Optimal Dilution Rate Research Articles

Tubular photobioreactor design based on mixing intensity

A novel design methodology for tubular photobioreactors (TPBRs) for the mass culture of microalgae that can account for mixing intensity is presented. To date, TPBRs have been mainly designed and operated under the assumption of perfect mixing with regard to photosynthesis performance (light integration regime). In this work we show that this simplification has been leads to significant errors in the prediction of the optimal dilution rate and biomass productivity. To this end, computational fluid dynamics and light distribution model have been employed to calculate the trajectories and light histories I(t) of a microalgal cell population represented by 50 particles of 5 μm diameter. The density of the microalgal cells was set at 1000 kg m−3 and the tube diameters (D) were 14, 24, 44, 64 and 84 mm, with the circulation velocities (v) ranging from 0.4 to 1 m s-1. This has been coupled to a dynamic photosynthesis model in order to calculate the average photosynthetic response and hence the integration factors in TPBRs. It has been demonstrated that for a generic microalgal strain, the use of the light integration simplification (Γ = 1) would result in the prediction of an optimal dilution rate of 0.0315 h−1 (for D = 14 mm and v = 0.4 m/s as an example), which would lead to an actual biomass productivity of 182.5 g biomass m−3h−1 if the predicted integration factor (Γ = 0.578) is used whereas the newly proposed method predicts an optimal dilution rate of 0.0125 h−1 and a biomass productivity of 362.3 g biomass m−3h−1. This demonstrates that simplifying the light integration regime is inadequate for TPBRs design and operation, resulting in significant inaccuracies. The estimation charts and regressions proposed in this work to estimate actual integration factors will enable the development of an optimization method for TPBRs based on mixing intensity.

First dose optimization study on freezing Anatolian buffalo semen

The main objective of sperm production centers is to produce as many straws as possible from the obtained ejaculates using the optimal dilution rate. To this end, this study is the first to evaluate the effect of different semen extender rates on Anatolian buffalo semen quality. Ejaculates were collected by artificial vagina from three Anatolian buffalo bulls. These ejaculates were divided into three aliquots and filled into 0.25 ml straws with soy-based extenders at concentrations of 35, 25, and 15 million sperm/straw (n=105). The straw samples of different sperm concentrations were frozen. The quality of sperm was evaluated after thawing (37 °C, 30 sec) and following the thermoresistance test (37 °C, 3 h). The post-thaw total motility and progressive motility values were similar between the groups. However, following the thermoresistance test, there was a significant decrease in total motility in the 35 million sperm/straw group, and the progressive motility was significantly higher in the 25 million sperm/straw group. There was no statistically significant difference between the groups in terms of sperm kinetic parameters, except for VSL after thawing, as well as VAP and LIN values following the thermoresistance test. The overall mean PMAI and STR values were the highest in the 25 million sperm/straw group. In conclusion, it is recommended to dilute the Anatolian buffalo semen at a concentration of 25 million/0.25 ml when freezing it with a soy-based semen extender. In addition, it is considered that soy-based extenders compensate for cryo-damage to sperm motility for a short time, and the thermoresistance test should be applied for objective evaluation in dose optimization studies.

Sustainable menaquinone-7 production through continuous fermentation in biofilm bioreactors.

Menaquinone-7 (MK-7), a vital vitamin with numerous health benefits, is synthesized and secreted extracellularly by the formation of biofilm, dominantly in Bacillus strains. Our team developed an innovative biofilm reactor utilizing Bacillus subtilis natto cells to foster biofilm growth on plastic composite supports to produce MK-7. Continuous fermentation in biofilm reactors offers a promising strategy for achieving sustainable and efficient production of Menaquinone-7 (MK-7). Unlike conventional batch fermentation, continuous biofilm reactors maintain a steady state of operation, which reduces resource consumption and waste generation, contributing to sustainability. By optimizing fermentation conditions, MK-7 production was significantly enhanced in this study, demonstrating the potential for sustainable industrial-scale production. To determine the optimal operational parameters, various dilution rates were tested. These rates were selected based on their potential to enhance nutrient supply and biofilm stability, thereby improving MK-7 production. By carefully considering the fermentation conditions and systematically varying the dilution rates, MK-7 production was significantly enhanced during continuous fermentation. The MK-7 productivity was found to increase from 0.12mg/L/h to 0.33mg/L/h with a dilution rate increment from 0.007 to 0.042h-1). This range was chosen to explore the impact of various nutrient supply rates on MK-7 production and to identify the optimal conditions for maximizing productivity. However, a further increase in the dilution rate to 0.084h-1 led to reduced productivity at approximately 0.16mg/L/h, likely due to insufficient retention time for effective biofilm formation. Consequently, a dilution rate of 0.042h-1 exhibited the highest productivity of 0.33mg/L/h, outperforming all investigated dilution rates and demonstrating the critical balance between nutrient supply and retention time in continuous fermentation. These findings validate the feasibility of operating continuous fermentation at a 0.084h-1 dilution rate, corresponding to a 48h retention time, to achieve the highest MK-7 productivity compared to conventional batch fermentation. The significant advancements achieved in enhancing Menaquinone-7 (MK-7) productivity through continuous fermentation at optimal dilution rates in the present work indicate promising prospects for even greater efficiency and sustainability in MK-7 production through future developments.

A Single-Step Method for Harvesting Influenza Viral Particles from MDCK Cell Culture Supernatant with High Yield and Effective Impurity Removal

Influenza vaccines, which are recommended by the World Health Organization (WHO), are the most effective preventive measure against influenza virus infection. Madin–Darby canine kidney (MDCK) cell culture is an emerging technology used to produce influenza vaccines. One challenge when purifying influenza vaccines using this cell culture system is to efficiently remove impurities, especially host cell double-stranded DNA (dsDNA) and host cell proteins (HCPs), for safety assurance. In this study, we optimized ion-exchange chromatography methods to harvest influenza viruses from an MDCK cell culture broth, the first step in influenza vaccine purification. Bind/elute was chosen as the mode of operation for simplicity. The anion-exchange Q chromatography method was able to efficiently remove dsDNA and HCPs, but the recovery rate for influenza viruses was low. However, the cation-exchange SP process was able to simultaneously achieve high dsDNA and HCP removal and high influenza virus recovery. For the SP process to work, the clarified cell culture broth needed to be diluted to reduce its ionic strength, and the optimal dilution rate was determined to be 1:2 with purified water. The SP process yielded a virus recovery rate exceeding 90%, as measured using a hemagglutination units (HAUs) assay, with removal efficiencies over 97% for HCPs and over 99% for dsDNA. Furthermore, the general applicability of the SP chromatography method was demonstrated with seven strains of influenza viruses recommended for seasonal influenza vaccine production, including H1N1, H3N2, B (Victoria), and B (Yamagata) strains, indicating that the SP process could be utilized as a platform process. The SP process developed in this study showed four advantages: (1) simple operation, (2) a high recovery rate for influenza viruses, (3) a high removal rate for major impurities, and (4) general applicability.

Continuous production of succinic acid from glycerol: A complete experimental and computational study

In this work, a bioprocess for the fermentation of A. succinogenes for the production of succinic acid from glycerol was developed, employing a continuous bioreactor with recycle. Moreover, a new bioprocess model was constructed, based on an existing double substrate limitation model, which was validated with experimental results for a range of operating parameters. The model was used to successfully predict the dynamics of the continuous fermentation process and was subsequently employed in optimisation studies to compute the optimal conditions, dilution rate, reflux rate and feed glycerol concentration, that maximise the productivity of bio-succinic acid. In addition, a Pareto front for optimal volumetric productivity and glycerol conversion combinations was computed. Maximum volumetric productivity of 0.518 g/L/h, was achieved at the optimal computed conditions, which were experimentally validated. This is the highest bio-succinic acid productivity reported so far, for such a continuous bioprocess.

Dynamical Simulation, Sensitivity, and Productivity Analysis of a Light-Photoacclimation Model for Microalgae-Based Carbohydrate Production in Continuous Photobioreactors

The world’s human population is increasing as is the demand for new sustainable sources of energy. Accordingly, microalgae-based carbohydrates for biofuel production are being considered as an alternative source of raw materials for producing biofuels. Microalgae grow in photobioreactors under constantly changing conditions. Models improve our understanding of microalgae growth. In this paper, a photoacclimated model for continuous microalgae cultures in photobioreactors was used to study the time-varying behavior and sensitivity of solutions under optimal productivity conditions. From the perspective of dynamic simulation in this work, light intensity was found to play an influential role in modifying metabolic pathways as a cell stressor. Enhancing carbohydrate productivity by combining nutritional deficiency and light intensity regulation modeling strategies could be helpful to optimize the process for the highest yield in large-scale cultivation systems. Under the proposed simulation conditions, a maximum carbohydrate productivity of 48.11 gCm−3d−1 was achieved using an optimal dilution rate of 0.2625 d−1 and 350 μmolm−2s−1 of light intensity. However, it is important to note that, a particular set of manipulated inputs can generate multiple outputs at a steady state. A numerical solution of the sensitivity functions indicated that the model outputs were especially sensitive to changes in parameters corresponding to a minimum nitrogen quota, maximum nitrogen intake rate, dilution rate, and maximum nitrogen quota compared to to other model parameters.

The effect of gallic acid on malondialdehyde, hydrogen peroxide and nitric oxide that influence viability of broiler blood cells at high ambient temperatures

ABSTRACT 1. The objective of this study was to measure the effect of gallic acid on levels of ferric reducing antioxidant power, malondialdehyde, hydrogen peroxide, nitric oxide and the viability of broiler blood cells (BBCs) when exposed to high ambient temperature. 2. The BBCs were maintained at 41.5°C (control group, CG) or at ambient temperatures ranging from 41.5°C to 46°C. At 41.5°C to 46°C, BBCs were diluted with gallic acid at 0 (positive control group, PCG), 6.25, 12.5, 25 and 50 µM, respectively. Ferric reducing antioxidant power, malondialdehyde, hydrogen peroxide, nitric oxide and viability of BBCs were investigated. 3. Hydrogen peroxide, malondialdehyde and nitric oxide for the CG was lower than PCG (P < 0.05). However, the viability of CG was higher than PCG (P < 0.05). At 41.5 to 46°C, malondialdehyde, hydrogen peroxide, and nitric oxide of BBCs diluted with gallic acid were lower compared to PCG (P < 0.05). Viability of BBCs diluted with gallic acid was higher than PCG (P < 0.05). 4. These results indicated that gallic acid could reduce the adverse oxidative effects of high ambient temperature on BBCs, with an optimum dilution rate of 12.5 µM.

Optimal production of microalgae in the presence of grazers

Zooplankton contamination represents a major constraint in large-scale microalgal cultivation systems. While zooplankton contamination cannot be avoided, their development can be controlled by regulating the dilution rate. However, it is not straightforward to find the best control strategy for the dilution rate. Low dilution rates (or long retention times) favor grazer development and high dilution rates avoid their establishment at the risk of reducing microalgal productivity. Furthermore, the presence of periodic regimes arising from the interaction predator–prey makes it unclear if the presence of grazers must be completely avoided. In this paper, we study the role of the dilution rate in the control of zooplankton populations and in the optimization of biomass productivity. We show that in the long-term operation (static optimal control problem or SOCP), the optimal constant dilution rate must ensure the eradication of the zooplankton population. In the case of time-varying dilution rate, we numerically solve an optimal control problem (OCP) over a finite interval of time. We find that the optimal solution approaches the solution for the SOCP most of the time, except when zooplankton actively avoid the pond outflow. Based on these results, we propose a simple sub-optimal feedback control that approximately matches the solution of the OCP when the initial concentration of grazers is low.

Improving Microalgal Biomass Productivity Using Weather-Forecast-Informed Operations.

The operation of microalgal cultivation systems, such as culture dilution associated with harvests, affects biomass productivity. However, the constantly changing incident light and ambient temperature in the outdoor environment make it difficult to determine the operational parameters that result in optimal biomass growth. To address this problem, we present a pond operation optimization tool that predicts biomass growth based on future weather conditions to identify the optimal dilution rate that maximizes biomass productivity. The concept was tested by comparing the biomass productivities of three dilution scenarios: standard batch cultivation (no dilution), fixed-rate dilution (harvest 60% of the culture every three days), and weather-forecast-informed dilution. In the weather-forecast-informed case, the culture was diluted daily, and the dilution ratio was optimized by the operation optimization tool according to the future 24 h weather condition. The results show that the weather-forecast-informed dilution improved the biomass productivity by 47% over the standard batch cultivation and 20% over the fixed-rate dilution case. These results demonstrate that the pond operation optimization tool could help pond operators to make decisions that maximize biomass growth in the field under ever-changing weather conditions.

Annual assessment of the wastewater treatment capacity of the microalga Scenedesmus almeriensis and optimisation of operational conditions

The depth of the culture and the dilution rate have a striking effect on the biomass productivity and the nutrient recovery capacity of microalgal cultures. The combination of culture depth and dilution rate that allows to maximise the performance of the system depends on environmental conditions. In the current study, a response surface methodology was used to explore the relationship between the two most relevant operational conditions and the biomass productivity achieved in 8.3 m2 pilot-scale raceways operated using urban wastewater. Four polynomial models were developed, one for each season of the year. The software predicted biomass productivities of 12.3, 25.6, 32.7, and 18.9 g·m−2·day−1 in winter, spring, summer, and autumn, respectively. The models were further validated at pilot-scale with R2 values ranging within 0.81 and 0.91, depending on the season. Lower culture depths had the advantage of minimising nitrification and stripping but allow to process a lower volume of wastewater per surface area. Biomass productivity was higher at culture depths of 0.05 m, when compared to 0.12 and 0.20 m, while the optimal dilution rate was season-dependent. Results reported herein are useful for optimising the biomass productivity of raceway reactors located outdoors throughout the year.

Enabling pseudo-ductility in geopolymer based glass-ceramics matrix composites by slurry dilution

Carbon fibre reinforced composites with matrix consisting of porous glass-ceramics obtained by high temperature heat-treatment of geopolymer based material are studied. The matrix is obtained from a slurry. Several composites have been manufactured by in-laboratory stratification of pre-impregnated plies with slurries diluted at various rates. Slurry dilution changes the porosity and leads to pseudo-ductile behaviour of the composite. Dilution implies a drop of non-linearity stress threshold together with a slower decrease of the strength. An optimal dilution rate is evidenced, which exhibits high strength but lower non-linearity stress threshold, and then, a significant failure strain. The optimized prepreg material is compared with a reference composite processed by an industrial prepreg process. The origin of the pseudo-ductility is related to decohesion at the interface between tows and inter-tow matrix. RTM also provides a pseudo-ductile composite but with very low non-linearity stress threshold, in relation to poorly impregnated tows.

Process maps and optimal processing windows based on three-dimensional morphological characteristics in laser directed energy deposition of Ni-based alloy

Constructing processing window to fabricate defect-free components with high forming quality and desired performance has been crucial in directed energy deposition. Due to its complexity as a mass and energy time-dependent system, it is still a key problem to be solved for laser powder-fed additive manufacturing to choose opportune processing parameters. In this paper, single scan track experiments were conducted under various combinations of processing parameters including laser power, scanning speed and powder feeding rate. Scan tracks had been thoroughly investigated through three-dimensional information including surface, longitudinal section and transverse section, which were correlated to each other in showing track morphological characteristics in directed energy deposition. Surface ripples, resembling fish scale in welding and chevron in selective laser melting, were found in directed energy deposition under low powder feeding rate and high linear energy density. Furthermore, several quantitative indexes, which were dimensionless mean roughness and ripples’ interval in surface, dimensional roughness in longitudinal section and dilution rate in transverse section, were used to evaluate the forming quality. These quantitative indexes were found to be closely related to the defects in additive manufacturing, and forming quality and accuracy of additive-manufactured components. Relationship between proposed indexes and processing parameters was studied and the mechanism behind it was also discussed. Five states which were no fusion, lack of fusion, optimum, rough surface and undesired dilution rate were distinguished based on the proposed quantitative indexes. Finally, a processing window based on these indexes was proposed for the laser powder-fed additive manufacturing for Inconel alloys. It is found that powder feeding rate affects the distribution of the five states and laser power, scanning speed affect the range of the five states.

Steady-state characteristics of a continuous-flow photobioreactor for neutral lipids synthesis by microalgae

The paper presents a mathematical model of a continuous-flow bioreactor in which cultivation of Pseudochlorococcum sp. algae proceeds. The process is directed on synthesis of neutral lipids, which are used for production of third-generation biodiesel. The model takes into account influence of light and nutrient limitation on the growth of microalgae. Numerical simulations were performed in order to determine steady-state properties of the bioreactor. The influence of key process parameters was investigated and detailed process interpretation was presented. Existence of optimal dilution rate and optimal influent nitrogen concentration was proved. In order to obtain maximum lipids productivity, lower dilution rate is required for higher influent inorganic nitrogen concentration. The factor limiting the process changes with the increase in the dilution rate. At low dilution rates the process is limited by nitrogen. At intermediate dilution rates the process is limited by light, whereas at high dilution rates the process is once again limited by nitrogen. Existence of a critical irradiance below which the biomass wash-out occurs was shown. The results presented are both of cognitive and practical importance.

Dynamics and productivity of microalgae in presence of predators

Abstract This paper is concerned with the dynamics and the productivity of biomass in a continuous microalgae culture contaminated by predators. We propose a general model describing a cultivation system where photolimited microalgae are grazed by zooplankton. We state necessary and sufficient conditions for the existence of a coexistence equilibrium. If this equilibrium exists, then microalgae and predators converge either to it or to a globally asymptotically stable periodic solution. In absence of the coexistence equilibrium, any solution approaches either an equilibrium characterized by the presence of algae and the absence of predators, or the washout equilibrium. This description of the dynamics allows to define the microalgae productivity in the long-term (i.e. when an attracting set is reached). With the help of numerical simulations, we show that operating the system at optimal (constant) dilution rate triggers the extinction of predators.

Effect of fed-batch and chemostat cultivation processes of C. glutamicum CP for L-leucine production

ABSTRACT Most of the current industrial processes for L-leucine production are based on fermentation, usually in fed-batch operation mode. Although the culture technology has advanced in recent decades, the process still has significant drawbacks. To solve these problems, we investigated the effects of chemostat culture conditions on the production of L-leucine by Corynebacterium glutamicum CP. The dilution rate, the nitrogen source, and the carbon–nitrogen ratio of the medium were optimized. With the addition of ammonium acetate to the chemostat medium, the initial C/N ratio was adjusted to 57.6, and the L-leucine titer reached the highest level at the optimal dilution rate of 0.04 h−1. Compared with fed-batch culture, the L-leucine titer was reduced (from 53.0 to 24.8 g L−1), but the yield from glucose was increased by 10.0% (from 0.30 to 0.33 mol mol−1) and productivity was increased by 58.3% (from 1.2 to 1.9 g L−1 h−1). Moreover, the titer of the by-product L-alanine was significantly reduced (from 8.9 to 0.8 g L−1). In addition, gene expression levels and activity of key enzymes in the synthesis of L-leucine and L-alanine were analyzed to explain the difference of production performance between chemostat culture and fed-batch culture. The results indicate that chemostat culture has great potential to increase the industrial production of L-leucine compared to current fed-batch approaches.

Design and characterization of FeCrCoAlMn0.5Mo0.1 high-entropy alloy coating by ultrasonic assisted laser cladding

In this work, FeCrCoAlMn 0.5 Mo 0.1 high-entropy alloy (HEA) coating was successfully synthesized on 316L stainless steel by ultrasonic assisted laser cladding. The effect of dilution rate on the phase composition of FeCrCoAlMn 0.5 Mo 0.1 coatings was investigated by thermodynamic calculation, solidification simulation and microstructure characterization. The mechanical properties, tribological behavior and corrosion resistance of FeCrCoAlMn 0.5 Mo 0.1 coating prepared under optimal dilution rate were also characterized in detail. The results show that the increase of dilution rate results in the transition of single solid solution (BCC) into dual-phase solid solution (FCC and BCC) of FeCrCoAlMn 0.5 Mo 0.1 coating. The TEM analysis reveals that FeCrCoAlMn 0.5 Mo 0.1 coating with optimal dilution rate (∼27.3%) is virtually composed of disordered BCC phase and ordered BCC (B2) phase. The spinodal decomposition structure and numerous dislocations were found in the grains. The average microhardness of FeCrCoAlMn 0.5 Mo 0.1 coating is ∼624.1 HV, which is more than 2.6 times higher than that of the substrate. The wear resistance of FeCrCoAlMn 0.5 Mo 0.1 coating was found significantly improved almost 4 times than that of 316L stainless steel. The passive current density of FeCrCoAlMn 0.5 Mo 0.1 coating is reduced by an order of magnitude compared with that of 316L stainless steel, proving the better corrosion resistance of FeCrCoAlMn 0.5 Mo 0.1 coating. • A new FeCrCoAlMn 0.5 Mo 0.1 HEA coating without defects was successfully prepared by ultrasonic assisted laser cladding. • Excessive dilution will result in phase transition of FeCrCoAlMn 0.5 Mo 0.1 HEA coating. • The spinodal decomposition structure and numerous dislocations are found in the coating. • FeCrCoAlMn 0.5 Mo 0.1 HEA coating shows good wear resistance and corrosion resistance.

Calidad y fertilidad del semen de conejo diluido con jugo de sandía.

Se diseñó un estudio para evaluar la idoneidad del jugo de sandía como diluyente del semen de conejo y la tasa de concepción conejos hembra inseminados. La sandía madura (Citrus lanatus) se obtuvo y procesó en jugo usando el procedimiento estándar. Para el ensayo se usaron un total de 10 conejo macho y 90 conejo hembra , todos de raza New Zealand White x Chinchilla. El semen se recolectó de los conejo macho utilizando una vagina artificial y se diluyó con jugo de sandía a una proporción 1: 0, 1: 0.25, 1: 0.67, 1: 1.5, 1: 4 o con solución salina normal 1:1; y se designó como T1, T2, T3, T4, T5 y T6 respectivamente. El análisis del semen se realizó en semen fresco y los diversos semen se diluyeron inmediatamente hasta 370C. Quince de cada uno fueron asignar al azar para el tratamiento diferente en un diseño completamente al azar y se inseminaron con su tratamiento respectivo utilizando el procedimiento estándar. La tasa de concepción, el tamaño de la camada y el índice de productividad al nacer se juzgado al final del período de gestación. El resultado obtenido reveló que el rango de valores obtenidos para la movilidad del espermatozoide, la integridad de la membrana estructural y la integridad del acrosoma está dentro de los valores aceptados para el semen de buena calidad. La tasa de concepción de inseminación con semen diluido con jugo de sandía a una proporción 1: 1.5 fue la tasa de dilución óptima con 75%. El tamaño de la camada fue significativamente (p

Continuous fermentation of recombinant Pichia pastoris Mut+ producing HBsAg: Optimizing dilution rate and determining strain-specific parameters

There is a growing interest in the biopharmaceutical industry to enhance production efficiency via shifting batch to continuous manufacturing. In the previous study, we demonstrated that under identical operation condition, continuous fermentation of recombinant Pichia pastoris (P. pastoris) Mut+ producing intracellular hepatitis B surface antigen (HBsAg) has considerably higher efficiency compared to the conventional fed-batch process. In the current work, by examining various dilution rates, we further optimized the process efficiency, and also determined some strain-specific parameters. According to the results, continuous operation at the dilution rate of 0.015 1/h demonstrated the highest performance compared to other dilution rates of 0.009, 0.02, 0.25, 0.03 and 0.0417 1/h. In the optimum dilution rate, the average HBsAg titer, yield, specific and volumetric productivity were 283.9mgHBsAg/L, 0.71mgHBsAg/g MeOH, 0.0097mgHBsAg/g wet cell weight (WCW)/h and 4.26mgHBsAg/L/h, respectively. Compared to the continuous fermentation in the previous study, the volumetric and specific productivities were improved by the factors of 2.0 and 2.5, respectively. Following Herbert-Pirt linear relation between specific growth rate and methanol consumption rate, the obtained biomass yield and maintenance coefficient in the continuous fermentation were 1.22 (g WCW/g MeOH) and 0.008 (g MeOH/g WCW/h), respectively. The consistency in the process condition and efficiency without any genetic instability and contamination in the one-month operation- in each fermentation run- suggests that the studied recombinant strain could be one of the potential candidates for continuous biomanufacturing of hepatitis B vaccine.

Potential of coconut water to enhance fresh semen quality and fertility in rabbits.

Coconut water as a natural diluent was evaluated on rabbit semen quality, conception and litter size in artificially inseminated does. A total of 10 bucks and 90 does, all crossbred New Zealand White × chinchilla, were used for the trial. Pooled semen was obtained from bucks using artificial vagina. Semen diluents were prepared at 0%, 20%, 40%, 60% and 80% and control 50% normal saline and designated as T1, T2, T3, T4, T5 and T6 respectively, in a completely randomised design. Semen analysis was conducted on fresh semen and the various diluted semen immediately at 37°C. Fifteen does each were randomly allotted to the different treatment and were inseminated with their respective treatment diluted semen using the standard procedure, and conception rate, litter size and productivity index at birth were assessed at kindling. Result obtained revealed that spermatozoa motility and structural membrane integrity of the diluted semen were significantly (p < 0.05) affected by the percentage of dilution. The range of values obtained for spermatozoa motility, structural membrane integrity and acrosome integrity is within the accepted values for good-quality semen. Conception rate, litter size and productivity index at birth were highest in does inseminate with T4 (60%), and the least values were obtained in T5 (80%). In conclusion, coconut water is a suitable diluent for rabbit semen for on-farm artificial insemination, the optimal dilution rate of coconut water in rabbit semen is 60%, which guarantees high conception, litter size and productivity index at birth.

Dehydration of crude oil by cellulose-based demulsifiers: statistical modeling, sensitivity analysis and optimization

In this research, demulsification performance of Ethoxylated coco-amine and Ethyl cellulose mixture is investigated at various concentrations. The efficiency of agents is formulated mathematically based on the central composite design (CCD) of response surface methodology (RSM) considering temperature, dilution rate, agent concentration, and pH as independent factors. Analysis of variance is performed to identify the importance of factors and interactions. Based on the developed model, the optimum operating conditions are determined via RSM considering dehydration efficiency as objective. The optimum temperature, dilution rate, agent concentration, and pH to achieve maximum performance are 79.3 °C, 9.97%, 854.4 ppm, and 7.65, respectively.