bluuebunny/crossref_metadata_2025 huggingface dataset:
Bis hin zu einer Symphonie der Reaktivität: Kaskaden mit Katalysen und sigmatropen Umlagerungen
Authors: Jones Amanda C. , May Jeremy A. , Sarpong Richmond , Stoltz Brian M.
Published: February 2014

Die Katalyse und die Synthese sind in der modernen organischen Chemie eng miteinander verbunden. Die Synthese komplexer Moleküle ist ein sich ständig weiterentwickelndes Gebiet. In vielerlei Hinsicht kann die inhärente Schönheit einer Synthesesequenz mit einer bestimmten Kombination aus Kreativität, mit der eine Sequenz entworfen wurde, und der Gesamteffizienz, mit der das endgültige Verfahren durchgeführt wird, in Zusammenhang gebracht werden. Ebenso wie bei anderen Unterfangen liegt bei chemischen Synthesen die Schönheit im Auge des Betrachters. In diesem Sinne werden wir versuchen, ein Gebiet der Synthese zu erörtern, das uns fasziniert, und das wir außergewöhnlich schön finden, nämlich die Kombination aus Katalyse und sigmatropen Umlagerungen in konsekutiven Sequenzen und Kaskadenreaktionen.

Manchmal erfolgt die Einschätzung von Schönheit nahezu einstimmig. Bei den ersten vier Noten von Beethovens 5. Symphonie (Symphonie Nr.5 in c‐Moll, op.67) handelt es sich vielleicht um das bekannteste und beliebteste Motiv in der klassischen Musik. Die Orchesterpartitur ist im Hintergrund des Titelbildes abgebildet. http://imslp.org/wiki/Symphony_No.5,_Op.67_%28Beethoven,_Ludwig_van%29, abgerufen am 20. März 2013.
N‐terminale Proteinmodifizierung mittels Substrat‐aktivierter Katalyse
Authors: Liebscher Sandra , Schöpfel Michael , Aumüller Tobias , Sharkhuukhen Ariunkhur , Pech Andreas , Höss Eva , Parthier Christoph , Jahreis Günther , Stubbs Milton T. , Bordusa Frank
Published: February 2014

Artifizielle Funktionalisierungen von Proteinen stellen sowohl in der angewandten als auch in der Grundlagenforschung ein wichtiges Werkzeug dar und erweisen sich als eine Herausforderung für Proteinchemiker. Aufgrund ihrer nativen Regio‐ und Stereoselektivität bieten enzymatische Proteinmodifizierungen einen attraktiven Ansatz, jedoch ist eine universelle Anwendung durch deren hohe Spezifität beschränkt. Aufgrund der intrinsischen Reversibilität enzymatischer Reaktionen sind Proteinasen prinzipiell in der Lage auch Ligationen zu katalysieren. Dies macht sie zu einem interessanten Werkzeug für spezifische Proteinkonjugationen. Wir berichten über die Entwicklung einer hochspezifischen Trypsinvariante für die selektive N‐terminale Modifizierung von Proteinen. Die Reaktion verläuft mit quantitativen Produktausbeuten unter nativen Bedingungen. Wir zeigen, dass die Variante eine ungeordnete Zymogen‐ähnliche Aktivierungsdomäne aufweist, die in Gegenwart geeigneter Substrate in die aktive Konformation überführt wird.
Perowskit als Lichtabsorptionsmaterial: ein Durchbruch in der Photovoltaik
Authors: Kazim Samrana , Nazeeruddin Mohammad Khaja , Grätzel Michael , Ahmad Shahzada
Published: February 2014

Es geschieht nicht oft, dass die Forschung auf ein Material stößt, das zu größten Hoffnungen Anlass gibt und von verschiedenster Seite Interesse erfährt. Wenn es geschieht, verläuft die Entwicklung rasant. Ein solches Material ist Perowskit, das gänzlich neue Konzepte in der Energieumwandlung angestoßen hat. Perowskite sind aufgrund ihrer panchromatischen Lichtabsorption und ihrem ambipolaren Verhalten von herausragendem Interesse als Material für die Photovoltaik. Der maximale Wirkungsgrad von Perowskit‐Solarzellen hat sich in weniger als einem Jahr verdoppelt und erreicht nun Werte von 15 % unter Laborbedingungen. Dies ist besonders markant in einem wissenschaftlichen und industriellen Umfeld, in dem jede Steigerung in der Nachkommastelle als Erfolg gefeiert und breit diskutiert wird. Wir fassen hier den Stand der Forschung bei der Verwendung von Perowskitmaterialien für Solarzellen zusammen.
Electrochemically Assisted Generation of Highly Ordered Azide‐Functionalized Mesoporous Silica for Oriented Hybrid Films
Authors: Vilà Neus , Ghanbaja Jaafar , Aubert Emmanuel , Walcarius Alain
Published: February 2014

One key challenge in inorganic mesoporous films is the development of oriented mesostructures with vertical channels, and even more challenging is their functionalization while maintaining accessible the selected surface groups. Combining the electrochemically assisted deposition of ordered and oriented azide‐functionalized mesoporous silica with alkyne–azide click chemistry enables such nanostructured and vertically aligned hybrid films to be obtained with significant amounts of active organic functional groups, as illustrated for ferrocene and pyridine functions. A good level of mesostructural order was obtained, namely up to 40 % of organosilane in the starting sol. The method could be applied to a wide variety of functional groups, thus offering numerous new opportunities for applications in various fields.
Copolymerization of Metal Nanoparticles: A Route to Colloidal Plasmonic Copolymers
Authors: Liu Kun , Lukach Ariella , Sugikawa Kouta , Chung Siyon , Vickery Jemma , Therien‐Aubin Heloise , Yang Bai , Rubinstein Michael , Kumacheva Eugenia
Published: February 2014

The resemblance between colloidal and molecular polymerization reactions is very useful in fundamental studies of polymerization reactions, as well as in the development of new nanoscale systems with desired properties. Future applications of colloidal polymers will require nanoparticle ensembles with a high degree of complexity that can be realized by hetero‐assembly of NPs with different dimensions, shapes, and compositions. A method has been developed to apply strategies from molecular copolymerization to the co‐assembly of gold nanorods with different dimensions into random and block copolymer structures (plasmonic copolymers). The approach was extended to the co‐assembly of random copolymers of gold and palladium nanorods. A kinetic model validated and further expanded the kinetic theories developed for molecular copolymerization reactions.
Elevated Catalytic Activity of Ruthenium(II)–Porphyrin‐Catalyzed Carbene/Nitrene Transfer and Insertion Reactions with N‐Heterocyclic Carbene Ligands
Authors: Chan Ka‐Ho , Guan Xiangguo , Lo Vanessa Kar‐Yan , Che Chi‐Ming
Published: February 2014

Bis(NHC)ruthenium(II)–porphyrin complexes were designed, synthesized, and characterized. Owing to the strong donor strength of axial NHC ligands in stabilizing the trans MCRR′/MNR moiety, these complexes showed unprecedently high catalytic activity towards alkene cyclopropanation, carbene CH, NH, SH, and OH insertion, alkene aziridination, and nitrene CH insertion with turnover frequencies up to 1950 min−1. The use of chiral [Ru(D4‐Por)(BIMe)2] (1 g) as a catalyst led to highly enantioselective carbene/nitrene transfer and insertion reactions with up to 98 % ee. Carbene modification of the N terminus of peptides at 37 °C was possible. DFT calculations revealed that the trans axial NHC ligand facilitates the decomposition of diazo compounds by stabilizing the metal–carbene reaction intermediate.
Rapid Generation of Cell Gradients by Utilizing Solely Nanotopographic Interactions on a Bio‐Inert Glass Surface
Authors: Yang Gao , Cao Yanhua , Fan Junbing , Liu Hongliang , Zhang Feilong , Zhang Pengchao , Huang Chao , Jiang Lei , Wang Shutao
Published: February 2014

The control of cell gradients is critical for understanding many biological systems and realizing the unique functionality of biomimetic implants. Herein, we report a nanotopographic gradient strategy that can rapidly generate cell gradients on a nanodendritic silica substrate without any chemical modification. We can achieve controllable cell gradients within only half an hour of cell incubation solely induced by the topographic effect of the gradient nanodendrites. We also demonstrate that cell gradients can be modulated by the combination of nanotopographic and chemical gradients. The results reveal that the enhanced topographic interactions between the nanodentritic structure and nanoscaled filopodia of the cells mainly contribute to the generation of cell gradients.
Accurate Zygote‐Specific Discrimination of Single‐Nucleotide Polymorphisms Using Microfluidic Electrochemical DNA Melting Curves
Authors: Yang Allen H. J. , Hsieh Kuangwen , Patterson Adriana S. , Ferguson B. Scott , Eisenstein Michael , Plaxco Kevin W. , Soh H. Tom
Published: February 2014

We report the first electrochemical system for the detection of single‐nucleotide polymorphisms (SNPs) that can accurately discriminate homozygous and heterozygous genotypes using microfluidics technology. To achieve this, our system performs real‐time melting‐curve analysis of surface‐immobilized hybridization probes. As an example, we used our sensor to analyze two SNPs in the apolipoprotein E (ApoE) gene, where homozygous and heterozygous mutations greatly affect the risk of late‐onset Alzheimer’s disease. Using probes specific for each SNP, we simultaneously acquired melting curves for probe–target duplexes at two different loci and thereby accurately distinguish all six possible ApoE allele combinations. Since the design of our device and probes can be readily adapted for targeting other loci, we believe that our method offers a modular platform for the diagnosis of SNP‐based diseases and personalized medicine.
Palladium‐Catalyzed CH Fluorosilylation of 2‐Phenylpyridines: Synthesis of Silafluorene Equivalents
Authors: Xiao Qing , Meng Xiangtai , Kanai Motomu , Kuninobu Yoichiro
Published: February 2014

Treatment of 2‐phenylpyridines with amino(1,3,2‐dioxaborolan‐2‐yl)diphenylsilane produced fluorosilylated 2‐phenylpyridines in good to excellent yields under palladium catalysis. This reaction is the first example of CH fluorosilylation. Single‐crystal X‐ray structure analysis revealed a Lewis acid–base interaction between the silicon and nitrogen atoms, and the obtained fluorosilylated products are silafluorene equivalents. The fluorosilylated products showed stronger fluorescence than the corresponding silafluorene derivative.
Ruthenium‐Catalyzed Oxidative Kinetic Resolution of Unactivated and Activated Secondary Alcohols with Air as the Hydrogen Acceptor at Room Temperature
Authors: Mizoguchi Hirotaka , Uchida Tatsuya , Katsuki Tsutomu
Published: February 2014

Enantiopure alcohols are versatile building blocks for asymmetric synthesis and the kinetic resolution (KR) of racemic alcohols is a reliable method for preparing them. Although many KR methods have been developed, oxidative kinetic resolution (OKR), in which dioxygen is used as the hydrogen acceptor, is the most atom‐efficient. Dioxygen is ubiquitous in air, which is abundant and safe to handle. Therefore, OKR with air has been intensively investigated and the OKR of benzylic alcohols was recently achieved by using an Ir catalyst without any adjuvant. However, the OKR of unactivated alcohols remains a challenge. An [(aqua)Ru(salen)] catalyzed OKR with air as the hydrogen acceptor was developed, in which the aqua ligand is exchanged with alcohol and the Ru complex undergoes single electron transfer to dioxygen and subsequent alcohol oxidation. This OKR can be applied without any adjuvant to activated and unactivated alcohols with good to high enantioselectivity. The unique influence of substrate inhibition on the enantioselectivity of the OKR is also described.
Highly Enantioselective Rhodium(I)‐Catalyzed Activation of Enantiotopic Cyclobutanone CC Bonds
Authors: Souillart Laetitia , Parker Evelyne , Cramer Nicolai
Published: February 2014

The selective functionalization of carbon–carbon σ bonds is a synthetic strategy that offers uncommon retrosynthetic disconnections. Despite progress in CC activation and its great importance, the development of asymmetric reactions lags behind. Rhodium(I)‐catalyzed selective oxidative additions into enantiotopic CC bonds in cyclobutanones are reported. Even operating at a reaction temperature of 130 °C, the process is characterized by outstanding enantioselectivity with the e.r. generally greater than 99.5:0.5. The intermediate rhodacycle is shown to react with a wide variety of tethered olefins to deliver complex bicyclic ketones in high yields.
Monolayer HNb3O8 for Selective Photocatalytic Oxidation of Benzylic Alcohols with Visible Light Response
Authors: Liang Shijing , Wen Linrui , Lin Sen , Bi Jinhong , Feng Pingyun , Fu Xianzhi , Wu Ling
Published: February 2014

Monolayer HNb3O8 2D nanosheets have been used as highly chemoselective and active photocatalysts for the selective oxidation of alcohols. The nanosheets exhibit improved photocatalytic activity over their layered counterparts. Results of in situ FTIR, DRS, ESR, and DFT calculations show the formation of surface complexes between the Lewis acid sites on HNb3O8 2D nanosheets and alcohols. These complexes play a key role in the photocatalytic activity of the material. Furthermore, the unique structural features of the nanosheets contributed to their high photocatalytic activity. An electron transition from the coordinated alcohol species to surface Nb atoms takes place and initiates the aerobic oxidation of alcohols with high product selectivity under visible light irradiation. This reaction process is distinct from that of classic semiconductor photocatalysis.
Probing the Zintl–Klemm Concept: A Combined Experimental and Theoretical Charge Density Study of the Zintl Phase CaSi
Authors: Kurylyshyn Iryna M. , Fässler Thomas F. , Fischer Andreas , Hauf Christoph , Eickerling Georg , Presnitz Manuel , Scherer Wolfgang
Published: February 2014

The nature of the chemical bonds in CaSi, a textbook example of a Zintl phase, was investigated for the first time by means of a combined experimental and theoretical charge density analysis to test the validity of the Zintl–Klemm concept. The presence of covalent SiSi interactions, which were shown by QTAIM analysis, supports this fundamental bonding concept. However, the use of an experimental charge density study and theoretical band structure analyses give clear evidence that the cation–anion interaction cannot be described as purely ionic, but also has partially covalent character. Integrated QTAIM atomic charges of the atoms contradict the original Zintl–Klemm concept and deliver a possible explanation for the unexpected metallic behavior of CaSi.
Formal Aminocyanation of α,β‐Unsaturated Cyclic Enones for the Efficient Synthesis of α‐Amino Ketones
Authors: Sun Chunrui , O'Connor Matthew J. , Lee Daesung , Wink Donald J. , Milligan Robert D.
Published: February 2014

Installation of amino functionality on organic molecules through direct CN bond formation is an important research objective. To achieve this goal, a 1,2‐aminocyanation reaction was developed. The reaction occurs through the formation of pyrazolines by means of a formal dipolar cycloaddition of cyclic α,β‐unsaturated ketones with lithium trimethylsilyldiazomethane followed by novel protonolytic NN bond cleavage under mild conditions. This two‐step process provides a diverse array of structurally complex free and mono‐alkylated α‐amino ketones in excellent yields.
The Topochemical Pseudomorphosis of a Chloride into a Bismuthide
Authors: Kaiser Martin , Rasche Bertold , Ruck Michael
Published: February 2014

The heterogeneous reaction of crystals of the novel intermetallic subhalide Bi12Rh3Cl2 with a solution of n‐butyllithium at 70 °C led to the complete topochemical exchange of chloride ions for bismuth atoms, that is, the transformation into the isostructural metastable intermetallic superconductor Bi14Rh3. The crystals underwent the reductive pseudomorphosis almost unchanged except some fissures perpendicular to the a‐axis. Detailed inspections of the transformed crystals by electron microscopy indicated no volume defects that would indicate internal chemical reactions. Thus, extensive mass transport must have occurred through the seemingly dense crystal structure. An efficient transport mechanism, based on an unusual breathing mode of the three‐dimensional network formed by edge‐sharing [RhBi8] cubes and antiprisms, is proposed. The replacement of ionic interaction in the chloride by metallic bonding in the binary intermetallic compound closes the pseudo gap in the density of states at the Fermi level. As a result, the rod‐packing of conducting, yet electrically isolated strands of [RhBi8] cubes in Bi12Rh3Cl2 turns into the three‐dimensional metal Bi14Rh3.
A Photochromic Agonist for μ‐Opioid Receptors
Authors: Schönberger Matthias , Trauner Dirk
Published: February 2014

Opioid receptors (ORs) are widely distributed in the brain, the spinal cord, and the digestive tract and play an important role in nociception. All known ORs are G‐protein‐coupled receptors (GPCRs) of family A. Another well‐known member of this family, rhodopsin, is activated by light through the cis/trans isomerization of a covalently bound chromophore, retinal. We now show how an OR can be combined with a synthetic azobenzene photoswitch to gain light sensitivity. Our work extends the reach of photopharmacology and outlines a general strategy for converting Family A GPCRs, which account for the majority of drug targets, into photoreceptors.
Concurrent Block Copolymer Polymersome Stabilization and Bilayer Permeabilization by Stimuli‐Regulated “Traceless” Crosslinking
Authors: Wang Xiaorui , Liu Guhuan , Hu Jinming , Zhang Guoying , Liu Shiyong
Published: February 2014

The fabrication of block copolymer (BCP) vesicles (polymersomes) exhibiting synchronized covalent crosslinking and bilayer permeabilization remains a considerable challenge as crosslinking typically leads to compromised membrane permeability. Herein it is demonstrated how to solve this dilemma by employing a stimuli‐triggered crosslinking strategy with amphiphilic BCPs containing photolabile carbamate‐caged primary amines. Upon self‐assembling into polymersomes, light‐triggered self‐immolative decaging reactions release primary amine moieties and extensive amidation reactions then occur due to suppressed amine pKa within hydrophobic milieu. This leads to serendipitous vesicle crosslinking and the process is associated with bilayer hydrophobicity‐to‐hydrophilicity transition and membrane permeabilization.
Combinatorially Designed Lipid‐like Nanoparticles for Intracellular Delivery of Cytotoxic Protein for Cancer Therapy
Authors: Wang Ming , Alberti Kyle , Sun Shuo , Arellano Carlos Luis , Xu Qiaobing
Published: February 2014

An efficient and safe method to deliver active proteins into the cytosol of targeted cells is highly desirable to advance protein‐based therapeutics. A novel protein delivery platform has been created by combinatorial design of cationic lipid‐like materials (termed “lipidoids”), coupled with a reversible chemical protein engineering approach. Using ribonuclease A (RNase A) and saporin as two representative cytotoxic proteins, the combinatorial lipidoids efficiently deliver proteins into cancer cells and inhibit cell proliferation. A study of the structure–function relationship reveals that the electrostatic and hydrophobic interactions between the lipidoids and the protein play a vital role in the formation of protein–lipidoid nanocomplexes and intracellular delivery. A representative lipidoid (EC16‐1) protein nanoparticle formulation inhibits cell proliferation in vitro and suppresses tumor growth in a murine breast cancer model.
Compatibilization of polypropylene/polyamide 6 blends using new synthetic nanosized talc fillers: Morphology, thermal, and mechanical properties
Authors: Yousfi Mohamed , Livi Sebastien , Dumas Angela , Crépin‐Leblond Jerome , Greenhill‐Hooper Mike , Duchet‐Rumeau Jannick
Published: February 2014

New synthetic nanotalc and a commercially available natural fine talc (Luzenac© A3) were chosen in order to establish a comparative study in terms of their contributions on the improvement of the morphology as well as the final properties of PP/PA6 blends prepared by melt processing. At first, the TEM and SEM micrographs showed that both talc particles have a preferential affinity for the more hydrophilic polyamide 6 phase compared with the continuous PP matrix. Moreover, in both cases, the addition of talc fillers induces a significant decrease of the size of the PA6 domains but the better compatibilization efficiency was obtained in the presence of synthetic nanotalc particles. In this work, the positive change induced by the talc nanofillers on the crystallization kinetics and final morphology was highlighted. In addition, compared with natural talc, a highly level of dispersion of talc layers has been obtained with the synthetic nanotalc which is more hydrophilic. Thus, this better dispersion greatly improves the thermal stability of PP/PA6 blends and leads to better mechanical properties (+ 40% in Young's modulus). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40453.
Fabrication of graphene supported carbon‐coating cobalt and carbon nanoshells for adsorption of toxic gases and smoke
Authors: Hong Ningning , Song Lei , Wang Bibo , Yuan Bibe , Shi Yongqian , Hu Yuan
Published: February 2014

Graphene‐supported carbon‐coating cobalt and carbon nanoshells (Co/C‐GNS and CNS‐GNS) were fabricated and their applications in absorbing toxic gases and smoke have been investigated. Co3O4‐loaded reduced graphite oxide was first prepared via a coprecipitation process, then carbon coatings on cobalt nanoparticles were fabricated by a catalytic carbonization process. The obtained hybrids were characterized by X‐ray diffraction, transmission electron microscopy, Raman spectroscopy, N2 absorption/desorption, and thermogravimetric analysis. Co/C core/shell structure and hollow carbon nanoshells in the size range of 15–22 nm were anchored onto the graphene surfaces. The resultant Co/C‐GNS and CNS‐GNS performed an important function in CO removal and smoke suppression during the combustion of acrylonitrile‐butadiene‐styrene. The good performance could be attributed to the combination effect of physical barrier of the GNS, porosity structure of the carbon nanoshells, and carbonization of the Co nanoparticles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40457.
Synthesis and characterization of maleated glycidyl 3‐pentadecenyl phenyl ether as a functionalized plasticizer for styrene–butadiene rubber/carbon black/silica composites
Authors: Gong Zhan‐Lin , Cen Lan , Wang Shu‐Ting , Chen Fu‐Lin
Published: February 2014

Maleated glycidyl 3‐pentadecenyl phenyl ether (M‐GPPE) was synthesized from glycidyl 3‐pentadecenyl phenyl ether (GPPE), a renewable derivative from cardanol, with maleic anhydride (MAH) by grafting copolymerization. The resulting M‐GPPE was used as a functionalized plasticizer for a styrene–butadiene rubber (SBR)/carbon black (CB)/silica composite. The effects of M‐GPPE on the development of the filler network, the extent of silica dispersion, the curing characteristics, and the mechanical performance of the composites were studied. Meanwhile, a comparative study was performed between M‐GPPE and aromatic oil, a traditional plasticizer used in SBR filler formulations. Gel permeation chromatography and IR and 1H‐NMR analysis results confirmed the occurrence of the grafting reaction between GPPE and MAH and the potential structure of M‐GPPE. The thermostability of GPPE was improved by grafting copolymerization with MAH, as shown by thermogravimetric analysis results. The presence of M‐GPPE resulted in a shorter curing time and better aging properties in the SBR composite compared with GPPE. The mechanical properties, dynamic mechanical analysis, and transmission electron microscopy analysis showed that the maleate of GPPE could enhance the compatibility between SBR and silica, improve the dispersion of silica in SBR, and partially replace the aromatic oil in the SBR/CB/silica composite formulation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40462.
Surface molecularly imprinted polymer prepared by reverse atom transfer radical polymerization for selective adsorption indole
Authors: Cao Yang , Liu Lukuan , Xu Wanzhen , Wu Xiangyang , Huang Weihong
Published: February 2014

The preparation of indole molecularly imprinted polymers (indole‐MIPs) using 4‐vinylpyridine as functional monomer, silica gel as matrix were used to adsorb indole from fuel oil specifically. The reverse atom transfer radical polymerization (RATRP) technology was introduced to prepare the surface molecularly imprinted polymers, and the precipitation polymerization was adopted in the preparation process. The obtained indole‐MIPs were characterized by nitrogen adsorption, Fourier transform infrared spectrometry and scanning electron microscopy. The results show that indole‐MIPs were provided with the larger surface areas and more pores. The adsorption capacity of indole‐MIPs was 31.80 mg g−1 at 298 K, and the adsorption equilibrium was reached in a short time. The adsorption process was spontaneous by thermodynamic analysis, and an appropriate decrease in temperature could enhance the adsorption capacity. The adsorption process obeyed pseudo‐second‐order kinetic model by kinetics analysis. The isotherm analysis results show that both Langmuir and Sips equations were suitable to experimental data. The selective adsorption and reusable performance of indole‐MIPs were favorable. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40473.
Improving the thermal and mechanical properties of poly(vinyl butyral) through the incorporation of acid‐treated single‐walled carbon nanotubes
Authors: Zanjanijam Ali Reza , Hajian Morteza , Koohmareh Gholam Ali
Published: February 2014

In this study, to investigate the effect of functionalized carbon nanotubes on the thermal and mechanical properties of the poly(vinyl butyral) (PVB) resin, PVB/functionalized single‐walled carbon nanotube (f‐SWCNT) composites were fabricated by a solution casting method. The functionalized nanotubes were prepared by acid treatment. The formation of oxygen‐containing functional groups on the surface of the nanotubes was confirmed by Fourier transform infrared spectroscopy, energy‐dispersive X‐ray spectroscopy, and scanning electron microscopy (SEM) measurements. SEM analysis also showed that the nanotubes were dispersed well in the PVB matrix. The thermal stability of the composites were investigated with thermogravimetric analysis, and the results show better stability for PVB in the presence of a very low content of the f‐SWCNTs. The prepared composites exhibited a significant increase in the temperature of degradation at 50 wt % loss and also in the onset temperature and decomposition temperature at the maximum rate of weight loss of butyral degradation. A significant enhancement in the mechanical properties was also achieved for these prepared composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40481.
Flexible‐elastic copolymerized polyurethane‐tannin foams
Authors: Basso Maria Cecilia , Giovando Samuele , Pizzi Antonio , Pasch Harald , Pretorius Nadine , Delmotte Luc , Celzard Alain
Published: February 2014

Open cell foams obtained by the simultaneous coreaction of condensed flavonoid tannins with an alkoxylated fatty amine and polymeric diphenylmethane isocyanate yielded highly flexible/elastic polyurethane foams. Copolymerized amine/isocyanate/tannin oligomers were identified by 13C NMR and MALDI‐TOF spectroscopy. In general, between 30% and 50% of natural tannins is added to the components used to obtain polymerisation of the polyurethane. The characteristic of these new, partially biosourced polyurethanes is that the tannin present slows down burning, some of them can be made flame self‐extinguishing and if burning they neither flow nor asperge flaming material around, contrary to what occurs with normal polyurethanes. This limits the possibility of transmitting fire to other materials in the same environment. Cyclic compression tests were carried out showing that after 50 cycles foam recovery was in excess of 80%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40499.
Nonsalt 1‐(arylmethyloxy)pyrene photoinitiators capable of initiating cationic polymerization
Authors: Uchida Naoki , Nakano Haruka , Igarashi Tetsutaro , Sakurai Tadamitsu
Published: February 2014

Analysis of photoproducts derived from 1‐(methoxynaphthalen‐1‐ylmethyloxy)pyrene initiators and polymer end groups demonstrated that methoxynaphthalen‐1‐ylmethyl carbocation is involved in the initiation steps for both styrene (St) and cyclohexene oxide (CHO) polymerization. Charge transfer from the pyrenyloxy oxygen atom to the methoxynaphthalen‐1‐ylmethyl chromophore in the singlet excited state is assumed to be responsible for the efficient generation of the carbocation species, which also initiates the copolymerization of St and CHO. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40510.
Synthesis of Ultra‐Stable Fluorescent Carbon Dots from Polyvinylpyrrolidone and Their Application in the Detection of Hydroxyl Radicals
Authors: Ren Xiangling , Liu Jing , Meng Xianwei , Wei Jianfei , Liu Tianlong , Tang Fangqiong
Published: February 2014

Highly biocompatible and highly photostable fluorescent carbon dots (C dots) were obtained through a simple and nontoxic one‐pot hydrothermal method. Polyvinylpyrrolidone, a common and low‐cost biocompatibility reagent, was used as the only carbon source for the first time. The resulting water‐soluble C dots showed a quantum yield of up to 23.58 % with low cytotoxicity, favorable photoluminescent properties, and good photostability. Importantly, the fluorescence intensities of the C dots were quite stable in high‐salt conditions and over a broad pH range (3.0–10.5). The as‐prepared C dots have been demonstrated to be an excellent probe for hydroxyl radicals sensing based on the fluorescence quenching with great sensitivity and specificity. This opens up a new application field for C dots.
Synthesis, Structure and Bonding, Optical Properties of Ba4MTrQ6 (M=Cu, Ag; Tr=Ga, In; Q=S, Se)
Authors: Lei Xiao‐Wu , Yang Min , Xia Sheng‐Qing , Liu Xiao‐Cun , Pan Ming‐Yan , Li Xin , Tao Xu‐Tang
Published: February 2014

Four new quaternary chalcogenides, Ba4AgGaS6 (1), Ba4AgGaSe6 (2), Ba4CuInS6 (3), and Ba4AgInS6 (4), were synthesized by solid‐state reactions and their structures were characterized through single‐crystal X‐ray diffraction. In spite of their similar chemical compositions, the flexible arrangement between the transition metals and the triel atoms leads to subtle differences in their polyanion structures. All structures feature similar [MTrQ6]8− 1D polyanionic chains (M=Cu, Ag; Tr=Ga, In; Q=S, Se), which are constructed from corner‐sharing MQ4 or TrQ4 tetrahedra. However, the transition metals and triels are mixed in 1, 2, and 3, but they occupy independent crystallographic sites in 4. As a result, compounds 1–3 belong to the known Ba2CoS3 (Pnma No. 62) or Ba2MnS3 (Pnma No. 62) class, whereas 4 crystallizes in its own structural type within the monoclinic P21/c (No. 14) space group. The structural relationship among these new phases was also studied with the aid of DFT calculations and related optical properties are presented as well.
Excellent Electrochemical Properties of Yolk–Shell MoO3 Microspheres Formed by Combustion of Molybdenum Oxide–Carbon Composite Microspheres
Authors: Ko You Na , Park Seung Bin , Kang Yun Chan
Published: February 2014

Yolk–shell MoO3 microspheres are prepared by a two‐step process in which molybdenum oxide–carbon (MoOx–C) composite microspheres are first obtained by spray pyrolysis, followed by combustion at 400 °C in air. The yolk–shell microspheres exhibit excellent electrochemical properties and structural stability.
Hypervalent Iodine‐Catalyzed Oxidative Functionalizations Including Stereoselective Reactions
Authors: Singh Fateh V. , Wirth Thomas
Published: February 2014

Hypervalent iodine chemistry is now a well‐established area of organic chemistry. Novel hypervalent iodine reagents have been introduced in many different transformations owing to their mild reaction conditions and environmentally friendly nature. Recently, these reagents have received particular attention because of their applications in catalysis. Numerous hypervalent iodine‐catalyzed oxidative functionalizations such as oxidations of various alcohols and phenols, α‐functionalizations of carbonyl compounds, cyclizations, and rearrangements have been developed successfully. In these catalytic reactions stoichiometric oxidants such as mCPBA or oxone play a crucial role to generate the iodine(III) or iodine(V) species in situ. In this Focus Review, recent developments of hypervalent iodine‐catalyzed reactions are described including some asymmetric variants. Catalytic reactions using recyclable hypervalent iodine catalysts are also covered.
Sex prevalence of major congenital anomalies in the United Kingdom: A national population‐based study and international comparison meta‐analysis
Authors: Sokal Rachel , Tata Laila J. , Fleming Kate M.
Published: February 2014

Background

The aim of this study was to assess sex differences in major congenital anomaly (CA) diagnoses within a national population sample; to examine the influence of sociodemographic and maternal factors on these risks; and to conduct a meta‐analysis using estimates from other population‐based studies.

Methods

We conducted a population‐based study in a United Kingdom research database of prospectively collected primary care data (The Health Improvement Network) including children born 1990 to 2009 (n = 794,169) and identified major CA diagnoses using EUROCAT (European Surveillance of Congenital Anomalies) classification. Prevalence ratios (PR) were used to estimate the risk of CA in males compared with females for any CA, system‐specific subgroups and specific CA diagnoses. In a subpopulation of children whose medical records were linked to their mothers', we assessed the effect of adjusting for sociodemographic and maternal factors on sex odds ratios. PRs were pooled with measures from previously published studies.

Results

The prevalence of any CA was 307/10,000 in males (95% CI, 302–313) and 243/10,000 in females (95% CI, 238–248). Overall the risk of any CA was 26% greater in males (PR (male: female) 1.26, 95% CI, 1.23–1.30) however there was considerable variation across specific diagnoses. The magnitude and direction of risk did not change for any specific CA upon adjustment for sociodemographic and maternal factors. Our PRs were highly consistent with those from previous studies.

Conclusion

The overall risk of CA is greater in males than females, although this masked substantial variation by specific diagnoses. Sociodemographic and maternal factors do not appear to affect these risks. Birth Defects Research (Part A) 100:79–91, 2014. © 2014 Wiley Periodicals, Inc.
Key Learnings from the Endocrine Disruptor Screening Program (EDSP) Tier 1 Rodent Uterotrophic and Hershberger Assays
Authors: Marty M. Sue , O'Connor John C.
Published: February 2014

In 2009, companies began screening compounds using the US Environmental Protection Agency's Endocrine Disruptor Screening Program (EDSP). EDSP has two tiers: Tier 1 includes 11 assays to identify compounds with potential endocrine activity. This article describes two laboratories' experiences conducting Tier 1 uterotrophic and Hershberger assays. The uterotrophic assay detects estrogen receptor agonists through increases in uterine weight. The advantages of the uterotrophic rat models (immature vs. adult ovariectomized) and exposure routes are discussed. Across 29 studies, relative differences in uterine weights in the vehicle control group and 17α‐ethynylestradiol–positive control group were reasonably reproducible. The Hershberger assay detects androgen receptor (AR) agonists, antagonists, and 5α‐reductase inhibitors through changes in accessory sex tissue (AST) weights. Across 23 studies, AST weights were relatively reproducible for the vehicle groups (baseline), testosterone propionate (TP) groups (androgenic response), and flutamide + TP groups (antiandrogenic response). In one laboratory, one and four compounds were positive in the androgenic and antiandrogenic portions of the assay, respectively. Each compound was also positive for AR binding. In the other laboratory, three compounds showed potential antiandrogenic activity, but each compound was negative for AR binding and did not fit the profile for 5α‐reductase inhibition. These compounds induced hepatic enzymes that enhanced testosterone metabolism/clearance, resulting in lower testosterone and decreased capacity to maintain AST weights. The Hershberger androgenic and antiandrogenic performance criteria were generally attainable. Overall, the uterotrophic and Hershberger assays were easily adopted and function as described for EDSP screening, although the mode of action for positive results may not be easily determined.
Beyond transcriptional silencing: Is methylcytosine a widely conserved eukaryotic DNA elimination mechanism?
Authors: Bracht John R.
Published: February 2014

Methylation of cytosine DNA residues is a well‐studied epigenetic modification with important roles in formation of heterochromatic regions of the genome, and also in tissue‐specific repression of transcription. However, we recently found that the ciliate Oxytricha uses methylcytosine in a novel DNA elimination pathway important for programmed genome restructuring. Remarkably, mounting evidence suggests that methylcytosine can play a dual role in ciliates, repressing gene expression during some life‐stages and directing DNA elimination in others. In this essay, I describe these recent advances in the DNA methylation field and discuss whether this unexpected novel role for methylcytosine in DNA elimination might be more widely conserved in eukaryotic biology, particularly in apoptotic pathways.
Chlorite dismutases – a heme enzyme family for use in bioremediation and generation of molecular oxygen
Authors: Hofbauer Stefan , Schaffner Irene , Furtmüller Paul G. , Obinger Christian
Published: February 2014

Chlorite is a serious environmental concern, as rising concentrations of this harmful anthropogenic compound have been detected in groundwater, drinking water, and soil. Chlorite dismutases (Clds) are therefore important molecules in bioremediation as Clds catalyze the degradation of chlorite to chloride and molecular oxygen. Clds are heme b‐containing oxidoreductases present in numerous bacterial and archaeal phyla. This review presents the phylogeny of functional Clds and Cld‐like proteins, and demonstrates the close relationship of this novel enzyme family to the recently discovered dye‐decolorizing peroxidases. The available X‐ray structures, biophysical and enzymatic properties, as well as a proposed reaction mechanism, are presented and critically discussed. Open questions about structure‐function relationships are addressed, including the nature of the catalytically relevant redox and reaction intermediates and the mechanism of inactivation of Clds during turnover. Based on analysis of currently available data, chlorite dismutase from “Candidatus Nitrospira defluvii” is suggested as a model Cld for future application in biotechnology and bioremediation. Additionally, Clds can be used in various applications as local generators of molecular oxygen, a reactivity already exploited by microbes that must perform aerobic metabolic pathways in the absence of molecular oxygen. For biotechnologists in the field of chemical engineering and bioremediation, this review provides the biochemical and biophysical background of the Cld enzyme family as well as critically assesses Cld's technological potential.
The role of substrate binding pocket residues phenylalanine 176 and phenylalanine 196 on Pseudomonas sp. OX1 toluene o‐xylene monooxygenase activity and regiospecificity
Authors: Sönmez Burcu , Yanık‐Yıldırım K. Cansu , Wood Thomas K. , Vardar‐Schara Gönül
Published: February 2014

Saturation mutagenesis was used to generate eleven substitutions of toluene‐o‐xylene monooxygenase (ToMO) at alpha subunit (TouA) positions F176 and F196 among which nine were novel: F176H, F176N, F176S, F176T, F196A, F196L, F196T, F196Y, F196H, F196I, and F196V. By testing the substrates phenol, toluene, and naphthalene, these positions were found to influence ToMO oxidation activity and regiospecificity. Specifically, TouA variant F176H was identified that had 4.7‐, 4.3‐, and 1.8‐fold faster hydroxylation activity towards phenol, toluene, and naphthalene, respectively, compared to native ToMO. The F176H variant also produced the novel product hydroquinone (61%) from phenol, made twofold more 2‐naphthol from naphthalene (34% vs. 16% by the wild‐type ToMO), and had the regiospecificity of toluene changed from 51% to 73% p‐cresol. The TouA F176N variant had the most para‐hydroxylation capability, forming p‐cresol (92%) from toluene and hydroquinone (82%) from phenol as the major product, whereas native ToMO formed 30% o‐cresol, 19% m‐cresol, and 51% of p‐cresol from toluene and 100% catechol from phenol. For naphthalene oxidation, TouA variant F176S exhibited the largest shift in the product distribution by producing threefold more 2‐naphthol. Among the other F196 variants, F196L produced catechol from phenol two times faster than the wild‐type enzyme. The TouA F196I variant produced twofold less o‐cresol and 19% more p‐cresol from toluene, and the TouA F196A variant produced 62% more 2‐naphthol from naphthalene compared to wild‐type ToMO. Both of these positions have never been studied through the saturation mutagenesis and some of the best substitutions uncovered here have never been predicted and characterized for aromatics hydroxylation. Biotechnol. Bioeng. 2014;111: 1506–1512. © 2014 Wiley Periodicals, Inc.
Subtile Verteidigungsstrategien in Pflanzen
Authors: Mithöfer Axel , Schuman Meredith C.
Published: February 2014

Pflanzen verteidigen sich gegen herbivore Angriffe sehr effizient durch den Einsatz von Chemie. Neben Verbindungen, die direkt auf den Aggressor wirken, produziert die von pflanzenfressenden Arthropoden befallene Pflanze auch niedermolekulare, flüchtige Stoffe, meistens Terpene und Acetogenine, die an die Umgebung abgegeben werden. Diese wirken als Signalstoffe mit unterschiedlichen Funktionen. So können sie einerseits Räuber oder Parasitoide der nächsthöheren trophischen Ebene anlocken, die die fressenden Herbivoren angreifen und somit die befallenen Pflanzen indirekt verteidigen; andererseits können solche Duftstoffe von benachbarten Teilen derselben Pflanzen wahrgenommen werden. Diese noch unbefallenen Bereiche der Pflanze können sich dann entsprechend wappnen und sind schneller in der Lage, ihre Verteidigung im Bedarfsfall zu aktivieren. Eine Anwendung des Prinzips einer natürlichen pflanzlichen Verteidigung in der Landwirtschaft ist durchaus denkbar.
Hochwasser – ein unterschätztes Risiko
Authors: Hollert Henner , Brinkmann Markus , Hudjetz Sebastian , Cofalla Catrina , Schüttrumpf Holger
Published: February 2014

Hochwasserereignisse stellen in überschwemmungsgefährdeten Gebieten immer wieder eine Bedrohung für Leben, Gesundheit und Eigentum der Bevölkerung sowie für Industrie, Landwirtschaft und Infrastruktureinrichtungen dar. Problematisch sind dabei aber nicht nur diese eher direkten Auswirkungen: Historische Belastungen – tickende “Zeitbomben” – im Sediment können durch Erosion erneut in die Gewässersäule gelangen. Dort können sie die Gewässerqualität nachhaltig beeinträchtigen und die Gesundheit aquatischer Organismen und auch des Menschen gefährden. In diesem Artikel werden verschiedene Untersuchungen zum Schädigungspotenzial von Hochwassern und speziell die Befunde einer kombinierten hydrologischen und ökotoxikologischen Untersuchungsmethodik vorgestellt.
Domestikation im Zeitraffer: Wie die Gerste zu mehr Körnern kam
Authors: Hensel Götz , Kumlehn Jochen
Published: February 2014

Wildgerste ist 2‐zeilig, Kulturgerste meist 6‐zeilig und damit ertragreicher. Doch wie kommt diese Zuchtform zu mehr Körnern? Aktuelle Forschungsergebnisse zeigen, dass ein durch das Vrs1‐Gen codierter Transkriptionsfaktor die Entwicklung seitlich positionierter Ährchen unterdrückt, während die 6‐Zeiligkeit auf einer verminderten Genaktivität beruht. Unterdrückt man das Vrs1‐Gen durch RNAi, werden Wildtypen zu Zuchtformen – die Domestikation wird im Schnelldurchlauf nachvollzogen.
Evaluation of fitness levels of children with a diagnosis of acute leukemia and lymphoma after completion of chemotherapy and autologous hematopoietic stem cell transplantation
Authors: Bianco Antonino , Patti Antonino , Thomas Ewan , Palma Romilda , Maggio Maria Cristina , Paoli Antonio , Palma Antonio
Published: February 2014

The aim of this study was to assess the fitness levels and possible deficits in physical performance in children with a diagnosis of childhood acute leukemia and lymphoma after 10 months of therapy ending through a specific test battery. A total of 58 subjects were enrolled in this study. The experimental group (EG) (7.55 ± 2.43 years; 41.8 ± 16.37 kg; 144.6 ± 10.21 cm) consisted of 18 children with diagnosed leukemia and lymphoma after completion of 10 months of therapy intervention and 40 healthy children who were enrolled in a control group (CG) (7.92 ± 1.78 years; 37.4 ± 12.37 kg; 140.6 ± 12.61 cm). A testing battery including the standing broad jump; the sit‐up test; the 4 × 10 m shuttle run test, and the hand grip strength test were administered to both groups. An unpaired t‐test was adopted to determine differences and the Pearson product moment was administered when appropriate. Results of the EG were generally lower when compared to the CG. Significant differences were identified for the standing broad jump (P < 0.05); 4 × 10 m shuttle run (P < 0.05); hand grip test DX (P < 0.05), and hand grip test SX (P < 0.05). No significant differences were found between the sit‐up tests. Pearson product moment correlation revealed a good interaction for all EG participants. Findings suggest that the proposed testing battery could be an appropriate tool to evaluate residual fitness levels in children with previous hematological malignancies. However, our results have to be confirmed with a larger number of participants with the same diagnosis of our EG.
Two BRM promoter insertion polymorphisms increase the risk of early‐stage upper aerodigestive tract cancers
Authors: Wong Kit Man , Qiu Xiaoping , Cheng Dangxiao , Azad Abul Kalam , Habbous Steven , Palepu Prakruthi , Mirshams Maryam , Patel Devalben , Chen Zhuo , Roberts Heidi , Knox Jennifer , Marquez Stephanie , Wong Rebecca , Darling Gail , Waldron John , Goldstein David , Leighl Natasha , Shepherd Frances A. , Tsao Ming , Der Sandy , Reisman David , Liu Geoffrey
Published: February 2014

Brahma (BRM) has a key function in chromatin remodeling. Two germline BRM promoter insertion–deletion polymorphisms, BRM‐741 and BRM‐1321, have been previously associated with an increased risk of lung cancer in smokers and head and neck cancer. To further evaluate their role in cancer susceptibility particularly in early disease, we conducted a preplanned case–control study to investigate the association between the BRM promoter variants and stage I/II upper aerodigestive tract (UADT) cancers (i.e., lung, esophageal, head and neck), a group of early‐stage malignancies in which molecular and genetic etiologic factors are poorly understood. The effects of various clinical factors on this association were also studied. We analyzed 562 cases of early‐stage UADT cancers and 993 matched healthy controls. The double homozygous BRM promoter variants were associated with a significantly increased risk of early stage UADT cancers (adjusted odds ratio [aOR], 2.46; 95% confidence interval [CI], 1.7–3.8). This association was observed in lung (aOR, 2.61; 95% CI, 1.5–4.9) and head and neck (aOR, 2.75; 95% CI, 1.4–5.6) cancers, but not significantly in esophageal cancer (aOR, 1.66; 95% CI, 0.7–5.8). There was a nonsignificant trend for increased risk in the heterozygotes or single homozygotes. The relationship between the BRM polymorphisms and early‐stage UADT cancers was independent of age, sex, smoking status, histology, and clinical stage. These findings suggest that the BRM promoter double insertion homozygotes may be associated with an increased risk of early‐stage UADT cancers independent of smoking status and histology, which must be further validated in other populations.