bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Policies on Yam Production and Consumption in Nigeria
Authors: Felicia Adesiyan Oluwafunmilola , Titus Adesiyan Adewumi , Bamire Adebayo Simeon , Ousmane Coulibaly , Asiedu Robert
Published: December 2015

Several efforts have been made through research, government programs and Non‐Governmental Organisations (NGO) interventions to improve yam production in Nigeria. In addition, some policies targeted at improving agricultural production have weakened the production and consumption of different commodities, especially yam. This study analyzed the effects of policy changes on yam production and consumption in Nigeria. A multi‐stage sampling technique was used to select 700 respondents for the study. Primary data was collected using pre‐tested structured questionnaire while interview guide was used to collect information in a Focus Group Discussion. Data were analyzed using Multi‐Market Model.

The results showed that that policy changes on yam substitutes, particularly rice, sometimes have negative effects on yam production, prices, land share and real income among yam farming households in Nigeria depending on the nature of the policy.
Diastereoselective Synthesis of β‐Ether Derivatives of Artemisinin, an Antimalarial Drug: The Effect of Nitrile on Stereoselectivity
Authors: Chand Hemender R. , Bhattacharya Asish K.
Published: December 2015

Malaria is a life‐threatening disease affecting a major portion of the world's population with considerable loss of human life. Artemisinin, isolated from Artemisia annua, its oil‐ and water‐soluble derivatives, and other known antimalarials are recommended for artemisinin combination therapy by the World Health Organization. We have established a method for the stereoselective synthesis of β‐ether derivatives of dihydroartemisinin in high yield and high diastereoselectivity. The reaction either in acetonitrile or dichloromethane/trichloroacetonitrile (6:1) mixtures at 0 °C or room temperature, respectively, furnished the antimalarial drugs artemether 3 or arteether 4 in high yield with a high diastereomeric ratio. The effect the nitrile has on the yield and stereoselectivity is mechanistically explained.
Enzyme‐Mediated Modification of Single‐Domain Antibodies for Imaging Modalities with Different Characteristics
Authors: Rashidian Mohammad , Wang Lu , Edens Jerre G. , Jacobsen Johanne T. , Hossain Intekhab , Wang Qifan , Victora Gabriel D. , Vasdev Neil , Ploegh Hidde , Liang Steven H.
Published: December 2015

Antibodies are currently the fastest‐growing class of therapeutics. Although naked antibodies have proven valuable as pharmaceutical agents, they have some limitations, such as low tissue penetration and a long circulatory half‐life. They have been conjugated to toxic payloads, PEGs, or radioisotopes to increase and optimize their therapeutic efficacy. Although nonspecific conjugation is suitable for most in vitro applications, it has become evident that site specifically modified antibodies may have advantages for in vivo applications. Herein we describe a novel approach in which the antibody fragment is tagged with two handles: one for the introduction of a fluorophore or 18F isotope, and the second for further modification of the fragment with a PEG moiety or a second antibody fragment to tune its circulatory half‐life or its avidity. Such constructs, which recognize Class II MHC products and CD11b, showed high avidity and specificity. They were used to image cancers and could detect small tumors.
Free Superoxide is an Intermediate in the Production of H2O2 by Copper(I)‐Aβ Peptide and O2
Authors: Reybier Karine , Ayala Sara , Alies Bruno , Rodrigues João V. , Bustos Rodriguez Susana , La Penna Giovanni , Collin Fabrice , Gomes Cláudio M. , Hureau Christelle , Faller Peter
Published: December 2015

Oxidative stress is considered as an important factor and an early event in the etiology of Alzheimer's disease (AD). Cu bound to the peptide amyloid‐β (Aβ) is found in AD brains, and Cu‐Aβ could contribute to this oxidative stress, as it is able to produce in vitro H2O2 and HO. in the presence of oxygen and biological reducing agents such as ascorbate. The mechanism of Cu‐Aβ‐catalyzed H2O2 production is however not known, although it was proposed that H2O2 is directly formed from O2 via a 2‐electron process. Here, we implement an electrochemical setup and use the specificity of superoxide dismutase‐1 (SOD1) to show, for the first time, that H2O2 production by Cu‐Aβ in the presence of ascorbate occurs mainly via a free O2.− intermediate. This finding radically changes the view on the catalytic mechanism of H2O2 production by Cu‐Aβ, and opens the possibility that Cu‐Aβ‐catalyzed O2.− contributes to oxidative stress in AD, and hence may be of interest.
An Amidinohydrolase Provides the Missing Link in the Biosynthesis of Amino Marginolactone Antibiotics
Authors: Hong Hui , Samborskyy Markiyan , Lindner Frederick , Leadlay Peter F.
Published: December 2015

Desertomycin A is an aminopolyol polyketide containing a macrolactone ring. We have proposed that desertomycin A and similar compounds (marginolactones) are formed by polyketide synthases primed not with γ‐aminobutanoyl‐CoA but with 4‐guanidinylbutanoyl‐CoA, to avoid facile cyclization of the starter unit. This hypothesis requires that there be a final‐stage de‐amidination of the corresponding guanidino‐substituted natural product, but no enzyme for such a process has been described. We have now identified candidate amidinohydrolase genes within the desertomycin and primycin clusters. Deletion of the putative desertomycin amidinohydrolase gene dstH in Streptomyces macronensis led to the accumulation of desertomycin B, the guanidino form of the antibiotic. Also, purified DstH efficiently catalyzed the in vitro conversion of desertomycin B into the A form. Hence this amidinohydrolase furnishes the missing link in this proposed naturally evolved example of protective‐group chemistry.
Interacting Carbon Nitride and Titanium Carbide Nanosheets for High‐Performance Oxygen Evolution
Authors: Ma Tian Yi , Cao Jian Liang , Jaroniec Mietek , Qiao Shi Zhang
Published: December 2015

Free‐standing flexible films, constructed from two‐dimensional graphitic carbon nitride and titanium carbide (with MXene phase) nanosheets, display outstanding activity and stability in catalyzing the oxygen‐evolution reaction in alkaline aqueous system, which originates from the Ti–Nx motifs acting as electroactive sites, and the hierarchically porous structure with highly hydrophilic surface. With this excellent electrocatalytic ability, comparable to that of the state‐of‐the‐art precious‐/transition‐metal catalysts and superior to that of most free‐standing films reported to date, they are directly used as efficient cathodes in rechargeable zinc–air batteries. Our findings reveal that the rational interaction between different two‐dimensional materials can remarkably promote the oxygen electrochemistry, thus boosting the entire clean energy system.
Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities
Authors: Cresswell Alexander J. , Eey Stanley T.‐C. , Denmark Scott E.
Published: December 2015

Although recent years have witnessed significant advances in the development of catalytic, enantioselective halofunctionalizations of alkenes, the related dihalogenation of olefins to afford enantioenriched vicinal dihalide products remains comparatively underdeveloped. However, the growing number of complex natural products bearing halogen atoms at stereogenic centers has underscored this critical gap in the synthetic chemist’s arsenal. This Review highlights the selectivity challenges inherent in the design of enantioselective dihalogenation processes, and formulates a mechanism‐based classification of alkene dihalogenations, including those that may circumvent the “classical” haliranium (or alkene‐dihalogen π‐complex) intermediates. A variety of metal and main group halide reagents that have been used for the dichlorination or dibromination of alkenes are discussed, and the proposed mechanisms of these transformations are critically evaluated.
Direct Observation of the Distribution of Gelatin in Calcium Carbonate Crystals by Super‐Resolution Fluorescence Microscopy
Authors: Fu Meifang , Wang Anhe , Zhang Xiaoming , Dai Luru , Li Junbai
Published: December 2015

Biological organic–inorganic hybrid materials often achieve excellent properties and provide inspiration for the design of advanced materials. The organic phase plays a key role in determining the properties of biogenic materials, and the spatial arrangement of organic and inorganic phases provides direct evidence for interaction between the two phases. Super‐resolution fluorescence microscopy was used to visualize the gelatin distribution in two different crystalline polymorphs of calcium carbonate (vaterite and calcite) and to investigate the process by which gelatin is excluded from the crystals. The results demonstrated that gelatin is distributed through vaterite microspheres in the form of nanoparticles, whereas it tends to accumulate on the edges of the calcite rhombohedra.
[Ge2]4− Dumbbells with Very Short Ge−Ge Distances in the Zintl Phase Li3NaGe2: A Solid‐State Equivalent to Molecular O2
Authors: Scherf Lavinia M. , Karttunen Antti J. , Pecher Oliver , Magusin Pieter C. M. M. , Grey Clare P. , Fässler Thomas F.
Published: December 2015

The novel ternary Zintl phase Li3NaGe2 comprises alkali‐metal cations and [Ge2]4− dumbbells. The diatomic [Ge2]4− unit is characterized by the shortest Ge−Ge distance (2.390(1) Å) ever observed in a Zintl phase and thus represents the first Ge=Ge double bond under such conditions, as also suggested by the (8−N) rule. Raman measurements support these findings. The multiple‐bond character is confirmed by electronic‐structure calculations, and an upfield 6Li NMR shift of −10.0 ppm, which was assigned to the Li cations surrounded by the π systems of three Ge dumbbells, further underlines this interpretation. For the unperturbed, ligand‐free dumbbell in Li3NaGe2, the π‐ bonding py and pz orbitals are degenerate as in molecular oxygen, which has singly occupied orbitals. The partially filled π‐type bands of the neat solid Li3NaGe2 cross the Fermi level, resulting in metallic properties. Li3NaGe2 was synthesized from the elements as well as from binary reactants and subsequently characterized crystallographically.
A Copper‐Based Metal–Organic Framework Acts as a Bifunctional Catalyst for the Homocoupling of Arylboronic Acids and Epoxidation of Olefins
Authors: Parshamoni Srinivasulu , Telangae Jyothi , Sanda Suresh , Konar Sanjit
Published: December 2015

A copper(I)‐based metal–organic framework ({[Cu2Br2(pypz)]n⋅nH2O} (Cu—Br–MOF) [pypz=bis[3,5‐dimethyl‐4‐(4’‐pyridyl)pyrazol‐1‐yl] methane] has been synthesized by using an elongated and flexible bridging ligand. The structure analysis reveals that each pypz ligand acts as a tritopic ligand connected to two Cu2Br2 dimeric units, forming a one‐dimensional zig–zag chain, and these chains further connected by a Cu2Br2 unit, give a two‐dimensional framework on the bc‐plane. In the Cu2Br2 dimeric unit, the copper ions are four coordinated, thereby possessing a tetrahedral geometry; this proves to be an excellent heterogeneous catalyst for the aerobic homocoupling of arylboronic acids under mild reaction conditions. This method requires only 3 mol % of catalyst and it does not require any base or oxidant—compared to other conventional (Cu, Pd, Fe, and Au) catalysts—for the transformation of arylboronic acids in very good yields (98 %). The shape and size selectivity of the catalyst in the homocoupling was investigated. The use of the catalyst was further extended to the epoxidation of olefins. Moreover, the catalyst can be easily separated by simple filtration and reused efficiently up to 5 cycles without major loss of reactivity.
Tetranuclear Heterometallic {Zn2Eu2} Complexes With 1‐Naphthoate Anions: Synthesis, Structure and Photoluminescence Properties
Authors: Goldberg Anna , Kiskin Mikhail , Shalygina Olga , Kozyukhin Sergey , Dobrokhotova Zhanna , Nikolaevskii Stanislav , Sidorov Alexey , Sokolov Sergey , Timoshenko Victor , Goloveshkin Alexander , Eremenko Igor
Published: December 2015

A series of new tetranuclear heterometallic ZnII‐EuIII complexes have been synthesized, that is, (bpy)2Zn2Eu2(naph)10 (1), (bpy)2Zn2Eu2(naph)8(NO3)2 (2), and (phen)2Zn2Eu2(naph)8(NO3)2 (3), and other ones, where naph− is the 1‐naphthoate anion, bpy=2,2′‐bipyridyl, and phen=1,10‐phenanthroline. The solid‐phase complexes consist of large supramolecular ensembles due to stacking interactions between the aromatic ligands. Photoluminescence (PL) measurements were carried out to study PL spectra, lifetimes and quantum yields (QY) of the synthesized complexes at different temperatures. The external QY for the solid phases of complexes under UV excitation was found to exceed 20 %. It has been shown that partial replacement of naphthoate ligands in the coordination environment of Eu3+ by NO3− anions influences the PL properties. To investigate the behavior of these complexes in solvent, we dissolved complex 3 in MeCN, put it on a transparent glass as a substrate, and studied the PL properties at room temperature.
Early Vaginal Opening in Juvenile Female Rats Given BRAF‐Inhibitor Dabrafenib Is Not Associated with Early Physiologic Sexual Maturation
Authors: Posobiec Lorraine M. , Vidal Justin D. , Hughes‐Earle Angela , Laffan Susan B. , Hart Timothy
Published: December 2015

Dabrafenib (DAB), an inhibitor of BRAF kinase activity, is approved for metastatic melanoma with a BRAF V600E mutation. In support of pediatric cancer development, a nonclinical juvenile rat toxicity study was conducted in which females had early vaginal opening (VO). It was hypothesized that the early VO was not indicative of sexual maturation, but a result of a local effect on the vagina. An investigative study was conducted that mimicked the definitive study design, with rats given DAB or vehicle orally from Postnatal Day (PND) 7 to 35 and with necropsy subsets just before VO, at the first and second estrus, along with age‐matched controls. Histopathology was performed on reproductive tissues, including immunohistochemistry for BRAF expression. VO occurred earlier in DAB females than in controls (PND 27.2 vs. 31.5); however, the timing of the first estrus was unaffected (PND 34.0 vs. 33.0). DAB‐treated females evaluated just before VO (PND 22.0) had mostly immature reproductive tracts with no evidence of ovulation, similar to age‐matched controls; however, DAB‐treated females had keratinized and histologically open vaginas. Also, there was raised skin around the urogenital area, which correlated with hyperplasia/keratosis of the vulvar skin and keratinization of the distal vagina. BRAF expression (evaluated in controls) was localized to these tissues. Thus, early VO in rats given DAB likely represents a local effect accelerating vaginal keratinization to become open and not accelerated sexual maturation
Sicherer Einsatz von Glasfaserbewehrung im Bauwesen
Authors: Knab Franz , Weber André , Schweinfurth Jörg
Published: December 2015

Bewehrung aus Glasfaserverbundwerkstoffen wird seit über 20 Jahren bei besonderen Anforderungen an Bewehrungseigenschaften erfolgreich eingesetzt. Mit der erstmaligen Zulassung eines Glasfaserbewehrungsstabs in Deutschland 2008 wurde die Grundlage für die breitere Nutzung dieser Technologie geschaffen.

Nachfolgend werden Unterschiede des Materialverhaltens von Glasfaserbewehrung gegenüber Stahl aufgezeigt und wichtige Grundlagen zur Bemessung vorgestellt. Praktische Hinweise zur Vergleichbarkeit von Glasfaserbewehrungen und zum Thema Zustimmung im Einzelfall sowie ein Ausblick auf die Regelungen zu Glasfaserbewehrung in der nächsten Generation des EC2 sollen den planenden Ingenieur bei der sicheren Anwendung unterstützen. Beispiele ausgeführter Projekte geben einen Überblick auf die verschiedenen Einsatzgebiete dieser Spezialbewehrungsart.

Safe application of glass fibre rebar in civil engineering. Hints and examples for practice

In cases where reinforcement with special requirements is needed, glass fibre reinforced polymer bars have successfully been used since more than 20 years. The first approval by the German building authorities (DIBt) has been issued in 2008 giving way for broad application of this technology.

This article focuses on differences in the material behaviour of mild steel and glass fibre rebar and offers basic knowledge for the design of glass fibre rebar. Additional information on comparison of different materials as well as for single use permissions (ZiE) is given. This knowledge combined with a glance on the future regulations on glass fibre rebar in the next EC2 shall enable structural engineers to perform safe calculations and a proper application of glass fibre rebar.

Examples of carried out projects give an overview of the broad field of applications.
Distinguishing between stochasticity and determinism: Examples from cell cycle duration variability
Authors: Pearl Mizrahi Sivan , Sandler Oded , Lande‐Diner Laura , Balaban Nathalie Q. , Simon Itamar
Published: December 2015

We describe a recent approach for distinguishing between stochastic and deterministic sources of variability, focusing on the mammalian cell cycle. Variability between cells is often attributed to stochastic noise, although it may be generated by deterministic components. Interestingly, lineage information can be used to distinguish between variability and determinism. Analysis of correlations within a lineage of the mammalian cell cycle duration revealed its deterministic nature. Here, we discuss the sources of such variability and the possibility that the underlying deterministic process is due to the circadian clock. Finally, we discuss the “kicked cell cycle” model and its implication on the study of the cell cycle in healthy and cancerous tissues.
Specific interactions of alcohols and non‐alcohols with a biologically active boronic acid derivative: a spectroscopic study
Authors: Geethanjali H. S. , Melavanki R. M. , Nagaraja D. , Patil N. R. , Thipperudrappa J. , Kusanur R. A.
Published: December 2015

The photophysical properties of 4‐fluoro‐2‐methoxyphenyl boronic acid (4FMPBA) are characterized using absorption and fluorescence techniques in series of non‐alcohols and alcohols. The results are analyzed using different solvent polarity functions and Kamlet and Catalan's multiple regression approaches. The excited state dipole moment and change in dipole moment are calculated using both the solvatochromic shift method and Reichardt's microscopic solvent polarity parameter
. The ground state dipole moment is evaluated using quantum chemical calculations. It is found that general solute–solvent and hydrogen bond interactions are operative in this system. A red shift of ~ 9 nm in the emission spectra is observed with an increase in the solvent polarity, which depicts π→π* transitions, as well as the possibility of an intramolecular charge transfer (ICT) character in the emitting singlet state of 4FMPBA. The relative quantum yield, radiative and non‐radiative decay constants are calculated in alkanes and alcohols using the single point method. It is found that the quantum yield of the molecule varies from 16.81% to 50.79% with the change in solvent polarity, indicating the dependence of fluorescence on the solvent environment. Copyright © 2015 John Wiley & Sons, Ltd.
High yield of recombinant human Apolipoprotein A‐I expressed in Pichia pastoris by using mixed‐mode chromatography
Authors: Narasimhan Janakiraman Vignesh , Noubhani Abdelmajid , Venkataraman Krishnan , Vijayalakshmi Mookambeswaran , Santarelli Xavier
Published: December 2015

A vast majority of the cardioprotective properties exhibited by High‐Density Lipoprotein (HDL) is mediated by its major protein component Apolipoprotein A‐I (ApoA1). In order to develop a simplified bioprocess for producing recombinant human Apolipoprotein A‐I (rhApoA1) in its near‐native form, rhApoA1was expressed without the use of an affinity tag in view of its potential therapeutic applications. Expressed in Pichia pastoris at expression levels of 58.2 mg ApoA1 per litre of culture in a reproducible manner, the target protein was purified by mixed‐mode chromatography using Capto™ MMC ligand with a purity and recovery of 84% and 68%, respectively. ApoA1 purification was scaled up to Mixed‐mode Expanded Bed Adsorption chromatography to establish an 'on‐line' process for the efficient capture of rhApoA1 directly from the P. pastoris expression broth. A polishing step using anion exchange chromatography enabled the recovery of ApoA1 up to 96% purity. Purified ApoA1 was identified and verified by RPLC‐ESI‐Q‐TOF mass spectrometry. This two‐step process would reduce processing times and therefore costs in comparison to the twelve‐step procedure currently used for recovering rhApoA1 from P. pastoris
Freestanding stacked mesh‐like hydrogel sheets enable the creation of complex macroscale cellular scaffolds
Authors: Son Jaejung , Bae Chae Yun , Park Je‐Kyun
Published: December 2015

Hydrogel‐based bottom‐up tissue engineering depends on assembly of cell‐laden modules for complex three‐dimensional tissue reconstruction. Though sheet‐like hydrogel modules enable rapid and controllable assembly, they have limitations in generating spatial microenvironments and mass transport. Here, we describe a simple method for forming large‐scale cell‐hydrogel assemblies via stacking cell‐embedded mesh‐like hydrogel sheets to create complex macroscale cellular scaffolds. Freestanding stacked hydrogel sheets were fabricated for long‐term cell culturing applications using a facile stacking process where the micropatterned hydrogel sheets (8.0 mm × 8.7 mm) were aligned using a polydimethylsiloxane drainage well. The stacked hydrogel sheets were precisely aligned so that the openings could facilitate mass transport through the stacked sheets. Despite the relatively large height of the stacked structure (400–700 μm), which is larger than the diffusion limit thickness of 150–200 μm, the freestanding cell‐ydrogel assemblies maintained cell viability and exhibited enhanced cellular function compared with single hydrogel sheets. Furthermore, a three‐dimensional co‐culture system was constructed simply by stacking different cell‐containing hydrogel sheets. These results show that stacked hydrogel sheets have significant potential as a macroscale cell‐culture and assay platform with complex microenvironments for biologically relevant in vitro tissue‐level drug assays and physiological studies.
PLK2 phosphorylates and inhibits enriched TAp73 in human osteosarcoma cells
Authors: Hu Zheng Bo , Liao Xiao Hong , Xu Zun Ying , Yang Xiao , Dong Chao , Jin An Min , Lu Hai
Published: December 2015

TAp73, a member of the p53 tumor suppressor family, can substitute for p53 function, especially in p53‐null and p53‐mutant cells. However, TAp73 enrichment and phosphorylation change its transcriptional activity. Previously, we found that the antitumor function of TAp73 was reactivated by dephosphorylation. Polo‐like kinase 2 (PLK2) plays an important role in bone development. Using a biological information database and phosphorylation prediction software, we hypothesized that PLK2 phosphorylates TAp73 and inhibits TAp73 function in osteosarcomas. Actually,we determined that PLK2 physically binds to and phosphorylates TAp73 when TAp73 protein abundance is up‐regulated by cisplatin. PLK2‐phosphorylated TAp73 at residue Ser48 within the TA domain; phosphorylation of TAp73 was abolished by mutating this residue. Moreover, PLK2 inhibition combined with cisplatin treatment in osteosarcoma Saos2 cells up‐regulated p21 and puma mRNA expression to a greater extent than cisplatin treatment alone. Inhibiting PLK2 in TAp73‐enriched Saos2 cells resulted in inhibited cell proliferation, increased apoptosis, G1 phase arrest, and decreased cell invasion. However, these changes did not occur in TAp73 knockdown Saos2 cells. In conclusion, these findings reveal a novel PLK2 function in the phosphorylation of TAp73, which prevents TAp73 activity in osteosarcoma cells. Thereby, this research provides an insight into the clinical treatment of malignant tumors overexpressing TAp73.
Simultaneous Liquefaction and Hydrodeoxygenation of Lignocellulosic Biomass over NiMo/Al2O3, Pd/Al2O3, and Zeolite Y Catalysts in Hydrogen Donor Solvents
Authors: Grilc Miha , Likozar Blaž , Levec Janez
Published: December 2015

The one‐step solvolysis and hydro‐treatment of oak, fir and beech sawdust was studied in a slurry reactor using tetralin, phenol and glycerol as solvents and representative heterogeneous catalysts used in the petrochemical industry for hydrogenolysis (the sulfide form of NiMo/Al2O3), hydrogenation (Pd/Al2O3) or fluid catalytic cracking (zeolite Y). Deoxyliquefaction products of cellulose, hemicellulose and lignin were characterised in terms of solvent fractionation, FTIR and diffuse reflectance infrared Fourier transform spectroscopy, elemental analysis and an innovative method for particle size distribution and mean grain size determination by SEM image processing. A new lumped kinetic model was developed according to the reaction mechanisms, which contain wood de‐polymerisation, decarbonylation, decarboxylation and demethanation, tar phase hydrodeoxygenation by molecular and in situ generated hydrogen, as well as charring inhibition by free‐radical stabilisation hydrogen transfer.
Selective Synthesis of Trimethylamine by Catalytic N‐Methylation of Ammonia and Ammonium Chloride by utilizing Carbon Dioxide and Molecular Hydrogen
Authors: Beydoun Kassem , Thenert Katharina , Streng Emilia S. , Brosinski Sandra , Leitner Walter , Klankermayer Jürgen
Published: December 2015

The synthesis of trimethylamine (TMA) through a multicomponent combination of ammonia with carbon dioxide and molecular hydrogen by using a homogeneous ruthenium catalyst was explored. The use of [Ru(triphos)(tmm)] [triphos: 1,1,1‐tris(diphenylphosphinomethyl)ethane, tmm: trimethylene methane] together with aluminum trifluoromethanesulfonate as a co‐catalyst resulted in high ammonia conversion and excellent selectivity for TMA in organic solvents. Aqueous solutions of ammonium chloride were methylated almost quantitatively to the corresponding hydrochloride salt (i.e., TMA⋅HCl) in a biphasic solvent system by using the same Ru complex without the need for any co‐catalyst.
A Computational and Experimental Study of Thieno[3,4‐b]thiophene as a Proaromatic π‐Bridge in Dye‐Sensitized Solar Cells
Authors: Brogdon Phillip , Giordano Fabrizio , Puneky George A. , Dass Amala , Zakeeruddin Shaik M. , Nazeeruddin Mohammad Khaja , Grätzel Michael , Tschumper Gregory S. , Delcamp Jared H.
Published: December 2015

Four D‐π‐A dyes (D=donor, A=accpetor) based on a 3,4‐thienothiophene π‐bridge were synthesized for use in dye‐sensitized solar cells (DSCs). The proaromatic building block 3,4‐thienothiophene is incorporated to stabilize dye excited‐state oxidation potentials. This lowering of the excited‐state energy levels allows for deeper absorption into the NIR region with relatively low molecular weight dyes. The influence of proaromatic functionality is probed through a computational analysis of optimized bond lengths and nucleus independent chemical shifts (NICS) for both the ground‐ and excited‐ states. To avoid a necessary lowering of the TiO2 semiconductor conduction band (CB) to promote efficient dye–TiO2 electron injection, strong donor functionalities based on triaryl‐ and diarylamines are employed in the dye designs to raise both the ground‐ and excited‐state oxidation potentials of the dyes. Solubility, aggregation, and TiO2 surface protection are addressed by examining an ethylhexyl alkyl chain in comparison to a simple ethyl chain on the 3,4‐thienothiophene bridge. Power conversion efficiencies of up to 7.8 % are observed.
Limiting the Number of Potential Binding Modes by Introducing Symmetry into Ligands: Structure‐Based Design of Inhibitors for Trypsin‐Like Serine Proteases
Authors: Furtmann Norbert , Häußler Daniela , Scheidt Tamara , Stirnberg Marit , Steinmetzer Torsten , Bajorath Jürgen , Gütschow Michael
Published: December 2015

In the absence of X‐ray data, the exploration of compound binding modes continues to be a challenging task. For structure‐based design, specific features of active sites in different targets play a major role in rationalizing ligand binding characteristics. For example, dibasic compounds have been reported as potent inhibitors of various trypsin‐like serine proteases, the active sites of which contain several binding pockets that can be targeted by cationic moieties. This results in several possible orientations within the active site, complicating the binding mode prediction of such compounds by docking tools. Therefore, we introduced symmetry in bi‐ and tribasic compounds to reduce conformational space in docking calculations and to simplify binding mode selection by limiting the number of possible pocket occupations. Asymmetric bisbenzamidines were used as starting points for a multistage and structure‐guided optimization. A series of 24 final compounds with either two or three benzamidine substructures was ultimately synthesized and evaluated as inhibitors of five serine proteases, leading to potent symmetric inhibitors for the pharmaceutical drug targets matriptase, matriptase‐2, thrombin and factor Xa. This study underlines the relevance of ligand symmetry for chemical biology.
Atomic‐Level Quality Assessment of Enzymes Encapsulated in Bioinspired Silica
Authors: Martelli Tommaso , Ravera Enrico , Louka Alexandra , Cerofolini Linda , Hafner Manuel , Fragai Marco , Becker Christian F. W. , Luchinat Claudio
Published: December 2015

Among protein immobilization strategies, encapsulation in bioinspired silica is increasingly popular. Encapsulation offers high yields and the solid support is created through a protein‐catalyzed polycondensation reaction that occurs under mild conditions. An integrated strategy is reported for the characterization of both the protein and bioinspired silica scaffold generated by the encapsulation of enzymes with an external silica‐forming promoter or with the promoter expressed as a fusion to the enzyme. This strategy is applied to the catalytic domain of matrix metalloproteinase 12. Analysis reveals that the structure of the protein encapsulated by either method is not significantly altered with respect to the native form. The structural features of silica obtained by either strategy are also similar, but differ from those obtained by other approaches. In case of the covalently linked R5–enzyme construct, immobilization yields are higher. Encapsulation through a fusion protein, therefore, appears to be the method of choice.
Direct Assembly of Mesoporous Silica Functionalized with Polypeptides for Efficient Dye Adsorption
Authors: Lu Yi‐Syuan , Bastakoti Bishnu Prasad , Pramanik Malay , Malgras Victor , Yamauchi Yusuke , Kuo Shiao‐Wei
Published: December 2015

Herein, we introduce a new polypeptide‐functionalized mesoporous silica template fabricated from a biodegradable poly(ethylene oxide‐b‐ɛ‐caprolactone) (PEO‐b‐PCL) diblock copolymer and a poly(tyrosine) (PTyr) biopolymer. The crystallization behavior of the PEO‐b‐PCL diblock copolymer changes after blending, but the secondary structure of PTry remains stable. After selective solvent extraction in THF, the PEO‐b‐PCL is removed, but PTyr remains within the silica matrix due to its different solubility. Fourier‐transform IR spectroscopic analysis (FTIR), thermal gravitometry analysis (TGA), small‐angle X‐ray scattering (SAXS), and X‐ray diffraction (XRD) studies confirm the retention of PTyr to form a polypeptide‐functionalized mesoporous material. The adsorption of methylene blue hydrate (MB) from aqueous solution into the polypeptide‐functionalized mesoporous silica is investigated, thus revealing that the nanocomposite exhibits a high adsorption capacity relative to pure silica due to hydrogen‐bonding interactions between the hydroxy phenolic group of PTyr and the N‐containing aromatic ring from MB.
Iodide Recognition and Sensing in Water by a Halogen‐Bonding Ruthenium(II)‐Based Rotaxane
Authors: Langton Matthew J. , Marques Igor , Robinson Sean W. , Félix Vítor , Beer Paul D.
Published: December 2015

The synthesis and anion‐recognition properties of the first halogen‐bonding rotaxane host to sense anions in water is described. The rotaxane features a halogen‐bonding axle component, which is stoppered with water‐solubilizing permethylated β‐cyclodextrin motifs, and a luminescent tris(bipyridine)ruthenium(II)‐based macrocycle component. 1H NMR anion‐binding titrations in D2O reveal the halogen‐bonding rotaxane to bind iodide with high affinity and with selectively over the smaller halide anions and sulfate. The binding affinity trend was explained through molecular dynamics simulations and free‐energy calculations. Photo‐physical investigations demonstrate the ability of the interlocked halogen‐bonding host to sense iodide in water, through enhancement of the macrocycle component’s RuII metal–ligand charge transfer (MLCT) emission.
Stepwise Reduction of an α‐Phosphonio–Carbocation to a Crystalline Phosphorus Radical Cation and an Acridinyl–Phosphorus Ylide
Authors: Hudnall Todd W. , Dorsey Christopher L. , Jones James S. , Gabbaï François P.
Published: December 2015

We have synthesized the dicationic α‐phosphonio–carbocation 12+, which can be regarded as a two‐electron oxidized phosphorus ylide. Carbocation 12+ exhibits two reversible reduction waves at −0.28 and −0.90 V (vs. Fc+/Fc) indicating that both the radical cation 1.+ and the neural phosphorus ylide 1 can be generated. Indeed, reduction of 12+ with Zn afforded 1.+ as a dark green solid that was characterized by XRD and EPR spectroscopy, and reduction with Mg(Ant)⋅(THF)3 gave 1, which was characterized by 1H and 31P NMR spectroscopy. Computational analyses reveal the stepwise population of a C−P π bonding orbital upon reduction of 12+.
Monofluorination and Trifluoromethylation of BODIPY Dyes for Prolonged Single‐Molecule Detection
Authors: Huynh Anh Minh , Menges Johannes , Vester Michael , Dier Tobias , Huch Volker , Volmer Dietrich A. , Jung Gregor
Published: December 2015

Electrophilic monofluorination with Selectfluor and nucleophilic trifluoromethylation with the Ruppert–Prakesh reagent of dimethyl‐, tetramethyl‐ and pentamethyl‐substituted boron dipyrromethenes (BODIPY) are investigated. Monofluorinated dyes are synthesized with low yields (<30 %), however trifluoromethyl derivatives are obtained in moderate to high yields (≈40–90 %). All compounds are characterized by steady‐state and time‐resolved fluorescence spectroscopy, the photostability is investigated with fluorescence correlation spectroscopy (FCS) and total internal reflection fluorescence microscopy (TIRF). Monofluorination hardly affects the spectroscopic parameters of the unsubstituted parent compounds, but distinctly enhances the photostability, whereas trifluoromethylation leads to a hypsochromic shift by up to 17 nm in both absorption and emission, slightly enhanced intersystem crossing, and higher photostability. Further development of soft fluorination and trifluoromethylation methods is therefore highly desired.
Non‐Bonded Interactions Drive the Sub‐Picosecond Bilin Photoisomerization in the Pfr State of Phytochrome Cph1
Authors: Yang Yang , Heyne Karsten , Mathies Richard A. , Dasgupta Jyotishman
Published: December 2015

Phytochromes are protein‐based photoreceptors harboring a bilin‐based photoswitch in the active site. The timescale of photosignaling via C15=C16 E‐to‐Z photoisomerization has been ambiguous in the far‐red‐absorbing Pfr state. Here we present a unified view of the structural events in phytochrome Cph1 post excitation with femtosecond precision, obtained via stimulated Raman and polarization‐resolved transient IR spectroscopy. We demonstrate that photoproduct formation occurs within 700 fs, determined by a two‐step partitioning process initiated by a planarization on the electronic excited state with a 300 fs time scale. The ultrafast isomerization timescale for Pfr‐to‐Pr conversion highlights the active role of the nonbonding methyl–methyl clash initiating the reaction in the excited state. We envision that our results will motivate the synthesis of new artificial photoswitches with precisely tuned non‐bonded interactions for ultrafast response.
A new learning automata‐based sampling algorithm for social networks
Authors: Rezvanian Alireza , Meybodi Mohammad Reza
Published: December 2015

Recently, studying social networks plays a significant role in many applications of social network analysis, from the studying the characterization of network to that of financial applications. Due to the large data and privacy issues of social network services, there is only a limited local access to the whole network data in a reasonable amount of time. Therefore, network sampling arises to studying the characterization of real networks such as communication, technological, information, and social networks. In this paper, a sampling algorithm for complex social networks that is based on a new version of distributed learning automata (DLA) reported recently called extended DLA (eDLA) is proposed. For evaluation purpose, the eDLA‐based sampling algorithm has been tested on several test networks and the obtained experimental results are compared with the results obtained for a number of well‐known sampling algorithms in terms of relative error and Kolmogorov–Smirnov test. It is shown that eDLA‐based sampling algorithm outperforms the existing sampling algorithms. Experimental results further show that the eDLA‐based sampling algorithm in comparison with the DLA‐based sampling algorithm has a 26.93% improvement for the average of Kolmogorov–Smirnov value for degree distribution taken over all test networks. Copyright © 2015 John Wiley & Sons, Ltd.
Modeling and predicting the growth of the mussel, Mytilus edulis: implications for planning of aquaculture and eutrophication mitigation
Authors: Bergström Per , Lindegarth Susanne , Lindegarth Mats
Published: December 2015

The increased pressure on the marine ecosystems highlights the need for policies and integrated approaches for sustainable management of coastal areas. Spatial planning based on geographic information of human activities, ecological structures and functions, and their associated goods and services is a fundamental component in this context. Here, we evaluate the potential of predictive modeling to provide spatial data on one ecosystem function, mussel growth for use in such processes. We developed a methodology based on statistical modeling, spatial prediction, and mapping for the relative growth of the blue mussel, Mytilus edulis. We evaluated the performance of different modeling techniques and classification schemes using empirical measurements of growth from 144 sampling sites and data on biological, chemical, and physical predictors. Following comparisons of the different techniques and schemes, we developed random forest models to predict growth along the Swedish west coast. Implemented into GIS the best model produced in this study predicts that low, intermediate, and high growth rates can be expected in 53%, 32%, and 15% of modeled area, respectively. The results of this study also suggest that the nature and quality of predictor data hold the key to improving the predictive power of models. On a more general note, this study exemplifies a feasible approach based on measuring, modeling, and mapping for obtaining scientifically based spatial information on ecosystem functions and services affected by a complex set of factors. Such information is fundamental for maritime spatial planning and ecosystem‐based management and its importance is likely to increase in the future. Because of its close link to nutrient assimilation and production yield, site‐specific information of soft tissue growth such as the map of predicted growth rate developed in this study can be used as a tool for optimizing actions aimed at mitigating eutrophication and aquaculture operations and in maritime spatial planning processes of coastal areas.
Sterically Protected Diphosphenes
Authors: Yoshifuji Masaaki
Published: December 2015

Diphosphenes with various kinds of sterically protecting groups are described and discussed with regard to 31P NMR spectroscopic data, X‐ray results, preparative methods, and some reactions including end‐on coordination complex formations. New results of theoretical calculations on the particular diphosphene (E)‐Mes*P=PMes* are also described.
Flavonoid‐Based Organometallics with Different Metal Centers – Investigations of the Effects on Reactivity and Cytotoxicity
Authors: Kurzwernhart Andrea , Mokesch Stephan , Klapproth Erik , Adib‐Ravazi Mahsa S. , Jakupec Michael A. , Hartinger Christian G. , Kandioller Wolfgang , Keppler Bernhard K.
Published: December 2015

Flavonol‐derived OsII(cym) and RhIII‐Cp* complexes were synthesized and the impact of the metal center on aqueous stability, reactivity toward biomolecules, and cytotoxic activity was compared to RuII analogs. The RhIII complexes were the most stable to ligand release in aqueous solution and showed the highest preference for ubiquitin binding. Investigations on the reactivity toward nucleoside triphosphates revealed the clear affinity of RhIII to 5′‐dATP, whereas RuII and OsII prefer binding to 5′‐dGTP. Simultaneous incubation with amino acids and nucleoside triphosphates reveals the preference toward amino acids, indicating that binding to proteins might be a key step in the mechanism of action of this compound class. The complexes exhibit in vitro anticancer activities in the high nM to low μM range, confirming the flavonol scaffold as a promising O,O‐chelating ligand system for the development of anticancer active organometallics.
Alkaline Earth Complexes of a Sterically Demanding Guanidinate Ligand
Authors: Moxey Graeme J. , Blake Alexander J. , Lewis William , Kays Deborah L.
Published: December 2015

The synthesis of the guanidine MesN{C(NCy2)}N(H)Mes (LH; Mes = 2,4,6‐Me3C6H2, Cy = cyclohexyl), and its use as a proligand for the synthesis of alkaline earth metal complexes are reported. Described herein are (i) an unusual Hauser base cubane, (ii) a homoleptic and a base‐stabilized magnesium complex featuring the same guanidinate ligands, and (iii) the comparison of a series of alkaline earth (Mg, Ca, Sr, Ba) bis(guanidinate) complexes, which allows the opportunity to compare the changing trends in bonding as the Group is descended. The reaction between LH and MeMgI(OEt2)2 yields the Hauser base as a mixture of the tetramer [Mg4L4(μ3‐I)4] (1a) and dimer [Mg2L2(μ‐I)2(OEt2)2] (1b), and the reaction with two equivalents of MgnBu2 leads to the formation of four‐coordinate [MgL2] (2), which features a square‐planar geometry for the magnesium cation, or five‐coordinate [MgL2(THF)] (3), depending on the solvent used. 1a is the first crystallographically‐characterized cubane structure to consist of four LAeX (L = ligand, X = halide) units. The complexes [AeL2(THF)2] (Ae = Ca, 4; Ae = Sr, 5) and [BaL2] (6) were synthesized via redox transmetallation/ligand exchange reactions. Complex 6 is the first example of a homoleptic, monomeric barium complex of the NCN ligand family, with the structure stabilized by a number of barium‐arene interactions in the solid state.
Physicochemical properties, volatile compounds, and oxidative stability of cold pressed kernel oils from raw and roasted pistachio (Pistacia vera L. Var Kerman)
Authors: Ling Bo , Yang Xuanmin , Li Rui , Wang Shaojin
Published: December 2015

Pistachio kernel oil (PKO) was prepared by cold‐pressing from raw (RPKO), conventional (CRPKO), and microwave (MRPKO) roasted kernels for Kerman pistachio. Physicochemical properties, bioactive compounds, antioxidant activities, and thermal behaviors of extracted oils were determined in this study. Volatile compounds were tentatively identified and semi‐quantified by headspace solid‐phase micro‐extraction combined with gas chromatography‐mass spectrometry technique. The results showed that there was no significant difference between oil samples for some physicochemical parameters and fatty acid profiles. Roasting treatments caused an increase in total phenolics and antioxidant capacity and a decrease in levels of total tocopherols and chlorophylls. The thermal transition temperatures of the RPKO were −47.15 and −19.85°C for crystallization, and −13.11 and 3.11°C for melting. Among the 43 volatile compounds identified, the major compounds were limonene, α‐pinene, β‐myrcene, hexanoic acid, and nonanal in RPKO. The levels of these compounds decreased after roasting. However, concentrations of pyrazines, furans, and pyrroles increased significantly as a result of roasting, especially for CRPKO. Using a PV of 15 meq/kg oil as a quality criterion, PKO stored in transparent glass bottles after exposed to fluorescent light (720 Lux) and room temperature conditions had an acceptable quality for only 30 days of storage.

Practical applications: Pistachios are normally consumed as salted and roasted snacks or as an ingredient in bakery and confectionery products, desserts, and ice‐creams. With the increasing consumption and demand for novel edible oils, the market is expanding and creating space for the production of the pistachio kernel oil. After analyzing the physicochemical characteristics and volatile compounds, roasting treatments may provide additional volatile compounds in the pistachio kernel oil. The research results suggest that cold‐pressed pistachio kernel oil is highly susceptible to photo‐oxidative degradation, and must be stored in containers with light‐barrier properties together with the addition of some appropriate natural antioxidants.

Physicochemical properties, volatile compounds, and oxidative stability of pistachio kernel oils obtained from different treated pistachio kernels (raw, conventional, and microwave roasting) by cold pressing method were analyzed. Results indicate that pistachio kernel oil can be produced by the cold pressing technique giving edible quality, which does not require chemical refining, and only a simple filtering or centrifugation to remove suspended plant materials may be needed. Conventional or microwave roasting treatments before pressing did not change the oil specifications significantly.
Ca2+‐complex stability of GAPAGPLIVPY peptide in gas and aqueous phase, investigated by affinity capillary electrophoresis and molecular dynamics simulations and compared to mass spectrometric results
Authors: Nachbar Markus , El Deeb Sami , Mozafari Mona , Alhazmi Hassan A. , Preu Lutz , Redweik Sabine , Lehmann Wolf Dieter , Wätzig Hermann
Published: December 2015

Strong, sequence‐specific gas‐phase bindings between proline‐rich peptides and alkaline earth metal ions in nanoESI‐MS experiments were reported by Lehmann et al. (Rapid Commun. Mass Spectrom. 2006, 20, 2404–2410), however its relevance for physiological‐like aqueous phase is uncertain. Therefore, the complexes should also be studied in aqueous solution and the relevance of the MS method for binding studies be evaluated. A mobility shift ACE method was used for determining the binding between the small peptide GAPAGPLIVPY and various metal ions in aqueous solution. The findings were compared to the MS results and further explained using computational methods. While the MS data showed a strong alkaline earth ion binding, the ACE results showed nonsignificant binding. The proposed vacuum state complex also decomposed during a molecular dynamic simulation in aqueous solution. This study shows that the formed stable peptide–metal ion adducts in the gas phase by ESI‐MS does not imply the existence of analogous adducts in the aqueous phase. Comparing peptide–metal ion interaction under the gaseous MS and aqueous ACE conditions showed huge difference in binding behavior.