Laser Welding of Medium-Manganese Steel

Medium-Manganese (MMn) third generation advanced high strength steel (AHSS) was joined using laser welding. The effects of rapid heating and cooling thermal cycles imposed by laser welding on MMn steel was investigated. Microhardness profiles of large heat input diode laser bead-on-plate (BoP) welds found that the steel was not susceptible to heat affected zone (HAZ) softening. The peak temperature above the upper critical temperature (A3) was determined to have a significant effect on the microstructure and morphology of austenite in the HAZ. The solidification mode of the diode laser fusion zone (FZ) was primarily columnar dendritic in nature and microsegregation of Mn to the inter-dendritic spaces was observed. Higher energy density fiber laser welding was used to produce laser welded blanks (LWB) containing MMn steel, high strength low alloy (HSLA) and dual-phase (DP) steel. Columnar dendritic solidification was also observed in fiber laser welds of MMn steel. Dissimilar welds containing HSLA and DP980 were found to produce a martensitic FZ with a fraction of stable austenite. HAZ softening was also absent from microhardness profiles of fiber laser welded MMn steel due to the absence of pre-existing martensite and austenite grain growth. Sub-sized similar MMn steel laser welded tensile blanks were observed to exhibit high joint efficiency with respect to the BM. Tensile testing conducted on dissimilar blanks of HSLA and DP980 were observed to fracture in their respective BM due to a difference in yield and ultimate tensile strength. Formability of similar MMn steel LWB was limited, but welding to HSLA or DP980 improved the LWB formability. LWBs of MMn steel were investigated for potential as a new press hardened steel (PHS) chemistry. Standard size tensile geometries of MMn steel LWB showed that the FZ was sensitive to loading conditions where large strains begin to accumulate. Heat treating and quenching a LWB at an inter-critical annealing temperature showed that the austenite reverse transformation can occur in the laser weld FZ. Laser weld joint ductility was determined to significantly improve by heat treating at a lower temperature (700 °C) and a shorter time (3-4 minutes) compared to conventional boron press hardened steels

Mid-range wireless power transfer with segmented coil transmitters for implantable heart pumps

In wireless power transfer systems, the transmitting coil dimensions can substantially affect the transmission range and alignment sensitivity. We found that a transmitting coil with larger inner and outer diameter has a wider transmission range and lower alignment sensitivity. Thus, we developed a larger coil (24¯30 cm2) designed to be embedded in the back of a vest to power DC pumps for artificial hearts or LVADs. To significantly reduce the required voltage, the coil was divided into 8 segments with resonant capacitors. The coil was operated at 6.78 MHz and evaluated with a 5.3-cm diameter receiving coil. A circuit model for the energy coupling coils was developed to predict the output power and efficiency. Having a coil separation of 7.7 cm, the output power and efficiency of the energy coupling coils are higher than 48 W and 80%, respectively. The system was experimentally tested with a DC pump, demonstrating that the proposed coil segmentation technique can significantly reduce the transmitter voltage to a safe level (~10 Vrms)

Phylogenetic analysis of Blaberoidea reveals non‐monophyly of taxa and supports the creation of multiple new subfamilies

The superfamily Blaberoidea is a highly species-rich group of cockroaches. High-level blaberoidean phylogenetics are still under debate owing to variable taxon sampling and incongruence between mitochondrial and nuclear evolution, as well as different methods used in various phylogenetic studies. We here present a phylogenetic analysis of Blaberoidea based on a dataset combining the mitochondrial genome with two nuclear markers from representatives of all recognized families within the superfamily. Our results support the monophyly of Blaberiodea, which includes Ectobiidae s.s. (=Ectobiinae), Pseudophyllodromiidae, Nyctiboridae, Blattellidae s.s. (=Blattellinae) and Blaberidae. Ectobiidae s.s. was recovered as sister to the remaining Blaberoidea in all inferences. Pseudophyllodromiidae was paraphyletic with respect to Anaplectoidea + Malaccina. Blattellidae s.s. excluding Anaplectoidea + Malaccina formed a monophyletic group that was sister to Blaberidae. Based on our results, we propose a revised classification for Blaberoidea: Anaplectoidinae subfam.nov. and Episorineuchora gen.nov., and two new combinations at species level within Pseudophyllodromiidae; Rhabdoblattellinae subfam.nov., Calolamprodinae subfam.nov., Acutirhabdoblatta gen.nov., as well as new combinations for three species within Blaberidae. Ancestral state reconstructions based on four morphological characters allow us to infer that the common ancestor of blaberoid cockroaches is likely to be a species with characteristics similar to those found in Ectobiidae, that is, front femur Type B, arolium present, abdomen with a visible gland and male genital hook on the left side.journal articl

Morphological Evolution and Dealloying During Corrosion of Ni20Cr (wt.%) in Molten FLiNaK Salts

The dealloying corrosion behavior of the FCC Ni20Cr (wt%) in molten LiF-NaF-KF (FLiNaK) salts at 600 °C under varying applied potentials was investigated. Using in-operando electrochemical techniques and a multi-modal suite of characterization methods, we connect electrochemical potential, thermodynamic stability, and electro-dissolution kinetics to the corrosion morphologies. Notably, under certain potential regimes, a micron-scale bicontinuous structure, characterized by a network of interconnected pores and ligaments riched with the composition of the more noble (MN) element, becomes prominent. At other potentials both MN and less noble (LN) elements dealloy but at different rates. The dealloying process consists of lattice and grain boundary diffusion of Cr to the metal/salt interface, interphase Cr oxidation, accompanied by surface diffusion of Ni to form interconnected ligaments. At higher potentials, the bicontinuous porous structure undergoes further surface coarsening. Concurrently, Cr(II), Cr(III), and Ni(II) begin to dissolve, with the dissolution of Ni occurring at a significantly slower rate. When solid-state transport of Cr is exceeded by the interfacial rates, dealloying depths are limited

Concurrent photocatalytic degradation of organic contaminants and photocathodic protection of steel Ag–TiO2 composites

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.mtla.2018.08.033 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/In this study, coupled titanium dioxide-silver composite and steel electrode pairs were investigated for their use in cathodic protection under illuminated and dark conditions to prevent corrosion and enhance contaminant degradation under photocatalysis. A series of photoelectrochemical tests were used to determine the properties of the photoanode and identify the cathodic protection behaviour in the presence and absence of organic/inorganic contaminants. Additionally, corrosion-prone steel was used to test the principle of photocathodic protection in reducing oxide formation and mass loss under base metal and welded materials.Natural Sciences and Engineering Research Council of Canada [STPG-494554-2016]Schwartz-Reisman Foundation through the Waterloo Institute of Nanotechnology − Technion University gran

Photodynamic therapy augments the efficacy of oncolytic vaccinia virus against primary and metastatic tumours in mice

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OptForce: An Optimization Procedure for Identifying All Genetic Manipulations Leading to Targeted Overproductions

Computational procedures for predicting metabolic interventions leading to the overproduction of biochemicals in microbial strains are widely in use. However, these methods rely on surrogate biological objectives (e.g., maximize growth rate or minimize metabolic adjustments) and do not make use of flux measurements often available for the wild-type strain. In this work, we introduce the OptForce procedure that identifies all possible engineering interventions by classifying reactions in the metabolic model depending upon whether their flux values must increase, decrease or become equal to zero to meet a pre-specified overproduction target. We hierarchically apply this classification rule for pairs, triples, quadruples, etc. of reactions. This leads to the identification of a sufficient and non-redundant set of fluxes that must change (i.e., MUST set) to meet a pre-specified overproduction target. Starting with this set we subsequently extract a minimal set of fluxes that must actively be forced through genetic manipulations (i.e., FORCE set) to ensure that all fluxes in the network are consistent with the overproduction objective. We demonstrate our OptForce framework for succinate production in Escherichia coli using the most recent in silico E. coli model, iAF1260. The method not only recapitulates existing engineering strategies but also reveals non-intuitive ones that boost succinate production by performing coordinated changes on pathways distant from the last steps of succinate synthesis

In COVID-19 Health Messaging, Loss Framing Increases Anxiety with Little-to-No Concomitant Benefits: Experimental Evidence from 84 Countries

The COVID-19 pandemic (and its aftermath) highlights a critical need to communicate health information effectively to the global public. Given that subtle differences in information framing can have meaningful effects on behavior, behavioral science research highlights a pressing question: Is it more effective to frame COVID-19 health messages in terms of potential losses (e.g., "If you do not practice these steps, you can endanger yourself and others") or potential gains (e.g., "If you practice these steps, you can protect yourself and others")? Collecting data in 48 languages from 15,929 participants in 84 countries, we experimentally tested the effects of message framing on COVID-19-related judgments, intentions, and feelings. Loss- (vs. gain-) framed messages increased self-reported anxiety among participants cross-nationally with little-to-no impact on policy attitudes, behavioral intentions, or information seeking relevant to pandemic risks. These results were consistent across 84 countries, three variations of the message framing wording, and 560 data processing and analytic choices. Thus, results provide an empirical answer to a global communication question and highlight the emotional toll of loss-framed messages. Critically, this work demonstrates the importance of considering unintended affective consequences when evaluating nudge-style interventions

A global experiment on motivating social distancing during the COVID-19 pandemic

Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e., a controlling message) compared with no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared with the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing. Controlled motivation was associated with more defiance and less long-term behavioral intention to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges