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1.
Sensors (Basel) ; 19(9)2019 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-31075916

RESUMO

The extraction of rolling bearings' degradation features has been developed for decades. However, the degradation features always present different trends of different run-to-failure data. To find a consistent indicator of different data will be helpful to establish a general model and explore the nature of bearings' degradation. In this study, we have found there is a trend of similarity between the energy and complexity features. By using the cointegration test, we found the two kinds of features exhibit a certain degree of cointegration relationship. Fused by the cointegration method, we have obtained a novel health indicator which can depict different run-to-failure data in a unified way. The difference between the energy features and complexity features can be explained by the novel health indicator. The indicator has "two-stage" characters. The first stage is the zero-line stage and the second stage is the quickly raise stage, which presents like an exponential function. It is easy to think about using an exponential degradation model to model this indicator. Next, we have compared the indicator to root mean square (RMS) by using the exponential degradation model. It shows that the indicator is more suitable for the exponential degradation model. In this paper, we used eleven run-to-failure data to verify the generality and "two-stage" characters of the proposed indicator. The result shows that the novel indicator is general and effective and that it will promote the development of bearings' prognostics.


Assuntos
Algoritmos , Análise de Falha de Equipamento , Vibração
2.
Sci Rep ; 5: 8510, 2015 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-25728980

RESUMO

Periconceptional supplementation with folic acid reduces the occurrence of neural tube defects (NTDs). The association between maternal abnormalities in homocysteine metabolism (e.g., hyperhomocysteinaemia, folate deficiency and low vitamin B12) and the risk of NTDs-affected pregnancies has been widely evaluated in recent years, although the results are conflicting. To investigate this inconsistency, we performed a meta-analysis of 32 studies, involving 1,890 NTD-affected mothers and 3,995 control mothers, to develop an understanding of the relationship between maternal biomarkers related to one-carbon metabolism and NTD. A random-effects model was used to calculate the ratio of means (RoM) between the cases and controls, along with the 95% confidence intervals (CIs). A significant increase in homocysteine levels was observed in NTD-affected mothers compared with controls (RoM: 1.16, 95% CI: 1.09-1.23, P = 1.8 × 10(-6)). The pooled analysis also revealed that NTD-affected mothers had significantly lower levels of folate (RoM: 0.93, 95% CI: 0.88-0.97, P = 0.002), vitamin B12 (RoM: 0.91, 95% CI: 0.87-0.95, P = 3.6 × 10(-5)) and red blood cell folate (RoM: 0.92, 95% CI: 0.86-0.98, P = 0.01). Therefore, altered plasma levels of biomarkers related to one-carbon metabolism are associated with NTD-affected pregnancies.


Assuntos
Biomarcadores/sangue , Carbono/metabolismo , Defeitos do Tubo Neural/sangue , Estudos de Casos e Controles , Intervalos de Confiança , Eritrócitos/metabolismo , Feminino , Ácido Fólico/sangue , Homocisteína/sangue , Humanos , Vitamina B 12/sangue
3.
Talanta ; 104: 39-43, 2013 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-23597886

RESUMO

The impedance of a capacitively coupled contactless conductivity detector (C(4)D) in capillary electrophoresis (CE) was measured by an impedance analysis method. The influence of solution conductivity and capillary dimension on impedance parameters was investigated. Under the experimental conditions used, 86-99.9% of the total impedance of a C(4)D is composed by its imaginary part from the capillary wall capacitor. With increasing inner diameter of capillary and solution conductivity in detection zone, the wall capacitance increases, which results in the increase in the response signal of C(4)D. But the wall capacitance is only 0.5-12% of the predicted value according to a cylinder capacitor model. As the change in solution resistance is detected in a resonant C(4)D (RC(4)D), the sensitivity of contactless conductivity detection in CE is improved. The application of an end-to-end differential RC(4)D (DRC(4)D) system in CE was demonstrated in the determination of 10 amino acids. The running buffer consisted of 2M acetic acid and 0.1% hydroxyethylcellulose (pH 2.1). The limit of detection for amino acids is in the range of 0.1-0.4 µM. Under our experimental conditions, the sensitivity of DRC(4)D enhances by a factor of 15-29 as compared with C(4)D.


Assuntos
Aminoácidos/análise , Capacitância Elétrica , Condutividade Elétrica , Impedância Elétrica , Eletroforese Capilar/métodos
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