Net Shape Fins for Compact Heat Exchanger Produced by Cold Spray

This work explores the manufacturability of pyramidal fin arrays produced using the cold spray process. Near-net shaped pyramidal fin arrays of various sizes and fin densities were manufactured using masks made of commercially available steel wire mesh. The feedstock powders used to produce the fins are characterized using scanning electron microscopy. Obstruction of the masks was investigated. The standoff distances between the substrate, mesh, and nozzle were empirically determined. Fin array characterization was performed using digital microscopy. The fin arrays’ heat transfer performance was assessed experimentally for a range of Reynolds number relevant to the application sought. The fins produced using the cold spray process outperform traditional straight (rectangular) fins at the same fin density and it is hypothesized that this is due to increased fluid mixing and turbulence.     

Effects of carbon nanotubes and their state of dispersion on the anionic polymerization of ϵ‐caprolactam: 1. Calorimetry

This work reports, for the first time, on the effect of carbon nanotubes (CNT) on the kinetics of the activated polymerization of lactams. Differential scanning calorimetry (DSC) was chosen to study the kinetics of the activated anionic polymerization of ε‐caprolactam in the presence of multiwalled carbon nanotubes (MWCNT). A statistical test was carried out to confirm the validity of the experimental approach. The presence of the MWCNT slowed down the polymerization rate. This inhibiting effect depended not only on the MWCNT content but also on its state of dispersion in the polymerizing system. An autocatalytic model coupled with an evolutionary algorithm showed that the MWCNT content had an effect on the autocatalysis while its state of dispersion had an effect on the apparent polymerization kinetic constant. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

A Neo-institutionalist Model of the Diffusion of IFRS Accounting Standards

The purpose of this study is to prepare a diffusion model of the new international accounting standards known as the international financial reporting standards (IFRS). This model fits within the neo-institutional conceptual framework; more specifically, we used the DiMaggio/Powell analytical grid. Our desire to prepare this model was born from the observation that the analytical framework that is generally used to study the adoption of these new standards is the neo-institutional framework and that the principal methodologies implemented are qualitative. The question addressed in this study regards the forces leading an agent—in this case, an organisation providing standards for accounting—to adopt, at a given moment, these new standards. Existing studies, as interesting as they might be, are devoted to the question of adoption and leave aside the question of diffusion. In other words, the evolution of the system as a whole in time is ignored. Constructing a model appeared to us to be a way to move beyond these limitations. This model allows us to formalise the forces at work in the DiMaggio/Powell representation and to simulate the diffusion processes of the IFRS. To this end, we implement a multi-agent simulation. The various simulation scenarios are then compared to the observed diffusion of the IFRS.     

Phosphate uptake from water on a Surfactant-Modified Zeolite and Ca-zeolites

The phosphate adsorption kinetics are determined in batch-wise (noted B) and fixed-bed column (noted C) experiments on a Surfactant-Modified Zeolite (SMZ) and various Ca-zeolites. The influence of phosphate concentration (0.08 or 0.8?mmol/L), presence of NO₃ ^?, HCO₃ ^?, SO₄ ^2? and Cl^? competing anions (individual concentration?=?0.8?meq/L) and flow rate Q (1?C30?mL/min) is studied. Preliminary experiments lead to the selection of the most efficient Ca-LTA and SMZ samples for the subsequent studies. In B experiments, the nature of the used system does not influence the equilibrium removal rate R (??80%) but affects the adsorption kinetics. The equilibrium times are shorter on SMZ than on Ca-LTA, increasing with the phosphate concentration and the presence of competing anions, respectively in the ~0.5?C6 or ~3?C24?h ranges. In C experiments, the phosphate uptake performances on SMZ are higher than in the corresponding B experiments, with in particular higher final q/q_m values. The deterioration of the performances on SMZ in presence of competing anions or with increase of Q is due to the effect of the slow phosphate ion-exchange kinetics and the short used contact time. For similar reasons, sorption on Ca-LTA is lower than on SMZ. For instance, with a 0.8?mmol/L phosphate concentration and a 10?mL/min flow rate, the time-decreasing R values become close to 50 and 10% after filtration of 10 bed-volumes respectively in presence of SMZ and Ca-LTA. Globally, SMZ is clearly more efficient than Ca-LTA, being furthermore a versatile and easily regenerable material.     

The effect of surface modification on the corrosion protection ability of the passive films of sensitized UNS S31803 duplex stainless steel

ABSTRACT

The influence of sensitisation heat treatment, surface roughness and repetitive cyclic voltammetry (RCV) procedure (that was used to create passive films on the surface of sensitised samples) on the corrosion behaviour of UNS S31803 duplex stainless steel was evaluated using sodium hydroxide etching, double-loop electrochemical potentiodynamic reactivation (DLEPR), potentiodynamic polarisation, Mott–Schottky analysis, X-ray diffraction and optical microscopy techniques. The results showed that prolonged sensitisation time leads to the formation of defective passive films on the surface. In addition, as the substrate surface roughness decreases, the defect concentration in the resulting passive film decreases. Moreover, thick passive films that were created at a high number of RCV cycles contain fewer defects than the thin ones. Finally, the specimens with smooth surfaces, thick passive films and low degree of sensitisation exhibit high corrosion resistance due to their intact passive layers formed on their surfaces.     

Experimental investigation of two-phase electrolysis processes: comparison with or without gravity

During two-phase electrolysis, bubble production occurs at one or two electrodes. This yields a large change for the electrolyser electrical and hydrodynamic properties. Under normal Earth gravity, the bubble production at the electrodes induces a macro-convection in the electrolyser. This leads to a modified local current density distribution at the electrodes. When gravity is avoided, bubbles are no longer subject to buoyancy forces and to the induced natural flow friction forces. Electrolysis was performed using a potentiostat, and gas bubble evolution was observed with cameras. Quantitative evolution laws for the electrochemical cell voltage, bubble diameter and population during two-phase electrolysis are established in function of the current density and gravity variation.     

Cancer-Associated Glycosphingolipids as Tumor Markers and Targets for Cancer Immunotherapy

Aberrant expression of glycosphingolipids is a hallmark of cancer cells and is associated with their malignant properties. Disialylated gangliosides GD2 and GD3 are considered as markers of neuroectoderm origin in tumors, whereas fucosyl-GM1 is expressed in very few normal tissues but overexpressed in a variety of cancers, especially in small cell lung carcinoma. These gangliosides are absent in most normal adult tissues, making them targets of interest in immuno-oncology. Passive and active immunotherapy strategies have been developed, and have shown promising results in clinical trials. In this review, we summarized the current knowledge on GD2, GD3, and fucosyl-GM1 expression in health and cancer, their biosynthesis pathways in the Golgi apparatus, and their biological roles. We described how their overexpression can affect intracellular signaling pathways, increasing the malignant phenotypes of cancer cells, including their metastatic potential and invasiveness. Finally, the different strategies used to target these tumor-associated gangliosides for immunotherapy were discussed, including the use and development of monoclonal antibodies, vaccines, immune system modulators, and immune effector-cell therapy, with a special focus on adoptive cellular therapy with T cells engineered to express chimeric antigen receptors.