Medium Dilution Rate Research Articles

Achieving excellent properties of laser tailor-welded thin Al-Si coated press-hardened steel joint via controlling dilution rate

In laser tailor welded traditional 25 μm thick Al-Si coated press-hardened steel (PHS), a lot of ferrite was easily formed in the weld, so filling with expensive high-alloys wire is usually necessary. In this work, a new thin Al-Si coated PHS with 18 μm thickness was laser tailor welded, and a cheap low alloy wire was attempted to fill into the weld to via control the dilution rate. At a high dilution rate of 94%, the weld contained a ferrite fraction of 38%, resulting in the fracture occurring in the weld during tension and bending. At a medium dilution rate of 85%, the ferrite fraction in the weld decreased to 18%, obtaining excellent tensile and bending properties. The tensile strength and elongation of the joint reached 1528 MPa and 5.6%, respectively, with fracture being in the base metal (BM). The maximum bending load and displacement were 1291 N and 7.0 mm, respectively, and cracks initiated and propagated in the BM. This is attributed to the small amount of ferrite and stress concentration in the narrow weld. At a low dilution rate of 76%, the ferrite reduced to 6%, and the bending cracks initiated and propagated in the BM. However, the tensile specimen fractured in the weld, which should be related to the relatively low C concentration and the stress concentration at the weld toe due to the weld reinforcements.

Нейросетевое моделирование изменения концентрации молочной кислоты в ходе непрерывной ферментации бифидобактерий

In this work the changes in the lactic acid concentration during continuous fermentation of bifidobacteria have been investigated to obtain a neural network mathematical description. The fermentation was carried out under the conditions close to those of the descending colon (maintaining pH of 6.8 with 20% sodium hydroxide; anaerobiosis; the medium dilution rate was 0.04 h-1). This colon section is characterized by a large number of microorganisms, as well as their enormous influence on the host organism. The researches were carried out with the probiotic strain of Bifidobacterium adolescentis VKPM Ac-1662 (ATCC 15703T), the concentrations of the prebiotic oligofructose were varied (2, 5, 10, 15 g/l). Until a dynamic equilibrium state and at least 36 h after that, the concentrations of lactic and acetic acids using the of high performance liquid chromatography, optical density and viable bacteria count (CFU/ml) were measured. The neural network was trained on the basis on the obtained experimental data. The multilayer perceptron was chosen as the main architecture of the neural network. The vectors of the training sample include 6 variables: 5 input and 1 output. The training took place synchronously using the error back propagation method. The general error of the neural network was 1.85%. It was proved that the neural network approach helps to well illustrate the influence of various factors on the course of biotechnological processes; it summarizes the multiple experimental data with an acceptable error. The resulting neural network mathematical description proves that the representativeness of the training sample is important for obtaining the most accurate mathematical description. Further researches are needed to obtain a mathematical description of the change in the all environment components concentration in the form of a complex of the trained artificial neural networks.

Analysis of Contrast Medium Dilution Rate for changes in Tube Current and SOD, which are Parameters of Lower Limb Angiography Examination

Analysis of Contrast Medium Dilution Rate for changes in Tube Current and SOD, which are Parameters of Lower Limb Angiography Examination

A systematic comparison of ectoine production from upgraded biogas using Methylomicrobium alcaliphilum and a mixed haloalkaliphilic consortium

Biogas is the byproduct of anaerobic digestion with the highest valorization potential, however its full exploitation is limited by the lack of tax incentives and the inherent presence of pollutants. The development of technologies for biogas conversion into added-value products is crucial in order to ensure the competitiveness of this bioresource. This study constitutes the first proof of concept of upgraded biogas bioconversion into the high profit margin product ectoine. Ectoine represents the most expensive product synthesized by microorganisms with a retail value of 1000 $ kg−1 and a yearly increasing demand that currently entails a total market opportunity of 15000 M€. First, the production of ectoine from upgraded biogas was assessed in batch bioreactors. The presence of H2S did not exert a negative effect on the growth of the haloalkaliphilic ectoine producers, and ectoine yields up to 49 mg g biomass−1 were obtained. A second experiment conducted in continuous bubble column bioreactors confirmed the feasibility of the process under continuous mode (with ectoine yields of 109 mg g biomass−1). Finally, this study revealed that the removal of toxic compounds (i.e. medium dilution rate of 0.5 day−1) and process operation with a consortium composed of methylotrophic/non-methylotrophic ectoine producers enhanced upgraded biogas bioconversion. This research discloses the basis for the application of this innovative technology and could boost the economic performance of anaerobic digestion.

65 Inactivation Kinetics of Epizootic Hemorrhagic Disease Virus (EHDV) By Ingredients Contained in Expect Healthy Deer Technology®.

Expect Healthy Deer Technology® is a novel feed additive that contains natural feed ingredients that are known to have anti-viral, anti-bacterial, and anti-fungal properties. Epizootic Hemorrhagic Disease (EHD), caused by EHD virus (EHDV), is a hemorrhagic disease spread by small biting midge gnats affecting certain species of animals, especially deer, although it can also affect elk and cattle. Death losses in deer from EHDV are very high, and in localized outbreaks, it can wipe out a large percentage of a deer herd. The aim of this study was to evaluate the virucidal effectiveness of a key ingredient contained in Expect Health Deer Technology® against EHDV. Briefly, serial dilutions of the key ingredient were mixed with equal amounts of EHDV. Samples were removed after various periods of contact and tested for the amount of surviving virus by inoculation in baby hamster kidney cells (BHK-21), which can support infection by EHDV. Serotype 1 of EHDV (EHDV-1) was obtained from the National Veterinary Services Laboratories, Ames, IA. To determine virucidal activity, titer levels of EHDV were calculated in triplicate for each dilution of the ingredient. The initial virus titer for the EHDV-1 was 3.50 log10 TCID50/0.1 ml. At the low dilution rate (1:2 dilution), the ingredient killed (P < 0.05) 3 logs (99.9%) of virus within 2 h and killed (P < 0.05) 2.5 logs at 12 and 24 h. At a medium dilution rate (1:20) the ingredient killed (P < 0.05) 3 logs (99.9%) of the EHD virus after 2 h, but killed (P < 0.05) 2.5 logs after 12 and 24 hours. At the high dilution rate (1:200) the ingredient killed (P < 0.05) 3 logs (99.9%) of virus after 2 h, but killed (P < 0.05) 2.5 logs after 12 and 24 h. At ultra-high dilution rates (1:2,000 and 1:20,000) the ingredient was less effective. In summary, the ingredient within Expect Healthy Deer Technology® demonstrated strong virucidal activity against EHDV under in-vitro (laboratory) conditions.

A microfluidic platform for physical entrapment of yeast cells with continuous production of invertase

AbstractBACKGROUNDThe rapidly increasing use of biotechnology in many industries has led to the need for novel methods for cell culture which provide an efficient way to either optimize or perform fermentation operations. In parallel, microfabrication techniques allowed the development of microfluidic chips for complex handling of fluids and cells.RESULTSThis work presents a microfluidic platform to trap non‐adherent cells for the continuous production of a biomolecule of interest. The biological system chosen as a model was the yeast species Saccharomyces cerevisiae and the extracellular protein invertase. The use of the appropriate combination of the flow rate of the medium, medium dilution rate, and pH allowed effective control of the cell growth in the microfluidic bioreactor while at the same time maximizing the invertase activity per cell. The microfluidic bioreactor allowed for continuous cell culture for 32 h and its productivity both per cell (3.22 × 10−8 U cell−1) and per consumed nutrient (3.79 U mg−1 sucrose) was consistently higher than its macroscale batch and continuous reactor counterparts.CONCLUSIONThis work demonstrated that a microfluidic bioreactor can be used for continuous production of an extracellular protein using hydrodynamically trapped non‐adherent yeast cells. © 2016 Society of Chemical Industry

Immobilised cells of Pachysolen tannophilus yeast for ethanol production from crude glycerol

Screening among naturally occurring yeast strains of Pachysolen spp. that are capable of producing ethanol from glycerol under aerobic conditions identified the most active culture, P. tannophilus Y −475. Conversion of glycerol by this producer immobilised in poly(vinyl alcohol) cryogel resulted in a 90% yield of ethanol relative to the theoretical limit. The maximum rate of alcohol accumulation was 0.64±0.01gL−1h−1 at a 25gL−1 concentration of glycerol in the culture medium. We demonstrated the efficacy of reusing immobilised cells (for a minimum of 16 working cycles for batch mode of crude glycerol conversion to ethanol) and the possibility of long-term (for a minimum of 140h) use of the cells in continuous mode with a maximum process productivity of 0.63±0.02gL−1h−1, while the medium dilution rate in the reactor was 0.062±0.001h−1. Reduction of metabolic activity did not exceed 5–7% relative to baseline. Immobilised cells were demonstrated to withstand long-term storage in frozen form for at least 2 years while retaining high metabolic activity.

Use of Saccharomyces cerevisiae and Zymomonas mobilis for bioethanol production from sugar beet pulp and raw juice

Biofuels have received great attention as an alternative energy source mainly due to limited oil reserves. Bioethanol can be produced from wide range of raw materials like starch, sucrose and cellulosic based sources. Sugar beet and raw juice, as its intermediate product, constitute very profitable substrates for bioethanol production, considering content of easy available fermentable sugars. In this study, sugar beet pulp and raw juice were fermented with Saccharomyces cerevisiae distillery yeasts and bacterium Zymomonas mobilis . Different medium dilution rate as well as yeasts preparations (Fermiol, Safdistil C-70) were investigated. Fermentation was run for 72 h at 30°C. Quality of obtained raw distillates was evaluated using GC method. S. cerevisiae distillery yeasts turned out to be more favourable microorganism than bacterium Z. mobilis for sucrose material fermentation. The ethanol yield obtained from sugar beet pulp and raw juice was 84 and 95% of theoretical yield, respectively. Fermentation of sugar beet raw juice obtained by pressing without enzymatic treatment yielded higher ethanol efficiency as compared to raw juice pressed with enzyme. Dilution ratio 1:1 for fermentation medium appeared to be profitable for effective fermentation process. Keywords : Sugar beet roots, raw juice, fermentation, bioethanol, Saccharomyces cerevisiae, Zymomonas mobilis African Journal of Biotechnology Vol. 12(18), pp. 2464-2470

Quantitative analysis of media dilution rate effects on Methanothermobacter marburgensis grown in continuous culture on H2 and CO2

Abstract The characterization of hydrogenotrophic methanogens by using analytical bioprocess technology holds great potential for the development of biological gas conversion processes. Therefore, we aimed to investigate the influence of liquid dilution rate and total gassing rate on the performance of Methanothermobacter marburgensis grown in continuous culture on H 2 /CO 2 . By increasing medium dilution rate M. marburgensis biomass concentration decreased while specific methane and specific water productivity increased. Low liquid dilution rates resulted in highest volumetric uptake and production rates. Steady state cultivations were limited in the mass transfer from the gas to the liquid phase. By quantification of biological water production we were able to give additional insight into maintenance requirements of M. marburgensis . At higher growth rates, water production can be used as an additional on-line signal to quantify biological activity, as it is directly correlated to methane productivity. We demonstrate the usefulness of dynamic investigations, such as the medium dilution shift experiment, in order to physiologically characterize hydrogenotrophic methanogens for its maximum specific methane productivity. Process development can focus on the optimization of the gas-liquid mass transfer, until this physiological limit is reached.

Efficacy of bacterial consortium-AIE2 for contemporaneous Cr(VI) and azo dye bioremediation in batch and continuous bioreactor systems, monitoring steady-state bacterial dynamics using qPCR assays

Bacterial consortium-AIE2 with a capability of contemporaneous Cr(VI) reduction and azo dye RV5 decolourization was developed from industrial wastewaters by enrichment culture technique. The 16S rRNA gene based molecular analyses revealed that the consortium bacterial community structure consisted of four bacterial strains namely, Alcaligenes sp. DMA, Bacillus sp. DMB, Stenotrophomonas sp. DMS and Enterococcus sp. DME. Cumulative mechanism of Cr(VI) reduction by the consortium was determined using in vitro Cr(VI) reduction assays. Similarly, the complete degradation of Reactive Violet 5 (RV5) dye was confirmed by FTIR spectroscopic analysis. Consortium-AIE2 exhibited simultaneous bioremediation efficiencies of (97.8 +/- 1.4) % and (74.1 +/- 1.2) % in treatment of both 50 mg l(-1) Cr(VI) and RV5 dye concentrations within 48 h of incubation at pH 7 and 37 degrees C in batch systems. Continuous bioreactor systems achieved simultaneous bioremediation efficiencies of (98.4 +/- 1.5) % and (97.5 +/- 1.4) % after the onset of steady-state at 50 mg l(-1) input Cr(VI) and 25 mg l(-1) input RV5 concentrations, respectively, at medium dilution rate (D) of 0.014 h(-1). The 16S rRNA gene copy numbers in the continuous bioreactor as determined by real-time PCR assay indicated that Alcaligenes sp. DMA and Bacillus sp. DMB dominated consortium bacterial community during the active continuous bioremediation process.

On-line size measurement of yeast aggregates using image analysis.

Alcohol fermentation productivity can be strongly improved using a flocculation-based yeast recycle. However, the efficiency of the biomass retention system depends strongly on the yeast particle size. Accordingly, the monitoring and control of yeast floc diameter are of primary importance. The on-line measurement of mean floc diameter has been achieved using on-line image analysis, based on the evaluation of image texture. The texture analysis method consisted in the building of a co-occurrence matrix from which the so-called "Energy parameter" was extracted. While image texture is usually used for classification purposes, it has been used here as a quantitative descriptor: a correlation has been found between this statistical image feature and off-line manual floc-size determinations. In the floc-size range investigated (X 0.5-4.3 mm), the evaluated mean diameter was in good agreement with the actual particle size, with a determination coefficient equal to 0.980. In contrast with manual measurements, slow and tedious, this method gave the value of the mean particle diameter in real-time, without sampling. This novel tool has been used to investigate the behavior of yeast aggregates as a function of fermentation conditions. While biomass concentration was kept constant, step increases of the feed rate led to a decrease of the mean floc diameter. Image analysis showed that the particle-size reduction could occur within a few minutes after modification of the medium dilution rate, demonstrating the disruptive effect of the CO(2) efflux. The kinetic of aggregate formation was dependent on the gas-phase composition. Instead of recycling fermentation gas, sparging the fermentor with nitrogen, to reduce dissolved CO(2) concentration, increased the rate of floc-size growth.

High production of 1,3-propanediol from industrial glycerol by a newly isolated Clostridium butyricum strain

Batch and continuous cultures of a newly isolated Clostridium butyricum strain were carried out on industrial glycerol, the major by-product of the bio-diesel production process. For both types of cultures, the conversion yield obtained was around 0.55 g of 1,3-propanediol formed per 1 g of glycerol consumed whereas the highest 1,3-propanediol concentration, achieved during the single-stage continuous cultures was 35–48 g l −1. Moreover, the strain presented a strong tolerance at the inhibitory effect of the 1,3-propanediol, even at high concentrations of this substance at the chemostat (e.g. 80 g l −1). 1,3-Propanediol was associated with cell growth whereas acetate and butyrate seemed non growth-associated products. At low and medium dilution rates (until 0.1 h −1), butyrate production was favoured, whereas at higher rates acetate production increased. The maximum 1,3-propanediol volumetric productivity obtained was 5.5 g l −1 h −1. A two-stage continuous fermentation was also carried out. The first stage presented high 1,3-propanediol volumetric productivity, whereas the second stage (with a lower dilution rate) served to further increase the final product concentration. High 1,3-propanediol concentrations were achieved (41–46 g l −1), with a maximum volumetric productivity of 3.4 g l −1 h −1. A cell concentration decrease was reported between the second and the first fermentor.

Extractive fermentation by Zymomonas mobilis and the control of oscillatory behavior

Extractive fermentation is shown to greatly improve the performance ofZymomonas mobilis in continuous culture during the conversion of concentrated substrates to ethanol, and it is also used to eliminate the oscillatory behavior often exhibited byZ. mobilis in conventional fermentations. An ethanol productivity of 15.6 g/Lh is achieved with the near-conversion of a 295 g/L glucose feed at a medium dilution rate of 0.11 h−1 and solvent dilution rate of 1.5 h−1. This is more than triple the productivity obtained during conventional fermentation of a 135 g/L glucose feed at the same medium dilution rate.

An immobilized hybridoma culture perfusion system for production of monoclonal antibodies

A fixed bed perfusion system for hybridoma cell immobilization is presented. The system consists of a culturing vessel (300 ml total volume) in which polyurethane (PU) sponges in the form of small cubes of about 5 mm sides are packed. Cells are immobilized by physical entrapment in the foam matrix. By entrapment of the cells in the pores of the matrix high cell concentration can be maintained in a mechanically protected environment. Medium is continuously circulated by an airlift pump mounted in the cell-free chamber (700 ml total volume).Medium flow rate, feeding rate, dissolved oxygen, pH, nutrient uptake and waste product formation can be easily monitored and controlled. Steady state conditions are established with medium dilution rates of 1.0-1.5 reactor volume per day. The steady state is characterized by a constant cell density, constant culture volume and constant glucose and lactate levels. Cell-free supernatant is collected continuously in a cold room adjacent to the 37°C culture room. Monoclonal antibodies (MAb) are produced at a concentration of 150-200 μg/ml for several weeks. An important feature of the system is the capacity to maintain a population of cells after the growth phase in a non-proliferating state for extended time periods expressing high titers of MAb.