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1.
J Neurosci ; 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32019827

RESUMO

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus internus (GPi) is an effective treatment for parkinsonian motor signs. Though its therapeutic mechanisms remain unclear, it has been suggested that antidromic activation of the primary motor cortex (M1) plays a significant role in mediating its therapeutic effects. This study tested the hypothesis that antidromic activation of M1 is a prominent feature underlying the therapeutic effect of STN and GPi DBS. Single-unit activity in M1 was recorded using high-density microelectrode arrays in two parkinsonian non-human primates each implanted with DBS leads targeting the STN and GPi. Stimulation in each DBS target had similar therapeutic effects, however antidromic activation of M1 was only observed during STN DBS. Although both animals undergoing STN DBS had similar beneficial effects, the proportion of antidromic-classified cells in each differed, 30% vs 6%. Over four hours of continuous STN DBS, antidromic activation became less robust, whereas therapeutic benefits were maintained. Although antidromic activation waned over time, synchronization of spontaneous spiking in M1 was significantly reduced throughout the four hours. While we cannot discount the potential therapeutic role of antidromic M1 activation at least in the acute phase of STN DBS, the difference in observed antidromic activation between animals, and target sites, raise questions about its hypothesized role as the primary mechanism underlying the therapeutic effect of DBS. These results lend further support that reductions in synchronization at the level of M1 are an important factor in the therapeutic effects of DBS.SIGNIFICANCE STATEMENTRecently there has been great interest and debate regarding the potential role of motor cortical activation in the therapeutic mechanisms of DBS for Parkinson's disease. In this study we used chronically implanted high density microelectrode arrays in primary motor cortex (M1) to record neuronal population responses in parkinsonian non-human primates during STN-DBS and GPi-DBS. Our results suggest a contribution of antidromic activation of M1 during STN-DBS in disrupting synchronization in cortical neuronal populations; however diminishing antidromic activity over time, and differences in observed antidromic activation between animals and target sites with antidromic activation not observed during GPi-DBS, raise questions about its role as the primary mechanism underlying the therapeutic effect of DBS.

2.
Phys Rev Lett ; 124(2): 027203, 2020 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-32004033

RESUMO

Spin waves can probe the Dzyaloshinskii-Moriya interaction (DMI), which gives rise to topological spin textures, such as skyrmions. However, the DMI has not yet been reported in yttrium iron garnet (YIG) with arguably the lowest damping for spin waves. In this work, we experimentally evidence the interfacial DMI in a 7-nm-thick YIG film by measuring the nonreciprocal spin-wave propagation in terms of frequency, amplitude, and most importantly group velocities using all electrical spin-wave spectroscopy. The velocities of propagating spin waves show chirality among three vectors, i.e., the film normal direction, applied field, and spin-wave wave vector. By measuring the asymmetric group velocities, we extract a DMI constant of 16 µJ/m^{2}, which we independently confirm by Brillouin light scattering. Thickness-dependent measurements reveal that the DMI originates from the oxide interface between the YIG and garnet substrate. The interfacial DMI discovered in the ultrathin YIG films is of key importance for functional chiral magnonics as ultralow spin-wave damping can be achieved.

3.
Neurol Sci ; 2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31901124

RESUMO

INTRODUCTION: To improve the accuracy of ultrasound techniques for the assessment of carotid stenosis, we designed a novel carotid artery stenosis ultrasound scale (CASUS), and evaluated its accuracy, reliability, and its value in predicting the occurrence of cardiovascular and cerebrovascular diseases in a prospective study. METHODS: A total of 750 patients with first-time ischemic stroke and hospitalized within 24 h were enrolled in the study. Using color Doppler ultrasound (CDUS), the degree of stenosis and blood flow (BF) in bilateral internal carotid arteries (ICA) and the V1-V3 segment of vertebral arteries (VA) was assessed. Cubic simulation curves for BF and global blood flow (GBF) over the stenosis score (SS), total stenosis score (TSS), and radiological imaging- total stenosis score (RI-TSS) were fitted and compared. The receiver operating characteristic (ROC) curves using TSS, RI-TSS, or GBF to predict various ischemic stroke endpoints were also analyzed and compared. RESULTS: There was a linear relationship between SS and BF both ICA and VA (R2 were 0.734 and 0.783, respectively, both P < 0.05). Both TSS and RI-TSS with GBF showed an inverse "S" curve relationship (R2 was 0.839 and 0.843, all P < 0.05). The AUC values of TSS-based and RI-TSS-based predictions of each endpoint were all greater than 0.7 (all P < 0.05), but the differences of the AUC values between TSS, RI-TSS, and GBF were not statistically significant (all P > 0.05). CONCLUSIONS: The novel CASUS can better reflect the level of cerebral reperfusion in patients with ischemic stroke and can better predict the occurrence of cardiovascular and cerebrovascular diseases.

4.
IEEE Trans Cybern ; 50(3): 1037-1046, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30668488

RESUMO

In this paper, a novel robust controller for continuous stochastic polynomial fuzzy systems is investigated. The aim of the proposed method is to eliminate the restrictive assumptions that the local input matrix Bi must be uniform and the sliding mode surface proposed did not consider the stochastic perturbations, which are required in most existing results. At the same time, the proposed method could handle the system with matched external disturbances. First, a novel vector integral sliding mode surface (VISMS) is constructed according to the basis matrix [Formula: see text]. The sliding mode surface parameter matrix [Formula: see text] can be obtained through the provided sum of squares conditions. Second, by using an improved Lyapunov method and a new proposed lemma, a novel sliding mode control law is designed to keep the state of the closed-loop systems on the VISMS approximately since the initial time. Third, a practical example and a numerical one are provided to illustrate the validity of the proposed approach.

5.
IEEE Trans Cybern ; 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31647455

RESUMO

In this article, by use of sliding-mode control, a descriptor stochastic fuzzy system with time-varying delay is considered. First, a new sliding-mode surface is proposed. By use of it, the fuzzy system with different input matrices could be studied. At the same time, the controlled system still has strong robustness to external disturbance. Second, since time delay is variable, there is not the time-delay term in the function of the new sliding-mode surface. It makes the controller construct hard. Third, the process of constructing the controller is different from the traditional method. The process of designing the controller does not use the border of external disturbance. Using a new self-adaptive method, the considered system reaches and is kept on the surface. Unlike the earlier sliding-mode controller, the virtue of this controller is that the fluctuation of the controller is small. Finally, two simulations are given to illustrate the effect of this method.

6.
Sensors (Basel) ; 19(9)2019 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-31052577

RESUMO

The hydropower generator unit (HGU) is a vital piece of equipment for frequency and peaking modulation in the power grid. Its vibration signal contains a wealth of information and status characteristics. Therefore, it is important to predict the vibration tendency of HGUs using collected real-time data, and achieve predictive maintenance as well. In previous studies, most prediction methods have only focused on enhancing the stability or accuracy. However, it is insufficient to consider only one criterion (stability or accuracy) in vibration tendency prediction. In this paper, an intelligence vibration tendency prediction method is proposed to simultaneously achieve strong stability and high accuracy, where vibration signal preprocessing, feature selection and prediction methods are integrated in a multi-objective optimization framework. Firstly, raw sensor signals are decomposed into several modes by empirical wavelet transform (EWT). Subsequently, the refactored modes can be obtained by the sample entropy-based reconstruction strategy. Then, important input features are selected using the Gram-Schmidt orthogonal (GSO) process. Later, the refactored modes are predicted through kernel extreme learning machine (KELM). Finally, the parameters of GSO and KELM are synchronously optimized by the multi-objective salp swarm algorithm. A case study and analysis of the mixed-flow HGU data in China was conducted, and the results show that the proposed model performs better in terms of predicting stability and accuracy.

7.
Nat Nanotechnol ; 14(7): 691-697, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31011219

RESUMO

Spin waves may constitute key components of low-power spintronic devices. Antiferromagnetic-type spin waves are innately high-speed, stable and dual-polarized. So far, it has remained challenging to excite and manipulate antiferromagnetic-type propagating spin waves. Here, we investigate spin waves in periodic 100-nm-wide stripe domains with alternating upward and downward magnetization in La0.67Sr0.33MnO3 thin films. In addition to ordinary low-frequency modes, a high-frequency mode around 10 GHz is observed and propagates along the stripe domains with a spin-wave dispersion different from the low-frequency mode. Based on a theoretical model that considers two oppositely oriented coupled domains, this high-frequency mode is accounted for as an effective antiferromagnetic spin-wave mode. The spin waves exhibit group velocities of 2.6 km s-1 and propagate even at zero magnetic bias field. An electric current pulse with a density of only 105 A cm-2 can controllably modify the orientation of the stripe domains, which opens up perspectives for reconfigurable magnonic devices.

8.
Talanta ; 198: 501-509, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30876592

RESUMO

As indispensable and strategic elements, Rare Earth Elements (REEs) have been found wide high-tech applications in many modern industries. Their mining, extraction and purification address on economic and environmental significances. This study was the first to report the successful determination and differentiation of rare earth metals using the Nitrogen-doped Carbon Dots (NCDs). NCDs were synthesized via the one-step hydrothermal treatment method starting from folic acid. The as-received NCDs can emit bright blue fluorescence at 440 nm in a high quantum yield of 85% due to the fluorescence enhancement effect of N dopant atoms on NCDs' surface. This as-received NCDs can not only determine REE ions based on the fluorescence quenching effect of the newly-formed REE-NCDs complexes, also distinguish two groups of REEs with significantly different electronic structures. It was found REE ions (Group II REEs: Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+) can only quench fluorescence of the initial NCDs solution, but not change its fluorescence wavelengths. This was contrasted to the similar quenching effect of REE ions (Group I REEs: La3+, Y3+, Lu3+) on NCDs, but further 20 nm red-shift of the fluorescence wavelength (from 439 nm to 458 nm). Taking examples of the selected La3+ and Sm3+, their detection limit were found to be 0.045 µM (the linear range of 0-6 µM, R2 =0.998) and 0.29 µM (the linear range of 0-10 µM, R2 =0.993), respectively. The characterizations of NCDs, based on the ultraviolet and visible spectrophotometry (UV-VIS), X-ray photoelectron spectrometer (XPS) and Fourier Transform infrared spectroscopy (FTIR), helped in revealing the coordination status of rare earth ions on the carboxyl group of the NCDs surface and also mechanisms of their electron and energy transfers.

9.
Chem Commun (Camb) ; 55(18): 2601-2604, 2019 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-30633265

RESUMO

Pulsed laser exfoliation was successfully applied to fabricate few-layer phosphorene from high energy mechanical milling (HEMM) synthesized black phosphorus (BP) powders and crystals. The results show that the polycrystalline phosphorene laser-exfoliated from the HEMM-synthesized BP powders is highly stable in ambient environments, providing proof-of-concept for the low-cost fabrication of highly stable few-layer phosphorene for large-scale applications.

10.
Chem Sci ; 9(37): 7413-7418, 2018 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-30542545

RESUMO

Spin-reorientation-induced magnetodielectric coupling effects were discovered in two layered perovskite magnets, [C6H5CH2CH2NH3]2[MCl4] (M = Mn2+ and Cu2+), via isothermal magnetodielectric measurements on single-crystal samples. Specifically, peak-like dielectric anomalies and spin-flop transitions appeared simultaneously at around ±34 kOe for the canted antiferromagnet (M = Mn2+) at below 44.3 K, while a low-field (1 kOe) controlled magnetodielectric effect was observed in the "soft" ferromagnet (M = Cu2+) at below 9.5 K. These isothermal magnetodielectric effects are highly reproducible and synchronous with the field-induced magnetization at different temperatures, well confirming the essential role of spin reorientation on inducing magnetodielectric coupling effects. These findings strongly imply that the layered perovskite magnets are new promising organic-inorganic hybrid systems to host magnetodielectric coupling effects.

11.
Org Lett ; 20(23): 7689-7693, 2018 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-30495964

RESUMO

The first Rh-catalyzed enantioselective synthesis of a 3,4-polyfused oxindole ring system enabled by carboacylation of acrylic amides based on C-C activation is reported. This transformation provides a new entry to access 3,4-polyfused oxindoles bearing quaternary stereocenters. Tri- to pentacyclic 3,4-fused oxindoles were asymmetrically generated in good yields (up to 95%) with good to excellent enantioselectivity (88%-97% ee). Application in the first total synthesis of xylanigripones A was completed in 6 steps with a 14% overall yield.

12.
J Immunol Res ; 2018: 2413637, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30255104

RESUMO

Objective: To investigate the fetal and maternal outcomes as well as predictors of APOs in women with SLE who conceived when the disease was stable, the so-called "planned pregnancy." Methods. A retrospective multicenter study of 243 patients with SLE who underwent a planned pregnancy was performed. APOs in fetus and mothers were recorded. Results: The average age at conception was 28.9 ± 3.9 years. Duration of SLE prior to pregnancy was 4.4 ± 4.3 years. Fetal APOs occurred in 86 (86/243, 35.4%) patients. Preterm births, intrauterine growth retardation (IUGR), fetal distress, and fetal loss accounted for 22.2%, 14.8%, 11.1%, and 4.9%, respectively. Forty-two preterm infants (42/54, 77.8%) were delivered after the 34th week of gestation. All the preterm infants were viable. Fifty-two patients (52/243, 21.4%) had disease flares, among which 45 cases (45/52, 86.5%) were mild, 6 (6/52, 11.5%) were moderate, and 1 (1/52, 1.9%) was severe. Disease flares were mainly presented as active lupus nephritis (41/52, 78.8%), thrombocytopenia (10/52, 19.2%), and skin/mucosa lesions (9/52, 17.3%). Pregnancy-induced hypertension (PIH) occurred in 29 patients, among which 3 were gestational hypertension and 26 were preeclampsia. Multiple analysis showed that disease flares (OR, 8.1; CI, 3.8-17.2) and anticardiolipin antibody positivity (OR, 7.4; CI, 2.5-21.8) were associated with composite fetal APOs. Conclusion: Planned pregnancy improved fetal and maternal outcomes, presenting as a lower rate of fetal loss, more favorable outcomes for preterm infants, and less severe disease flares during pregnancy.


Assuntos
Serviços de Planejamento Familiar/estatística & dados numéricos , Lúpus Eritematoso Sistêmico/epidemiologia , Complicações na Gravidez/epidemiologia , Adulto , China/epidemiologia , Progressão da Doença , Feminino , Feto , Humanos , Lactente , Recém-Nascido , Masculino , Gravidez , Resultado da Gravidez , Estudos Retrospectivos
13.
Zhonghua Nan Ke Xue ; 24(2): 138-141, 2018 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-30156073

RESUMO

Objective: To explore the strategies of preserving urinary continence in transurethral plasmakinetic enucleation of the prostate (PKEP) for benign prostate hyperplasia (BPH). METHODS: We treated 65 BPH patients by PKEP with preservation of urinary continence (UC-PKEP), which involved protection of the external urethral sphincter in the beginning of surgery, proper preservation of the anterior lobe of the prostate to protect the internal urethral sphincter in the middle, and preservation of the integrity of the bladder neck towards the end. We compared the postoperative status of urinary continence of the patients with that of the 54 BPH cases treated by complete plasmakinetic enucleation of the prostate (Com-PKEP). RESULTS: All the operations were performed successfully with the urinary catheters removed at 5 days after surgery. In comparison with Com-PKEP, UC-PKEP achieved evidently lower incidence rates of urinary incontinence at 24 hours (31.49% vs 13.85%, P <0.05), 1 week (18.52% vs 4.62%, P <0.05), 2 weeks (14.81% vs 3.08%, P <0.05), 1 month (3.70% vs 1.54%, P >0.05), and 3 months (3.70% vs 0%, P >0.05) after catheter removal. Compared with the baseline, the maximum urinary flow rate (Qmax) was significantly improved postoperatively in both the Com-PKEP (ï¼»7.43 ± 3.26ï¼½ vs ï¼»20.58 ± 3.22ï¼½ ml, P <0.05) and the UC-PKEP group (ï¼»8.04 ± 2.28ï¼½ vs ï¼»20.66 ± 3.08ï¼½ ml, P <0.05). CONCLUSIONS: Transurethral PKEP is a safe and effective method for the management of BPH, during which the strategies of avoiding blunt or sharp damage to the external urethral sphincter in the beginning, properly preserving the anterior lobe of the prostate in the middle and preserving the integrity of the bladder neck towards the end may help to achieve rapid recovery of urinary continence.


Assuntos
Tratamentos com Preservação do Órgão/métodos , Hiperplasia Prostática/cirurgia , Ressecção Transuretral da Próstata/métodos , Uretra , Bexiga Urinária , Incontinência Urinária/prevenção & controle , Humanos , Masculino , Período Pós-Operatório , Qualidade de Vida , Ressecção Transuretral da Próstata/efeitos adversos , Resultado do Tratamento , Cateterismo Urinário
14.
Biomed Pharmacother ; 106: 426-433, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29990830

RESUMO

Scabiosa comosa inflorescence is a traditional Mongolian medicine in the treatment of liver diseases. In the study, we investigated the anti-fibrotic efficacy of flavonoid-rich Scabiosa comosa inflorescence extract (TF-SC) in a rat model of CCl4-induced hepatic fibrosis and explored its underlying mechanism in vitro and in vivo. Rats (Wistar, Male, weight 200-250 g) were injected intraperitoneally with CCl4 (1:1v/v in peanut oil, 2 mL/kg body weight) to induce liver fibrosis, followed by treatment with TF-SC or vehicle. In addition, transforming growth factor-ß1 (TGF-ß1)-activated hepatic stellate cells (HSCs) were used for measuring Smad3 phosphorylation. We found decrease in liver function and liver fibrosis markers in serums. Also, TF-SC decreased hydroxyproline content and collagen deposition in liver tissues. TF-SC also decreased the expression of α-SMA, collagen I and fibronectin in CCl4-induced hepatic fibrosis rats. Mechanistically, TF-SC attenuated liver fibrosis by selectively inhibiting Smad3 phosphorylation. In TGF-ß1-stimulated HSCs, TF-SC blocked the interaction between Smad3 and TGF-ß type I receptor (TßRI), suppressed subsequent phosphorylation and nuclear translocation of Smad3, and down-regulated the transcription of fibrotic genes. In conclusion, the study demonstrated that TF-SC was an effective therapeutic agent for treatment of hepatic fibrosis, and provided a molecular basis through which TF-SC exerts its anti-fibrotic effects.


Assuntos
Tetracloreto de Carbono , Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Flavonoides/farmacologia , Cirrose Hepática Experimental/prevenção & controle , Fígado/efeitos dos fármacos , Extratos Vegetais/farmacologia , Substâncias Protetoras/farmacologia , Proteína Smad3/metabolismo , Fator de Crescimento Transformador beta1/farmacologia , Animais , Biomarcadores/sangue , Doença Hepática Induzida por Substâncias e Drogas/sangue , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Doença Hepática Induzida por Substâncias e Drogas/patologia , Citoproteção , Dipsacaceae/química , Relação Dose-Resposta a Droga , Flavonoides/isolamento & purificação , Células Estreladas do Fígado/efeitos dos fármacos , Células Estreladas do Fígado/metabolismo , Células Estreladas do Fígado/patologia , Fígado/metabolismo , Fígado/patologia , Cirrose Hepática Experimental/sangue , Cirrose Hepática Experimental/induzido quimicamente , Cirrose Hepática Experimental/patologia , Masculino , Fosforilação , Fitoterapia , Extratos Vegetais/isolamento & purificação , Plantas Medicinais , Substâncias Protetoras/isolamento & purificação , Ratos Wistar , Receptor do Fator de Crescimento Transformador beta Tipo I/metabolismo , Transdução de Sinais/efeitos dos fármacos
15.
Neuropsychiatr Dis Treat ; 14: 511-515, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29491710

RESUMO

Introduction: The incidence of corpus callosum infarction is low, and sudden cognitive dysfunction caused by corpus callosum infarction is very rare. We report two cases of acute corpus callosum infarction with sudden cognitive impairment, and the related basis, clinical manifestations, diagnosis, differential diagnosis, treatment, and prognosis of this disease are reviewed. Cases presentation: The two patients had sudden and severe memory impairment and spatial orientation disorder. Their cognitive function scores were significantly lower, and their MRI demonstrated clear corpus callosum infarction. Through treatment, the symptoms improved significantly. Discussion: This paper reports two cases with corpus callosum infarction with sudden cognitive impairment, and its relevant background is also reviewed, which will help doctors with the classification diagnosis of cerebral infarction and understanding of corpus callosum infarction.

16.
Org Lett ; 20(4): 1102-1105, 2018 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-29400472

RESUMO

This study presents new mechanistic insights into the frustrated Lewis pairs (FLPs) catalyzed C-H activation of heteroarenes. Besides the generally accepted concerted C-H activation, a novel stepwise carbene type pathway is proposed as an alternative mechanism. The reaction mechanisms can be varied by tuning the distance between Lewis acid and Lewis base due to catalyst-substrate match. These results should expand the understanding of the structure and function of FLPs for catalyzed C-H activation.

17.
J Am Chem Soc ; 140(3): 900-903, 2018 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-29323490

RESUMO

Previous studies of a thermophilic alcohol dehydrogenase (ht-ADH) demonstrated a range of discontinuous transitions at 30 °C that include catalysis, kinetic isotope effects, protein hydrogen-deuterium exchange rates, and intrinsic fluorescence properties. Using the Förster resonance energy transfer response from a Trp-NADH donor-acceptor pair in T-jump studies of ht-ADH, we now report microsecond protein motions that can be directly related to active site chemistry. Two distinctive transients are observed: a slow, kinetic process lacking a temperature break, together with a faster transient that is only detectable above 30 °C. The latter establishes a link between enzyme activity and microsecond protein motions near the cofactor binding site, in a region distinct from a previously detected protein network that communicates with the substrate binding site. Though evidence of direct dynamical links between microsecond protein motions and active site bond cleavage events is extremely rare, these studies highlight the potential of T-jump measurements to uncover such properties.


Assuntos
Álcool Desidrogenase/química , Transferência Ressonante de Energia de Fluorescência/métodos , Geobacillus stearothermophilus/enzimologia , Sítios de Ligação , Domínio Catalítico , Geobacillus stearothermophilus/química , Cinética , Modelos Moleculares , Movimento (Física) , NAD/química , Conformação Proteica , Temperatura Ambiente
18.
Water Sci Technol ; 78(10): 2183-2192, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30629546

RESUMO

It is of practical significance to promote the transformation of Fe in acid mine drainage (AMD) into ferric hydroxysulfate minerals with strong ability to remove heavy metals or metalloids. To investigate the types of biogenic ferric hydroxysulfate minerals generated in AMD by Acidithiobacillus ferrooxidans (A. ferrooxidans), different pH and K+ concentrations are tested for the formation of precipitates in media containing 160 mmol/L Fe2+. The Cr(VI) removal efficiencies of ferric hydroxysulfate minerals in AMD with different acidities are also compared. Results indicate that the mineralizing abilities of the initial pH levels (pH 3.0 > pH 2.5 > pH 2.0) and K+ concentrations (53.3 mmol/L > 3.2 mmol/L ≈ 0.8 mmol/L) differ, with cumulative Fe precipitation efficiencies of 58.7%, 58.0%, and 44.2% (K+ = 53.3 mmol/L), and 58.7%, 29.9%, and 29.6% (pH 3.0) after 96 h of A. ferrooxidans incubation, respectively. X-ray diffraction indicates that K-jarosites are formed in the treatments n(Fe)/n(K) = 0.1 and 3 at pH 2.0-3.0, while only schwertmannite is generated in a system of pH 3.0 and n(Fe)/n(K) = 200. X-ray photoelectron spectroscopy reveals that HCrO4- may be adsorbed as an inner-sphere complex on schwertmannite when the AMD pH is 3.0.


Assuntos
Cromo/química , Minerais/química , Potássio/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Cromo/análise , Compostos Férricos , Concentração de Íons de Hidrogênio , Mineração , Poluentes Químicos da Água/análise
19.
Sci Rep ; 7(1): 14700, 2017 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-29089620

RESUMO

It is well known the thermal properties of three-dimensional (3-D) hybrid graphene (GR)-carbon nanotube (CNT) structures are not superior to that of the individual GR and CNT, however, the 3-D hybrid GR-CNT structures can effectively improve the thermal properties of polymer matrix. Therefore, understanding the thermal energy transport in the interface between polymer matrix and 3-D hybrid GR-CNT structure is essential. Here, the enhancement mechanism of interfacial thermal transport of hybrid GR-CNT structure was explored by applying non-equilibrium molecular dynamics (NEMD) simulations. Three different types of hybrid GR-CNT structures were built. The influences of CNT radius and CNT type for the hybrid GR-CNT on the interfacial thermal properties were also analyzed. Computational results show that among the three different types of hybrid GR-CNT structures, the Model-I, i.e., the covalent bond hybrid GR-CNT structures are of the best interfacial thermal properties. Meanwhile, the CNT radius of hybrid GR-CNT structure has a great influence on the interfacial thermal properties.

20.
Leuk Res ; 63: 28-33, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29096333

RESUMO

OBJECTIVE: To determine the role and mechanism of EphB4 in dasatinib (DAS) resistance in advanced chronic myeloid leukemia (CML), we explored the EphB4-mediated apoptotic and matrix microenvironment pathway in human CML and K562 cell lines. METHOD: Heparinized bone marrow samples were obtained from enrolled five patients (identified as A to E and visits identified by number) at initial diagnosis (A1-E1) and in the DAS-resistance advanced phase (A2-E2). Meanwhile, highly DAS-resistant cells, named K562-R cells, were obtained from K562-W cells with increasing concentrations of DAS. Stable under-expressing EphB4 cells (K562-R-EphB4-sh) were obtained from K562-R cells by RNA interference. K562-W, K562-R and K562-R-EphB4-sh cells (108) were respectively injected subcutaneously on the dorsal surface of BALB/C female nude mice to establish the xenografts models. RESULT: The mRNA/protein of EphB4 was overexpressed in the DAS-resistant A2-E2 in comparison with the A1-E1 human cell lines. Further, compared with K562-R cells, the expressions of EphB4 and p-Rac1/Cdc42 protein/mRNA were significantly downregulated in K562-R-EphB4-sh cells (P<0.01). K562-R cells showed the highest DAS resistance (IC50 10.54±0.67µg/ml), but K562-R-EphB4-sh cells became sensitive to DAS (IC50 1.02±0.1µg/ml, P<0.01). The expression of EphB4/p-RhoA/MCL-1 protein was gradually increased in the stimulating of EphrinB2-Fc, which partly made K562-R-EphB4-sh cells restore sensitivity to DAS (4.18±0.30µg/ml). Meanwhile, the K562-R-EphB4-sh xenografts group had relatively good efficacy compared to K562-R xenografts nude mice receiving the same dose of DAS. The analysis of xenografts tissue also suggested parallel results with the overexpression of EphB4/RhoA/ROCK1/PTEN/MCL-1 in K562-R xenografts, which decreased in the A2-R-EphB4-sh xenografts (P<0.01). CONCLUSIONS: The present study found that a new DAS resistance pathway of EphB4 overexpression was triggered by EphrinB2-Fc, which induced the resistance to DAS by activating RhoA/ROCK1/PTEN/MCL-1 signaling.


Assuntos
Apoptose , Dasatinibe/farmacologia , Resistencia a Medicamentos Antineoplásicos , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Receptor EphB4/metabolismo , Adulto , Idoso , Animais , Antineoplásicos/farmacologia , Proliferação de Células , Feminino , Humanos , Células K562 , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Pessoa de Meia-Idade , Transdução de Sinais/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
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