bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating Salary Compression in an ARL Institution: A University of Colorado at Boulder Case Study
Authors: Seaman Scott
Published: June 2014

Salary compression is the narrowing of the pay differentials between people in the same job but with widely varying years of experience. Within academics, the most commonly asserted cause for salary compression is that of a labor shortage. When institutions compete in a job market with more vacancies than candidates, salaries for vacant positions increase faster than salaries for filled positions. As resources are directed at recruiting new hires rather than annual merit increases, productive senior staff find themselves earning similar salaries as new hires. While this has been common in disciplines such as business, nursing, and engineering, there is also anecdotal evidence that the conditions may have existed for this to happen in librarianship during the late 1990s. This case study defines salary compression, reviews the context in which it may arise, and discusses those conditions in which compression may be beneficial or may be detrimental, and examines the statistical tools used to detect evidence of compression within an organization. Multiple regression analysis is used to determine if there is evidence of salary compression among the librarians at the University of Colorado at Boulder.
Selected Reference Works, 2006–2007
Authors: Witte Sarah , Cargill Mary
Published: June 2014

This article follows the pattern set by the semiannual series initiated by the late Constance M. Winchell more than fifty years ago and continued first by Eugene Sheehy and then by Eileen McIlvaine. Because the purpose of the list is to present a selection of recent scholarly and general works, it does not pretend to be either well balanced or comprehensive. A brief roundup of new editions of standard works is provided at the end of the articles. Code numbers (such as AC527) have been used to refer to titles in the Guide to Reference Books, 11th ed. (Chicago: ALA, 1996).
Feast AND Famine: A Statewide Science Serial Collection Assessment in Illinois
Authors: Schmidt Karen , Chrzastowski Tina E. , Naun Chew Chiat , Norman Michael
Published: June 2014

In 2004, a group of Illinois librarians was awarded a research grant to assess the state of Illinois’ science serial collection. This collection assessment focused on academic libraries in the state, specifically those participating in the Consortium of Academic Research Libraries in Illinois (CARLI), but also including another 10 academic libraries in the state that do not belong to the consortium. Current serial subscription data were collected through both automated and manual means and the analysis was conducted in conjunction with Ulrich’s Serials Analysis System. Due to cataloging limitations and issues surrounding different ISSNs for print and electronic formats, the study centered on current (as of spring 2005) print serial subscriptions. Results found that well over half of the state’s print serial subscriptions were Illinois’ “last copy” and another 13 percent were at risk, with only two copies owned in the state. And while most titles were limited to one print copy within Illinois, other titles have wide accessibility and duplication at a high cost to the state.
Organizational Learning in the Evaluation Procedures: A Qualitative Study
Authors: Chen Kuan-nien , Lin Pei-chun
Published: June 2014

The study investigated the nature of organizational learning within Taiwanese Institute of Technology academic libraries, and in particular the nature of the relationship between the Institutional Evaluation of those libraries by the Ministry of Education and the organizational response of the libraries. Semistructured interviews were conducted with 24 library personnel, including directors. These interviews resulted in the identification of three themes. The results of this study show that few libraries seem to be achieving what might be considered an adequate level of organizational learning, largely, it seems, because of internal barriers and structural problems with how the institutional evaluation is implemented. It seems difficult for some libraries to use evaluation as a tool to assist with organizational learning. Libraries must engage more in a learning dialogue with their environments and enhance their capacity for effective organizational learning.
Librarians as Teachers: A Qualitative Inquiry into Professional Identity
Authors: Walter Scott
Published: June 2014

This study explores the development of “teacher identity” among academic librarians through a series of semistructured interviews. Drawing both on the idea of teacher identity from the literature of teacher education and on existing studies of professional stereotypes and professional identity development among academic librarians, this study explores the degree to which academic librarians think of themselves as teachers, the ways in which teaching has become a feature of their professional identity, and the factors that may influence academic librarians to adopt a “teacher identity” as part of their personal understandings of their role on campus.
A Mixed-Methods Investigation of the Relationship between Critical Thinking and Library Anxiety among Undergraduate Students in their Information Search Process
Authors: Kwon Nahyun
Published: June 2014

This study investigated the nature of associations between critical thinking dispositions and library anxiety among 137 undergraduate students. The study was conducted by administering standardized survey instruments and by analyzing the contents of student essays on critical incidents of their library use experience. The results of these quantitative and qualitative investigations consolidated each other by revealing negative associations between the two variables. An interactive model of critical thinking and library anxiety emerged from the investigation, showing how they interact with each other during the library use process. Both theoretical and practical implications of the findings were discussed within the frameworks of affective information behavior and information literacy, respectively.
The Proportion of NUC Pre-56 Titles Represented in the RLIN and OCLC Databases Compared: A Follow-up to the Beall/Kafadar Study
Authors: DeZelar-Tiedman Christine
Published: June 2014

This article replicates a previous study that investigated the proportion of bibliographic records from the National Union Catalog Pre-1956 Imprints in the OCLC WorldCat database and expands it to search a similar-sized sample of records in the RLIN database as well. The author seeks to determine the impact that the merger of the RLIN and OCLC databases will have on the ability to locate catalog records for older materials, and whether there are still significant numbers of library materials for which there are no online bibliographic records. Entries for non-Roman language materials were not included in the study.
Information Literacy from the Trenches: How Do Humanities and Social Science Majors Conduct Academic Research?
Authors: Head Alison J.
Published: June 2014

This article examines the ways in which students majoring in humanities and social sciences conceptualize and operationalize course-related research. Findings are presented from an information-seeking behavior study with data collected from student discussion groups, a student survey, and a content analysis of professors' research assignment handouts. Results indicate that students first use course readings and library resources for academic research and then rely on public Internet sites later in their research process. Students adopt a hybrid approach to course-related research. A majority of students in this study leveraged both human and computer-mediated resources to compensate for their lack of information literacy. In particular, students faced problems with determining information needs for assignments, selecting and critically evaluating resources, and gauging professors' expectations for quality research.
Identifying Student and Faculty Needs through LibQUAL+™: An Analysis of Qualitative Survey Comments
Authors: Jones Sherri , Kayongo Jessica
Published: June 2014

The LibQUAL+™ survey allows libraries to collect quantitative as well as qualitative data concerning their users. Comments that survey-takers provide contain a wealth of information that shed light on the quantitative responses they give to questions. This article reports on a study conducted by the authors to analyze the written comments provided by faculty and students participating in the 2006 LibQUAL+™ survey at the University of Notre Dame to determine, in a systematic way, what issues are most important to users and to see if there are differences among the three primary user groups. The authors were interested in whether the analysis of the comments would reveal the same issues that the quantitative data had.
The Traditional Future: A Computational Theory of Library Research
Authors: Abbott Andrew
Published: June 2014

I argue that library-based research should be conceived as a particular kind of research system, in contrast to more familiar systems like standard social scientific research (SSSR). Unlike SSSR, library-based research is based on nonelicited sources, which are recursively used and multiply ordered. It employs the associative algorithms of reading and browsing as opposed to the measurement algorithms of SSSR. Unlike SSSR, it is nonstandardized, nonsequential, and artisanally organized, deriving crucial power from multitasking. Taken together, these facts imply that, as a larger structure, library-based research has a neural net architecture as opposed to the von Neumann architecture of SSSR. This architecture is probably optimal, given library-based research's chief aim, which is less finding truth than filling a space of possible interpretations. From these various considerations it follows that faster is not necessarily better in library-based research, with obvious implications for library technologization. Other implications of this computational theory of library research are also explored.
Journal Prices, Book Acquisitions, and Sustainable College Library Collections
Authors: Walters William H.
Published: June 2014

Library collections are economically sustainable only if the rate of increase in costs is no greater than the rate of increase in the library acquisitions budget. Because book prices increase at a much lower rate than journal prices, undergraduate libraries can achieve economic sustainability through a renewed emphasis on books rather than journals. Book-centered collections are consistent with the goals of many undergraduate colleges, and books rather than journals may provide the best teaching resources even in those fields that rely heavily on journals for the communication of original research results.
Why Do We Teach? Adult Learning Theory in Professional Standards as a Basis for Curriculum Development
Authors: Gilstrap Donald L.
Published: June 2014

This article provides an overview of adult learning theory in relation to teaching philosophies among librarians belonging to ACRL, using Hadley’s Educational Orientation Questionnaire. Although not significant as a predictor, there was a nonlinear and negative correlation between librarians’ familiarity with the ACRL Standards and their adult learning orientation scores (p = .047, t < .05). Additional variables are included to investigate other influences on adult learning orientation scores. Results of the study showed high significance for gender (β = 0.213, p = 0.008), current library instruction (β = 0.199, p = 0.025), and the number of library instruction classes taught during the current year (β = 0.199, p = 0.041). Additional descriptive statistical analysis and qualitative responses are included, and propositions for professional development are then introduced for future discussions among the ACRL community about the importance of adult learning as well as the evolution of our teaching philosophies.
Making a Case for Technology in Academia
Authors: Dodds Kathrin , Callender Donell , Henry Cynthia
Published: June 2014

Interested in connecting users with the latest resources aimed at advancing intellectual inquiry and discovery, researchers from Texas Tech University Libraries decided to embark on a study to explore the practicality of the latest technology, the iPad, within the varying functions of academia. Using an online survey and focus groups, the researchers sought to investigate how students and faculty felt the iPad might be used in teaching and learning, as well as research. This article describes the process the researchers used to obtain iPads for research and how they explored their use in an academic setting.
Impulsivité et psychiatrie : de nouveaux outils pour mieux la définir, l’évaluer, la prévenir et la traiter
Authors: Joyal Christian C. , Dumais Alexandre
Published: June 2014

Bien que l’impulsivité soit l’une des manifestations les plus couramment rencontrées en psychiatrie et en psychologie clinique, elle demeure difficile à prévoir, à mesurer, à traiter, voire même à définir. Le principal objectif de cette conférence était de proposer une définition claire et opérationnelle du construit multidimensionnel de l’impulsivité, pour ensuite résumer les troubles mentaux qu’elle affecte et présenter des instruments de mesure plus sensibles susceptibles de faciliter l’évaluation psychiatrique au quotidien. Il s’agissait également de proposer l’utilisation en psychiatrie de techniques neurologiques peu coûteuses et faciles d’accès pour non seulement évaluer les risques d’impulsivité individuels, mais aussi pour les diminuer. Ces outils pourraient s’implanter dans tout milieu clinique et s’avérer complémentaires aux approches conventionnelles.
Do trypanosome turncoats wait before they commit?
Authors: Ooi Cher-Pheng , Rudenko Gloria
Published: June 2014

The strategy that sleeping sickness parasites use to evade the mammalian immune system may be linked to the metamorphosis that allows them to transfer from mammals into tsetse flies.
How do we walk and chew gum at the same time?
Authors: Morquette Philippe , Kolta Arlette
Published: June 2014

A genetic approach has been used to map the neural circuits that control and coordinate the tongue and jaw muscles.
High‐frequency imaging of elastic contrast and contact area with implications for naturally observed changes in fault properties
Authors: Nagata Kohei , Kilgore Brian , Beeler Nick , Nakatani Masao
Published: June 2014

During localized slip of a laboratory fault we simultaneously measure the contact area and the dynamic fault normal elastic stiffness. One objective is to determine conditions where stiffness may be used to infer changes in area of contact during sliding on nontransparent fault surfaces. Slip speeds between 0.01 and 10 µm/s and normal stresses between 1 and 2.5 MPa were imposed during velocity step, normal stress step, and slide‐hold‐slide tests. Stiffness and contact area have a linear interdependence during rate stepping tests and during the hold portion of slide‐hold‐slide tests. So long as linearity holds, measured fault stiffness can be used on nontransparent materials to infer changes in contact area. However, there are conditions where relations between contact area and stiffness are nonlinear and nonunique. A second objective is to make comparisons between the laboratory‐ and field‐measured changes in fault properties. Time‐dependent changes in fault zone normal stiffness made in stress relaxation tests imply postseismic wave speed changes on the order of 0.3% to 0.8% per year in the two or more years following an earthquake; these are smaller than postseismic increases seen within natural damage zones. Based on scaling of the experimental observations, natural postseismic fault normal contraction could be accommodated within a few decimeter wide fault core. Changes in the stiffness of laboratory shear zones exceed 10% per decade and might be detectable in the field postseismically.
Accurate tremor locations from coherent S and P waves
Authors: Armbruster John G. , Kim Won‐Young , Rubin Allan M.
Published: June 2014

Nonvolcanic tremor is an important component of the slow slip processes which load faults from below, but accurately locating tremor has proven difficult because tremor rarely contains clear P or S wave arrivals. Here we report the observation of coherence in the shear and compressional waves of tremor at widely separated stations which allows us to detect and accurately locate tremor events. An event detector using data from two stations sees the onset of tremor activity in the Cascadia tremor episodes of February 2003, July 2004, and September 2005 and confirms the previously reported south to north migration of the tremor. Event detectors using data from three and four stations give Sand P arrival times of high accuracy. The hypocenters of the tremor events fall at depths of ∼30 to ∼40 km and define a narrow plane dipping at a shallow angle to the northeast, consistent with the subducting plate interface. The S wave polarizations and P wave first motions define a source mechanism in agreement with the northeast convergence seen in geodetic observations of slow slip. Tens of thousands of locations determined by constraining the events to the plate interface show tremor sources highly clustered in space with a strongly similar pattern of sources in the three episodes examined. The deeper sources generate tremor in minor episodes as well. The extent to which the narrow bands of tremor sources overlap between the three major episodes suggests relative epicentral location errors as small as 1–2 km.
Self‐organization of the Earth's climate system versus Milankovitch‐Berger astronomical cycles
Authors: Maslov Lev A.
Published: June 2014

The Late Pleistocene Antarctic temperature variation curve is decomposed into two components: “cyclic” and “high frequency, stochastic.” For each of these components, a mathematical model is developed which shows that the cyclic and stochastic temperature variations are distinct, but interconnected, processes with their own self‐organization. To model the cyclic component, a system of ordinary differential equations is written which represent an auto‐oscillating, self‐organized process with constant period. It is also shown that these equations can be used to model more realistic variations in temperature with changing cycle length. For the stochastic component, the multifractal spectrum is calculated and compared to the multifractal spectrum of a critical sine‐circle map. A physical interpretation of relevant mathematical models and discussion of future climate development within the context of this work is given.
Photochemical Doping and Tuning of the Work Function and Dirac Point in Graphene Using Photoacid and Photobase Generators
Authors: Baltazar Jose , Sojoudi Hossein , Paniagua Sergio A. , Zhang Siyuan , Lawson Richard A. , Marder Seth R. , Graham Samuel , Tolbert Laren M. , Henderson Clifford L.
Published: June 2014

This work demonstrates that photochemical doping of CVD‐grown graphene can be easily achieved using photoacid (PAG) and photobase (PBG) generators such as triphenylsulfonium perfluoro‐1‐butanesufonate (TPS‐Nf) and 2‐nitrobenzyl N‐cyclohexylcarbamate (NBC). The TPS‐Nf ionic onium salt photoacid generator does not noticeably dope or alter the electrical properties of graphene when coated onto the graphene surface, but is very effective at inducing p‐doping of graphene upon exposure of the PAG‐coated graphene sample. Likewise, the neutral NBC photobase generator does not significantly affect the electrical properties of graphene when coated, but upon exposure to ultraviolet light produces a free amine, which induces n‐doping of the graphene. Electrical measurements show that the doping concentration can be modulated by controlling the deep ultraviolet (DUV) light exposure dose delivered to the sample. The interaction between both dopants and graphene is also investigated. The photochemical doping process is able to tune the work function of the single‐layer graphene samples used in this work from 3.4 eV to 5.3 eV. Finally, a p–n junction is fabricated and analyzed, showing that it is possible to control the position of the two current minima (two Dirac points) in the ambipolar p–n junction.
Multimodal Nanoprobes Evaluating Physiological Pore Size of Brain Vasculatures in Ischemic Stroke Models
Authors: Zheng Shuyan , Bai Ying‐Ying , Changyi Yinzhi , Gao Xihui , Zhang Wenqing , Wang Yuancheng , Zhou Lu , Ju Shenghong , Li Cong
Published: June 2014

Ischemic stroke accounts for 80% strokes and originates from a reduction of cerebral blood flow (CBF) after vascular occlusion. For treatment, the first action is to restore CBF by thrombolytic agent recombinant tissue‐type plasminogen activator (rt‐PA). Although rt‐PA benefits clinical outcome, its application is limited by short therapeutic time window and risk of brain hemorrhage. Different to thrombolytic agents, neuroprotectants reduce neurological injuries by blocking ischemic cascade events such as excitotoxicity and oxidative stress. Nano‐neuroprotectants demonstrate higher therapeutic effect than small molecular analogues due to their prolonged circulation lifetime and disrupted blood–brain barrier (BBB) in ischemic region. Even enhanced BBB permeability in ischemic territories is verified, the pore size of ischemic vasculatures determining how large and how efficient the therapeutics can pass is barely studied. In this work, nanoprobes (NPs) with different diameters are developed. In vivo multimodal imaging indicates that NP uptakes in ischemic region depended on their diameters and the pore size upper limit of ischemic vasculatures is determined as 10–11 nm. Additionally, penumbra defined as salvageable ischemic tissues performed a higher BBB permeability than infarct core. This work provides a guideline for developing nano‐neuroprotectants by taking advantage of the locally enhanced BBB permeability in ischemic brain tissues.
Conformationally Rigid Chiral Bicyclic Skeleton‐Tethered Bipyridine N,N′‐Dioxide as Organocatalyst: Asymmetric Ring Opening of meso‐Epoxides
Authors: Gnanamani Elumalai , Someshwar Nagamalla , Sanjeevi Jayakumar , Ramanathan Chinnasamy Ramaraj
Published: June 2014

The conformationally rigid chiral bicyclic skeleton tethered bipyridine N,N′‐dioxide (−)‐9 has been designed, synthesized and examined as an organocatalyst in the enantioselective ring opening of meso‐epoxides using tetrachlorosilane (SiCl4). The catalyst (−)‐9 is found to exhibit good enantioselectivity for substituted cis‐stilbene epoxides; whereas, the saturated cyclic meso‐epoxides display a moderate enantioselectivity. At −30 °C in chloroform, the catalyst (−)‐9 with 0.5 mol % loading generated the chlorohydrins in up to 97 % yield with up to 93 % ee. The possible creation of transient axial chiral environment around hypervalent silicon species due to the presence of conformationally rigid chiral bicyclic skeleton tethered bipyridine N,N′‐dioxide may be responsible for such enantioselectivity observed in the desymmetrization of meso‐epoxides.

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Developments in Eu+2‐Doped Strontium Aluminate and Polymer/Strontium Aluminate Composite
Authors: Anesh M. P. , Gulrez Syed K. H. , Anis A. , Shaikh H. , Ali Mohsin M. E. , AL‐Zahrani S. M.
Published: June 2014

The discovery of rare earth based phosphors in 1960s started a new era of luminescence. In comparison with sulfide‐based phosphors, strontium aluminates received worldwide acceptance because of their chemical stability and good luminescent properties. The SrAlxOy:Eu2+,Dy3+ phosphors excited by UV or visible light emit phosphorescence in the blue‐green region after the excitation source has been removed, and the phosphorescence last for more than 15 h. The major disadvantage of SrAlxOy:Eu2+,Dy3+ phosphors is that they are prone to hydrolysis and their luminescent properties gradually deteriorate. The dispersion of these phosphors in a waterproof polymer matrix is an alternative method reported for retaining their luminescent properties. The review extensively deals with strontium aluminate based luminescent materials, the mechanism of luminescence, their synthesis techniques, and different mixing procedures to prepare polymer/strontium aluminate composites. Different methods to improve the dispersion of the strontium aluminate in the polymer matrix are also outlined.
Optimal design of large‐scale chemical processes under uncertainty: A ranking‐based approach
Authors: Bahakim Sami S. , Rasoulian Shabnam , Ricardez‐Sandoval Luis A.
Published: June 2014

An approach for the optimal design of chemical processes in the presence of uncertainty was presented. The key idea in this work is to approximate the process constraint functions and model outputs using Power Series Expansions (PSE)‐based functions. The PSE functions are used to efficiently identify the variability in the process constraint functions and model outputs due to multiple realizations in the uncertain parameters using Monte Carlo (MC) sampling methods. A ranking‐based approach is adopted here where the user can assign priorities or probabilities of satisfaction for the different process constraints and model outputs considered in the analysis. The methodology was tested on a reactor–heat exchanger system and the Tennessee Eastman process. The results show that the present method is computationally attractive since the optimal process design is accomplished in shorter computational times when compared to the use of the MC method applied to the full plant model. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3243–3257, 2014
Durable superoleophobic fabric surfaces with counterintuitive superwettability for polar solvents
Authors: Pan Shuaijun , Guo Rui , Xu Weijian
Published: June 2014

Significance

Smart superoleophobic (SOP) cotton fabric surfaces are created only through a controlled fluorosilanization treatment, exhibiting the first‐ever extreme wetting behaviors displaying ultrarepellency to nonpolar oils and counterintuitive superwettability for all polar solvents. The smart durable SOP surfaces, demonstrated chemically, thermally, and mechanically, render great potential practical and industrial applications in robust oil shielding, effective antifouling, highly energy efficient self‐cleaning, and solely gravity‐driven oil–water separations. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2752–2756, 2014
Polymorphisms in cyclooxygenase‐2 gene and risk of developing coal workers' pneumoconiosis: A case–control study
Authors: Bian Lu‐Qin , Mao Ling , Shi Jin , Bi Ying
Published: June 2014

Background

Coal workers' pneumoconiosis (CWP) is characterized by progressive pulmonary fibrosis. Inflammation is crucial in the host response to silica and it contributes to pulmonary fibrosis. Cyclooxygenase‐2 is involved in this process. The association between single‐nucleotide polymorphisms in cyclooxygenase‐2 gene with pneumoconiosis risk was investigated.

Methods

An association study was conducted by analyzing two single‐nucleotide polymorphisms of cyclooxygenase‐2 (rs689466 and rs20417) in a case–control study involving 90 patients and 90 healthy individuals (controls). Genotyping was performed by the TaqMan method.

Results

The rs689466 AG and GG and rs689466 GC polymorphisms were significantly less frequent in patients than in controls. Cyclooxygenase‐2 rs689466 and rs20417 variant genotypes exhibited 21% and 12% decreased CWP risk, respectively.

Conclusion

Cyclooxygenase‐2 rs689466 and rs20417 polymorphisms were associated with CWP risk. Am. J. Ind. Med. 57:866–871, 2014. © 2014 Wiley Periodicals, Inc.
Maternal exposure to methotrexate and birth defects: A population‐based study
Authors: Dawson April L. , Riehle‐Colarusso Tiffany , Reefhuis Jennita , Arena J. Fernando ,   the National Birth Defects Prevention Study
Published: June 2014

Methotrexate is an anti‐folate medication that is associated with increased risk of multiple birth defects. Using data from the National Birth Defects Prevention Study, a case‐control study of major birth defects in the United States, we examined mothers exposed to methotrexate. The study population included mothers of live‐born infants without major birth defects (controls) and mothers of fetuses or infants with a major birth defect (cases), with expected dates of delivery between October 1997 and December 2009. Mothers of cases and controls were asked detailed questions concerning pregnancy history, demographic information, and exposures in a telephone interview. Approximately 0.06% (n = 16/27,623) of case and 0.04% (n = 4/10,113) of control mothers reported exposure to methotrexate between 3 months prior to conception through the end of pregnancy. Of the 16 case infants, 11 (68.8%) had a congenital heart defect (CHD). The observed CHDs included atrial septal defects, tetralogy of Fallot, valvar pulmonary stenosis, ventricular septal defects (VSDs), and total anomalous pulmonary venous return. One case infant had microtia in addition to a VSD and another had VACTER association. Exposed cases without a CHD had one of the following birth defects: cleft palate, hypospadias, congenital diaphragmatic hernia, or craniosynostosis. Based on a limited number of methotrexate‐exposed mothers, our findings support recent case reports suggesting an association between early pregnancy exposure to methotrexate and CHDs. Because of the rarity of maternal periconceptional exposure to methotrexate, long‐term, population‐based case‐control studies are needed to confirm these findings and better evaluate the association between methotrexate and birth defects. © 2014 Wiley Periodicals, Inc.
Significant Improvements in CO2 Capture by Pyridine‐Containing Anion‐Functionalized Ionic Liquids through Multiple‐Site Cooperative Interactions
Authors: Luo Xiaoyan , Guo Yan , Ding Fang , Zhao Hongqing , Cui Guokai , Li Haoran , Wang Congmin
Published: June 2014

A strategy for improving CO2 capture by new anion‐functionalized ionic liquids (ILs) making use of multiple site cooperative interactions is reported. An extremely high capacity of up to 1.60 mol CO2 per mol IL and excellent reversibility were achieved by introducing a nitrogen‐based interacting site on the phenolate and imidazolate anion. Quantum‐chemical calculations, spectroscopic investigations, and calorimetric data demonstrated that multiple‐site cooperative interactions between two kinds of interacting sites in the anion and CO2 resulted in superior CO2 capacities, which originated from the π‐electron delocalization in the pyridine ring.
Cytoprotective Silica Coating of Individual Mammalian Cells through Bioinspired Silicification
Authors: Lee Juno , Choi Jinsu , Park Ji Hun , Kim Mi‐Hee , Hong Daewha , Cho Hyeoncheol , Yang Sung Ho , Choi Insung S.
Published: June 2014

The cytoprotective coating of physicochemically labile mammalian cells with a durable material has potential applications in cell‐based sensors, cell therapy, and regenerative medicine, as well as providing a platform for fundamental single‐cell studies in cell biology. In this work, HeLa cells in suspension were individually coated with silica in a cytocompatible fashion through bioinspired silicification. The silica coating greatly enhanced the resistance of the HeLa cells to enzymatic attack by trypsin and the toxic compound poly(allylamine hydrochloride), while suppressing cell division in a controlled fashion. This bioinspired cytocompatible strategy for single‐cell coating was also applied to NIH 3T3 fibroblasts and Jurkat cells.
Über die Synthese von α‐Azidoestern und geminalen Triaziden
Authors: Klahn Philipp , Erhardt Hellmuth , Kotthaus Andreas , Kirsch Stefan F.
Published: June 2014

Drei einfache Methoden zur Synthese geminaler Triazide werden beschrieben: Ausgehend von 1) 3‐Oxocarbonsäuren, 2) Iodmethylketonen oder 3) terminalen Olefinen gelingt der Aufbau einer Reihe von Triazidomethylketonen unter milden, oxidativen Reaktionsbedingungen mit IBX‐SO3K, einem sulfonierten Derivat der 2‐Iodoxybenzoesäure (IBX), und NaN3 als Azidquelle. Von dieser neuen Verbindungsklasse sind bislang keine Mitglieder beschrieben. Die geminalen Triazide erweisen sich trotz ihres hohen Stickstoffgehalts auch in präparativen Mengen als unerwartet leicht handhabbar (Vorsicht: Explosionsgefahr besteht trotzdem!) und stehen nun erstmals in voller Breite für weitere Untersuchungen zu Reaktivität und Eigenschaften zur Verfügung. Darüber hinaus zeigen wir, wie mit dieser Methode α‐Azidoester, die als Bausteine für Aminosäuren fungieren können, gebildet werden.
Complex Reconfiguration of DNA Nanostructures
Authors: Wei Bryan , Ong Luvena L. , Chen Jeffrey , Jaffe Alexander S. , Yin Peng
Published: June 2014

Nucleic acids have been used to create diverse synthetic structural and dynamic systems. Toehold‐mediated strand displacement has enabled the construction of sophisticated circuits, motors, and molecular computers. Yet it remains challenging to demonstrate complex structural reconfiguration in which a structure changes from a starting shape to another arbitrarily prescribed shape. To address this challenge, we have developed a general structural‐reconfiguration method that utilizes the modularly interconnected architecture of single‐stranded DNA tile and brick structures. The removal of one component strand reveals a newly exposed toehold on a neighboring strand, thus enabling us to remove regions of connected component strands without the need to modify the strands with predesigned external toeholds. By using this method, we reconfigured a two‐dimensional rectangular DNA canvas into diverse prescribed shapes. We also used this method to reconfigure a three‐dimensional DNA cuboid.
Phosphine‐Directed CH Borylation Reactions: Facile and Selective Access to Ambiphilic Phosphine Boronate Esters
Authors: Crawford Kristina M. , Ramseyer Timothy R. , Daley Christopher J. A. , Clark Timothy B.
Published: June 2014

Ambiphilic ligands have received considerable attention over the last two decades due to their unique reactivity as organocatalysts and ligands. The iridium‐catalyzed CH borylation of phosphines is described in which the phosphine is used as a directing group to provide selective formation of arylboronate esters with unique scaffolds of ambiphilic compounds. A variety of aryl and benzylic phosphines were subjected to the reaction conditions, selectively providing stable, isolable boronate esters upon protection of the phosphine as the borane complex. After purification, the phosphine‐substituted boronate esters could be deprotected and isolated in pure form.
Asymmetrische Kaskadenreaktion zu Allylsulfonamiden aus Allylalkoholen über eine Palladium(II)/Base‐katalysierte Umlagerung von Allylcarbamaten
Authors: Bauer Johannes Moritz , Frey Wolfgang , Peters René
Published: June 2014

Eine regio‐ und enantioselektive Tandemreaktion, die leicht zugängliche achirale Allylalkohole direkt in chirale sulfonylgeschützte Allylamine überführt, wird beschrieben. Die Reaktion wird durch Kooperation eines chiralen Ferrocen‐Palladacyclus und einer tertiären Amin‐Base katalysiert und kombiniert hohe Stufenökonomie mit leichter Handhabung (ohne Inertgasatmosphäre oder Katalysatoraktivierung). Mechanistische Studien stützen eine PdII‐katalysierte [3,3]‐Umlagerung eines Allylcarbamats – in situ erzeugt aus einem Allylalkohol und einem Isocyanat – als Schlüsselschritt, dem eine Decarboxylierung folgt.
Biomimetic Polymers Responsive to a Biological Signaling Molecule: Nitric Oxide Triggered Reversible Self‐assembly of Single Macromolecular Chains into Nanoparticles
Authors: Hu Jinming , Whittaker Michael R. , Duong Hien , Li Yang , Boyer Cyrille , Davis Thomas P.
Published: June 2014

Novel nitric oxide (NO) responsive monomers (NAPMA and APUEMA) containing o‐phenylenediamine functional groups have been polymerized to form NO‐responsive macromolecular chains as truly biomimetic polymers. Upon exposure to NO—a ubiquitous cellular signaling molecule—the NAPMA‐ and APUEMA‐labeled thermoresponsive copolymers exhibited substantial changes in solubility, clearly characterized by tuneable LCST behavior, thereby inducing self‐assembly into nanoparticulate structures. Moreover, the NO‐triggered self‐assembly process in combination with environmentally sensitive fluorescence dyes could be employed to detect and image endogenous NO.
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

Es 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

The 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

Photochrome 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

Chirality 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

Difficulties 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

Die 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

The 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

The 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

We 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

Reported 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

The 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

40 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.