bluuebunny/crossref_metadata_2025 huggingface dataset:
Rational Design of a 310‐Helical PIP‐Box Mimetic Targeting PCNA, the Human Sliding Clamp
Authors: Wegener Kate L. , McGrath Amy E. , Dixon Nicholas E. , Oakley Aaron J. , Scanlon Denis B. , Abell Andrew D. , Bruning John B.
Published: June 2018

The human sliding clamp (PCNA) controls access to DNA for many proteins involved in DNA replication and repair. Proteins are recruited to the PCNA surface by means of a short, conserved peptide motif known as the PCNA‐interacting protein box (PIP‐box). Inhibitors of these essential protein‐protein interactions may be useful as cancer therapeutics by disrupting DNA replication and repair in these highly proliferative cells. PIP‐box peptide mimetics have been identified as a potentially rapid route to potent PCNA inhibitors. Here we describe the rational design and synthesis of the first PCNA peptidomimetic ligands, based on the high affinity PIP‐box sequence from the natural PCNA inhibitor p21. These mimetics incorporate covalent i,i+4 side‐chain/side‐chain lactam linkages of different lengths, designed to constrain the peptides into the 310‐helical structure required for PCNA binding. NMR studies confirmed that while the unmodified p21 peptide had little defined structure in solution, mimetic ACR2 pre‐organized into 310‐helical structure prior to interaction with PCNA. ACR2 displayed higher affinity binding than most known PIP‐box peptides, and retains the native PCNA binding mode, as observed in the co‐crystal structure of ACR2 bound to PCNA. This study offers a promising new strategy for PCNA inhibitor design for use as anti‐cancer therapeutics.
Quantum Simulation Verifies the Stability of an 18‐Coordinated Actinium–Helium Complex
Authors: Ozama Eiki , Adachi Sadia , Takayanagi Toshiyuki , Shiga Motoyuki
Published: June 2018

Structures of a trivalent actinium cation in helium clusters (Ac3+⋅Hen) have been studied by quantum path integral molecular dynamics simulations with different cluster sizes, n=18–200. The nuclear quantum effect of helium atoms plays an important role in the vibrational amplitude of the Ac3+–He complex at low temperatures (1–3 K) at which the complex is stable. We found that the coordination number of helium atoms comprising the first solvation shell can be as high as eighteen. In this case, the helium atoms are arranged in D4d symmetry. The Ac3+–He18 complex becomes more rigid as the cluster increases in size, which implies that it becomes more stable. The simulation results are based on an accurate description of the Ac3+–He interaction using relativistic ab initio calculations.
Electrochemical Cobalt‐Catalyzed C−H Activation
Authors: Sauermann Nicolas , Meyer Tjark H. , Ackermann Lutz
Published: June 2018

Carbon–heteroatom bonds represent omnipresent structural motifs of the vast majority of functionalized materials and bioactive compounds. C−H activation has emerged as arguably the most efficient strategy to construct C−Het bonds. Despite of major advances, these C−H transformations were largely dominated by precious transition metal catalysts, in combination with stoichiometric, toxic metal oxidants. Herein, we discuss the recent evolution of cobalt‐catalyzed C−H activations that enable C−Het formations with electricity as the sole sustainable oxidant until May 2018.
The Future of Polar Organometallic Chemistry Written in Bio‐Based Solvents and Water
Authors: García‐Álvarez Joaquín , Hevia Eva , Capriati Vito
Published: June 2018

There is a strong imperative to reduce the release of volatile organic compounds (VOCs) into the environment, and many efforts are currently being made to replace conventional hazardous VOCs in favour of safe, green and bio‐renewable reaction media that are not based on crude petroleum. Recent ground‐breaking studies from a few laboratories worldwide have shown that both Grignard and (functionalised) organolithium reagents, traditionally handled under strict exclusion of air and humidity and in anhydrous VOCs, can smoothly promote both nucleophilic additions to unsaturated substrates and nucleophilic substitutions in water and other bio‐based solvents (glycerol, deep eutectic solvents), competitively with protonolysis, at room temperature and under air. The chemistry of polar organometallics in the above protic media is a complex phenomenon influenced by several factors, and understanding its foundational character is stimulating in the perspective of the development of a sustainable organometallic chemistry.
Enantiomeric separation of Novel Psychoactive Substances by capillary electrophoresis using (+)‐18‐crown‐6‐tetracarboxylic acid as chiral selector
Authors: Hägele Johannes S. , Schmid Martin G.
Published: June 2018

In the recent years, hundreds of Novel Psychoactive Substances (NPS) have entered both the European and the global drug market. These drugs, which are mainly used for recreational matters, have caused serious social problems. Every year, the spectrum of these misused drugs is enlarged by new derivatives, which are produced by modifications of basic structures of already well‐known substances. Additionally, a lot of them possess a stereogenic center which leads to 2 enantiomeric forms. The fact that the pharmacological effects and potencies of the enantiomers of these chiral NPS may differ can be assumed from a broad spectrum of active pharmaceutical ingredients. For this reason, analytical method development regarding enantiomeric separation for these classes of substances is of great pharmaceutical and medical interest. The aim of this work was to create an easy‐to‐prepare chiral capillary electrophoresis method for the enantioseparation of NPS which contains a primary amino group by means of (+)‐18‐crown‐6‐tetracarboxylic acid as chiral selector. Novel Psychoactive Substances were purchased at various Internet stores or represent samples seized by Austrian police. The effects of selector concentration, the electrolyte composition, and the addition of organic modifiers to the background electrolyte on enantioseparation were investigated. Under optimized conditions, the use of 20‐mM (+)‐18‐crown‐6‐tetracarboxylic acid, 10‐mM Tris, and 30‐mM citric acid buffer at pH 2.10 turned out to be effective. Fifteen of 24 tested NPS were resolved in their enantiomers within 15 minutes. It was found that all NPS were traded as racemic mixtures.
Activation and deactivation scenarios in a plasma‐synthesized Co/C catalyst for Fischer‐Tropsch synthesis
Authors: Aluha James , Abatzoglou Nicolas
Published: June 2018

A carbon‐supported cobalt nano‐catalyst (Co/C) synthesized through plasma was tested for Fischer‐Tropsch activity. Catalyst deactivation and activation protocols studied included in situ sample pre‐treatment at 673 K in gas flowing at the rate of 250 cm3 · min−1 in: (a) H2 only, (b) CO only, and (c) CO followed by H2, with each cycle lasting 24 h. The so‐treated catalyst samples were then tested for FTS activity for over 50 h of time‐on‐stream (TOS), at 2.2 MPa pressure and 493 or 518 K temperature in a 3‐phase continuously‐stirred tank slurry reactor (3‐φ‐CSTSR) using squalane (C30H62) as the carrier liquid phase. The feed gas composition of molar H2:CO = 1.7 comprising 50 % H2, 30 % CO, and 10 % CO2 balanced in Ar for mass balance determination, flowing at a gas hourly space velocity (GHSV) of 3360 cm3 · h−1 · g−1 of catalyst. Fresh catalysts and those reduced by CO‐only were completely inactive at 493 K and initial inactivity was attributed to the excessive C matrix formed around the metal nanoparticles during catalyst synthesis. The sample that was reduced by H2 only was the most active, although it showed the fastest declining activity due to cumulative high H2O vapour pressure in the FTS reactor, while the sample pre‐treated in both CO and H2 demonstrated a higher degree of stability with TOS.
1,2,3‐Triazolium‐Based Cationic Amphipathic Peptoid Oligomers Mimicking Antimicrobial Helical Peptides
Authors: Shyam Radhe , Charbonnel Nicolas , Job Aurélie , Blavignac Christelle , Forestier Christiane , Taillefumier Claude , Faure Sophie
Published: June 2018

Amphipathic cationic peptoids (N‐substituted glycine oligomers) represent a promising class of antimicrobial peptide mimics. The aim of this study is to explore the potential of the triazolium group as a cationic moiety and helix inducer to develop potent antimicrobial helical peptoids. Herein we report the first solid‐phase synthesis of peptoid oligomers incorporating 1,2,3‐triazolium‐type side chains and their evaluation against Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus. Several triazolium‐based oligomers, even of short length, selectively kill bacteria over mammalian cells. SEM visualization of S. aureus cells treated with a dodecamer and a hexamer reveals severe cell membrane damage and suggests that the longer oligomer acts by pore formation.
In vitro simulation of erosive challenges to human enamel using a novel artificial mouth
Authors: Qutieshat Abubaker S. , Mason Andrew Graham , Chadwick Richard Graham
Published: June 2018

This in vitro work reports upon the design, build and operation of an artificial environment (Saltus) that sought to simulate the process of in vivo dental erosion upon human enamel. A novel testing environment, housed 8 erosion testing substrate specimens, that on separate occasions were subject to 4 different experimental diets, of increasing erosive challenge, simulating the consumption of an acidic beverage. Each set of specimens was subjected to one of the experimental diets only. These were liquid only and administered the test beverage over a standardized range of volumes and durations. Flow of both artificial unstimulated and stimulated saliva was maintained throughout and the effects upon the substrates were measured by profilometry, surface microhardness determination and chemical analysis of the saliva and beverage mixture for traces of Calcium and Phosphate ions. The overall trend of surface hardness reduction, depth of surface loss and ion loss across the diets increased in proportion to the severity of insult. Accepting the limitations of this study Saltus appeared to perform well as an environment in which to simulate and assess dental erosion using parameters defined by previous in vivo observations of human drinking behaviour. The authors however acknowledge that in vitro testing can never replicate fully the in vivo situation.
Facile Modification of Titania with Nickel Sulfide and Sulfate Species for the Photoreformation of Cellulose into Hydrogen
Authors: Hao Hongchang , Zhang Ling , Wang Wenzhong , Zeng Shuwen
Published: June 2018

Photocatalytic cellulose reformation is regarded as a potential and affordable route for sustainable H2 evolution. However, direct photoreformation still suffers from challenges such as the limited solubility of cellulose and the dependence on the catalytic activity of noble metals. Herein, we report a new photoreformation of cellulose into H2 over TiO2 that is modified with nickel sulfide (NixSy) and chemisorbed sulfate species (SO42−) by a one‐pot approach. A significant elevation in the photocatalytic hydrogen evolution rate is achieved with a maximal value of 3.02 mmol g−1 h−1 during the first 3 h, which is almost 76‐fold higher than that of P25 and comparable to that of Pt‐P25. Aided by systematic investigation, it is proposed that nickel sulfide and sulfate modification contribute synergistically to the remarkably increased efficiency of biomass transformation. Specifically, NixSy acts as a cocatalyst for photocatalytic H2 production, and we infer that SO42− ions promote cellulose hydrolysis and the consequent accessibility of the biomass to catalysts. Further, the accumulated formate intermediates have a poisoning effect on the catalysts, the desorption of which can be controlled by tuning the aqueous alkalinity. Overall, our strategy for the modification of TiO2 with SO42− and NixSy provides a new perspective for the concurrent acceleration of cellulose hydrolysis and increase of the number of hydrogen evolution sites for the efficient photocatalytic reformation of cellulose into H2.
Solution‐Processed Air‐Stable Copper Bismuth Iodide for Photovoltaics
Authors: Hu Zhaosheng , Wang Zhen , Kapil Gaurav , Ma Tingli , Iikubo Satoshi , Minemoto Takashi , Yoshino Kenji , Toyoda Taro , Shen Qing , Hayase Shuzi
Published: June 2018

Bismuth‐based solar cells have been under intensive interest as an efficient non‐toxic absorber in photovoltaics. Within this new family of semiconductors, we herein report a new, long‐term stable copper bismuth iodide (CuBiI4). A solutionprocessed method under air atmosphere is used to prepare the material. The adopted HI‐assisted dimethylacetamide (DMA) co‐solvent can completely dissolve CuI and BiI3 powders with high concentration compared with other organic solvents. Moreover, the high vapor pressure of tributyl phosphate, selected for the solvent vapor annealing (SVA), enables complete low‐temperature (≤70 °C) film preparation, resulting in a stable, uniform, dense CuBiI4 film. The average grain size increases with the precursor concentration, greatly improving the photoluminescence lifetime and hall mobility; a carrier lifetime of 3.03 ns as well as an appreciable hall mobility of 110 cm2 V−1s−1 were obtained. XRD illustrates that the crystal structure is cubic (space group Fd3m) and favored in the [1 1 1] direction. Moreover, the photovoltaic performance of CuBiI4 was also investigated. A wide bandgap (2.67 eV) solar cell with 0.82 % power conversion efficiency is presented, which exhibits excellent long‐term stability over 1008 h under ambient conditions. This air‐stable material may give an application in future tandem solar cells as a stable short‐wavelength light absorber.
A high‐speed RSD‐based flexible ECC processor for arbitrary curves over general prime field
Authors: Shah Yasir Ali , Javeed Khalid , Azmat Shoaib , Wang Xiaojun
Published: June 2018

This workpresents a novel high‐speed redundant‐signed‐digit (RSD)‐based elliptic curve cryptographic (ECC) processor for arbitrary curves over a general prime field. The proposed ECC processor works for any value of the prime number and curve parameters. It is based on a new high speed Montgomery multiplier architecture which uses different parallel computation techniques at both circuit level and architectural level. At the circuit level, RSD and carry save techniques are adopted while pre‐computation logic is incorporated at the architectural level. As a result of these optimization strategies, the proposed Montgomery multiplier offers a significant reduction in computation time over the state‐of‐the‐art. At the system level, to further enhance the overall performance of the proposed ECC processor, Montgomery ladder algorithm with (X,Y)‐only common Z coordinate (co‐Z) arithmetic is adopted. The proposed ECC processor is synthesized and implemented on different Xilinx Virtex (V) FPGA families for field sizes of 256 to 521 bits. On V‐6 platform, it computes a single 256 to 521 bits scalar point multiplication operation in 0.65 to 2.6 ms which is up to 9 times speed‐up over the state‐of‐the‐art.
Analysis of mismatch impact on image rejection ratio for passive polyphase filters
Authors: Martínez‐Pérez A.D. , Aznar F. , Royo G. , Sánchez‐Azqueta C. , Celma S.
Published: June 2018

Passive polyphase filters (PPFs) are useful symmetric RC networks for processing analog quadrature signals. Passive polyphase filters are also used to implement differential‐quadrature or quadrature‐differential converters. The quality of these quadrature signals is essential to achieve good performance in modern communication systems. However, mismatch effects can produce notable degradation in the PPF frequency response, and this results in an important reduction in quadrature signal quality, being amplitude balance and phase offset notably affected. Both these errors could be summarized and evaluated together considering image rejection ratio as a figure of merit. This work deepens in the analysis of mismatch impact on PPF, studying image rejection ratio degradation for 2 PPF types, and a systematic method is proposed to obtain the worst case of mismatch in PPFs with any number of stages. It has been validated in a 65‐nm CMOS technology.
A constraint optimization of low‐delay and low‐operation driven FIR digital filters for big data signal processing
Authors: Hirakawa Tomohiro , Nakamoto Masayoshi
Published: June 2018

In big data signal processing system, low‐delay and low‐operation driven digital filters are required for large amounts of data processing. We introduce a design method for low‐delay FIR (finite impulse response) filters with semi‐sparse coefficients. The semi‐sparse coefficients stand for to have some 0 ± 1 values with real values. The semi‐sparse coefficients lead to reduction of number of multipliers. We show the design problem of the filters are formulated in a constraint optimization problem. Also, we propose a design algorithm to solve the design problem. Using the filters, the number of multipliers can be reduced. Finally, we present examples to demonstrate the effectiveness of the proposed method.
Soil homogenization and microedges: perspectives on soil‐based drivers of plant diversity and ecosystem processes
Authors: Stover Holly J. , Henry Hugh A. L.
Published: June 2018

Disturbance caused by agriculture and resource extraction has resulted in widespread homogenization of soils at the local (within‐site) scale. Here, we describe how experimental manipulation of heterogeneity at the local scale has had inconsistent effects on plant species diversity. Moreover, we discuss how soil homogenization per se typically has not been accounted for in the study of heterogeneity–diversity relationships, and how disturbance, often viewed as an artifact in soil heterogeneity experiments, can be a key driver of soil homogenization. We propose a conceptual model for describing the relationship between plant size, patch size, and diversity, and we discuss how factors such as disturbance, productivity, and competition among species either should be controlled or accounted for in soil heterogeneity–plant diversity experiments. Finally, we consider the concept of soil patch microedges, which may provide unique microsites for increased plant diversity, and how these biogeochemical and hydrological interfaces could potentially drive ecosystem processes in a manner unique from the adjacent patches. Overall, this synthesis integrates perspectives on the functional links between plant‐driven processes, and soil patterns and processes.
Design of a coil geometry for generating magnetic field to evaluate biological effects at 85 kHz
Authors: Matsubara Kazuki , Wada Keiji , Suzuki Yukihisa
Published: June 2018

In recent years, the use of induction‐heating systems has increased and wireless power transmission (WPT) systems have been discussed. These applications are installed close to a human body. Therefore, it is important to discuss the effects of alternating magnetic fields and to evaluate electromagnetic interference. This paper discusses the design procedure of a magnetic field generator to evaluate the electromagnetic interference at 85 kHz that is being studied in WPT systems for EV and HEV. The magnetic field generator presented in this paper consists of a single‐phase inverter circuit that uses SiC‐MOSFETs and an air–core inductor that is used as the coil for generating a magnetic field. In particular, this paper shows that the coil used for generating magnetic field needs to reduce the winding voltage to generate higher magnetic flux. In addition, this paper presents the design procedure of the proposed coil structure that can satisfy some limited conditions. The experimental results of the proposed system rated at 82 kHz and 100 A are presented.
Bis(tri‐tert‐butylphosphine)palladium(0)‐Catalyzed Iodine–Fluorine Exchange at closo‐Carboranes
Authors: Ishita Keisuke , Khalil Ahmed , Tiwari Rohit , Gallucci Judith , Tjarks Werner
Published: June 2018

The bis(tri‐tert‐butylphosphine)palladium(0) [Pd(tBu3P)2]‐catalyzed synthesis of fluorinated closo‐carboranes from 3D aromatic iodo‐closo‐carboranes by nucleophilic halogen exchange using silver(I) fluoride is described. Fluorination of 2‐iodo‐closo‐p‐carborane proceeded more readily than that of 9‐iodo‐closo‐m‐carborane. Iodine–fluorine exchange at 9‐iodo‐closo‐o‐carborane was not successful yielding instead a charge‐compensated dibutylphosphonio nido‐o‐carborane. The described methodology advances the understanding of nucleophilic fluorination at aromatic systems by Pd0/PdII catalysis. With further optimization, it could find application in the synthesis of 18F‐labeled carboranyl diagnostics for biomedical applications.
The Phosphonium Ion [Cy3PCHCl2]+: Synthesis and Properties
Authors: Spang Nils , Müller Matthias , Buchner Magnus R.
Published: June 2018

The synthetic pathway to the functional phosphonium cation [Cy3PCHCl2]+ (3) has been evaluated by using in situ 31P NMR spectroscopy and mass spectrometry. The synthesis is only successful if CCl4/CHCl3 mixtures are used. A mechanism for the varying reactivity in different solvents is given as well as a mechanism for the observed equilibrium between ions [Cy3PCHCl2]+ and [Cy3PCH2Cl]+ (12). Through the anticipated hydrogen bonding interaction between [Cy3PCHCl2]+ and the corresponding anion, crystal structures of the compounds [Cy3PCHCl2]Cl·2CHCl3 (3a) and [Cy3PCHCl2]3[H3O][H5O2]Cl5·C6D6 (3b) could be obtained and evaluated.
Dirhodium(II)‐Mediated Alkene Epoxidation with Iodine(III) Oxidants
Authors: Nasrallah Ali , Grelier Gwendal , Lapuh Maria Ivana , Duran Fernando J. , Darses Benjamin , Dauban Philippe
Published: June 2018

Dirhodium(II) complexes and iodine(III) oxidants have found useful applications in synthetic nitrene chemistry. In this study, the combination of the dirhodium(II) complex Rh2(tpa)4(tpa = triphenylacetate) with the iodine(III) oxidant PhI(OPiv)2is shown to promote the epoxidation of alkenes in the presence of 2 equivalents of water. The reaction can be applied to diversely substituted alkenes and the corresponding epoxides are isolated with yields of up to 90 %. A possible mechanism involves the dirhodium(II) complex as a Lewis acid species that would tune the oxidizing character of the iodine(III) reagent.
Steroid–Fullerene Hybrids from Epiandrosterone: Synthesis, Characterization and Theoretical Study
Authors: Almagro Luis , Hernández‐Castillo David , Ortiz Orlando , Alonso Dayana , Ruiz Alberto , Coro Julieta , Herranz María Ángeles , Molero Dolores , Martínez‐Álvarez Roberto , Suárez Margarita , Martín Nazario
Published: June 2018

New hybrid fullerene–steroid derivatives were prepared by using the Bingel–Hirsch protocol, by treatment of [60]fullerene with malonates bearing the appropriate steroid moieties obtained, in turn, from the functionalization of epiandrosterone, an important naturally occurring steroid hormone. Monocycloadduct C60‐steroid conjugates were obtained by functionalization of ring A or ring D of the steroid moiety. We have also described the multistep preparation of a [60]fullerene hybrid dumbbell endowed with two fullerene units connected through an epiandrosterone molecule by a cyclopropanation reaction. The new compounds have been spectroscopically characterized and their redox potentials, determined by cyclic voltammetry, reveal three reversible reduction waves for monocycloadducts (8, 9 and 11, 12), whereas dumbbell‐type derivative 10 exhibits the best electron‐accepting abilities of the Bingel‐type fullerene–steroid series. Theoretical calculations at semiempirical (AM1) and single point B3LYP‐D3/6‐31G+(d,p) levels have predicted the most stable conformations for the hybrid compounds and allow explaining the observed regioselectivity in the cyclopropanation reaction with dimalonate 7 during the synthesis of the dumbbell derivative.
Syntheses, Structures and Dynamics of 9‐(Ferrocenylmethyl)anthracene and Related Molecular Gears: Phosphorus to the Rescue!
Authors: Nikitin Kirill , Ortin Yannick , Müller‐Bunz Helge , Gilheany Declan G. , McGlinchey Michael J.
Published: June 2018

The rotational barriers of the anthracenyl and triptycyl units in 1‐(9‐anthracenyl)‐1′‐(9‐triptycyl)ferrocene were independently measured as 11.6 and 17.6 kcal mol–1, respectively. Attempts to reduce 9‐ferrocenoylanthracene to 9‐(ferrocenylmethyl)anthracene, 3, in which the sandwich moiety and the planar aromatic are linked through an angular methylene unit, were thwarted by reduction of the anthracene moiety to form 9‐ferrocenylmethyl‐9,10‐dihydroanthracene, 5, and 9‐ferrocenoyl‐9,10‐dihydroanthracene, 6. However, treatment of phenyl(ferrocenyl)methanol, 9, with triphenylphosphine and triflic acid gave [(phenyl)(ferrocenyl)methyl]phosphonium triflate, 10; subsequent hydrolysis yielded benzylferrocene (93 %). Analogously, (9‐anthracenyl)(ferrocenyl)methanol, 11, and Ph3P/TfOH furnished 3 (up to 92 %) together with various amounts of its anthracenylidene tautomer, 15, depending on the hydrolysis conditions. Surprisingly, during the chromatographic purification of 11, partial dehydration occurred to give di[(9‐anthracenyl)(ferrocenyl)methyl] ether, 12. The fluxional dynamics of 3, 11 and 12 are very different: anthracenyl rotation of the group in 3 and 11 is facile (barriers of < 9 and ≈ 9.6 kcal mol–1, respectively), but is arrested in 12 due to mutual steric locking of the two anthracenes. Diels–Alder addition of benzyne to 3 furnished 9‐(ferrocenylmethyl)triptycene, 16. The molecular structures of 3, 5, 9, 10, 11, 12 and 16 were determined by X‐ray crystallography.
Online fully automated SPE‐HPLC‐MS/MS determination of ceftiofur in bovine milk samples employing a silica‐anchored ionic liquid as sorbent
Authors: Ferreira Débora Cecatto , de Toffoli Ana Lúcia , Maciel Edvaldo Vasconcelos Soares , Lanças Fernando Mauro
Published: June 2018

Solid‐phase extraction coupled online with high performance liquid chromatography and tandem mass spectrometry was successfully applied to determine low concentrations of ceftiofur antibiotic in bovine milk samples. A silica‐anchored ionic liquid was applied as sorbent material to be used as extraction phase in the proposed online system. The material was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. In order to improve the system reproducibility, the following experimental parameters were optimized: organic solvent percentage, time and sample loading flow rate. Subsequently, the method was validated presenting satisfactory results as adequate selectivity, good linearity and correlation coefficient higher than 0.98. The limit of detection and quantification were 0.1 and 0.7 μg/L, respectively. The precision of the methodology was evaluated as repeatability and intermediate precision, with relative standard deviation values lower than 15%. The accuracy of the method ranged from 72.8 to 137% and the minimum and maximum recovery values were 73.4 and 111.3%, respectively. After the validation, seven milk samples were analyzed and although ceftiofur was not detected in any of them the method was demonstrated to be efficient when applied to the analysis of milk samples fortified with the pollutant of interest.
Elevated aeolian sediment transport on the Colorado Plateau, USA: The role of grazing, vehicle disturbance, and increasing aridity
Authors: Nauman Travis W. , Duniway Michael C. , Webb Nicholas P. , Belnap Jayne
Published: June 2018

Dryland wind transport of sediment can accelerate soil erosion, degrade air quality, mobilize dunes, decrease water supply, and damage infrastructure. We measured aeolian sediment horizontal mass flux (q) at 100 cm height using passive aspirated sediment traps to better understand q variability on the Colorado Plateau. Measured q ‘hot spots’ rival the highest ever recorded including 7,460 g m−2 day−1 in an off‐highway vehicle (OHV) area, but were more commonly 50‐2,000 g m−2 day−1. Overall mean q on rangeland sites was 5.14 g m−2 day−1, considerably lower than areas with concentrated livestock use (9‐19 g m−2 day−1), OHV use (414 g m−2 day−1), and downwind of unpaved roads (13.14 g m−2 day−1), but were higher than areas with minimal soil disturbance (1.60 g m−2 day−1). Rangeland q increased with increasing annual temperature, increased winds, and decreasing precipitation. Spatial modeling suggests that ~92‐93% of regional q occurs in rangelands versus ~7‐8% along unpaved roads. Four of the five largest road q values (n=33) measured were along roads used primarily for oil or gas wells. Our findings indicate that predicted future mega‐droughts will increase q disproportionately in disturbed rangelands, and potentially further compromise air quality, hydrologic cycles, and other ecosystem services. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.
Acute toxicity of sodium chloride and potassium chloride to a unionid mussel (Lampsilis siliquoidea) in water exposures
Authors: Wang Ning , Ivey Christopher D. , Dorman Rebecca A. , Ingersoll Christopher G. , Steevens Jeffery , Hammer Edward J. , Bauer Candice R. , Mount David R.
Published: June 2018

Freshwater mussels (order Unionoida) are one of the most imperiled groups of animals in the world. However, many ambient water quality criteria and other environmental guideline values do not include data for freshwater mussels, in part because mussel toxicity test methods are comparatively new and data may not have been available when criteria and guidelines were derived. The objectives of the present study were to evaluate the acute toxicity of sodium chloride (NaCl) and potassium chloride (KCl) to larvae (glochidia) and/or juveniles of a unionid mussel (fatmucket, Lampsilis siliquoidea) and to determine the potential influences of water hardness (50, 100, 200, and 300 mg/L as CaCO3) and other major ions (Ca, K, SO4, or HCO3) on the acute toxicity of NaCl to the mussels. From the KCl test, the 50% effect concentration (EC50) for fatmucket glochidia was 30 mg K/L, similar to or slightly lower than the EC50s for juvenile fatmucket (37–46 mg K/L) tested previously in our laboratory. From the NaCl tests, the EC50s for glochidia increased from 441 to 1597 mg Cl/L and the EC50s for juvenile mussels increased from 911 to 3092 mg Cl/L with increasing water hardness from 50 to 300 mg/L. Increasing K from 0.4 to 1.9 mg/L, SO4 from 13 to 40 mg/L, or HCO3 from 44 to 200 mg/L in the 50 mg/L hardness water did not substantially change the NaCl EC50s for juvenile mussels, whereas increasing Ca from 9.9 to 42 mg/L increased the EC50s by a factor of 2. The overall results indicate that glochidia were equally or more sensitive to NaCl and KCl compared with juvenile mussels and that the increased water hardness ameliorated the acute toxicity of NaCl to glochidia and juveniles. These responses rank fatmucket among the most acutely sensitive freshwater organisms to NaCl and KCl. Environ Toxicol Chem 2018;37:3041–3049. © 2018 SETAC. This article is a US government work and, as such, is in thepublic domain in the United States of America.
The response of cultured meiofaunal and benthic foraminiferal communities to lead exposure: Results from mesocosm experiments
Authors: Frontalini Fabrizio , Semprucci Federica , Di Bella Letizia , Caruso Antonio , Cosentino Claudia , Maccotta Antonella , Scopelliti Giovanna , Sbrocca Claudia , Bucci Carla , Balsamo Maria , Martins Maria Virginia , Armynot du Châtelet Eric , Coccioni Rodolfo
Published: June 2018

Lead (Pb) is regarded as a highly toxic element that poses a serious threat to biota. A mesocosm experiment was performed to assess the influence of Pb on meiofaunal (metazoans within 45–500 μm) and benthic foraminiferal (protozoan) communities. To this end, sediments bearing such communities were incubated in mesocosms, exposed to different levels of Pb in seawater, and monitored for up to 8 wk. Concentrations of Pb <1 ppm in water did not promote a significant increase of this metal in sediments. Relatively high concentrations of Pb seemed to affect meiofaunal and benthic foraminiferal communities by reducing their richness or diversity, and the abundance of the most sensitive taxa. The mesocosm approach can be considered an effective method to document the responses of meiofaunal and benthic foraminiferal communities to various kinds and concentrations of pollutants over time. This approach allows the evaluation of dose–response relationships, validates the outcomes of field studies, and possibly confirms the sediment quality guidelines and thresholds. Environ Toxicol Chem 2018;37:2439–2447. © 2018 SETAC
Nickel toxicity in wood frog tadpoles: Bioaccumulation and sublethal effects on body condition, food consumption, activity, and chemosensory function
Authors: Klemish Jaimie L. , Bogart Sarah J. , Luek Andreas , Lannoo Michael J. , Pyle Greg G.
Published: June 2018

Nickel (Ni) concentrations in aquatic ecosystems can be amplified by anthropogenic activities including resource extraction. Compared with fish and invertebrates, knowledge of Ni toxicity in amphibians is limited, especially for northern species. We examined the effect of Ni on wood frog (Lithobates sylvaticus) tadpoles, the species with the widest and most northern distribution of any anuran in North America. Wood frog tadpoles were exposed to a Ni concentration gradient (0.02–5.5 mg/L of Ni at 164 mg/L as CaCO3 water hardness) for 8 d and examined for lethality, Ni bioaccumulation, and several sublethal endpoints including body condition, food consumption, activity, and chemosensory function. Nickel induced a sublethal effect on body condition (8-d 10 and 20% effect concentrations [EC10 and EC20] of 1.07 ± 0.38 and 2.44 ± 0.51 mg/L of Ni ± standard error [SE], respectively) but not on food consumption, activity, or chemosensory function. Nickel accumulation in tadpole tissues was positively related to an increase in aqueous Ni concentration but was not lethal. Both the acute and chronic US Environmental Protection Agency water quality guideline concentrations for Ni (0.71 and 0.08 mg/L at 164 mg/L as CaCO3 water hardness, respectively) were protective against lethal and sublethal effects in wood frog tadpoles. In the present study, wood frog tadpoles were protected by current water quality guidelines for Ni and are likely not as useful as other taxa for environmental effects monitoring for this particular metal. Environ Toxicol Chem 2018;37:2458–2466. © 2018 SETAC

Abstract

The body condition of wood frog tadpoles decreases with an increase in the accumulation of nickel (Ni) in the whole body.
Development of cardiovascular and neurodevelopmental metrics as sublethal endpoints for the Fish embryo toxicity test
Authors: Krzykwa Julie C. , Olivas Alexis , Sellin Jeffries Marlo K.
Published: June 2018

The fathead minnow fish embryo toxicity (FET) test has been proposed as a more humane alternative to current toxicity testing methods as younger organisms are thought to experience less distress during toxicant exposure. However, the FET test protocol does not include endpoints that allow for the prediction of sublethal adverse outcomes, limiting its utility relative to other test types. Researchers have proposed the development of sublethal endpoints for the FET test to increase its utility. The present study 1) developed methods for previously unmeasured sublethal metrics in fathead minnows (i.e., spontaneous contraction frequency and heart rate) and 2) investigated the responsiveness of several sublethal endpoints related to growth (wet wt, length, and growth-related gene expression), neurodevelopment (spontaneous contraction frequency, eye size, and neurodevelopmental gene expression), and cardiovascular function and development (pericardial area, heart rate, and cardiovascular system–related gene expression) as additional FET test metrics using the model toxicant 3,4-dichloroaniline. Of the growth, neurological, and cardiovascular endpoints measured, length, eye size, and pericardial area were found to be more responsive than the other endpoints evaluated. Future studies linking alterations in these endpoints to longer-term adverse impacts are needed to fully evaluate the predictive power of these metrics in chemical and whole-effluent toxicity testing. Environ Toxicol Chem 2018;37:2530–2541. © 2018 SETAC
Fabrication of peppermint essential oil nanoemulsions by spontaneous method: Effect of preparing conditions on droplet size
Authors: Barzegar Hassan , Mehrnia Mohammad Amin , Nasehi Behzad , Alipour Mohammad
Published: June 2018

Peppermint essential oil is used in food, cosmetics, and pharmaceutical industries. The fabrication of peppermint nanoemulsion can increase its efficiency at lower concentrations. Spontaneous emulsification is a low‐energy method based on the characteristics of the surfactant. Factors affecting the interfacial properties of organic and aqueous phases at the time of mixing can influence the formation and droplet size of emulsions. In this study, nonionic surfactants of Tween 20, Tween 40, and Tween 80 were used to prepare peppermint microemulsions. After selecting an appropriate surfactant, the effect of stirring speed, organic phase temperature, storage for 90 days, and different surfactant‐to‐oil ratios were evaluated to investigate the emulsifying ability of the surfactant under different conditions and concentrations. The results showed that the best microemulsion was formed using Tween 80 with a droplet size of around 50 nm. Varying the surfactant‐to‐oil ratio from 50 to 225%, we found that a nanoemulsion was formed at all concentrations. Moreover, we found that the speed of mixing of organic and aqueous phases and the temperature of the organic phase affects the droplet size. At higher surfactant‐to‐oil ratios, storing the microemulsion for 90 days decreased its droplet size and increased transparency.
Forecasts for leverage heterogeneous autoregressive models with jumps and other covariates
Authors: Choi Ji‐Eun , Shin Dong Wan
Published: June 2018

For leverage heterogeneous autoregressive (LHAR) models with jumps and other covariates, called LHARX models, multistep forecasts are derived. Some optimal properties of forecasts in terms of conditional volatilities are discussed, which tells us to model conditional volatility for return but not for the LHARX regression error and other covariates. Forecast standard errors are constructed for which we need to model conditional volatilities both for return and for LHAR regression error and other blue covariates. The proposed methods are well illustrated by forecast analysis for the realized volatilities of the US stock price indexes: the S&P 500, the NASDAQ, the DJIA, and the RUSSELL indexes.
Novel Concept for Evaporative Cooling of Fuel Cells: an Experimental Study Based on Neutron Imaging
Authors: Cochet M. , Forner‐Cuenca A. , Manzi V. , Siegwart M. , Scheuble D. , Boillat P.
Published: June 2018

Polymer electrolyte fuel cells (PEFC), although a promising technology for carbon free production of electricity, are penalized by system complexity, partly due to cooling and humidifying systems. These systems are necessary to avoid the heating up and drying of the membrane, which stop the electrochemical reaction. Here, we present an evaporative cooling concept for PEFC developed at Paul Scherrer Institute (PSI). Unlike other concepts, our approach does not require any additional layer in the cell structure. Water flows through dedicated anode flowfield channels, parallel to the gas channels, and is distributed over the cell area thanks to a modified gas diffusion layer (GDL). A synthesis method developed at Paul Scherrer Institut (PSI) transforms some portions of the GDL into hydrophilic patterns, which wick the water from the supply channels at low capillary pressure. These hydrophilic areas, parallel and equally spaced, define pathways for liquid water separated from the gases, which avoids flooding. A test cell was built to investigate both water transport with the help of neutron radiography and heat transport thanks to integrated heat flux sensors. Here, we will present how the evaporation can be controlled by the mass flow rates, temperatures, pressures of gases, and the geometry of the hydrophilic lines.
Chinese Natural Gas Market Huge but Beset With Difficulties
Authors: Zhu Zhen
Published: June 2018

China has been a major player in the world energy market.
Effects of offshore oil exploration and development in the Alaskan Beaufort Sea: A three-decade record for sediment metals
Authors: Trefry John H , Neff Jerry M
Published: June 2018

Impacts from oil exploration, development, and production in the Beaufort Sea, Alaska, USA are assessed using concentrations of metals in sediments collected during 2014 to 2015, combined with a large data set for 1985 to 2006. Concentrations of 7 (1980s) or 17 (1999–2015) metals in 423 surface sediments from 134 stations, plus 563 samples from 30 cores were highly variable, primarily as a function of sediment granulometry with naturally greater metals concentrations in fine-grained, Al-rich sediment. Metals versus Al correlation plots were used to normalize metals concentrations and identify values significantly above background. Barium, Cr, Cu, Hg, and Pb concentrations were above background, but variable, within 250 m of some offshore sites where drilling occurred between 1981 and 2001; these areas totaled <6 km2 of 11 000 km2 in the total lease area. Random and fixed sampling along the coastal Beaufort Sea from 1985 to 2015 yielded 40 positive anomalies for metals in surface sediments (∼0.8% of 5082 data points). About 85% of the anomalies were from developed areas. Half the anomalies were for the 5 metals found enhanced near drilling sites. No metals concentrations, except As, exceeded accepted sediment quality criteria. Interannual shifts in metals values for surface sediments at inner shelf sites were common and linked to storm-induced transitions in granulometry; however, metal-to-Al ratios were uniform during these shifts. Sediment cores generally recorded centuries of background values, except for As, Fe, and Mn. These 3 metals were naturally enriched in sediments from deeper water (>100 m) via diagenetic remobilization at sediment depths of 5 to 15 cm, upward diffusion, and precipitation in surface oxic layers. Minimal evidence for anthropogenic inputs of metals, except near some exploratory drilling sites, is consistent with extraction of most oil from land or barrier islands in the Alaskan Arctic and restricted offshore activity to date. Integr Environ Assess Manag 2019;15:209–223. © 2018 SETAC
Qualitative Approach to Comparative Exposure in Alternatives Assessment
Authors: Greggs William , Burns Thomas , Egeghy Peter , Embry Michelle R , Fantke Peter , Gaborek Bonnie , Heine Lauren , Jolliet Olivier , Lee Carolyn , Muir Derek , Plotzke Kathy , Rinkevich Joseph , Sunger Neha , Tanir Jennifer Y , Whittaker Margaret
Published: June 2018

Most alternatives assessments (AAs) published to date are largely hazard-based rankings, thereby ignoring potential differences in human and/or ecosystem exposures; as such, they may not represent a fully informed consideration of the advantages and disadvantages of possible alternatives. Building on the 2014 US National Academy of Sciences recommendations to improve AA decisions by including comparative exposure assessment into AAs, the Health and Environmental Sciences Institute's (HESI) Sustainable Chemical Alternatives Technical Committee, which comprises scientists from academia, industry, government, and nonprofit organizations, developed a qualitative comparative exposure approach. Conducting such a comparison can screen for alternatives that are expected to have a higher or different routes of human or environmental exposure potential, which together with consideration of the hazard assessment, could trigger a higher tiered, more quantitative exposure assessment on the alternatives being considered, minimizing the likelihood of regrettable substitution. This article outlines an approach for including chemical ingredient- and product-related exposure information in a qualitative comparison, including ingredient and product-related parameters. A classification approach was developed for ingredient and product parameters to support comparisons between alternatives as well as a methodology to address exposure parameter relevance and data quality. The ingredient parameters include a range of physicochemical properties that can impact routes and magnitude of exposure, whereas the product parameters include aspects such as product-specific exposure pathways, use information, accessibility, and disposal. Two case studies are used to demonstrate the application of the methodology. Key learnings and future research needs are summarized. Integr Environ Assess Manag 2018;00:000–000. © 2018 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC)
Motorized Equipment Improves Efficiency For Smaller Systems
Authors: Ramey Jesse C.
Published: June 2018

Selection of the proper types of trucks, vans, and emergency vehicles for use in conjunction with the operation and maintenance of hydrants, meters, and other equipment will increase efficiency in small water systems.
‘Examsmanship‘—How to Take a Certification Exam
Authors: Beer Chuck
Published: June 2018

This article gives advice on how to prepare and take Certification Exams, along with suggestions on how to tackle calculation problems. The author also includes a list of recommended text books to study in preparation for a water utility operator exam.
Breakpoint Chlorination—the Chemistry of Chlorine
Authors: Leidholdt Ralph
Published: June 2018

This article is a continuation of “Chlorine‐‐‘Special Agent’ for Disinfecting Water” by Ralph Leidholdt (OpFlow September 1982). In this selection, the author discusses the chemical reactions that occur when chlorine gas, calcium hypochlorite, or sodium hypochlorite is added to water for disinfection purposes. The following chlorine residuals are discussed: hypochlorous acid; hypochlorite ion; monochloramine; dichloramine; and trichloramine. Breakpoint chlorination is also defined and discussed, as well as superchlorination and dechlorination.
Brine Well Provides Salt Needed for Softening
Authors: Valentine Lawrence
Published: June 2018

In 1966, the City of Cuyahoga Falls, Ohio, whose water treatment plant has an average capacity of 6 mgd, used approximately 10 mil lb (4.5 mil kg) of salt, costing $45,000, to regenerate synthetic zeolite for water softening. This article describes the drilling and development of a brine well to be used as a source of the needed salt solution. Technical aspects and development costs of the brine treatment unit are detailed. At current production and use rates, the salt well represents an annual savings of $234,000 per year.
Motion Sensor/Alarm Detects Sweep Arm Stoppage
Authors: Loehr Michael J.
Published: June 2018

This article describes the construction of a motion sensor and alarm to detect stoppage of the sludge collector sweep arms of a clarifier basin.
Main Line Chlorinator Is Easy to Transport and Use
Authors: Wixom Ted
Published: June 2018

The Bolton Point Water System, in Ithaca, New York, serves a rapidly developing area, where several water main extensions go on‐line every year. In order to improve the water main installation procedures, Bolton Point distribution personnel developed a water main chlorination unit. The device operates on pressure from an existing water main. No pumps, generators, or engines are required, making the unit easy to transport and set up. Materials needed to construct the chlorinator and costs involved are presented.
Early Bird Gets Worm, Prevents Frustration
Authors: Stanbery Robert
Published: June 2018

Our system had a problem with some customers who used makeshift shut‐off rods to turn their water service on after it had been shut off for nonpayment. Typically, after we turned off water service due to a seriously overdue bill, the resident would watch our truck leave, then remove the curb stop's buffalo box top, and turn the water back on. After a day or two, we would return, turn the water off again, only to repeat this scenario again and again. We solved this problem by adapting a curb stop lock that allows only water employees to turn the water supply on. This article lists materials and construction information.