149 research outputs found
Oznaczanie poziomów zawartości surfaktantów w próbkach środowiskowych. Część 3. Niejonowe związki
Non-ionic surface active agents are a diverse group of chemicals which have an uncharged polar head
and a non-polar tail. They have different properties due to amphiphilic structure of their molecules. Commercial
available non-ionic surfactants consist of the broadest spectrum of compounds in comparison with other types of
such agents. Typically, non-ionic compounds found applications in households and industry during formulation
of cleaning products, cosmetics, paints, preservative coatings, resins, textiles, pulp and paper, petroleum products
or pesticides. Their are one of the most common use class of surfactants which can be potential pollution sources
of the different compartment of environment (because of they widely application or discharging treated
wastewaters to surface water and sludge in agricultural). It is important to investigate the behavior, environmental
fate of non-ionic surfactants and their impact on living organisms (they are toxic and/or can disrupt endocrine
functions). To solve such problems should be applied appropriated analytical tools. Sample preparation step is one
of the most critical part of analytical procedures in determination of different compounds in environmental
matrices. Traditional extraction techniques (LLE - for liquid samples; SLE - for solid samples) are time and
solvent-consuming. Developments in this field result in improving isolation efficiency and decreasing solvent
consumption (eg SPE and SPME - liquid samples or PLE, SFE and MAE - solid samples). At final determination
step can be applied spectrophotometric technique, potentiometric titrametration or tensammetry (determination
total concentration of non-ionic surfactants) or chromatographic techniques coupled with appropriated detection
techniques (individual analytes). The literature data concerning the concentrations of non-ionic surfactants in the
different compartments of the environment can give general view that various ecosystems are polluted by those
compounds
Oznaczanie poziomów zawartości surfaktantów w próbkach środowiskowych. Część 2. Związki anionowe
Surface active agents (SAA) with negative charge of polar group are named as anionic compounds.
They are the main constituent of most products containing synthetic surfactants. The linear alkylbenzene
sulfonates (LAS), alkyl ethoxysulfates (AES) and alkyl sulfates (AS) are typically applied from this class of
compounds. Those surfactants are ingredients of household detergents and cleaners, laundry detergents, cosmetic
etc. Moreover they can be applied in the paper, textile and tanning industry as optical brighteners, dispersant,
wetting and suspending agents. They can be substrates in the formulation of different products like dyes,
pigments, pesticides, exchange resins, plasticizers and pharmaceuticals. Anionic surfactants after use are passed
into sewage-treatment plants, where they are partially degraded and adsorbed to sewage sludge (applied in
agriculture fields). Finally, the anionic SAA or their degradation products are discharged into surface waters and
onto bottom sediments, soils or living organisms. Therefore, it is important (widely application, bioaccumulation,
toxicity for living organisms) to investigate the environmental fate of those class of compounds in more details.
This research involves determination the concentration of anionic surfactants with use appropriated analytical
techniques in environmental samples The official methodology for determination of anionic SAA in liquid
samples is based on the ion-pair reaction of these analytes compounds with methylene blue (MB) and an
extraction with toxic solvent chloroform. During isolation step of anionic compounds from solid samples are
employed Soxhlet and ultrasonic-assisted extraction techniques with use of methanol or mixture of other organic
solvents as extraction medium. To overcome disadvantages of those traditional techniques were applied following
techniques at sample preparation step from liquid and solid matrices: solid-phase extraction (SPE) and
solid-phases microextraction (SPME); accelerated solvent extraction (ASE), microwave-assisted extraction
(MAE), supercritical fluid extraction (SFE), respectively. For estimate total concentration of anionic analytes in
extracts the spectrophotometric technique is used (as official regulation). For determination concentration of
individual analytes were applied gas (derivatization step requires) and liquid chromatography mainly with mass
spectrometry technique. The presence of anionic surface active agents was confirmed in various ecosystems
(liquid and solid environmental samples)
Effects of Short and Long-term Dietary Protein Restriction on the Rumen Fermentation Activity in Growing Lambs
Determination of fuel combustion product in airport runoff water samples using liquid–liquid extraction with gas chromatography–spectrometry
Applicability of non-invasively collected matrices for human biomonitoring
With its inclusion under Action 3 in the Environment and Health Action Plan 2004–2010 of the European Commission, human biomonitoring is currently receiving an increasing amount of attention from the scientific community as a tool to better quantify human exposure to, and health effects of, environmental stressors. Despite the policy support, however, there are still several issues that restrict the routine application of human biomonitoring data in environmental health impact assessment. One of the main issues is the obvious need to routinely collect human samples for large-scale surveys. Particularly the collection of invasive samples from susceptible populations may suffer from ethical and practical limitations. Children, pregnant women, elderly, or chronically-ill people are among those that would benefit the most from non-invasive, repeated or routine sampling. Therefore, the use of non-invasively collected matrices for human biomonitoring should be promoted as an ethically appropriate, cost-efficient and toxicologically relevant alternative for many biomarkers that are currently determined in invasively collected matrices. This review illustrates that several non-invasively collected matrices are widely used that can be an valuable addition to, or alternative for, invasively collected matrices such as peripheral blood sampling. Moreover, a well-informed choice of matrix can provide an added value for human biomonitoring, as different non-invasively collected matrices can offer opportunities to study additional aspects of exposure to and effects from environmental contaminants, such as repeated sampling, historical overview of exposure, mother-child transfer of substances, or monitoring of substances with short biological half-lives
Progressing Pollutant Elution from Snowpack and Evolution of its Physicochemical Properties During Melting Period—a Case Study From the Sudetes, Poland
Kisspeptin signaling is required for the luteinizing hormone response in anestrous ewes following the introduction of males
The introduction of a novel male stimulates the hypothalamic-pituitary-gonadal axis of female sheep during seasonal anestrus, leading to the resumption of follicle maturation and ovulation. How this pheromone cue activates pulsatile secretion of gonadotropin releasing hormone (GnRH)/luteinizing hormone (LH) is unknown. We hypothesised that pheromones activate kisspeptin neurons, the product of which is critical for the stimulation of GnRH neurons and fertility. During the non-breeding season, female sheep were exposed to novel males and blood samples collected for analysis of plasma LH profiles. Females without exposure to males served as controls. In addition, one hour before male exposure, a kisspeptin antagonist (P-271) or vehicle was infused into the lateral ventricle and continued for the entire period of male exposure. Introduction of a male led to elevated mean LH levels, due to increased LH pulse amplitude and pulse frequency in females, when compared to females not exposed to a male. Infusion of P-271 abolished this effect of male exposure. Brains were collected after the male effect stimulus and we observed an increase in the percentage of kisspeptin neurons co-expressing Fos, by immunohistochemistry. In addition, the per-cell expression of Kiss1 mRNA was increased in the rostral and mid (but not the caudal) arcuate nucleus (ARC) after male exposure in both aCSF and P-271 treated ewes, but the per-cell content of neurokinin B mRNA was decreased. There was also a generalized increase in Fos positive cells in the rostral and mid ARC as well as the ventromedial hypothalamus of females exposed to males. We conclude that introduction of male sheep to seasonally anestrous female sheep activates kisspeptin neurons and other cells in the hypothalamus, leading to increased GnRH/LH secretion
Dinâmica da distribuição e degradação de atrazina em argissolo vermelho-amarelo sob condições de clima tropical úmido
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