Extreme-ultraviolet- and X-Ray-driven Photochemistry of Gaseous Exoplanets

The interaction of exoplanets with their host stars causes a vast diversity in bulk and atmospheric compositions and physical and chemical conditions. Stellar radiation, especially at the shorter wavelengths, drives the chemistry in the upper atmospheric layers of close orbiting gaseous giants, providing drastic departures from equilibrium. In this study, we aim at unfolding the effects caused by photons in different spectral bands on the atmospheric chemistry. This task is particularly difficult because the characteristics of chemical evolution emerge from many feedbacks on a wide range of timescales, and because of the existing correlations among different portions of the stellar spectrum. In describing the chemistry, we have placed particular emphasis on the molecular synthesis induced by X-rays. The weak X-ray photoabsorption cross sections of the atmospheric constituents boost the gas ionization to pressures inaccessible to vacuum and extreme-ultraviolet photons. Although X-rays interact preferentially with metals, they produce a secondary electron cascade able to ionize efficiently hydrogen- and helium-bearing species, giving rise to a distinctive chemistry.

Safety of Some Synthetic Food Colours: Review

Food additives are used to protect food, increase quality and extend shelf life in many stages, from production to consumption of food. Colorants added by food producers to color food or to adjust the color to desired level are among the commonly used food additives. Considering today's developing production technologies, foods fade or discolor at various stages of processing, storage, and sale due to physical and chemical conditions such as heat, light, pH and oxygen. Colorants are used to regain these color losses, to enhance weak colors, to give color to the food that is actually colorless, and to win back the favour of customers by hiding low quality. Therefore, the most used food colorants in Canada, China, European Union, Mexico and United States of America were presented. The chemical name, chemical structure, common uses, acceptable daily intake (ADI), and toxicity literature of six most used artificial food colors were reviewed.

Leveraging the interplay between homogeneous and heterogeneous catalytic mechanisms: copper-iron nanoparticles working under chemically relevant tumor conditions

The present work sheds light on a generally overlooked issue in the emerging field of bio-orthogonal catalysis within tumor microenvironments (TMEs): the interplay between homogeneous and heterogeneous catalytic processes. In most cases, previous works dealing with nanoparticle-based catalysis in the TME, focus on the effects obtained (e.g. tumor cell death) and attribute the results to heterogeneous processes alone. The specific mechanisms are rarely substantiated and, furthermore, the possibility of a significant contribution of homogeneous processes by leached species –and the complexes that they may form with biomolecules- is neither contemplated nor pursued. Herein, we have designed a bimetallic catalyst nanoparticle containing Cu and Fe species and we have been able to describe the whole picture in a more complex scenario where both homogeneous and heterogeneous processes are coupled and fostered under TME relevant chemical conditions. We investigate the preferential leaching of Cu ions in the presence of a TME overexpressed biomolecule such as glutathione (GSH). We demonstrate that these homogeneous processes initiated by the released by Cu-GSH interactions are in fact responsible for the greater part of the cell death effects found (GSH, a scavenger of reactive oxygen species is depleted and highly active superoxide anions are generated in the same catalytic cycle). The remaining solid CuFe nanoparticle becomes an active catalase-mimicking surrogate able to supply oxygen from oxygen reduced species, such as superoxide anions (by-product from GSH oxidation) and hydrogen peroxide, another species that is enriched in the TME. This enzyme-like activity is essential to sustain the homogeneous catalytic cycle in the oxygen-deprived tumor microenvironment. The combined heterogeneous-homogeneous mechanisms revealed themselves as highly efficient in selectively killing cancer cells, due to their higher GSH levels compared to healthy cell lines.

The Effect of Ionic Strength and pH on the Dewatering Rate of Cellulose Nanofibril Dispersions

Cellulose nanofibrils, CNFs, show a great potential in many application areas. One main aspect limiting the use of the material is the slow and energy demanding dewatering of CNF suspensions. Here we investigate the dewatering with a piston press process. Three different CNF qualities, two laboratory grades (high and low charge) and one industrial grade (low charge) were tested. The chemical conditions were varied by changing salt concentration (NaCl) and pH. For the original suspensions, the dewatering rate is substantially slower for the high charge CNFs. However, by changing the conditions it dewatered as fast as the two low charge CNFs, even though salt/acid additions also improved dewatering rate for these two CNFs. Finally, by tuning the conditions fast dewatering could be obtained with only minor effect on strength and barrier performance of films prepared from the CNFs.

Microbes from Brine Systems with Fluctuating Salinity Can Thrive under Simulated Martian Chemical Conditions

The waters that were present on early Mars may have been habitable. Characterising environments analogous to these waters and investigating the viability of their microbes under simulated martian chemical conditions is key to developing hypotheses on this habitability and potential biosignature formation. In this study, we examined the viability of microbes from the Anderton Brine Springs (United Kingdom) under simulated martian chemistries designed to simulate the chemical conditions of water that may have existed during the Hesperian. Associated changes in the fluid chemistries were also tested using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The tested Hesperian fluid chemistries were shown to be habitable, supporting the growth of all of the Anderton Brine Spring isolates. However, inter and intra-generic variation was observed both in the ability of the isolates to tolerate more concentrated fluids and in their impact on the fluid chemistry. Therefore, whilst this study shows microbes from fluctuating brines can survive and grow in simulated martian water chemistry, further investigations are required to further define the potential habitability under past martian conditions.

Hydrochemical and Hydroacoustic Investigation of the Yugama Acid Crater Lake, Kusatsu-Shirane, Japan

The gases dissolved in the waters of volcanic lakes can present a serious hazard if the physical-chemical conditions change due to variations in the supply of magmatic gases. The monitoring of gases such as CO2 and He help us understand the degassing process and their connection with magmatic/hydrothermal system. One of the most acidic volcanic lakes on the planet is the Yugama, on Kusatsu Shirane volcano (Japan). We report the results of an interdisciplinary study carried out in August 2013 at Yugama consisting of the first estimation of rate of diffuse CO2 emission, the chemical and isotopic analysis of water and dissolved gases in samples from vertical lake profiles, and an echo-sounding survey. The lake water has an average temperature of 24-25°C, pH 1.01, concentrations of SO42- between 1,227 and 1,654 mgL−1 and Cl− between 1,506 and 2,562 mgL−1, with gas bubbling at several locations and floating sulfur globules with sulfide inclusions. A total of 66 CO2 efflux measurements were taken at the lake surface by means of the floating accumulation chamber method to estimate the diffuse CO2 output from the studied area. CO2 efflux values ranged from 82 up to 25,800 g m−2 d−1. Estimation of the diffuse CO2 emission at Yaguma Crater Lake was 30 ± 12 t d−1. Normalized CO2 emission rate (assuming an area of 0.066 km2) was 454 t km−2 d−1, a value within the range of acid volcanic lakes. Vertical profiles of major ions and dissolved gases showed variations with increases in ion content and dissolved CO2 and He with depth. Acoustic imaging shows the presence of intense bubbling and provides important information on the bathymetry of the lake. The 50–200 kHz echograms exhibit frequent vertical plumes of rising gas bubbles. Within the crater-lake, three circular submarine vents have been identified showing flares due to a significant activity of sublacustrine emissions. This work shows the first data of diffuse CO2 degassing, dissolved gases in water and echosounding (ES) from Yugama Crater Lake. Periodic hydrogeochemical and hydroacoustic surveys at Yugama Crater Lakemay thus help to document changes in the state of activity of this high-risk volcanic area.

Aluminum in Bottom Sediments of the Lower Silesian Rivers Supplying Dam Reservoirs vs. Selected Chemical Parameters

The study was carried out on sediments collected from three rivers: Nysa Szalona, Strzegomka and Bystrzyca flowing in southwestern Poland. The content of Al in sediments and in bottom water was determined in relation to chemical conditions. The study was carried out in a four-year cycle, during spring and autumn. The aim of the study was to determine the level and accumulation of aluminum in sediments of rivers supplying dam reservoirs storing water for consumption. The sediments studied were mineral in nature, with neutral pH and moderate sulfate content. The level of Al and heavy metals in the sediments was the highest in the Nysa Szalona River and the lowest in the Strzegomka River, which was also evident in the concentration factor (CF). In terms of season, higher Al contents were recorded in sediments in autumn than in spring, which was also reflected in the concentration factor (CF). Along the course of the river, a gradual decrease in Al levels was observed in successive tributaries in the Nysa Szalona and Strzegomka Rivers, while there was no apparent regularity for the Bystrzyca. Against this background, a comparison of extreme sites below the springs and at the reservoir outlet shows that values were higher in the Nysa Szalona below the springs, and lower in the Strzegomka and Bystrzyca below the reservoir outlet. The general picture of Al and heavy metal loading of the studied sediments shows the lowest loading for the Strzegomka, only the enrichment factor (EF) was the lowest for the Nysa Szalona: metal pollution index (MPI)—S < B < NS, contamination factor (Cf)—S < B < NS, degree of contamination (DC)—S < NS < B, EF—NS < B < S, geoaccumulation index (Igeo)—S < B < NS, CF—S < NS < B. There was no effect of catchment size and river length on Al levels in sediments.

Development and Characterization of Crackers Substitution of Wheat Flour With Jellyfish

The objective of this study was to investigate the possibility of using jellyfish (Lobonema smithii) for the production of nutritionally improved crackers. In this study, ground jellyfish were incorporated into different levels (20, 30, and 40%) to replace wheat flour in cracker formula. Physicochemical characteristics (linear expansion, hardness, and color) and sensory quality of the developed crackers were examined and compared with control crackers. The crackers with jellyfish were found significantly darker, with more brittleness, and less consumer accepted than the control samples (p &lt; 0.05). Moisture content, aw, and thiobarbituric acid reactive substances (TBARS)-values of jellyfish crackers increased while the hardness of the jellyfish crackers decreased with increasing the storage time for both crackers stored at 35 and 45°C. The substitution of wheat flour with jellyfish led to high protein content in the crackers. The cracker with 30% of jellyfish gained characteristics of cracker, liking scores, as well as the subjective quality of the final product and had good physical and chemical conditions, being able to be consumed for 12 weeks stored at 35°C.

Environmental Heterogeneity Determines Diatom Colonisation on Artificial Substrata: Implications for Biomonitoring in Coastal Marine Waters

Benthic diatoms form an important component of the microphytobenthos and have long been utilised as suitable bioindicators in aquatic systems. However, knowledge on benthic diatom community succession on hard substrata (biofilm) remains understudied in austral marine coastal systems. In this study, we investigated benthic diatom colonisation on artificial substrates (Plexiglass) over a period of 5 weeks at two locations with different physical environments along the warm temperate coast of South Africa. Results revealed relatively similar physico-chemical conditions but highly contrasting diatom community development were observed between the two sites. While there were some shared taxa, site-specific dynamics resulted in significantly different diatom species diversity and richness, facilitated by common (e.g., Nitzschia ventricosa and Cocconeis scutellum) and a large percentage of rarely observed species such as Cocconeis testudo and Lyrella lyra. A total of 134 species belonging to 44 genera were observed during the study. The overall diatom composition differed spatio-temporally during the experimental period, with the fluctuating species occurrences and abundances highlighting the rapid microalgal species turnover within days, under natural conditions. Environmental variables were shown to have varying influences as drivers of the diatom community descriptors. Multivariate modelling confirmed that study site and the interaction between site and sampling occasion were important predictors of diatom abundances, and the overall observed community composition. The current results suggest that benthic diatoms on artificial substrata could be incorporated as suitable indicators of change along the coastline subject to further investigations, taking into account site-specific differences driven by habitat complexity and environmental variability. The experimental method proved to be efficient and can be implemented to study the response of benthic diatoms to localised nutrient enrichment around the coastline.