Some Problems in Winding Geometry

The efficiency of wound, hollow-fiber separation modules used to remove dissolved salts from water by the process of reverse osmosis may be improved by alterations in module geometry. Normally, the hollow-fiber membranes composing the module are helically wound about a cylindrical core. Flow rate through the module may be increased, however, if the cross-sectional density of wound fibers varies uniformly along the module axis. This paper explores the analytical requirements for the helical winding of a conical mandrel with filamentary material in a manner that eventually produces a cylindrically shaped package. The effect of specifying either a constant yarn feed rate or a constant spindle speed during winding is considered in relation to restrictions on the length of material added per circuit.

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A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs

Applied Sciences ◽

10.3390/app11083404 ◽

2021 ◽

Vol 11 (8) ◽

pp. 3404

Author(s):

Majid Hejazian ◽

Eugeniu Balaur ◽

Brian Abbey

Keyword(s):

Molecular Dynamics ◽

Flow Rate ◽

Numerical Study ◽

Three Dimensional ◽

Microfluidic Devices ◽

Liquid Jets ◽

Mixing Efficiency ◽

X Ray Diffraction ◽

Cross Sectional ◽

Time Required

Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.

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Effects of hemodialysis treatment on saliva flow rate and saliva composition during in-center maintenance dialysis: a cross-sectional study

Renal Failure ◽

10.1080/0886022x.2020.1857769 ◽

2020 ◽

Vol 43 (1) ◽

pp. 71-78

Author(s):

I-Chen Yu ◽

Chieh-Yu Liu ◽

Ji-Tseng Fang

Keyword(s):

Flow Rate ◽

Cross Sectional Study ◽

Sectional Study ◽

Cross Sectional ◽

Saliva Flow Rate ◽

Hemodialysis Treatment ◽

Maintenance Dialysis ◽

Saliva Flow ◽

Saliva Composition

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Salivary flow rate and the risk of cognitive impairment among Korean elders: a cross-sectional study

BMC Geriatrics ◽

10.1186/s12877-021-02200-2 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Minh-Tung Do ◽

Huong Vu ◽

Jong-Koo Lee ◽

Sang-Min Park ◽

Joung-Sik Son ◽

...

Keyword(s):

Cognitive Impairment ◽

Flow Rate ◽

Salivary Flow ◽

Cross Sectional Study ◽

Community Dwelling ◽

Salivary Flow Rate ◽

Multivariable Logistic Regression Analysis ◽

Sectional Study ◽

Cross Sectional ◽

Denture Status

Abstract Background Salivary function has been suggested to be associated with cognitive impairment. However, the effect of salivary flow rate (SFR) on cognitive impairment remains unclear. This study aimed to investigate whether SFR is associated with cognitive impairment among Korean elders. Methods This cross-sectional study included 649 elders aged 65 and older in the Korean community-dwelling population. Cognitive impairment was assessed using the Mini-Mental Status Examination. Unstimulated SFR was measured and dichotomized. Denture status, age, sex, education level, smoking, drinking, diabetes, hypertension, and obesity were considered confounders. Multivariable logistic regression analysis was applied to assess the adjusted association. Stratified analysis by sex and denture status was performed to clarify the effect modification. Results Participants without cognitive impairment showed a higher SFR level than those with cognitive impairment (0.81 mL/min for non-cognitive impairment versus 0.52 mL/min for cognitive impairment, p < 0.001). After controlling for confounders, participants with low SFR (< 0.3 mL/min) were more likely to have cognitive impairment by 1.5 times than participants with normal SFR (odds ratio [OR] = 1.5, confidence interval [CI] = 1.05–2.10). The association of low SFR with cognitive impairment was higher in women and dentate participants: about 10% higher in women (OR = 1.63, CI = 1.07–2.50) and about 22% higher in dentate participants (OR = 1.82, CI = 1.41–2.90). Conclusions Salivary flow rate is independently associated with cognitive impairment among Korean elders. The association was modified in females and dentate elders. Physicians and dentists should consider low SFR and cognitive impairment as a risk factor between them in clinics.

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Osmotically enhanced reverse osmosis using hollow fiber membranes

Journal of Membrane Science ◽

10.1016/j.memsci.2021.119703 ◽

2021 ◽

pp. 119703

Author(s):

Xianhui Li ◽

Ying Mei ◽

Junwei Zhang ◽

Yang Yang ◽

Lu Elfa Peng ◽

...

Keyword(s):

Reverse Osmosis ◽

Hollow Fiber ◽

Hollow Fiber Membranes ◽

Fiber Membranes

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Optimization of TFC-PES hollow fiber membranes for reverse osmosis (RO) and osmotically assisted reverse osmosis (OARO) applications

Journal of Membrane Science ◽

10.1016/j.memsci.2021.119156 ◽

2021 ◽

Vol 625 ◽

pp. 119156

Author(s):

Mohammad Askari ◽

Can Zeng Liang ◽

Looh Tchuin (Simon) Choong ◽

Tai-Shung Chung

Keyword(s):

Reverse Osmosis ◽

Hollow Fiber ◽

Hollow Fiber Membranes ◽

Fiber Membranes

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Hollow fiber composite membrane modules for reverse osmosis

Desalination ◽

10.1016/s0011-9164(00)88377-0 ◽

1977 ◽

Vol 22 (1-3) ◽

pp. 221-227 ◽

Cited By ~ 5

Author(s):

R.B. Davis ◽

R.D. Burchesky ◽

M.J. Coplan

Keyword(s):

Reverse Osmosis ◽

Composite Membrane ◽

Hollow Fiber ◽

Fiber Composite ◽

Hollow Fiber Composite Membrane ◽

Membrane Modules

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Preparation and characterization of different geometrical shapes of multi-bore hollow fiber membranes and application in vacuum membrane distillation

Journal of Analytical Science & Technology ◽

10.1186/s40543-020-00244-4 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Elham M. El-Zanati ◽

Eman Farg ◽

Esraa Taha ◽

Ayman El-Guindi ◽

Heba Abdallah

Keyword(s):

Mechanical Properties ◽

Flow Rate ◽

Hollow Fiber ◽

Amorphous Structure ◽

Membrane Distillation ◽

Operating Conditions ◽

Hollow Fiber Membranes ◽

Preparation Conditions ◽

Geometrical Shapes ◽

Fiber Membranes

Abstract Multi-bore hollow fiber membranes were prepared through phase inversion spinning process using new locally designed spinnerets of various geometrical shapes. The spun cylindrical-like, rectangular or ribbon-like, and triangular-like are prepared, dried, and characterized by scanning electronic microscope. Fibers of circular (seven, five, and four bores) shape, rectangular of five bores, and triangular of three bores were chosen to study the effect of both geometrical configuration and the number of bores on the amorphous structure and the mechanical properties of the membranes. Membrane geometry, surface amorphous, and bore arrangements are very sensitive to the operating conditions, especially the extrusion and drawing rates. Three polymeric blends of different compositions are used to prepare multi-bore hollow fiber membranes. This study revealed that the blend composition of PES 16%, PVP 2%, PEG 2%, diethylene glycol 2%, and NMP 78% gives excellent mechanical properties. Optimization of the preparation conditions also developed, where the dope flow rate, the bore flow rate, and the air gap were 1.14 cm3 s−1, 1.1 cm3 s−1, and 0 cm, respectively. Furthermore, this study proved that the circular arrangement has high mechanical strength. The prepared seven-MBHF membranes were applied in the membrane distillation process, a solution of 35 g/l NaCl was used to test the membrane performance, and the achieved flux and rejection were 28.32 L/m2 h and 98.9%, respectively. This performance demonstrated that the prepared membrane in this way is suitable to compete with conventional reverse osmosis technology that uses single track hollow fibers.

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