bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel extrusion process for the production of polymer micropellets
Authors: Schäfer Christian , Meyer Stefan P. , Osswald Tim A.
Published: March 2018

Traditional micropellet and powder‐based polymer processing techniques, such as powder bed fusion, compression molding, and rotational molding have shown an increased demand in polymer processing. These processes require powders and micropellets with a small particle size, narrow size distribution and defined geometry for a variety of polymer resins. Therefore, micropelletization technologies, where particles in the size range of 50–1,000 μm are generated, have been attracting growing attention over the past decade. A new technique, presented here, yields micropellets with a controlled morphology and narrow particle size distribution. In this process, a polymer melt is extruded through a capillary and is subsequently stretched with a hot airstream until flow instabilities or melt fracture cause it to break up into particles. Small changes in process conditions result in different size distributions and particle shapes, such as lenticular pellets, fibers, and strand segments. This work shows how processing parameters and different polymer materials influence the produced micropellets. Depending on the processed polymer resin and process conditions, spherical particles with sizes ranging from 50 to 1,000 μm can be produced using the novel extrusion technique. Comprehensive design of experiment and data analysis was used to establish a more detailed understanding of the micropelletization process. POLYM. ENG. SCI., 58:2264–2275, 2018. © 2018 Society of Plastics Engineers
Extrusion foaming of thermoplastic cellulose acetate sheets with HFO‐1234ze and co‐blowing agents
Authors: Hendriks Sven , Hopmann Christian , Zepnik Stefan
Published: March 2018

Cellulose acetate is a bio‐based plastic which can be used to produce foam sheets through the extrusion process. In this study, different co‐blowing agents (BAs) were added to the foaming process in order to improve the extrusion foaming behavior and cell density of sheets foamed with HFO‐1234ze. The effect of co‐BAs on the melt viscosity was investigated with an inline extrusion rheometer. Furthermore, the resulting cell morphology of foam sheets was studied. While the plasticizing effect of the co‐BA is similar to HFO‐1234ze, the cell density of the foam sheets could be improved by adding co‐BAs in concentrations between 0.04 and 0.16 mol/kg. Adding 0.06 mol/kg of ethanol increased the cell density from approximately 1 to 12 × 105 1/cm³ at an invariant density of ∼130 kg/m³. The density reduction of the foam sheets can be calculated in good agreement from the molar concentration of the BAs. However, high amounts of co‐BA slightly reduce the BA yield. POLYM. ENG. SCI., 58:E182–E188, 2018. © 2018 Society of Plastics Engineers
Apelins, ELABELA, and their derivatives: Peptidic regulators of the cardiovascular system and beyond
Authors: Murza Alexandre , Trân Kien , Bruneau‐Cossette Laurent , Lesur Olivier , Auger‐Messier Mannix , Lavigne Pierre , Sarret Philippe , Marsault Éric
Published: March 2018

The apelinergic system emerges as an important regulator of cardiovascular functions via its actions on the heart, vasculature, and kidney. It also possesses additional beneficial properties, via its actions on the pancreas and skeletal muscle, on type 2 diabetes. The apelinergic system distinguishes itself by the presence of two structurally distinct sets of endogenous ligands, the Apelins (–13, −17, and −36) and Elabela, which both activate the apelin (APJ) receptor. In the past decade, numerous peptidic ligands have been used to better understand the structure–activity relationship of apelin (and more recently Elabela), providing important tools to rationalize how ligand modifications impact receptor structure and dynamics as well as its downstream signaling. The recently disclosed structure of the apelin receptor in complex with an analogue of apelin‐17 provides an important tool in this quest. In this review, we first summarize the physiopharmacology of the apelinergic system, then, review existing knowledge on the various ligands of the apelin receptor with an emphasis on peptidic ligands, although small molecules are covered as well. Throughout this work, we tried to integrate existing knowledge of ligands’ pharmacological profiles with structure and signaling profile.
Procalcitonin Monitoring as a Guide for Antimicrobial Therapy: A Review of Current Literature
Authors: Covington Elizabeth W. , Roberts Megan Z. , Dong Jenny
Published: March 2018

Effective antimicrobial stewardship practices are increasingly essential to best utilize the current arsenal of antimicrobials for the shortest necessary duration to minimize the development of antimicrobial resistance, secondary infections, and health care costs. Monitoring of serum procalcitonin (PCT) levels represents an effective antimicrobial stewardship strategy to differentiate bacterial infections from viral infections and noninfectious inflammatory conditions. Current literature illustrates the merits of PCT monitoring in reducing duration of antibiotic therapy without detrimental effects on mortality or infection relapses. However, the interpretation of PCT levels can be challenging, especially in light of comorbid disease states that can elevate PCT levels. This review sheds light on the utility of PCT monitoring, as well as providing insight into the practical interpretation of PCT levels. Much of the current literature surrounding PCT monitoring consists of use among patients with lower respiratory tract infections or in the critically ill. Overall, studies have demonstrated shorter antibiotic therapy durations when PCT monitoring is utilized. No studies to date have found increased rates of mortality or infection relapses, suggesting that PCT monitoring is not only effective, but also safe when used as a guide for antimicrobial therapy. Nonetheless, many conditions were shown to elevate PCT serum concentrations, even in the absence of bacterial infections, which can make interpretation of PCT concentrations challenging. Two common conditions that affect the accurate interpretation of PCT levels are renal dysfunction and congestive heart failure. Limited studies have been performed in these populations, but current available data propose the need for higher PCT thresholds in those with renal dysfunction or congestive heart failure and support utilizing PCT trends to monitor clinical improvement from bacterial infections. Evidence also suggests that PCT monitoring is cost‐effective, as long as the test is ordered judiciously. In summary, PCT monitoring represents a promising antimicrobial stewardship strategy to limit exposure to unnecessary antimicrobial therapy.
Systematic Review and Meta‐Analysis of Real‐World Studies Evaluating Rivaroxaban for Cancer‐Associated Venous Thrombosis
Authors: Martinez Brandon K. , Sheth Jit , Patel Nishi , Baker William L. , Coleman Craig I.
Published: March 2018

Introduction

While not designated as guideline‐recommended first‐line anticoagulation therapy, about one in five patients in the United States receive rivaroxaban for the treatment of cancer‐associated venous thrombosis (CAT).

Methods

A systematic review and meta‐analysis were performed to evaluate the incidences of recurrent venous thromboembolism (VTE), major bleeding, and all‐cause mortality in rivaroxaban patients treated for CAT in routine practice. Literature searches of MEDLINE and SCOPUS were performed through September 2017 to identify real‐world studies of ≥ 20 patients evaluating the incidence of recurrent VTE, major bleeding, or all‐cause mortality in CAT patients anticoagulated with rivaroxaban. Using a Hartung‐Knapp random‐effects model, the pooled incidence estimates and 95% confidence intervals (CIs) were calculated for each end point.

Results

Six studies evaluating rivaroxaban for CAT were identified. Of these, three were prospective and three were retrospective. Study sample sizes ranged from 41 to 949 patients, and duration of follow‐up ranged from 164 to 496 days. The most frequent active cancer sites reported in studies were gastrointestinal (range: 12.0–56.0%), genitourinary (range: 8.6–26.0%), and breast (range: 9.3–25.5%). The weighted average incidences of recurrent VTE, major bleeding, and all‐cause mortality were 4.2% (95% CI = 2.6–6.6%; I2 = 31%), 2.9% (95% CI = 1.6–5.0%; I2 = 59%), and 16.1% (95% CI = 6.0–36.6%; I2 = 96%).

Conclusions

This meta‐analysis suggests that incidences of recurrent VTE and major bleeding among rivaroxaban‐managed patients are not dissimilar to those seen in recent randomized trials of anticoagulation in CAT. The pooled incidence for mortality was lower than reported in many anticoagulation CAT trials. This may suggest that rivaroxaban is being used in CAT patients who have less severe cancer.
Characterization of thermally crosslinkable polyester films by thermomechanical analysis: a versatile and very sensitive technique for the evaluation of low crosslinking degree in polymers
Authors: Prataviera Rogério , Pessan Luiz Antonio , Carvalho Antonio José Felix
Published: March 2018

Thermomechanical analysis (TMA) is an effective technique for the characterization of small samples such as thin films of micrometric thickness, allowing the determination of thermal events such as glass transition, softening temperature and thermal expansion. Here we describe use of the TMA technique to investigate the drying and curing properties of polyester thin films ranging from 40 to 70 μm thick. The main purpose of this study was to investigate the effects of residual solvent and crosslinking on the glass transition and softening temperatures of the polyester films subjected to thermal cycling. Despite the fact that the analysed films were thinner than 100 μm, TMA proved to be very sensitive to small changes in residual solvent content and to the effects of the degree of crosslinking on the glass transition and softening temperatures of the polymer films. The most important finding is the possibility of detecting very small degrees of crosslinking in an easy, fast and quantitative way. Other methods such as swelling were not sensitive enough to differentiate the crosslinked samples and data for thicker films are not comparable to the data for thin films. © 2018 Society of Chemical Industry
Sulfonated poly(butylene succinate) as a pseudo‐random copolymer: effect of sulfonate groups on microstructure and thermal behavior
Authors: Kaykha Yasin , Rafizadeh Mehdi
Published: March 2018

The positional effect of sulfonate groups on poly(butylene succinate) (PBS) microstructure was investigated. In this regard, unsaturated poly(butylene fumarate) (PBF) and poly(butylene succinate‐ran‐fumarate) copolymers, synthesized via esterification/polycondensation reactions, were modified through post‐polymerization modification. The progress of the PBF sulfonation reaction was analyzed via 1H NMR, dynamic light scattering and field emission SEM. The microstructure and thermal behavior of the functional polyesters were studied through DSC, TGA, elemental analysis and 1H NMR. Based on the results, the sulfonation reaction of unsaturated polymer chains, which are not experiencing a phase separation, is instantaneous, but sulfonation of the chains that have formed colloidal particles is a time‐consuming process. Surprisingly, the outcomes of 1H NMR analysis revealed a kind of heterogeneity along the fully sulfonated PBS backbone, similar to what is usually observed for copolymers. This is due to the ability of sulfonate groups to locate in different sites and create various block types. Due to the attraction between sulfonate groups, they tend to attach to the chain such that they provide the greatest number of second type blocks (containing two sulfonate groups). The randomness of sulfonated polymers after the sulfonation reaction was increased compared to that of the corresponding unsaturated copolymers. Increasing the content of sulfonate groups also led to a significant decrease in the thermal resistance (ca 120 °C) and crystallinity, along with a dramatic increase in ash content and Tg (up to 156 °C). © 2018 Society of Chemical Industry
Polymers beyond standard optical fibres – fabrication of microstructured polymer optical fibres
Authors: Arrospide Eneko , Durana Gaizka , Azkune Mikel , Aldabaldetreku Gotzon , Bikandi Iñaki , Ruiz‐Rubio Leire , Zubia Joseba
Published: March 2018

This paper reports the overall fabrication process of microstructured polymer optical fibres (mPOFs). mPOF fabrication involves a two‐step process: on the one hand, the design and creation of a preform containing a large‐scale version of the desired fibre and, on the other, the precise heating and drawing of the preform to the final fibre. The preforms are produced either by an improved drilling technique or by capillary stacking. For a correct and accurate drawing of the fibre, a controlled and precise heating unit has to be designed, an issue that will be explained in detail in this work. The quality and optical performance of the final mPOF depends strongly on key factors such as the preform annealing, the accuracy of the technique selected for the creation of the preform structure, the heating stage, as well as on the drawing parameters. All of them are analysed in detail and some drawn mPOFs of interest are reported as well. © 2018 Society of Chemical Industry
Fabrication and analysis of side‐emitting poly(methyl methacrylate) fibres with non‐circular cross‐sections
Authors: Bunge Christian‐Alexander , Mohr Benjamin , Vad Thomas , Beckers Markus , Gries Thomas
Published: March 2018

We present a novel type of side‐light‐emitting fibre with trilobal cross‐section. The fibre is especially designed for indirect illumination applications and the special shape of the filament cross‐section permits the formation of a distinct asymmetric radiation pattern. These fibres can focus the radially emitted light on particular locations, e.g. in order to cure resins or polymers at well‐defined positions, or may be used as indirect illumination sources in car interiors. The polymer material is commercial optical‐grade poly(methyl methacrylate) (PMMA) that is compounded with different concentrations of a TiO2‐nanofiller‐modified PMMA. © 2018 Society of Chemical Industry
Structural and thermochemical properties of methyl ethyl sulfide alcohols: HOCH2SCH2CH3, CH3SCH(OH)CH3, CH3SCH2CH2OH, and radicals corresponding to loss of H atom
Authors: Song Guanghui , Bozzelli Joseph W.
Published: March 2018

Sulfide alkoxy radicals are important intermediates during the partial oxidation of alkyl sulfides in atmospheric chemistry and in combustion. The atmospheric reaction sequence to formation of the alkoxy radicals includes (1) initial reaction with OH to create a radical on a carbon site, (2) the carbon radical then associates with 3O2 to form a peroxy radical, and (3) an NO radical reacts with the peroxy radical to form an alkoxy radical (RO•) plus NO2. This study determines structural parameters, internal rotor potentials, bond dissociation energies, and thermochemical properties (ΔfH°, S°, and Cp(T)) of 3 corresponding alcohols HOCH2SCH2CH3, CH3SCH(OH)CH3, and CH3SCH2CH2OH of methyl ethyl sulfides studied in order to characterize the thermochemistry of the respective alkoxy radicals. The lowest energy molecular structures were calculated using the B3LYP density functional level of theory with the 6‐311G(2d,d,p) basis set. Standard enthalpies of formation (ΔfH°298) for the radicals and their parent molecules were calculated using B3LYP/6‐31 + G(2d,p), CBS‐QB3, M062x/6‐311 + g(2d,p), and G3MP2B3 methods. Isodesmic reactions were used to determine ∆fH° values. Internal rotation potential energy diagrams and rotation barriers were investigated using the B3LYP/6‐31 + G(d,p) level theory. The contributions for S°298 and Cp(T) were calculated using the rigid rotor harmonic oscillator approximation based on the structures and vibrational frequencies obtained by CBS‐QB3 calculations, with contributions from torsion frequencies replaced by internal rotor contributions. Group additivity and hydrogen bond increment values were developed for estimating properties of structurally similar and larger sulfur‐containing peroxide molecules and their radicals.
A highly selective fluorescent chemosensor for Cu2+ based on a diarylethene with a 2,1,3‐benzoxadiazole unit
Authors: Zhang Zhihui , Liu Hongliang , Pu Shouzhi
Published: March 2018

A novel photochromic diarylethene containing a 2,1,3‐benzoxadiazole structure has been synthesized and its multicontrollable fluorescence properties have been systematically studied by the stimulation of light and metal ions. The compound exhibited favorable photochromism and fluorescent switching properties. Furthermore, it can serve as a fluorescent chemosensor for highly selective recognition of Cu2+ in aqueous acetonitrile. When triggered by Cu2+, it displayed a remarkable blue shift from 594 to 524 nm (70 nm) with a significant fluorescence color change from yellow to bright green. As a result, a logic circuit has also been constructed on the basis of light and chemical stimulation.
Dichloromethane as solvent and reagent: a case study of photoinduced reactions in mixed phosphonium‐iodonium ylide
Authors: Levina Irina I. , Klimovich Olga N. , Vinogradov Dmitrii S. , Podrugina Tatyana A. , Bormotov Denis S. , Kononikhin Alexey S. , Dement'eva Olga V. , Senchikhin Ivan N. , Nikolaev Evgeny N. , Kuzmin Vladimir A. , Nekipelova Tatiana D.
Published: March 2018

Several years ago the photoinduced reaction of mixed phosphonium‐iodonium ylides (1) with acetylenes (2) to give λ5‐phosphinolines (3) and substituted furans (4) was described. This reaction is one‐pot, metal‐free synthesis of heterocycles 3 and 4 with the yields of 40% to 80%. The reaction proceeds only in dichloromethane (DCM) at the high ylide concentrations (>0.01 mol/L). The product analysis by 31P NMR, electrospray ionization mass spectrometry, UV‐vis spectrophotometry, and the dynamic light scattering study of the self‐aggregation of the ylide in DCM showed a dual role of the solvent in the photoinduced reactions of mixed phosphonium‐iodonium ylide: (i) at the low ylide concentrations (<0.01 mol/L), the conjugated photoinitiation of the chain reaction in DCM results in the formation of chlorine‐containing products and (ii) at the high ylide concentrations (>0.01 mol/L), the photolysis mechanism is determined by self‐organization of the ylide molecules to give large stable aggregates in DCM, in which the target heterocycles are synthesized. Two important issues follow from the study. First, the annulation reaction between mixed phosphonium‐iodonium ylide and acetylenes occurs only when the reactive intermediates are in close proximity to one other, and, second, DCM is not inert reagent in reactions occurring with participation of radicals and in one form or another can participate in photoinduced radical reactions of various solutes.
An emerging post‐polymerization modification technique: The promise of thiol‐para‐fluoro click reaction
Authors: Agar Soykan , Baysak Elif , Hizal Gurkan , Tunca Umit , Durmaz Hakan
Published: March 2018

Post‐polymerization modification (PPM) of polymers is extremely beneficial in terms of designing brand new synthetic pathways toward functional complex polymers. Fortunately, the new developments in the field of organic chemistry along with controlled/living radical polymerization (CLRP) techniques have enabled scientists to readily design and synthesize the functionalized‐polymers for wide range of applications via the PPM. In this regard, the reactivity of para‐fluorine atom in the fluorinated aromatic structures toward the nucleophilic substitution reactions has made the polymers possessing this group to become a very strong candidate that can undergo efficient PPM. Besides, it has been proven that the thiol‐functionalized compounds react with the para‐fluorine atom of the pentafluorophenyl group more rapidly and efficiently than the amine‐ and the hydroxyl‐functionalized compounds. Furthermore, the milder experimental conditions to achieve quantitative conversions have led to the reaction between the thiol and the structures possessing pentafluorophenyl groups to be referred to as a click‐type reaction. Given this information, this review article aims to present the scientific developments regarding the thiol‐para‐fluoro “click” (TPF‐click) chemistry, and its impact on PPM to construct novel polymeric structures. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1181–1198
A computational structure–property relationship study of glass transition temperatures for a diverse set of polymers
Authors: Chen Min , Jabeen Farukh , Rasulev Bakhtiyor , Ossowski Martin , Boudjouk Philip
Published: March 2018

The glass transition temperature (Tg) is one of the most important properties affecting the stability of a polymeric material. A cheminformatics‐based approach has been employed to investigate the glass transition temperatures for a set of polymers. Specifically, a set of 80 polymers was used to build a quantitative structure–property relationship (QSAR). By applying a combination of cheminformatics methods, several predictive models were developed consisting of 1–10 physicochemical variables. The best predictive model, which is based on seven descriptors, successfully predicts the glass transition temperatures for the investigated polymers. Furthermore, the best developed model identified several significant descriptors responsible for glass transition temperatures of the investigated polymers with a correlation coefficient of r2 = 0.77. The computational model derived from this study may serve as a powerful tool to predict glass transition temperatures for various polymers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 877–885
Deep insights into the hydrolysis of N,N‐dialkylaminoethyl methacrylates in aqueous solution with 1H NMR spectroscopy
Authors: Zheng Pengfei , Su Xin , Fei Chenhong , Shi Xiaohuo , Yin Hongyao , Feng Yujun
Published: March 2018

N,N‐dialkylaminoethyl methacrylate (DAEA) monomers are extensively used to prepare multi‐responsive polymers. However, these monomers face high risk of hydrolysis in their ester groups when being polymerized in water‐containing medias. Here, NMR spectroscopy was employed to continuously track the hydrolysis and solubility of four widely used DAEA monomers [CH2CH2R1COO(CH2)2N(R2)2; R1 = H or CH3; R2 = CH3, CH2CH3 or CH(CH3)2] under typical polymerization conditions. With this technique, the hydrolysis reactivity and absolute hydrolysis amount of these monomers are separately examined, and then their kinetic correlations with solubility, molecular structure, pH, and temperature are established, so that the hydrolysis of DAEA monomers and even other esters with similar cyclic structure can be predicted. The present efforts are expected to provide a general understanding for the hydrolysis of all the DAEA monomers, benefitting to the optimization of polymerization toward well‐defined DAEA copolymers, as well as the design of smart soft matter for specific applications. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 914–923
Explosive Properties of a High Explosive Composition Based on Cis‐1,3,4,6‐tetranitrooctahydroimidazo‐[4,5‐d]imidazole and 1,1‐Diamino‐2,2‐dinitroethene (BCHMX/FOX‐7)
Authors: Hussein Ahmed K. , Elbeih Ahmed , Jungova Marcela , Zeman Svatopluk
Published: March 2018

In this work, preparation and characterization of a plastic bonded explosive (PBX) based on a mixture of cis‐1,3,4,6‐tetranitrooctahydroimidazo‐[4,5‐d]imidazole (BCHMX) and 1,1‐diamino‐2,2‐dinitroethene (DADNE or FOX‐7) bonded by poly‐dimethyl siloxane binder (PDMS) were investigated. Impact and friction sensitivities were determined. Detonation velocity was measured and the detonation characteristics were determined by the EXPLO 5 thermodynamic code. Relative explosive strength was determined using the ballistic mortar test. For comparison, four individual cyclic nitramines, RDX (1,3,5‐trinitro‐1,3,5‐triazinane), β‐HMX (β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane), BCHMX and ϵ‐CL20 (ϵ‐2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane, ϵ‐HNIW) in addition to their PBXs bonded by the same polymeric matrix were studied. Also traditional plastic explosives such as Czech plastic explosive (SEMTEX 10) and Egyptian Plastic Explosive (EPX‐1) were included in the study. The results confirmed that BCHMX/FOX7‐Sil has the lowest impact and friction sensitivity of all the studied samples and its detonation velocity and pressure are higher than the traditional PETN plastic explosives.
Experimental Determination of Acceleration of Explosively Driven Metal by Photonic Doppler Velocimetry in the Process of Explosive Welding
Authors: Kucera Jindrich , Anastacio Aline Cardoso , Nesvadba Petr , Kunzel Martin , Selesovsky Jakub , Pachman Jiri
Published: March 2018

Two important parameters reflect in the quality of the interface of two explosively welded metal plates – impact velocity and collision angle. Both parameters can be determined from the knowledge of velocity history of the accelerated surface. A suitable measurement methodology that would allow in‐situ determination of the course of acceleration at a technological scale experiments is however not yet available. One of the emerging options enabling such measurements is Photonic Doppler Velocimetry (PDV). This paper focuses on the issues observed during measurement of metal plate acceleration in explosive welding using this technique. A well‐known combination in which copper plate is accelerated by detonation and welded to a steel baseplate was chosen for small scale experiments. The methodology was further employed at a large scale technological tests were two different steel plates were joined by detonation. The PDV proved to be successful in determination of the entire velocity history and provides unprecedented insight into the welding process. The knowledge of the velocity time history enables optimization of the impact velocity and collision angle without having to modify the explosive composition. A methodology of velocity measurement of the entire velocity profile of accelerated plate and its collision velocity during metal welding was developed. In addition, we are proposing a new way of optimizing welding parameters based on the exact velocity and thus a collision angle calculation.
Structural basis for the flexible recognition of α‐glucan substrates by Bacteroides thetaiotaomicron SusG
Authors: Arnal Gregory , Cockburn Darrell W. , Brumer Harry , Koropatkin Nicole M.
Published: March 2018

Bacteria that reside in the mammalian intestinal tract efficiently hydrolyze dietary carbohydrates, including starch, that escape digestion in the small intestine. Starch is an abundant dietary carbohydrate comprised of α1,4 and α1,6 linked glucose, yet mammalian intestinal glucoamylases cannot effectively hydrolyze starch that has frequent α1,6 branching as these structures hinder recognition and processing by α1,4‐specific amylases. Here we present the structure of the cell surface amylase SusG from Bacteroides thetaiotaomicron complexed with a mixed linkage amylosaccharide generated from transglycosylation during crystallization. Although SusG is specific for α1,4 glucosidic bonds, binding of this new oligosaccharide at the active site demonstrates that SusG can accommodate α1,6 branch points at subsite −3 to −2, and also at subsite+1 adjacent to the site of hydrolysis, explaining how this enzyme may be able to process a wide range of limit dextrins in the intestinal environment. These data suggest that B. thetaiotaomicron and related organisms may have a selective advantage for amylosaccharide scavenging in the gut.
Exploring the role of post‐translational modifications in regulating α‐synuclein interactions by studying the effects of phosphorylation on nanobody binding
Authors: El Turk Farah , De Genst Erwin , Guilliams Tim , Fauvet Bruno , Hejjaoui Mirva , Di Trani Justin , Chiki Anass , Mittermaier Anthony , Vendruscolo Michele , Lashuel Hilal A. , Dobson Christopher M.
Published: March 2018

Intracellular deposits of α‐synuclein in the form of Lewy bodies are major hallmarks of Parkinson's disease (PD) and a range of related neurodegenerative disorders. Post‐translational modifications (PTMs) of α‐synuclein are increasingly thought to be major modulators of its structure, function, degradation and toxicity. Among these PTMs, phosphorylation near the C‐terminus at S129 has emerged as a dominant pathogenic modification as it is consistently observed to occur within the brain and cerebrospinal fluid (CSF) of post‐mortem PD patients, and its level appears to correlate with disease progression. Phosphorylation at the neighboring tyrosine residue Y125 has also been shown to protect against α‐synuclein toxicity in a Drosophila model of PD. In the present study we address the potential roles of C‐terminal phosphorylation in modulating the interaction of α‐synuclein with other protein partners, using a single domain antibody fragment (NbSyn87) that binds to the C‐terminal region of α‐synuclein with nanomolar affinity. The results reveal that phosphorylation at S129 has negligible effect on the binding affinity of NbSyn87 to α‐synuclein while phosphorylation at Y125, only four residues away, decreases the binding affinity by a factor of 400. These findings show that, despite the fact that α‐synuclein is intrinsically disordered in solution, selective phosphorylation can modulate significantly its interactions with other molecules and suggest how this particular form of modification could play a key role in regulating the normal and aberrant function of α‐synuclein.
Structural basis for tankyrase‐RNF146 interaction reveals noncanonical tankyrase‐binding motifs
Authors: DaRosa Paul A. , Klevit Rachel E. , Xu Wenqing
Published: March 2018

Poly(ADP‐ribosyl)ation (PARylation) catalyzed by the tankyrase enzymes (Tankyrase‐1 and ‐2; a.k.a. PARP‐5a and ‐5b) is involved in mitosis, telomere length regulation, GLUT‐4 vesicle transport, and cell growth and differentiation. Together with the E3 ubiquitin ligase RNF146 (a.k.a. Iduna), tankyrases regulate the cellular levels of several important proteins including Axin, 3BP2, and angiomotins, which are key regulators of Wnt, Src and Hippo signaling, respectively. These tankyrase substrates are first PARylated and then ubiquitylated by RNF146, which is allosterically activated by binding to PAR polymer. Each tankyrase substrate is recognized by a tankyrase‐binding motif (TBM). Here we show that RNF146 binds directly to tankyrases via motifs in its C‐terminal region. Four of these RNF146 motifs represent novel, extended TBMs, that have one or two additional amino acids between the most conserved Arg and Gly residues. The individual RNF146 motifs display weak binding, but together mediate a strong multivalent interaction with the substrate‐binding region of TNKS, forming a robust one‐to‐one complex. A crystal structure of the first RNF146 noncanonical TBM in complex with the second ankyrin repeat domain of TNKS shows how an extended motif can be accommodated in a peptide‐binding groove on tankyrases. Overall, our work demonstrates the existence of a new class of extended TBMs that exist in previously uncharacterized tankyrase‐binding proteins including those of IF4A1 and NELFE.
Bicelle size modulates the rate of bacteriorhodopsin folding
Authors: Gruenhagen Timothy C. , Ziarek Joshua J. , Schlebach Jonathan P.
Published: March 2018

The conformational equilibria of integral membrane proteins have proven extremely difficult to characterize within native lipid bilayers. To circumvent technical issues, investigations of the structure and stability of α‐helical membrane proteins are often carried out in mixed micelle or bicelle solvents that mimic the membrane and facilitate measurements of reversible folding. Under these conditions, the energetics of membrane protein folding are typically proportional to the mole fraction of an anionic detergent in the micelle. However, investigations of the folding and unfolding of bacteriorhodopsin (bR) surprisingly revealed that the folding rate is also highly sensitive to the bulk molar concentration of lipids and detergents. We show here that this rate enhancement coincides with changes in bicelle size and suggest this effect arises through restriction of the conformational search space during folding. In conjunction with previous mutagenic studies, these results provide additional evidence that a topological search limits the rate of bR folding. Furthermore, this finding provides insights into the manner by which micellar and bicellar environments influence the conformational stability of polytopic membrane proteins.
The impact of intraductal carcinoma of the prostate on the site and timing of recurrence and cancer‐specific survival
Authors: Trinh Vincent Q. , Sirois Jennifer , Benzerdjeb Nazim , Mansoori Babak K. , Grosset Andrée‐Anne , Albadine Roula , Latour Mathieu , Mes‐Masson Anne‐Marie , Hovington Hélène , Bergeron Alain , Ladouceur Martin , Fradet Yves , Saad Fred , Trudel Dominique
Published: March 2018

Background

To investigate the effect of intraductal carcinoma of the prostate (IDC‐P) in radical prostatectomy (RP) specimens in the context of the site of recurrence, time to recurrence, and cancer‐specific survival in two academic cohorts of locally, regionally, or distantly recurrent prostate cancer.

Methods

Our cohort included men enrolled into two academic tissue repositories from 1993 to 2011, who were treated with first‐line RP who later experienced local recurrence, regional recurrence, or distant metastasis (together termed clinical recurrence, CR). RP material was reviewed to identify IDC‐P and to update grading to current standards. The primary endpoint was the initial location of CR. Secondary endpoints included time to CR and cancer‐specific survival. Pearson's chi‐square, Welch's t‐test, Mann‐Whitney U test and Fisher's exact test were performed for univariate analyses. Multinomial logistic regression was used for multivariate analyses. Cancer‐specific survival was analyzed with the generalized Wilcoxon test and Cox regression.

Results

Eighty‐five patients with CR were included in the analysis. IDC‐P was present in 78.5% of patients from Center 1 and 70.0% from Center 2 (P = 0.547). IDC‐P was independently associated with distant metastasis at initial CR (multivariate odds ratio = 6.27, P = 0.015). IDC‐P status did not affect time to recurrence; median survival without recurrence was at 53 months for IDC‐P(+) and at 50 months for IDC‐P(−) (P = 0.441). Distant metastases at the initial CR event had a 36% reduction of cancer‐specific survival compared to local recurrences (P = 0.007). Additionally, prostatic‐bed radiotherapy (adjuvant or salvage for biochemical recurrence before distant metastasis) was associated with a 25% reduction in cancer‐specific mortality compared to no radiotherapy (P = 0.023). Similar reduction in cancer‐specific mortality was observed in the subgroup of patients with distant metastasis and IDC‐P when treated with radiotherapy (29%, P = 0.050).

Conclusions

In our cohort, presence of IDC‐P was an independent factor for distant metastasis at initial CR, but did not have a significant impact on time to CR. Furthermore, metastatic patients showed statistically reduced cancer‐specific mortality when treated with radiotherapy. This reduction in cancer‐specific mortality was also identified in patients with IDC‐P. Future large scale validation studies should take into account the presence of IDC‐P and confirm its impact on disease progression.
Mating disruption of Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) by playback of vibrational signals in vineyard trellis
Authors: Krugner Rodrigo , Gordon Shira D
Published: March 2018

BACKGROUND

Glassy‐winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) is an important vector of the bacterium Xylella fastidiosa, the causal agent of Pierce's disease of grapevine. Area‐wide insecticide applications have suppressed GWSS populations for ∼ 25 years, but reduced levels of insecticide susceptibility have been reported. Therefore, alternative methods of control are needed. Objectives of this study were to evaluate the efficacy of playback of vibrational mating communication signals for disrupting mating of GWSS in a natural vineyard setting and to evaluate spectral properties of signal transmission through vineyard trellis.

RESULTS

Playback reduced mating of GWSS on grapevines. A total of 28 (of 134) male–female pairs mated in the control treatment (silence) and only one (of 134) pair mated when treated with the vibrational signal playback. Playback of vibrational signals through vineyard trellis was affected by distance from the signal source, with frequency composition being the highest at the source and lowest on vines positioned away from the source. Frequency composition in canes housing test insects decreased exponentially as distance from the source increased, whereas the relative amplitude of analyzed frequencies decreased linearly.

CONCLUSION

Although further studies are needed prior to method implementation, data from this study continue to support integration of vibrational mating disruption with current methods to suppress GWSS populations. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.
Carbon Ordering in Martensite Lattice Under External Stress: Thermodynamic Theory and Molecular Dynamics Simulation
Authors: Chirkov Pavel , Mirzoev Alexander , Mirzaev Dzhalal
Published: March 2018

Rapid cooling of the Fe–C fcc solution leads to the formation of a phase called martensite, which has high mechanical properties. It is well known that under stress a martensite has the ability to plastically deform within a small range, despite the large value of the macroscopic yield strength. This effect is explained in different ways, mainly on the basis of dislocation theory. We study the impact of external stress on ordering of interstitial atoms in Fe–C solid solutions and formation of tetrahedral distortion of martensite lattice. Molecular dynamics with embedded atom (EAM) interatomic potential is used. According to the simulations, interstitial carbon atoms migrate under external stress applied along the tetragonality direction from z‐sublattice, and tetrahedral distortion of lattice changes its orientation to other ones when the stress exceeds some critical value. This result enables us to justify a new look at the nature of the martensite plastic deformation. The influence of temperature and carbon content on the critical stress value is investigated.
Dielectric Tunability, Expanding the Function of Metal‐Organic Frameworks
Authors: Guo Jiang‐Bin , Chen Li‐Hong , Ke Hao , Wang Xuan , Zhao Hai‐Xia , Long La‐Sheng , Zheng Lan‐Sun
Published: March 2018

Above room‐temperature dielectric tunability is observed in the metal‐organic frameworks (MOFs) [NH2(CH3)2]n[FeIIIFeII(HCOO)6]n (1) and [NH2(CH3)2]n[FeIIIFeII(1−x)NiIIx(HCOO)6]n (x = 0.64–0.69) (2). The relative tunability (defined as [ϵ′(0) – ϵ′(E)]/ϵ′(0) × 100% = Δϵ′/ϵ′(0) × 100%) values for 1 are up to 35% (at 410 K) for E⊥c and 21% (at 380 K) for E||c, while these for 2 are 14% for E⊥c and 11.5% for E||c. Investigation on the mechanism of the dielectric tunability in 1 and 2 reveals that the activation energy for the electron hopping between two adjacent metal ions and the magnetic exchange interaction play a key role in the dielectric tunability of these materials.
Evaluation of the two‐moment scheme LIMA based on microphysical observations from the HyMeX campaign
Authors: Taufour Marie , Vié Benoît , Augros Clotilde , Boudevillain Brice , Delanoë Julien , Delautier Gaëlle , Ducrocq Véronique , Lac Christine , Pinty Jean‐Pierre , Schwarzenböck Alfons
Published: March 2018

The goal of this paper is to present and evaluate the new LIMA (Liquid Ice Multiple Aerosols) microphysical scheme, which predicts six water species (water vapour, cloud water, rainwater, primary ice crystals, snow aggregates, and graupel). LIMA uses a two‐moment parametrization for three hydrometeor species (ice crystals, cloud droplets, and raindrops), and is derived from the one‐moment scheme ICE3 used daily in the AROME cloud‐resolving operational model at Météo‐France. In addition, it integrates a prognostic representation of the aerosol population. To evaluate the scheme, we simulate two well‐documented Heavy Precipitation Events from the HyMeX (Hydrological cycle in the Mediterranean Experiment) campaign. The LIMA simulations are compared to ICE3 simulations and to a large variety of observations, such as rainfall accumulation from rain gauges, particle size distributions from disdrometers, airborne in situ measurements of ice particles, and dual‐polarization radar variables. The evaluation suggests that the rain mixing ratio prognosed by LIMA is more realistic than that prognosed by ICE3. Comparisons with disdrometers and dual‐polarization radars highlight the better representation of the rain microphysical variability when using LIMA and also its overprediction of raindrops with large diameters. The vertical composition of the convective cells is also improved by the two‐moment ice parametrization in the LIMA scheme, which impacts the contents of the one‐moment parametrized snow and graupel species. This evaluation of LIMA suggests ways to improve the hydrometeor representation, focusing especially on the description of the particle size distributions for different water species.
Unravelling the relative roles of physical processes in modelling the life cycle of a warm radiation fog
Authors: Steeneveld Gert‐Jan , de Bode Michiel
Published: March 2018

This study evaluates the representation of the life cycle of a radiation fog case‐study observed at the Cabauw 213 m tower (Netherlands) facility by the Weather Research and Forecasting (WRF) single‐column model, and aims to advance the understanding of the model behaviour, which will assist in setting research priorities for the future. First an ensemble of 16 WRF configurations that vary in parametrization schemes for the planetary boundary layer, land surface, long‐wave radiation, and microphysics are evaluated. Next, we perform a sensitivity study to examine which physical process is most crucial in modelling the fog, i.e. soil heat diffusivity, the CO2 concentration (representing clear‐sky long‐wave radiation), the vapour diffusion to droplets, and the turbulent mixing. Subsequently, we study whether these perturbations can improve the model representation, and on the other hand whether they can explain the model behaviour of the 16 ensemble members. Results are displayed in process diagrams. We find that the behaviour of the ensemble can be explained by variations in the soil heat diffusivity and the turbulent mixing. However, their sensitivities orient in approximately the same direction, and as such, errors in the formulation of the boundary‐layer scheme can be hidden by compensating errors in the land‐surface scheme. In addition, we find that simultaneous perturbations in the soil heat diffusivity and turbulent mixing do not result in the same results as superposing the individual perturbations.
A literature review on selective maintenance for multi‐unit systems
Authors: Cao Wenbin , Jia Xisheng , Hu Qiwei , Zhao Jianmin , Wu Yutao
Published: March 2018

Selective maintenance is regarded as a type of profit‐generating maintenance policy, playing an important role in balancing limited maintenance resources with system performance. Since 1988, increasing interest has been focused on this research area. Nevertheless, to the best of our knowledge, there is a lack of critical reviews of selective maintenance. This paper is the first systematic review focusing on this relevant topic. In this work, a definition and some specific features of selective maintenance are elaborated. Based on these features, a set of criteria that have been considered in selective maintenance optimization are summarized into 3 categories: system characteristics, maintenance characteristics, and mission profile characteristics. Based on these criteria, a comprehensive literature review on selective maintenance is undertaken. The solution approaches, as well as a general procedure for selective maintenance optimization, are discussed. Finally, some possible directions for further research are provided.
Estimating N2O processes during grassland renewal and grassland conversion to maize cropping using N2O isotopocules
Authors: Buchen Caroline , Lewicka‐Szczebak Dominika , Flessa Heinz , Well Reinhard
Published: March 2018

Rationale

Enhanced nitrous oxide (N2O) emissions can occur following grassland break‐up for renewal or conversion to maize cropping, but knowledge about N2O production pathways and N2O reduction to N2is very limited. A promising tool to address this is the combination of mass spectrometric analysis of N2O isotopocules and an enhanced approach for data interpretation.

Methods

The isotopocule mapping approach was applied to field data using a δ15NspN2Oand δ18ON2Omap to simultaneously determine N2O production pathways contribution and N2O reduction for the first time. Based on the isotopic composition of N2O produced and literature values for specific N2O pathways, it was possible to distinguish: (i) heterotrophic bacterial denitrification and/or nitrifier denitrification and (ii) nitrification and/or fungal denitrification and the contribution of N2O reduction.

Results

The isotopic composition of soil‐emitted N2O largely resembled the known end‐member values for bacterial denitrification. The isotopocule mapping approach indicated different effects of N2O reduction on the isotopic composition of soil‐emitted N2O for the two soils under study. Differing N2O production pathways in different seasons were not observed, but management events and soil conditions had a significant impact on pathway contribution and N2O reduction. N2O reduction data were compared with a parallel15N‐labelling experiment.

Conclusions

The field application of the isotopocule mapping approach opens up new prospects for studying N2O production and consumption of N2O in soil simultaneously based on mass spectrometric analysis of natural abundance N2O. However, further studies are needed in order to properly validate the isotopocule mapping approach.
A comprehensive protocol for chemical analysis of flame combustion emissions by secondary ion mass spectrometry
Authors: Irimiea Cornelia , Faccinetto Alessandro , Carpentier Yvain , Ortega Ismael‐Kenneth , Nuns Nicolas , Therssen Eric , Desgroux Pascale , Focsa Cristian
Published: March 2018

Rationale

Time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) is used to provide detailed information on the surface chemical composition of soot. An analytical protocol is proposed and tested on a laboratory flame, and the results are compared with our previous measurements provided by two‐step laser mass spectrometry (L2MS).

Methods

This work details: (1) the development of a dedicated apparatus to sample combustion products from atmospheric flames and deposit them on substrates suitable for TOF‐SIMS analysis; (2) the choice of the deposition substrate and the material of the sampling line, and their effect on the mass spectra; (3) a method to separate the contributions of soot and condensable gas based on impact deposition; and finally (4) post‐acquisition data processing.

Results

Compounds produced during flame combustion are detected on the surface of different deposition substrates and attributed a molecular formula based on mass defect analysis. Silicon and titanium wafers perform similarly, while the surface roughness of glass microfiber filters results in a reduced mass resolution. The mass spectra obtained from the analysis of different locations of the deposits obtained by impaction show characteristic patterns that are attributed to soot/condensable gas.

Conclusions

A working method for the analysis of soot samples and the extraction of useful data from mass spectra is proposed. This protocol should help to avoid common experimental issues like sample contamination, while optimizing the setup performance by maximizing the achievable mass resolution.