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https://www.readbyqxmd.com/read/29235721/the-ideal-ionic-liquid-salt-bridge-for-the-direct-determination-of-gibbs-energies-of-transfer-of-single-ions-part-ii-evaluation-of-the-role-of-ion-solvation-and-ion-mobilities
#1
Andreas Ermantraut, Valentin Radtke, Niklas Gebel, Daniel Himmel, Thorsten Koslowski, Ivo Leito, Ingo Krossing
An important intermediate goal to evaluate our concept for the assumption-free determination of single ion Gibbs transfer energies ΔtrG°(i, S1 > S2) is presented: We executed the crucial steps a) and b) of the methodology, described in Part I of this treatise, exemplarily for Ag+ and Cl- with S1 being water and S2 being acetonitrile. The experiments showed that virtually all parts of the liquid junction potentials (LJPs) at both ends of a salt bridge cancel, if the bridge electrolyte is an "ideal" ionic liquid - one with nearly identical diffusion of anion and cation...
December 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29235713/the-ideal-ionic-liquid-salt-bridge-for-the-direct-determination-of-gibbs-energies-of-transfer-of-single-ions-part-i-the-concept
#2
Valentin Radtke, Andreas Ermantraut, Daniel Himmel, Thorsten Koslowski, Ivo Leito, Ingo Krossing
We describe a procedure for the thermodynamically rigorous, experimental determination of the Gibbs Energy of Transfer of single ions between solvents. The method is based on potential difference measurements between two electrochemical half cells with different solvents connected by an ideal Ionic Liquid Salt Bridge (ILSB). We discuss the specific requirements for the IL with regard to the procedure, ensuring that the Liquid Junction Potentials (LJP) at both ends of the ILSB cancel largely. The remaining parts of the LJPs can be determined by separate emf measurements...
December 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29229855/distinct-roles-of-n-and-o-glycans-in-cellulase-activity-and-stability
#3
Antonella Amore, Brandon C Knott, Nitin T Supekar, Asif Shajahan, Parastoo Azadi, Peng Zhao, Lance Wells, Jeffrey G Linger, Sarah E Hobdey, Todd A Vander Wall, Todd Shollenberger, John M Yarbrough, Zhongping Tan, Michael F Crowley, Michael E Himmel, Stephen R Decker, Gregg T Beckham, Larry E Taylor
In nature, many microbes secrete mixtures of glycoside hydrolases, oxidoreductases, and accessory enzymes to deconstruct polysaccharides and lignin in plants. These enzymes are often decorated with N- and O-glycosylation, the roles of which have been broadly attributed to protection from proteolysis, as the extracellular milieu is an aggressive environment. Glycosylation has been shown to sometimes affect activity, but these effects are not fully understood. Here, we examine N- and O-glycosylation on a model, multimodular glycoside hydrolase family 7 cellobiohydrolase (Cel7A), which exhibits an O-glycosylated carbohydrate-binding module (CBM) and an O-glycosylated linker connected to an N- and O-glycosylated catalytic domain (CD)-a domain architecture common to many biomass-degrading enzymes...
December 11, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29213319/natural-diversity-of-glycoside-hydrolase-family-48-exoglucanases-insights-from-structure
#4
Roman Brunecky, Markus Alahuhta, Deanne W Sammond, Qi Xu, Mo Chen, David B Wilson, John W Brady, Michael E Himmel, Yannick J Bomble, Vladimir V Lunin
Glycoside hydrolase (GH) family 48 is an understudied and increasingly important exoglucanase family found in the majority of bacterial cellulase systems. Moreover, many thermophilic enzyme systems contain GH48 enzymes. Deletion of GH48 enzymes in these microorganisms results in drastic reduction in biomass deconstruction. Surprisingly, given their importance for these microorganisms, GH48s have intrinsically low cellulolytic activity but even in low ratios synergize greatly with GH9 endoglucanases. In this study, we explore the structural and enzymatic diversity of these enzymes across a wide range of temperature optima...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/29213316/visualizing-chemical-functionality-in-plant-cell-walls
#5
REVIEW
Yining Zeng, Michael E Himmel, Shi-You Ding
Understanding plant cell wall cross-linking chemistry and polymeric architecture is key to the efficient utilization of biomass in all prospects from rational genetic modification to downstream chemical and biological conversion to produce fuels and value chemicals. In fact, the bulk properties of cell wall recalcitrance are collectively determined by its chemical features over a wide range of length scales from tissue, cellular to polymeric architectures. Microscopic visualization of cell walls from the nanometer to the micrometer scale offers an in situ approach to study their chemical functionality considering its spatial and chemical complexity, particularly the capabilities of characterizing biomass non-destructively and in real-time during conversion processes...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/29213309/structure-of-a-thermobifida-fusca-lytic-polysaccharide-monooxygenase-and-mutagenesis-of-key-residues
#6
Nathan Kruer-Zerhusen, Markus Alahuhta, Vladimir V Lunin, Michael E Himmel, Yannick J Bomble, David B Wilson
Background: Auxiliary activity (AA) enzymes are produced by numerous bacterial and fungal species to assist in the degradation of biomass. These enzymes are abundant but have yet to be fully characterized. Here, we report the X-ray structure of Thermobifida fusca AA10A (TfAA10A), investigate mutational characterization of key surface residues near its active site, and explore the importance of the various domains of Thermobifida fusca AA10B (TfAA10B). The structure of TfAA10A is similar to other bacterial LPMOs (lytic polysaccharide monooxygenases), including signs of photo-reduction and a distorted active site, with mixed features showing both type I and II copper coordination...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/29209415/undefined-cellulase-formulations-hinder-scientific-reproducibility
#7
EDITORIAL
Michael E Himmel, Charles A Abbas, John O Baker, Edward A Bayer, Yannick J Bomble, Roman Brunecky, Xiaowen Chen, Claus Felby, Tina Jeoh, Rajeev Kumar, Barry V McCleary, Brett I Pletschke, Melvin P Tucker, Charles E Wyman, Stephen R Decker
In the shadow of a burgeoning biomass-to-fuels industry, biological conversion of lignocellulose to fermentable sugars in a cost-effective manner is key to the success of second-generation and advanced biofuel production. For the effective comparison of one cellulase preparation to another, cellulase assays are typically carried out with one or more engineered cellulase formulations or natural exoproteomes of known performance serving as positive controls. When these formulations have unknown composition, as is the case with several widely used commercial products, it becomes impossible to compare or reproduce work done today to work done in the future, where, for example, such preparations may not be available...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/29209272/a-european-perspective-on-auditory-processing-disorder-current-knowledge-and-future-research-focus
#8
Vasiliki Vivian Iliadou, Martin Ptok, Helen Grech, Ellen Raben Pedersen, André Brechmann, Naïma Deggouj, Christiane Kiese-Himmel, Mariola Śliwińska-Kowalska, Andreas Nickisch, Laurent Demanez, Evelyne Veuillet, Hung Thai-Van, Tony Sirimanna, Marina Callimachou, Rosamaria Santarelli, Sandra Kuske, Jose Barajas, Mladen Hedjever, Ozlem Konukseven, Dorothy Veraguth, Tone Stokkereit Mattsson, Jorge Humberto Martins, Doris-Eva Bamiou
Current notions of "hearing impairment," as reflected in clinical audiological practice, do not acknowledge the needs of individuals who have normal hearing pure tone sensitivity but who experience auditory processing difficulties in everyday life that are indexed by reduced performance in other more sophisticated audiometric tests such as speech audiometry in noise or complex non-speech sound perception. This disorder, defined as "Auditory Processing Disorder" (APD) or "Central Auditory Processing Disorder" is classified in the current tenth version of the International Classification of diseases as H93...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/29202811/high-prevalence-of-prescription-of-psychotropic-drugs-for-older-patients-in-a-general-hospital
#9
Inken Arnold, Kati Straube, Wolfgang Himmel, Stephanie Heinemann, Vivien Weiss, Laura Heyden, Eva Hummers-Pradier, Roland Nau
BACKGROUND: Many elderly patients receive psychotropic drugs. Treatment with psychotropic agents is associated with serious side effects including an increased risk of falls and fractures. Several psychotropic drugs are considered potentially inappropriate for treatment of the elderly. METHODS: A retrospective chart review was conducted covering all patients aged ≥ 65 years who were admitted to Evangelisches Krankenhaus Göttingen-Weende between 01/01/2013 and 03/31/2013...
December 4, 2017: BMC Pharmacology & Toxicology
https://www.readbyqxmd.com/read/29186657/a-more-stable-template-localization-for-an-incremental-focal-point-approach-implementation-and-application-to-the-intramolecular-decomposition-of-tris-perfluoro-tert-butoxyalane
#10
Benjamin Fiedler, Daniel Himmel, Ingo Krossing, Joachim Friedrich
We present a new implementation of the template localization for the fully-automated and parallizable incremental method, which excludes failures of this important step within the domain-specific basis set approach and thus ensures a higher reliability of the scheme, preserving its very high accuracy. Furthermore, we combine our method with an efficient focal-point ansatz to reach the complete basis set limit and carefully assess this approach for the first time with regard to reaction energies. For a test set of 51 reactions the incremental focal-point method with a basis set of moderate size provides a very high accuracy with respect to the complete basis set limit...
November 29, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/29171707/basic-remarks-on-acidity
#11
Daniel Himmel, Valentin Radtke, Burkhard Butschke, Ingo Krossing
We report on a unified view on Brønsted acidity introduced by our group in this journal in 2010, its perception in the view of a synthetic/materials chemist contrasted by that of a physical or a theoretical chemist, and the discrepancy between both views. For this purpose, we provide a brief overview of the concepts acidity, acid strengths, and pH value, including problems, proposed solutions, and the pH_abs/pH_abs^H2O scale as a unifying concept developed in our group. Thereafter, we give some examples for accessibility and applications of unified pH_abs values...
November 24, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29161046/heavy-metal-free-tannin-from-bark-for-sustainable-energy-storage
#12
Alolika Mukhopadhyay, Yucong Jiao, Rui Katahira, Peter N Ciesielski, Michael E Himmel, Hongli Zhu
A novel renewable cathode made from earth-abundant, low-cost materials can contribute to the intermittent storage needs of renewable energy based society. Inspired by Nature, we report for the first-time tannin as a cathode material. Our approach exploits the charge storage mechanism of the redox active quinone moiety. Tannins extracted from tree bark using environmental friendly aqueous solvents has the highest phenol content (5.56 mol g-1) among all the natural phenolic biopolymers, 5000 times higher than lignin...
November 21, 2017: Nano Letters
https://www.readbyqxmd.com/read/29155467/synthesis-characterisation-and-reactions-of-truly-cationic-ni-i-phosphine-complexes
#13
Ingo Krossing, Miriam Mareen Schwab, Daniel Himmel, Sylwia Kacprzak, Valentin Radtke, Daniel Kratzert, Philippe Weis, Melanie Wernet, Andreas Peter, Zeinab Yassine, Dominik Schmitz, Ernst-Wilhelm Scheidt, Wolfgang Scherer, Stefan Weber, Wolfram Feuerstein, Frank Breher, Alexander Higelin
The recently published purely metalorganic NiI salt [Ni(cod)2][Al(ORF)4] (1, cod = 1,5-cyclooctadiene, RF = C(CF3)3) provides a starting point for a new synthesis strategy leading to NiI phosphine complexes, replacing cod ligands by phosphines. Clearly visible colour changes indicate reactions within minutes, while quantum chemical calculations (PBE0-D3(BJ)/def2-TZVPP) approve exergonic reaction enthalpies in all performed ligand exchange reactions. Hence, [Ni(dppp)2][Al(ORF)4] (2, dppp = 1,3-Bis(diphenylphosphino)propane), [Ni(dppe)2][Al(ORF)4] (3, dppe = 1,3-Bis(diphenyl-phosphino)ethane), three-coordinate [Ni(PPh3)3][Al(ORF)4] (4) and a remarkable two-coordinate NiI phosphine complex [Ni(PtBu3)2][Al(ORF)4] (5) were characterised via single crystal X-ray structure analysis...
November 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29154478/on-the-dual-reactivity-of-a-nucleophilic-dihydrido-diborane-reaction-at-the-b-b-bond-and-or-the-b-h-bond
#14
Anna Widera, Elisabeth Kaifer, Hubert Wadepohl, Hans-Jörg Himmel
The electron-rich, double-base stabilized dihydrido-diborane(4) [HB(hpp)]2 (hpp = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate) combines two different, easily accessible reactive sites: the B-B and B-H bond. We hereby report two basically similar reactions of [HB(hpp)]2 with catecholborane and B-chlorocatecholborane unsuspectedly resulting in two different reactivities. While reaction of the diborane with two equivalents of HB(cat) proceeded under formation of a cationic triborane with a (3c2e) bond, [{HB(μ-hpp)}2(μ-BH2)]+, reaction with ClB(cat) led to hydride-chloride substitution yielding [ClB(hpp)]2...
November 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29147523/a-unified-view-to-br%C3%A3-nsted-acidity-scales-do-we-need-solvated-protons
#15
Eno Paenurk, Karl Kaupmees, Daniel Himmel, Agnes Kütt, Ivari Kaljurand, Ilmar A Koppel, Ingo Krossing, Ivo Leito
The most comprehensive solvent acidity scale spanning 28 orders of magnitude of acidity was measured in the low-polarity solvent 1,2-dichloroethane (DCE). Its experimental core is linked to the unified acidity scale (pHabs) in an unprecedented and generalized approach only based on experimental values. This enables future measurements of acid strengths and acidity adjustments in low polarity solvents. The scale was cross-validated computationally. The purely experimental and computational data agree very well...
October 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29120636/the-vibrations-of-v2o4-matrix-isolation-and-quantum-chemical-calculations
#16
Olaf Hübner, Hans-Joerg Himmel
V2O4 has been generated in solid Ne and characterized by infrared spectroscopy and additionally by multi-reference configuration interaction and density functional calculations. Four vibrational transitions at 1003, 731.7, 640.9, and 309.1 cm-1 (16O2) have been observed and based on the calculations assigned to bu, au, bu, and bu modes, respectively, of the C2h symmetric structure. The calculated bond distances are in good agreement with the results of previous calculations.
November 9, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29101202/expression-of-a-cellobiose-phosphorylase-from-thermotoga-maritima-in-caldicellulosiruptor-bescii-improves-the-phosphorolytic-pathway-and-results-in-a-dramatic-increase-in-cellulolytic-activity
#17
Sun-Ki Kim, Michael E Himmel, Yannick J Bomble, Janet Westpheling
Members of the genus Caldicellulosiruptor have the ability to deconstruct and grow on lignocellulosic biomass without conventional pretreatment and a genetically tractable species, C. bescii, was recently engineered to produce ethanol directly from switchgrass. C. bescii contains more than 50 glycosyl-hydrolases and a suite of extracellular enzymes for biomass deconstruction, most prominently CelA, a multi-domain cellulase that uses a novel mechanism to deconstruct plant biomass. Accumulation of cellobiose, a product of CelA during growth on biomass, inhibits cellulase activity...
November 3, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29100023/lignocellulose-deconstruction-in-the-biosphere
#18
REVIEW
Yannick J Bomble, Chien-Yuan Lin, Antonella Amore, Hui Wei, Evert K Holwerda, Peter N Ciesielski, Bryon S Donohoe, Stephen R Decker, Lee R Lynd, Michael E Himmel
Microorganisms have evolved different and yet complementary mechanisms to degrade biomass in the biosphere. The chemical biology of lignocellulose deconstruction is a complex and intricate process that appears to vary in response to specific ecosystems. These microorganisms rely on simple to complex arrangements of glycoside hydrolases to conduct most of these polysaccharide depolymerization reactions and also, as discovered more recently, oxidative mechanisms via lytic polysaccharide monooxygenases or non-enzymatic Fenton reactions which are used to enhance deconstruction...
October 31, 2017: Current Opinion in Chemical Biology
https://www.readbyqxmd.com/read/29092732/searching-for-factors-that-may-reduce-the-use-of-benzodiazepines-in-hospitals-a-survey-of-hospital-doctors-and-nurses%C3%A2
#19
Stephanie Heinemann, Wolfgang Himmel
A chart review at a mid-sized German general hospital found a high usage of benzodiazepines among older patients. Therefore, all doctors and nurses of this hospital were surveyed about the benefits and risks of benzodiazepines that they considered to be the strongest and their own overall assessment of the risk-benefit ratio for their patients Response rate was 54% (63/116) for doctors and 30% (73/243) for nurses. "Reduced fear or agitation" was perceived by many doctors (71%) and nurses (49%) to be a strong benefit of benzodiazepines...
October 26, 2017: International Journal of Clinical Pharmacology and Therapeutics
https://www.readbyqxmd.com/read/29059695/-auditory-processing-disorder-is-the-diagnosis-already-possible-in-first-graders
#20
Christiane Kiese-Himmel, Andreas Nickisch, Franziska Werner
Objective Significant differences in performance on an eclectic German test battery for Auditory Processing Disorders (APD) was found in the most diagnostic tools between children with APD and controls in the 2nd, 3rd and 4th school year of primary education. Aim of the present study was to examine whether it is also the case for first graders. Material and Methods The performance in the behavioral test battery (including 14 specific auditory tests) was compared in two subject groups (aged 6-8 yrs): 41 first graders with APD of a clinical database, 37 typically developing first graders without APD (controls)...
October 23, 2017: Laryngo- Rhino- Otologie
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