bluuebunny/crossref_metadata_2025 huggingface dataset:
Actinides: Biogeochemistry
Authors: Boukhalfa Hakim , Neu Mary
Published: September 2018

Transuranic elements are highly reactive and form multiple oxidation states and complex species that can co‐exist, which underlies their fascinating inorganic, bioinorganic, and environmental chemistry. Because they are ubiquitous, microorganisms through their natural processes can interact with transuranic elements to change their speciation through both direct microbe‐transuranics interactions and indirect change of physical and chemical conditions in their environment. Understanding how microbial processes affect transuranic elements broadens our knowledge of fundamental transuranic chemistry, increases our understanding of the impact of biological and environmental receptors and metals on each other, and enables the development of applications in separation, remediation technologies, mammalian decorporation strategies, and nuclear repository design. Microorganisms and biogeochemical processes transform metals via numerous and varied chemical, biological, and geological processes, many of which have yet to be characterized in detail even for main group elements. The focus of this article is a brief overview of transuranic species that form in the environment and the biogeochemical processes that transform them. The primary processes that have been well studied for transuranic species are as follows: (i) complexation with inorganic/bioinorganic ligands within, and produced by, bacteria; (ii) complexation by organic ligands, including microbial metabolites, and transuranic bio‐associations; and (iii) biomineralization to form transuranic materials and mineral analogs.
Metal Ions and Complexes inAlzheimer's Disease: From Fundamental to Therapeutic Perspectives
Authors: Hureau Christelle
Published: September 2018

In this article, the author reviews the structural, thermodynamic, and kinetic data on metal ions (copper and zinc) binding to the amyloid‐β peptides of various sequences involved in Alzheimer's disease. Metal ions are indeed regarded as key players in Alzheimer's disease because they may contribute to the oxidative stress and modulate the aggregation propensity of the amyloid‐β peptides, two key processes in the etiology of the disease. An analogy with the influence of the interaction between metal ions and other intrinsically disordered peptides in different pathologies is also drawn. In a second part, several therapeutic and diagnostic approaches based on the role of metal ions are described and discussed. A selection of chelators, metallophores, prodrugs as well as inorganic compounds is proposed that illustrates the various strategies developed by inorganic medicinal chemists to fight Alzheimer's disease.
Gaseous Elemental Mercury Removal Using Combined Metal Ions and Heat Activated Peroxymonosulfate/H2O2 Solutions
Authors: Liu Yangxian , Wang Yan
Published: September 2018

Several novel oxidation removal processes of elemental mercury (Hg0) from flue gas using combined Fe2+/Mn2+ and heat activated peroxymonosulfate (PMS)/H2O2 solutions in a bubbling reactor were proposed. The operating parameters (e.g., PMS/H2O2 concentration, Fe2+/Mn2+ concentration, solution pH, activation temperature, and Hg0/NO/SO2/O2/CO2 concentration), mechanism and mass transfer‐reaction kinetics of Hg0 removal were investigated. The results show that heat and Fe2+/Mn2+ have significant synergistic effect for activating PMS and PMS/H2O2 to produce free radicals to oxidize Hg0. Hg0 removal is strongly affected by PMS/H2O2 concentration, Fe2+/Mn2+ concentration, activation temperature, and solution pH. · and ·OH produced from combined heat and Fe2+/Mn2+ activated PMS/H2O2 play a leading role in Hg0 removal. Under optimized experimental conditions, Hg0 removal efficiencies reach 100, 94.9, 66.9, and 58.9% in heat/Fe2+/PMS/H2O2, heat/Mn2+/PMS/H2O2, heat/Fe2+/PMS, and heat/Mn2+/PMS systems, respectively. Hg0 removal processes in four systems belong to fast reaction and were controlled by mass transfer under optimized experimental conditions. © 2018 American Institute of Chemical Engineers AIChE J, 65: 161–174, 2019
Tuning Charge Transport in Aromatic‐Ring Single‐Molecule Junctions via Ionic‐Liquid Gating
Authors: Xin Na , Li Xingxing , Jia Chuancheng , Gong Yao , Li Mingliang , Wang Shuopei , Zhang Guangyu , Yang Jinlong , Guo Xuefeng
Published: September 2018

Achieving gate control with atomic precision, which is crucial to the transistor performance on the smallest scale, remains a challenge. Herein we report a new class of aromatic‐ring molecular nanotransistors based on graphene–molecule–graphene single‐molecule junctions by using an ionic‐liquid gate. Experimental phenomena and theoretical calculations confirm that this ionic‐liquid gate can effectively modulate the alignment between molecular frontier orbitals and the Fermi energy level of graphene electrodes, thus tuning the charge‐transport properties of the junctions. In addition, with a small gate voltage (|VG|≤1.5 V) ambipolar charge transport in electrochemically inactive molecular systems (EG>3.5 eV) is realized. These results offer a useful way to build high‐performance single‐molecule transistors, thus promoting the prospects for molecularly engineered electronic devices.
Engineered Biosynthesis of β‐Alkyl Tryptophan Analogues
Authors: Boville Christina E. , Scheele Remkes A. , Koch Philipp , Brinkmann‐Chen Sabine , Buller Andrew R. , Arnold Frances H.
Published: September 2018

Noncanonical amino acids (ncAAs) with dual stereocenters at the α and β positions are valuable precursors to natural products and therapeutics. Despite the potential applications of such bioactive β‐branched ncAAs, their availability is limited due to the inefficiency of the multistep methods used to prepare them. Herein we report a stereoselective biocatalytic synthesis of β‐branched tryptophan analogues using an engineered variant of Pyrococcus furiosus tryptophan synthase (PfTrpB), PfTrpB7E6. PfTrpB7E6 is the first biocatalyst to synthesize bulky β‐branched tryptophan analogues in a single step, with demonstrated access to 27 ncAAs. The molecular basis for the efficient catalysis and broad substrate tolerance of PfTrpB7E6 was explored through X‐ray crystallography and UV/Vis spectroscopy, which revealed that a combination of active‐site and remote mutations increase the abundance and persistence of a key reactive intermediate. PfTrpB7E6 provides an operationally simple and environmentally benign platform for the preparation of β‐branched tryptophan building blocks.
Specific and Oriented Encapsulation of Fullerene C70 into a Supramolecular Double‐Decker Cage Composed of Shape‐Persistent Macrocycles
Authors: Kawano Shin‐ichiro , Fukushima Tomoaki , Tanaka Kentaro
Published: September 2018

An efficient strategy for the specific recognition of ellipsoidal fullerenes uses molecular containers with well‐designed three‐dimensional (3D) nanospaces. We describe the synthesis of a supramolecular double‐decker cage composed of shape‐persistent metallomacrocycles and pillar ligands. A discrete 3D nanospace was built within the molecular framework of the shape‐persistent‐macrocycle/bidentate‐pillar molecule. The single‐crystal structure of the supramolecular cage reveals a uniquely shaped inner cavity with a size and net volume (>670 Å3) that are well matched to the shape and size of C70. The cage exhibited higher selectivity for C70 over C60, the smaller carbon allotrope. We suggest that such C70‐selective recognition is derived from multiple CH–π interactions between hydrogen atoms inside the cage and C70.
Working with traumatized refugees on the Balkan route
Authors: Jović Vladimir
Published: September 2018

In the past several years Serbia has been in the center of the so‐called “Balkan route”, a pathway for refugees from the Middle East and Central Asia. In March 2016 the Balkan route was closed and this measure reduced the number of daily arrivals and prolonged the stay of refugees in Serbia. A brief overview of the current situation is given, together with some previous experiences in psychosocial programs for the displaced population during wars in former Yugoslavia and current psychosocial programs and interventions. Several short examples are presented to point out some aspects of those experiences that might have relevance to our understanding of the psychological trauma and possible ways of treatment.
Ultra‐performance liquid chromatography tandem mass spectrometry for the rapid, simultaneous analysis of ziprasidone and its impurities
Authors: Čarapić Marija , Nikolic Katarina , Marković Bojan , Petković Miloš , Pavlovic Milena , Agbaba Danica
Published: September 2018

The separation and characterization of the unknown degradation product of second‐generation antipsychotic drug ziprasidone are essential for defining the genotoxic potential of the compound. The aim of this study was to develop a simple UHPLC method coupled with tandem mass spectrometry (MS/MS) for chemical characterization of an unknown degradant, and the separation and quantification of ziprasidone and its five main impurities (I–V) in the raw material and pharmaceuticals. Chromatographic conditions were optimized by experimental design. The MS/MS fragmentation conditions were optimized individually for each compound in order to obtain both specific fragments and high signal intensity. A rapid and sensitive UHPLC–MS/MS method was developed. All seven analytes were eluted within the 7 min run time. The best separation was obtained on the Acquity UPLC BEH C18 (50 × 2.1 mm × 1.7 μm) column in gradient mode with ammonium‐formate buffer (10 mm; pH 4.7) and acetonitrile as mobile phase, with the flow rate of 0.3 mL min−1 and at the column temperature of 30°C. The new UHPLC–MS/MS method was fully validated and all validation parameters were confirmed. The fragmentation pathways and chemical characterization of an unknown degradant were proposed and it was confirmed that there are no structural alerts concerning genotoxicity.
Jack of many trades: Multifaceted role of neuropilins in pancreatic cancer
Authors: Matkar Pratiek N. , Jong Eric D. , Ariyagunarajah Ramya , Prud'homme Gerald J. , Singh Krishna K. , Leong‐Poi Howard
Published: September 2018

Neuropilins (NRPs) have been described as receptors for class 3 semaphorins and coreceptors for a plethora of ligands, such as members of the vascular endothelial growth factor (VEGF) family of angiogenic cytokines and transforming growth factor (TGF). Initial studies using genetic models have indicated that neuropilin‐1 (NRP‐1) is essential for axonal guidance during neuronal and cardiovascular development, regulated via semaphorins and VEGF, respectively, whereas the other homolog of neuropilin, NRP‐2, has been shown to play a more specific role in neuronal patterning and lymphangiogenesis. Pancreatic ductal adenocarcinoma (PDAC) remains a significant cause of cancer mortality with the lowest five‐year survival rate compared to other types of cancer. Recent findings have indicated that NRPs are abundantly expressed in pancreatic cancer cell lines and pancreatic tumor tissues, where they mediate several essential cancer‐initiating and cancer‐promoting functional responses through their unique ability to bind multiple ligands. Specifically, NRPs have been implicated in numerous biological processes such as cancer cell proliferation, survival, invasion, and tumor growth. More recently, several other protumorigenic roles mediated by NRPs have emerged, advocating NRPs as ideal therapeutic targets against PDAC.
RNA versus DNA G‐Quadruplex: The Origin of Increased Stability
Authors: Zaccaria Francesco , Fonseca Guerra Célia
Published: September 2018

DNA quadruplexes have been the subject of investigation because of their biological relevance and because of their potential application in supramolecular chemistry. Similarly, RNA quadruplexes are now gaining increasing attention. Although DNA and RNA quadruplexes are structurally very similar, the latter show higher stability. In this study we report dispersion‐corrected density functional theory (DFT‐D) quantum chemical calculations that were undertaken to understand the difference in stabilities of RNA and DNA quadruplexes. The smallest meaningful model of a stack of quartets, interacting with alkali metal cations, was simulated in an aqueous environment. The energy decomposition analysis allows for in‐depth examination of the interaction energies, emphasising the role of noncovalent interactions and better electrostatics in determining RNA‐GQs higher stabilities, particularly pinpointing the role of the extra 2′‐OH groups. Furthermore, our computations present new insights on why the cation is required for self‐assembly: unexpectedly the cation is not necessary to relieve the repulsion between the oxygen atoms in the central cavity, but it is needed to overcome the entropic penalty.
Synthesis of Ribo‐Azanucleosides by Anodic Oxidation: Reactivity Control of Intermediate for Efficient Access to Pharmacophores
Authors: Okamoto Kazuhiro , Shoji Takao , Tsutsui Mizuki , Shida Naoki , Chiba Kazuhiro
Published: September 2018

Azanucleosides, the sugar‐modified nucleoside analogues, have various biological activities, while their efficient synthetic strategy is still under development. Herein, a novel method for the synthesis of pharmaceutically relevant azanucleosides, β‐anomers of ribo‐azanucleosides, by means of site‐specific anodic C−H activation by using a nitroalkane–lithium perchlorate medium is reported. A mechanistic study of the electrochemical reaction and the armed/disarmed concept from traditional glycochemistry revealed that the 2′‐substituent has a significant effect on the reactivity of prolinol derivative, and suitable carboxylic acid additives can control the reactivity of the intermediate species, an iminium cation equivalent. Finally, this method was demonstrated to be applicable for the synthesis of β‐anomers of ribo‐azanucleosides with all four nucleobases in a stereoselective manner.
Efficient Photoelectrochemical Water Oxidation on Hematite with Fluorine‐Doped FeOOH and FeNiOOH as Dual Cocatalysts
Authors: Deng Jiujun , Zhang Qingzhe , Feng Kun , Lan Huiwen , Zhong Jun , Chaker Mohamed , Ma Dongling
Published: September 2018

An effective cocatalyst is usually required to improve the performance of photoelectrochemical (PEC) water splitting catalysts. A fluorine‐doped FeOOH (F:FeOOH) cocatalyst on a hematite photoanode was used to lower the onset potential by 140 mV and significantly improve the PEC performance. Moreover, a more effective dual cocatalytic system was prepared by subsequent loading of a FeNiOOH cocatalyst, which resulted in a further decrease of the onset potential by 270 mV. The final onset potential of the Fe2O3/F:FeOOH/FeNiOOH photoanode was lowered to 0.45 V versus the reversible hydrogen electrode (RHE), which is one of the lowest onset potential values ever reported for hematite photoanodes. The photocurrent also dramatically increased by a factor of approximately 3 to 0.9 mA cm−2 at 1.0 V versus RHE. Based on the structural, chemical, and electrochemical impedance spectroscopy characterization, the enhanced performance was attributed to the F:FeOOH overlayer, which reduced the surface recombination and accelerated the oxygen evolution reaction activity, and the FeNiOOH cocatalyst, which further enhanced the reaction kinetics. The facile preparation of the F:FeOOH cocatalyst and the design of the dual cocatalytic system will allow the development of high‐performance hematite photoanodes.
A congestion control method of SDN data center based on reinforcement learning
Authors: Jin Rong , Li Jiaojiao , Tuo Xin , Wang Weiming , Li Xiaolin
Published: September 2018

With the development of cloud computing and big data, the internal communication business in data center has increased dramatically, and then the traffic in data center has also significantly increased. The bandwidth of data center is difficult to meet the bandwidth requirements of those intensive applications, and data center is facing a risk of network congestion. Under the background of the development of network intelligence, software‐defined network (SDN) should demonstrate its intelligence as a future network architecture. In this paper, we introduce reinforcement learning into the SDN data center to implement congestion control based on flow. We improve the Q‐learning and Sarsa algorithms and propose two methods of congestion control based on the algorithms. Test results show that these two congestion control methods can control congestion effectively. And Sarsa method has a better performance of link utilization. The average link utilization of the Sarsa method is 2.4% higher than the Q‐learning method and is 4.48% higher than the on‐demand method.
Partial feedback impact on achievable rate region in multiple‐access relay channels
Authors: Moeen Taghavi Ehsan , Abed Hodtani Ghosheh
Published: September 2018

For discrete memoryless Slepian‐Wolf multiple‐access relay channel with relay‐sources feedback (SW‐MARC‐RSF), an achievable rate region via partial decode and forward strategy at the relay is proposed, and by extending the results to the continuous alphabet version, the corresponding achievable rate region of the Gaussian SW‐MARC‐RSF is obtained. It is shown that our results include the important previous works on multiple‐access channel (MAC) with feedback (Cover‐Leung rate region) and without feedback (Slepian‐Wolf [SW] rate region, etc) as special cases. Finally, through comparison of the achievable rate regions, with and without feedback, the impact of feedback on achievability is analyzed. The derived achievable rate region is shown to resolve the residual uncertainty at the receiver in an efficient way and demonstrates that in the partial decode and forward strategy, relay‐sources feedback increases the achievable rate region in both discrete memoryless and Gaussian multiple‐access relay channels.
Asymmetric hybridization in Cordulegaster (Odonata: Cordulegastridae): Secondary postglacial contact and the possible role of mechanical constraints
Authors: Solano Emanuela , Hardersen Sönke , Audisio Paolo , Amorosi Valentina , Senczuk Gabriele , Antonini Gloria
Published: September 2018

Two Cordulegaster dragonflies present in Italy, the Palaearctic and northern distributed Cordulegaster boltonii and the endemic to the south of the peninsula Cordulegaster trinacriae, meet in central Italy and give rise to individuals of intermediate morphology. By means of mitochondrial and nuclear markers and of Geometric Morphometrics applied to sexual appendages, we defined i) the geographical boundaries between the two species in Italy and ii) we determined the presence, the extent, and the genetic characteristics of the hybridization. Genetic data evidenced asymmetric hybridization with the males of C. trinacriae able to mate both interspecifically and intraspecifically. The results contrast with expectations under neutral gene introgression and sexual selection. This data, along with the morphological evidence of significant differences in size and shape of sexual appendages between the males of the two species, seem indicative of the role of mechanical constraints in intraspecific matings. The origin of the two species is dated about to 1.32 Mya and the hybridization resulted related to range expansion of the two species after Last Glacial Maximum and this led to the secondary contact between the two taxa in central Italy. At last, our results indicate that the range of C. trinacriae, a threatened and protected species, has been moving northward probably driven by climate changes. As a result, the latter species is currently intruding into the range of C. boltonii. The hybrid area is quite extended and the hybrids seem well adapted to the environment. From a conservation point of view, even if C. trinacriae has a strong genetic identity, the discovery of hybridization between the two species should be considered in a future species management.
An Extended AgI Cluster‐Based Framework Solid: Silver‐Thiolate Cluster Linked Polyoxometalate Including AgI···H–C Anagostic Interactions
Authors: Xie An , Wang Zhi , Cheng Li‐Ping , Luo Geng‐Geng , Liu Qing‐Yun , Sun Di
Published: September 2018

In this contribution, a new crystalline silver(I) cluster‐based coordination polymer, {[Ag11(iBuS)9(CH3CN)](Mo6O19)}n (SD/Ag11a) has been prepared and structurally characterized by single‐crystal X‐ray diffraction. The structure of SD/Ag11a consists of an asymmetric unit of Ag11S9 cluster, in which the coordination number of the eleven silver atoms varies from two to four and the Ag···Ag contacts in the cluster range from 2.897 to 3.374 Å. Each Ag11S9 cluster is interconnected by thiolate ligands iBuS–, thus forming one‐dimensional (1‐D) coordination polymer. An extended two‐dimensional (2‐D) infinite sheet formed by linking 1‐D silver(I) cluster‐based polymeric motifs and [Mo6O19]2– anions through intermolecular Ag···O weak interactions. One of the interesting structural features of SD/Ag11a is the presence of obvious Ag···H–C interactions between hydrogen atoms of the methylene and methyl groups on the iBuS– ligands and silver atoms. The solution behavior and the solid‐state optical properties of SD/Ag11a were also investigated.
Naphthalimide Platinum(IV) Compounds as Antitumor Agents with Dual DNA Damage Mechanism to Overcome Cisplatin Resistance
Authors: Wang Qingpeng , Li Guoshuai , Liu Zhifang , Tan Xiaoxiao , Ding Zhuang , Ma Jing , Li Lanjie , Li Dacheng , Han Jun , Wang Bingquan
Published: September 2018

A new series of naphthalimide platinum(IV) compounds with dual DNA damage mechanism were designed, synthesized and evaluated for antitumor activities. The platinum(IV) compounds could combine with DNA and cause DNA damage via naphthalimide fragment. Then the platinum(II) complexes released in reductive microenvironment would cause remarkable secondary DNA lesions. Some title compounds exhibit good antitumor activities and are of great potential in overcoming the drug resistance of cisplatin. Furthermore, naphthalimide platinum(IV) complexes could effectively combine with HSA by electrostatic force, which would influence the drug distribution and bioactivities in vivo. Moreover, the accumulation of the tested platinum(IV) compounds in whole cells and DNA is remarkably enhanced in comparison with cisplatin and oxaliplatin.
Exploration of Intrinsic Lipase‐Like Activity of Zirconium‐Based Metal‐Organic Frameworks
Authors: Liu Xiao , Qi Wei , Wang Yuefei , Su Rongxin , He Zhimin
Published: September 2018

To overcome the disadvantages of natural enzymes, artificial enzyme mimics attracted increasing attention of researchers. Metal‐organic frameworks (MOFs) are expected as one of the most appropriate candidates for artificial enzyme mimics. In this work, we demonstrate that the zirconium‐based MOF material UiO‐66 and its analogues possess intrinsic lipase‐like activity and can efficiently catalyze ester hydrolysis, transesterification and esterification reactions. Furthermore, the UiO‐66(NH2) exhibits much higher catalytic activity than that of UiO‐66, which can be attributed to the synergy effect between the zirconium cluster centres and the amino moieties during the catalytic cycle.
Synthesis of 3‐Amino‐1‐benzothiophene‐1,1‐diones by Alkyne Directed Hydroarylation and 1/N→3/C‐Sulfonyl Migration
Authors: Bernar Ivan , Blanco‐Ania Daniel , Stok Sophie J. , Sotorríos Lia , Gómez‐Bengoa Enrique , Rutjes Floris P. J. T.
Published: September 2018

A completely regioselective and highly stereoselective palladium‐catalyzed intramolecular hydroarylation of arenesulfonyl ynamines to benzothiazoles was developed. The presence of an electron‐withdrawing group on the triple bond of the sulfonyl ynamine was crucial for the success of the reaction and our mechanistic studies suggest an alkyne‐directed 5‐exo‐dig cyclization pathway. The products easily underwent photoinduced rearrangement to 3‐amino‐1‐benzothiophene‐1,1‐diones (up to 35 % yields after two steps).
Novel and Efficient Access to Flavones under Mild Conditions: Aqueous HI‐Mediated Cascade Cyclization/Oxidative Radical Reaction of 2‐Propynolphenols
Authors: Song Xian‐Rong , Li Ren , Yang Tao , Chen Xi , Ding Haixin , Xiao Qiang , Liang Yong‐Min
Published: September 2018

Herein we disclose a metal‐free and efficient method for the direct conversion of 2‐propynolphenols to biologically important flavones using aqueous HI as the promoter. This transformation was proved via 4‐iodo‐2H‐chromenes intermediate, which was simultaneously conversed to corresponding flavones by a Csp2−I bond cleavage and a C–O bond formation under air.
The Diverse One‐Pot Reactions of 2‐Quinolylzincates: Homologation, Electrophilic Trapping, Hydroxylation, and Arylation Reactions
Authors: Jeong Hye Jin , Chae Suyeon , Jeong Keunhong , Namgoong Sung Keon
Published: September 2018

2‐Quinolylzincates were efficiently produced from the regioselective metalation reactions of quinoline with various organozincates as key intermediates. The four different types of title reactions of these intermediates under the presented reaction conditions allowed for the facile formation of the corresponding C‐2 functionalized quinolines, which are not successfully accessed through typical zincation methods.
Synthesis of a Calix[4]arene‐Monodiazonium Salt for Surface Modification
Authors: Malytskyi Volodymyr , Troian‐Gautier Ludovic , Mattiuzzi Alice , Lambotte Sarah , Cornelio Benedetta , Lagrost Corinne , Jabin Ivan
Published: September 2018

Reduction of calix[4]arene‐tetradiazonium salts at the vicinity of a surface, notably a carbon surface, leads to the formation of a dense and robust covalently bound monolayer. To expand the versatility of this unique methodology, the efficient synthesis of a calix[4]arene bearing a single diazonium group and thus a single anchoring point was achieved. The introduction of the diazonium group was developed through an original approach involving a copper‐catalyzed reaction for the preparation of an intermediate azido‐calixarene. The grafting ability of the calix[4]arene‐monodiazonium cation was evaluated by investigating its electrochemical reduction at glassy carbon electrodes. Studies of the blocking properties of the modified surfaces toward redox probes evidenced the formation of compact covalently bound layers at the carbon substrates, opening interesting perspectives in the field of surface modification by calixarene‐based diazonium salts.
In situ measurements of fine sediment infiltration (FSI) in gravel‐bed rivers with a hydropeaking flow regime
Authors: Hauer Christoph , Holzapfel Patrick , Tonolla Diego , Habersack Helmut , Zolezzi Guido
Published: September 2018

The overpresence of fine sediment and fine sediment infiltration (FSI) in the aquatic environment of rivers are of increasing importance due to their limiting effects on habitat quality and use. The habitats of both macroinvertebrates and fish, especially spawning sites, can be negatively affected. More recently, hydropeaking has been mentioned as a driving factor in fine sediment dynamics and FSI in gravel‐bed rivers. The primary aim of the present study was to quantify FSI in the vertical stratigraphy of alpine rivers with hydropeaking flow regimes in order to identify possible differences in FSI between the permanently wetted area (during base and peak flows) and the so‐called dewatering areas, which are only inundated during peak flows. Moreover, we assessed whether the discharge ratio between base and peak flow is able to explain the magnitude of FSI. To address these aims, freeze‐core samples were taken in eight different alpine river catchments. The results showed significant differences in the vertical stratification of FSI between the permanently wetted area during base flow and the dewatering sites. Surface clogging occurred only in the dewatering areas, with decreasing percentages of fine sediments associated with increasing core depths. In contrast, permanently wetted areas contained little or no fine sediment concentrations on the surface of the river bed. Furthermore, no statistical relationship was observed between the magnitude of hydropeaking and the sampled FSI rate. A repeated survey of FSI in the gravel matrix revealed the importance of de‐clogging caused by flooding and the importance of FSI in the aquatic environment, especially in the initial stages of riparian vegetation establishment. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.
Petrology and geochemistry of Carboniferous volcanic rocks from the Awulale Iron Metallogenetic Belt in the West Tianshan Orogen (NW China): Constraints on petrogenesis and tectonic setting
Authors: Wang Bangyao , Jing Delong , Zhang Bo , Han Ling , Jiang Changyi
Published: September 2018

The Awulale Iron Metallogenic Belt (AIMB) is the most largest submarine volcanic‐hosted iron metallogenic belts in Tianshan Orogen (NW‐China). The volcanic rocks from the Dahalajunshan Formation, extensively occurred in the western Tianshan Mountains, are mainly hosted‐iron rocks in the AIMB. In combination with published data, our new major and trace elements and isotopic data of volcanic rocks from the AIMB help define their petrogenesis and the tectonic evolution of the western Tianshan. The results indicate that these volcanic rocks belong to shoshonite, high‐K calc‐alkaline, and med‐K series with a small amount of tholeiite series, consisting mainly of basalt, trachybasalt, basaltic andesite, basaltic trachyte andesite, andesite, trachyte andesite, rhyolite, and dacite. They display similar geochemical features such as enrichment in large‐ion lithophile elements (LILE) and light REE (LREE), depletion in heavy REE and high‐field strength elements (HFSE), and prominent Nb‐Ta‐Ti negative anomalies, associated with the subduction‐related magmas. The basaltic and andesitic rocks show a more scattered range of initial 87Sr/86Sr ratios and higher positive εNd(t) values, whereas the acid volcanic rocks exhibit lower positive εNd(t) values with limited initial 87Sr/86Sr ratios. The basaltic rocks were derived from partial melting of phlogopite‐bearing mantle sources in the spinel stability field triggered by the slab‐released fluids of the subducted plate. The andesitic rocks originated by partial melting of mafic migmatites in response to metasomatism formed by early magmas derived from the mantle intruded into the crustal rocks. The acid volcanic rocks are likely derived from the partial melting of components in the lower crust. Therefore, the generation of the volcanic rocks in the AIMB is genetically linked to the geodynamic evolution of the western Tianshan from convergent subduction to collision during the Carboniferous. Both magmatism and hydrothermal processes control the mineralization, and in general, the parental magma of iron mineralization is basaltic and andesitic magma.
Unconventional gas resources in theCantabrian Zone(NW Spain): A comprehensive preliminary assessment
Authors: Álvarez Rodrigo , Ordóñez Almudena , Canteli Paula , De Miguel Eduardo
Published: September 2018

With the aim of acquiring a better knowledge of the potential for unconventional gas resources in Spain, 134 rock samples were taken from 12 lithostratigraphic units in the Cantabrian Zone (north‐west Spain) and studied for a 3‐year period. The selected units gather, a priori, the basic conditions to constitute potential source rocks for unconventional hydrocarbons. Petrographic studies and total organic carbon analyses were carried out for all samples, whereas Rock‐Eval pyrolysis and vitrinite reflectance measurements with kerogen visual analysis were performed on selected samples. Lutites, litharenites, limestones, and slates are the predominant petrographic types. In most cases, the mean total organic carbon content is below the 2% limit for good quality potential source rocks. Only the Jurassic Rodiles and Tereñes limestones show total organic carbon values above this threshold. Rock‐Eval data reveal very low potential for hydrocarbon generation in almost all cases, with the exception of the dark mudstones of the Carboniferous Barcaliente Formation and the Rodiles Formation (fair and good potential for hydrocarbon generation, respectively). As regards thermal maturation, only the Ordovician formations are located in the peak of the gas generation interval. The Barcaliente and Rodiles formations are near the frontier oil/wet gas maturation areas, and the rest of the units are immature for gas generation.
Contemporary Issues in Women's Health
Authors: Geary Michael , Boama Vincent , Guinto Valerie T. , Sosa Claudio G.
Published: September 2018

The influence of the type of medical training program on trainees’ educational experience and outcome

Does lack of sleep due to night call affect surgical outcomes for patient?

Venous thromboprophylaxis in postpartum women

Intrauterine device use and cervical cancer

Vaginal rejuvenation: the evidence
Irrigation Strategies for Rotational Grazing Pasture in Canterbury, New Zealand, and Impacts on Irrigation Efficiency
Authors: KC Birendra , Mohssen Magdy , Chau Henry , Curtis Andrew , Cuenca Richard , Bright John , Srinivasan Ms , Safa Majeed
Published: September 2018

To support irrigation efficiency improvement, it is essential to identify the major limitations to irrigation management. Thirty‐two dairy farmers in Canterbury, New Zealand, were interviewed in order to understand current irrigation strategies on pastoral farms, particularly in relation to grazing rotations and plant available water (PAW). A water balance model, IrriCalc, was used to estimate irrigation and drainage from irrigation strategies obtained from the survey.

Current irrigation strategies differ greatly from farm to farm, which depend solely on PAW with no consideration for grazing rotations. During shoulder seasons (Sept–Oct and Mar–Apr) the majority of farmers start irrigation at 50% PAW and stop at 80% PAW. During the peak irrigation season (Nov–Feb) irrigation mostly starts at 70% PAW and stops at 100% PAW, leaving no room for precipitation. Results showed that over 14 irrigation seasons (2001/2002–2014/2015) this irrigation strategy would have produced a range of drainage per irrigation season between 40 and 400 mm, which demonstrates a high potential of optimising current irrigation strategies. Better utilization of rainfall during the irrigation season would minimize irrigation requirements and drainage losses. This would help to address the issues of nutrient losses and relieve the pressure on water resources. © 2018 John Wiley & Sons, Ltd.
Repeatability of Dixon magnetic resonance imaging and magnetic resonance spectroscopy for quantitative muscle fat assessments in the thigh
Authors: Grimm Alexandra , Meyer Heiko , Nickel Marcel D. , Nittka Mathias , Raithel Esther , Chaudry Oliver , Friedberger Andreas , Uder Michael , Kemmler Wolfgang , Engelke Klaus , Quick Harald H.
Published: September 2018

Background

Changes in muscle fat composition as for example observed in sarcopenia or muscular dystrophy affect physical performance and muscular function, like strength and power. The purpose of the present study is to measure the repeatability of Dixon magnetic resonance imaging (MRI) for assessing muscle volume and fat in the thigh. Furthermore, repeatability of magnetic resonance spectroscopy (MRS) for assessing muscle fat is determined.

Methods

A prototype 6‐point Dixon MRI method was used to measure muscle volume and muscle proton density fat fraction (PDFF) in the left thigh. PDFF was measured in musculus semitendinosus of the left thigh with a T2‐corrected multi‐echo MRS method. For the determination of short‐term repeatability (consecutive examinations), the root mean square coefficients of variation of Dixon MRI and MRS data of 23 young and healthy (29 ± 5 years) and 24 elderly men with sarcopenia (78 ± 5 years) were calculated. For the estimation of the long‐term repeatability (13 weeks between examinations), the root mean square coefficients of variation of MRI data of seven young and healthy (31 ± 7 years) and 23 elderly sarcopenic men (76 ± 5 years) were calculated. Long‐term repeatability of MRS was not determined.

Results

Short‐term errors of Dixon MRI volume measurement were between 1.2% and 1.5%, between 2.1% and 1.6% for Dixon MRI PDFF measurement, and between 9.0% and 15.3% for MRS. Because of the high short‐term repeatability errors of MRS, long‐term errors were not determined. Long‐term errors of MRI volume measurement were between 1.9% and 4.0% and of Dixon MRI PDFF measurement between 2.1% and 4.2%.

Conclusions

The high degree of repeatability of volume and PDFF Dixon MRI supports its use to predict future mobility impairment and measures the success of therapeutic interventions, for example, in sarcopenia in aging populations and muscular dystrophy. Because of possible inhomogeneity of fat infiltration in muscle tissue, the application of MRS for PDFF measurements in muscle is more problematic because this may result in high repeatability errors. In addition, the tissue composition within the MRS voxel may not be representative for the whole muscle.
Automatic and multithreaded method for determining the number of vector fitting poles based on empirical data
Authors: Al‐Hawari Feras H.
Published: September 2018

The vector fitting method has been largely used to generate accurate and passive time‐domain macromodels for circuits or structures characterized by frequency‐domain data such as scattering parameters. Nevertheless, very few approaches to determine the vector fitting order were discussed in the literature. In this paper, an iterative method to automatically identify the number of vector fitting poles is proposed. It can achieve acceptable performance and accuracy by capitalizing on the fact that the number of vector fitting poles lies in the range that spans the number of resonance peaks in the model and double that number as deduced from the empirical data that was acquired by experimentation on different types of models. Therefore, the algorithm's awareness of the frequency response of the model and confining the search for an acceptable order within the aforementioned range proved to be key factors to enable it to mostly outperform its MATLAB counterpart as shown in the experimental results. Furthermore, a multithreaded implementation of the proposed method is introduced to distribute the vector fitting passes on multicore processors in order to obtain a better speedup factor. The experiments that demonstrate the positive effect of the multithreaded version on performance are also presented.
Inter‐annual variation of the spring haze pollution over the North China Plain: Roles of atmospheric circulation and sea surface temperature
Authors: Chen Shangfeng , Guo Jianping , Song Linye , Li Jian , Liu Lin , Cohen Jason Blake
Published: September 2018

Haze pollution is a serious air quality issue in China. Previous studies over the North China Plain (NCP) mainly focused on analysing the haze during boreal winter. However, the variation in haze during spring and the related factors remain unclear. This study investigates inter‐annual variation of the spring haze, which is represented by the humidity‐corrected dry extinction coefficient (DEC) over the NCP. During high DEC years, pronounced positive DEC anomalies appear over the NCP and its surrounding regions. Correspondingly, a notable anticyclonic anomaly is observed over Northeast Asia, inducing significant southeasterly wind anomalies over the NCP. The anomalous southeasterly winds reduce wind speed and increase relative humidity, which provides favourable meteorological conditions for accumulation and growth of aerosol pollutants. Further analysis shows that the North Atlantic Oscillation (NAO) contributes to the formation of anticyclonic anomalies over Northeast Asia via downstream propagating atmospheric wave trains. Additionally, positive sea surface temperature (SST) anomalies over the subtropical northeastern Atlantic Ocean may also impact the DEC variation. The linear barotropic model experiment further confirms the important role of subtropical northeastern Atlantic SST anomalies in contributing to the anomalous anticyclone over Northeast Asia and southerly wind anomalies over the NCP region, which are triggered via eastwards propagating atmospheric wave trains. This study gives support to the idea that the NAO and the North Atlantic SST may be potential predictors for the frequently observed springtime NCP haze variation.
Large‐scale indices for assessing typhoon activity around Taiwan
Authors: Tu Jien‐Yi , Chen Jau‐Ming
Published: September 2018

This study quantifies large‐scale indices associated with variations in the western Pacific subtropical high (WPSH) and tropical sea surface temperature (SST) to assess typhoon activity around Taiwan. A WPSH index is constructed for both summer and early autumn as the meridional difference of areal means between the northern (120°–130°E, 25°–30°N) and southern (120°–130°E, 20°–25°N) regions (north minus south) of the 500 hPa height. These are regions north and south of Taiwan. In the high index years, typhoons forming in the tropical western North Pacific tend to be steered by easterly/southeasterly flows at the southwestern boundary of a northwards‐shifted WPSH to move northwestwards towards Taiwan, leading to increased typhoon activity around Taiwan. In the low index years, a southwards‐shifted, eastwards‐retreated WPSH steers typhoons along its western periphery to move northwards away from Taiwan. The northwards shift of the WPSH and consequent enhanced typhoon activity around Taiwan associate with a meridional wave train induced by a zonal SST gradient in summer, but link with a Matsuno‐Gill‐type response induced by tropical SSTs in early autumn. As so, the summer SST index is defined as a zonal gradient of areal‐mean SSTs between the tropical western Pacific (150°–175°E, 10°–20°N) and the Bay of Bengal–South China Sea–Philippine Sea region (80°–130°E, 5°–20°N) (former minus latter). In early autumn, the SST index is averaged from the tropical western Pacific over 130°–165°E, 5°S–5°N. All WPSH and SST indices in summer and early autumn are significantly correlated (at the 99% level) with the number of typhoons affecting Taiwan.
Immunomodulators targeting the PD‐1/PD‐L1 protein‐protein interaction: From antibodies to small molecules
Authors: Yang Jeffrey , Hu Longqin
Published: September 2018

Cancer immunotherapy has made great strides in the recent decade, especially in the area of immune checkpoint blockade. The outstanding efficacy, prolonged durability of effect, and rapid assimilation of anti‐PD‐1 and anti‐PD‐L1 monoclonal antibodies in clinical practice have been nothing short of a medical breakthrough in the treatment of numerous malignancies. The major advantages of these therapeutic antibodies over their small molecule counterparts have been their high binding affinity and target specificity. However, antibodies do have their flaws including immune‐related toxicities, inadequate pharmacokinetics and tumor penetration, and high cost burden to manufacturers and consumers. These limitations hinder broader clinical applications of the antibodies and have heightened interests in developing the alternative small molecule platform that includes peptidomimetics and peptides to target the PD‐1/PD‐L1 immune checkpoint system. The progress on these small molecule alternatives has been relatively slow compared to that of the antibodies. Fortunately, recent structural studies of the interactions among PD‐1, PD‐L1, and their respective antibodies have revealed key hotspots on PD‐1 and PD‐L1 that may facilitate drug discovery efforts for small molecule immunotherapeutics. This review is intended to discuss key concepts in immuno‐oncology, describe the successes and shortcomings of PD‐1/PD‐L1 antibody‐based therapies, and to highlight the recent development of small molecule inhibitors of the PD‐1/PD‐L1 protein‐protein interaction.
A Bayesian multivariate approach to estimating the prevalence of a superordinate category of disorders
Authors: Fawcett Jonathan M. , Fairbrother Nichole , Fawcett Emily J. , White Ian R.
Published: September 2018

Objective

Epidemiological research plays an important role in public health, facilitated by the meta‐analytic aggregation of epidemiological trials into a single, more powerful estimate. This form of aggregation is complicated when estimating the prevalence of a superordinate category of disorders (e.g., “any anxiety disorder,” “any cardiac disorder”) because epidemiological studies rarely include all of the disorders selected to define the superordinate category. In this paper, we suggest that estimating the prevalence of a superordinate category based on studies with differing operationalization of that category (in the form of different disorders measured) is both common and ill‐advised. Our objective is to provide a better approach.

Methods

We propose a multivariate method using individual disorder prevalences to produce a fully Bayesian estimate of the probability of having one or more of those disorders. We validate this approach using a recent case study and parameter recovery simulations.

Results

Our approach produced less biased and more reliable estimates than other common approaches, which were at times highly biased.

Conclusion

Although our approach entails additional effort (e.g., contacting authors for individual participant data), the improved accuracy of the prevalence estimates obtained is significant and therefore recommended.
Output feedback stabilization for a cascaded heat PDE‐ODE system subject to uncertain disturbance
Authors: Jia Yan‐Na , Liu Jun‐Jun , Li Sheng‐Jia
Published: September 2018

In this paper, we are concerned with the output feedback exponential stabilization of a cascaded parabolic partial differential equation–ordinary differential equation system where the control end suffers from the external uncertain disturbance. We design an unknown input–type state observer with the disturbance estimator term, which is used to stabilize this cascaded system and compensate the external disturbance simultaneously. The stabilizing state feedback control is designed for the observer system by the three‐step backstepping transformation, which is the corresponding observer‐based output feedback stabilizing control for the original system. Finally, the closed‐loop system is shown to be exponentially stable.
Unknown inputs observer design for descriptor systems with monotone nonlinearities
Authors: Gupta Mahendra Kumar , Tomar Nutan Kumar , Darouach Mohamed
Published: September 2018

This paper is devoted to the reduced‐order unknown inputs observer design problem for a class of descriptor systems having generalized monotone nonlinearities. The underlying system is considered in general rectangular form with unknown inputs in dynamic and in output equations. Under some basic assumptions on system parameters, sufficient conditions for the existence of observers are proved by showing the stability of their error dynamics. The case where nonlinearity appears in output equation is also considered. The importance of the work is illustrated by real‐life and academic examples.
System dynamics at sixty: the path forward
Authors: Sterman John
Published: September 2018

The late Jay Forrester founded the field of system dynamics 60 years ago. On this anniversary I ask what lessons his remarkable life of innovation and impact hold for the field. From a Nebraska ranch to MIT, servomechanisms, digital computing and system dynamics, Jay lived his entire life on the frontier, innovating to solve critical problems. Today, more than ever, humanity faces grave threats arising from our mismanagement of increasingly complex systems. Fortunately, progress in system dynamics, the natural and social sciences, computing, data availability, and other modeling disciplines have advanced the frontier in theory and methods to build reliable, useful knowledge of complex systems. We must therefore ask: What would Jay do if he were young today? How would he build on the knowledge, technology, data and methods now available to improve the science and practice of system dynamics? What must we now do to explore the next frontier?

© 2018 System Dynamics Society