Gene co-expression network analysis in zebrafish reveals chemical class specific modules

Background Zebrafish is a popular animal model used for high-throughput screening of chemical hazards, however, investigations of transcriptomic mechanisms of toxicity are still needed. Here, our goal was to identify genes and biological pathways that Aryl Hydrocarbon Receptor 2 (AHR2) Activators and flame retardant chemicals (FRCs) alter in developing zebrafish. Taking advantage of a compendium of phenotypically-anchored RNA sequencing data collected from 48-h post fertilization (hpf) zebrafish, we inferred a co-expression network that grouped genes based on their transcriptional response. Results Genes responding to the FRCs and AHR2 Activators localized to distinct regions of the network, with FRCs inducing a broader response related to neurobehavior. AHR2 Activators centered in one region related to chemical stress responses. We also discovered several highly co-expressed genes in this module, including cyp1a, and we subsequently show that these genes are definitively within the AHR2 signaling pathway. Systematic removal of the two chemical types from the data, and analysis of network changes identified neurogenesis associated with FRCs, and regulation of vascular development associated with both chemical classes. We also identified highly connected genes responding specifically to each class that are potential biomarkers of exposure. Conclusions Overall, we created the first zebrafish chemical-specific gene co-expression network illuminating how chemicals alter the transcriptome relative to each other. In addition to our conclusions regarding FRCs and AHR2 Activators, our network can be leveraged by other studies investigating chemical mechanisms of toxicity.

INVESTIGATIONOF FRICTION COEFFICIENTOF DRAPERY FABRICS TREATED WITH DIFFERENT RATIO OF FLAME RETARDANT

As the security precautions with respect to new standards for the furnishing textiles in big platforms such as concert, theatre halls have increased, flame retardancy has become one of the vital required property for drapery fabrics. However, those kind of additional treatment processes may lead to some differences in fabric properties such as friction which should be considered for the consumers. This study aims to evaluate the influence of using different ratio of flame retardant chemicals (g/l) on friction coefficient of drapery fabrics. For this purpose, nine types of fabrics composed of three different weft density (9, 11, 13 threads/cm) were selected. The warp yarns were selected as 400/200 denier/filament while the weft yarns were selected as 800 /200 denier/filament textured micro polyester yarns. Three levels for flame retardant (0, 60 and 90 g/l) were determined as the finishing processes. After the dobby fabrics were woven and exposed to finishing treatments; Friction coefficient values were recorded with Labthink Param MXD-02. ANOVA tests were performed in order to evaluate the significant effect of weft density and flame retardant chemical ratio on friction properties of drapery fabrics. Additionally, SNK tests were conducted for the comparison of means of friction values of drapery fabrics produced at different weft density also of the samples treated with different flame retardant chemical ratio. Experimental results revealed that structural parameters and the finishing processes were influential factors on the surface frictional characteristics of the fabrics. It was clearly observed that surface friction coefficients of drapery fabrics decreased due to the flame retardant process.

Assessing fire-blocking effectiveness of barrier fabrics in the cone calorimeter

Cone calorimetry experiments of on flexible polyurethane foam and flexible polyurethane foam covered with a variety of fire-blocking barrier fabrics were used to characterize and rank the effectiveness of barrier fabrics with the ultimate goal being an ability to predict the effectiveness of barrier fabrics for reducing the flammability of residential upholstered furniture. The primary measure used to characterize the burning behavior was heat release rate. The effect of the underlying sample substrate was shown to have a large effect on the burning behavior of flexible polyurethane foam samples, and a thermally insulating substrate was used during composite experiments. At times, rapid heat release rate fluctuations were observed, and in such cases approximate corrections were applied to correct for finite cone calorimeter time response. Measurements using thermocouples placed within the flexible polyurethane foam provided insights on flexible polyurethane foam pyrolysis behavior, the collapse rate of flexible polyurethane foam, and the thermal protective properties of barrier materials. Heat release rate temporal profiles for flexible polyurethane foam showed two distinct burning stages with peak values which have been attributed to sequential burning of species (primarily) derived from the diamine ( PHRR1) and polyol components ( PHRR2) used to manufacture the flexible polyurethane foam. When a barrier fabric was added, many of the composites displayed a three-stage burning behavior which was attributed to an initial short, intense burning (termed flash burning) stage associated with the barrier fabric covering followed by the two flexible polyurethane foam stages. Seven out of 16 flexible polyurethane foam/barrier fabric composites exhibited flame extinction prior to fuel burn out. Five out of the seven composites reignited when the spark ignition source was reapplied. Reignition allowed barrier fabric effectiveness to be assessed even for cases with flame extinction. Barrier fabric performance was shown to be consistent with four properties that were previously identified as important barrier fabric properties: barrier fabric flammability, gas permeability, thermal protection, and physical integrity. In addition, the current experiments indicate the presence and effectiveness of gas-phase active flame retardants in the barrier fabric can also play an important role. A limited number of tests were conducted to de-couple the effects of flame-retardant chemicals and physical effects of barrier fabrics on flexible polyurethane foam burning behavior. These tests showed that while flame-retardant chemicals can be effective in quenching and extinguishing the flames, the presence of effective barrier fabric shells is also very important in lowering the heat release rate of burning flexible polyurethane foam. In general, the presence of a barrier fabric was shown to reduce the heat release rate peak values during both flexible polyurethane foam burning stages. The magnitude of the peak associated with second-stage flexible polyurethane foam burning was deemed the most appropriate for characterizing the thermal protection provided by a barrier fabric. Since the times for PHRR2 also varied between composites, a measurement referred to as the peak fire growth rate (PFIGRA) parameter was calculated by dividing the heat release rate by time since time to ignition and PFIGRA2 was also considered for characterizing the barrier fabrics. Three possible classification schemes, each consisting of three classes, were introduced based on composite flame extinction and reignition behavior, PHRR2 values, and PFIGRA2 values. Each scheme provided differentiation between barrier fabric effectiveness. While the schemes were able to assess whether the barrier fabrics were particularly effective or ineffective, there were variations among classes of barrier fabrics having intermediate levels of effectiveness. Further work will be required to assess which, if any, of the classification schemes are most appropriate for predicting barrier fabric performance in residential upholstered furniture.

Novel Environmental Friendly Fire Retardants

Nowadays flame-retardant chemicals are mandatory in many products worldwide, flame-retardant chemicals are mandatory in many products worldwide, since they protect human life and property. Over the past few decades the use of flame-retardant chemicals has increase. Flame-retardant polymeric materials have spawned huge research interest in both scientific and industrial communities due to their broad range of applications in the fields of aviation, automotive industry, construction, electronics and telecommunications. The use of conventional FRs to meet the fire safety standards is of serious importance as they ultimately yield POPs of global concern. Considering eco-friendliness and other required properties, unsatisfactory fire performance is a major obstacle. The aim of this article is to provide an overview of traditional, commonly used flame retardants, as well as an overview of new, more environmentally acceptable alternatives.