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NeuroImage Feb 2021Unilateral damage to the inner ear results in an acute vestibular syndrome, which is compensated within days to weeks due to adaptive cerebral plasticity. This process,...
Unilateral damage to the inner ear results in an acute vestibular syndrome, which is compensated within days to weeks due to adaptive cerebral plasticity. This process, called central vestibular compensation (VC), involves a wide range of functional and structural mechanisms at the cellular and network level. The short-term dynamics of whole-brain functional network recruitment and recalibration during VC has not been depicted in vivo. The purpose of this study was to investigate the interplay of separate and distinct brain regions and in vivo networks in the course of VC by sequential [F]-FDG-PET-based statistical and graph theoretical analysis with the aim of revealing the metabolic connectome before and 1, 3, 7, and 15 days post unilateral labyrinthectomy (UL) in the rat. Temporal changes in metabolic brain connectivity were determined by Pearson's correlation (|r| > 0.5, p < 0.001) of regional cerebral glucose metabolism (rCGM) in 57 segmented brain regions. Metabolic connectivity analysis was compared to univariate voxel-wise statistical analysis of rCGM over time and to behavioral scores of static and dynamic sensorimotor recovery. Univariate statistical analysis revealed an ipsilesional relative rCGM decrease (compared to baseline) and a contralesional rCGM increase in vestibular and limbic networks and an increase in bilateral cerebellar and sensorimotor networks. Quantitative analysis of the metabolic connections showed a maximal increase from baseline to day 3 post UL (interhemispheric: 2-fold, ipsilesional: 3-fold, contralesional: 12-fold) and a gradual decline until day 15 post UL, which paralleled the dynamics of vestibular symptoms. In graph theoretical analysis, an increase in connectivity occurred especially within brain regions associated with brainstem-cerebellar and thalamocortical vestibular networks and cortical sensorimotor networks. At the symptom peak (day 3 post UL), brain networks were found to be organized in large ensembles of distinct and highly connected hubs of brain regions, which separated again with progressing VC. Thus, we found rapid changes in network organization at the subcortical and cortical level and in both hemispheres, which may indicate an initial functional substitution of vestibular loss and subsequent recalibration and reorganization of sensorimotor networks during VC.
Topics: Adaptation, Physiological; Animals; Arsanilic Acid; Brain; Connectome; Fluorodeoxyglucose F18; Glucose; Locomotion; Neural Pathways; Neuronal Plasticity; Nystagmus, Pathologic; Positron-Emission Tomography; Postural Balance; Radiopharmaceuticals; Rats; Vestibular Diseases; Vestibule, Labyrinth
PubMed: 33249212
DOI: 10.1016/j.neuroimage.2020.117588 -
The Science of the Total Environment Feb 2021Adsorption and desorption of p-arsanilic acid (p-ASA) and roxarsone (ROX) on six soil minerals, including hematite (α-FeO), goethite (α-FeOOH), ferrihydrite (Fe(OH)),...
Adsorption and desorption of p-arsanilic acid (p-ASA) and roxarsone (ROX) on six soil minerals, including hematite (α-FeO), goethite (α-FeOOH), ferrihydrite (Fe(OH)), aluminum oxide (α-AlO), manganese oxide (γ-MnO), and kaolinite, were studied, and the impact of solution matrices on their adsorption was systematically evaluated. Adsorption of p-ASA/ROX on the metal (hydro)oxide and clay minerals occurred quickly (mostly within 2 h), and could be well described by the pseudo second-order kinetic model. The apparent maximum adsorption capacities of α-FeO, α-FeOOH, Fe(OH), α-AlO, γ-MnO, and kaolinite (at an initial pH of 7.0) for p-ASA were 1.7, 0.9, 2.5, 0.08, 1.1, and 0.02 μmol/m, while those for ROX were 1.6, 0.7, 2.4, 0.1, 0.5, and 0.05 μmol/m, respectively. Besides adsorbing p-ASA/ROX, γ-MnO also caused their oxidation. Experimental results suggest that formation of inner-sphere complexes through the arsonic acid group is the primary mechanism for adsorption of p-ASA/ROX on iron (hydro)oxides and γ-MnO, while outer-sphere complexation plays a critical role in their adsorption on α-AlO and kaolinite. Adsorption of p-ASA/ROX on the metal (hydro)oxide and clay minerals was affected by solution pH, co-existing metal ions (Ca, Mg, Al, Cu, Fe, and Zn), oxyanions (HPO, HCO, and SO), and humic acid. The solid-to-liquid partition coefficients of p-ASA during the desorption from α-FeO, α-FeOOH, Fe(OH), α-AlO, γ-MnO, and kaolinite were 0.47, 2.69, 4.38, 0.03, 30.4, and 0.1 L/g, while those of ROX were 0.28, 1.68, 3.48, 0.02, 4.0, and 0.02 L/g, respectively. Agricultural soils with lower contents of organic carbon exhibited higher adsorption capacities towards p-ASA/ROX, which indicates that soil minerals play a key role in the adsorption of phenylarsonic acid compounds while organic matter could have strong inhibitory effect. These findings could help better understand and predict the transport and fate of p-ASA/ROX in surface soils with low contents of organic matter.
PubMed: 33229094
DOI: 10.1016/j.scitotenv.2020.143765 -
Electrophoresis Mar 2021Arsenic aromatic compounds including p-arsanylic acid (pASA) are still widely used in a number of countries as the feed additives in animal breeding resulting in its...
Arsenic aromatic compounds including p-arsanylic acid (pASA) are still widely used in a number of countries as the feed additives in animal breeding resulting in its entering the environment. Under the influence of oxidizing agents or UV radiation, pASA undergoes transformations leading to generation of inorganic arsenic species that are more mobile and toxic than organic ones. On the one hand, an approach based on the treatment of contaminated waters by UV irradiation seems perspective for their detoxification, but the feasibility of this approach depends on the composition of the products forming as a result of photodegradation. In the present work, a CZE was applied for the study of the pASA degradation process during stationary (308 nm) photolysis in the presence of Fe(III)-oxalate complex. A developed assay allowed controlling the parent compounds and also As-containing products of pASA degradation, presented mainly by arsenate and arsenite ions. It was found that the main inorganic derivatives of the pASA photolytic conversions are presented by arsenate and arsenite ions whose ratio depends on the initial amount of pASA and reaction conditions.
Topics: Animals; Arsanilic Acid; Arsenates; Arsenic; Arsenites; Electrophoresis, Capillary; Ferric Compounds; Hydrogen-Ion Concentration; Organic Chemicals; Photolysis
PubMed: 33185273
DOI: 10.1002/elps.202000262 -
Food Chemistry Apr 2021This study investigated the effect of seaweed supplementation (Ulva lactuca (UL) or Sargassum hemiphyllum var. chinense (SHC)) on the distribution and metabolites of As...
This study investigated the effect of seaweed supplementation (Ulva lactuca (UL) or Sargassum hemiphyllum var. chinense (SHC)) on the distribution and metabolites of As in broiler breasts. Broilers fed 5% UL or 5% SHC ingested 1.4- or 78- fold greater total As than birds fed the control diet. The majority of As species were arsenate in the SHC feed and dimethylarsinic acid in breasts from chicks fed the SHC-containing diet. Arsenate and arsenobetaine were the dominant metabolites in the UL-containing feed, and arsenobetaine was the major metabolite in breasts from chicks fed the UL-containing diet. Feeding SHC enhanced hepatic S-adenosyl-methionine and arsenic methyltransferase, whereas feeding UL elevated renal arsenic methyltransferase. Taken together, considerable variation in the profiles of As species and As metabolites existed in broilers fed seaweed. The use of SHC-containing feeds in poultry production should be approached cautiously because of the potential accumulation of inorganic As species in chicken breasts.
Topics: Animals; Arsenic; Chickens; Diet; Sargassum; Ulva; Vegetables
PubMed: 33077282
DOI: 10.1016/j.foodchem.2020.128346 -
Chemosphere Nov 2020It is crucial for water environment security to remove its p-arsanilic acid (p-ASA) efficiently. Namely, removing p-arsanilic acid from aqueous media through magnetic...
It is crucial for water environment security to remove its p-arsanilic acid (p-ASA) efficiently. Namely, removing p-arsanilic acid from aqueous media through magnetic separation, has become a novel method of removing toxic pollutants from water. Batch adsorption experiments demonstrated a higher adsorption of lignin-based magnetic activated carbon (201.64 mg g) toward p-ASA. In addition, LMAC nanoparticles exhibited typical magnetism (35.63 emu g of saturation magnetization) and could be easily separated from the aqueous solution. Meanwhile, the endothermic adsorption of p-ASA over LMAC could spontaneously proceed and be well described by the pseudo-first-order and pseudo-second-order model as well as the intra-particle diffusion model. Moreover, the mechanisms during p-ASA adsorption over LMAC included the electrostatic attraction, surface complexation, π-π stacking and hydrogen bonding interaction. Importantly, lignin-based magnetic activated carbon has high absorbability and preferable reusability in real water samples. Consequently, this paper provides insights into preparation of the lignin-based magnetic activated carbon may be potential adsorbents for the remediation of organoarsenic compounds.
Topics: Adsorption; Arsanilic Acid; Charcoal; Kinetics; Lignin; Magnetic Phenomena; Magnetics; Magnets; Water; Water Pollutants, Chemical; Water Purification
PubMed: 32947657
DOI: 10.1016/j.chemosphere.2020.127276 -
Journal of Hazardous Materials Nov 2020In this study, magnetic material based reduced graphene oxide (M-rGO) was prepared through co-precipitation and displayed high catalytic efficiency together with...
In this study, magnetic material based reduced graphene oxide (M-rGO) was prepared through co-precipitation and displayed high catalytic efficiency together with persulfate (PS) for simultaneous p-arsanilic acid (p-ASA) decomposition and arsenic removal. Linear sweep voltammetry and chronoamperometric measurements with M-rGO revealed that PS was effectively bound to M-rGO surface and probably formed charge transfer complex, in which M-rGO was pivotal in mediating facile electron transfer. The effects of pH, temperatures, anions, p-ASA concentration, PS, and M-rGO dosages on p-ASA decomposition were studied in the system. Excellent degradation of p-ASA was carried out at a wide range of pH values, which was unattainable by other Fenton-like processes. Under optimal conditions, M-rGO exhibited prominent removal of both p-ASA (98.8 %) and inorganic arsenic (89.8 %). M-rGO had reasonably excellent repeatability and stability, and 77.7 % p-ASA degraded in the third recovered catalyst. The advantages of environmental friendliness, short reaction time, and straightforward synthesis of M-rGO will facilitate the development of heterogeneous Fenton-like catalysts under neutral conditions.
PubMed: 32937710
DOI: 10.1016/j.jhazmat.2020.123032 -
Langmuir : the ACS Journal of Surfaces... Sep 2020Reported here is a new chemical route for the wet chemical functionalization of germanium (Ge), whereby arsanilic acid is covalently bound to a chlorine (Cl)-terminated...
Reported here is a new chemical route for the wet chemical functionalization of germanium (Ge), whereby arsanilic acid is covalently bound to a chlorine (Cl)-terminated surface. This new route is used to deliver high concentrations of arsenic (As) dopants to Ge, via monolayer doping (MLD). Doping, or the introduction of Group III or Group V impurity atoms into the crystal lattice of Group IV semiconductors, is essential to allow control over the electronic properties of the material to enable transistor devices to be switched on and off. MLD is a diffusion-based method for the introduction of these impurity atoms via surface-bound molecules, which offers a nondestructive alternative to ion implantation, the current industry doping standard, making it suitable for sub-10 nm structures. Ge, given its higher carrier mobilities, is a leading candidate to replace Si as the channel material in future devices. Combining the new chemical route with the existing MLD process yields active carrier concentrations of dopants (>1 × 10 atoms/cm) that rival those of ion implantation. It is shown that the dose of dopant delivered to Ge is also controllable by changing the size of the precursor molecule. X-ray photoelectron spectroscopy (XPS) data and density functional theory (DFT) calculations support the formation of a covalent bond between the arsanilic acid and the Cl-terminated Ge surface. Atomic force microscopy (AFM) indicates that the integrity of the surface is maintained throughout the chemical procedure, and electrochemical capacitance voltage (ECV) data shows a carrier concentration of 1.9 × 10 atoms/cm corroborated by sheet resistance measurements.
PubMed: 32787047
DOI: 10.1021/acs.langmuir.0c00408 -
Chemosphere Dec 2020Organic arsenicals are important environment pollutants due to wide use in livestock and toxicity of degradation products. In this work we report about the efficient...
Organic arsenicals are important environment pollutants due to wide use in livestock and toxicity of degradation products. In this work we report about the efficient photodegradation of the p-arsanilic acid (p-ASA) and its decomposition products in the Fe(III)-oxalate assisted approach under nature-relevant conditions. At neutral pH under near-visible UV irradiation the Fe(III) oxalate complexes generate the primary oxidizing intermediate, OH radical (the quantum yield of ϕ ∼ 0.06), which rapidly reacts with p-ASA with high rate constant, (8.6 ± 0.5) × 10 Ms. Subsequent radical reactions result in the complete photooxidation of both p-ASA and basic aromatic photoproducts with the predominant formation of inorganic arsenic species, mainly As(V), under optimal conditions. Comparing with the direct UV photolysis, the presented Fe(III)-oxalate mediated degradation of p-ASA has several advantages: higher efficiency at low p-ASA concentration and complete degradation of organic arsenic by-products without use of short-wavelength UV radiation. The obtained results illustrate that the Fe(III)-oxalate complexes are promising natural photosensitizers for the removal of arsenic pollutants from contaminated waters.
Topics: Arsanilic Acid; Arsenic; Ferric Compounds; Hydrogen-Ion Concentration; Iron; Organic Chemicals; Oxalates; Photolysis; Ultraviolet Rays
PubMed: 32731031
DOI: 10.1016/j.chemosphere.2020.127770 -
The Science of the Total Environment Nov 2020In this study, resin-based hydrated iron oxide (HFOR) composites were prepared and used as a functional adsorbent for the simultaneous removal of p-Arsanilic acid...
In this study, resin-based hydrated iron oxide (HFOR) composites were prepared and used as a functional adsorbent for the simultaneous removal of p-Arsanilic acid (p-ASA) and arsenate (As (V)). The effects of solution pH and coexisting substances on the adsorption of different arsenic species were also investigated. Results showed that the coexisting substances slightly affected the adsorption process of two arsenic species. Analysis of the adsorption behavior, isotherm equilibrium, and adsorption kinetics, as well as that results of the X-ray photoelectron spectroscopy, zeta potential, and other analytical methods revealed that the satisfactory adsorption performance of HFOR can be attributed to the electrostatic interactions induced by the positively charged groups and the coordination of the hydrated iron oxide nanoparticles, which exhibited excellent specific adsorption for both arsenic species. Moreover, HFOR showed high acid and alkali resistance and reusability, as well as a constant co-removal performance for different arsenic species in five consecutive operating cycles (55 mg As/g of As(V) and 18 mg/g of p-ASA). Results of continuous running fixed-bed column experiments confirmed that HFOR enabled excellent simultaneous adsorption for p-ASA and As(V).
PubMed: 32629256
DOI: 10.1016/j.scitotenv.2020.140508 -
The Science of the Total Environment Nov 2020para-arsanilic acid (p-ASA), as a major phenylarsonic feed additive, was used annually in many countries. Once it enters the water environment, p-ASA would be...
para-arsanilic acid (p-ASA), as a major phenylarsonic feed additive, was used annually in many countries. Once it enters the water environment, p-ASA would be transformed into hypertoxic inorganic arsenic species, causing severe arsenic pollution. In this study, magnetic copper ferrite (CuFeO) was applied to activate peroxymonosulfate (PMS) for p-ASA removal and synchronous control of the released inorganic arsenic species. Results showed that CuFeO/PMS system presented favorable oxidation ability and close to 85% of 10 mg/L p-ASA was eliminated under the condition of simultaneous dosing 0.2 g/L CuFeO and 1 mM PMS. The rapid decomposition of p-ASA resulted from homogeneous PMS oxidation and the attack of reactive oxygen species (i.e., SO, HO and O), which was involved the heterogeneous PMS activation through the cycles between Fe(II)/Fe(III) and Cu(II)/Cu(I). Meanwhile, the released inorganic arsenic species during p-ASA degradation were found to be controllable via the adsorption on CuFeO surface and metal hydroxyl groups played the crucial role. CuFeO/PMS system exhibited the stable and efficient performance within the broad range of pH 3.0-11.0. The existence of common anions (Cl, NO, HCO, SO) and humic acid presented the slight inhibition for p-ASA degradation. The reduction of initial p-ASA concentration favored the p-ASA removal. Besides, the catalyst retained a favorable reactivity and stability even after four successive cycles and almost no metal leaching was observed. The rational degradation pathway was mainly involved in the cleavage of AsC bond, oxidation of amino group, substitution and oxidation of hydroxyl group. The transformation of arsenic species could be divided into the release of inorganic arsenic species, the oxidation of As(III) into As(V) and the adsorption of As(V) by CuFeO.
PubMed: 32623153
DOI: 10.1016/j.scitotenv.2020.140587