bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Fluorescence Lifetime Imaging Microscopy (FLIM) Data
Authors: Pande P. , Trivedi C. A. , Jo J. A. 
Published: July 2010

Summary
Objectives: A novel Fluorescence Lifetime Imaging Microscopy (FLIM) deconvolution method based on the linear expansion of fluorescence decays on a set of orthonormal Laguerre functions was recently proposed. The Laguerre deconvolution method applies linear least-square estimation to estimate the expansion coefficients of all pixel decays simultaneously, performing at least two orders of magnitude faster than the other algorithms. In the original Laguerre FLIM deconvolution implementation, however, the Laguerre parameter α is selected using a heuristic approach, making it unsuitable for online applications.
Methods: In this study, we present a fully automated implementation of the Laguerre FLIM deconvolution, whereby the Laguerre parameter α is treated as a free parameter within a nonlinear least-squares optimization scheme.
Results: The performance of this method has been successfully validated on simulated data, and experimental FLIM images of standard fluorescent dyes and endogenous tissue fluorescence.
Conclusions: The main advantage of the proposed method is that it does not require any user intervention for tuning up the deconvolution process. Thus, we believe this method will facilitate the translation of FLIM to online applications, including real-time clinical diagnosis.
Investigation of an Automatic Sleep Stage Classification by Means of Multiscorer Hypnogram
Authors: Helland V. C. , Gapelyuk A. , Suhrbier A. , Riedl M. , Penzel T. , Kurths J. , Wessel N. 
Published: July 2010

Summary
Objectives: Scoring sleep visually based on polysomnography is an important but time-consuming element of sleep medicine. Whereas computer software assists human experts in the assignment of sleep stages to polysomnogram epochs, their performance is usually insufficient. This study evaluates the possibility to fully automatize sleep staging considering the reliability of the sleep stages available from human expert sleep scorers.
Methods: We obtain features from EEG, ECG and respiratory signals of polysomnograms from ten healthy subjects. Using the sleep stages provided by three human experts, we evaluate the performance of linear discriminant analysis on the entire polysomnogram and only on epochs where the three experts agree in their sleep stage scoring.
Results: We show that in polysomnogram intervals, to which all three scorers assign the same sleep stage, our algorithm achieves 90% accuracy. This high rate of agreement with the human experts is accomplished with only a small set of three frequency features from the EEG. We increase the performance to 93% by including ECG and respiration features. In contrast, on intervals of ambiguous sleep stage, the sleep stage classification obtained from our algorithm, agrees with the human consensus scorer in approximately 61%.
Conclusions: These findings suggest that machine classification is highly consistent with human sleep staging and that error in the algorithm’s assignments is rather a problem of lack of well-defined criteria for human experts to judge certain polysomnogram epochs than an insufficiency of computational procedures.
A Data Protection Scheme for Medical Research Networks
Authors: Demiroglu S. Y. , Rakebrandt F. , Pommerening K. , Rienhoff O. , Sax U. , Helbing K. 
Published: July 2010

Summary
Background: The data protection requirements matured in parallel to new clinical tests generating more personal data since the 1960s. About ten years ago it was recognized that a generic data protection scheme for medical research networks is required, which reinforces patient rights but also allows economically feasible medical research compared to “hand-carved” individual solutions.
Objectives: To give recommendations for more efficient IT infrastructures for medical research networks in compliance with data protection requirements.
Methods: The IT infrastructures of three medical research networks were reviewed with respect to the relevant data management modules. Recommendations are derived to increase cost efficiency in research networks assessing the consequences of a service provider approach without lowering the data protection level.
Results: The existing data protection schemes are very complex. Smaller research networks cannot afford the implementation of such schemes. Larger networks struggle to keep them sustainable. Due to a modular redesign in the medical research network community, a new approach offers opportunities for an efficient sustainable IT infrastructure involving a service provider concept. For standard components 70–80% of the costs could be cut down, for open source components about 37% over a three-year period.
Conclusions: Future research networks should switch to a service-oriented approach to achieve a sustainable, cost-efficient IT infrastructure.
Clonal structure of wild populations and origins of horticultural stocks of Illicium parviflorum (Illiciaceae)
Authors: Newell Darah L. , Morris Ashley B. 
Published: July 2010

• Premise of the study: Habitat fragmentation is often assumed to result in limited genetic diversity across impacted plant communities. Central Florida has undergone extensive anthropogenic changes, while also harboring large numbers of endemic species. In this study, we assessed genetic structure and dependence on clonality in a central Florida endemic, Illicium parviflorum (Illiciaceae), as well as evaluated genetic diversity of this species in horticultural stocks.• Methods: Six sites were sampled across the geographic range of I. parviflorum. A PCR‐based assay using intersimple sequence repeats (ISSRs) was used to assess genetic structure.• Key results: Results, based on 26 ISSR loci, suggest that clonal structure plays a role in all populations, with PD values ranging from 0.25 to 0.50. Only two populations exhibited unique genotypes, while the remaining four populations shared genotypes. Horticultural samples all shared one genotype, which can be traced back to a single natural population.• Conclusions: Clonal reproduction is an important factor in the maintenance of natural populations of I. parviflorum, although the degree to which this is true varies by population. Horticultural samples likely represent a single or very few collection events, indicating the need for greater genetic diversity within horticultural stocks. Further analyses using microsatellites are planned to confirm these results.
Wirkstoffverabreichung mithilfe polymerer Mehrschichtkapseln
Authors: De Cock Liesbeth J. , De Koker Stefaan , De Geest Bruno G. , Grooten Johan , Vervaet Chris , Remon Jean Paul , Sukhorukov Gleb B. , Antipina Maria N. 
Published: July 2010

AbstractDie Fortschritte der letzten Jahre in Medizin und Biotechnologie haben die Entwicklung von Transportsystemen im Nanomaßstab dringlich gemacht, die eine Vielzahl an neuartigen Therapeutika wie Proteine, Chemotherapeutika und Nucleinsäuren einschließen können. Zudem sollten diese Transportsysteme “intelligent” sein, d. h., sie sollten ihre Ladung zu einer festgelegten Zeit, an einem bestimmten Ort oder nach einer spezifischen Stimulierung abladen können. Seit polymere Mehrschichtkapseln verfügbar sind, die durch mehrstufiges Beschichten eines Opfertemplats und anschließendes Auflösen dieses Templats hergestellt werden, ist es möglich, Mikrokapseln unter rein wässrigen Bedingungen mithilfe einfacher Baustein‐ und Assoziationsverfahren gezielt herzustellen, was eine bislang unerreichte Steuerung der Mikrokapselfunktionalität erlaubt. Inzwischen sind polymere Mehrschichtkapseln auf zunehmendes Interesse in den Biowissenschaften gestoßen, und viele interessante Systeme mit bioabbaubaren Bestandteilen und biospezifischen Funktionen wurden beschrieben. In dieser Übersicht werden die neuesten Durchbrüche beim Einsatz für die Wirkstoffverabreichung vorgestellt.
A structuration approach to online communities of practice: The case of Q&A communities
Authors: Rosenbaum Howard , Shachaf Pnina 
Published: July 2010

AbstractThis article describes an approach based on structuration theory (Giddens, 1979, 1984; Orlikowski, 1992, 2000) and communities of practice (Wenger, 1998) that can be used to guide investigation into the dynamics of online question and answer (Q&A) communities. This approach is useful because most research on Q&A sites has focused attention on information retrieval, information‐seeking behavior, and information intermediation and has assumed uncritically that the online Q&A community plays an important role in these domains of study. Assuming instead that research on online communities should take into account social, technical, and contextual factors (Kling, Rosenbaum, & Sawyer, 2005), the utility of this approach is demonstrated with an analysis of three online Q&A communities seen as communities of practice. This article makes a theoretical contribution to the study of online Q&A communities and, more generally, to the domain of social reference.
Abstraction Assistant: An automatic text abstraction system
Authors: Wang Wendy , Hwang Drew 
Published: July 2010

AbstractIn the interest of standardization and quality assurance, it is desirable for authors and staff of access services to follow the American National Standards Institute (ANSI) guidelines in preparing abstracts. Using the statistical approach an extraction system (the Abstraction Assistant) was developed to generate informative abstracts to meet the ANSI guidelines for structural content elements. The system performance is evaluated by comparing the system‐generated abstracts with the author's original abstracts and the manually enhanced system abstracts on three criteria: balance (satisfaction of the ANSI standards), fluency (text coherence), and understandability (clarity). The results suggest that it is possible to use the system output directly without manual modification, but there are issues that need to be addressed in further studies to make the system a better tool.
Design and Preparation of Co‐crystals Utilizing the ${{\bf R}{{ \bf 2\hfill \atop \bf 4\hfill}}}$(8) Hydrogen‐Bonding Motif
Authors: Bernstein Joel , Novoa Juan J. , Boese Roland , Cirkel Sebastian A. 
Published: July 2010

AbstractAn investigation of the feasibility of utilizing a specific, and previously largely unrecognized, hydrogen‐bonded synthon for the design and preparation of co‐crystals is reported. Structural evidence (i.e., >12 000 instances) indicated the robustness of the cyclic${{\rm{R}}_4^2 (8)}$hydrogen‐bonded motif containing, in most cases, four individual (either identical or different) molecules, in which the donor substituent (e.g., an amine) can provide two hydrogen‐bond donors, and the acceptor (e.g., a carbonyl oxygen) can provide two hydrogen‐bond acceptors. The energetic robustness of the motif with respect to chemical substitution and charge on the component molecules was investigated and confirmed in a series of fully optimized calculations at the MP2/6‐31+G(d) level. A proof‐of‐concept experiment to prepare a co‐crystal between a prototypical ketone and a primary amine yielded the crystal structure reported herein, in which the hydrogen bonds between the co‐crystal components indeed exhibit exclusively the designed and sought‐after${{\rm{R}}_4^2 (8)}$motif.
Highly Efficient Visible Light Plasmonic Photocatalyst Ag@Ag(Br,I)
Authors: Wang Peng , Huang Baibiao , Zhang Qianqian , Zhang Xiaoyang , Qin Xiaoyan , Dai Ying , Zhan Jie , Yu Jiaoxian , Liu Haixia , Lou Zaizhu 
Published: July 2010

AbstractThe new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion‐exchange process between the silver bromide and potassium iodide, then by reducing some Ag+ ions in the surface region of Ag(Br,I) particles to Ag0 species. Ag nanoparticles are formed from Ag(Br,I) by the light‐induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83 nm to 1 μm. The as‐grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce CrVI under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X‐ray diffraction and X‐ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I).
An Investigation into the Optimum Thickness of Titanium Dioxide Thin Films Synthesized by Using Atmospheric Pressure Chemical Vapour Deposition for Use in Photocatalytic Water Oxidation
Authors: Hyett Geoffrey , Darr Jawwad A. , Mills Andrew , Parkin Ivan P. 
Published: July 2010

AbstractTwenty eight films of titanium dioxide of varying thickness were synthesised by using atmospheric pressure chemical vapour deposition (CVD) of titanium(IV) chloride and ethyl acetate onto glass and titanium substrates. Fixed reaction conditions at a substrate temperature of 660 °C were used for all depositions, with varying deposition times of 5–60 seconds used to control the thickness of the samples. A sacrificial electron acceptor system composed of alkaline sodium persulfate was used to determine the rate at which these films could photo‐oxidise water in the presence of 365 nm light. The results of this work showed that the optimum thickness for CVD films on titanium substrates for the purposes of water oxidation was ≈200 nm, and that a platinum coating on the reverse of such samples leads to a five‐fold increase in the observed rate of water oxidation.
Redox Sorption and Recovery of Silver Ions as Silver Nanocrystals on Poly(aniline‐co‐5‐sulfo‐2‐anisidine) Nanosorbents
Authors: Li Xin‐Gui , Feng Hao , Huang Mei‐Rong 
Published: July 2010

AbstractPoly[aniline(AN)‐co‐5‐sulfo‐2‐anisidine(SA)] nanograins with rough and porous structure demonstrate ultrastrong adsorption and highly efficient recovery of silver ions. The effects of five key factors—AN/SA ratio, AgI concentration, sorption time, ultrasonic treatment, and coexisting ions—on AgI adsorbability were optimized, and AN/SA (50/50) copolymer nanograins were found to exhibit much stronger AgI adsorption than polyaniline and all other reported sorbents. The maximal AgI sorption capacity of up to 2034 mg g−1 (18.86 mmol g−1) is the highest thus far and also much higher than the maximal Hg‐ion sorption capacity (10.28 mmol g−1). Especially at ≤2 mM AgI, the nanosorbents exhibit ≥99.98 % adsorptivity, and thus achieve almost complete AgI sorption. The sorption fits the Langmuir isotherm well and follows pseudo‐second‐order kinetics. Studies by IR, UV/Vis, X‐ray diffraction, polarizing microscopy, centrifugation, thermogravimetry, and conductivity techniques showed that AgI sorption occurs by a redox mechanism mainly involving reduction of AgI to separable silver nanocrystals, chelation between AgI and NH/N/NH2/ SO3H/OCH3, and ion exchange between AgI and H+ on SO3−H+. Competitive sorption of AgI with coexisting Hg, Pb, Cu, Fe, Al, K, and Na ions was systematically investigated. In particular, the copolymer nanoparticles bearing many functional groups on their rough and porous surface can be directly used to recover and separate precious silver nanocrystals from practical AgI wastewaters containing Fe, Al, K, and Na ions from Kodak Studio. The nanograins have great application potential in the noble metals industry, resource reuse, wastewater treatment, and functional hybrid nanocomposites.
Density Functional Calculations of 55Mn, 14N and 13C Electron Paramagnetic Resonance Parameters Support an Energetically Feasible Model System for the S2 State of the Oxygen‐Evolving Complex of Photosystem II
Authors: Schinzel Sandra , Schraut Johannes , Arbuznikov Alexei V. , Siegbahn Per E. M. , Kaupp Martin 
Published: July 2010

AbstractMetal and ligand hyperfine couplings of a previously suggested, energetically feasible Mn4Ca model cluster (SG2009−1) for the S2 state of the oxygen‐evolving complex (OEC) of photosystem II (PSII) have been studied by broken‐symmetry density functional methods and compared with other suggested structural and spectroscopic models. This was carried out explicitly for different spin‐coupling patterns of the S=1/2 ground state of the MnIII(MnIV)3 cluster. By applying spin‐projection techniques and a scaling of the manganese hyperfine couplings, computation of the hyperfine and nuclear quadrupole coupling parameters allows a direct evaluation of the proposed models in comparison with data obtained from the simulation of EPR, ENDOR, and ESEEM spectra. The computation of 55Mn hyperfine couplings (HFCs) for SG2009−1 gives excellent agreement with experiment. However, at the current level of spin projection, the 55Mn HFCs do not appear sufficiently accurate to distinguish between different structural models. Yet, of all the models studied, SG2009−1 is the only one with the MnIII site at the MnC center, which is coordinated by histidine (D1‐His332). The computed histidine 14N HFC anisotropy for SG2009−1 gives much better agreement with ESEEM data than the other models, in which MnC is an MnIV site, thus supporting the validity of the model. The 13C HFCs of various carboxylates have been compared with 13C ENDOR data for PSII preparations with 13C‐labelled alanine.
3‐Fluoroaspartate and Pyruvoyl‐Dependant Aspartate Decarboxylase: Exploiting the Unique Characteristics of Fluorine To Probe Reactivity and Binding
Authors: de Villiers Jandré , Koekemoer Lizbé , Strauss Erick 
Published: July 2010

AbstractFluorine‐containing amino acids have been used with great success as mechanism‐based inhibitors of pyridoxal phosphate (PLP)‐dependent enzymes, and the influence of fluorine on the conformation of molecules has also been extensively studied and practically exploited. In this study, we sought to use these unique characteristics to probe the reactivity and binding of aspartate decarboxylase (ADC) enzymes, which are members of the small class of pyruvoyl‐dependant decarboxylases. Since ADC activity has been shown to be essential to the virulence of Mycobacterium tuberculosis, information gained in this manner could be used for the development of inhibitors that selectively target pyruvoyl‐dependent enzymes such as ADC, without affecting PLP‐dependent enzymes in the host. For this purpose, we synthesized the L‐erythro and L‐threo isomers of 3‐fluoroaspartate and tested their ability to act as substrates and/or inhibitors of the M. tuberculosis and Escherichia coli ADC enzymes. Trapping and MS‐based binding analysis was additionally used to confirm that both isomers enter the enzymes’ active sites. Our studies show that both isomers undergo single turnover decarboxylation and fluorine elimination reactions to give enamine products that can be trapped within the active site. Interestingly, the enamine/ADC complex that forms from the L‐erythro (but not the L‐threo) isomer is sufficiently stable that it can be observed even without any trapping. This finding suggests that the two 3‐fluoroaspartates maintain different conformations within the ADC active site, which leads to the enamine products with configurations of different stabilities. Taken together, our results provide new insights for the development of cofactor‐specific inhibitors, and confirm the utility of fluorine as a unique tool for probing reactivity and binding profiles within enzymes.
Multichromophoric Phthalocyanine–(Perylenediimide)8 Molecules: A Photophysical Study
Authors: Albert‐Seifried Sebastian , Finlayson Chris E. , Laquai Frederic , Friend Richard H. , Swager Timothy M. , Kouwer Paul H. J. , Juríček Michal , Kitto Heather J. , Valster Sanne , Nolte Roeland J. M. , Rowan Alan E. 
Published: July 2010

AbstractWe describe the synthesis of a series of phthalocyanine (Pc)–perylenediimide (PDI)8 “octad” molecules, in which eight PDI moieties are attached to a Pc core through alkyl‐chain linkers. There is clear spectroscopic evidence that these octads can exist as non‐aggregated “monomers” or form aggregates along the Pc cores, depending on the type of Pc and the solvent medium. In the low dielectric constant solvents, into which the octads are soluble, photoexcitation of the PDI units leads to rapid energy transfer to the Pc centre, rather than a charge separation between moieties. In octad monomers, the Pc singlet excited‐state decays within tens of ps, whereas the excitons are stabilised in the aggregated form of the molecules, typically with lifetimes in the order of 1–10 ns. By contrast, in an octad design in which π–π interactions are suppressed by the steric hindrance of a corona of incompatible glycol tails around the molecule, a more straightforward photophysical interaction of Förster energy transfer between the PDI moieties and Pc core may be inferred. We consider these molecules as prototypical multichromophoric aggregates, giving delocalised states with considerable flexibility of design.
Highly Enantioselective Synthesis of α‐Stereogenic Esters through Catalytic Asymmetric Michael Addition of 4‐Oxo‐4‐arylbutenoates
Authors: Wang Zhen , Chen Donghui , Yang Zhigang , Bai Sha , Liu Xiaohua , Lin Lili , Feng Xiaoming 
Published: July 2010

AbstractHighly enantioselective Michael addition of 1,3‐dicarbonyl compounds and nitromethane to 4‐oxo‐4‐arylbutenoates catalyzed by N,N′‐dioxide–Sc(OTf)3 complexes has been developed. Using 0.5–2 mol % catalyst loading, various α‐stereogenic esters were obtained regioselectively with excellent yields (up to 97 %) and enantioselectivities (up to >99 % ee). Moreover, the reaction performed well under nearly solvent‐free conditions. The products with functional groups are ready for further transformation, which showed the potential value of the catalytic approach. According to the experimental results and previous reports, a plausible working model has been proposed to explain the origin of the activation and the asymmetric induction.
DFT Investigation of the Palladium‐Catalyzed Ene–Yne Coupling
Authors: Henriksen Signe Teuber , Tanner David , Skrydstrup Troels , Norrby Per‐Ola 
Published: July 2010

AbstractThe mechanism of the recently developed palladium‐catalyzed ene–yne coupling has been evaluated by DFT methods. The calculations validate the previously proposed reaction mechanism and explain the stereoselectivity of the reaction (exclusive formation of the E isomer of the disubstituted alkene). Concerning chemoselectivity, the calculations also clarify why the ene–yne coupling is able to dominate over plausible alternative reaction pathways such as alkene homocoupling and alkyne polymerization. The role of the phosphine ligand at various stages of the catalytic cycle has also been delineated.
Synthesis of Diverse Indole‐Containing Scaffolds by Gold(I)‐Catalyzed Tandem Reactions of 3‐Propargylindoles Initiated by 1,2‐Indole Migrations: Scope and Computational Studies
Authors: Sanz Roberto , Miguel Delia , Gohain Mukut , García‐García Patricia , Fernández‐Rodríguez Manuel A. , González‐Pérez Adán , Nieto‐Faza Olalla , de Lera Ángel R. , Rodríguez Félix 
Published: July 2010

AbstractSimilar to propargylic carboxylates and sulphides, 3‐propargylindoles undergo 1,2‐indole migrations under cationic gold(I) catalysis. The intermediate Au–carbenoid complex may evolve through different pathways depending on the substituents at the propargylic and terminal positions of the alkyne moiety. Thus, 3‐indenylindole derivatives were easily obtained through formal iso‐Nazarov or Nazarov cyclizations. DFT computations support the formation of an alkylidenecyclopropane intermediate that undergoes gold‐iso‐Nazarov or gold‐Nazarov cyclizations upon torquoselective ring opening. In addition, 3‐dienylindoles could be accessed when none of the referred pathways were accessible and so the intermediate Au–carbenoid complex evolved via a 1,2‐CH insertion reaction. We have also demonstrated that the final products can be obtained in a one‐pot protocol from easily available propargylic alcohols and indoles.