A novel hyperbaric swimming respirometer allows the simulation of varying swimming depths in fish respirometry studies.

The understanding of swimming physiology and knowledge on the metabolic costs of swimming are important for assessing effects of environmental factors on migratory behavior. Swim tunnels are the most common experimental setups for measuring swimming performance and oxygen uptake rates in fishes; however, few can realistically simulate depth and the changes in hydrostatic pressure that many fishes experience, e.g. during diel vertical migrations. Here, we present a new hyperbaric swimming respirometer (HSR) that can simulate depths of up to 80 m. The system consists of three separate, identical swimming tunnels, each with a volume of 205 L, a control board and a storage tank with water treatment. The swimming chamber of each tunnel has a length of 1.40 m and a diameter of 20 cm. The HSR uses the principle of intermittent-flow respirometry and has here been tested with female European eels (Anguilla anguilla). Various pressure, temperature and flow velocity profiles can be programmed, and the effect on metabolic activity and oxygen consumption can be assessed. Thus, the HSR provides opportunities to study the physiology of fish during swimming in a simulated depth range that corresponds to many inland, coastal and shelf waters.

Produção de biscoitos recheados com formação de organogel na base gordurosa / Production of sandwich cookies with the formation of organogel in the fatty base

A fim de atender à demanda do público que atualmente busca por alimentos mais saudáveis, as indústrias têm procurado alternativas que possibilitem a aplicação de ingredientes que agreguem valor nutricional aos produtos. A redução de gorduras saturadas e trans em produtos alimentícios, bem como a inserção de cereais ou farinhas nutricionais, vem sendo aplicadas em produtos de panificação. Biscoitos recheados possuem como bases geralmente biscoitos à base de farinha de trigo. O objetivo foi desenvolver formulação de biscoitos recheados com substituição de gordura vegetal por organogel no recheio e de farinha de trigo por farinha de sorgo no biscoito, a fim de agregar valor nutricional ao produto. Foram desenvolvidos biscoitos recheados: 1) recheio controle e com substituição da gordura vegetal dos recheios por organogel elaborado com sistema emulsionado (colágeno + óleo vegetal + água), a fim de diminuir concentrações de gorduras saturadas e trans. 2) para a base elaborouse biscoitos controle (farinha de trigo) e com substituição parcial e total de farinha de trigo por farinha de sorgo em 50% (50FS) e 100% (100FS). Foram conduzidas nos recheios e das bases dos biscoitos análises físicas e físico-químicas (textura, atividade de água, cor, composição centesimal e reologia) para avaliação e para análise de estabilidade de 6 semanas. Os resultados apresentaram que o biscoito 50FS obteve melhor valor de textura (Controle: 16,09 ± 1,28 N; 50FS: 19,63 ± 5,68 N e 100FS: 10,09 ± 0,65 N) e menor teor de atividade de água (Semana 01: 0,327±0,01 e Semana 06: 0,389 ± 0,00) do que o biscoito controle, durante análise de estabilidade. O biscoito 100FS apresentou coloração mais avermelhada. Os biscoitos 50FS e 100FS apresentaram maior teor proteico do que o controle (Controle: 5,37 ± 0,23 %; 50FS: 5,64 ± 0,49 % e 100FS: 5,75 ± 0,49 %). O recheio com organogel apresentou maior dureza (N) durante análise de estabilidade do que o recheio controle (Semana 6 Organogel: 6,81±1,48; Controle: 4,29±0,38). Os parâmetros de adesividade, coesividade e gomosidade do recheio com organogel não apresentaram diferenças significativas (p > 0,05). Os valores de atividade de água da formulação com organogel foram mais altos do que o recheio controle (Semana 6 Organogel: 0,730±0,00; Controle: 0,555±0,01). O valor de L* foi maior para o recheio controle, apresentando coloração mais amarelada do que a formulação com organogel. O recheio com organogel apresentou redução de 65 % do teor lipídico e aumento do teor proteico. Os recheios controle, com organogel e de mercado apresentaram comportamento tixotrópico durante a avaliação reológica, sendo que o produto de mercado teve comportamento próximo à formulação controle, com recuperação quase total da estrutura. Foram desenvolvidos cinco produtos, sendo três inovadores com valor nutricional agregado, atendendo às legislações vigentes, vida útil mínima de 6 semanas e ao apelo do mercado atual, podendo ser comercializados como biscoito recheado

In order to satisfy the demand of the public that is currently looking for healthier foods industries have been looking for alternatives that allow the application of ingredients that add nutritional value to the products. The reduction of saturated and trans fats in food products, as well as the insertion of cereals or nutritional flours, has been applied in bakery products. Filled cookies are usually based on wheat flour. The objective was to develop a formulation of filled cookies with replacement of vegetable fat for organogel in the filling and wheat flour for sorghum flour in the biscuit, in order to add nutritional value to the product. In this study, cookies filled with vegetable fat and wheat flour were used as a control where: 1) filling was replaced by organogel elaborated with an emulsified system (collagen + vegetable oil + water); and 2) base was prepared with partial and total replacer of wheat flour for sorghum flour in 50% (50FS) and 100% (100FS). Physical and physicochemical analyzes (texture, water activity, color, proximate composition and rheology) were carried out on the fillings and bases of the biscuits for evaluation and for the stability analysis of 6 weeks. The results showed that the 50FS cookies had a better texture value (Control: 16,09±1,28 N; 50FS: 19,63±5,68N and 10,09±0,65 N) and lower content of water activity (Week 1: 0,327±0,01 and Week 6: 0,389±0,00) than the control cookie during stability analysis. The 100FS had a more reddish color. The 50FS and 100FS cookies had a higher protein content than the control (Control: 5,37±0,23 %; 50FS 5,64±0,49 %). The fillings with organogel showed a higher hardness (N) than the control during stability analysis (Week 6 Organogel: 6,81±1,48; Control: 4,29±0,38). The parameters of adhesiveness, cohesiveness and guminess of the filling with organogel showed no significant differences (p> 0.05). The water activity values of the organogel formulation were higher than the control filling (Week 6 Organogel: 0,730±0,00; Control: 0,555±0,01). The value of L * was higher for the control filling, showing a more yellowish color than the formulation with organogel. The filling with organogel showed a 65% reduction in lipid content and an increase in protein content. The control, organogel and market fillings showed a thixotropic behavior in the rheological evaluation, and the market product had a behavior close to the control formulation, with almost total recovery of the structure. Five products were developed, three of which were innovative with added nutritional value, in compliance with current legislation, a minimum shelf life of 6 weeks, which can be sold as a stuffed cookies.

Pressure induced lung injury in a novel in vitro model of the alveolar interface: protective effect of dexamethasone.

PURPOSE: The lungs of infants born with congenital diaphragmatic hernia suffer from immaturity as well as the short and long term consequences of ventilator-induced lung injury, including chronic lung disease. Antenatal and postnatal steroids are among current strategies promoted to treat premature lungs and limit long term morbidity. Although studied in whole-animal models, insight into ventilator-induced injury at the alveolar-capillary interface as well as the benefits of steroids, remains limited. The present study utilizes a multi-fluidic in vitro model of the alveolar-interface to analyze membrane disruption from compressive aerodynamic forces in dexamethasone-treated cultures. METHODS: Human alveolar epithelial cell lines, H441 and A549, were cultured in a custom-built chamber under constant aerodynamic shear followed by introduction of pressure stimuli with and without dexamethasone (0.1µM). On-chip bioelectrical measurements were noted to track changes to the cellular surface and live-dead assay to ascertain cellular viability. RESULTS: Pressure-exposed alveolar cultures demonstrated a significant drop in TEER that was less prominent with an underlying extracellular-matrix coating. Addition of dexamethasone resulted in increased alveolar layer integrity demonstrated by higher TEER values. Furthermore, dexamethasone-treated cells exhibited faster recovery, and the effects of pressure appeared to be mitigated in both cell types. CONCLUSION: Using a novel in vitro model of the alveolus, we demonstrate a dose-response relationship between pressure application and loss of alveolar layer integrity. This effect appears to be alleviated by dexamethasone and matrix sub-coating.

Role of contrast and fractality of laser speckle image in assessing flow velocity and scatterer concentration in phantom body fluids.

Blood flow velocity and red blood cell concentration are of vital importance in assessing tissue microcirculation. Laser speckle contrast analysis is being considered as a promising tool in the qualitative assessment of flow velocity as well as scatterer concentration in different body fluids, though the quantification part still remains challenging. The fractal-based spatial correlation analysis of speckle flow images along with the corresponding contrast analysis for the quantitative assessment of flow and scatterer concentration is investigated. In this study, phantom body fluid solution (intralipid 20%) of different concentrations is pumped at different flow rates through the designed flow channel using a syringe pump and the corresponding speckle images are acquired. The fractality of the acquired speckle images in response to the changes in concentration of the fluid as well as the variations in fluid flow is analyzed along with the corresponding contrast-based analysis. Following this qualitative analysis, an experimental model is attempted toward quantification of these parameters from a single acquired speckle image by considering the contrast and fractality changes together.

Comparison of pyrolytic products produced from inorganic-rich and demineralized rice straw (Oryza sativa L.) by fluidized bed pyrolyzer for future biorefinery approach.

The objectives of this study were to investigate the effects of inorganic constituents on the fast pyrolysis of the biomass and to determine the yields as well as physicochemical properties of pyrolytic products. The pyrolytic products were obtained from raw and demineralized rice straw using a fluidized bed type pyrolyzer at different temperatures. As pyrolysis temperature increased, total biooil yield gradually decreased from 46.6 to 29.6 wt.% for the raw-straw, and from 55.4 to 35.3 wt.% for the demineralized rice straw. For demineralized rice straw, higher pyrolysis temperatures promoted gasification reactions but reduced char formations. However, char yield for the raw-straw was relatively unaffected by temperature due to an increase in carbonization reactions that were catalyzed by some inorganics. Certain inorganic constituents in the biomass were distinctively distributed in the biooil, and ICP-ES and GC/MS analysis indicated that some inorganics may be chemically bound to cell wall components.

Performance of down-flow hanging sponge (DHS) reactor coupled with up-flow anaerobic sludge blanket (UASB) reactor for treatment of onion dehydration wastewater.

In this study, a promising system consisting of up-flow anaerobic sludge blanket (UASB) reactor followed by down-flow hanging sponge (DHS) reactor was investigated for onion dehydration wastewater treatment. Laboratory experiments were conducted at two different phases, i.e., phase (1) at overall hydraulic retention time (HRT) of 11h (UASB reactor: 6h and DHS reactor: 5h) and phase (2) at overall HRT of 9.4h (UASB reactor: 5.2h and DHS reactor: 4.2h). Long-term operation results of the proposed system showed that its overall TCOD, TBOD, TSS, TKN and NH(4)-N removal efficiencies were 92 ± 5, 95 ± 2, 95 ± 2, 72 ± 6 and 99 ± 1.3%, respectively (phase 1). Corresponding values for the 2nd phase were 85.4 ± 5, 86 ± 3, 87 ± 6, 65 ± 8 and 95 ± 2.8%. Based on the available results, the proposed system could be more viable option for treatment of wastewater generated from onion dehydration industry in regions with tropical or sub-tropical climates and with stringent discharge standards.

Acoustical scattering by multilayer spherical elastic scatterer containing electrorheological layer.

A computational procedure for analyzing acoustical scattering by multilayer concentric spherical scatterers having an arbitrary mixture of acoustic and elastic materials is proposed. The procedure is then used to analyze the scattering by a spherical scatterer consisting of a solid shell and a solid core encasing an electrorheological (ER) fluid layer, and the tunability in the scattering characteristics afforded by the ER layer is explored numerically. Tunable scatterers with two different ER fluids are analyzed. One, corn starch in peanut oil, shows that a significant increase in scattering cross-section is possible in moderate frequencies. Another, fine poly-methyl methacrylate (PMMA) beads in dodecane, shows only slight change in scattering cross-sections overall. But, when the shell is thin, a noticeable local resonance peak can appear near ka=1, and this resonance can be turned on or off by the external electric field.

Continuous-flow biodiesel production using slit-channel reactors.

Slit-channel reactors are reactors whose active surface areas are orders of magnitude higher than those of micro-reactors but have low fabrication costs relative to micro-reactors. We successfully produced biodiesel with different degrees of conversion using homogeneous catalyst in the slit-channel reactor. The reactor performance shows that percent conversion of soybean oil to biodiesel increases with channel depth, as expected, due to more efficient mixing. Shallow slit-channels require short average residence times for complete product conversion. Present results show that the slit-channel reactor provides an improved performance over traditional batch reactors using homogeneous sodium alkoxide catalyst. It is aimed to couple the reactors with solid catalysts in converting soybean oil to biodiesel and implementation method is suggested. The cost advantages resulting from the ease of fabrication of slit-channel reactors over micro-reactors and how these factors relate to the oil conversion efficiency to biodiesel are briefly noted and discussed.

Design of a water coupling bolus with improved flow distribution for multi-element superficial hyperthermia applicators.

A water bolus used in superficial hyperthermia couples the electromagnetic (EM) or acoustic energy into the target tissue and cools the tissue surface to minimise thermal hotspots and patient discomfort during treatment. Parametric analyses of the fluid pressure inside the bolus computed using 3D fluid dynamics simulations are used in this study to determine a bolus design with improved flow and surface temperature distributions for large area superficial heat applicators. The simulation results are used in the design and fabrication of a 19 x 32 cm prototype bolus with dual input-dual output (DIDO) flow channels. Sequential thermal images of the bolus surface temperature recorded for a step change in the circulating water temperature are used to assess steady state flow and surface temperature distributions across the bolus. Modelling and measurement data indicate substantial improvement in bolus flow and surface temperature distributions when changing from the previous single input-single output (SISO) to DIDO configuration. Temperature variation across the bolus at steady state was measured to be less than 0.8 degrees C for the DIDO bolus compared to 1.5 degrees C for the SISO water bolus. The new DIDO bolus configuration maintains a nearly uniform flow distribution and low variation in surface temperature over a large area typically treated in superficial hyperthermia.

Identification of viscoelastic parameters of skin with a scar in vivo, influence of soft tissue technique on changes of skin parameters.

The goal of the experiment was to develop an identification method capable of objective detection of changes of viscoelastic properties of skin with a scar remaining after a modified radical mastectomy. We compared the intact skin and the skin with a scar, a scar before and after physiotherapy. We used two methods. The first one is based on measurements of the local dynamic deformation response of the skin and the second one is the matrix identification of static deformation that identifies properties of the whole tested region of the explored tissues. We identified the skin stretchability, shiftability against deeper layers and deeply analysed both the methods. In some patients, we found statistically proven difference. In all these cases the measurement methods have detected changes of the observed tissue condition. We found both methods to be potentially applicable after further improvements as a diagnostic tool, which can contribute to the improvement of postoperative care of patients.

A viscosity-enhanced mechanism for biogenic ocean mixing.

Recent observations of biologically generated turbulence in the ocean have led to conflicting conclusions regarding the significance of the contribution of animal swimming to ocean mixing. Measurements indicate elevated turbulent dissipation--comparable with levels caused by winds and tides--in the vicinity of large populations of planktonic animals swimming together. However, it has also been noted that elevated turbulent dissipation is by itself insufficient proof of substantial biogenic mixing, because much of the turbulent kinetic energy of small animals is injected below the Ozmidov buoyancy length scale, where it is primarily dissipated as heat by the fluid viscosity before it can affect ocean mixing. Ongoing debate regarding biogenic mixing has focused on comparisons between animal wake turbulence and ocean turbulence. Here, we show that a second, previously neglected mechanism of fluid mixing--first described over 50 years ago by Charles Darwin--is the dominant mechanism of mixing by swimming animals. The efficiency of mixing by Darwin's mechanism is dependent on animal shape rather than fluid length scale and, unlike turbulent wake mixing, is enhanced by fluid viscosity. Therefore, it provides a means of biogenic mixing that can be equally effective in small zooplankton and large mammals. A theoretical model for the relative contributions of Darwinian mixing and turbulent wake mixing is created and validated by in situ field measurements of swimming jellyfish using a newly developed scuba-based laser velocimetry device. Extrapolation of these results to other animals is straightforward given knowledge of the animal shape and orientation during vertical migration. On the basis of calculations of a broad range of aquatic animal species, we conclude that biogenic mixing via Darwin's mechanism can be a significant contributor to ocean mixing and nutrient transport.

Flow patterns and heat convection in a rectangular water bolus for use in superficial hyperthermia.

This paper investigates both numerically and experimentally the spatio-temporal effects of water flow in a custom-made water bolus used for superficial hyperthermia generated by a 915-MHz, 4 x 3 microwave applicator array. Similar hyperthermia models referenced in the literature use a constant water temperature and uniform heat flux to describe conduction and convection energy exchange within the heating apparatus available to cool the tissue surface. The results presented in this paper show that the spatially varying flow pattern and rate are vital factors for the overall heat control applicability of the 5 mm thick bolus under study. Regions with low flow rates and low heat convection clearly put restrictions on the maximum microwave energy possible within the limits of skin temperature rise under the bolus. Our analysis is illustrated by experimental flow front studies using a contrast liquid set-up monitored by high definition video and complemented by numerical analysis of liquid flow and heat exchange within the rectangular water bolus loaded by malignant tissue. Important factors for the improvement of future bolus designs are also discussed in terms of diameter and configuration of the water input and output tubing network.

Molecular modeling directed by an interfacial test apparatus for the evaluation of protein and polymer ingredient function in situ.

A simplified apparatus is described that measures the damping of a suspended measuring device. The movement of the device (bob) is damped by the properties of the air-water surface adsorbed material. Its value lies in describing the surface chemomechanical properties of ingredients and excipients used in food, nutraceutical, cosmetic (cosmeceutical), and natural drug-food product formulations that traverse the food sciences. Two surfactants, two food and drug-grade polymers, and five naturally occurring food and serum proteins were tested and used to estimate and model interfacial viscoelasticity. Equilibration times of >15 min were found to give sufficiently stable interfaces for routine assessment. The viscoelasticity of the air-water interface was estimated with reference to model solutions. These model solutions and associated self-assembled interfacial nanostructured adsorbed layers were fabricated using a preliminary screening process with the aid of a specialized foaming apparatus ( C(300) values), surface tension measurements (23-73 mN/m), and referential surface shear and dilation experiments. The viscoelasticity measured as a percentage of surface damping ( D) of a pendulum was found to range from 1.0 to 22.4% across the samples tested, and this represented interfacial viscosities in the range of 0-4630 microNs/m. The technique can distinguish between interfacial compositions and positions itself as an easily accessible valuable addition to tensiometric and analytical biochemistry-based techniques.

Validation of high gradient magnetic field based drug delivery to magnetizable implants under flow.

The drug-eluting stent's increasingly frequent occurrence late stage thrombosis have created a need for new strategies for intervention in coronary artery disease. This paper demonstrates further development of our minimally invasive, targeted drug delivery system that uses induced magnetism to administer repeatable and patient specific dosages of therapeutic agents to specific sites in the human body. Our first aim is the use of magnetizable stents for the prevention and treatment of coronary restenosis; however, future applications include the targeting of tumors, vascular defects, and other localized pathologies. Future doses can be administered to the same site by intravenous injection. This implant-based drug delivery system functions by placement of a weakly magnetizable stent or implant at precise locations in the cardiovascular system, followed by the delivery of magnetically susceptible drug carriers. The stents are capable of applying high local magnetic field gradients within the body, while only exposing the body to a modest external field. The local gradients created within the blood vessel create the forces needed to attract and hold drug-containing magnetic nanoparticles at the implant site. Once these particles are captured, they are capable of delivering therapeutic agents such as antineoplastics, radioactivity, or biological cells.

Skin stimulation by the fluid powered self-excited oscillation and its effect on the human body.

A novel fluid power actuator called Flat Ring Tube (FRT) is introduced in this paper. The mechanism of FRT is so simple that it only needs a urethane flat tube and water pressure power source. No valves or switches are required. Applying constant water pressure results in periodic oscillation of the tube. The frequency is proportional to the flow rate of water and inversely proportional to the tube length. By contacting the tube with a passively supported shaft, it rotates due to the periodic tube oscillation. This principle can also generate the linear driving force, when FRT is mounted so as to kick the ground. Such kind of performance can be also expected to stimulate the blood flow rate, when FRT touches on the skin of the human body appropriately. The experimental results showed us the developed wearable massage device could effectively improve both the circulation of the blood flow and the density of oxygen in blood, which resulted in let the people feel more comfortable than conventional massage devices.

Evaluation of different parameters that affect droplet-size distribution from nasal sprays using the Malvern Spraytec.

The applicability of laser diffraction (Spraytec) for characterizing the droplet-size distribution (DSD) from nasal sprays was examined to understand the relationship between physical properties of nasal formulations and their spray characteristics. The impact of actuation force (3-7 kg), rheological properties from carboxymethylcellulose (CMC) and carbopol 934PNF, the influence of surfactant (Tween 80), actuation distance, and different nasal-pump designs on the aerosol DSD of nasal sprays were investigated using Spraytec((R)) with the eNSP actuation station (InnovaSystems, Moorestown, NJ). Spray-pattern analysis was performed by monitoring the emitted nasal spray containing a dye or a fluorescent marker. Parameters for DSD and spray pattern included: Dv(10), Dv(50), Dv(90), polydispersity, minimum and maximum diameters, plume area, and ovality. Increasing actuation distance from 1.5 to 6 cm from the laser beam decreased Dv(50) values by 17-27% for commercial nasal-spray products. Spray-pattern analysis revealed a power law relationship between viscosity and surface area for CMC formulations. However, this relationship could not be obtained for carbopol formulations, which was attributed to differences in their rheological behavior. The addition of surfactant (0.5-5% Tween 80) to a 2% CMC solution decreased the Dv(50) values (16-26%) and altered the rheological properties (e.g., changes in viscosity and appearance of the thixotropic system). Briefly, the characteristic of nasal aerosol generation is dependent on a combination of actuation force, viscosity, rheological properties, surface tension, and pump design. The Spraytec with the eNSP actuation station provides an efficient and reliable way of monitoring the effects of formulation variables on DSD from nasal aerosols.

Rheology of giant vesicles: a micropipette study.

We develop a micropipette rheometer to study the effect of oscillatory shear flow on the spontaneous fluctuations of phospholipid bilayers. Our results on giant vesicles show that oscillatory shear flow leads to a suppression of membrane fluctuations. They also imply that the Helfrich equation is modified in the presence of the flow. This equation, a fundamental constitutive relation between the amount of area stored in the fluctuations and the membrane tension, must be supplemented under oscillatory shear by a flow excess function that we determine.

Osteogenic enrichment of bone-marrow stromal cells with the use of flow chamber and type I collagen-coated surface.

The stromal cells of the bone marrow are able to attach to the surface and differentiate into cells with bone-forming capability when stimulated with osteogenic supplements. In this study, we have employed a flow-chamber device containing a collagen-coated surface to enrich the potential osteoprogenitor cells from bone marrow stromal cells (BMSCs). The population of the cells attached to the collagen-coated substratum is about twice that attached to the uncoated surface. In the flow chamber, almost all marrow cells attached on the untreated glass were flushed out at the shear stress of 1.10 dyne/cm(2). On the other hand, 25% of the marrow cells remained attached to the collagen-coated glass, even under the shear stress of 1.30 dyne/cm(2). The collagen-attached marrow cells exhibited similar, specific alkaline phosphatase activity compared with that of the cells attached to the uncoated dish in the early stage of culturing. Nevertheless, only the collagen-attached marrow cells later expressed significant amounts of osteocalcin, which is a specific marker for osteoblast cells. Thus, we have successfully developed a protocol that uses a collagen-coated surface efficiently in a flow chamber to enrich the osteogenic cells from the BMSCs. This provides a useful tool to obtain osteogenic cells from bone marrow for biologic and clinical applications.

Comparison of a production process in a membrane-aerated stirred tank and up to 1000-L airlift bioreactors using BHK-21 cells and chemically defined protein-free medium.

The applicability of a protein-free medium for the production of recombinant human interleukin-2 with baby hamster kidney cells in airlift bioreactors was investigated. For this purpose, a BHK-21 cell line, adapted to grow and produce in protein-free SMIF7 medium without forming spheroids in membrane-aerated bubble-free bioreactors, was used as the producer cell line. First, cultivation of the cells was established at a 20-L scale using an internal loop airlift bioreactor system. During the culturing process the medium formulation was optimized according to the specific requirements associated with cultivation of mammalian cells under protein-free conditions in a bubble-aerated system. The effects of the addition of an antifoam agent on growth, viability, productivity, metabolic rates, and release of lactate dehydrogenase were investigated. Although it was possible to establish cultivation and production at a 20-L scale without the use of antifoaming substances, the addition of 0.002% silicon-oil-based antifoaming reagent improved the cultivation system by completely preventing foam formation. This reduced the release of lactate dehydrogenase activity to the level found in bubble-free aerated stirred tank membrane bioreactors and led to a reduction in generation doubling times by about 5 h (17%). Using the optimized medium formulation, cells were cultivated at a 1000-L scale, resulting in a culture performance comparable to the 20-L airlift bioreactor. For comparison, cultivations with protein-containing SMIF7 medium were carried out at 20- and 1000-L scales. The application of protein supplements did not lead to a significant improvement in the cultivation conditions. The results were also compared with experiments performed in a bubble-free aerated stirred tank membrane bioreactor to evaluate the influence of bubbles on the investigated culture parameters. The data implied a higher metabolic activity of the cells in airlift bioreactors with a 150% higher glucose consumption rate. The results of this study clearly demonstrate the applicability of a protein-free chemically defined medium for the production of recombinant proteins with BHK cells in airlift bioreactors.