bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extrem starke Lewis‐Basen – Synthese und Methylkationaffinitäten von Dimethylamino‐substituierten Terpyridinen
Authors: Hommes Paul , Fischer Christina , Lindner Christoph , Zipse Hendrik , Reißig Hans‐Ulrich 
Published: June 2014

AbstractEs wird eine vielseitig einsetzbare Methode zur Herstellung von funktionalisierten 2,2′:6′,2′′‐Terpyridinen vorgestellt, bei der die äußeren Pyridinringe über Cyclisierungsreaktionen aufgebaut werden. Die Vorstufen – Bis‐β‐ketoenamide – werden aus in 4‐Position substituierten 2,6‐Pyridindicarbonsäuren und Acetylaceton oder dem entsprechenden Enaminoketon hergestellt. Ihre Cyclisierung erfolgt mithilfe von Trifluormethansulfonsäuretrimethylsilylester durch eine zweifache intramolekulare Kondensation. Die Methode bietet einen effizienten Zugang zu 4,4′′‐di‐ und 4,4′,4′′‐trifunktionalisierten 6,6′′‐Dimethyl‐2,2′:6′,2′′‐terpyridinen und ermöglicht die Herstellung bislang unbekannter 4,4′′‐Bis(dimethylamino)‐ und 4,4′,4′′‐Tris(dimethylamino)terpyridine, für die extrem hohe Lewis‐Basizitäten berechnet wurden.
A Cooperative N‐Heterocyclic Carbene/Chiral Phosphate Catalysis System for Allenolate Annulations
Authors: Lee Anna , Scheidt Karl A. 
Published: June 2014

AbstractThe highly enantioselective NHC‐catalyzed [3+2] annulation reaction with α,β‐alkynals and α‐ketoesters has been developed. A new mode of cooperative catalysis involving the combination of a chiral Brønsted acid and a C1‐symmetric biaryl saturated‐imidazolium precatalyst was required to generate the desired γ‐crotonolactones in high yields and levels of enantioselectivity.
Optische Kontrolle der Acetylcholinesterase mit einem schaltbaren Tacrin
Authors: Broichhagen Johannes , Jurastow Innokentij , Iwan Katharina , Kummer Wolfgang , Trauner Dirk 
Published: June 2014

AbstractPhotochrome Liganden lassen sich dazu verwenden, um diverse biologische Funktionen, insbesondere in neuronalen Systemen, zu steuern. In letzter Zeit wurde die Photokontrolle von Ionenkanälen und G‐Protein‐gekoppelten Rezeptoren, die in der Synapse zu finden sind, intensiv beforscht. Nun beschreiben wir die Erweiterung unseres photopharmakologischen Ansatzes zur Lichtsteuerung eines Enzyms. Unsere Untersuchungen zu photochromen Inhibitoren eines der wichtigsten Enzyme in der synaptischen Übertragung, der Acetylcholinesterase (AChE), führten zum strukturbasierten Design mehrerer Azobenzol‐Analoga des bekannten AChE‐Hemmers Tacrin (THA). Eine unserer Verbindungen, AzoTHA, ist ein reversibler photochromer Blocker, der AChE in vitro und ex vivo mit hoher Affinität und schneller Kinetik hemmt. Daher kann AzoTHA über den lichtabhängigen Abbau eines Neurotransmitters dazu verwendet werden, die synaptische Übertragung an der neuromuskulären Endplatte zu steuern.
Chirality Induction and Amplification in the 2,2,2‐Trifluoroethanol⋅⋅⋅Propylene Oxide Adduct
Authors: Thomas Javix , Jäger Wolfgang , Xu Yunjie 
Published: June 2014

AbstractChirality induction and amplification in a model system, that is, the 2,2,2‐trifluoroethanol (TFE)⋅⋅⋅propylene oxide (PO) adduct, were investigated using free‐space and cavity‐based Fourier transform microwave spectroscopy, complemented with high level ab initio calculations. Rotational spectra of four out of eight predicted TFE⋅⋅PO adducts were assigned, and the remaining four were shown to relax to the geometries of the four observed in a jet expansion. The g+ TFE⋅⋅⋅S‐PO adduct was found to be favored over that of g− TFE⋅⋅⋅S‐PO by a factor of 2.8 at 60 K. This difference contrasts the TFE dimer for which an extreme case of chirality synchronization was previously reported. All TFE⋅⋅⋅PO conformers observed take on the open arrangement, in contrast to 2‐fluoroethanol⋅⋅⋅PO, which prefers the closed arrangement. Furthermore, perfluorination at CH3 increases the hydrogen‐bonding energy by about 70 % over its ethanol counterpart.
In Vitro Synthesis of the E. coli Sec Translocon from DNA
Authors: Matsubayashi Hideaki , Kuruma Yutetsu , Ueda Takuya 
Published: June 2014

AbstractDifficulties in constructing complex lipid/protein membranes have severely limited the development of functional artificial cells endowed with vital membrane‐related functions. The Sec translocon membrane channel, which mediates the insertion of membrane proteins into the plasma membrane, was constructed in the membrane of lipid vesicles through in vitro expression of its component proteins. The components of the Sec translocon were synthesized from their respective genes in the presence of liposomes, thereby bringing about a functional complex. The synthesized E. coli Sec translocon mediated the membrane translocation of single‐ and multi‐span membrane proteins. The successful translocation of a functional peptidase into the liposome lumen further confirmed the proper insertion of the translocon complex. Our results demonstrate the feasible construction of artificial cells, the membranes of which can be functionalized by directly decoding genetic information into membrane functions.
Oberflächenunterstützte großflächige Anordnung von DNA‐Origami‐Kacheln
Authors: Aghebat Rafat Ali , Pirzer Tobias , Scheible Max B. , Kostina Anna , Simmel Friedrich C. 
Published: June 2014

AbstractDie großflächige Anordnung von DNA‐basierten Nanostrukturen in geordnete Überstrukturen ist ein wichtiger Schritt auf dem Weg zu deren Nutzung als funktionale molekulare Materialien. In dieser Arbeit zeigen wir, dass durch elektrostatische Kontrolle der Adhäsion und der Mobilität von DNA‐Origami‐Strukturen auf Glimmeroberflächen mittels einfacher Zugabe von monovalenten Kationen große geordnete 2D‐Gitterstrukturen aus Origami‐Kacheln erzeugt werden können. Die Gitter können entweder durch dichtes Packen symmetrischer, wechselwirkungsloser DNA‐Origami‐Strukturen erzeugt werden oder durch Nutzung von Basenstapelwechselwirkungen zwischen Origamieinheiten. Die resultierenden kristallinen Gitter können direkt als Vorlage für die strukturierte Anordnung von Proteinen genutzt werden.
Structure‐Driven Orientation of the High‐Spin–Low‐Spin Interface in a Spin‐Crossover Single Crystal
Authors: Sy Mouhamadou , Varret François , Boukheddaden Kamel , Bouchez Guillaume , Marrot Jérôme , Kawata Santoshi , Kaizaki Sumio 
Published: June 2014

AbstractThe orientation of the high‐spin (HS)–low‐spin (LS) macroscopic interface at the thermal transition of thin [{Fe(NCSe)(py)2}2(m‐bpypz)] crystals is explained by considering the possible vanishing of the structural mismatch between the coexisting phases. The structural property which allows mismatch‐free interfaces is characterized. The observed orientations of the interface and the tilt angle between the HS and LS domains are accurately reproduced by a two‐dimensional continuous medium model, based on the structural data. Simulations using an atomistic electro‐elastic model meet the predictions of the macroscopic analysis and provide information on the distribution of the elastic energy density in the biphasic state. The presence of mismatch‐free domain structures can explain the exceptional resilience of these crystals upon repeated switching.
Sulfur‐Functionalized Graphene Oxide by Epoxide Ring‐Opening
Authors: Thomas Helen R. , Marsden Alexander J. , Walker Marc , Wilson Neil R. , Rourke Jonathan P. 
Published: June 2014

AbstractThe treatment of graphene oxide (GO) with potassium thioacetate followed by an aqueous work‐up yields a new material via the ring‐opening of the epoxide groups. The new material is a thiol‐functionalized GO (GO‐SH) which is able to undergo further functionalization. Reaction with butyl bromide gives another new material, GO‐SBu, which shows significantly enhanced thermal stability compared to both GO and GO‐SH. The thiol‐functionalized GO material showed a high affinity for gold, as demonstrated by the selective deposition of a high density of gold nanoparticles.
The Self‐Sorting Behavior of Circular Helicates and Molecular Knots and Links
Authors: Ayme Jean‐François , Beves Jonathon E. , Campbell Christopher J. , Leigh David A. 
Published: June 2014

AbstractWe report on multicomponent self‐sorting to form open circular helicates of different sizes from a primary monoamine, FeII ions, and dialdehyde ligand strands that differ in length and structure by only two oxygen atoms. The corresponding closed circular helicates that are formed from a diamine—a molecular Solomon link and a pentafoil knot—also self‐sort, but up to two of the Solomon‐link‐forming ligand strands can be accommodated within the pentafoil knot structure and are either incorporated or omitted depending on the stage that the components are mixed.
[NiFe]Hydrogenase from Citrobacter sp. S‐77 Surpasses Platinum as an Electrode for H2 Oxidation Reaction
Authors: Matsumoto Takahiro , Eguchi Shigenobu , Nakai Hidetaka , Hibino Takashi , Yoon Ki‐Seok , Ogo Seiji 
Published: June 2014

AbstractReported herein is an electrode for dihydrogen (H2) oxidation, and it is based on [NiFe]Hydrogenase from Citrobacter sp. S‐77 ([NiFe]S77). It has a 637 times higher mass activity than Pt (calculated based on 1 mg of [NiFe]S77 or Pt) at 50 mV in a hydrogen half‐cell. The [NiFe]S77 electrode is also stable in air and, unlike Pt, can be recovered 100 % after poisoning by carbon monoxide. Following characterization of the [NiFe]S77 electrode, a fuel cell comprising a [NiFe]S77 anode and Pt cathode was constructed and shown to have a a higher power density than that achievable by Pt.
Deorphaning Pyrrolopyrazines as Potent Multi‐Target Antimalarial Agents
Authors: Reker Daniel , Seet Michael , Pillong Max , Koch Christian P. , Schneider Petra , Witschel Matthias C. , Rottmann Matthias , Freymond Céline , Brun Reto , Schweizer Bernd , Illarionov Boris , Bacher Adelbert , Fischer Markus , Diederich François , Schneider Gisbert 
Published: June 2014

AbstractThe discovery of pyrrolopyrazines as potent antimalarial agents is presented, with the most effective compounds exhibiting EC50 values in the low nanomolar range against asexual blood stages of Plasmodium falciparum in human red blood cells, and Plasmodium berghei liver schizonts, with negligible HepG2 cytotoxicity. Their potential mode of action is uncovered by predicting macromolecular targets through avant‐garde computer modeling. The consensus prediction method suggested a functional resemblance between ligand binding sites in non‐homologous target proteins, linking the observed parasite elimination to IspD, an enzyme from the non‐mevalonate pathway of isoprenoid biosynthesis, and multi‐kinase inhibition. Further computational analysis suggested essential P. falciparum kinases as likely targets of our lead compound. The results obtained validate our methodology for ligand‐ and structure‐based target prediction, expand the bioinformatics toolbox for proteome mining, and provide unique access to deciphering polypharmacological effects of bioactive chemical agents.
α‐ and β‐Lipomycin: Total Syntheses by Sequential Stille Couplings and Assignment of the Absolute Configuration of All Stereogenic Centers
Authors: Hofferberth Max L. , Brückner Reinhard 
Published: June 2014

Abstract40 years ago spectroscopy, derivatization, and degradation revealed the structures of α‐lipomycin and its aglycon β‐lipomycin except for the configurations of their side‐chain stereocenters. We synthesized all relevant β‐lipomycin candidates: the (12R,13S) isomer has the same specific rotational value as the natural product. By the same criterion the (12R,13S)‐configured D‐digitoxide is identical to α‐lipomycin. We double‐checked our assignments by degrading α‐ and β‐lipomycin to the diesters 33 and 34 and proving their 3D structures synthetically.
The Synthesis of α‐Azidoesters and Geminal Triazides
Authors: Klahn Philipp , Erhardt Hellmuth , Kotthaus Andreas , Kirsch Stefan F. 
Published: June 2014

AbstractThree simple methods for the synthesis of geminal triazides are described: Starting from 1) 3‐oxocarboxylic acids, 2) iodomethyl ketones, or 3) terminal olefins, a range of triazidomethyl ketones can be constructed under mild oxidative reaction conditions by the use of IBX‐SO3K, a sulfonylated derivative of 2‐iodoxybenzoic acid (IBX), and NaN3 as an azide source. This is the first report of representatives of this novel class of triazide compounds: Despite their high nitrogen content, the geminal triazides are easy to handle, even when preparative‐scale syntheses are performed. (Caution: These procedures still require protective measures!) The triazides are now broadly available for further studies regarding their properties and reactivity. Furthermore, we show how the method can be used to provide α‐azidoesters, which are potential building blocks for amino acids.
The Molecular Basis of Conjugated Polyyne Biosynthesis in Phytopathogenic Bacteria
Authors: Ross Claudia , Scherlach Kirstin , Kloss Florian , Hertweck Christian 
Published: June 2014

AbstractPolyynes (polyacetylenes), which are produced by a variety of organisms, play important roles in ecology. Whereas alkyne biosynthesis in plants, fungi, and insects has been studied, the biogenetic origin of highly unstable bacterial polyynes has remained a riddle. Transposon mutagenesis and genome sequencing unveiled the caryoynencin (cay) biosynthesis gene cluster in the plant pathogen B. caryophylli, and homologous gene clusters were found in various other bacteria by comparative genomics. Gene inactivation and phylogenetic analyses revealed that novel desaturase/acetylenase genes mediate bacterial polyyne assembly. A cytochrome P450 monooxygenase is involved in the formation of the allylic alcohol moiety, as evidenced by analysis of a fragile intermediate, which was stabilized by an in situ click reaction. This work not only grants first insight into bacterial polyyne biosynthesis but also demonstrates that the click reaction can be employed to trap fragile polyynes from crude mixtures.
Surface‐Assisted Large‐Scale Ordering of DNA Origami Tiles
Authors: Aghebat Rafat Ali , Pirzer Tobias , Scheible Max B. , Kostina Anna , Simmel Friedrich C. 
Published: June 2014

AbstractThe arrangement of DNA‐based nanostructures into extended higher order assemblies is an important step towards their utilization as functional molecular materials. We herein demonstrate that by electrostatically controlling the adhesion and mobility of DNA origami structures on mica surfaces by the simple addition of monovalent cations, large ordered 2D arrays of origami tiles can be generated. The lattices can be formed either by close‐packing of symmetric, non‐interacting DNA origami structures, or by utilizing blunt‐end stacking interactions between the origami units. The resulting crystalline lattices can be readily utilized as templates for the ordered arrangement of proteins.
Lanthanide‐Based Functional Misfit‐Layered Nanotubes
Authors: Panchakarla Leela S. , Popovitz‐Biro Ronit , Houben Lothar , Dunin‐Borkowski Rafal E. , Tenne Reshef 
Published: June 2014

AbstractThe synthesis of nanotubes from layered compounds has generated substantial scientific interest. “Misfit” layered compounds (MLCs) of the general formula [(MX)1+x]m[TX2]n, where M can include Pb, Sb, rare earths; T=Cr, Nb, and X=S, Se can form layered structures, even though each sub‐system alone is not necessarily a layered or a stable compound. A simple chemical method is used to synthesize these complex nanotubes from lanthanide‐based misfit compounds. Quaternary nanotubular structures formed by partial substitution of the lanthanide atom in nanotubes by other elements are also confirmed. The driving force and mechanism of formation of these nanotubes is investigated by systematic temperature and time‐dependent studies. A stress‐inducement mechanism is proposed to explain the formation of the nanotubes. The resulting materials may find applications in fields that include thermoelectrics, light emitters, and catalysis and address fundamental physical issues in low dimensions.
Evolution of the properties of a poly(l‐lactic acid) scaffold with double porosity during in vitro degradation in a phosphate‐buffered saline solution
Authors: Deplaine Harmony , Acosta‐Santamaría Victor A. , Vidaurre Ana , Gómez Ribelles José Luis , Doblaré Manuel , Ochoa Ignacio , Gallego Ferrer Gloria 
Published: June 2014

ABSTRACTA poly(l‐lactic acid) scaffold prepared by a combination of freeze‐extraction and porogen‐leaching methods was submitted to static degradation in a phosphate‐buffered saline solution at pH 7.4 and 37°C for up to 12 months. After 6 months of degradation, the scaffold maintained its integrity, although noticeable changes in its permeability and pore size were recorded. After 12 months, scanning electron microscopy pictures showed that most of the trabeculae were broken, and the sample disaggregated under minimum loading. Neither weight loss nor crystallinity changes in the first heating calorimetric scan were observed during the degradation experiment. However, after 12 months, a rise in the crystallinity from 13 to 38% and a drop in the glass‐transition temperature from 58 to 54°C were measured in the second heating scan. The onset of thermal degradation moved from 300 to 210°C after 12 months. Although the elastic modulus suffered only a very slight reduction with degradation time, the aggregate modulus decreased 44% after 6 months. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40956.
Aid Volatility: Is It a Problem inTuvalu?
Authors: Iulai Letasi 
Published: June 2014

AbstractEmpirical evidence on aid volatility shows that it adversely impacts recipient countries. This study seeks to find if aid volatility matters inTuvalu—a small aid recipient country in thePacific. The study finds that, with a coefficient of variation of 0.49, aid volatility inTuvalu is significant. It is also found that project aid is more volatile than aid that goes to budget support and routine programs such as scholarships. Aid volatility results in incomplete projects, high transaction costs, ‘Dutch disease’ and fiscal planning problems. To manage the adverse impacts of aid volatility,Tuvalu needs to strengthen itsConsolidatedInvestmentFund to buffer for any disruptions in aid disbursements, provide a sound policy and institutional climate, target aid to budget support and programs instead of specific projects, and implement large infrastructure projects in phases.
From Intervention to Partnership—Prospects for Development Partnership in Solomon Islands after the RAMSI
Authors: Barbara Julien 
Published: June 2014

AbstractThis article considers prospects for effective development partnership in Solomon Islands following the transition of development assistance from the Regional Assistance Mission to Solomon Islands (RAMSI) to bilateral donors in 2013. It focuses on the shifting nature of Australian aid that has transitioned from an interventionary approach under RAMSI to a partnership‐based approach under the bilateral program. Prospects for partnership in Solomon Islands are complicated by issues of state fragility, political instability and aid dependency that undermine local ownership and alignment. While the rhetoric of partnership guided RAMSI transition, Australia's post‐RAMSI aid responds to these challenges through a hybrid approach incorporating partnership and interventionary modalities. This hybrid approach reflects Australia's role in the co‐production of sovereignty in Solomon Islands. Recognition of the hybrid nature of Australian aid, and, by implication, Australia's ‘ownership’ of development problems in Solomon Islands, will be important to the effectiveness of future support.
Informed consent and the prescription of nonsteroidal antiinflammatory drugs
Authors: Katz Jeffrey N. , Daltroy Lawren H. , Brennan Troyen A. , Liang Matthew H. 
Published: June 2014

AbstractObjective. To examine disclosure of side effects of nonsteroidal antiinflammatory drugs (NSAIDs) and to identify patient‐ and physician‐specific factors associated with greater disclosure.Methods. Forty‐six encounters between rheumatologists and new adult outpatients who were prescribed an NSAID they had not been taking prior to the visit were audiotaped. Reviewers coded the NSAID prescribed, specific side effects mentioned, demographic features of patients and physicians, and patient clinical characteristics. Neither patients nor physicians were aware that side effect disclosure was being studied.Results. A mean of 1.7 side effects was mentioned per encounter. Epigastric discomfort was mentioned in 72% of encounters, while other side effects, including hepatic, renal, hematologic, or central nervous system effects, were mentioned in ≤15% of encounters. Three factors were identified as independent predictors of less disclosure of side effects: senior clinician (versus less experienced), patient not taking another NSAID immediately prior to the visit, and patient age <40. Increased disclosure by less experienced clinicians occurred exclusively with patients who were taking another NSAID prior to the visit.Conclusion. Disclosure of side effects other than epigastric discomfort to patients who are prescribed a new NSAID is limited. Patients not taking NSAIDs previously, who presumably have the most to gain from such discussions, are told the least. These results have implications with regard to doctor—patient decision‐making and malpractice litigation in the outpatient setting.
Psychological well‐being among people with recently diagnosed rheumatoid arthritis: Do self‐perceptions of abilities make a difference?
Authors: Blalock Susan J. , Devellis Brenda M. , Devellis Robert F. , Giorgino Karen B. , Sauter Suzanne van H. , Jordan Joanne M. , Keefe Francis J. , Mutran Elizabeth J. 
Published: June 2014

AbstractObjective. Satisfaction with abilities and perceived importance of abilities are 2 factors involved in the process of self‐evaluation. We examined the role that these factors play in adjustment to rheumatoid arthritis (RA).Methods. Data were collected, via telephone interview and mailed questionnaire, from 234 individuals with recently diagnosed RA. Disease severity information was obtained from participants' physicians.Results. Consistent with study hypotheses, satisfaction was associated with psychological well‐being only among those who viewed as very important the abilities being evaluated.Conclusion. These findings increase understanding of the conditions under which low levels of satisfaction are likely to be associated with psychological distress.
Defective hypothalamic response to immune and inflammatory stimuli in patients with rheumatoid arthritis
Authors: Chikanza Ian C. , Petrou Petros , Kingsley Gabrielle , Chrousos George , Panayi Gabriel S. 
Published: June 2014

AbstractObjective. To determine the integrity of the hypothalamic‐pituitary‐adrenal (HPA) axis responses to immune/inflammatory stimuli in patients with rheumatoid arthritis (RA).Methods. Diurnal secretion of cortisol and the cytokine and cortisol responses to surgery were studied in subjects with active RA, in subjects with chronic osteomyelitis (OM), and in subjects with noninflammatory arthritis, who served as controls.Results. Patients with RA had a defective HPA response, as evidenced by a diurnal cortisol rhythm of secretion which was at the lower limit of normal in contrast to those with OM, and a failure to increase cortisol secretion following surgery, despite high levels of interleukin‐1β (IL‐1β) and IL‐6. The corticotropin‐releasing hormone stimulation test in the RA patients showed normal results, thus suggesting a hypothalamic defect, but normal pituitary and adrenal function.Conclusion. These findings suggest that RA patients have an abnormality of the HPA axis response to immune/inflammatory stimuli which may reside in the hypothalamus. This hypothalamic abnormality may be an additional, and hitherto unrecognized, factor in the pathogenesis of RA.