bluuebunny/crossref_metadata_2025 huggingface dataset:
The ecological and evolutionary importance of nectar‐secreting galls
Authors: Pierce Mac P.
Published: April 2019

Some species of cynipid wasp engage in mutualisms with ants by producing nectar‐secreting galls, providing carbohydrates, and receiving protection from parasitoids. The galls are functionally similar to extrafloral nectaries, plant structures well known for their role in ant–plant mutualisms. Though not well known, nectar‐secreting galls may have important ecological and evolutionary implications for arthropods, plants, and the evolution of ant‐mutualisms. Here, I review the known ecology of nectar‐secreting galls and speculate on their wider ecological significance based on past research and similar ecological systems. I then develop a conceptual framework for considering the possible historical role of nectar‐secreting galls in the evolution of ant‐mutualisms. I review current knowledge on the origin of ant‐mutualisms and develop a hypothesis for the role of nectar‐secreting galls using examples of similar, contemporary species interactions. Finally, I lay out some of the future directions for research into nectar‐secreting galls and their species interactions, including important questions that remain to be addressed. Future studies of the diversity and ecology of nectar‐secreting galls are necessary to determine the extent to which they may be involved in ecological functioning and the evolution of ant‐mutualisms, and it is hoped that this review will contribute to motivating and developing future research.
Experimentally warmer and drier conditions in an Arctic plant community reveal microclimatic controls on senescence
Authors: Livensperger Carolyn , Steltzer Heidi , Darrouzet‐Nardi Anthony , Sullivan Patrick F. , Wallenstein Matthew , Weintraub Michael N.
Published: April 2019

The timing and duration of the plant growing season and its period of peak activity have shifted globally in response to climate change. These changes alter the period of maximum and potential total carbon uptake, especially in highly seasonal environments such as the Arctic. Earlier plant growth has been observed, and if plant senescence remains the same or is delayed, growing season extension will likely lead to greater carbon uptake and growth. We used phenology data from a multifactor climate change experiment to examine how altered seasonality influences the timing and rate‐of‐senescence and to compare direct observations of individual plant senescence with mathematical models of onset‐of‐senescence based on near‐surface remote sensing. Our three‐year experiment in an Arctic tundra ecosystem altered plant microclimates through factorial warming and earlier snowmelt treatments. We found that (1) early snowmelt and warmer temperatures led to earlier remotely sensed onset‐of‐senescence, but did not alter the rate‐of‐senescence, (2) the timing of color change for individual vascular plants did not change in response to the treatments, leading to a mismatch with remotely sensed phenology, and (3) cumulative, phenologically dependent microclimate metrics (e.g., soil cold degree‐days) best predicted the onset‐of‐senescence. Our study highlights the complexity of observing and understanding controls over phenological shifts that affect plant growth and consequently ecosystem functions. Experimental studies that include multiple approaches to observe and model phenological changes and microclimate are critical to develop phenological forecasting models.
A dryland re‐vegetation in northern China: Success or failure? Quick transitions or long lags?
Authors: Chen Ning , Ratajczak Zak , Yu Kailiang
Published: April 2019

Intensified anthropogenic activities have drastically altered many ecosystems, motivating the use of restoration to regain key ecosystem functions and services and to stem biodiversity losses. Restoration is particularly difficult when human activities have pushed an area into a new state with self‐reinforcing feedbacks. This study investigated a long‐term restoration project in a dryland ecosystem of the Tengger Desert in northwestern China, initiated in 1956. We analyzed shrub and grass cover for 49 yr after the installation of restoration infrastructure that altered external conditions (i.e., using packed straw to reduce wind erosion) and system state (by planting shrubs). After 37–40 yr, the re‐vegetation project was successful in restoring the system to a state similar to native vegetation, with high grass cover (30–50%), low shrub cover (8–10%), and a thick biological soil crust (biocrust). However, the shift to high grass cover did not begin until year 37, before which shrub cover was high (15–20%) and grasses were subdominant (usually <10%). The shift from shrub to grass dominance was abrupt, registering significant nonlinear changes over time and relative to a key driver of vegetation dynamics, estimated biocrust thickness. Biocrust thickness increased gradually over time, which reduced rainfall infiltration into deep soil and thus increased soil moisture available for the shallow‐rooted grasses. The shift from the bare soil state to the steppe state exhibited a long time lag, suggesting that it can take decades to determine whether dryland restoration efforts succeed. The results indicate that persistence might be critical to forcing desired state transitions and that dryland restoration can proceed as a series of time lags, punctuated by abrupt changes in ecosystem state.
Simple measurements in a complex system: soil community responses to nitrogen amendment in a Pinus taeda forest
Authors: Kuske Cheryl R. , Sinsabaugh Robert L. , Gallegos‐Graves La Verne , Albright Michaeline B. N. , Mueller Rebecca , Dunbar John
Published: April 2019

Microorganisms regulate the decomposition of soil organic matter and the flow of plant‐available nutrients. In a temperate pine forest in North Carolina, USA, where nitrogen (N) had been experimentally added for eight years, we combined DNA‐based measures of fungal and bacterial biomass and composition with measures of seven extracellular enzymes (ecoenzymes). These measures were then correlated with soil chemistry. Our goals were to evaluate the relative sensitivity and repeatability of multiple structural and functional measures of community organization to long‐term N deposition. Measurements were conducted at three litter/soil depths, corresponding to the litter, Oa, and mineral A horizons (max depth 10 cm) with ten spatial replicates per experimental plot. Soil chemistry differed significantly with soil depth and N amendment. Total biomass (soil DNA), as well as fungal and bacterial biomass (measured by qPCR), was greatest in the litter horizon and declined significantly with depth. Ecoenzyme activity patterns also changed with soil depth, transitioning from high levels of C, N, and P metabolizing activities in the litter horizon to increased oxidative activities at the lower depth. Under N amendment, soil pH decreased and nitrate concentrations increased in all three soil horizons. Correspondingly, the estimated microbial C use efficiency decreased in N‐amended soils at all depths, despite differences in microbial biomass, community composition, and soil chemistry. Overall, bacterial composition was most responsive to nitrogen amendment, but the taxonomic context of the response varied with soil horizons in conjunction with shifts in soil chemistry and enzyme activities. While a single measure that would incorporate all of the C, N, and P metabolizing activities did not emerge, many measures correlated with each other, and/or with depth and/or N amendment.
Genetic structure of Pinus parviflora on Mt. Fuji in relation to the hoarding behavior of the Japanese nutcracker
Authors: Bekku Yukiko Sakata , Kurokochi Hiroyuki , Matsuki Yu , Nishi Norio , Lian Chunlan
Published: April 2019

Pinus parviflora (Japanese white pine) is distributed along a wide range of altitudes between 1100 and 2500 m above sea level (asl) on the northwestern slope of Mt. Fuji in Japan. The seeds of P. parviflora are presumed to be dispersed from the mountainous area to the timberline by the Japanese nutcracker (Nucifraga caryocatactes var. japonica). We aimed to clarify the effect of the nutcracker on the genetic diversity and structures of P. parviflora populations on Mt. Fuji. Leaf samples were collected from eight populations at altitudes between 1100 and 2500 m asl. Using 11 microsatellite markers, we investigated the genetic diversity and structures of P. parviflora populations on Mt. Fuji. The average expected heterozygosity (HE), allelic richness (Ar), and inbreeding coefficients (FIS) of the P. parviflora populations on Mt. Fuji were 0.66, 1.66, and 0.14, respectively, suggesting a lower genetic diversity in comparison with those of P. parviflora populations in other regions of Japan. The genetic structure of the population at the lowest altitude of 1100 m was significantly different from that of the other populations. However, certain individuals in the populations at higher altitudes (2300–2500 m asl) were likely derived from populations at lower altitudes (1100–1500 m asl), probably because of the hoarding behavior of the nutcracker. Our results indicate that seeds carried from low altitudes by nutcrackers have become established at the timberline and have contributed to expanding the distribution and maintaining the genetic diversity of P. parviflora on Mt. Fuji.
Oxidative Photochlorination of Electron‐Rich Arenes via in situ Bromination
Authors: Düsel Simon Josef Siegfried , König Burkhard
Published: April 2019

Electron‐rich arenes are oxidatively photochlorinated in the presence of catalytic amounts of bromide ions, visible light, and 4CzIPN as organic photoredox catalyst. The substrates are brominated in situ in a first photoredox‐catalyzed oxidation step, followed by a photocatalyzed ipso‐chlorination, yielding the target compounds in high ortho/para regioselectivity. Dioxygen serves as a green and convenient terminal oxidant. The use of aqueous hydrochloric acid as the chloride source reduces the amount of saline by‐products.
Preparation of Nano‐bismuth with Different Particle Sizes and the Size Dependent Electrochemical Thermodynamics
Authors: Wang Mengying , Cui Zixiang , Xue Yongqiang , Yan Aijie , Yu Xing , Song Xinru , Li Hongxing
Published: April 2019

Nano‐bismuth has excellent electrochemical properties. However, it is still unclear how the particle size of nano‐bismuth influences its electrochemical thermodynamic properties. In this paper, spherical bismuth nanoparticles with different particle sizes were prepared by solvothermal method; the electrode potentials, the temperature coefficients of the electrode potentials and the thermodynamic functions of reaction for nano‐bismuth electrodes with different particle sizes at different temperatures were determined; and the effects of particle size on the electrode potential, the temperature coefficient and the thermodynamic functions were discussed. The experimental results show that particle size of bismuth nanoparticles has a significant influences on the electrochemical thermodynamic properties. The standard electrode potential of the nano‐bismuth electrode with a diameter of 39.9 nm was 0.009 V lower than that of the ordinary standard electrode (0.308 V); the temperature coefficient of the electrode potential with a diameter of 39.9 nm was nearly double that of 85.9 nm. With the particle sizes decrease, the standard molar Gibbs energy of reaction, the standard molar enthalpy of reaction, the standard molar entropy of reaction, the molar reversible reaction heat and the temperature coefficient increase; and these quantities are linearly related to the reciprocal of the particle diameter.
Supercritical, Freezing and Thermal Drying Process of Resorcinol‐Formaldehyde Polymer based Nano‐carbons and their Highly Loaded PtRu Anode Electrocatalyst for DMFC
Authors: Bong Sungyool , Han Donghoon
Published: April 2019

The capillary condensation is affected by micropore and nanopore of catalyst layer on fuel cell. Due to limitation of sluggish mass transport and electrocatalytic activity, to retain the pore skeleton of carbon and metal nanoparticles are very significant for enhanced utilizations of pore structure in electrochemical reaction. Besides, thickness of electrocatalyst layer is very crucial due to one of the factor affected by cell performance of direct methanol fuel cell. Highly loaded four Pt−Ru anode catalysts supported on resorcinol‐formaldehyde (RF) polymer based on meso‐porous carbons (80 wt.% Pt−Ru/carbon cryogel, 80 wt.% Pt−Ru/carbon xerogel and 80 wt.% Pt−Ru/carbon aerogel) and conventional carbon (80 wt.% Pt−Ru/Vulcan XC‐72) were prepared by colloidal method for direct methanol fuel cell. These catalysts were characterized by X‐Ray diffraction (XRD), High resolution transmission electron microscopy (HR‐TEM) and X‐ray photoemission (XPS). The results of CO stripping voltammetry, cyclic voltammetry (CV) and single cell test performed on DMFC show that Pt−Ru/carbon cryogel and Pt−Ru/carbon aerogel exhibits better performances in comparison to Pt−Ru/carbon xerogel and Pt−Ru/Vulcan XC‐72. It is thus considered that particle size, oxidation state of metal and electrochemical active surface area of these catalysts are important role in electrocatalytic activity in DMFC.
Single‐gap Microelectrode Functionalized with Single‐walled Carbon Nanotubes and Pbzyme for the Determination of Pb2+
Authors: Wang Hui , Yin Yuan , Gang Liu
Published: April 2019

Lead is a highly toxic metal, which can persist in the natural environment and enrich in biological bodies. It can cause many severe diseases in the human body even at extremely low concentration. Here, we developed a new biosensor using single‐walled carbon nanotubes (SWNTs) modified with a specific Pbzyme (Pbzyme/SWNTs/FET) to detect lead ion (Pb2+), which can monitor the lead pollution. This biosensor used 3‐aminopropyltriethoxysilane to immobilize SWNTs on the area between the source and the drain of single‐gap microelectrode (FET), and the duplex DNA (Pbzyme) consisted of DNAzyme (GR‐5) and complementary DNA (CS‐DNA) was functionalized with the SWNTs’ surface through a peptide bond. The use of GR‐5 DANzyme and Pb2+ to form a stable complex structure to cleave the CS‐DNA can change radically the Pbzyme's structure on the SWNTs’ surface, which will further affect the number of carriers in SNWTs and the conductivity of the Pbzyme/SWNTs/FET. The change in conductivity can be used to evaluate the Pb2+ concentration. Under the optimal conditions, the relative resistances presented a positive correlation with the Pb2+ concentrations, showing a good linear relationship in the range of 10 pM to 50 nM, where the linear regression equation was y=10.104log [CPb]+5.8656, and the detection limit was 7.4 pM. Finally, the biosensor was applied to measure the Pb2+ contents in the soil collected from the forest grass green belt and paint, and the results were compared with the results of atomic fluorescence spectrometry.
Electrochemical Determination of Vitamin B12 Based on Cu2+‐Involved Fenton‐like Reaction
Authors: Kou Yanxia , Lu Jiajia , Jiang Xiangmei , Tian Bowen , Xue Yuanyuan , Wang Meijuan , Tan Liang
Published: April 2019

Poly(thionine) (PTH) film was generated on the electrochemically activated glassy carbon electrode (GCE(ea)) by using the two‐step cyclic voltammetric scan. Scanning electron microscopy, infrared spectral analysis and electrochemical measurement were employed to characterize the modified electrode surface. Hydroxyl radicals, which were produced by the Fenton‐like reaction, could induce the effective oxidization of PTH under near‐neutral condition and cause the notable enhancement of the cathodic peak current (Ipc) during the potential cycling process. Due to the binding of copper ions with the ligands liberated from VB12 and the inferior catalytic ability of Co2+ for the generation of hydroxyl radicals, the addition of VB12 into the Cu2+−H2O2 system inhibited the oxidization of PTH and resulted in the decrease of the Ipc value. The cathodic peak current change was linear with the logarithm of the VB12 concentration in the range of 10 nmol L−1–100 μmol L−1 with a detection limit of 2 nmol L−1 under optimal conditions. The developed sensor displayed excellent analytical performance including high sensitivity, good selectivity, acceptable reproducibility and satisfactory stability. The VB12 content in the injection sample was measured and the recovery values were in the range of 92.0 %–102 %.
Laser‐induced Graphene‐based Non‐enzymatic Sensor for Detection of Hydrogen Peroxide
Authors: Zhang Yuhan , Zhu Huichao , Sun Pin , Sun Chang‐Kai , Huang Hui , Guan Shui , Liu Hailong , Zhang Hangyu , Zhang Chi , Qin Kai‐Rong
Published: April 2019

In this study, a laser‐induced graphene (LIG) loaded platinum nanoparticles (PtNPs) was prepared for precise, rapid and non‐enzymatic electrochemical detection of hydrogen peroxide (H2O2). The commercial PI films were used as the substrate of LIG. In order to improve the electrochemical performance of LIG, a layer of PtNPs catalyst was fabricated through a magnetron sputtering process on the surface of LIG (PtLIG). Under optimized conditions, a linear relationship between H2O2 reduction current and H2O2 concentration was recorded, the correlation coefficient R2 is 0.9919 with the detection limit of 0.1 μM (S/N=3) and the sensitivity of 248.4 μA mM−1cm−2. Moreover, the PtLIG exhibits excellent selectivity, reproducibility and repeatability. Because of these remarkable advantages, we believe that PtLIG will provide a wider range of applications in biosensors and bioelectronic devices.
Electrochemical Sensor for Sensitive Determination of Capsaicin Using Pd Decorated Reduced Graphene Oxide
Authors: Zhong Faqiang , Liu Zhiguang , Han Yujie , Guo Yujing
Published: April 2019

In this work, the reduced graphene oxide functionalized with poly dimethyl diallyl ammonium chloride (PDDA) modified palladium nanoparticles (PDDA‐rGO/Pd) had been facile synthesized and used as the sensing layer for sensitive determination of capsaicin. The prepared composite was characterized by transmission electron microscopy, UV‐visible absorption spectroscopy. The image demonstrated that Pd nanoparticles were uniformly distributed on the graphene surface. The electrochemical properties of the prepared sensor were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the nanocomposite exhibits attractive electrocatalytic activity towards the oxidation of capsaicin. This attributed to the synergistic action of the excellent properties of Pd nanoparticles and graphene nanosheets. Under optimized conditions, the electrochemical sensor possessed a dynamic linear range from 0.32 μM to 64 μM with a detection limit of 0.10 μM (S/N=3) for capsaicin detection. Moreover, the cost‐effective and simple fabrication procedure, good reproducibility and stability as well as acceptable accuracy for capsaicin determination in actual samples are also the main advantages of this method, which might have broad application in other amide alkaloid detection.
Silver Amalgam Tubular Detector Combined with Platinum Auxiliary Electrode for Electrochemical Measurements in Flow Systems
Authors: Josypčuk Oksana , Barek Jiří , Josypčuk Bohdan
Published: April 2019

A new type of tubular detector with platinum auxiliary electrode inside the silver amalgam tube (TD+AuxE) was proposed, fabricated, tested and compared with a typical silver amalgam tubular detector developed earlier. Non‐stop‐flow differential pulse voltammetric anodic stripping method (AS‐DPV) and amperometric method in a glucose oxidase biosensor arrangement were tested. Both detectors were applied for AS‐DPV detection in flow systems for the first time. Solutions of zinc and cadmium cations were used as the testing species for voltammetry, and detection of oxygen concentration was used for amperometry. All these experiments require application of highly negative potentials, which is possible to realize with detectors made of silver solid amalgam. The proposed combination of TD+AuxE provides a much greater current response than the arrangement with three individual electrodes. All relevant parameters were optimized for the developed TD+AuxE. The simple and fast measuring protocol for the determination of the zinc content in commercial food supplement tablets has been developed.
Spectroelectrochemical Sensing: Current Trends and Challenges
Authors: Garoz‐Ruiz Jesus , Perales‐Rondon Juan Victor , Heras Aranzazu , Colina Alvaro
Published: April 2019

Spectroelectrochemistry (SEC) has been used for more than 50 years, but this set of techniques has not been widely used for quantitative analysis. For many years, no commercial instruments were available, which made very difficult to spread the use of SEC. Nowadays, only the creativity of the researchers is required to exploit the capabilities of SEC. This review is written with the aim of showing the potential of SEC, mainly for analytical chemistry. Here, we explain what SEC is, how analytical responses can be obtained, why these techniques are useful for sensors, with a brief description of its advantages in use, and, finally, we try to show the challenges that must be addressed in the next years. SEC can resolve interesting analytical problems using the high amount of data provided by this intrinsic trilinear technique. Given the quantitative analysis point of view of this review, the discussion of the SEC techniques is focused on UV/Vis absorption, photoluminescence and Raman SEC.
Screening of Iberian Coinage in the 2th‐1th BCE Period Using the Voltammetry of Immobilized Particles
Authors: Doménech‐Carbó Antonio , Doménech‐Carbó María Teresa , Álvarez‐Romero Carla , Pasíes Trinidad , Buendía Milagros
Published: April 2019

The voltammetry of immobilized particles (VIMP) was applied for grouping a series of 86 Iberian coins nominally minted in the cities of Iltirta, Cástulo and Obulco in the 2th‐1th BCE period for which there are no chronological data. Using characteristic signatures for the reduction of cuprite, tenorite and lead corrosion products in the patina of the coins, voltammetric grouping of coins was proposed. Voltammetric data were found to be consistent with textural and compositional properties of the surface and subsurface of selected coins using FIB‐FESEM‐EDX. The obtained data confirmed a clear separation between the productions of Iltirta on one side, and those of Cástulo and Obulco on the other side, indicating the possibility to establish a rough chronology for these productions.
Fast‐response Electrochemical Detection of Trinitrotoluene at Sub‐ppb Levels on Nitrogenized Porous Carbon Spheres
Authors: Hao Xi‐Juan , Li Chang‐Ming , Guo Chunxian
Published: April 2019

We present sub‐ppt level detection of explosive trinitrotoluene by constructing a fast‐response electrochemical sensor using nitrogenized porous carbon spheres (NPCS). NPCS with nitrogen doping and amino functionalization accelerates charge transfer and trinitrotoluene accumulation. A high sensitivity of 60.2 μA cm−2 ppb−1 and a detection limit of 0.15 ppb are achieved on NPCS, among the best of recently reported trinitrotoluene electrochemical sensors. Moreover, response time of NPCS is greatly reduced by two times comparing with nitrogen‐free sample. NPCS also offers high selectivity, repeatability and stability, rendering new opportunities to fast detect trinitrotoluene for home security and environment protection.
Evaluation of the Performance of a Mediatorless Microbial Fuel Cell by Electrochemical Impedance Spectroscopy
Authors: Herrero‐Hernandez Eliseo , Greenfield David , Smith Thomas J. , Akid Robert
Published: April 2019

A mediatorless microbial fuel cell was developed using Escherichia coli bacteria and platinised titanium mesh as electrodes, producing a maximum power density of 627 mW m−2. The performance characteristics of the fuel cell were evaluated using both electrochemical and optical techniques. Cyclic Voltammetry showed that an anaerobically grown cell suspension of E. coli was electrochemically active, and is consistent with a role for E. coli‐secreted mediators in the functioning of the cell, after the formation of a biofilm on the surface of the electrode. Electrochemical impedance spectroscopy (EIS) data show a variation in the internal resistance during bacterial growth. EIS analysis based on an equivalent circuit revealed that the initial internal resistance of the cell (5.6 MΩ) initially reduces by around 50 % over an 8 hour period; more or less the same time where the fuel cell reaches its maximum potential of 860 mV, whereupon the resistance begins to increase resulting in the corresponding fall in potential; this trend was reversible upon the introduction of further nutrients into the cell.
Retention prediction using quantitative structure‐retention relationships combined with the hydrophobic subtraction model in reversed‐phase liquid chromatography
Authors: Wen Yabin , Amos Ruth I. J. , Talebi Mohammad , Szucs Roman , Dolan John W. , Pohl Christopher A. , Haddad Paul R.
Published: April 2019

The hydrophobic subtraction model (HSM) combined with quantitative structure‐retention relationships (QSRR) methodology was utilized to predict retention times in reversed‐phase liquid chromatography (RPLC). A selection of new analytes and new RPLC columns that had never been used in the QSRR modeling process were used to verify the proposed approach. This work is designed to facilitate early prediction of co‐elution of analytes in pharmaceutical drug discovery applications where it is advantageous to predict whether impurities might be co‐eluted with the active drug component. The QSRR models were constructed through partial least squares regression combined with a genetic algorithm (GA‐PLS) which was employed as a feature selection method to choose the most informative molecular descriptors calculated using VolSurf+ software. The analyte hydrophobicity coefficient of the HSM was predicted for subsequent calculation of retention. Clustering approaches based on the local compound type and the local second dominant interaction were investigated to select the most appropriate training set of analytes from a larger database. Predicted retention times of five new compounds on five new RPLC C18 columns were compared with their measured retention times with percentage root‐mean‐square errors of 15.4 and 24.7 for the local compound type and local second dominant interaction clustering methods, respectively.
Implementation of at‐line capillary zone electrophoresis for fast and reliable determination of adenovirus concentrations in vaccine manufacturing
Authors: van Tricht Ewoud , Geurink Lars , Galindo Garre Francisca , Schenning Martijn , Backus Harold , Germano Marta , Somsen Govert W. , Sänger – van de Griend Cari E.
Published: April 2019

A CZE method was validated and implemented for fast and accurate in‐process determination of adenovirus concentrations of downstream process samples obtained during manufacturing of adenovirus vector‐based vaccines. An analytical‐quality‐by‐design approach was embraced for method development, method implementation, and method maintenance. CZE provided separation of adenovirus particles from sample matrix components, such as cell debris, residual DNA and proteins. The intermediate precision of the virus particle concentration was 6.9% RSD and the relative bias was 2.3%. In comparison, the CZE method is intended to replace a quantitative polymerase chain reaction method which requires three replicates in three analytical runs to achieve an intermediate precision of 8.1% RSD. Given that, in addition, the time from sampling till reporting results of the CZE method was less than 2 h, whereas quantitative polymerase chain reaction requires 3 days, it follows that the CZE method enables faster processing times in downstream processing.
On the Factors Affecting Aging and Self‐Discharge of Lithium–Sulfur Cells. Effect of Positive Electrode Composition
Authors: Kuzmina Elena , Karaseva Elena , Ivanov Alexey , Kolosnitsyn Vladimir
Published: April 2019

Fast self‐discharge (reversible capacity loss during storage) and aging (irreversible capacity loss during cycling and storage) are important and difficult problems in the development of lithium–sulfur batteries (LSB). Both problems are caused by the solubility of the active materials of the positive electrode in the electrolyte. Processes at the negative and positive electrodes result in self‐discharge and aging of LSB. Sulfur (S) and lithium polysulfides (Li2Sn), dissolved in the electrolyte, interact with the lithium metal electrode, causing the formation of insoluble lithium sulfide (Li2S). The main reasons for irreversible capacity loss are the accumulation of Li2S on the negative electrode and the binding of S and Li2S in the micropores of carbon materials, included in positive electrodes, during prolonged cycling and storage of LSB. Li2S does not accumulate on the lithium electrode during storage of LSB for 120 days. The equilibrium content of Li2S on the lithium electrode is 0.06 mg cm−2. The main reason for the irreversible capacity loss is the binding of sulfur in the pore spaces of the carbon particles. The interaction of sulfur and Li2Sn (n > 4) with metallic lithium, causing the formation of soluble Li2Sn (n ≤ 4), is the reason for a reversible capacity loss.
Capacity Distribution of Large Lithium‐Ion Battery Pouch Cells in Context with Pilot Production Processes
Authors: Hoffmann Louisa , Grathwol Jan-Kirsten , Haselrieder Wolfgang , Leithoff Ruben , Jansen Tobias , Dilger Klaus , Dröder Klaus , Kwade Arno , Kurrat Michael
Published: April 2019

The increasing relevance of automotive lithium‐ion battery cells spotlights the importance of economic production in a high quantity. In this context, production technology for large battery formats is of great relevance. Therefore, it is necessary to identify effects on important cell properties, and based on this, develop an understanding of the interaction between process parameters and product properties. Large‐format cells are not comprehensively examined, particularly, in a large sample size, analyzing cell properties in terms of distributed values. Hence, there is so far no statistical data concerning large‐format batteries and their distributed discharge capacity and self‐discharge. For this reason, and in contrast to other studies, the scope of this work is to investigate a large sample size of 79 industrial‐scale 9 Ah battery cells to ensure statistical relevance and generate distributed data of cell properties. For this purpose, a large number of cells are produced and extensively electrochemically investigated. Subsequently, the essential parameters are correlated with the electrode parameter of carbon black particle size. Hence, the foundation for this process–product–property relationship is laid.
The evaluation of eco‐efficiency of the industrial coupling symbiosis network of the eco‐industrial park in oil and gas resource cities
Authors: Wang Yanqiu , Li Pengtai , Zhu Zhiwei , Liu Zhenbin
Published: April 2019

Eco‐industrial parks (EIPs) is a complex system, composed of a variety of companies with embedded ties. Members in EIPs shape the “Eco‐Industrial Chain Network,” the industrial coupling symbiosis network (ICSN) system, in which businesses cooperate with each other and share the mutual benefits at the same time. In order to study the development levels of the ICSN system in EIPs, this paper uses the grey relational analysis (GRA) method to evaluate the eco‐efficiency of coupling and symbiosis network in EIPs in oil and gas resource‐based cities. The results show that the overall level of eco‐efficiency and the stability of ICSN could be reflected through the application of the economic, environmental, and the dematerialized cycle and network structure relational analysis. Furthermore, it confirms the feasibility and applicability of the evaluation model and the evaluation indicator system.
Techno‐economic analysis of multiservice EPON deployment
Authors: Radivojević Mirjana , Matavulj Petar
Published: April 2019

Deployment of future‐proof access networks requires new infrastructure and new equipment and, on top of it, raises many questions regarding the costs and risks associated with the technology, telecommunications market, and legal regulations of these networks. This paper presents the techno‐economic analysis of single‐channel and multichannel Ethernet passive optical network implementation in different urban environments since urban areas are currently associated with the need for the delivery of more advanced value‐added services. In order to get realistic results, the techno‐economic study has been applied to different urban areas in the city of Belgrade, capital of Serbia. Cost/benefit analysis is performed in order to determine the most influential parameters and give general guidelines for the deployment of new‐generation optical access networks in different environments. Analysis also shows that the price for new services that a customer needs to pay is competitive in the market today.
Essential oil components and cytochrome P450 enzymes: a review
Authors: Zehetner Petra , Höferl Martina , Buchbauer Gerhard
Published: April 2019

Phase‐I metabolism mediated by cytochrome P450 (CYP) enzymes represents a major route of elimination of many drugs that can compete for the same CYP enzyme. The bioactivity of essential oils (EOs) and their flavour and fragrance constituents have been known since ancient times, and like any other physiological process in the human body the activity of CYP enzymes can also be influenced (increased and/or decreased) by these natural compounds. This review discusses the effects of EO constituents on important drug‐metabolizing CYP enzymes. Exposure to EO constituents through commonly used products via cutaneous, oral, and inhalation routes is outlined, and the impact of some important EO constituents on CYP enzymes is described in more detail. In particular, the simultaneous application of EO constituents with drugs or the excessive use of EOs and their constituents can lead to unexpected adverse effects.
Multifidelity approaches for uncertainty quantification
Authors: Biehler Jonas , Mäck Markus , Nitzler Jonas , Hanss Michael , Koutsourelakis Phaedon‐Stelios , Wall Wolfgang A.
Published: April 2019

The aim of this paper is to give an overview of different multifidelity uncertainty quantification (UQ) schemes. Therefore, different views on multifidelity UQ approaches from a frequentist, Bayesian, and possibilistic perspective are provided and recent developments are discussed. Differences as well as similarities between the methods are highlighted and strategies to construct low‐fidelity models are explained. In addition, two state‐of‐the‐art examples to showcase the capabilities of these methods and the tremendous reduction of computational costs that can be achieved when using these approaches are provided.
Glutamatergic signaling between neurons and oligodendrocyte lineage cells: Is it synaptic or non‐synaptic?
Authors: Kula Bartosz , Chen Ting‐Jiun , Kukley Maria
Published: April 2019

Fast chemical synaptic transmission is a major form of neuronal communication in the nervous system of mammals. Another important, but very different, form of intercellular communication is volume transmission, which is a slower non‐synaptic signaling. The amino acid glutamate is the most abundant excitatory neurotransmitter in the nervous system, which mediates both synaptic and non‐synaptic signaling via ionotropic and metabotropic glutamate receptors. Intriguingly, neurons establish glutamatergic synapses also with oligodendrocyte precursor cells (NG2+‐glia). Moreover, neuronal activity and glutamate receptors play an important role in the development and functionality of oligodendrocytes and their precursors in vivo. Yet, molecular characteristics and functional significance of neuron–glia synapses remain poorly understood, and it is unclear how glutamate receptors mediate the effects of neuronal activity on the oligodendrocyte lineage cells. In this review, we discuss what is known with regard to synaptic and non‐synaptic glutamatergic signaling between neurons and oligodendrocyte lineage cells, what can be suggested based on the current state of knowledge, and what is fully unknown and requires new research.
The costs of dementia in England
Authors: Wittenberg Raphael , Knapp Martin , Hu Bo , Comas‐Herrera Adelina , King Derek , Rehill Amritpal , Shi Cheng , Banerjee Sube , Patel Anita , Jagger Carol , Kingston Andrew
Published: April 2019

Objectives

This study measures the average per person and annual total costs of dementia in England in 2015.

Methods/Design

Up‐to‐date data for England were drawn from multiple sources to identify prevalence of dementia by severity, patterns of health and social care service utilisation and their unit costs, levels of unpaid care and its economic impacts, and other costs of dementia. These data were used in a refined macrosimulation model to estimate annual per‐person and aggregate costs of dementia.

Results

There are around 690 000 people with dementia in England, of whom 565 000 receive unpaid care or community care or live in a care home. Total annual cost of dementia in England is estimated to be £24.2 billion in 2015, of which 42% (£10.1 billion) is attributable to unpaid care. Social care costs (£10.2 billion) are three times larger than health care costs (£3.8 billion). £6.2 billion of the total social care costs are met by users themselves and their families, with £4.0 billion (39.4%) funded by government. Total annual costs of mild, moderate, and severe dementia are £3.2 billion, £6.9 billion, and £14.1 billion, respectively. Average costs of mild, moderate, and severe dementia are £24 400, £27 450, and £46 050, respectively, per person per year.

Conclusions

Dementia has huge economic impacts on people living with the illness, their carers, and society as a whole. Better support for people with dementia and their carers, as well as fair and efficient financing of social care services, are essential to address the current and future challenges of dementia.
Solving the dual Russian option problem by using change‐of‐measure arguments
Authors: Gapeev Pavel V.
Published: April 2019

We apply the change‐of‐measure arguments of Shepp and Shiryaev (Theory of Probability and its Applications, 1994, 39, 103–119) to study the dual Russian option pricing problem proposed by Shepp and Shiryaev (Probability Theory and Mathematical Statistics: Lectures presented at the semester held in St. Peterburg, Russia, March 2 April 23, 1993, Amsterdam, the Netherlands: Gordon and Breach, 1996, pp. 209–218) as an optimal stopping problem for a one‐dimensional diffusion process with reflection. We recall the solution to the associated free‐boundary problem and give a solution to the resulting one‐dimensional optimal stopping problem by using the martingale approach of Beibel and Lerche (Statistica Sinica, 1997, 7, 93–108) and (Theory of Probability and its Applications, 2000, 45, 657–669).
Is coworker feedback more important than supervisor feedback for increasing innovative behavior?
Authors: Eva Nathan , Meacham Hannah , Newman Alexander , Schwarz Gary , Tham Tse Leng
Published: April 2019

A growing body of research explores human resource management practices that encourage employees to innovate. In this study, we examine the links between different sources of feedback (supervisor and coworker) and employees’ innovative behavior. Drawing on social exchange theory and the job demands‐resources theory, we first propose that work engagement and psychological contract breach mediate the relationship between supervisor feedback and employees’ innovative behavior. Second, we propose a moderated mediation model in which coworker feedback attenuates the relationships between supervisor feedback and employees’ innovative behavior through the mediating mechanisms of both work engagement and psychological contract breach. Using three waves of multisource data from 300 Chinese employees and their 64 supervisors, we found a dual‐mediation pathway by which employees’ work engagement and perceptions of psychological contract breach mediate the influence of supervisor feedback on innovative behavior. Our results also show that coworker feedback can be used to supplement the lack of supervisor feedback when required. Organizations are advised to ensure that employees obtain regular feedback from multiple sources because such feedback can promote employees’ work engagement and perceptions that the organization is upholding its side of the psychological contract, which fosters employees’ innovative behavior.
Experimental and numerical study of forced convection heat transfer in different internally ribbed tubes configuration using TiO2 nanofluid
Authors: Al Kumait Aadel A. R. , Ibrahim Thamir K. , Abdullah Maysoon A.
Published: April 2019

TiO2/water nanofluid is used together with a ribbed tube for heat transfer augmentation. This paper presents an experimental and numerical investigation to study the influence of the ribs' pitch distance and ribbed tube configuration on heat transfer using TiO
2 nanofluid in a turbulent regime with Reynolds numbers of 5000‐40 000. Meanwhile, the fluid properties are assumed to be constant with temperature under uniform heat flux. The average nanoparticle size is 50 nm and volume fractions of 0% to 1% are adopted. The study is accomplished by using the finite volume method, and its objective involves finding a low friction factor and high heat transfer enhancement in the presence of TiO
2/water nanofluids. In comparison with the plain tube, a helical ribbed tube provides higher performance evaluation criteria (about 2.0%), while circumferentially ribbed tube provides 1.9% and longitudinal ribbed tube provides 1.88%. The helical ribbed tubes with a 5.89 mm pitch distance gave higher turbulent kinetic energy due to a stronger swirl intensity, resulting in a thinner thermal boundary layer and a higher Nusselt number with uniform distribution. The nonlinear models of friction factor and Nusselt number have been predicted with a maximum deviation of ±3% and ±2%, respectively.
Numerical investigation of semiempirical relations representing the local Nusselt number magnitude of a pin fin heat sink
Authors: Siddique Umair M. , Nitin Gulhane P. , Khan Sher A. , Taler Jan , Cebula Arthur , Oclon Pawel , Patil Rajesh
Published: April 2019

Heat transfer augmentation study using air jet impingement has recently attained great interest toward electronic packaging systems and material processing industries. The present study aims at developing a nondimensional semiempirical relation, which represents the cooling rate (Nu) in terms of different geometric and impinging parameters. The spacing of the fin (S/dp) and the fin heights (H/dp) are the geometric parameters, while the impinging Reynolds number (Re) and nozzle‐target spacing (Z/d) are the impinging parameters. During the plot of the Nusselt profile, three vital secondary peaks are observed due to local turbulence of air over the heat sink. To incorporate this nonlinear behavior of the Nusselt profile in developing nondimensional empirical relations, the Nusselt profiles are divided into different regions of secondary rise and fall. Four different sets of the semiempirical relation using regression analysis are proposed for Z/d ≤ 6, H/dp ≤ 4.8 with S/dp ≤ 1.58, S/dp > 1.58 and for Z/d > 6, H/dp > 4.8 with S/dp ≤ 1.58, S/dp > 1.58. These empirical relations benefit the evaluation of the cooling rate (Nu) without any experimentation or simulation.
Pooled frequency analysis for intensity–duration–frequency curve estimation
Authors: Requena Ana I. , Burn Donald H. , Coulibaly Paulin
Published: April 2019

Rainfall intensity–duration–frequency (IDF) curves are used in the design of urban infrastructure. Their estimation is based on rainfall frequency analysis, usually performed on rainfall records from a single gauged station. However, available at‐site record length is often too short to provide accurate estimates for long return periods. In the present study, a general framework for pooled rainfall frequency analysis based on the index‐event model is proposed for IDF estimation at gauged stations. Pooling group formation is defined by the region of influence approach on the basis of the geographical distance similarity measure. Several pooled approaches are defined and evaluated by a procedure through which quantile estimation and uncertainty are assessed. Alternate approaches for the definition of a pooling group are based on different criteria regarding initial pooling group size (and the relationship between size and return period), approaches for assessing pooling group homogeneity, and the use of macroregions in pooling group formation. The proposed framework is applied to identify the preferred approach for pooled rainfall intensity frequency analysis in Canada. Pooled approaches are found to provide more precise estimates than the at‐site approach, especially for long return periods. Pooled parent distribution selection supported the use of the generalized extreme value distribution across the country. Recommendations for pooling group formation include increasing the pooling group size with increases in return period and identifying an appropriate trade‐off between pooling group homogeneity and size for long return periods.
Patterns in metabolite profile are associated with risk of more aggressive prostate cancer: A prospective study of 3,057 matched case–control sets from EPIC
Authors: Schmidt Julie A. , Fensom Georgina K. , Rinaldi Sabina , Scalbert Augustin , Appleby Paul N. , Achaintre David , Gicquiau Audrey , Gunter Marc J. , Ferrari Pietro , Kaaks Rudolf , Kühn Tilman , Boeing Heiner , Trichopoulou Antonia , Karakatsani Anna , Peppa Eleni , Palli Domenico , Sieri Sabina , Tumino Rosario , Bueno‐de‐Mesquita Bas , Agudo Antonio , Sánchez Maria‐Jose , Chirlaque María‐Dolores , Ardanaz Eva , Larrañaga Nerea , Perez‐Cornago Aurora , Assi Nada , Riboli Elio , Tsilidis Konstantinos K. , Key Timothy J. , Travis Ruth C.
Published: April 2019

Metabolomics may reveal novel insights into the etiology of prostate cancer, for which few risk factors are established. We investigated the association between patterns in baseline plasma metabolite profile and subsequent prostate cancer risk, using data from 3,057 matched case–control sets from the European Prospective Investigation into Cancer and Nutrition (EPIC). We measured 119 metabolite concentrations in plasma samples, collected on average 9.4 years before diagnosis, by mass spectrometry (AbsoluteIDQ p180 Kit, Biocrates Life Sciences AG). Metabolite patterns were identified using treelet transform, a statistical method for identification of groups of correlated metabolites. Associations of metabolite patterns with prostate cancer risk (OR1SD) were estimated by conditional logistic regression. Supplementary analyses were conducted for metabolite patterns derived using principal component analysis and for individual metabolites. Men with metabolite profiles characterized by higher concentrations of either phosphatidylcholines or hydroxysphingomyelins (OR1SD = 0.77, 95% confidence interval 0.66–0.89), acylcarnitines C18:1 and C18:2, glutamate, ornithine and taurine (OR1SD = 0.72, 0.57–0.90), or lysophosphatidylcholines (OR1SD = 0.81, 0.69–0.95) had lower risk of advanced stage prostate cancer at diagnosis, with no evidence of heterogeneity by follow‐up time. Similar associations were observed for the two former patterns with aggressive disease risk (the more aggressive subset of advanced stage), while the latter pattern was inversely related to risk of prostate cancer death (OR1SD = 0.77, 0.61–0.96). No associations were observed for prostate cancer overall or less aggressive tumor subtypes. In conclusion, metabolite patterns may be related to lower risk of more aggressive prostate tumors and prostate cancer death, and might be relevant to etiology of advanced stage prostate cancer.