Application of direct fluid flow oscillations to improve mixing in microbioreactors

This article describes an active mixing method for a microbioreactor that was designed, simulated, tested, and successfully implemented. By applying a varying pressure to a microchannel looping tangentially into a cylindrical microreactor an oscillating fluid flow was shown to occur. Such an oscillating fluid flow improved mixing, both by diffusion and convection. The oscillating fluid flow has a large impact on the ratio between the diffusion domain and the convection domain. A good match was obtained between experimental mixing results, computational fluid dynamics simulation results and the results of a simplified mixing model thus demonstrating the potential of simulation on improving the design of microreactors. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Neuroproteomics in neurotrauma

Neurotrauma in the form of traumatic brain injury (TBI) afflicts more Americans annually than Alzheimer's and Parkinson's disease combined, yet few researchers have used neuroproteomics to investigate the underlying complex molecular events that exacerbate TBI. Discussed in this review is the methodology needed to explore the neurotrauma proteome-from the types of samples used to the mass spectrometry identification and quantification techniques available. This neuroproteomics survey presents a framework for large-scale protein research in neurotrauma, as applied for immediate TBI biomarker discovery and the far-reaching systems biology understanding of how the brain responds to trauma. Ultimately, knowledge attained through neuroproteomics could lead to clinical diagnostics and therapeutics to lessen the burden of neurotrauma on society.     

Size-exclusion simulated moving bed chromatographic protein refolding

Size-exclusion chromatographic refolding (SECR) has successfully proven its capability to refold a variety of proteins using a range of gel filtration column materials. Several approaches have also been undertaken to improve the refolding yield of these systems, mostly under batch operation. Although, these approaches may lead to an increase on refolding yield, it is not expected that they will lead to significant increases in other important process indicators, such as volumetric productivity, specific eluent consumption and product concentration in the product stream; as these indicators are strongly dependent on the mode of operation. To overcome the shortcomings of batch chromatography, the size-exclusion refolding reactor may be operated in a continuous mode, with the aid of Simulated Moving Bed (SMB) technology. Albeit, SMB technology has inherent advantages over batch chromatography, these have been proven mainly in the context of conventional purifications and are still to be addressed in the context of chromatographic refolding reactors. In this work we report the on-column refolding of an industrially relevant protein, produced in inclusion bodies, by batch size-exclusion chromatography (SEC) and simulated moving bed size-exclusion chromatography (SMBSEC). The presented study encompasses: (1) a statistical design of experiments (DOE) to study the combined effect of the mobile phase pH (9.0–11.20) and the feed concentration of denatured and reduced protein (C_f,D&R=2.50–7.50 mg ml^?1) on the refolding yield of the model protein; (2) a mechanistic analysis of the SMBSECR data, using a detailed model that accounts for both separation and refolding; and (3) a detailed comparison of the SMBSECR against the SECR, based both on quantitative and qualitative criteria. Our work showed that: (1) refolding yields of 50% are attainable by tuning pH and C_f,D&R, and that the positive effect of pH is strongly dependent on the C_f,D&R; (2) the modeling tool captured well the SMBSECR behavior, based solely on the effect that C_f,D&R has on the reaction rates; and (3) the volumetric productivity of the SMBSECR is about 53 times higher than that of the SECR, the specific solvent consumption is approximately 1/10th of that of the SECR, and the concentration of the product (i.e., native protein), leaving the SMBSECR, is roughly 4.5-fold higher than the one leaving the SECR. Accordingly, the comparison revealed the significant advantages that SMB technology has to offer to the design of chromatographic refolding reactors.     

Compliances of a tapered DCB specimen configurations by a finite element method

A series of finite element calculations is carried out to investigate the influence of the crack configuration on the compliance of a tapered double cantilever beam specimen. The results of the calculations are compared with experimental data.     

Spatial externalities, neighbourhood rules and CA land-use modelling

This paper investigates which, how and to what extent land-use related neighbourhood effects play a role in urban dynamics. To justify the use of cellular automata land-use models for spatial policy support, existing neighbourhood rules need to be better founded. This research eliminates a number of uncertainties in the land-use model outcomes by introducing improved empirically founded and regional-specific neighbourhood rules. This allows for a better evaluation and justification of spatial policy scenarios and their effects on future land-use dynamics.     

A multidimensional differential proteomic platform using dual-phase ion-exchange chromatography-polyacrylamide gel electrophoresis/reversed-phase liquid chromatography tandem mass spectrometry

Differential proteomic analysis has arisen as a large-scale means to discern proteome-wide changes upon treatment, injury, or disease. Tandem protein separation methods are required for large-scale differential proteomic analysis. Here, a novel multidimensional platform for resolving and differentially analyzing complex biological samples is presented. The platform, collectively termed CAX-PAGE/RPLC-MSMS, combines biphasic ion-exchange chromatography with polyacrylamide gel electrophoresis for protein separation, quantification, and differential band targeting, followed by capillary reversed-phase liquid chromatography and data-dependent tandem mass spectrometry for quantitative and qualitative peptide analysis. CAX-PAGE provides high protein resolving power with a theoretical peak capacity of 3570, extendable to 7600, a wide protein mass range verified from 16 to 273 kDa, and reproducible differential sample comparison without the added expense of fluorescent dyes and imaging equipment. Demonstrated using a neuroproteomic model, CAX-PAGE revealed an increased number of differential proteins, 137, compared with 82 found by 2D difference gel electrophoresis. When combined with RPLC-MSMS for protein identification, an additional quantification step is performed for internal validation, confirming a 2-fold or greater change in 89% of identified differential targets.     

Spatial impact of urban expansion on surface water bodies—A case study of Wuhan,China

This study aims to raise the level of attention paid to surface water management issues in spatial planning and urban development processes. In the case of cities located in alluvial river plains, surface water bodies may occupy large areas but severe ecological and environmental consequences can arise if they are given insufficient weight in the planning and development processes. After discussing in general terms some of the connections between surface water bodies and urban land use we specifically examine the situation in Wuhan, one of the largest cities in China, which has many surface water bodies in its urban region. We measure and analyse land use changes between 1993 and 2004 to lakes and shallow water bodies and their riparian areas using data derived from detailed land use surveys of the city. Our results show that urban expansion has had a significant impact on Wuhan's surface water bodies and their riparian zones. The reduction, disappearance and pollution of surface water may contribute to the undervaluation of water bodies, thereby increasing the likelihood of further impacts taking place. An integrative and proactive land use planning and management system at regional strategic level and local action level is considered to be essential if surface water systems are to be conserved and improved. Increased recognition of their societal and ecological value should be reflected in more detailed attention to the spatial requirements of water bodies and riparian areas in urban planning policies.     

Cognitive and existential therapies: Toward an integration.

Cognitive and existential therapies are typically viewed as so diverse in their assumptions as to be largely incompatible, representing opposite ends of the psychotherapeutic spectrum. The purpose of this article is to show how a merging of these therapies may contribute to a greater range of options for therapists. The authors attempt to show the surprisingly wide number of connections between these two schools. Comparisons and suggestions are made in the areas of the therapeutic relationship, interpersonal and environmental factors, sociotropy and autonomy, and meaning-making. Existential therapy is especially helpful in understanding the formation and identification of ontological core schemas, and an extensive list of these is provided. A case example involving a 32-yr-old female client with depression is provided that illustrates the integration of these two approaches. (PsycINFO Database Record (c) 2010 APA, all rights reserved)