Aperture Membrane Research Articles

Application and Cytotoxicity Evaluation of Fe-MIL-101 Nanozyme in Milk.

In this study, we used Fe-MIL-101 nanozyme to convert lactose into lactitol, and it was proved that Fe-MIL-101 nanozyme has lactase-like activity. Due to the potential health effects of nanomaterials, we evaluated the cytotoxicity of Fe-MIL-101 nanozyme. To reduce the potential toxicity of the nanozyme, we applied centrifugation and membrane filtration. When the membrane aperture size was 100nm, the residual content of Fe-MIL-101 nanozyme was 14.09μg/mL. The residual content of Fe-MIL-101 nanozyme was reduced by optimizing time, temperature, and Fe-MIL-101 nanozyme-to-substrate ratio. It was showed that the concentration of Fe was 38.47mg/kg and the concentration of H2BDC was 0mg/kg under optimized conditions (110℃, 2h of reaction and the ratio of Fe-MIL-101 nanozyme to substrate is 1:20). The result met the national standard of China. Experiments measuring cytotoxicity, oxidative stress, and cell membrane damage revealed that less than 20μg/mL Fe-MIL-101 nanozyme had no significant cytotoxicity. Our study findings showed that Fe-MIL-101 nanozyme reduced lactose content in milk.

The anti-fouling and mechanism of Fe3O4@PVDF catalytic membrane in-situ coupling Fenton oxidation for organic pollutants removal

Polyvinylidene fluoride (PVDF) membrane is a promising technique for deep treatment of organic wastewater. However, the unavoidable membrane contamination greatly restrictions its field of application. Herein, we successfully prepared Fe3O4@PVDF membrane with excellent anti-fouling and catalytic ability by non-solvent induced phase inversion method. Meanwhile, Fe3O4@PVDF membrane was characterized by SEM, XRD, FTIR, Water contact Angle and membrane aperture analyzer. The properties of separation and anti-fouling were also evaluated by cross flow filtration of humic acid (HA). Compare with pristine membrane, the pure water flux, rejection rate and FRR respectively increase from 556.81 L m-2 h−1, 65.42 %, 68.26 % to 656.96 L m-2 h−1, 99.64 %, 90.17 % under in-situ Fenton reaction condition. In addition, further mechanistic insights by XDLVO theory, 3D-EEM and EPR verified that high anti-fouling mainly attribute to excellent hydrophilicity of Fe3O4@PVDF and in-situ degradation of HA by OH and 1O2· This work provides insights for improving the separation properties and anti-fouling properties of PVDF membrane in the field of treatment organic wastewater.

Effect of pore size polydispersity on the acoustic properties of high-porosity solid foams

This study investigates the influence of pore size polydispersity on the acoustic behavior of high-porosity solid foams using numerical simulations. The effect of the size of the periodic unit cell (PUC) on the transport parameters is first examined. It is found that the size of the PUC required for properly estimating the acoustic properties of random foams depends on both the analyzed transport parameter(s) and level of polydispersity. Assuming identical and constant aperture ratio of membranes, the results indicate that (i) the viscous permeability is a reliable indicator regarding the size of the PUC (a more constraining property than the other transport parameters), and (ii) high-polydispersity foams require a larger number of pores in the PUC to achieve convergence with respect to morphological characteristics and acoustic properties. The influence of polydispersity on dimensionless transport parameters is then analyzed. It is found that polydispersity has a negligible effect on the high-frequency tortuosity but induces substantial variations in the remaining macroscopic parameters. Simulations further show that the ratio of the dimensionless transport parameters does not depend on membrane aperture ratio. This important result allows us to propose a fast method to estimate the acoustic properties of a random foam from the transport parameters of monodisperse foams with different pore sizes, for each studied transport parameter. The proposed method is finally employed to characterize the pore size and polydispersity in two real foams (with and without membranes), solving an inverse problem.

Pollen Morphology of Polygala L. (Polygalaceae) from Turkey and its Taxonomic Implications

Pollen morphology of Polygala taxa from the family Polygalaceae in Turkey is presented in this study. Pollen features of 18 species along with one undescribed species in the section Polygala were examined with light and scanning electron microscopy, 11 of which were studied and defined for the first time. Cluster analysis and principal components analysis were conducted to determine informative palynological characters and to discover similarities among the studied taxa. Based on qualitative and quantitative variables in the phenogram, the studied taxa were divided into three major clusters. Multivariate analyses revealed that apocolpium characters, including a psilate apocolpium, the presence of apocolpial lumens with granules and small depressions with psilate or rugulate walls are the most distinct features for discriminating Polygala taxa. Intraspecific variations in some pollen characters, such as the exine pattern and aperture membrane features, are reported for several taxa. Pollen morphological data obtained in the present study are compared with those from previous studies for a number of species, and the results are evaluated. In addition, the aperture number and its probable significance in the Turkish Polygala are considered for some taxa, with emphasis on their known pollination strategies.

Optimized Approach for Image Design Processing in Optical Networks: A Comparative Study

Abstract Deep space detection and remote sensing both require optical imaging devices. The optical imaging system often needs a bigger aperture mirror to attain high spatial resolution. As a result, several novel optical imaging systems, such as big segmented mirror telescopes, large aperture membrane diffractive optical telescopes, and others, have been researched in recent years. Real-time wavefront measurement is not required for the wavefront sensorless (WFSless) applied optics (AO) approach. The wavefront corrector is directly regulated via feedback following an image quality measure of the far-field image to correct for wavefront aberration. Integrating artificial neural networks (ANN) and deep learning plays a vital role in developing WFSless AO systems. This paper evaluated various important aspects to provide an in-depth review of the state-of-the-art machine learning-based algorithms deployed in WFSless AO systems. Finally, the applications and prospects were outlined.

Pollen morphology of the early branching papilionoid legume genera Harleyodendron, Holocalyx and Uribea

In this study, pollen grains of Harleyodendron unifoliolatum, Holocalyx balansae, and Uribea tamarindoides, three monospecific genera with Neotropical distribution belonging to the clade Exostyleae, one of the basal lineages of the family Leguminosae, subfamily Papilionoideae, were analyzed. The palynological material was acetolyzed and analyzed under light microscopy (LM) and scanning electron microscopy (SEM). Under LM, small and medium-sized pollen grains were observed, which showed a prolate-spheroidal to prolate shape, 3-colporate, microreticulate and reticulate exine, sexine and nexine of equal thickness in Harleyodendron and Holocalyx, while the sexine was thicker than nexine in Uribea. Analysis under SEM showed finely granulate, psilate, and granulate apertural membrane, while the exine ornamentation varied from perforate-microechinate in Harleyodendron, to perforate in Holocalyx, while in Uribea showed an irregular relief and granular projections on the perforate tectum. The pollen morphology of these species is similar to each other, varying in sexine/nexine ratio, apertural membrane, and exine ornamentation. Harleyodendron has a finely granulate apertural membrane, sexine and nexine of equal thickness, and a perforate-microreticulate exine ornamentation, Holocalyx shows a psilated apertural membrane, sexine and nexine of equal thickness, and exine ornamentation perforate, and Uribea has a granulate apertural membrane, sexine thicker than nexine, and exine ornamentation with granular projections.

Enhanced and evenly-distributed Li+ transport in well-aligned nanochannels enables stable lithium metal anode

The high theoretical capacity of lithium (Li) has sparkled its intensive research as the anode for Li batteries. However, the dendritic growth due to the uneven Li deposition causes premature cell failure and dramatically restricts the application of Li anode. Herein, inspired by the pore sizes effects of anodized aluminum oxide (AAO) membranes on Li+ transport performance, 20 nm aperture membrane (AAO-20) with enhanced Li+ transport can achieve higher Li+ concentration near the deposition substrate, possibly preventing rapid Li+ depletion compared to other aperture sizes. Subsequently, smaller Li nucleation overpotential and larger exchange current density in AAO-20 reveal the enhanced kinetics at deposition interface, which is derived from the enhanced Li+ transport in nanochannels, leading to a superior Li deposition. With AAO-20 which can stabilize Li anode, Li-Cu, Li-Li, and Li-LiFePO4 cells demonstrate high Coulombic efficiency, superior cycling stability, and excellent capacity retention, respectively. Such findings can be helpful for the development of high-energy Li metal batteries.

High-frequency permeability of porous media with thin constrictions. I. Wedge-shaped porous media

In this series of publications, the high-frequency behavior of the dynamic permeability of porous media with thin constriction is investigated. In Part I, the classical theory of Johnson et al. [“Theory of dynamic permeability and tortuosity in fluid saturated porous media,” J. Fluid Mech. 176, 379 (1987)] for soft-curved pore geometries is recalled. For wedge-shaped pore geometries, numerical computations (by finite element method) and analysis by Cortis et al. [“Influence of pore roughness on high-frequency permeability,” Phys. Fluids 15, 1766 (2003)] are revisited and confirmed, while leading to important new conclusions. Because the electric field is singular at the tip of wedges, the original model developed by Johnson et al., which links the viscous fluid flow problem to the electrical conduction problem, is inappropriate for describing the high-frequency behavior of the viscous fluid flow through wedge-shaped porous media. In particular, in the case of small wedge angles, we show that the real part of the dynamic permeability behaves in the high-frequency regime as ℜ(k(ω))∝ω−(3/2)(ln (ω)+constant), which differs from the predictions of the Johnson et al. model [ℜ(k(ω))∝ω−(3/2)]. However, our results show that the classical Johnson et al. high frequency limit can be a good approximation of the viscous fluid flow if the electrical conduction problem is solved over a fluid domain truncated by a boundary layer having a thickness comparable to the viscous skin depth. In Part II, we consider foam with perforated membranes involving different microstructural characteristic lengths: pore size, membrane aperture size, and membrane thickness. We assess the validity domain of the Johnson et al. approximation and test our modified high-frequency approximation for such porous materials.

High-frequency permeability of porous media with thin constrictions. II. Porous media containing thin holed membranes

In this series of publications, the high-frequency behavior of the dynamic permeability of porous media with thin constriction is investigated. In Paper I, the classical theory of Johnson et al. [J. Fluid Mech. 176, 379 (1987)] for soft-curved pore geometries is recalled. For wedge-shaped pore geometries, numerical computations (by the finite element method) and analysis by Cortis et al. [Phy. Fluids 15, 1766 (2003)] are revisited and confirmed, while leading to important new conclusions. Because the electric field is singular at the tip of wedges, the original model developed by Johnson et al., which links the viscous fluid flow problem to the electrical conduction problem, is inappropriate for describing the high-frequency behavior of the viscous fluid flow through wedge-shaped porous media. In particular, in the case of small wedge angles, we show that the real part of the dynamic permeability behaves in the high-frequency regime as ℜ(k(ω))∝ω−(3/2)(ln (ω)+constant), which differs from the predictions of the Johnson et al. model [ℜ(k(ω))∝ω−(3/2)]. However, our results show that the classical Johnson et al. high frequency limit can be a good approximation of the viscous fluid flow if the electrical conduction problem is solved over a fluid domain truncated by a boundary layer having a thickness comparable to the viscous skin depth. In Paper II, we consider foam with perforated membranes involving different microstructural characteristic lengths: pore size, membrane aperture size, and membrane thickness. We assess the validity domain of the Johnson et al. approximation and test our modified high-frequency approximation for such porous materials.

Enhanced Electro-Fenton Degradation of Ciprofloxacin by Membrane Aeration

Electro-Fenton is a widely used electrochemical advanced oxidation process for the treatment of refractory organic pollutants, in which O2 input is required to generate hydrogen peroxide. The aeration mode directly affects the dissolution and stability of O2 bubbles in the solution, thus the rate of degradation. Herein, membrane aeration was introduced to the electro-Fenton degradation of ciprofloxacin in which O2 was dispersed into the liquid phase in the form of microbubbles through the ceramic membrane. Microbubbles can greatly improve the gas–liquid mass transfer efficiency of unit volume O2 to obtain an ultrahigh concentration of dissolved O2 up to 46 mg/L, thus improving the reaction rate. The effects of aeration mode, applied current, membrane aperture, aeration rate, and ciprofloxacin concentration on degradation rate were studied. Compared with the conventional electro-Fenton process using plastic pipe aeration, the membrane aeration-enhanced electro-Fenton (MAEF) system achieved a significant improvement in the degradation rate, and the reaction time required to achieve a 97% degradation ratio was remarkably reduced from 4 h to 10 min. Membrane aeration is an efficient approach to facilitating heterogeneous catalysis reactions involving the gas phase.

Can pollen exine ornamentation contribute to species delimitation in Korean Iris L. taxa (Iridaceae)?

ABSTRACT Iridaceae L. is a large and well-known plant family that is widely distributed across the northern hemisphere. According to recent and ongoing taxonomic revision, its largest genus, Iris L., includes 14 species of perennial herbs occurring in Korea. Although pollen morphological data have proved crucial to the resolution of systematic relationships within the Iris genus, detailed palynological studies of Korean irises are scarce. Thus, this study aimed to describe the pollen morphology of 14 species representing two subgenera (Limniris and Pardanthopsis) of Korean Iris and one closely related species (Sisyrinchium rosulatum) using scanning electron microscopy. Pollen grains of all studied taxa were large in size (P = 35.9–86.7 μm, E = 37.3–72.9 μm), oblate (P/E = 0.68) to prolate (P/E = 1.99) in shape, and monosulcate with a granulate-perforate aperture membrane. Three types of exine ornamentation were identified in Korean Iris species: perforate (Type I); microreticulate (Type II); and reticulate (Type III), which was divided into four distinct subtypes based on lumen diameter. The observed pollen micromorphological characters enabled species distinction and taxonomic delimitation to the series level in the genus. The pollen morphological data presented in this study may be of systematic significance to Korean Iris species.

Pollen morphology of the genus Sophora (Fabaceae) and its taxonomic implications.

The genus Sophora (Fabaceae) is one of the taxonomically challenging genera with high economic and medical values. In this study, the pollen morphology of 43 samples of 27 species, 4 subspecies, and 4 varieties of the genus Sophora and 3 closely related genera was examined using scanning electron microscopy to evaluate the pollen diversity of the genus and its taxonomic significance. Pollen grains of the studied species were tricolporate (rarely six-aperture), and pollen shape varied from suboblate, spheroidal, subprolate to prolate. Echinate external ornamentation was reported for the first time in some species of the genus. Aperture membrane ornamentation and outline in a polar/equatorial view were described for the first time in the genus. Principal component analysis was used to understand the relationship and discrimination between the species and the genera, with six components accounting for 79.92% of the total variance. Taxonomic keys based on pollen morphology were also constructed to easily identify the taxa of the genus through palynological characteristics. Results showed that pollen morphology alone is not sufficient to elucidate or reconstruct taxonomic relationships within the genus Sophora, but palynological assessments can provide some useful information for identifying taxonomically problematic taxa.

Pollen and seed morphology of selected species of Andrographis (Acanthaceae) from India

Light and scanning electron microscopic studies of pollen and seeds were carried out for nine species of Andrographis (Acanthaceae) from India. Pollen in all species is isopolar, radially symmetric and tricolporate with elongated apertures, oblate-spheroidal in A. ovata, prolate-spheroidal in A. alata, prolate in A. echioides and A. macrobotrys to sub-prolate in A. lineata var. lawii, A. lineata var. lineata, A. paniculata, A. producta and A. serpyllifolia and lobate-circular to triangular amb. Surface ornamentation is bireticulate except in A. alata, which has microperforate and spinulate tectum. Seeds are obovoid, oblongoid, subquadrate or ellipsoid in shape. The seed coat is covered with hair in A. ovata and with echinate protuberances in A. echioides and A. serpyllifolia. The pollen characteristics of A. echioides including the colporate apertures, prolate shape, bireticulate tectum and verrucate aperture membrane are support an inclusion of this species in Andrographis, rather than considering it as Indoneesiella echioides, which has been the subject of much debate.

Micromorphological differentiation of Korean Disporum species using light and scanning electron microscopy.

The genus Disporum Salisb. is widely distributed in East Asia, yet phylogenetically relevant morphological traits useful for differentiating many of the small, perennial, herbaceous species remain poorly described. To address this, leaf, floral, pollen, and orbicule micromorphology of four Korean Disporum species was investigated using light and scanning electron microscopy. All Korean Disporum species examined had hypostomatic leaves, with anomocytic stomatal complexes found only on the abaxial epidermis. Guard cell length varied among species, ranging from 44.30 μm in D. viridescens to 53.49 μm in D. uniflorum. The epidermal cells of the investigated Disporum taxa had sinuate anticlinal cell walls on both adaxial and abaxial surfaces. The surface of the guard and subsidiary cells were either smooth with weak striations or had strongly wrinkled striations. The pollen grains of all Korean Disporum taxa were monads, monosulcate with granular aperture membranes, subprolate to prolate in shape with microreticulate or verrucate exine surfaces. The mean size of pollen grains ranged from 46.38 to 49.92 μm in polar length and from 34.39 to 39.58 μm in equatorial diameter across species. Sexine ornamentation was a taxonomically relevant trait for differentiating Korean Disporum taxa. Additionally, the presence of orbicules as well as the orbicular characters (e.g., size, shape, ornamentation, and association pattern) are described for the first time in species from this genus. The present investigation of leaf and floral micromorphology using light and scanning electron microscopy provides valuable information for the taxonomic differentiation and identification of Disporum species in Korea. RESEARCH HIGHLIGHTS: A detailed micromorphological description of leaf, floral characters (tepal, stigma, style), pollen and orbicule is provided for Korean Disporum species using scanning electron microscopy (SEM) and light microscopy (LM). The presence of orbicules and their taxonomic implications in Korean Disporum species are described for the first time. Phylogenetically informative pollen and orbicule micromorphological characters are described, improving understanding the systematic relationships of Korean species in the genus Disproum.

Copolyamide-Imide Membrane with Low CTE and CME for Potential Space Optical Applications.

Polyimide diffractive membrane lens can be used in space optical telescope to reduce the size and mass of an imaging system. However, traditional commercial aromatic polyimide membrane is hard to meet the challenging requirements of dimensional stability and optical homogeneity for optical use. Based on molecular structure design and the optimization of fabrication process, the prepared copolyamide-imide membrane achieved the desired performance of membrane as an optical material. It showed a very low coefficient of thermal expansion (CTE), which is 0.95 ppm/°C over a temperature range of −150–100 °C and relatively low coefficient of moisture expansion (CME), which is only 13.30 ppm/% RH (0~90% RH). For the optical use, the prepared copolyamide-imide membrane (φ200 mm) achieved good thickness uniformity with wave-front error smaller than λ/30 (λ = 632 nm) in RMS (root mean square). Besides, it simultaneously meets the optical, thermal, and mechanical requirements for space telescope use. Copolyamide-imide membranes in this research with good comprehensive performance can be used as large aperture membrane optical system architectures.

Integrated nanoparticle size with membrane porosity for improved analytical performance in sandwich immunochromatographic assay

The use of luminescent nanobeads to improve the sensitivity of sandwich immunochromatographic assay (ICA) has obtained increasing concern. Illustrating the relationship among luminescent intensity, nanobead size, nitrocellulose membrane aperture, and ICA sensitivity is important for achieving the optimal target detection. Thus, we synthesized six differently sized quantum dot beads (QBs) (95, 140, 180, 235, 325, and 405 nm) as ICA labels and applied them in three aperture membranes (10, 15, and 25 μm). Results indicate that increasing the QB size to less than an appropriate size of 235 nm is beneficial for ICA sensitivity because of the increased fluorescence. However, oversized QBs result in reduced sensitivity due to the decreased diffusion or settlement of the QB on the membrane that causes obvious background signal. The small aperture membrane perfectly matching the QB size contributes to ICA sensitivity by decreasing the migration velocity of the QB probe for increased binding of the QB@analyte complex at the T zone. Consequently, the best detection of hepatitis B surface antigen with a sensitivity of 0.156 ng/mL is achieved using 235 nm QBs in 15 μm membrane. Further performance evaluation of our QB235-ICACN95 demonstrates excellent accuracy, selectivity, and practicability. This work provides a new idea to manipulate the sensitivity of sandwich ICA by tuning the QB size and the membrane aperture, and a theoretical guidance for selecting the probe and membrane to achieve the best detection of target analytes.

Confirmation of Suzuki-Miyaura Cross-Coupling Reaction Mechanism through Synthetic Architecture of Nanocatalysts.

Despite widespread use of heterogeneous Pd catalysts in Suzuki-Miyaura coupling reactions, detailed roles of Pd, especially the nature of its active species, are still a topic of controversial debate. While some studies showed an active surface of Pd nanoparticles or nanoclusters acting heterogeneously, others claimed soluble Pd species leached from the metallic Pd to be active species which are homogeneous in nature. Besides, within the homogeneous mechanism, how the Pd leaches and promotes the cross-coupling reaction is then another question that needs to be addressed. It could be envisioned that if the soluble Pd species and solid-phase Pd are physically separated, the mechanism of Suzuki-Miyaura coupling could then be confirmed through examining the catalytic activity in different reaction regions. Herein we use microporous Stöber silica as a membrane to separate the soluble Pd species from solid Pd and conduct size-selective reactions which allow the passage of leaching Pd species, but not of reactants or products larger than the membrane aperture. With this strategy, we have been able to differentiate the surface reaction from the solution cross-coupling. We find that the leached Pd species are the only genuine catalytic intermediate in the cross-coupling reactions. We also confirm that oxidative addition of aryl halides to the solid Pd leads to leaching of the soluble Pd species which is necessary to promote Suzuki-Miyaura reactions.

Facile large-area uniform photolithography of membrane diffractive lens based on vacuum assisted self contact method

Optical polyimide (PI) membrane is a promising substrate material for diffractive lens applied in future large-aperture space based imaging system because of its light weight, environmental adaptability and deployable feature. In this letter, we put forward a facile large-area uniform photolithography technique using vacuum assisted self contact method to fabricate large-aperture membrane diffractive lens. We fabricated a φ 400 mm aperture membrane off-axis 2-levels Fresnel Zone Lens (FZL) based on the method and achieved uniformly distributed photoresist morphology as well as over 36.6% average diffraction efficiency in full aperture. The results demonstrated that vacuum assisted self contact method effectively eliminates considerable air gaps caused by unevenness of large area photomask and substrate, thus facilitates uniform light field distribution in photoresist. This work provides reference to fabrication techniques of large aperture membrane diffractive lens, and offers feasible methods for future large area flexible electronics manufacturing.

Preparation of Silicon Carbide hollow fiber Membrane in Low Temperature by Precursor Pyrolysis

The silicon carbide (SiC) powder is covered with polycarbosilane (PCS), N-Methyl pyrrolidone (NMP) is a solvent, polyethersulfone (PES) is a bonding aid, using phase-phase and solid-phase sintering process combined with a step-by-step molding to prepare a symmetrical structure of silicon carbide hollow fibers, and determine the membrane’s perforation and purification and purity of the water distribution and the circumference of the membrane. The results show that the SiC membrane tube is a finger-hole structure layer-spongy structure layer-finger-hole structure structure, the optimal sintering temperature is at 1200 °C, the size of the prepared ceramic membrane aperture is concentrated in about 0.9 μm, and the pure water flux is 2.832m3 / (m2⋅h).

Structural design and development of a water transfer sample

Understanding rare suspended particulate matter (including planktonic microorganisms) in the deep ocean is important but difficult to sample, for which we deigned a large-sized in-situ water sampler (200-1000L), i.e., a large volume water transfer system sampler. The system comprises of a deep-ocean pump, a filtering device, data acquisition and control devices, a supporting frame, a power supply component, a connecting mechanism, and a flow meter, etc. The filtering device integrates membranes for three-graded filtration at 0.22, 1, and 5μm, and an additional membrane aperture upon the need. The control device adopts two working modes: depth trigger and time trigger. The system can be added with a CTD and a fluorescence meter, etc. In addition, for a stationed site survey, several sets (such as 3 sets) of the system can be fixed at an interval on the suspension cable to work at different depths simultaneously. The system can be applied for high-level multi-layer filtration to obtain suspended particles. The system has been applied in several marine expeditions. The development of this system provides an ideal tool for deep-ocean in-situ sampling technology in China. The applications of the large volume water transfer system sampler for in-situ sampling in deep-ocean have been launched for a few times. Some interesting phenomena have been discovered and the advantages of in situ sampling are proved.