With the ever-increasing clinical application of cell-based therapies, it is considered critical to develop systems that facilitate the storage and distribution of cell therapy products (CTPs) between sites of manufacture and the clinic. For such systems to be realized, it is essential that downstream bioprocessing strategies be established that are scalable, reproducible and do not influence the viability or function of the living biologic. To this end, we examined alginate-encapsulation as a method to heighten the preservation of human adipose-derived stem cells (hASCs) during hypothermic storage, and establish a scalable process for high-volume production. A drop-wise method for scalable alginate bead generation, using calcium as the cross-linker, was modified to enable the yield of up to 3500 gelled beads per minute. The effect of alginate concentration on the viscosity of non-gelled sodium alginate and the mechanical properties and internal structure of calcium-crosslinked alginate in response to different alginate and calcium concentrations were investigated. Mechanical strength was chiefly dependent on alginate concentration and 1.2% alginate cross-linked with 100mM calcium chloride could withstand stress in the order of 35 kPa. Upon selection of appropriate parameters, we demonstrated the suitability of using this method for immobilizing human stem cells. Encapsulated hASCs demonstrated no loss in cell viability, and had a uniform distribution after high-volume production. Following storage, released cells were able to attach and recover a normal morphology upon return to culture conditions. Thus we present a scalable method for stem cell encapsulation and storage for application within the cell therapy supply chain. (C) 2016 The Authors. Published by Elsevier Ltd.

Current targets in reducing CO2 and other greenhouse gases as well as fossil fuel depletion have promoted the research for alternatives to petroleum-based fuels. Pyrolysis oil (PO) from biomass and waste oil is seen as a method to reduce life-cycle CO2, broaden the energy mix and increase the use of renewable fuels. The abundancy and low prices of feedstock have attracted the attention of biomass pyrolysis in order to obtain energy-dense products. Research has been carried out in optimising the pyrolysis process, finding efficient ways to convert the waste to energy. However, the pyrolysis products have a high content in water, high viscosity and high corrosiveness which makes them unsuitable for engine combustion. Upgrading processes such as gasification, trans-esterification or hydro-deoxynegation are then needed. These processes are normally costly and require high energy input. Thus, emulsification in fossil fuels or alcohols is being used as an alternative. In this research work, the feasibility of using PO-diesel emulsion in a single-cylinder diesel engine has been investigated. In-cylinder pressure, regulated gaseous emissions, particulate matter, fuel consumption and lubricity analysis reported. The tests were carried out of a stable non-corrosive wood pyrolysis product produced by Future Blends Ltd of Milton Park, Oxfordshire, UK. The product is trademarked by FBL, and is a stabilized fraction of raw pyrolysis oil produced in a process for which the patent is pending. The results show an increase in gaseous emissions, fuel consumption and a reduction in soot. The combustion was delayed with the emulsified fuel and a high variability was observed during engine operation.

The commercial production of vanillin from sodium lignosulfonate under highly alkaline conditions, catalyzed by Cu2+ at elevated temperature and pressures up to similar to 10 bar, has been simulated in a 3-L stirred reactor. Initially, the process was operated in the presence of nitrogen in dead-end mode, and it was shown that vanillin and vanillic acid were formed by hydrolysis at temperatures of 120, 140, and 160 degrees C. At the two higher temperatures, the amount of vanillin produced was the same. Subsequently, experiments were conducted at the same elevated pressures and temperatures with addition of air or oxygen enriched air once the temperature in the reactor had reached temperatures similar to those used when only hydrolysis occurred. In this case, the concentration of vanillin at 140 and 160 degrees C was equal to that due to hydrolysis, and the subsequent 2-fold increase was due to oxidation. In addition, both vanillic acid and acetovanillone (which has rarely been reported) were produced, as was hydrogen. Thus, for the first time, it has been shown that the production of vanillin (and other compounds) from sodium lignosulfonate at elevated temperatures involves hydrolysis and oxidation, with hydrolysis starting at just above 100 degrees C, that is, much lower than has previously been reported. Approximately 50% is produced by each mechanism. In addition, the orders of the reactions of the different steps were estimated, and the reaction mechanisms are discussed.

The production of vanillin from sodium lignosulfonate under highly alkaline conditions, catalyzed by Cu2+ and at elevated temperature and pressures, has been studied in two sizes of stirred reactors. The larger reactor (3 L) was operated in both the dead end and the gas throughflow modes; the sparged gas was nitrogen and "simulated air" in the former case and air in the latter. The smaller reactor (300 mL) was only operated in the batch mode with oxygen. In the 3 L reactor, with nitrogen gas alone in the dead end mode, vanillin was produced by hydrolysis. With the other conditions, both hydrolysis and oxidation occurred and the amount of vanillin produced was greater. In addition, for the first time since this process was first introduced in 1936, the composition of the gas phase produced by the reaction was investigated, too. The measurements were made on samples taken from the headspace of the 300 mL batch reactor and the headspace of the 3 L reactor in the dead end mode and in the exhaust gases in the throughflow mode. It was found that, whenever vanillin was produced, hydrogen was detected in the gas phase. In the 3 L reactor in the dead end mode, the amount of H-2 formed was so great (similar to 7% by volume) in the case of "simulated air" that the production of vanillin ceased as no further air (oxygen) was able to enter the reactor. In the throughflow mode, the concentration of hydrogen detected in the exit gas was much lower as it was flushed out in the exhaust. As a result of the different levels of oxygen and hydrogen in the reactor in the dead end and throughflow modes, the amount of vanillin produced was greater in the latter case. Thus, it is difficult to use studies in the dead end mode to predict the behavior in throughflow, the mode generally used industrially.

The effect of power input, solid content, surfactant concentration, and pH on the kinetics of wet deagglomeration of hematite nanopowder in ultrasonic comminution device and on the rheology of resulting suspensions has been investigated and compared with the kinetics of deagglomeration and rheology of the suspensions of goethite nanopowder. It has been found that the main mechanisms are fragmentation and erosion, which leads to bimodal transient size distributions of aggregates. Fragmentation of large aggregates starts after certain delay time but erosion of nanoparticles starts from very beginning of processing. Deaggregation of hematite nanopowder is only possible in the presence of surfactant, but increase of concentration of surfactant above certain critical value does not affect kinetics of deagglomeration. The increase of solid concentration up to 20 w / w % reduces the amount of energy necessary for deagglomeration of unit mass of the powder. Effect of pH on the kinetics of deagglomeration and the morphology/rheology of the resulting suspensions is discussed. © 2009 American Institute of Chemical Engineers AIChE J, 2009

The effect of energy density, pH and solid concentration on kinetics of de-agglomeration of hydrophobic silica nano-powder in a high shear mixer and on the rheology of resulting suspensions was investigated and compared with de-agglomeration kinetics and rheology of the suspension of hydrophilic silica nano-powder. In both types of nano-powders large aggregates were broken by fracture and erosion. In hydrophobic nano-powder erosion was more pronounced whilst in hydrophilic nano-powder erosion followed initial fracture of large aggregates. At sufficiently high energy input both hydrophobic and hydrophilic aggregates were broken into nano-aggregates but, even at the highest energy input, those nano-aggregates could not have been broken into single nano-particles. Rheology of the suspensions of hydrophobic nano-aggregates strongly depends on pH and on solid concentration whilst rheology of suspensions of hydrophilic nano-powder is rather weakly dependent on those parameters.

Effect of chemical composition and applied strain on mechanical properties of gelled gelatin-rich micro-particles resulting from phase separated gelatin/pullulan mixtures has been investigated. The mechanical properties of micro-particles (20–120μm) were measured using a micromanipulation technique. The compress–release tests revealed that at a low deformation (up to 10% strain) particles are fully elastic with Young’s modulus proportional to the concentration of gelatin and at the higher deformation (up to 50–80%) particles are visco-elastic. Even at very high load resulting in 50–60% deformation, no fracture of particles was observed and after the load was removed, particles recovered to a fully spherical shape. The visco-elastic behaviour was investigated by a stress-relaxation method, where force relaxation at constant deformation was measured as a function of time. The experimental results were analysed using a standard liner model of visco-elastic solids and the parameters of this model were related to the composition of gelled particles.

The effect of power input, solid content and ionic strength of liquid on the kinetics of de-agglomeration of acicular goethite nano-particles in ultrasonic comminution device has been investigated. It has been found that the pattern of de-agglomeration is independent of power input. Initially large aggregates are broken by fragmentation and as the process progresses the primary particles are gradually eroded from the surface of those large aggregates. The breakage of large aggregates was described by size-energy model and the model describing the generation of primary particles was developed. The increase of solid concentrations in the suspension (up to 20 wt.%) leads to an increase of the efficiency of both breakage of large aggregates and formation of fine particles. The ionic strength and solid concentration have practically no effect on mechanism of de-agglomeration but they affect the morphology and rheology of the suspensions of goethite nano-powder. (C) 2008 Elsevier B.V. All rights reserved.

The effect of the type of surfactant and pH on de-agglomeration of a hydrophilic silica nanopowder in a high shear mixer was investigated. It has been found that the presence of surfactant does not affect the general pattern of de-agglomeration characterized by the transition of a single modal aggregates size distribution with the median of 10 mu m, through a bi-modal distributions with the second median of the order of 100 run to a single modal distribution with the median of the order of 100 run. None of the investigated surfactants enabled de-agglomeration of the nano-powder into a primary nanoparticle.

The kinetics of deagglomeration in diluted suspensions of goethite nanopowder, as well as the rheology and morphology of the resulting suspensions, strongly depends on pH. At pH 3, nanopowder can be dispersed as separate nanoparticles, and the resulting suspension is Newtonian, with the viscosity only marginally higher than the viscosity of water. At pH between 5 and 12, nanoparticles tend to reaggregate and form weak aggregates/flocs. Morphology changes from a Newtonian suspension of primary nanoparticles to a non-Newtonian, shear-thinning suspension of large, porous, interconnected flocs with the yield stress reaching a maximum at an isoelectric point. The effect of pH on morphology and rheology is reversible, and as pH is reduced to 3, the suspension becomes Newtonian, with viscosity marginally higher than the viscosity of water. The rheological models based on DLVO theory do not allow prediction of the effect of pH on viscosity and yield stress, but the flow curves of goethite suspensions can be described by a fractal model with five adjustable parameters.

The current study offers a first insight into the interfacial properties of pullulan–sodium dodecyl sulphate (SDS) aqueous two-phase systems (ATPS) in the presence of sodium chloride (NaCl). The effect of composition on the interfacial tension (σ) in these ATPS was investigated over a wide range of pullulan, SDS and NaCl concentrations. An increase in the interfacial tension was observed with increasing pullulan and SDS concentrations and a small increase was also observed as the NaCl concentration was increased. In both cases the interfacial tension increases were closely related to the phase behaviour of these systems; as a consequence of increasing the pullulan, SDS and/or NaCl concentrations, the system moves further away from the critical point. In all systems interfacial tensions (of the order of μN/m) were comparable with those reported for polymer–polymer ATPS. Interfacial tensions σ can be well correlated with the difference in pullulan and SDS concentrations between the phases (ΔCpul and ΔCSDS) and also the tie-line length (TLL); all yield straight lines on a log–log scale.

The effect of energy input, pH and temperature on de-aggregation of hydrophilic silicon dioxide powder (particle size 12 nm) in a high shear mixer was investigated. It has been found that de-aggregation is a two step process. Initially, at low energy input very large aggregates (3-1000 mu m) are gradually broken into smaller secondary aggregates (2-100 mu m) of a single modal size distributions. As the energy input increases primary aggregates (0.03-1 mu m) are eroded from the secondary aggregates leading to bimodal size distributions with the first mode between 0.03 mu m and 1 mu m corresponding to the primary aggregates and the second mode between 2 mu m and 100 mu m corresponding to the secondary aggregates. At a sufficiently high energy density all secondary aggregates are broken into primary aggregates however, even at the highest energy density employed the primary aggregates could not be broken into single nano-particles. The temperature and the pH affect deaggregation kinetics but do not alter de-aggregation pattern. Increasing pH at low temperature speeds up de-aggregation, whilst increasing pH at high temperature slows down de-aggregation process. (c) 2007 Elsevier B.V. All rights reserved.

A process for the manufacture of chemically produced toner (CPT) has been analyzed using model materials. In part 1 of this two-part paper, the impact of pH and temperature in a Couette-type rheometer and in a combination of two mechanically agitated systems with recirculation between them is reported. The initially stable 100 nm latex suspension at pH approximate to 9 was destabilized by the addition of acid accompanied by vigorous agitation. This destabilization led to the formation of primary aggregates of the original latex suspension of similar to 1-2 mu m which, at pH < 4, themselves aggregated to give a closely packed paste or gellike structure. This rheologically complex structure had a Yield stress and exhibited internal slippage between primary aggregates at certain shearing conditions. The gel was broken by heating to above T-g, the glass-transition temperature, leading to the reformation of aggregates of the primary 1-2 mu m latex aggregates of similar to 6-12 mu m, which could be stabilized by raising the pH again to similar to 7. The final near-spherical model CPT product was obtained by heating the 6-12 mu m aggregates to >> T-g to cause internal coalescence. These changes of rheological property and structure and the physicochemical reasons for them are reported in detail.

In part 1 of this two part paper, the impact of pH and temperature on structure and rheological properties at the various process steps of the model CPT manufacture were reported. Part 2 uses temperature and pH values established in part I and concentrates on the impact of agitation conditions on the CPT product and their implications for scale-up. It is seen that the main drivers for the process are pH and temperature, but if a product is to be obtained that can meet the typical tight commercial size distribution and morphology specification, then mixing aspects must be understood. The initial stages involving lowering the pH to cause destabilization, flocculation, and gelling required intense micromixing to prevent oversize CPT product. For gel breakage, again intense agitation was necessary to ensure full motion in the gel due to its yield stress. Intense agitation here was also able to reduce the amount of oversize CPT product to meet specification. All these processing aspects are analyzed in detail in this paper in the light of the present knowledge of mixing. The findings also throw some interesting light on the impact of mixing on aggregate structure at scales below the Kolmogoroff microscale of turbulence, appearing to give support to the ideas of Levich.

The effect of temperature on the interfacial tension and rheology of separated phases in two phase pullulan/gelatin mixtures was investigated over a range of concentrations of both biopolymers. Interfacial tension was measured in a computer controlled Couette device using the retracting drop method and the rheological properties, where determined using Carrimed AR1000 rheometer.It was found that above gelling temperature the gelatin rich phase is approximately Newtonian but as the temperature approaches gelation point it becomes strongly non-Newtonian, with G′ and G″ being time dependent. The pullulan rich phase is also approximately Newtonian at low shear rates and becomes non-Newtonian at a higher shear rate and high concentrations. Above gelling temperature the interfacial tension increases with total concentration of polymers, or in other words with length of tie-lines and at each tie-line it is temperature independent. As the temperature approaches gelation point the interfacial tension for a given mixture decreases sharply.

The effect of solute concentrations on interfacial tension was investigated in phase-separated mixtures of dextran and gelatin over a range of concentrations that covered different tie-lines and different positions on one tie-line. The investigations were carried out using equilibrated gelatin-rich and dextran-rich phases in a computer-controlled Couette device at 40°C (above the gelation point of gelatin) and interfacial tensions were measured using the retracting drop method. The results show that the interfacial tension can be related to the length of the tie-line or to the difference in the concentration of dextran (or gelatin) in the separated phases. Interfacial tension increases as either of these parameters increases. For concentrations lying on any single tie-line, the interfacial tension is constant and independent of the concentration of biopolymers. Also, the addition of small amounts of low molecular weight dextran to a dextran-rich phase does not significantly affect the interfacial tension between the gelatine-rich and dextran-rich phases. Experimental results were also compared with theoretical predictions of the interfacial tension using a Flory–Huggins based analysis of the measured tie-line data. Reasonable agreement was found between predicted and measured values, indicating that this approach captures the basic physics of the system.

The mean drop size and the structure of two-phase aqueous/aqueous dispersions, one-phase sodium alginate-rich of viscosity ∼0.25Pas and the other sodium caseinate-rich of viscosity ∼0.022Pas, have been measured in an unbaffled vessel fitted with a helical screw impeller. The measurements were carried out over a range of volume fractions and at Reynolds numbers in the range from laminar to low transitional. In addition, the interfacial tension between the two phases has been measured in situ using a recently developed drop retraction technique, which, for the first time, has been successfully applied at a high volume fraction of the dispersed phase. At low volume fractions of the viscous phase (viscosity ratio, λ=μd/μc≈10), drops of that phase are seen much as in equivalent aqueous/oil dispersions but the functionality between the drop size and impeller speed is different. As the volume fraction of the viscous phase increases, the structure first changes to a striated one, something never seen in "pure" oil/aqueous dispersions. The striated structure also evolves into complex (droplets-in-drops) in samples withdrawn from the vessel and within the vessel when stirring is stopped. This implies that the system is in a phase inversion region, but contrary to oil/water dispersions, there is not a rapid switch from one phase being continuous to the other, i.e. the phase inversion region appears to be very stable in time. On a further increase of the volume fraction of the viscous phase, phase inversion occurs when stirring but a striated structure continues to exist, i.e. there is no dramatic change of structure as found with aqueous/oil dispersions undergoing phase inversion. However, when a sample is withdrawn or the impeller is stopped, the complex droplets-in-drops formation no longer appears and only a simple dispersed structure develops. Only at very low speeds and volume fractions of the low viscosity dispersed phase, i.e., λ∼0.1, do drops re-appear in the vessel when stirring. Overall, it can be concluded that there is a very significant difference in the behavior of oil/aqueous and aqueous/aqueous dispersions.