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1.
Adv Exp Med Biol ; 1232: 263-269, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893419

RESUMO

Ahematological and morphological investigation was made of the effects of pulsed magnetic field (PMF) stimulus on oxidized erythrocyte membrane using the smear method and spectroscopic measurement. Tert-butyl hydroperoxide (tBHP) was used for oxidative stress, and verapamil was used as reduction agent on red blood cells (RBCs). Our PMF stimulator system was designed to generate a maximum intensity of 0.27 T at a transition time of 0.102 ms. The morphology of oxidized RBCs, and oxidative stressed RBCs after treatment with a reducing agent were observed before and after PMF. Light absorbance of hemoglobin (Hb) was measured in the membrane as well as plasma, through hemolysis of RBCs. Absorbance for a sample exposed to PMF before the oxidation treatment was lower than that for a sample not exposed to PMF in the plasma. This means that PMF plays a role in preventing hemolysis of erythrocyte membrane from oxidative stress. Our results were confirmed using an osmotic fragility test. Hemolysis in the case of PMF treatment is 28% lower than that of non-PMF treatment. As a result, PMF stimulus is proposed to achieve an improvement of RBCs aggregation and prevent RBCs from oxidative stress, and could be used in various clinical fields related to peripheral vascular diseases. For further clinical application, we need to optimize PMF intensity and stimulated duration.


Assuntos
Eritrócitos , Hemólise , Campos Magnéticos , Estresse Oxidativo , Membrana Eritrocítica , Eritrócitos/patologia , Eritrócitos/efeitos da radiação , Hemólise/efeitos da radiação , Humanos , Campos Magnéticos/efeitos adversos
2.
Arch Microbiol ; 202(1): 77-83, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31485710

RESUMO

Several studies have investigated the effects of ionizing and non-ionizing radiations on microorganisms. However, the interaction between the magnetic field radiations and bacteria is less studied. The aim of our study was to study the effect of static magnetic field on the biofilm formation in Pseudomonas aeruginosa and its isogenic sod mutants. Our results revealed that the exposure to the static magnetic field (200 mT) increases significantly the swarming in the wild strain. The fliC gene expression did not show significant difference after 6 h exposure of the wild-type strain. The release of some compounds of the biofilm matrix such as rhamnolipids has been considerably enhanced after 6 h of exposure in the wild type. On the other hand, the pyocyanin and biofilm production was increased significantly in all strains compared to controls. Furthermore, our results revealed that the biofilm formation was confirmed by the pslA and ppyR gene expressions.


Assuntos
Biofilmes/efeitos da radiação , Campos Magnéticos , Pseudomonas aeruginosa/fisiologia , Flagelina/genética , Regulação Bacteriana da Expressão Gênica/efeitos da radiação , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/efeitos da radiação
3.
J Environ Sci (China) ; 87: 205-212, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791493

RESUMO

This study aims to investigate the effect of a magnetic field on nitrous oxide (N2O) emission from a sequencing batch reactor treating low-strength domestic wastewater at low temperature (10°C). After running for 124 days in parallel, results indicated that the conversion rate of N2O for a magnetic field-sequencing batch reactor (MF-SBR) decreased by 34.3% compared to that of a conventional SBR (C-SBR). Meanwhile, the removal efficiencies for total nitrogen (TN) and ammonia nitrogen (NH4-N) of the MF-SBR were 22.4% and 39.5% higher than those of the C-SBR. High-throughput sequencing revealed that the abundances of AOB (Nitrosomonas), NOB (Nitrospira) and denitrifiers (Zoogloea), which could reduce N2O to N2, were promoted significantly in the MF-SBR. Enzyme activities (Nir) and gene abundances (nosZ nirS and nirK) for denitrification in the MF-SBR were also notably higher compared to C-SBR. Our study shows that application of a magnetic field is a useful approach for inhibiting the generation of N2O and promoting the nitrogen removal efficiency by affecting the microbial characteristics of sludge in an SBR treating domestic wastewater at low temperature.


Assuntos
Reatores Biológicos , Campos Magnéticos , Óxido Nitroso/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias , Temperatura Baixa , Desnitrificação , Nitrificação , Nitrogênio , Nitrosomonas
4.
Chemosphere ; 240: 124962, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574447

RESUMO

Pre-magnetized Fe0 (Pre-Fe0) was for the first time applied as heterogeneous catalyst to enhance the oxidation efficiency of electro-Fenton (EF) for the degradation of p-nitrophenol (PNP). The parameters including current, initial pH and pre-Fe0 dosage of Pre-Fe0/EF process were optimized and compared with other two processes (conventional Fe0/EF and electro-oxidation) to confirm its advantage. The rate constants of PNP removal were 1.40-3.82 folds of those by Fe0/EF process under various experimental conditions. The application of pre-Fe0 as catalyst could extend the working pH range from 3.0 to neutral conditions for PNP removal and reduce the Fe0 dosage from 2 to 0.5 mM corresponding to Fe0/EF, avoiding the second pollution of iron sludge. The superiority of Pre-Fe0/EF process was also verified to improve the degradation and mineralization of other phenols and antibiotics. Furthermore, a possible pathway of PNP degradation was revealed by the identification of intermediates and organic acids, and the possible mechanism of pre-Fe0 efficiently enhanced the EF efficiency was proposed. This work demonstrated that such a novel heterogeneous EF process using pre-Fe0 catalyst was clean and promising for the degradation of refractory organic pollutants.


Assuntos
Peróxido de Hidrogênio/química , Ferro/química , Campos Magnéticos , Nitrofenóis/metabolismo , Esgotos/química , Poluentes Químicos da Água/análise , Catálise , Concentração de Íons de Hidrogênio , Oxirredução
5.
Food Chem ; 309: 125651, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31678674

RESUMO

The effects of low frequency magnetic field on myoglobin (Mb) oxidation stability were evaluated by treatments at 0, 3, 6, 9, 12 mT and storage for 10 h. The results showed that Mb oxidation was inhibited under all magnetic field treatments, due to the increase of total sulfhydryl and free amino groups (9 or 12 mT) from unfolding of Mb clusters (3, 9, 12 mT) as well as ß-turn and ß-sheet structures (9 or 12 mT). The unfolding also induced (i) the destruction or burial of iron porphyrin and tyrosine residues; (ii) the exposure of tryptophan; (iii) more uniform Mb particle size distribution (3, 9, 12 mT) and increased zeta potential (3, 6, 12 mT). Overall, magnetic field promoted exposed active groups as the preferred oxidation target, thus decreasing the oxidation rate of central iron atoms. It also promoted Mb stability by redistributing particle size and increasing zeta potential.


Assuntos
Mioglobina/química , Aminas/análise , Campos Magnéticos , Oxirredução , Tamanho da Partícula , Conformação Proteica em Folha beta , Estabilidade Proteica , Desdobramento de Proteína , Compostos de Sulfidrila/análise
6.
J Environ Manage ; 253: 109680, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31634748

RESUMO

Microalgae produce increased lipid content accompanied by a significant decrease in cell density with decreasing nitrate concentration. Magnetic fields (MF) have been reported as a factor that could accelerate metabolism and growth in microalgae culture. Thus, this study aimed to optimize the influence of MF and nitrate concentration (sodium nitrate, N) on the growth and lipid productivity of Nannochloropsis oculata. A single-factor experiment integrated with response surface methodology (RSM) via central composite design (CCD) was performed. The results showed that the maximum specific growth rate (0.24 d-1) and maximum lipid productivity (38 mg L-1 d-1) obtained in this study were higher than those of the control culture (by 166% and 103%, respectively). This study also found that the two-way interaction term MF × N had a significant effect on cell growth but not on lipid production. It was concluded that to design appropriate MF for enhanced lipid productivity due to cell growth, further research must focus on developing an understanding of the relationship between the bioeffects of the magnetic field and the proteomic changes involved in lipid accumulation strategies. This approach would enable the design of conditions to obtain inexpensive high-value products from N. oculata.


Assuntos
Microalgas , Estramenópilas , Biomassa , Lipídeos , Campos Magnéticos , Proteômica
7.
Bioresour Technol ; 295: 122283, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31669874

RESUMO

Enhancing Acid Red B (ARB) decolorization by growing cells of a halotolerant yeast Candida tropicalis SYF-1 with static magnetic field (SMF) was investigated. Activity of key enzymes and membrane phospholipid fatty acids (PLFAs) were analyzed for estimating the change of metabolic activity and membrane salt-stress response, respectively. Possible enhancement mechanisms were revealed through comparative transcriptome analysis. The results showed that 95.0 mT SMF enhanced ARB decolorization by growing cells of a yeast SYF-1, as well as cell growth and halotolerance capability. Activity of intracellular lignin peroxidase (LiP) and laccase (Lac) was 1.51- and 1.47-fold higher with 95.0 mT SMF than that without SMF, respectively. Unsaturation degree and chain length of dominant PLFAs was increased by 95.0 mT SMF treatment. Several functional protein encoding unigenes related to organics biodegradation, cell growth and halotolerance were 1.17- to 4.19-fold up-regulated in response to 95.0 mT SMF.


Assuntos
Compostos Azo , Candida tropicalis , Biodegradação Ambiental , Lacase , Campos Magnéticos
8.
J Chem Phys ; 151(22): 225101, 2019 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-31837685

RESUMO

The ability of night-migratory songbirds to sense the direction of the Earth's magnetic field is increasingly attributed to a photochemical mechanism in which the magnetic field acts on transient radical pairs in cryptochrome flavoproteins located in the birds' eyes. The magnetically sensitive species is commonly assumed to be [FAD•- TrpH•+], formed by sequential light-induced intraprotein electron transfers from a chain of tryptophan residues to the flavin adenine dinucleotide chromophore. However, some evidence points to superoxide, O2 •-, as an alternative partner for the flavin radical. The absence of hyperfine interactions in O2 •- could lead to a more sensitive magnetic compass, but only if the electron spin relaxation of the O2 •- radical is much slower than normally expected for a small mobile radical with an orbitally degenerate electronic ground state. In this study we use spin dynamics simulations to model the sensitivity of a flavin-superoxide radical pair to the direction of a 50 µT magnetic field. By varying parameters that characterize the local environment and molecular dynamics of the radicals, we identify the highly restrictive conditions under which a O2 •--containing radical pair could form the basis of a geomagnetic compass sensor. We conclude that the involvement of superoxide in compass magnetoreception must remain highly speculative until further experimental evidence is forthcoming.


Assuntos
Criptocromos/química , Flavina-Adenina Dinucleotídeo/química , Superóxidos/química , Campos Magnéticos , Modelos Químicos , Simulação de Dinâmica Molecular
9.
J Chem Phys ; 151(20): 204101, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31779321

RESUMO

The magnetic response of a particle that tunnels in a double-well potential is considered. The Hamiltonian of the model includes the Zeeman, spin-orbit, and other interactions. The spin state changes due to the motion of electrons in the electric field rather than the action of the magnetic field of nucleus on the electrons. At realistic values of the model parameters, the spin-orbit interaction leads to magnetic effects that resemble those in the well-known radical pair mechanism (RPM) model. In particular, the probability of electron transfer depends on the direction of the magnetic field. At the same time, the model under consideration has distinctions that make it reasonable when searching for a mechanism of nonspecific magnetic biological effects. In particular, unlike in the RPM, the magnitude of the magnetic effect is not limited to a narrow range of the hyperfine interaction. The model enables molecular rotations. This could explain an asymmetry in response to the inversion of the magnetic field vector, which has been observed in experiments.


Assuntos
Campos Magnéticos , Modelos Químicos , Teoria Quântica
10.
J Chem Phys ; 151(20): 201102, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31779325

RESUMO

Throughout nature, both free radicals and transient radical reaction intermediates are vital to many biological functions. Coenzyme B12 is a case in point. This organometallic cofactor generates a radical pair upon activation in its dependent enzymes by substrate binding and following photolysis. The resulting cob(ii)alamin/5'-deoxyadenosyl radical pair has unusual magnetic properties that present a challenge to detailed investigation at ambient temperatures. Here, we use femtosecond transient absorption spectroscopy adapted for magnetic field exposure to reveal that the spin dynamics of the B12 radical pair are sufficiently fast for magnetic field effects to be observed on the ultrafast reaction kinetics. Moreover, the large difference in g-values between the radicals of the pair means that effects of the Δg mechanism are observed for the first time for a radical pair system exposed to magnetic fields below 1 T. Spin dynamic simulations allow a value of the cob(ii)alamin radical g-value (2.105) at ambient temperature to be extracted and, because the spin dynamic time scale is faster than the diffusional rotation of the cob(ii)alamin radical, the observed value corresponds to the anisotropic g|| value for this radical.


Assuntos
Fotólise , Teoria Quântica , Vitamina B 12/química , Radicais Livres/química , Campos Magnéticos , Estrutura Molecular , Temperatura Ambiente
11.
Analyst ; 144(24): 7192-7199, 2019 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-31696868

RESUMO

The magic angle coil spinning (MACS) technique has been introduced as a very promising extension for solid state NMR detection, demonstrating sensitivity enhancements by a factor of 14 from the very first time it has been reported. The main beneficiary of this technique is the scientific community dealing with mass- and volume-limited, rare, or expensive samples. However, more than a decade after the first report on MACS, there is a very limited number of groups who have continued to develop the technique, let alone it being widely adopted by practitioners. This might be due to several drawbacks associated with the MACS technology until now, including spectral linewidth, heating due to eddy currents, and imprecise manufacturing. Here, we report a device overcoming all these remaining issues, therefore achieving: (1) spectral resolution of approx 0.01 ppm and normalized limit of detection of approx. 13 nmol s0.5 calculated using the anomeric proton of sucrose at 3 kHz MAS frequency; (2) limited temperature increase inside the MACS insert of only 5 °C at 5 kHz MAS frequency in an 11.74 T magnetic field, rendering MACS suitable to study live biological samples. The wafer-scale fabrication process yields MACS inserts with reproducible properties, readily available to be used on a large scale in bio-chemistry labs. To illustrate the potential of these devices for metabolomic studies, we further report on: (3) ultra-fine 1H-1H and 13C-13C J-couplings resolved within 10 min for a 340 mM uniformly 13C-labeled glucose sample; and (4) single zebrafish embryo measurements through 1H-1H COSY within 4.5 h, opening the gate for the single embryo NMR studies.


Assuntos
Embrião não Mamífero/metabolismo , Glucose/análise , Metabolômica , Ressonância Magnética Nuclear Biomolecular/instrumentação , Peixe-Zebra/embriologia , Animais , Caenorhabditis elegans , Campos Magnéticos , Metabolômica/métodos
12.
Phys Chem Chem Phys ; 21(41): 22849-22856, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31612167

RESUMO

Hyperpolarized metabolites are very attractive contrast agents for in vivo magnetic resonance imaging studies enabling early diagnosis of cancer, for example. Real-time production of concentrated solutions of metabolites is a desired goal that will enable new applications such as the continuous investigation of metabolic changes. To this end, we are introducing two NMR experiments that allow us to deliver high levels of polarization at high concentrations (50 mM) of an acetate precursor (55% 13C polarization) and acetate (17% 13C polarization) utilizing 83% para-state enriched hydrogen within seconds at high magnetic field (7 T). Furthermore, we have translated these experiments to a portable low-field spectrometer with a permanent magnet operating at 1 T. The presented developments pave the way for a rapid and affordable production of hyperpolarized metabolites that can be implemented in e.g. metabolomics labs and for medical diagnosis.


Assuntos
Técnicas de Química Analítica/métodos , Meios de Contraste/síntese química , Campos Magnéticos , Acetatos/química , Acetatos/metabolismo , Meios de Contraste/química , Hidrogênio/química , Imagem por Ressonância Magnética/instrumentação
13.
Chem Commun (Camb) ; 55(91): 13733-13736, 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31661100

RESUMO

The tough challenges for the convenient and quantitative determination of circulating miRNAs (cmiRNAs) in the peripheral blood are low abundance, high interference and lack of direct digital readout. Here, we developed dual-enhanced magnetobiosensors based on cascaded nucleic acid circuits, which integrate catalyzed hairpin assembly (CHA) with the hybridization chain reaction (HCR), for sensitive, portable and digital quantitative detection of circulating miRNAs in serum by a personal glucose meter (PGM).


Assuntos
Técnicas Biossensoriais/métodos , Campos Magnéticos , MicroRNAs/sangue , Ácidos Nucleicos/química , Glucose/química , Humanos , Hibridização de Ácido Nucleico
14.
Int J Nanomedicine ; 14: 7549-7560, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31571863

RESUMO

Background: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignant tumor in the world. Studies in recent years have demonstrated that cancer stem cells (CSCs) are present in many tumor tissues, including HNSCC, and CSCs are the root cause of tumor recurrence and metastasis. Thus, taking new treatment measures to target the killing of CSCs that are resistant to chemotherapy and radiotherapy is key to the success of cancer treatment. Methods: We explored a method for preparing anti-CD44 antibody-modified superparamagnetic iron oxide nanoparticles (SPIONPs). Biocompatibility was evaluated by a CCK-8 assay. The CSCs were obtained by a 3D cell culture technique from Cal-27 (human oral squamous cell carcinoma) cells, and then the CSCs were identified by quantitative real-time polymerase chain reaction (qRT-PCR). The targeting efficiency of the CD44-SPIONPs to CSCs was confirmed by Prussian blue staining and visualized by laser scanning confocal microscopy (LSCM). Flow cytometry was used to detect the apoptosis of CSCs after alternating magnetic field (AMF) treatment. The efficacy of tumor growth inhibition by CD44-SPIONP-mediated magnetic hyperthermia therapy was evaluated with tumor xenografts in nude mice. Results: The CD44-SPIONPs exhibited no negative effect on CSCs, indicating good biocompatibility. After SPIONPs were cocultured with stem cells, the majority of CD44-SPIONPs labeled with FITC penetrated the cell membrane into the cytoplasm. After AMF treatment, CD44-SPIONPs induced CSCs to undergo programmed death. The inhibitory ratio of the treated group was 33.43%, and necrotic areas in the tumor tissue were mainly distributed around the magnetic fluid. Conclusion: These results demonstrate that it is possible to kill CSCs using targeted magnetic nanoparticles and an AMF and that magnetic fluid hyperthermia significantly inhibited the growth of grafted Cal-27 tumors in mice.


Assuntos
Apoptose , Receptores de Hialuronatos/metabolismo , Campos Magnéticos , Nanopartículas de Magnetita/uso terapêutico , Carcinoma de Células Escamosas de Cabeça e Pescoço/terapia , Animais , Linhagem Celular Tumoral , Proliferação de Células , Endocitose , Regulação Neoplásica da Expressão Gênica , Humanos , Nanopartículas de Magnetita/ultraestrutura , Masculino , Camundongos Endogâmicos BALB C , Camundongos Nus , Células-Tronco Neoplásicas/patologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia
15.
J Phys Chem Lett ; 10(19): 5917-5922, 2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31509419

RESUMO

Nuclear magnetic relaxation provides invaluable quantitative site-specific information on the dynamics of complex systems. Determining dynamics on nanosecond time scales requires relaxation measurements at low magnetic fields incompatible with high-resolution NMR. Here, we use a two-field NMR spectrometer to measure carbon-13 transverse and longitudinal relaxation rates at a field as low as 0.33 T (proton Larmor frequency 14 MHz) in specifically labeled side chains of the protein ubiquitin. The use of radiofrequency pulses enhances the accuracy of measurements as compared to high-resolution relaxometry approaches, where the sample is moved in the stray field of the superconducting magnet. Importantly, we demonstrate that accurate measurements at a single low magnetic field provide enough information to characterize complex motions on low nanosecond time scales, which opens a new window for the determination of site-specific nanosecond motions in complex systems such as proteins.


Assuntos
Ressonância Magnética Nuclear Biomolecular/métodos , Proteínas/química , Isótopos de Carbono , Cinética , Campos Magnéticos , Movimento (Física) , Prótons , Ubiquitina/química
16.
Bioelectromagnetics ; 40(8): 539-552, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31564068

RESUMO

The present analysis revisits the impact of extremely low-frequency magnetic fields (ELF-MF) on melatonin (MLT) levels in human and rat subjects using both a parametric and non-parametric approach. In this analysis, we use 62 studies from review articles. The parametric approach consists of a Bayesian logistic regression (LR) analysis and the non-parametric approach consists of a Support Vector analysis, both of which are robust against spurious/false results. Both approaches reveal a unique well-ordered pattern, and show that human and rat studies are consistent with each other once the MF strength is restricted to cover the same range (with B ≲ 50 µT). In addition, the data reveal that chronic exposure (longer than ∼22 days) to ELF-MF appears to decrease MLT levels only when the MF strength is below a threshold of ~30 µT ( log B thr [ µ T ] = 1 . 4 - 0 . 4 + 0 . 7 ), i.e., when the man-made ELF-MF intensity is below that of the static geomagnetic field. Studies reporting an association between ELF-MF and changes to MLT levels and the opposite (no association with ELF-MF) can be reconciled under a single framework. Bioelectromagnetics. 2019;40:539-552. © 2019 Bioelectromagnetics Society.


Assuntos
Campos Magnéticos , Melatonina/metabolismo , Animais , Teorema de Bayes , Humanos , Modelos Logísticos , Ratos
17.
Artigo em Russo | MEDLINE | ID: mdl-31513170

RESUMO

This article provides information on currently proven effective treatment methods for patients with joint diseases, by using magnetic fields with various physical characteristics. A wide range of biotropic parameters allows obtaining various primary physicochemical changes in biological tissues, which was a rationale for including magnetic therapy (MT) in the combination treatment of degenerative-dystrophic and inflammatory diseases. Analysis of scientific publications suggests that there are a large number of randomized, placebo-controlled studies providing evidence for reduced pain, improved joint functional activity and quality of life in patients with knee osteoarthritis under magnetic fields with varying inductions, frequencies, and exposures. There are few randomized clinical trials identifying the efficiency of MT for a number of other joint diseases and after arthroplasty. Despite the fact that there are differences in methodological approaches, it is possible to draw a general conclusion on the scientific validity of using MT in the complex treatment and rehabilitation programs for patients with joint diseases and on the prospects of further developments in this area.


Assuntos
Artropatias/terapia , Campos Magnéticos , Medicina Baseada em Evidências , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Resultado do Tratamento
18.
Chem Asian J ; 14(21): 3898-3914, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31545553

RESUMO

Simultaneous incorporation of both CoII and CoIII ions within a new thioether S-bearing phenol-based ligand system, H3 L (2,6-bis-[{2-(2-hydroxyethylthio)ethylimino}methyl]-4-methylphenol) formed [Co5 ] aggregates [CoII CoIII 4 L2 (µ-OH)2 (µ1,3 -O2 CCH3 )2 ](ClO4 )4 ⋅H2 O (1) and [CoII CoIII 4 L2 (µ-OH)2 (µ1,3 -O2 CC2 H5 )2 ](ClO4 )4 ⋅H2 O (2). The magnetic studies revealed axial zero-field splitting (ZFS) parameter, D/hc=-23.6 and -24.3 cm-1 , and E/D=0.03 and 0.00, respectively for 1 and 2. Dynamic magnetic data confirmed the complexes as SIMs with Ueff /kB =30 K (1) and 33 K (2), and τ0 =9.1×10-8  s (1), and 4.3×10-8  s (2). The larger atomic radius of S compared to N gave rise to less variation in the distortion of tetrahedral geometry around central CoII centers, thus affecting the D and Ueff /kB values. Theoretical studies also support the experimental findings and reveal the origin of the anisotropy parameters. In solutions, both 1 and 2 which produce {CoIII 2 (µ-L)} units, display solvent-dependent catechol oxidation behavior toward 3,5-di-tert-butylcatechol in air. The presence of an adjacent CoIII ion tends to assist the electron transfer from the substrate to the metal ion center, enhancing the catalytic oxidation rate.


Assuntos
Catecol Oxidase/química , Cobalto/química , Complexos de Coordenação/síntese química , Sulfetos/química , Enxofre/química , Catecol Oxidase/metabolismo , Cobalto/metabolismo , Complexos de Coordenação/química , Complexos de Coordenação/metabolismo , Cristalografia por Raios X , Peróxido de Hidrogênio/análise , Cinética , Ligantes , Campos Magnéticos , Modelos Moleculares , Estrutura Molecular , Oxirredução , Sulfetos/metabolismo , Enxofre/metabolismo
19.
Artigo em Inglês | MEDLINE | ID: mdl-31547412

RESUMO

Human neuropsychological reactions and brain activities when driving electric vehicles (EVs) are considered as an issue for traffic and public safety purposes; this paper examined the effect of the static magnetic field (SMF) derived from EVs. A lane change task was adopted to evaluate the driving performance; and the driving reaction time test and the reaction time test were adopted to evaluate the variation of the neuro-psychological cognitive functions. Both the sham and the real exposure conditions were performed with a 350 µT localized SMF in this study; 17 student subjects were enrolled in this single-blind experiment. Electroencephalographs (EEGs) of the subjects were adopted and recorded during the experiment as an indicator of the brain activity for the variations of the driving performance and of the cognitive functions. Results of this study have indicated that the impact of the given SMF on both the human driving performance and the cognitive functions are not considerable; and that there is a correlation between beta sub-band of the EEGs and the human reaction time in the analysis.


Assuntos
Condução de Veículo/estatística & dados numéricos , Automóveis/classificação , Cognição/efeitos da radiação , Campos Magnéticos/efeitos adversos , Tempo de Reação/efeitos da radiação , Feminino , Hong Kong , Humanos , Masculino , Método Simples-Cego , Adulto Jovem
20.
Chemosphere ; 226: 891-897, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31509918

RESUMO

Eucalyptus globulus pre-treated by static magnetic fields of 30, 60, 120, 150 and 400 mT (mT) before sowing were used in a 45-day experiment to remediate soil containing Cd, Hg, Pb, Zn, Cr and Cu. The influence of magnetic fields on its remediation efficiency was evaluated. Magnetic fields with strength of 30, 60, 120 and 150 mT increased the biomass yield of the species by 3.1, 19.4, 48.1 and 60.9%, respectively, while 400 mT decreased the yield by 16.7%. Comparing with the control exposed only to the earth's geomagnetic field, all plants pre-treated by static magnetic field had significantly higher metal concentrations with the highest values achieved in the field of 400 mT. Higher transpiration rate of the plants along with exposure to static magnetic fields induced lower soil moisture content and was beneficial to environmental control because it could reduce the leachate during the phytoremediation process. Among all static magnetic field treatments, 150 mT was the best to improve the phytoremediation and alleviate the environmental risk, which shortened the time to purify Cd, Pb and Cu by 27.8-73.2%, 27.3-74.7% and 2.5-50.6%, respectively and intercepted 31.6-86.1% of the leachate. Therefore, static magnetic field with appropriate intensity is a suitable candidate to improve phytoremediation efficiency through enhancing the biomass production, toxin uptake and leachate interception.


Assuntos
Biodegradação Ambiental , Biomassa , Eucalyptus/fisiologia , Campos Magnéticos , Metais Pesados/análise , Poluentes do Solo/análise , Solo/química , Eucalyptus/crescimento & desenvolvimento
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