bluuebunny/crossref_metadata_2025 huggingface dataset:
Two‐Dimensional Periodic Relief Gratings as a Versatile Platform for Label‐Free Specific DNA Detection
Authors: Chen Jem‐Kun , Zhou Gang‐Yan , Chang Chi‐Jung , Lee Ai‐Wei , Chang Feng‐Chih
Published: February 2014

In this study, nanopillar arrays of silicon oxide are fabricated through a process involving very‐large‐scale integration, for use as two‐dimensional periodic relief gratings (2DPRGs) on silicon surfaces. Oligonucleotides are successively immobilized on the pillar surface, allowing the system to be used as an optical detector specific for the targeted single‐stranded DNAs (ssDNAs). The surfaces of the oligonucleotides‐modified 2DPRGs undergo insignificant structural changes, but upon hybridizing with target ssDNA, the 2DPRGs undergo dramatic changes in terms of their pillar scale. Binding of the oligonucleotides to the 2DPRG occurs in a way that allows them to retain their function and selectively bind the target ssDNA. The performance of the sensor is evaluated by capturing the target ssDNA on the 2DPRGs and measuring the effective refractive index (neff). The binding of the target ssDNA species to the 2DPRGs results in a color change from pure blue to red, observable by the naked eye along an angle of 15–20°. Moreover, effective medium theory is used to calculate the filling factors inside the 2DPRGs and, thereby, examine the values of neff during the structural changes of the 2DPRGs. Accordingly, these new films have potential applications as label‐free optical biosensors.
Plasmonic Schottky Nanojunctions for Tailoring the Photogeneration Profile in Thin Film Solar Cells
Authors: Beck Fiona J. , Lasanta Tania , Konstantatos Gerasimos
Published: February 2014

Schottky nanojunctions are presented, fabricated from solution‐processed PbS quantum dot films and self‐assembled Ag nanoparticle arrays. If the Ag nanoparticle arrays are sufficiently dense to ensure the overlap of the individual depletion regions set up around the discrete Ag nanoparticles, open circuit voltages and shunt resistances similar to reference Schottky junctions with bulk Ag contacts can be achieved. Light is incident from the Ag nanoparticle side of the device and can excite localized surface plasmon resonances in the metal. These plasmonic resonances strongly concentrate the electromagnetic field within tens of nanometers of the nanoparticles. The resulting absorption profile is modified such that carriers are generated close to the metal–semiconductor interface, within the depletion region of the Schottky diodes. In this way, the generation profile is tailored across the device to achieve more efficient carrier collection. External quantum efficiency spectra exhibit clear spectral features characteristic of near‐field assisted absorption, as predicted by full field optical simulations. By comparing two different active layer thicknesses—resulting in one depleted reference device and one partially depleted—it is possible to differentiate between the optical (due to changes in absorption) and electrical (due to changes in carrier collection efficiency) effects of modifying the generation profile in Schottky diodes.
Ultra‐confined Modes in Metal Nanoparticle Arrays for Subwavelength Light Guiding and Amplification
Authors: Palacios Edgar , Chen Aiqing , Foley Jonathan , Gray Stephen K. , Welp Ulrich , Rosenmann Daniel , Vlasko‐Vlasov Vitalii K.
Published: February 2014

Propagating optical eigenmodes are found in densely packed monolayers of plasmonic nanoparticles on a metal mirror. FDTD numerical calculations show that these 2D waves carry strongly confined and amplified light energy directly in the layer of nanoparticles or in the gap between the nanoparticles and the mirror. The extreme amplification of light intensity and localization at the nanoscale offer a high potential of these waves for photon emission, light harvesting, and waveguiding applications.
Compliant, Heterogeneously Integrated GaAs Micro‐VCSELs towards Wearable and Implantable Integrated Optoelectronics Platforms
Authors: Kang Dongseok , Lee Sung‐Min , Li Zhengwei , Seyedi Ashkan , O'Brien John , Xiao Jianliang , Yoon Jongseung
Published: February 2014

Vertical cavity surface emitting lasers (VCSELs) represent a ubiquitous light source with unique performance characteristics that excel for edge‐emitting lasers or light‐emitting diodes. VCSELs are available, however, mostly on growth wafers in rigid, planar formats over restricted areas, thereby frustrating their use for applications that benefit greatly from unconventional design options including large‐scale, programmable assemblies on unusual substrates, hybrid integration with dissimilar materials and devices, or mechanically compliant constructions. Here, materials design and fabrication strategies are presented to overcome these limitations of conventional VCSELs and create new application opportunities that are unavailable with existing technologies. Specialized epitaxial design and fabrication processes, together with printing‐based integration methods, enable defect‐free release of ultrathin, microscale VCSELs and their device‐level implementation on non‐native substrates in a scalable, cost‐effective fashion. Demonstrations of large‐scale, addressable arrays of VCSELs on plastics for flexible near‐infrared laser displays, and heterogeneous assemblies with silicon‐based electronics to form integrated optoelectronic sensors, illustrate unique capabilities.
Tuneable Nanostructuring of Highly Transparent Zinc Gallogermanate Glasses and Glass‐Ceramics
Authors: Chenu Sébastien , Véron Emmanuel , Genevois Cécile , Matzen Guy , Cardinal Thierry , Etienne Auriane , Massiot Dominique , Allix Mathieu
Published: February 2014

New nanostructured gallogermanate‐based glass materials exhibiting high transparency in the visible and infrared regions are fabricated by conventional melt‐quenching. These materials can accommodate wide oxide compositions and present nanoscale phase separation, in the form of droplets well separated from the germanate matrix. The size of the nanostructures can be tailored depending on the composition. A single heat treatment then allows selective crystallization of the sole glassy phase corresponding to the droplets. As the crystal growth is limited by the size of the initial phase separation, the resulting glass‐ceramic materials exhibit nanostructures and transparency similar to the ones observed in the parent glass. The large variety of accessible compositions combined with the precise control over the nanostructure offer a great opportunity to design new highly transparent nanostructured glass and glass‐ceramic materials with a wide range of tuneable optical properties.
Ultrahigh‐Energy‐Density Lithium‐Ion Batteries Based on a High‐Capacity Anode and a High‐Voltage Cathode with an Electroconductive Nanoparticle Shell
Authors: Lee Jung‐In , Lee Eun‐Ho , Park Jang‐Hoon , Park Soojin , Lee Sang‐Young
Published: February 2014

The combination of high‐capacity anodes and high‐voltage cathodes has garnered a great deal of attention in the pursuit of high‐energy‐density lithium‐ion batteries. As a facile and scalable electrode‐architecture strategy to achieve this goal, a direct one‐pot decoration of high‐capacity silicon (Si) anode materials and of high‐voltage LiCoO2 (LCO) cathode materials is demonstrated with colloidal nanoparticles composed of electroconductive antimony‐doped tin oxide (ATO). The unusual ATO nanoparticle shells enhance electronic conduction in the LCO and Si electrode materials and mitigate unwanted interfacial side reactions between the electrode materials and liquid electrolytes. The ATO‐coated LCO materials (ATO‐LCO) enable the construction of a high‐mass‐loading cathode and suppress the dissolution of cobalt and the generation of by‐products during high‐voltage cycling. In addition, the ATO‐coated Si (ATO‐Si) anodes exhibit highly stable capacity retention upon cycling. Integration of the high‐voltage ATO‐LCO cathode and high‐capacity ATO‐Si anode into a full cell configuration brings unprecedented improvements in the volumetric energy density and in the cycling performance compared to a commercialized cell system composed of LCO/graphite.
Strategic planning, design, and development of the shale gas supply chain network
Authors: Cafaro Diego C. , Grossmann Ignacio E.
Published: February 2014

The long‐term planning of the shale gas supply chain is a relevant problem that has not been addressed before in the literature. This article presents a mixed‐integer nonlinear programming (MINLP) model to optimally determine the number of wells to drill at every location, the size of gas processing plants, the section and length of pipelines for gathering raw gas and delivering processed gas and by‐products, the power of gas compressors, and the amount of freshwater required from reservoirs for drilling and hydraulic fracturing so as to maximize the net present value of the project. Because the proposed model is a large‐scale nonconvex MINLP, we develop a decomposition approach based on successively refining a piecewise linear approximation of the objective function. Results on realistic instances show the importance of heavier hydrocarbons to the economics of the project, as well as the optimal usage of the infrastructure by properly planning the drilling strategy. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2122–2142, 2014
An analytical solution to the extended Navier–Stokes equations using the Lambert W function
Authors: Jaishankar Aditya , McKinley Gareth H.
Published: February 2014

Microchannel gas flows are of importance in a wide range of microelectro mechanical devices. In these flows, the mean free path of the gas can be comparable to the characteristic length of the microchannel, leading to strong diffusion‐enhanced transport of momentum. Numerical solutions to the extended Navier–Stokes equations (ENSE) have successfully modeled such microchannel flows. Analytical solutions to the ENSE for the pressure and velocity fields using the Lambert W function are derived. We find that diffusive contributions to the total transport are only dominant for low average pressures and low pressure drops across the microchannel. For large inlet pressures, we show that the expressions involving the Lambert W function predict steep gradients in the pressure and velocity localized near the channel exit. We extract a characteristic length for this boundary layer. Our analytical results are validated by numerical and experimental results available in the literature. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1413–1423, 2014
FeII‐Spincrossover‐Komplexe in ultradünnen Filmen: elektronische Struktur und Spinschaltung durch sichtbares und Vakuum‐UV‐Licht
Authors: Ludwig E. , Naggert H. , Kalläne M. , Rohlf S. , Kröger E. , Bannwarth A. , Quer A. , Rossnagel K. , Kipp L. , Tuczek F.
Published: February 2014

Die elektronische Struktur des FeII‐Spincrossover‐Komplexes [Fe(H2bpz)2(phen)], deponiert als ultradünner Film auf Au(111), wird mithilfe von UV‐Photoelektronenspektroskopie (UPS) im High‐Spin‐ und im Low‐Spin‐Zustand bestimmt. Dies ermöglicht es auch, den thermischen sowie den photoinduzierten Spinübergang in diesem System zu verfolgen. Der Komplex wird ebenfalls durch Bestrahlung mit Vakuum‐UV‐Licht in den metastabilen High‐Spin‐Zustand überführt. Relaxationsraten nach Photoanregung werden als Funktion der Temperatur bestimmt. Sie zeigen einen Übergang von thermisch aktiviertem zu Tunnelverhalten und sind zwei Größenordnungen höher als im Volumenmaterial.
Tunable Oxygen Activation for Catalytic Organic Oxidation: Schottky Junction versus Plasmonic Effects
Authors: Long Ran , Mao Keke , Gong Ming , Zhou Shan , Hu Jiahua , Zhi Min , You Yang , Bai Song , Jiang Jun , Zhang Qun , Wu Xiaojun , Xiong Yujie
Published: February 2014

The charge state of the Pd surface is a critical parameter in terms of the ability of Pd nanocrystals to activate O2 to generate a species that behaves like singlet O2 both chemically and physically. Motivated by this finding, we designed a metal–semiconductor hybrid system in which Pd nanocrystals enclosed by {100} facets are deposited on TiO2 supports. Driven by the Schottky junction, the TiO2 supports can provide electrons for metal catalysts under illumination by appropriate light. Further examination by ultrafast spectroscopy revealed that the plasmonics of Pd may force a large number of electrons to undergo reverse migration from Pd to the conduction band of TiO2 under strong illumination, thus lowering the electron density of the Pd surface as a side effect. We were therefore able to rationally tailor the charge state of the metal surface and thus modulate the function of Pd nanocrystals in O2 activation and organic oxidation reactions by simply altering the intensity of light shed on Pd–TiO2 hybrid structures.
CH Bond Arylation in the Synthesis of Aryltetralin Lignans: A Short Total Synthesis of Podophyllotoxin
Authors: Ting Chi P. , Maimone Thomas J.
Published: February 2014

A short total synthesis of podophyllotoxin, the prototypical aryltetralin lignan natural product, is reported. Key to the success of this synthetic pathway is a Pd‐catalyzed C(sp3)–H arylation reaction enabled by a conformational biasing element to promote C–C reductive elimination over an alternative CN bond‐forming pathway. This strategy allows for access to the natural product in five steps from commercially available bromopiperonal, and sheds light on subtle conformational effects governing reductive elimination pathways from high‐valent palladium centers.
New Generation of Biocatalysts for Organic Synthesis
Authors: Nestl Bettina M. , Hammer Stephan C. , Nebel Bernd A. , Hauer Bernhard
Published: February 2014

The use of enzymes as catalysts for the preparation of novel compounds has received steadily increasing attention over the past few years. High demands are placed on the identification of new biocatalysts for organic synthesis. The catalysis of more ambitious reactions reflects the high expectations of this field of research. Enzymes play an increasingly important role as biocatalysts in the synthesis of key intermediates for the pharmaceutical and chemical industry, and new enzymatic technologies and processes have been established. Enzymes are an important part of the spectrum of catalysts available for synthetic chemistry. The advantages and applications of the most recent and attractive biocatalysts—reductases, transaminases, ammonia lyases, epoxide hydrolases, and dehalogenases—will be discussed herein and exemplified by the syntheses of interesting compounds.
Toward a Symphony of Reactivity: Cascades Involving Catalysis and Sigmatropic Rearrangements
Authors: Jones Amanda C. , May Jeremy A. , Sarpong Richmond , Stoltz Brian M.
Published: February 2014

Catalysis and synthesis are intimately linked in modern organic chemistry. The synthesis of complex molecules is an ever evolving area of science. In many regards, the inherent beauty associated with a synthetic sequence can be linked to a certain combination of the creativity with which a sequence is designed and the overall efficiency with which the ultimate process is performed. In synthesis, as in other endeavors, beauty is very much in the eyes of the beholder. It is with this in mind that we will attempt to review an area of synthesis that has fascinated us and that we find extraordinarily beautiful, namely the combination of catalysis and sigmatropic rearrangements in consecutive and cascade sequences.

Sometimes the assessment of beauty is nearly unanimous. The first four notes of Beethoven’s 5th Symphony (Symphony No.5 in C minor, Op.67) represent perhaps the most well‐known and popular motif in classical music. The orchestral score is shown in the background of the cover graphic. Accessed March 20, 2013 from http://imslp.org/wiki/Symphony_No.5,_Op.67_%28Beethoven,_Ludwig_van%29.
Metal‐Free Hydrogenation of Unsaturated Hydrocarbons Employing Molecular Hydrogen
Authors: Paradies Jan
Published: February 2014

The metal‐free activation of hydrogen by frustrated Lewis pairs (FLPs) is a valuable method for the hydrogenation of polarized unsaturated molecules ranging from imines, enamines, and silyl enol ethers to heterocycles. However, one of the most important applications of hydrogenation technology is the conversion of unsaturated hydrocarbons into alkanes or alkenes. Despite the fast development of the FLP chemistry, such reactions proved as highly challenging. This Minireview provides an overview of the basic concepts of FLP chemistry, the challenge in the hydrogenation of unsaturated hydrocarbons, and first solutions to this central transformation.
Heterologous Reconstitution of Ikarugamycin Biosynthesis in E. coli
Authors: Antosch Janine , Schaefers Françoise , Gulder Tobias A. M.
Published: February 2014

Polycyclic tetramate macrolactams (PTMs) are a family of biomedically promising natural products with challenging molecular frameworks. Despite these interesting properties, so far only relatively little is known about the biosynthetic origin of PTMs, in particular concerning the mechanism by which their ring systems are formed. Herein we present the first insights into these processes by using the biosynthesis of ikarugamycin as an example. This has been facilitated by the first heterologous expression of a PTM biosynthetic gene cluster in Escherichia coli. With this approach it will not only become possible to mechanistically investigate already known PTM biosynthetic pathways in more detail in the future, but also to interrogate cryptic PTM biosynthetic pathways chemically and biochemically.
Ring‐functionalized niobocene complexes
Authors: Honzíčková Iva , Honzíček Jan , Vinklárek Jaromír , Padělková Zdeňka , Řezáčová Martina , Šebestová Lucie
Published: February 2014

A series of new ring‐functionalized niobocene dichloride compounds (RCH2C5H4)2NbCl2 (R = MeOCH2, (CH2)5NCH2, 2‐MeOC6H4, 3‐MeOC6H4, 4‐MeOC6H4, 2,4‐(MeO)2C6H3, 3,4‐(MeO)2C6H3, 2,4,6‐(MeO)3C6H2, 3,4,5‐(MeO)3C6H2, 4‐FC6H4, 4‐Me2NC6H4) was synthesized and characterized by electron paramagnetic resonance. Three structures were determined by X‐ray diffraction analysis and revealed the expected bent metallocene structure with two cyclopentadienyl ligands and two chlorides coordinated to niobium in the oxidation state IV. Chlorides and the centroids of the η5‐bonded cyclopentadienyl rings define a distorted tetrahedron. The cytotoxicity study has demonstrated that substitution with methoxybenzyl groups can lead to highly active species, but the activity strongly varies with the number and positions of the methoxy groups in the benzene ring. The most active species under study – {2,4‐(MeO)2C6H3CH2C5H4}2NbCl2 – has a maximal inhibitory concentration value comparable with cisplatin. Copyright © 2014 John Wiley & Sons, Ltd.
Significantly improving electro‐activated shape recovery performance of shape memory nanocomposite by self‐assembled carbon nanofiber and hexagonal boron nitride
Authors: Lu Haibao , Lei Ming , Leng Jinsong
Published: February 2014

This study presents two effective approaches to significantly improve the electro‐thermal properties and electro‐activated shape recovery performance of shape memory polymer (SMP) nanocomposites that are incorporated with carbon nanofibers (CNFs) and hexagonal boron nitrides (h‐BNs), and show Joule heating triggered shape recovery. CNFs were self‐assembled and deposited into buckypaper form to significantly improve the electrical properties of SMP and achieve the shape memory effect induced by electricity. The h‐BNs were either blended into or self‐assembled onto CNF buckypaper to significantly improve the thermally conductive properties and electro‐thermal performance of SMPs. Furthermore, the shape recovery behavior and temperature profile during the electrical actuation of the SMP nanocomposites were monitored and characterized. It was found that a unique synergistic effect of CNFs and h‐BNs was presented to facilitate the heat transfer and accelerate the electro‐activated shape recovery behavior of the SMP nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40506.
Functionalized KIT‐6/Terpolyimide composites with ultra‐low dielectric constant
Authors: Purushothaman Revathi , Palanichamy Muthiapillai , Mohammed Bilal I.
Published: February 2014

Polyimides with low dielectric constants are important raw materials for the fabrication of flexible printed circuit boards and other microelectronic applications. As creation of voids in polyimide matrix could decrease dielectric constant, in this study mesoporous KIT‐6, synthesized hydrothermally, was functionalized with 3‐aminopropyltriethoxysilane (APTS) and mixed with 4,4′‐oxydianiline (ODA) in the synthesis of terpoly(amic acid) using 3,3′,4,4′‐biphenyldianhydride (BPDA), 3,3′,4,4′‐oxydiphthalic dianhydride (ODPA) and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) and subsequently stage‐cured to obtain APTS‐KIT‐6/Terpolyimide composites (APTS‐KIT‐6/TPI). The asymmetric and symmetric vibrations of imide OCNCO groups of APTS‐KIT‐6/TPI composites showed their peaks at 1772 and 1713 cm−1. The dielectric constant decreased with the increase in KIT‐6 loading from 2 to 4%, but increased at higher loadings, and at 4% loading it was 1.42. Its tensile strength (103 MPa), tensile modulus (2.5 GPa), and percentage elongation (8.2) and high thermal stability (>540°C) were also adequate for application in microelectronics such as flexible printed circuits. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40508.
Comparison of modification of a bacterial uricase with N‐hydroxysuccinimide esters of succinate and carbonate of monomethoxyl poly(ethylene glycol)
Authors: Zhang Chun , Yang Xiaolan , Gao Ang , Hu Xiaolei , Pu Jun , Liu Hongbo , Feng Juan , Liao Juan , Li Yuanli , Liao Fei
Published: February 2014

Uricase after modification with monomethoxy poly(ethylene glycol) (mPEG) is currently the sole agent to treat refractory gout. For formulating Bacillus fastidious uricase, succinimidyl carbonate of mPEG‐5000 (SC‐mPEG5k) and succinimidyl succinate of mPEG‐5000 (SS‐mPEG5k) were compared. SC‐mPEG5k possessed higher purity, comparable reaction rate constant with glycine but lower hydrolysis rate, and stronger effectiveness to modify amino groups. The uricase possessed two types of amino groups bearing a 25‐fold difference in reactivity with SC‐mPEG5k or SS‐mPEG5k at pH 9.2. Oxonate and xanthine concentration‐dependently protected the bacterial uricase from inactivation during PEGylation. With SC‐mPEG5k at a molar ratio of 200 to uricase subunits and oxonate of 50 µM, the PEGylated uricase (1) retained about 73% of the original activity, (2) displayed about 10% reactivity to rabbit anti‐sera recognizing the native uricase, (3) elicited IgG in rats accounting for about 5% of that by the native uricase, (4) exhibited circulation half‐life time of about 25 H in cock plasma in vivo, and (5) concurrently maintained uric acid at lowered levels for over 20 H. Hence, PEGylation with SC‐mPEG under the protection of a competitive inhibitor was a practical approach to formulation of the bacterial uricase; protection of enzymes by competitive inhibitors during PEGylation may have universal significance.
Rare nasal cleft in a patient with holoprosencephaly due to a mutation in the ZIC2 gene
Authors: Savastano Clarice Pagani , Bernardi Pricila , Seuánez Hector N. , Moreira Miguel Ângelo Martins , Orioli Iêda Maria
Published: February 2014

BACKGROUND

Holoprosencephaly (HPE) is a spectrum of midline malformations of the prosencephalon generally reflected in a continuum of midline facial anomalies. Patients with mutation in the ZIC2 gene usually present a normal or mildly dysmorphic face associated with a severe brain malformation. Here we present a rare unilateral nasal cleft (Tessier cleft n. 1) with holoprosencephaly in a patient with a ZIC2 mutation.

CASE

The male newborn presented with alobar HPE, microcephaly, ocular hypertelorism, upslanting palpebral fissures, a bulky nose with a left paramedian alar cleft. Mutational screening for HPE genes revealed the occurrence of a frameshift mutation in the ZIC2 gene. The mutation was inherited from the father who presented only mild ocular hypotelorism but had an affected child with HPE from his first marriage.

CONCLUSION

The occurrence of oral clefts is common in patients with HPE, but unusual in patients with mutation in the ZIC2 gene. To our knowledge, clefts of the nasal alae have been reported only once or twice in patients with ZIC2 mutations. In documented patients from the literature, only 2% of individuals with described pathogenic mutations in the ZIC2 gene (3/171) presented facial clefts, one of them a nasal cleft, while common oral clefts were observed in 27% of individuals (7/26) described with nonpathogenic ZIC2 mutations or presenting a concomitant mutation in another HPE gene. When compared with the general population, nasal clefts are common in ZIC2 mutations and these mutations must be searched for in undiagnosed cases. Birth Defects Research (Part A) 100:300–306, 2014. © 2014 Wiley Periodicals, Inc.
Probability estimation with machine learning methods for dichotomous and multicategory outcome: Applications
Authors: Kruppa Jochen , Liu Yufeng , Diener Hans‐Christian , Holste Theresa , Weimar Christian , König Inke R. , Ziegler Andreas
Published: February 2014

Machine learning methods are applied to three different large datasets, all dealing with probability estimation problems for dichotomous or multicategory data. Specifically, we investigate k‐nearest neighbors, bagged nearest neighbors, random forests for probability estimation trees, and support vector machines with the kernels of Bessel, linear, Laplacian, and radial basis type. Comparisons are made with logistic regression. The dataset from the German Stroke Study Collaboration with dichotomous and three‐category outcome variables allows, in particular, for temporal and external validation. The other two datasets are freely available from the UCI learning repository and provide dichotomous outcome variables. One of them, the Cleveland Clinic Foundation Heart Disease dataset, uses data from one clinic for training and from three clinics for external validation, while the other, the thyroid disease dataset, allows for temporal validation by separating data into training and test data by date of recruitment into study. For dichotomous outcome variables, we use receiver operating characteristics, areas under the curve values with bootstrapped 95% confidence intervals, and Hosmer–Lemeshow‐type figures as comparison criteria. For dichotomous and multicategory outcomes, we calculated bootstrap Brier scores with 95% confidence intervals and also compared them through bootstrapping. In a supplement, we provide R code for performing the analyses and for random forest analyses in Random Jungle, version 2.1.0. The learning machines show promising performance over all constructed models. They are simple to apply and serve as an alternative approach to logistic or multinomial logistic regression analysis.
Ho3+‐doped strontium–aluminium–bismuth–borate glasses for green light emission
Authors: Rajesh D. , Dhamodhara Naidu M. , Ratnakaram Y. C. , Balakrishna A.
Published: February 2014

Strontium–aluminium–bismuth–borate glasses (SAlBiB) doped with different concentrations of Ho3+ were prepared using conventional melt quenching technique and their structural and optical properties investigated. X‐ray diffraction and scanning electron microscopy analysis were used to study the structural properties. Optical properties were studied by measuring the optical absorption and visible luminescence spectra. The Judd–Ofelt (J‐O) theory was applied to evaluate J‐O intensity parameters, Ωλ (λ = 2, 4 and 6). Using J‐O intensity parameters, radiative properties such as spontaneous transition probabilities (AR), branching ratios (βR) and radiative lifetimes (τR) were determined. From the emission spectra, a strong green emission nearly at 549 nm corresponding to the transition, 5S2(5F4)→5I8 was observed. Emission peak positions (λP), effective bandwidths (Δλeff) and stimulated emission cross‐sections (σp) were calculated for the observed emission transitions, 5F3→5I8, 5S2(5F4)→5I8 and 5F5→5I8 of Ho3+ in all the glass matrices. Chromaticity color coordinates were calculated using the emission spectra. The experimental results suggest that SAlBiB glass matrix with 1.5 mol% of Ho3+ has better emission properties. Copyright © 2014 John Wiley & Sons, Ltd.
Directed evolution of a cellodextrin transporter for improved biofuel production under anaerobic conditions in Saccharomyces cerevisiae
Authors: Lian Jiazhang , Li Yanglin , HamediRad Mohammad , Zhao Huimin
Published: February 2014

Introduction of a cellobiose utilization pathway consisting of a cellodextrin transporter and a β‐glucosidase into Saccharomyces cerevisiae enables co‐fermentation of cellobiose and xylose. Cellodextrin transporter 1 (CDT1) from Neurospora crassa has been established as an effective transporter for the engineered cellobiose utilization pathways. However, cellodextrin transporter 2 (CDT2) from the same species is a facilitator and has the potential to be more efficient than CDT1 under anaerobic conditions due to its energetic benefits. Currently, CDT2 has a very low activity and is considered rate‐limiting in cellobiose fermentation. Here, we report the directed evolution of CDT2 with an increased cellobiose uptake activity, which results in improved cellobiose fermentation under anaerobic conditions. After three rounds of directed evolution, the cellobiose uptake activity of CDT2 was increased by 2.2‐fold, which resulted from both increased specific activity and transporter expression level. Using high cell density fermentation under anaerobic conditions, the evolved mutant conferred 4.0‐ and 4.4‐fold increase in the cellobiose consumption rate and ethanol productivity, respectively. In addition, although the cellobiose uptake activity was still lower than that of CDT1, the engineered CDT2 showed significantly improved cellobiose consumption and ethanol production under anaerobic conditions, representing the energetic benefits of a sugar facilitator for anaerobic cellobiose fermentation. This study demonstrated that anaerobic biofuel production could be significantly improved via directed evolution of a sugar transporter protein in yeast. Biotechnol. Bioeng. 2014;111: 1521–1531. © 2014 Wiley Periodicals, Inc.
Evaluation of a kinetic model for computer simulation of growth and fermentation by Scheffersomyces (Pichia) stipitis fed D‐xylose
Authors: Slininger P. J. , Dien B. S. , Lomont J. M. , Bothast R. J. , Ladisch M. R. , Okos M. R.
Published: February 2014

Scheffersomyces (formerly Pichia) stipitis is a potential biocatalyst for converting lignocelluloses to ethanol because the yeast natively ferments xylose. An unstructured kinetic model based upon a system of linear differential equations has been formulated that describes growth and ethanol production as functions of ethanol, oxygen, and xylose concentrations for both growth and fermentation stages. The model was validated for various growth conditions including batch, cell recycle, batch with in situ ethanol removal and fed‐batch. The model provides a summary of basic physiological yeast properties and is an important tool for simulating and optimizing various culture conditions and evaluating various bioreactor designs for ethanol production. Biotechnol. Bioeng. 2014;111: 1532–1540. © 2014 Wiley Periodicals, Inc.
Lotsenfunktion von Phosphatidylinositen
Authors: Hille‐Rehfeld Annette
Published: February 2014

Phosphatidylinosite sind eine besonders vielfältige und wandelbare Gruppe von Membranlipiden. Ihre Vertreter finden sich spezifisch in unterschiedlichen Zellkompartimenten und beteiligen sich als Adressierungssignale an der Steuerung des Vesikeltransports innerhalb von Zellen.
Radical versus conservative surgical treatment of liver hydatid cysts
Authors: El Malki H O , Souadka A , Benkabbou A , Mohsine R , Ifrine L , Abouqal R , Belkouchi A
Published: February 2014

Background

The management of liver hydatid cysts is controversial. Surgery remains the basic treatment, and can be divided into radical and conservative approaches. The purpose of this study was to compare the results of radical and conservative surgery in the treatment of liver hydatid cysts.

Methods

Data from all patients with liver hydatid cyst treated in a hepatobiliary surgical unit, between January 1990 and December 2010, were retrieved from a retrospective database. To minimize selection bias, propensity score matching was performed, based on 17 variables representing patient characteristics and operative risk factors. The primary outcome measure was hydatid cyst recurrence.

Results

One hundred and seventy patients were matched successfully, representing 85 pairs who had either a radical or a conservative approach to surgery. At a median (i.q.r.) follow-up of 106 (59–135) and 87 (45–126) months in the radical and conservative groups respectively, the recurrence rate was 4 per cent in both groups (odds ratio (OR) 1·00, 95 per cent confidence interval 0·19 to 5·10). There were no statistically significant differences between conservative and radical surgery in terms of operative mortality (1 versus 0 per cent; P = 0·497), deep abdominal complications (12 versus 16 per cent; OR 1·46, 0·46 to 3·49), overall postoperative complications (15 versus 19 per cent; OR 1·28, 0·57 to 2·86), reinterventions (0 versus 4 per cent; P = 0·246) and median hospital stay (7 (i.q.r. 5–12) days in both groups; P = 0·220).

Conclusion

This study could not demonstrate that radical surgery reduces recurrence and no trend towards such a reduction was observed.
Determination of cefuroxime lysine in rat brain microdialysates by ultra‐fast liquid chromatography with UV and tandem mass spectrometry: application to an acute toxicokinetic study
Authors: Zhao Longshan , Li Qing , Zhu Heyun , Chen Xiaohui , Bi Kaishun
Published: February 2014

Cefuroxime lysine is a new second‐generation cephalosporins, which can penetrate the blood–brain barrier to cure the meningitis. In order to investigate its acute toxicokinetic study after intraperitoneal injection of 675 mg/kg cefuroxime lysine, a sensitive and clean ultra‐fast liquid chromatography–tandem mass spectrometry (UFLC‐MS/MS) method for the determination of cefuroxime lysine in microdialysate samples was developed and validated, which was compared with UFLC‐UV as a reference method. Chromatographic separation was performed on a Shim‐pack XR‐ODS C18 column (75 × 3.0 mm, 2.2 µm), with an isocratic elution of 0.1% formic acid in acetonitrile–0.1% formic acid in water (45:55, v/v) for LC‐MS and acetonitrile–20 mm potassium dihydrogen phosphate (pH 3.0,20:80, v/v) for LC‐UV. The lower limit of detection was 0.01 µg/mL for LC‐MS and 0.1 µg/mL for LC‐UV method, with the same corresponding linearity range of 0.1–50 µg/mL. The intra‐ and inter‐day precisions (relative standard deviation) for both methods were from 1.1 to 8.9%, while the accuracy was all within ±10.9%. The results of both methods were finally compared using paired t‐test; the results indicated that the concentrations measured by the two methods correlated significantly (p < 0.05), which suggested that the two methods based on LC‐MS and LC‐UV were suitable for the acute toxicokinetic study. Copyright © 2014 John Wiley & Sons, Ltd.
Alphavbeta6 is required in maintaining the intestinal epithelial barrier function
Authors: Yu Yong , Chen Si , Lu Gao‐Feng , Wu Yingying , Mo Lihua , Liu Zhi‐Qiang , Zheng Peng‐Yuan , Liu Zhigang , Yang Ping‐Chang
Published: February 2014

Epithelial barrier dysfunction is involved in a large number of diseases, but the pathogenesis is unclear. Integrin alphavbeta6 (avb6) in involved in the maintenance of the mucosal homeostasis. We have investigated the role of avb6 in maintaining the epithelial barrier function. Using T84 monolayers cultures, transepithelial electric resistance (TER) and permeability to ovalbumin (OVA) were measured as indicators of functioning. The antigenicity of OVA collected from the Transwell basal chambers was assessed using OVA‐specific T cell proliferation. Knockdown of the avb6 genes increased the permeability of T84 monolayers to OVA, but did not affect TER. The deficiency of avb6‐related hyperpermeability in T84 monolayers could be compensated by adding exogenous avb6 to the culture. The OVA samples collected from the basal chambers had strong antigenicity as it markedly induced the antigen specific T cell proliferation. Addition of recombinant avb6 blocked increases in permeability of T84 monolayers to OVA induced by tumor necrosis factor‐α.
Hybrid procedure of bilateral pulmonary artery banding and bilateral ductal stenting in an infant with aortic atresia and interrupted aortic arch
Authors: Kobayashi Daisuke , Turner Daniel R. , Delius Ralph E. , Aggarwal Sanjeev
Published: February 2014

We report an infant with aortic valve atresia, interrupted aortic arch, ventricular septal defect, confluent pulmonary arteries, bilateral arterial ducts, absent common carotid arteries, and anomalous coronary arteries arising from main pulmonary artery. Hybrid procedure consisting of bilateral pulmonary artery banding and bilateral arterial duct stenting was performed at 4 weeks of age. Hybrid procedure can be an alternative palliative approach in an infant with this complex cardiac anatomy. © 2014 Wiley Periodicals, Inc.
Myocardial infarction due to intracoronary embolization of percutaneous coronary intervention packaging
Authors: Ertel Andrew W. , Shroff Adhir R. , Vidovich Mladen I.
Published: February 2014

Intracoronary device loss is occasionally encountered and removal is commonly performed at the time of the procedure. We report a case of removal of a retained coronary balloon protective plastic tubing inadvertently left in the coronary artery for a month and associated with myocardial infarction. Optical coherence tomography was used to visualize the foreign body prior to removal with a snare. To our knowledge this is the first report of a removal of disposable packaging equipment after prolonged intracoronary dwell time. © 2014 Wiley Periodicals, Inc.
Expanding the Scope of Alcohol Dehydrogenases towards Bulkier Substrates: Stereo‐ and Enantiopreference for α,α‐Dihalogenated Ketones
Authors: Kędziora Kinga , Bisogno Fabricio R. , Lavandera Iván , Gotor‐Fernández Vicente , Montejo‐Bernardo Jose , García‐Granda Santiago , Kroutil Wolfgang , Gotor Vicente
Published: February 2014

Alcohol dehydrogenases (ADHs) were identified as suitable enzymes for the reduction of the corresponding α,α‐dihalogenated ketones, obtaining optically pure β,β‐dichloro‐ or β,β‐dibromohydrins with excellent conversions and enantiomeric excess. Among the different biocatalysts tested, ADHs from Rhodococcus ruber (ADH‐A), Ralstonia sp. (RasADH), Lactobacillus brevis (LBADH), and PR2ADH proved to be the most efficient ones in terms of activity and stereoselectivity. In a further study, two racemic α‐substituted ketones, namely α‐bromo‐ α‐chloro‐ and α‐chloro‐α‐fluoroacetophenone were investigated to obtain one of the four possible diastereoisomers through a dynamic kinetic process. In the case of the brominated derivative, only the (1R)‐enantiomer was obtained by using ADH‐A, although with moderate diastereomeric excess (>99 % ee, 63 % de), whereas the fluorinated ketone exhibited a lower stereoselectivity (up to 45 % de).
Hierarchical Mesoporous SnO Microspheres as High Capacity Anode Materials for Sodium‐Ion Batteries
Authors: Su Dawei , Xie Xiuqiang , Wang Guoxiu
Published: February 2014

Mesoporous SnO microspheres were synthesised by a hydrothermal method using NaSO4 as the morphology directing agent. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high‐resolution transmission electron microscopy (HRTEM) analyses showed that SnO microspheres consist of nanosheets with a thickness of about 20 nm. Each nanosheet contains a mesoporous structure with a pore size of approximately 5 nm. When applied as anode materials in Na‐ion batteries, SnO microspheres exhibited high reversible sodium storage capacity, good cyclability and a satisfactory high rate performance. Through ex situ XRD analysis, it was found that Na+ ions first insert themselves into SnO crystals, and then react with SnO to generate crystalline Sn, followed by Na–Sn alloying with the formation of crystalline NaSn2 phase. During the charge process, there are two slopes corresponding to the de‐alloying of Na–Sn compounds and oxidisation of Sn, respectively. The high sodium storage capacity and good electrochemical performance could be ascribed to the unique hierarchical mesoporous architecture of SnO microspheres.
Phosphine‐Catalyzed Domino Reactions: A Route to Functionalized Bicyclic Skeletons
Authors: Li Erqing , Huang You
Published: February 2014

A novel strategy that involves phosphine‐catalyzed sequential [2+3] and [3+2] annulation reactions was developed. In this domino reaction, γ‐substituted allenoates were used as novel C4 synthons, and the bicyclic cyclopenta[b]dihydrofuran derivatives were produced in good to excellent diastereoselectivities and yields under mild conditions. Furthermore, preliminary studies on an asymmetric variant of this reaction proceeded with moderate enantioselectivity.
Molecular Dyads Comprising Metalloporphyrin and Alkynylplatinum(II) Polypyridine Terminal Groups for Use as a Sensitizer in Dye‐Sensitized Solar Cells
Authors: Kwok Eric Chi‐Ho , Chan Mei‐Yee , Wong Keith Man‐Chung , Yam Vivian Wing‐Wah
Published: February 2014

A new class of molecular dyads comprising metalloporphyrin‐linked alkynylplatinum(II) polypyridine complexes with carboxylic acids as anchoring groups has been designed and synthesized. These complexes can sensitize nanocrystalline TiO2 in dye‐sensitized solar cell (DSSC) studies. The photophysical, electrochemical, and luminescence properties of the complexes were studied and their excited‐state properties were investigated by nanosecond transient absorption spectroscopy, with the charge‐separated [Por.−{(CC)Pt(tBu3tpy)}.+] state observed upon excitation. Excited‐state redox potentials were determined; the electrochemical data supports the capability of the complexes to inject an electron into the conduction band of TiO2. The complexes sensitize nanocrystalline TiO2 and exhibited photovoltaic properties, as characterized by current–voltage measurements under illumination of air mass 1.5 G sunlight (100 mWcm−2). A DSSC based on one of the complexes showed a short‐circuit photocurrent of 10.1 mAcm−2, an open‐circuit voltage of 0.64 V, and a fill factor of 0.52, giving an overall power conversion efficiency of 3.4 %.
Diblock‐Copolymer‐Mediated Self‐Assembly of Protein‐Stabilized Iron Oxide Nanoparticle Clusters for Magnetic Resonance Imaging
Authors: Tähkä Sari , Laiho Ari , Kostiainen Mauri A.
Published: February 2014

Superparamagnetic iron oxide nanoparticles (SPIONs) can be used as efficient transverse relaxivity (T2) contrast agents in magnetic resonance imaging (MRI). Organizing small (D<10 nm) SPIONs into large assemblies can considerably enhance their relaxivity. However, this assembly process is difficult to control and can easily result in unwanted aggregation and precipitation, which might further lead to lower contrast agent performance. Herein, we present highly stable protein–polymer double‐stabilized SPIONs for improving contrast in MRI. We used a cationic–neutral double hydrophilic poly(N‐methyl‐2‐vinyl pyridinium iodide‐block‐poly(ethylene oxide) diblock copolymer (P2QVP‐b‐PEO) to mediate the self‐assembly of protein‐cage‐encapsulated iron oxide (γ‐Fe2O3) nanoparticles (magnetoferritin) into stable PEO‐coated clusters. This approach relies on electrostatic interactions between the cationic N‐methyl‐2‐vinylpyridinium iodide block and magnetoferritin protein cage surface (pI≈4.5) to form a dense core, whereas the neutral ethylene oxide block provides a stabilizing biocompatible shell. Formation of the complexes was studied in aqueous solvent medium with dynamic light scattering (DLS) and cryogenic transmission electron microcopy (cryo‐TEM). DLS results indicated that the hydrodynamic diameter (Dh) of the clusters is approximately 200 nm, and cryo‐TEM showed that the clusters have an anisotropic stringlike morphology. MRI studies showed that in the clusters the longitudinal relaxivity (r1) is decreased and the transverse relaxivity (r2) is increased relative to free magnetoferritin (MF), thus indicating that clusters can provide considerable contrast enhancement.
Halide‐Free Diarylcalcium Complexes—Syntheses, Structures, and Stability
Authors: Langer Jens , Köhler Mathias , Görls Helmar , Westerhausen Matthias
Published: February 2014

A general procedure was developed for the synthesis of diarylcalcium complexes by addition of KOtBu to arylcalcium iodides in THF. Intermediate arylcalcium tert‐butanolate dismutates immediately leading to insoluble tert‐butanolate precipitates of calcium. Depending on the steric demand and denticity of additional neutral aliphatic azabases, mononuclear or dinuclear complexes trans‐[Ca(α‐Naph)2(thf)4] (1), [Ca(β‐Naph)2(thf)4] (2), [Ca(Tol)2(tmeda)]2 (3), [Ca(Ph)2(tmeda)]2 (4), [Ca(Ph)2(pmdta)(thf)] (5), [Ca(hmteta)(Ph)2] (6), and [Ca([18]C‐6)(Ph)2] (7) were isolated (Naph=naphthyl; meda=N,N,N′,N′‐tetramethylethylenediamine; pmdta= N,N,N′,N′′,N′′‐pentamethyldiethylenetriamine; hmteta=N,N,N′,N′′,N′′′,N′′′‐hexamethyltriethylenetetramine). The CaC bond lengths vary between 250.8 and 263.5 pm, the ipso‐carbon atoms show low‐field‐shifted resonances in the 13C NMR spectra.
Selective Synthesis of Functionalized Trifluoromethylated Pyrrolidines, Piperidines, and Azepanes Starting from 1‐Tosyl‐2‐(trifluoromethyl)aziridine
Authors: Dolfen Jeroen , Kenis Sara , Van Hecke Kristof , De Kimpe Norbert , D'hooghe Matthias
Published: February 2014

This paper reports on the generation and alkylation of the 1‐tosyl‐2‐(trifluoromethyl)aziridin‐2‐yl anion with ω,ω′‐dihaloalkanes, followed by a novel ring‐expansion protocol toward 2‐CF3‐pyrrolidines, 2‐CF3‐piperidines, and 3‐CF3‐azepanes. A variety of halogen, oxygen, nitrogen, sulfur, and carbon nucleophiles was used to trigger this ring rearrangement, resulting in CF3‐azaheterocycles bearing different types of functionalized side chains.
Unusual Nitrile–Nitrile and Nitrile–Alkyne Coupling of FcCN and FcCCCN
Authors: Becker Lisanne , Strehler Frank , Korb Marcus , Arndt Perdita , Spannenberg Anke , Baumann Wolfgang , Lang Heinrich , Rosenthal Uwe
Published: February 2014

Invited for the cover of this issue is the group of Uwe Rosenthal at Leibniz Institute for Catalysis (LIKAT Rostock) and the group of Heinrich Lang at the Technische Universität Chemnitz. The image depicts five coupling possibilities of alkynes and nitriles at metallocenes. Read the full text of the article at 10.1002/chem.201304478.
Chiroptical Study and Absolute Configuration of (−)–O‐DMA Produced From Daidzein Metabolism
Authors: Kim Mihyang , Han Jaehong
Published: February 2014

To elucidate the hitherto unknown absolute configuration of (−)–O‐desmethylangolensin ((−)–O‐DMA), an intestinal bacterial metabolite produced from daidzein, chiroptical study, including specific optical rotation and electronic circular dichroism (ECD), of (R)–O‐DMA was carried out by Time‐Dependent Density Functional Theory (TD‐DFT) calculations. Intramolecular hydrogen bonding between 2’–OH and carbonyl oxygen at 1‐C of O‐DMA was a governing factor for O‐DMA to form the stable conformations. Total energy values of four possible conformers were calculated in the framework of DFT using the B3LYP exchange correlation functional at the 6‐31++G basis set level. The theoretical specific rotation and ECD spectra of all conformers in ethanol were obtained by TD‐DFT calculation using B3LYP functional at the 6‐311++G basis set level, and compared to the experimental data. Chiroptical properties of (R)–O‐DMA showed a good agreement with the biological (−)–O‐DMA. Therefore, the stereospecific biosynthetic pathway of (−)–O‐DMA was proposed as daidzein → (R)‐dihydrodaidzein ↔ (S)‐dihydrodaizein → (R)–O‐DMA. Chirality 26:434–437, 2014. © 2014 Wiley Periodicals, Inc.