Urban seismic monitoring in Brasília, Brazil.

Urban seismology has gained scientific interest with the development of seismic ambient noise monitoring techniques and also for being a useful tool to connect society with the Earth sciences. The interpretation of the sources of seismic records generated by sporting events, traffic, or huge agglomerations arouses the population's curiosity and opens up a range of possibilities for new applications of seismology, especially in the area of urban monitoring. In this contribution, we present the analysis of seismic records from a station in the city of Brasilia during unusual episodes of silencing and noisy periods. Usually, cultural noise is observed in high-fequency bands. We showed in our analysis that cultural noise can also be observed in the low-frequency band, when high-frequency signal is attenuated. As examples of noisy periods, we have that of the Soccer World Cup in Brazil in 2014, where changes in noise are related to celebrations of goals and the party held by FIFA in the city, and the political manifestations in the period of the Impeachment trial in 2016, which reached the concentration of about 300,000 protesters. The two most characteristic periods of seismic silence have been the quarantine due to the COVID-19 pandemic in 2020, and the trucker strike that occurred across the country in 2018, both drastically reducing the movement of people in the city.

Plant single-cell solutions for energy and the environment.

Progress in sequencing, microfluidics, and analysis strategies has revolutionized the granularity at which multicellular organisms can be studied. In particular, single-cell transcriptomics has led to fundamental new insights into animal biology, such as the discovery of new cell types and cell type-specific disease processes. However, the application of single-cell approaches to plants, fungi, algae, or bacteria (environmental organisms) has been far more limited, largely due to the challenges posed by polysaccharide walls surrounding these species' cells. In this perspective, we discuss opportunities afforded by single-cell technologies for energy and environmental science and grand challenges that must be tackled to apply these approaches to plants, fungi and algae. We highlight the need to develop better and more comprehensive single-cell technologies, analysis and visualization tools, and tissue preparation methods. We advocate for the creation of a centralized, open-access database to house plant single-cell data. Finally, we consider how such efforts should balance the need for deep characterization of select model species while still capturing the diversity in the plant kingdom. Investments into the development of methods, their application to relevant species, and the creation of resources to support data dissemination will enable groundbreaking insights to propel energy and environmental science forward.

Quantification of Ammonia Oxidizing Bacterial Abundances in Environmental Samples by Quantitative-PCR.

Quantitative-PCR (qPCR) enables the quantification of specific DNA targets, such as functional or phylogenetic marker genes associated with environmental samples. During each qPCR cycle, the number of copies of a gene (or region) of interest in DNA samples is determined in real time using a fluorescence-based label and compared to a standard serial dilution. Here, we describe a qPCR method to quantify the ammonia oxidizing bacteria involved in the first step of nitrification, using the amoA gene as a proxy of their abundance. The preparation of the standards from environmental samples and qPCR is presented in detail for specifically quantifying microbial abundance in environmental samples such as soil.

Changing nutrient cycling in Lake Baikal, the world's oldest lake.

Lake Baikal, lying in a rift zone in southeastern Siberia, is the world's oldest, deepest, and most voluminous lake that began to form over 30 million years ago. Cited as the "most outstanding example of a freshwater ecosystem" and designated a World Heritage Site in 1996 due to its high level of endemicity, the lake and its ecosystem have become increasingly threatened by both climate change and anthropogenic disturbance. Here, we present a record of nutrient cycling in the lake, derived from the silicon isotope composition of diatoms, which dominate aquatic primary productivity. Using historical records from the region, we assess the extent to which natural and anthropogenic factors have altered biogeochemical cycling in the lake over the last 2,000 y. We show that rates of nutrient supply from deep waters to the photic zone have dramatically increased since the mid-19th century in response to changing wind dynamics, reduced ice cover, and their associated impact on limnological processes in the lake. With stressors linked to untreated sewage and catchment development also now impacting the near-shore region of Lake Baikal, the resilience of the lake's highly endemic ecosystem to ongoing and future disturbance is increasingly uncertain.

Assessing the risk of bias in choice of search sources for environmental meta-analyses.

Results of meta-analyses are potentially valuable for informing environmental policy and practice decisions. However, selective sampling of primary studies through searches exclusively using widely used bibliographic platform(s) could bias estimates of effect sizes. Such search strategies are common in environmental evidence reviews, and if risk of bias can be detected, this would provide the first empirical evidence that comprehensiveness of searches needs to be improved. We compare the impact of using single and multiple bibliographic platform(s) searches vs more comprehensive searches on estimates of mean effect sizes. We used 137 published meta-analyses, based on multiple source searches, analyzing 9388 studies: 8095 sourced from commercially published articles; and 1293 from grey literature and unpublished data. Single-platform and multiple-platform searches missed studies in 100 and 80 of the meta-analyses, respectively: 52 and 46 meta-analyses provided larger-effect estimates; 32 and 28 meta-analyses provided smaller-effect estimates; eight and four meta-analyses provided opposite direction of estimates; and two each were unable to estimate effects due to missing all studies. Further, we found significant positive log-linear relationships between proportions of studies missed and the deviations of mean effect sizes, suggesting that as the number of studies missed increases, deviation of mean effect size is likely to expand. We also found significant differences in mean effect sizes between indexed and non-indexed studies for 35% of meta-analyses, indicating high risk of bias when the searches were restricted. We conclude that the restricted searches are likely to lead to unrepresentative samples of studies and biased estimates of true effects.

Fabrication of multifunctional Guar gum-silver nanocomposite hydrogels for biomedical and environmental applications.

Poly(acrylamide-co-acrylamidoglycolic acid)/guar gum@ Ag-nanocomposite (AgNC@PAAG) hydrogels has been fabricated by a green protocol utilizing rhubarb stem-extract as bioreductant. The prepared nanocomposites (NCs) are formulated by varying guar gum (GG) polymer and cross-linker content, and used remarkably to study the release of an anticancer drug, 5-fluorouracil (FU). The AgNC@PAAG has demonstrated its potential in bacterial inactivation and p-nitrophenol (PNP) reduction. The AgNC@PAAG hydrogels showed extended FU release time, which was up to 23 h in pH 7.4. The higher zone of inhibition was documented for AgNC@PAAG against B. subtilis and E. coli. It was noticed that, the inhibition activity of AgNC@PAAG, was directly proportional to cross-linker content than the GG polymer. The efficiency of AgNC@PAAG as a nanocatalyst was evaluated for a model reduction reaction of p-nitrophenol (PNP) reduction by aqueous sodium borohydride (NaBH4), with an apparent rate constant of 121.8 × 10-3 min-1 at ambient temperature. The proposed nanocatalysts are reliable and recyclable, demonstrated its catalytic recycle efficacy of 85% after the third successive run. These NCs robust its biological and catalytic activity after embedding silver nanoparticles (AgNPs) by the bioreduction process; these optimized nanocatalysts can be remarkably used in biomedical healthcare sectors and industrial catalysis.

A novel method for evaluating the effect of pollution on the human skin under controlled conditions.

BACKGROUND: Generally considered as a major risk factor for various respiratory diseases, air pollution can also have a significant impact on the skin. To date, there is a plethora of cosmetics products with "anti-pollution" claims. However, these claims have not been fully substantiated with robust scientific evidence and currently there is no standardized method in place for validating the anti-pollution efficacy of cosmetics products. MATERIALS AND METHODS: This article discusses an innovative Controlled Pollution Exposure System (CPES) which allows quantified administration of pollutants on the skin and analysis of their direct impact. Using CPES, human subjects were exposed to ambient dust and ozone and sebum were sampled and analyzed for biomarkers. RESULTS: Following exposure of human subjects' skin to either ambient dust(100-450 µg/cm3 ) or ozone(100-1000 ppb), analysis of sebum revealed a significant decrease in squalene concentration, and significant increases in squalene monohydroperoxide and malondialdehyde concentration. CONCLUSION: The findings demonstrate cutaneous oxidative stress induced by ambient dust and ozone. The findings also demonstrate the efficacy of CPES to accurately measure the direct effect of controlled gaseous and particulate pollutants on human skin and indicate that squalene, squalene monohydroperoxide and malondialdehyde may serve as potent biomarkers for evaluating potential anti-pollution claims of cosmetics products.

Evaluation of Fe-containing Li2CuO2 on CO2 capture performed at different physicochemical conditions.

Li2CuO2 and different iron-containing Li2CuO2 samples were synthesized by solid state reaction. On iron-containing samples, atomic sites of copper are substituted by iron ions in the lattice (XRD and Rietveld analyses). Iron addition induces copper release from Li2CuO2, which produce cationic vacancies and CuO, due to copper (Cu2+) and iron (Fe3+) valence differences. Two different physicochemical conditions were used for analyzing CO2 capture on these samples; (i) high temperature and (ii) low temperature in presence of water vapor. At high temperatures, iron addition increased CO2 chemisorption, due to structural and chemical variations on Li2CuO2. Kinetic analysis performed by first order reaction and Eyring models evidenced that iron addition on Li2CuO2 induced a faster CO2 chemisorption but a higher thermal dependence. Conversely, CO2 chemisorption at low temperature in water vapor presence practically did not vary by iron addition, although hydration and hydroxylation processes were enhanced. Moreover, under these physicochemical conditions the whole sorption process became slower on iron-containing samples, due to metal oxides presence.