scholarly journals Facile Fabrication of Zeolitic Imidazolate Framework Hollow Fibre Membranes via A Novel Scalable Continuous Fluid Circulation Process

Nanoscale ◽  
2021 ◽  
Author(s):  
Allana Lewis ◽  
Ting Chen ◽  
Fraz Saeed Butt ◽  
Xiuming Wei ◽  
Norbert Radacsi ◽  
...  
Keyword(s):  
Internal Surface ◽  
Hollow Fibre ◽  
Circulation System ◽  
Fluid Circulation ◽  
Zeolitic Imidazolate Framework ◽  
Facile Fabrication

A novel continuous fluid circulation system was designed and employed for the impregnation seeding and fabrication of zeolitic imidazolate framework (ZIF) crystals on the internal surface of polymeric hollow fibre...

scholarly journals Facile Fabrication of Diatomite-Supported ZIF-8 Composite for Solid-Phase Extraction of Benzodiazepines in Urine Samples Prior to High-Performance Liquid Chromatography

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5209
Author(s):  
Li Du ◽  
Shaonan Xu ◽  
Han Wu ◽  
Tengwen Zhao ◽  
Xuesheng Wang ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Solid Phase Extraction ◽  
High Performance ◽  
Solid Phase ◽  
Enrichment Factors ◽  
Phase Extraction ◽  
Zeolitic Imidazolate Framework ◽  
Facile Fabrication ◽  
Sensitive Determination

A novel diatomite-supported zeolitic imidazolate framework-8 sorbent (ZIF-8@Dt-COOH) was in situ fabricated and developed for solid-phase extraction of three benzodiazepines (triazolam, midazolam and diazepam) in urine followed by high-performance liquid chromatography. ZIF-8@Dt-COOH was easily prepared by coating ZIF-8 on the surface of Dt-COOH and characterized by Fourier transform infrared spectra, X-ray powder diffractometry and scanning electron microscopy. Compared with bare Dt-COOH, the extraction efficiency of ZIF-8@Dt-COOH for the target was significantly increased from 20.1–39.0% to 100%. Main extraction parameters, including ionic strength and pH of solution, loading volume, washing solution, elution solvent and elution volume, were optimized in detail. Under optimum conditions, the developed method gave linearity of three BZDs in 2–500 ng/mL (r ≥ 0.9995). Limits of detection (S/N = 3), and limits of quantification (S/N = 10) were 0.3–0.4 ng/mL and 1.0–1.3 ng/mL, respectively. In addition, the average recoveries at three spiked levels (5, 10 and 20 ng/mL) varied from 80.0% to 98.7%, with the intra-day and inter-day precisions of 1.4–5.2% and 1.5–8.2%, respectively. The proposed method provided an effective purification performance and gave the enrichment factors of 24.0–29.6. The proposed method was successfully employed for the accurate and sensitive determination of benzodiazepines in urine.

Perpendicular Axis Magnetorheological Finishing of Spherical Optics

2012 ◽  
Vol 628 ◽  
pp. 161-165
Author(s):  
Yun Zhang ◽  
Jing Shan Zhao ◽  
Yu Yue Wang
Keyword(s):  
Spherical Surface ◽  
Circulation System ◽  
Fluid Circulation ◽  
Magnetorheological Finishing ◽  
Polishing Process ◽  
Mr Fluid ◽  
Aspheric Surfaces ◽  
Flat Surfaces ◽  
Spherical Surfaces ◽  
Rotation Motion

Magnetorheological Finishing, MRF can achieve deterministic results on different surface shapes such as flat surfaces, spherical surfaces and aspheric surfaces. MRF can also overcome many drawbacks of the conventional polishing process. The schedule uncertainties driven by edge roll and edge control are virtually eliminated with the MRF process. This paper presents a polishing wheel that combines rotation motion with revolution motion while renewing the MR fluid. Stable removal characteristic can be obtained by using the composite-rotation wheel. This paper also presents some recent results of the deterministic finishing typified by the tool and its MR fluid circulation system. An example of finishing a square optical workpiece with spherical surface will be reviewed.

scholarly journals THERMAL ASYMMETRY ANALYSIS OF MOTORIZED SPINDLES

2021 ◽  
Vol 2021 (3) ◽  
pp. 4612-4619
Author(s):  
L. Koch ◽  
◽  
N. Steinbock ◽  
G. Krueger ◽  
◽  
...  
Keyword(s):  
Mathematical Formulation ◽  
Longitudinal Axis ◽  
Circulation System ◽  
Fluid Circulation ◽  
Motorized Spindle ◽  
Asymmetry Analysis ◽  
Center Point ◽  
Complex Fluid ◽  
Thermal Centroid ◽  
Motorized Spindles

This paper presents a method to quantify and reduce thermal asymmetry of motorized spindles. Thermal asymmetry leads to angular and radial deflections at the tool center point. In contrast to simple thermal expansion issues, these effects are harder to compensate. Therefore, the causes of the asymmetries should preferably be evident in the construction phase. This paper introduces a newly developed mathematical formulation to quantify thermal asymmetry. Thermal asymmetry is observed along the longitudinal axis of a motorized spindle. The formulation quantifies thermal asymmetries as a difference of a geometrical centroid and a newly introduced thermal centroid. For this analysis, several motor spindles with different fluid cooling circulation systems were observed. In order to show the legitimacy of the formulation, the spindle’s calculated thermal asymmetries are compared with their respective radial tool center point displacements. The results show that the asymmetries correlate with the displacements. Furthermore, the quantification of the thermal asymmetry actually allows to locate its causes. In motor spindles the asymmetry is mostly caused by the complex fluid circulation system. The spindle with the worst cooling circulation showed a radial displacement of 26,32 µm. Through thermal asymmetry optimization of the circulation’s heat transfer, the displacement could be reduced to 0,66 µm. The developed method is not limited to motorized spindles. It will be investigated further to develop a generally valid formulation.

scholarly journals Magmatic and tectonic segmentation of the intermediate-spreading Costa Rica Rift—a fine balance between magma supply rate, faulting and hydrothermal circulation

2020 ◽  
Vol 222 (1) ◽  
pp. 132-152
Author(s):  
A H Robinson ◽  
L Zhang ◽  
R W Hobbs ◽  
C Peirce ◽  
V C H Tong
Keyword(s):  
Costa Rica ◽  
P Wave ◽  
Circulation System ◽  
Fluid Circulation ◽  
Ridge Axis ◽  
Low Velocity ◽  
Low Velocity Zone ◽  
Velocity Anomaly ◽  
Magma Supply ◽  
Velocity Zone

SUMMARY 3-D tomographic modelling of wide-angle seismic data, recorded at the intermediate-spreading Costa Rica Rift, has revealed a P-wave seismic velocity anomaly low located beneath a small overlapping spreading centre that forms a non-transform discontinuity at the ridge axis. This low velocity zone displays a maximum velocity anomaly relative to the ‘background’ ridge axis crustal structure of ∼0.5 km s−1, has lateral dimensions of ∼10 × 5 km, and extends to depths ≥2.5 km below the seabed, placing it within layer 2 of the oceanic crust. We interpret these observations as representing increased fracturing under enhanced tectonic stress associated with the opening of the overlapping spreading centre, that results in higher upper crustal bulk porosity and permeability. Evidence for ongoing magmatic accretion at the Costa Rica Rift ridge axis takes the form of an axial magma lens beneath the western ridge segment, and observations of hydrothermal plume activity and microearthquakes support the presence of an active fluid circulation system. We propose that fracture pathways associated with the low velocity zone may provide the system through which hydrothermal fluids circulate. These fluids cause rapid cooling of the adjacent ridge axis and any magma accumulations which may be present. The Costa Rica Rift exists at a tipping point between episodic phases of magmatic and tectonically enhanced spreading. The characteristics inherited from each spreading mode have been preserved in the crustal morphology off-axis for the past 7 Myr. Using potential field data, we contextualize our seismic observations of the axial ridge structure at the whole segment scale, and find that the proposed balance between magmatic and tectonically dominated spreading processes observed off-axis may also be apparent along-axis, and that the current larger-scale magma supply system at the Costa Rica Rift may be relatively weak. Based on all available geophysical observations, we suggest a model for the inter-relationships between magmatism, faulting and fluid circulation at the Costa Rica Rift across a range of scales, which may also be influenced by large lithosphere scale structural and/or thermal heterogeneity.

Veins in the Lockport dolostone: Evidence for an Acadian fluid circulation system

Geology ◽  
1992 ◽  
Vol 20 (11) ◽  
pp. 971 ◽  
Author(s):  
Michael R. Gross ◽  
Terry Engelder ◽  
Simon R. Poulson
Keyword(s):  
Circulation System ◽  
Fluid Circulation
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