Continuous flow characterization of solid biomass in a reciprocating/rotating scraper tube: An experimental study

The performance of reciprocating/rotating scrapers has been assessed in a visualization study of the continuous flow hydrodynamics of air‐fluidized solid biomass under varying conditions of air flow rate and scraping velocities. A combination of low air flow rates and high scraping velocities results in more uniform flow of both types of biomass investigated. Power consumed by the reciprocating action of the scrapers increases with the scraping velocity but typically represents no more than 20% of the overall power consumption at the highest air flow rate applied. We also demonstrate that rotation of the scrapers superimposed on their reciprocating action gives higher flow rate of biomass and better mixing within the bulk solid compared to reciprocating action alone. The application of the reciprocating/rotating scraper technology described in this study represents a viable step forward in developing a continuous, large‐scale process for the microwave‐assisted decomposition of solid biomass to produce bio‐oils. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3732–3738, 2014     

Surfactant-free emulsion polymerisation of methyl methacrylate and methyl acrylate using intensified processing methods

The feasibility of enhancing the latex yield and colloid characteristics in the surfactant-free emulsion polymerisation (SFEP) of methyl methacrylate (MMA) and methyl acrylate (MA) through the use of intensified processing technologies is reported in this paper. The effects of high power ultrasonic energy as a well-established technique for mixing and mass transfer enhancements were compared with thermal initiation in a conventional mechanically agitated reactor. Although increases in ultrasonic power input resulted in higher rates of reaction and larger particles in the MMA polymerisation, reaction yields were nevertheless found to be low compared with the thermally initiated stirred tank reactor experiments. This was attributed to the low frequency ultrasound used (24 kHz) that was observed to provide excellent emulsification but was ineffective in terms of radical generation. The results for a thermally initiated SFEP of MA in a narrow channel reactor as an example of a continuous flow reactor technology showed that reaction rates were comparable with those achieved in the stirred tank reactor but at only a fraction of the specific power input whilst smaller particles with a tighter distribution are generated. These effects highlight the process intensification characteristics of the narrow channel reactor for the SFEP of MA.     

Development of a Higee bioreactor (HBR) for production of polyhydroxyalkanoate: Hydrodynamics,gas–liquid mass transfer and fermentation studies

This study addresses the hydrodynamics and mass transfer characterisation of a Higee bioreactor (HBR) for application to polyhydroxyalkanoate (PHA) production from Pseudomonas putida KT2442 fermentation. The motivation for this work is to address the potential oxygen transfer limitations which can severely impede the progress of this aerobic fermentation process and reduce PHA productivity in conventional bioreactors. It is shown that a maximum of 2.5 transfer units can be achieved in an oxygen-stripping operation where the presence of packing, higher rotor speeds, higher air flowrates and lower liquid flowrates all have a positive influence on the number of transfer units (NTU). We also observed from a visualisation study that gas bubbles as small as 0.36 mm in diameter can be generated within the HBR operating at 1200 rpm. Preliminary results from the P. putida fermentation studies in the HBR indicate that biomass concentrations of up to 0.5 g/l can be achieved with a maximum PHA yield of 6.2%, both of which are lower than those achieved in a conventional stirred tank reactor. The reasons for the relatively poor performance of the HBR in the context of the fermentation study are discussed and suggestions for improvement are presented.     

Ground surface displacements and tilt monitoring for reconstruction of reservoir deformations

Surface deformation generated during hydrocarbon production, and waste or water reinjection, can be used to indirectly monitor subsurface deformation sources. Forward and inverse models previously studied are mostly based on the nucleus of strain approach and are focused on measurements of vertical or horizontal deformations. The main objective of this study was to reconstruct subsurface deformations based on the unidirectional deformation technique and using combinations of tilt values as well as vertical displacements. A new numerical model was therefore developed. In order to stabilize the inverse ill-posed problem, a regularization method was developed in this study.One objective of this study was to determine the most suitable surface deformation data set resulting in the best inverse simulation. A detailed analysis was therefore performed. Tilt measurements were found to be more suitable data for inverse modeling compared to vertical displacements: tilts result in a better resolution (smaller root mean square error (RMSE)). Moreover, the inverse simulation was found to be significantly less sensitive to measurement errors when tilt values were used as input data: adding 0.55% error to the surface vertical displacement values increased the RMSE by more than 13 times, whereas, adding 20% error to the tilt values increased the RMSE by a factor of 7. Furthermore, the number of benchmarks could considerably be reduced without affecting the inverse solution significantly when using tilt measurements.     

Multilayer coatings on biomaterials for control of MG-63 osteoblast adhesion and growth

Here, the layer-by-layer technique (LbL) was used to modify glass as model biomaterial with multilayers of chitosan and heparin to control the interaction with MG-63 osteoblast-like cells. Different pH values during multilayer formation were applied to control their physico-chemical properties. In the absence of adhesive proteins like plasma fibronectin (pFN) both plain layers were rather cytophobic. Hence, the preadsorption of pFN was used to enhance cell adhesion which was strongly dependent on pH. Comparing the adhesion promoting effects of pFN with an engineered repeat of the FN III fragment and collagen I which both lack a heparin binding domain it was found that multilayers could bind pFN specifically because only this protein was capable of promoting cell adhesion. Multilayer surfaces that inhibited MG-63 adhesion did also cause a decreased cell growth in the presence of serum, while an enhanced adhesion of cells was connected to an improved cell growth.     

Synthesis,Characterization, and Application of Zn–Al Layered Double Hydroxide as a Nano-Sorbent for the Removal of Direct Red 16 from Industrial Wastewater Effluents

In this research, nano-structured zinc–aluminum layered double hydroxide (Zn–Al LDH) was successfully synthesized by a co-precipitation method and followed by thermal treatment. The structure and morphology of the obtained material was characterized by X-ray diffraction, transmission electron microscopy, nitrogen-adsorption–desorption isotherms, and Fourier transform infrared spectroscopy. The as-prepared LDH was applied as a solid phase extraction (SPE) sorbent for the removal of direct red 16 (DR16) from aqueous solutions. A spectrophotometric method was used for monitoring of the extracted DR16 at λ = 548 nm. The effect of several parameters such as pH, sample flow rate, amount of nano-sorbent, elution conditions, and sample volume on the removal percentage was investigated. The results showed that DR16 could be retained by Zn–Al(NO₃^?) LDH at pH 6 and stripped by 2.5 mL of 1.0 mol L^?1 NaOH. In the optimum experimental conditions, the limit of detection and relative standard deviation were 0.003 µg mL^?1 and 1.2%, respectively. The calibration graph using the presented SPE system was linear in the range of 0.01–2.00 µg mL^?1 of DR16 with a correlation coefficient of 0.9994. The method was successfully applied for the removal of DR16 from several industrial wastewater effluents.     

Classical cationic polymerization of styrene in a spinning disc reactor using silica‐supported BF3 catalyst

The carbo‐cationic polymerization of styrene has been studied in a Spinning Disc Reactor (SDR) and the results were compared to those observed in a conventional Stirred Tank Reactor (STR). Addition of styrene to a slurry of silica‐supported boron trifluoride (BF₃/SiO₂) in 1,2‐dichloroethane led to uncontrollable reactions in the STR at monomer concentrations > 25%w/w and initial temperatures of 20–25°C. By comparison, monomer concentrations of 75% w/w were safely and controllably polymerized in the SDR at 40°C to yield polymers with molecular weights comparable to those reported in the literature for polymer prepared at ?60°C. Exceptional heat transfer rates achieved in the SDR are sufficient to deal with the heat evolved when styrene is polymerized at concentrations as high as 75% w/w, the reaction proceeding under essentially isothermal conditions. In the present study, the effects of monomer/solvent feed rates, monomer concentrations, disc size, and disc speed on monomer conversions, polymer molecular weights, and polydispersities achieved in the SDR are investigated. Speculative explanations of the observed results are presented in terms of enhanced mixing effects on the polymerization mechanisms in the SDR. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 8–19, 2006     

Morphometric and Nanomechanical Features of Erythrocytes Characteristic of Early Pregnancy Loss

Early pregnancy loss (EPL) is estimated to be between 15 and 20% of all adverse pregnancies. Approximately, half of EPL cases have no identifiable cause. Herein, we apply atomic force microscopy to evaluate the alteration of morphology and nanomechanics of erythrocytes from women with EPL with unknown etiology, as compared to healthy pregnant (PC) and nonpregnant women (NPC). Freshly isolated erythrocytes from women with EPL differ in both the roughness value (4.6 ± 0.3 nm, p < 0.05), and Young’s modulus (2.54 ± 0.6 MPa, p < 0.01) compared to the values for NPC (3.8 ± 0.4 nm and 0.94 ± 0.2 MPa, respectively) and PC (3.3 ± 0.2 nm and 1.12 ± 0.3 MPa, respectively). Moreover, we find a time-dependent trend for the reduction of the cells’ morphometric parameters (cells size and surface roughness) and the membrane elasticity—much faster for EPL than for the two control groups. The accelerated aging of EPL erythrocytes is expressed in faster morphological shape transformation and earlier occurrence of spiculated and spherical-shaped cells, reduced membrane roughness and elasticity with aging evolution. Oxidative stress in vitro contributed to the morphological cells’ changes observed for EPL senescent erythrocytes. The ultrastructural characteristics of cells derived from women with miscarriages show potential as a supplementary mark for a pathological state.