Reductive C−C Coupling from α,β‐Unsaturated Nitriles by Intercepting Keteniminates

We present an atom‐economic strategy to catalytically generate and intercept nitrile anion equivalents using hydrogen transfer catalysis. Addition of α,β‐unsaturated nitriles to a pincer‐based Ru−H complex affords structurally characterized κ‐N‐coordinated keteniminates by selective 1,4‐hydride transfer. When generated in situ under catalytic hydrogenation conditions, electrophilic addition to the keteniminate was achieved using anhydrides to provide α‐cyanoacetates in high yields. This work represents a new application of hydrogen transfer catalysis using α,β‐unsaturated nitriles for reductive C−C coupling reactions.An atom‐economic strategy to catalytically generate and intercept nitrile anion equivalents by hydrogen transfer catalysis has been developed. Addition of α,β‐unsaturated nitriles to a pincer‐based Ru−H complex affords keteniminates by selective 1,4‐hydride transfer, which were employed in a net hydrogenative acylation reaction.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149503/1/anie201904530.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149503/2/anie201904530-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149503/3/anie201904530_am.pd

Physicochemical characterization of the PEG8000-Na2SO4 aqueous two-phase system

The polyethylene glycol-sodium sulfate aqueous two-phase system has been characterized at 23 °C. Tielines for the phase diagram were obtained experimentally. Phases in equilibrium were characterized by means of the solvatochromic parameters π*, α, and β, which provide a measurement of the polarity/polarizability and the H-bond donor and acceptor abilities, respectively. The ability of the phases to participate in hydrophobic interactions was characterized by means of the free energy of transfer of a methylene group between the conjugated phases, using the partition of a homologous series of dinitrophenylated amino acids. The results show the effect of the presence of polymer and salt in the aqueous phase, and a comparison of both phases with pure water is made.LSRE-PortoUniversidade Católica PortuguesaEscola Superior de Biotecnologia do PortoFundação para a Ciência e a Tecnologia (FCT

Sampling Local Fungal Diversity in an Undergraduate Laboratory using DNA Barcoding

Traditional methods for fungal species identification require diagnostic morphological characters and are often limited by the availability of fresh fruiting bodies and local identification resources. DNA barcoding offers an additional method of species identification and is rapidly developing as a critical tool in fungal taxonomy. As an exercise in an undergraduate biology course, we identified 9 specimens collected from the Hendrix College campus in Conway, Arkansas, USA to the genus or species level using morphology. We report that DNA barcoding targeting the internal transcribed spacer (ITS) region supported several of our taxonomic determinations and we were able to contribute 5 ITS sequences to GenBank that were supported by vouchered collection information. We suggest that small-scale barcoding projects are possible and that they have value for documenting fungal diversity

A combined experimental-theoretical study of the ligW-catalyzed decarboxylation of 5-carboxyvanillate in the metabolic pathway for lignin degradation

Although it is a member of the amidohydrolase superfamily, LigW catalyzes the nonoxidative decarboxylation of 5-carboxyvanillate to form vanillate in the metabolic pathway for bacterial lignin degradation. We now show that membrane inlet mass spectrometry (MIMS) can be used to measure transient CO₂ concentrations in real time, thereby permitting us to establish that C–C bond cleavage proceeds to give CO₂ rather than HCO₃^– as the initial product in the LigW-catalyzed reaction. Thus, incubation of LigW at pH 7.0 with the substrate 5-carboxyvanillate results in an initial burst of CO₂ formation that gradually decreases to an equilibrium value as CO₂ is nonenzymatically hydrated to HCO₃^–. The burst of CO₂ is completely eliminated with the simultaneous addition of substrate and excess carbonic anhydrase to the enzyme, demonstrating that CO₂ is the initial reaction product. This finding is fully consistent with the results of density functional theory calculations, which also provide support for a mechanism in which protonation of the C5 carbon takes place prior to C–C bond cleavage. The calculated barrier of 16.8 kcal/mol for the rate-limiting step, the formation of the C5-protonated intermediate, compares well with the observed <i>k</i>_cat value of 27 s^–1 for Sphingomonas paucimobilis LigW, which corresponds to an energy barrier of ∼16 kcal/mol. The MIMS-based strategy is superior to alternate methods of establishing whether CO₂ or HCO₃^– is the initial reaction product, such as the use of pH-dependent dyes to monitor very small changes in solution pH. Moreover, the MIMS-based assay is generally applicable to studies of all enzymes that produce and/or consume small-molecule, neutral gases

Undergraduate views of critical thinking

Clemson University\u27s Quality Enhanement Plan (QEP) is designed to assist undergraduates in the development of their critical thinking skills. Paul et al. (1997) found that professors indicate that they value critical thinking as important, explicit, and achieved in their students, but faculty also are vague and confusing in their open-ended descriptions of the conceptual and practical components of critical thinking instruction in the classroom. The purpose of the current study was to assess student views of the a typical professor\u27s views and student\u27s own personal views using modified versions of the survey items that Paul et al. (1997) employed. Students (n = 139) completed two eleven-item surveys; one framed a typical professor\u27s view and the other framed the student\u27s personal views of critical thinking. Students do not rate a typical professor as valuing critical thinking as important explicit and achieved in their students

Reconstructing complex regions of genomes using long-read sequencing technology

Cataloged from PDF version of article.Obtaining high-quality sequence continuity of complex regions of recent segmental duplication remains one of the major challenges of finishing genome assemblies. In the human and mouse genomes, this was achieved by targeting large-insert clones using costly and laborious capillary-based sequencing approaches. Sanger shotgun sequencing of clone inserts, however, has now been largely abandoned, leaving most of these regions unresolved in newer genome assemblies generated primarily by next-generation sequencing hybrid approaches. Here we show that it is possible to resolve regions that are complex in a genome-wide context but simple in isolation for a fraction of the time and cost of traditional methods using long-read single molecule, real-time (SMRT) sequencing and assembly technology from Pacific Biosciences (PacBio). We sequenced and assembled BAC clones corresponding to a 1.3-Mbp complex region of chromosome 17q21.31, demonstrating 99.994% identity to Sanger assemblies of the same clones. We targeted 44 differences using Illumina sequencing and find that PacBio and Sanger assemblies share a comparable number of validated variants, albeit with different sequence context biases. Finally, we targeted a poorly assembled 766-kbp duplicated region of the chimpanzee genome and resolved the structure and organization for a fraction of the cost and time of traditional finishing approaches. Our data suggest a straightforward path for upgrading genomes to a higher quality finished state

Guide to archiving personal data

Key messages in this Guide: -Data Protection law shapes archiving of personal data. It supports it and does not prevent it; -Personal data worthy of permanent preservation should be safeguarded by recordkeepers until it is archived; - The new archiving in the public interest purpose adapts the operation of various principles and maintains exemptions from data subject rights such as the right to be forgotten and data rectification where the necessary safeguards are met

Rapid and inexpensive purification of adenovirus vectors using an optimised aqueous two-phase technology.

Adenoviruses (AdVs) are used as gene therapy vectors to treat human diseases and as vaccines against COVID-19. AdVs are produced by transfecting human embryonic kidney 239 (HEK293) or PER.C6 virus producer cells with AdV plasmid vectors or infecting these cells withcell lysates containing replication-defective AdV. Cell lysates can be purified further by caesium chloride or chromatographic protocols to research virus seed stocks (RVSS) for characterisation to high quality master virus seed stocks (MVSS) and working virus seed stocks (WVSS) before downstream production of pure, high titre AdV. Lysates are poorly infectious, block filtration columns and have limited storage capability. Aqueous two-phase systems (ATPS) are an alternative method for AdV purification that rapidly generates cleaner RVSS for characterisation to MVSS. After testing multiple ATPS formulations, an aqueous mixture of 20 % PEG 600 and 20 % (NH4)2SO4 (w/w) was found most effective for AdV partitioning, producing up to 97+3% yield of high-titre virus that was devoid of aggregates both effective in vitro and in vivo with no observable cytotoxicity. Importantly, AdV preparations stored at −20 °C or 4 °C show negligible loss of titre and are suitable for downstream processing to clinical grade to support the need for AdV vaccines

Arthrocentesis versus non-surgical intervention as initial treatment for temporomandibular joint arthralgia:a randomized controlled trial with long-term follow-up

Arthrocentesis for arthralgia of the temporomandibular joint (TMJ) is often only indicated when conservative, non-surgical interventions have failed. However, performing arthrocentesis as initial therapy may facilitate earlier and better recuperation of the joint. The aim of this study was to assess the efficacy of this therapy with a long-term follow-up. Eighty-four patients were randomly allocated to receive either arthrocentesis as initial treatment (n = 41) or non-surgical intervention (n = 43). Pain (100-mm visual analogue scale, VAS) and mandibular function impairment questionnaire scores (MFIQ, 0–100) were recorded at 3, 12, and 26 weeks, and ≥ 5 years (median 6.2, interquartile range 5.6–7.4 years). Univariable analyses were performed and linear mixed-effect models were constructed. Patients in the arthrocentesis group experienced significantly lower TMJ arthralgia compared to those treated non-surgically (pain during movement: −10.23 mm (95% confidence interval −17.86; −2.60); pain at rest: − 8.39 mm (95% confidence interval −13.70; −3.08)), while mandibular function remained similar in the two groups (MFIQ −2.41 (95% confidence interval −8.61; 3.78)). Of the final sample, 10 patients (10/39, 26%) in the non-surgical intervention group and two patients (2/34, 6%) in the arthrocentesis group received additional treatment during follow-up. Thus, initial treatment with arthrocentesis reduced TMJ arthralgia more efficaciously than non-surgical intervention in the long term, while maintaining similar mandibular function