Visualization of Structural Changes in Thermochemically Pretreated Plant Cell Wall Polymers

Second-generation biofuels made from lignocellulosic biomass hold immense potential in serving as an alternative source of energy. Due to the rigid cell wall structure, the biomass has to be pretreated with chemicals, often at high temperature and pressure, to breakdown the cell wall structure and increase cellulose accessibility to hydrolytic enzymes. Through years of research, a great amount has been learned about the structural rearrangements that occur after pretreatment and have resulted in proposed reasons for recalcitrance to enzyme hydrolysis that occurs even after pretreatment. But why the structural re-arrangement took place the way it did during pretreatment is largely unknown. This is because our current understanding of how polymers are interacting and influencing each other’s structures during pretreatment is lacking. The overall aim of the work is to understand how plant cell wall polymers interact in lignocellulose and the changes that occur in these interactions during hot water or dilute acid pretreatment. Our approach involves studying polymer-polymer interactions using model systems and conducting comparative studies in natural variants of poplar and switchgrass. Using x-rays and neutrons based scattering techniques, we studied the impact different kinds of hemicelluloses have on the hierarchical structure of cellulose before and after pretreatment. We also studied intact biomass and used a comparative approach to study the sugar release differences before and after pretreatment for two poplar woods with different lignin content. Lastly, we also explored the interactions of pectin with lignin to determine if pectin can influence the lignin aggregate formation. Overall, information on this fundamental knowledge of polymer interactions can help design milder pretreatments or plants that are more susceptible to deconstruction which would decrease the cost of thermochemical pretreatment

Genome engineering in mammalian cells by Flp and Cre DNA recombinase variants

Genome engineering relies on DNA modifying enzymes that are able to locate a DNA sequence of interest and initiate a desired genome rearrangement. Currently, the field predominantly utilizes site-specific DNA nucleases that depend on the host DNA repair machinery to complete a genome modification task. We show here that genome engineering approaches that employ self-sufficient, versatile site-specific DNA recombinase Flp and Cre can be developed into promising alternatives. We demonstrate that a Flp variant evolved to recombine an FRT-like sequence FL-IL10A, which is located upstream of the human interleukin-10 gene, can target this sequence in the model setting and native HEK293 cells. Similarly, Cre variant evolved to recombine at loxP-like sequence LL-69058, which is located upstream of the beta globin gene, can target this sequence in the model setting of CHO cells and human HEK293 cells. The target-specific Flp variant is able to perform the integration reaction but the efficiency of the integration reaction in human cells can be enhanced by `humanizing\u27 the Flp variant gene and by adding the NLS sequence to the recombinase. Cre variant displays a poor replacement activity in the mammalian cells and thus is fused with TAL DNA-binding domain to enhance their performance. TAL-Cre variant is able to perform efficient replacement reaction, when paired with another recombinase (dual RMCE). The Cre variant replacement activity is observed only when they are fused to the TA

An AHP based visual tool assignment model for accident avoidance in manufacturing workplaces

Collaborative risk management techniques place management and workers equally while developing a safety culture in workplaces. Traditional risk awareness methods which are commonly carried out in workplaces, such as training and safety manuals, are inherently passive in nature. On the other hand, visual tools are active risk communication mechanisms which deliver specific risk information in a work area. The presented study places emphasis on risk awareness for workers through the assignment of visual tools, which is critical to the success of a collaborative framework. Traditionally, the assignment of visual tools to work area locations has been arbitrary, potentially causing the risk information to be ineffective. The framework presented in this study provides a systematic visual tool assignment method for safety managers in manufacturing work areas. This placement is based on the attributes of the work area. The use of multi-criteria decision making (MCDM) techniques such as Analytic Hierarchy Process (AHP) incorporates the expertise of safety managers for a successful visual tool assignment by considering work area and entity variables. Analysis of Variance (ANOVA) and Data Envelopment Analysis (DEA) reduce the number of variables that act as the criteria for AHP. The scenario-based case study indicate that these variables had an impact on the choice of visual tools. These scenarios are designed to depict multiple locations in a heavy manufacturing plant layout. The presented study is applicable to mobile entity interfaces in manufacturing industries. It can be applied to other manufacturing safety incident categories and industries which could benefit from visual communication of risk information in work areas

Use of fluorescent micropsheres to measure coronary flow reserve in rat animal model

Heart attacks result from reduced or blocked blood flow through major coronary arteries, resulting in permanent damage to heart muscle. Coronary blood flow (CBF) is thus important to measure in experimental animal models of heart disease. A standard method to measure CBF uses tracer microspheres (Ø = 15 µm) injected into the left ventricle that flow through coronary arteries but cannot pass through capillaries and so become trapped in heart muscle. Previously, radioactive or colored microspheres have quantified the number of tracers trapped in the muscle. Fluorescent microspheres offer a more recent and more sensitive measurement mode. However, fluorescent microspheres have not often been used to measure CBF in small animals (rats, mice) that are now the most common animal models used in heart research. This thesis aimed to develop the techniques for use of fluorescent microspheres to measure CBF in rat animal models used by the cell biology laboratories at UMDNJ-Newark. Two non-overlapping fluorescent wavelengths were chosen (yellow-green; red). Using a spectrophotometer, fluorescence intensity was calibrated for known numbers of microspheres (set via controlled dilution). CBF in two rats was measured at rest and during maximal vasodilation (adenosine) using procedures for colored microspheres. After euthanasia, hearts were removed, and blood samples and left ventricular tissue were processed using a sedimentation method for full recovery of fluorescent microspheres, which were scanned through the spectrophotometer to count fluorescence intensity. Using the predetermined calibration curve, the number of microspheres in each sample was determined; from this CBF was calculated. CBF averaged 5.9 ml/min/g at rest, which was within the normal range for rats quoted in recent literature. With maximal vasodilation, CBF increased to an average of 12.9 ml/min/g, which indicated a coronary flow reserve that was 2.2 times the resting level. The same value for coronary flow velocity reserve (2.2) was measured in 6 rats using Doppler echocardiography. The consistency of these results suggests that the procedures developed for fluorescent microspheres lead to repeatable and reliable measurement of coronary blood flow in rats

Cartan subgroups in connected locally compact groups

We define Cartan subgroups in connected locally compact groups, which extends the classical notion of Cartan subgroups in Lie groups. We prove their existence and justify our choice of the definition which differs from the one given by Chevalley on general groups. Apart from proving some properties of Cartan subgroups, we show that the Cartan subgroups of the quotient groups are precisely the images of Cartan subgroups of the ambient group. We establish the so-called `Levi' decomposition of Cartan subgroups which extends W\"ustner's decomposition theorem and our earlier results about the same proven for Lie groups. We also show that the centraliser of any maximal torus of the radical is connected and its Cartan subgroups are also the Cartan subgroup of the ambient group; moreover, every Cartan subgroup arises this way. We prove that Cartan subalgebras defined by Hofmann and Morris in pro-Lie algebras are the same as those corresponding to Cartan subgroups in case of pro-Lie algebras of connected locally compact groups, and that they are nilpotent. We characterise density of the image of a power map in the group in terms of its surjectivity on all Cartan subgroups, and show that weak exponentiality of the group is equivalent to the condition that all its Cartan subgroups are connected.Comment: 33 page