bluuebunny/crossref_metadata_2025 huggingface dataset:
Homogeneous Copper‐Catalyzed Conversion of Methane to Methyl Trifluoroacetate in High Yield at Low Pressure
Authors: Ravi Manoj , van Bokhoven Jeroen A.
Published: March 2018

The direct catalytic oxidation of methane to oxygenates, a reaction that garners significant scientific and industrial interest, is plagued by poor methane‐based yields. Some of the best homogeneous catalytic systems reported to date convert methane to methyl esters using catalysts with complex organic ligands to reach high yields at relatively high temperature (>423 K) and pressure (20–70 bar). In our study, we used a simple copper compound, copper(II) oxide, to selectively convert methane to methyl trifluoroacetate at 363 K and low pressure (5 bar) resulting in yields as high as 63 % at a methane conversion of 71 %. The catalyst is easily recovered by treating the spent reaction mixture with a base, and the catalytic performance of the recovered material is highly comparable to that of the fresh catalyst. In terms of turnover, copper oxide (TON=33 for ester yield of 56 %) ranks higher than other simple metal compounds and is comparable to catalysts with NHC ligands. Thus, this work demonstrates the possibility of using a simple catalyst devoid of complex ligands to convert methane in high yields at low pressure.
A Magnetic Chameleon: Biocompatible Lanthanide Fluoride Nanoparticles with Magnetic Field Dependent Tunable Contrast Properties as a Versatile Contrast Agent for Low to Ultrahigh Field MRI and Optical Imaging in Biological Window
Authors: Biju Silvanose , Gallo Juan , Bañobre‐López M. , Manshian Bella B. , Soenen Stefaan J. , Himmelreich Uwe , Vander Elst Luce , Parac‐Vogt Tatjana N.
Published: March 2018

A novel type of multimodal, magnetic resonance imaging/optical imaging (MRI/OI) contrast agent was developed, based on core–shell lanthanide fluoride nanoparticles composed of a β‐NaHoF4 core plus a β‐NaGdF4:Yb3+, Tm3+ shell with an average size of ∼24 nm. The biocompatibility of the particles was ensured by a surface modification with poly acrylic acid (PAA) and further functionalization with an affinity ligand, folic acid (FA). When excited using 980 nm near infrared (NIR) radiation, the contrast agent (CA) shows intense emission at 802 nm with lifetime of 791±3 μs, due to the transition 3H4→3H6 of Tm3+. Proton nuclear magnetic relaxation dispersion (1H‐NMRD) studies and magnetic resonance (MR) phantom imaging showed that the newly synthesized nanoparticles, decorated with poly(acrylic acid) and folic acid on the surface (NP‐PAA‐FA), can act mainly as a T1‐weighted contrast agent below 1.5 T, a T1/T2 dual‐weighted contrast agent at 3 T, and as highly efficient T2‐weighted contrast agent at ultrahigh fields. In addition, NP‐PAA‐FA showed very low cytotoxicity and no detectable cellular damage up to a dose of 500 μg mL−1.
How Mycobacterium tuberculosis Galactofuranosyl Transferase 2 (GlfT2) Generates Alternating β‐(1–6) and β‐(1–5) Linkages: A QM/MM Molecular Dynamics Study of the Chemical Steps
Authors: Janoš Pavel , Kozmon Stanislav , Tvaroška Igor , Koča Jaroslav
Published: March 2018

Mycobacterium tuberculosis features a unique cell wall that protects the bacterium from the external environment. Disruption of the cell wall assembly is a promising direction for novel anti‐tuberculotic drugs. A key component of the cell wall is galactan, a polysaccharide chain composed of galactofuranose (Galf) units connected by alternating β‐(1–5) and β‐(1–6) linkages. The majority of the galactan chain is biosynthesized by a bifunctional enzyme—galactofuranosyl transferase 2 (GlfT2). GlfT2 catalyzes two reactions: the formation of β‐(1–5) and β‐(1–6) linkages. It was suggested that the enzyme acts through a processive mechanism until it adds 30–35 Galf units in a single active site. We applied a QM/MM string method coupled with ab initio molecular dynamics simulations to study the two reactions catalyzed by GlfT2. We showed that both reactions proceed very similarly and feature similar transition‐state structures. We also present novel information about the ring puckering behavior of the five‐membered furanose ring during the glycosyltransferase reaction and a calculated transition‐state structure with galactose in a furanose form that may be used as a guide for the rational design of very specific and extremely potent inhibitors, that is, transition‐state analogues, for GlfT2. Due to the absence of a furanose form of galactose in humans, transition‐state‐analogous inhibitors represent an attractive scaffold for the development of novel antibacterial drugs.
Asymmetric Synthesis of Diarylmethyl Sulfones by Palladium‐Catalyzed Enantioselective Benzylic Substitution: A Remarkable Effect of Water
Authors: Najib Atifah , Hirano Koji , Miura Masahiro
Published: March 2018

A Pd/(R)‐BINAP‐catalyzed enantioselective benzylic sulfonation of diarylmethyl carbonates with sodium sulfinates proceeds to deliver the corresponding chiral diarylmethyl sulfones in good yields with high enantioselectivity. The reaction occurs in a dynamic kinetic asymmetric transformation (DYKAT) manner and thus provides convergent access to optically active benzylic sulfones from racemic secondary benzylic carbonates. Additionally, the addition of H2O is found to be critical for high enantioselectivity.
Gold(III) Complexes for Antitumor Applications: An Overview
Authors: Bertrand Benoît , Williams Morwen R. M. , Bochmann Manfred
Published: March 2018

Gold(III) complexes have emerged as a versatile and effective class of metal‐based anticancer agents. The development of various types of ligands capable of stabilizing the AuIII cation and preventing its reduction under physiological conditions, such as chelating nitrogen‐donors, dithiocarbamates and C^N cyclometalled ligands, has opened the way for the exploration of their potential intracellular targets and action mechanisms. At the same time, the bioconjugation of AuIII complexes has emerged as a promising strategy for improving the selectivity of this class of compounds for cancer cells over healthy tissues, and recent developments have shown that combining gold complexes with molecular structures that are specifically recognized by the cell can exploit the cell's own transport mechanisms to improve selective metal uptake.
Mechanical Switching of Aromaticity and Homoaromaticity in Molecular Optical Force Sensors for Polymers
Authors: Stauch Tim
Published: March 2018

The sensing of mechanical stress in polymers is indispensable for investigating the origin and propagation of cracks that lead to material failure and for designing mechanically responsive polymers. Here the unique approaches of using the force‐induced switching of aromaticity and homoaromaticity in molecular optical force sensors for the real‐time measurement of mechanical forces acting in stretched polymers are suggested. The mechanical switching of aromaticity in Dewar benzene is an irreversible event, whereas the degree of π‐orbital overlap in homoaromatic compounds like homotropylium can be adjusted progressively over a wide range of forces. Using computational methods, it is demonstrated that both approaches lead to significant changes in the visible part of the UV/Vis spectra of the force sensors upon application of weak forces (pN–nN). Polymers that incorporate such molecular force sensors therefore change their color well before material failure occurs.
Hierarchical Self‐Assembly Induced by Dilution‐Enhanced Hydrophobic Hydration
Authors: Liu Dapeng , Wang Xiaosong
Published: March 2018

Hydrophobic hydration (HH) is crucial in protein chemistry. Its role in the organization of molecules in water, however, remains elusive and difficult to investigate without appropriate model systems. Metal carbonyl vesicles (MCsomes), assembled from hydrophobic Fp(CH2)6Azobenzenetrans (Fp head=(PPh3)(Cp)Fe(CO)(CO‐); hydrocarbon tail=(CH2)6Azobenzenetrans; trans:trans configuration) is dispersible in water via HH of the Fp heads. We examined the dependence of this HH on solution conditions by taking advantage of redox activity and fluorescence quenching ability of hydrated Fe elements. A subtle variation in the HH substantially varied the solution behaviour of the MCsomes for hierarchical structural evolutions. This scrutiny resolved a long‐standing challenge to explicate the role of HH in self‐assembly at molecular levels, an imperative step to understand the biological systems.
Preparation of Ammonia from Liquid AdBlue – Modeling Approaches and Future Challenges
Authors: Lauer Thomas
Published: March 2018

Sustainable mobility is a legal and public demand. An important measure to clean the exhaust gas of diesel engines is the conversion of nitric oxides with selective catalytic reduction (SCR). The development of SCR systems can be strongly supported by numerical methods. This review article is to document the status of the CFD‐simulation method with respect to the preparation of the injected urea‐water solution, the turbulent transport of ammonia and the assessment of solid deposits coming from liquid film. Comparisons with measurements for realistic sprays and mixing sections are given.
Hydrothermal dewatering of lignite water slurries: Part 2 surface properties and stability
Authors: Li Qiang , Yang Dingzheng , Liu Qingxia , Zhang Jiansheng
Published: March 2018

In this paper, the mechanism of the stability of lignite lignite water slurry after hydrothermal dewatering/treatment (HTD) was studied by the measurement of the yield stress and the fractal dimension of the slurry. The effects of HTD on the surface properties of low rank coal were characterized by the contact angle, zeta potential, and Fourier transform infrared (FTIR) spectroscopy. After HTD, the hydrophobic attraction between coal particles was found to increase, as shown by the increase of the contact angle, and the electrical double layer repulsion was found to decrease, due to the decrease of zeta potential. These effects lead to an increase on the inter‐particle attractions, which is also proven by the theoretical calculations on the interaction energy using the extended DLVO theory. The stability measurements show that the low rank coal water slurry (CWS) becomes more stable after HTD, which is probably due to the formation of a network structure (soft sediment) by coal aggregating across the whole volume of the slurry to prevent coal particles from settling down. The network structure (soft sediment) in coal water slurry after HTD was verified and quantified by the yield stress and fractal dimension. Our findings indicated that the static stability of coal water slurry may be acquired by the network structure of the aggregated coal particles.
Coal pyrolysis and gasification in a fluidized bed thermogravimetric analyzer
Authors: Samih Said , Chaouki Jamal
Published: March 2018

The kinetics and modelling of coal gasification were studied in the newly developed fluidized bed thermogravimetric analyzer. The total weight loss obtained from the fluidized bed reactor and the total gas product are in general agreement. The presented model for the micro‐fluidized bed reactor encompasses the kinetics of coal pyrolysis as well as the gasification reactions. For coal pyrolysis, the resulting activation energies for the individual gases were 34.7 to 59.8 kcal/mol. These values are 19 to 21 % lower than those found in the literature for similar coals. This decrease of the activation energies of the endothermic pyrolysis reactions is attributed to a gradient of temperature of 185 to 209 °C. The obtained activation energy for the CO shift reaction is 46.6 kcal/mol, increasing by 20 % from the one used in the literature. This increase of the activation energy of such a mildly exothermic reaction represents an equivalent of 170 °C gradient of temperature. The effects of temperature on the yield and the composition of the gas product are studied. Experimental results and equilibrium data are also compared. The model shows reasonably good agreement with the experimental results, except for the water gas shift reaction.
Covalent immobilization of cytochrome P450 BM3 (R966D/W1046S) on glutaraldehyde activated SPIONs
Authors: Bahrami Atieh , Garnier Alain , Larachi Faïçal , Iliuta Maria C.
Published: March 2018

Selective hydroxylation of the C‐H bond of saturated hydrocarbon chains at room temperature is the signature of an invaluable biocatalyst, cytochrome P450 BM3 from Bacillus megaterium. Despite this remarkable ability, because of the enzyme's inherent low stability and dependence on electron supply by expensive NADPH, developing stable and economic BM3 systems is a challenging subject. To improve BM3 stability, facilitate its reuse, and reduce the process cost, this study suggests covalent immobilization of R966D/W1046S P450 BM3 on glutaraldehyde pre‐activated super paramagnetic iron oxide nanoparticles (SPIONs). This double mutant consumes less expensive cofactors like NADH and BNAH and its immobilization on magnetic support facilitates its separation and reuse. Free and immobilized enzyme performances were evaluated by 10‐pNCA hydroxylation and BM3 selectivity (hydroxylation at ω (1–3) positions of a fatty acid) was confirmed in a reaction involving myristic acid. The enzyme activity recovery was up to 60 % with 100 % enzyme binding efficiency. BM3‐SPIONs were easily separated from the reaction medium by applying a magnet, and recycled for 5 times, after which they could still present half of their initial activity. The enzyme storage stability was significantly improved: after one month of storage at 4 °C, the immobilized enzyme showed 80 % residual activity toward NADH while the soluble enzyme was inactive after a week. Binding an enzyme to fabricated SPIONs is a promising technique to increase enzyme stability and prevent downstream contamination in biocatalytic processes. In this context, BM3‐SPIONs can be a practical model system in cost‐effective large‐scale applications of such enzymes.
Decarboxylative Fluorination of Arylcarboxylic Acids Promoted by ortho‐Hydroxy and Amino Groups
Authors: Wang Dinghai , Yuan Zheliang , Liu Qilun , Chen Pinhong , Liu Guosheng
Published: March 2018

A novel decarboxylative fluorination process has been developed for the synthesis of ortho‐hydroxy/amino arylfluorides from salicylic acid analogs, in which the ortho‐hydroxy/amino group plays an important role in the transformation. In addition, various arylfluorides are obtained in good to excellent yields under mild conditions.
Distribution of cytochrome oxidase‐rich patches in human primary visual cortex
Authors: Marcondes Marco , Rosa Marcello G.P. , Fiorani Mario , Lima Bruss , Gattass Ricardo
Published: March 2018

We studied the tangential distribution of cytochrome oxidase (CytOx)‐rich patches (blobs) in the striate cortex (V1) of normally sighted Homo sapiens. We analyzed the spatial density and cross‐sectional area of patches in CytOx‐reacted tangential sections of flat‐mounted preparations of V1 and surrounding areas. CytOx‐rich patches were most clearly defined in the supragranular cortical layers of V1, particularly at middle levels of layer III. Variations in patch spatial density were subtle across different visual eccentricity representations. Within the binocular representation of V1, the average patch spatial density decreased slightly with increasing cortical eccentricity, from around 1.0 patch/mm2 in the foveal representation to 0.6 patch/mm2 at the representation of ∼60° eccentricity, but seemed to increase again at the representation of the monocular crescent. Across the entire sample, the cross‐sectional area of patches (i.e., patch size) varied from approximately 0.2–0.8 mm2, with a mean value of 0.32 mm2. Notably, there was no significant variation in the mean patch size across eccentricity representations. Human patches are on average larger than those reported for nonhuman primate brains, and analysis of species with different brain sizes suggests an approximately linear relationship between V1 area and patch size. The relative constancy of patch metrics across eccentricities is in stark contrast with the exponential variation in V1 cortical magnification, suggesting a nearly invariant modular organization throughout human V1.
Counterion Specificity of Polyelectrolyte Brushes: Role of Specific Ion‐Pairing Interactions
Authors: Kou Ran , Zhang Jian , Chen Zhen , Liu Guangming
Published: March 2018

We demonstrate here that the properties of poly (2‐(methacryloyloxy) ethyl trimethylammonium chloride) brushes can be tuned by counterion species. When the brushes are exposed to external chloride (Cl−) counterions, obvious dehydration and collapse are only observed at high salt concentrations. In the presence of very strongly chaotropic perchlorate (ClO4−), the brushes strongly dehydrate and collapse at a very low salt concentration. For the strongly chaotropic thiocyanate ion (SCN−), the changes in hydration and conformation of the brushes are similar to those observed for ClO4− but at a smaller extent at very low salt concentrations. With the addition of kosmotropic acetate (Ac−), hydration of the brushes increases, accompanied by a swelling of the brushes in the low‐salt‐concentration regime. In contrast, the brushes dehydrate and collapse with increasing concentration of Ac− in the high‐salt‐concentration regime. The counterion specificity of the brushes demonstrated here is determined by specific ion‐pairing interactions through modulating the osmotic pressure within the brushes and the hydrophobicity of the ion pairs.
Delivering cognitive behavioural therapy to advanced cancer patients: A qualitative exploration into therapists' experiences within a UK psychological service
Authors: Hassan Suzan , Bennett Kirsty , Serfaty Marc
Published: March 2018

Background

Cognitive behavioural therapy (CBT) is commonly used to treat cancer patients with psychological disorders such as depression. There has been little qualitative research exploring the experience of therapists delivering CBT to patients with advanced cancer and long‐term health conditions generally. Therapists' views may help identify difficulties in delivering therapy and how these may be overcome. The aim of this study was to inform practice by qualitatively exploring the experiences of therapists delivering CBT to patients with advanced cancer.

Design

Sixteen semi‐structured interviews were conducted with therapists from Increasing Access to Psychological Therapy (IAPT) services in London, UK, who had delivered CBT to patients enrolled on the CanTalk trial. Interviews were recorded, transcribed, and analysed using framework analysis.

Results

Therapists reported positive experiences when working with the target population. Flexibility, adaptability, and a consideration of individual needs were identified as important when delivering CBT, but the rigidity of IAPT policies and demand for services were perceived as problematic. Although therapists reported adequate training, specialist supervision was desired when delivering therapy to this complex population.

Conclusion

IAPT therapists can deliver CBT to advanced cancer patients, given therapists positive experiences evident in the present study. However, it was concluded that additional service and modifications of therapy may be needed before positive outcomes for both therapists and patients can be achieved.
Syntheses and Excited‐State Intramolecular Proton Transfer of 3‐Hydroxythioflavone and Its Sulfone Analogue
Authors: Meng Fan‐Yi , Chen Yi‐An , Chen Chih‐Lin , Chou Pi‐Tai
Published: March 2018

3‐Hydroxythioflavone (3‐HTF) was synthesized upon oxidation with selenium dioxide, in contrast to 3‐hydroxyflavone, a prototype molecule undergoing excited‐state intramolecular proton transfer (ESIPT) reaction. Also achieved were the syntheses of the 3‐HTF sulfone analogue and an interesting sulfonyl selane intermediate. Their structures were fully characterized. 3‐HTF showed an ultrafast ESIPT property, as evidenced by >150 fs−1 reaction rate constant and it solely exhibited a proton‐transfer tautomer emission (590 nm) in cyclohexane at room temperature and in a 77 K solid matrix. The lower electronegativity of the sulfur atom in 3‐HTF leads to a significant redshift of the tautomer emission compared with that of 3‐hydroxyflavone. The sulfone analogue showed a lack of ESIPT, mainly owing to the decrease in carbonyl basicity.
Design and implementation of sub 0.5‐V OTAs in 0.18‐μm CMOS
Authors: Kulej Tomasz , Khateb Fabian
Published: March 2018

A family of bulk‐driven CMOS operational transconductance amplifiers (OTAs) has been designed for extremely low supply voltages (0.3‐0.5 V). Three OTA design schemes with different gain boosting techniques and class AB input/output stages are discussed. A detailed comparison among these schemes has been presented in terms of performance characteristics such as voltage gain, gain‐bandwidth product, slew rate, circuit sensitivity to process/mismatch variations, and silicon area. The design procedures for all the compared structures have been developed. The OTAs have been fabricated in a standard 0.18‐μm n‐well CMOS process from TSMC. Chip test results are in good agreement with theoretical predictions and simulations.
Recurrent reciprocal copy number variants: Roles and rules in neurodevelopmental disorders
Authors: Deshpande Aditi , Weiss Lauren A.
Published: March 2018

Deletions and duplications, called reciprocal CNVs when they occur at the same locus, are implicated in neurodevelopmental phenotypes ranging from morphological to behavioral. In this article, we propose three models of how differences in gene expression in deletion and duplication genotypes may result in deleterious phenotypes. To explore these models, we use examples of the similarities and differences in clinical phenotypes of five reciprocal CNVs known to cause neurodevelopmental disorders: 1q21.1, 7q11.23, 15q13.3, 16p11.2, and 22q11.2. These models and examples may inform some insights into better understanding of gene–phenotype relationships. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 78: 519–530, 2018
Niche similarities among introduced and native mountain ungulates
Authors: Lowrey B. , Garrott R. A. , McWhirter D. E. , White P. J. , DeCesare N. J. , Stewart S. T.
Published: March 2018

The niche concept provides a strong foundation for theoretical and applied research among a broad range of disciplines. When two ecologically similar species are sympatric, theory predicts they will occupy distinct ecological niches to reduce competition. Capitalizing on the increasing availability of spatial data, we built from single species habitat suitability models to a multispecies evaluation of the niche partitioning hypothesis with sympatric mountain ungulates: native bighorn sheep (BHS; Ovis canadensis) and introduced mountain goats (MTG; Oreamnos americanus) in the northeast Greater Yellowstone Area. We characterized seasonal niches using two‐stage resource selection functions with a used‐available design and descriptive summaries of the niche attributes associated with used GPS locations. We evaluated seasonal similarity in niche space according to confidence interval overlap of model coefficients and similarity in geographic space by comparing model predicted values with Schoener's D metric. Our sample contained 37,962 summer locations from 53 individuals (BHS = 31, MTG = 22), and 79,984 winter locations from 57 individuals (BHS = 35, MTG = 22). Slope was the most influential niche component for both species and seasons, and showed the strongest evidence of niche partitioning. Bighorn sheep occurred on steeper slopes than mountain goats in summer and mountain goats occurred on steeper slopes in winter. The pattern of differential selection among species was less prevalent for the remaining covariates, indicating similarity in niche space. Model predictions in geographic space showed broad seasonal similarity (summer D = 0.88, winter D = 0.87), as did niche characterizations from used GPS locations. The striking similarities in seasonal niches suggest that introduced mountain goats will continue to increase their spatial overlap with native bighorn. Our results suggest that reducing densities of mountain goats in hunted areas where they are sympatric with bighorn sheep and impeding their expansion may reduce the possibility of competition and disease transfer. Additional studies that specifically investigate partitioning at finer scales and along dietary or temporal niche axes will help to inform an adaptive management approach.
Contrasting patterns of Andean diversification among three diverse clades of Neotropical clearwing butterflies
Authors: Chazot Nicolas , De‐Silva Donna Lisa , Willmott Keith R. , Freitas André V. L. , Lamas Gerardo , Mallet James , Giraldo Carlos E. , Uribe Sandra , Elias Marianne
Published: March 2018

The Neotropical region is the most biodiverse on Earth, in a large part due to the highly diverse tropical Andean biota. The Andes are a potentially important driver of diversification within the mountains and for neighboring regions. We compared the role of the Andes in diversification among three subtribes of Ithomiini butterflies endemic to the Neotropics, Dircennina, Oleriina, and Godyridina. The diversification patterns of Godyridina have been studied previously. Here, we generate the first time‐calibrated phylogeny for the largest ithomiine subtribe, Dircennina, and we reanalyze a published phylogeny of Oleriina to test different biogeographic scenarios involving the Andes within an identical framework. We found common diversification patterns across the three subtribes, as well as major differences. In Dircennina and Oleriina, our results reveal a congruent pattern of diversification related to the Andes with an Andean origin, which contrasts with the Amazonian origin and multiple Andean colonizations of Godyridina. In each of the three subtribes, a clade diversified in the Northern Andes at a faster rate. Diversification within Amazonia occurred in Oleriina and Godyridina, while virtually no speciation occurred in Dircennina in this region. Dircennina was therefore characterized by higher diversification rates within the Andes compared to non‐Andean regions, while in Oleriina and Godyridina, we found no difference between these regions. Our results and discussion highlight the importance of comparative approaches in biogeographic studies.
Habitat quality is more important than matrix quality for bird communities in protected areas
Authors: Häkkilä Matti , Abrego Nerea , Ovaskainen Otso , Mönkkönen Mikko
Published: March 2018

Protected areas are meant to preserve native local communities within their boundaries, but they are not independent from their surroundings. Impoverished habitat quality in the matrix might influence the species composition within the protected areas through biotic homogenization. The aim of this study was to determine the impacts of matrix quality on species richness and trait composition of bird communities from the Finnish reserve area network and whether the communities are being subject of biotic homogenization due to the lowered quality of the landscape matrix. We used joint species distribution modeling to study how characteristics of the Finnish forest reserves and the quality of their surrounding matrix alter species and trait compositions of forest birds. The proportion of old forest within the reserves was the main factor in explaining the bird community composition, and the bird communities within the reserves did not strongly depend on the quality of the matrix. Yet, in line with the homogenization theory, the beta‐diversity within reserves embedded in low‐quality matrix was lower than that in high‐quality matrix, and the average abundance of regionally abundant species was higher. Influence of habitat quality on bird community composition was largely explained by the species' functional traits. Most importantly, the community specialization index was low, and average body size was high in areas with low proportion of old forest. We conclude that for conserving local bird communities in northern Finnish protected forests, it is currently more important to improve or maintain habitat quality within the reserves than in the surrounding matrix. Nevertheless, we found signals of bird community homogenization, and thus, activities that decrease the quality of the matrix are a threat for bird communities.
Polyphosphazenes – Synthetically Versatile Block Copolymers (“Multi‐Tool”) for Self‐Assembly
Authors: Carriedo Gabino A. , de la Campa Raquel , Soto Alejandro Presa
Published: March 2018

This microreview outlines recent advances on the synthesis and self‐assembly of polyphosphazene diblock copolymers, a class of versatile polymers (Multi‐Tool) able to generate a great variety of different well‐defined nanomorphologies. Particular focus is placed on the synthesis of linear block copolymers composed of two polyphosphazene chains (PP‐b‐PP′), or hybrid polymers combining one PP chain with a non‐phosphazene segment [i.e. organic blocks such as poly(olefin)s, polyethers, polyesters, etc.]. We also survey the self‐assembly of these macromolecules equipped with crystalline, rigid or chiral PP core‐forming blocks, to show the morphological diversity and structural complexity of the nanostructures generated in thin films or in solution (selective solvent).
Copper(I)‐Arene Complexes with a Sterically Hindered Tris(pyrazolyl)borate Ligand
Authors: Álvarez María , Urbano Juan , Fructos Manuel R. , Álvarez Eleuterio , Pérez Pedro J.
Published: March 2018

A series of arene copper(I) complexes bearing the hydrotris(3‐mesitylpyrazolyl)borate ligand (TpMs) of general formula TpMsCu(arene) (arene = toluene, 1; nitrobenzene, 2; chlorobenzene, 3; and iodobenzene, 4) has been structurally characterized. Complexes 1–3 show a η2‐arene coordination mode to the copper center, whereas the iodobenzene ligand in 4 is coordinated to Cu by the iodine atom. In the absence of excess arene, these compounds undergo arene loss and formation of the dinuclear complex [TpMsCu]2 (5), which has also been structurally characterized. Given the number of catalytic systems described in which the TpxCu core plays the main role, the observation of these adducts assesses their presence in those catalytic systems, a feature not described to date.
Reactivity of a N→Sn Coordinated Distannyne: Reduction and Hydrogen Abstraction
Authors: Bouška Marek , Tydlitát Jiří , Jirásko Robert , Růžička Aleš , Dostál Libor , Herres‐Pawlis Sonja , Hoffmann Alexander , Jambor Roman
Published: March 2018

The reduction ability of a N→Sn coordinated distannyne {LSn}2, where L is [C6H3‐2,6‐(Me2NCH2)2]– is tested towards organic molecules ethylene and cyclooctatetraene. These reactions provide the compound [{LSn}3SnH] (2), as the result of a hydride abstraction. DFT calculations suggest that compound 2 can be interpreted as highly covalently bonded {HSnI} and {(SnIL)3} fragments. While the reduction of the C=C bond is not observed in the reaction of 1 with organic molecules, the reducing ability of 1 is observed in the reaction with inorganic SnO. Complex 1 is able to reduce SnO and the organotin(II) oxide {LSn}2O (3) is obtained. Moreover, compound 3 is able to coordinate an excess of SnO to yield the organotin(II)–tin(II)–oxo cluster L4Sn10O8 (4).
Selective Oxidation of Sulfides in Flow Chemistry
Authors: Silva Filipa , Baker Alastair , Stansall James , Michalska Weronika , Yusubov Mehkman S. , Graz Michael , Saunders Robert , Evans Gareth J. S. , Wirth Thomas
Published: March 2018

A packed‐bed reactor with oxone has been employed for selective oxidations of sulfur compounds. Various sulfides containing different functional groups are efficiently oxidized to the corresponding sulfoxides without formation of sulfones or other side products.
New approaches in bioprocess‐control: Consortium guidance by synthetic cell‐cell communication based on fungal pheromones
Authors: Hennig Stefan , Wenzel Mandy , Haas Christiane , Hoffmann Andreas , Weber Jost , Rödel Gerhard , Ostermann Kai
Published: March 2018

Bioconversions in industrial processes are currently dominated by single‐strain approaches. With the growing complexity of tasks to be carried out, microbial consortia become increasingly advantageous and eventually may outperform single‐strain fermentations. Consortium approaches benefit from the combined metabolic capabilities of highly specialized strains and species, and the inherent division of labor reduces the metabolic burden for each strain while increasing product yields and reaction specificities. However, consortium‐based designs still suffer from a lack of available tools to control the behavior and performance of the individual subpopulations and of the entire consortium. Here, we propose to implement novel control elements for microbial consortia based on artificial cell–cell communication via fungal mating pheromones. Coupling to the desired output is mediated by pheromone‐responsive gene expression, thereby creating pheromone‐dependent communication channels between different subpopulations of the consortia. We highlight the benefits of artificial communication to specifically target individual subpopulations of microbial consortia and to control e.g. their metabolic profile or proliferation rate in a predefined and customized manner. Due to the steadily increasing knowledge of sexual cycles of industrially relevant fungi, a growing number of strains and species can be integrated into pheromone‐controlled sensor‐actor systems, exploiting their unique metabolic properties for microbial consortia approaches.
Testing geomorphic signal of active normal faulting: The case of the Cittanova Fault (Calabria, southern Italy)
Authors: Peronace Edoardo , Della Seta Marta , Troiani Francesco , Galli Paolo , Giaccio Biagio , Messina Paolo , Fredi Paola
Published: March 2018

Extracting tectonic signals from the landscape is an important challenge for constraining the style and rate of deformation associated with active faults, especially where their displacement history cannot be independently determined. Based on previous paleoseismological data coupled with new geomorphological field work and 14C dating of geomorphic markers, we analysed the geomorphic signal of the along‐strike differential throw of the Cittanova Fault in southern Calabria (Italy), the recent activity of which is already well documented and constrained. Through DTM‐derived stream power law parameters (SL and χ), we provide evidence of drainage network disequilibrium and reorganization in response to fault growth and deformation style. Furthermore, a methodological test of the reliability of the χ metric as a proxy for the differential throw along the strike of active normal faults provided good preliminary results, consistent with a strong inverse linear correlation with fault throw. Copyright © 2018 John Wiley & Sons, Ltd.
Assessing the release of copper from nanocopper-treated and conventional copper-treated lumber into marine waters I: Concentrations and rates
Authors: Parks Ashley N. , Cantwell Mark G. , Katz David R. , Cashman Michaela A. , Luxton Todd P. , Ho Kay T. , Burgess Robert M.
Published: March 2018

Little is known about the release of metal engineered nanomaterials (ENMs) from consumer goods, including lumber treated with micronized copper. Micronized copper is a recent form of antifouling wood preservative containing nanosized copper particles for use in pressure-treated lumber. The present study investigated the concentrations released and the release rate of total copper over the course of 133 d under freshwater, estuarine, and marine salinity conditions (0, 1, 10, and 30‰) for several commercially available pressure-treated lumbers: micronized copper azole (MCA) at 0.96 and 2.4 kg/m3, alkaline copper quaternary (ACQ) at 0.30 and 9.6 kg/m3, and chromated copper arsenate (CCA) at 40 kg/m3. Lumber was tested as blocks and as sawdust. Overall, copper was released from all treated lumber samples. Under leaching conditions, total release ranged from 2 to 55% of the measured copper originally in the lumber, with release rate constants from the blocks of 0.03 to 2.71 (units per day). Generally, measured release and modeled equilibrium concentrations were significantly higher in the estuarine conditions compared with freshwater or marine salinities, whereas rate constants showed very limited differences between salinities. Furthermore, organic carbon was released during the leaching and demonstrated a significant relationship with released copper concentrations as a function of salinity. The results indicate that copper is released into estuarine/marine waters from multiple wood treatments including lumber amended with nanoparticle-sized copper. Environ Toxicol Chem 2018;37:1956–1968. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.
Postnatal maturation of microglia is associated with alternative activation and activated TGFβ signaling
Authors: Attaai Abdelraheim , Neidert Nicolas , von Ehr Alexander , Potru Phani Sankar , Zöller Tanja , Spittau Björn
Published: March 2018

Microglia are involved in a widespread set of physiological and pathological processes and further play important roles during neurodevelopmental events. Postnatal maturation of microglia has been associated with the establishment of microglia‐specific gene expression patterns. The mechanisms governing microglia maturation are only partially understood but Tgfβ1 has been suggested to be one important mediator. In the present study, we demonstrate that early postnatal microglia maturation is associated with alternative microglia activation, increased engulfment of apoptotic cells as well as activated microglial Tgfβ signaling. Interestingly, microglial Tgfβ signaling preceded the induction of the microglia‐specific gene expression indicating the importance of Tgfβ1 for postnatal microglia maturation. Moreover, we provide evidence that Tgfβ1 is expressed by neurons in postnatal and adult brains defining neuron‐microglia communication via Tgfβ1 as an important event. Finally, we introduce the recently identified microglia marker Tmem119 as a direct Tgfβ1‐Smad2 target gene. Taken together, the data presented here further increase the understanding of Tgfβ1‐mediated effects in microglia and place emphasis on the importance of Tgfβ1 for microglia maturation and maintenance.
Screening an elderly hearing impaired population for mild cognitive impairment using Mini‐Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA)
Authors: Lim Magdalene Yeok Leng , Loo Jenny Hooi Yin
Published: March 2018

Objectives

To determine if there is an association between hearing loss and poorer cognitive scores on Mini‐Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) and to determine if poor hearing acuity affects scoring on the cognitive screening tests of MMSE and MoCA.

Methods

One hundred fourteen elderly patients (Singapore residents) aged between 55 and 86 years were sampled. Participants completed a brief history questionnaire, pure tone audiometry, and 2 cognitive screening tests—the MMSE and MoCA. Average hearing thresholds of the better ear in the frequencies of 0.5, 1, 2, and 4 kHz were used for data analysis.

Results

Hearing loss was significantly associated with poorer cognitive scores in Poisson regression models adjusted for age. Mini‐Mental State Examination scores were shown to decrease by 2.8% (P = .029), and MoCA scores by 3.5% (P = .013) for every 10 dB of hearing loss. Analysis of hearing‐sensitive components of “Registration” and “Recall” in MMSE and MoCA using chi‐square tests showed significantly poorer performance in the hearing loss group as compared to the normal hearing group. Phonetic analysis of target words with high error rates shows that the poor performance was likely contributed by decreased hearing acuity, on top of a possible true deficit in cognition in the hearing impaired.

Conclusions

Hearing loss is associated with poorer cognitive scores on MMSE and MoCA, and cognitive scoring is likely confounded by poor hearing ability. This highlights an important, often overlooked aspect of sensory impairment during cognitive screening. Provisions should be made when testing for cognition in the hearing‐impaired population to avoid over‐referral and subsequent misdiagnoses of cognitive impairment.
Orbito‐frontal cortex mechanism of inhibition of return in current and remitted depression
Authors: Dai Qin , Yin Xuntao , Li Hong , Feng Zhengzhi
Published: March 2018

Deficient inhibition of return (IOR) for emotional materials is an important cognitive biomarker of depression. However, its neural mechanism and role in depression remission remain largely unknown. Using functional magnetic resonance imaging (fMRI), this study observed the neural foundation of inhibition of return in individuals with current (n = 30) and remitted (n = 27) depression and in healthy controls (n = 33), by using a cue‐target task. The results showed that individuals with remitted depression (RMD) possessed a nonavoidant attention model for sad faces, which indicated a cue validity and was correlated with enhanced task‐ and resting‐state activation and function connectivity in orbitofrontal cortex (OFC). The patients with major depressive disorder (MDD), in contrast, displayed an IOR effect for all faces, which indicated a strategy of attention avoidance due to the high cognitive burden in the cue‐target task, and was correlated with decreased resting‐state activation and function connectivity in OFC. Moreover, the hippocampus, a less‐known cortex in IOR, showed a contrary model, that is, lower activation in depression remission and higher task‐ and resting‐state activation in depressive episodes. The results suggest the OFC mechanism of the IOR effect in remitted depression and the hippocampus mechanism of the IOR effect in depressive episodes, which offer potential biomarkers for the clinical treatment of depression.
Design and Endpoints for Clinical Trials in Primary Sclerosing Cholangitis
Authors: Ponsioen Cyriel Y. , Lindor Keith D. , Mehta Ruby , Dimick‐Santos Lara
Published: March 2018

Primary sclerosing cholangitis (PSC) is a rare and chronic liver disease for which there is no effective therapy. Interest has grown in developing treatments for this condition, with several agents proposed as potential therapies. However, there is a lack of clarity about how to measure clinical benefit in trials involving patients with this complex and rare disease. This article reviews regulatory information, the available literature on natural history, as well as potential candidate clinical and surrogate endpoints for PSC. (Hepatology 2018; 00:000‐000).
Photo‐Driven Hydrogen Evolution by an Artificial Hydrogenase Utilizing the Biotin‐Streptavidin Technology
Authors: Keller Sascha G. , Probst Benjamin , Heinisch Tillmann , Alberto Roger , Ward Thomas R.
Published: March 2018

Photocatalytic hydrogen evolution by an artificial hydrogenase based on the biotin‐streptavidin technology is reported. A biotinylated cobalt pentapyridyl‐based hydrogen evolution catalyst (HEC) was incorporated into different mutants of streptavidin. Catalysis with [Ru(bpy)3]Cl2 as a photosensitizer (PS) and ascorbate as sacrificial electron donor (SED) at different pH values highlighted the impact of close lying amino acids that may act as a proton relay under the reaction conditions (Asp, Arg, Lys). In the presence of a close‐lying lysine residue, both, the rates were improved, and the reaction was initiated much faster. The X‐ray crystal structure of the artificial hydrogenase reveals a distance of 8.8 Å between the closest lying Co‐moieties. We thus suggest that the hydrogen evolution mechanism proceeds via a single Co centre. Our findings highlight that streptavidin is a versatile host protein for the assembly of artificial hydrogenases and their activity can be fine‐tuned via mutagenesis.
Time–space fractional governing equations of transient groundwater flow in confined aquifers: Numerical investigation
Authors: Tu Tongbi , Ercan Ali , Levent Kavvas M.
Published: March 2018

In order to model non‐Fickian transport behaviour in groundwater aquifers, various forms of the time–space fractional advection–dispersion equation have been developed and used by several researchers in the last decade. The solute transport in groundwater aquifers in fractional time–space takes place by means of an underlying groundwater flow field. However, the governing equations for such groundwater flow in fractional time–space are yet to be developed in a comprehensive framework. In this study, a finite difference numerical scheme based on Caputo fractional derivative is proposed to investigate the properties of a newly developed time–space fractional governing equations of transient groundwater flow in confined aquifers in terms of the time–space fractional mass conservation equation and the time–space fractional water flux equation. Here, we apply these time–space fractional governing equations numerically to transient groundwater flow in a confined aquifer for different boundary conditions to explore their behaviour in modelling groundwater flow in fractional time–space. The numerical results demonstrate that the proposed time–space fractional governing equation for groundwater flow in confined aquifers may provide a new perspective on modelling groundwater flow and on interpreting the dynamics of groundwater level fluctuations. Additionally, the numerical results may imply that the newly derived fractional groundwater governing equation may help explain the observed heavy‐tailed solute transport behaviour in groundwater flow by incorporating nonlocal or long‐range dependence of the underlying groundwater flow field.
Benefits of antifungal therapy in asthma patients with airway mycosis: A retrospective cohort analysis
Authors: Li Evan , Tsai Chu‐Lin , Maskatia Zahida K. , Kakkar Ekta , Porter Paul , Rossen Roger D. , Perusich Sarah , Knight John M. , Kheradmand Farrah , Corry David B.
Published: March 2018

Introduction

Fungal airway infection (airway mycosis) is increasingly recognized as a cause of asthma and related disorders. However, prior controlled studies of patients treated with antifungal antibiotics have produced conflicting results. Our objective is to measure the effect of antifungal therapy in moderate to severe adult asthmatics with positive fungal sputum cultures in a single center referral‐based academic practice.

Methods

We retrospectively evaluated 41 patients with asthma and culture‐proven airway mycosis treated with either terbinafine, fluconazole, itraconazole, voriconazole, or posaconazole for 4 to >12 weeks together with standard bronchodilator and anti‐inflammatory agents. Asthma control (1 = very poorly controlled; 2 = not well controlled; and 3 = well controlled), peak expiratory flow rates (PEFR), serum total IgE, and absolute blood eosinophil counts before and after antifungal therapy were assessed. In comparison, we also studied nine patients with airway mycosis and moderate to severe asthma who received standard therapy but no antifungals.

Results

Treatment with azole‐based and allylamine antifungals was associated with improved asthma control (mean change in asthma control 1.72–2.25; p = 0.004), increased PEFR (69.4% predicted to 79.3% predicted, p = 0.0011) and markedly reduced serum IgE levels (1,075 kU/L to 463 kU/L, p = 0.0005) and blood eosinophil counts (Mean absolute count 530–275, p = 0.0095). Reduction in symptoms, medication use, and relapse rates decreased as duration of therapy increased. Asthmatics on standard therapy who did not receive antifungals showed no improvement in asthma symptoms or PEFR. Antifungals were usually well tolerated, but discontinuation (12.2%) and relapse (50%) rates were relatively high.

Conclusion

Antifungals help control symptoms in a subset of asthmatics with culture‐proven airway mycosis. Additional randomized clinical trials are warranted to extend and validate these findings.