bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tuning the Guest‐Binding Ability of a Helically Folded Capsule by In Situ Modification of the Aromatic Oligoamide Backbone
Authors: Lautrette Guillaume , Aube Christophe , Ferrand Yann , Pipelier Muriel , Blot Virginie , Thobie Christine , Kauffmann Brice , Dubreuil Didier , Huc Ivan 
Published: January 2014

AbstractStarting from a previously described aromatic oligoamide helically folded capsule that binds tartaric acid with high affinity and diastereoselectivity, we demonstrate the feasibility of the direct in situ modification of the helix backbone, which results in a conformational change that reduces its affinity for guests by two orders of magnitude. Specifically, ring contraction of the central pyridazine unit into a pyrrole in the full helical sequence was investigated by using electrochemical and chemical processes. The sequence containing the pyrrole was synthesized independently in a convergent manner to ascertain its structure. The conformation of the pyrrolic folded capsule was elucidated in the solid state by X‐ray crystallography and in solution by using 1H and 13C NMR spectroscopy. Solution studies revealed an unanticipated solvent‐dependent equilibrium between the anti–anti and syn–syn conformations of the pyrrole ring with respect to its two adjacent pyridine units. Titrations of the pyrrole‐containing sequence monitored by 1H NMR spectroscopy confirmed the expected drop in affinity for tartaric acid and malic acid that arises from the conformation change in the backbone that follows the replacement of the pyridazine by a pyrrole. The reduction of the pyridazine to a pyrrole was characterized by cyclic voltammetry both on the entire sequence and on a shorter precursor. The lower cathodic potential of the precursor made its preparative‐scale electroreduction possible. Direct in situ modification of the pyridazine within the entire capsule sequence was achieved chemically by using zinc in acetic acid.
Folding‐Induced Folding: The Assembly of Aromatic Amide and 1,2,3‐Triazole Hybrid Helices
Authors: Wu Chun‐Fang , Li Zhi‐Ming , Xu Xiao‐Na , Zhao Zhi‐Xiong , Zhao Xin , Wang Ren‐Xiao , Li Zhan‐Ting 
Published: January 2014

AbstractFolding‐induced folding for the construction of artificial hybrid helices from two different kinds of aromatic sequences is described. Linear compounds 1 a, 1 b, and 2, containing one aromatic amide trimer or pentamer and one or two aromatic 1,2,3‐triazole tetramers, have been designed and synthesized. The trimeric and pentameric amide segments are driven by intramolecluar NH⋅⋅⋅F hydrogen bonding to adopt a folded or helical conformation, whereas the triazole segment is intrinsically disordered. In organic solvents of low polarity, the amide foldamer segment induces the attached triazole segment(s) to fold through intramolecular stacking, leading to the formation of hybrid helices. The helical conformation of these hybrid sequences has been confirmed by 1H and 19F NMR spectroscopy, UV/Vis spectroscopy, circular dichroism (CD) experiments, and theoretical calculations. It was found that the amide pentamer exhibits a stronger ability to induce the folding of the attached triazole segment(s) compared with that of the shorter trimer. Enantiomers (R)‐3 and (S)‐3, which contain an R‐ or S‐(1‐naphthyl)ethylamino group at the end of a tetraamide segment, have also been synthesized. CD experiments showed that introduction of a chiral group caused the whole framework to produce a strong helicity bias. Density‐functional‐theory calculations on (S)‐3 suggested that this compound exists as a right‐handed (P) helix.
Label‐Free Measurements of the Diffusivity of Molecules in Lipid Membranes
Authors: Johansson Björn , Höök Fredrik , Klenerman David , Jönsson Peter 
Published: January 2014

AbstractAn important and characteristic property of a cell membrane is the lateral mobility of protein molecules in the lipid bilayer. This has conventionally been measured by labeling the molecules with fluorescent markers and monitoring their mobility by different fluorescence‐based techniques. However, adding the label to the studied molecule may affect the system, so it is an assumption in almost all experiments that the measured mobility of the biomolecule with its label is the same as that of the unlabeled molecule. However, this assumption is rarely tested due to a lack of suitable methods. In this work, a new technique to perform label‐free diffusivity measurements is developed and used to measure the effect of the label for two common protein–lipid systems: 1) streptavidin (SA) coupled to a supported lipid bilayer (SLB) through biotinylated lipids and 2) the extracellular part of the T‐cell adhesion protein CD2, coupled to an SLB through histidine tags to nickel‐chelating lipids. A measurable (≈12 %) decrease in diffusivity is found for both labeled proteins, even though the molecular mass of the label is almost 100 times smaller than those of the proteins (≈50 kDa). The results illustrate the importance of being able to study different biophysical properties of cell membranes and their mimics without relying on fluorescent labels, especially if fluorescent labeling is difficult or is expected to affect the nature of the intermolecular interactions being studied.
Synthesis, Characterization, and Crystal Structures of Scorpionate Complexes with the Hydrotris[3‐(2′‐thienyl)pyrazol‐1‐yl]borate Ligand
Authors: Pettinari Claudio , Marchetti Fabio , Orbisaglia Serena , Palmucci Jessica , Pettinari Riccardo , Di Nicola Corrado , Skelton Brian W. , White Allan H. 
Published: January 2014

AbstractSix scorpionate complexes of group 10–12 metal elements (CuI, CuII, ZnII, and CdII) containing the anionic hydrotris[3‐(2′‐thienyl)pyrazol‐1‐yl]borate (TpTn) ligand were prepared from the reaction of the thallium(I) salt of TpTn with the corresponding metal acceptors in chloroform solution. The air‐ and heat‐stable complexes were characterized by analytical and spectroscopic methods (IR, conductivity, ESI‐MS, 1H NMR and 13C NMR solution data) and structurally characterized by single‐crystal X‐ray studies. The ZnII complexes [Zn(TpTn)X] (X = Cl or Br) contain a tripodal tridentate TpTn ligand, in which the tetrahedral metal environment is completed by a halide; in [Cd(TpTn)2], cadmium is found in an octahedral environment coordinated by two TpTn ligands. In [Cu(TpTn)(PPh3)]·CHCl3 and [Cu(TpTn)(OC(O)CH3)], TpTn is also coordinated in the tripodal fashion, in which the copper environment is completed by a triphenylphosphine ligand in the former complex and by a symmetrically coordinated bidentate acetate ligand occupying trans‐coordinated sites in the latter complex. The reaction of [Zn(TpTn)X] with an excess amount of [Tl(TpTn)] in MeOH yielded [Zn(TpTn)2] and TlX, whereas the reaction of [Zn(TpTn)X] with Na(Tp) gave [Zn(TpTn)2] and [Zn(Tp)2] in a 1:1 molar ratio but not [Zn(TpTn)(Tp)]. By contrast, the reaction of [Tl(TpTn)] with copper(II) sulfate monohydrate in chloroform gave a green powder, which was identified as the [(Hpz3Tn)4CuSO4](∞|∞) coordination polymer containing OSO2O bridging sulfate groups and four coordinated pyrazole ligands on each metal center, the latter of which arises from the decomposition of the TpTn ligand through B–N bond breaking. Similarly, the interaction between [Tl(TpTn)] and platinum(II) diiodide in chloroform/DMSO proceeded through TpTn decomposition to afford a monomeric trans‐[(Hpz3Tn)2PtI2]·2(CH3)2SO complex, wherein two neutral pyrazole ligands are coordinated to the PtII center.
A Metal‐Mediated Base Pair with a [2+1] Coordination Environment
Authors: Richters Tim , Müller Jens 
Published: January 2014

AbstractA silver(I)‐mediated base pair based on azole‐derived ligands only was devised. The base pair comprises the monodentate imidazole nucleoside and a nucleoside carrying the new bidentate ligand 4‐[(1H‐1,2,4‐triazol‐1‐yl)methyl]‐1H‐1,2,3‐triazole. The silver(I) ion is hence coordinated in a trigonal planar [2+1] environment. A representative DNA duplex comprising the new base pair is stabilized by 6 °C upon binding one equivalent of silver(I). CD spectroscopy was used to confirm that the duplex adopts the canonical B‐type conformation. The base pair represents the first example of a metal‐mediated base pair with a [2+1] coordination environment.
Differential Functionalization of 1,6‐Naphthyridin‐2(1H)‐ones through Sequential One‐Pot Suzuki–Miyaura Cross‐Couplings
Authors: Montoir David , Tonnerre Alain , Duflos Muriel , Bazin Marc‐Antoine 
Published: January 2014

AbstractA practical synthesis of 7‐chloro‐3‐iodo‐1‐methyl‐1,6‐naphthyridin‐2(1H)‐one is described that starts from 2‐chloro‐4‐(methylamino)nicotinaldehyde. The dihalo compound then undergoes sequential, site‐selective Suzuki–Miyaura cross‐coupling reactions to afford highly functionalized 1,6‐naphthyridones in good yields.
Hazardous processes and events from glacier and permafrost areas: lessons from the Chilean and Argentinean Andes
Authors: Iribarren Anacona Pablo , Mackintosh Andrew , Norton Kevin Patrick 
Published: January 2014

ABSTRACTGlacier and permafrost hazards such as glacial‐lake outburst floods and rock–ice avalanches cause significant socio‐economic damages worldwide, and these processes may increase in frequency and magnitude if the atmospheric temperature rises. In the extratropical Andes nearly 200 human deaths were linked to these processes during the twentieth century. We analysed bibliographical sources and satellite images to document the glacier and permafrost dynamics that have caused socio‐economic damages in this region in historic time (including glacial lake outburst floods, ice and rock–ice avalanches and lahars) to unravel their causes and geomorphological impacts. In the extratropical Andes, at least 15 ice‐dammed lakes and 16 moraine‐dammed lakes have failed since the eighteenth century, causing dozens of floods. Some floods rank amongst the largest events ever recorded (5000 × 106 m3 and 229 × 106 m3, respectively). Outburst flood frequency has increased in the last three decades, partially as a consequence of long‐term (decades to centuries) climatic changes, glaciers shrinkage, and lake growth. Short‐term (days to weeks) meteorological conditions (i.e. intense and/or prolonged rainfall and high temperature that increased meltwater production) have also triggered outburst floods and mass movements. Enormous mass failures of glaciers and permafrost (> 10 × 106 m3) have impacted lakes, glaciers, and snow‐covered valleys, initiating chain reactions that have ultimately resulted in lake tsunamis and far‐reaching (> 50 km) flows. The eruption of ice‐covered volcanoes has also caused dozens of damaging lahars with volumes up to 45 × 106 m3. Despite the importance of these events, basic information about their occurrence (e.g. date, causes, and geomorphological impact), which is well established in other mountain ranges, is absent in the extratropical Andes. A better knowledge of the processes involved can help to forecast and mitigate these events. Copyright © 2014 John Wiley & Sons, Ltd.
Identification of the Active Sites for Low Temperature CO Oxidation over Nanocrystalline Co3O4 Catalysts
Authors: Liu Chang‐Xiang , Liu Qian , Huang Xi‐Gen , Nie Xu‐Liang , Huang Zhong 
Published: January 2014

AbstractThe microstructural properties of dry‐grinding derived Co3O4 catalysts pretreated under different atmospheres, in relation to the activities on CO oxidation were investigated. The Co3O4 synthesized by soft reactive grinding and pretreated with O2 resulted in the best activity, with 100% conversion of CO at −52 °C, superior to that of Co3O4 pretreated with He. To find out the active sites on Co3O4 for low temperature CO oxidation, the characterizations of the cobalt oxides had been investigated by means of N2 physisorption, XRD, TEM, H2‐TPR, CO‐titration, XPS and O2‐TPD technologies. XPS of Co2p results show that it is difficult to ascribe the difference in catalytic performance to the surface concentration of active Co3+ sites. A correlation between the activity and the CO‐titration and O2‐TPD results for Co3O4 reveals that a high abundance of readily accessible superficial electrophilic oxygen (O−) species is important for achieving a high activity. Therefore, CO oxidation takes place on the surface active oxygen sites in Co3O4 crystallites via the suprafacial mechanism.
Gadolinium‐free extracellular MR contrast agent for tumor imaging
Authors: Nofiele Joris Tchouala , Haedicke Inga E. , Zhu Yong Le K. , Zhang Xiao‐an , Cheng Hai‐Ling Margaret 
Published: January 2014

PurposeTo evaluate a new formulation of manganese porphyrin as a potential gadolinium (Gd)‐free extracellular magnetic resonance imaging (MRI) contrast agent for dynamic contrast‐enhanced (DCE) MRI of tumors.Materials and MethodsA previously reported new contrast agent, MnTCP, was evaluated in six female tumor‐bearing nude rats. MRI was performed on a 3 T clinical scanner 3 to 4 weeks after inoculation of breast tumor cells in the mammary fat pads. Gd‐DTPA was injected intravenously, followed by injection of MnTCP at least 2 hours later (both at 0.05 mmol/kg). T1 relaxation time measurements and DCE‐MRI were performed.ResultsEnhancement and clearance patterns were visually similar between MnTCP and Gd‐DTPA. However, relative R1 increases in all 11 tumors were larger for MnTCP over 60 minutes postcontrast, the difference being significant as late as 20 minutes (R1post/R1pre = 1.42 ± 0.15 for MnTCP vs. 1.20 ± 0.08 for Gd‐DTPA, P < 0.05). R1‐related effects for MnTCP were largely reduced after 60 minutes (R1post/R1pre = 1.13 ± 0.07) and completely gone within 24 hours (R1post/R1pre = 0.97 ± 0.06). DCE‐MRI revealed a consistently larger (1.5 to over 2‐fold) peak enhancement and higher values of the steepest slope, time‐to‐peak, and AUC60 in all tumors with MnTCP (P < 0.01).ConclusionMnTCP is an alternative to extracellular Gd agents for tumor imaging, offering sensitive detection and rapid renal clearance. J. Magn. Reson. Imaging 2015;41:397–403.© 2013 Wiley Periodicals, Inc.
Acid Resistance in Francisella tularensis
Authors: Adcock Noreen J. , Morris Brian J. , Rice Eugene W. 
Published: January 2014

AbstractFrancisella tularensis, the etiologic agent of tularemia, can survive under acidic conditions. Tularemia can be acquired by several routes, including by ingestion of contaminated food or water. While acid resistance is usually associated with a low oral infective dose (ID), the ID for gastrointestinal illness is quite high. In this study, four strains of F. tularensis ssp. tularensis (type A) and four strains of F. tularensis ssp. holarctica (type B) were examined for innate acid resistance and the ability to survive in synthetic gastric fluid (SGF) under in vitro conditions similar to passage through the human stomach. Survival for all strains was significantly less in pH 2.5 SGF than in pH 2.5 phosphate‐buffered saline and pH 4.0 SGF. Attenuated strains were consistently less resistant. Type B strains are most often associated with waterborne outbreaks and were examined after storage in natural water. Low‐nutrient preadaptation resulted in increased resistance. Although F. tularensis can persist under certain acidic conditions, it is sensitive to conditions replicating the fasting human stomach. This may help explain the high ID required for gastrointestinal infections.
Nonlinear model predictive control for path following problems
Authors: Yu Shuyou , Li Xiang , Chen Hong , Allgöwer Frank 
Published: January 2014

SummaryThis paper presents a general nonlinear model predictive control scheme for path following problems. Path following problem of nonlinear systems is transformed into a parameter‐dependent regulation problem. Sufficient conditions for recursive feasibility and asymptotic convergence of the given scheme are presented. Furthermore, a polytopic linear differential inclusion‐based method of choosing a suitable terminal penalty and the corresponding terminal constraint are proposed. To illustrate the implementation of the nonlinear model predictive control scheme, the path following problem of a car‐like mobile robot is discussed, and the control performance is confirmed by simulation results. Copyright © 2014 John Wiley & Sons, Ltd.
Robust nonlinear H ∞  control based on the incremental gain
Authors: Beikzadeh Hossein , Marquez Horacio J. 
Published: January 2014

SummaryThe incremental gain is proposed as an alternative to the usual gain for designing nonlinear H ∞  controllers. Considering a class of plants with Lipschitz nonlinearities and using linear matrix inequalities, a state feedback controller is designed such that the closed‐loop system is exponentially stable in the absence of disturbance inputs and has incremental gain less than or equal to a minimized number in the presence of disturbances as well as model uncertainties. Moreover, a norm‐wise robustness analysis of the proposed technique against nonlinear uncertainties has been accomplished. Our result is verified through stabilization of both certain and uncertain systems in an incremental sense and also input tracking of a chaotic plant. Copyright © 2014 John Wiley & Sons, Ltd.
A mobile phone‐based physical‐social location proof system for mobile social network service
Authors: Ni Xudong , Luo Junzhou , Zhang Boying , Teng Jin , Bai Xiaole , Liu Bo , Xuan Dong 
Published: January 2014

AbstractLocation‐related mobile social network services are popular nowadays, and their methods to obtain end users’ location information are based on people's self‐report location claims, using mobile devices to check positions and send them back to the service providers. However, this mechanism has a serious vulnerability that makes malicious users be able to access restricted resource by transmitting fake locations. Both academic and industrial researchers are recently aware of this problem's importance since the commercialized trend of location‐related mobile social network services. To address this issue, we propose mobile phone‐based physical‐social location, a mobile phone‐based location proof system to verify users’ location claims and defend various fake location information. Our core idea is that a user's location claim can be proved by a set of selective physical encountered people serving as “witnesses” who are co‐located with him/her in that area. The system is composed of proof generation and verification. In the proof generation phase, we leverage a certain number of co‐located people to generate certificates as location proofs during their encounters via bluetooth interface. In the verification phase, we propose an efficient verification scheme to make our system accurate and adaptive. We have implemented the MPSL system using real world Nokia N82 (Nokia, Espoo, Finland) phones. Our experimental results show that our mobile phone‐based system can achieve high verification accuracy and good performance. Copyright © 2014 John Wiley & Sons, Ltd.
Comparison of urine and self‐collected vaginal samples for detecting human papillomavirus DNA in pregnant women
Authors: Franciscatto Laura G. , Silva Cláudia M.D. , Barcellos Regina B. , Angeli Suelen , Silva Márcia S.N. , Almeida Sabrina E.M. , Rossetti Maria L.R. 
Published: January 2014

AbstractObjectiveTo investigate the utility of urine sampling for detecting human papillomavirus (HPV) DNA among pregnant women and to compare HPV DNA detection in urine with detection in vaginal samples.MethodsIn a cross‐sectional study, urine and vaginal samples were self‐collected from pregnant women attending prenatal care at Hospital Divina Providencia, Frederico Westphalen, Brazil, between October 2006 and August 2007. Part of the L1 region of the HPV genome was amplified via GP5+/bioGP6+ primers. Positive urine was genotyped for high‐risk HPV genotypes (HPV16, HPV18, HPV31, HPV33, HPV39, HPV45, and HPV59).ResultsDuring the study period, urine samples were obtained from 133 pregnant women, 63 of whom also self‐collected vaginal samples. HPV DNA was detected in 54.0% (34/63) and 61.9% (39/63) of urine and vaginal samples, respectively. HPV infection was significantly associated with first intercourse at younger than 20 years of age (P = 0.008). There was substantial agreement in HPV DNA test results between the urine and vaginal samples (κ value, 77.3%; P < 0.0001). HPV31 and HPV16 accounted for 80.7% of the oncogenic types identified.ConclusionDetection of HPV DNA in urine showed good agreement with detection in self‐collected vaginal samples, indicating that urine might be a reliable sample for HPV testing among pregnant women.
Obstetric complications and cesarean delivery in Nepal
Authors: Karkee Rajendra , Lee Andy H. , Khanal Vishnu , Pokharel Paras K. , Binns Colin W. 
Published: January 2014

AbstractObjectiveTo determine the incidence of obstetric complications, the stillbirth rate, and the factors associated with cesarean delivery in central Nepal.MethodsA community‐based prospective cohort study was undertaken in the Kaski district during 2011–2012. In total, 701 women who were at least 5 months pregnant were recruited and interviewed. Participants were followed‐up and interviewed again within 45 days after delivery.ResultsOf the 658 women who remained in the cohort after 43 were lost to follow‐up, 12 (1.8%) had stillbirths. Cesareans accounted for 13.3% of the total deliveries. Age, urban residency, college‐level education, and particularly presence of intrapartum symptoms significantly increased the likelihood of cesarean delivery. Prepartum, intrapartum, and postpartum symptoms were reported by 21.1%, 24.4%, and 10.2% of women, respectively. Common danger signs included prolonged labor, severe abdominal pain, swollen hand and body, and heavy bleeding.ConclusionObstetric complications and stillbirth rates were relatively high in central Nepal. Cesarean delivery appeared to meet obstetric need and was performed with medical indication, particularly after the onset of labor.
Idols in the Archive
Authors: Asif Manan Ahmed 
Published: January 2014

Is a circumcision, for example, an exterior mark? Is it an archive?Let me begin at the beginning.My left eyebrow has a scar. It is jagged, and usually the droop of the eyebrow hides it from view. I see it sometimes when I look in the mirror. When I see it, I am reminded instantly of my father. He was sitting, reading a newspaper, on the lawn of our Lahore house. It was near to 6:00 p.m.—late evening to dusk. I had recently conquered the art of biking and I was eager to show him how well I rode. I kept going past him on the bike, but he was engrossed in the paper. Finally I decided that to really get his attention, I would need to go really, really fast. I went a ways, and began to pedal furiously. Right as I gathered full speed and came up to him, I looked at him to see if he was watching me. He wasn't. That split second, however, was enough for me to lose control of the bike, which swerved radically to the left, and I went face-first into a column of bricks. He looked up as I stumbled up, my eye covered in blood. I have no memory of this, except for when I “see” my scar.
On the Importance of Golden Parachutes
Authors: Fich Eliezer M. , Tran Anh L. , Walkling Ralph A. 
Published: January 2014

AbstractIn acquisitions, target chief executive officers (CEOs) face a moral hazard: Any personal gain from the deal could be offset by the loss of the future compensation stream associated with their jobs. Larger, more important parachutes provide greater relief for these losses. To explicitly measure the moral hazard target CEOs face, we standardize the parachute payment by the expected value of their acquisition-induced lost compensation. We examine 851 acquisitions from 1999–2007, finding that more important parachutes benefit target shareholders through higher completion probabilities. Conversely, as parachute importance increases, target shareholders receive lower takeover premia, while acquirer shareholders capture additional rents from target shareholders.