bluuebunny/crossref_metadata_2025 huggingface dataset:
Zero‐voltage soft‐switching DC–DC converter‐based charger for LV battery in hybrid electric vehicles
Authors: Sayed Khairy
Published: June 2019

This study presents the implementation of a DC‐DC power converter for battery charging from 200 V lithium‐ion or nickel metal hydride (NiMH) battery to lead‐acid battery (typically 12 V) utilised in hybrid vehicles such as Toyota Prius. For hybrid car, a low‐voltage (LV) battery is utilised to power air conditioner, main lights, and different actuators in engine controlling unit etc. The LV battery is usually recharged by car alternator. For the sake of improving fuel efficiency, it is important to regulate charging by using the charging control scheme, where the battery charging is implemented in deceleration interval avoiding the acceleration interval of the car. The hybrid car is equipped with a high‐voltage (HV) NiMH battery. The lead‐acid LV battery is charged from the HV storage battery. The advantage of this charging method is recognised not only to replace the alternator from the car, but also to make efficient braking touching for the car driver, because the regenerative breaking recovered energy can be totally absorbed in the main HV battery. Moreover, the overall efficiency could be easily improved because the total efficiency of charging DC‐DC circuit is greater than that of the car alternator.
Control delay compensation scheme based on non‐instantaneous loading and pulse‐width equivalence for active damping of LCL‐type inverters
Authors: Zhu Kunlong , Sun Pengju , Wang Lin , Zhou Luowei , Du Xiong
Published: June 2019

Active damping (generally by the feedback of capacitor current) is an effective solution to the resonance peak of LCL‐type grid‐connected inverters. However, the damping performance is significantly affected by the computation and pulse‐width modulation delays in the digital control system, which results in poor system robustness. Moreover, the phase lag would be introduced by these control delays, leading to the constrained bandwidth and low‐frequency gain of control loop. In this study, a novel compensation method based on non‐instantaneous loading and pulse‐width equivalence is proposed to completely eliminate the computation delay without any reliability problem. Moreover, compared to the traditional strategies, the proposal can be extended to most two‐level converters because of its simplicity. Finally, the validity of the proposed method is confirmed by the experimental results from a 3 kW single‐phase grid‐connected inverter with an LCL filter.
A two‐stage stochastic optimisation model for the water value calculation in a hybrid diesel/wind/pumped‐storage power system
Authors: Fernández‐Muñoz Daniel , Pérez‐Díaz Juan I. , Chazarra Manuel
Published: June 2019

This study presents a two‐stage stochastic linear programming (LP) model to calculate the water value in an isolated hybrid diesel/wind/pumped‐storage power system with high wind power penetration and with a closed‐loop pumped‐storage power plant (i.e. there is no natural inflows in the upper pond), that takes into account in an approximate manner that the start‐up cost of the diesel units depends on the time passed since the previous shut‐down. The proposed model is applied in the power system of El Hierro island in the Canary Archipelago. The water values provided by the proposed model have been used as input for the day‐ahead generation scheduling. The results obtained in the study indicate that the day‐ahead generation schedule obtained when using the water values provided by the proposed model is similar to the one obtained when using the water values provided by a detailed mixed integer LP (MILP) model. The computational time required to obtain the water value with the proposed model is several orders of magnitude lower than the one needed to solve the MILP model.
Influence of static and dynamic rotor/stator misalignments in axial flux magnetically geared machines
Authors: Hamad Khatab Mohammed F. , Zhu Zi‐Qiang , Li Huayang , Liu Yue
Published: June 2019

Here, static and dynamic (rotating) misalignments between the low‐speed rotor (LSR) and the stator of axial flux magnetically geared machines are studied with the aid of 3‐D finite element analysis (FEA). The influence of rotor/stator axis misalignments on machine performance in terms of cogging torque, air‐gap flux density, and back‐EMF is investigated with reference to the fully healthy condition. The results show that the LSR and HSR cogging torques are significantly affected by such misalignments due to distorted air‐gap flux density. However, the amplitude and the harmonics of the back‐EMF are only slightly changed. Furthermore, the influence of the misalignments on the machine torque performance is investigated. It is shown that the machine torque is significantly reduced when the LSR axis is misaligned with the axis of the stator. Thus, it is concluded that the torque performance of axial flux magnetically geared machines significantly deteriorates under static and dynamic axis misalignments. In addition, the two types of misalignments have similar effects on machine performance.
Dusty disk winds at the sublimation rim of the highly inclined, low mass young stellar object SU Aurigae
Authors: Labdon Aaron , Kraus Stefan , Davies Claire L. , Kreplin Alexander , Kluska Jacques , Harries Tim J. , Monnier John D. , ten Brummelaar Theo , Baron Fabien , Millan-Gabet Rafael , Kloppenborg Brian , Eisner Joshua , Sturmann Judit , Sturmann Laszlo
Published: June 2019

Context. T Tauri stars are low-mass young stars whose disks provide the setting for planet formation. Despite this, their structure is poorly understood. We present new infrared interferometric observations of the SU Aurigae circumstellar environment that offer resolution that is three times higher and a better baseline position angle coverage than previous observations.

Aims. We aim to investigate the characteristics of the circumstellar material around SU Aur, constrain the disk geometry, composition and inner dust rim structure.

Methods. The CHARA array offers unique opportunities for long baseline observations, with baselines up to 331 m. Using the CLIMB three-telescope combiner in the K-band allows us to measure visibilities as well as closure phase. We undertook image reconstruction for model-independent analysis, and fitted geometric models such as Gaussian and ring distributions. Additionally, the fitting of radiative transfer models constrain the physical parameters of the disk. For the first time, a dusty disk wind is introduced to the radiative transfer code TORUS to model protoplanetary disks. Our implementation is motivated by theoretical models of dusty disk winds, where magnetic field lines drive dust above the disk plane close to the sublimation zone.

Results. Image reconstruction reveals an inclined disk with slight asymmetry along its minor-axis, likely due to inclination effects obscuring the inner disk rim through absorption of incident star light on the near-side and thermal re-emission and scattering of the far-side. Geometric modelling of a skewed ring finds the inner rim at 0.17 ± 0.02 au with an inclination of 50.9 ± 1.0° and minor axis position angle 60.8 ± 1.2°. Radiative transfer modelling shows a flared disk with an inner radius at 0.18 au which implies a grain size of 0.4 μm assuming astronomical silicates and a scale height of 15.0 at 100 au. Among the tested radiative transfer models, only the dusty disk wind successfully accounts for the K-band excess by introducing dust above the mid-plane.
Chemical composition and formation conditions of NaHCO3 type of waters in the eastern Transbaikalia
Authors: Borzenko Svetlana , Drebot Valeriia , Fedorov Igor
Published: June 2019

The chemical composition of the supergene zone groundwater in the Eastern Transbaikalia is considered. The main geochemical processes for steppe landscapes are identified and determined the causes of some component’s concentrations in groundwater. To understand the formation conditions of NaHCO3 water, were calculated equilibria of this water with the main minerals of the region’s rocks.
Bacterial diversity and community structure in nitrate-contaminated shallow groundwater in the Poyang Lake basin, China
Authors: Dong Yihui , Li Jiale , Sun Zhanxue , Soldatova Evgeniya , Zan Jinjing
Published: June 2019

The Poyang Lake basin in the Jiangxi province of China has been exposed to nitrate pollution caused by irrigation practices, leading to high groundwater nitrate concentration. Eight groundwater samples were collected from shallow wells for hydrochemical, bacterial diversity, and community structure analysis in November 2017. Shallow groundwaters of the basin are weakly acid and in an oxidizing state, with EC ranging from 87.6 to 279.5 µS/cm and TDS varying between 53 to 344 mg/L and averaging of 164 mg/L. The NO3-N form is the dominant nitrogen species in groundwater, with сoncentrations of NO3-N, NO2-N and NH4-N ranging between 2.5 to 164 mg/L, 0.01 to 0.10 mg/L, <0.01 to 0.08 mg/L, respectively. Groundwater communities are dominated by actinobacteria, alphaproteobacterial, gammaproteobacteria and betaproteobacteria both in high- and low-nitrate groundwaters. The results of a 16S rRNA gene clone library indicate that the bacterial community structure of the high-nitrate groundwater is different from that of the low-nitrate groundwater. The bacterial populations Denitratisoma and Sulfuritalea detected in low-nitrate groundwater suggest that these bacteria are capable of denitrification in anaerobic groundwater environment. Bacterial populations Flavobacteria and Cytophagia in high-nitrate groundwater are common in the s wetlands examined and likely capable of nitrification.
Silicon in ultrafresh groundwater: a case study of the Imandra Lake catchment, The Kola Peninsula
Authors: Guseva Natalia V. , Kopylova Yuliya G. , Vorobeva Daria A , Khvashchevskaya Albina A. , Evtyugina Zinaida A.
Published: June 2019

The ultrafresh groundwater (with TDS values less than 200 mg/L) of the Imandra Lake catchment, Kola Peninsula, is from an intensive water exchange zone, where the water has a short period of contact with the rock. Therefore, the considered water is at the initial stages of the water–rock interaction. The water is saturated with respect to oxides and hydroxides of aluminium and iron. In the groundwater of the Imandra Lake catchment area, the silicon concentrations significantly exceed the concentrations of magnesium and especially potassium. Nevertheless, water is undersaturated with respect to with respect to silicon oxides. The shown enrichment of water with cations is explained by time of water-rock interaction.
Geochemical barriers as a form of self-organization of geochemical systems (case of study Kerch Peninsula, Russia)
Authors: Khaustov Aleksandr , Redina Margarita , Yakovleva Eugeniya
Published: June 2019

According to the author's concept, discharge of groundwater to the surface is considered as a sharp change of geochemical conditions, leading to the formation of geochemical barriers (GCB). In the article presented results of geochemical study of groundwater-soil-organic matter-gas interaction as example of Kerch Peninsula self-organizing system The geochemical barriers give rise to the formation of a kind of non-equilibrium geoecosystems with an individual structure of direct and inverse connections between the components, size and borders of geochemical systems (GCS) are determined by many factors: frequency and scale of discharge, chemical composition, temperature of the source and of the environment, phase transitions within the system with interacting heterogeneous media: "water – rocks", "water – atmosphere", "water – ice", "water – soil", "water – plants (including algae and other living organisms)", and etc. Polycyclic aromatic hydrocarbons (PAHs) are used as tracers of this interaction.
Principal Conditions and Geochemical Trends in Formation of High-grade Bauxite Deposits, Republic of Guinea
Authors: Mamedov Vladimir , Chausov Alexey , Makarova Marina
Published: June 2019

Conditions and principal geochemical trends in the formation of bauxite-bearing lateritic mantles are considered on the example of Fouta Djalon-Mandingo Bauxite-bearing Province as the best natural model. Input and output dynamics of petrogenic components was calculated on the isovolumetric base and the obtained data were used to interpret the zoned structure of weathered profile as resulting from its hydrogeological and gas regimes. Although Al separates from Fe in the formation of bauxite horizon, three-valence iron is a typomorphic element of the lateritic landscape as a whole, with 50% Al leaching from lateritic mantle.
Escape of Supercritical-CO2 Fluids Trapped in Calcite Nano-metric Pores
Authors: Zuddas Pierpaolo , Salvi Stefano , Lopez Olivier , De Giudici Giovanni , Censi Paolo
Published: June 2019

Flow of supercritical CO2-bearing fluids through a rock is a fundamental phenomenon which acts upon a great many geological processes ranging from seismic activity to formation of ore deposits. Atomic Force Microscopy scanning experiments allowed us to infer movement of supercritical CO2-bearing fluids through calcite crystals and relate it to natural decrepitation of nanoscale fluid inclusions. Calculated velocities exceed the rate of diffusion predicated via current vacancy models by several orders of magnitude implying that CO2-rich fluid movement through micro and nano-pore space may presently be greatly underestimated.
Distribution of arsenite-oxidizing bacteria and its correlation with environmental factors in geothermal areas of Tengchong, Yunnan, China
Authors: Li Ping , Jiang Dawei , Jiang Zhou
Published: June 2019

Arsenic (As) is an ubiquitous constituent in geothermal water. Arsenite (AsIII) is oxidized via microbial processes as the waters equilibrate with oxygen in the geothermal effluent. The distribution of arsenite oxdizing bacteria and its correlation with environment factors were studied in Tengchong geothermal areas of Yunnan, China. A total of 230aioA clone sequences were obtained and these sequences were affiliated with four phyla:Betaproteobacteria,Alphaproteobacteria,Deinococcus-ThermusandAquificae. Temperature was negatively correlated withaioA diversity and was the only environment factor that had correlation with diversity index.Betaproteobacteriawas mainly distributed in low temperature (T = 28 to 43 °C) and circumneutral or light alkaline (pH = 7 to 9) springs;Alphaproteobacteriawas mainly predominant in low pH (pH = 3.3 to 3.6) springs;Deinococcus-ThermusandAquificaemainly inhabited in high temperature (T=55 to 78 °C) springs with a wide range of pH. Usually,Deinococcus-Thermuswas dominant when springs had a pH within 4.0 to 8.0.Aquificaewas dominated in springs with pH > 8.0 or pH < 4.0.
Geochemical interactions between hydraulic fracturing fluid and fractured Whitby Mudstone
Authors: Kaszuba John , Houben Maartje E. , Hangx Suzanne J.T.
Published: June 2019

We examine how a mechanically-induced fracture network may influence geochemical reaction between shale and stimulation fluid used in hydraulic fracturing. Two different types of bedding-parallel fractures, a simple fracture between bedding planes and a damage zone with multiple fractures, were induced in the Whitby Mudstone (Early Jurassic) from the UK. Both fractured shales were subsequently reacted with stimulation fluid at 10 MPa and 100°C for about 2000 hours. pH increased from 2.1 to about 6 after 1000 hours of reaction in both shales, but pH increased slightly more rapidly by reaction in the shale with the damage zone. Total dissolved inorganic carbon evolved in similar fashion in both experiments and did not readily distinguish between the two styles of fracturing induced in the Whitby Mudstone.
Absence of solid solution between Fe(II) and Mg(II) hydroxides and consequences on formation of fougerite and smectites
Authors: Bourrié Guilhem , Ben Nacib Jihaine , Ona-Nguema Georges , Trolard Fabienne
Published: June 2019

As there exists extended solid solutions between ferrous and magnesian silicates, experiments were conducted to check if ferrous and magnesian hydroxides can co-precipitate in a solid solution. Results show that no solid solution forms and instead Fe(II) and Mg(II) hydroxides precipitate separately with the same solubilities as pure components. However, in fougerite, F(III), Fe(II) and Mg(II) coexist in a brucitic type hydroxide, with an extended solid solution. This implies that fougerite formation results from Fe(III) precipitation, Fe(III) being surrounded by divalent Fe(II) and Mg(II) to comply with the exclusion rule: Fe(III) ions cannot be direct neighbours. Consequently, Fe(III) - Fe(II) - Mg(II) smectites cannot form by oxidation of a ferrous magnesian brucitic layer, but by silication of fougerite. The impossibility of formation of a solid solution between Fe(II) hydroxide and Mg(II) hydroxide, while their electric charge and ionic radii are identical can be explained by the differences of electronegativities of the elements. Fe(II) and Mg(II) can dimerize separately in aqueous solution, but an heterodimer cannot form.
Trace element mobility during CO2storage: application of reactive transport modelling
Authors: Kirste Dirk , Pearce Julie K. , Golding Sue D. , Dawson Grant K.W.
Published: June 2019

The geologic storage of CO2carries both physical and chemical risks to the environment. In order to reduce those risks, it is necessary to provide predictive capabilities for impacts so that strategies can be developed to monitor, identify and mitigate potential problems. One area of concern is related to water quality both in the reservoir and in overlying aquifers. In this study we report the critical steps required to develop chemically constrained reactive transport models (RTM) that can be used to address risk assessment associated with water quality. The data required to produce the RTM includes identifying the individual hydrostratigraphic units and defining the mineral and chemical composition to sufficient detail for the modelling. This includes detailed mineralogy, bulk chemical composition, reactive mineral phase chemical composition and the identification of the occurrence and mechanisms of mobilisation of any trace elements of interest. Once the required detail is achieved the next step involves conducting experiments to determine the evolution of water chemistry as reaction proceeds preferably under varying elevated CO2fugacities with and without impurities. Geochemical modelling of the experiments is then used for characterising the reaction pathways of the different hydrostratigraphic units. The resultant geochemical model inputs can then be used to develop the chemical components of a reactive transport model.
Thermodynamic Simulation of Essentuki Type Mineral Water Formation
Authors: Limantseva Oxana A. , Potapov E.G.
Published: June 2019

Thermodynamic models of Essentuki and Nagutsky fields of Caucasian Mineral Waters deposits (KMW) are developed. The models are based on laboratory studies of core samples of aptian-albian lower Cretaceous rock dissolution. The rock samples were disintegrated up to 0.25 mm grains. The rock grains were mixed with distilled or mineral waters and the mixtures were kept at 20-25°С and 65-70°С, carbon dioxide pressure of 4.04 MPa. The results of experimental and thermodynamic modeling are showed that aqueous solution composition formed, in particular, microcomponent concentrations, depends on the rock cement composition (clayey, calcic, siliceous, ferriferous, chloritic, zeolitic phosfatic, sulfatic or mixed) and on the percentage of the microelement mineral-bearing in the water-bearing rock. Also the aqueous solution composition depends on temperature and CO2 partial pressure in the silt - rain water CO2 system. Thermodynamic modeling of the system confirmed gypsum dominant role in sulfate type water formation against pyrite role.
Factors that influence the spatial distribution of heavy metals in soil of the Yutian County, Xinjiang, China
Authors: Chen Yunfei , Zhou Jinlong , Zhou Yinzhu , Zeng Yanyan , Sun Ying
Published: June 2019

In this study, 1165 surface soil samples for heavy metal analysis were collected in the Yutian County, Xinjiang, China. The factors that influence the spatial distribution of heavy metal elements in soils in the study area were analyzed by means of multivariate statistical analysis, geostatistics, spatial autocorrelation, spatial analysis and GIS technology. Results show that among 1165 soil samples, three of which had As contents greater than the risk screening values. The theoretical models for variation function of Cd and Pb were exponential model, while the theoretical models for variation function of Hg, As, Cr, Cu, Ni and Zn were spherical model. Nugget value of Cd was less than 25%, indicated a relatively strong spatial correlation. Nugget value of other elements ranged between 25% and 50%, indicated significant spatial correlations. The spatial autocorrelation Moran's I index of soil heavy metal contents in the Yutian County was greater than 0. There was a positive spatial correlation distribution in the county scale. The spatial distribution of soil heavy metal contents in the Yutian County showed a general decreasing trend from the center of the study area to surrounding areas. Distribution of soil heavy metal contents in the Yutian County varied in different parent materials, soil types and land use patterns. Hg, As, Pb, Cr, Cu, Ni and Zn in soil derived from the same source, contents of which were affected by soil texture.
How to integrate ground-truth and satellite image to estimate surface soil moisture at the field and watershed scales?
Authors: Corrêa Rotunno Filho Otto , de Paiva Kary , Paiva Alcoforado Rebello Vitor , Augusto Magalhães de Araujo Afonso
Published: June 2019

Soil moisture is a key environmental variable for developing a coupled hydrological and biogeochemical modeling approach. It is recognized that a relationship does exist between water stress and emission of volatile organic compounds (VOCs) in forested areas, which may have negative effect on human health and ecosystems. Therefore it is necessary to achieve a better understanding of the land phase of the hydrological cycle, namely soil moisture estimation, which modulates surface energy balance and consequently vegetation cover patterns. This work focuses on a new methodological approach to evaluate the spatial variability of surface soil moisture at the field scale using the Bayesian kriging model jointly with TDR measurements and Landsat 8-TM remotely sensed image. The analysis looked for quantifying different deterministic sources of variability, measurement errors and also components not well understood of variability. In particular, the spatial distribution of in situ measurements and digital image data in a scene provided by remote sensing technology is addressed through a geostatistical framework. This technique is explored as alternative to the regression techniques currently used for modeling soil moisture mapping. Tests conducted on an extensively sampled pasture field showed significant improvement, which suggests that the methodological approach could be applied at the watershed scale for validating remotely sensed datasets.
Tungsten speciation and its geochemical behavior in geothermal water: A review
Authors: Cao Yaowu , Guo Qinghai
Published: June 2019

Tungsten and most of its compounds remain one of the least regulated substances. As the potential toxicity of tungsten has been reported, the stereotypes about tungsten are gradually being broken. Areas with intense magmatic hydrothermal activity are likely threatened by geothermal tungsten (up to 1037 μg/L of tungsten was detected in the geothermal waters from a magmatic hydrothermal system in Tibet, Daggyai), and the geothermal developers should be cautious during the utilization of geothermal resource. This paper reviews the studies on transformation of aqueous tungsten species, distribution of tungsten in geothermal waters, and critical geochemical processes (or parameters) controlling geothermal tungsten concentrations. The mobility of aqueous tungsten depends on environmental pH, its complexation with sulfide, and its sorption onto Fe(III) oxides/oxyhydroxides. More attention still needs to be paid to environmental geochemistry of tungsten, in view that there are limited literatures reporting the thermodynamic properties of tungsten compounds at high temperatures and the models delineating the geochemical behavior of tungsten.
Hydrochemistry of thermal waters in crystalline rocks of the Sikhote-Alin ridge, Far East of Russia
Authors: Chelnokov George , Bragin Ivan , Kharitonova Natalia
Published: June 2019

Low-enthalpy thermal waters (30-50°C) of HCO3-Na and HCO3-SO4-Na types with nitrogen as a dominant associated gas discharge on the southern continental margin of the Russian Far East and traditionally are of great importance for recreation and balneology facilities. All studied thermal waters have meteoric origin and relate to Palaeocene granite intrusions. Based on the chemical characteristics and isotopic composition, thermal waters are divided onto “immature” thermal waters with a short residence time (3H=1.3±0.2TU), and “mature” thermal waters (3H=0.3±0.2TU) originated as a result of a longer evolution history (more than 60 years). The chemical composition of waters is largely determined by water-rock interactions, residence time and the local geothermal gradient.
A highly active karstic aquifer bounded by saline waters: The Judea Group aquifer
Authors: Gavrieli Ittai , Guttman Joseph , Yechieli Yoseph , Talhami Firas , Burg Avihu
Published: June 2019

The freshwater of the Judea Group aquifer that recharges on the crest of the Judea and Samria Mountain ridge flows east and west, defining two groundwater basins. At the foothills of both basins the freshwater encounters ancient saline or brackish water. The mode of interaction between the two water bodies within each basin is different, although both eventually discharge as brackish spring system. We describe these systems and identify the source of the higher salinity end members.
Geochemical characterization of components of the groundwater flow system in the basin of Mexico
Authors: Olea-Olea Selene , Escolero Oscar , Mahlknecht Jürgen
Published: June 2019

More than 21 million people live within the Basin of Mexico. Water is the main concern of this large population, where groundwater has been intensively exploited, leading to subsidence and fracturing of the ground. It is for this reason that it’s very important to understand the behavior of groundwater flow system components. This knowledge can help to more effectively manage water use and conserve the recharge zones. The main purpose of this study is to identify and characterize the components of groundwater flow system. Cluster analysis was used to classify 303 groundwater samples into groups. The groups show that chemical concentrations increase along the trajectories of groundwater flow. We describe these groups and identify three components in the flow system; the upper zone, the intermediate zone and the inferior zone. Different water management policies are suggested for each system component, because they have different response times to the actions taken in their use and conservation.
Hydrogeochemistry of thermal waters of the Baikal Rift, South-Eastern Tuva, Russia
Authors: Shestakova Anastasia , Guseva Natalia , Kopylova Yulia , Khvaschevskaya Albina , Arakchaa Kara-Kys
Published: June 2019

The spa resort of the Ush-Beldir is located in the south-eastern part of the Tuva region, Russia in the zone of influence of the Baikal rift. The Ush-Beldir territory has about 10 thermal springs and 4 exploration wells used for treatment and prevention of diseases. Hydrological and hydrochemical features of the thermal groundwaters are considered. The studied waters are thermal (T=50–83°C), alkaline (pH=9.3–10), low mineralized (TDS<370 mg/L) Na–НСО3 waters with a high content of SiO2 (up to 125 mg/L) and F (up to 14 mg/L). The correlation of F- with SiO2, НСО3–, Cl-, Na+ as well as the calculation of saturation indices of minerals, allows one plausible solute source for these thermal waters, viz. the dissolution of rock-forming aluminosilicates, most likely plagioclase, gabbro and/or amphiboles in shales.
Dissolved fluoride removal by OCP, a precursor of apatite
Authors: Idini Alfredo , Dore Elisabetta , Fancello Dario , Ghiglieri Giorgio , Frau Franco
Published: June 2019

The consumption of water with fluoride concentration higher than 1.5 mg/L (WHO recommended limit) is recognized to cause serious diseases. Fluoride removal from natural contaminated waters is a worldwide priority for more than 200 million people. The octacalcium phosphate (OCP), a mineralogical precursor of bio-apatite, is here tested as a fluoride remover. A new two-step method for the synthesis of OCP is proposed; it consists of 1) synthesis of brushite from calcium carbonate and phosphoric acid and, 2) subsequent hydrolysis of brushite. Fluoride removal experiments were performed in batch-mode using 200 mg of OCP in 50 ml solutions with different initial concentrations of fluoride (from 40 to 140 mg/L). Most of fluoride is removed within the first two hours, whereas the WHO limit of 1.5 mg/L is reached within a minimum of 3 hours for a starting Fconcentration of 40 mg/L, and in about 12 hours for a starting F-concentration of 80 mg/L. One gram of OCP can remove up to 26 mg of fluoride. The pH of the solution after the treatment is within the range of drinking water. XRD characterization of the solid phases, before and after the experiments, indicates that OCP transforms into fluorapatite via Fremoval from solution.
The provenance of deep groundwater and its relation to arsenic distribution in the northwestern Hetao Basin, Inner Mongolia
Authors: Liu Shuai , Guo Huaming , Lu Hai , Zhang Zhuo , Zhao Weiguang
Published: June 2019

High arsenic (As) groundwater has been found in deep aquifer of the northwestern Hetao Basin. Little is known about the source of high As deep groundwater and its role in As distribution. Based on strontium (Sr) isotopes, this study aims to investigate the provenance of high arsenic deep groundwater (DGW). 87Sr/86Sr in DGW gradually decreased from the alluvial fans to the flat plain. Results show that fissure water, plagioclase dissolution, and shallow groundwater (SGW) controlled the 87Sr/86Sr variation. Although the reductive dissolution of As-containing iron oxide controlled the As mobilization, the leaching of phyllite and meta-basalt, incongruent dissolution of plagioclase, and vertical mixing with SGW also played an important role in increasing As concentrations in DGW approximately along the flow paths.
Partitioning of potentially toxic elements among two colloidal fractions and relevance for their mobility in different water types
Authors: Moreno Filipa , Valente Teresa , Gomes Patrícia , Fonseca Rita , Costa Maria Rosário , Costa Ana
Published: June 2019

Potentially toxic elements are mobilized in aquatic systems in solution or bounded to colloids of different sizes, which may include nanometer particles. The present work studies the distribution of elements (Al, Fe, Zn, Mn, Co, Cd, Ni, Cu, and As) between small (<0.20 μm) and larger (0.45–0.20 μm) colloids in different waters sources in a world class metallogenic province (Iberian Pyrite Belt), including the acid mine waters. Syringe filters with pore-size ratings of 0.20 μm and 0.45 μm have been used to assess the transport and fate of these potentially toxic elements. The results show the contribution of colloids for mobility of arsenic and most metals, evidencing the role of the small ones in acid mine drainage.
Acid Mine Drainage Contamination of the Ur Impoundment: Environmental Geochemistry
Authors: Myagkaya Irina , Gustaytis Maria , Kirichenko Ivan , Saryg-ool Bagai-ool , Lazareva Elena
Published: June 2019

Water, particulate matter, and bottom sediments of the Ur impoundment used for fishing have been analyzed in terms of environmental geochemistry. The impoundment is located within the dispersion train of gold-bearing sulfide tailings at the Ur ore field and has been contaminated by acid mine drainage (AMD). The depth-dependent distribution of elements in the bottom sediments corresponds to (1) pre-mining, (2) early mining, and (3) post-mining (present) stages. Sediment enrichment in Cu, Cd, Fe, Pb, Zn, As and Hg depends on their speciation and migration patterns in water. The concentrations of many elements in water and bottom sediments exceed maximum allowable values. Hg occurring as the most toxic methyl compound poses the greatest hazard.
Climate factors of groundwater formation: a case study of the Lower Don
Authors: Nazarenko Olesya
Published: June 2019

Natural factors play an important role in the formation of the chemical composition and allocation of hydrogeochemical classes of groundwater in the Lower Don basin. The most resistant to human effects are groundwater of Sarmatian complex. The prospect of improving the quality of drinking water supply is associated with the involvement of groundwater in water management, but they are characterized by high hardness. Groundwater is influenced by geology, climate, biology, soil, and etc. Understanding the groundwater regime and pathways is essential because groundwater join and mixes with river water.
Hydrogeochemical Characteristics of Fluoride in the Groundwater of Shuangliao City, China
Authors: Sun Ying , Liang Xiujuan , Xiao Changlai , Wang Ge , Meng Fanao
Published: June 2019

This study investigated the hydrogeochemical characteristics of fluoride in the groundwater of Shuangliao City. This paper analyzes the effects of different forms of hydrochemistry and the chemical speciation of fluorine in water. The results showed that an area of high fluorine was located in the northern section of Shuangliao City, and the soil salinization degree was also high in this area. The chemical composition of groundwater was mainly formed by the evaporation-concentration process; both pH (weak alkaline environment) and total dissolved solids (TDS) had a positive effect on fluorine enrichment within a certain range; Na+ and F- had significant positive correlation, HCO3- and F- had a weak positive correlation, and Ca2+ was the only ion with a negative correlation with F-.
Influencing Factors of Groundwater Organic Pollution around the Bosten Lake Area of Xinjiang, China
Authors: Sun Ying , Zhou Jinlong , Zhou Yinzhu , Zeng Yanyan , Chen Yunfei
Published: June 2019

To study the status and influencing factors of groundwater organic pollution around the Bosten Lake area (Kaidu River-Kongque River Basin), Xinjiang, China, the pollution index method was applied to 82 groundwater samples and 15 lake water samples for comprehensive pollution evaluation. Results showed that the detection rates of organic pollutants in groundwater and lake water samples in the study area are 24.4% and 6.7%, respectively, but all the water samples have concentrations of organic pollutants less than the standard water quality limits. There are 11 unpolluted groundwater samples, 8 mildly polluted groundwater samples and one mid-polluted groundwater sample, accounting for 13.4%, 9.8% and 1.2% of total groundwater samples, respectively. The detection points of groundwater organic pollutants in the study area are mainly distributed in the piedmont plain area in the northern Yanqi Basin, the Yanqi County and the northwestern plain area of Bosten Lake. Some points sporadically distributed in the urban area in Korla. Groundwater organic pollution around the Bosten Lake area is mainly affected by industrial pollution, agricultural pollution, domestic pollution, vadose zone lithology, surface water quality and land utilization type.
Microscale effects of oxygen and light on bacterial sulfate reduction in organic-rich lacustrine sediments
Authors: Menchén Alfonso , Valiente Nicolas , Toledo Beatriz , Gómez-Alday Juan José
Published: June 2019

Biogeochemical cycling involves the exchange of electrons between chemical species through redox reactions. Microorganisms can utilize energy released by redox reactions for their metabolism following a thermodynamic sequence. Among these reactions, the dissimilatory reduction of sulfate (SO42−) to produce hydrogen sulfide (H2S) is one of the most important microbially-mediated pathways. The use of microelectrodes at the water-sediment interface provided a better understanding of sulfate reduction processes in the suboxic and anoxic zones. The goal of this study was to assess the microzonation of H2S and O2 under different conditions of light and oxygen in the water column. For this purpose, organic-rich lacustrine sediments from Pétrola Lake (SE Spain) were used. Sediment incubations were performed in mesocosm devices. The highest production of H2S (up to 0.36 nmol/cm-3s-1) was observed under anoxic and dark conditions. Production under those conditions was several orders of magnitude higher than those measured when oxygen was present in the water column. Furthermore, the absence of O2 in the water column significantly altered the microzonation of H2S in depth. The absence of light seems not to affect the dynamics of O2 and H2S in depth. The study contributes to our understanding of microzonation in organic-rich sediments.
Groundwater recharge by high-salinity lake water in a density-driven flow dominated system: an isotopic approach
Authors: Valiente Nicolás , Sanz David , Gómez-Alday Juan José
Published: June 2019

Pétrola Lake is a terminal lake located in the discharge zone of an endorheic basin. Terminal lakes may be responsible for a significant amount of recharge from evaporated saline water, increasing the salinity of the shallow groundwater. The purpose of this paper is to evaluate the interaction between groundwater and saline water from Pétrola Lake in order to improve the knowledge of groundwater recharge processes by density-driven flow (DDF) in terminal lakes. To achieve this goal, hydrochemical (chloride concentration) and stable isotope (δ18O and δDH2O) data were used. The isotopic composition of 190 groundwater and surface water samples collected between September 2008 and July 2015 provide a regression line (δDH2O = 5.0·δ18O – 14.3‰, R2 = 0.95) consistent with dominant evaporation processes. In the basin, groundwater recharge is mainly produced by Atlantic-derived precipitation. In the lake, isotope data suggested that the loss of water occurred at humidity values between 60% and 75%. The saline boundary layer is formed at elevated salt concentrations. Leakage from the lake to the underlying aquifer would take place with salinities from 1.24 g/cm3 by means of the DDF. This study contributes to better understand the role of DDF in terminal lakes.
Origin of brines and modern water circulation contribution to Qarhan salt lake in Qaidam basin, Tibetan plateau
Authors: Xiao Yong , Hao Qichen , Luo Yinfei , Wang Shengbin , Dang Xueya , Shao Jingli , Huang Linxian
Published: June 2019

Lake Qarhan is the largest salt lake and potassium salt resource mining base in china. Understanding the origin of brines and the contribution of modern water circulation is extremely important to the sustainable development of the salt lake. Comprehensive tools including isotope, hydrochemistry and numerical simulation had been performed. Results suggest that brine groundwater in the salt lake area is the result of ancient brines migrated from the western Qaidam Basin due to the uplift of the western basin in the geological past. Shallow phreatic aquifers in the salt lake area are also recharged by the modern surface water in the flood period. The contribution of modern groundwater circulation to the salt lake area is very limited with only 3% of the total quantity of groundwater discharge for the watershed.
Mineralogical, geochemical and isotopic (C, O, Sr) features of the unique high-grade REE-Nb ores from the Tomtor deposit (Arctic Siberia, Russia)
Authors: Zhmodik Sergey , Lazareva Elena , Dobretsov Nikolay , Ponomarchuk Viktor , Tolstov Alexander
Published: June 2019

The mineralogy (SEM), geochemistry (LA-ICP-MS) and isotopic composition of C, O and Sr in carbonates from uniquely high-grade REE-Nb ores of the Tomtor massif is presented. Testing of the formation conditions for uniquely high-grade ores from the Tomtor deposit was conducted.
KPFM surface photovoltage measurement and numerical simulation
Authors: Marchat Clément , Connolly James P. , Kleider Jean-Paul , Alvarez José , Koduvelikulathu Lejo J. , Puel Jean Baptiste
Published: June 2019

A method for the analysis of Kelvin probe force microscopy (KPFM) characterization of semiconductor devices is presented. It enables evaluation of the influence of defective surface layers. The model is validated by analysing experimental KPFM measurements on crystalline silicon samples of contact potential difference (VCPD) in the dark and under illumination, and hence the surface photovoltage (SPV). It is shown that the model phenomenologically explains the observed KPFM measurements. It reproduces the magnitude of SPV characterization as a function of incident light power in terms of a defect density assuming Gaussian defect distribution in the semiconductor bandgap. This allows an estimation of defect densities in surface layers of semiconductors and therefore increased exploitation of KPFM data.
Megalobrama amblycephala grazes preferentially on Hydrilla verticillata but makes more efficient use of Vallisneria denseserrulata: implications for biological control of submerged macrophytes
Authors: Yin Chunyu , Wang Zhaoxia , Zhao Yu , Gao Yiming , Zhen Wei , He Xiaolin , Yin Chunsheng , Guan Baohua
Published: June 2019

Growth of the meadow-forming macrophyte Vallisneria denseserrulata is often negatively impacted as result of shading by the canopy-forming Hydrilla verticillata. Grazing by the herbivorous cyprinid Megalobrama amblycephala is thought to control H. verticillata. We hypothesized that M. amblycephala would prefer H. verticillata over V. denseserrulata, and that where the latter is grazed, its growth will not be wholly compromised, due in part to the efficiency with which it is metabolized by the grazer. In a pond experiment, macrophytes were planted with monocultures of H. verticillata and V. denseserrulata, and in mixed cultures of the two species, with and without grazing by M. amblycephala. The results showed that in the absence of fish, the growth rate of V. denseserrulata was significantly reduced in the presence of H. verticillata. In the mixture, M. amblycephala had a significant negative effect on the growth of H. verticillata but not on V. denseserrulata. Grazing was associated with reductions in plant height, plant fresh weight and leaf fresh weight but the leaf number, maximum root length, maximum blade width, root weight and stem weight in V. denseserrulata increased. The food utilization ratio of M. amblycephala was significantly higher when grazing solely on V. denseserrulata than when grazing on H. verticillata or the mixture. Our results imply that V. denseserrulata is protected from overgrazing by the ability of M. amblycephala to make more effective metabolic use of ingested material than for H. verticillata. Furthermore, M. amblycephala is beneficial to V. denseserrulata in reducing competition from H. verticillata.
Investigation of diffusion behavior of carburized sheet metal in hot stamping
Authors: Horn Alexander , Merklein Marion
Published: June 2019

Today, manufacturing of structural car body parts faces several challenges, like forming accuracy, passenger safety and lightweight design. One possibility to fulfill these partially rivalling demands is the application of hot stamped components. The combination of hot forming and in-die quenching reduces not only springback, but also results in tensile strengths of more than 1500 MPa. Besides conventional hot stamping, the process can be adapted to manufacture parts with tailored properties. One of the biggest issues of these state-of-the-art processes is the formation of extensive transition zones due to heat transfer. A promising approach to adjust the mechanical properties with a minimized transition zone is tailored carburization of sheet metal. Therefore, the parts are locally coated with graphite, heat treated and subsequently quenched. In this work, the time variant process of carbon diffusion is investigated. Sheets with two different thicknesses are carburized and quenched. The resulting mechanical properties are analyzed using uniaxial tensile tests and microhardness measurements. On this basis, a process window is identified. Furthermore, the applicability of EDX and WDX analysis for the measurement of carbon concentration is investigated within this work.
Modeling of excitatory amino acid transporters and clearance of synaptic cleft on millisecond time scale
Authors: Shchepakin Denis , Kalachev Leonid , Kavanaugh Michael
Published: June 2019

Excitatory Amino Acid Transporters (EAATs) operate over wide time scales in the brain. They maintain low ambient concentrations of the primary excitatory amino acid neurotransmitter glutamate, but they also seem to play a significant role in clearing glutamate from the synaptic cleft in the millisecond time-scale process of chemical communication that occurs between neurons. The detailed kinetic mechanisms underlying glutamate uptake and clearance remain incompletely understood. In this work we used a combination of methods to model EAAT kinetics and gain insight into the impact of transport on glutamate dynamics in a general sense. We derive reliable estimates of the turnover rates of the three major EAAT subtypes expressed in the mammalian cerebral cortex. Previous studies have provided transporter kinetic estimates that vary over an order of magnitude. The values obtained in this study are consistent with estimates that suggest the unitary transporter rates are approximately 20-fold slower than the time course of glutamate in the synapse. A combined diffusion/transport model provides a possible mechanism for the apparent discrepancy.
Modified Courant-Beltrami penalty function and a duality gap for invex optimization problem
Authors: Hassan Mansur , Baharum Adam
Published: June 2019

In this paper, we modified a Courant-Beltrami penalty function method for constrained optimization problem to study a duality for convex nonlinear mathematical programming problems. Karush-Kuhn-Tucker (KKT) optimality conditions for the penalized problem has been used to derived KKT multiplier based on the imposed additional hypotheses on the constraint function g. A zero-duality gap between an optimization problem constituted by invex functions with respect to the same function η and their Lagrangian dual problems has also been established. The examples have been provided to illustrate and proved the result for the broader class of convex functions, termed invex functions.
Spitzengefühl beweisen – Semmes-Weinstein Monofilament Test
Authors: Schormann Niklas
Published: June 2019

Ergotherapeuten begegnen immer wieder Patienten, die von eingeschränkter Sensibilität in Händen und Füßen berichten. Um das Ausmaß der Einschränkungen bestimmen und Rückschlüsse auf die zugrunde liegende Schädigung ziehen zu können, steht der Semmes-Weinstein Monofilament Test zur Verfügung.
„Das Besondere an dieser Therapie ist, dass sie zu Hause stattfindet“ – homeCIMT
Authors: Janssen Christina
Published: June 2019

Mit der evidenzbasierten Therapiemethode homeCIMT können Menschen nach einem Schlaganfall ihren Arm- und Handeinsatz verbessern. Dabei arbeiten sie mit einem nicht professionellen Übungsbegleiter im häuslichen Umfeld. ergopraxis hat Therapeutinnen des Fortbildungsteams homeCIMT-Konzept befragt.