Days In Static Conditions Research Articles

New approach to niobia-modified borosilicate glasses for Cs waste immobilization

The use of nuclear materials is increasing in energy production, medicine, and environmental sectors. Following this trend, the generation of radioactive wastes is also increasing in the whole production cycle and use of this kind of materials. Among these, the 137Cs radionuclide presents a potential risk to human health due to its half-life time (30,2 years), high-level activity (1 TBq) and easiness to contaminate rivers, soil, and air. The immobilization of 137Cs in solid matrices has been an available option researched by several countries. In this context a new glass composition based on aluminoborosilicate glass modified with niobium (Nb) was used for the immobilization of cesium through adding Cs-loaded zeolite. Homogeneous vitreous wasteforms were improved with the growth of Nb content in the compositions. All compositions were able to keep up to 5.9 wt% Cs2O, previously adsorbed by zeolite A, and the immobilization efficiency was around 53%. Their structural analyses by Raman revealed a depolymerized and complex network structure, due to the presence of several cations including Cs. In turn, Nb reflected positively on the chemical resistance and thermal properties, by changing the distribution of silicate species. The wasteforms presented good glass forming ability and thermal stability up to 520 °C. Through the thermal treatment for devitrification, Cs atoms were stabilized into the Pollucite phase (CsAlSi2O6). Besides that, the wasteforms, preferably the one containing 8.0 mol% Nb, showed low elemental releases and leaching rates for Cs (1 × 10−3 g m2.day−1), after the leaching experiments at 90 °C for 7 days in static conditions, verified by the neutron activation analysis (NAA).

Mechanical stimulation is a key component in the development of pericellular matrix around human chondrocytes

Purpose: Articular cartilage within the joint experience multi-directional mechanical stimulation. These stimuli are transferred to the chondrocytes through the pericellular matrix, a small shell surrounding the cells. The signal is then translated by the cell, which subsequently responds by releasing catabolic or anabolic markers. Our aim was to be able to determine if, depending on the mechanical stimulus applied onto the chondrocytes, there would be a variation in extracellular matrix production. To address this, we used our cartilage-on-chip and studied the effects of mechanical stimulation on human articular chondrocytes. The cartilage-on-chip system includes a 3D cell-hydrogel compartment, a perfusion channel to provide nutrients and a mechanical actuation unit. The mechanical actuation unit, which is separated from the rest of the system by a thin elastic polydimethylsiloxane membrane, comprises 3 individually addressable chambers were positive or negative pressure can be applied (Fig. 1). We report here how different mechanical stimuli: 1) affect IL-6 cytokine production; and 2) the chondrocyte’s phenotype compared to static conditions; 3) influence the directionality in extracellular matrix deposition; 4) stimulate pericellular matrix formation, and; 5) differentially affect overall protein expression. Methods: The cartilage-on-chip was fabricated using soft-lithography with polydimethylsiloxane. Application of positive and/or negative pressure resulted in different sets of stimulations onto the 3D hydrogel (compression or compression & shear strain). Low melting temperature agarose (2% w/v) was used to embed human primary chondrocytes (hCHs), which were cultured in the platform for one day with proliferation medium followed by chondrocyte differentiation medium. First, the cell-laden constructs were stimulated for 7 days (1 h a day at 1 Hz) with either compression, or compression and shear strain (wave form) or without mechanical stimuli. Medium was collected from the device at day 1, 2, 3, 5 and 7 and IL-6 concentration quantified using enhanced SPRi. qPCR was performed at day 7 for Collagen type I and type II. Next, cell-laden hydrogels were cultured for 7 days in static condition and subsequently stimulated for 7 days with the two aforementioned mechanical actuation patterns, or in static conditions for a total of 14 days. Samples were fixed and stained for aggrecan, collagen type II and collagen type VI. Results: The expression of COL2A1 mRNA was higher in the mechanically stimulated samples in particular when using a combination of compression and shear strain. Interestingly, COL1A1 mRNA expression was inversely correlated with the COL2A1 mRNA with highest expression in the static conditions. Consequently, these results suggest the involvement of mechanical stimulation on the transition of human chondrocytes towards a more hyaline like cartilage phenotype. IL-6 secretion decreased over time with no detectable signal at day 7 for the static conditions indicating chondrocyte adaptation to the 3D environment. Moreover, IL-6 was higher in the constructs exposed to mechanical stimuli, indicating a role of mechanical stimulation in IL-6 production. Aggrecan, collagen type II and collagen type VI immunostaining revealed higher pericellular matrix production in dynamic conditions. The pericellular matrix formed was mainly present in the direction of the mechanical stimulation suggesting cell adaptation to the applied stimuli (Fig. 3). Furthermore, the combination of compression and shear strain additionally enhanced both aggrecan and collagen production. Conclusions: Our cartilage-on-a-chip platform allows exposure of hydrogel embedded chondrocytes to multi-modal mechanical stimuli. Mechanical actuation supported the creation of a pericellular matrix surrounding the cells. Here, chondrocytes responded differently both at the gene and protein levels depending on the stimuli applied. Interestingly, chondrocytes produced their matrix in the direction of the stimuli suggesting a cell adaptation or “self-protection” mechanism. We are currently investigating if, by applying different biochemical stimuli, it is possible to influence the composition of the pericellular matrix.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Endobacterial symbiont of Fusarium oxysporum f.sp. cubense and the pathogenicity of their symbiosis towards banana plantling

Fusarium oxysporum f.sp. cubense (Foc), a causal agent of panama disease was reported carrying bacterial endosymbionts. This research aimed to identify the endobacteria in 7 Foc strains and to study their symbiosis effect on the Foc pathogenicity towards Ambon Kuning and Tanduk banana cultivars. The pathogenicity of endobacteria-Foc symbiosis were tested in vitro on banana plantling. Crude filtrate and biomass suspension that were produced by culturing each Foc strains for 21 days in static condition either in PDB (Potato Dextrose Broth) (Foc − ) or in antibiotics supplemented PDB (Foc +) were used as effectors. The Foc pathogenicity was stated as disease severity percentage on leaves and on rhizome. The result showed that all Foc strains contained endobacteria. Enterobacter sp. was hosted by Foc IPBCC 19.1427 and Izhakiella australiensis was in the hyphae of Foc IPBCC 19.1430. Enterobacter sp. affected Foc IPBCC 19.1427 virulence towards banana cv. Tanduk through effectors in the filtrate, while that towards cv. Ambon Kuning was unclear. Izhakiella australiensis did not affect Foc IPBCC 19.1430 virulence towards the two banana cultivars. The pathogenicity of Foc should further be verified, as the antibiotics given could not completely kill the endobacteria.

Hierarchical ZSM-5 beads composed of zeolite nanosheets obtained by pseudomorphic transformation

Abstract The concept of pseudomorphic transformation was used to transform amorphous mesoporous silica beads with different size (20, 50 and 75 μm) into hierarchical MFI-type zeolite beads composed of ZSM-5 nanosheets. The beads were synthesized under hydrothermal conditions with and without mechanical stirring at different temperatures and treatment times. The influence of the different synthesis parameters was investigated by X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, X-Ray Fluorescence, Nitrogen adsorption-desorption measurements, 27 Al solid-state Nuclear Magnetic Resonance, Energy-Dispersive X-Ray analysis and Thermogravimetric analysis. Well-crystallized 20 μm ZSM-5 nanosheets beads similar in size and shape to the original mesoporous amorphous silica beads were obtained after a hydrothermal treatment at 150 °C for 5 days in a tumbling oven and 2 days in static conditions at 120 °C. The influence of the bead size on the pseudomorphic transformation was studied in order to prepare well-crystallized ZSM-5 nanosheets beads of 50 and 75 μm. Results showed that the required time of static treatment at 120 °C increases when the size of the parent silica spheres increases. This is explained by the fact that crystallization starts from the outer bead surface toward the center.

First evidence of protein modulation by polystyrene microplastics in a freshwater biological model

Microplastics (MPs) are now one of the major environmental problems due to the large amount released in aquatic and terrestrial ecosystems, as well as their diffuse sources and potential impacts on organisms and human health. Still the molecular and cellular targets of microplastics’ toxicity have not yet been identified and their mechanism of actions in aquatic organisms are largely unknown. In order to partially fill this gap, we used a mass spectrometry based functional proteomics to evaluate the modulation of protein profiling in zebra mussel (Dreissena polymorpha), one of the most useful freshwater biological model. Mussels were exposed for 6 days in static conditions to two different microplastic mixtures, composed by two types of virgin polystyrene microbeads (size = 1 and 10 μm) each one. The mixture at the lowest concentration contained 5 × 105 MP/L of 1 μm and 5 × 105 MP/L of 10 μm, while the higher one was arranged with 2 × 106 MP/L of 1 μm and 2 × 106 MP/L of 10 μm.Proteomics’ analyses of gills showed the complete lack of proteins’ modulation after the exposure to the low-concentrated mixture, while even 78 proteins were differentially modulated after the exposure to the high-concentrated one, suggesting the presence of an effect-threshold. The modulated proteins belong to 5 different classes mainly involved in the structure and function of ribosomes, energy metabolism, cellular trafficking, RNA-binding and cytoskeleton, all related to the response against the oxidative stress.

Waktu Kultivasi Optimal dan Aktivitas Antibakteri dari Ekstrak Etil Asetat Jamur Simbion Aspergillus unguis (WR8) dengan Haliclona fascigera

Penelitian tentang penentuan waktu optimal pertumbuhan jamur simbion Aspergillus unguis (WR8) dan pengujian aktivitas antibakteri telah dilakukan. Kultivasi jamur dilakukan dengan menggunakan media Sabaoraud Dextrose Broth (SDB) dalam keadaan statis dan di-shaker (120 rpm) pada suhu 25-28oC. Pertumbuhan jamur secara optimal ditentukan berdasarkan jumlah biomassa kering miselia jamur per satuan waktu. Media cair diekstraksi dengan pelarut etil asetat, ekstrak etil asetat selanjutnya digunakan untuk pengujian aktivitas antibakteri menggunakan metode difusi agar terhadap bakteri Staphylococcus aureus. Hasil penelitian menunjukkan bahwa waktu optimal pertumbuhan jamur simbion tersebut dalam keadaan statis adalah pada hari ke-21 dan diameter hambat ekstrak (5 %b/v) adalah 21 mm. Sedangkan waktu optimal pertumbuhan jamur yang di shaker adalah pada hari ke-14 dan diameter hambat ekstrak sebesar 11 mm. Dapat disimpulkan waktu kultivasi optimal untuk menghasilkan senyawa antibakteri dari jamur A. unguis (WR8) adalah selama 21 hari secara statis menggunakan media cair.

Effect of Incubation Temperature on Growth of <i>Acetobacter xylinum</i> 0416 and Bacterial Cellulose Production

The objective of this research was to investigate the effect of incubation temperature towards the growth of Acetobacter xylinum 0416 and the production of bacterial cellulose. Fermentation of A.xylinum 0416 were carried out for 5 days in static condition using Hestrin & Schramm (HS) medium with initial glucose concentration of 4.0% (w/v) and initial pH of 6.4. The incubation temperature were varied at 5°C, 20°C, 25°C, 27°C, 28°C, 30°C, 35°C and 40°C respectively. Results indicated that 28°C served as the best incubation temperature for the growth of A.xylinum 0416 and produced the highest amount of bacterial cellulose with total dried weight of 0.3722 g/l. Meanwhile at incubation temperature of 5°C and 40°C, no significant growth of A.xylinum 0416 and bacterial cellulose were obtained. As a conclusion, incubation temperature plays an important role for the growth of A.xylinum 0416. The best incubation temperature is at 28°C in which the sufficient energy will be provided for bacterial growth thus enhancing the cellulose biosynthetic pathway in order to convert glucose into bacterial cellulose.

Bio-statistical approach for optimization of cold-active α-amylase production by novel psychrotolerant M. foliorum GA2 in solid state fermentation

Abstract Cold-active enzymes along with their producing microbes are of commercial value and find multiple applications in various industrial and biotechnological sectors. In this study, production optimization of cold active α-amylase from cold-adapted Microbacterium foliorum GA2 was carried out. The aim of the present work was to use economical agro-substrate for increasing cold-active α-amylase production and to optimize the fermentation parameters in SSF (Solid state fermentation) using two statistical experimental designs. Plackett–Burman design and response surface methodology was used to determine key ingredients for the best media composition and optimal concentration of these components, respectively. The screening result of Plackett–Burman design showed bagasse, lactose and pH had significant effects ( p -value≤0.05) on cold-active α-amylase production. Maximum α-amylase production (6610 units) was observed through response surface methodology in medium having 40% bagasse, 0.003 M lactose, and pH 8.0 at 20 °C when incubated for 5 days in static conditions. The closeness of optimized values ( R 2 =92.26%) to experimental values ( R 2 =96.28%) proved the validity of the statistical model. Under these experimental designs, the α-amylase yield increased three-fold in comparison to control and was much efficient and economical than “one-variable-at-a-time” methodology. Thus, cold-adapted M. foliorum GA2 could be exploited for industrial production of α-amylase using bagasse at relatively low temperatures.

In vitro bioactivity of Polyurethane/85S Bioglass composite scaffolds

Abstract In the present work Polyurethane (PU)/Bioglass (BG) composite materials were synthesized with different content of BG (10 and 20 mol.%) as filler. The 85S Bioglass was synthesized via polystep sol-gel method. The chemical composition of BG is 85SiO2-10CaO-5P2O5 (wt.%). The synthesis of PU was carried out by a two-step polyaddition reaction. The 85S BG was added in situ during the polymerization reaction. In vitro bioactivity of the prepared composites was examined in the presence of 1.5 SBF for 7 days in static conditions. The structure of synthesized PU/BG composites before and after in vitro test was determined by XRD, FTIR and SEM. XRD of the samples before in vitro test proved that the phase of γCa2P2O7 in the PU/20BG is visible. FTIR revealed the presence of urethane bond between OH-(from BG) and NCO groups (from PU). Based on FTIR results after in vitro test in 1.5 SBF solutions, A/B-carbonate containing hydroxyapatite (CO3HA) was formed. XRD proved that HA was formed on the surface of the samples, but Ca2P2O7 does not undergo any changes in the 1.5 SBF solution. SEM depicted the nano-HA agglomerated in spherical particles after immersion in 1.5 SBF for 7 days.

Effect of different algae used for enrichment of rotifers on growth, survival, and swim bladder inflation of larval amberjack Seriola dumerili

The effect of algae with different DHA contents used for the enrichment of rotifers on the growth performance, survival, and swim bladder inflation of larval amberjack Seriola dumerili was investigated. Rotifers were enriched with freshwater Chlorella vulgaris containing three levels of DHA (rotifer containing DHA 0.04, 0.60, 1.32 g DHA 100 g−1 DM) and Nannochloropsis (0.04 g DHA 100 g−1 DM; 2.54 g EPA 100 g−1DM). The larvae were fed the enriched rotifers in triplicate from 3 days post-hatch for 7 days in static condition. The same algae used for rotifer enrichment were supplied to the larval tanks. Growth and survival rate of fish fed the rotifers enriched with Nannochloropsis were higher than those of fish fed the rotifers enriched with all three Chlorella treatments. Swim bladder inflation was lowest in fish fed the rotifers enriched with Nannochloropsis. The proportion of EPA was higher in fish fed the rotifers enriched with Nannochloropsis, while that of DHA increased proportionally with the DHA levels in the rotifers enriched with Chlorella. These results suggest that rotifers enriched with Nannochloropsis (EPA-rich rotifers) are effective to enhance growth and survival, but DHA instead of EPA is essential to improve the swim bladder inflation in amberjack larvae.

Isolation and characterization of a Scenedesmus acutus strain to be used for bioremediation of urban wastewater

Green microalgae, due to their short growth cycle and to their ability to photosynthetically fix carbon dioxide producing an oil-rich biomass, have been proposed as an attractive alternative feedstock for the production of “second generation” biofuels. However, it has been anticipated that owing to their ability to colonize very different environments characterized by high levels of nitrogen, they can also be good candidates for bioremediation, thus integrating environmental protection with sustainable biomass production. We have isolated a strain belonging to Scenedesmus genus from urban wastewater. This isolate, Scenedesmus acutus PVUW12, was tested for its ability to grow and actively deplete eutrophicating inorganic molecules present in wastewater. In order to test its biomass productivity, the PVUW12 strain was grown in a vertical-column photobioreactor using standard growth medium obtaining a maximal productivity of 0.3 g dry weight L−1 d. When the same strain was grown in the photobioreactor filled with wastewater collected from the final step of the local urban purifier plant containing 18.8 mg L−1 nitrate, we observed complete nitrogen removal coupled with a biomass production of about 0.74 g dry weight L−1 within 3 days. After 10 days, the recovered biomass was analyzed for triglyceride content which was found to be 9.3% of the dry biomass. However, when algal cells were left for additional 10 days in static conditions the triglyceride content increased to 28.8%. These data show that this Scenedesmus strain can be used for wastewater bioremediation producing a biomass suitable for energy production.

In vitro bioactivity of 70 wt.% SiO2 — 30 wt.% CaO sol-gel glass, doped with 1, 3 and 5 wt.% NbF5

Abstract The 70SiO2-30CaO (wt.%) sol-gel glasses doped with 1, 3 and 5 NbF5 (wt.%) were prepared via polystep sol-gel route. The synthesized glasses were characterized by XRD, FTIR and SEM. Changes in 1.5 SBF solutions were measured by ICP-AES. XRD of the glasses stabilized at 700°C for 6 hours proved the presence of niocalite. FTIR was consistent with XRD data. The in vitro bioactivity study of all glasses prepared were carried out by soaking in 1.5 simulated body fluid (1.5 SBF) at 37°C for 6 and 12 days in static conditions. The FTIR reveals the formation of A-type and B-type carbonate containing hydroxyapatite (CO3HA) layer. Changes in 1.5 SBF solutions, after 6 days of soaking, show that the Ca concentration increased significantly, compared to the initial Ca content in the 1.5 SBF solution before in vitro test. After 12 days of immersion, the Ca concentration decreased, i.e., the formation of HA phase consumed Ca from 1.5 SBF solution. For all soaking times, the concentration of P is much lower than that the used 1.5 SBF. Based on these results we suggest that Ca and P play an active role in the future of the glasses. SEM depicts that the different morphology of hydroxyapatite can be formed as a function of soaking time.

Bayesian modelling of daphnid responses to time-varying cadmium exposure in laboratory aquatic microcosms

Experiments were carried out to test the effects of cadmium on five aquatic species in 2-L indoor freshwater/sediment microcosms. Experimental data were collected over 21 days in static conditions, i.e. the microcosms evolved without water renewal. Because of speciation, the total cadmium concentration in water decreased with time. Here we present a focus on Daphnia magna responses. For the three life history traits we considered (survival, growth and reproduction), mathematical effect models were built based on threshold stress functions involving no effect concentrations (NECs). These models took the time-varying conditions of exposure into account through a time-recurrent formalism. Within a Bayesian framework, four kinds of data were fitted simultaneously (exposure, survival, growth and reproduction), using an appropriate error model for each endpoint. Hence, NECs were determined as well as their associated estimation uncertainty. Through this modelling approach, we demonstrate that thresholds for stress functions can be successfully inferred even in experimental setup more complex than standard bioassays.

Effect of copper exposure on growth, condition indices and biomarker response in juvenile sole <i>Solea senegalensis</i>

Juvenile Solea senegalensis were exposed to different concentrations of waterborne copper (Cu) for 15 days in static conditions with continuous aerated artificial salt water at 20°C (± 0.8°C) with a normal photoperiod (10 h/14 h light/dark) and daily feeding. Several measures of exposure and effects were determined: 1) biomarkers - metallothioneins and lipid peroxidation level; 2) mass indices - growth rate and morphometric condition indices; and 3) biochemical condition indices - RNA:DNA ratio and lipid and protein content in fish tissues. Copper exposure triggered the response of the biomarkers and resulted in reduced growth and condition (RNA:DNA and lipid content), but the morphometric indices did not vary. The physiological costs of Cu contamination on condition suggested that lipid reserves were allocated as an energy source to enable exposed fish to respond to Cu toxicity as well as to maintain positive growth rates and protein synthesis throughout the experiment, although with lower growth rates than the control fish. This study showed the importance of selecting suitable biomarkers according to contaminant source, fish species and their life-history stage. In addition, the use of several biomarkers of exposure, growth and specific condition indices can improve fish health determination and should be considered in evaluations of the effects of environmental contaminants on fish.

Culture of C3A Cells in Alginate Beads for Fluidized Bed Bioartificial Liver

Extracorporeal bioartificial liver has been designed to sustain the detoxification and synthetic function of the failed liver in patients suffering from acute liver failure until the time of liver allotransplantation or regeneration of their own. A fluidized bed, bioartificial liver improves the mass transfer velocity between the medium and the hepatocytes. Detoxification functions of the liver could be replaced by completely artificial systems, but the synthetic functions of hepatocytes may be obtained only by metabolically active cells. The aim of our study was to investigate the influence of C3A cell culture in alginate beads on synthetic function in a fluidized bed, bioartificial liver. Cells in alginate beads were prepared using an electrostatic droplet generator of our own design using low-viscosity alginate. Beads were cultured for 24 hours then 7 days in static conditions and then 24 hours of fluidization in the bioreactor to assess albumin production. We observed significantly increased albumin production by C3A cells entrapped in alginate beads during static culture. Fluidization increased albumin production compared with static culture. Fluidization performed after 7 days of static culture resulted in a significant increase in albumin synthesis. In conclusion, static culture of alginate beads hosting hepatic cells facilitates restoration of cell function.

Mechanical stress promotes the expression of smooth muscle-like properties in marrow stromal cells

It is poorly understood what kind of factors are involved in lineage commitment and maturation of mesenchymal stem cells. The present study investigates whether mechanical stress promotes expression of smooth muscle cell (SMC)-specific cytoskeletal protein in marrow stromal cells. Fibroblast-like stromal cells expressing STRO-1 antigen were isolated from rat bone marrow by density gradient separation. After preincubation for 7, 14, or 21 days in static condition, cells were exposed to one of three types of fluid flow-induced mechanical forces (flow dominant, pressure dominant, or combined) for 36 hours. The expression of SMC-specific cytoskeletal protein [alpha smooth muscle actin (alphaSMA) and smooth muscle myosin heavy chain (SMMHC)] was evaluated by immunofluorescence staining and Western blotting. The proportion of SMMHC-positive cells was increased with longer preincubation periods (p < 0.01 vs 7-day incubation) and by any types of mechanical stimulation (p < 0.01 vs static control condition). The SMMHC-positive fraction after exposure to pressure-dominant forces (0.9% +/- 0.2%, 2.9% +/- 0.9%, and 12.6% +/- 0.8% for 7, 14, and 21 days of preincubation) or to combined forces (1.2% +/- 0.2%, 3.1% +/- 1.6%, and 15.5% +/- 2.8%) was higher than after flow-dominant stimulation (0, 1.2% +/- 0.1%, and 7.2% +/- 2.0%) (p < 0.01). In Western blotting, pressure-dominant or combined stimulation upregulated alphaSMA and SMMHC expression compared to static control condition. The long-term cell incubation and subsequent mechanical stimulation, especially compressive strain, promote expression of SMC-specific cytoskeletal protein in marrow stromal cells.

A DURABLE, NON-POWER-CONSUMPTIVE, AND SIMPLE SEAL FOR ROTARY BLOOD PUMPS

One the key technologies required for rotary blood pumps is the sealing of the motor shaft. A mechanical seal, a journal bearing, magnetic coupling and magnetic suspension have been developed, but they have drawbacks such as wear, thrombus formation, and power consumption. A ferrfluidic seal was developed for an axial flow pump. A ferrofluidic seals is durable, simple and non-power-consumptive. Long-term experiments and finite element modeling (FEM) analyses confirmed these advantages. The seal body was composed of a Ned-Fe magnet (Hc:-114kA/m, 8 mm in diameter and 1 mm in thickness) and two pole pieces (8 mm in diameter and 0.5 mm in thickness). This seal was formed by injecting ferrofluid into the gap (50 μm) between the pole pieces and the motor shaft (3 mm in diameter). To contain the ferrofluid in the seal and to minimize the possibility of ferrofluid making contact with blood, a shield with a small cavity was provided on the pole piece. Vibration of the motor shaft was maintained within 5 μm. The sealing pressure of the seal was measured while in blood. The sealing pressure was 188 mmHg with the ferrofluid LS-40 (Saturated magnetization: 24.3 kA/m) at a motor speed of 10,000 rpm and 225 mmHg in a static condition. The ferrofluidic seals have been perfect against pressure of 100 mmHg for 440+ days in static condition, and 51,39+ and 34+ days at a motor speed of 8,000 rpm. The FEM analyses indicated a theoretical sealing pressure of 260 mmHg. Leakage of the ferrofluid into water was measured with spectrophotometer. Leakage was not detected (less than the resolution). The specially designed ferrofluidic seal for sealing out liquids is useful for axial flow blood pumps. The ferrofluidic seal is incorporated into an intra-cardiac axial flow pump.