Processes2015, 3(1), 113-137; doi:10.3390/pr3010113 - published 17 February 2015 Show/Hide Abstract
Abstract: Performance assessment and retuning techniques for proportional-integral-derivative (PID) controllers are reviewed in this paper. In particular, we focus on techniques that consider deterministic performance and that use routine operating data (that is, set-point and load disturbance step signals). Simulation and experimental results show that the use of integrals of predefined signals can be effectively employed for the estimation of the process parameters and, therefore, for the comparison of the current controller with a selected benchmark.
Processes2015, 3(1), 98-112; doi:10.3390/pr3010098 - published 16 February 2015 Show/Hide Abstract
Abstract: Silver nanoparticles supported on hierarchically porous silica and cobalt oxide monoliths have previously been shown to be catalytically active for the hydrogenation of common organic dyes in batch studies. This work presents a detailed investigation of the activity and stability of these monoliths during the hydrogenation of eosin-Y in a continuous flow microreactor. The silver-containing monoliths showed excellent catalytic activity that reached a plateau after a period of approximately 6 h. From SEM particle size distribution studies of the catalysts before and after water and hexane were flowed through them, it was determined that under reaction conditions, silver was removed both by washing off of particles and by dissolution of silver.
Processes2015, 3(1), 75-97; doi:10.3390/pr3010075 - published 11 February 2015 Show/Hide Abstract
Abstract: The kinase Syk is intricately involved in early signaling events in B cells and isrequired for proper response when antigens bind to B cell receptors (BCRs). Experimentsusing an analog-sensitive version of Syk (Syk-AQL) have better elucidated its role, buthave not completely characterized its behavior. We present a computational model for BCRsignaling, using dynamical systems, which incorporates both wild-type Syk and Syk-AQL.Following the use of sensitivity analysis to identify significant reaction parameters, we screenfor parameter vectors that produced graded responses to BCR stimulation as is observedexperimentally. We demonstrate qualitative agreement between the model and dose responsedata for both mutant and wild-type kinases. Analysis of our model suggests that the level of NF-KB activation, which is reduced in Syk-AQL cells relative to wild-type, is more sensitiveto small reductions in kinase activity than Erkp activation, which is essentially unchanged.Since this profile of high Erkp and reduced NF-KB is consistent with anergy, this implies thatanergy is particularly sensitive to small changes in catalytic activity. Also, under a range offorward and reverse ligand binding rates, our model of Erkp and NF-KB activation displaysa dependence on a power law affinity: the ratio of the forward rate to a non-unit power of thereverse rate. This dependence implies that B cells may respond to certain details of bindingand unbinding rates for ligands rather than simple affinity alone.
Processes2015, 3(1), 71-74; doi:10.3390/pr3010071 - published 11 February 2015 Show/Hide Abstract
Abstract: The Special Issue “Feature Papers” of the journal Processes aims to establish the scope of this new open access journal in chemical, biological, environmental, pharmaceutical, and material-process engineering, as well as the development of general process engineering methods. The Special Issue is available online at: http://www.mdpi.com/journal/processes/special_issues/feature-paper.[...]
Processes2015, 3(1), 50-70; doi:10.3390/pr3010050 - published 14 January 2015 Show/Hide Abstract
Abstract: Interleukin-6 (IL-6) is a systemic inflammatory mediator that triggers the human body’s acute phase response to trauma or inflammation. Although mathematical models for IL-6 signaling pathways have previously been developed, reactions that describe the expression of acute phase proteins were not included. To address this deficiency, a recent model of IL-6 signaling was extended to predict the dynamics of acute phase protein expression in IL-6-stimulated HepG2 cells (a human hepatoma cell line). This included reactions that describe the regulation of haptoglobin, fibrinogen, and albumin secretion by nuclear transcription factors STAT3 dimer and C/EBPβ. This new extended model was validated against two different sets of experimental data. Using the validated model, a sensitivity analysis was performed to identify seven potential drug targets to regulate the secretion of haptoglobin, fibrinogen, and albumin. The drug-target binding kinetics for these seven targets was then integrated with the IL-6 kinetic model to rank them based upon the influence of their pairing with drugs on acute phase protein dynamics. It was found that gp80, JAK, and gp130 were the three most promising drug targets and that it was possible to reduce the therapeutic dosage by combining drugs aimed at the top three targets in a cocktail. These findings suggest hypotheses for further experimental investigation.
Processes2015, 3(1), 46-49; doi:10.3390/pr3010046 - published 12 January 2015 Show/Hide Abstract
Abstract: Tissue engineering and, more broadly, regenerative medicine is moving into a phase where we are seeing potential therapies moving ‘slowly but surely’ from the laboratory into the clinic, i.e.,from research to the clinic and into manufacturing. The numbers of cells required for cell therapy protocols can vary from tens of millions, to billions , and it is widely considered that such cell numbers can be produced in bioreactor systems. Thus, the bioreactor is becoming a key tool for culturing clinical numbers of human cells and the regenerative medicine industry will become increasingly reliant on such systems at the centre of cell therapy production and tissue engineering.[...]