bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biomimetic High‐Valent Mononuclear Nonheme Iron‐Oxo Chemistry
Authors: Klein Johannes E.M.N. , Que Lawrence 
Published: March 2016

Abstract

Herein we summarize the current status of efforts to synthesize and characterize high‐valent mononuclear nonheme iron‐oxo complexes that serve as models for intermediates found in the catalytic cycles of dioxygen activating nonheme iron enzymes. The main focus is the description and comparison of over 70 nonheme Fe
IV
(O) complexes synthesized thus far, and also included are few examples of Fe
III
(O), Fe
III
(OX), and Fe
V
(O) complexes, which are often generated with related or identical ligand frameworks as the Fe
IV
(O) complexes. Structural and spectroscopic parameters, as well as basic trends in oxygen‐ and hydrogen‐atom transfer reactivity, are described for subsets of complexes where systematic comparisons can be made.
N

‐Formimino‐
L
‐Glutamate Iminohydrolase from

P

seudomonas Aeruginosa
Authors: Martí‐Arbona Ricardo , Raushel Frank M 
Published: March 2016

Abstract

N
‐formimino‐
l
‐glutamate iminohydrolase, also known as
N
‐formimino‐
l
‐glutamate deiminase or
HutF
, catalyzes the hydrolysis of the imino group in
N
‐formimino‐
l
‐glutamate to produce
N
‐formyl‐
l
‐glutamate and ammonia. The enzyme from
Pseudomonas aeruginosa
is a dimer in solution and residues in the active site bind one divalent metal ion in a distorted trigonal bipyramidal coordination geometry.
Palladium‐Catalyzed Three‐Component Reaction of 3‐(Tri‐n‐ butylstannyl)allyl Acetates, Aldehydes, and Triorganoboranes: An Alternative to the Carbonyl Allylation Using α,γ‐Substituted Allylic Tin Reagents
Authors: Horino Yoshikazu , Sugata Miki , Abe Hitoshi 
Published: March 2016

AbstractA three‐component reaction of 3‐(tri‐n‐butylstannyl)allyl acetates, aldehydes, and triorganoboranes in the presence of a palladium‐Xantphos catalyst system predominately gave (E)‐anti‐homoallylic alcohols with high diastereoselectivity and good to high levels of alkene stereocontrol. An efficient chirality transfer was observed when an enantioenriched substrate was employed. The reaction was initiated by the formation of an allylic gem‐palladium/stannyl intermediate, which subsequently underwent allylation of the aldehyde by an allyltributyltin followed by a coupling reaction of the in‐situ‐generated (E)‐vinylpalladium acetate with the triorganoborane.magnified image
Transition Metal‐Free Approach to Propynenitriles and 3‐Chloropropenenitriles
Authors: Sharma Pawan K. , Ram Sita , Chandak Navneet 
Published: March 2016

AbstractA transition metal‐free, facile and efficient one‐pot protocol for the synthesis of propynenitriles from readily available 3‐chloropropenals is disclosed. The reaction conditions have also been optimized for the exclusive formation and isolation of 3‐chloropropenenitriles which are important building blocks in general and are intermediates in the synthesis of propynenitriles. The hallmark of the methodology is the use of non‐toxic reagents, milder, metal‐free and economically benign reaction conditions avoiding a harsh dehydration step while achieving excellent yields.magnified image
Variation in the human bicondylar angle
Authors: Waxenbaum Erin B. , Stock Michala K. 
Published: March 2016

ABSTRACTObjectivesInvestigations of the human femoral bicondylar angle have largely focused on interspecific differences and intrapopulation variation. This analysis assesses the range of variation in the bicondylar angle in humans across four populations, examining the effects of population, sex and age.Materials and MethodsThe bicondylar angle was assessed in four sex‐ and age‐balanced adult skeletal samples—modern Terry Whites and Blacks and archaeological South Dakota Arikara and Native Alaskans. The overall range of variation was assessed, and variation specific to population, sex, and age analyzed through ANOVAs and post hoc Tukey's honestly significant difference tests.ResultsA one‐way ANOVA highlights a significant effect of population on bicondylar angle; however, the only significant difference occurs between the Terry White and South Dakota Arikara samples. Sex displays a significant effect for the total pooled sample; yet, within population, the effect of sex is significant only among South Dakota Arikara. Age also has a significant effect on bicondylar angle in the total sample; however, the interaction between age and population is not significant.ConclusionThe results highlight the degree of variation in the bicondylar angle that exists intraspecifically. Differing degrees of variation due to sex suggest that sexual dimorphism is not universal in the human bicondylar angle. Furthermore, the broad impact of age on this feature is discussed, including the potential for plasticity through adulthood. By recognizing and explicitly examining morphological features that vary in human populations, we can appreciate the origins of variation and its implications for locomotor function, human diversity and evolutionary relationships. Am J Phys Anthropol 160:334–340, 2016. © 2016 Wiley Periodicals, Inc.
Solid‐State Conformational Flexibility at Work: Zipping and Unzipping within a Cyclic Peptoid Single Crystal
Authors: Meli Alessandra , Macedi Eleonora , De Riccardis Francesco , Smith Vincent J. , Barbour Leonard J. , Izzo Irene , Tedesco Consiglia 
Published: March 2016

AbstractA peptidomimetic compound undergoes a reversible single‐crystal‐to‐single‐crystal transformation upon guest release/uptake with the transformation involving a drastic conformational change. The extensive and reversible alteration in the solid state is connected to the formation of an unprecedented “CH–π zipper” which can reversibly open and close (through the formation of CH–π interactions), thus allowing for guest sensing.
Polymorphismus von Amyloidfibrillen in vivo
Authors: Annamalai Karthikeyan , Gührs Karl‐Heinz , Koehler Rolf , Schmidt Matthias , Michel Henri , Loos Cornelia , Gaffney Patricia M. , Sigurdson Christina J. , Hegenbart Ute , Schönland Stefan , Fändrich Marcus 
Published: March 2016

AbstractPolymorphismus ist ein weit verbreitetes Merkmal von in vitro gebildeten Amyloid‐artigen Fibrillen, doch blieb bislang unklar, ob Amyloidfibrillen in vivo ebenso von diesem Phänomen betroffen sind. Hier zeigen wir, dass sich verschiedene innerhalb eines Patienten gebildete Amyloidfibrillen erheblich in ihrer Morphologie unterscheiden können. Wir erhalten diesen Befund mit Amyloidfibrillen aus verschiedenen Organen, bestehend aus nicht‐homologen Polypeptidketten sowie aus menschlichem und tierischem Gewebe. Unabhängig von Amyloidtyp und ‐herkunft finden wir, dass in vivo gebildete Amyloidfibrillen signifikant polymorphe Eigenschaften aufweisen. Diese Daten lassen darauf schließen, dass die chemischen Grundlagen jener Reaktionen, die in der Selbstorganisation zu Fibrillen zu Polymorphismus führen, in vivo und in vitro grundsätzlich konserviert sind.
Oxidative Conversion of a Europium(II)‐Based T1 Agent into a Europium(III)‐Based paraCEST Agent that can be Detected In Vivo by Magnetic Resonance Imaging
Authors: Funk Alexander M. , Clavijo Jordan Veronica , Sherry A. Dean , Ratnakar S. James , Kovacs Zoltan 
Published: March 2016

AbstractThe EuII complex of 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) tetra(glycinate) has a higher reduction potential than most EuII chelates reported to date. The reduced EuII form acts as an efficient water proton T1 relaxation reagent, while the EuIII form acts as a water‐based chemical exchange saturation transfer (CEST) agent. The complex has extremely fast water exchange rate. Oxidation to the corresponding EuIII complex yields a well‐defined signal from the paraCEST agent. The time course of oxidation was studied in vitro and in vivo by T1‐weighted and CEST imaging.
Decoding the Morphological Diversity in Two Dimensional Crystalline Porous Polymers by Core Planarity Modulation
Authors: Halder Arjun , Kandambeth Sharath , Biswal Bishnu P. , Kaur Gagandeep , Roy Neha Chaki , Addicoat Matthew , Salunke Jagadish K. , Banerjee Subhrashis , Vanka Kumar , Heine Thomas , Verma Sandeep , Banerjee Rahul 
Published: March 2016

AbstractTwo new chemically stable triazine‐ and phenyl‐core‐based crystalline porous polymers (CPPs) have been synthesized using a single‐step template‐free solvothermal route. Unique morphological diversities were observed for these CPPs [2,3‐DhaTta (ribbon) and 2,3‐DhaTab (hollow sphere)] by simply altering the linker planarity. A detailed time‐dependent study established a significant correlation between the molecular level structures of building blocks with the morphology of CPPs. Moreover, a DFT study was done for calculating the interlayer stacking energy, which revealed that the extent of stacking efficiency is responsible for governing the morphological diversity in these CPPs.
Fully Borylated Methane and Ethane by Ruthenium‐Mediated Cleavage and Coupling of CO
Authors: Batsanov Andrei S. , Cabeza Javier A. , Crestani Marco G. , Fructos Manuel R. , García‐Álvarez Pablo , Gille Marie , Lin Zhenyang , Marder Todd B. 
Published: March 2016

AbstractMany transition‐metal complexes and some metal‐free compounds are able to bind carbon monoxide, a molecule which has the strongest chemical bond in nature. However, very few of them have been shown to induce the cleavage of its C−O bond and even fewer are those that are able to transform CO into organic reagents with potential in organic synthesis. This work shows that bis(pinacolato)diboron, B2pin2, reacts with ruthenium carbonyl to give metallic complexes containing borylmethylidyne (CBpin) and diborylethyne (pinBC≡CBpin) ligands and also metal‐free perborylated C1 and C2 products, such as C(Bpin)4 and C2(Bpin)6, respectively, which have great potential as building blocks for Suzuki–Miyaura cross‐coupling and other reactions. The use of 13CO‐enriched ruthenium carbonyl has demonstrated that the boron‐bound carbon atoms of all of these reaction products arise from CO ligands.
Molecular Calcium Hydride: Dicalcium Trihydride Cation Stabilized by a Neutral NNNN‐Type Macrocyclic Ligand
Authors: Leich Valeri , Spaniol Thomas P. , Maron Laurent , Okuda Jun 
Published: March 2016

AbstractHydrogenolysis of bis(triphenylsilyl)calcium containing the neutral NNNN‐type macrocyclic amine ligand Me4TACD [Ca(Me4TACD)(SiPh3)2] (2), gave the cationic dinuclear calcium hydride [Ca2H3(Me4TACD)2](SiPh3) (3), characterized by NMR spectroscopy, single‐crystal X‐ray analysis, and DFT calculations. Compound 3 reacted with deuterium to give the deuteride [D3]‐3.
Gold‐Catalyzed Allylation Reactions
Authors: Quintavalla Arianna , Bandini Marco 
Published: March 2016

AbstractThe allylation reaction is a well‐established and indispensable tool for the development of chemical complexity and diversity in organic synthesis. Over several decades, this unique transformation has undergone several developments to establish a more simple, selective, and sustainable variant. Moving from stoichiometric amounts of metal additives to sub‐stoichiometric amounts, and more recently to catalytic loadings is only one of the chemical revolutions faced by the allylation reaction. In this context, homogeneous gold catalysis has played a pivotal role, resulting in unexpected reaction pathways, concerning unactivated unsaturated hydrocarbons, feasible. Among them, [AuI]‐ and [AuIII]‐assisted allylation reactions deserve particular mention owing to their impact in the synthesis of key organic building blocks and value‐added compounds. An unprecedented survey across the development of allylation methodologies based on this coinage metal is documented in the present Minireview.
NH4I‐Catalyzed Synthesis of Sulfonamides from Arylsufonylhydrazides and Amines
Authors: Yu Hui , Zhang Yonghao 
Published: March 2016

AbstractA novel and efficient approach to sulfonamides has been developed. Using TBHP as the oxidant and NH4I (20 mol%) as the catalyst, arylsulfonyl hydrazides reacted with amines to provide sulfonamides in moderate to good yields. Possible reaction pathway for the formation of the products was also discussed in this paper.
DNA Nanotechnology Mediated Gold Nanoparticle Conjugates and Their Applications in Biomedicine
Authors: Wang Chenguang , Zhang Huan , Zeng Dongdong , San Lili , Mi Xianqiang 
Published: March 2016

AbstractGold nanoparticles (Au NPs) provide numerous biomedical applications with unique chemical and physical properties. Au NPs can be readily synthesized, and modified with multiple chemical or biological molecules, making them excellent candidates for biosensor, in vitro and in vivo imaging, drug delivery and catalysis. Perfect specific DNA base‐pairing can not only serve as genetic information carriers but also construct novel nanostructures and hybrid conjugates with inorganic nanomaterials such as Au NPs. On one hand, based on the unique DNA characters including unparalleled base pairing, double helix with precise diameter and programmable sequences, various DNA statical nanostructures with well‐defined size, shape and dynamic structures as well as controlled functions have been created through using DNA nanotechnology. On the other hand, rapid developments in nanotechnology and nanoscience have new questions on how DNA and DNA structures interact with inorganic nanomaterials, which should be important for their biological and biomedical applications. In this review, we intend to provide an overview on recent advanced Au NPs‐based DNA conjugates for biomedical applications, mainly including the functionalization of Au NPs (Au NPs‐based DNA conjugates interact with Au‐S bond or Au‐polyA); application of Au NPs‐based conjugates in biomedicine, such as biosensing, drug delivery and therapy, and Au NPs‐DNA conjugates based advanced nanostructures.
State‐of‐the‐Art in Electrophilic Trifluoromethylthiolation Reagents
Authors: Chachignon Hélène , Cahard Dominique 
Published: March 2016

AbstractThis work proposed a label‐free, cost‐effective and fairly sensitive electrogenerated chemiluminescence (ECL) strategy for the specific detection of lysozyme based on the hemin/G‐quadruplex hybrid. Gold nanoparticles were spread onto the chitosan thin‐film as substrate to adsorb thiolated captures: a hairpin‐structured DNA, integrating dual head‐tail connected functional domains: one aptamer sequence for lysozyme and the other for hemin (iron(III) proto‐porphyrin IX). In the presence of the both, the hairpin conformation unfolded and transformed into the hemin/G‐quadruplex motif, which quenched the ECL emission of underlaid quantum dots significantly via the consumption of dissolved oxygen as endogenous coreactant. This construction enabled a wide linear response to lysozyme, ranging from 20 pg·mL−1 to 5 µg·mL−1, with a detection limit as low as 4.95 pg·mL−1 (e.g. 9.4 pmol·L−1), demonstrating the prospective utilization of DNA technologies in bioanalysis.
Orthogonal Sensing of Small Molecules Using a Modular Nanoparticle‐Based Assay
Authors: Neri Simona , Pinalli Roberta , Dalcanale Enrico , Prins Leonard J. 
Published: March 2016

AbstractHerein, we present a modular indicator‐displacement assay able to selectively recognize small molecules with biological relevance under competitive conditions. The assay relies on the change in affinity of macrocyclic receptors, such as cavitands, cyclodextrins or calixarenes, for monolayer‐protected gold nanoparticles upon complexation of the respective target analyte. This change affects the equilibrium between the nanoparticles and a fluorescent reporter leading to a change in intensity of the fluorescent output signal. The recognition modules can be changed in order to tune the selectivity of the assay without affecting the nature of the output signal. The combined use of recognition modules results in an assay able to detect multiple analytes simultaneously with high selectivity.
Shifts in symbiotic associations in plants capable of forming multiple root symbioses across a long‐term soil chronosequence
Authors: Albornoz Felipe E. , Lambers Hans , Turner Benjamin L. , Teste François P. , Laliberté Etienne 
Published: March 2016

AbstractChanges in soil nutrient availability during long‐term ecosystem development influence the relative abundances of plant species with different nutrient‐acquisition strategies. These changes in strategies are observed at the community level, but whether they also occur within individual species remains unknown. Plant species forming multiple root symbioses with arbuscular mycorrhizal (AM) fungi, ectomycorrhizal (ECM) fungi, and nitrogen‐(N) fixing microorganisms provide valuable model systems to examine edaphic controls on symbioses related to nutrient acquisition, while simultaneously controlling for plant host identity. We grew two co‐occurring species, Acacia rostellifera (N2‐fixing and dual AM and ECM symbioses) and Melaleuca systena (AM and ECM dual symbioses), in three soils of contrasting ages (c. 0.1, 1, and 120 ka) collected along a long‐term dune chronosequence in southwestern Australia. The soils differ in the type and strength of nutrient limitation, with primary productivity being limited by N (0.1 ka), co‐limited by N and phosphorus (P) (1 ka), and by P (120 ka). We hypothesized that (i) within‐species root colonization shifts from AM to ECM with increasing soil age, and that (ii) nodulation declines with increasing soil age, reflecting the shift from N to P limitation along the chronosequence. In both species, we observed a shift from AM to ECM root colonization with increasing soil age. In addition, nodulation in A. rostellifera declined with increasing soil age, consistent with a shift from N to P limitation. Shifts from AM to ECM root colonization reflect strengthening P limitation and an increasing proportion of total soil P in organic forms in older soils. This might occur because ECM fungi can access organic P via extracellular phosphatases, while AM fungi do not use organic P. Our results show that plants can shift their resource allocation to different root symbionts depending on nutrient availability during ecosystem development.
A Sensitive Biosensor for Determination of Cu2+ by One‐step Electrodeposition
Authors: Tian Rong , Chen Xiaojun , Liu Dejin , Yao Cheng 
Published: March 2016

AbstractA simple one‐step electrodeposition method is described to fabricate three dimensional ordered macroporous chitosan−prussian blue−single walled carbon nanotubes (3DOM CS−PB−SWCNTs) film onto the gold electrode surface to fabricate a copper ions (Cu2+)‐specific DNAzyme biosensor. The new sensing strategy for sensitive and selective detection of Cu2+ was based on Au nanorods (AuNRs) as signal amplification labels. The electrochemical signal of glucose increased with the concentration of Cu2+ increasing. The morphologies and electrochemistry of the composites were investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical techniques including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and so on. Linear correlations of copper ion concentration were obtained in the range from 10−18 M to 10−5 M, achieving with a limit of detection of 10−19 M (S/N=3). Parameters affecting the biosensor response such as temperature, the cleavage time and the time of hybridization were optimized. This biosensor showed a wide range, low detection limit, good reproducibility and high stability. Additionally, these striking properties endow the biosensor with a great promise for analytical applications.
Multi‐chambers Microsystem for Simultaneous and Direct Electrochemical Detection of Reactive Oxygen and Nitrogen Species Released by Cell Populations
Authors: Li Yun , Meunier Anne , Fulcrand Rémy , Sella Catherine , Amatore Christian , Thouin Laurent , Lemaître Frédéric , Guille‐Collignon Manon 
Published: March 2016

AbstractElectrochemical quantification of four reactive oxygen and nitrogen species (e.g., H2O2, ONOO−, NO and NO2−) emitted from macrophages populations was completed using a four‐chambers microchip. This microchip was fabricated from a glass substrate equipped with four sets of microband electrodes. Each set consisted of a platinum‐black coated working electrode combined to an Ag/AgCl reference and a Pt counter electrodes. A cover made of polydimethylsiloxane was designed with four wells whose open bottoms fitted over each set. Loading, culture and stimulation of cells were conducted within each well. After stimulation of macrophages by a calcium ionophore, amperometric responses were then monitored using a multipotentiostat to detect one species per well simultaneously. The results showed good reproducibility and were quite consistent with averaged amperometric detections obtained from single cell measurements. This methodology allowed drastically diminishing the number of experiments necessary to reach a statistical significance from n=100–160 experiments required for single cell detection compared to n=5 experiments to obtain the mean behavior of the cell population. This work demonstrated that this simple and versatile microchip could be used for quantification of species in oxidative stress investigations on cell populations as well as a complementary tool to compare behaviors between single cell and cell population for investigations involving many experimental variables.
Process Comparison for Biomass Combustion: In Situ Gasification‐Chemical Looping Combustion (iG‐CLC) versus Chemical Looping with Oxygen Uncoupling (CLOU)
Authors: Mendiara T. , Adánez‐Rubio I. , Gayán P. , Abad A. , de Diego L. F. , García‐Labiano F. , Adánez J. 
Published: March 2016

AbstractBiomass is an interesting renewable fuel to be used in chemical looping combustion (CLC). If the CO2 generated during biomass combustion is captured, the negative‐CO2 emission concept is possible. This work evaluates the differences between biomass combustion under two CLC configurations developed for solid fuels: in situ gasification‐chemical looping combustion (iG‐CLC) and chemical looping with oxygen uncoupling (CLOU). The combustion efficiency, tar emission, and carbon capture efficiency obtained at different fuel reactor temperatures in a continuous 1.5 kWth CLC unit were compared. Higher carbon capture efficiencies were reached under the CLOU mode, with no tar emission. Although in the iG‐CLC mode tars were always present in the fuel reactor outlet gas, high carbon capture was reached by using CO2 as gasifying agent. Moreover, a simulation of the effect of the solid inventory necessary in the fuel reactor to reach certain carbon capture efficiency was performed for both processes. Lower solid inventories are needed in the CLOU configuration, but the cost for the oxygen carrier used in CLOU is higher than in iG‐CLC.