Characterizing variations in ambient PM2.5 concentrations at the U.S. Embassy in Dhaka, Bangladesh using observations and the CMAQ modeling system.

We analyze hourly PM2.5 (particles with an aerodynamic diameter of ≤ 2.5 µm) concentrations measured at the U.S. Embassy in Dhaka over the 2016 - 2021 time period and find that concentrations are seasonally dependent with the highest occurring in winter and the lowest in monsoon seasons. Mean winter PM2.5 concentrations reached ~165-175 µg/m3 while monsoon concentrations remained ~30-35 µg/m3. Annual mean PM2.5 concentration reached ~5-6 times greater than the Bangladesh annual PM2.5 standard of 15 µg/m3. The number of days exceeding the daily PM2.5 standard of 65 µg/m3 in a year approached nearly 50%. Daily-mean PM2.5 concentrations remained elevated (>65 µg/m3) for more than 80 consecutive days. Night-time concentrations were greater than daytime concentrations. The comparison of results obtained from the Community Multiscale Air Quality (CMAQ) model simulations over the Northern Hemisphere using 108-km horizontal grids with observed data suggests that the model can reproduce the seasonal variation of observed data but underpredicts observed PM2.5 in winter months with a normalized mean bias of 13-32%. In the model, organic aerosol is the largest component of PM2.5, of which secondary organic aerosol plays a dominant role. Transboundary pollution has a large impact on the PM2.5 concentration in Dhaka, with an annual mean contribution of ~40 µg/m3.

Skipping the skippable: An empirical study with out-of-sample predictive relevance.

PURPOSE: This explanatory research aims to describe the factors that impact YouTube ad intrusiveness, value, and avoidance in light of psychological reactance theory. RESEARCH DESIGN: The research has a causal-predictive design. It describes the relationship between the construct with an underpinning theory. Data from a sample of 294 respondents were analyzed using partial least square structural equation modeling to test within sample explanatory power and out-of-sample prediction power. FINDINGS: The results show that informativeness does not significantly impact intrusiveness and ad avoidance. Entertainment has a negative direct and mediated impact on ad avoidance. Moreover, irritation was found to moderate the impact of informativeness on intrusiveness negatively. Importance-Performance Map Analysis revealed that entertainment lacks in performance despite being an essential factor. Besides explanatory power, the model has a moderate out-of-sample predictive relevance power. PRACTICAL IMPLICATIONS: The relative importance of the entertainment and interactive impact of irritation with informativeness is established for the first time in this study. The new finding is a significant contribution to theory while leading to practical implications for the industry.

A modified approach to Industrial Pollution Projection System for the assessment of sectoral pollution loads in Bangladesh.

Industrial pollution in Bangladesh has posed a serious threat to human health, economic activity, and the environment. By emphasizing industries that produce major pollutants, substantial improvements can be made to pollution mitigation measures. In countries where primary pollution data is not readily available, the Industrial Pollution Projection System (IPPS) could be used to calculate the pollution load utilizing total industrial output or employment data. IPPS data, which was designed for developed countries like the USA, had been used directly for other countries without any normalization in previously reported studies. The main purpose of this study is to modify the current IPPS approach for any other country by incorporating specific correction factor for a specific country. In this study, a specific correction factor for Bangladesh was determined, taking into account the country's major polluting industries, and used to estimate the pollution scenario for the year 2020. The accuracy of the specific pollution intensities was also evaluated by comparing the data obtained using both gross output and employee number. According to this study, the top three air-polluting industries are structural clay products, cement-lime-plaster industry, and iron and steel industry. Similarly, for water pollution, the food industry, paper and paper product industry, and textile industry are the largest pollutant contributors. The detailed pollution load matrix in terms of air and water pollution is also developed, and can be used to predict both short-term and long-term scenarios of industrial pollution in Bangladesh, which eventually will assist the policy makers to adopt appropriate pollution management approach. Moreover, the methods developed in this study will help to tailor the IPPS data for any country and increase the accuracy of the pollution load.

Incorporating ash removal unit in local rice parboiling industries for flue gas cleaning and heat recovery.

Local rice parboiling industries of Bangladesh are burdened with heavy emission. Despite recent modification in the rice-parboiling boiler, the amount of stack emission (especially particulate matter) from local rice parboiling industry is still considerably high to jeopardize public health and environmental sustainability. There is no provision of flue gas cleaning in these industries since flue gas cleaning often requires significant investment, complicated installation and heavy-maintenance. Therefore, a modified flue gas cleaning system, namely Ash removal unit (ARU) was designed for simultaneously and synergistically removing particulate matter (PM), SO2, NOx, CO2 and heat from flue gas of local rice parboiling industries. In this study, ARU was incorporated in a local rice parboiling industry in order to evaluate the co-removal efficiency achieved by the ARU. Installation of ARU eliminated PM from flue gas by 91.8%, while it removed 78.5% SO2, 78.3% NOx and 23.9% CO2 respectively from the emitting stack. Other than flue gas cleaning , ARU also facilitates heat exchange between flue gas and boiler feed water. Hence, flue gas temperature was dropped by 42.1%, while boiler feed water temperature was raised by 36% in 30 min. Moreover, adopting ARU also improved the ambient air quality surrounding the industrial area, since it reduced SO2, NOx, SPM, PM2.5 and PM10 level in ambient air by 81.7%, 78.2%, 21.1%, 22.9% and 43.1% respectively.

Data-driven modeling reconciles kinetics of ERK phosphorylation, localization, and activity states.

The extracellular signal-regulated kinase (ERK) signaling pathway controls cell proliferation and differentiation in metazoans. Two hallmarks of its dynamics are adaptation of ERK phosphorylation, which has been linked to negative feedback, and nucleocytoplasmic shuttling, which allows active ERK to phosphorylate protein substrates in the nucleus and cytosol. To integrate these complex features, we acquired quantitative biochemical and live-cell microscopy data to reconcile phosphorylation, localization, and activity states of ERK. While maximal growth factor stimulation elicits transient ERK phosphorylation and nuclear translocation responses, ERK activities available to phosphorylate substrates in the cytosol and nuclei show relatively little or no adaptation. Free ERK activity in the nucleus temporally lags the peak in nuclear translocation, indicating a slow process. Additional experiments, guided by kinetic modeling, show that this process is consistent with ERK's modification of and release from nuclear substrate anchors. Thus, adaptation of whole-cell ERK phosphorylation is a by-product of transient protection from phosphatases. Consistent with this interpretation, predictions concerning the dose-dependence of the pathway response and its interruption by inhibition of MEK were experimentally confirmed.

Manipulating epigenetic diversity in crop plants: Techniques, challenges and opportunities.

Epigenetic modifications act as conductors of inheritable alterations in gene expression, all while keeping the DNA sequence intact, thereby playing a pivotal role in shaping plant growth and development. This review article presents an overview of techniques employed to investigate and manipulate epigenetic diversity in crop plants, focusing on both naturally occurring and artificially induced epialleles. The significance of epigenetic modifications in facilitating adaptive responses is explored through the examination of how various biotic and abiotic stresses impact them. Further, environmental chemicals are explored for their role in inducing epigenetic changes, particularly focusing on inhibitors of DNA methylation like 5-AzaC and zebularine, as well as inhibitors of histone deacetylation including trichostatin A and sodium butyrate. The review delves into various approaches for generating epialleles, including tissue culture techniques, mutagenesis, and grafting, elucidating their potential to induce heritable epigenetic modifications in plants. In addition, the ground breaking CRISPR/Cas is emphasized for its accuracy in targeting specific epigenetic changes. This presents a potent tools for deciphering the intricacies of epigenetic mechanisms. Furthermore, the intricate relationship between epigenetic modifications and non-coding RNA expression, including siRNAs and miRNAs, is investigated. The emerging role of exo-RNAi in epigenetic regulation is also introduced, unveiling its promising potential for future applications. The article concludes by addressing the opportunities and challenges presented by these techniques, emphasizing their implications for crop improvement. Conclusively, this extensive review provides valuable insights into the intricate realm of epigenetic changes, illuminating their significance in phenotypic plasticity and their potential in advancing crop improvement.

Recent development in antiviral surfaces: Impact of topography and environmental conditions.

The transmission of viruses is largely dependent on contact with contaminated virus-laden communal surfaces. While frequent surface disinfection and antiviral coating techniques are put forth by researchers as a plan of action to tackle transmission in dire situations like the Covid-19 pandemic caused by SARS-CoV-2 virus, these procedures are often laborious, time-consuming, cost-intensive, and toxic. Hence, surface topography-mediated antiviral surfaces have been gaining more attention in recent times. Although bioinspired hydrophobic antibacterial nanopatterned surfaces mimicking the natural sources is a very prevalent and successful strategy, the antiviral prospect of these surfaces is yet to be explored. Few recent studies have explored the potential of nanopatterned antiviral surfaces. In this review, we highlighted surface properties that have an impact on virus attachment and persistence, particularly focusing and emphasizing on the prospect of the nanotextured surface with enhanced properties to be used as antiviral surface. In addition, recent developments in surface nanopatterning techniques depending on the nano-scaled dimensions have been discussed. The impacts of environments and surface topology on virus inactivation have also been reviewed.

Synthesis, characterization, and comparative assessment of antimicrobial properties and cytotoxicity of graphene-, silver-, and zinc-based nanomaterials.

Zinc oxide (ZnO) and graphene oxide (GO) nanoparticles, silver/zinc zeolite (Ag/Zn-Ze), and graphene oxide-silver (GO-Ag) nanocomposites were synthesized and characterized with X-ray powder Diffraction, Field Emission Scanning Electron Microscope and Fourier Transform-Infrared Spectroscopy. The antibacterial efficacy of these nanoparticles was evaluated against E. coli. by shake flask method and plate culture method for different concentrations. For 105 cells/mL initial bacterial concentration, minimum inhibitory concentration (MIC) were <160, <320, <320, and >1280 µg/mL, and antibacterial concentration at which 50% cells are inhibited (IC50) were 47, 90, 78, and 250 µg/mL for Ag/Zn-Ze, GO, GO-Ag, and ZnO, respectively. Therefore, the shake flask method showed that for all nanoparticle concentrations, Ag/Zn-Ze, and GO-Ag exhibited greater inhibition efficacy, which was also highly dependent on initial bacterial concentration. However, in case of the plate culture method, similar range of inhibition capacity was found for Ag/Zn-Ze, GO-Ag, and ZnO, whereas GO showed lower potency to inhibit E. coli. In addition, GO-Ag nanocomposite exhibited more efficacy than Ag/Zn-Ze when the antibacterial surface was prepared with those. However, Ag/Zn-Ze showed no toxicity on Vero cells, whereas GO-Ag exhibited severe toxicity at higher concentrations. This study establishes GO-Ag and Ag/Zn-Ze as potent antimicrobial agents; however, their application dosage should carefully be chosen based on cytotoxic effects of GO-Ag in case of any possible physiological interaction.

Poly(vinylmethylsiloxane) elastomer networks as functional materials for cell adhesion and migration studies.

Cell migration is central to physiological responses to injury and infection and in the design of biomaterial implants. The ability to tune the properties of adhesive materials and relate those properties in a quantitative way to the dynamics of intracellular processes remains a definite challenge in the manipulation of cell migration. Here, we propose the use of poly(vinylmethylsiloxane) (PVMS) networks as novel substrata for cell adhesion and migration. These materials offer the ability to tune independently chemical functionality and elastic modulus. Importantly, PVMS networks are compatible with total internal reflection fluorescence (TIRF) microscopy, which is ideal for interrogating the cell-substratum interface; this latter characteristic presents a distinct advantage over polyacrylamide gels and other materials that swell with water. To demonstrate these capabilities, adhesive peptides containing the arginyl-glycyl-aspartic acid (RGD) tripeptide motif were successfully grafted to the surface of PVMS network using a carboxyl-terminated thiol as a linker. Peptide-specific adhesion, spreading, and random migration of NIH 3T3 mouse fibroblasts were characterized. These experiments show that a peptide containing the synergy sequence of fibronectin (PHSRN) in addition to RGD promotes more productive cell migration without markedly enhancing cell adhesion strength. Using TIRF microscopy, the dynamics of signal transduction through the phosphoinositide 3-kinase pathway were monitored in cells as they migrated on peptide-grafted PVMS surfaces. This approach offers a promising avenue for studies of directed migration and mechanotransduction at the level of intracellular processes.

Chitooligosaccharides and their structural-functional effect on hydrogels: A review.

Chitosan's lack of solubility in physiological pH and high molecular weight (MW) limits its use in hydrogel scaffolds. Conversion of chitosan to low MW chitooligosaccharides (COS) not only imparts water solubility, it also enhances several other biological properties. When used in hydrogels, the low MW improves the performance of the hydrogels, e.g., the absorptive property, biocompatibility and cell proliferation capability. Most importantly, properties of COS, namely the degree of polymerization (DP) and degree of deacetylation (DD), can be altered to support specific functions in hydrogels used in regenerative medicine. Methods of preparation of COS must therefore be simple and convenient, leading to COS that can be readily used in biomedical applications without requiring extensive post-purification. This review compares these various methods of production of COS and discusses critically the specific advantages that COS can lend to hydrogels, which make COS better alternatives to chitosan in cell-related applications.

Directional persistence of cell migration coincides with stability of asymmetric intracellular signaling.

It has long been appreciated that spatiotemporal dynamics of cell migration are under the control of intracellular signaling pathways, which are mediated by adhesion receptors and other transducers of extracellular cues. Further, there is ample evidence that aspects of cell migration are stochastic: how else could it exhibit directional persistence over timescales much longer than typical signal transduction processes, punctuated by abrupt changes in direction? Yet the mechanisms by which signaling processes affect those behaviors remain unclear. We have developed analytical methods for relating parallel live-cell microscopy measurements of cell migration dynamics to the intracellular signaling processes that govern them. In this analysis of phosphoinositide 3-kinase signaling in randomly migrating fibroblasts, we observe that hot spots of intense signaling coincide with localized cell protrusion and endure with characteristic lifetimes that correspond to those of cell migration persistence. We further show that distant hot spots are dynamically and stochastically coupled. These results are indicative of a mechanism by which changes in a cell's direction of migration are determined by a fragile balance of relatively rapid intracellular signaling processes.

Design and evaluation of engineered protein biosensors for live-cell imaging of EGFR phosphorylation.

Live-cell fluorescence microscopy is broadly applied to study the dynamics of receptor-mediated cell signaling, but the availability of intracellular biosensors is limited. A biosensor based on the tandem SH2 domains from phospholipase C-γ1 (PLCγ1), tSH2-WT, has been used to measure phosphorylation of the epidermal growth factor receptor (EGFR). Here, we found that tSH2-WT lacked specificity for phosphorylated EGFR, consistent with the known promiscuity of SH2 domains. Further, EGF-stimulated membrane recruitment of tSH2-WT differed qualitatively from the expected kinetics of EGFR phosphorylation. Analysis of a mathematical model suggested, and experiments confirmed, that the high avidity of tSH2-WT resulted in saturation of its target and interference with EGFR endocytosis. To overcome the apparent target specificity and saturation issues, we implemented two protein engineering strategies. In the first approach, we screened a combinatorial library generated by random mutagenesis of the C-terminal SH2 domain (cSH2) of PLCγ1 and isolated a mutant form (mSH2) with enhanced specificity for phosphorylated Tyr992 (pTyr992) of EGFR. A biosensor based on mSH2 closely reported the kinetics of EGFR phosphorylation but retained cross-reactivity similar to tSH2-WT. In the second approach, we isolated a pTyr992-binding protein (SPY992) from a combinatorial library generated by mutagenesis of the Sso7d protein scaffold. Compared to tSH2-WT and mSH2, SPY992 exhibited superior performance as a specific, moderate-affinity biosensor. We extended this approach to isolate a biosensor for EGFR pTyr1148 (SPY1148). This approach of integrating theoretical considerations with protein engineering strategies can be generalized to design and evaluate suitable biosensors for various phospho-specific targets.

Migrating fibroblasts reorient directionality by a metastable, PI3K-dependent mechanism.

Mesenchymal cell migration as exhibited by fibroblasts is distinct from amoeboid cell migration and is characterized by dynamic competition among multiple protrusions, which determines directional persistence and responses to spatial cues. Localization of phosphoinositide 3-kinase (PI3K) signaling is thought to play a broadly important role in cell motility, yet the context-dependent functions of this pathway have not been adequately elucidated. By mapping the spatiotemporal dynamics of cell protrusion/retraction and PI3K signaling monitored by total internal reflection fluorescence microscopy, we show that randomly migrating fibroblasts reorient polarity through PI3K-dependent branching and pivoting of protrusions. PI3K inhibition did not affect the initiation of newly branched protrusions, nor did it prevent protrusion induced by photoactivation of Rac. Rather, PI3K signaling increased after, not before, the onset of local protrusion and was required for the lateral spreading and stabilization of nascent branches. During chemotaxis, the branch experiencing the higher chemoattractant concentration was favored, and, thus, the cell reoriented so as to align with the external gradient.