keyword
MENU ▼
Read by QxMD icon Read
search

Chemical speciation

keyword
https://www.readbyqxmd.com/read/28731295/biogeochemistry-of-lead-its-release-to-the-environment-and-chemical-speciation
#1
Jay T Cullen, Jason McAlister
Lead (Pb) is a metal that is not essential for life processes and proves acutely toxic to most organisms. Compared to other metals Pb is rather immobile in the environment but still its biogeochemical cycling is greatly perturbed by human activities. In this review we present a summary of information describing the physical and chemical properties of Pb, its distribution in crustal materials, and the processes, both natural and anthropogenic, that contribute to the metal's mobilization in the biosphere. The relatively high volatility of Pb metal, low melting point, its large ionic radius, and its chemical speciation in aquatic systems contributes to its redistribution by anthropogenic and natural processes...
April 10, 2017: Metal Ions in Life Sciences
https://www.readbyqxmd.com/read/28730356/seasonal-variation-of-chemical-composition-and-source-apportionment-of-pm2-5-in-pune-india
#2
Ranjeeta D Gawhane, Pasumarthi Surya Prakasa Rao, Krishnakant B Budhavant, Vinayak Waghmare, Dhananjay C Meshram, Pramod D Safai
Particulate matter with size less than or equal to 2.5 μm (PM2.5) samples were collected from an urban site Pune, India, during April 2015 to April 2016. The samples were analyzed for various chemical constituents, including water soluble inorganic ions, organic carbon (OC), and elemental carbon (EC). The yearly mean total mass concentration of PM2.5 at Pune was 37.3 μg/m(3), which is almost four times higher than the annual WHO standard (10 μg/m(3)), and almost equal to that recommended by the Central Pollution Control Board, India (40 μg/m(3))...
July 20, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28728128/radionuclide-biokinetics-in-the-russian-sturgeon-and-phylogenetic-consistencies-with-cartilaginous-and-bony-marine-fishes
#3
Ross A Jeffree, Scott J Markich, Francois Oberhaensli, Jean-Louis Teyssie
The biokinetics of eight radionuclides ((241)Am, (109)Cd, (134)Cs, (75)Se, (54)Mn, (110m)Ag, (65)Zn, (60)Co) absorbed from the aquatic medium by juvenile Russian sturgeon (Acipenser gueldenstaedtii) were experimentally determined in fresh (0.42‰) and brackish (9.0‰) waters, of a similar salinity range to the Caspian Sea, and in conjunction with chemical speciation modelling. Uptake and loss rate constants were determined for each radionuclide for a 14 day exposure at each salinity and during 28 days of exposure to radionuclide-free conditions...
July 17, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28726692/chemical-speciation-of-trace-metals-in-the-industrial-sludge-of-dhaka-city-bangladesh
#4
Md Saiful Islam, Md Habibullah Al-Mamun, Ye Feng, Masahiro Tokumura, Shigeki Masunaga
The objective of this study was to assess total concentration and chemical fractionation of trace metals in the industrial wastewater and sludge collected from seven different types of industries in Dhaka City, Bangladesh. The sludge from industries is either dumped on landfills or reused as secondary resources in order to preserve natural resources. Metals were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The ranges of Cr, Ni, Cu, As, Cd, and Pb in the sludges were 1.4-9,470, 4.8-994, 12...
July 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28718696/tumor-induced-disorder-of-iron-metabolism-in-major-organs-a-new-insight-from-chemical-speciation-of-iron
#5
Rujie Chen, Guangcun Chen
Objective To investigate the evolution of iron speciation in major organs of tumor-bearing mice and its role in cancer formation and cancer-associated complications. Methods The concentration and chemical speciation of iron in the spleen, liver, lung, kidney, heart, blood, muscle, and tumor tissue of healthy mice and tumor-bearing mice were studied by synchrotron radiation-based total reflection X-ray fluorescence spectrometry (SR-TXRF) coupled with X-ray absorption spectroscopy (XAS). Results The TXRF and XAS results showed that the iron content, especially the ferritin content, significantly decreased in the blood and spleen but significantly increased in the liver, lung, and muscle of mice after tumor implantation...
January 1, 2017: Journal of International Medical Research
https://www.readbyqxmd.com/read/28714679/spectroscopic-study-of-the-reversible-chemical-reduction-and-reoxidation-of-substitutional-cr-ions-in-sr2tio4
#6
Keith A Lehuta, Anubhab Haldar, Dongming Zhou, Kevin R Kittilstved
The solid-state synthesis and controllable speciation of Cr dopants in the layered perovskite Sr2TiO4 is reported. We employed a chemical reduction procedure with NaBH4 at relatively mild temperatures (<450 °C) to impart sensitive control over the relative concentration of Cr(3+) dopants, the charge-state of oxygen-vacancy defects, and presence of Ti(3+) defects in highly reduced Cr-doped Sr2TiO4. The electron paramagnetic resonance (EPR) spectra of the reduced powder samples reveal a 12-fold increase in the Cr(3+) concentration within the axially compressed Ti(4+)-site of the Sr2TiO4 host...
July 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28710730/remediation-of-chromium-contaminated-soil-by-electrokinetics-and-electrokinetics-coupled-with-caal-ldh-permeable-reaction-barrier
#7
Yunfeng Xu, Wei Xia, Hetian Hou, Jia Zhang, Guangren Qian
The remediation of Cr(VI)-contaminated soil was investigated by electrokinetic (EK) and permeable-reactive-barrier assisted electrokinetic (EK-PRB). The medium of PRB was hydrocalumite (CaAl-LDH). The results showed that removal efficiency of hexavalent chromium (Cr(VI)) in EK-PRB and EK system was 96.49 and 85.50%, respectively. Simultaneously, the removal efficiency of total chromium (TCr) was 69.34 and 40.97% after 120-h treatment. The XRD, FTIR, and XPS analyses indicated that the reactive barrier media of CaAl-LDH successfully captured the chromium...
July 15, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28702905/assessment-of-biofilm-changes-and-concentration-depth-profiles-during-arsenopyrite-oxidation-by-acidithiobacillus-thiooxidans
#8
Hugo Ramírez-Aldaba, Jorge Vazquez-Arenas, Fabiola S Sosa-Rodríguez, Donato Valdez-Pérez, Estela Ruiz-Baca, Jessica Viridiana García-Meza, Gabriel Trejo-Córdova, René H Lara
Biofilm formation and evolution are key factors to consider to better understand the kinetics of arsenopyrite biooxidation. Chemical and surface analyses were carried out using Raman spectroscopy, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), glow discharge spectroscopy (GDS), and protein analysis (i.e., quantification) in order to evaluate the formation of intermediate secondary compounds and any significant changes arising in the biofilm structure of Acidithiobacillus thiooxidans during a 120-h period of biooxidation...
July 12, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28674972/genetic-variation-and-phylogenetic-relationships-of-the-ectomycorrhizal-floccularia-luteovirens-on-the-qinghai-tibet-plateau
#9
Rui Xing, Qing-Bo Gao, Fa-Qi Zhang, Peng-Cheng Fu, Jiu-Li Wang, Hui-Ying Yan, Shi-Long Chen
Floccularia luteovirens, as an ectomycorrhizal fungus, is widely distributed in the Qinghai-Tibet Plateau. As an edible fungus, it is famous for its unique flavor. Former studies mainly focus on the chemical composition and genetic structure of this species. However, the phylogenetic relationship between genotypes remains unknown. In this study, the genetic variation and phylogenetic relationship between the genotypes of F. luteovirens in Qinghai-Tibet Plateau was estimated through the analysis on two protein-coding genes (rpb1 and ef-1α) from 398 individuals collected from 24 wild populations...
July 4, 2017: Journal of Microbiology / the Microbiological Society of Korea
https://www.readbyqxmd.com/read/28668753/precipitation-adsorption-and-rhizosphere-effect-the-mechanisms-for-phosphate-induced-pb-immobilization-in-soils-a-review
#10
REVIEW
Guangming Zeng, Jia Wan, Danlian Huang, Liang Hu, Chao Huang, Min Cheng, Wenjing Xue, Xiaomin Gong, Rongzhong Wang, Danni Jiang
Lead (Pb) is one of the most toxic heavy metals that pose a direct threat to organisms and it can not been degraded through microbial activities or chemical reaction. Bioavaibility and eco-toxicity of Pb which mostly depend on Pb chemical speciation play an important role in the remediation of Pb-contaminated soils. Phosphate (P) amendments which could transfer Pb from unstable fraction to stable fraction are commonly used to immobilize Pb in soils and have been extensively studied by researchers during decades...
June 20, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28667848/prediction-of-the-bioavailability-of-potentially-toxic-elements-in-freshwaters-comparison-between-speciation-models-and-passive-samplers
#11
Jordi Sierra, Neus Roig, Gemma Giménez Papiol, Elena Pérez-Gallego, Marta Schuhmacher
The aim of this work is to predict the bioavailability of the Potentially Toxic Elements (PTEs) Cd, Pb, Hg, Ni, Cu, Zn, As, Cr and Se in 6 sites within the Ebro River basin. In situ Diffusive gradient in thin-films (DGTs) and classical sampling have been used and compared. The potentially bioavailable fractions of each PTE was estimated by modelling their chemical speciation using three programs (WHAM 7.0, Visual MINTEQ 3.1 and Bio-met), following the suggestions published in recent European regulations. Results of the equilibrium-based models WHAM 7...
June 28, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28664967/two-coexisting-liquid-phases-in-switchable-ionic-liquids
#12
Juan Yao, David B Lao, Xiao Sui, Yufan Zhou, Satish K Nune, Xiang Ma, Tyler P Troy, Musa Ahmed, Zihua Zhu, David J Heldebrant, Xiao-Ying Yu
Switchable ionic liquids (SWILs) derived from organic bases and alcohols are attractive due to their applications in gas capture, separations, and nanomaterial synthesis. However, their exact solvent structure still remains a mystery. We present the first chemical mapping of a SWIL solvent structure using in situ time-of-flight secondary ion mass spectrometry. In situ chemical mapping discovers two coexisting liquid phases and molecular structures vastly different from conventional ionic liquids. SWIL chemical speciation is found to be more complex than the known stoichiometry...
June 30, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28657305/solid-phase-speciation-and-solubility-of-vanadium-in-highly-weathered-soils
#13
Worachart Wisawapipat, Ruben Kretzschmar
Vanadium (V) is increasingly recognized both as a medical trace element with essential biological functions and as a potentially toxic environmental pollutant, yet the current knowledge on V speciation in soils is limited. Here, we investigated the chemical speciation and extractability of V in highly weathered tropical soils, which are often rich in V compared to soils of temperate climatic regions. Vanadium K-edge X-ray absorption near edge structure (XANES) spectra of soil samples, along with a range of reference compounds differing in V-oxidation state and coordination chemistry, revealed the predominance of V4+/5+ in a primarily octahedral or tetrahedral coordination...
June 28, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28656557/distribution-and-assessment-of-heavy-metal-toxicity-in-sediment-cores-from-bizerte-lagoon-tunisia
#14
Haïfa Ben Mna, Walid Oueslati, Mohamed Amine Helali, Noureddine Zaaboub, Ayed Added, Lotfi Aleya
To examine the state of pollution of Bizerte Lagoon which is exposed to intense anthropogenic pressure, two sediment cores were taken at two sites, one undergoes the dual effects of both marine waters arriving from the Mediterranean Sea through the Channel, and also of freshwater from the Tinja River; the other core is located at the center of the lagoon where water depth is maximal (12 m). Heavy metal concentrations in the two cores were assessed, with calculated enrichment factors and geo-accumulation indexes...
July 2017: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/28644630/expanding-the-therapeutic-potential-of-the-iron-chelator-deferasirox-in-the-development-of-aqueous-stable-ti-iv-anticancer-complexes
#15
Sergio A Loza-Rosas, Alexandra M Vázquez-Salgado, Kennett I Rivero, Lenny J Negrón, Yamixa Delgado, Josué A Benjamín-Rivera, Angel L Vázquez-Maldonado, Timothy B Parks, Charlene Munet-Colón, Arthur D Tinoco
The recent X-ray structure of titanium(IV)-bound human serum transferrin (STf) exhibiting citrate as a synergistic anion reveals a difference in Ti(IV) coordination versus iron(III), the metal endogenously delivered by the protein to cells. This finding enriches our bioinspired drug design strategy for Ti(IV)-based anticancer therapeutics, which applies a family of Fe(III) chelators termed chemical transferrin mimetic (cTfm) ligands to inhibit Fe bioavailability in cancer cells. Deferasirox, a drug used for iron overload disease, is a cTfm ligand that models STf coordination to Fe(III), favoring Fe(III) binding versus Ti(IV)...
July 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28636822/electrochemical-properties-and-speciation-in-mg-hmds-2-based-electrolytes-for-magnesium-batteries-as-a-function-of-ethereal-solvent-type-and-temperature
#16
Laura C Merrill, Jennifer L Schaefer
Magnesium batteries are a promising alternative to lithium-ion batteries due to the widespread abundance of magnesium and its high specific volumetric energy capacity. Ethereal solvents such as tetrahydrofuran (THF) are commonly used for magnesium-ion electrolytes due to their chemical compatibility with magnesium metal, but the volatile nature of THF is a concern for practical application. Herein, we investigate magnesium bis(hexamethyldisilazide) plus aluminum chloride (Mg(HMDS)2-AlCl3) electrolytes in THF, diglyme, and tetraglyme at varying temperature...
July 6, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28626946/do-changes-in-gene-expression-contribute-to-sexual-isolation-and-reinforcement-in-the-house-mouse
#17
Etienne Loire, Sergio Tusso, Pierre Caminade, Dany Severac, Pierre Boursot, Guila Ganem, Carole M Smadja
Expression divergence, rather than sequence divergence, has been shown to be important in speciation, particularly in the early stages of divergence of traits involved in reproductive isolation. In the two European subspecies of house mice, Mus musculus musculus and M. m. domesticus, earlier studies have demonstrated olfactory-based assortative mate preference in populations close to their hybrid zone. It has been suggested that this behaviour evolved following the recent secondary contact between the two taxa (~3,000 years ago) in response to selection against hybridisation...
June 19, 2017: Molecular Ecology
https://www.readbyqxmd.com/read/28620816/bioaccessibility-of-as-cu-pb-and-zn-in-mine-waste-urban-soil-and-road-dust-in-the-historical-mining-village-of-ka%C3%A5-k-czech-republic
#18
Petr Drahota, Karel Raus, Eva Rychlíková, Jan Rohovec
Historical mining activities in the village of Kaňk (in the northern part of the Kutná Hora ore district, Czech Republic) produced large amounts of mine wastes which contain significant amounts of metal(loid) contaminants such as As, Cu, Pb, and Zn. Given the proximity of residential communities to these mining residues, we investigated samples of mine waste (n = 5), urban soil (n = 6), and road dust (n = 5) with a special focus on the solid speciation of As, Cu, Pb, and Zn using a combination of methods (XRD, SEM/EDS, oxalate extractions), as well as on in vitro bioaccessibility in simulated gastric and lung fluids to assess the potential exposure risks for humans...
June 15, 2017: Environmental Geochemistry and Health
https://www.readbyqxmd.com/read/28611437/reproductive-isolation-through-experimental-manipulation-of-sexually-antagonistic-coevolution-in-drosophila-melanogaster
#19
Zeeshan Ali Syed, Martik Chatterjee, Manas Arun Samant, Nagaraj Guru Prasad
Promiscuity can drive the evolution of sexual conflict before and after mating occurs. Post mating, the male ejaculate can selfishly manipulate female physiology, leading to a chemical arms race between the sexes. Theory suggests that drift and sexually antagonistic coevolution can cause allopatric populations to evolve different chemical interactions between the sexes, thereby leading to postmating reproductive barriers and speciation. There is, however, little empirical evidence supporting this form of speciation...
June 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28600571/micro-scale-heterogeneity-of-soil-phosphorus-depends-on-soil-substrate-and-depth
#20
Florian Werner, Carsten W Mueller, Jürgen Thieme, Alessandra Gianoncelli, Camille Rivard, Carmen Höschen, Jörg Prietzel
Soils comprise various heterogeneously distributed pools of lithogenic, free organic, occluded, adsorbed, and precipitated phosphorus (P) forms, which differ depending on soil forming factors. Small-scale heterogeneity of element distributions recently has received increased attention in soil science due to its influence on soil functions and soil fertility. We investigated the micro-scale distribution of total P and different specific P binding forms in aggregates taken from a high-P clay-rich soil and a low-P sandy soil by combining advanced spectrometric and spectroscopic techniques to introduce new insights on P accessibility and availability in soils...
June 9, 2017: Scientific Reports
keyword
keyword
29344
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"