Adverse Chemical Conditions Research Articles

Nanocomposite ceramic membranes as novel tools for remediation of textile dye waste water – A review of current applications, machine learning based modeling and future perspectives

Textile effluent treatment has gained significant attention due to the carcinogenic effects of the dye pollutants present and their enhanced resistance to degradation. Porous ceramic membranes have gained growing interest for dye remediation due to various unique characteristics, including resistance to fungal invasion, adverse chemical conditions, and high temperature. The current study explores applications of ceramic membrane technology, including membranes like MF, UF, and NF, for dye remediation from textile effluent. The best-performing nanocomposite membranes for eliminating azo dyes from textile effluent and efficiencies achieved are reported as Clay-alumina (99%), yttria-stabilized-zirconia (99%), nano TiO2-bentonite UF (95%), and tight TiO2 UF (100%). Ceramic nanocomposites with TiO2 and Al2O3 active layer NF (99%), Ceramic Hybrid hollow fiber LNF (99.3%). Loose nanofiltration (LNF) ceramic membranes have demonstrated outstanding targeted separation performance for the separation of dyes, making them affirm the effective recoveries and recurrent use of high-value-added constituents amongst all the membrane approaches examined. The potential of ceramic membranes for future research and development, including membrane production and mechanism, are discussed. In addition, the implementation of AI-based methods and Machine learning (ML) algorithms are discussed in relation to predicting membrane filtration performance and fouling tendencies and dye removal processes, maximizing opportunities in this field.

Sedimentary ancient DNA of rotifers reveals responses to 200 years of climate change in two Kenyan crater lakes

Abstract Sedimentary ancient DNA (sedaDNA) has proven to be a useful tool for palaeoenvironmental studies, but only a handful of studies exist so far for tropical regions. In this study we used sedaDNA to study the temporal succession of Brachionus spp. rotifer mitochondrial DNA haplotypes using two sediment cores from two climatically different alkaline‐saline crater lakes from the Kenyan Rift Valley. Data were retrieved from a sediment core (dating back to AD 1800) from Lake Kageinya, located in the remote, hot and hyper‐arid Suguta Valley. sedaDNA was used to study the temporal succession of mitochondrial DNA haplotypes of Brachionus spp. rotifers. The results were compared to previously published data from Lake Sonachi, a well‐studied lake in the humid and colder mountainous region of Kenya near the town of Naivasha, now supported by a 210Pb age chronology. Both records extend back before the onset of substantial anthropogenic impact in these regions. The results revealed that climate—rather than anthropogenic impact—was most strongly correlated with haplotype changes in both lakes. During prolonged dry periods (such as from AD 1910 to the late AD 1960s), certain haplotypes persisted. Sudden changes and the emergence of alter native haplotypes were observed when climate became more humid or during episodes of highly variable climate (before AD 1910 and from AD 1960s onwards). Progressive changes in prevailing haplotypes during periods with variable climate could reflect local adaptation and/or be the result of immigration of new haplotypes after the eradication of previous populations during extreme environmental conditions (high temperatures, UV irradiation, pH and salinity). The results indicate that, despite adverse chemical conditions, sedaDNA in tropical lake sediments is preserved for at least a few hundred years. Therefore, its analysis provides a useful complementary palaeoenvironmental proxy for palaeolimnological reconstructions and novel insights on changes in rotifer populations through time.

Where do the embryos of Riftia pachyptila develop? Pressure tolerances, temperature tolerances, and buoyancy during prolonged embryonic dispersal

Abstract The giant vent tubeworm Riftia pachyptila releases slightly buoyant lipid-rich zygotes into the water column, where embryos develop and disperse for 21–25 days before they become ciliated larvae capable of controlling their position in the water column. If embryos rise too rapidly, either from their own buoyancy or by being entrained in a buoyant plume, they could encounter warmer temperatures or lower pressures than the embryos can tolerate. Likewise, if they are entrained among the tubes of the adults or in near-bottom currents, the embryos could encounter warm water and adverse chemical conditions. To determine the range of physiological tolerances for normal development of R. pachyptila, we examined survival of embryos at various combinations of pressure and temperature in the laboratory using small pressure vessels. We also used small incubation chambers deployed in and above tubeworm clusters at our study site on the East Pacific Rise. These served as an in situ comparison for the laboratory data. Temperatures were measured at each incubation site with temperature data loggers. The ambient temperature away from the vents at the study site was 2 °C, and the upper thermal limit for 50% normal development was 6 °C for embryos cultured in the pressure vessels and approximately 7 °C in situ. This limited temperature tolerance defines the embryos physiologically as “cold stenotherms”. In laboratory experiments conducted at 2 °C, embryos developed normally at the near-ambient vent pressure of 238 and also at 170 atm. Cleavage rates at 170 atm were much slower than at the higher pressure, however, suggesting that the embryos were probably near their low-pressure threshold. No development occurred at 100 or at 1 atm. During upward migration, embryos would encounter a pressure of 170 atm at a significantly greater depth (1700 m) than they would encounter a temperature of 6 °C, suggesting that embryonic survival should be pressure limited before temperature becomes a controlling factor. To determine the likelihood that these physiological stresses would be encountered during embryogenesis, we measured flotation rates of zygotes and early embryos. At ambient vent pressure (250 atm) and temperature, the zygotes rose at an average rate of 2 m day−1. As the embryos develop, they consume wax esters and therefore lose some buoyancy, but assuming a constant flotation of 2 m day−1 for 25 days, this would bring the embryos approximately 50 m off the bottom. If embryos were entrained in a buoyant plume however, they would reach a depth of slightly more than 2300 m (230 atm) before the plume becomes neutrally buoyant. In either case, the embryos would remain below the critical depth for normal development. Because development is inhibited at temperatures above 6–7 °C, it is unlikely that embryos are retained in or among the adult tubes.

In‐line monitoring of molten polymers: Near infrared spectroscopy, robust probes, and rapid data analysis

AbstractThe concept of improved product quality and reduced costs has revolutionized analytical techniques in the polymer industry. It has brought in‐line analysis to the forefront, with near infrared (NIR) spectroscopy proving to be a very viable technique for such operations. A system for continuous in‐line near infrared monitoring of molten polymer blends, copolymers, and polymer reactions is being developed. The ultimate objective is to use this monitoring system to develop feedback control for polymeric processes. Experiments on blends of polystyrene and poly(phenylene oxide) have been performed by using a flow cell, located at the exit port of a single‐screw extruder. Qualitative analysis of spectral data has been substantiated by a variety of quantitative (multivariate) techniques. Robust calibration models, suitable for on‐line predictions, have been developed. The success of in‐line process analysis depends on the performance of fiber‐optic probes that are inserted into the process stream. These probes normally succumb to the demands of the rigorous process environment, typical of polymeric processes, i.e., high temperatures, high pressures, and adverse chemical conditions. Design and development of fiber‐optic probes that are capable of withstanding such harsh conditions have also been undertaken. Results will be reported on the polymeric systems and optical probes.

The anomaly of silicon in plant biology.

Silicon is the second most abundant element in soils, the mineral substrate for most of the world's plant life. The soil water, or the "soil solution," contains silicon, mainly as silicic acid, H4SiO4, at 0.1-0.6 mM--concentrations on the order of those of potassium, calcium, and other major plant nutrients, and well in excess of those of phosphate. Silicon is readily absorbed so that terrestrial plants contain it in appreciable concentrations, ranging from a fraction of 1% of the dry matter to several percent, and in some plants to 10% or even higher. In spite of this prominence of silicon as a mineral constituent of plants, it is not counted among the elements defined as "essential," or nutrients, for any terrestrial higher plants except members of the Equisitaceae. For that reason it is not included in the formulation of any of the commonly used nutrient solutions. The plant physiologist's solution-cultured plants are thus anomalous, containing only what silicon is derived as a contaminant of their environment. Ample evidence is presented that silicon, when readily available to plants, plays a large role in their growth, mineral nutrition, mechanical strength, and resistance to fungal diseases, herbivory, and adverse chemical conditions of the medium. Plants grown in conventional nutrient solutions are thus to an extent experimental artifacts. Omission of silicon from solution cultures may lead to distorted results in experiments on inorganic plant nutrition, growth and development, and responses to environmental stress.

Prevention of chemically induced synaptosomal changes

The ability of altered environmental conditions to modulate some properties of synaptosomes has been studied. Incubation conditions used included the presence of methyl mercury or an organochlorine insecticide: chlordecone. Other adverse chemical conditions during incubation were the absence of calcium salts from the incubation medium or the addition of agents bringing about enhanced oxidative conditions. Synaptosomal parameters studied were the cytosolic level of free, ionic calcium, [Ca2+]i, the extent of depolarization-induced uptake of radioactive calcium, and the permeability of the limiting membrane. In addition, peroxidative activity was estimated by quantitation of thiobarbituric acid-reactive material. All these facets of synaptosomal function were responsive to the presence of these potentially deleterious changes in the incubation medium. While the response of [Ca2+]i was potentially in either direction, all adverse conditions increased synaptosomal permeability as evaluated by leakage of fura-2 into the extracellular compartment. Pretreatment with ganglioside GM1 in some situations or alpha-tocopherol in others could either wholly or partially prevent the onset of such altered synaptosomal characteristics.

Impact of Recent Economic Growth and Industrial Development on the Ecology of Northwest Miramichi Atlantic Salmon (Salmo salar)

The history of Atlantic salmon (Salmo salar) runs of the Northwest Miramichi from 1950 to 1973 is reviewed. Decreases in these runs are related to degrading of ecological conditions in the river's rearing reaches as a result of adverse chemical conditions attributable to recent developments in forest management and to base metal mining. Diversion of indigenous adult stocks into other streams of the system as a result of pollution of the home stream by mining, pulpmill, and other human activities is examined and evaluated. Increase of commercial catches as a result of pollution-caused delay in the estuary of migrating adults is analyzed. Grave depletion of stocks as a result of the combined effects of these factors plus distant-water fishing is identified, as is incipient recovery of stocks when home-water commercial fishing was eliminated and pollution abatement measures were introduced to the river. A suppressing effect of heavy angling pressure on stock abundance when stocks are low is noted.