Μm Pore Diameter Research Articles

Fabrication of low thermal conductivity yttrium silicate ceramic flat membrane for membrane distillation

This paper reports on the successful fabrication of γ-Y2Si2O7 membranes with low thermal conductivity, which is an important membrane property for achieving high performance in membrane distillation process. Single-phase γ-Y2Si2O7 powder was first synthesized by calcination of SiO2 and Y2O3 powders, with 3 wt% LiYO2 as a sintering aid. The membrane was produced by tape-casting of a suspension of this powder. After sintering at 1300 °C for 4 h, a flat membrane was obtained, which had a thickness of 0.5 mm, 49% porosity, 0.9 μm pore diameter, and low thermal conductivity of 0.497 W/m⋅K at 32 °C, and 0.528 W/m⋅K at 100 °C. The obtained membrane presented hydrophobic features (water contact angle was 132°) after surface modification, which resulted in formation of a strongly adhered robust hydrophobic SiNCO nanoparticle layer on its surface. The resultant hydrophobic membrane was tested in water desalination experiments using a sweeping gas membrane distillation (SGMD) device. High water flux of 10.07 L⋅ m−2⋅ h−1 was achieved for a 20 wt% NaCl feeding solution and a temperature at the feed of 90 °C. Stable water flux and rejection rates were recorded in long-term experiments (>400 h).

Human iPS derived progenitors bioengineered into liver organoids using an inverted colloidal crystal poly (ethylene glycol) scaffold

Generation of human organoids from induced pluripotent stem cells (iPSCs) offers exciting possibilities for developmental biology, disease modelling and cell therapy. Significant advances towards those goals have been hampered by dependence on animal derived matrices (e.g. Matrigel), immortalized cell lines and resultant structures that are difficult to control or scale. To address these challenges, we aimed to develop a fully defined liver organoid platform using inverted colloid crystal (ICC) whose 3-dimensional mechanical properties could be engineered to recapitulate the extracellular niche sensed by hepatic progenitors during human development. iPSC derived hepatic progenitors (IH) formed organoids most optimally in ICC scaffolds constructed with 140 μm diameter pores coated with type I collagen in a two-step process mimicking liver bud formation. The resultant organoids were closer to adult tissue, compared to 2D and 3D controls, with respect to morphology, gene expression, protein secretion, drug metabolism and viral infection and could integrate, vascularise and function following implantation into livers of immune-deficient mice. Preliminary interrogation of the underpinning mechanisms highlighted the importance of TGFβ and hedgehog signalling pathways. The combination of functional relevance with tuneable mechanical properties leads us to propose this bioengineered platform to be ideally suited for a range of future mechanistic and clinical organoid related applications.

Assessment of corneal and conjunctival metaplasia by impression cytology during the treatment of canine keratoconjunctivitis sicca.

The purpose of this study was to assess the condition of cells in the conjunctiva and corneal epithelium prior to and during cyclosporine- or tacrolimusbased treatment of keratoconjunctivitis sicca (KCS). The study was performed on 40 dogs with KCS. The dogs were divided into two groups of 20 animals each. In Group I, 0.75% cyclosporine eye drops were administered three times a day, while in Group II 0.02% tacrolimus eye drops were administered twice daily. Additionally, each group was subdivided into three subgroups based on the results of the Schirmer I tear test (STT I). Evaluation of cellular metaplasia in the cornea and the palpebral and bulbar conjunctiva based on the Nelson-Adams scale was performed by impression cytology using Millipore round filters (Millipore VSWP 01300 DA) of 25 μm pore diameter applied to the studied area. Ophthalmological and cytological examinations were performed prior to the treatment as well as after one and two months of therapy. In both groups, a decrease in Nelson-Adams values was observed, corresponding to the increasing STT values [Rxy Spearman statistically significant correlation coefficient values between -0.75 (P < 0.001) and -0.45 (P < 0.01)]. The absence of goblet cells was observed in all dogs, regardless of the KCS stage. Goblet cells reappeared following both tacrolimus- and cyclosporine-based treatment in impression cytology specimens classified as 0 in the Nelson-Adams scale. The extent of corneal and conjunctival metaplasia in the course of tacrolimus- and cyclosporine-based treatment of KCS decreases with increasing STT values.

The behaviour of zirconium and hafnium during water-rock interaction

Zr and Hf are two elements with same ionic charge and similar ionic size at a given coordination number. Despite the Zr/Hf ratio is quite constant in meteorites and lithospheric rocks, in natural waters can be either higher or lower compared to values of interacting minerals and rocks. Here, we reanalyze very recent published and present new data on continental and brine waters indicating that the Zr and Hf behavior is dependent on the properties of the authigenic phases formed during the water-rock interaction process. Our results show that water pH in the range between 1 and 9 and water ionic strength in the range between 0.001 and 4 mol kg−1 are responsible for the change of the Zr/Hf ratio. However, analyzing the colloidal fraction comprising Fe-oxyhydroxides, carbonate and clay minerals (occasionally gypsum and halite), obtained by ultrafiltration at the dimension between 10 kDa and 0.45 μm diameter pore, we found that the Zr/Hf molar ratio is very low and variable between 5 and 35. We propose that the dissolved Zr/Hf ratio is dependent on the morphological and electrical properties of authigenic mineral surfaces and emphasize the lack of a quantitative evaluation of the ion speciation of Zr and Hf in natural waters and brines limiting the transport prediction of Zr and Hf during the complex water-rock interaction process.

Influence of porosity of low-density polyethylene media on the maturation process of biofilters used in recirculating aquaculture systems

The effect of pores with different diameters in polyethylene media on the process of ammonia nitrification during the maturation of biofilters is evaluated. Four types of media were produced: M1 without pores, M2 with 40–112 μm in diameter pores, M3 with 125–187 μm diameter pores, and M4 with 312–437 μm diameter pores. Ammonia concentrations were statistically equal among media. On the majority of days, nitrite concentrations were lowest for M1 and M2, intermediate for M3, and highest for M4. Increased pore diameter favored the formation of biofilm in the interior, but the pores obtained in the expansion process were not interconnected, which may have caused low oxygenation of the water in the internal area. It was concluded that porosity did not reduce biofiltration time and did not increase the efficiency of nitrification of ammonia.

Rotating Membrane Emulsification for Producing Single and Multiple Emulsions

Membrane emulsification is a technique utilising a novel concept of generating droplet ‘drop by drop’ to produce emulsions. The technique has several distinctive advantages over the conventional emulsification techniques.This paper concerns on the development of membrane emulsification (Rotating Membrane Reactor, RMR) which utilizes rotating tubular membrane to initiate droplet detachments. The RMR uses a rotating stainless steel tubular membrane with laser drilled pores (100 μm pore diameter) and a syringe pump to drive the dispersed phase through the membrane at a given flow rate. O/W formulations were prepared with low viscosity of paraffin wax, two types of emulsifiers, different membrane rotation rate and dispersed phase flow rate. The emulsion droplets exhibited a coefficient of variation of 9% and 81μm droplet size. In this research, the pore size/droplet size ratio could achieve 0.8. This value was below than other membrane emulsification processes. The effects of principal system operating parameters on both the average droplet diameter and droplet uniformity were discussed. In addition, a multiple (W/O/W) emulsion formulation was investigated as well.

Design and characterization of macroporous alumina membranes for passive samplers of water contaminants

Macroporous ceramic membranes with hierarchical pore structure were developed and characterized for the time-integrated analysis of water contaminants. The alumina membranes were boosted to allow a suitable diffusion rate for envisaged applications. Sacrificial fugitives as cornstarch and graphite and partial sintering technique were utilized for the control of pore structure and morphology. The present study includes: (i) Development of ceramic membrane preparation methods based on wet forming techniques and partial sintering in order to control of membrane parameters such as porosity, tortuosity factor and thickness; (ii) Microstructural characterization of the ceramic membranes using two complementary techniques: Hg-porosimetry and SEM; (iii) the diffusion tests performed under laboratory conditions by an innovative, easy and accurate method based in the use of methylene blue (C16H18ClN3S) water solutions as test compound to study the characteristics of ceramic membranes. Using slip casting and partial sintering processing three different Al2O3 membrane configurations with high values 34.5, 36.9 and 39.6 vol% of interconnected porosity and 1.75, 1.7 and 1.3mm thickness were prepared. The pore morphology consisted of spherical cavities of 5-10 μm diameter and small pores of 70–200nm. This study also gathers the basis for the calculation of diffusion coefficients, membrane geometrical factor and sampling rates using methylene blue water solutions whose concentration can be accurately determined by optical absorption measurements at 664nm. Diffusion coefficients for methylene blue range from 2.3±0.5E-8 to 3.0±0.5E-8cm2s−1 increasing as connected porosity increases and membrane thickness decreases. The membrane geometrical factors are low, between 0.6 and 1E-02 and Archie’s constants large 4.5–5.5. This has been associated to the bimodal pore structure with coexistence of large and small pores that may increase the tortuosity factors in membranes. The macroporous ceramic membranes herein developed are suitable for the fabrication of passive samplers aimed at preconcentrating organic contaminants in water.

Crossflow microfiltration coupled with diafiltration to concentrate and purify carotenoids and flavonoids from citrus juices

Abstract This work aimed to evaluate an eco-friendly process based on microfiltration with a diafiltration stage in order to concentrate and purify the main carotenoids and flavonoids in citrus juices. Pilot plant scale trial parameters were: tubular ceramic membranes with 0.2 μm pore diameter, 40 °C and 3 bar of transmembrane pressure. Different operating conditions were tested varying volumetric reduction ratio (VRR) from 2.5 to 10 and diavolume (DV) up to 1.7. Permeate flux ranged from 20 to 100 L h− 1 m− 2 according to the VRR. The concentration was multiplied by 5 to 10 for carotenoids and hesperidin but only by 2 to 3 for narirutin. Diafiltration increased the purity of carotenoids and hesperidin from 8 to 20 times. A model was validated for prediction of the concentration and purification factors vs. VRR and DV and the retentions were 100%, 97% and 63% for carotenoids, hesperidin and narirutin.

Injectable glycosaminoglycan–protein nano-complex in semi-interpenetrating networks: A biphasic hydrogel for hyaline cartilage regeneration

Articular hyaline cartilage regeneration remains challenging due to its less intrinsic reparability. The study develops injectable biphasic semi-interpenetrating polymer networks (SIPN) hydrogel impregnated with chondroitin sulfate (ChS) nanoparticles for functional cartilage restoration. ChS loaded zein nanoparticles (∼150nm) prepared by polyelectrolyte-protein complexation were interspersed into injectable SIPNs developed by blending alginate with poly(vinyl alcohol) and calcium crosslinking. The hydrogel exhibited interconnected porous microstructure (39.9±5.8μm pore diameter, 57.7±5.9% porosity), 92% swellability and >350Pa elastic modulus. Primary chondrocytes compatibility, chondrocyte-matrix interaction with cell–cell clustering and spheroidal morphology was demonstrated in ChS loaded hydrogel and long-term (42days) proliferation was also determined. Higher fold expression of cartilage-specific genes sox9, aggrecan and collagen-II was observed in ChS loaded hydrogel while exhibiting poor expression of collagen-I. Immunoblotting of aggregan and collagen II demonstrate favorable positive influence of ChS on chondrocytes. Thus, the injectable biphasic SIPNs could be promising composition-mimetic substitute for cartilage restoration at irregular defects.

Abstract 2912: Size based enrichment and sorting of Ov90 cancer cells and clusters with a new multistage filtration cartridge reveals distinct phenotypes

Abstract Background: Circulating tumor cells (CTCs) are released in blood from the primary tumor, but although very heterogeneous both in size and marker expression, are very rare and provide information not available from the primary tumor. The identification of CTC cells and clusters could advance our understanding of metastasis and help personalize therapy.1,2 Notably, CTC clusters were shown to have a higher metastatic potential than single cells3 but the process remains poorly understood. We present a multistage filtration system with pore sizes from 20 down to 8 μm for the size-selective enrichment of Ov90 ovarian cancer cells and clusters from blood. Each captured cell population was released, cultured and characterized independently. Methods: We developed a 3D printed multistage filtration cartridge and polymer filters with 20, 15, 12, 10 and 8 μm-diameter pores. Filters were stacked from 20 (top) to 8 μm (bottom) and used to enrich and sort Ov-90 cells spiked in 1:6 mL of blood:PBS. Captured cells were released by removing individual filters from the cartridge, reverse flowing OSE medium, and then cultured separately. Results: Ov-90 clusters were found mostly on the top filter (20 μm) and interestingly, few small clusters (3-4 cells) were found on the 8 and 10 μm filters, suggesting alignment of cluster cells as they pass through the pores.4 Cell and nucleus diameters were measured, and a general correlation was found between filter pore size and cell and nucleus size. Interestingly, nucleus size was found to be the single most significant parameter in determining passage of single cells and small clusters through pores. Following cell culture, two distinct phenotypes were observed: cell captured on small pore filters (8-12 μm) grew primarily in a monolayer. Cells captured on filters with larger pores (15-20 μm) first grew as monolayer, but rapidly formed cell aggregates that subsequently detached from the surface. Staining for E-Cadherin, a cell-cell adhesion protein, revealed a loss of expression of cells from filter with larger pores. Conclusion: We developed a new multistage filtration method and selectively enriched and sorted cells based primarily on their nucleus size. We identified two Ov-90 populations with different growth behaviors with low E-cadherin expression on the cells forming clusters, which is known to correlate with metastasis. The application of multistage filters may also reveal different CTC populations based on nucleus and cell size.

Characteristics of Pores as Measured by Porosimetry and Microscopy Considering Spaghetti as a Model System

Abstract Open pore porosity of spaghetti was measured by helium (He) gas pycnometer and mercury (Hg) porosimetry and it was observed as 0.025 and 0.023, respectively. Pore size distribution curve from mercury porosimetry indicated two sharp crests, at alternate position of 59±8 μm and 6.4±0.9 μm diameter pore; while Scanning Electron Microscopy (SEM) showed two types of pores, first class was cracks and second one was holes. The average width of the cracks (channel) and diameters of holes were determined as 3.6±1.5 µm and 1.0±0.3, respectively. The moisture sorption isotherm of spaghetti was measured by dynamic sorption method and modeled by Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAM) models. The values of BET monomolecular layer were observed as 3.24 and 5.91 kg water/kg dry solids, respectively for adsorption and desorption cycles.

Bioresorbable Fe–Mn and Fe–Mn–HA Materials for Orthopedic Implantation: Enhancing Degradation through Porosity Control

Resorbable, porous iron-manganese-hydroxyapatite biocomposites with suitable degradation rates for orthopedic applications are prepared using salt-leaching for the first time. These transient biomaterials have the potential to replace inert, permanent implants that can suffer from long-term complications, or have to be surgically removed, leaving an unfavorable void. Fe30Mn-10HA materials are newly developed to address inadequate resorption rates of degradable materials proposed for orthopedic environments in the past. In this study, controllable porosities with 300 µm diameter pores are introduced into Fe30Mn alloys and Fe30Mn-10HA composites, which enhance tissue ingrowth. For the composites, a Ca2 Mn7 O14 phase generated within the Fe30Mn matrix during the sintering process greatly increases degradability. The combination of this second phase and added porosity is found to contribute to increased bone-like apatite layer formation, mouse bone marrow mesenchymal stem cell attachment, and reduction of detrimental oxide layer flaking. Remarkably, after thirty days in vitro, there is a significant increase in degradation up to 0.82 ± 0.04 mm per year for 30 wt% porous Fe30Mn-10HA biocomposites, compared to 0.02 ± 0.00 mm per year for traditional nonporous Fe30Mn, thereby increasing the viability of these materials for future clinical studies.

Evaluation of concentration measurement techniques of colloidal nanoparticles for microfiltration and ultrafiltration applications: Inductively coupled plasma-mass spectrometry, nanoparticle tracking analysis and electrospray-scanning mobility particle sizer

Abstract Three different liquid-borne particle concentration measurement methods, including the inductively coupled plasma-mass spectrometry (ICP-MS), nanoparticle tracking analysis (NTA) and electrospray-scanning mobility particle sizer (ES-SMPS), for determining the efficiency of liquid filtration were investigated and compared for their applicability and feasibility. These methods were first calibrated using commercial Au monospheres with various sizes from 5 to 50 nm and several sizes of NIST traceable polystyrene latex (PSL) from 20 to 125 nm. Calibration results showed that the prepared concentrations of liquid-borne particles according to that provided by the manufacturers were proportional to the concentrations measured by all these methods. The calibration results were then used to determine the filtration efficiencies of Au and PSL nanoparticles through the 0.1 μm pore diameter polycarbonate track-etched (PCTE or Nuclepore filter) membrane filters, which were performed as the dead-end type filtration. It was found that the filtration efficiencies obtained by different measurement methods under the same condition were comparable with each other. The results of this study provide a very useful guidance in selecting the proper method for liquid-borne particle filtrations under different circumstances.

3D microporous Sn-Sb-Ni alloy impregnated Ni foam as high-performance negative electrode for lithium-ion batteries

A novel, “active-active-inactive” type Tin-Antimony-Nickel alloy with dendritic morphology electrodeposited on 3D interconnected microporous Nickel foam (∼8 μm pore diameter) as a potential high capacity anode for Li-ion batteries is reported. The multiphase composition comprising of SnSb and Ni3Sn4 “reactant” intermetallics dispersed in Sn “matrix”, alleviates the volumetric stress generated during cycling by lithiating at different step potentials (0.84, 0.66, 0.57, 0.42, 0.40, and 0.38–0.25 V vs. Li/Li+). Nickel foam was synthesized by template-free hydrogen bubble-assisted electrodeposition and it successfully acts as a stress buffer preventing delamination. This combination of properties for Tin-Antimony-Nickel anode impregnated into Nickel foam results in 2nd cycle discharge capacity of 845 mAh/g, superior rate capability and stable cycle retention with a capacity loss of 16% in the last 50 cycles at a rate of 430 mA/g (0.5 C), while preserving its structural integrity and micro-architecture in comparison to a Tin-Antimony-Nickel anode deposited on a planar Nickel film as a current collector.

A Novel Multiphase Sn-Sb-Cu Alloy Electrodeposited on 3D Interconnected Microporous Cu Current Collector as Negative Electrode for Lithium Ion Battery

We report a novel, active-active-inactive-type tin-antimony-copper alloy with dendritic morphology electrodeposited on 3D interconnected microporous copper foam (~70 μm pore diameter) as a promising high specific capacity anode for Li-ion batteries. The multiphase composition, SnSb and Cu6Sn5 “reactant” intermetallics embedded in Sn “matrix,” alleviates the volumetric stress generated during cycling by lithiating at different step potentials (0.84, 0.66, 0.57, 0.42, 0.39, and 0.38 to 0.33 V vs Li/Li+). Copper foam successfully acts as a stress buffer preventing both pulverization and delamination. This combination of properties in tin-antimony-copper anode on copper foam results in 2nd cycle discharge capacity of 723 mAh/g, superior rate capability, and stable cycle retention with a capacity loss of 16 pct in the last 70 cycles at a rate of 400 mA/g (0.5 C) while preserving its structural integrity in comparison to tin-antimony-copper anode deposited on a planar copper foil as a current collector.

Biodegradable Porous Silk Microtubes for Tissue Vascularization.

Cardiovascular diseases are the leading cause of mortality around the globe, and microvasculature replacements to help stem these diseases are not available. Additionally, some vascular surgeries needing small diameter vascular grafts present different performance requirements. In this work silk fibroin scaffolds based on silk/polyethylene oxide blends were developed as microtubes for vasculature needs and for different tissue regeneration times, mechanical properties and structural designs. Systems with 13, 14 and 15% silk alone or blended with 1 or 2% of polyethylene oxide (PEO) were used to generate porous microtubes using gel-spinning. Microtubes with inner diameters (ID) of 150-300 μm and 100 μm wall thickness were fabricated. The systems were assessed for porosity, mechanical properties, enzymatic degradability, and in vitro vascular endothelial cell attachment and metabolic activity. After 14 days all tubes supported the proliferation of cells and cell attachment increased with porosity. The silk tubes with PEO had similar crystallinity but higher elastic modulus compared with the systems without PEO. The silk (13%)/PEO (1%) system showed the highest porosity (20 μm pore diameters on average), highest cell attachment and fastest degradation profile. There was a good correlation between these parameters with silk concentration and the presence of PEO. The results demonstrate the ability to generate versatile and tunable tubular biomaterials based on silk-PEO-blends with potential for microvascular grafts.

Influence of erythrocyte anisocytosis on filterability through 3 µm diameter pores

Influence of erythrocyte anisocytosis on filterability through 3 µm diameter pores

Peptide-Mediated Platelet Capture at Gold Micropore Arrays.

Ordered spherical cap gold cavity arrays with 5.4, 1.6, and 0.98 μm diameter apertures were explored as capture surfaces for human blood platelets to investigate the impact of surface geometry and chemical modification on platelet capture efficiency and their potential as platforms for surface enhanced Raman spectroscopy of single platelets. The substrates were chemically modified with single-constituent self-assembled monolayers (SAM) or mixed SAMs comprised of thiol-functionalized arginine-glycine-aspartic acid (RGD, a platelet integrin target) with or without 1-octanethiol (adhesion inhibitor). As expected, platelet adhesion was promoted and inhibited at RGD and alkanethiol modified surfaces, respectively. Platelet adhesion was reversible, and binding efficiency at the peptide modified substrates correlated inversely with pore diameter. Captured platelets underwent morphological change on capture, the extent of which depended on the topology of the underlying substrate. Regioselective capture of the platelets enabled study for the first time of the surface enhanced Raman spectroscopy of single blood platelets, yielding high quality Raman spectroscopy of individual platelets at 1.6 μm diameter pore arrays. Given the medical importance of blood platelets across a range of diseases from cancer to psychiatric illness, such approaches to platelet capture may provide a useful route to Raman spectroscopy for platelet related diagnostics.

Fabrication of 3D porous MoS2–GO nanocomposite monolith as a promising adsorbent

AbstractThree-dimensional (3D) nanocomposite monolith containing MoS2 nanoflakes, graphene oxide (GO) and amorphous SiO2 was fabricated through a simple mixing process and hydrothermal treatment. Compared with GO monolith prepared under identical conditions, the MoS2–GO monolith had larger specific surface area, smaller pore diameter, as well as much higher adsorption capacity for Cu2+ and Rhodamine B. Introducing amorphous SiO2 into the end monolith by using tetraethyl orthosilicate as a reactant in the synthesis reduced shrinkage and produced a greater number of large pores (&gt;1 μm pore diameter) in the monolith. The specific surface area and pore diameter of the MoS2–GO monolith were 321.4 m2 g−1 and 11.71 nm, respectively. The higher adsorption capacity was ascribed to the presence of many S atoms in the MoS2 nanoflakes inside the monolith.

Growth and Attachment-Facilitated Entry of Bacteria into Submicrometer Pores Can Enhance Bioremediation and Oil Recovery in Low-Permeability and Microporous Media

Bioremediation end points for biodegradable hydrophobic compounds in soil aggregates are regulated by bacterial accessibility to different pore sizes. We evaluated the accessibility of the nonmotile hydrocarbon-degrading bacterium Dietzia maris (d = 1 μm in the stationary phase) to 0.4 μm pores. A significant fraction (22%) of the pore volume of the clayey soil from which the bacterium was isolated was associated with 0.4–1 μm diameter pores. The entry of bacteria into the pores was observed by electron microscopy and by monitoring mineralization of [14C]hexadecane placed well above membranes with fixed pore sizes (0.4 or 3 μm), in a bioreactor. The membranes were used as a surrogate for soil pores of fixed diameters. When membranes were not wetted or were wetted with nonbiodegradable heptamethylnonane, bacteria did not penetrate pores even if they attached to the membrane. However, bacteria penetrated pores when membranes were wetted with hexadecane, as growth on hexadecane yielded a crowd of smaller rod...