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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
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
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
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
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
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
Ute Wild, Florian Schön, Hans-Jörg Himmel
Herein we report the first examples for the use of redox-active guanidines as catalysts in the green oxidation of organic molecules with dioxygen. In one half-reaction, the oxidized state of the redox-active guanidine is converted to the reduced, protonated state, thereby enabling dehydrogenative oxidation of the substrate (3,5-ditertbutylcatechol → o-benzoquinone, benzoin → benzil, and 2,4-ditertbutylphenol → biphenol). In the other half-reaction, efficient re-oxidation of the guanidine to the oxidized state is achieved with dioxygen in the presence of a copper catalyst...
October 18, 2017: Angewandte Chemie
Chamarrita Farkas, Claire D Vallotton, Katherine Strasser, María Pía Santelices, Erika Himmel
Due to the rapid growth in early socioemotional skills during the first three years of life, significant variations in socioemotional development begin early and increase with time. Family competences as sensitivity and mentalization, contribute to differences among children of the same age. This study examines whether the level of socioemotional skills is stable or changes between 12 and 30 months of age, and whether primary caregiver sensitivity and mentalization, as well as educational level, are associated with changes in the level of socioemotional skills...
September 23, 2017: Infant Behavior & Development
Sun-Ki Kim, Daehwan Chung, Michael E Himmel, Yannick J Bomble, Janet Westpheling
Members of the genus Caldicellulosiruptor are the most thermophilic cellulolytic bacteria so far described and are capable of efficiently utilizing complex lignocellulosic biomass without conventional pretreatment. Previous studies have shown that accumulation of high concentrations of cellobiose and, to a lesser extent, cellotriose, inhibits cellulase activity both in vivo and in vitro and high concentrations of cellobiose are present in C. bescii fermentations after 90 h of incubation. For some cellulolytic microorganisms, β-D-glucosidase is essential for the efficient utilization of cellobiose as a carbon source and is an essential enzyme in commercial preparations for efficient deconstruction of plant biomass...
December 2017: Journal of Industrial Microbiology & Biotechnology
Roman Brunecky, Bryon S Donohoe, John M Yarbrough, Ashutosh Mittal, Brian R Scott, Hanshu Ding, Larry E Taylor Ii, Jordan F Russell, Daehwan Chung, Janet Westpheling, Sarah A Teter, Michael E Himmel, Yannick J Bomble
The crystalline nature of cellulose microfibrils is one of the key factors influencing biomass recalcitrance which is a key technical and economic barrier to overcome to make cellulosic biofuels a commercial reality. To date, all known fungal enzymes tested have great difficulty degrading highly crystalline cellulosic substrates. We have demonstrated that the CelA cellulase from Caldicellulosiruptor bescii degrades highly crystalline cellulose as well as low crystallinity substrates making it the only known cellulase to function well on highly crystalline cellulose...
August 29, 2017: Scientific Reports
Stefan C Meier, Albina Holz, Alexei Schmidt, Daniel Kratzert, Daniel Himmel, Ingo Krossing
The facile synthesis of a pentacarbonyl cobalt(I) salt without the need for a superacid as solvent is presented. This salt, [Co(CO)5 ](+) [Al(OR(F) )4 ](-) {R(F) =C(CF3 )3 }, readily accessible on a multigram scale, undergoes substitution reactions with arenes yielding the hitherto unknown class of two-legged cobalt piano-stool complexes [(arene)Co(CO)2 ](+) with four different arene ligands. Such a substitution chemistry would have been impossible in superacid solution, as the arenes used would have been oxidized and/or protonated...
August 10, 2017: Chemistry: a European Journal
David F Schrempp, Simone Leingang, Martin Schnurr, Elisabeth Kaifer, Hubert Wadepohl, Hans-Jörg Himmel
Fast and efficient electron transfer in blue copper proteins is realized by a structural harmonization between the Cu(I) and Cu(II) complex pair ("entatic state" model). Herein, we present now a Cu(I) /Cu(II) complex pair with redox-active guanidine ligands showing almost perfect match between both redox states. By modifying the ligand electron donor strength, the redox chemistry of the copper complex can be controlled to be either metal-centered or to cross the borderline to ligand-centered. This work is the first systematic study of complexes with redox-active ligands within the concept of the entatic state...
August 3, 2017: Chemistry: a European Journal
Olaf Hübner, Hans-Jörg Himmel
Detailed knowledge of the electronic structure of vanadium oxide clusters provides the basis for understanding and tuning their significant catalytic properties. However, already for the simple four-atom V2 O2 molecule, there are contradictory reports in the literature regarding the electronic ground state and a possible vanadium-vanadium bond. We herein show through a combination of experimental (matrix isolation) studies and theoretical results that there is a multiple vanadium-vanadium bond in this benchmark vanadium oxide molecule...
July 31, 2017: Angewandte Chemie
Qi Xu, Eric P Knoshaug, Wei Wang, Markus Alahuhta, John O Baker, Shihui Yang, Todd Vander Wall, Stephen R Decker, Michael E Himmel, Min Zhang, Hui Wei
BACKGROUND: Lipomyces starkeyi is one of the leading lipid-producing microorganisms reported to date; its genetic transformation was only recently reported. Our aim is to engineer L. starkeyi to serve in consolidated bioprocessing (CBP) to produce lipid or fatty acid-related biofuels directly from abundant and low-cost lignocellulosic substrates. RESULTS: To evaluate L. starkeyi in this role, we first conducted a genome analysis, which revealed the absence of key endo- and exocellulases in this yeast, prompting us to select and screen four signal peptides for their suitability for the overexpression and secretion of cellulase genes...
July 24, 2017: Microbial Cell Factories
Markus Frick, Elisabeth Kaifer, Hans-Jörg Himmel
Diboration of unsaturated organic compounds is an extremely useful reaction in synthetic chemistry. Herein, we report the first diboration of a nitrile by an electron-rich diborane, mediated by an electrophilic borane. The reaction is metal-free, and all of the reagents are readily available.
September 11, 2017: Angewandte Chemie
Breeanna R Urbanowicz, Vivek S Bharadwaj, Markus Alahuhta, Maria J Peña, Vladimir V Lunin, Yannick J Bomble, Shuo Wang, Jeong-Yeh Yang, Sami T Tuomivaara, Michael E Himmel, Kelley W Moremen, William S York, Michael F Crowley
The mechanistic underpinnings of the complex process of plant polysaccharide biosynthesis are poorly understood, largely because of the resistance of glycosyltransferase (GT) enzymes to structural characterization. In Arabidopsis thaliana, a glycosyl transferase family 37 (GT37) fucosyltransferase 1 (AtFUT1) catalyzes the regiospecific transfer of terminal 1,2-fucosyl residues to xyloglucan side chains - a key step in the biosynthesis of fucosylated sidechains of galactoxyloglucan. We unravel the mechanistic basis for fucosylation by AtFUT1 with a multipronged approach involving protein expression, X-ray crystallography, mutagenesis experiments and molecular simulations...
July 3, 2017: Plant Journal: for Cell and Molecular Biology
Bryon S Donohoe, Hui Wei, Ashutosh Mittal, Todd Shollenberger, Vladimir V Lunin, Michael E Himmel, Roman Brunecky
In planta expression of a thermophilic endoglucanase (AcCel5A) reduces recalcitrance by creating voids and other irregularities in cell walls of Arabidopsis thaliana that increase enzyme accessibility without negative impacts on plant growth or cell wall composition. Our results suggest that cellulose β-1-4 linkages can be cut sparingly in the assembling wall and that these minimal changes, made at the proper time, have an impact on plant cell wall recalcitrance without negative effects on overall plant development...
June 29, 2017: Scientific Reports
David Fridolin Schrempp, Elisa Schneider, Elisabeth Kaifer, Hubert Wadepohl, Hans-Jörg Himmel
A new redox-active 4,5-bisguanidino-substituted o-benzoquinone ligand L is synthesized, which allows rational access to heterobinuclear complexes through the sequential coordination of two metals. In the examples discussed in this work, mononuclear Cu and Pd complexes are prepared in a first coordination step, and these complexes are then used as precursors to homobinuclear [Cu(II) -L(0) -Cu(II) ] and heterobinuclear [Pd(II) -L(0) -Cu(II) ] complexes. In the heterobinuclear complex, the Pd(II) is coordinated by the softer bisguanidine side of L and the Cu(II) by the harder dioxolene side (in line with the HSAB concept)...
June 27, 2017: Chemistry: a European Journal
Sun-Ki Kim, Daehwan Chung, Michael E Himmel, Yannick J Bomble, Janet Westpheling
The use of microbial cells to convert plant biomass directly to fuels and chemicals is referred to as consolidated bioprocessing (CBP). Members of the bacterial genus, Caldicellulosiruptor (Gram-positive, anaerobic hyperthermophiles) are capable of deconstructing plant biomass without enzymatic or chemical pretreatment. This is accomplished by the production and secretion of free, multi-domain enzymes that outperform commercial enzyme cocktails on some substrates. Here, we show that the exoproteome of Caldicellulosiruptor bescii may be enhanced by the heterologous expression of enzymes from Acidothermus cellulolyticus that act synergistically to improve sugar release from complex substrates; as well as improve cell growth...
November 2017: Biotechnology and Bioengineering
P Adamson, L Aliaga, D Ambrose, N Anfimov, A Antoshkin, E Arrieta-Diaz, K Augsten, A Aurisano, C Backhouse, M Baird, B A Bambah, K Bays, B Behera, S Bending, R Bernstein, V Bhatnagar, B Bhuyan, J Bian, T Blackburn, A Bolshakova, C Bromberg, J Brown, G Brunetti, N Buchanan, A Butkevich, V Bychkov, M Campbell, E Catano-Mur, S Childress, B C Choudhary, B Chowdhury, T E Coan, J A B Coelho, M Colo, J Cooper, L Corwin, L Cremonesi, D Cronin-Hennessy, G S Davies, J P Davies, P F Derwent, R Dharmapalan, P Ding, Z Djurcic, E C Dukes, H Duyang, S Edayath, R Ehrlich, G J Feldman, M J Frank, M Gabrielyan, H R Gallagher, S Germani, T Ghosh, A Giri, R A Gomes, M C Goodman, V Grichine, R Group, D Grover, B Guo, A Habig, J Hartnell, R Hatcher, A Hatzikoutelis, K Heller, A Himmel, A Holin, J Hylen, F Jediny, M Judah, G K Kafka, D Kalra, S M S Kasahara, S Kasetti, R Keloth, L Kolupaeva, S Kotelnikov, I Kourbanis, A Kreymer, A Kumar, S Kurbanov, K Lang, W M Lee, S Lin, J Liu, M Lokajicek, J Lozier, S Luchuk, K Maan, S Magill, W A Mann, M L Marshak, K Matera, V Matveev, D P Méndez, M D Messier, H Meyer, T Miao, W H Miller, S R Mishra, R Mohanta, A Moren, L Mualem, M Muether, S Mufson, R Murphy, J Musser, J K Nelson, R Nichol, E Niner, A Norman, T Nosek, Y Oksuzian, A Olshevskiy, T Olson, J Paley, P Pandey, R B Patterson, G Pawloski, D Pershey, O Petrova, R Petti, S Phan-Budd, R K Plunkett, R Poling, B Potukuchi, C Principato, F Psihas, A Radovic, R A Rameika, B Rebel, B Reed, D Rocco, P Rojas, V Ryabov, K Sachdev, P Sail, O Samoylov, M C Sanchez, R Schroeter, J Sepulveda-Quiroz, P Shanahan, A Sheshukov, J Singh, J Singh, P Singh, V Singh, J Smolik, N Solomey, E Song, A Sousa, K Soustruznik, M Strait, L Suter, R L Talaga, M C Tamsett, P Tas, R B Thayyullathil, J Thomas, X Tian, S C Tognini, J Tripathi, A Tsaris, J Urheim, P Vahle, J Vasel, L Vinton, A Vold, T Vrba, B Wang, M Wetstein, D Whittington, S G Wojcicki, J Wolcott, N Yadav, S Yang, J Zalesak, B Zamorano, R Zwaska
Results are reported from an improved measurement of ν_{μ}→ν_{e} transitions by the NOvA experiment. Using an exposure equivalent to 6.05×10^{20} protons on target, 33 ν_{e} candidates are observed with a background of 8.2±0.8 (syst.). Combined with the latest NOvA ν_{μ} disappearance data and external constraints from reactor experiments on sin^{2}2θ_{13}, the hypothesis of inverted mass hierarchy with θ_{23} in the lower octant is disfavored at greater than 93% C.L. for all values of δ_{CP}.
June 9, 2017: Physical Review Letters
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