A feasibility assessment of a retrofit Molten Carbonate Fuel Cell coal-fired plant for flue gas CO₂ segregation

This work considers the use of a Molten Carbonate Fuel Cell (MCFC) system as a power generation and CO2 concentrator unit downstream of the coal burner of an existing production plant. In this way, the capability of MCFCs for CO2 segregation, which today is studied primarily in reference to large-scale plants, is applied to an intermediate-size plant highlighting the potential for MCFC use as a low energy method of carbon capture. A technical feasibility analysis was performed using an MCFC system-integrated model capable of determining steady-state performance across varying feed composition. The MCFC user model was implemented in Aspen Custom Modeler and integrated into the reference plant in Aspen Plus. The model considers electrochemical, thermal, and mass balance effects to simulate cell electrical and CO2 segregation performance. Results obtained suggest a specific energy requirement of 1.41 MJ kg CO2 121 significantly lower than seen in conventional Monoethanolamine (MEA) capture processes

Termination Casts: A Flexible Approach to Termination with General Recursion

This paper proposes a type-and-effect system called Teqt, which distinguishes terminating terms and total functions from possibly diverging terms and partial functions, for a lambda calculus with general recursion and equality types. The central idea is to include a primitive type-form "Terminates t", expressing that term t is terminating; and then allow terms t to be coerced from possibly diverging to total, using a proof of Terminates t. We call such coercions termination casts, and show how to implement terminating recursion using them. For the meta-theory of the system, we describe a translation from Teqt to a logical theory of termination for general recursive, simply typed functions. Every typing judgment of Teqt is translated to a theorem expressing the appropriate termination property of the computational part of the Teqt term.Comment: In Proceedings PAR 2010, arXiv:1012.455

Dialectica Categories for the Lambek Calculus

We revisit the old work of de Paiva on the models of the Lambek Calculus in dialectica models making sure that the syntactic details that were sketchy on the first version got completed and verified. We extend the Lambek Calculus with a \kappa modality, inspired by Yetter's work, which makes the calculus commutative. Then we add the of-course modality !, as Girard did, to re-introduce weakening and contraction for all formulas and get back the full power of intuitionistic and classical logic. We also present the categorical semantics, proved sound and complete. Finally we show the traditional properties of type systems, like subject reduction, the Church-Rosser theorem and normalization for the calculi of extended modalities, which we did not have before

The effect of particulate matter on paper degradation

Background: In this work we explore the chemical effects of particulate matter on paper. We exposed paper made of pure cellulose to the environment in different locations in central London, outdoors (in sheltered conditions) and indoors, for a period of up to 6 months. We monitored particulate matter (PM) deposition by counting the particles deposited every month with a scanning electron microscope. We analysed elemental composition of the deposited particles using inductively coupled plasma mass spectrometry. After accelerated degradation of the exposed samples, we determined the degree of polymerisation using viscometry. Results: We observed higher deposition rates and higher metal concentration outdoors than indoors. Elemental analysis of the deposited particles revealed the presence of some transition metals (Fe, Cu, Cr) that can contribute to the degradation of cellulose fibres through the Fenton reaction. By comparing the degree of polymerisation of pro‑ tected, unprotected and unexposed samples we could determine the relative contribution of PM deposition on the increase of the degradation rate. We found that the surface concentration of iron correlates with the reduction in the degree of polymerisation of the exposed paper. Conclusions: The results suggest that the presence of Fenton metals in PM has a significant effect on the accelera‑ tion of the degradation of cellulose. However, we estimate that this will unlikely occur at the levels of area coverage by PM that are typically avoided in indoor heritage through preventive maintenance and cleaning

Extracellular electrical signals in a neuron-surface junction: model of heterogeneous membrane conductivity

Signals recorded from neurons with extracellular planar sensors have a wide range of waveforms and amplitudes. This variety is a result of different physical conditions affecting the ion currents through a cellular membrane. The transmembrane currents are often considered by macroscopic membrane models as essentially a homogeneous process. However, this assumption is doubtful, since ions move through ion channels, which are scattered within the membrane. Accounting for this fact, the present work proposes a theoretical model of heterogeneous membrane conductivity. The model is based on the hypothesis that both potential and charge are distributed inhomogeneously on the membrane surface, concentrated near channel pores, as the direct consequence of the inhomogeneous transmembrane current. A system of continuity equations having non-stationary and quasi-stationary forms expresses this fact mathematically. The present work performs mathematical analysis of the proposed equations, following by the synthesis of the equivalent electric element of a heterogeneous membrane current. This element is further used to construct a model of the cell-surface electric junction in a form of the equivalent electrical circuit. After that a study of how the heterogeneous membrane conductivity affects parameters of the extracellular electrical signal is performed. As the result it was found that variation of the passive characteristics of the cell-surface junction, conductivity of the cleft and the cleft height, could lead to different shapes of the extracellular signals

Effects of Menopause in Women With Multiple Sclerosis: An Evidence-Based Review

Over two thirds of all individuals who develop multiple sclerosis (MS) will be women prior to the age of menopause. Further, an estimated 30% of the current MS population consists of peri- or postmenopausal women. The presence of MS does not appear to influence age of menopausal onset. In clinical practice, symptoms of MS and menopause can frequently overlap, including disturbances in cognition, mood, sleep, and bladder function, which can create challenges in ascertaining the likely cause of symptoms to be treated. A holistic and comprehensive approach to address these common physical and psychological changes is often suggested to patients during menopause. Although some studies have suggested that women with MS experience reduced relapse rates and increased disability progression post menopause, the data are not consistent enough for firm conclusions to be drawn. Mechanisms through which postmenopausal women with MS may experience disability progression include neuroinflammation and neurodegeneration from age-associated phenomena such as immunosenescence and inflammaging. Additional effects are likely to result from reduced levels of estrogen, which affects MS disease course. Following early retrospective studies of women with MS receiving steroid hormones, more recent interventional trials of exogenous hormone use, albeit as oral contraceptive, have provided some indications of potential benefit on MS outcomes. This review summarizes current research on the effects of menopause in women with MS, including the psychological impact and symptoms of menopause on disease worsening, and the treatment options. Finally, we highlight the need for more inclusion of MS patients from underrepresented racial and geographic groups in clinical trials, including among menopausal women

Genome-wide analyses of Liberibacter species provides insights into evolution, phylogenetic relationships, and virulence factors.

'Candidatus Liberibacter' species are insect-transmitted, phloem-limited α-Proteobacteria in the order of Rhizobiales. The citrus industry is facing significant challenges due to huanglongbing, associated with infection from 'Candidatus Liberibacter asiaticus' (Las). In order to gain greater insight into 'Ca. Liberibacter' biology and genetic diversity, we have performed genome sequencing and comparative analyses of diverse 'Ca. Liberibacter' species, including those that can infect citrus. Our phylogenetic analysis differentiates 'Ca. Liberibacter' species and Rhizobiales in separate clades and suggests stepwise evolution from a common ancestor splitting first into nonpathogenic Liberibacter crescens followed by diversification of pathogenic 'Ca. Liberibacter' species. Further analysis of Las genomes from different geographical locations revealed diversity among isolates from the United States. Our phylogenetic study also indicates multiple Las introduction events in California and spread of the pathogen from Florida to Texas. Texan Las isolates were closely related, while Florida and Asian isolates exhibited the most genetic variation. We have identified conserved Sec translocon (SEC)-dependent effectors likely involved in bacterial survival and virulence of Las and analysed their expression in their plant host (citrus) and insect vector (Diaphorina citri). Individual SEC-dependent effectors exhibited differential expression patterns between host and vector, indicating that Las uses its effector repertoire to differentially modulate diverse organisms. Collectively, this work provides insights into the evolution of 'Ca. Liberibacter' species, the introduction of Las in the United States and identifies promising Las targets for disease management