Wyniki wyszukiwania - Biblioteka Nauki

1

An analytical model for the tool center point placement in Robotic Roller Forming

100%

Stewens T. , Liu Y. , Wang L. , Min J.

Computer Methods in Materials Science

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2024

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tom Vol. 24, No. 2

39--48

EN

Robotic Roller Forming (RRF) is a novel process using an articulated robotic manipulator that can bend Ultra-High Strength materials into thin-walled profiles. For high strength or difficult-to-form sheet materials, a laser can be employed to synchronously heat and soften the local material during RRF. The aim of RRF is to establish itself as a highly flexible process for rapid prototyping as well as for small batch production. However, in finished parts formed with different materials, a new defect that shapes the profile like that of a hook was observed. To overcome this defect and to improve the adaptability of the process, a new analytical model is suggested for the automatic calculation of the tool center point based on the given process parameters. The model was compared to the previous state, where the hook defect was noticeably reduced. Additionally, the control of the bend radius was studied, and the resulting bend radius diverged from the target radius by 0.04 mm (2.45%). Further, when examining the reproducibility, the same bend angles could be achieved as in previous experiments using the constant laser power density. Finally, the development of the bend allowance was studied in various experiments. The analytical model for RRF is a promising method for calculating tool placement and controlling the bend radius in a freeform environment.

2

Mineralogy characteristics, stability conditions, and formation pathways of synthetic pyrrhotite formed by heating pyrite at 700℃

88%

Wang Z. , Wang L. , He Y. , Duan J. , Fan B.

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2023

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tom T. 39, z. 1

23--34

EN

Pyrite is a sulfide mineral and is widely distributed in nature. Pyrite may transform into pyrrhotite when heated at high temperatures. In order to support processing engineering techniques and industrial applications of pyrite and pyrrhotite, it is necessary to investigate synthetic pyrrhotite, which is formed by heating pyrite in air, based on existing research. In this work, the mineralogical characteristics and stability conditions of synthetic pyrrhotite formed by heating pyrite at elevated temperatures were studied. The possible formation pathway was verified using a solid-phase reaction. X-ray-diffraction results revealed that synthetic pyrrhotite differs from natural pyrrhotite in the paragenetic association of minerals. Natural pyrrhotite and magnetite coexist in the natural pyrrhotite sample. Synthetic pyrrhotite formed by heating pyrite at 700℃ for 1 h has the paragenetic association with hematite and a small amount of pyrite and magnetite. All pyrrhotite samples were monoclinic pyrrhotite-4C (Fe7S8) and exhibit minimal differences in terms of lattice parameters. Synthetic pyrrhotite-4C was stable under 0.5–2 h of heating at 700℃ in air. It had the highest relative content by heating for 1 h. It was eventually transformed into hematite with heating periods exceeding 3 h, as was the case for pyrite and magnetite. In air, synthetic pyrrhotite-4C is mainly formed via two pathways: (1) pyrite → pyrrhotite-4C and (2) pyrite → magnetite → pyrrhotite-4C. Pathway (1) is more favorable than pathway (2). This transformation cannot be achieved by the reaction between hematite and sulfur.

PL

Piryt jest minerałem siarczkowym szeroko rozpowszechnionym w przyrodzie. Piryt może przekształcić się w pirotyn podczas ogrzewania w wysokich temperaturach. W celu wsparcia technik inżynierii mineralnej i przemysłowego zastosowania pirytu i pirotynu, konieczne jest zbadanie syntetycznego pirotynu w oparciu o istniejące badania, który powstaje w wyniku ogrzewania pirytu w powietrzu. W pracy zbadano właściwości mineralogiczne i warunki trwałości syntetycznego pirotynu powstałego w wyniku ogrzewania pirytu w podwyższonej temperaturze. Możliwą ścieżkę powstawania zweryfikowano za pomocą reakcji w fazie stałej. Wyniki dyfrakcji rentgenowskiej ujawniły, że syntetyczny pirotyn różni się od naturalnego pirotynu w paragenetycznych asocjacjach minerałów. Naturalny pirotyn i magnetyt współistnieją w próbce naturalnego pirotynu. Syntetyczny pirotyn powstały w wyniku ogrzewania pirytu w temperaturze 700℃ przez 1 godz. wykazuje asocjację paragenetyczną z hematytem oraz niewielką ilością pirytu i magnetytu. Wszystkie próbki pirotynu były jednoskośnym pirotynem-4C (Fe7S8) i wykazują minimalne różnice pod względem parametrów sieci. Syntetyczny pirotyn-4C był stabilny w czasie 0,5–2 godzin ogrzewania w powietrzu w temperaturze 700℃. Najwyższą względną zawartość miał po ogrzewaniu przez 1 godzinę. Ostatecznie został przekształcony w hematyt z okresami ogrzewania przekraczającymi 3 godziny, podobnie jak w przypadku pirytu i magnetytu. W powietrzu syntetyczny pirotyn-4C powstaje głównie dwoma metodami: (1) piryt → pirotyn-4C i (2) piryt → magnetyt → pirotyn-4C. Ścieżka (1) jest korzystniejsza niż ścieżka (2). Tej przemiany nie można osiągnąć w reakcji hematytu z siarką.

3

Simultaneous quantitation of aconitum alkaloids from You-Gui-yin in rat plasma by UPLC–ESI–MS and its application to a pharmacokinetic study

88%

Zhang J. , Wang L. , Zhu X. , Bai X. , Yin H.

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tom Vol. 31, no. 1

23--27

EN

You-Gui-Yin (YGY), a famous traditional Chinese medicine, has been widely used in clinics for the treatment of kidney-yang deficiency, yang deficiency caused by excessive yin, and osteoporosis. A rapid and sensitive ultraperformance liquid chromatography–electrospray ionization–mass spectrometry (UPLC–ESI–MS) method for simultaneous determination of six Aconitum alkaloids including aconitine (AC), hypaconitine (HA), mesaconitine (MA), benzoylaconine (BAC), benzoylhypaconine (BHA), and benzoylmesaconine (BMA) in rat plasma after oral administration of YGY was developed in this study. Chromatographic separation was performed on an ACQUITY UPLC™ BEH C18 column (2.1 × 100 mm, 1.7 μm) using gradient elution with the mobile phase consisting of 2 mmol/L ammonium formate in 0.05% formic acid aqueous solution and 0.05% formic acid methanol solution, at a flow rate of 0.20 mL/min. MS detection was performed in the positive ion mode. The calibration curves were linear in the concentration range of 0.04160–41.60 ng/mL, 0.1070–107.0 ng/mL, 0.07358–73.50 ng/mL, 0.03228–32.28 ng/mL, 0.01809–18.09 ng/mL, and 0.1320–132.0 ng/mL for AC, HA, MA, BAC, BHA, and BMA, respectively. The intra- and inter-day precisions (relative standard deviation [RSD]) were less than 11.6% and 12.6%, respectively. The accuracies Relative Error (RE) ranged from −10.2% to 5.6%, while the recoveries ranged from 70.4% to 99.3%. The method for simultaneous quantitation of Aconitum alkaloids of You-Gui-Yin in rat plasma is accurate and repeatable, and this method was successfully applied to investigate the pharmacokinetics of the six Aconitum alkaloids in rat plasma after oral administration of YGY. For the pharmacokinetic study, the pharmacokinetics of the six Aconitum alkaloids were best described by a two-compartment open model.

4

A sensitive, heart-cutting, two-dimensional liquid chromatography–tandem mass spectrometry method for the determination of mometasone furoate in human plasma : application for a bioequivalence study in nasal spray formulations

75%

Yang L. , Yang H. , Xie H. , Liu H. , He G. , Zhong W. , Wang L.

Acta Chromatographica

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2024

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tom Vol. 36, no. 1

14--22

EN

We developed and validated a sensitive, heart-cutting, two-dimensional liquid chromatography–tandem mass spectrometry (2D-LC‒MS/MS) method to determine the concentration of mometasone furoate in human plasma after nasal spray administration. Isotopically labeled mometasone furoate-13¹³C,d₆ was used as an internal standard (IS). Plasma samples were prepared using a solid-phase extraction (SPE) method. With this 2D-LC strategy, the analytes were trapped in the first dimension (1D) column, and only judiciously selected portions of the 1D effluent were transferred to the second dimension (2D) column for further separation to obtain high-resolution information. MS/MS quantification was performed in positive ionization mode via multiple-reaction monitoring (MRM). This analytical method was fully validated according to related regulatory guidance, and the results showed that the method is robust and sensitive enough for pharmacokinetic investigation of mometasone furoate with satisfactory linearity from 0.25 to 30 pg mL⁻¹. This method was successfully applied to a bioequivalence (BE) study of mometasone furoate aqueous nasal sprays in healthy volunteers.

5

A rapid and sensitive High-Performance Liquid Chromatography-tandem Mass Spectrometry method for determining apremilast in beagle dog plasma and urine: Application in a pharmacokinetic study

75%

Yan G. , Yu L. , Chen X. , Tran T. , Nguyen L. , Zhijun W. , Wang L.

Acta Chromatographica

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2021

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tom Vol. 33, no. 2

112--119

EN

A rapid and sensitive High-Performance Liquid Chromatography-tandem Mass Spectrometry (HPLC/MS/MS) method for determining apremilast in beagle dog plasma and urine samples was developed and validated using clopidogrel as the internal standard (IS). Apremilast was extracted from the plasma and urine samples by liquid–liquid extraction using methyl tert-butyl ether. Chromatographic separation was performed using a C8 column with gradient elution and a mobile phase containing methanol and 0.1% formic acid. Quantification was achieved in multiple reaction monitoring (MRM) mode with a transition of m/z 461.3→178.2 for apremilast and m/z 322.2→184.1 for clopidogrel (IS). This method was validated regarding its specificity, linearity, precision, accuracy, and stability. The lower limit of quantification (LLOQ) for this method was 5 ng/mL, and the calibration curve was linear over 5–1,000 ng/mL. The intra- and inter-run coefficients of variance (CV) of aprelimast in plasma samples were less than 12.92% and 10.64%, respectively, while in urine samples, the CV were less than 11.84% and 10.20%, respectively. The samples were stable under the tested conditions. This method was successfully applied to a pharmacokinetic study in beagle dogs following oral administration of 10 mg of apremilast.

6

Semi-quantitative analysis study of the impact of microwave treatment on fly ash

63%

Ma X. Y. , Nie Y. M. , Guo J. L. , Chen Y. , Chang Z. J. , Wang L. , Liu S. X. , Wang L.

Physicochemical Problems of Mineral Processing

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2023

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tom Vol. 59, iss. 6

art. no. 174897

EN

Pre-processing provides an effective way for fly ash's high value-added utilization. However, the shortcomings of pre-processing methods such as grinding and flotation are apparent with many disadvantages that make it more challenging to use efficiently. Microwave heating helps the SiO2-Al.2O3 bond break, not only can make the structural change of the material can also promote the chemical reaction process. In the article, XRD, SEM, FT-IR, ammonia nitrogen adsorption, and other methods were used to analyze the changes in the properties of fly ash before and after microwave pre-treatment, the change in adsorption performance of fly ash before and after microwave treatment was analyzed. The study found that under microwave conditions of 600 W and 15 min, the adsorption rate of ammonia nitrogen by fly ash reached a maximum of 29.67%. The intensity of mullite and amorphous diffraction peaks decreased after 20 min at 600 W. The Si-O-(Si, Al) and Si-O-(Si) bonds showed significant changes at 15 min and 20 min under 600 W conditions. Based on the results, the microwave conditions were selected at 600 W for different periods, and semi-quantitative analysis was carried out by XRD-Rietveld, infrared peak fitting, and nuclear magnetic resonance. The XRD-Rietveld analysis showed that the amorphous phase content reached 46.18% at 15 min. In the infrared peak fitting, the fitting area at 1300-900 cm-1 and 600-400 cm-1 peaks at 56.92% at 25 min and 17.5% at 15 min, respectively. The silicon-oxygen network's degree of connection and polymerization was reduced after 15 min of microwave treatment for the nuclear magnetic resonance analysis. By combining specific surface area measurements, it was discovered that the maximum specific surface area attained a value of 3.122 m2/g at 15 min.