Passive concentration dynamics incorporated into the library IB2d, a two-dimensional implementation of the immersed boundary method

In this paper, we present an open-source software library that can be used to numerically simulate the advection and diffusion of a chemical concentration or heat density in a viscous fluid where a moving, elastic boundary drives the fluid and acts as a source or sink. The fully- coupled fluid-structure interaction problem of an elastic boundary in a viscous fluid is solved using Peskin’s immersed boundary method. The addition or removal of the concentration or heat density from the boundary is solved using an immersed boundary-like approach in which the concentration is spread from the immersed boundary to the fluid using a regularized delta function. The concentration or density over time is then described by the advection-diffusion equation and numerically solved. This functionality has been added to our software library, IB2d, which provides an easy-to-use immersed boundary method in two dimensions with full implementations in MATLAB and Python. We provide four examples that illustrate the usefulness of the method. A simple rubber band that resists stretching and absorbs and releases a chemical concentration is simulated as a first example. Complete convergence results are presented for this benchmark case. Three more biological examples are presented: (1) an oscillating row of cylinders, representative of an idealized appendage used for filter-feeding or sniffing, (2) an oscillating plate in a background flow is considered to study the case of heat dissipation in a vibrating leaf, and (3) a simplified model of a pulsing soft coral where carbon dioxide is taken up and oxygen is released as a byproduct from the moving tentacles. This method is applicable to a broad range of problems in the life sciences, including chemical sensing by antennae, heat dissipation in plants and other structures, the advection-diffusion of morphogens during development, filter-feeding by marine organisms, and the release of waste products from organisms in flows.

Retrieving Tarnished Daguerreotype Content Using X-ray Fluorescence Imaging—Recent Observations on the Effect of Chemical and Electrochemical Cleaning Methods

We report a study on the effect of chemical and electrochemical cleaning of tarnished daguerreotypes observed using X-ray fluorescence (XRF) microscopy with a micro-focussed X-ray beam from a synchrotron source. It has been found that, while both techniques result in some success depending on the condition of the plate and the experimental parameters (chemical concentration, voltage, current, etc.) the effect varies, and cleaning is often incomplete. The XRF images using Hg Lα,β at an excitation energy just above the L3 edge threshold produce fine images, regardless of the treatment. This finding confirms previous observations that if the bulk of the image particles remains intact, the surface tarnish has little effect on the quality of the original daguerreotype image retrievable from XRF.

Dip Degreasing Stage Improvement in Car Body Pretreatment Process by Six Sigma

An automobile company in this research faced the consistency problem from the chemical concentration in degreasing bath which was one of the stages in the pretreatment process. The problem came from the proportion of total alkaline (T.Al) lower than the lower control limit (LCL) which was set at 18.2 points during February – May 2020. This resulted in the low values of Cp and Cpk, i.e. 0.83 and 0.51, respectively. To remedy the problem, Six Sigma (DMAIC) was applied to improve the process stability. The cause and effect matrix was used to analyse the potential causes of problems and prioritise the causes to solve. It was found that four (causes) factors were solved by auto titration and feeding controller installation to reduce variance and increase stability. Another one factor, quality of water, was improved by adding a check item to monitor and collect data during the initial implementation stage. The result after improvement showed that Cp and Cpk were increased to 1.82 and 1.52 in August 2020, respectively.

Response of Culex pipiens pallens to Visual and Olfactory Stimuli from a Mosquito Trap

ABSTRACT This study examined Culex pipiens pallens responses to different combinations of colors and chemicals employed via a mosquito trap under semifield conditions. Our results indicated that Cx. p. pallens has color and chemical concentration preferences. Culex p. pallens had a 38.0% greater response to white than black color treated traps. Further, Cx. p. pallens showed differences in olfactory attraction depending on the chemical and concentration. Culex p. pallens was 107.6% more attracted to traps employing 500 ppm ammonia than control (i.e., unscented). Similarly, Cx. p. pallens was 117.5%, 128.8%, and 140.3% more attracted to traps employing, respectively, 1,000, 10,000, and 20,000 ppm of ammonia hydrogen carbonate compared to controls. And the response to lactic acid showed that Cx. p. pallens was most attracted to concentrations of 100 and 500 ppm (135.7% and 142.9%, respectively) compared to controls.

Controlled electrospray generation of non-spherical alginate microparticles

Electrospraying is a technique used to generate microparticles in a high throughput manner. For biomedical applications, a biocompatible electrosprayed material is often desirable. Using polymers, such as alginate hydrogels, makes it possible to create biocompatible and biodegradable microparticles that can be used for cell encapsulation, to be employed as drug carriers, and for use in 3D cell culturing. Evidence in the literature suggests that the morphology of the biocompatible microparticles is relevant in controlling the dynamics of the microparticles in drug delivery and 3D cell culturing applications. Yet, most electrospray-based techniques only form spherical microparticles, and there is currently no widely adopted technique for producing non-spherical microparticles at a high throughput. Here, we demonstrate the generation of non-spherical biocompatible alginate microparticles by electrospraying, and control the shape of the microparticles by varying experimental parameters such as chemical concentration and the distance between the electrospray tip and the particle-solidification bath. Importantly, we show that these changes to the experimental setup enable the synthesis of different shaped particles, and the systematic change in parameters, such as chemical concentration, result in monotonic changes to the particle aspect ratio. We expect that these results will find utility in many biomedical applications that require biocompatible microparticles of specific shapes.

Applications of toxicokinetic (TK) models on freshwater invertebrates in a regulation perspective

Toxicokinetic (TK) models have been developed to describe the bioaccumulation of chemicals in organisms. They are used as the first step to evaluate the toxicity of a contaminant in environmental risk assessment (ERA) and are developed to provide a theorical framework for understanding the link between exposure and accumulation by the biota, testing hypotheses, and make predictions (e.g. predictions of the chemical concentration in organisms according to environmental concentration or inversely). In France, polycyclic aromatic hydrocarbons (PAH) have generally been analyzed in sediment as part of annual monitoring. However, regulation specifies that for PAHs, the environmental quality standard (EQS) concerns biota, in this case invertebrates. However, modifying the monitoring protocol used for several years would lead to a loss of data continuity. In this context, TK models could be used to predict ( i) concentrations in the sediment equivalent to the EQS biota and ( ii) concentrations in biota, directly from data measured in sediment in situ, then compared to the EQS biota. Thus, the aim of this study was to illustrate how to use TK models to retro-predict chemical concentrations in the sediment leading to the EQS biota. To achieve this purpose, we firstly used experimental data of a TK study available in the literature (e.g. Hyallela azteca and Chironomustentans exposed to benzo(a)pyrene (BaP) spiked sediment) to estimate the distributions of the model parameters and thus to predict the concentration in the sediment that will lead to a concentration in the biota below the corresponding EQS biota (for both BaP and its metabolites). The results raised the issue of taking into account metabolites in regulation, where their concentrations in the organism could exceed the EQS biota defined for the parent compound. Secondly, we used several experimental data of TK studies which reported different amount of organic matter to account for the bioavailability of PAH in the model.

Insight Into Hartoušov Mofette, Czech Republic: Tales by the Fluids

The Cheb Basin (Czech Republic) is characterized by emanations of magma-derived gases and repeated occurrences of mid-crustal earthquake swarms with small to intermediate magnitudes (ML < 4.5). Associated intense mantle degassing occurs at the Hartoušov Mofette, a representative site for the Cheb Basin. Here, we performed 14 sampling campaigns between June 2019 and March 2020. Gas samples of fluids ascending in two boreholes (F1, ∼28 m depth and F2, ∼108 m depth) and from a nearby natural mofette were analyzed for their chemical (CO2, N2, O2, Ar, He, CH4, and H2) and isotope compositions (noble gases and CO2). CO2 concentrations were above 99.1% in most samples, while O2 and N2 were below 0.6%. He ranged from 19 to 34 μmol/mol and CH4 was mostly below 12 μmol/mol. Isotope compositions of helium and carbon in CO2 ranged from 5.39 to 5.86 RA and from −2.4 to −1.3 ‰ versus VPDB, respectively. Solubility differences of the investigated gases resulted in fluctuations of their chemical compositions. These differences were accompanied by observed changes of gas fluxes in the field and at the monitoring station for F1. Variations in solubilities and fluxes also impacted the chemical concentration of the gases and the δ13C values that were also likely influenced by Fischer-Tropsch type reactions. The combination of (a) the Bernard ratio, (b) CH4/3He distributions, (c) P-T conditions, (d) heat flow, and (e) the sedimentary regime led to the hypothesis that CH4 may be of mixed biogenic and volcanic/geothermal origin with a noticeable atmospheric contribution. The drilling of a third borehole (F3) with a depth of ∼238 m in August 2019 has been crucial for providing insights into the complex system of Hartoušov Mofette.

Existence and Uniqueness of Weak Solution for chemotaxis model coupled with heat equation

Keller-Segel chemotaxis model is described by a system of nonlinear PDE : a convection diffusion equation for the cell density coupled with a reaction-diffusion equation for chemoattractant concentration. In this work, we study the phenomenon of Keller Segel model coupled with a heat equation, because The heat has an effect the density of the cells as well as the signal of chemical concentration, since the heat is a factor affecting the spread and attraction of cells as well in relation to the signal of chemical concentration, The main objectives of this work is the study of the global existence and uniqueness and boundedness of the weak solution for the problem defined in (8) for this we use the technical of Galerkin method.

Chemotactic TEG3 Cells’ Guiding Platforms Based on PLA Fibers Functionalized With the SDF-1α/CXCL12 Chemokine for Neural Regeneration Therapy

(Following spinal cord injury, olfactory ensheathing cell (OEC) transplantation is a promising therapeutic approach in promoting functional improvement. Some studies report that the migratory properties of OECs are compromised by inhibitory molecules and potentiated by chemical concentration differences. Here we compare the attachment, morphology, and directionality of an OEC-derived cell line, TEG3 cells, seeded on functionalized nanoscale meshes of Poly(l/dl-lactic acid; PLA) nanofibers. The size of the nanofibers has a strong effect on TEG3 cell adhesion and migration, with the PLA nanofibers having a 950 nm diameter being the ones that show the best results. TEG3 cells are capable of adopting a bipolar morphology on 950 nm fiber surfaces, as well as a highly dynamic behavior in migratory terms. Finally, we observe that functionalized nanofibers, with a chemical concentration increment of SDF-1α/CXCL12, strongly enhance the migratory characteristics of TEG3 cells over inhibitory substrates.