First Hour Of Exposure Research Articles

Novel technique for the ultra-sensitive detection of hazardous contaminants using an innovative sensor integrated with a bioreactor

This study introduces an evaluation methodology tailored for bioreactors, with the aim of assessing the stress experienced by algae due to harmful contaminants released from antifouling (AF) paints. We present an online monitoring system equipped with an ultra-sensitive sensor that conducts non-invasive measurements of algal culture's optical density and physiological stage through chlorophyll fluorescence signals. By coupling the ultra-sensitive sensor with flash-induced chlorophyll fluorescence, we examined the dynamic fluorescence changes in the green microalga Chlamydomonas reinhardtii when exposed to biocides. Over a 24-h observation period, increasing concentrations of biocides led to a decrease in photosynthetic activity. Notably, a substantial reduction in the maximum quantum yield of primary photochemistry (FV/FM) was observed within the first hour of exposure. Subsequently, we detected a partial recovery in FV/FM; however, this recovery remained 50% lower than that of the controls. Integrating the advanced submersible sensor with fluorescence decay kinetics offered a comprehensive perspective on the dynamic alterations in algal cells under the exposure to biocides released from antifouling coatings. The analysis of fluorescence relaxation kinetics revealed a significant shortening of the fast and middle phases, along with an increase in the duration of the slow phase, for the coating with the highest levels of biocides. Combining automated culturing and measuring methods, this approach has demonstrated its effectiveness as an ultrasensitive and non-invasive tool for monitoring the physiology of photosynthetic cultures. This is particularly valuable in the context of studying microalgae and their early responses to various environmental conditions, as well as the potential to develop an AF system with minimal harm to the environment.

Global omics study of Tetraselmis chuii reveals time-related metabolic adaptations upon oxidative stress

Microalgae species encounter oxidative stress in their natural environments, prompting the development of species-specific adaptation mechanisms. Understanding these mechanisms can offer valuable insights for biotechnological applications in microalgal metabolic manipulation. In this study, we investigated the response of Tetraselmis chuii, an industrially important microalga, to H2O2-induced oxidative stress. Exposure to 0.5-mM H2O2 resulted in reduced cell viability, and higher concentrations led to a drastic decline. After 1 h of exposure to H2O2, photosynthetic capacity (Qy) was negatively impacted, and this reduction intensified after 6 h of continuous stress. Global multi-omics analysis revealed that T. chuii rapidly responded to H2O2-induced oxidative stress within the first hour, causing significant changes in both transcriptomic and metabolomic profiles. Among the cellular functions negatively affected were carbon and energy flow, with photosynthesis-related PSBQ having a 2.4-fold downregulation, pyruvate kinase decreased by 1.5-fold, and urea content reduced by threefold. Prolonged exposure to H2O2 incurred a high energy cost, leading to unsuccessful attempts to enhance carbon metabolism, as depicted, for example, by the upregulation of photosystems-related PETC and PETJ by more than twofold. These findings indicate that T. chuii quickly responds to oxidative stress, but extended exposure can have detrimental effects on its cellular functions.Key points• 0.5-mM H2O2–induced oxidative stress strongly affects T. chuii• Distinct short- and long-term adaptation mechanisms are induced• Major metabolic adaptations occur within the first hour of exposure

Accelerated Carbonation of Binders Containing SCM at High CO2 Concentration

Abstract Accelerated carbonation of recycled concrete aggregates (RCA) could be an efficient way to reduce the carbon footprint. High CO2-concentration under optimal relative humidity could accelerate the CO2 binding capacity of the hydrated cement paste in the RCA. The latter is the topic of this paper. The study looks into the forced carbonation of crushed cement pastes as a basis to understand the CO2 uptake in relation to various binders containing supplementary cementitious materials (SCM) such as fly ash (FA) and ground granulated blast furnace slag (GGBS). Samples include three cement pastes: ordinary Portland cement, substitution rate of 30 % FA and 50 % GGBS respectively at a water/binder ratio of 0.45. All binders were graded to 0/2, 2/4 and 4/8 mm fraction sizes and preconditioned before exposed to CO2 concentration of 10 % under controlled temperature at 20 °C and 65 % RH. All tested binders presented a high CO2 uptake within the first hours of exposure with clear differences concerning the fraction sizes and the composition. The phase content before and after carbonation was observed by X-ray diffraction and the portlandite and calcite were quantified by thermogravimetric analyses and their derivative curves for fraction size 4/8 mm.

In vitro and in silico scolicidal effect of sanguinarine on the hydatid cyst protoscoleces.

We aimed to investigate the scolicidal effects of sanguinarine on hydatid cyst protoscoleces (PSCs) in vitro and in silico. Different targets were docked into the active sites of sanguinarine. Molecular docking processes and visualization of interactions were performed using AutoDock Vina and Discovery Studio Visualizer. Binding energy was calculated and compared (kcal/mol). PSCs were aspirated from the hydatid cysts and washed. The sediments of PSCs were then exposed to various concentrations (50, 25, 12, 6, 3, and 1 μg/mL) of sanguinarine. The viability test was finally evaluated by the Trypan blue solution 4%. Levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPX), and catalase were analyzed to assess the level of oxidative stress-treated PSCs. Caspase-3 activity rate was determined to evaluate cell apoptosis in treated PSCs. Among the receptors, acetylcholinesterase was identified as the excellent target, with Vina score of -11.8. Sanguinarine showed high scolicidal effects after 12, 24, and 48 h. Also, in the first hour of exposure to the drug, caspase-3 activity and MDA level significantly increased, but the levels of GSH and GPx had a significant reduction after 12, 24, and 48 h (P < 0.05). The findings of this study revealed that sanguinarine have potent scolicidal effects in vitro and in silico and could be considered an opportunity for the introduction of a novel and safe therapeutic agent for the treatment of cystic echinococcosis. However, supplementary studies will be desired to prove the current findings by examining sanguinarine in a clinical setting.

Comprehensive assessment of transparent wood degradation

Transparent wood includes a group of composite materials consisting of a renewable component (various wood species) and a refractive-matching index polymer (petroleum or bio-based) with a wide range of applications. There are various types of polymers used for transparent wood preparation Due to their favourable optical, mechanical, and carbon-storing properties, transparent wood is ideal for use in, e.g., the automobile industry, construction, packaging, or electronics. In this study, acrylic-based transparent wood was prepared by deactivating chromophore groups in natural basswood (Tilia cordata, L.), followed by a subsequent vacuum-assisted 2-hydroxyethyl-methacrylate polymer infiltration. Fire characteristics, UV and biological resistance of this wood-polymer system were investigated. Transparent wood prepared for this study shows high resistance to wood decay fungi. Fire performance test shows higher resistance to initiation (higher time to ignition and critical heat flux)compared to natural wood and lower yields of carbon monoxide. When exposed to UV irradiation, colour, and transmittance change intensively only in the first hours of exposure, then only very gradually. On the other hand, transparent wood shows higher values of heat release rate and derived parameters.

Evaluation of the Synergistic Effect of LL-37 and Oncorhyncin II Recombinant Proteins on Staphylococcus aureus Under In Vitro Conditions

Background: The treatment of Staphylococcus aureus infections has become a public health crisis due to the extensive development of antimicrobial resistance. Antimicrobial peptides (AMPs) have been introduced as promising naturally-derived antimicrobial alternatives to antibiotics. LL-37 and oncorhyncin II are 2 AMPs with notable proven antibacterial effects. Objectives: This study aimed to produce recombinant LL-37 and oncorhyncin II and investigate their synergistic effects on S. aureus (ATCC25923). Methods: The synthetic genes of LL-37 and oncorhyncin II were individually ligated into the pET32a expression vector. Transformed pET32a was introduced into Escherichia coli BL21 as an expression host. The protein expression and purification steps were optimized, and the biological effectiveness of the peptides was evaluated by assessing the minimum inhibitory concentration (MIC), time-kill, and growth kinetic tests against S. aureus. Results: The MIC assay confirmed the effective antibacterial performances of LL-37 and oncorhyncin II against S. aureus at 30.6 and 47.93 µg/mL, respectively. The peptides’ synergistic activity was validated by the checkerboard method. A combination of LL-37 and oncorhyncin II at 2 × MIC showed a sharp decline of the viable cells with over 3-time reductions in log 10 colony-forming units (CFU)/mL within the first 5 hours. The growth kinetic results confirmed the high effectiveness of the peptides’ combination in eliminating the bacterial inoculum turbidity by 50% reduction during the first hour of exposure. Conclusions: The produced recombinant LL-37 and oncorhyncin II showed effective antimicrobial function against S. aureus. The synergistic performance of the peptides was repeatedly confirmed through checkerboard, time-kill, and growth kinetic assays.

Atrazine contaminated sites and bullfrog tadpoles: evasive trends and biochemical consequences.

Atrazine (ATZ) is one of the most used active principles in agricultural systems. This pesticide has the ability to easily accumulate in terrestrial and aquatic environments, causing impacts with chronic adverse effects. Avoidance tests are tests that seek to assess the concentration from which a given organism escapes, that is, migrates to another habitat. They are being used as a modality of innovative and minimally invasive ecotoxicological tests. Our objective was to evaluate the sensitivity and possible toxic effects of ATZ in bullfrog tadpoles (Lithobates catesbeianus), through avoidance tests and oxidative stress analyses. We performed the behavioral avoidance test lasting 12 h, with observations every 60 min in a linear multi-compartment system with seven compartments. Each compartment corresponded to a concentration: negative control, 1, 2, 20, 200, 2000, 20,000 µg L-1. After the selection of habitat, organisms were forcedly maintained in the chosen concentrations for 48 h and then, metabolic effects were measured assessing the blood plasma amino acid profile and liver protein degradation. We also determined the effective concentrations of ATZ tested at 0 h and 48 h. The results showed that there was an effect of the treatment on the distribution of tadpoles, but not on the hours or on the combined effect (interaction). The biochemical analyses also showed a concentration-dependent relationship which caused significant toxic effects even in a short period of time. In conclusion, these frogs were able to avoid places with high concentrations of ATZ in the first hours of exposure, which suggests that in the natural environment these animals can migrate or avoid areas contaminated by this herbicide; however, depending on the selected concentration, serious biochemical consequences can occur.

Malathion alters the transcription of target genes of the tumour suppressor tp53 and cancerous processes in Colossoma macropomum: Mechanisms of DNA damage response, oxidative stress and apoptosis

Different classes of pesticides such as fungicides, herbicides, and insecticides, can induce differential expression of genes that are involved in tumorigenesis events in fish, including the expression of tumor suppressor tp53. The degree and duration of the stressful condition is decisive in defining which tp53-dependent pathway will be activated. Herein we evaluate the target genes expression that participates in the regulation pathway of the tumor suppressor tp53 and in the cancerous processes in tambaqui after exposure to malathion. Our hypothesis is that malathion promotes a gene response that is differentially regulated over time, with positive regulation of tp53 target genes related to the apoptotic pathway and a negative regulation of genes that promote antioxidant responses. The fish were exposed to a sublethal concentration of the insecticide for 6 and 48 h. Liver samples were used to analyze the expression of 11 genes using real-time PCR. Overall, the malathion promoted over time increases in tp53 expression and differential expression of tp53 related genes. The exposure resulted in the activation of damage response related genes, caused a positive expression of atm/atr genes. The pro-apoptotic gene bax was up-regulated and the anti-apoptotic bcl2 was down-regulated. Increased expression of mdm2 and sesn1 in the first hours of exposure and no effect on the antioxidant genes sod2 and gpx1 were also observed. We also witnessed an increase in the expression of the hif-1α gene, with no effect on ras proto-oncogene. The extension of this stressful condition accentuated tp53 transcription, and minimized the levels of mdm2, sens1 and bax; however, it down regulated the levels of bcl2 and the bcl2/bax ratio, which indicates the maintenance of the apoptotic response to the detriment of an antioxidant response.

Impact of lead (Pb2+) on the growth and biological activity of Serratia marcescens selected for wastewater treatment and identification of its zntR gene-a metal efflux regulator.

Microorganisms isolated from contaminated areas play an important role in bioremediation processes. They promote heavy metal removal from the environment by adsorbing ions onto the cell wall surface, accumulating them inside the cells, or reducing, complexing, or precipitating these substances in the environment. Microorganism-based bioremediation processes can be highly efficient, low-cost and have low environmental impact. Thus, the present study aimed to select Pb2+-resistant bacteria and evaluate the growth rate, biological activity, and the presence of genes associated with metal resistance. Serratia marcescens CCMA 1010, that was previously isolated from coffee processing wastewater, was selected since was able to growth in Pb2+ concentrations of up to 4.0mM. The growth rate and generation time did not differ from those of the control (without Pb2+), although biological activity decreased in the first hour of exposure to these ions and stabilized after this period. The presence of the zntR, zntA and pbrA genes was analysed, and only zntR was detected. The zntR gene encodes a protein responsible for regulating the production of ZntA, a transmembrane protein that facilitates Pb2+ extrusion out of the cell. S. marcescens CCMA 1010 demonstrated a potential for use as bioindicator that has potential to be used in bioremediation processes due to its resistance to high concentrations of Pb2+, ability to grow until 24h of exposure, and possession of a gene that indicates the existence of mechanisms associated with resistance to lead (Pb2+).

Characterizing asphalt emissions under in-service conditions

Recent studies have suggested that asphalt related emissions at environmentally pertinent conditions are a major contributor of volatile organic compounds ubiquitous to the environment. Many variables such as temperature/viscosity of asphalt binder, solar irradiance of the asphalt binder, and geometric constraints including film thickness, the act of coating aggregate to produce Hot Mix Asphalt, and compaction into pavements influence the magnitude and composition of measured emissions. Continuous films of asphalt binder were used to determine how temperature/viscosity and film thicknesses can influence measured emissions. The magnitude of emissions scaled with the inverse of viscosity, whereas the composition of emissions varied with film thickness and age of the asphalt binder sample. Asphalt binder exposed to solar irradiance showed short term impacts on emissions in the first hours of exposure. Compacted asphalt pavements were used to simulate real world new in-service conditions. The emissions from a freshly compacted asphalt pavement were compared to a 17-year-old pavement sample collected from the field to determine how the act of compacting asphalt binder coated in aggregate influenced emissions over a 17-year period. An increase in the complexity of the system caused slowing in the total emissions profile. While lower than what was observed in the freshly compacted samples, emissions were still observed in the 17-year-old pavement. The composition of emissions indicated that smaller and more volatile compounds are capable of being released from deeper within the compacted pavement, whereas the larger and less volatile compounds tend to remain trapped. • Asphalt emission generator used to measure emissions under in-service conditions. • The effects of solar irradiation on asphalt pavement emission. • Solar irradiation of asphalt binders generates short term increases in emissions. • Effects of asphalt pavement compaction on released emissions.

Bioinformatic analysis and relative expression of hyd and fdx during H2 production in microalgae

SUMMARYMicroalgae have been positioned as excellent models for producing new sources of energy (biofuels and biohydrogen). Some investigations in these biological models have been directed to know if the enzymes ferredoxin (FDX) and hydrogenase (HYD) are involved in the algae producing different concentrations of molecular hydrogen (H2). To date, little is known about the concomitant transcriptional regulation of both enzymes during H2 evolution in algae. In this research, we evaluated the relative expression of hdy and fdx genes during the evolution of H2 in three microalgae (Chlorella vulgaris, Scenedesmus obliquus, and Chlamydomonas reinhardtii) in N‐deprived anaerobic cultures in the presence of Fe, and 12:24 and 24:24 h dark:light cycles. We also detected structural differences in the enzymes. The 3D modeling indicated that the 3D structure of HYD and FDX are conserved in most algal genera, and the results of our grouping according to the aa characteristics of the proteins showed two grouping trends: One, according to the algae's phylogenetic classification, and another one according to the species‐specific enzyme's characteristics, and the grouping could perhaps be more influenced by the algae's ability to produce H2. The three microalgae species reached maximum H2 accumulation values in 24h:24 h dark:light conditions in Fe‐supplemented media (4.2 ± 0.12 mL L−1 in C. vulgaris, 3.9 ± 0.10 mL L−1 in S. obliquus, and 4.5 ± 0.10 mL L−1 in C. reinhardtii), and the highest global relative expression of hyd and fdx genes was reached during the first hour of exposure to light, which suggests concomitant expression of both enzymes at the beginning of H2 production. The behavior of the expression of the hyd and fdx genes in these algal species proved to be similar between species. A better understanding of the concomitant regulation of both enzymes could lay the groundwork for the future use of both enzymes to improve H2 yields in microalgae.

Titanium Dioxide/Polysiloxane Composites: Preparation, Characterization and Study of Their Color Stability Using Thermochromic Pigments

In order to improve thermomechanical, antibacterial and temperature-controlled color-response performance of polydimethylsiloxane (PDMS) in maxillofacial prostheses, the incorporation of titania (TiO2) nanoparticles and thermochromic pigments (TCP) into PDMS was examined. The thermal transitions of TiO2/PDMS nanocomposites, investigated by differential scanning calorimetry (DSC), remain almost unaffected, while an increase of the crystallinity of PDMS was recorded in specimens with higher titania concentrations. The incorporation of titania improves the thermal stability, as it was revealed by thermogravimetric analysis (TGA), as well as the tensile properties of the reinforced elastomer. Nanocomposites with 10 wt% titania presented antibacterial activity against Escherichia Coli, leading to 72% reduction of the bacterial colony after 3 h of exposure. Specimens colored with red TCP (0.2 and 0.6 wt%) showed significant color change at a lower temperature (−20 °C) in comparison with that at an ambient temperature, especially at lower TCP concentration (0.2 wt%). Accelerating aging experiments, consisting of repeated cycles of combined exposure to UV-radiation and damp heating, of PDMS colored with TCP showed poor color stability of the specimens, from the first hours of exposure. The addition of titania to polysiloxane specimens works as an opacifier providing a positive effect on the color stability of the examined thermochromic pigment.

Neutrophil Elastase-Activatable Prodrugs Based on an Alkoxyamine Platform to Deliver Alkyl Radicals Cytotoxic to Tumor Cells.

Current chemotherapies suffer low specificity and sometimes drug resistance. Neutrophil elastase activity in cancer is associated with poor prognosis and metastasis settlement. More generally, tumors harbor various and persistent protease activities unseen in healthy tissues. In an attempt to be more specific, we designed prodrugs that are activatable by neutrophil elastase. Upon activation, these alkoxyamine-based drugs release cytotoxic alkyl radicals that act randomly to prevent drug resistance. As a result, U87 glioblastoma cells displayed high level caspase 3/7 activation during the first hour of exposure in the presence of human neutrophil elastase and the prodrug in vitro. The apoptosis process and cell death occurred between 24 and 48 h after exposure with a half lethal concentration of 150 μM. These prodrugs are versatile and easy to synthetize and can be adapted to many enzymes.

AI/ML‐driven simulation of the skin retention of opioid analgesics following topical administration in normal skin and cutaneous lesions

Topical drug administration in the treatment of skin disorders is known to have high efficacy with a favorable safety profile in clinical settings. Disposition of the active pharmaceutical ingredient (API) in the skin layers plays a critical role for the dose regimen calculator required for desired therapy efficiency. Experimental measurements of the API skin concentration are complicated and inaccurate and can be replaced with physiologically based pharmacokinetic modeling predicting local and systemic drug exposure. Opioid analgesics are commonly used in treating severe pain and it is frequently associated with putative adverse effects. Topical applications of opioids were shown to have high efficacy with a favorable safety profile in clinical settings. Clinical investigations of transdermal drug formulations, especially in patients with skin lesions, are often hindered due to the patient intolerance, high cost of the studies, and ethical aspects.BIOiSIM, a hybrid artificial intelligence computational platform integrating machine learning optimization with mechanistic modeling was implemented to accurately simulate in vivo plasma concentration profile and predict partition coefficients and API skin retention for two opioid analgesics in healthy skin and simulated skin lesions. Publicly available drug parameters and physiological data were used for the model building.The platform successfully predicted API systemic exposure and skin concentration following the epicutaneous application of central opioid agonist buprenorphine and peripheral opioid agonist oxycodone in healthy human skin and simulated subjects impaired skin. Experimentally observed plasma concentration for both drugs demonstrated validity of the in‐silico methods. The results indicated that buprenorphine permeates rapidly through the stratum corneum and partitions into the dermis, where its concentration slowly declines as the reservoir in the compound vehicle is depleted. Thus, the impact of lesions is not as significant. In contrast, the hydrophilic oxycodone, where the rate‐limiting stratum corneum layer prevents a significant portion of the compound from permeating deeper in healthy patients. Hence, concentration of oxycodone sharply declines over the first hours of exposure in deeper indicating poorer accumulation capacity in the skin in the presence of lesions.An AI/ML‐driven PBPK model was applied for accurate simulation skin concentrations of two opioid analgesics – buprenorphine and oxycodone. The results have confirmed that both these drugs have good skin retention and can stimulate opioid receptors located in skin. The results suggest that buprenorphine showing substantial skin retention capacity can be applied topically for the treatment of skin disorders in in patients.

Polymerisation Kinetics on FT-IR and Colorimetric Changes under UV Irradiation for a Commercial Polycyanoacrylate Adhesive, Addressed to Glass Restoration

This study evaluates a commercial polycyanoacrylate adhesive of medium viscosity regarding its suitability for the restoration of glass objects of cultural heritage in a museum environment (exhibition/storage). Loctite® Super Attak was investigated in terms of (a) its polymerisation rate and degree of conversion, using Infrared Spectroscopy FT-IR by monitoring the change of the C=C peak vs. C=O peak and (b) the alteration of the colour parameters of its films after its submission to UVC irradiation for several time intervals. It was confirmed that within 6 h, a thin-layered adhesive film acquires 80–85% of its polymerization in ambient conditions, while the reaction continues for up to 12–18 h in the conditions examined. The progress of the reaction is slower when the adhesive is in a protected environment. On the other hand, the effect of UVC rays on the glue is destructive and oxidative, provoking a yellow shade/colour from the first hours of exposure. The intensity of the yellowness becomes higher after 6 h of exposure, showing shifts in the absorption peaks of C–O/C=O groups of the initial IR spectrum and the augmentation of –OH absorptions. It was concluded that the adhesive is suitable for glass restoration, especially for instant, rapid, applications, under mild conditions of maintenance and exposure.

Influence of Age and Genetic Background on Ethanol Intake and Behavioral Response Following Ethanol Consumption and During Abstinence in a Model of Alcohol Abuse.

Genetic background and age at first exposure have been identified as critical variables that contribute to individual vulnerability to drug addiction. Evidence shows that genetic factors may account for 40–70% of the variance in liability to addiction. Alcohol consumption by young people, especially in the form of binge-drinking, is becoming an alarming phenomenon predictive of future problems with drinking. Thus, the literature indicates the need to better understand the influence of age and genetic background on the development of alcohol dependence. To this aim, the inbred rat strains Lewis (LEW, addiction prone) and Fischer 344 (F344, addiction resistant) were used as a model of genetic vulnerability to addiction and compared with the outbred strain Sprague-Dawley (SD) in a two-bottle choice paradigm as a model of alcohol abuse. During a 9-week period, adolescent and adult male rats of the three strains were intermittently exposed to ethanol (20%) and water during three 24-h sessions/week. Adult and adolescent SD and LEW rats escalated their alcohol intake over time reaching at stable levels, while F344 rats did not escalate their intake, regardless of age at drinking onset. Among adolescents, only F344 rats consumed a higher total amount of ethanol than adults, although only SD and LEW rats escalated their intake. Adult LEW rats, albeit having a lower ethanol consumption as compared to SD rats but greater than F344, showed a more compulsive intake, consuming higher amounts of ethanol during the first hour of exposure, reaching a higher degree of ethanol preference when start drinking as adolescents. Behavioral analysis during the first hour of ethanol consumption revealed significant strain differences, among which noticeable the lack of sedative effect in the LEW strain, at variance with F344 and SD strains, and highest indices of withdrawal (most notable jumping) in LEW rats during the first hour of abstinence days. The present results underscore the importance of individual genetic background and early onset of alcohol use in the progression toward abuse and development of alcohol addiction.

Polymer-based nanostructures loaded with piperine as a platform to improve the larvicidal activity against Aedes aegypti

Piperine is an alkaloid extracted from the seed of Piper spp., which has demonstrated a larvicidal effect against Ae. aegypti. The incorporation of piperine into nanostructured systems can increase the effectiveness of this natural product in the control of Ae. aegypti larvae. In this study, we evaluated the effectiveness of piperine loaded or not into two nanostructured systems (named NS-A and NS-B) prepared by the nanoprecipitation method. The Ae. aegypti larvae were exposed to different concentrations of piperine loaded or not (2 to 16 ppm) and the mortality was investigated after 24, 48, and 72 hours. The nanostructures prepared were spherical in shape with narrow size distribution and great encapsulation efficiency. The lethal concentration 50 (LC50) for non-loaded piperine were 13.015 ppm (24 hours), 8.098 ppm (48 hours), and 7.248 ppm (72 hours). The LC50 values found for NS-A were 35.378 ppm (24 hours), 12.091 ppm (48 hours), and 8.011 ppm (72 hours), whereas the values found for NS-B were 21.267 ppm (24 hours), 12.091 ppm (48 hours), and 8.011 ppm (72 hours). Collectively, these findings suggested that non-loaded piperine caused higher larval mortality in the first hours of exposure while the nanostructured systems promoted the slow release of piperine and thereby increased the larvicidal activity over time. Therefore, loading piperine into nanostructured systems might be an effective tool to improve the larval control of vector Ae. aegypti.

Прочность оптических волокон с органическими покрытиями после воздействия аммиака

A study of the effect of ammonia vapor and solution on optical fibers in acrylate, polyimide and carbon/polyimide coatings was carried out to determine the degree of degradation of the mechanical characteristics of optical fibers in an alkaline environment. The ultimate strength of the optical fibers was measured by the two-point bending method, and the coating condition after interaction with ammonia was monitored with an optical microscope. A decrease in the tensile strength was recorded for all the examined types of protective-strengthening coatings starting from the first hour of exposure. It was determined that after 7 days of exposure to gaseous and aqueous ammonia the structure of quartz glass is completely destroyed.

Production aspects of hay of tropical pasture of

Context Tropical pasture have been little explored for haymaking, due to lack of information regarding loss of nutrients and of forage dehydration. Aims This study aimed to evaluate the production aspects of tropical pasture hays. Methods To characterise forage dry mass yield and dehydration rate, we studied the grasses Marandú, Xaraés, Massai, Paredão, Planaltina and Tupã. The water soluble carbohydrates concentration curve, chemical composition and in situ rumen degradability of dry mass, crude protein and neutral detergent fibre were also determined. Key results The highest forage dry mass yield was observed in 2018, when Planaltina and Paredão performed best (6.28 and 5.26 ± 0.41 t of dry matter ha−1, respectively). There was no genotype × dehydration time interaction (P = 0.81) on water soluble carbohydrates. Exposure to sun resulted in a linear decreasing effect (P &lt; 0.01) on water soluble carbohydrates content, with loss of 5.03 g kg−1 for each hour of exposure to the sun during the haymaking process. There was an interaction effect (P &lt; 0.01) between type of material and genotype on the content of dry matter, mineral matter, crude protein and neutral detergent fibre (P &lt; 0.01). In situ degradability of Massai grass dry mass was higher for the hay (758.0 and 253.8 ± 7.9 g kg−1 for hay and in natura material, respectively). Conclusions and implications The greater amount of leaves in relation to stem indicates that Massai grass is more efficient in dehydration during the first hours of exposure to the sun, as well as sustaining lower losses.

The impact of chemical composition of halide surface ligands on the electronic structure and stability of lead sulfide quantum dot materials.

There is a high fundamental interest in the surface and bulk chemistry of quantum dot (QD) solids, as they have proven to be very promising materials in optoelectronic devices. The choice of surface ligands for quantum dots in solid devices determines many of the film properties, as the ligands influence for example the doping density, chemical stability and charge transport. Lead halide ligands have developed as the main ligand of choice for lead sulfide quantum dots, as they have been shown to passivate quantum dot surfaces and enhance the chemical stability. In this study, we successfully varied the ligand composition on the surface of PbS quantum dot films from pure lead iodide to pure lead bromide and investigated its influence on the chemical and electronic structure of the QD solids using hard X-ray photoelectron spectroscopy (HAXPES). Furthermore, we developed a surface treatment to prevent the surface oxidation of a bulk PbS reference sample. Through measurements of this sample and of lead halide reference samples, we were able to assign the contributions of different chemical bonding to the Pb 4f core level and of different atomic orbitals to the valence band spectral shape of the QD materials. Overall, we found that the valence band edge position was very similar for all different iodide:bromide ratios and that all investigated compositions were able to protect the quantum dot surfaces within solid films from oxidation. However, the ligand composition significantly influences the sample stability under X-rays. The iodide rich QD solids showed the highest stability with very little to no chemical changes over several hours of X-ray exposure, while the bromide rich QD solids changed already within the first hour of exposure.