bluuebunny/crossref_metadata_2025_split huggingface dataset:
Halogen, Chalcogen, and Pnicogen Bonding Involving Hypervalent Atoms
Authors: Scheiner Steve , Lu Jia 
Published: March 2018

AbstractThe additional substituents arising from hypervalency present a number of complicating issues for the formation of noncovalent bonds. The XF5molecule (X=Cl, Br, I) was allowed to form a halogen bond with NH3as the base. Hypervalent chalcogen bonding is examined by way of YF4and YF6(Y=S, Se, Te), and ZF5(Z=P, As, Sb) is used to model pnicogen bonding. Pnicogen bonds are particularly strong, with interaction energies approaching 50 kcal mol−1, and also involve wholesale rearrangement from trigonal bipyramidal in the monomer to square pyramidal in the complex, subject to a large deformation energy. YF4chalcogen bonding is also strong, and like pnicogen bonding, is enhanced by a heavier central atom. XF5halogen bond energies are roughly 9 kcal mol−1, and display a unique sensitivity to the identity of the X atom. The crowded octahedral structure of YF6permits only very weak interactions. As the F atoms of SeF6are replaced progressively by H, a chalcogen bond appears in combination with SeH⋅⋅⋅N and NH⋅⋅⋅F H‐bonds. The strongest such chalcogen bond appears in SeF3H3⋅⋅⋅NH3, with a binding energy of 7 kcal mol−1, wherein the base is located in the H3face of the Lewis acid. Results are discussed in the context of the way in which the positions and intensities of σ‐holes are influenced by the locations of substituents and lone electron pairs.
An Improved Approach to the Direct Construction of 2‐Deoxy‐β‐Linked Sugars: Applications to Oligosaccharide Synthesis
Authors: Lloyd Dina , Bennett Clay S. 
Published: March 2018

AbstractA next‐generation reagent‐controlled approach for the synthesis of 2,6‐dideoxy and 2,3,6‐trideoxy sugar donors in good yield and high β‐selectivity is reported. The use of p‐toluenesulfonyl chloride and potassium hexamethyldisilazide (KHMDS) greatly simplifies deoxy‐sugar glycoside construction, and can be used for gram‐scale glycosylation reactions. The development of this approach and its application to the construction of β‐linked deoxy‐sugar oligosaccharides are described.
Synthesis and Structure of a Stable Bis(methylene)‐λ4‐sulfane
Authors: Sugamata Koh , Hashizume Daisuke , Suzuki Yuko , Sasamori Takahiro , Ishii Shigeru 
Published: March 2018

AbstractBis(methylene)‐λ4‐sulfane 1, a >C=S=C< heterocumulene, was obtained as a red crystalline solid from the reaction between elemental sulfur and a carbenoid that contains sterically demanding silylalkyl groups. Under atmospheric conditions, and even at elevated temperatures, 1 exhibits extraordinary stability. The molecular structure and electron‐density distribution of 1 were analyzed by single‐crystal X‐ray diffraction analysis, which revealed a bent C=S=C geometry with C=S=C π‐bonds. These results, combined with those of variable‐temperature NMR measurements and theoretical calculations suggest a slow rotation of the S=C moieties in 1, the stability and structure of which were further examined by theoretical calculations.
Bioinspired Design of Fe3+‐Doped Mesoporous Carbon Nanospheres for Enhanced Nanozyme Activity
Authors: Sang Yanjuan , Huang Yanyan , Li Wei , Ren Jinsong , Qu Xiaogang 
Published: March 2018

AbstractNanozymes have received considerable attention as alternatives of natural enzymes. However, the catalytic activity of nanozymes is often lower than that of natural enzymes, which largely limits their applications. Current methods utilized to improve the catalytic efficiency and substrate selectivity of a nanozyme usually have some inherent drawbacks. Herein, a biomimetic strategy was developed to design Fe3+‐doped mesoporous carbon nanospheres (Fe3+‐MCNs) as a horseradish peroxidase (HRP) mimic to realize the structure and function mimicking of natural HRP. In this system, Fe3+ ions could act as catalytic centers and carboxyl‐modified mesoporous carbon nanospheres (MCNs‐COOH) could be used to bind with substrates. As a result, Fe3+‐MCNs showed higher enzymatic activity than that of Fe3O4 nanoparticles. Therefore, this strategy can contribute to the development of nanozymes and further understanding of the complicated enzymatic reactions in natural and biological systems.
Self‐Assembled Bright Luminescent Lanthanide‐Organic Polyhedra for Ratiometric Temperature Sensing
Authors: Guo Xiao‐Qing , Zhou Li‐Peng , Cai Li‐Xuan , Sun Qing‐Fu 
Published: March 2018

AbstractLuminescent lanthanide‐containing compounds have a lot of stimulating applications. However, the fine‐tuning of the optical properties of multi‐nuclear lanthanide edifices is still a big challenge. We report here the coordination self‐assembly of a group of bright luminescent lanthanide organic polyhedra (LOPs) with record high emission quantum yields, by using two fully‐conjugated ligands featuring the triazole‐pyridine‐amido (tpa) chelating moiety, easily‐accessible from the “Click” reaction. The self‐assembled LOPs are characterized by NMR spectroscopy, high‐resolution ESI‐TOF‐MS, and X‐ray crystallography. Interestingly, inter‐metal energy transfer (ET) is confirmed on the mixed‐lanthanide polyhedral molecules, though the metal centers are separated nearly 2 nm apart. A feasible ratiometric luminescent thermometer, with work range from cryogenic to physiological temperatures, has been demonstrated with the mixed Eu/Tb LOPs. We envisage these molecular‐level bright luminescent LOPs have great application potential in displaying, labelling/imaging, up‐conversion materials etc.
Nonvolatile Tri‐State Resistive Memory Behavior of a Stable Pyrene‐Fused N‐Heteroacene with Ten Linearly‐Annulated Rings
Authors: Li Yang , Zhang Cheng , Gu Peiyang , Wang Zilong , Li Zhengqiang , Li Hua , Lu Jianmei , Zhang Qichun 
Published: March 2018

AbstractThe diverse functionalities of large N‐heteroacenes continue to be developed in terms of their strategic synthesis and application in the organic electronic field. Here, we report a novel large stable pyrene‐containing N‐heteroacene with ten linearly‐annulated rings in one row. Remarkably, it exhibited excellent tri‐state resistive memory property, which held great promise to achieve ultrahigh‐density data storage. To the best of our knowledge, it is the first demonstration of organic multistate memory device based on large N‐heteroacene (n≥10), which provides guidelines for designing more proof‐of‐concept larger N‐heteroacene‐based memory electronics.
A Facile Synthesis of Blue Luminescent [7]Helicenocarbazoles Based on Gold‐Catalyzed Rearrangement‐Iodonium Migration and Suzuki–Miyaura Benzannulation Reactions
Authors: Alcaide Benito , Almendros Pedro , Aragoncillo Cristina , Busto Eduardo , López‐Calixto Carmen G. , Liras Marta , de la Peña O'Shea Víctor A. , García‐Sánchez Alba , Stone Hannah V. 
Published: March 2018

AbstractNew azahelicenes having interesting photophysical properties have been prepared in a four‐step sequence. These [7]helicenocarbazoles are efficient blue luminophores, demonstrating the utility of gold catalysis in the preparation of advanced materials.
Iridium‐Catalyzed Aerobic Coupling of Salicylaldehydes with Alkynes: A Remarkable Switch of Oxacyclic Product
Authors: Yamane Shintaro , Hinoue Tomoaki , Usuki Yoshinosuke , Itazaki Masumi , Nakazawa Hiroshi , Hayashi Yoshihiro , Kawauchi Susumu , Miura Masahiro , Satoh Tetsuya 
Published: March 2018

AbstractThe iridium(III)/copper(II)‐catalyzed dehydrogenative coupling of salicylaldehydes with internal alkynes proceeds efficiently under atmospheric oxygen through aldehyde C−H bond cleavage and decarbonylation. A variety of benzofuran derivatives can be synthesized by the environmentally benign procedure. DFT calculations suggest that this unique transformation involves the facile deinsertion of CO in the key metallacycle intermediate, which is in marked contrast to the corresponding rhodium(III) catalysis that leads to CO‐retentive chromone derivatives.
5‐Aza‐7‐deaza‐2′‐deoxyguanosine and 2′‐Deoxycytidine Form Programmable Silver‐Mediated Base Pairs with Metal Ions in the Core of the DNA Double Helix
Authors: Guo Xiurong , Leonard Peter , Ingale Sachin A. , Liu Jiang , Mei Hui , Sieg Martha , Seela Frank 
Published: March 2018

Abstract5‐Aza‐7‐deaza‐2′‐deoxyguanosine (dZ) forms a silver‐mediated base pair with dC. The metal ion pair represents a mimic of the H‐bonded Watson–Crick dG‐dC pair. The modified nucleoside displays a similar shape as the parent 2′‐deoxyguanosine from which it can be constructed by transposition of nitrogen‐7 to the bridgehead position‐5. It lacks the major groove binding site as the positional change moves the dG‐ acceptor position from nitrogen‐7 to nitrogen‐1. As a shape mimic of dG, it fits nicely in the DNA double helix. The purine–pyrimidine dZ‐dC hetero pair shows a relationship to the pyrimidine–pyrimidine dC‐dC homo base pair. The dZ‐dC pair forms a mismatch in the absence of silver ions and matches after addition of metal ions. Base‐pair formation was verified on self‐complementary 6‐mer duplexes and 12‐mer DNA with random composition by UV‐dependent Tm measurements. Modified silver‐mediated and hydrogen‐bonded canonical base pairs can coexist. The dZ‐Ag+‐dC base pair is slightly less stable than the dG‐dC pair, shows sequence dependence, and consumes one or two silver ions. These properties make the dZ‐Ag+‐dC pair suitable for programmable incorporation of silver ions in DNA which cannot be achieved by canonical base pairs. If the silver ion content is higher than the total number of base pairs the duplexes turn into very stable structures in which all base pairs are considered to be in the silver‐mediated pairing mode.
Total Synthesis of Lapidilectine B Enabled by Manganese(III)‐Mediated Oxidative Cyclization of Indoles
Authors: Gao Yang , Fan Mengyang , Geng Qixiang , Ma Dawei 
Published: March 2018

AbstractA novel manganese(III)‐mediated oxidative cyclization of readily accessible 1,2,3‐trisubstituted indoles is described. This unprecedented method enabled the efficient construction of a complex polycyclic scaffold bearing a spiro‐indoline motif and a lactone moiety in one step. Its synthetic utility was demonstrated in the total synthesis of lapidilectine B (in 18 steps) by employing a strategic regioselective ring‐expansion and a silver‐promoted allenic amine cyclization as the additional key elements.
Solvent polarity effects on supramolecular chirality of a polyfluorene‐thiophene copolymer
Authors: Hirahara Takashi , Yoshizawa‐Fujita Masahiro , Takeoka Yuko , Rikukawa Masahiro 
Published: March 2018

AbstractThis study demonstrates the supramolecular chirality control of a conjugated polymer via solvent polarity. We designed and synthesized a chiral polyfluorene‐thiophene copolymer having two different chiral side chains at the 9‐position of the fluorene unit. Chiral cyclic and alkyl ethers with different polarities were selected as the chiral side chains. The sign of the circular dichroism spectra in the visible wavelength region was affected by the solvent system, resulting from the change of supramolecular structure. The estimation of the solubility parameter revealed that the solubility difference of the side chains contributed to the change of the circular dichroism sign, which was also observed in spin‐coated films prepared from good solvents having different polarities.
Functional characterization of salt‐tolerant microbial esterase WDEst17 and its use in the generation of optically pure ethyl (R)‐3‐hydroxybutyrate
Authors: Wang Yilong , Xu Yongkai , Zhang Yun , Sun Aijun , Hu Yunfeng 
Published: March 2018

AbstractThe two enantiomers of ethyl 3‐hydroxybutyrate are important intermediates for the synthesis of a great variety of valuable chiral drugs. The preparation of chiral drug intermediates through kinetic resolution reactions catalyzed by esterases/lipases has been demonstrated to be an efficient and environmentally friendly method. We previously functionally characterized microbial esterase PHE21 and used PHE21 as a biocatalyst to generate optically pure ethyl (S)‐3‐hydroxybutyrate. Herein, we also functionally characterized one novel salt‐tolerant microbial esterase WDEst17 from the genome of Dactylosporangium aurantiacum subsp. Hamdenensis NRRL 18085. Esterase WDEst17 was further developed as an efficient biocatalyst to generate (R)‐3‐hydroxybutyrate, an important chiral drug intermediate, with the enantiomeric excess being 99% and the conversion rate being 65.05%, respectively, after process optimization. Notably, the enantio‐selectivity of esterase WDEst17 was opposite than that of esterase PHE21. The identification of esterases WDEst17 and PHE21 through genome mining of microorganisms provides useful biocatalysts for the preparation of valuable chiral drug intermediates.
Prediction of Product Yields for Different Reactor Types in Catalytic Pyrolysis
Authors: Engelhardt Armin , Stam‐Creutz Timo , Hahn Thomas , Seitz Mathias 
Published: March 2018

AbstractFür den Wandel hin zu einer postfossilen Gesellschaft werden rohstoffvariable Verfahren wie die katalytische Pyrolyse von festen Kohlenwasserstoffen benötigt. Zur Vorhersage der Produktausbeute aus unterschiedlichen Einsatzstoffen wurden Modellansätze entwickelt, die Rohstoffqualität, Katalysatoreigenschaften und Prozessbedingungen berücksichtigen. Eine gute Beschreibung für die stoffliche Nutzung von Braunkohle ist mit wenigen Einflussgrößen und signifikanten Modellparametern möglich. Perspektivisch sollen solche Modelle auf die Spaltung polyolefinischer Rezyklate und fettreiche Biomassen übertragen werden.
Generational Differences in the Importance, Availability, and Influence of Work Values: A Public Service Perspective
Authors: Smith Christopher , Halinski Michael , Gover Laura , Duxbury Linda 
Published: March 2018

AbstractThis study uses a sample of 832 Canadian public servants to test a theoretically derived framework which hypothesizes that generational cohort: (1) predicts the importance public servants place on intrinsic and extrinsic work values, (2) predicts the perceived availability of such rewards in public service workplaces, and (3) impacts the relationship between perceived availability of important rewards, organizational commitment, and job satisfaction. Our study adds to the limited body of research on generational cohort and work values in the public service. Generational cohort had little impact on the importance of work values, but did predict perceived availability of work‐rewards and the relationship between perceived availability of important rewards, organizational commitment, and job satisfaction. Findings could help public service organizations' recruitment and retention efforts. Copyright © 2018 ASAC. Published by John Wiley & Sons, Ltd.
Design of internal model control dead‐time compensation scheme for first order plus dead‐time systems
Authors: Pathiran Arun R. , Jagadeesan Prakash 
Published: March 2018

AbstractInternal model control (IMC) is a well‐known model‐based control structure that has additional dead‐time compensation (DTC), while PID is the popularly‐implemented control structure due to its simple structure, ease of implementation, and satisfactory performance at a wide range of operating conditions. Therefore, IMC‐based PID tuning methods are introduced to include the benefits of IMC in PID. Approximations involved in the existing IMC‐based PID tuning methods for specific types of transfer function models result in performance degradation. The IMC structure can be rearranged to the form of a standard PID type controller without approximation, which retains good servo performance for time delay processes. On the other hand, the presence of a time delay element in the controller structure makes the loop highly sensitive to dead‐time variations. Thus, the sensitivity of the IMC scheme realized in the PID structure is studied based on the conventional Nyquist stability criterion. It is observed that the high sensitivity is due to the occurrence of multiple interaction points of the Nyquist curve of the loop transfer function and unit circle. Besides, the number of the interaction points is relative to the ratio of loop dead‐time to closed loop time constant. Further, it is shown that the occurrence of multiple interaction points can be avoided by the right choice of closed loop time constant. The performance and robustness of the proposed design approach is confirmed via simulation analysis.
Y zeolite equilibrium catalyst waste from fluidized catalytic cracking regenerated by electrokinetic treatment: An adsorbent for sulphur and nitrogen compounds
Authors: de Oliveira Thamayne Valadares , Valt Renata Bachmann Guimarães , de Araújo Ponte Haroldo , de Santana Ponte Maria José Jerônimo , Yamamoto Carlos Itsuo , de Souza Antônio Augusto Ulson , de Arruda Guelli Ulson de Souza Selene Maria 
Published: March 2018

AbstractThe adsorption of sulphur, nitrogen, and aromatic compounds on a regenerated equilibrium catalyst (ecat‐R) was studied using model and real diesel fuels. The ecat‐R was obtained by electrokinetic treatment of an equilibrium catalyst (Y zeolites) waste from fluidized catalytic cracking (FCC) units. The studied model diesel fuel contained dibenzothiophene (1039 mg/L), quinoline (600 mg/L), and naphthalene (600 mg/L), as models for sulphur, nitrogen, and aromatic compounds, respectively, in n‐decane as solvent. The ecat‐R was characterized using X‐ray diffraction, X‐ray fluorescence, N2 adsorption‐desorption, thermogravimetric and differential thermal analysis, scanning electron microscopy, Fourier‐transform infrared spectroscopy, and granulometry. The adsorption experiments were performed at 40 °C and 150 rpm. The results of the isotherm and a chemical kinetics studies were favourable; the material showed a high adsorption capacity for dibenzothiophene (2.8 mg S/g) and quinoline (6.3 mg N/g). The isotherm for naphthalene was less favourable (2 mg NAP/g). The process rapidly reached equilibrium in approximately 2 h. For real diesel fuel, the adsorption removal was 26 % for sulphur and 36 % for nitrogen.
Goodness‐of‐fit tests for Lévy‐driven Ornstein‐Uhlenbeck processes
Authors: Abdelrazeq Ibrahim , Ivanoff B. Gail , Kulik Rafal 
Published: March 2018

AbstractLévy‐Driven Ornstein‐Uhlenbeck (or CAR(1)) processes have been introduced in the literature as a model for stochastic volatility. A general formula to recover the unobserved driving process from a continuously observed CAR(1) was developed. When the CAR(1) process is observed at discrete times, the driving process must be approximated. Approximated increments of the driving process are used to test the hypothesis that the CAR(1) belongs to a specified class of Lévy processes. Two goodness‐of‐fit tests are proposed. The performance of the tests is illustrated through simulation. The Canadian Journal of Statistics 46: 355–376; 2018 © 2018 Statistical Society of Canada
Laserinduzierte Fluoreszenz von Iod in der Gasphase
Authors: Dege Janina , Zeuch Thomas , Waitz Thomas 
Published: March 2018

AbstractDie Fluoreszenz von Festkörpern und Flüssigkeiten ist ein weitläufig bekanntes Phänomen, das unter anderem auch im Alltag beobachtet werden kann. In diesem Versuch wird gezeigt, dass auch Stoffe in der Gasphase zu einer Fluoreszenz angeregt werden können – am Beispiel von gasförmigen Iod. Diese, durch grünes Laserlicht induzierte faszinierende Fluoreszenzentstehung sowie deren ‐löschung, können dabei anhand eines didaktisch angepassten Energiestufenmodell im fortgeschrittenen Chemieunterricht anschaulich erarbeitet werden. Darüber hinaus ermöglicht das Experiment viele Anknüpfungspunkte zu den grundlegenden Themen des Chemie‐ und Physikunterrichts wie Absorption, Emission, Strahlungs‐ sowie Energieübergänge
Efficient GPU‐based implementation for decoding non‐binary LDPC codes with layered and flooding schedules
Authors: Liu Zhanxian , Liu Rongke , Hou Yi , Peng Hao , Zhao Ling 
Published: March 2018

SummaryNonbinary low‐density parity‐check (NB‐LDPC) codes are excellent error correcting codes and outperform their binary counterparts under the same code length. NB‐LDPC decoders are based on Belief Propagation Algorithm, which demands intensive message‐passing computation. Recently, to achieve both flexibility and good throughput performance, NB‐LDPC decoders have been ported from dedicated hardware solutions to multi/many‐core systems. In this paper, we propose an FFT‐based q‐ary Sum‐Product Algorithm (QSPA) decoding architecture for NB‐LDPC codes with layered and flooding schedules on a graphics processing unit (GPU). To improve the throughput performance of the proposed decoder, four optimization methods are presented to not only accelerate the decoding kernel execution but also improve the data transfer efficiency. The experiments are mainly accomplished on NVIDIA GTX580 and GTX Titan X. Throughputs up to 63 Mbps over GF(16) and 7.65 Mbps over GF(256) are achieved on GTX580 when executing 5 layered decoding iterations. Throughputs can reach up to 139 Mbps over GF(16) and17 Mbps over GF(256) on GTX Titan X. Experimental results show that the speedups of the decoding throughputs range from ×1.7 to ×16.8 by comparison with the existing FFT‐based QSPA decoders on GPU.
Self‐learning and self‐adaptive resource allocation for cloud‐based software services
Authors: Chen Xing , Lin Junxin , Lin Bing , Xiang Tao , Zhang Ying , Huang Gang 
Published: March 2018

SummaryIn the presence of scale, dynamism, uncertainty, and elasticity, cloud engineers face several challenges when allocating resources for cloud‐based software services. They should allocate appropriate resources in order to guarantee good quality of services as well as low cost of resources. Self‐adaptive ability is needed in this process because engineers' intervention is difficult. Traditional self‐adaptive resource allocation methods are policy‐driven. Thus, cloud engineers usually have to develop separate sets of rules for each systems in order to allocate resources effectively, which leads to high administrative cost and implementation complexity. Machine learning has made great achievements in many fields, and it can be also applied to resource allocation. In this paper, we present a self‐learning and self‐adaptive approach to resource allocation for cloud‐based software services. For a given cloud‐based software service, its QoS model is firstly trained on history data, which is capable to predict the QoS value as output by using the information on workload and allocated resources as inputs. Then, on‐line decision‐making on resource allocation can be carried out automatically based on genetic algorithm, which is aimed to search reasonable resource allocation plan by using the QoS model. We evaluate our approach on RUBiS benchmark, demonstrating the accuracy of the QoS model over 90% and the improvement of resource utilization by 10%‐30%.