bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractIntensified 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

AbstractMicroorganisms 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

AbstractPinus 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.
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

AbstractNano‐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

AbstractThe 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

AbstractLead 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

AbstractPoly(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

AbstractIn 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

AbstractIn 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

AbstractA 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

AbstractSpectroelectrochemistry (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

AbstractThe 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

AbstractWe 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

AbstractA 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

AbstractThe 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

AbstractA 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.