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关键词： Forward osmosis (FO)   Osmotic membrane bioreactor   Seawater   Brine   Elevated salinity   Shortcut pathway of nitrogen removal  

摘要： Forward osmosis membrane bioreactor (FOMBR) is an integrated physical-biological treatment process that has received increased awareness in treating municipal wastewater for its potential to produce high effluent quality coupled with its low propensity for fouling formation. However, reverse salt diffusion (RSD) is a major issue and so far limited studies have reported long-term FOMBR operation under the elevated salinity conditions induced by RSD. This study investigated the performance of a FOMBR in treating municipal wastewater under a controlled saline environment (6-8 g L-1 NaCl) using two separate sodium chloride draw solution (NaCl DS) concentrations (35 and 70 g L-1) over 243 days. At 35 g L-1 NaCl DS, the water flux performance dropped from 6.75 L m(-2) L-1 (LMH) to 2.07 LMH after 72 days of operation in the first experimental stage, when no cleaning procedure was implemented. In the subsequent stage, the DS concentration was increased to 70 g L-1 and a weekly physical cleaning regime introduced. Under stable operation, the water flux performance recovery was 67% after 21 cycles of physical cleaning. For the first time in FOMBR studies, a shortcut nitrogen removal via the nitrite pathway was also achieved under the elevated salinity conditions. At the end of operation (day 243), the ammonia-oxidising bacteria (Nitrosomonas sp.) was the only nitrifler species in the system and no nitrite oxidising bacteria was detected. The above study proves that a FOMBR system is a feasible process for treating municipal wastewater. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： attached growth MBR   domestic wastewater   membrane bioreactor   membrane fouling   wastewater treatment  

摘要： The performance of laboratory scale experiments in treating synthetic domestic wastewater were conducted with suspended growth (SG) (without media) and attached growth (AG) (with moving media) membrane bioreactors (MBRs). The aim of this study is to compare fouling and the treatment performance of attached growth membrane bioreactor (AGMBR) with suspended growth membrane bioreactor (SGMBR) by assessing the removal of chemical oxygen demand (COD), nitrate, nitrite and ammonia. The finding shows that with 10% of attached growth media, average COD, nitrate, nitrite and nitrogen ammonia removal efficiency for AGMBR were found to be greater than the SGMBR system. AGMBR significantly increased critical flux, (J(c)) up to 48 L m(-2) h(-1), hence producing low final transmembrane pressure (TMP) after cleaning and decreased the total resistance at 5.69 x 10(11) m(-1). Addition of cylindrical polythene media resulted in slow TMP increment that prolonged filtration process. In conclusion, AGMBR gave a better treatment performance and could minimize the membrane fouling problem.

关键词： cardiac tissue engineering   left atrial appendage   plastic compression   scaffold prevascularization  

摘要： Treatment of terminal heart failure still poses a significant clinical problem. Cardiac tissue engineering could offer autologous solutions for the replacement of nonfunctional myocardial tissue. So far, soft matrix construction and missing large-scale prevascularization prevented the application of sizeable cardiac repair patches. We developed a novel bioreactor system for semi-automatic compression of a collagen I hydrogel applying 16 times higher pressure than in previous studies. Resistance towards compression stress was investigated for multiple cardiac-related cell types. For scaffold prevascuarization, a tubular cavity was imprinted during the compaction process. Primary cardiac-derived endothelial cells (ECs) were isolated from human left atrial appendages (HLAAs) and characterized by fluorescence-activated cell sorting (FACS) and immunocytology. EC were then seeded into the preformed channel with dermal fibroblasts as interstitial cell component of the fully cellularized patch. After 8 days of constant perfusion culture within the same bioreactor, scaffold dynamic modulus and cell viability were analyzed. Endothelial proliferation and vessel maturation were examined by immunohistochemistry and transmission electron microscopy. Our design allowed for scaffold production and dynamic culture in a one-stop-shop model. Enhanced compression and cell-mediated matrix remodeling induced a significant increase in scaffold stiffness while ensuring excellent cell survival. For the first time, we could isolate HLAA-derived EC with proliferative potential. ECs within the central channel proliferated during flow culture, continuously expressing endothelial markers (CD31) and displaying basal membrane synthesis (collagen IV, ultrastructural analysis). After 7 days of culture, a complete endothelial monolayer could be observed. Covering cells aligned themselves in flow direction and developed mature cell-cell contacts.

关键词： Sulfadiazine   Hybrid moving bed biofilm reactor-membrane bioreactor system   Impacts   Membrane fouling   C/N ratio  

摘要： The performance and membrane fouling of a hybrid moving bed biofilm reactor-membrane bioreactor (MBBRMBR) system was evaluated when exposed to 0.5 mg/L of antibiotic sulfadiazine (SDZ). Results indicated that although SDZ reduced the removal efficiency of NH4+-N and TN (up to 12%) and TOC (up to 6%) at low C/N (2.5 and 4), it had no significant effect at high C/N (6 and 9). It was found that SDZ was removed 75% and 58% at high C/N of 9 and low C/N of 2.5, respectively. SDZ decreased the ratio of volatile biomass/total biomass and sludge particle size and increased the concentrations of extracellular polymeric substance (EPS) and soluble microbial product (SMP) in MBR. Consequently, this accelerated the membrane fouling rates, with an average increase of 6.85 kPa/d at low C/N (2.5) and 0.513-0.701 kPa/d at medium and high C/N (4, 6 and 9).

关键词： Bone marrow history   Stem cells   Osteonecrosis   Marrow transplantation   Tissue engineering  

摘要： Purpose Three hundred seventy million years ago, bone marrow appeared in skeleton of a fish. More than one hundred years ago, the concept of bone marrow transplantation was proposed to treat human diseases. During the last five decades, this concept became a reality first in hematology and later for orthopaedic diseases. Material and methods These advances were possible due to the comprehension of the three major components of bone marrow: the fat part, the haematologic part, and the stroma part. Each part has a different history, but the three parts are linked in physiology as in history. Results During many centuries, bone marrow was considered just as food;however, one hundred years ago, the concept of bone marrow transplantation to treat humans was proposed by the French physician Brown-Sequard. During the last five decades, this concept became a reality first in haematology and later for orthopaedic diseases. Transferring what was known from experimental animal models to humans was met with many challenges, the atomic bomb research, and many deaths. Yet through the recognition and subsequent understanding of fundamental processes, medical resiliency, and the determination of a few pioneers, local bone marrow transplantation in orthopaedic surgery became a therapeutic option first for a limited number of diseases and patients. Over the last two decades, mesenchymal stromal cells (MSCs) have been the focus of intense research by acadaemia and industry due to their unique features. MSCs can be easily isolated and expanded through in vitro culture by taking full advantage of their self-renewing capacity. In addition, MSCs exert immunomodulatory effects and can be differentiated into various lineages, which makes them highly attractive for clinical applications in cell-based therapies. Conclusion In this review, we attempted to provide a historical overview of bone marrow history, MSC discovery, characterization, and the first clinical studies conducted.

关键词： Flow modeling   perfusion bioreactor   rotating and perfusion bioreactor   computational modeling   bone tissue engineering  

摘要： Bioreactor system has been used in bone tissue engineering in order to simulate dynamic nature of bone tissue environments. Perfusion bioreactors have been reported as the most efficient types of shear-loading bioreactor. Also, combination of forces, such as rotation plus perfusion, has been reported to enhance cell growth and osteogenic differentiation. Mathematical modeling using sophisticated infrastructure processes could be helpful and streamline the development of functional grafts by estimating and defining an effective range of bioreactor settings for better augmentation of tissue engineering. This study is aimed to conduct computational modeling for newly designed bioreactors in order to alleviate the time and material consuming for evaluating bioreactor parameters and effect of fluid flow hydrodynamics (various amounts of shear stress) on osteogenesis. Also, biological assessments were performed in order to validate similar parameters under implementing the perfusion or rotating and perfusion fluid motions in bioreactors' prototype. Finite element method was used to investigate the effect of hydrodynamic of fluid flow inside the bioreactors. The equations used in the simulation to calculate the velocity values and consequently the shear stress values include Navier-Stokes and Brinkman equations. It has been shown that rotational fluid motion in rotating and perfusion bioreactor produces more velocity and shear stress compared with perfusion bioreactor. Moreover, implementing the perfusion together with rotational force in rotating and perfusion bioreactors has been shown to have more cell proliferation and higher activity of alkaline phosphatase enzyme as well as formation of extra cellular matrix sheet, as an indicator of bone-like tissue formation.

关键词： dissolved oxygen   fetal hepatic organoids   human pluripotent stem cells   red blood cells   stirred tank bioreactor  

摘要： Developing technologies for scalable production of human organoids has gained increased attention for "organoid medicine" and drug discovery. We developed a scalable and integrated differentiation process for generation of hepatic organoid from human pluripotent stem cells (hPSCs) in a fully controlled stirred tank bioreactor with 150 ml working volume by application of physiological oxygen concentrations in different liver tissue zones. We found that the 20-40% dissolved oxygen concentration [DO] (corresponded to 30-60 mmHg pO(2)within the liver tissue) significantly influences the process outcome via regulating the differentiation fate of hPSC aggregates by enhancing mesoderm induction. Regulation of the [DO] at 30% DO resulted in efficient generation of human fetal-like hepatic organoids that had a uniform size distribution and were comprised of red blood cells and functional hepatocytes, which exhibited improved liver-specific marker gene expressions, key liver metabolic functions, and, more important, higher inducible cytochrome P450 activity compared to the other trials. These hepatic organoids were successfully engrafted in an acute liver injury mouse model and produced albumin after implantation. These results demonstrated the significant impact of the dissolved oxygen concentration on hPSC hepatic differentiation fate and differentiation efficacy that should be considered ascritical translational aspect of established scalable liver organoid generation protocols for potential clinical and drug discovery applications.

关键词： Fixed-bed bioreactor   Scale-down   Low cell inoculum density   Serum-free   Pseudorabies virus  

摘要： Fixed-bed bioreactors packed with macrocarriers show great potential to be used for vaccine process development and large-scale production due to distinguishing features of low shear force, high cell adhering surface area, and easy replacement of culture media in situ. As an initial step of utilizing this type of bioreactors for Pseudorabies virus production (PRV) by African green monkey kidney (Vero) cells, we developed a tube-fixed-bed bioreactor in the previous study, which represents a scale-down model for further process optimization. By using this scale-down model, here we evaluated impacts of two strategies (use of serum-free medium and low cell inoculum density) on PRV production, which have benefits of simplifying downstream process and reducing risk of contamination. We first compared Vero cell cultures with different media, bioreactors and inoculum densities, and conclude that cell growth with serum-free medium is comparable to that with serum-containing medium in tube-fixed-bed bioreactor, and low inoculum density supports cell growth only in this bioreactor. Next, we applied serum-free medium and low inoculum cell density for PRV production. By optimization of time of infection (TOI), multiplicity of infection (MOI) and the harvesting strategy, we obtained total amount of virus particles similar to 9 log(10) TCID50 at 5 days post-infection (dpi) in the tube-fixed-bed bioreactor. This process was then scaled up by 25-fold to a Xcell 1-L fixed-bed bioreactor, which yields totally virus particles of 10.5 log(10) TCID50, corresponding to similar to 3 x 10(5) doses of vaccine. The process studied in this work holds promise to be developed as a generic platform for the production of vaccines for animal and human health.

关键词： Bioethanol   Fed-batch extractive fermentation   Liquid-liquid extraction   Drop column bioreactor   High substrate concentration  

摘要： The use of fed-batch extractive fermentation can overcome inhibitory effects caused by the substrate and ethanol to the yeast cells, since it allows regulate the substrate concentration and remove the product as it is produced. The present study describes the modelling and experimental validation of ethanol production in fed-batch extractive fermentation with in situ ethanol removal by oleic acid in a non-conventional drop column bioreactor (DCB) operated under industrial conditions. The model developed using the hybrid Andrews-Levenspiel equation and ethanol distribution coefficient parameter (K-DE) provided an excellent description of the fed-batch extractive ethanol fermentation process with oleic acid. Furthermore, extractive fed-batch fermentation allowed the feed up to 306.6 kg m(-3)of substrate (total reducing sugars), with total ethanol concentration in extractive fermentation in the ranging 100.3-139.8 kg m(-3)(12.7-17.7 oGL), 19.9-67.2% higher when compared with the conventional process without ethanol removal. Moreover, this process has the advantage of less effluent generated and energy consumption for ethanol recovery when compared to the conventional process.

关键词： Fructosyltransferase   beta-fructofuranosidase   Fructooligosaccharides   Aspergillus   Enzyme production   K(L)a  

摘要： Objective Fructooligosaccharides (FOS) are prebiotic substances that have been extensively incorporated in different products of food industry mostly for their bifidogenic properties and economic value. The main commercial FOS production comes from the biotransformation of sucrose and intracellular and extracellular microbial enzymes-fructosyltransferases (FTase). Aspergillus oryzaeIPT-301 produces FTase. In order to increase its production, this study focuses on evaluating the effects of different agitation speed and aeration rates which affect yields in a stirred tank bioreactor. Results Agitation had more influence on cell growth than aeration. The maximum intracellular FTase activity and the volumetric productivity of total intracellular FTase were obtained at 800 rpm and 0.75 vvm, and reached values of 2100 U g(-1)and 667 U dm(-3) h(-1), respectively. The agitation speed had a strong influence on the activity of extracellular FTase produced which reached the maximum amount of 53 U cm(-3). The higher value of total activity obtained was 22,831 U dm(-3) at 0.75 vvm and 800 rpm. Conclusion Aeration rates and agitation speed showed strong influence upon the growth and production of fructosyltransferase fromAspergillus oryzaeIPT-301 in media containing sucrose as carbon source. The control of aeration rate and agitation speed can be a valuable fermentation strategy to improve enzyme production.