Agitation Intensity Research Articles

Evaluation of deep eutectic solvent pretreatment towards efficacy of enzymatic saccharification using multivariate analysis techniques

In this paper, deep eutectic solvent (DES) pretreatment of lignocellulosic biomass was analysed using principal component analysis (PCA) and partial least square (PLS) methods to determine correlations between the pretreatment process variables and assess their significance level. The analysis was conducted on the dataset containing 103 experimental observations and 32 variables. Both PCA and selected PLS model (M4) had substantial prediction power and prediction relevance, as exhibited by their good cumulative explained variance (R2cum, 0.787) and cumulative predicted variance (Q2cum, 0.524) for six principal components of PCA model, and explained variance of independent variable (R2Xcum, 0.781), explained variance of dependent variable (R2Ycum, 0.803) and cumulative predicted variance (Q2cum, 0.776) for the best PLS model. The results of PCA and PLS analyses revealed that the most significant variables for DES pretreatment were severity factor , temperature, type of antisolvent, particle size, agitation intensity and type of hydrogen bond donor (HBD) of the DES. The use of carboxylic acid and hydroxy acid HBD was associated with higher glucose yield and shorter duration of saccharification . The models also showed that enzymatic saccharification was more efficient when organic solvent or inorganic salt solution was used as antisolvent for lignocellulose regeneration. Usage of water as antisolvent was associated with reduced glucose yield during saccharification. Another notable outcome of this work was that intensive stirring during pretreatment had negative effect on glucose yield due to the shear thickening properties of DESs. This work provided a systematic analysis of DES pretreatment process of lignocellulosic biomass using PCA and PLS methods that allowed better understanding of the factors affecting the pretreatment process. • Multivariate analysis of PCA and PLS were used to study DES pretreatment. • The models had high predictive accuracy with good R2Xcum, R2Ycum, Q2cum values. • SF, antisolvent, particle size, agitation and HBD had great impact on pretreatment. • Long p-time, low t, AS (organic, inorganic), HBD (–COOH, –OH) favored pretreatment. • High agitation intensity and large particle size led to poor pretreatment.

Single cell protein production by Candida robusta isolated from sugar cane (Saccharum sp.) for animal feed / Produção de Biomassa por Candida robusta isolada da Cana-de-açúcar (Saccharum sp.) para alimentação animal

The protein obtained from the microorganisms is not only cheap but can be used as additive to provide a balanced nutrition for many animals feeding. The aim of this work was the single cell protein (SCP) production by Candida robusta URM5293 using sugarcane bagasse as substrate. The yeast C. robusta URM5293 was isolated from root sugarcane and was identified based on morphological and biochemical characteristics. Biomass production was done into Erlenmayers flasks (250 mL) containing culture medium supplemented of sugarcane bagasse hydrolyzate. Fermentations were carried varying culture conditions through the study of four different variables: temperature (25, 30, and 35°C), agitation intensity (110, 140 or 170 rpm), pH (6.0, 7.0, and 8.0) and production time (72, 96, and 120h), according to a 24-1 fractional factorial design. Results demonstrated that this yeast was able to ensure the highest level of biomass (141 g/L) when cultivated at 25°C, pH 6.0, 170 rpm of agitation intensity after 72h of cultivation using sugarcane bagasse. The present results demonstrate the potential of sugarcane bagasse hemicellulosic hydrolyzate as a substrate for the production of microbial protein by C. robusta URM5293.

Study on the aggregate motion for gas–liquid–solid agitated tank reactors design using radioactive particle tracking

This work provides a detailed study on the agitation rate influence on the solid motion within a pilot-scale slurry tank containing nickel oxide particle agglomerates suspended in iso-octane by the action of an axial impeller and slight bubbling nitrogen gas. The behaviour of a tracer particle representing solid aggregates is determined from radioactive particle tracking measurements with a spatial accuracy of ∼2 mm. An increase in the overall space occupied by the tracer is observed with increasing stirring speed. The instantaneous velocities, calculated by time differentiation of successive tracer positions, are significantly higher than the dynamic error. A measure based on the Reynolds stress as the turbulence level estimator is reliably mapped in three dimensions from the ensemble-averaged correlation matrix of the Lagrangian tracer velocity, enabling studying the influence of agitation on the turbulence levels distribution. This study offers an improved understanding of three-phase stirred reactors, which efficiencies are heavily coupled to complex fluid mechanics, especially in a turbulent flow. The axisymmetry is broken due to the presence of baffles. Incrementing the agitation intensity reduces the axial coherence of the thrust on the solid phase, raising turbulence levels, especially nearby the impeller tip.

Numerical Solution of the Problem of Filtering Estimates Information Impact on the Electorate

The formulation and numerical scheme for solving the problem of filtering estimates of the informational impact of mass media on the electorate, allowing with a high degree of accuracy at a given observation interval to estimate the number of individuals in society who prefer a certain political subject (opinion), are proposed in the article. A mathematical model for assessing the information impact on the electorate during election campaigns, which boils down to solving a stochastic differential equation – the equation of state, forms the basis of the formulation of the problem. When compiling a model for filtering information impact estimates, it is proposed to reduce the study of the equation of state to a numerical solution of the Duncan–Mortensen–Zakai equation by introducing an additional observation equation, which is obtained from the equation of state when evaluating its stochastic components (observed agitation intensities) by methods of polyspectral analysis. In the projection formulation of the Galerkin method, when reducing to a system of linear differential equations and obtaining its solution in a recursive estimation scheme when sampling the analysis interval into subintervals and using the matrix exponential method, the Duncan–Mortensen–Zakai equation is solved. For a visual comparison of the effectiveness of the generated numerical solution to the problem of filtering information impact assessments, calculations were carried out on test examples.

Effect of electrostatic forces on the dispersion of like-charged solid particles transported by homogeneous isotropic turbulence

The effect of electrostatic forces on the dispersion of small like-charged inertial particles transported by a homogeneous isotropic turbulent flow is analysed by means of direct numerical simulations coupled with the Lagrangian tracking of charged particles. The results show that particle dispersion decreases for increasing charge. Since turbulent particle dispersion is related to the intensity of particle agitation and to the Lagrangian particle integral time scale, we analyse the effects of electrostatic forces on these two quantities. Particle agitation decreases for increasing particle charge. In fact, particle kinetic energy is not directly modified by electrostatic forces, which are conservative, it is rather the particle entrainment by fluid turbulence that is modified. To support this claim, one shows that the fluid–particle velocity covariance is destructed by electrostatic forces, a destruction can be predicted by drawing an analogy between inter-particle collisions and Coulomb collisions. As expected, electrostatic forces decorrelate particle velocities leading to a decrease of the Lagrangian particle integral time scale. Finally, one shows that the analogy with inter-particle collisions allows us to predict the reduction of particle dispersion.

Optimization and production kinetics for cellulases by wild and mutant strain of Thermomyces dupontii in stirred tank reactor

The main bottleneck in fermentation technology is scaling up procedure of industrial enzymes according to the biological characteristics of the organism. The current study describes the production kinetics of cellulases in stirred tank reactor by using mutant and wild strains of T. dupontii. The fermentation span of both the strains in bioreactor was examined. It is was found in mutant strain of T. dupontii fermentation time required for optimum production was reduced to 48h as compared to 72h in wild strain. The kinetic studies also exhibited greater value of µ (h-1) in case of mutated strain in comparison with wild strain. The effects of some other critical factors like agitation intensity dissolve oxygen, aeration, temperature, size of inoculum and pH was estimated on enzyme production kinetics. The results shows maximum activity of cellulases was attained at 220 rpm, 15% dissolve oxygen, aeration rate 1.5 vvm, 55°C, 8 % inoculum size and pH 5.5 for both strains respectively. The higher values of enzyme production kinetics i.e. Yp/x, Qp, Qx and qp in STR in case of mutant strain indicates its superiority over wild strain of T. dupontii. Thus mutant thermophilic T. dupontii might be a potential candidate for industrial applications.

Algorithmic solutions to the problem of assessing the information impact on the electorate during election campaigns

In the article, to solve the problem of assessing the information impact on the electorate during election campaigns, algorithmic solutions, including a mathematical model, a numerical scheme and algorithmic implementations, are formed. This assessment is reduced to determining the instantaneous values of the number of voters who prefer a candidate (party), taking into account: the positive or negative stochastic nature of the impact of mass media; interpersonal interaction; two-step assimilation of information; the presence of a variety of mass media, social groups and a list of candidates. The mathematical model is based on a generalized model of information confrontation in a structured society and, with the introduction of stochastic components in the intensity of agitation, it is reduced to solving the FokkerPlanckKolmogorov equation. For its study in the formulation of the Galerkin method, a numerical scheme is proposed and the order of its convergence is determined. In relation to the basic procedures of the numerical scheme, the features of the algorithmic implementation are clarified.

Effect of Bath Agitation on the Transient Cooling by Quenching Process

Abstract During the quenching process, the liquid bath is usually agitated to homogenize the temperature and to enhance convective heat transfer. The purpose of this paper is to characterize on the one hand the agitation of a water bath due to the movement of a three-blade turbine and on the other, the cooling of an Inconel 718 part being quenched in a stirred water bath. Velocity measurements were taken by particle image velocimetry (PIV) with and without the metallic part. We found that the velocity field became purely axial when we were far enough away from the turbine. Moreover, a high turbulent mixing level was shown for this type of jet. Velocity measurements were carried out for two agitation intensities. The axial velocity amplitude, as well as the turbulent kinetic energy, decreased dramatically as the rotational speed of the propeller decreased from 410 to 100 rpm. This caused the thermal behavior of the part to differ during quenching. Indeed, we found that the part cooled faster under stronger agitation. During the film boiling and transition phases, no appreciable effect of agitation could be observed. However, from the middle of the nucleate boiling phase, the part-bath heat transfer coefficient was found to decrease much less rapidly with the surface temperature if agitation was strong than if it was weak or if the bath was completely calm. In such a case of strong agitation, both nucleate boiling and convection concomitantly ensure part cooling.

58.4 PSYCHOPHARMACOLOGY REVIEW AND SAFETY PLANNING FOR AUTISM SPECTRUM DISORDER YOUTH WITH IMPULSIVE AGGRESSION

Children and adolescents with autism spectrum disorder (ASD) are often referred for mood dysregulation, aggression, and other maladaptive behaviors. Safety concerns create urgency for safe and effective pharmacotherapy and behavioral interventions. When comorbid conditions (eg, intellectual disability, mood disorders, psychosis, and ADHD) are present, pharmacological interventions are often complex and complicated by parental fears, medication interactions, and side effects. Participants will: 1) review research on pharmacological interventions that may reduce frequency and intensity of acute agitation, self-injurious behaviors, irritability, and impulsive aggression in youth with ASD; 2) learn strategies to manage safety during outpatient visits with youth with ASD; and 3) learn prescribing options when treating patients with ASD and co-occurring conditions that may be complicating the presentation. Therapeutic strategies to target maladaptive behaviors will be presented. Evidence from a PubMed review of literature to manage irritability and impulsive aggression in ASD will be reviewed. Strong evidence supports the use of atypical antipsychotics for severe irritability and aggression in ASD. However, there are limited randomized, placebo-controlled trials in other areas of impairment for ASD. Evidence for pharmacological interventions used to treat comorbid conditions (anxiety, bipolar disorder, mood instability, and ADHD) in this population will be presented. Limited evidence for novel agents (N-acetylcysteine, D-cycloserine, arbaclofen, cannabidiol oil, and naltrexone) will also be reviewed. Attendees will review recent literature on pharmacologic interventions to address mood dysregulation and impulsive aggression in youth with ASD. They will learn to develop a rational treatment plan based on treating the most serious presenting symptoms. As rates of ASD diagnosis continue to increase, it is essential for clinicians to be aware of current research to provide appropriate pharmacologic interventions. Caregiver stress for youth with ASD can be diminished when there is decreased frequency and intensity of aggression, mood dysregulation, and other maladaptive behaviors.

Automated Compartment Model Development Based on Data from Flow-Following Sensor Devices

Due to the heterogeneous nature of large-scale fermentation processes they cannot be modelled as ideally mixed reactors, and therefore flow models are necessary to accurately represent the processes. Computational fluid dynamics (CFD) is used more and more to derive flow fields for the modelling of bioprocesses, but the computational demands associated with simulation of multiphase systems with biokinetics still limits their wide applicability. Hence, a demand for simpler flow models persists. In this study, an approach to develop data-based flow models in the form of compartment models is presented, which utilizes axial-flow rates obtained from flow-following sensor devices in combination with a proposed procedure for automatic zoning of volume. The approach requires little experimental effort and eliminates the necessity for computational determination of inter-compartmental flow rates and manual zoning. The concept has been demonstrated in a 580 L stirred vessel, of which models have been developed for two types of impellers with varying agitation intensities. The sensor device measurements were corroborated by CFD simulations, and the performance of the developed compartment models was evaluated by comparing predicted mixing times with experimentally determined mixing times. The data-based compartment models predicted the mixing times for all examined conditions with relative errors in the range of 3–27%. The deviations were ascribed to limitations in the flow-following behavior of the sensor devices, whose sizes were relatively large compared to the examined system. The approach provides a versatile and automated flow modelling platform which can be applied to large-scale bioreactors.

Ammoniacal leaching process for the selective recovery of value metals from waste lithium-ion batteries

ABSTRACT The recovery of valuable metals in spent lithium-ion batteries (LIBs) is not only environmentally sustainable but also economically advantageous. In this research, ammoniacal leaching process was adopted to selectively extract valuable metals from the mixed types of cathode active materials. By employing the ammonium sulphite as the reductant, while the ammonia and ammonium carbonate are used to provide NH3 to complex metal elements. The Eh–pH diagrams were used to study the extraction behaviour of Co, Li, Ni and Mn during ammoniacal leaching, and the Co, Ni can be leached out as the complexes ([Ni(NH3) n ]2+, [Co(NH3) m ]2+), while the Li was leached out as metallic ion. Manganese is first leached out as [Mn(NH3)β]2+ and then precipitated as (NH4)2Mn(SO3)2·H2O and (NH4)2Mn(SO4)3 when an excess of ammonium sulphites added to the solution. A detailed understanding of the ammoniacal selective leaching process is carried out by investigating the effects of factors such as reaction temperature (50–90 ℃), leaching time (2–6 h), agitation intensity (400–900 rpm) and solid-to-liquid ratio (10–50 g/L). The experiment of response surface methodology shows that significant interactions exist between ammonium sulphite and ammonium carbonate, ammonium sulphite and ammonia according to the leaching efficiency of Co. Under the optimum conditions, Co, Li, Ni, Mn and Al can be leached out with the efficiencies of 84.56%, 90.31%, 64.13%, 4.53% and 1.72%, respectively. The results proved the possibility of selective leaching. Summarily, this research is potentially beneficial for the design of a selective recycling technique.

Behavior of Pantaneiro ewes and their offspring

The objective was to describe the behavior of Pantaneiro ewes and their lambs during the peripartum and to correlate these behavioral characteristics with the maternal behavior score (MBS) and productive characteristics of the lambs until weaning. During 2 years, on paddocks with Brachiaria brizantha pasture, 288 ewes aged of 3.5 ± 1.5 years and weighing 41.3 ± 8.1 kg were evaluated. Ewes were sired to Pantaneiro rams and to Morada Nova or Santa Inês rams. The characteristics observed were separation of the parturient ewe from the flock, agitation intensity, care for the lamb, nursing facilitation, latency of the first attempt of the lamb to stand up and suckle, vocalizations, sex of the lamb, weight at birth (BW) and weaning (WW), and the type of delivery. MBS was assessed approximately 12 hours after delivery, using a 6-point scale (1 = very poor and 6 = very good). Data were submitted to descriptive, univariate variance and principal factor analysis (PFA). Linear correlations were tested between behavior of animals at lambing and the lamb's productive indexes. Most ewes did not separate from the flock to deliver (74%), showed adequate maternal behavior as they facilitated the first suckling (86%) and kept close to their offspring (92%), presenting high MBS (≥4). Pantaneiro-sired lambs spent less time searching for the udder and sucking compared with crossbred lambs. Three principal factors (PF) with eigenvalues ≥1.0 explained 68.7% of the total variance for the ewes’ behavior at lambing. Latency to vocalize and latency to care for the lambs were positively associated, while they were negatively associated with ingestion of amniotic fluid and placenta. Agitation intensity at lambing was positively associated with separation from the flock. Three PF with eigenvalues ≥1.0 explained 63.0% of the total variance for the lambs’ behavior at lambing. The PFA evidenced positive association between the latencies to vocalize, stand up, search for the udder and suck, females and heavier animals presented lower durations of latency. Most ewes showed low reactivity to the human presence, but MBS did not correlate with behavior at lambing. The WW and the body weight gain of the lambs correlated positively only with the agitation intensity of the ewes. Behavior of Pantaneiro ewes at lambing is influenced by management and environment of Pantanal region, as ewes do not separate from the flock. In general, behavior of ewes at peripartum does not correlate with MBS and lambs's performance at weaning.

НИЗКОРАЗМЕРНЫЕ СТРУКТУРЫ БЛАГОРОДНЫХ И ЦВЕТНЫХ МЕТАЛЛОВ И МЕТОДЫ ИХ СЕЛЕКТИВНОЙ СЕПАРАЦИИ

There is a worldwide trend of increasing the share of extraction and processing of low-grade minerals, but their extraction and processing volumes are still low. There are several reasons for this: high mining and transportation costs, imperfect techniques and technological difficulties in enrichment and processing of refractory and low-quality minerals. Due to the depletion of reserves of easily beneficiated raw materials and to compensate for the growing shortage of high-quality minerals, the Russian mining industry development strategy provides for the involvement of new and unconventional types of deposits into production. Examples of such deposits are deposits of carbonaceous raw materials (black shale, refractory sulphide carbon-bearing ores, impactites, etc.) containing carbon of varying degrees of metamorphism. On the basis of the most modern mineralogical, physical, nuclear and chemical methods of research of composition, structure and properties of the carbonaceous raw materials at the micro- and nanolevel, the composition of the productive mineral matter, physical, chemical and thermodynamic laws of separation of valuable mineral components and the basic technological processes to obtain the finished product for valorization of the unconventional carbonaceous mineral raw materials were determined with maximum reliability. One of the possible reasons of difficulty of beneficiation of carbonaceous raw materials is the fine phenocrysts in graphite which can be solved by using the flotation process. Contrast of surface properties of minerals with similar technological properties can be increased by application of different energy effects (MEMI, MIO, microwave, electrochemical treatment etc.) at successive stages of raw material transformation, regulation of pulp conditioning conditions (duration and intensity of agitation, heat treatment of pulp) as well as by development and application of selective reagent regimes. The special feature of flotation as a method of extraction of noble and rare metals is the ability to extract valuable metals not only in their native free form, but also in close association with sulphides and carbon. Flotation with the use of intensifying influences made it possible to transfereven low-sized structures of noble and rare metals, which are not extracted by conventional methods of cyanidation, gravitation enrichment and amalgamation, into the concentrate. One of the ways to increase the efficiency of the flotation process is preliminary modification of the additive which is introduced in addition to the main reagents of the sinter - “carrier material”.

Gel Strength of Hydrophilic Matrix Tablets in Terms of In Vitro Robustness

PurposeThe purpose of this study was to correlate the gel strength of swollen matrix tablets with their in vitro robustness against agitation intensity and applied mechanical forces. Five commercial products, i.e. Glucophage®, Alfuzosin®, Tromphyllin®, Preductal® MR and Quetiapin® formulated as water-soluble/erodible matrix tablets were investigated.MethodsEffect of agitation speed (50–150 rpm) on drug release, hydration/erosion and gel strength was investigated using USP paddle apparatus II. The gel strength of matrix tablets during dissolution at different conditions was characterized by a texture analyzer.ResultsCommercial tablets formulated with HPMC of higher viscosity, such as K15M or K100M, demonstrated the gel strength in swollen state >0.02 MPa. In this case, the release mechanism was predominantly diffusional and, therefore, not affected by stirring speed and mechanical stress. In contrast, the Quetiapin® matrix tablet, formulated with HPMC K 4 M in amount of approx. 25%, demonstrated the gel strength dropped below 0.02 MPa after 6 h of release. In this case, the drug was predominantly released via erosional mechanism and very susceptible to stirring speed.ConclusionSufficient gel strength of swollen tablets is an important prerequisite for unchanged in vitro performance in consideration of mechanical stress.

Correlation between the emulsion oligomerization parameters for C9 fraction and the characteristics of hydrocarbon resins

This paper investigates the production of hydrocarbon resins by emulsion oligomerization of the С9 fraction hydrocarbons in liquid by-products of oil refining. Such oligomers have a wide range of applications as film-forming agents in paints and anti-color coatings. Emulsion oligomerization was carried out using emulsifiers of the first and second kind. The study was performed at different values of the reaction temperature of the reaction duration, the intensity of agitation; concentrations of the emulsifier; С9:water fraction ratio. The resulting products were estimated according to the following indicators: the yield, unsaturation degree, softening temperature, mean molecular weight, color. Statistical analysis was carried out, the correlation of parameters of emulsion oligomerization and the yield and characteristics of oligomers was established. Given that, it would be possible to establish the optimal conditions for emulsion oligomerization and predict the properties of the products obtained. Specifically, it was established that the yield of hydrocarbon resins does not correlate with the reaction temperature (0.15 and 0.30) and the concentration of emulsifiers (0.08 and 0.03). It was proven that in the intervals studied the variable yield of oligomers depends on the duration of the reaction (correlation 0.88 and 0.81). In the case of oligomerization in the reverse emulsion, a significant correlation with the yield is also demonstrated by agitation intensity (0.51) and a С9:water fraction ratio (0.51). That has made it possible to derive an equation of the yield multiple linear regression dependent on the most significant process parameters. The high values of the yield and bromine number correlation (0.94 and 0.93) give grounds to argue about the progress of oligomerization reaction. The relationship among the characteristics of oligomers has been confirmed. This indicates the possibility of directed adjustment of certain characteristics of hydrocarbon resins.

Motility Response to Hydrodynamic Stress During the Growth Cycle in Active Fluid Suspensions

Abstract In this work, we focus on the motility behavior of two model micro-organisms widely used in the study of active fluids: Chlamydomonas reinhardtii micro-alga and Synechocystis sp. cyanobacterium. Understanding the physiological responses of micro-organisms under variable environmental conditions is essential for bioreactor engineering. Yet, most of the previous studies focused on the observation of cellular motility regardless of the growth process. Here, we measure the motility of Chlamydomonas reinhardtii and Synechocystis sp. during their growth when subjected to different intensities of hydrodynamic shear stress. The results demonstrate a significant difference in the motility response of the two species against the applied hydrodynamic shear stress. Mechanical agitation appears to affect the motility of Chlamydomonas reinhardtii micro-algae by stimulating the growth process and increasing the magnitude of the cellular swimming velocity. This effect is described using an empirical model for the time variation of the motility. Synechocystis cells show a high endurance to the applied shear such that the global effect of agitation intensity on their motility is insignificant. However, it seems that the peak of the swimming velocity always occurs in the middle of exponential phase of growth.

Optimised transesterification of used frying oils: production and characterisation of biodiesel

ABSTRACT To compete with the growing energy demands, it is necessary to explore some new alternative sources of energy. Presently, biodiesel is being acknowledged for its environmentally friendly and renewable nature. In order to avoid fuel versus fuel problem, biodiesel can be made by using low-cost feedstocks such as non-conventional seed oils (Jatropha, Karanja and Castor), discarded and repeated fried/used frying oils. This work is targeted towards production of biodiesel from used frying oils collected from local frying outlets. Alkali-catalysed transesterification reaction was applied to make biodiesel through optimisation of different reaction variables with glycerine as the byproduct. Optimised conditions/reaction variables such as catalyst type and concentration, methanol/oil molar ratio, reaction temperature and agitation intensity yielded good quality and high percentage yield of biodiesel. The optimum parameters for biodiesel production were observed as 9:1 molar ratio of methanol/used frying oil, 1.5% KOH by wt. of oil, 60°C reaction temperature and 600 rpm agitation intensity. GC-MS and FTIR analysis of the produced used frying oil methyl esters (UFOMEs) confirmed the complete conversion of oil into biodiesel. The biodiesel fuel properties like density, flash point, kinematic viscosity, cloud point, pour point were determined and found comparable with American (ASTM D6751) and European (EN 14214) standard methods. From the results, it can be concluded that low cost of used frying oil as raw material was observed to be the most important aspect for economic viability of biodiesel production using such feedstocks.

A Review of Novel Drug Delivery Controlled Porosity Osmotic Pump Tablets Therapeutic Approach and Future Trend

The review work is comprised the enhancement of bioavailability and increase therapeutic efficacy. The porous osmotic pump tablets were designed using D‐Optimal design and numerical optimization technique was applied to find out the best formulation. Another hand an osmotic pump (OP) were designed and evaluated with the aim to deliver drug in a controlled manner. Osmotic agent and pore former was considered as independent variables. Drug release rate at 2 h, 4 h, 8 h, 12 h, T50% and release exponent (n) were taken as responses. The increase in concentration of pore former and osmotic agent after a limit, changes the release was measured. The optimized formulation follows mechanism measured. The FT‐IR and DSC studies revealed that no physicochemical interaction between excipients and drug. The influence of pH and agitation intensity on the release of drug was studied and the release mechanism was through osmosis. Stability studies revealed that optimized formulation was stable. The result of D‐ Optimal design and ANOVA studies reveals that osmotic agent and pore former have significant effect on the drug release up to 12 h. The observed independent variables were found to be very close to predicted values of most satisfactory formulation which demonstrates the feasibility.
 Keywords: osmotic pump, pore former, bioavailability

Electrocoagulation reduces harvesting costs for microalgae

Centrifugation is the most commonly used method for harvesting autotrophically produced microalgae, but it is expensive due to high energy demands. With the aim of reducing these costs, we tested electrocoagulation with iron electrodes for harvesting Chlorella vulgaris. During extensive lab-scale experiments, the following factors were studied to achieve a high harvesting efficiency and a low iron content in the harvested biomass: electric charge, initial biomass concentration, pH, temperature, agitation intensity, residual salt content and electrolysis time. A harvesting efficiency greater than 95% was achieved over a broad range of conditions and the residual iron content in the biomass complied with legislative requirements for food. Using electrocoagulation as the pre-concentration step prior to centrifugation, total energy costs were reduced to 0.136 kWh/kg of dry biomass, which is less than 14% of that for centrifugation alone. Our data show that electrocoagulation is a suitable and cost-effective method for harvesting microalgae.

Critical Factors for Metformin Osmotic Controlled Release Pump

Aim: Studied the critical factors in the design of an osmotic pump with metformin release rate constant at 4%/hr in diabetes mellitus within 24 hr. with the goal to reduce daily medications.
 Study Design: Experimental design 32
 Methodology: In vitro drug release profiles for 24h. The effects of different formulation variables, that is, concentration of hydrophilic polymer, diameter of drug releasing orifice and coating thickness, on the drug release profile were investigated. Also, the impact of pH, osmotic pressure and morphology with stereo microscopy and scanning electronic microscopy of the osmotic pumps were investigated. At last, osmotic pumps surface was analyze with scanning electronic microscopy.
 Results: Metformin osmotic pump were successfully prepared in this study to overcome the weak point of multiple doses and great concentration fluctuation of metformin. The formulation determined finally have a release orifice of 700 mm and 3.0% of weight gain, achieved the desired effect which can realize the constant drug release rate at the first 24 hr.
 Conclusion: The developed osmotic systems have a linear release near 4%/hr. and demonstrated that the behavior was independent of the agitation intensity and the pH of the gastrointestinal apparatus.