Your browser doesn't support javascript.
loading
: 20 | 50 | 100
1 - 11 de 11
1.
Sensors (Basel) ; 22(6)2022 Mar 17.
Article En | MEDLINE | ID: mdl-35336496

Thermal compensation control can correct errors caused by the thermal deformation of phased array antenna (PAA) panels. Thermal deformation of the panel is needed to calculate the compensation value. While the PAA is working, thermal deformation is unconditional to measure, but predicting it by temperature is feasible. However, thermal deformation is also affected by other factors, such as the structural shape, assembly method, and material parameters, and it is difficult to measure these parameters of PAA because of the complex structure. In contrast, the measurement method of the temperature and thermal deformation of the PAA in the laboratory is much easier. Therefore, a comprehensive influence parameters (CIPs)-finite element method (FEM) method was proposed in this study, it can extract the influence of above parameters on thermal deformation from temperature and thermal deformation measurement data and build a thermal deformation prediction model. Experiments have verified that the CIPs-FEM can greatly reduce the difficulty of thermal deformation modeling and have a high prediction accuracy.

2.
Anal Methods ; 13(11): 1404-1411, 2021 03 21.
Article En | MEDLINE | ID: mdl-33666211

A method consisting of solid-phase isotope dansylation (derivatization with dansyl chloride) and liquid chromatography-high resolution mass spectrometry (LC-HRMS) was developed for the quantitative analysis of phenolic compounds (phenols) in environmental samples. A magnetic-HLB (hydrophilic lipophilic balanced) material was synthesized and applied as an adsorbent in magnetic solid-phase extraction (MSPE) for the enrichment of the analytical targets. Furthermore, with the solid-phase isotope labeling, the desalting and removal of labeling residuals could be simplified over conventional in-solution labeling. In addition to overcoming the matrix effect by isotope dansylation, the sensitivity for the analysis of phenols by LC-HRMS was remarkably improved by over 100-fold. The method was systematically verified, and good accuracy (86.5-104.9%) and precision (<8.6% and <11.4% for intra- and inter-day, respectively) were achieved for the tested 15 phenols. The limits of detection (LODs) of this method were estimated to be 0.2-5 ng L-1 and 5-100 ng kg-1 in estuary water and sediment samples, respectively. With this method, samples collected from the Daliao River estuary (Panjin, China) were analyzed. It was found that all of the targeted phenols were detected at concentrations ranging from unquantifiable to 485 ng L-1 (the total concentration of analytes found in each sample were in the range 822-957 ng L-1) and unquantifiable to 1368 ng kg-1 (the total concentration of analytes found in each sample were in the range 2251-2992 ng kg-1) in water and sediment, respectively.

3.
Talanta ; 219: 121272, 2020 Nov 01.
Article En | MEDLINE | ID: mdl-32887162

Estrogens distribute widely in the environment as endocrine-disrupting chemicals (EDCs), which have to be monitored to evaluate their environmental impact. Aim to improve the analytical throughput of liquid chromatography-high resolution mass spectrometry (LC-HRMS), a quadruplex stable isotope dansylation method was developed, with which three real samples could be quantitatively analyzed in one injection. As the estrogens were at trace level in complex matrices, magnetic solid-phase extraction (MSPE) was applied to enrich these analytes and remove the interfaces. By integrating MSPE and quadruplex stable isotope dansylation, a solid-phase quadruplex labeling method was developed for the LC-HRMS analysis of estrogen analogues. For the tested seven estrogens, the developed method showed low detection limits (0.1-0.5 ng/L for pond water and 0.01-0.05 µg/kg for poultry manure), good precision (RSD < 5.5%) and accuracy (96.8-108.3%). The method was applied in the determination of estrogens in environmental samples, and the results revealed that all the tested estrogens were present in the estuary water (unquantifiable to 71.2 ng/L) and chicken manure (undetectable to 25.43 µg/kg).


Estrogens , Water Pollutants, Chemical , Chromatography, Liquid , Isotopes , Limit of Detection , Solid Phase Extraction , Tandem Mass Spectrometry , Water Pollutants, Chemical/analysis
4.
J Chromatogr A ; 1613: 460712, 2020 Feb 22.
Article En | MEDLINE | ID: mdl-31759641

A simple magnetization method was developed for the preparation of magnetic materials from conventional solid phase packing though coprecipitation and solvothermal approaches. And the prepared magnetic materials were used for magnetic solid phase extraction (MSPE) of biogenic amines (BAs) from beers. Furthermore, to improve the analytical throughput, a solid phase "on-situ" quadraplex isotope dimethyl labeling method was developed for the quantification of BAs by liquid chromatography-high resolution mass spectrometry (LCHRMS). Compared to conventional in-solution labeling, the "on-situ" labeling could simplify the sample preparation procedure and efficiently remove the residuals such as inorganic salts and excessive labeling reagents. The quadraplex labeling, which enabled three real samples and one internal standard sample to be analyzed simultaneously in a single LCHRMS run. For the tested 8 BAs (cadaverine, phenethylamine, spermine, spermidine, tyramine, histamine, putrescine and tryptamine), LODs of 0.02-0.05 µg/L and LOQs of 0.05-0.1 µg/L were achieved at good reproducibility (RSD of 0.5-4.6% and 2.2-7.0% for intra- and inter-day reproducibility, respectively). With this method, six beer samples were analyzed, and these 8 BAs were all detected in the range of low µg/L to 2.9 mg/L, which were lower than maximal residual level (MRL) required in the regulations of China and EU.


Beer/analysis , Biogenic Amines/analysis , Chromatography, Liquid/methods , Mass Spectrometry/methods , Biogenic Amines/isolation & purification , Isotope Labeling , Limit of Detection , Magnetic Phenomena , Reproducibility of Results , Solid Phase Extraction/methods
6.
Rev Sci Instrum ; 90(7): 075006, 2019 Jul.
Article En | MEDLINE | ID: mdl-31370506

This study demonstrates a new approach for constructing a rotary piezoelectric motor that utilizes an asymmetric stator driven by a single-phase signal. An asymmetric stator with four driving feet is proposed on the basis of the idea of generating asymmetric action on the rotor. This new motor consists of one piezoelectric transducer with two anchors and four driving feet placed in a parallelogram and internally connected to a circular rotor. The four feet vibrate asymmetrically to push the rotor into motion in one direction when a preload is applied. The proposed motor is designed, analyzed, and tested by using a finite element method (FEM). The vibration and impedance characteristics of the stator are measured after fabricating a prototype, and the test results are consistent with the FEM analysis results. The typical output of the prototype is a no-load speed of 176.5 rpm and a maximum torque of 29.4 N mm at an excitation voltage of 274 Vp-p.

7.
Food Chem ; 289: 701-707, 2019 Aug 15.
Article En | MEDLINE | ID: mdl-30955669

A simple modification method was developed for the functionalization of amino terminated carbon nanotubes (CNT-NH2) by using isocyanates as modifiers via the nucleophilic addition reaction. Two types of functionalized magnetic carbon nanotubes (MCNT) were prepared through deposition of magnetic nanoparticles on CNT-NH2 and modification with different isocyanates. p-Tolyl-functionalized MCNT (Tol-MCNT) with better adsorption performance were selected as adsorbent for magnetic solid phase extraction (MSPE), which could extract sulfonamides (SAs) from various milk samples with a enrichment factor of about 30 after optimization. By combining the MSPE with liquid chromatography-high resolution mass spectrometry (LC-HRMS), a new method was developed. Both skimmed and whole milk samples of three brands were analyzed with this method, and 4 SAs including sulfadiazine, sulfisomidine, sulfamethazine and sulfameter were detected with the concentration from unquantifiable to 72 ng/L, which were all well below the maximum residue limits in milk according to the regulations of China and EU.


Isocyanates/chemistry , Milk/chemistry , Nanotubes, Carbon/chemistry , Solid Phase Extraction , Sulfonamides/analysis , Animals , China , Chromatography, Liquid , Europe , Food Analysis , Mass Spectrometry , Nutrition Policy/legislation & jurisprudence , Reproducibility of Results
8.
Rev Sci Instrum ; 89(7): 075002, 2018 Jul.
Article En | MEDLINE | ID: mdl-30068090

A dual stage tuning fork transducer (DSTFT) is designed as a stator for a resonant-type inertial linear motor. The first- and second-layer resonant frequencies of DSTFT are automatically adjusted with a ratio of 1:2 by using an ANSYS optimization design algorithm, and a resonant-type sawtooth-shaped mechanical waveform is generated by composing the two resonant vibrations of DSTFT. An inertial linear motor prototype is fabricated and tested. Experimental results confirmed the effectiveness of the designed transducer. The no-load maximum speed is 21.5 mm/s with a driving voltage of 67.2 Vp-p at a base frequency of 2831 Hz. The linear speed is 10.5 mm/s, and the drag load is 0.02 N at a preload force of 1 N and a driving voltage of 114 Vp-p for the base frequency. The movement direction could be reversed by changing the driving voltage phase.

9.
Rev Sci Instrum ; 88(7): 075002, 2017 Jul.
Article En | MEDLINE | ID: mdl-28764494

A novel, bio-inspired, single-phase driven piezoelectric linear motor (PLM) using an asymmetric stator was designed, fabricated, and tested to avoid mode degeneracy and to simplify the drive mechanism of a piezoelectric motor. A piezoelectric transducer composed of two piezoelectric stacks and a displacement amplifier was used as the driving element of the PLM. Two simple and specially designed claws performed elliptical motion. A numerical simulation was performed to design the stator and determine the feasibility of the design mechanism of the PLM. Moreover, an experimental setup was built to validate the working principles, as well as to evaluate the performance, of the PLM. The prototype motor outputs a no-load speed of 233.7 mm/s at a voltage of 180 Vp-p and a maximum thrust force of 2.3 N under a preload of 10 N. This study verified the feasibility of the proposed design and provided a method to simplify the driving harmonic signal and structure of PLMs.

10.
Opt Express ; 25(15): 18421-18430, 2017 Jul 24.
Article En | MEDLINE | ID: mdl-28789327

We have demonstrated the realization of on-line temperature-controlled random lasers (RLs) in the polyhedral oligomeric silsesquioxanes (POSS) nanoparticles (NPs) as well as Pyrromethene 597 (PM597) laser dye, Fe3O4/SiO2 NPs as well as PM597, and only PM597 doped polymer optical fibers (POFs), respectively. The RLs can be obtained from the gained POFs system caused by multiple scattering of emitted light. The refractive index of the fiber core materials can be easily tuned via temperature due to the polymer with large thermo-optic coefficient. Meanwhile, the scattering mean free path of core in the POFs, which is the key role for the emission wavelength of RLs, is strongly dependent on the matrix refractive index. Thus emission wavelength of RLs in the POF temperature can be controlled through changing the temperature. With the increasing the temperature, the RL emission wavelength has occurred red-shift effect for the POFs.

11.
Se Pu ; 32(5): 547-52, 2014 May.
Article Zh | MEDLINE | ID: mdl-25185319

In order to study the pyrolytic properties of Lysimachia foenum-graecum Hance extract, it was pyrolysed and detected by online pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). The pyrolytic experimental conditions were designed to simulate the real combustion conditions inside a burning cigarette. The sample was heated at 30 degrees C/s from 300 to 900 degrees C (held for 5 s) under the flow of 9% oxygen in nitrogen. The pyrolytic components and volatile components were compared. The results showed that 64 pyrolytic components were detected, with 88.27% of the total peak area, including linoleic acid ethyl ester (10.33%), hexadecanoic acid, ethyl ester (9.12%), 9,12,15-octadecatrienoic acid, (Z,Z,Z) - (8.03%), 2-furan-carboxaldehyde, 5-(hydroxymethyl) - (6.02%), neophytadiene (5.12%), heptadecanoic acid, ethyl ester (4.50%), acetic acid, phenyl ester (3.51%), 5-methoxy-2, 2-di-methylindan-1-one (2.73%). The number of pyrolytic components was more than that of the volatile components, and 20 components were identified in both pyrolytic components and volatile components, including higher fatty acids and their esters, neophytadiene, 2-furancarboxaldehyde, (hydroxymethyl)-, and 2 (5H)-furanone, 3-hydroxy-4, 5-dimethyl-. The on-line pyrolysis was similar to the real cigarette combustion conditions. The method is a simple, rapid and good qualitative method for the pyrolysis.


Gas Chromatography-Mass Spectrometry , Plant Extracts/analysis , Primulaceae/chemistry , Fatty Acids , Hot Temperature , Linoleic Acid , Palmitic Acid
...