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1.
Nat Sci Sleep ; 14: 1113-1124, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35707548

RESUMO

Purpose: Accumulated studies revealed that electromagnetic field can affect human brain and sleep, and the extremely low-frequency electromagnetic field, Schumann resonance, may have the potential to reduce insomnia symptoms. The purpose of this study was to investigate the responses of patients with insomnia to a non-invasive treatment, Schumann resonance (SR), and to evaluate its effectiveness by subjective and objective sleep assessments. Patients and Methods: We adopted a double-blinded and randomized design and 40 participants (70% female; 50.00 ± 13.38 year) with insomnia completed the entire study. These participants were divided into the SR-sleep-device group and the placebo-device group and were followed up for four weeks. The study used polysomnography (PSG) to measure objective sleep and used sleep diaries, Pittsburgh Sleep Quality Inventory (PSQI), Epworth Sleepiness Scale (ESS), and visual analogy of sleep satisfaction to measure subjective sleep. The 36-Item Short-Form Health Survey (SF-36) was used to evaluate quality of life. Chi-square test, Mann-Whitney U-test, and Wilcoxon test were used to analyze the data. Results: About 70% of the subjects were women, with an average age of 50±13.38 years and an average history of insomnia of 9.68±8.86 years. We found that in the SR-sleep-device group, objective sleep measurements (sleep-onset-latency, SOL, and total-sleep-time, TST) and subjective sleep questionnaires (SOL, TST, sleep-efficiency, sleep-quality, daytime-sleepiness, and sleep-satisfaction) were significantly improved after using the SR-sleep-device; in the placebo-device group, only such subjective sleep improvements as PSQI and sleep-satisfaction were observed. Conclusion: This study demonstrates that the SR-sleep-device can reduce the insomnia symptoms through both objective and subjective tests, with minimal adverse effects. Future studies can explore the possible mechanism of SR and health effects and, with a longer tracking time, verify the effectiveness and side effects.

2.
Electromagn Biol Med ; 40(3): 384-392, 2021 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-33632057

RESUMO

Extremely low-frequency electromagnetic field (ELF-EMF) exposures influence many biological systems. These effects are mainly related to the intensity, duration, frequency, and pattern of the ELF-EMF. Our intent was to characterize the effect of specific pulsed electromagnetic fields on the in vitro proliferation of MCF-7 adenocarcinoma and MDA-MB-231 breast cancer cell lines and one non-cancerous M10 breast epithelial cell line. The following four important parameters of ELF-EMF were examined: frequencies (7.83 ± 0.3, 23.49 ± 0.3, and 39.15 ± 0.3 Hz), flux density (0.5 and 1 mT), exposure duration (12, 24, and 48 h), and the exposure methodology (continuous exposure versus switching exposure). The viability of MDA-MB-231 cells exposed to the optimized ELF-EMF pattern (7.83 ± 0.3 Hz, 1 mT, and 6 h switching exposure) was 40.1%. By contrast, the optimized ELF-EMF parameters that were most cytotoxic to breast cancer MDA-MB-231 cells were not damaging to normal M10 cells. In vitro studies also showed that exposure of MDA-MB-231 cells to the optimized ELF-EMF pattern promoted Ca2+ influx and resulted in apoptosis. These data confirm that exposure to this specific ELF-EMF pattern can influence cellular processes and inhibit cancer cell growth. The specific ELF-EMF pattern determined in this study may provide a potential anti-cancer treatment in the future.


Assuntos
Neoplasias da Mama , Campos Eletromagnéticos , Apoptose , Proliferação de Células , Feminino , Humanos , Células MCF-7
3.
Electromagn Biol Med ; 40(1): 150-157, 2021 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-33111597

RESUMO

Extremely low-frequency electromagnetic field (ELF-EMF) exposure influences many biological systems; these effects are mainly related to the intensity, duration, frequency, and pattern of the ELF-EMF. In this study, exposure to square wave with 7.83±0.3 Hz (sweep step 0.1 Hz) was shown to inhibit the growth of B16F10 melanoma tumor cells. In addition, the distribution of the magnetic field was calculated by Biot-Savart Law and plotted using MATLAB. In vitro studies demonstrated a decrease in B16F10 cell proliferation and an increase of Ca2+ influx after 48 h of exposure to the square wave. Ca2+ influx was also partially blocked by inhibition of voltage-gated L- and T-type Ca2+ channels. The data confirmed that the specific time-varying ELF-EMF had an anti-proliferation effect on B16F10 cells and that the inhibition is related to Ca2+ and voltage-gated L- and T-type Ca2+ channels.


Assuntos
Canais de Cálcio Tipo L/metabolismo , Canais de Cálcio Tipo T/metabolismo , Campos Eletromagnéticos , Melanoma Experimental/patologia , Proliferação de Células/efeitos da radiação , Humanos , Transdução de Sinais/efeitos da radiação
4.
Front Plant Sci ; 11: 518, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32499797

RESUMO

Meiosis plays an essential role in the production of gametes and genetic diversity of posterities. The normal double-strand break (DSB) repair is vital to homologous recombination (HR) and occurrence of DNA fragment exchange, but the underlying molecular mechanism remain elusive. Here, we characterized a completely sterile Osmfs1 (male and female sterility 1) mutant which has its pollen and embryo sacs both aborted at the reproductive stage due to severe chromosome defection. Map-based cloning revealed that the OsMFS1 encodes a meiotic coiled-coil protein, and it is responsible for DSB repairing that acts as an important cofactor to stimulate the single strand invasion. Expression pattern analyses showed the OsMFS1 was preferentially expressed in meiosis stage. Subcellular localization analysis of OsMFS1 revealed its association with the nucleus exclusively. In addition, a yeast two-hybrid (Y2H) and pull-down assay showed that OsMFS1 could physically interact with OsHOP2 protein to form a stable complex to ensure faithful homologous recombination. Taken together, our results indicated that OsMFS1 is indispensable to the normal development of anther and embryo sacs in rice.

5.
Electromagn Biol Med ; 38(2): 149-157, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30889982

RESUMO

This paper presents a method to inhibit B16F10 cancer cells using extremely low-frequency electromagnetic fields (ELF-EMFs) and to evaluate cell viability using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The study examined the effect of a natural EMF resonance frequency (7.83 Hz) and a power line frequency (60 Hz) on B16F10 cancer cells for 24 and 48 h. The B16F10 cancer cells were also exposed to sweep frequencies in several sweep intervals to quantitatively analyze the viability of cancer cells. The results yielded a 17% inhibition rate under 7.83 Hz compared with that of the control group. Moreover, sweep frequencies in narrow intervals (7.83 ± 0.1 Hz for the step 0.05 Hz) caused an inhibition rate of 26.4%, and inhibitory effects decreased as frequency sweep intervals increased. These results indicate that a Schumann resonance frequency of 7.83 Hz can inhibit the growth of cancer cells and that using a specific frequency type can lead to more effective growth inhibition.


Assuntos
Campos Eletromagnéticos , Melanoma Experimental/patologia , Neoplasias Cutâneas/patologia , Animais , Sobrevivência Celular/efeitos da radiação , Camundongos , Transdução de Sinais/efeitos da radiação
6.
ACS Appl Mater Interfaces ; 11(1): 706-713, 2019 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-30499295

RESUMO

The interface at the metal oxide-carbon hybrid heterojunction is the source to the well-known "synergistic effect" in catalysis. Understanding the structure-function properties is key for designing more advanced catalyst-support systems. Using a model MnIII-O x single-layer catalyst on carbon, we herein report a full elucidation to the catalytic synergism at the hybrid heterojunction in the oxygen reduction reaction (ORR). The successful fabrication of the single-layer catalyst from bottom-up is fully characterized by the X-ray absorption fine structure and high-resolution transmission electron microscopy. For oxygen electrocatalysis over this model hybrid heterostructure, our results, from both theory and experiment, show that the synergistic ORR truly undergoes a cooperated two-step electrocatalysis with catalytic promotion (Δ Eonset = 60 mV) near the heterojunction and over the single-layer catalyst through an interfacial electronic interplay, rather than an abstruse transition towards a one-step dissociative pathway. Finally, we report a superior peroxide-reducing activity of 432.5 mA cm-2 mg(M)-1 over the MnIII-O x single-layer.

7.
Rev Sci Instrum ; 89(6): 065003, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29960512

RESUMO

In this study, an automatic glycated hemoglobin (HbA1c) impedance measurement system (AHMS) is developed for the detection of HbA1c. The proposed device removes some of the drawbacks of common instruments for HbA1c detection (i.e., large, expensive, difficult to operate) by detecting the ratio of HbA1c to Hb. The method is label-free and requires only a small sample volume; no additional reagents are required. The manpower consumption and bulk of the instrument are also reduced. The method provides a simple way to analyze impedance deviation and effectively reduces the effort required by the operator. The ratios of HbA1c to Hb (4%-7%) are well distinguished, and the experiment is used to build a database for AHMS. To check the reliability of the proposed system, a sample test using three different ratios of HbA1c is applied in this study. The sample test uses HbA1c to Hb ratios of 4.7%, 5.6%, and 6.8%, and the determined experimental values are 4.93%, 5.8%, and 6.83%, respectively. The sample test has an accuracy of approximately 96.99%. Based on these results, the proposed system for detecting HbA1c through protein coverage is both effective and feasible.


Assuntos
Análise Química do Sangue/instrumentação , Hemoglobinas Glicadas/análise , Automação , Impedância Elétrica , Eletrodos , Desenho de Equipamento , Miniaturização , Reprodutibilidade dos Testes
8.
Chem Sci ; 7(6): 3640-3644, 2016 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30008996

RESUMO

Carbon dioxide is expected to be employed as an inexpensive and potential feedstock of C1 sources for the mass production of valuable chemicals and fuel. Versatile chemical transformations of CO2, i.e. insertion of CO2 producing bicarbonate/acetate/formate, cleavage of CO2 yielding µ-CO/µ-oxo transition-metal complexes, and electrocatalytic reduction of CO2 affording CO/HCOOH/CH3OH/CH4/C2H4/oxalate were well documented. Herein, we report a novel pathway for the reductive activation of CO2 by the [NiIII(OMe)(P(C6H3-3-SiMe3-2-S)3)]- complex, yielding the [NiIII(κ1-OCO˙-)(P(C6H3-3-SiMe3-2-S)3)]- complex. The formation of this unusual NiIII(κ1-OCO˙-) complex was characterized by single-crystal X-ray diffraction, EPR, IR, SQUID, Ni/S K-edge X-ray absorption spectroscopy, and Ni valence-to-core X-ray emission spectroscopy. The inertness of the analogous complexes [NiIII(SPh)], [NiII(CO)], and [NiII(N2H4)] toward CO2, in contrast, demonstrates that the ionic [NiIII(OMe)] core attracts the binding of weak σ-donor CO2 and triggers the subsequent reduction of CO2 by the nucleophilic [OMe]- in the immediate vicinity. This metal-ligand cooperative activation of CO2 may open a novel pathway promoting the subsequent incorporation of CO2 in the buildup of functionalized products.

9.
Med Biol Eng Comput ; 53(5): 393-403, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25681949

RESUMO

For end-stage renal disease patients undergoing hemodialysis, thrombosis caused by stenosis hinders the long-term use of vascular access. However, traditional spectral bruit analysis techniques for detecting the severity of vascular access stenosis are not robust. Accordingly, the present study proposes an automated method for mimicking a trained practitioner in performing the auscultation process. In the proposed approach, the bruit obtained using a standard phonoangiographic method is transformed into the time-frequency domain, and two spectro-temporal features, namely the auditory spectrum flux and the auditory spectral centroid, are then extracted. The distributions of the two features are analyzed using a multivariate Gaussian distribution (MGD) model. Finally, the distribution parameters of the MGD model are used to detect the presence (or otherwise) of vascular access stenosis. The validity of the proposed approach is investigated using the phonoangiography signals obtained from 16 hemodialysis patients with straight arteriovenous grafts over the upper arm region. The results show that the MGD covariance matrix coefficient of the auditory spectral centroid feature yields an accuracy of 83.87 % in detecting significant vascular access stenosis. Thus, the proposed method has significant potential for the applications of vascular access stenosis detection.


Assuntos
Auscultação/métodos , Constrição Patológica/diagnóstico , Técnicas de Diagnóstico Cardiovascular , Diálise Renal/efeitos adversos , Processamento de Sinais Assistido por Computador , Dispositivos de Acesso Vascular/efeitos adversos , Idoso , Constrição Patológica/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Espectral/métodos
10.
Inorg Chem ; 53(24): 12822-31, 2014 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-25494947

RESUMO

Red Ca0.99Al(1-4δ/3-x)Si(1+δ+x)N(3-x)C(x):Eu(2+)0.01 (δ = 0.345; x = 0-0.2) nitride phosphors exhibit a blue-shifted emission with increased eye sensitivity function and excellent thermal stability. The variations in the photoluminescence in the Ca0.99Al(1-4δ/3-x)Si(1+δ+x)N(3-x)C(x):Eu(2+)0.01 (δ = 0.345; x = 0-0.2) system are thoroughly investigated. The enhanced emission energy and the improved thermal stability with increasing x are dominated by the second-sphere shrinkage effect via the substitution of small Si(4+) for large Al(3+) with simultaneous charge compensation. Related proofs of the second-sphere shrinkage effect control for photoluminescence are confirmed via high-resolution neutron powder diffraction, EXAFS, and (29)Si solid-state NMR techniques.

11.
Dalton Trans ; 43(46): 17358-65, 2014 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-25327834

RESUMO

The structural properties of (Bi0.5Na0.5)Ti1-xZrxO3 (where 0 ≤ x ≤ 0.7) have been investigated using powder diffraction and X-ray absorption spectroscopy. Diffraction measurements on (Bi0.5Na0.5)TiO3 confirm that both monoclinic Cc and rhombohedral R3c phases are present at room temperature. Doping small amounts of Zr into the B site of (Bi0.5Na0.5)TiO3 initially stabilizes the rhombohedral phase before the orthorhombic Pnma phase begins to form at x = 0.5. Analysis of the Ti K-edge and Zr L3-edge XANES spectra show that the crystallographic phase change has very little effect on the local structure of Ti(4+)/Zr(4+) cations, suggesting that there is little change in the cation off-center displacement within the BO6 octahedra with each successive phase change.

12.
Electrophoresis ; 35(16): 2392-400, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24610717

RESUMO

A battery-powered portable instrument system for the single-HeLa-cell trapping and analyses is developed. A method of alternating current electrothermal (ACET) and DEP are employed for the cell trapping and the method of impedance spectroscopy is employed for cell characterizations. The proposed instrument (160 mm × 170 mm × 110 mm, 1269 g) equips with a highly efficient energy-saving design that promises approximately 120 h of use. It includes an impedance analyzer performing an excitation voltage of 0.2-2 Vpp and a frequency sweep of 11-101 kHz, function generator with the sine wave output at an operating voltage of 1-50 Vpp with a frequency of 4-12 MHz, cell-trapping biochip, microscope, and input/output interface. The biochip for the single cell trapping is designed and simulated based on a combination of ACET and DEP forces. In order to improve measurement accuracy, the curve fitting method is adopted to calibrate the proposed impedance spectroscopy. Measurement results from the proposed system are compared with results from a precision impedance analyzer. The trapped cell can be modeled for numerical analyses. Many advantages are offered in the proposed instrument such as the small volume, real-time monitoring, rapid analysis, low cost, low-power consumption, and portable application.


Assuntos
Espectroscopia Dielétrica/instrumentação , Análise de Célula Única/instrumentação , Análise Serial de Tecidos/instrumentação , Impedância Elétrica , Desenho de Equipamento , Células HeLa , Humanos , Software
13.
Dalton Trans ; 43(18): 6909-18, 2014 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-24667811

RESUMO

The structural, magnetic and electrical properties of the mixed Ti-Mn oxides Sr(1-x)La(x)Ti(0.5)Mn(0.5)O3 (0 ≤ x ≤ 0.5) are reported. At room temperature the oxides have a cubic structure in space group Pm3m for x ≤ 0.25 and rhombohedral in R3c for 0.3 ≤ x ≤ 0.50. X-ray absorption spectroscopic measurements demonstrate the addition of La(3+) is compensated by the partial reduction of Mn(4+) to Mn(3+). Variable temperature neutron diffraction measurements show that cooling Sr(0.6)La(0.4)Ti(0.5)Mn(0.5)O3 results in a first order transition from rhombohedra to an orthorhombic structure in Imma. Complex magnetic behaviour is observed. The magnetic behaviour of the mixed valent (Mn(3+/4+)) examples is dominated by ferromagnetic interactions, although cation disorder frustrates long range magnetic ordering.

14.
J Am Chem Soc ; 136(4): 1514-9, 2014 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-24410074

RESUMO

The complex metal oxide SrCo0.5Ru0.5O(3-δ) possesses a slightly distorted perovskite crystal structure. Its insulating nature infers a well-defined charge distribution, and the six-fold coordinated transition metals have the oxidation states +5 for ruthenium and +3 for cobalt as observed by X-ray spectroscopy. We have discovered that Co(3+) ion is purely high-spin at room temperature, which is unique for a Co(3+) in an octahedral oxygen surrounding. We attribute this to the crystal field interaction being weaker than the Hund's-rule exchange due to a relatively large mean Co-O distances of 1.98(2) Å, as obtained by EXAFS and X-ray diffraction experiments. A gradual high-to-low spin state transition is completed by applying high hydrostatic pressure of up to 40 GPa. Across this spin state transition, the Co Kß emission spectra can be fully explained by a weighted sum of the high-spin and low-spin spectra. Thereby is the much debated intermediate spin state of Co(3+) absent in this material. These results allow us to draw an energy diagram depicting relative stabilities of the high-, intermediate-, and low-spin states as functions of the metal-oxygen bond length for a Co(3+) ion in an octahedral coordination.

15.
Inorg Chem ; 53(2): 952-60, 2014 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-24364379

RESUMO

The key role played by bismuth in an average intermediate oxidation state in the magnetoelastic spin-gap compounds Ba3BiRu2O9 and Ba3BiIr2O9 has been confirmed by systematically replacing bismuth with La(3+) and Ce(4+). Through a combination of powder diffraction (neutron and synchrotron), X-ray absorption spectroscopy, and magnetic properties measurements, we show that Ru/Ir cations in Ba3BiRu2O9 and Ba3BiIr2O9 have oxidation states between +4 and +4.5, suggesting that Bi cations exist in an unusual average oxidation state intermediate between the conventional +3 and +5 states (which is confirmed by the Bi L3-edge spectrum of Ba3BiRu2O9). Precise measurements of lattice parameters from synchrotron diffraction are consistent with the presence of intermediate oxidation state bismuth cations throughout the doping ranges. We find that relatively small amounts of doping (∼10 at%) on the bismuth site suppress and then completely eliminate the sharp structural and magnetic transitions observed in pure Ba3BiRu2O9 and Ba3BiIr2O9, strongly suggesting that the unstable electronic state of bismuth plays a critical role in the behavior of these materials.

16.
J Environ Sci (China) ; 25(3): 626-36, 2013 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-23923437

RESUMO

This study investigates biogeochemical reductive release of arsenate from beudantite into solution in a crater area in northern Taiwan, using a combination of X-ray absorption near-edge structure (XANES) and atomic absorption spectrometry. Total arsenic (As) concentrations in the soil were more than 200 mg/kg. Over four months of laboratory experiments, less than 0.8% As was released into solution after reduction experiments. The 71% to 83% As was chemically reduced into arsenite (As(III)) and partially weathering into the soluble phase. The kinetic dissolution and re-precipitation of As, Fe, Pb and sulfate in this area of paddy soils merits further study.


Assuntos
Arseniatos/análise , Solo/química , Espectroscopia por Absorção de Raios X/métodos , Geografia , Chumbo/análise , Compostos Orgânicos/análise , Oxirredução , Taiwan
17.
Dalton Trans ; 42(41): 14875-82, 2013 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-23989102

RESUMO

The pyrochlore-defect fluorite phase transition in the mixed-metal zirconate Nd2-xYxZr2O7 (0 ≤ x ≤ 2) solid solution was investigated using synchrotron X-ray and neutron diffraction, as well as X-ray absorption spectroscopy. Diffraction analysis revealed a two-phase region between 1.0 ≤ x ≤ 1.2. In the pyrochlore phase, Zr L3-edge XANES analysis demonstrated a gradual change in the local coordination environment of the B site with increasing Y content that was consistent with an increase in disorder. Although Y L3-edge XANES analysis suggested that the Y cations remained in an ordered coordination environment in the pyrochlore phase, disorder did gradually increase once the fluorite phase formed. It was found that Y cations prefer an ordered coordination environment near the phase boundary whereas Zr cations prefer a disordered coordination environment.

18.
Biosens Bioelectron ; 49: 450-6, 2013 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-23811477

RESUMO

Glycated hemoglobin (HbA1c) is one of the most important diagnostic assays for the long-term mark of glycaemic control in diabetes. This study presents an affinity biosensor for HbA1c detection which is label-free based on the impedance measurement, and it features low cost, low sample volume, and requires no additional reagent in experiments. The ring-shaped interdigital electrodes (RSIDEs) are designed to promote the distribution uniformity and immobilization efficiency of HbA1c, and are further employed to characterize the impedance change and identify various concentrations of HbA1c. The self-assembled monolayer (SAM) of thiophene-3-boronic acid (T3BA) is provided to modify the gold electrode surface. Afterwards, the esterification reaction between HbA1c and T3BA produces a relative change of electrical property on the electrode surface. The RSIDEs with SAM of T3BA exhibit a wide range from 100 to 10 ng/µL producing an approximate logarithmic decrease of impedance, a low detection limit of 1 ng/µL, a good selectivity and short-term stability for HbA1c determination. The remarkable advantages (miniaturization and low-cost) fill the bill of point-care diagnostics for portable sensor development.


Assuntos
Técnicas Biossensoriais/instrumentação , Hemoglobinas Glicadas/análise , Ácidos Borônicos/química , Impedância Elétrica , Eletrodos , Desenho de Equipamento , Ouro/química , Humanos , Limite de Detecção , Tiofenos/química
19.
Inorg Chem ; 52(15): 8409-15, 2013 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-23844979

RESUMO

The pyrochlore-defect fluorite order-disorder transition has been studied for a series of oxides of the type Gd(2-x)Tb(x)Zr2O7 by a combination of diffraction and spectroscopy techniques. Synchrotron X-ray diffraction data suggest an abrupt transition from the coexistence of pyrochlore and defect fluorite phases to a single defect fluorite phase with increasing Tb content. However neutron diffraction data, obtained at λ ≈ 0.497 Å for all Gd-containing samples to minimize absorption, not only provide evidence for independent ordering of the anion and cation sublattices but also suggest that the disorder transition across the pyrochlore-defect fluorite boundary of Ln2Zr2O7 is rather gradual. Such disorder was also evident in X-ray absorption measurements at the Zr L3-edge, which showed a gradual increase in the effective coordination number of the Zr from near 6-coordinate in the pyrochlore rich samples to near 7-coordinate in the Tb rich defect fluorites. These results indicate the presence of ordered domains throughout the defect fluorite region, and demonstrate the gradual nature of the order-disorder transition across the Gd(2-x)Tb(x)Zr2O7 series.

20.
Biosens Bioelectron ; 49: 297-304, 2013 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-23787359

RESUMO

We present an advanced technique improving upon the micron-sized particle trap integrated in biochip systems using a planar structure to generate an adjustable trapping position by utilizing voltage phase-controlled (VPC) method and negative dielectrophoresis (nDEP) theory in high conductivity physiological media. The designed planar and split structure is composed of independent components of measuring and trapping micro-electrodes. Through different voltage configurations on the device, the trapped position of single particles/cells was selected and adjusted in vertical and horizontal directions. The numerical simulations verify our theoretical predictions of the effects at the various voltages. It shows that the trapped position can be adjusted in the vertical (0 to 26 µm) and horizontal (0 to 74 µm) directions. In experiments, the single particles/cells is captured, measured, and then released, with the same process being repeated twice to demonstrate the precision of the positioning. The measurement results determined that particles at various heights result in different magnitude values, while the impedance error is less than 5% for the proposed electrode layout. Finally, the experiments are performed to verify that a particle/cell can be precisely trapped on the selected site in both the vertical and horizontal directions.


Assuntos
Técnicas Biossensoriais/instrumentação , Dispositivos Lab-On-A-Chip , Análise de Célula Única/instrumentação , Impedância Elétrica , Desenho de Equipamento , Células HeLa , Humanos , Microeletrodos , Micromanipulação/instrumentação
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