Low Residual Concentration Research Articles

Determination of Hormonal Growth Promotants in Beef Using Liquid Chromatography-Tandem Mass Spectrometry.

Hormonal growth promotants (HGPs) are a class of pharmaceutical agents commonly administered to cattle in the United States to improve growth rates of the animal, alter behavior, or to improve the desired characteristics of retail cuts of meat. There is a concern that low residual concentrations of HGPs may remain in tissue after slaughter, and consumption of tissues containing these compounds may increase the risk of adverse health outcomes, including cancer. Sensitive and selective methods are necessary to assess exposure of HGPs by populations that consume meat products from animals that may have been administered HGPs. A liquid chromatography-tandem mass spectrometry method was developed and validated to detect the low-level presence of HGPs including estradiol, testosterone, estradiol benzoate, melengestrol, melengestrol acetate, progesterone, testosterone propionate, trenbolone, trenbolone acetate, and α-zearalanol in retail cuts of meat following a liquid-liquid extraction using a high pH solution with 30-50× less mass of meat required as compared to similar approaches. Good chromatographic performance and sensitivity was achieved utilizing ammonium fluoride as a mobile phase additive without the need for derivatization. Validation parameters including accuracy, precision, recovery, matrix effects, limits of detection, limits of quantitation, linear range, and stability were determined. The limits of detection ranged from 0.1 to 1.0 ng/g, depending on the compound, with adequate accuracy and precision without the need for extensive sample preparation approaches.

Accelerated Lanthanide Intercalation into Graphite Catalyzed by Na.

Lanthanides (Ln) are notoriously difficult to intercalate into graphite. We investigated the possibility of using Na to catalyze the formation of Ln-intercalated graphite and successfully synthesized LnC6 (Ln = Sm, Eu, and Yb) significantly rapidly in high yields. The synthesis process involves the formation of the reaction intermediate NaCx, through the mixing of Na and C, which subsequently reacts with Ln upon heating to form LnC6. Well-sintered LnC6 pellets with low residual Na concentrations (Ln:Na ≈ 98:2) were fabricated by the two-step method. The pellets enabled the evaluation of LnC6 by powder X-ray diffraction and electrical resistivity measurements. This study highlights the versatility of the Na-catalyzed method and lays the foundation for the rapid mass production of LnC6, with potential applications in superconducting and rechargeable battery materials.

Long-term herbicide residues affect soil multifunctionality and the soil microbial community

Residues of herbicides with the extensive applications may impact the soil ecosystem and ultimately threaten agricultural sustainability. However, the effects of long-term herbicide residues on soil multifunctionality and the soil microbial community remain poorly understood. Here, we evaluated relationships between soil multifunctionality and soil microbial communities with residual herbicide concentrations by surveying and analyzing 62 black soil samples collected from an agricultural area in northeastern China. Total residual herbicide concentrations varied from 35 to 568 μg/kg in the soil samples. The response of soil multifunctionality to increasing residual herbicide concentrations exhibited an inverted U-shaped relationship with a peak at approximately 310 μg/kg, with net mineralized organic nitrogen (Nm) and total nitrogen (TN) exhibiting the same trend. Microbial community richness was significantly lower in soil samples with high residual herbicide concentrations (> 310 μg/kg, HG) compared to low residual herbicide concentrations (< 310 μg/kg, LG). In addition, the relative abundances of specific keystone microbial genera differed significantly between LG and HG: norank_f_Acetobacteraceae, norank_f_Caldilineaceae, Candidatus_Alysiosphaera, and Gonytrichum. The relative abundances of these genera were also significantly correlated with soil multifunctionality. Structural equation models (SEMs) further showed that herbicide residues influenced soil multifunctionality by affecting these specific keystone genera. Our study demonstrates that long-term herbicide residues significantly impact the multifunctionality of agricultural black soil, where low concentrations stimulate while high concentrations inhibit, underscoring the need for reasonable application of herbicides to maintain soil ecosystem health.

Comparative Assessment of Thermal Treatment for Mycotoxins Adsorption Potential of Indigenous Clay from Balochistan, Pakistan

The current study aimed to investigate the physical characteristics and mycotoxins (Aflatoxins B1 (AFB1) and Ochratoxin A (OTA) binding efficacy of indigenous clays before and after thermal treatment (calcination). The clay sample was collected from various mountainous areas of Balochistan, Pakistan. The samples were ground into a 360 mesh size and thermally treated initially at 200 °C and thereafter at 800 °C for 30 minutes with the help of a muffle furnace. XRD analysis revealed montmorillonite as the most commonly occurring group of clay minerals. The thermally treated clays showed that the binding potential was significantly (P &lt;0.05) improved against mycotoxins. Enzyme-linked immunoassay (ELISA) determination showed significantly (P &lt;0.05) lower residual concentrations of mycotoxins in thermally treated clays. The mycotoxin adsorption capacity (%) was found to be higher in the clay samples procured from Pishin (79.17% for AFB1 and 67.34% for OTA) and Bolan (62.0% for AFB1 and 50.17% for OTA). Calcination also caused a significant decrease in Cation Exchange Capacity (CEC) in some clay samples. Overall, the findings of the study showed that thermal treatment enhanced the in vitro binding capacity of clays against the studied mycotoxins. An increase in the mycotoxin binding capacity of the clays not only reduces the bioavailability of mycotoxins but also decreases their toxic effects. It is recommended that Balochistan clay have the potential to be used as an adsorbent for the removal of mycotoxins from the environment and animal feeds.

Post-sorption of Cd, Pb, and Zn onto peat, compost, and biochar: Short-term effects of ecotoxicity and bioaccessibility

Contamination by potentially toxic metals and metalloids (PTMs) has become a significant health and environmental issue worldwide. Sorption has emerged as one of the most prominent strategies for remediating both soil and water contamination. New sorbents are being developed to provide economically viable and environmentally sound alternatives, in alignment with the principles of the Sustainable Development Goals. This research aimed to assess the potential effects on human health and environmental toxicity following the sorption of cadmium (Cd), lead (Pb), and zinc (Zn) using peat, compost, and biochar as sorbents. The peat was collected in Brazil, a country with a tropical climate, while the compost and biochar were produced from the organic fraction of municipal solid waste (OFMSW). In terms of bioaccessibility, the results showed the following order: compost < biochar < peat for Pb, and compost < peat < biochar for Cd and Zn. There was a significant growth inhibition for Eruca sativa and Zea mays exposed to increasing concentrations of PTMs treated with peat and compost. The presence of contaminants played a decisive role on immobilization of neonates of Ceriodaphnia silvestrii after treatments with compost and, especially, peat. However, the biochar addition rate caused a significant influence on the outcomes of ecotoxicity across all tested species. Although the samples treated with biochar exhibited lower residual concentrations of PTMs than those treated with compost and peat, the inherent toxicity of biochar might be attributed to the material itself. The exposure to residual PTM concentrations post-desorption caused ecotoxic effects on tested species, emphasizing the need to assess PTM desorption potential. Peat, compost, and biochar are promising alternatives for the sorption of PTMs, but the addition rates must be properly adjusted to avoid the occurrence of undesirable ecotoxicological effects. This research offers valuable insights for sustainable environmental management and protection by thoroughly investigating the impacts of different sorbents and contaminants on aquatic and terrestrial ecosystems.

Evaluating antibiotic occurrence, degradation, and environmental risks in poultry litter within Argentina's agricultural hub

This study explores the relationship between poultry farming's antibiotic administration practices and residual antibiotic levels in the litter before its application onto agricultural soils. Twenty-three antibiotics were performed across 19 Argentinean farms representing diverse antibiotic management practices. Analysis revealed up to 20 antibiotics from eight chemical classes in poultry litter samples, with tylosin, enrofloxacin, and salinomycin being the most relevant drugs. Farms with restricted antibiotic use in feed exhibited lower residual concentrations. A self-heating treatment was tested to reduce litter antibiotic levels. Although a 60 % reduction of antibiotics was found after treatment, prevalent compounds persisted at residual levels. Regulatory measures and comprehensive litter treatments pre-application are crucial to mitigate environmental risks. This is the first study that provides insight on the occurrence of >20 drugs in real poultry production scenarios from Latin America and demonstrates how relatively simple treatments can be readily applied to decrease the associated environmental risks.

Laccase-mediated degradation of petroleum hydrocarbons in historically contaminated soil

Laccases (EC1.10.3.2) have attracted growing attention in bioremediation research due to their high reactivity and substrate versatility. In this study, three genes for potential novel laccases were identified in an enrichment culture from contaminated field soil and recombinantly expressed in E. coli. Two of them, designated as PlL and BaL, were biochemically characterized regarding their optimal pH and temperature, kinetic parameters, and substrate versatility. In addition, lacasse PlL from Parvibaculum lavamentivorans was tested on historically contaminated soil. Treatment with PlL led to a significantly higher reduction of total petroleum hydrocarbons (83% w/w) compared to the microbial control (74% w/w). Hereby, PlL was especially effective in degrading hydrocarbons > C17. Their residual concentration was by 43% w/w lower than in the microbial treatment. In comparison to the laccase from Myceliophthora thermophila (MtL), PlL treatment was not significantly different for the fraction > C17 but resulted in a 30% (w/w) lower residual concentration for hydrocarbons < C18. In general, PlL can promote the degradation of petroleum hydrocarbons. As a consequence, it can be applied to reduce remediation time by duly achieving remediation target concentrations needed for site closure.

Assessing potential soil pollution from plant waste disposal: A modeling analysis of pesticide contamination

Pesticide residues can be taken up by plants after pesticide application, potentially resulting in soil pollution following the disposal of plant wastes at harvest. Currently, there is a lack of simple and efficient methods that can conduct high-throughput simulations to explore this problem across various chemicals and plant species. We present a modeling approach to simulating pesticide residue concentrations in soil as a result of plant waste disposal to assess the impact of plant wastes on agricultural soil pollution with respect to pesticide residues. This modeling approach employs well-established plant uptake models, providing versatility in evaluating different chemicals and plant species. The simulation process was tabulated in the spreadsheet interface, providing users with the flexibility to adjust input values for specific chemicals, plant species, and regions. The simulation results revealed that pesticides with relatively low lipophilicity (i.e., log KOW < 2) had low simulated residue concentrations in the soil as a result of plant waste disposal at harvest, whereas soil concentrations for lipophilic pesticides dramatically rose. This indicated that disposal of plant waste in agricultural soils will not pose significant ecological concerns to pesticides with low lipophilicity. The variability analysis showed that for certain pesticides, environmental factors (such as temperature and humidity) had a significant impact on the simulated residue concentrations in the soil as a result of plant waste disposal, which aided in the assessment of regional ecological risk as well as plant disposal management. Although some modeling aspects such as plant decomposition process, advanced plant uptake models, heterological distribution of residue concentrations in the soil, and plant waste stacking patterns require further research, the proposed approach can be used to assist in managing soil pesticides from plant waste disposal in preliminary stages.

Efficacy of Peracetic Acid and Chlorine on the Reduction of Shiga Toxin-producing Escherichia coli and a Nonpathogenic E. coli Strain in Preharvest Agricultural Water

Produce-borne outbreaks of Shiga toxin-producing Escherichia coli (STEC) linked to preharvest water emphasize the need for efficacious water treatment options. This study quantified reductions of STEC and generic E. coli in preharvest agricultural water using commercially available sanitizers. Water was collected from two sources in Virginia (pond, river) and inoculated with either a seven-strain STEC panel or environmental generic E. coli strain TVS 353 (∼9 log10 CFU/100 mL). Triplicate inoculated water samples were equilibrated to 12 or 32°C and treated with peracetic acid (PAA) or chlorine (Cl) [low (PAA:6ppm, Cl:2–4 ppm) or high (PAA:10 ppm, Cl:10–12 ppm) residual concentrations] for an allotted contact time (1, 5, or 10 min). Strains were enumerated, and a log-linear model was used to characterize how treatment combinations influenced reductions. All Cl treatment combinations achieved a ≥3 log10 CFU/100 mL reduction, regardless of strain (3.43 ± 0.25 to 7.05 ± 0.00 log10 CFU/100 mL). Approximately 80% (19/24) and 67% (16/24) of PAA treatment combinations achieved a ≥3 log10 CFU/100 mL for STEC and E. coli TVS 353, respectively. The log-linear model showed contact time (10 > 5 > 1 min) and sanitizer type (Cl > PAA) had the greatest impact on STEC and E. coli TVS 353 reductions (p < 0.001). E. coli TVS 353 in water samples was more resistant to sanitizer treatment (p < 0.001) indicating applicability as a good surrogate. Results demonstrated Cl and PAA can be effective agricultural water treatment strategies when sanitizer chemistry is managed. These data will assist with the development of in-field validation studies and may identify suitable candidates for the registration of antimicrobial pesticide products for use against foodborne pathogens in preharvest agricultural water treatment.

Milk residues following multiple doses of meloxicam and gabapentin in lactating dairy cattle.

To determine the influence of stage of lactation on the pharmacokinetics in milk when multiple doses of meloxicam were administered alone or in combination with gabapentin to postpartum (PP) and mid-lactation (ML) cows. 8 postpartum and 8 mid-lactation dairy cows. Cows were randomly divided into 2 groups (n = 8) which included 4 PP cows and 4 ML cows. Group I received only 6 oral daily doses of meloxicam (1.0 mg/kg for 6 doses). Group II received 6 oral daily doses of co-administered meloxicam (1.0 mg/kg) and gabapentin (20 mg/kg) for 6 doses. Meloxicam and gabapentin were quantified in plasma and milk samples by ultra-high-performance liquid chromatography-tandem mass spectrometry, and the pharmacokinetic analysis of milk and plasma was performed using a non-compartmental approach. Regardless of lactation status, dairy cattle administered multiple doses of meloxicam and/or gabapentin showed low drug residue concentrations and little accumulation in milk. The terminal plasma half-life of meloxicam was significantly increased (P < .02) in PP cows (12.9 hr) compared to ML cows (9.4 hr). The apparent terminal half-life in milk for meloxicam and gabapentin was not affected by stage of lactation. Co-administration of gabapentin did not alter plasma or milk concentrations of meloxicam. The results of this study suggest that milk from cows treated with multiple doses of meloxicam alone or in combination with gabapentin will have low drug concentrations and falls below our reported limit of detection for meloxicam or gabapentin 120 and 60 hours respectively, following the final dose regardless of their stage of lactation.

Kinetics and mechanism for efficient Co(II) removal from zinc sulfate solution by ultrasonic-enhanced zinc powder replacement

The purification of zinc sulfate electrolytes in zinc hydrometallurgy has always been a vexing problem. The aggregation of zinc powder and the removal of recalcitrant Co(II) are the most challenging. Here, we propose a new method for removing Co(II) from a zinc sulfate solution using ultrasonic-enhanced zinc powder replacement. The parameters affecting Co(II) removal are investigated to obtain the optimum conditions. The Co(II) removal efficiency increases remarkably by 26.6% and the required amount of zinc powder was correspondingly reduced by 50% after introducing ultrasound and activators. The optimal dosage of activators Sb2O3 and Cu(II) is CCu(II): CSb(III): CCo(II) = 2: 1: 1. Moreover, the addition of Cu(II) does not deteriorate the quality of zinc sulfate solution because of its low residual concentration (0.84 mg/L). The removal kinetics show that the activation energy of Co-precipitation decreases by 32.27 kJ/mol, and the conversion range of the kinetic mechanism is increased to CCo(II),0 = 60–80 mg/L. The particle diameter of the purified slags decreases from 136.22 to 19.81 µm compared with that of conventional experiments. The cobalt removal mechanism mainly involves that ultrasound promotes the dispersion of zinc powder, opens the package and reduces the activation energy; the Co-Sb-Cu alloys reduce the Co-precipitation overpotential and inhibit the redissolution of Co. The proposed method presents a promising solution to the challenging problem of Co(II) removal. This study opens new possibilities for the application of ultrasound in the metallurgical fields for more efficient and energy-saving production.

Spatial Distribution and Migration Characteristic of Forchlorfenuron in Oriental Melon Fruit by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

Forchlorfenuron is a widely used plant growth regulator to support the pollination and fruit set of oriental melons. It is critical to investigate the spatial distribution and migration characteristics of forchlorfenuron among fruit tissues to understand its metabolism and toxic effects on plants. However, the application of imaging mass spectrometry in pesticides remains challenging due to the usually extremely low residual concentration and the strong interference from plant tissues. In this study, a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) method was developed for the first time to obtain the dynamic images of forchlorfenuron in oriental melon. A quantitative assessment has also been performed for MALDI-MSI to characterize the time-dependent permeation and degradation sites of forchlorfenuron in oriental melon. The majority of forchlorfenuron was detected in the exocarp and mesocarp regions of oriental melon and decreased within two days after application. The degradation rate obtained by MALDI-MSI in this study was comparable to that obtained by HPLC-MS/MS, indicating that the methodology and quantification approach based on the MALDI-MSI was reliable and practicable for pesticide degradation study. These results provide an important scientific basis for the assessment of the potential risks and effects of forchlorfenuron on oriental melons.

Importance of residual insulin secretion in type 1 diabetes

Finland has the highest incidence of type 1 diabetes in the world, which has led to many important studies of type 1 diabetes in the Finnish population and to the formation of several study groups. In The Lancet Diabetes & Endocrinology, Minna Harsunen and colleagues 1 Harsunen M Haukka J Harjutsalo V et al. Residual insulin secretion in individuals with type 1 diabetes in Finland: longitudinal and cross-sectional analyses. Lancet Diabetes Endocrinol. 2023; (published online June 5.)https://doi.org/10.1016/S2213-8587(23)00123-7 Google Scholar present longitudinal and cross-sectional analyses of random C-peptide (an index of insulin secretion and β-cell function) measurements in three Finnish cohorts: 957 newly diagnosed patients seen at Helsinki University Hospital, in collaboration with the Finnish Pediatric Diabetes Registry (FPDR), for the longitudinal analysis; and 3984 study participants from the FinnDiane study group and 645 from the DIREVA regional diabetes registry in western Finland for the cross-sectional analysis. Data from these studies were used to examine which parameters were associated with residual insulin secretion. Residual insulin secretion in individuals with type 1 diabetes in Finland: longitudinal and cross-sectional analysesAlthough children with multiple autoantibodies and HLA risk genotypes progressed to absolute insulin deficiency rapidly, many adolescents and adults had residual random serum C-peptide decades after the diagnosis. Polygenic risk of type 1 and type 2 diabetes affected residual random serum C-peptide. Even low residual random serum C-peptide concentrations seemed to be associated with a beneficial complications profile. Full-Text PDF

Residual insulin secretion in individuals with type 1 diabetes in Finland: longitudinal and cross-sectional analyses

Contrary to the presumption that type 1 diabetes leads to an absolute insulin deficiency, many individuals with type 1 diabetes have circulating C-peptide years after the diagnosis. We studied factors affecting random serum C-peptide concentration in individuals with type 1 diabetes and the association with diabetic complications. Our longitudinal analysis included individuals newly diagnosed with type 1 diabetes from Helsinki University Hospital (Helsinki, Finland) with repeated random serum C-peptide and concomitant glucose measurements from within 3 months of diagnosis and at least once later. The long-term cross-sectional analysis included data from participants from 57 centres in Finland who had type 1 diabetes diagnosed after 5 years of age, initiation of insulin treatment within 1 year from diagnosis, and a C-peptide concentration of less than 1·0 nmol/L (FinnDiane study) and patients with type 1 diabetes from the DIREVA study. We tested the association of random serum C-peptide concentrations and polygenic risk scores with one-way ANOVA, and association of random serum C-peptide concentrations, polygenic risk scores, and clinical factors with logistic regression. The longitudinal analysis included 847 participants younger than 16 years and 110 aged 16 years or older. In the longitudinal analysis, age at diagnosis strongly correlated with the decline in C-peptide secretion. The cross-sectional analysis included 3984 participants from FinnDiane and 645 from DIREVA. In the cross-sectional analysis, at a median duration of 21·6 years (IQR 12·5-31·2), 776 (19·4%) of 3984 FinnDiane participants had residual random serum C-peptide secretion (>0·02 nmol/L), which was associated with lower type 1 diabetes polygenic risk compared with participants without random serum C-peptide (p<0·0001). Random serum C-peptide was inversely associated with hypertension, HbA1c, and cholesterol, but also independently with microvascular complications (adjusted OR 0·61 [95% CI 0·38-0·96], p=0·033, for nephropathy; 0·55 [0·34-0·89], p=0·014, for retinopathy). Although children with multiple autoantibodies and HLA risk genotypes progressed to absolute insulin deficiency rapidly, many adolescents and adults had residual random serum C-peptide decades after the diagnosis. Polygenic risk of type 1 and type 2 diabetes affected residual random serum C-peptide. Even low residual random serum C-peptide concentrations seemed to be associated with a beneficial complications profile. Folkhälsan Research Foundation; Academy of Finland; University of Helsinki and Helsinki University Hospital; Medical Society of Finland; the Sigrid Juselius Foundation; the "Liv and Hälsa" Society; Novo Nordisk Foundation; and State Research Funding via the Helsinki University Hospital, the Vasa Hospital District, Turku University Hospital, Vasa Central Hospital, Jakobstadsnejdens Heart Foundation, and the Medical Foundation of Vaasa.

Preharvest Treatments with Low-Risk Plant Protection Products Can Help Apple Growers Fulfill the Demands of Supermarket Chains Regarding Pesticide Residues and Marketing Apples under 0-Residue Brands

As a result of worried consumer pressure, European supermarket chains (ESC) have developed very strict rules about the number and concentration of pesticide active substance residues (AS) accepted in fruits. So-called fruit quality toxicological burden indicators were developed. If fruit suppliers do not comply with ESC requirements, their fruit is often rejected. It is becoming increasingly difficult for apple producers to meet all the requirements of the ESC, so they need new residue reduction tools. One of the options to lower the concentrations of residue on apples is a preharvest application of low-risk preparations (LRP) based on potassium bicarbonate (KHCO3) = PBC, coconut di-ethanol amide ((CH3(CH2)nC(=O)N(CH2CH2OH)2) = DEA, hydrogen peroxide (H2O2) = HP, and a mixture of microbes (EM) that have the ability to dissolve or disintegrate the AS residue. Trials were carried out to test the concept mentioned above. The application of LRP during the last four weeks of preharvest significantly reduced the residue concentration of pesticide AS in apples. Reduction rates among 25 active substances ranged from 0 to 100%, depending on the combination of LRP and AS. HP had the highest capacity to accelerate AS degradation, PB was the second most efficient, and DEA and EM displayed a low residue disintegration ability. The application of the tested LRP can enable apple growers to produce fruits with significantly lower residue concentrations and allows them to comply more successfully with strict ESC rules based on the calculations of toxicological burden indicators.

Suppression of the Carbon Vacancy Traps and the Corresponding Leakage Current Reduction in 4H-SiC Diodes by Low-Temperature Implant Activation in Combination With Oxidation

Junction barrier Schottky diode fabrication involves multi-folded Al ion implantation for realizing p-type doping. With a new fabrication recipe, we demonstrate that the trade-off between sufficiently high Al acceptor activation and sufficiently low residual concentration of carbon vacancies - acting as free carrier traps - may be resolved applying relatively low temperature anneals (1700°C), followed by the thermal oxidation which leads to in-diffusion of the carbon interstitials from the C-rich sacrifice-oxide/SiC interface. Specifically, we detected two major interconnected factors: suppression of the carbon vacancies and dramatic reduction of the reverse leakage current (by 32 times at -1200 V). The reduction of the reverse biased current is correlated with the removal of the carbon vacancies, interconnected with the Poole-Frenkel emission contribution to the leakage current.

Physical and mechanical properties of ultrapure copper obtained by zone melting

This paper presents the results of studies on the electrical conductivity, macro- and microstructure of ultrapure copper (5N3) obtained after zone melting of refined copper (99.96% Cu). The effect of residual concentrations of impurity metals on the electrical conductivity of ultrapure copper has been established. To assess the effect of low concentration impurities on the electrical conductivity of copper, the authors used a linear dependence of the increase in resistivity on the concentration of impurities (Ci), which was determined by the Mathyssen-Fleming rule. It is shown that low residual concentrations of impurity metals obtained in copper after its zone melting refining, ppm (ppm = 10&ndash;4 %): 0.2As; 0.06Sb; 0.006Ag; 0.07Bi; 0.006Sn; 0.02Pb; 1,1Ni have practically no effect on the electrical conductivity of ultrapure copper. The maximum electrical conductivity of M00K industrial grade copper (99.99% Cu) is 59 MSm/m, while zonerefined copper with a copper content of 99.999% has the electrical conductivity of 60.2 MSm/m. The values of the electrical conductivity of the obtained samples can serve to control the quality of obtained copper. It is shown that, in contrast to the microstructure of the initial copper sample, the ultrapure copper microstructure is a densely packed structure consisting of fine grains. On the microstructure map of ultrapure copper, the presence of individual impurity metals in the form of rounded small balls was established. Elongated filaments in the form of continuous lines, which are associated with the formation of chemical compounds of impurity metals with each other, are also found. This phenomenon is clearly observed on the microstructure map of ultrapure copper, captured at a magnification of 1000x under conditions of etching of the sample under study. The values of macro- and microhardness of the initial copper sample and ultrapure copper sample are established. The hardness of the initial copper sample is 84.42 HB (according to Brinell). After zone melting refining of copper from impurities, the hardness of the resulting ultrapure copper was 59.85 HB. Measurements of the microhardness of samples of the initial copper sample and ultrapure copper obtained by zone melting showed the microhardness of 103.0 and 70.42, respectively.

Continuous simultaneous saccharification and co-fermentation (SSCF) for cellulosic L-lactic acid production

Continuous fermentation is preferred in industrial bioprocesses by its steady-state operation mode and the significant reduction of switch operation of vessels emptying, cleaning, and sterilizing. General biorefinery fermentation of lignocellulose is conducted in the mode of simultaneous saccharification and co-fermentation (SSCF) thus the continuous operation does not stand well because of the mismatch between the optimal temperatures of cellulase enzymes and microbial cells. This study challenged the continuous SSCF operation for production of high chiral purity L-lactic acid based on the dry biorefinery processing platform. An engineered thermophilic L-lactic acid bacterium Pediococcus acidilactici with complete non-glucose assimilation capacity and antibacterial activity with a nearly perfect match of temperature (42–50 °C) and pH (5.5) with that of cellulase enzyme used (50 °C, pH 4.8). This microbial cell factory allows the enzymatic hydrolysis and fermentation to be conducted simultaneously in one-pot bioreactor and provides the basis for establishing a valid continuous SSCF operation. The continuous SSCF of the biodetoxified wheat straw was established in cascade bioreactors and the performances of L-lactic acid titer, yield, and productivity reached 107.5 ± 1.1 g/L, 0.29 ± 0.01 g/g DM, and 2.69 ± 0.03 g/L/h, respectively. The chiral purity of the cellulosic L-lactic acid reached 99.5 %. The low residual sugar concentration and high-optical purity L-lactic acid product in broth facilitate the subsequent purification of L-lactic acid as the monomer for cyclic lactide or direct PLA synthesis. This multi-stage continuous SSCF technology overcomes the inherent barriers of the batch SSCF operation and provides a prototype for future industrial cellulosic lactic production.

Assessing the potential use of composite titanium-containing coagulants, when treating wastewater from copper compounds

Wastewater treatment from heavy metals is a complicated and currently relevant task. Electrochemical coating processes are undoubtedly a main source of heavy metal compounds in wastewater. The second major source of heavy metal input to the environment is mining and processing of various ores. As part of the conducted research, the author assessed a potential intensification of wastewater treatment from copper compounds, using conventional and titanium-containing chemical agents. The samples taken for research were wastewater from electroplating facilities, containing copper compounds, rinse waters after neutralization and sedimentation, and mine waters. It is found that the use of pure titanium salts (titanyl sulfate) contributes to achieving the minimum residual concentration of copper compounds for all the wastewater samples under study; however, their extremely high cost makes this process economically impractical. Composite titanium-containing chemical agents produced by modification of aluminum sulfate with added titanium compounds significantly increased efficiency of the base chemical agent and reduced the residual concentration of copper in wastewater by almost 30%. Iron-containing coagulant was not efficient for the task. Factoring into a minimum amount of added titanium compounds (5&ndash;10 % wt.), the cost of composite titanium-containing chemical agents is slightly higher than the cost of pure aluminum sulfate, while the lower residual concentration of copper will significantly reduce the amount of penalties from the regulatory authorities for discharging pollutants into the city drainage main above the limit. It is stated that composite titanium-containing coagulants also contribute to a significant increase in efficiency of removing suspended particles and the coagulation sludge sedimentation rate, entailing reduced sizes of wastewater treatment facilities or their increased performance.The author gratefully acknowledges Natalia E. Kruchinina, research advisor,&nbsp;Doctor of Engineering Sciences, Professor, Head of the Industrial Ecology&nbsp;Department.The measurements were made using equipment of the Mendeleev Research&nbsp;Equipment Sharing Center.

Assessment of water, sanitation, and hygiene services in district health care facilities in rural area of Mekong Delta, Vietnam.

Access to sufficient water, sanitation, and hygiene (WASH) services is a crucial requirement for patients during therapy and general well-being in the hospital. However, in low- and middle-income countries, these services are often inadequate, resulting in increased morbidity and mortality of patients. This study aimed at assessing the current situation of WASH services in six District Health Care Facilities (DHCFs) in rural areas of the Mekong Delta provinces, Vietnam. The results showed that these services were available with inappropriate quality, which did not compromise the stakeholders' needs. The revealed WASH infrastructures have raised concerns about the prolonged hospital stays for patients and push nosocomial infections to a high level. The safety of the water supply was doubted as the high E. coli (> 60%) and total coliform incidence (86%) was observed with very low residual chlorine concentration (< 0.1mg/L) in water quality assessment. Moreover, water supply contained a high concentration of iron (up to 15.55mg/L) in groundwater in one DHCF. Technical assessment tool analysis proved that the improper management and lack of knowledge by human resources were the primary roots of the observed status WASH services. Improvement of the perceptions of WASH should be done for the hospital staff with collaboration and support from the government to prevent incidents in the future.