bluuebunny/crossref_metadata_2025 huggingface dataset:
Global optimality properties of total annualized and operating cost problems for compressor sequences
Authors: Conner Jeremy A. , Manousiouthakis Vasilios I.
Published: August 2014

The minimum total annualized cost problem for a series of nonisentropic compressors and coolers that brings a gas with constant compressibility factor from a specified initial pressure and temperature to a specified final pressure and the same temperature is studied in this work. It is established analytically that at the global optimum, the cooler outlet temperatures are equal to the minimum allowable temperature. For constant heat capacity, constant compressibility factor gases, additional properties of the globally optimal compressor sequence are analytically established for the minimum operating cost case. The aforementioned properties permit development of a solution strategy that identifies the globally minimum operating cost. Several case studies are presented to illustrate the developed theorems and solution strategies. © 2014 American Institute of Chemical Engineers AIChE J 60: 4134–4149, 2014
Hypomethylation of the paternally inherited LRRTM1 promoter linked to schizophrenia
Authors: Brucato Nicolas , DeLisi Lynn E. , Fisher Simon E. , Francks Clyde
Published: August 2014

Epigenetic effects on psychiatric traits remain relatively under‐studied, and it remains unclear what the sizes of individual epigenetic effects may be, or how they vary between different clinical populations. The gene LRRTM1 (chromosome 2p12) has previously been linked and associated with schizophrenia in a parent‐of‐origin manner in a set of affected siblings (LOD = 4.72), indirectly suggesting a disruption of paternal imprinting at this locus in these families. From the same set of siblings that originally showed strong linkage at this locus, we analyzed 99 individuals using 454‐bisulfite sequencing, from whole blood DNA, to measure the level of DNA methylation in the promoter region of LRRTM1. We also assessed seven additional loci that would be informative to compare. Paternal identity‐by‐descent sharing at LRRTM1, within sibling pairs, was linked to their similarity of methylation at the gene's promoter. Reduced methylation at the promoter showed a significant association with schizophrenia. Sibling pairs concordant for schizophrenia showed more similar methylation levels at the LRRTM1 promoter than diagnostically discordant pairs. The alleles of common SNPs spanning the locus did not explain this epigenetic linkage, which can therefore be considered as largely independent of DNA sequence variation and would not be detected in standard genetic association analysis. Our data suggest that hypomethylation at the LRRTM1 promoter, particularly of the paternally inherited allele, was a risk factor for the development of schizophrenia in this set of siblings affected with familial schizophrenia, and that had previously showed linkage at this locus in an affected‐sib‐pair context. © 2014 Wiley Periodicals, Inc.
Epigenetic promoter silencing in Friedreich ataxia is dependent on repeat length
Authors: Chutake Yogesh K. , Lam Christina , Costello Whitney N. , Anderson Michael , Bidichandani Sanjay I.
Published: August 2014

Objective

Friedreich ataxia (FRDA) is caused by an expanded GAA triplet‐repeat (GAA‐TR) mutation in the FXN gene. Patients are typically homozygous for expanded alleles containing 100 to 1,300 triplets, and phenotypic severity is significantly correlated with the length of the shorter of the 2 expanded alleles. Patients have a severe deficiency of FXN transcript, which is predominantly caused by epigenetic silencing of the FXN promoter. We sought to determine whether the severity of FXN promoter silencing is related to the length of the expanded GAA‐TR mutation in FRDA.

Methods

Patient‐derived lymphoblastoid cell lines bearing a range of expanded alleles (200–1,122 triplets) were evaluated for FXN transcript levels by quantitative reverse transcriptase polymerase chain reaction. FXN promoter function was directly measured by quantitative analysis of transcriptional initiation via metabolic labeling of newly synthesized transcripts in living cells.

Results

FXN transcriptional deficiency was significantly correlated with the length of the shorter of the 2 expanded alleles, which was noted both upstream (R2 = 0.84, p = 0.014) and downstream (R2 = 0.89, p = 0.002) of the expanded GAA‐TR mutation, suggesting that FXN promoter silencing in FRDA is related to repeat length. A bilinear regression model revealed that length dependence was strongest when the shorter of the 2 expanded alleles contained <400 triplets. Direct measurement of FXN promoter activity in patients with expanded alleles containing <400 versus >400 triplets in the shorter of the 2 expanded alleles revealed a significantly greater deficiency in individuals with longer GAA‐TR alleles (p < 0.05).

Interpretation

FXN promoter silencing in FRDA is dependent on the length of the expanded GAA‐TR mutation. Ann Neurol 2014;76:522–528
Schwefel(VI)‐fluorid‐Austausch (SuFEx): Eine weitere gute Anwendung für die Click‐Chemie
Authors: Dong Jiajia , Krasnova Larissa , Finn M. G. , Sharpless K. Barry
Published: August 2014

Arylsulfonylchloride (z. B. Ts‐Cl) sind die am häufigsten eingesetzten SVI‐Elektrophile in der organischen Synthesechemie, und auch die Stammverbindung, das Sulfurylchlorid (O2SVICl2), wurde zur Synthese von Sulfaten und Sulfamiden genutzt. Allerdings wird die gewünschte Halogenidsubstitution oftmals durch die Zersetzung des Schwefelelektrophils in SIV‐Spezies und Cl− verhindert, denn die SVI‐Cl‐Bindung ist äußerst reduktionsanfällig. Mit Schwefel(VI)‐fluoriden (z. B. R‐SO2‐F und SO2F2) verläuft die Umsetzung hingegen ausschließlich über den Substitutionsweg. Wie es bei der Click‐Chemie zumeist der Fall ist, wurden viele entscheidende Aspekte der Reaktivität von Schwefel(VI)‐fluoriden vor langer Zeit in Deutschland entdeckt.6a Überraschenderweise gerieten diese außerordentlichen Arbeiten in der Mitte des 20. Jahrhunderts ziemlich abrupt aus dem Blickfeld. In diesem Aufsatz versuchen wir, dieser Chemie neues Leben einzuhauchen. Insbesondere stützen wir uns dabei auch auf John Hyatts unbeachtet gebliebene Veröffentlichung über CH2CH‐SO2‐F aus dem Jahr 1979.98 Wir tragen mehrere neue Beobachtungen bei, einschließlich dem Befund, dass das ansonsten sehr stabile Gas SO2F2 eine exzellente Reaktivität unter den richtigen Umständen aufweist. Wir zeigen auch, dass Protonen oder Siliciumzentren den Austausch von S‐F‐Bindungen gegen S‐O‐Bindungen aktivieren können und dass der Sulfat‐Konnektor überraschend hydrolysestabil ist. Anwendungen dieser kontrollierbaren Ligationschemie auf kleine Moleküle, Polymere und Biomoleküle werden diskutiert.
Chemical Probing of the Human Sirtuin 5 Active Site Reveals Its Substrate Acyl Specificity and Peptide‐Based Inhibitors
Authors: Roessler Claudia , Nowak Theresa , Pannek Martin , Gertz Melanie , Nguyen Giang T. T. , Scharfe Michael , Born Ilona , Sippl Wolfgang , Steegborn Clemens , Schutkowski Mike
Published: August 2014

Sirtuins are NAD+‐dependent deacetylases acting as sensors in metabolic pathways and stress response. In mammals there are seven isoforms. The mitochondrial sirtuin 5 is a weak deacetylase but a very efficient demalonylase and desuccinylase; however, its substrate acyl specificity has not been systematically analyzed. Herein, we investigated a carbamoyl phosphate synthetase 1 derived peptide substrate and modified the lysine side chain systematically to determine the acyl specificity of Sirt5. From that point we designed six potent peptide‐based inhibitors that interact with the NAD+ binding pocket. To characterize the interaction details causing the different substrate and inhibition properties we report several X‐ray crystal structures of Sirt5 complexed with these peptides. Our results reveal the Sirt5 acyl selectivity and its molecular basis and enable the design of inhibitors for Sirt5.
Antifreezes Act as Catalysts for Methane Hydrate Formation from Ice
Authors: McLaurin Graham , Shin Kyuchul , Alavi Saman , Ripmeester John A.
Published: August 2014

Contrary to the thermodynamic inhibiting effect of methanol on methane hydrate formation from aqueous phases, hydrate forms quickly at high yield by exposing frozen water–methanol mixtures with methanol concentrations ranging from 0.6–10 wt % to methane gas at pressures from 125 bars at 253 K. Formation rates are some two orders of magnitude greater than those obtained for samples without methanol and conversion of ice is essentially complete. Ammonia has a similar catalytic effect when used in concentrations of 0.3–2.7 wt %. The structure I methane hydrate formed in this manner was characterized by powder X‐ray diffraction and Raman spectroscopy. Steps in the possible mechanism of action of methanol were studied with molecular dynamics simulations of the Ih (0001) basal plane exposed to methanol and methane gas. Simulations show that methanol from a surface aqueous layer slowly migrates into the ice lattice. Methane gas is preferentially adsorbed into the aqueous methanol surface layer. Possible consequences of the catalytic methane hydrate formation on hydrate plug formation in gas pipelines, on large scale energy‐efficient gas hydrate formation, and in planetary science are discussed.
Near‐IR‐Triggered, Remote‐Controlled Release of Metal Ions: A Novel Strategy for Caged Ions
Authors: Atilgan Ahmet , Tanriverdi Eçik Esra , Guliyev Ruslan , Uyar T. Bilal , Erbas‐Cakmak Sundus , Akkaya Engin U.
Published: August 2014

A ligand incorporating a dithioethenyl moiety is cleaved into fragments which have a lower metal‐ion affinity upon irradiation with low‐energy red/near‐IR light. The cleavage is a result of singlet oxygen generation which occurs on excitation of the photosensitizer modules. The method has many tunable factors that could make it a satisfactory caging strategy for metal ions.
Metal‐Free Hydrogenation Catalyzed by an Air‐Stable Borane: Use of Solvent as a Frustrated Lewis Base
Authors: Scott Daniel J. , Fuchter Matthew J. , Ashley Andrew E.
Published: August 2014

In recent years ‘frustrated Lewis pairs’ (FLPs) have been shown to be effective metal‐free catalysts for the hydrogenation of many unsaturated substrates. Even so, limited functional‐group tolerance restricts the range of solvents in which FLP‐mediated reactions can be performed, with all FLP‐mediated hydrogenations reported to date carried out in non‐donor hydrocarbon or chlorinated solvents. Herein we report that the bulky Lewis acids B(C6Cl5)x(C6F5)3−x (x=0–3) are capable of heterolytic H2 activation in the strong‐donor solvent THF, in the absence of any additional Lewis base. This allows metal‐free catalytic hydrogenations to be performed in donor solvent media under mild conditions; these systems are particularly effective for the hydrogenation of weakly basic substrates, including the first examples of metal‐free catalytic hydrogenation of furan heterocycles. The air‐stability of the most effective borane, B(C6Cl5)(C6F5)2, makes this a practically simple reaction method.
Au@Pt Nanoparticle Encapsulated Target‐Responsive Hydrogel with Volumetric Bar‐Chart Chip Readout for Quantitative Point‐of‐Care Testing
Authors: Zhu Zhi , Guan Zhichao , Jia Shasha , Lei Zhichao , Lin Shuichao , Zhang Huimin , Ma Yanli , Tian Zhong‐Qun , Yang Chaoyong James
Published: August 2014

Point‐of‐care testing (POCT) with the advantages of speed, simplicity, portability, and low cost is critical for the measurement of analytes in a variety of environments where access to laboratory infrastructure is lacking. While qualitative POCTs are widely available, quantitative POCTs present significant challenges. Here we describe a novel method that integrates an Au core/Pt shell nanoparticle (Au@PtNP) encapsulated target‐responsive hydrogel with a volumetric bar‐chart chip (V‐Chip) for quantitative POCT. Upon target introduction, the hydrogel immediately dissolves and releases Au@PtNPs, which can efficiently catalyze the decomposition of H2O2 to generate a large volume of O2 to move of an ink bar in the V‐Chip. The concentration of the target introduced can be visually quantified by reading the traveling distance of the ink bar. This method has the potential to be used for portable and quantitative detection of a wide range of targets without any external instrument.
A New Class of Organocatalysts: Sulfenate Anions
Authors: Zhang Mengnan , Jia Tiezheng , Yin Haolin , Carroll Patrick J. , Schelter Eric J. , Walsh Patrick J.
Published: August 2014

Sulfenate anions are known to act as highly reactive species in the organic arena. Now they premiere as organocatalysts. Proof of concept is offered by the sulfoxide/sulfenate‐catalyzed (1–10 mol %) coupling of benzyl halides in the presence of base to generate trans‐stilbenes in good to excellent yields (up to 99 %). Mechanistic studies support the intermediacy of sulfenate anions, and the deprotonated sulfoxide was determined to be the resting state of the catalyst.
Bacterial Imprinting at Pickering Emulsion Interfaces
Authors: Shen Xiantao , Svensson Bonde Johan , Kamra Tripta , Bülow Leif , Leo Jack C. , Linke Dirk , Ye Lei
Published: August 2014

The tendency of bacteria to assemble at oil–water interfaces can be utilized to create microbial recognition sites on the surface of polymer beads. In this work, two different groups of bacteria were first treated with acryloyl‐functionalized chitosan and then used to stabilize an oil‐in‐water emulsion composed of cross‐linking monomers that were dispersed in aqueous buffer. Polymerization of the oil phase followed by removal of the bacterial template resulted in well‐defined polymer beads bearing bacterial imprints. Chemical passivation of chitosan and cell displacement assays indicate that the bacterial recognition on the polymer beads was dependent on the nature of the pre‐polymer and the target bacteria. The functional materials for microbial recognition show great potential for constructing cell–cell communication networks, biosensors, and new platforms for testing antibiotic drugs.
Gold‐Catalyzed 1,2‐Acyloxy Migration/Intramolecular [3+2] 1,3‐Dipolar Cycloaddtion Cascade Reaction: An Efficient Strategy for Syntheses of Medium‐Sized‐Ring Ethers and Amines
Authors: Zhao Changgui , Xie Xingang , Duan Shuangshuang , Li Huilin , Fang Ran , She Xuegong
Published: August 2014

A highly efficient strategy for the formation of medium‐sized‐ring ethers and amines based on a gold‐catalyzed cascade reaction, involving enynyl ester isomerization and intramolecular [3+2] cyclization, has been developed. Various multisubstituted medium‐sized‐ring unsaturated ethers and amines were obtained through this transformation. This method represents one of the relatively few transition metal catalyzed intramolecular cycloaddition reactions for medium‐sized ring synthesis.
Carbon Dioxide as a Protecting Group: Highly Efficient and Selective Catalytic Access to Cyclic cis‐Diol Scaffolds
Authors: Laserna Victor , Fiorani Giulia , Whiteoak Christopher J. , Martin Eddy , Escudero‐Adán Eduardo , Kleij Arjan W.
Published: August 2014

The efficient and highly selective formation of a wide range of (hetero)cyclic cis‐diol scaffolds using aminotriphenolate‐based metal catalysts is reported. The key intermediates are cyclic carbonates, which are obtained in high yield and with high levels of diastereo‐ and chemoselectivity from the parent oxirane precursors and carbon dioxide. Deprotection of the carbonate structures affords synthetically useful cis‐diol scaffolds with different ring sizes that incorporate various functional groups. This atom‐efficient method allows the simple construction of diol synthons using inexpensive and accessible precursors and green metal catalysts and showcases the use of CO2 as a temporary protecting group.
Interrupted Imino‐Nazarov Cyclization of 1‐Aminopentadienyl Cation and Related Cascade Process
Authors: William Ronny , Wang Siming , Ding Feiqing , Arviana Elise Nerissa , Liu Xue‐Wei
Published: August 2014

Facile 4π conrotatory imino‐Nazarov cyclization of a 1‐aminopentadienyl cation generated from condensation an aldehyde and secondary aniline in the presence of a catalytic amount of a Lewis acid has been developed. Silver(I)‐catalyzed intramolecular arene trapping of the resulting cyclic oxyallyl cation leads to formation of tricyclic indoline‐fused cyclopentanone. The use of lanthanide salts allows transformation after the initial trapping to afford tetrahydroquinoline‐fused cyclopentenone in a concise manner.
Mechanism on the permeation of ethanol in nitrile gloves studied using positron annihilation lifetime spectroscopy
Authors: Pham Binh , Phalen Robert , Sasanuma Naoko , Dorsainvil Yacinthe , Tol Jacqueline , Zhang Renwu
Published: August 2014

Positron annihilation lifetime spectroscopy (PALS) was applied to study the mechanism of ethanol diffusion through commercial nitrile rubber gloves. Even though the untreated raw samples were very different in their colors and area densities (g/cm2), the correlation between the ethanol diffusion coefficient from permeation test and the free volume from PALS measurement is well consistent with the Vrentas‐Duda model. Via combining the PALS technique and the Vrentas‐Duda theory, it is revealed that (a) the diffusion coefficient is correlated to the number of free volume holes rather than the average size of holes, (b) the diffusion process is not regulated by the size of ethanol molecule but by the size of critical volume for polymer segments to migrate, (c) nitrile group does not present in the free volume hole where the diffusion of ethanol molecule takes place, but is embedded in polymer matrix, and therefore, does not directly interact with ethanol molecule, and (d) nitrile group affects the average size, but not the number of free volume holes. The experiment demonstrates that the PALS technique, being mainly used in pure academic researches, might have application in the glove industry due to its ability in measuring terminal free volume quantities, which are directly related to the permeation of small organic molecules through protective gloves. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41282.
Preadolescent Decision‐Making Competence Predicts Interpersonal Strengths and Difficulties: A 2‐Year Prospective Study
Authors: Weller Joshua A. , Moholy Maxwell , Bossard Elaine , Levin Irwin P.
Published: August 2014

Recent research has demonstrated that decision‐making competence (DMC), a latent construct reflecting individual differences in rational thought, is predictive of real‐world decision outcomes at various stages of life. This construct has been shown to be associated with concurrent and retrospective accounts of health‐risking behavior, but its predictive validity has yet to be demonstrated. In the present study, we examine this issue using a 2‐year prospective, multiple‐informant design. Specifically, we tested the degree to which preadolescent DMC (PA‐DMC) obtained at ages 10–11 years (Time 1; N = 101) predicted both self‐reports and caregiver reports of emotional, behavioral, and peer‐related difficulties obtained 2 years later (Time 2; N = 76). Holding variables such as numeracy and inhibitory control constant, lower Time 1 PA‐DMC scores predicted greater reported Time 2 psychosocial difficulties (i.e. peer, conduct, emotional, and hyperactivity/inattention problems). Additionally, higher PA‐DMC scores were associated with greater self‐reported prosocial behaviors at Time 2. These results highlight the utility of testing individual differences in rational responding. We discuss the potential for improving children's decision‐making processes. Copyright © 2014 John Wiley & Sons, Ltd.
Phenylboronate chromatography selectively separates glycoproteins through the manipulation of electrostatic, charge transfer, and cis‐diol interactions
Authors: Carvalho Rimenys J. , Woo James , Aires‐Barros M. Raquel , Cramer Steven M. , Azevedo Ana M.
Published: August 2014

Phenylboronate chromatography (PBC) has been applied for several years, however details regarding the mechanisms of interactions between the ligand and biomolecules are still scarce. The goal of this work is to investigate the various chemical interactions between proteins and their ligands, using a protein library containing both glycosylated and nonglycosylated proteins. Differences in the adsorption of these proteins over a pH range from 4 to 9 were related to two main properties: charge and presence of glycans. Acidic or neutral proteins were strongly adsorbed below pH 8 although the uncharged trigonal form of phenylboronate (PB) is less susceptible to forming electrostatic and cis‐diol interactions with proteins. The glycosylated proteins were only adsorbed above pH 8 when the electrostatic repulsion between the boronate anion and the protein surface was mitigated (at 200 mM NaCl). All basic proteins were highly adsorbed above pH 8 with PB also acting as a cation‐exchanger with binding occurring through electrostatic interactions. Batch adsorption performed at acidic conditions in the presence of Lewis base showed that charge‐transfer interactions are critical for protein retention. This study demonstrates the multimodal interaction of PBC, which can be a selective tool for separation of different classes of proteins.
Gold‐Catalyzed Cycloisomerization of 1,6,8‐Dienyne Carbonates and Esters to cis‐Cyclohepta‐4,8‐diene‐Fused Pyrrolidines
Authors: Rao Weidong , Sally  , Berry Stuart Neil , Chan Philip Wai Hong
Published: August 2014

A synthetic approach that provides access to cis‐cyclohepta‐4,8‐diene‐fused pyrrolidines efficiently through AuI‐catalyzed cycloisomerization of 1,6,8‐dienyne carbonates and esters at a low catalyst loading of 2 mol % is reported. Starting carbonates and esters with a pendant alkyl group on the terminal alkenyl carbon center were found to favor tandem 1,2‐acyloxy migration/cyclopropanation followed by Cope rearrangement of the resulting cis‐3‐azabicyclo[3.1.0]hexane intermediate. On the other hand, substrates containing a terminal diene or starting materials in which the distal alkene moiety bears a phenyl substituent were observed to undergo competitive but reversible 1,3‐acyloxy migration prior to the nitrogen‐containing bicyclic ring formation. The delineated reaction mechanism also provides experimental evidence for the reversible interconversion between the oft‐proposed organogold intermediates obtained in this step of the tandem process.
Highly Enantioselective Catalytic System for Asymmetric Copolymerization of Carbon Dioxide and Cyclohexene Oxide
Authors: Hua Yuan‐Zhao , Lu Liu‐Jie , Huang Pei‐Jin , Wei Dong‐Hui , Tang Ming‐Sheng , Wang Min‐Can , Chang Jun‐Biao
Published: August 2014

A new ligand can be easily prepared, and its intramolecular dinuclear zinc complexes act as a high performance catalyst for the asymmetric alternating copolymerization of cyclohexene oxide and CO2 under very mild conditions (1 atm CO2, room temperature), affording completely alternating polycarbonates with up to 93.8 % enantiomeric excess (ee) and 98 % yield. A high Mn value of 28 600 and a relatively narrow polydispersity (Mw/Mn ratio) of 1.43 were also achieved.
Thioetherification of Chloroheteroarenes: A Binuclear Catalyst Promotes Wide Scope and High Functional‐Group Tolerance
Authors: Platon Mélanie , Wijaya Novi , Rampazzi Vincent , Cui Luchao , Rousselin Yoann , Saeys Mark , Hierso Jean‐Cyrille
Published: August 2014

A constrained binuclear palladium catalyst system affords selective thioetherification of a wide range of functionalized arenethiols with chloroheteroaromatic partners with the highest turnover numbers (TONs) reported to date and tolerates a large variety of reactive functions. The scope of this system includes the coupling of thiophenols with six‐ and five‐membered 2‐chloroheteroarenes (i.e., functionalized pyridine, pyrazine, quinoline, pyrimidine, furane, and thiazole) and 3‐bromoheteroarenes (i.e., pyridine and furane). Electron‐rich congested thiophenols and fluorinated thiophenols are also suitable partners. The coupling of unprotected amino‐2‐chloropyridines with thiophenol and the successful employment of synthetically valuable chlorothiophenols are described with the same catalyst system. DFT studies attribute the high performance of this binuclear palladium catalyst to the decreased stability of thiolate‐containing resting states. Palladium loading was as low as 0.2 mol %, which is important for industrial application and is a step forward in solving catalyst activation/deactivation problems.
Versatile CuI/Pd0 Dual Catalysis for the Synthesis of Quaternary α‐Allylated Carbonyl Compounds: Development, Mechanistic Investigations and Scope
Authors: Nahra Fady , Macé Yohan , Boreux Arnaud , Billard Francois , Riant Olivier
Published: August 2014

We report herein a versatile cooperative dual catalysis reaction based on a CuI/Pd0 system. Mechanistic investigation shows that every component plays a crucial role in determining the reaction outcome. The reaction is successfully extended to various substrates; such as α,β‐unsaturated ketones, malonates and coumarins. The strategy tolerates different substitution patterns and affords good yields for each family of substrates.
N‐Alkylacylamides in Thin Films Display Infrared Spectra of 310‐, α‐, and π‐Helices with Visible Static and Dynamic Growth Phases
Authors: Kosower Edward M. , Borz Galina
Published: August 2014

A peptide model is a physical system containing a CONH group, the simplest being HCONHCH3, N‐methylformamide (NMF). We have discovered that NMF and N‐methylacetamide (NMA), which form hydrogen‐bonded oligomers in thin films on a planar AgX fiber, display infrared (IR) spectra with peaks like those of polypeptide helices. Structures can be assigned by their amide I maxima near 1672 (310), 1655 (310), 1653 (α), 1655 (π), and 1635 cm−1 (π), which are the first IR data for the π‐helix. Sharp peaks are an outcome of immobilization of polar species on the polar surface of silver halides. We report the first use of expanded thin‐film IR spectroscopy, in which plots of every spectrum over the amide I–II range show pauses or slow stages in the increase or decrease of absorption. These are identified as static phases followed by dynamic phases, with the incremental gain or loss of a helix turn. A general theory can be stated for such processes. Density functional calculations show that the NMA α‐helix pentamer (crystal structure geometry) is transformed into a π‐helix‐like form. For the first time, an entire sequence (310‐helix, α‐helix, π‐helix, quasiplanar species) of spectra has been recorded for NMA.
N‐Methyl‐trimethylacetamide in Thin Films Displays Infrared Spectra of π‐Helices, with Visible Static and Dynamic Growth Phases, and then a β‐Sheet
Authors: Kosower Edward M. , Borz Galina , Goldberg Israel , Ermakov Natalya
Published: August 2014

The simplest (minimal) peptide model is HCONHCH3. An increase in the π‐helix content with increased substitution in the acyl portion suggested the examination of N‐methyl‐trimethylacetamide) (NMT). NMT displays spectra, in which there is evolution of a set of helices defined by their amide I maxima near 1686 (310), 1655 (first π), and, most importantly, at 1637 cm−1 (π). Expanded thin‐film infrared spectroscopy (XTFIS) shows pauses or slow stages, which are identified as static phases followed by dynamic phases with the incremental gain or loss of a helix turn. In addition, absorbance at 1637 cm−1 suddenly increases at 82.1 s (30 % over 0.3 s), indicating a phase change and crystallization of the π‐helix, along with a coincidental decrease in the absorbance for the first π‐helix. A sharp peak occurs at the maximum of the phase change at 82.5 s, representing a pure NMT π‐helix. The spectra then undergo a decreasing general absorption loss over 150 s, with the π‐helix evolving further to an antiparallel β‐sheet fragment. The spectral quality arises from the immobilization of polar molecules on polar surfaces. The crystal structure is that of an antiparallel β‐sheet.
Theoretical Modeling of Low‐Energy Electronic Absorption Bands in Reduced Cobaloximes
Authors: Bhattacharjee Anirban , Chavarot‐Kerlidou Murielle , Dempsey Jillian L. , Gray Harry B. , Fujita Etsuko , Muckerman James T. , Fontecave Marc , Artero Vincent , Arantes Guilherme M. , Field Martin J.
Published: August 2014

The reduced CoI states of cobaloximes are powerful nucleophiles that play an important role in the hydrogen‐evolving catalytic activity of these species. In this work we analyze the low‐energy electronic absorption bands of two cobaloxime systems experimentally and use a variety of density functional theory and molecular orbital ab initio quantum chemical approaches. Overall we find a reasonable qualitative understanding of the electronic excitation spectra of these compounds but show that obtaining quantitative results remains a challenging task.
Synthesis of Urchin‐Like FeF2 Nanoarchitectures and Their Conversion into Three‐Dimensional Urchin‐Like Mesoporous α‐Fe2O3 Nanoarchitectures for Methane Activation
Authors: Dong Bing , Zhang Hengqiang , Kong Aiguo , Kong Yingying , Yang Fan , Shan Yongkui
Published: August 2014

Novel urchin‐like FeF2 nanoarchitectures have been fabricated by an unconventional nonhomogeneous ionic liquid/diphenyl ether solvothermal method. Subsequent solid‐state thermal annealing was utilized to convert the FeF2 nanoarchitectures into 3D urchin‐like mesoporous α‐Fe2O3 nanoarchitectures. The reaction system and temperature played important roles in the morphology of FeF2 and the growth of the 3D urchin‐like α‐Fe2O3. A study of methane activation over the 3D urchin‐like mesoporous α‐Fe2O3 nanoarchitectures revealed that methane was activated and converted into carbon dioxide at a low temperature (230 °C). Compounds containing C–C bonds were produced at 600 °C. This 3D urchin‐like mesoporous α‐Fe2O3 shows excellent potential as a catalyst for methane conversion in the chemical industry.
Highly Enantioselective Construction of Polycyclic Spirooxindoles by Organocatalytic 1,3‐Dipolar Cycloaddition of 2‐Cyclohexenone Catalyzed by Proline‐Sulfonamide
Authors: Xiao Jun‐An , Liu Qi , Ren Ji‐Wei , Liu Jian , Carter Rich G. , Chen Xiao‐Qing , Yang Hua
Published: August 2014

The enantioselective 1,3‐dipolar cycloaddition of 2‐cyclohexene‐1‐one and azomethine ylides generated in situ from isatins and amino esters was developed by employing prolinosulfonamides as the catalyst. Consequently, novel polycyclic spirooxindole scaffolds with three contiguous stereocenters were prepared in high yield (up to 95 %) with excellent diastereo‐ (>20:1 dr) and enantioselectivity (up to 99 % ee).
Fast and versatile fabrication of PMMA microchip electrophoretic devices by laser engraving
Authors: Gabriel Ellen Flávia Moreira , Coltro Wendell Karlos Tomazelli , Garcia Carlos D.
Published: August 2014

Electrophoresis 2014, 35, 2325–2332. DOI: 10.1002/elps.elps201300511

In order to demonstrate the versatility of the proposed methodology, a PMMA substrate was engraved following the conditions described in our article (CO2 laser engraving, raster mode, 1200 dpi) and then imaged using a 3D microscope. We believe these two instruments are very good complements of the traditional instrumentation linked to the fabrication and characterization of microfluidic devices and could provide not only a simple way to produce devices but also a new way to see the surface of the features produced.

image
QoS‐based power allocation for cognitive radios with AMC and ARQ in Nakagami‐m fading channels
Authors: Musavian Leila , Le‐Ngoc Tho
Published: August 2014

This paper presents power allocation schemes to maximize the effective capacity (EC) of a secondary user (SU) communications link using adaptive modulation and coding (AMC) in an underlay cognitive radio Nakagami‐m block‐fading environment to meet target quality‐of‐service (QoS) requirements in terms of delay‐outage probability and packet error rate constraints. The SU transmission parameters are chosen such that the primary user imposed interference power constraint (IPC) is satisfied. Three different types of IPCs, namely average interference power, peak interference power and interference power outage, are considered. For each IPC, the analytical solutions for choosing the AMC mode and power allocation in each fading block, and the corresponding SU achievable EC under given QoS requirements are derived. Furthermore, we investigate the performance of a hybrid automatic repeat request (ARQ)/AMC and obtain the closed‐form packet loss rate expression. Illustrative results show the effects of the IPC, fading duration and fading severeness on the SU achievable EC under given QoS requirements. It is shown that for loose delay‐outage requirements, average interference power and interference power outage constraints give higher SU EC than peak interference power constraint. However, for more stringent delay‐outage requirements, the SU achievable EC for the three IPC is significantly reduced. The results also indicate that ARQ is helpful to significantly reduce the packet loss rate for loose delay constraint. However, ARQ increases the delay and is not effective for stringent delay‐outage requirements. Copyright © 2014 John Wiley & Sons, Ltd.
Energy‐efficient opportunistic forwarding in multi‐hop cellular networks using device‐to‐device communications
Authors: Coll‐Perales B. , Gozalvez J. , Friderikos V.
Published: August 2014

Cellular networks face significant capacity, efficiency and quality challenges because of the exponential growth of cellular data traffic. Multi‐hop cellular networks (MCNs) have been proposed to address these challenges through the integration of cellular and device‐to‐device communications. This work investigates how the adoption and design of opportunistic store, carry and forward mechanisms in MCNs can help importantly decrease the energy consumption for delay tolerant traffic. To this aim, the study first derives an analytical framework to identify in two‐hop scenarios the optimum mobile relay location and the location from which the mobile relay should start forwarding the information to the cellular base station in order to minimise the overall energy consumption. The derived optimum configuration is then used as a benchmark for the proposal and design of a novel context‐based opportunistic MCN forwarding scheme that exploits context information provided at low cost by the cellular network. Numerical and simulation results demonstrate that the proposed context‐based opportunistic forwarding can achieve a performance close to that obtain with the optimum configuration and reduce the energy consumption by more than 90% compared with traditional single‐hop cellular communications. Copyright © 2014 John Wiley & Sons, Ltd.
A demand‐based spectrum orthogonalisation scheme for interference avoidance in LTE‐Advanced heterogeneous networks
Authors: Mohamad Maharum Siti M. , Fisal Norsheila , Lo Anthony , Ghafar Aimi S. A. , Saparudin Faiz Asraf , Katiran Norshidah
Published: August 2014

Successful deployment of femtocells within a macrocell coverage area would be hindered if cross‐layer and co‐layer interference in such heterogeneous networks (HetNets) is not properly mitigated. Through spectrum management, cross‐layer interference between macrocell and femtocell network layers can be avoided by assigning the network layers with orthogonal spectrum bands. However, the orthogonal spectrum assignments in prior works are no longer effective because they may not guarantee the variation of users' traffic demand in HetNets to be satisfied all the time. Therefore, a centralised and dynamic orthogonal spectrum assignment called demand‐based spectrum orthogonalisation (DeBaSO) is proposed in this paper to address the interference issues in downlink of LTE‐Advanced HetNets. In our proposed scheme, the problem of orthogonal spectrum assignment is formulated with the objective to maximise the overall system throughput based on the requirement of physical spectral resources to satisfy the users' traffic demand. Additionally, the co‐layer interference among femtocells is avoided by grouping the adjacent femtocells into different femtocell clusters. To do so, typical model of spatial frequency reuse is exploited in this paper. In this way, femtocells that are grouped within the same cluster can universally reuse the assigned spectrum resource without creating co‐layer interference among them. Numerical results indicate that the proposed scheme achieves a remarkable performance in terms of overall system throughput and spectrum efficiency because the cross‐layer and co‐layer interference is entirely avoided. The achievements prove that DeBaSO scheme overcomes the limitations found in other orthogonal spectrum assignments, which were previously proposed in the literature. Copyright © 2014 John Wiley & Sons, Ltd.
Torii: multipath distributed Ethernet fabric protocol for data centres with zero‐loss path repair
Authors: Rojas Elisa , Ibanez Guillermo , Gimenez‐Guzman Jose Manuel , Rivera Diego , Azcorra Arturo
Published: August 2014

This paper describes and evaluates Torii, a layer 2 data centre network fabric protocol. The main features of Torii are being fully distributed, scalable, fault‐tolerant and with automatic setup. Torii is based on multiple, tree‐based, topological media access control addresses that are used for table‐free forwarding over multiple equal‐cost paths, and it is capable of rerouting frames around failed links on the fly without needing a central fabric manager for any function. To the best of our knowledge, it is the first protocol that does not require the exchange of periodic messages to work under normal conditions and to recover from link failures, as Torii exchanges messages just once. Moreover, another important characteristic of Torii is that it is compatible with a wide range of data centre topologies. Simulation results show an excellent distribution of traffic load and latencies, similar to the shortest path protocols. Copyright © 2014 John Wiley & Sons, Ltd.
Population‐Based Association and Gene by Environment Interactions in Genetic Analysis Workshop 18
Authors: Satten Glen A. , Biswas Swati , Papachristou Charalampos , Turkmen Asuman , König Inke R.
Published: August 2014

In the past decade, genome‐wide association studies have been successful in identifying genetic loci that play a role in many complex diseases. Despite this, it has become clear that for many traits, investigation of single common variants does not give a complete picture of the genetic contribution to the phenotype. Therefore a number of new approaches are currently being investigated to further the search for susceptibility loci or regions. We summarize the contributions to Genetic Analysis Workshop 18 (GAW18) that concern this search using methods for population‐based association analysis. Many of the members of our GAW18 working group made use of data types that have only recently become available through the use of next‐generation sequencing technologies, with many focusing on the investigation of rare variants instead of or in combination with common variants. Some contributors used a haplotype‐based approach, which to date has been used relatively infrequently but may become more important for analyzing rare variant association data. Others analyzed gene‐gene or gene‐environment interactions, where novel statistical approaches were needed to make the best use of the available information without requiring an excessive computational burden. GAW18 provided participants with the chance to make use of state‐of‐the‐art data, statistical techniques, and technology. We report here some of the experiences and conclusions that were reached by workshop participants who analyzed the GAW18 data as a population‐based association study.
Multivariate Analyses of Blood Pressure Related Phenotypes in a Longitudinal Framework: Insights From Genetic Analysis Workshop 18
Authors: Ghosh Saurabh
Published: August 2014

Our working group studied methods for joint analyses of multiple phenotypes using the data provided by Genetic Analysis Workshop 18. Two data sets were available: one containing genotypes obtained from a real human whole‐genome sequencing study along with longitudinal measurements on systolic and diastolic blood pressure, age, sex, medication use, and tobacco smoking; and the other a simulated data set using the same set of genotypes and phenotype structure as the real data set. The nine sets of investigators in our working group focused on the statistical challenges posed by association analyses of multivariate phenotypes; they applied a wide spectrum of statistical methods, such as linear mixed models, copula models, and semiparametric regression models for simultaneous analyses of longitudinal data on the two blood pressure phenotypes at the genome‐wide level. In this report, we discuss the various strategies explored by the different investigators whose common goal was improving the power to detect association with multivariate phenotypes.
BDNF contributes to the facilitation of hippocampal synaptic plasticity and learning enabled by environmental enrichment
Authors: Novkovic Tanja , Mittmann Thomas , Manahan‐Vaughan Denise
Published: August 2014

Sensory, motor, and cognitive stimuli, resulting from interactions with the environment, play a key role in optimizing and modifying the neuronal circuitry required for normal brain function. An experimental animal model for this phenomenon comprises environmental enrichment (EE) in rodents. EE causes profound changes in neuronal and signaling levels of excitation and plasticity throughout the entire central nervous system and the hippocampus is particularly affected. The mechanisms underlying these changes are not yet fully understood. As brain‐derived neurotrophic factor (BDNF) supports hippocampal long‐term potentiation (LTP), we explored whether it participates in the facilitation of synaptic plasticity and hippocampus‐dependent learning that occurs following EE. In the absence of EE, LTP elicited by high‐frequency stimulation was equivalent in wildtype mice and heterozygous BDNF+/− siblings. LTP elicited by theta‐burst stimulation in BDNF+/− mice was less than in wildtypes. Long‐term depression (LTD) was also impaired. EE for three weeks, beginning after weaning, improved hippocampal LTP in both wildtype and transgenic animals, with LTP in transgenics achieving levels seen in wildtypes in the absence of EE. Object recognition memory was evident in wildtypes 24 h and 7 days after initial object exposure. EE improved memory performance in wildtypes 24 h but not 7 days after initial exposure. BDNF+/− mice in the absence of EE showed impaired memory 7 days after initial object exposure that was restored by EE. Western blotting revealed increased levels of BDNF, but not proBDNF, among both EE cohorts. These data support that BDNF plays an intrinsic role in improvements of synaptic plasticity and cognition that occur in EE. © 2014 The Authors. Hippocampus Published by Wiley Periodicals, Inc.
Identifying barriers to move to better health coverage: preferences for health insurance benefits among the rural poor population in La Guajira, Colombia
Authors: Amaya Jeannette Liliana , Ruiz Fernando , Trujillo Antonio J. , Buttorff Christine
Published: August 2014

Even though access to health insurance in Colombia has improved since the implementation of the 1993 health reforms (Law 100), universal coverage has not yet been accomplished. There is still a segment of the population under the low‐income (subsidized) health insurance policy or without health insurance altogether. The purpose of this research was to identify preferences and behavior regarding health insurance among the subsidized rural population in La Guajira, Colombia, and to understand why that population remains under the subsidized health insurance policy. The field experiment gathered information from 400 households regarding their socioeconomic situation, health conditions, and preferences for health insurance characteristics. Results suggest that the surveyed population gives priority to expanded family coverage, physician and hospital choice, and access to specialists, rather than to attributes associated with co‐payments or premiums. That indicates that people value healthcare benefits and family coverage more than health insurance expenses, and policy makers could use these preferences to enroll subsidized population into the contributory regime. Copyright © 2014 John Wiley & Sons, Ltd.
Anticonvulsants to treat post‐traumatic stress disorder
Authors: Wang Hee Ryung , Woo Young Sup , Bahk Won‐Myong
Published: August 2014

Objective

We reviewed the existing literature on the efficacy of anticonvulsants in treating post‐traumatic stress disorder.

Methods

We performed a literature search using PubMed, EMBASE and the Cochrane database on 30 September 2013. Randomized, controlled studies that investigated the efficacy of anticonvulsants for post‐traumatic stress disorder were included in this review. Studies with retrospective designs, case reports and case series were excluded.

Results

A total of seven studies met the inclusion criteria for this review. Three studies used topiramate with negative findings regarding its efficacy. Two studies used divalproex, both of which failed to show superiority over placebo. One study used lamotrigine, with favourable results, and one study used tiagabine, with negative results.

Conclusions

Future long‐term studies with larger sample sizes are needed to investigate the clinical utility of anticonvulsants for post‐traumatic stress disorder treatment. Copyright © 2014 John Wiley & Sons, Ltd.
FELLOWSHIP RECORD EXAMINATION
Authors: Swineford Frances
Published: August 2014

This summary contains data from validity studies conducted between October ′46 and July ′49. It is planned that additional supplements will be compiled from time to time in the future. In this connection, suggestions are invited for improving the organization of the material, as are requests for additional information to be included in subsequent summaries.
REPORT ON THE VALIDATION OF TESTS AGAINST FIRST AND SECOND TERM GRADES AND QUALITY‐POINT RATIOS AT THE U. S. NAVAL POSTGRADUATE SCHOOL (JULY 1948 TESTING)
Authors: Mollenkopf William G.
Published: August 2014

Scores on the 20 aptitude and achievement tests given in July 1948 have been correlated with each other and with first and second term grades at the Naval Postgraduate School. The following tests correlated higher than .40 with the criterion of Quality‐Point Ratio for both of the terms: (1) Engineering Achievement Test in Mathematics, (2) Physics SA, (3) the Graduate Record Examination Advanced Test in Engineering, (4) Reading Comprehension, (5) Mathematics WSA2, and (6) Mathematics WIM3. Several other tests showed significant but lesser degrees of validity for predicting the Q.P.R. or one or more course grades.

The technique of multiple correlation was also used, and shewed that mathematics and engineering wore the two areas which contributed most heavily to the prediction of grades in the first two terms.

Item analyses of the mathematics, engineering and physics tests have been carried out as an aid to further test development.

Results for the first two terms have been very encouraging and indicate that initial efforts to predict academic success at the Naval Postgraduate School have been quite fruitful.