bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer‐gestütztes Design ionischer Flüssigkeiten zur CO2‐Absorption
Authors: Firaha Dzmitry S. , Hollóczki Oldamur , Kirchner Barbara
Published: May 2015

Ionische Flüssigkeiten (ILs) variieren stark in ihrer Wechselwirkung mit CO2. Es wird ein einfaches theoretisches Verfahren vorgeschlagen, mit dem sich das Absorptionsverhalten von ILs vorhersagen lässt. Während starke Wechselwirkungen der IL‐Anionen mit CO2 chemische Absorption bedeuten, weisen schwache auf physikalische Absorption hin. Eine Abschätzung mit klarer Trennung zwischen chemischer und physikalischer Absorption kann leicht erhalten werden, indem die Geometrie in Gegenwart eines Solvatationsmodells optimiert wird statt wie bisher nur in der Gasphase. Aus diesen solvatisierten Geometrien lassen sich Gibbs‐Energien erhalten, die sehr gut mit experimentellen Werten übereinstimmen. Somit können die berechneten Gibbs‐Energien mit vermessenen Kapazitäten korreliert werden. Vielversprechende Anionen für den Entwurf von ILs für reversible chemische CO2‐Absorption können durch berechnete Gibbs‐Reaktionsenergien definiert werden. Für diese Kandidaten lassen sich wiederum die Kapazitäten aus der eben erwähnten Korrelation abschätzen.
The Role of Substituent Effects in Tuning Metallophilic Interactions and Emission Energy of Bis‐4‐(2‐pyridyl)‐1,2,3‐triazolatoplatinum(II) Complexes
Authors: Prabhath M. R. Ranga , Romanova Julia , Curry Richard J. , Silva S. Ravi P. , Jarowski Peter D.
Published: May 2015

The photoluminescence spectra of a series of 5‐substituted pyridyl‐1,2,3‐triazolato PtII homoleptic complexes show weak emission tunability (ranging from λ=397–408 nm) in dilute (10−6 M) ethanolic solutions at the monomer level and strong tunability in concentrated solutions (10−4 M) and thin films (ranging from λ=487–625 nm) from dimeric excited states (excimers). The results of density functional calculations (PBE0) attribute this “turn‐on” sensitivity and intensity in the excimer to strong Pt–Pt metallophilic interactions and a change in the excited‐state character from singlet metal‐to‐ligand charge transfer (1MLCT) to singlet metal‐metal‐to‐ligand charge transfer (1MMLCT) emissions in agreement with lifetime measurements.
Zinc‐Catalyzed Alkyne Oxidation/CH Functionalization: Highly Site‐Selective Synthesis of Versatile Isoquinolones and β‐Carbolines
Authors: Li Long , Zhou Bo , Wang Yong‐Heng , Shu Chao , Pan Yi‐Fei , Lu Xin , Ye Long‐Wu
Published: May 2015

An efficient zinc(II)‐catalyzed alkyne oxidation/CH functionalization sequence was developed, thus leading to highly site‐selective synthesis of a variety of isoquinolones and β‐carbolines. Importantly, in contrast to the well‐established gold‐catalyzed intermolecular alkyne oxidation, over‐oxidation can be completely suppressed in this system and the reaction most likely proceeds by a Friedel–Crafts‐type pathway. Mechanistic studies and theoretical calculations are described.
Aufklärung der donorbasenfreien Aggregation von Lithiumdiisopropylamid in Kohlenwasserstoffen mithilfe einer DOSY‐Methode
Authors: Neufeld Roman , John Michael , Stalke Dietmar
Published: May 2015

Lithiumdiisopropylamid (LDA) ist ein überaus wichtiges Reagens und nimmt vor allem in der organischen Synthesechemie eine Schlüsselrolle bei einer Vielzahl von Deprotonierungsreaktionen ein. Trotzdem ist seine Aggregation, und damit die Gestalt der reaktiven Spezies in nichtdonierenden Lösungsmitteln, bislang noch ungeklärt. Hier lösen wir dieses Problem durch eine neu entwickelte DOSY‐NMR‐Methode. Sie beruht auf externen Kalibrierungskurven mit normalisierten Diffusionskoeffizienten und ist vielfältig einsetzbar.
Targeting the Two Oncogenic Functional Sites of the HPV E6 Oncoprotein with a High‐Affinity Bivalent Ligand
Authors: Ramirez Juan , Poirson Juline , Foltz Clémence , Chebaro Yassmine , Schrapp Maxime , Meyer Amandine , Bonetta Anaëlle , Forster Anne , Jacob Yves , Masson Murielle , Deryckère François , Travé Gilles
Published: May 2015

The E6 oncoproteins of high‐risk mucosal (hrm) human papillomaviruses (HPVs) contain a pocket that captures LxxLL motifs and a C‐terminal motif that recruits PDZ domains, with both functions being crucial for HPV‐induced oncogenesis. A chimeric protein was built by fusing a PDZ domain and an LxxLL motif, both known to bind E6. NMR spectroscopy, calorimetry and a mammalian protein complementation assay converged to show that the resulting PDZ‐LxxLL chimera is a bivalent nanomolar ligand of E6, while its separated PDZ and LxxLL components are only micromolar binders. The chimera binds to all of the hrm‐HPV E6 proteins tested but not to low‐risk mucosal or cutaneous HPV E6. Adenovirus‐mediated expression of the chimera specifically induces the death of HPV‐positive cells, concomitant with increased levels of the tumour suppressor P53, its transcriptional target p21, and the apoptosis marker cleaved caspase 3. The bifunctional PDZ‐LxxLL chimera opens new perspectives for the diagnosis and treatment of HPV‐induced cancers.
The Role of Oxygen in the Degradation of Methylammonium Lead Trihalide Perovskite Photoactive Layers
Authors: Aristidou Nicholas , Sanchez‐Molina Irene , Chotchuangchutchaval Thana , Brown Michael , Martinez Luis , Rath Thomas , Haque Saif A.
Published: May 2015

In this paper we report on the influence of light and oxygen on the stability of CH3NH3PbI3 perovskite‐based photoactive layers. When exposed to both light and dry air the mp‐Al2O3/CH3NH3PbI3 photoactive layers rapidly decompose yielding methylamine, PbI2, and I2 as products. We show that this degradation is initiated by the reaction of superoxide (O2−) with the methylammonium moiety of the perovskite absorber. Fluorescent molecular probe studies indicate that the O2− species is generated by the reaction of photoexcited electrons in the perovskite and molecular oxygen. We show that the yield of O2− generation is significantly reduced when the mp‐Al2O3 film is replaced with an mp‐TiO2 electron extraction and transport layer. The present findings suggest that replacing the methylammonium component in CH3NH3PbI3 to a species without acid protons could improve tolerance to oxygen and enhance stability.
Oxygen Evolution Catalyzed by a Mononuclear Ruthenium Complex Bearing Pendant SO3− Groups
Authors: Yoshida Masaki , Kondo Mio , Torii Sena , Sakai Ken , Masaoka Shigeyuki
Published: May 2015

Rational molecular design of catalytic systems capable of smooth OO bond formation is critical to the development of efficient catalysts for water oxidation. A new ruthenium complex was developed, which bears pendant SO3− groups in the secondary coordination sphere: [Ru(terpy)(bpyms)(OH2)] (terpy=2,2′:6′,2′′‐terpyridine, bpyms=2,2′‐bipyridine‐5,5′‐bis(methanesulfonate)). Water oxidation driven by a Ce4+ oxidant is distinctly accelerated upon introduction of the pendant SO3− groups in comparisons to the parent catalyst, [Ru(terpy)(bpy)(OH2)]2+ (bpy=2,2′‐bipyridine). Spectroscopic, electrochemical, and crystallographic investigations concluded that the pendant SO3− groups promote the formation of an OO bond via the secondary coordination sphere on the catalyst, whereas the influence of the pendant SO3− groups on the electronic structure of the [Ru(terpy)(bpy)(OH2)]2+ core is negligible. The results of this work indicate that modification of the secondary coordination sphere is a valuable strategy for the design of water oxidation catalysts.
Gallotannins and Tannic Acid: First Chemical Syntheses and In Vitro Inhibitory Activity on Alzheimer’s Amyloid β‐Peptide Aggregation
Authors: Sylla Tahiri , Pouységu Laurent , Da Costa Grégory , Deffieux Denis , Monti Jean‐Pierre , Quideau Stéphane
Published: May 2015

The screening of natural products in the search for new lead compounds against Alzheimer’s disease has unveiled several plant polyphenols that are capable of inhibiting the formation of toxic β‐amyloid fibrils. Gallic acid based gallotannins are among these polyphenols, but their antifibrillogenic activity has thus far been examined using “tannic acid”, a commercial mixture of gallotannins and other galloylated glucopyranoses. The first total syntheses of two true gallotannins, a hexagalloylglucopyranose and a decagalloylated compound whose structure is commonly used to depict “tannic acid”, are now described. These depsidic gallotannins and simpler galloylated glucose derivatives all inhibit amyloid β‐peptide (Aβ) aggregation in vitro, and monogalloylated α‐glucogallin and a natural β‐hexagalloylglucose are shown to be the strongest inhibitors.
Hypoxia Induced by Upconversion‐Based Photodynamic Therapy: Towards Highly Effective Synergistic Bioreductive Therapy in Tumors
Authors: Liu Yanyan , Liu Yong , Bu Wenbo , Cheng Chao , Zuo Changjing , Xiao Qingfeng , Sun Yong , Ni Dalong , Zhang Chen , Liu Jianan , Shi Jianlin
Published: May 2015

Local hypoxia in tumors is an undesirable consequence of photodynamic therapy (PDT), which will lead to greatly reduced effectiveness of this therapy. Bioreductive pro‐drugs that can be activated at low‐oxygen conditions will be highly cytotoxic under hypoxia in tumors. Based on this principle, double silica‐shelled upconversion nanoparticles (UCNPs) nanostructure capable of co‐delivering photosensitizer (PS) molecules and a bioreductive pro‐drug (tirapazamine, TPZ) were designed (TPZ‐UC/PS), with which a synergetic tumor therapeutic effect has been achieved first by UC‐based (UC‐) PDT under normal oxygen environment, immediately followed by the induced cytotoxicity of activated TPZ when oxygen is depleted by UC‐PDT. Treatment with TPZ‐UC/PS plus NIR laser resulted in a remarkably suppressed tumor growth as compared to UC‐PDT alone, implying that the delivered TPZ has a profound effect on treatment outcomes for the much‐enhanced cytotoxicity of TPZ under PDT‐induced hypoxia.
Inverted Fuel Cell: Room‐Temperature Hydrogen Separation from an Exhaust Gas by Using a Commercial Short‐Circuited PEM Fuel Cell without Applying any Electrical Voltage
Authors: Friebe Sebastian , Geppert Benjamin , Caro Jürgen
Published: May 2015

A short‐circuited PEM fuel cell with a Nafion membrane has been evaluated in the room‐temperature separation of hydrogen from exhaust gas streams. The separated hydrogen can be recovered or consumed in an in situ olefin hydrogenation when the fuel cell is operated as catalytic membrane reactor. Without applying an outer electrical voltage, there is a continuous hydrogen flux from the higher to the lower hydrogen partial pressure side through the Nafion membrane. On the feed side of the Nafion membrane, hydrogen is catalytically split into protons and electrons by the Pt/C electrocatalyst. The protons diffuse through the Nafion membrane, the electrons follow the short‐circuit between the two brass current collectors. On the cathode side, protons and electrons recombine, and hydrogen is released.
Remote Hydroxylation through Radical Translocation and Polar Crossover
Authors: Hollister Kyle A. , Conner Elizabeth S. , Spell Mark L. , Deveaux Kristina , Maneval Léa , Beal Michael W. , Ragains Justin R.
Published: May 2015

Mild conditions are reported for the hydroxylation of aliphatic CH bonds through radical translocation, oxidation to carbocation, and nucleophilic trapping with H2O. This remote functionalization employs fac‐[Ir(ppy)3] together with Tzo sulfonate esters and sulfonamides to facilitate the site‐selective replacement of relatively inert CH bonds with the more synthetically useful COH group. The hydroxylation of a range of substrates and the methoxylation of two substrates through 1,6‐ and 1,7‐hydrogen‐atom transfer are demonstrated. In addition, a synthesis of the antidepressant fluoxetine using remote hydroxylation as a key step is presented.
Unambiguous Diagnosis of Photoinduced Charge Carrier Signatures in a Stoichiometrically Controlled Semiconducting Polymer‐Wrapped Carbon Nanotube Assembly
Authors: Olivier Jean‐Hubert , Park Jaehong , Deria Pravas , Rawson Jeff , Bai Yusong , Kumbhar Amar S. , Therien Michael J.
Published: May 2015

Single‐walled carbon nanotube (SWNT)‐based nanohybrid compositions based on (6,5) chirality‐enriched SWNTs ([(6,5) SWNTs]) and a chiral n‐type polymer (S‐PBN(b)‐Ph4PDI) that exploits a perylenediimide (PDI)‐containing repeat unit are reported; S‐PBN(b)‐Ph4PDI‐[(6,5) SWNT] superstructures feature a PDI electron acceptor unit positioned at 3 nm intervals along the nanotube surface, thus controlling rigorously SWNT–electron acceptor stoichiometry and organization. Potentiometric studies and redox‐titration experiments determine driving forces for photoinduced charge separation (CS) and thermal charge recombination (CR) reactions, as well as spectroscopic signatures of SWNT hole polaron and PDI radical anion (PDI−.) states. Time‐resolved pump–probe spectroscopic studies demonstrate that S‐PBN(b)‐Ph4PDI‐[(6,5) SWNT] electronic excitation generates PDI−. via a photoinduced CS reaction (τCS≈0.4 ps, ΦCS≈0.97). These experiments highlight the concomitant rise and decay of transient absorption spectroscopic signatures characteristic of the SWNT hole polaron and PDI−. states. Multiwavelength global analysis of these data provide two charge‐recombination time constants (τCR≈31.8 and 250 ps) that likely reflect CR dynamics involving both an intimately associated SWNT hole polaron and PDI−. charge‐separated state, and a related charge‐separated state involving PDI−. and a hole polaron site produced via hole migration along the SWNT backbone that occurs over this timescale.
Carbon Dioxide Activation and Reaction Induced by Electron Transfer at an Oxide–Metal Interface
Authors: Calaza Florencia , Stiehler Christian , Fujimori Yuichi , Sterrer Martin , Beeg Sebastian , Ruiz‐Oses Miguel , Nilius Niklas , Heyde Markus , Parviainen Teemu , Honkala Karoliina , Häkkinen Hannu , Freund Hans‐Joachim
Published: May 2015

A model system has been created to shuttle electrons through a metal–insulator–metal (MIM) structure to induce the formation of a CO2 anion radical from adsorbed gas‐phase carbon dioxide that subsequently reacts to form an oxalate species. The process is completely reversible, and thus allows the elementary steps involved to be studied at the atomic level. The oxalate species at the MIM interface have been identified locally by scanning tunneling microscopy, chemically by IR spectroscopy, and their formation verified by density functional calculations.
Hyperbranched Hybridization Chain Reaction for Triggered Signal Amplification and Concatenated Logic Circuits
Authors: Bi Sai , Chen Min , Jia Xiaoqiang , Dong Ying , Wang Zonghua
Published: May 2015

A hyper‐branched hybridization chain reaction (HB‐HCR) is presented herein, which consists of only six species that can metastably coexist until the introduction of an initiator DNA to trigger a cascade of hybridization events, leading to the self‐sustained assembly of hyper‐branched and nicked double‐stranded DNA structures. The system can readily achieve ultrasensitive detection of target DNA. Moreover, the HB‐HCR principle is successfully applied to construct three‐input concatenated logic circuits with excellent specificity and extended to design a security‐mimicking keypad lock system. Significantly, the HB‐HCR‐based keypad lock can alarm immediately if the “password” is incorrect. Overall, the proposed HB‐HCR with high amplification efficiency is simple, homogeneous, fast, robust, and low‐cost, and holds great promise in the development of biosensing, in the programmable assembly of DNA architectures, and in molecular logic operations.
Carbon Nanodots: Supramolecular Electron Donor–Acceptor Hybrids Featuring Perylenediimides
Authors: Strauss Volker , Margraf Johannes T. , Dirian Konstantin , Syrgiannis Zois , Prato Maurizio , Wessendorf Cordula , Hirsch Andreas , Clark Timothy , Guldi Dirk M.
Published: May 2015

We describe the formation of charge‐transfer complexes that feature electron‐donating carbon nanodots (CND) and electron‐accepting perylenediimides (PDI). The functionalities of PDIs have been selected to complement those of CNDs in terms of electrostatic and π‐stacking interactions based on oppositely charged ionic head groups and extended π‐systems, respectively. Importantly, the contributions from electrostatic interactions were confirmed in reference experiments, in which stronger interactions were found for PDIs that feature positively rather than negatively charged head groups. The electronic interactions between the components in the ground and excited state were characterized in complementary absorption and fluorescence titration assays that suggest charge‐transfer interactions in both states with binding constants on the order of 8×104 M−1 (25 L g−1). Selective excitation of the two components in ultrafast pump probe experiments gave a 210 ps lived charge‐separated state.
Drug Pharmacokinetics Determined by Real‐Time Analysis of Mouse Breath
Authors: Li Xue , Martinez‐Lozano Sinues Pablo , Dallmann Robert , Bregy Lukas , Hollmén Maija , Proulx Steven , Brown Steven A. , Detmar Michael , Kohler Malcolm , Zenobi Renato
Published: May 2015

Noninvasive, real‐time pharmacokinetic (PK) monitoring of ketamine, propofol, and valproic acid, and their metabolites was achieved in mice, using secondary electrospray ionization and high‐resolution mass spectrometry. The PK profile of a drug influences its efficacy and toxicity because it determines exposure time and levels. The antidepressant and anaesthetic ketamine (Ket) and four Ket metabolites were studied in detail and their PK was simultaneously determined following application of different sub‐anaesthetic doses of Ket. Bioavailability after oral administration vs. intraperitoneal injection was also investigated. In contrast to conventional studies that require many animals to be sacrificed even for low‐resolution PK curves, this novel approach yields real‐time PK curves with a hitherto unmatched time resolution (10 s), and none of the animals has to be sacrificed. This thus represents a major step forward not only in animal welfare, but also major cost and time savings.
Degradation of disaccharides containing two glucose units in subcritical water
Authors: Wiboonsirikul Jintana , Nakata Keisuke , Kobayashi Takashi , Khuwijitjaru Pramote , Adachi Shuji
Published: May 2015

Disaccharides containing two glucose units, including trehalose, cellobiose, maltose, gentiobiose, and isomaltose, were hydrolyzed in a single‐component system using subcritical water at 200–240 °C and 10 MPa. A mixture of maltose and trehalose was also hydrolyzed in a binary‐component system using subcritical water at 210 and 230 °C. The fraction of the remaining disaccharides decreased as a function of the residence time and could be expressed by the Weilbull equation at any temperature. While trehalose showed the highest resistance to hydrolysis, the other disaccharides were much less resistant to hydrolysis and their reaction rates were not much different from each other. The mixture of trehalose and maltose exhibited a reduced resistance to the hydrolysis of trehalose at high hydrolysis temperatures. In addition, glucose, which was the product of the hydrolysis, can be easily subjected to further degradation to organic acids and consequently reduces the pH of the effluent. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.
Cellulose fiber networks reinforced with glutaraldehyde–chitosan complexes
Authors: Wu Tongfei , Du Yicheng , Yan Ning , Farnood Ramin
Published: May 2015

In this study, glutaraldehyde–chitosan complexes (GA–chitosan) were prepared and were used as functional additives to enhance the strength properties of cellulose fiber networks. The adsorption and distribution of GA–chitosan on the surface of cellulose fiber were characterized by scanning electron microscopy, X‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectrometry. The effects of glutaraldehyde dosage and GA–chitosan to fiber ratio on the strength properties, including wet‐strength, wet‐web strength, and dry strength, were investigated. GA–chitosan did not require high temperature curing and had good cross‐linking rates at room temperature. Samples treated with GA–chitosan exhibited significant improvements in their mechanical properties. Wet tensile index and wet‐web tensile index (both at 50% solids), and dry tensile index, were increased by about 1300, 190, and 115%, respectively. The GA–chitosan additive developed in this study provides a useful approach to prepare high‐performance value‐added specialty wood‐fiber based products. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42375.
Dynamics and thermal properties of epoxy resin cured by new diamino disiloxanes
Authors: Shi Xinxiu , Lin Xiankai , Xu Caihong , Cui Mengzhong
Published: May 2015

Two disiloxane compounds, 3,3′‐(1,3‐dimethyl‐1,3‐diphenyl‐1,3‐disiloxanediyl)bis(benzenamine) (C1) and 4,4′‐(1,3‐dimethyl‐1,3‐diphenyl‐1,3‐disiloxanediyl)bis(benzenamine) (C2) were synthesized and used as new curing agents of DGEBA epoxy resin with an epoxy value of 0.51 (E‐51). The curing kinetics of E‐51/C1 and E‐51/C2 systems was investigated by non‐isothermal differential scanning calorimetry (DSC) analyses. The activation energy (ΔE) and the characteristic cure temperatures of the two systems were determined. The two systems have the similar activation energy. The reactivity of E‐51/C1 is higher than that of E‐51/C2. The reaction orders of E‐51/C1 and E‐51/C2 are 0.88 and 0.87, respectively, illustrating that curing reaction between the epoxy resin and curing agent (C1 or C2) is complicated. The DSC result shows that E51 cured by C2 has higher Tg; whereas thermogravimetric analysis results indicate that E51 cured by C1 has higher thermal stability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42385.
Thermophysical properties of bacterial poly(3‐hydroxybutyrate): Characterized by TMA, DSC, and TMDSC
Authors: Wei Liqing , McDonald Armando G.
Published: May 2015

The melting, isothermal and nonisothermal crystallization behaviors of poly(3‐hydroxybutyrate) (PHB) have been studied by means of temperature modulated differential scanning calorimetry (TMDSC) and conventional DSC. Various experimental conditions including isothermal/annealing temperatures (80, 90, 100, 105, 110, 120, 130, and 140°C), cooling rates (2, 5, 10, 20, and 50°C/min) and heating rates (5, 10, 20, 30, 40, and 50°C/min) have been investigated. The lower endothermic peak (Tm1) representing the original crystals prior to DSC scan, while the higher one (Tm2) is attributed to the melting of the crystals formed by recrystallization. Thermomechanical analysis (TMA) was used to evaluate the original melting temperature (Tmelt) and glass transition temperature (Tg) as comparison to DSC analysis. The multiple melting phenomenon was ascribed to the melting‐recrystallization‐remelting mechanism of the crystallites with lower thermal stability showing at Tm1. Different models (Avrami, Jeziorny‐modified‐Avrami, Liu and Mo, and Ozawa model) were utilized to describe the crystallization kinetics. It was found that Liu and Mo's analysis and Jeziorny‐modified‐Avrami model were successful to explain the nonisothermal crystallization kinetic of PHB. The activation energies were estimated in both isothermal and nonisothermal crystallization process, which were 102 and 116 kJ/mol in respective condition. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42412.
Creatinine adsorption capacity of electrospun polyacrylonitrile (PAN)‐zeolite nanofiber membranes for potential artificial kidney applications
Authors: Lu Limin , Samarasekera Champika , Yeow John T.W.
Published: May 2015

Innovative dialysis membranes are needed for dialysis, which is the primary treatment for patients with end stage renal disease. In this study, we developed a polyacrylonitrile zeolite nanofiber composite membrane using an electrospinning process to adsorb uremic toxins through molecular sieve mechanism. Scanning electron microscope images revealed that the average diameter of the fiber fabricated with 10 wt % polyacrylonitrile was 673 nm and that of polyacrilonitirle‐zeolite membranes were 277−419 nm. The creatinine adsorption behavior of 500‐KOA (L), 720‐KOA (Farrierite), 840‐NHA (ZSM‐5), and 940‐HOA (Beta) zeolite powders were investigated. Among all the zeolites, 940‐HOA zeolites showed the best performance. The creatinine adsorption capacity of 940‐zeolite powders increased from 2234 µg/g in 50 µmol/L creatinine solution to 25423 µg/g in 625 µmol/L creatinine solution. The speed of adsorption was very quick; 0.025 g of 940‐zeolite powders can eliminate 91% of 2 µmol creatinine in 5 min. The zeolites incorporated inside the membrane had higher creatinine adsorption capacity than free zeolites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42418.
Hybrid biocomposites with enhanced thermal and mechanical properties for structural applications
Authors: Birat KC , Panthapulakkal Suhara , Kronka Andrei , Agnelli Jose Augusto M. , Tjong Jimi , Sain Mohini
Published: May 2015

The current work focuses on enhancing the mechanical and thermal properties of sisal fiber reinforced composites that were previously used in developing interior automotive trims. In order to extend their use in other structural applications, two hybrid biocomposites with the combination of sisal (SF) and glass fiber (GF)‐SF20/GF10 and SF10/GF20 were blended with polypropylene via extrusion and injection molding process. Critical material properties such as density, fogging, acoustic, mechanical, thermal, and rheological properties were evaluated and results were analyzed using ANOVA. Hybridization of SF and GF enhanced flexural strength and thermal properties of the biocomposites by 33 and 19%, respectively, while no significant change in acoustic, impact and rheological properties were observed. The properties of the hybrid biocomposites were compared with the material specification of a battery tray and it was found that these hybrid biocomposites could be better alternative materials in structural applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42452.
Linear and nonlinear viscoelasticity of oleogels based on vegetable oil and ethylene vinyl acetate copolymer/isotactic polypropylene blends
Authors: Alfonso Jose Enrique Martín , Valencia Concepción
Published: May 2015

This work deals with a rheological study of oleogels based on high‐oleic sunflower oil (HOSO) and ethylene vinyl acetate copolymer (EVA) / isotactic polypropylene (iPP) blends. EVA copolymers with different vinyl acetate content were used. With this aim, linear small amplitude oscillatory shear (SAOS) and nonlinear (relaxation) measurements combined with polarized optical microscopy were carried out. Oleogels were prepared by using the mixing rheometry technique in a batch mixer. Oscillatory strain amplitude sweep tests showed that the end from the viscoelastic linear region for oleogels was accompanied by opposite trends for viscoelastic moduli. SAOS tests showed that all the oleogels present similar behavior characteristic of polymeric systems with physical entanglements. It was found that the elastic equilibrium modulus and loss tangent increases with iPP content. On the other hand, nonlinear relaxation tests presented a strong dependence on the strain applied and the Soskey–Winter model was found to provide an accurate description of the damping function of these oleogels. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42477.
Regulation of Inflammation and Angiogenesis in Giant Cell Arteritis by Acute‐Phase Serum Amyloid A
Authors: O'Neill Lorraine , Rooney Peadar , Molloy Danielle , Connolly Mary , McCormick Jennifer , McCarthy Geraldine , Veale Douglas J. , Murphy Conor C. , Fearon Ursula , Molloy Eamonn
Published: May 2015

Objective

Giant cell arteritis (GCA) is pathologically characterized by dysfunctional angiogenesis and inflammatory cell infiltration. Acute‐phase serum amyloid A (A‐SAA) is an acute‐phase reactant, but is also produced at sites of inflammation and may contribute to vascular inflammation in atherosclerosis. This study was undertaken to examine the effect of A‐SAA on proinflammatory pathways and angiogenesis in GCA, using a novel ex vivo temporal artery tissue explant model.

Methods

Serum A‐SAA levels were measured by enzyme‐linked immunosorbent assay (ELISA). Temporal artery explants and peripheral blood mononuclear cell (PBMC) cultures were established from patients with GCA. Temporal artery explant morphology, viability, and spontaneous release of proinflammatory mediators following 24‐hour culture were assessed by hematoxylin and eosin, calcein viability staining, and ELISA. Temporal artery explants and PBMC cultures were stimulated with A‐SAA (10 μg/ml), and interleukin‐6 (IL‐6), IL‐8, vascular endothelial growth factor, Ang2, and matrix metalloproteinase 2 (MMP‐2)/MMP‐9 were quantified by ELISA and gelatin zymography. The effect of conditioned medium from temporal artery explants on angiogenesis was assessed using endothelial cell Matrigel tube‐formation assays. Temporal artery explants were also embedded in Matrigel, and myofibroblast outgrowth was assessed.

Results

Serum A‐SAA levels were significantly higher in GCA patients versus healthy controls (P < 0.0001). Intact tissue morphology, cell viability, and spontaneous cytokine secretion were demonstrated in temporal artery explants. A‐SAA treatment induced a significant increase in the levels of IL‐6 and IL‐8 from temporal artery explants (P < 0.05) and IL‐8 from PBMCs (P < 0.05) compared to basal conditions. Conditioned medium from A‐SAA–treated explants significantly induced angiogenic tube formation (P < 0.05 versus basal controls). Finally, A‐SAA induced myofibroblast outgrowth and MMP‐9 activation.

Conclusion

Our findings demonstrate a functional role for A‐SAA in regulating temporal artery inflammation, angiogenesis, and invasion, all key processes in the pathogenesis of GCA.
Reset Control Systems With Time‐Varying Delay: Delay‐Dependent Stability And Gain Performance Improvement
Authors: Zhao Guanglei , Wang Jingcheng
Published: May 2015

This paper considers the stability analysis of reset control systems with time‐varying delay. Based on sector reset conditions, delay‐dependent exponential stability and finite gain
stability conditions are proposed, and piecewise Lyapunov functions are used such that less conservative results can be obtained, moreover,
gain performance improvement results are presented to show the advantage of reset control. Numerical examples are given to show the effectiveness.
Nitrilase‐catalyzed conversion of (R,S)‐mandelonitrile by immobilized recombinant Escherichia coli cells harboring nitrilase
Authors: Zhang Xin‐Hong , Liu Zhi‐Qiang , Xue Ya‐Ping , Xu Ming , Zheng Yu‐Guo
Published: May 2015

(R)‐(−)‐Mandelic acid (R‐MA) is widely used both as a versatile intermediate for pharmaceuticals and a resolving agent in chiral resolution processes. In the current study, to improve the stability of operation, recombinant Escherichia coli cells expressing nitrilase from Alcaligenes faecalis were immobilized for the enantioselective hydrolysis of (R,S)‐mandelonitrile to R‐MA. Different immobilization methods including entrapment matrices, entrapment matrices cross‐linked by cross‐linking and polymerization agents, and direct cross‐linking cells using glutaraldehyde (GA) or bionic silicon were investigated. To facilitate industrial solid–liquid separation, the direct cross‐linking recombinant E. coli cells using diatomite/GA/polyethyleneimine with 135.95% relative activity compared with free cells was chosen using water as the reaction medium. The operational stability of the immobilized cells was obviously superior to that of free cells, without significant activity loss after 28 cycles of batch reaction and the successive production of R‐MA could reach 1.88 M. Moreover, the immobilized cells showed good storage stability with about 52% relative activity after storing for 30 days at 4 °C. Therefore, the immobilized biocatalyst is very promising for upscale production of optically pure R‐MA with high performance and low cost.
Pure rhombohedral Bi1‐xEuxPO4 nano‐/micro‐structures: fast synthesis, shape evolution and luminescence properties
Authors: Yu Dongyan , Liang Yujun , Zhang Mengfei , Li Guogang , Yan Chunjie
Published: May 2015

BiPO4 and Eu‐doped BiPO4 crystals were synthesized via a simple precipitation route at room temperature, employing Bi(NO3)3 and (NH4)2HPO4 as the reactants, Eu2O3 as the dopant and citric acid as a template. X‐ray powder diffraction analyses showed that pure rhombohedral BiPO4 form was obtained, and was the preferential orientation growth of the crystal. Field emission scanning electron microscope observations showed that the concentration of Bi3+ obviously changed the products' morphologies from nanosphere, hollow sphere to hexagonal prism. The acidity of the solution and the contents of citric acid and Eu3+ ion tailored the size of the final crystals. Effects of concentration of Eu3+ ion on the luminescence emission intensity were also investigated. Copyright © 2015 John Wiley & Sons, Ltd.
Photophysical and electrochemical properties of a dysprosium‐zinc tetra(4‐sulfonatophenyl)porphyrin complex
Authors: Chen Wen‐Tong , Liu Dong‐Sheng , Xu Ya‐Ping , Luo Qiu‐Yan , Pei Yun‐Peng
Published: May 2015

A dysprosium‐zinc porphyrin, [DyZn(TPPS)H3O]n (1) (TPPS = tetra(4‐sulfonatophenyl)porphyrin), was prepared through solvothermal reactions and structurally characterized by single‐crystal X‐ray diffraction analyses. Complex 1 features a three‐dimensional (3‐D) porous open framework that is thermally stable up to 400 °C. Complex 1 displays a void space of 215 Å3, occupying 9.2% of the unit cell volume. The fluorescence spectra reveal that it shows an emission band in the red region. The fluorescence lifetime is 39 µsec and the quantum yield is 1.7%. The cyclic voltammetry (CV) measurement revealed one quasi‐reversible wave with E1/2 = 0.30 V. Copyright © 2015 John Wiley & Sons, Ltd.
Development of highly sensitive sensor system for methane utilizing cataluminescence
Authors: Gong Gu. , Zhu Hua
Published: May 2015

A gaseous sensor system was developed for the detection of methane based on its cataluminescence emission. Cataluminescence characteristics and optimal conditions were studied in detail under optimized experimental conditions. Results showed that the methane cataluminescence sensor system could cover a linear detection range from 10 to 5800 ppm (R = 0.9963, n = 7) and the detection limit was about 7 ppm (S/N = 3), which was below the standard permitted concentration. Moreover, a linear discriminant analysis method was used to test the recognizable performance of the methane sensor. It was found that methane, ethane, propane and pentane could be distinguished clearly. Its methane sensing properties, including improved sensitivity, selectivity, stability and recognition demonstrated the TiO2/SnO2 materials to be promising candidates for constructing a cataluminescence‐based gas sensor that could be used for detecting explosive gas contaminants. Copyright © 2015 John Wiley & Sons, Ltd.
A chemiluminescence method to detect hydroquinone with water‐soluble sulphonato‐(salen)manganese(III) complex as catalyst
Authors: Zhang Guangbin , Tang Yuhai , Sun Yang , Yu Hua , Du Wei , Fu Qiang
Published: May 2015

A water‐soluble sulphonato‐(salen)manganese(III) complex with excellent catalytic properties was synthesized and demonstrated to greatly enhance the chemiluminescence signal of the hydrogen peroxide − luminol reaction. Coupled with flow‐injection technique, a simple and sensitive chemiluminescence method was first developed to detect hydroquinone based on the chemiluminescence system of the hydrogen peroxide–luminol–sulphonato‐(salen)manganese(III) complex. Under optimal conditions, the assay exhibited a wide linear range from 0.1 to 10 ng mL–1 with a detection limit of 0.05 ng mL–1 for hydroquinone. The method was applied successfully to detect hydroquinone in tap‐water and mineral‐water, with a sampling frequency of 120 times per hour. The relative standard deviation for determination of hydroquinone was less than 5.6%, and the recoveries ranged from 96.8 to 103.0%. The ultraviolet spectra, chemiluminescence spectra, and the reaction kinetics for the peroxide–luminol–sulphonato‐(salen)manganese(III) complex system were employed to study the possible chemiluminescence mechanism. The proposed chemiluminescence analysis technique is rapid and sensitive, with low cost, and could be easily extended and applied to other compounds. Copyright © 2015 John Wiley & Sons, Ltd.
Hairpin formation promoted by the heterochiral dinipecotic acid segment: A DFT study
Authors: Kang Young Kee , Park Hae Sook
Published: May 2015

Conformational preferences for the turn and β‐hairpin structures of Ala‐based peptides [Ac‐Alan‐(R)‐Nip‐(S)‐Nip‐Alan‐X (n = 0–2; X = NHMe or NMe2)] containing nipecotic acid (Nip) residues were carried out using the density functional M06‐2X and the implicit solvation model SMD in CH2Cl2 and/or water. The turn structure of the (R)‐Nip‐(S)‐Nip segment with a C10 H‐bond between two terminal groups was found to be most preferred (populated at 98.9%) in CH2Cl2; this structure is consistent with IR and 1H NMR results. The stabilities of the β‐hairpins containing the (R)‐Nip‐(S)‐Nip segment as a turn motif relative to the extended structures increased with peptide sequence length. The relative strengths of the H‐bonds between the carbonyl oxygen and the amide hydrogen appeared to be responsible for stabilizing the turn and β‐hairpin structures in CH2Cl2. In addition, the (R)‐Nip‐(S)‐Nip segment exhibited the capability to be incorporated into one of the two β‐turn motifs of gramicidin S (GS). The structure of this GS derivative (GS‐Nip2) was generally similar to the native peptide but was less hydrophobic and it is therefore expected to exhibit lower hemolytic activity; however, further experiments are needed to evaluate its antimicrobial activity. The structure of GS‐Nip2 was somewhat more flexible than GS in solvents of higher polarity. Thus, our calculated results regarding the turn and β‐hairpin motifs of the (R)‐Nip‐(S)‐Nip segment indicate that this structure might be useful for the design of bioactive macrocyclic peptides containing β‐hairpin mimics as well as binding epitopes in protein–protein and protein–nucleic acid recognitions. © 2015 Wiley Periodicals, Inc. Biopolymers 103: 609–617, 2015.
Probing the role of sequence in the assembly of three‐dimensional DNA crystals
Authors: Saoji Maithili , Zhang Daoning , Paukstelis Paul J.
Published: May 2015

DNA is a widely used biopolymer for the construction of nanometer‐scale objects due to its programmability and structural predictability. One long‐standing goal of the DNA nanotechnology field has been the construction of three‐dimensional DNA crystals. We previously determined the X‐ray crystal structure of a DNA 13‐mer that forms a continuously hydrogen bonded three‐dimensional lattice through Watson‐Crick and non‐canonical base pairs. Our current study sets out to understand how the sequence of the Watson‐Crick duplex region influences crystallization of this 13‐mer. We screened all possible self‐complementary sequences in the hexameric duplex region and found 21 oligonucleotides that crystallized. Sequence analysis showed that one specific Watson‐Crick pair influenced the crystallization propensity and the speed of crystal self‐assembly. We determined X‐ray crystal structures for 13 of these oligonucleotides and found sequence‐specific structural changes that suggests that this base pair may serve as a structural anchor during crystal assembly. Finally, we explored the crystal self‐assembly and nucleation process. Solution studies indicated that these oligonucleotides do not form base pairs in the absence of cations, but that the addition of divalent cations leads to rapid self‐assembly to higher molecular weight complexes. We further demonstrate that crystals grown from mixtures of two different oligonucleotide sequences contain both oligonucleotides. These results suggest that crystal self‐assembly is nucleated by the formation of the Watson‐Crick duplexes initiated by a simple chemical trigger. This study provides new insight into the role of sequence for the assembly of periodic DNA structures. © 2015 Wiley Periodicals, Inc. Biopolymers 103: 618–626, 2015.
A sensitive and efficient method for trace analysis of some phenolic compounds using simultaneous derivatization and air‐assisted liquid–liquid microextraction from human urine and plasma samples followed by gas chromatography–nitrogen phosphorous detection
Authors: Farajzadeh Mir Ali , Afshar Mogaddam Mohammad Reza , Alizadeh Nabil Ali Akbar
Published: May 2015

In present study, a simultaneous derivatization and air‐assisted liquid–liquid microextraction method combined with gas chromatography–nitrogen phosphorous detection has been developed for the determination of some phenolic compounds in biological samples. The analytes are derivatized and extracted simultaneously by a fast reaction with 1‐flouro‐2,4‐dinitrobenzene under mild conditions. Under optimal conditions low limits of detection in the range of 0.05–0.34 ng mL−1 are achievable. The obtained extraction recoveries are between 84 and 97% and the relative standard deviations are less than 7.2% for intraday (n = 6) and interday (n = 4) precisions. The proposed method was demonstrated to be a simple and efficient method for the analysis of phenols in biological samples. Copyright © 2015 John Wiley & Sons, Ltd.
Highly sensitive HPLC‐DAD method for the assay of gefitinib in patient plasma and cerebrospinal fluid: application to a blood‐brain barrier penetration study
Authors: Fang Luo , Song Yu , Weng Xu , Li Fanzhu , Xu Yaping , Lin Nengming
Published: May 2015

The quantification of intracranial gefitinib (GEF) exposure is limited owing to the sensitivity of analytical equipment. Although mass spectrometry (MS) is the preferred method because of its high sensitivity, the equipment is not available in many laboratories, especially in developing Asian countries. In this paper, we developed a highly sensitive high performance liquid chromatography‐diode array detector (HPLC‐DAD) method for the assay of GEF in human cerebrospinal fluid (CSF) and plasma. GEF was extracted from CSF and plasma by solid‐phase extraction and liquid–liquid extraction, respectively. The chromatographic separation was performed on a C18 column with gradient elution of 0.1% triethylamine solution and acetonitrile, then finally detected at 344 nm. This method was validated and proved to be highly sensitive with a lower limit of quantitation value of 0.11 ng/mL in CSF and 11 ng/mL in plasma. The blood–brain barrier penetration ratio of GEF ranged from 1.48 to 2.41%. This method provides a reliable MS‐independent solution for the quantitation of GEF in patients’ CSF and plasma. Copyright © 2015 John Wiley & Sons, Ltd.
Selective isolation of bacteria for metagenomic analysis: Impact of membrane characteristics on bacterial filterability
Authors: Nnadozie Chika F. , Lin Johnson , Govinden Roshini
Published: May 2015

For indirect DNA extraction for metagenomics studies, bacterial cells can be effectively separated from sample debris by using a simple size exclusion technique, such as filtration, and thereafter lysed. The requirement for the optimal recovery of cells in filtrates is critical to achieve sufficient DNA yield and a representative population. Particles smaller than the filter pore size are expected to be found in the filtrate, whereas particles larger than the filter pore sizes are excluded. However, this is not always the case. It is established that the membrane pore size influences filtration efficiency to some degree. In addition the physicochemical characteristics of the filter suspension and characteristics of the microbial cells being filtered influence the exclusion property of a membrane. This review provides an overview of membrane filtration techniques and the factors that affect filterability of bacteria cells through a filter membrane. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:853–866, 2015
Fractionation of yeast extract by nanofiltration process to assess key compounds involved in CHO cell culture improvement
Authors: Mosser Mathilde , Kapel Romain , Chevalot Isabelle , Olmos Eric , Marc Ivan , Marc Annie , Oriol Eric
Published: May 2015

Yeast extract (YE) is known to greatly enhance mammalian cell culture performances, but its undefined composition decreases process reliability. Accordingly, in the present study, the nature of YE compounds involved in the improvement of recombinant CHO cell growth and IgG production was investigated. First, the benefits of YE were verified, revealing that it increased maximal concentrations of viable cells and IgG up to 73 and 60%, respectively compared to a reference culture. Then, the analyses of YE composition highlighted the presence of molecules such as amino acids, vitamins, salts, nucleobase, and glucose that were contained in reference medium, while others including peptides, trehalose, polysaccharides, and nucleic acids were not. Consequently, YE was fractionated by a nanofiltration process to deeper evaluate its effects on CHO cell cultures. The YE molecules already contained in reference medium were mainly isolated in the permeate fraction together with trehalose and short peptides, while other molecules were concentrated in the retentate. Permeate, which was free of macromolecules, exhibited a similar positive effect than raw YE on maximal concentrations. Additional studies on cell energetic metabolism underlined that dipeptides and tripeptides in permeate were used as an efficient source of nitrogenous substrates. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:875–882, 2015
Advective hydrogel membrane chromatography for monoclonal antibody purification in bioprocessing
Authors: Hou Ying , Brower Mark , Pollard David , Kanani Dharmesh , Jacquemart Renaud , Kachuik Bradley , Stout James
Published: May 2015

Protein A chromatography is widely employed for the capture and purification of monoclonal antibodies (mAbs). Because of the high cost of protein A resins, there is a significant economic driving force to seek new downstream processing strategies. Membrane chromatography has emerged as a promising alternative to conventional resin based column chromatography. However, to date, the application has been limited to mostly ion exchange flow through (FT) mode. Recently, significant advances in Natrix hydrogel membrane has resulted in increased dynamic binding capacities for proteins, which makes membrane chromatography much more attractive for bind/elute operations. The dominantly advective mass transport property of the hydrogel membrane has also enabled Natrix membrane to be run at faster volumetric flow rates with high dynamic binding capacities. In this work, the potential of using Natrix weak cation exchange membrane as a mAb capture step is assessed. A series of cycle studies was also performed in the pilot scale device (> 30 cycles) with good reproducibility in terms of yield and product purities, suggesting potential for improved manufacturing flexibility and productivity. In addition, anion exchange (AEX) hydrogel membranes were also evaluated with multiple mAb programs in FT mode. Significantly higher binding capacity for impurities (support mAb loads up to 10Kg/L) and 40X faster processing speed were observed compared with traditional AEX column chromatography. A proposed protein A free mAb purification process platform could meet the demand of a downstream purification process with high purity, yield, and throughput. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:974–982, 2015