bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frequency Interval Cross Gramians for Linear and Bilinear Systems
Authors: Jazlan Ahmad , Sreeram Victor , Shaker Hamid Reza , Togneri Roberto , Minh Ha Binh 
Published: May 2016

AbstractIn many control engineering problems, it is desired to analyze the systems at particular frequency intervals of interest. This paper focuses on the development of frequency interval cross gramians for both linear and bilinear systems. New generalized Sylvester equations for calculating the frequency interval cross gramians are derived in order to be used to obtain information regarding controllability and observability within a single matrix. The advantage of the proposed method is that it is computationally more efficient compared to existing gramian‐based techniques since only half of the number of equations need to be solved in order to obtain information regarding the controllability and observability of a system compared to existing techniques. Numerical examples are provided to demonstrate the computational efficiency of the proposed method which uses frequency interval cross gramians relative to existing methods.
Redundant Input Safety Tracking for Omnidirectional Rehabilitative Training Walker with Control Constraints
Authors: Sun Ping , Wang Shuoyu 
Published: May 2016

AbstractThis study proposes a nonlinear safety tracking method based on redundant degrees of freedom with control constraints to protect against actuator faults that may occur in robotic rehabilitative walkers. A redundant input model with uniform actuator faults is constructed by separating the corresponding columns of the control matrix, and an adaptive robust control method is presented to deal with the separated term that is considered in relation to the extrinsic bounded interference that occurs on robotic walker systems. Based on the backstepping technique, an adjustable control law can be designed to maintain stability in terms of solving linear matrix inequality. The trajectory tracking error performance and the velocity tracking error performance are derived simultaneously. As an application, simulation results confirm the effectiveness of the proposed method and verify that the walker can provide safe sequential motions even when one wheel actuator fails.
The side‐chain hydroxy groups of a cyclic α,α‐disubstituted α‐amino acid promote oligopeptide 310‐helix packing in the crystalline state
Authors: Demizu Yosuke , Doi Mitsunobu , Yamashita Hiroko , Misawa Takashi , Oba Makoto , Kurihara Masaaki , Suemune Hiroshi , Tanaka Masakazu 
Published: May 2016

AbstractA single chiral cyclic α,α‐disubstituted amino acid with side‐chain methoxymethyl (MOM) protecting groups, (3S,4S)−1‐amino‐(3,4‐dimethoxymethoxy)cyclopentanecarboxylic acid [(S, S)‐Ac5cdOMOM], or side‐chain hydroxy groups, (3S,4S)−1‐amino‐(3,4‐dihydroxy)cyclopentanecarboxylic acid [(S, S)‐Ac5cdOH], was attached to the N‐terminal or C‐terminal position of α‐aminoisobutyric acid (Aib) tetrapeptide segments; i.e., we designed and synthesized four pentapeptides, Cbz‐[(S, S)‐Ac5cdOMOM]‐(Aib)4‐OEt (1), Cbz‐[(S, S)‐Ac5cdOH]‐(Aib)4‐OEt (2), Cbz‐(Aib)4‐[(S, S)‐Ac5cdOMOM]‐OMe (3), and Cbz‐(Aib)4‐[(S, S)‐Ac5cdOH]‐OMe (4). We then analyzed the peptides’ structures in the crystalline state. The four peptides all folded into 310‐helical structures; 1 formed a left‐handed (M) 310‐helix, 2 formed a mixture of right‐handed (P) and (M) 310‐helices, 3 formed a mixture of (P) and (M) 310‐helices, and 4 formed a (P) 310‐helix, respectively. In packing mode, the molecules of peptides 1 and 3, which both possessed an Ac5cdOMOM residue, were connected by intermolecular hydrogen bonds along the peptide backbone (NH···O type). On the other hand, the packing of peptides 2 and 4, which both contained an Ac5cdOH residue, was based on intermolecular hydrogen bonds derived from both the peptide backbone and the side‐chain hydroxy groups of the amino acid Ac5cdOH (OH···O type). © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 757–768, 2016.
A Selective Na+ Aptamer Dissected by Sensitized Tb3+ Luminescence
Authors: Zhou Wenhu , Ding Jinsong , Liu Juewen 
Published: May 2016

AbstractA previous study of two RNA‐cleaving DNAzymes, NaA43 and Ce13d, revealed the possibility of a common Na+ aptamer motif. Because Na+ binding to DNA is a fundamental biochemical problem, the interaction between Ce13d and Na+ was studied in detail by using sensitized Tb3+ luminescence spectroscopy. Na+ displaces Tb3+ from the DNAzyme, and thus quenches the emission from Tb3+. The overall requirement for Na+ binding includes the hairpin and the highly conserved 16‐nucleotide loop in the enzyme strand, along with a few unpaired nucleotides in the substrate. Mutation studies indicate good correlation between Na+ binding and cleavage activity, thus suggesting a critical role of Na+ binding for the enzyme activity. Ce13d displayed a Kd of ∼20 mm with Na+ (other monovalent cations: 40–60 mm). The Kd values for other metal ions are mainly due to non‐specific competition. With a single nucleotide mutation, the specific Na+ binding was lost. Another mutant improved Kd to 8 mm with Na+. This study has demonstrated a Na+ aptamer with important biological implications and analytical applications. It has also defined the structural requirements for Na+ binding and produced an improved mutant.
PEGylated Cationic Serum Albumin for Boosting Retroviral Gene Transfer
Authors: Palesch David , Boldt Felix , Müller Janis A. , Eisele Klaus , Stürzel Christina M. , Wu Yuzhou , Münch Jan , Weil Tanja 
Published: May 2016

AbstractRetroviral vectors are common tools for introducing genes into the genome of a cell. However, low transduction rates are a major limitation in retroviral gene transfer, especially in clinical applications. We generated cationic human serum albumin (cHSA) protected by a shell of poly(ethylene glycol) (PEG); this significantly enhanced retroviral gene transduction with potentially attractive pharmacokinetics and low immunogenicity. By screening a panel of chemically optimized HSA compounds, we identified a very potent enhancer that boosted the transduction rates of viral vectors. Confocal microscopy revealed a drastically increased number of viral particles attached to the surfaces of target cells. In accordance with the positive net charge of cationic and PEGylated HSA, this suggests a mechanism of action in which the repulsion of the negatively charged cellular and viral vector membranes is neutralized, thereby promoting attachment and ultimately transduction. Importantly, the transduction‐enhancing PEGylated HSA derivative evaded recognition by HSA‐specific antibodies and macrophage activation. Our findings hold great promise for facilitating improved retroviral gene transfer.
Methylene blue toxicity in zebrafish cell line is dependent on light exposure
Authors: Costa Simone Rutz da , Monteiro Mauricio da Costa , da Silva Júnior Flavio Manoel Rodrigues , Sandrini Juliana Zomer 
Published: May 2016

AbstractMethylene blue (MB) has been widely applied in the clinical area and is currently being used in aquaculture as biocide. Some recent studies have emphasized the importance of understanding the action mechanism and the MB cellular targets. In this sense, zebrafish is considered a relevant model to study the intrinsic pathway of apoptosis as well as the cellular responses involving DNA damage and repair. So, the aim of the present study was to compare MB action mechanisms in a zebrafish cell line, both in the absence (MB alone; dark toxicity) and in the presence of photosynthetically active radiation (MB+PAR; phototoxicity). There was a significant increase of the levels of reactive oxygen and nitrogen species 3 h after MB treatment, whereas this increase was only observed 12 h after treatment with MB+PAR. All treatments with MB resulted in an increase in DNA damage after 3 and 6 h. However, cell death by apoptosis was observed from 6 h after treatment with MB+PAR and 12 h after treatment with MB alone. The expression of genes related to apoptosis was altered after MB and MB+PAR treatment. Therefore, this zebrafish cell line is sensitive to the photodynamic action of MB; MB is able to generate DNA damage and induce apoptosis in this cell line both alone and in the presence of PAR. However, the pathways leading to apoptosis in this model appear to be dependent on the type of MB exposure (in the presence or absence of PAR).
Vinylic Addition Polynorbornene as Support for N‐Heterocyclic Carbene Palladium Complexes: Use as Reservoir of Active Homogeneous Catalytic Species in C−C Cross‐Coupling Reactions
Authors: Molina de la Torre Jesús A. , Albéniz Ana C. 
Published: May 2016

AbstractA vinylic addition polynorbornene (VA‐PNB) functionalized with imidazolium groups can be used to synthesize a well‐defined supported palladium carbene complex. This complex is a suitable precatalyst for Suzuki and Negishi cross‐coupling reactions, and it can be reused. A close look at how the catalysis works reveals that palladium aggregates form on the polymer surface after the first catalytic reaction. However, they are not easily washed out and serve as a source of small amounts of homogeneous palladium active species (about 0.01% mol), which are responsible for the catalysis. The recovered polymer can be reused several times although increased induction and reaction times are observed in consecutive uses from one run to the next. The reaction was followed up by in situ IR spectroscopy by using the ν(C−Br) absorption band of the electrophile, so there is no need for an additional functional group to apply this technique.
Porous Graphitic Carbon Nitride Derived from Melamine–Ammonium Oxalate Stacking Sheets with Excellent Photocatalytic Hydrogen Evolution Activity
Authors: Li Kui , Xie Xin , Zhang Wei‐De 
Published: May 2016

AbstractA facile strategy to synthesize porous graphitic carbon nitride with stacking nanotubes by thermal condensation of melamine–ammonium oxalate stacking sheets is reported. The photocatalytic generation rate of hydrogen over the porous graphitic carbon nitride (99.7 μmol h−1) is nearly 9.5 times as that of pristine g‐C3N4 (10.5 μmol h−1). Such enhancement is attributed to the large specific surface area (91.1 m2 g−1), improved visible‐light absorption and efficient separation of photogenerated electrons and holes. The strategy of preparing the porous graphitic carbon nitride with modified melamine as a precursor opens a new gate for the regulation of the morphologies of g‐C3N4 to get higher photocatalytic activity.
Synthesis of Oxazolidinones from Epoxides and Isocyanates Catalysed by Aluminium Heteroscorpionate Complexes
Authors: Castro‐Osma José A. , Earlam Amy , Lara‐Sánchez Agustín , Otero Antonio , North Michael 
Published: May 2016

AbstractThe combination of an aluminium(heteroscorpionate) complex and tetrabutylammonium bromide acts as a highly efficient catalyst system for the synthesis of oxazolidinones from epoxides and isocyanates. Twenty two complexes were tested derived from a range of bispyrazole ligands and containing 1–3 aluminium atoms per complex. The optimal catalyst was found to be a bimetallic complex of a thioacetamidate ligand. Under the optimal reaction conditions (80 °C in toluene for 24 h using 5 mol % of both aluminium catalyst and tetrabutylammonium bromide co‐catalyst), six epoxides were reacted with six aromatic isocyanates, giving 25 oxazolidinones in moderate to excellent yields showing broad substrate scope. The regiochemistry of the reaction (to produce 3,4‐ or 3,5‐oxazolidinones) is controlled by the substrate with epoxide ring opening occurring preferentially at the less hindered end of the epoxide unless a substituent on the epoxide can stabilise a positive charge.
Effect of Hydrodynamic Forces onmeso‐(4‐Sulfonatophenyl)‐Substituted Porphyrin J‐Aggregate Nanoparticles: Elasticity, Plasticity and Breaking
Authors: El‐Hachemi Zoubir , Balaban Teodor Silviu , Campos J. Lourdes , Cespedes Sergio , Crusats Joaquim , Escudero Carlos , Kamma‐Lorger Christina S. , Llorens Joan , Malfois Marc , Mitchell Geoffrey R. , Tojeira Ana P. , Ribó Josep M. 
Published: May 2016

AbstractThe J aggregates of 4‐sulfonatophenylmeso‐substituted porphyrins are non‐covalent polymers obtained by self‐assembly that form nanoparticles of different morphologies. In the case of high aspect‐ratio nanoparticles (bilayered ribbons and monolayered nanotubes), shear hydrodynamic forces may modify their shape and size, as observed by peak force microscopy, transmission electron microscopy of frozen solutions, small‐angle X‐ray scattering measurements in a disk‐plate rotational cell, and cone–plate rotational viscometry. These nanoparticles either show elastic or plastic behaviour: there is plasticity in the ribbons obtained upon nanotube collapse on solid/air interfaces and in viscous concentrated nanotube solutions, whereas elasticity occurs in the case of dilute nanotube solutions. Sonication and strong shear hydrodynamic forces lead to the breaking of the monolayered nanotubes into small particles, which then associate into large colloidal particles.
Active Esters as Pseudostoppers for Slippage Synthesis of [2]Pseudorotaxane Building Blocks: A Straightforward Route to Multi‐Interlocked Molecular Machines
Authors: Legigan Thibaut , Riss‐Yaw Benjamin , Clavel Caroline , Coutrot Frédéric 
Published: May 2016

AbstractThe efficient synthesis and very easy isolation of dibenzo[24]crown‐8‐based [2]pseudorotaxane building blocks that contain an active ester motif at the extremity of the encircled molecular axle and an ammonium moiety as a template for the dibenzo[24]crown‐8 is reported. The active ester acts both as a semistopper for the [2]pseudorotaxane species and as an extensible extremity. Among the various investigated active ester moieties, those that allow for the slippage process are given particular focus because this strategy produces fewer side products. Extension of the selected N‐hydroxysuccinimide ester based pseudorotaxane building block by using either a mono‐ or a diamino compound, both containing a triazolium moiety, is also described. These provide a pH‐dependent two‐station [2]rotaxane molecular machine and a palindromic [3]rotaxane molecular machine, respectively. Molecular machinery on both interlocked compounds through variation of pH was studied and characterized by means of NMR spectroscopy.
Postoperative Strokes and Intracranial Bleeds in Patients With Atrial Fibrillation: The FibStroke Study
Authors: Palomäki Antti , Kiviniemi Tuomas , Hartikainen Juha E.K. , Mustonen Pirjo , Ylitalo Antti , Nuotio Ilpo , Hartikainen Päivi , Jaakkola Jussi , Luite Riho , Airaksinen K.E. Juhani 
Published: May 2016

ABSTRACTBackgroundPatients with atrial fibrillation (AF) frequently undergo invasive procedures. Optimal perioperative use of oral anticoagulation (OAC) and heparin bridging is not well defined.HypothesisDiscontinuation of OAC for minor procedures/operations places AF patients at risk for thromboembolism.MethodsIn this study, we assessed perioperative antithrombotic treatment in patients with AF who suffered a postoperative stroke or intracranial bleeding. The FibStroke Study includes AF patients with an ischemic stroke or intracranial bleed identified from the discharge registries of 4 Finnish hospitals. In total, 3632 consecutive patients developed 3252 ischemic strokes and 794 intracranial bleeds. All invasive procedures during the 30 days preceding the stroke or intracranial bleed were identified.ResultsA total of 194/3252 (6.0%) ischemic strokes and 23/794 (2.9%) intracranial bleeds were preceded by a procedure. Altogether, 69% of the patients were on OAC prior to index procedure, OAC was interrupted in 81.2% of the procedures preceding a stroke, and heparin bridging was used in 27.8% of interruptions. Of the procedures leading to stroke, 42.3% were low‐bleeding‐risk procedures, and OAC was interrupted in 84.7% of these procedures. The median time from procedure to stroke was 4 days. Heparin bridging was used in 54.5% of OAC interruptions preceding intracranial bleeding and combination of anticoagulation with antiplatelet therapy by 43.5% of patients with postoperative intracranial bleeding.ConclusionsPerioperative interruption of OAC is common in patients who suffer a postoperative stroke, even in patients with low‐bleeding‐risk procedures. Postoperative intracranial bleeding is frequently preceded by perioperative heparin bridging.
α‐Fluoro‐o‐cresols: The Key Role of Intramolecular Hydrogen Bonding in Conformational Preference and Hydrogen‐Bond Acidity
Authors: Bogdan Elena , Quarré de Verneuil Alexis , Besseau François , Compain Guillaume , Linclau Bruno , Le Questel Jean‐Yves , Graton Jérôme 
Published: May 2016

AbstractThe conformational preferences of o‐cresols driven by fluorination were thoroughly investigated from a theoretical point of view with quantum‐chemical methods, and the results were compared to those recently reported for benzyl alcohols. The key conformers of both families exhibit a six‐membered intramolecular hydrogen‐bond (IMHB) interaction. A significant enhancement in the strength of the IMHB is observed in α‐fluoro‐o‐cresols, owing to a simultaneous increase in the hydrogen bond (HB) basicity of the aliphatic fluorine and the HB acidity of the aromatic hydroxyl relative to that observed for o‐fluorobenzyl alcohols, which are characterized by aromatic fluorine atoms and aliphatic hydroxyl groups. In the cases of the di‐ and trifluorinated derivatives, the occurrence of a three‐centered HB is emphasized, and its features are discussed. The impact of these structural predilections on the HB properties of o‐cresol was characterized from the estimation of the HB acidity parameter, pKAHY, weighted according to their conformational populations. We found that α‐fluorination led to a decrease in the HB acidity of the hydroxyl group (in contrast with the o‐fluorination of benzyl alcohols), whereas α,α‐difluorination resulted in no significant variation in pKAHY. Finally, an increase in the HB acidity was predicted upon methyl perfluorination, which was confirmed experimentally. Theoretical descriptors based on atoms in molecules, noncovalent interactions, and natural bond orbital analyses allowed rationalization of the predicted trends and revealed a relationship with the strength of the established OH⋅⋅⋅F IMHB.
Alternative Single‐Solvent Electrolytes Based on Cyanoesters for Safer Lithium‐Ion Batteries
Authors: Brox Sebastian , Röser Stephan , Husch Tamara , Hildebrand Stephan , Fromm Olga , Korth Martin , Winter Martin , Cekic‐Laskovic Isidora 
Published: May 2016

AbstractTo identify alternative single‐solvent‐based electrolytes for application in lithium‐ion batteries (LIBs), adequate computational methods were applied to screen specified physicochemical and electrochemical properties of new cyanoester‐based compounds. Out of 2747 possible target compounds, two promising candidates and two structurally equivalent components were chosen. A constructive selection process including evaluation of basic physicochemical properties as well assessing the compatibility towards graphitic anodes was initiated to identify the most promising candidates. With addition of a film‐forming additive in a low concentration, the most promising candidate showed an adequate long‐term cycling stability with LiNi1/3Mn1/3Co1/3O2 [NMC(111)] in a full‐cell setup using graphite as anode material. The main advantages of the new electrolyte formulation are related to its good thermal behavior, especially with regard to safety in combination with satisfying electrochemical performance.
Asymptotic design of quantization and bit allocation for distributed estimation in wireless sensor networks
Authors: Chen Junyong , Shen Zhiping , Zhong Jun 
Published: May 2016

SummaryThis paper investigates the schemes of asymptotically optimal quantization and bit allocation for distributed estimation in wireless sensor networks in which a total bit rate constraint is imposed. Because there is no communication among all sensors, quantizers for observations need to be designed separately. The Lloyd‐Max quantizer is shown to be asymptotically optimal for each sensor. Moreover, it is shown that the level number of asymptotically optimal quantization for sensors is proportional to the signal‐to‐noise ratio, which is determined by the variances of observation and noise. Because the original quantized minimum mean‐square error estimator often corresponds to a high computational cost when a large number of sensors are active, in our work, an asymptotically equivalent algorithm of iterative quantized estimator (IQE), which enjoys a low computational cost, is proposed. In addition, an IQE algorithm can be applied to wireless sensor networks with delay or packet loss. Simulation results of this work indicate that the effectiveness of our IQE algorithm is obvious; that is, a significant improvement of estimation performance is achieved by using the optimal bit allocation when comparing with the uniform bit allocation. Copyright © 2016 John Wiley & Sons, Ltd.
Association between severity of hypoglycemia and loss of heart rate variability in patients with type 1 diabetes mellitus
Authors: Silva Ticiana Paes , Rolim Luiz Clemente , Sallum Filho Celso , Zimmermann Livia M. , Malerbi Fernando , Dib Sergio Atala 
Published: May 2016

AbstractBackgroundThe occurrence of hypoglycemia has been associated with the presence of cardiovascular autonomic neuropathy. Cardiovascular autonomic reflex tests are the gold standard diagnostic method for cardiovascular autonomic neuropathy. Nevertheless, impaired heart rate variability indices on spectral analysis have been reported before cardiovascular autonomic reflex test abnormalities arise. The objective of the present study was to analyse the association between the severity of hypoglycemia and indices of heart rate variability on spectral analysis.MethodsConsecutive type 1 diabetes patients were prospectively enrolled. Heart rate variability indices were assessed by spectral analysis. One abnormal test result was used to define impaired spectral analysis. The severity of hypoglycemia was evaluated by a hypoglycemia score and patients were classified into absent/minor or moderate/severe hypoglycemia groups.ResultsPatients with moderate/severe hypoglycemia were older, had longer duration of diabetes and had higher rates of diabetic complications. After adjusting for baseline clinical characteristics, impaired spectral analysis (OR: 3.85; 95% IC 1.23 – 12.02; p = 0.020), nephropathy (OR: 4.15, 95% IC 1.27 – 13.54; p = 0.018) and macrovascular complications (OR: 12.18, 95% IC 1.14 – 129.84; p = 0.038) remained independent predictors of moderate/severe hypoglycemia. Patients with moderate/severe hypoglycemia had lower heart rate variability in the high frequency band of spectral analysis, reflecting a decreased parasympathetic tonus on the heart. These patients also had higher low frequency/high frequency ratios, ultimately denoting the occurrence of cardiovascular autonomic imbalance.ConclusionsImpaired heart rate variability on spectral analysis, nephropathy and macrovascular complication were shown to independently predict moderate/severe hypoglycemia. Patients with moderate/severe hypoglycemia showed loss of the cardio protective effect of vagal activity according to spectral analysis. Copyright © 2016 John Wiley & Sons, Ltd.