Prolonged Exposure Time Research Articles

The combined toxicity influence of microplastics and nonylphenol on microalgae Chlorella pyrenoidosa.

Microplastics and nonylphenol (NP) are considered as emerging pollutant and have attracted wide attention, while their combined toxicity on aquatic organisms is barely researched. Therefore, the combined toxicity influence of NP with three types of microplastics containing polyethylene (PE1000, 13μm and PE, 150μm), polyamide (PA1000, 13μm and PA, 150μm) polystyrene (PS, 150μm) on microalgae Chlorella pyrenoidosa was analyzed. Both growth inhibition, chlorophyll fluorescence, superoxide dismutase (SOD), malondialdehyde (MDA), and catalase (CAT) were determined. We found that single microplastics and NP both inhibited algal growth, thereby causing oxidative stress. The order of inhibition effect in single microplastics experiment was PE1000>PA1000>PE≈PS>PA. The combined toxicity experiment results indicated that the presence of microplastics had positive effect in terms of alleviating NP toxicity to C. pyrenoidosa, and the microplastics adsorption capacity to NP was the dominant contributing factor for this effect. According to the independent action model, the combined toxicity was antagonistic. Because the negative effect of smaller size microplastics on algal growth was aggravated with prolonged exposure time, the optimum effect of microplastics alleviated NP toxicity was PA1000 at 48h, while this effect was substituted by PA at 96h during combined toxicity. Thus, the toxicity of smaller size microplastics has a nonnegligible influence on combined toxicity. This study confirms that microplastics significantly affected the toxicity of organic pollutants on microalgae. Further research on the combined toxicity of smaller size microplastics with pollutants in chronic toxicity is needed.

Polypyrrole Modified E-Coat Paint for Corrosion Protection of Aluminum AA1200

This article reports the potential of Polypyrrole (PPy) particles as anticorrosive additive on an epoxy water-based paint to increase the corrosion protective property of aluminum-coated panels. AA1200 aluminum panels were painted using the electrophoretic deposition method and the coatings with different concentrations of PPy particles tested. PPy particles were synthetized by oxidative polymerization of pyrrole (Py) with iron (III) chloride hexahydrate (FeCl3.6H2O) in the presence of dodecylbenzenesulfonic acid (DBSA). Electrically conducting PPy particles (6.5 S.cm-1) were obtained with a size average of 154 nm. The as-prepared PPy particles were added into a water-based epoxy paint and AA1200 panels were coated via electrophoretic deposition method. The corrosion protective properties of e-coated AA1200 panels were evaluated by means of electrochemical impedance spectroscopy over prolonged exposure time in neutral non-aerated 0.1 M NaCl electrolyte. In particular, the addition of 0.4 wt. % PPy has improved the coating corrosion protective property with respect to epoxy clearcoat and exhibited the highest value among the studied coatings.

Effects of Non-Lethal High-Temperature Stress on Bradysia odoriphaga (Diptera: Sciaridae) Larval Development and Offspring.

Throughout China, the dipteran pest Bradysia odoriphaga significantly reduces Chinese chive production; therefore, identifying conditions that influence its growth and development is crucial for developing ecological regulation strategies. In this study, different non-lethal high temperatures and treatment durations were used to stress the third-instar larvae of B. odoriphaga, and the effects of this treatment on their growth and offspring were recorded and analyzed. The results showed that the average larval mortality increased with increased temperature and prolonged exposure times. After stress treatment at 40 °C for 2 h, 100% of larvae died within 5 days, which was not significantly different from the 5-day average larval mortality (90.66%) after stress at 37 °C for 4 h, but significantly higher than the 5-day average larval mortality (72.00%) after stress at 40 °C for 1 h. After 5 days, all still-living larvae could pupate, and there was no significant difference in average pupal period after pupation. However, the eclosion rate of subsequent pupae decreased with increased temperature and prolonged exposure times, and were only 43.00% and 42.73% after larvae were stressed at 37 °C for 4 h and 40 °C for 1 h, respectively. After eclosion into adults, there was no significant difference in the lifespan of unmated female adults, while the lifespan of unmated male adults was significantly reduced to 1.67 d and 2 d after larvae were stressed at 37 °C for 4 h and 40 °C for 1 h, respectively. However, there was no significant difference in male and female adult longevity after mating. There was no significant difference in oviposition or egg hatchability. This indicates that non-lethal high temperature at 37 °C for 4 h can hinder development and allow control of B. odoriphaga. There is great potential for non-lethal high temperature to be applied in the field to control agricultural pests.

Effects of short‐term heat stress on the growth and development of Bradysia cellarum and Bradysia impatiens

AbstractBradysia cellarum Frey and Bradysia impatiens Johansen are major pests of vegetable crops, as well as edible mushrooms and ornamental plants, and damage to hosts resulting in economic losses. Temperatures above the optimum levels for these pests have been predicted to regulate their population growth during summer. The aim of the present study was to examine the effects of both heat stress and exposure time on the growth and development of eggs, larvae and pupae for two Bradysia species. The egg stage, egg hatching rate, 4th instar larval stage, pupation rate, pupal stage and adult emergence rate were observed after exposing at high temperatures of 34°C, 37°C and 40°C for 1, 2, 4 and 6 hr. The results showed that 34°C, 37°C and 40°C for 1‐, 2‐, 4‐ and 6‐hr exposure treatments prolonged the developmental stage of egg, 4th instar larva and pupa, while decreasing the egg hatching rate, pupation rate and adult emergence rate. This suggests that increasing temperature or prolonging exposure time to the heat stress could significantly affect insect survival, growth and development. Our study could provide an ecological basis for pests’ management strategy by using short‐term heat stress.

Evaluation of the Oxidative Stress Status in Zebrafish (Danio rerio) Liver Induced by Three Typical Organic UV Filters (BP-4, PABA and PBSA).

Organic UV filters are a kind of emerging pollutants, which have been widely used in personal care products (PCPs). This study evaluated the effects of benzophenone-4 (BP-4), 4-aminobenzoic acid (PABA), and 2-phenylbenzimidazole-5-sulfonic acid (PBSA) on the selected indices of antioxidative responses in zebrafish (Danio rerio) liver. Zebrafish were exposed to two different doses (i.e., 0.5 and 5 mg L−1) of semi-static water with three individual compounds. Liver samples were collected on 7 and 14 days to analyze biochemical indicators, including superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH), and malondialdehyde (MDA). Oxidative stress occurred in zebrafish liver with significantly changed indicators during the whole exposure period. Different experimental groups could induce or inhibit the activity of antioxidant enzymes with varying degrees. With a prolonged exposure time and increased exposure dose, the hepatic lipid peroxidation was also obviously observed. Moreover, the toxicity order of three organic UV filters was analyzed using the integrated biomarker response (IBR) index and the results indicate that exposure to PABA for 7 days at 0.5 mg L−1 and PBSA for 7 days at 5 mg L−1 induced the most severe oxidative stress in the liver of zebrafish.

Impact of prolonged cardiopulmonary bypass and operative exposure time on the incidence of surgical site infections in patients undergoing open heart surgery: Single center case series

IntroductionSurgical site infections (SSIs) are either superficial or deep and may involve the organ. The reported incidence of SSIs in coronary artery bypass grafting (CABG) surgery ranges from 0.3% to 8%. While the incidence of superficial wound infection is 3–5% and deep sternal wound infection is 0,5-5%. Objectives of the current study is to determine the relation of prolonged CPB time and rate of SSI in patients underwent open heart surgery. Methodsprospective observational study included all patients underwent open heart surgery in our center, The patients followed-up within 2–3 month of their periodical visits. The data collection was performed from January 1st 2018 to January 1st 2019. Relevant data were entered into a database created using Microsoft Access 2007 program & then analyzed via specific queries. ResultsThe mean age of the patients were 55.32 (SD: 22.82 years) ranged from 30 to 81 years. Most of the patients were male 69.7%). The mean exposure time of the operation and cardiopulmonary bypass time (CBPT) were 4.30 (SD: 1.0 h) and 140.38 (SD: 56.03 min), respectively. The mean duration of the patients in ICU was 21.34 (SD: 7.58 h).In this study, 17 patients (4.5%) developed SSIs. The incidence of prolonged surgery was 37.8%. The study showed that those patients developed infection had a greater operation exposure time (4.88 vs. 4.27hrs.), and CBPT (161.59 vs. 56.53 min). ConclusionThe operation exposure and CBP times were directly related to the occurrence of surgical site infection.

EVALUATION OF THE HEAVY METALS IONS INFLUENCE ON THE TROPHIC BEHAVIOR OF MOLLUSCS (GASTROPODA)

In an acute experiment (48 h), the influence of ions of heavy metals (copper, cadmium, nickel, zinc, cobalt, man- ganese) were investigated for the basic trophological indicators of pond snails (Lymnaea stagnalis, L.): the average daily ration (ADR) and the duration of food passage (DFP) in various concentration ranges of the toxicants. We also determined the total amount of mollusk food consumed in the solutions with various concentrations of pollutants dur- ing the chronic experiment (30 days) and it was calculated for an individual (average monthly ration – AMR). The obtained results enabled us to draw conclusions about the intensity of food intake at different levels of intoxication. In solutions of acute lethal concentrations, snails die within the first days of toxic exposure as a result of damage to their tissues and organ systems. In such an environment, the mollusks almost do not eat, so it is not possible to establish trophic indicators. Chronic lethal concentrations of toxicants dramatically inhibit the nutrition of pond snails. At the beginning of the experiment solutions of heavy metals with sublethal concentrations give some stimulatory effect on the digestive system of mollusks that is replaced by its suppression in case of longer being in the toxic environment. The influence of toxicants within a subthreshold limit cannot be considered safe because of the cumulative properties of heavy metals – they become sublethal with prolonged exposure time. We have noticed a tendency to decrease the basic trophic indicators of mollusks with the increasing of heavy metals concentration in the environment. The re- duction of the amount of food consumed by ponds in sublethal concentrations is offset by the prolonged time of the forage keeping in the digestive tract of mollusks.

Developmental toxicity of disinfection by-product monohaloacetamides in embryo-larval stage of zebrafish.

As an emerging class of nitrogenous disinfection by-products (N-DBPs), haloacetamides (HAcAms) have been widely detected in drinking water. Limited toxicity studies have shown an inconsistent toxicity of monoHAcAms, including CAcAm, BAcAm and IAcAm. In this study, the developmental toxicity of monoHAcAms was evaluated in embryo-larval stage of zebrafish. Embryos were exposed to one concentration of 2.50, 5.00, 10.0, 20.0, 40.0 and 80.0mg/L monoHAcAms from 4h post-fertilization (hpf) to 120 hpf. Multiple endpoints, including hatching rate, morphological abnormalities, mortality as well as locomotor behavior were assessed at specified stages (24, 48, 72, 96 and 120 hpf). Results showed that 80mg/L CAcAm and 40mg/L BAcAm significantly decreased the hatching rate, IAcAm decreased the hatching rate and delayed the hatching process in a concentration-dependent manner with an EC50 of 16.37mg/L at 72 hpf. The frequency and severity order of morphological abnormalities increased with the raised exposure concentrations and prolonged exposure time, and the corresponding EC50 at 96 hpf were 21.10, 9.77 and 16.60mg/L for CAcAm, BAcAm and IAcAm, respectively. MonoHAcAms exposure resulted in a time- and dose-dependent response in mortality and the calculated LC50 at 72 hpf were 38.44, 17.74 and 28.82mg/L for CAcAm, BAcAm and IAcAm, respectively. Based on EC50 for morphological abnormalities and LC50, a toxicity rank order of BAcAm>IAcAm>CAcAm was observed. Different degrees of hyperactivity and hypoactivity were observed from locomotor behavior analysis in larvae from ≤10.0mg/L monoHAcAms exposure groups. The light-dark periodic change was disappeared in larvae of 10.0mg/L BAcAm exposure group. In summary, our study showed that monoHAcAms were developmentally toxic to zebrafish even at very low concentrations and BAcAm exerted higher toxicity than IAcAm and CAcAm. These results will further our understanding of the toxicity of HAcAms and its potential toxicological impact on human and ecological environment.

Assessment of the immobilization effectiveness of several amendments on a cadmium-contaminated soil using Eisenia fetida.

Proper protocols for assessing the remediation effectiveness of contaminated soils are an important part of remediation projects. In the present study, the residual immobilization effectiveness of hydrated lime (L), hydroxyapatite (H), biochar (B) and organic fertilizer (F) alone and in combination was assessed by Eisenia fetida. The results showed that the application of amendments had no significant effect on the death rate and average fresh weight loss of earthworms. The earthworm Cd concentration increased with prolonged exposure time, however, the significant immobilization efficacy of amendments observed on the 7th day nearly disappeared after 28 days of exposure. The immobilization efficiencies, estimated by the earthworms internal Cd concentration, of L, H and B on the 7th day were 38.6%, 37.8% and 20.7%, respectively. These values decreased to 4.9%, 19.8% and 15.1%, respectively, on the 28th day. The detoxification effect of amendments was confirmed by the Cd subcellular fractionation in earthworms with lower proportions of Cd distributed in the metal-sensitive fractions in L, H and B treatments. The level of oxidative stress response of earthworms increased with exposure duration and amendments alleviated the oxidative damage induced by Cd to the earthworms. In addition, the pH and CaCl2-Cd in soils were both increased due to earthworm life activities and gut-related ingestion. In summary, the assessment of immobilization effectiveness of heavy metal-contaminated soils using Eisenia fetida was time-dependent. The immobilization efficacy of L and H performed better than B and F on the 7th day, while H and B performed better than L and F on the 28th day. Accordingly, the short-term earthworm exposure experiment (7 days) was recommended to be an alternative approach to time-consuming plant bioassays in assessment of reduced phytoavailability in chemical immobilization remediation. But the impact of earthworms on the immobilization effect of amendments needs to be considered in practical remediation.

Open source 3D printable replacement parts for the WHO insecticide susceptibility bioassay system

BackgroundMalaria vector control and research rely heavily on monitoring mosquito populations for the development of resistance to public health insecticides. One standard method for determining resistance in adult mosquito populations is the World Health Organization test (WHO bioassay). The WHO bioassay kit consists of several acrylic pieces that are assembled into a unit. Parts of the kit commonly break, reducing the capacity of insectaries to carry out resistance profiling. Since there is at present only a single supplier for the test kits, replacement parts can be hard to procure in a timely fashion.MethodsUsing computer-aided design software and widely available polylactic acid (PLA) filament as a printing material, we 3D designed and printed replacement parts for the WHO bioassay system. We conducted a comparison experiment between original WHO bioassay kits and 3D printed kits to assess congruence between results. The comparison experiment was performed on two Kenyan laboratory strains of Anopheles gambiae (s.s.), Kilifi and Mbita. Studentʼs t-tests were used to assess significant differences between tube types. Finally, we exposed the PLA filament to common solutions used with the bioassay kit.ResultsWe were able to design and print functional replacements for each piece of the WHO bioassay kit. Replacement parts are functionally identical to and interchangeable with original WHO bioassay parts. We note no significant difference in mortality results obtained from PLA printed tubes and WHO acrylic tubes. Additionally, we observed no degradation of PLA in response to prolonged exposure times of commonly used cleaning solutions.ConclusionsOur designs can be used to produce replacement parts for the WHO bioassay kit in any facility with a 3D printer, which are becoming increasingly widespread. 3D printing technologies can affordably and rapidly address equipment shortages and be used to develop bespoke equipment in laboratories.

Chemical cleaning of algae-fouled ultrafiltration (UF) membrane by sodium hypochlorite (NaClO): Characterization of membrane and formation of halogenated by-products

This paper presents an investigation of the variation in membrane characteristics and formation of halogenated by-products during the off-line chemical cleaning of algae-fouled ultrafiltration (UF) membrane by NaClO solution. The chemical treatment led to the recovery of membrane flux, decrease of membrane hydrophilicity and HA rejection. Proteins, amino acids, and polysaccharides contained in algal cells were easy to adsorb on the membrane surface and contributed to the formation of halogenated by-products during the NaClO cleaning process. The increase of NaClO concentration and temperature significantly promoted the formation of most selected halogenated by-products. With the increase of pH, trichloromethane (TCM), dichloroacetic acid (DCAA) and trichloronitromethane (TCNM) rose continuously; monochloroacetic acid (MCAA), trichloroacetic acid (TCAA) and trichloroacetonitrile (TCAN) followed an increasing and then decreasing trend. With the prolonged exposure time from 2 to 24 h, most halogenated by-products from the cleaning of algal cell-, extracellular organic matter (EOM)- and humic acid (HA)-fouled membranes monotonically increased, while the formation of 1,1-dichloro-2-propanone (DCP) and dichloroacetonitrile (DCAN) varied differently. NaClO cleaning of algal cell-fouled membrane generated much lower concentrations of selected carbonaceous halogenated by-products and TCNM, but caused higher yields of haloacetonitriles (HANs) than that of HA-fouled membrane.

Corrosion characteristic comparisons of ZrO2-, TiO2-coated and uncoated 316 stainless steel samples in supercritical water oxidation of municipal sludge

Supercritical water oxidation (SCWO) can efficiently and harmlessly dispose municipal sludge (MS), but typically faces severe reactor corrosion problems. In this work, 316 stainless steel (316SS) sample surface was processed by atmospheric plasma spraying to form a protective ZrO2 or TiO2 coating. The 316SS, ZrO2/316SS and TiO2/316SS samples were exposed to a typical MS SCWO environment (at 450 °C, 24 MPa and 1.2 of oxidation coefficient) for 20 h–150 h. The results show that prolonging exposure time increased corrosion and surface coating could inhibit 316SS corrosion. ZrO2/316SS showed the best corrosion resistance among 316SS, ZrO2/316SS and TiO2/316SS, and its maximum corrosion rate was 0.0097 mg·cm−2·h-1. The oxide film of ZrO2/316SS after 150 h of corrosion exposure consisted of ZrO2, FeO, Fe2O3, NiO and Cr2O3, and its inner layer was rich in Cr2O3. The ZrO2 coating was much more stable than the TiO2 coating, and can be considered as the coating of the 316SS structure material for a MS SCWO reactor.

In vitro time-kill kinetics of dalbavancin against Staphylococcus spp. biofilms over prolonged exposure times

Staphylococcus aureus and Staphylococcus epidermidis are leading pathogens of biofilm-related infections and represent the most common cause of osteomyelitis and biomedical implants infections. Biofilm-related infections usually require long-term antibiotic treatment, often associated to surgical interventions. Dalbavancin is a newer lipoglycopeptide approved for the treatment of acute skin and skin-structure infections caused by Gram-positive pathogens. In addition, dalbavancin has recently been considered as a potential option for the treatment of staphylococcal osteomyelitis and orthopedic implant infections.In this study, time-kill kinetics of dalbavancin against S. aureus and S. epidermidis biofilms were determined over prolonged exposure times (up to 7 days), using both a standardized biofilm susceptibility model and biofilms grown onto relevant orthopedic biomaterials (i.e. titanium and cobalt-chrome disks). Dalbavancin (at concentrations achievable in bone and articular tissue) showed a potent activity against established staphylococcal biofilms in both tested models, and was overall superior to the comparator vancomycin.

Water Inhibition in Methane Oxidation over Alumina Supported Palladium Catalysts

In situ diffuse reflectance infrared Fourier transform spectroscopy has been used to distinguish surface hydroxyl groups on Al2O3 and PdO/Al2O3 model catalysts calcined at 500-900 °C. Employing the operando approach, the formation of surface hydroxyl groups has been correlated to the methane oxidation activity for PdO/Al2O3 catalysts using a PdO powder sample as reference. The results show that the alumina support stabilizes active PdO particles leading to enhanced apparent methane turnover frequency (TOF), which decreases slowly in dry conditions due to alumina hydroxylation. Wet conditions cause severe hydroxylation that is detrimental for the methane TOF. The hydroxylation follows two different routes, i.e., spillover of hydrogen-containing species to the PdO-Al2O3 boundary and/or the close proximity of the supported PdO particles and under wet conditions also dissociation of gas phase water on the entire alumina surface. Both hydroxylation routes obey varying kinetics such that near saturation is reached quickly (minutes) followed by a continuous slow growth for prolonged exposure times (hours). At low temperatures, inhibition of palladium active sites on the rim of the PdO particles close to alumina seems to be of particular importance for the observed detrimental effect of water, whereas water induced morphological changes (no sintering observed) of the PdO particles play a minor role.

Guadecitabine (SGI-110): an investigational drug for the treatment of myelodysplastic syndrome and acute myeloid leukemia

ABSTRACTIntroduction: The incidence of acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) is increasing with the aging population. Prognosis and overall survival (OS) remain poor in elderly patients and in those not eligible for intensive treatment. Hypomethylating agents (HMAs) have played an important role in this group of patients but their efficacy is limited.Areas covered: This article reviews the mechanism of action, pharmacology, safety profile and clinical efficacy of subcutaneous guadecitabine, a second-generation DNA methylation inhibitor in development for the treatment of AML and MDS.Expert opinion: Although guadecitabine did not yield improved complete remission (CR) rates and OS compared to the control arm in patients with treatment-naïve AML who were ineligible for intensive chemotherapy, subgroup analysis in patients who received ≥4 cycles of therapy demonstrated superior outcomes in favor of guadecitabine. Given its stability, ease of administration, safety profile and prolonged exposure time, guadecitabine would be the more appropriate HMA, replacing azacitidine and decitabine, to be used combination treatment regimens in patients with myeloid malignancies.

A rapid method for screening and determination test of methanol content in ethanol-based products using portable Raman spectroscopy

Raman spectroscopy is nondestructive sample preparation and suitable for use in quality control-related field inspections, particularly on ethanol-based products. The influence of laser power density (PD) and exposure time (ET) on the Raman spectra similarity, specificity, selectivity, and accurate measurements for screening and determination of methanol content were carried out in this study.Raman spectra of samples were measured using a Raman handheld instrument. Measuring scales of PD and ET were varied from 50 to 300 milliWatt (mW) and 1000–5000 ms (ms), respectively. The similarity of Raman-spectra of those samples was statistically analysed with the help of hierarchical cluster analysis (HCA) and cross-correlation function (Ccorrel). The subtracted Raman spectra and pure ethanol spectra were implemented to identify methanol content in samples of ethanol-based products specifically.The Raman spectra measured at PD of 200–300 mW and clustered in one group by ward linkage method showed a similarity level of 99.98%. The variation of ET between 1000 and 5000 ms on fix PD of 300 mW showed high precision (RSD <2%) with more than 99% similarity of Raman spectra. Rinsing of PD was found to increase the signal: noise ratio, while prolonged exposure time reduced the signal: noise ratio. The precision and accuracy measurements were obtained by setting the PD and ET values of 300 mW and 4000 ms, respectively. The subtracted Raman spectra with the spectra of absolute ethanol introduced a simultaneous screening of methanol containing alcohols and determination of both substances.

Protez kaide rezinleri üzerindeki Candida albicans'ın uzaklaştırılmasında protez temizleyici tabletlerin etkin sürelerinin belirlenmesi

Objective: The aim of this study was to determinate of the effective time of different denture cleanser tablets on the removal of Candida albicans on various base resins. Materials and Methods: Conventional heat cured resin, high impact resin, autopolymerized resin, and polyamide resin were used. 160 samples were prepared for each resin type. The biofilm of C. albicans was formed on the resins and then exposed to alkaline peroxide tablet and enzymatic tablets for 3-5-10-20-40-80-160-200 minutes. Cell viability was assessed by MTT test. 3-way ANOVA was used for statistical analysis. Results: The effect of resin type, tablet type and application time on cell viability of C. albicans were found to be significant (p&amp;lt;0.05). Cell death was at least 65% on the resins even at the minimum time. Furthermore, as the duration of administration of both tablets increased, cell viability in all resins tended to decrease. The administration of both tablets on all resins for 10 min resulted in approximately 80% cell death. Additionally, the most significant antimicrobial activities of the tablets were determined on 20th minutes. The alkaline peroxide tablet on all base resins for application periods of 3 to 200 minutes was generally more effective than the enzymatic tablet. Conclusion: Alkaline peroxide and enzymatic cleanser tablets showed remarkable anticandidal activity for all resins. The patients with risk of C. albicans infection should keep their prostheses in cleanser tablets for at least 20 minutes. Furthermore, the anticandidal effect tended to increase with prolonged exposure time.

Microbial community evolution and fate of antibiotic resistance genes in anammox process under oxytetracycline and sulfamethoxazole stresses

The microbial community characteristics, functional and antibiotic resistance genes (ARGs), anammox performance under individual and combined oxytetracycline (OTC) and sulfamethoxazole (SMX) were tested under environmentally relevant levels. The results showed that anammox performance was inhibited when the OTC or SMX concentration increased from 0.5 to 1.0 mg L−1. The absolute abundance of tetX in OTC (3.03 × 106 copies mg−1), SMX (2.80 × 106 copies mg−1) and OTC + SMX (2.03 × 106 copies mg−1) was the highest and one more order of magnitude higher than that of tetG, tetM, intI1, or sul2. The anammox performance in the presence of OTC or SMX was lower than that sum of their independent effects. The enrichment of sludge resistomes with prolonged exposure time and increasing OTC and SMX doses might be due to succession of bacterial hosts and potential elevation of ARGs by horizontal transfer.

Trophic characteristics of Lymnaea stagnalis (Mollusca: Gastropoda: Lymnaeidae) in toxic environment

Abstract The influence of ions of heavy metals (copper, cadmium, nickel, zinc, cobalt and manganese) was investigated on the basis of trophic characteristics: the average daily ration (ADR), and duration of food passage (DFP) of the Lymnaea stagnalis L. in various concentrations of toxicants in vivisection experiment. In addition to these indicators, the total amount of food consumed in the solutions with various concentrations of pollutants was found out during the chronic experiment and it was calculated for an individual (average monthly ration – AMR). It leads to the conclusions about the intensity of food consuming considering different levels of intoxication. In solutions with lethal concentrations, the death of animals occurs during the first day of its impact due to the damage of tissues and organ systems. Chronic lethal concentrations of toxicants inhibit the nutrition of pond snails dramatically. At the beginning of the experiment, solutions of heavy metals with sublethal concentrations give some stimulatory effect on the digestive system of molluscs that is replaced by its suppression in case of longer being in the toxic environment. The influence of toxicants within a subthreshold limit cannot be considered safe because of the cumulative properties of heavy metals – they become sublethal with prolonged exposure time.

Burning postharvest sugarcane residue for control of surface-deposited divine nightshade (Solanum nigrescens) and itchgrass (Rottboellia cochinchinensis) seed

AbstractBurning postharvest sugarcane residue is a standard practice to remove extraneous leaf material before spring regrowth. Live-fires were simulated from field-collected postharvest sugarcane residue and seeds of divine nightshade and itchgrass were exposed to dry and moistened postharvest residue (PHR) at four densities (6.1, 12.1, 18.2, and 24.2 Mg ha−1) and a nonburned control. The moisture content of residue exposed to simulated rainfall was 14% more in Experiment 2 than Experiment 1; however, burning PHR with 44% moisture when wind speeds were lower allowed the fire to continue and created a smoldering effect that reduced weed emergence by 23% when compared with burning PHR with 30% moisture during breezy conditions. The moistened 6.1 Mg ha−1 PHR treatment resulted in 53% more divine nightshade and itchgrass emergence when compared with dry 6.1 Mg ha−1 PHR after burning, and greater emergence was attributed to more seed survival for divine nightshade than itchgrass. The PHR moisture condition failed to influence the burn duration; however, the burn duration increased 103% and 56% as the amount of PHR increased from 6.1 to 12.1 Mg ha−1 and 12.1 to 18.2 Mg ha−1, respectively. The combination of high wind speeds and moistened PHR did not enhance the maximum burn temperature near the soil surface, but surface-deposited divine nightshade and itchgrass seeds were susceptible to prolonged exposure times at 100 C. Burning PHR from fields with poor stands or older ratoon, especially when PHR is abundantly wet, will not produce temperatures lethal to divine nightshade and itchgrass seeds. The fluid-filled and fleshy content that comprises divine nightshade fruit protected seed from short durations of high temperatures, but may not insulate seeds long enough when exposed to a smoldering fire.