings: Recently, clinical practice guidelines provided recommendation for the management of IC. However, results from recent trials and systematic reviews questioned the effect of untargeted antifungal treatment strategies, especially in terms of survival benefits in non-neutropenic patients, even with septic shock. Summary: Widespread use of untargeted antifungal treatment strategi…
2014
Viral CD8 T-cell epitopes, represented by viral peptides bound to major histocompatibility complex class-I (MHC-I) glycoproteins, are often identified by “reverse immunology”, a strategy not requiring biochemical and structural knowledge of the actual viral protein from which they are derived by antigen processing. Instead, bioinformatic algorithms predicting the probability of C-terminal cleavage in the proteasome, as well as binding affinity to the presenting MHC-I molecules, are applied to amino acid sequences deduced from predicted open reading frames (ORFs) based on the genomic sequence. If the protein corresponding to an antigenic ORF is known, it is usually inferred that the kinetic …