Μm Pore Diameter Research Articles

Effects of pasteurization, microfiltration, and ultraviolet-c treatments on microorganisms and bioactive proteins in bovine skim milk

Effects of high-temperature short-time (HTST) pasteurization, microfiltration (MF) with 1.4/0.8 μm pore diameters, and ultraviolet-c (UV-C) irradiation with a coiled tube reactor on reducing microorganisms and somatic cells, and retaining bioactive proteins/enzymes along with protein oxidation in skim milk were studied. Bacteria were reduced by 2.3 log using HTST and UV-C, and 3.0 log using MF. Coliforms were not detected after all treatments. Spores were unaffected by HTST, reduced by 0.3 log using UV-C, and not detected after MF. Somatic cells remained unaffected by HTST and UV-C, and were undetectable after MF. Bioactive xanthine oxidase (XO), immunoglobulin G (IgG), lactoperoxidase (LPO), lactoferrin (LF), IgM, and IgA were retained at 87, 78, 69, 57, 48, and 41% using HTST, and 100% using UV-C and MF-1.4, while MF-0.8 retained fully the IgG and LPO, and 93, 92, 91, and 86% of IgA, XO, LF, and IgM. Native serum proteins were retained at 89% using HTST, 95% using UV-C, and 100% using MF. Carbonyls were increased by 26% using UV-C, and sulfhydryls were reduced by 14% using HTST, while both were unaffected using MF. Flux for MF-1.4 was higher and remained steady after an initial decrease of 12%, while flux for MF-0.8 decreased progressively by 45% until end of processing, resulting in complete and 89% passages of casein micelles using MF-1.4 and MF-0.8. MF-1.4 and UV-C could be proposed as nonthermal technologies alternatives or as hurdle-technologies to HTST for reducing microorganisms while retaining bioactive proteins/enzymes in skim milk, without inducing significant oxidative effects.

3D quantification of short vertical neurites in membrane pores and their differentiation from other cell parts

Scientific efforts towards nerve regeneration and nerve-electrode interfaces depend on the possibility of guided neurite growth. The quantification and tracing of neurite growth during experiments is therefore essential. While tracing is possible under 2D cell culture conditions, it gets more complex when analysing three dimensionally orientated neurite pathways resulting in the ongoing development of 3D neuron tracing software. However, the quantification of short vertical neurite sprouts remains complicated due to difficult distinction from small cell body parts. With this study, we present a new method for precise identification and quantification of short neurite sprouts growing vertically from the surface of a track-etched membrane into 8 μm diameter pores of the membrane. Based on collected radius data from identified horizontally orientated neurites, a 95% reference interval for average radii of neurites was established and the limits were applied to trace neurite sprouts in the membrane's pores. Following this procedure, neurites were successfully distinguished from small cell body parts. This study demonstrates how to identify short neurite sprouts by assessing number, length, and radius with an additional checkpoint for bias detection.

Biocompatibility and Osseointegration of Calcium Phosphate-Coated and Non-Coated Titanium Implants with Various Porosities.

The aim of the investigation was to study the influence of pore size and the presence of a biologically active calcium phosphate coating in porous 3D printed titanium implants on the process of integration with the bone tissue.Materials and MethodsSamples of cylindrical implants with three different pore diameters (100, 200, and 400 μm) were fabricated from titanium powder on the Arcam 3D printer (Sweden) using electron beam melting technology. A calcium phosphate coating with a thickness of 20±4 μm was applied to some of the products by microarc oxidation. Cytotoxicity of the implants was determined in vitro on human dermal fibroblast cultures. The samples were implanted in the femoral bones of 36 rabbits in vivo. The animals were divided into 6 groups according to the bone implant samples. The prepared samples and peri-implant tissues were studied on days 90 and 180 after implantation using scanning electron microscopy and histological methods.ResultsAll samples under study were found to be non-toxic and well biocompatible with the bone tissue. There were revealed no differences between coated and non-coated implants of 100 and 200 μm pore diameters in terms of their histological structure, intensity of vascularization in the early stages, and bone formation in the later stages. Samples with pore diameters of 100 and 200 μm were easily removed from the bone tissue, the depth of bone growth into the pores of the implant was lower than in the samples with pore diameter of 400 μm (p<0.001). There were differences between coated and non-coated samples of 400 μm pore diameter, which was expressed in a more intensive osseointegration of samples with calcium phosphate coating (p<0.05).ConclusionThe optimal surface characteristics of the material for repairing bone defects are a pore diameter of 400 μm and the presence of a calcium phosphate coating.

Additive Manufacturing of Porous Ti6Al4V Alloy: Geometry Analysis and Mechanical Properties Testing

This work is devoted to the research of porous titanium alloy structures suitable for use in biomedical applications. Mechanical properties were examined on six series of samples with different structures and porosity via static compressive test to identify the type of structure suitable for elimination of the “stress shielding” effect. In addition, high porosity is desirable due to the overgrowth of bone tissue into the internal structure of the implant. The samples were made of titanium alloy Ti6Al4V by using selective laser melting (SLM) additive manufacturing. The series of samples differ from each other in pore size (200, 400, and 600 µm) and porous structure topology (cubic or trabecular). The actual weight of all samples, which plays an important role in identifying other characteristics, was determined. Compressive tests were focused on the detection of maximum stress. The highest porosity and thus the lowest weight were achieved in the samples with a trabecular structure and 600 µm pore size. All tested samples reached optimal values of maximum stress and tensile strength. The most appropriate mechanical properties were observed for samples with a 200 µm pore diameter and cubic structure.

Nerve Response to Superelastic Shape Memory Polyurethane Aerogels.

We have previously shown the suitability of aerogels as scaffolds for neuronal cells. Here, we report on the use of superelastic shape memory polyurethane aerogels (SSMPA). SSMPA have a distinctly different stiffness than previously reported aerogels. The soft and deformable nature of SSMPA allowed for radial compression of the aerogel induced by a custom designed apparatus. This radial compression changed the pore diameter and surface roughness (Sa) of SSMPA, while maintaining similar stiffness. Two varieties of SSMPA were used, Mix-14 and Mix-18, with distinctly different pore diameters and Sa. Radial compression led to a decreased pore diameter, which, in turn, decreased the Sa. The use of custom designed apparatus and two types of SSMPA allowed us to examine the influence of stiffness, pore size, and Sa on the extension of processes (neurites) by PC12 neuronal cells. PC12 cells plated on SSMPA with a higher degree of radial compression extended fewer neurites per cell when compared to other groups. However, the average length of the neurites was significantly longer when compared to the unrestricted group and to those extended by cells plated on SSMPA with less radial compression. These results demonstrate that SSMPA with 1.9 µm pore diameter, 1.17 µm Sa, and 203 kPa stiffness provides the optimum combination of physical parameters for nerve regeneration.

Suppression of Dendritic Growth on Li Negative Electrode for All-Solid-State Rechargeable Battery

Introduction All-Solid-State Lithium Battery (ASSLiB) is expected as one of the next-generation batteries to achieve high power and energy density and high safety. Applying the Li metal negative electrode with a high mass capacity and low standard electrode potential to the ASSB system is desirable; however, there is a critical problem of the Li dendritic growth which induces internal short-circuits. The Li dendritic growth is known to proceed even in the voids and cracks of solid electrolytes (SEs). Moreover, because the Li metal electrode is sandwiched between a current collector and SE, high mechanical stress due to volume expansion is applied to the electrode/SE interface during charging. For conventional planer current collectors, Li metal easily penetrates into SE through voids for the relaxation of mechanical stress (Fig. 1a). In contrast, for porous current collectors, the mechanical stress will be reduced because the deposited Li-metal can fill pores. In this study, we investigated the usefulness of an Au-coated membrane filter with micro-size pores as a porous current collector for suppressing the Li dendritic growth (Fig. 1b).1 Experimental A porous current collector was prepared by cutting a commercial membrane filter (Advantec, 16080004) with 8 µm-diameter pores and 7 µm-thickness into a circular shape. Gold or nickel was coated with a sputter coater to give electric conductivity. The gold-coated porous current collector is named as Au-MF, and nickel-coated one is named as Ni-MF.A laboratory-made cell was assembled in an Ar-filled grove box. Li3PS4-glass electrolyte as SE was prepared by mechanical-milling according to ref. 1, and pelletized in a polycarbonate tube. Gold was coated on the negative electrode side of the SE pellet. The SE was put between the porous current collector and Li-In alloy as the counter electrode, followed by pressing to obtain an ASSB cell.All charge/discharge measurements were conducted by galvanostatic technique at 30 ℃. The charge/discharge current density and deposition capacity for evaluating coulombic efficiency were 0.1 mA cm-2 and 0.1 mAh cm-2, respectively. Li deposition behavior in the porous current collectors was investigated by scanning electron microscope (SEM). Results and Discussion Fig. 2(a) shows an SEM image of the Au-MF as prepared. Circular pores with 8 µm in diameter are vertically and sparsely located. After charging at 0.010 mA cm-2 for 10 h, the surface morphology of Au-MF changed like moss (Fig. 2(b)), which means Li was deposited on the surface of Au-MF. When the Ni-MF, in which Ni layer does not form any alloys with Li, was used to charge at the current density of 0.010 mA cm-2 for 10 h, Li deposits were observed only in the pores of Ni-MF and surface morphology did not change (Fig. 2(c)). These results suggest that the Li deposition on Au-MF is due to the Li diffusion in the Au layer on the MF, and the mechanical stress on the Au-MF/SE interface is relaxed by the Li deposition in pores.Fig. 3 shows Coulombic efficiencies of Au-MF, Ni-MF, planer Ni foil and Au-coated Ni-foil as a function of cycle number. The Coulombic efficiency reached to the maximum at the 4th cycle in each case. The Au-MF showed the highest coulombic efficiency of 82 %, while other electrodes showed lower than 80 % values. The charge/discharge curve for the Ni foil and Ni-MF showed the short-circuit at the 8th cycle; however, the Au-MF and the Au-coated Ni foil did not make a short-circuit for 20 cycles. These results indicate Au-MF is superior in coulombic efficiency and the suppression of Li dendritic growth to the other current collectors.We assume the synergetic effect of Au-coating and pores on the current collector. During charging, the electrochemically prepared Li metal diffuses to the pores through the Au layer and fills the pores. This effective filling of the pores with Li metal is essential for suppressing the Li dendritic growth. The Coulombic efficiency depends on the amount of the dead Li, which is formed by interruption of conduction during the dissolution of lithium deposited in dendrite form. Preventing the dendritic growth of Li metal also leads to the increase in the Coulombic efficiency.In conclusion, the Au-coated porous current collector can effectively work for inhibiting the Li dendritic growth. Acknowledgement This work was partially supported by JST ALCA-SPRING. References Shinzo et. al., ACS Appl. Mater. Interfaces (2020), 12, 20, 22798 Figure 1

Effect of Dynamic Chemical Etching on the Pore Structure, Permeability, and Mechanical Properties of Ti-Nb-Zr Scaffolds for Medical Applications

Abstract Improving the post-processing of metallic porous tissue scaffolds is an essential step to create a new generation of superelastic implants for the replacement of damaged bone tissue. In this study, the dynamic chemical etching technique is applied to improve the permeability and to optimize the porous structure of Ti-Nb-Zr scaffolds fabricated by the powder metallurgy-based space holder technique. The etched scaffolds are characterized in terms of their porous structure geometry, permeability, and mechanical properties. It is shown that an increase in porosity from 49% to 54% during the etching is mainly due to an increase in the number of 100 to 800 μm-diameter pores, from 30% to 50% of them measuring from 100 to 300 μm in size. These changes in the porous structure lead to a significant increase of its permeability, i.e., from (0.1–15) × 10−11 m2 before etching to (44–91) × 10−11 m2, after etching; these permeability ranges corresponding to those of bone tissues. Furthermore, the etched scaffolds show systematically higher yield compressive stresses as compared to the as-sintered scaffolds of equivalent porosities. Finally, the highly permeable etched Ti-Nb-Zr scaffolds with a porosity varying from 40% to 60% exhibit an apparent Young’s modulus ranging from 8.6 to 1.9 GPa and an ultimate compressive strength from 650 to 190 MPa, which can be considered as a promising balance of properties for the potential use of these scaffolds as bone implants.

Concentration and purification by crossflow microfiltration with diafiltration of carotenoids from a by-product of cashew apple juice processing

This work aimed to further investigate microfiltration with diafiltration to obtain a rich carotenoid extract from the solid by-product of cashew apple (Anacardium occidentale L.) juice processing. This solid residue called cashew fibers is rich in bioactive compounds, especially carotenoids. After mixing with water and pressing, an aqueous suspension was obtained and processed by crossflow microfiltration (40 °C) using tubular ceramic membrane with 0.2 μm pore diameter. Permeate flux, which increased with transmembrane pressure, could be maintained above 100 L·h−1·m−2 at high volume reduction ratio by coupling mechanical extraction with enzyme liquefaction. The concentration step led to an increase of the carotenoid content by up to 19-fold and the diafiltration step allowed the carotenoid purity to be multiplied by 5. The impact of the process on the retentate characteristics was assessed using a model based on simple assumptions. This calculation tool can easily be implemented and is helpful for choosing the operating conditions, to minimize water consumption as well as effluent production.

Valorization of palm biomass waste into carbon matrices for the immobilization of recombinant Fusarium heterosporum lipase towards palm biodiesel synthesis

Continuous expansion of agriculture for the production of biofuels may be considered a potential source of greenhouse gas (GHG) emissions due to the ever-increasing amount of waste and fossil fuel-dependent materials involved. Agricultural waste utilization through the circular bioeconomy concept offers a pathway to reduce GHG emissions. Palm oil production, for instance, produces palm kernel shells (PKS) and palm oil mill effluents (POME) as wastes in enormous amounts. PKS and POME account for >60% of solid and liquid waste generated from the mill. In this work, the feasibility of a circular palm bioeconomy is explored where waste PKS is directly converted to activated carbons (AC) in a cost-effective one-step technique (550 °C, 10 mL min−1 N2) that departs from the conventional two-step (carbonization and activation) technique. Characterization of the synthesized carbons, PKAC, using Fourier-transform infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy showed oxygen-rich morphological features that were 2-fold higher than in bituminous coal-derived AC. The <10 μm pore diameters of PKAC were relevant in the immobilization of Aspergillus oryzae whole-cells expressing Fusarium heterosporum lipase (PKAC-FHL). For biodiesel production, the 81.6 IU mg−1 specific activity of PKAC-FHL yielded ≥97.5 wt% fatty acid methyl ester (FAME) from POME. While offering the benefits of environmental remediation through effluent utilization, the produced FAME showed 48.8 Cetane Number and cold-flow properties that conform to ASTM and EN biodiesel requirements. This waste valorization approach, thus, proposes a green framework for the use of POME and PKS in immobilized lipase-catalyzed methanolysis.

The effect of pore diameter on neo-tissue formation in electrospun biodegradable tissue-engineered arterial grafts in a large animal model

To date, there has been little investigation of biodegradable tissue engineered arterial grafts (TEAG) using clinically relevant large animal models. The purpose of this study is to explore how pore size of electrospun scaffolds can be used to balance neoarterial tissue formation with graft structural integrity under arterial environmental conditions throughout the remodeling process. TEAGs were created with an outer poly-ε-caprolactone (PCL) electrospun layer and an inner sponge layer composed of heparin conjugated 50:50 poly (l-lactide-co-ε-caprolactone) copolymer (PLCL). Outer electrospun layers were created with four different pore diameters (4, 7, 10, and 15 µm). Fourteen adult female sheep underwent bilateral carotid artery interposition grafting (n = 3–4 /group). Our heparin-eluting TEAG was implanted on one side (n = 14) and ePTFE graft (n = 3) or non-heparin-eluting TEAG (n = 5) on the other side. Twelve of the fourteen animals survived to the designated endpoint at 8 weeks, and one animal with 4 µm pore diameter graft was followed to 1 year. All heparin-eluting TEAGs were patent, but those with pore diameters larger than 4 µm began to dilate at week 4. Only scaffolds with a pore diameter of 4 µm resisted dilation and could do so for up to 1 year. At 8 weeks, the 10 µm pore graft had the highest density of cells in the electrospun layer and macrophages were the primary cell type present. This study highlights challenges in designing bioabsorbable TEAGs for the arterial environment in a large animal model. While larger pore diameter TEAGs promoted cell infiltration, neotissue could not regenerate rapidly enough to provide sufficient mechanical strength required to resist dilation. Future studies will be focused on evaluating a smaller pore design to better understand long-term remodeling and determine feasibility for clinical use. Statement of SignificanceIn situ vascular tissue engineering relies on a biodegradable scaffold that encourages tissue regeneration and maintains mechanical integrity until the neotissue can bear the load. Species-specific differences in tissue regeneration and larger mechanical forces often result in graft failure when scaling up from small to large animal models. This study utilizes a slow-degrading electrospun PCL sheath to reinforce a tissue engineered arterials graft. Pore size, a property critical to tissue regeneration, was controlled by changing PCL fiber diameter and the resulting effects of these properties on neotissue formation and graft durability was evaluated. This study is among few to report the effect of pore size on vascular neotissue formation in a large animal arterial model and also demonstrate robust neotissue formation.

Study of total suspended solid concentration based on Doxaran algorithm using Landsat 8 image in coastal water between Bodri River estuary up to east flood canal Semarang City

The water quality in the northern coastal waters estuary of Central Java has been polluted at a moderate to severe level. Water quality monitoring efforts for evaluating the condition of dissolved sedimentation can be done through total suspended solid methods by analising the remote sensing imagery. Total suspended solid (TSS) is measured by suspended material (diameter> 1 µm) which retained in the millopore filter with a 0.45 µm pore diameter. The purpose of this research is to assess the distribution of TSS concentrations in the research location. This study was conducted using Landsat 8 image data on August 9th, 2018. TSS concentration values were obtained through linear regression tests Doxaran algorithm which is the most suitable algorithm with the field condition. The results showed that: 1) The appropriate empirical algorithm for mapping TSS concentrations is the Doxaran algorithm with the TSS equation = 1.0248x - 10.503, 2) Distribution of TSS with the range >75 mg/l mostly concentrated in center and west of the study area, while the concentration with range <75 mg/l is concentrated in the east, and 3) Distribution of TSS is affected by the movement of currents driven by the wind towards the west and southwest and partly collected in the western part of the study area.

Bio-inspired TiB2-TiB-TiN lattices by selective laser melting

Selective laser melting was exploited to fabricate lattice structures from TiB2-Tipowder mixtures of high ceramic content (50wt.%TiB2). The lattice structures of 0.8 mm unit cell size were nitridized to produce TiB2-TiN ceramic-ceramic composite. During processing, TiB2 is partially transformed into TiB. Lattice structures of the TiB2-TiB-TiN composite were characterized with ~600 μm pore diameter maintaining 3.5 MPa compressive strength. Due to the viability of TiB2-TiB-TiN composites, they may be considered as the potential bio-materials.

Analysis of the Features of the Behavior of Track Membrane Filters during their Use

Changes in the properties of a FiTreM track membrane filter with a 0.45 μm pore diameter during water filtration and changes in filtration rate during continuous water filtration were studied. It was established during the experiments that the decrease in filtration rate through a track membrane filter depends both on the occurrence of suspensions and colloid compounds, as well as on the physical properties of the filter. This is also due to the change in membrane permeability due to partial destruction of a filter, its compaction during use, as well as the accumulation of a negative charge on the pore surface due to the dissociation of COOH groups.

Control of Dendritic Growth of the Lithium Metal in All-Solid-State Lithium Metal Batteries: Effect of the Current Collector with Microsized Pores.

The dendritic growth of the Li metal through a separator is a serious issue for the development of rechargeable Li metal batteries in which the Li metal is used as the negative electrode. Several methods have been investigated for this issue; however, it has not been completely solved until now. The all-solid-state battery (ASSB) system is one of the most powerful methods for practical use of the Li metal negative electrode because the solid-state electrolyte (SSE) can mechanically block the dendritic growth of Li metal. ASSBs are pressed for reducing interfacial resistance between electrode active materials and SSE; therefore, the high mechanical strength of SSE results in the growth of Li metal through voids among SSE particles, leading to internal short circuit. In this study, a negative electrode current collector with microsized pores where the Li metal could be preferentially deposited was designed and prepared by coating Au or Ni on a commercially available membrane filter with 8 μm diameter pores. The Li metal deposition/dissolution behavior in the pores of the Au- or Ni-coated membrane filter under galvanostatic conditions was discussed based on scanning electron microscopy images. Consequently, the Li metal deposition occurred in the pores during charging and the deposited Li dissolved from the pores during discharging. Moreover, it was found that there were two modes in the Li deposition in the pores, and the deposition modes could be controlled by coating material and current density.

Valorization of Palm Biomass Waste for Sustainable Production of Lipase-Carbon Matrices And Biodiesel

The conversion of arable land to produce plant-based biofuels can produce more greenhouse gas (GHG) emissions than the displacing effect that is expected from the use of biofuels instead of fossil fuels. Utilizing agricultural waste offers an alternative pathway to reducing GHG emissions. Typical palm oil mills, for instance, produce palm kernel shells (PKS) and palm oil mill effluents (POME) as wastes in enormous amounts which accounts for > 60% of solid and liquid waste from the mill. Here, we explore the feasibility of a circular palm bioeconomy where waste PKS was directly converted to activated carbons (AC) in a technique (550 °C, under N 2 ) that departs from the conventional two-step (carbonization and activation) AC synthesis route. Using FT-IR, FE-SEM, and EDX as surface analysis tools, the synthesized carbons, PKAC, showed excellent morphological and surface functionalities similar to bituminous coal-derived activated carbons. The 1 – 10 μm pore diameters of PKAC were relevant in the immobilization of Aspergillus oryzae whole-cells expressing recombinant Fusarium heterosporum lipase. For biodiesel synthesis, the higher specific activity of the PKAC-immobilized whole-cell lipase (81.6 IU/mg BSP) ensured the conversion of POME to ≥97.5 wt. % fatty acid methyl ester (FAME). Whilst offering the benefits of cheap immobilization carriers and greener synthesis routes, the produced FAME showed properties (48.8 cetane number) that conform to ASTM and EN specifications. This study thus serves as a framework for the design of hydrocarbon synthesis platforms for a future palm bioeconomy.

A Study on the Influence of Ionization Method on Single Cell Initial Performance: Electrospray Method

Various catalysts showing high ORR activity have been developed over the past several years, and the results of evaluating actual fuel cells prepared using highly ORR-active catalysts have been reported. However, in contrast to rotating disk electrode (RDE) results showing high ORR activity, it is difficult to implement the high activity in actual fuel cell testinghen using the same catalysts. The most significant difference compared to the RDE is that there is an interface between the electrolyte and the surface of the catalyst in a membrane electrode assembly (MEA). In order to improve the coating properties of the electrolyte binder on the surface of the catalyst and the distribution of the electrolyte binder in the catalyst layer, various slurry[1] and catalyst layer preparation methods have been studied[2,3,4]. In this study, the catalyst layers were prepared using the electrospray (ES) method, and two different ionization methods (positive, negative) were used, based on surface charge analysis of the electrolyte binder (-35 mV) and electrolyte binder-coated catalysts (-43 mV). Structural differences in the catalyst layer were observed for the different ionization methods used. Mainly, it was observed that greater than 1 μm diameter pores were formed in the catalyst layer prepared by the positive ionization method. In contrast, with the negative ionization method, relatively uniform pores were formed in the catalyst layer. The initial performance of the MEAs prepared by the negative ionization method revealed improved initial performance over that of the positive ionization method: at 0.85 V, O2 supply, positive: 0.074, negative: 0.091 A/mgPt; at 0.65 V, air supply, positive: 1.26, negative: 2.10 A/mgPt; and O2 supply, positive: 3.86, negative 6.31 A/mgPt). The initial performance difference according to the ionization method can be understood through a structural difference in the catalyst layer analyzed by STEM and TEM, and through electrochemical analysis: i) different electrolyte binder morphology. ii) structural differences in the catalyst layer, and iii) proton transport resistance in the catalyst layer. Therefore, it was confirmed that, when the catalyst layer was prepared by the electrospray method using the same electrolyte binder content, the negative ionization method yielded around 1.5 times better initial performance, regardless of the single cell operating conditions. Acknowledgement This work was partially supported by funds for the “Superlative, Stable, and Scalable Performance Fuel Cell (SPer-FC) Project" from the New Energy and Industrial Technology Development Organization (NEDO) and the "Yamanashi Frontier for Innovation and Ecosystem Project" from Regional Innovation Ecosystems of the Ministry of Education, Culture, Sports, Science and Technology.

Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering.

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm-50 nm crystalline indium tin oxide or a 100 nm-150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure-function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.

Chondrogenic differentiation of adipose-derived mesenchymal stem cells induced by L-ascorbic acid and platelet rich plasma on silk fibroin scaffold.

Articular cartilage is an avascular tissue with limited regenerative property. Therefore, a defect or trauma in articular cartilage due to disease or accident can lead to progressive tissue deterioration. Cartilage tissue engineering, by replacing defective cartilage tissue, is a method for repairing such a problem. In this research, three main aspects—cell, biomaterial scaffold, and bioactive factors—that support tissue engineering study were optimized. Adipose-derived mesenchymal stem cells (ADSC) that become cartilage were grown in an optimized growth medium supplemented with either platelet rich plasma (PRP) or L-ascorbic acid (LAA). As the characterization result, the ADSC used in this experiment could be classified as Mesenchymal Stem Cell (MSC) based on multipotency analysis and cell surface marker analysis. The biomaterial scaffold was fabricated from the Bombyx morii cocoon using silk fibroin by salt leaching method and was engineered to form different sizes of pores to provide optimized support for cell adhesion and growth. Biocompatibility and cytotoxicity evaluation was done using MTT assay to optimize silk fibroin concentration and pore size. Characterized ADSC were grown on the optimized scaffold. LAA and PRP were chosen as bioactive factors to induce ADSC differentiation to become chondrocytes. The concentration optimization of LAA and PRP was analyzed by cell proliferation using MTT assay and chondrogenic differentiation by measuring glycosaminoglycan (GAG) using Alcian Blue at 605 nm wavelength. The optimum silk fibroin concentration, pore size, LAA concentration, and PRP concentration were used to grow and differentiate characterized ADSC for 7, 14, and 21 days. The cell morphology on the scaffold was analyzed using a scanning electron microscope (SEM). The result showed that the ADSC could adhere on plastic, express specific cell surface markers (CD73, CD90, and CD105), and could be differentiated into three types of mature cells. The silk fibroin scaffold made from 12% w/v concentration formed a 500 µm pore diameter (SEM analysis), and was shown by MTT assay to be biocompatible and to facilitate cell growth. The optimum concentrations of the bioactive factors LAA and PRP were 50 µg/mL and 10%, respectively. GAG analysis with Alcian Blue staining suggested that PRP induction medium and LAA induction medium on 12% w/v scaffold could effectively promote not only cell adhesion and cell proliferation but also chondrogenic differentiation of ADSC within 21 days of culture. Therefore, this study provides a new approach to articular tissue engineering with a combination of ADSC as cell source, LAA and PRP as bioactive factors, and silk fibroin as a biocompatible and biodegradable scaffold.

The effect of larger than cell diameter polylactic acid surface patterns on osteogenic differentiation of rat dental pulp stem cells.

Topography of the scaffold is one of the most important factors defining the quality of artificial bone. However, the production of precise micro- and nano-structured scaffolds, which is known to enhance osteogenic differentiation, is expensive and time-consuming. Meanwhile, little is known about macro-patterns (larger than cell diameter) effect on cell fate, while this kind of structures would significantly facilitate the manufacturing of artificial skeleton. Therefore, this research is focused on polylactic acid scaffold's macro-pattern impact on rat's dental pulp stem cells (DPSCs) morphology, proliferation, and osteogenic differentiation. For this study, two types of scaffolds were 3D printed: wavy and porous. Wavy scaffolds consisted of 188 μm wide joined threads, meaning that cells might have been curved on the filament as well as compressed in the groove. Porous scaffolds were designed to avoid groove formation and consisted of 500 μm threads, arranged in the woodpile manner, forming 300 μm diameter pores. We found that both macro-surfaces influenced DPSC morphology compared to control. As a consequence, enhanced DPSC proliferation and increased osteogenic differentiation potential was registered in cells grown on these scaffolds. Finally, our results showed that the construction of an artificial bone did not necessarily require the precise structuring of the scaffold, because both types of macro-topographic PLA scaffolds were sufficient enough to induce spontaneous DPSC osteogenic differentiation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 174-186, 2019.

Experimental characterisation of a novel adiabatic membrane-based micro-absorber using H2O-LiBr

In the interest of reducing the size of absorption chillers, a novel adiabatic membrane-based micro-absorber prototype is experimentally studied. Water–lithium bromide solution is used as the working fluid flowing through 50 rectangular microchannels of 0.15 mm height, 3 mm width and 58 mm length. In the present study, a laminated microporous PTFE membrane of 0.45 µm pore diameter, separating the solution from the vapour, is tested. It incorporates a supporting layer of polypropylene. Different operating parameters were tested, including the inlet solution mass flow rate, temperature and concentration and the pressure potential for absorption. The measured concentration and temperature of the solution at the absorber outlet are used to evaluate the mass transfer characteristics of the micro-absorber. It is demonstrated that the process is controlled by the solution mass transfer resistance. Calculated results of the absorption rate and the absorption ratio show the advantages of the proposed design considering its compactness. The cooling power of a hypothetical chiller equipped with the tested micro-absorber of 73.7 cm3 effective volume, for the range of variables considered in this study, is 41 W. The modular configuration of the absorber allows to easily scale-up the cooling capacity.