High Residual Concentrations Research Articles

Accumulation and Determination of Phenylethanolamine A Residue in Hair of Swine and Sheep.

The present study proposed the use of liquid chromatography-tandem mass spectrometry to detect the novel β-agonist phenylethanolamine A (PEA) in incurred hair samples of swine and sheep and to assess its accumulation for residue monitoring. The method showed good percent recoveries ranging from 93.2% to 102% and good coefficient of variation at <15%. The experiment was conducted in swine (24 treated and 4 controls) and sheep (3 treated and 1 control). PEA concentration was determined in hair during the treatment. High residue concentrations were present in hair as early as Day 24 (14.8±3.6 and 25.8±7.6 ng/g) and Day 21 (23.4±6.6 ng/g) for swine and sheep; these residues persisted until withdrawal on Days 14 and 21. Results showed high PEA accumulation in hair, thereby indicating the use of hair as a matrix in the control of PEA abuse in farm animals.

Froth Flotation of Copper and Copper Compounds from Fine Fractions of Waste Incineration Bottom Ashes

AbstractIn Germany about 5 million tons of municipal solid waste incineration (MSWI) bottom ashes are treated for metal recovery annually. With the actual processing metal recovery is realized down to 2 mm. The fractions &lt; 2 mm are utilized without metal recovery. Due to high residual concentrations of non‐ferrous metals in these fractions, especially Cu, several thousand tons of metals are lost every year. This article presents an approach to recover Cu of fine fractions &lt; 0.2 mm by froth flotation. Several collector regimes are screened and flotation parameters are varied. First results exhibit Cu recoveries of 50 % with Cu concentrations of about 5 %.

Influence of Metal Transfer Stability and Shielding Gas Composition on CO and CO2 Emissions during Short-circuiting MIG/MAG Welding

Abstract: Several studies have demonstrated the influence of parameters and shielding gas on metal transfer stability or on the generation of fumes in MIG/MAG welding, but little or nothing has been discussed regarding the emission of toxic and asphyxiating gases, particularly as it pertains to parameterization of the process. The purpose of this study was to analyze and evaluate the effect of manufacturing aspects of welding processes (short-circuit metal transfer stability and shielding gas composition) on the gas emission levels during MIG/MAG welding (occupational health and environmental aspects). Using mixtures of Argon with CO2 and O2 and maintaining the same average current and the same weld bead volume, short-circuit welding was performed with carbon steel welding wire in open (welder’s breathing zone) and confined environments. The welding voltage was adjusted to gradually vary the transfer stability. It was found that the richer the composition of the shielding gas is in CO2, the more CO and CO2 are generated by the arc. However, unlike fume emission, voltage and transfer stability had no effect on the generation of these gases. It was also found that despite the large quantity of CO and CO2 emitted by the arc, especially when using pure CO2 shielding gas, there was no high level residual concentration of CO and CO2 in or near the worker’s breathing zone, even in confined work cells.

Evaluation of using aluminum sulfate and water-soluble Moringa oleifera seed lectin to reduce turbidity and toxicity of polluted stream water

Aluminum salts are used as coagulants in water treatment; however, the exposure to residual aluminum has been associated with human brain lesions. The water-soluble Moringa oleifera lectin (WSMoL), which is extracted with distilled water and isolated by chitin chromatography, has coagulant activity and is able to reduce the concentration of metal ions in aqueous solutions. This study evaluated the potential of using aluminum sulfate and WSMoL to reduce the turbidity and toxicity of water from the Cavouco stream located in Recife, Pernambuco, Brazil. The water sample used (called P1) was collected from the stream source, which was found to be strongly polluted based on physicochemical and water quality analyses, as well as ecotoxicity assays with Artemia salina and seeds of Eruca sativa and Lactuca sativa. The assays combining WSMoL and aluminum sulfate were more efficient than those that used these agents separately. Furthermore, the greatest reduction in turbidity (96.8%) was obtained with the treatment using aluminum sulfate followed by WSMoL, compared to when they were applied simultaneously (91.3%). In addition, aluminum sulfate followed by WSMoL treatment resulted in residual aluminum concentration (0.3 mg/L) that was much lower than that recorded after the treatment using only the salt (35.5 mg/L). The ecotoxicity of P1 was also strongly reduced after the treatments. In summary, the combined use of aluminum sulfate and WSMoL was efficient in promoting a strong reduction of turbidity and ecotoxicity of a polluted water sample, without resulting in a high residual aluminum concentration at the conclusion of the treatment.

Application of redox potential control to improve ethanol productivity from inulin by consolidated bioprocessing

Long fermentation time and high residual sugar concentration represent significant challenges for the ethanol production from inulin-containing feedstock by Kluyveromyces marxianus, which possesses the advantages of high temperature resistance, rapid growth and high level of native inulinase secretion. To solve the problems, an applicable strategy in ethanol production from inulin was developed. Batch fermentations were conducted by oxidation-reduction potential (ORP) control. When the ORP was controlled at −130mV, the highest ethanol concentration and productivity, 97.7g/L and 2.04g/L/h, were achieved, with the residual sugar concentration of 3g/L. The high cell viability ensured an effective conversion of total sugar to ethanol, leading to a low sugar concentration at the terminal. Metabolic flux analysis (MFA) demonstrated that significant differences in EMP, PPP and some nodes after pyruvate under different ORPs. With the increase of ORP from −150 to −100mV, total sugar uptake rate increased from 195.11 to 223.13Cmmol/L/h. Controlling ORP at −130mV was the most suitable strategy for the industrialization of ethanol production from inulin reported so far.

Accumulation of steroid hormones in soil and its adjacent aquatic environment from a typical intensive vegetable cultivation of North China

Steroid hormones released from manure agricultural application are a matter of global concern. The residual levels of steroid hormones were studied in a typical intensive vegetable cultivation area in northeast China, with a long history of heavy manure application. Seven steroids (estrone, 17α-estradiol, 17β-estradiol, estriol, testosterone, androstendione and progesterone) were analyzed from soil sampled from vegetable greenhouses, from sediments and water from the adjacent drainage ditch and from the groundwater. The results showed that target steroids were detected in the soil samples, with detection frequencies varying from 3.13 to 100%. The steroid concentrations varied substantially in soils, ranging from below the detection limit to 109.7μg·kg−1. Three steroids—progesterone, androstendione and estrone—were found to have relatively high residue concentrations in soil, with maximum concentrations of 109.7, 9.83 and 13.30μg·kg−1, respectively. In adjacent groundwater, all the steroids, with the exception of estrone, were detected in one or more of the 13 groundwater samples. The concentrations of steroids in groundwater ranged from below the method detection limit to 2.38ng·L−1. Six of the seven (excluding androstendione) were detected in drainage ditch water samples, with concentrations ranging from below the detection limit to 14ng·L−1. Progesterone, androstendione and estrone accumulated relatively easily in soils; their concentrations in groundwater were lower than those of other steroids. The concentrations of testosterone and estriol were relatively low in soil, while in groundwater were higher than those of other steroids. The residual levels of steroids in soil and groundwater showed a clear spatial variation in the study area. The residual levels of steroid hormones in soil varied substantially between differently planted greenhouses.

Metalorganic chemical vapor deposition growth of high-mobility AlGaN/AlN/GaN heterostructures on GaN templates and native GaN substrates

Severe surface decomposition of semi-insulating (SI) GaN templates occurred in high-temperature H2 atmosphere prior to epitaxial growth in a metalorganic chemical vapor deposition system. A two-step heating process with a surface stabilization technique was developed to preserve the GaN template surface. Utilizing the optimized heating process, a high two-dimensional electron gas mobility ∼2000 cm2/V·s was obtained in a thin AlGaN/AlN/GaN heterostructure with an only 100-nm-thick GaN spacer layer homoepitaxially grown on the GaN template. This technique was also demonstrated viable for native GaN substrates to stabilize the surface facilitating two-dimensional growth of GaN layers. Very high residual silicon and oxygen concentrations were found up to ∼1 × 1020 cm−3 at the interface between the GaN epilayer and the native GaN substrate. Capacitance-voltage measurements confirmed that the residual carbon doping controlled by growth conditions of the GaN epilayer can be used to successfully compensate the donor-like impurities. State-of-the-art structural properties of a high-mobility AlGaN/AlN/GaN heterostructure was then realized on a 1 × 1 cm2 SI native GaN substrate; the full width at half maximum of the X-ray rocking curves of the GaN (002) and (102) peaks are only 21 and 14 arc sec, respectively. The surface morphology of the heterostructure shows uniform parallel bilayer steps, and no morphological defects were noticeable over the entire epi-wafer.

DEVELOPMENT OF A SAMPLE PREPARATION METHOD FOR RAW MATERIAL EVALUATION OF SCHOOL SUPPLIES

The aim of this study was to evaluate the extraction of elements Ba, Cd, Cr, Hg and Pb in solid samples, using a microwave oven with closed flasks and to understand the physicochemical parameters involved in this process. The conducting of this study was based on directive 2009/48/CE, which specifies the levels of elements in the materials used by children. A total of eight samples were used to evaluate the extraction process. A full factorial design 23 was performed and principal component analysis (PCA) was used to select only critical samples (simultaneously high residual solid content and metal concentrations) for the proposed process, reducing the number of samples tested. A second full factorial design 23 was performed with selected samples (masterbatch, polymer and kaolin) and the following variables investigated: addition of H2O2, addition of analytes, and HNO3 volume. The responses observed for this factorial design were recoveries of the analytes (Ba, Cd, Cr, Hg, and Pb) and a desirability function was used in order to combine all responses. The conclusions were that it is not possible to digest some samples with different physicochemical characteristics (masterbatch and polymer, for example) in the same batch and that the proposed system can be used to perform sample screening.

Residue Dynamics and Safe Pre-Harvest Interval of Chlorpyrifos in Water Dropwort

Chlorpyrifos residue contents in market water dropwort, residue dynamics of chlorpyrifos and the safe pre-harvest interval (SPHI) in field water dropwort were conducted in Changzhou, Jiangsu Province, China. The results showed that concentrations of chlorpyrifos residues in more than half of the market samples (57%) exceeded the maximum allowable concentration (MAC, 0.05 mg kg-1), according to the Chinese Standard (GB 2763 – 2014). The average chlorpyrifos content in the samples was 0.23 mg kg-1 that was 3.6 times higher than the MAC. Study on the residue dynamics of chlorpyrifos demonstrated that the half-life of chlorpyrifos residues in the water dropwort of early-sowing (in summer) and late-sowing (in autumn) were 4.1 and 5.4 days, respectively, and it took 31.2 and 43.1 days, respectively, for chlorpyrifos residues to decrease to the MAC level. In normal application dosage (recommended for vegetables), the SPHI was 30-35 days for the water dropwort of early-sowing, and 40 days for the water dropwort of late-sowing, which were much longer than the recommended pre-harvest interval (seven days) according to the Chinese Standard ((GB/T 8321 – 2000)). It may be the cause of high chlorpyrifos residue concentrations in market water dropwort.

Fatigue Strength Improvement of Aluminum and High Strength Steel Welded Structures using High Frequency Mechanical Impact Treatment

Most structures and components are fabricated using welded joints. A very high percentage of all fatigue failures locally occur at welded locations due to high tensile residual stresses and stress concentrations resulting from the weld process. High frequency mechanical impact (HFMI) treatment has been increasingly used as an effective post-weld treatment technique to improve fatigue strength of welded structures. Fatigue tests have been conducted for as-welded and HFMI treated 5083-H321 grade aluminum and ASTM A514 steel welded specimens to investigate the effects of the HFMI treatment under constant amplitude R= 0.1 and variable amplitude loading. This paper presents fatigue test results including local properties (residual stresses) of welded specimens under the as-welded and the HFMI treated conditions. Test results showed that the HFMI treatment significantly improved fatigue life performance of the aluminum and steel welded specimens under both constant and variable amplitude load conditions. Therefore, the HFMI treatment is a quite promising post-weld treatment technique and its potential applications on the fatigue design of welded structures and components can lead to lighter structures and products, in which components and structures can be down-sized and optimized to reduce weights.

Accumulation and Degradation of Thiabendazole Residues in Eggs in Administered Layer Hens

Administration of thiabendazole (TBZ) to laying hens may cause accumulation of the drug residues in eggs. Twenty five week old hens (n=6) were administered with a single oral dose of 75 mg TBZ/day/layer hen for 5 consecutive days and its residues in eggs were quantified by HPLC-FD. The highest TBZ (0.4308±0.0253 ppm), below maximum residue limit (0.0886±0.0161 ppm) and below limit of detection (LOD) residue concentrations in eggs were observed on mean time of 127.54, 177.62 and 252.58 h after first feeding, respectively. The highest TBZ concentration (0.5260 ppm) and total residue on any day from 2 to 9 day in the entire egg white portion were significantly (P&lt;0.01) higher than those in the yolk. The highest residue concentrations as well as the highest total residue in egg albumin (0.5944 ppm), yolk (0.6587 ppm) and whole egg (0.5867 ppm) were quantified. The highest TBZ concentration (0.5260 ppm) as well as total TBZ residue on any day from day 2 to day 9 in the entire white portion of egg were significantly (P&lt;0.01) higher than those in the yolk . Egg white, yolk and whole egg from the TBZ fed hens had residues at 50.71 to 153.50, 75.62 to 153.50 and 50.71 to 153.50 h after first feeding, respectively. The highest concentration TBZ residue in whole egg is 0.4308±0.0253 ppm and cumulative residue is 8.1886±6.5385 ppm and also calculated in microgram is useful to show as per the standard values. The work indicated that safe dose and days to consume egg. Safe time/days can be reduced for consuming eggs after administration of thiabendazole by using different types of decontamination techniques.Keywords: Thiabendazole Residues Yolk Albumin Hen’s egg

Effect of oxygen on the microstructure and hydrogen storage properties of V–Ti–Cr–Fe quaternary solid solutions

The effect of low (<300 ppm O) and high (10,000 ppm O) residual oxygen concentration in vanadium raw metals on the microstructure and hydrogenation properties of V40Fe8Ti26Cr26, was investigated by means of XRD, SEM, TEM and pressure-composition isotherms. A high oxygen concentration in the vanadium raw metal led to the formation of an oxygen-rich secondary phase isostructural with α-Ti. The lattice parameter of the BCC main phase of the high-oxygen sample was reduced to 3.0141 (3) Å compared to 3.0308 (2) Å for the low-oxygen sample. As a result of the high oxygen content the equilibrium hydrogen pressure of the material was increased from 1 MPa to 4 MPa. Deoxidization through the addition of 1 at% rare earth metal could be achieved. The lattice constant of the deoxidized sample was 3.0297 (3) Å, and the thermodynamic properties were also the same as in case of the low-oxygen sample.

Survival strategies of polyphosphate accumulating organisms and glycogen accumulating organisms under conditions of low organic loading

Enhanced biological phosphorus removal (EBPR) is usually limited by organic carbon availability in wastewater treatment plants (WWTPs). Polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) were operated under extended periods with low organic carbon loading in order to examine its impact on their activity and survival. The decrease in organic carbon load affected PAOs and GAOs in different ways, where the biomass decay rate of GAOs was approximately 4times higher than PAOs. PAOs tended to conserve a relatively high residual concentration of polyhydroxyalkanoates (PHAs) under aerobic conditions, while GAOs tended to deplete their available PHA more rapidly. This slower oxidation rate of PHA by PAOs at residual concentration levels enabled them to maintain an energy source for aerobic maintenance processes for longer than GAOs. This may provide PAOs with an advantage over GAOs in surviving the low organic loading conditions commonly found in full-scale wastewater treatment plants.

QUANTIFICATION OF RESIDUAL CLOVE OIL, BENZOCAINE AND TRICAINE IN FISH FILLETS USING SPE AND UPLC-DAD

Residual quantification of the anesthetics clove oil (CO) – isoeugenol (ISO), eugenol (EUG) and methyleugenol (MET) –,benzocaine (BZN) and tricaine (MS-222) was made in fillets of two fish species: Nile tilapia (Oreochromis niloticus) and acatfish hybrid, cachadia (Pseudoplatystoma reticulatum x Leiarius marmoratus). Samples (n=4) of each fish wereevaluated after submitted to anesthesia in five dosages defined based on the induction time of each species afterdepuration times (0h, 12h, 24h and 48h). Different methodologies of sample preparation were tested and selectedaccording to the better recovery. The quantification of anesthetics was performed by UPLC-DAD. The variance of residualmeans among anesthetics, dosages and fish species was compared. After anesthesia (0h) both species, tilapia andcachadia, presented residual anesthetics. Fishes depurated during 12h, 24h and 48h did not present detectable values, itmeans, values were below the limits of detection. BZN presented the highest mean residual concentration for tilapia andcachadia (p=0.01), while MS-222 presented the lowest residual amounts in tilapias and EUG in cachadias, what may berelated to the metabolism and carcass composition of each fish species. There were no significant differences among thefive dosages, except the lowest MS-222 concentration in tilapias that resulted in higher residual concentrations becauselow dosages increase the induction time and consequently the permanence of the fish in anesthesia. Ultimately, meanvalues of residues in cachadia were higher than in tilapia, and MS-222 and EUG presented the lowest residual values fortilapia and cachadia, respectively.

Spatial and temporal exposure patterns in non-target small mammals during brodifacoum rat control

Worldwide pest rodents on livestock farms are often regulated using anticoagulant rodenticides (ARs). Second generation ARs in particular can cause poisoning in non-target species due to their high toxicity and persistence. However, research on exposure of small mammals is rare. We systematically investigated spatial and temporal exposure patterns of non-target small mammals in a large-scale replicated study. Small mammals were trapped at different distances to bait stations on ten farms before, during and after brodifacoum (BR) bait application, and liver samples of 1178 non-target small mammals were analyzed for residues of eight ARs using liquid chromatography coupled with tandem mass spectrometry. BR residues were present in 23% out of 742 samples collected during and after baiting. We found clear spatial and temporal exposure patterns. High BR residue concentrations mainly occurred within 15m from bait stations. Occurrence and concentrations of residues significantly decreased with increasing distance. This pattern was found in almost all investigated taxa. After baiting, significantly more individuals contained residues than during baiting but concentrations were considerably lower. Residue occurrence and concentrations differed significantly among taxa, with the highest maximal residue concentrations in Apodemus species, which are protected in Germany. Although Sorex species are known to be insectivorous we regularly found residues in this genus. Residues of active agents other than brodifacoum were rare in all samples. The confirmation of substantial primary exposure in non-target small mammals close to the baiting area indicates considerable risk of secondary poisoning of predators, a pathway that was possibly underestimated until now. Our results will help to develop risk mitigation strategies to reduce risk for non-target small mammals, as well as their predators, in relation to biocidal AR usage.

Residual Stresses in Ultrasonically Peened Fillet Welded Joints

Fatigue cracks mostly initiate at areas subjected to high tensile residual stress and stress concentration. Ultrasonic peening is a mechanical method to increase fatigue life by imparting compressive residual stress. In this study residual stresses are characterized in fillet welded ship structural steel plates with longitudinal attachments. As-welded, ultrasonically peened, and specimens peened then subjected to accelerated corrosion testing were measured. Residual stress characterization was performed by the contour method and neutron diffraction.

Isolation of a novel, crystalline cellulose material from the spent liquor of cellulose nanocrystals (CNCs)

We have modified the standard sulphuric acid hydrolysis method for the production of cellulose nanocrystals (CNCs) to successfully isolate a novel, highly crystalline cellulose material from the spent liquor of CNCs. The novel material has a cellulose II crystal structure that is distinctly different from the cellulose I crystal structure of CNCs. The modified method uses a shorter time for the hydrolysis, followed by maintaining a high residual acid concentration for the separation of the spent liquor and CNCs, and by adding the spent liquor to water. The modified method offers an opportunity to concurrently produce CNCs in up to ~40 % yield and the novel, highly crystalline, sulphated cellulose II in ~15 % yield in separate and pure forms from sulphuric acid hydrolysis of a commercial northern bleached softwood kraft pulp. It can potentially reduce the production cost of CNCs, allow easier downstream processing of CNCs and recovery of sulphuric acid, and generate a new cellulose bio-material for product development.

Transcriptomic, biochemical and individual markers in transplanted Daphnia magna to characterize impacts in the field

Daphnia magna individuals were transplanted across 12 sites from three Spanish river basins (Llobregat, Ebro, Jucar) showing different sources of pollution. Gene transcription, feeding and biochemical responses in the field were assessed and compared with those obtained in re-constituted water treatments spiked with organic eluates obtained from water samples collected at the same locations and sampling periods. Up to 166 trace contaminants were detected in water and classified by their mode of action into 45 groups that included metals, pharmaceuticals, pesticides, illicit drugs, and other industrial compounds. Physicochemical water parameters differentiated the three river basins with Llobregat having the highest levels of conductivity, metals and pharmaceuticals, followed by Ebro, whereas the Jucar river had the greatest levels of illicit drugs. D. magna grazing rates and cholinesterase activity responded similarly than the diversity of riparian benthic communities. Transcription patterns of 13 different genes encoding for general stress, metabolism and energy processes, molting and xenobiotic transporters corroborate phenotypic responses differentiated sites within and across river basins. Principal Component Analysis and Partial Least Square Projections to Latent Structures regression analyses indicated that measured in situ responses of most genes and biomarkers and that of benthic macroinvertebrate diversity indexes were affected by distinct environmental factors. Conductivity, suspended solids and fungicides were negatively related with the diversity of macroinvertebrates cholinesterase, and feeding responses. Gene transcripts of heat shock protein and metallothionein were positively related with 11 classes of organic contaminants and 6 metals. Gene transcripts related with signaling paths of molting and reproduction, sugar, protein and xenobiotic metabolism responded similarly in field and lab exposures and were related with high residue concentrations of analgesics, diuretics, psychiatric drugs, β blockers, illicit drugs, trizoles, bisphenol A, caffeine and pesticides. These results indicate that application of omic technologies in the field is a promising subject in water management.

Closantel plasma and milk disposition in dairy goats: assessment of drug residues in cheese and ricotta.

Closantel (CLS) is currently used in programs for the strategic control of gastrointestinal nematodes. CLS is extralabel used in different dairy goat production systems. From available data in dairy cows, it can be concluded that residues of CLS persist in milk. The current work evaluated the concentration profiles of CLS in plasma and milk from lactating orally treated dairy goats to assess the residues pattern in dairy products such as cheese and ricotta. Six (6) female Saanen dairy goats were treated orally with CLS administered at 10mg/kg. Blood and milk samples were collected between 0 and 36days post-treatment. The whole milk production was collected at 1, 4, 7, and 10days post-treatment to produce soft cheese and ricotta. CLS concentrations in plasma, milk, cheese, whey, and ricotta were determined by HPLC. The concentrations of CLS measured in plasma were higher than those measured in milk at all sampling times. However, the calculated withdrawal time for CLS in milk was between 39 and 43days postadministration to dairy goats. CLS residual concentrations in cheese (between 0.93 and 1.8μg/g) were higher than those measured in the milk used for its production. CLS concentrations in ricotta were sixfold higher than those in the milk and 20-fold higher than those in the whey used for its production. The persistent and high residual concentrations of CLS in the milk and in the cheese and ricotta should be seriously considered before issuing any recommendation on the extralabel use of CLS in dairy goat farms.

Dissipation and persistence of major herbicides applied in transgenic and non-transgenic canola production in Quebec

After soybeans, canola is the second most important oilseed crop in Canada, with more than 99% of the canola cultivation consisting of herbicide resistant (HR) varieties. The expansion in HR canola cultivation has led to the increasing use of the same herbicides for weed control which has resulted in a growing concern about their impact on the environment. The present study was conducted to investigate the dissipation and transport of the herbicides, glyphosate and glufosinate, in soil used for the transgenic production of canola and a comparison was made with the herbicide, trifluralin, used in non-transgenic canola. Commercially grown HR transgenic canola varieties and a conventional canola variety were planted in a randomized complete block design. The plots planted with Roundup Ready and Liberty Link cultivars were treated with glyphosate and glufosinate, respectively, at the 2–3 leaf stage and at the rosette stage in each replication. On conventional canola plots, trifluralin was incorporated into soil a day before planting. Soil samples were collected from two depths, 0–0.15 m and 0.15–0.30 m, at different time intervals (1, 7 and 20 days) after the application of the herbicide. Analysis of the soil samples was done by HPLC (high performance liquid chromatography) to determine the residual amounts of herbicide in the soil. Glufosinate was found to be the least persistent herbicide, while trifluralin persisted the longest. The overall order of persistence was Trifluralin > Glyphosate > Glufosinate. Trifluralin was found at lower depths (0.15–0.30 cm) at 7 and 20 days after the herbicide application, with higher residual concentrations than the other herbicides used in the HR canola.