bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of the Aromatic/Paraffinic Composition of Synthetic Jet Fuels
Authors: Al‐Nuaimi Ibrahim A. , Bohra Moiz , Selam Muaz , Choudhury Hanif A. , El‐Halwagi Mahmoud M. , Elbashir Nimir O. 
Published: September 2016

AbstractAviation fuels derived from the gas‐to‐liquid (GTL) technology may be used as drop‐in alternatives to conventional oil‐derived fuels. Reliable composition‐property relations must be developed based on experimental data to correlate the hydrocarbon compositions of formulated synthetic fuels with their properties to be certified for aviation commercial use. An experimental and property‐integration framework for the design of synthetic jet fuels from GTL‐based kerosene derived by evaluating the role of aromatics on resultant fuel properties is presented. The experimental results were used to develop property‐mixing rules and linear programming for the design of optimum fuel compositions that meet the ASTM specifications. The role of aromatics on critical physical properties for jet fuel certification is revealed. A practical solution for jet fuels blending through optimization of jet fuel formulation based on cost and technically effective manners is provided.
Intensified Distillation‐Based Separation Processes: Recent Developments and Perspectives
Authors: Long Nguyen Van Duc , Minh Le Quang , Ahmad Faizan , Luis Patricia , Lee Moonyong 
Published: September 2016

AbstractGreater sustainability can be achieved by decreasing the production costs, energy consumption, equipment size, and environmental impact as well as improvement of the raw material yields, remote control, and process flexibility. Process intensification (PI) as the main route for improving the process performance is used widely in heat transfer, reactions, separation, and mixing, which results in plant compactness, cleanliness, and energy efficiency. Some of the main intensified separation processes and improvement mechanisms are reviewed briefly with the main focus on the PI of distillation processes, which are the most important separation methods. In addition to these technologies, the potential and reliability of reactive separation processes are addressed briefly, which will enable higher efficiency and capacity.
Molecular Dimensions and Porous Structure of Activated Carbons for Sorption of Xylene and Isooctane
Authors: Troppová Ivana , Matějová Lenka , Kuboňová Lenka , Strašák Tomáš , Študentová Soňa , Kustrowski Piotr , Obalová Lucie 
Published: September 2016

AbstractThe sorption of xylene and isooctane was measured by the gravimetric flow sorption method on commercial activated carbons (ACs), namely, virgin and reactivated ACs. Nitrogen physisorption, high‐pressure mercury porosimetry, helium pycnometry, iodine number, pH measurement, Raman and X‐ray photoelectron spectroscopies were applied for textural, structural, and surface characterization of ACs. The equilibrium geometries of isooctane and xylene molecules were modeled using density functional theory (DFT) calculations. Their dimensions were estimated to be correlated with textural properties of ACs to reveal the effect of size selectivity. The key factors influencing the adsorption capacity of the chosen ACs for both tested volatile organic compounds (VOCs) were found to be the mesopore surface area and the surface basicity.
Controllability Analysis of Distillation Sequences for the Separation of Bio‐Jet Fuel and Green Diesel Fractions
Authors: Acosta‐Solórzano Angel D. A. , Guerrero‐Farfán Oscar , Ramírez‐Márquez César , Gómez‐Castro Fernando I. , Segovia‐Hernández Juan Gabriel , Hernández Salvador , Gutiérrez‐Antonio Claudia , Briones‐Ramírez Abel 
Published: September 2016

AbstractThe aviation sector is nowadays looking for a biofuel to partially substitute the fossil fuel used for flights, i.e., jet fuel. Among the proposed processes for the production of the renewable jet fuel, the hydrotreating process has, to date, the best performance. At the final stage of the hydrotreating process, a distillation train is required to obtain hydrocarbon fractions useful as fuels. Conventional or thermally coupled distillation sequences can be used in this step, and it can be expected that thermally coupled sequences require less energy to perform the separation. Nevertheless, in the selection of the best sequence for a given separation, it is important to analyze its control properties. A controllability analysis was performed here for different distillation sequences used to obtain biofuels from a hydrocarbon renewable mixture, in order to detect the best sequence in terms of control properties.
Controllable Deposition of Platinum Layers on Oxide Surfaces for the Synthesis of Fuel Cell Catalysts
Authors: Vukmirovic Miomir B. , Kuttiyiel Kurian A. , Meng Hui , Adzic Radoslav R. 
Published: September 2016

AbstractReducing the amount of Pt, the most costly component of both anode and cathode fuel cell catalysts, has attracted considerable attention from the research community. An approach is reported herein to deposit sub‐monolayer to multilayer amounts of Pt and other noble metals on metal oxides and oxidized carbon materials. The process is exemplified by Pt deposition on RuO2(110). The Pt deposit consists of Pt atoms arranged in a c(2×2) array, that is, a 0.25 monolayer (ML). The deposit has lower catalytic activity for the oxygen reduction reaction (ORR) and similar activity for the hydrogen oxidation reaction compared to Pt(111). These activities are explained by a large calculated upshift of the d‐band center of Pt atoms and larger Pt–Pt interatomic distances than those of Pt(111). A catalyst with Pt coverage larger than 0.25 ML on oxide surfaces and oxidized carbon materials is shown to be active for the ORR as well as for other electrocatalytic reactions. A PtRhSnO2/C catalyst shows high activity for ethanol oxidation as a result of its ability to effectively cleave the C−C bond in ethanol. Pt deposited on reduced graphene oxide shows high Pt mass ORR activity and good stability.
Electrochemical Oxidation of Organotrifluoroborate Compounds
Authors: Suzuki Junji , Tanigawa Masahiro , Inagi Shinsuke , Fuchigami Toshio 
Published: September 2016

AbstractElectrochemical analyses of various organotrifluoroborates, and the corresponding boronic acids and esters, were comparatively studied by using cyclic voltammetry. The organotrifluoroborates were found to have much lower oxidation potentials compared with the latter two types of compounds. We also found a pronounced β‐effect for allyltrifluoroborate, which was indicated by both experimental and theoretical aspects. Such a β‐effect is similar to that of allyltrimethylsilane. Anodic oxidation of n‐decyltrifluoroborate at a platinum anode gave a radical coupling product in moderate yield, eliminating a boryl moiety. Anodic acetoxylation of phenethyl‐, aryl‐, and styryltrifluoroborates was also successfully carried out at a graphite anode in NaOAc/AcOH to provide the acetoxylated products in good to moderate yields although a large excess of electricity was required.
Engineering the Ionic Self‐Assembly of Polyoxometalates and Facial‐Like Peptides
Authors: Li Jingfang , Li Xiaodong , Xu Jing , Wang Yang , Wu Lixin , Wang Yanqiu , Wang Liyan , Lee Myongsoo , Li Wen 
Published: September 2016

AbstractThe self‐assembly behavior of polyoxometalates (PMs) and facial‐like cationic peptides carrying lysine residues were systematically investigated. Circular dichroism and UV/Vis spectra demonstrated that the multivalent electrostatic attractions between polyanionic PMs and short peptides with protonated lysine residues initiated the conformational transition of peptide molecules from random‐coil to β‐sheet state, and subsequently the co‐assembly. TEM and atomic force microscopy (AFM) measurements showed that uniform nanofibers formed with decreasing size of the PMs or increasing the intermolecular forces of the peptides, such as through hydrogen‐bonding, hydrophobic, and/or π–π interactions. Additionally, the stability of the nanostructures can be improved by rational suppression of the electrostatic repulsion of the shell peptides covering the surface of the nanostructures. These results provide new insight into understanding the ionic self‐assembly of peptides and PMs and controlling their final morphology.
Honeycomb‐like Ordered Assembly of DNA Induced by Flexible Binuclear Ruthenium(II)–Polypyridyl Complexes
Authors: Singh Sushma B. , Kumbhar Avinash S. , Khan Ayesha 
Published: September 2016

AbstractA series of binuclear ruthenium(II)–polypyridyl complexes of the type [Ru2(N‐N)4(BPIMBp)]4+, in which N‐N is 2,2′‐bipyridine (bpy; 1), 1,10‐phenanthroline (phen; 2), dipyrido[3,2‐d:2′,3‐f] quinoxaline (dpq; 3), dipyrido[3,2‐a:2′,3′‐c] phenanzine (dppz; 4), and 1,4′‐bis[(2‐pyridin‐2‐yl)‐1H‐imidazol‐1‐yl)methyl]‐1,1′‐biphenyl (BPIMBp) is a bridging ligand, have been synthesized and characterized. These complexes are charged (4+) cations and flexible due to the −CH2 group of the bridging ligand and possess terminal ligands with variable intercalative abilities. The interaction of complexes 1–4 with calf thymus DNA (CT‐DNA) was explored by using UV/Vis absorption spectroscopy, steady‐state emission, emission quenching with K4[Fe(CN)6], ethidium bromide displacement assay, Hoechst displacement assay, and viscosity measurements and revealed a groove‐binding mode for all the complexes through a spacer and an intercalative mode for complexes 3 and 4. A decrease in the viscosity of DNA revealed bending and coiling of DNA, an initial step toward aggregation. Interestingly, a distinctive honeycomb‐like ordered assembly of the DNA–complex species was visualized by fluorescence microscopy in the solution state. The use of SEM and AFM confirmed the disordered self‐organization of the DNA–complex adduct on evaporation of the solvent. The small orderly nanosized DNA aggregates were confirmed by means of circular dichroism, dynamic light scattering (DLS), and TEM. These complexes are moderately cytotoxic against three different cell lines, namely, MCF‐7, HeLa, and HL‐60.
Homolytic, Heterolytic, Mesolytic ‐ As You Like It: Steering the Cleavage of a HC(sp3)−C(sp3)H Bond in Bis(1H‐2,1‐benzazaborole) Derivatives
Authors: Hejda Martin , Lyčka Antonín , Mikysek Tomáš , Jambor Roman , Růžička Aleš , Vinklárek Jaromír , Wilfer Claudia , Hoffmann Alexander , Herres‐Pawlis Sonja , Dostál Libor 
Published: September 2016

AbstractA set of (3,3′)‐bis(1‐Ph‐2‐R‐1H‐2,1‐benzazaborole) compounds, in which R=tBu (Bab‐tBu)2, R=Dipp (Bab‐Dipp)2 or R=tBu and Dipp (Bab‐Dipp)(Bab‐tBu), was synthesized and fully characterized using 1H, 11B, 13C, and 15N NMR spectroscopy as well as single‐crystal X‐ray diffraction analysis. The central HC(sp3)−C(sp3)H bond with restricted rotation at the junction of both 1H‐2,1‐benzazaborole rings displayed an intriguing reactivity. It was demonstrated that this bond is easily mesolytically cleaved using alkali metals to form the respective aromatic 1Ph‐2R‐1H‐2,1‐benzazaborolyl anions M+(THF)n(Bab‐tBu)− (M=Li, Na, K) and K+(THF)n(Bab‐Dipp)−. Furthermore, the central HC(sp3)−C(sp3)H bond of bis(1H‐2,1‐benzazaborole)s is also homolytically cleaved either by heating or photochemical means, giving corresponding 1Ph‐2R‐1H‐2,1‐benzazaborolyl radicals (Bab‐tBu). and (Bab‐Dipp)., which rapidly self‐terminate. Nevertheless, their formation was unambiguously established by NMR analysis of the reaction mixtures containing products of the self‐termination of the radicals after heating or irradiation. (Bab‐Dipp). radical was also characterized using EPR spectroscopy. Importantly, it turned out that the essentially non‐polarized HC(sp3)−C(sp3)H bond in (Bab‐tBu)2 is also cleaved heterolytically with 2 equiv of MeLi, giving the mixture of Li+(SOL)n(Bab‐tBu)− (SOL=THF or Et2O) and lithium methyl‐substituted borate complex Li+(SOL)n(Bab‐tBu‐Me)− in a diastereoselective fashion.
How a Small Structural Difference Can Turn Optical Properties of π‐Extended Coumarins Upside Down: The Role of Non‐Innocent Saturated Rings
Authors: Ventura Barbara , Poronik Yevgen M. , Deperasińska Irena , Gryko Daniel T. 
Published: September 2016

AbstractThe fluorescence properties of two new families of heterocycles possessing either a seven‐ or five‐membered ring attached at the core molecule are entirely different in solution and in the solid state. Crystallization has the effect of inhibiting non‐radiative excited‐state deactivation pathways, operative in solution for the seven‐membered ring compounds, thus leading to significant fluorescence efficiency in the solid state, with quantum yields ranging from 0.10 to 0.36. Conversely, the five‐membered ring derivatives, which display notable emission properties in solution, are almost non‐emissive in the crystalline state, characterized by a long‐range π‐stacked arrangement. When embedded in polymeric films, both series show fluorescence features similar to the solution case, with remarkable fluorescence quantum yields ranging from 0.09 to 0.41. According to quantum chemical calculations, 3H‐chromeno[3,4‐c]pyridine‐4,5‐diones show the specific mechanism of fluorescence quenching. The derivatives bearing the seven‐membered ring undergo, in solution, a significant structural deformation in the excited state, resulting in a large decrease of the energy gap between S1 and S0 and hence to a substantial contribution of the internal conversion in the relaxation process. The fluorescence quenching of the five‐membered ring derivatives is in turn related to the intermolecular interaction between adjacent molecules prevailing to a greater extent in the crystal lattice.
Oxo‐Functionalized Graphene as a Cell Membrane Carrier of Nucleic Acid Probes Controlled by Aging
Authors: Pieper H. , Halbig C. E. , Kovbasyuk L. , Filipovic M. R. , Eigler S. , Mokhir A. 
Published: September 2016

AbstractWe applied a fluorescein‐containing oligonucleotide (ON) to probe surface properties of oxidized graphene (oxo‐G) and observed that graphene‐like patches are formed upon aging of oxo‐G, indicated by enhanced probe binding and by FTIR spectroscopic analysis. By using a recently developed fluorogenic endoperoxide (EP) probe, we confirmed that during the aging process the amount of EPs on the oxo‐G surface is reduced. Furthermore, aging was found to strongly affect cell membrane carrier properties of this material. In particular, freshly prepared oxo‐G does not act as a carrier, whereas oxo‐G aged for 28 days at 4 °C is an excellent carrier. Based on these data we prepared an optimized oxo‐G, which has a low‐defect density, binds ONs, is not toxic, and acts as cell membrane carrier. We successfully applied this material to design fluorogenic probes of representative intracellular nucleic acids 28S rRNA and β‐actin‐mRNA. The results will help to standardize oxidized graphene derivatives for biomedical and bioanalytical applications.
Allosteric and Chelate Cooperativity in Divalent Crown Ether/Ammonium Complexes with Strong Binding Enhancement
Authors: von Krbek Larissa K. S. , Achazi Andreas J. , Solleder Marthe , Weber Marcus , Paulus Beate , Schalley Christoph A. 
Published: September 2016

AbstractA thorough thermodynamic analysis by isothermal titration calorimetry of allosteric and chelate cooperativity effects in divalent crown ether/ammonium complexes is combined with DFT calculations including implicit solvent on the one hand and large‐scale molecular dynamics simulations with explicit solvent molecules on the other. The complexes studied exhibit binding constants up to 2×106 m−1with large multivalent binding enhancements and thus strong chelate cooperativity effects. Slight structural changes in the spacers, that is, the exchange of two ether oxygen atoms by two isoelectronic methylene groups, cause significantly stronger binding and substantially increased chelate cooperativity. The analysis is complemented by the examination of solvent effects and allosteric cooperativity. Such a detailed understanding of the binding processes will help to efficiently design and construct larger supramolecular architectures with multiple multivalent building blocks.
The Total Synthesis of the Bioactive Natural Product Plantazolicin A and Its Biosynthetic Precursor Plantazolicin B
Authors: Fenner Sabine , Wilson Zoe E. , Ley Steven V. 
Published: September 2016

AbstractHerein, we describe our full investigations into the synthesis of the peptide‐derived natural product plantazolicin A, a compound that demonstrates promising selective activity against the causative agent of anthrax toxicity, and its biosynthetic precursor plantazolicin B. This report particularly focuses on the challenging preparation of the arginine containing thiazole fragment, including the development of a robust, high yielding procedure that avoids the use of sulfurating agents. Extensive studies on the design of a coherent protecting group strategy and the establishment of a step‐efficient dicyclization/oxidation approach allowed high levels of convergence for the construction of the oxazole fragments. This has led to a unified, highly convergent synthesis for both plantazolicin A and B.
Cyclobutenones and Benzocyclobutenones: Versatile Synthons in Organic Synthesis
Authors: Chen Peng‐hao , Dong Guangbin 
Published: September 2016

AbstractCyclobutenones, four‐membered ketones bearing an unsaturated carbon–carbon double bond, and their structural sibling benzocyclobutenones, possess unique reactivity. Owing to their inherent high ring strain, such structures readily undergo ring opening under a variety of conditions, including thermolysis, photolysis, and transition metal catalysis, to afford reactive intermediates that can be trapped with nucleophiles, dienophiles, and unsaturated bonds. Their electron‐deficient enone moieties are good electrophiles for facile nucleophilic addition. Such properties render cyclobutenones versatile synthons, serving as excellent coupling partners in a vast array of synthetically valuable transformations.
Rhodium‐Catalyzed Dynamic Kinetic Asymmetric Allylation of Phenols and 2‐Hydroxypyridines
Authors: Li Changkun , Breit Bernhard 
Published: September 2016

AbstractInspired by the mechanistic studies of rhodium‐catalyzed atom‐economic addition of carboxylate acids to allenes, a rhodium‐catalyzed dynamic kinetic asymmetric allylation of different nucleophiles with racemic allylic carbonates has been developed. High regio‐ and enantioselectivities can be obtained under neutral conditions and, furthermore, the chemoselectivities can be controlled by different diphosphine ligands. (R,R)‐QuinoxP* leads to selective O‐allylation of phenols, whereas when embedding (S,S)‐DIOP as the ligand, 2‐naphthol is ortho‐C‐allylated for the first time in high enantioselectivity. To this end, hydroxypyridines can be N‐allylated by RhI/(S)‐DTBM‐Segphos via the same intermediate as in the previously reported atom‐economic addition to allenes.
Comparison of the Flow of Permanent and Condensable Gases through an Asymmetric Porous Membrane
Authors: Uchytil Petr , Reznickova Jirina , Setnickova Katerina , Loimer Thomas 
Published: September 2016

AbstractPorous inorganic membranes are usually composed of several layers, which are asymmetric with respect to the flow direction. For permanent gases, investigations about the influence of the flow direction on the mass flux through an asymmetric ceramic membrane were previously performed and can be found in literature. Mass flow differences between the two flow directions were calculated. Here the flow of condensable gases, i.e., of vapors, through the same membrane is analyzed and it is shown that the mass flow might be up to 40 % larger in one direction than in the other direction.
Discovery of α‐Substituted Imidazole‐4‐acetic Acid Analogues as a Novel Class of ρ1 γ‐Aminobutyric Acid Type A Receptor Antagonists with Effect on Retinal Vascular Tone
Authors: Krall Jacob , Brygger Benjamin M. , Sigurðardóttir Sara B. , Ng Clarissa K. L. , Bundgaard Christoffer , Kehler Jan , Nielsen Birgitte , Bek Toke , Jensen Anders A. , Frølund Bente 
Published: September 2016

AbstractThe ρ‐containing γ‐aminobutyric acid type A receptors (GABAARs) play an important role in controlling visual signaling. Therefore, ligands that selectively target these GABAARs are of interest. In this study, we demonstrate that the partial GABAAR agonist imidazole‐4‐acetic acid (IAA) is able to penetrate the blood–brain barrier in vivo; we prepared a series of α‐ and N‐alkylated, as well as bicyclic analogues of IAA to explore the structure–activity relationship of this scaffold focusing on the acetic acid side chain of IAA. The compounds were prepared via IAA from l‐histidine by an efficient minimal‐step synthesis, and their pharmacological properties were characterized at native rat GABAARs in a [3H]muscimol binding assay and at recombinant human α1β2γ2S and ρ1 GABAARs using the FLIPR™ membrane potential assay. The (+)‐α‐methyl‐ and α‐cyclopropyl‐substituted IAA analogues ((+)‐6 a and 6 c, respectively) were identified as fairly potent antagonists of the ρ1 GABAAR that also displayed significant selectivity for this receptor over the α1β2γ2S GABAAR. Both 6 a and 6 c were shown to inhibit GABA‐induced relaxation of retinal arterioles from porcine eyes.
“Pseudo solid” nuclear spin echo study of poly(ethylene oxide) grafted on silica. Comparison with magic‐angle spinning technique results
Authors: Tajouri Tahar , Ben Mariem Mohamed Aymen , Hommel Hubert 
Published: September 2016

AbstractThe polymer/solid interface of Poly (ethylene oxide) (PEO) grafted on silica is studied by 1H NMR. For grafted polymers, the dipolar interaction is an important factor in the spin–spin relaxation process. For this purpose, the part of the dipolar interaction that is not averaged to zero by the motion is used. The “pseudo solid” spin echo can indeed give an estimation of the nonzero average dipolar interactions. The appropriate pulse sequence permits a standard measurement of the average dipolar spin coupling involved in the transverse magnetization relaxation. The influence of some major parameters such as molecular weights of the chains, grafting ratios, and temperatures on the relaxation and ultimately on the concentration is followed by “pseudo solid” spin echo. The magic‐angle spinning technique is also used. The sample rotation confirms by the narrowing of the central line and the appearance of side bands, the existence of a residual dipolar interaction which reveals the concentration of high monomer units at the surface. The study of the side bands permits to calculate the second moment as a function of temperature. A fair agreement is obtained by these two independent techniques: pseudo solid echo and magic‐angle spinning.