Sodium Nitrate Solutions Research Articles

Effect of Aqueous Electrolyte Composition on Efficiency of Electrochemical Post-Processing of Additive Manufacturing Products from Ti-6Al-4V Alloy Obtained by Selective Electron Beam Melting

The influence of the anionic composition of an aqueous electrolyte on the efficiency of the electrochemical leveling of the initial microgeometry of samples obtained by the selective electron beam melting (SEBM) at the following mode parameters was studied: current density – 20 A/cm2, initial interelectrode gap – 0.3 mm, average speed of electrolyte pumping – 12 m/c. Aqueous solutions of sodium chloride, nitrate, perchlorate and bisalt electrolytes based on them were studied. It was that aqueous solutions of sodium perchlorate have the best microleveling properties among the studied working media, which provides the ability to reduce the parameters Ra and Rz from values of 35 and 180 μm, respectively, to values of 3.2 and 20 μm during electrolysis of 30 s in a direct-flow electrolyzer. It was established that the microgeometry leveling corresponds to the model of the secondary distribution of dissolution rates; two main factors were identified that significantly influenced on the result: polarization of the electrodes and a decrease in the oxidation state of metal ions passing into the solution during electrochemical machining in the vicinity of the depression in relation to the protrusion due to changes in the local conditions of electrolysis. Microetching along grain boundaries in the studied electrolytes was not detected at the accepted parameters of the electrolysis mode.

Adsorptive removal of a nitrate ion from the aqueous solution of sodium nitrate by application of double fixed-bed column

This study focuses on the removal of nitrate ions from aqueous solutions using rice husk activated carbon (RHAC). The RHAC was subjected to characterization via Fourier transform infrared (FTIR), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), and X-ray florescence (XRF) to ascertain its functional groups, surface morphology, and oxide/elemental composition, respectively. Batch experiments were conducted to assess the impact of nitrate concentration, bed height, and number of packing layers on removal efficiency. FTIR spectra revealed favorable sorption-related functional groups within RHAC, while SEM analysis indicated the presence of effective sorption sites on its surface. EDS analysis of the rice husk adsorbent before adsorption (RHBS) demonstrated a significant composition of Si (42.20%), O (35.30%), and Ca (12.33%). The batch study unveiled a concentration-dependent decrease in nitrate removal efficiency, alongside the enhanced performance with increased bed height and number of packing layers. Kinetic data fitting favored the Yoon–Nelson and Adams–Bohart models. Overall, RHAC exhibited efficient nitrate ion removal, with column performance notably improved by utilizing multiple packing layers. These results will enhance our understanding of the mechanisms involved in removing nitrate ions and highlight the potential effectiveness of RHAC, especially when utilized with multiple packing arrangements in column setups.

In vitro bioaccessibility of inorganic and organic copper in different diets

In poultry diets, copper is an essential nutrient that is critical for various physiological functions. Although copper sulfate is commonly used due to its cost-effectiveness, organic copper sources are gaining popularity because of their superior production outcomes and environmental benefits. Nevertheless, understanding the distinct bioaccessibility of inorganic and organic copper in diverse dietary setting remains limited. This study investigated the bioaccessibility of copper sulfate, copper amino acid chelate, and copper proteinate in the intestine via in vitro digestion and in situ dialysis. The results showed significant differences in the molecular size distribution of compounds formed by different copper salts within the intestinal environment, thereby leading to varying bioaccessibility. Copper sulfate has a bioaccessibility of 47 % ± 4%, which is significantly lower than copper amino acid chelate and copper proteinate (63% ± 5%, and 60% ± 4%, respectively) in purified diet systems. Similarly, in whey protein systems, sulfate records 54% ± 10% bioaccessibility compared to 78% ± 9% and 76% ± 5% for copper amino acid chelate and copper proteinate. Coexisting feed ingredients have a significant impact on copper bioaccessibility. Copper sulfate forms precipitates, reducing its bioaccessibility to 34% ± 1% in sodium nitrate solution. The addition of digestive enzyme increases the bioaccessibility of copper sulfate to 81% ± 2% by providing organic ligands. Digestive enzyme also enhanced the bioaccessibility of copper proteinate from 36% ± 4% to 81% ± 4% by degrading its ligands. However, feed ingredients may decrease copper bioaccessibility by forming macromolecular complexes with copper, as all the organic ligands can competitively bind with copper in the intestine. These findings emphasize the importance of considering copper salt types and diet composition in animal nutrition practices.

Fabricating Precise and Smooth Microgroove Structures on Zr-Based Metallic Glass Using Jet-ECM.

Zr-based metallic glasses (MGs) are promising materials for mold manufacturing due to their unique mechanical and chemical properties. However, the high hardness of metallic glasses and their tendency to crystallize at high temperatures make it challenging to fabricate precise and smooth microscale structures on metallic glasses. This limitation hampers the development of metallic glasses as molds. Jet electrochemical machining (jet-ECM) is a non-contact subtractive manufacturing technology that utilizes a high-speed electrolyte to partially remove material from workpieces, making it highly suitable for processing difficult-to-machine materials. Nevertheless, few studies have explored microgroove structures on Zr-based MGs using sodium nitrate electrolytes by jet-ECM. Therefore, this paper advocates the utilization of the jet-ECM technique to fabricate precise and smooth microgroove structures using a sodium nitrate electrolyte. The electrochemical characteristics were studied in sodium nitrate solution. Then, the effects of the applied voltages and nozzle travel rates on machining performance were investigated. Finally, micro-helical and micro-S structures with high geometric dimensional consistency and low surface roughness were successfully fabricated, with widths and depths measuring 433.7 ± 2.4 µm and 101.4 ± 1.6 µm, respectively. Their surface roughness was determined to be 0.118 ± 0.002 µm. Compared to non-aqueous-based methods for jet-ECM of Zr-based MGs, the depth of the microgrooves was increased from 20 μm to 101 μm. Furthermore, the processed microstructures had no uneven edges in the peripheral areas and no visible flow marks on the bottom.

Electrochemical dissolution behavior of 07Cr16Ni6 alloy in sodium nitrate solution

07Cr16Ni6 alloy is a kind of martensitic-austenitic duplex stainless steel that is widely used in aviation and aerospace. Electrochemical machining (ECM) is an ideal manufacturing process for 07Cr16Ni6 alloy because of its high machining accuracy and good final surface quality. Studying the electrochemical dissolution behavior is pre-requisite and key to optimizing the ECM process; however, few studies have focused on the electrochemical dissolution behavior of 07Cr16Ni6 alloy. In this work, the corrosion behavior, passivation characteristics, efficiency curves, and material-removal process of 07Cr16Ni6 alloy in NaNO3 solution were comprehensively investigated. Based on the curves of potentiodynamic polarization and conductivity curve, it was found that both of them have significant passive and transpassive characteristics. The results of X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy indicated that the passive film was mainly composed of Fe3O4, α-Fe2O3, γ-Fe2O3, Cr2O3, NiO, SiO, and SiO2, and its structure was composed of a dense inner-layer film and a loose outer-layer film. A schematic model was proposed to characterize the interface structure between the 07Cr16Ni6 alloy, the passive film and electrolyte. ECM tests were performed at different current densities and for different corrosion times. The current-efficiency results indicate that the material-removal rate can be divided into three regions. The current efficiency first rises gently, then rises steeply once the current density exceeds 26 A cm−2; it finally remains stable at current densities greater than 45 A cm−2. The corrosion morphology exhibits loose, blocky bulges at low current density, while the surface exhibits lath-type martensite structures when the current density j > 15 A cm−2. The material-dissolution process of the 07Cr16Ni6 alloy in NaNO3 solution at 20 A cm−2 was presented. Finally, a model of dissolution was established to characterize the electrochemical dissolution of the 07Cr16Ni6 alloy in NaNO3 solution.

Exclusion liquid chromatography of carboxymethylchitin and carboxymethylchitosan from crustacean <i>Artemia Parthenogenetica</i> of the Aral Sea

The article deals with the synthesis of water-soluble derivatives of chitin and chitosan from cysts of crustaceans of the genus Artemia Parthenogenetica of the Aral Sea by carboxymethylation of OH and NH2 groups of their chains. The elution, viscosity and polyelectrolyte properties in size exclusion liquid chromatography of carboxymethylchitin and carboxymethylchitosan were studied. The suppression of electrostatic effects and the implementation of the exclusion mechanism for the separation of these polysaccharides were achieved by using an aqueous solution of sodium nitrate with a concentration of 0.1 mol/l as an eluent, which was recommended for determining molecular weight characteristics.

PSII-24 Relationship Among Color, Physicochemical Traits, and Ruminal in Situ Dry Matter Digestion of Corn Grains from Argentina, Brazil, and the United States

Abstract Corn-derived starch and rumen-degradable protein (RDP) available for rumen microbial fermentation vary significantly with corn hybrid and environmental conditions. Identifying corn physicochemical traits potentially correlated with ruminal DM digestibility would facilitate the prediction of its nutritional value compared with more time-consuming determinations. We assessed 1) the effect of corn origin on color, physicochemical traits, and 22-h in situ DM digestibility (22h-DMD), and 2) the relationship of color and physicochemical traits with 22h-DMD on Argentinian (AR, n = 29), Brazilian (BR, n = 4), and North American (US, n = 15) corn samples. The hardness-associated properties measured were: color (Hue angle; H) and physicochemical traits [crude protein (CP), thousand kernel weight (TKW), test weight (TW, Schopper chondrometer with ¼ L capacity), floaters (FLO, percent of kernels floating in a sodium nitrate solution), kernel density (KD, pycnometer method), vitreousness (VIT), and coarse-to-fine milling ratio (C:F)]. In situ 22h-DMD was determined using two ruminally cannulated steers receiving a 53:47 forage-to-concentrate ratio diet. Mastication was simulated by grinding a 100-g sample for 10 s using a 0.625-cm screen. For each steer, three sets of 4-g (DM basis) of each corn sample were placed into R1020 Ankom bags and introduced in the ventral sac of the rumen at two independent events separated by 48 h. Four bags per sample were placed in a water bath (39 °C, 15 min) to determine the soluble fraction (0h-DMD). Corn origin effect on color and physicochemical traits and on 0h-DMD and 22h-DMD were tested using GLM and MIXED procedures, respectively. Means were compared by Tukey-Kramer test. Relationships among variables were studied using a correlation matrix (PROC CORR) and stepwise multiple linear regression (PROC REG). All traits differed (P < 0.01; Table 1) among corn origin, being AR corns intermediate in hardness-associated properties between BR and US samples, though more similar to BR ones. Correlation coefficients (P < 0.01) of 22h-DMD with H, FLO, TW, KD, C:F, and CP, were 0.43, 0.80, −0.77, −0.71, −0.82, and −0.72, respectively; TKW was unrelated (P = 0.26) to 22h-DMD. The predictive 22h-DMD equation (P < 0.01) based on physicochemical traits was 22h-DMD (%) = 160.31 – 1.16 × TW (kg/hL) – 7.49 × C:F (g/g; RMSE = 3.54, R2 = 0.74). Softer kernels with higher H and FLO and lower TW, KD, C:F, and CP, demonstrated greater 22h-DMD than harder samples. Indeed, TW and C:F resulted in reliable predictors of 22h-DMD to describe the nutritional value of corn samples. Succinctly, AR and BR corn hardness-associated properties contrasted with US ones. We hypothesized that greater CP and reduced 0h-DMD and 22h-DMD of harder genotypes may reduce or eliminate the need for RDP supplementation when those grains are included in beef cattle finishing rations; however, more research is warranted on this topic.

Particle Network Self-Assembly of Similar Size Sub-Micron Calcium Alginate and Polystyrene Particles Atop Glass.

Particle-mediated self-assembly, such as nanocomposites, microstructure formation in materials, and core-shell coating of biological particles, offers precise control over the properties of biological materials for applications in drug delivery, tissue engineering, and biosensing. The assembly of similar-sized calcium alginate (CAG) and polystyrene sub-micron particles is studied in an aqueous sodium nitrate solution as a model for particle-mediated self-assembly of biological and synthetic mixed particle species. The objective is to reinforce biological matrices by incorporating synthetic particles to form hybrid particulate networks with tailored properties. By varying the ionic strength of the suspension, the authorsalter the energy barriers for particle attachment to each other and to a glass substrate that result from colloidal surface forces. The particles do not show monotonic adsorption trend to glass with ionic strength. Hence, apart from DLVO theory-van der Waals and electrostatic interactions-the authors further consider solvation and bridging interactions in the analysis of the particulate adsorption-coagulation system. CAG particles, which support lower energy barriers to attachment relative to their counterpart polystyrene particles, accumulate as dense aggregates on the glass substrate. Polystyrene particles adsorb simultaneously as detached particles. At high electrolyte concentrations, where electrostatic repulsion is largely screened, the mixture of particles covers most of the glass substrate; the CAG particles form a continuous network throughout the glass substrate with pockets of polystyrene particles. The particulate structure is correlated with the adjustable energy barriers for particle attachment in thesuspension.

Electrochemical dissolution behavior of TNM intermetallic in sodium nitrate solution

TNM alloy is a new kind of lightweight and high temperature resistant material. Electrochemical machining (ECM) is an ideal manufacturing method for TNM alloy because of its high machining efficiency and good machining quality. In this work, the dissolution properties and surface passive film of TNM in NaNO3 solution are studied comprehensively. The passivation properties of the samples are tested using potentiodynamic, potentiostatic and CV curves. The results show that there are obvious passive and transpassive areas on the surface of TNM alloy, and the corrosion resistance of the passive film gradually increased with the test time from 0 to 7200 s. XPS and EIS indicate that the passive film mainly consists of Al2O3, TiO2, Nb2O5 and MoO3. Its structure is a bi-layer consisting of an inner layer with few pores and an outer layer with many pores. A corresponding schematic model is also proposed to characterize the interface structure between TNM alloy matrix and passive film. TNM alloy has a very high material removal rate according to the ηω-j curve. The dissolution morphology of TNM alloy is observed at various current densities. It is found that the surface dissolution morphology is very different under low and high current densities. The sample exhibits a loose lamellar microstructure with some isolated lamellar colonies at low current density, while the surface is quite smooth (about Ra 0.55 μm) when current density (j) > 20 A/cm2. Finally, the material dissolution process of TNM alloy at 2 and 25 A/cm2 is also presented.

Mesoporous cellulose assemblage Al-doped ferrite for sustainable defluoridation process based on parameters optimization through RSM

In this work, we present defluoridation studies of Mesoporous Cellulose assemblage Al-doped ferrite (MCAF). The characteristic changes in the material were observed by Fourier transform infrared spectroscopy, Scanning electron microscopy, Energy dispersive X-ray spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller surface area analysis and thermal gravimetric analysis. Scaffolds formed due to introduction of aluminium and iron oxides shows collaborative effect on the material. It increases the stability of the material and makes the material mesoporous. Magnetic behavior contributes towards effortless handling of the material. Collective impact of the different parameters on adsorption process were optimized by availing the response surface methodology (RSM). Design of experiments based on 48 runs was formulated and accordingly experiments were conducted. Process optimization was carried out as next step and based on the optimized condition 98 % adsorption was achieved for 20 mg/L initial fluoride concentration. From contour and surface plots between the three independent variables, the optimized adsorption time was 30 min, pH at 6.27 and adsorbent dose at 0.25 g. The optimization condition had a composite desirability of 1. Isotherm studies have revealed that the adsorption process fit well to Freundlich model. The composite displayed maximum absorption capacity of 42.52 mg g-1for fluoride adsorption. Pseudo second order followed for the adsorption of fluoride. Adsorption process found to be spontaneous and exothermic as revealed from thermodynamic studies. Applicability of composite at field conditions was tested with real samples from fluoride endemic areas through column studies. It was found that approximately 5 L of water sample having fluoride concentration 4.81 mg/g was purified with 1 g of the adsorbent. The used adsorbent had been regenerated by 5 % (w/V) sodium nitrate solution. Adsorption desorption cycles shown that up to fourth cycle the % removal of fluoride was more than 90 %.

The determination of zinc using flow injection and continuous flow analysis combined with a polymer inclusion film-coated column: Application to the determination of zinc in alloys and commercial lithium chloride

A column coated with a polymer inclusion film (PIF) containing Aliquat 336 as carrier cast on glass beads packed in a glass tube is described for the separation, preconcentration, and determination of zinc(II) in flow injection analysis (FIA) and continuous flow analysis (CFA) systems. In the FIA method, 200 μL of a sample solution containing 2 mol/L lithium chloride is injected into a 2 mol/L lithium chloride stream. This converts zinc(II) ion into its anionic chlorocomplexes which are then extracted into the Aliquat 336-based PIF by anion exchange. The extracted zinc(II) is then back-extracted into a stream of 1 mol/L sodium nitrate solution and determined spectrophotometrically using 4-(2-pyridylazo)resorcinol as the color reagent. The limit of detection (LOD, S/N = 2) was determined as 0.017 mg/L. The usability of the PIF-based FIA method was demonstrated by the determination of zinc in alloys. The PIF-coated column was also employed successfully in the CFA determination of zinc(II) as an impurity in commercial lithium chloride samples. For this, 2 mol/L commercial lithium chloride solution was passed through the column for a predetermined time period followed by stripping in a stream of 1 mol/L sodium nitrate solution.

Environmental soil contamination with zoonotic soil-transmitted helminths in the temple grounds of Chachoengsao Province, Thailand

Background and Aim: Soil-transmitted helminth infections are a serious public health problem. The soil is an important reservoir for several helminth species. This study aimed to estimate the prevalence of soil contamination with zoonotic soil-transmitted helminths. Materials and Methods: Soil samples were collected on the grounds of 19 temples in Ratchasan and Bang Khla districts, Chachoengsao Province, Thailand, between June 2021 and February 2022. A total of 190 soil samples were collected from ten different areas on the grounds of each temple, of which 31 (16.3%) were contaminated. The samples were analyzed by a centrifugal flotation technique using a saturated sodium nitrate solution. Results: Six genera of helminths were recovered from the soil samples, of which five genera were identified as helminth eggs and two genera were identified as helminth larvae. The prevalence of soil contamination with helminth eggs was as follows: Toxocara spp. 15.8% (30/190), hookworm/strongylid 12.1% (23/190), Trichuris spp. 6.8% (13/190), Taenia spp. 2.1% (4/190), Ascaris spp. 1.6% (3/190), and unidentified helminth eggs 5.8% (11/190). Moreover, nematode larvae consisted of 8.4% (16/190) hookworm/strongylid, 3.7% (7/190) of Strongyloides spp., and 4.2% (8/190) unidentified nematode larvae. The rates of soil-transmitted helminth contamination were not significantly different between Ratchasan and Bang Khla districts (p = 0.878). Conclusion: Soil-transmitted helminth contamination was found in the soil environment of the community temples with a high probability of spreading intestinal helminthiasis to the local residents. Therefore, public awareness campaigns should be conducted targeting people in the community to increase their knowledge and understanding about animal healthcare to prevent and control the spread of soil-transmitted helminthiasis. Keywords: soil contamination, soil-transmitted helminth, temple, Thailand, zoonotic helminth.

Electrochemical Properties and Specific Selectivity of Ion-Exchange Membranes in Borate-Nitrate Electrolyte Solutions

Electrochemical characteristics of heterogeneous cation- and anion-exchange Ralex membranes and the mechanism of transfer of ions of salt, boric acid and its anions through membranes at different pH values were investigated by the method of rotating membrane disk (RMD). It is shown that boric acid is transported mainly through an anion exchange membrane. At pH 9.5, the limiting stage of anion transfer through the anion exchange membrane is the reaction of tetrahydroxyborate \({\text{B}}\left( {{\text{OH}}} \right)_{4}^{ - }\) anion formation. The study of the electrodialysis separation of a solution of sodium nitrate and boric acid showed that the electrodialysis method makes it possible to effectively separate the components of the mixture, while the value of the specific selectivity coefficient \({{P}_{{{{\text{B}} \mathord{\left/ {\vphantom {{\text{B}} {{\text{NaN}}{{{\text{O}}}_{{\text{3}}}}}}} \right.} {{\text{NaN}}{{{\text{O}}}_{{\text{3}}}}}}}}}\) = (0.02–0.06), depending on the voltage on the electrodialyzer.

Gamma Radiation-Induced Degradation of Acetohydroxamic Acid (AHA) in Aqueous Nitrate and Nitric Acid Solutions Evaluated by Multiscale Modelling.

Acetohydroxamic acid (AHA) has been proposed for inclusion in advanced, single-cycle, used nuclear fuel reprocessing solvent systems for the reduction and complexation of plutonium and neptunium ions. For this application, a detailed description of the fundamental degradation of AHA in dilute aqueous nitric acid is required. To this end, we present a comprehensive, multiscale computer model for the coupled radiolytic and hydrolytic degradation of AHA in aqueous sodium nitrate and nitric acid solutions. Rate coefficients for the reactions of AHA and hydroxylamine (HA) with the oxidizing nitrate radical were measured for the first time using electron pulse radiolysis and used as inputs for the kinetic model. The computer model results are validated by comparison to experimental data from steady-state gamma ray irradiations, for which the agreement is excellent. The presented model accurately predicts the yields of the major degradation products of AHA: acetic acid, HA, nitrous oxide, and molecular hydrogen.

Polythiophene/multiwalled carbon nanotubes/nitrate reductase deposited glassy carbon electrode (GCE/PTH/MWCNT/NR): a novel biosensor for the detection of nitrate in aqueous solution

Abstract In the present investigation, a novel biosensor (GCE/PTH/MWCNT/NR) based on the nanocomposite of polythiophene (PTH) and multiwalled carbon nanotube (MWCNT) immobilized by nitrate reductase (NR) was designed and made on a glassy carbon electrode (GCE). PTH and its composite with MWCNT were prepared by in situ oxidative polymerization. The structural features and surface morphologies of the composites were investigated by the standard analytical techniques, namely, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Measurements of the electrochemical performance and electrocatalytic activity of GCE/PTH/MWCNT/NR were carried out by cyclic voltammetry at different scan rates (20–100 mV s−1) in artificially polluted water containing nitrate ions. This laboratory-developed bio-electrode attained a maximum current density of 5.12 mAcm−2 at a scan rate of 100 mVs−1 for 8.0 mM sodium nitrate solution.

Study on ionic association behavior in sodium nitrate solution

Raman spectroscopy combined with component analysis and molecular dynamics simulation were used to study chemical species and their transformation in aqueous sodium solutions. Study shows that the characteristic vibrational frequency of nitrate ions (ν1-NO3-) blue-shifted from 1043.9 to 1046.9 cm−1, and the full width at half maximum increased from 6.8 to 10.8 cm−1 as the concentration increasing. When water/salt molar ratio (WSR) > 30, the relative concentration (RC) of free hydrated ions and solvent shared ion pair accounts for the vast majority, and there is almost no contact ion pair in solution. When WSR less than 30, due to the continuous reduction of the number of water molecules, the hydrated water molecules around the sodium ions and nitrate ions begin to decrease, and solvent shared ion pair or contact ion pair gradually forms. Sodium ions and nitrate ions mainly exist in a monodentate coordination. When WSR > 160, both the relative concentration of contact ion pair and complex structure is close to 0. This work proves that a lower RC of complex structure in solution, a smaller supersaturation of the solution is achieved, meaning aqueous sodium nitrate solution is easier to nucleate crystals.

Thermal denitration of sodium nitrate in a fluidized bed reactor: Optimization of process parameters and application of S-statistics for fluidization state monitoring

A voluminous liquid waste stream is generated as sodium nitrate (NaNO3) solution in Spent Nuclear Fuel Reprocessing Plants. Fluidized bed thermal denitration is a strong contender among various disposal options for this stream. In the present work experimental investigations on thermochemical denitration of NaNO3 have been carried out in an 80 NB laboratory scale fluidized bed reactor. Carbon based reductant was utilized to convert NaNO3 to sodium carbonate (Na2CO3) as well as to reduce denitration temperature. The operating parameters were optimized for maximum conversion of NaNO3 and 99.13% denitrification has been achieved. Pressure fluctuation across bed was also recorded and analysed in the state space domain employing attractor comparison technique. This technique computes a statistical metric ‘S’, as a measure of the fluidization state in the fluidized bed reactor and can be used for early detection of agglomeration in the bed. The sensitivity and early agglomeration detection capability of S-statistics are illustrated with experimental results for a liquid-sprayed gas fluidized bed.

Selective dissolution of copper and iron from molybdenite concentrate using acidic sodium nitrate solution

In this study, the selective dissolution of copper and iron from the molybdenite (MoS2) concentrate consisting of chalcopyrite and pyrite by acidic sodium nitrate leaching has been investigated to improve the quality of molybdenite. The influence of various leaching parameters, namely sodium nitrate (NaNO3) and sulfuric acid (H2SO4) concentration, temperature, contact time, and solid: liquid phase ratio, was examined on the dissolution of copper (Cu) and iron (Fe) from the concentrate. Under the optimized conditions, the extraction of Cu and Fe can achieve 81.4% and 74.1%, respectively, along with a minor amount of molybdenum (Mo) loss in the solution from the concentrate in 240 min leaching. The kinetic study indicated that the impurities removal process was controlled by a mixed mechanism with a corresponding activation energy of 35.77 kJ/mol at the temperature range of 70–97 °C. The XRD and SEM-EDS analysis of the solid residues from the leaching revealed the insolubility of molybdenite in the leaching media. As a result, the molybdenite grade reached 90.73 wt% from an initial value of 81.33 wt%.

A Comparative Study of Mini-FLOTAC With Traditional Coprological Techniques in the Analysis of Cetacean Fecal Samples.

Free-ranging cetaceans are considered sentinels for the marine ecosystem's health. New and non-invasive methods have been set up for the collection of fecal samples from free-ranging big whales at sea, permitting to gain an excellent epidemiological picture of parasitic infections in wild populations. To select the best protocol to be used for copromicroscopic examination in cetaceans stool samples, we evaluated the sensitivity of two commonly used techniques, i.e., a sedimentation-floatation method and the Mini-FLOTAC through validation by helminth isolation from the digestive tract. For this aim, gastrointestinal content and fecal samples were collected during necropsy from 44 cetaceans, including bottlenose dolphins (Tursiops truncatus), striped dolphins (Stenella coeruleoalba), sperm whales (Physeter macrocephalus), Risso's dolphins (Grampus griseus), Cuvier's beaked whales (Ziphius cavirostris), pilot whale (Globicephala melas), and fin whales (Balaenoptera physalus). Helminths were recovered through washing and filtering of the gastrointestinal contents and morphologically identified. Copromicroscopic examinations were performed on formalin-preserved fecal samples, using a sodium nitrate, sodium thiosulphate, and sucrose solution (s.g. = 1.450) for both methods. Helminths belonging to 9 taxa (i.e., the trematodes Synthesium tursionis, Synthesium delamurei, Campula palliata, Braunina cordiformis, Pholeter gastrophilus, the nematode Anisakis sp., cestodes of the family Tetrabothriidae and the acanthocephalan Bolbosoma sp.) were isolated. Eggs referable to the same taxa, with the exception of cestodes, were found in copromicroscopic analyses. Sensitivity of the Mini-FLOTAC method appeared higher or equal for all taxa, proving superior to the sedimentation-flotation method for the detection of all except Anisakis sp. The concordance of the two tests indeed revealed a moderate to perfect agreement (kappa values 0.42–1). Not excluding the limitations inherent to the techniques themselves, explanations for false-negative results at copromicroscopy could be linked to parasite-related factors, including prepatent infections, low parasitic burdens, or intermittent egg shedding. Notwithstanding these limitations, this study evidenced that the Mini-FLOTAC protocol approximates more accurately the composition of the gastrointestinal helminthic community of cetaceans from copromicroscopic examination, providing at the same time a quantitative estimation.

Reduction of the nematode egg reappearance period in horses after anthelmintic therapy.

Background and Aim:Anthelmintics are used to control equine nematodes. However, helminth resistance to regularly used drugs is a well-known challenge. Among tests to assess effective control and monitor resistance, the most common is the fecal egg count reduction test (FECRT). In the absence of reliable FECRT results, the nematode egg reappearance period (ERP) is taken into account. This study aimed to examine horses from farms around the Moscow Region to assess nematode resistance through ERP after therapy.Materials and Methods:In the first stage, fecal samples from 280 horses were examined by the flotation method with a sodium nitrate solution. The eggs per gram (EPG) in feces were counted using the modified McMaster technique. One hundred and forty out of 280 horses were selected for further work. Five groups were formed: Two groups of horses infected with strongyles (n = 50) and three groups with Parascaris equorum (n = 90). Therapy against strongyles was performed with albendazole and ivermectin. Therapy for parascaridosis was performed with fenbendazole, ivermectin, and aversectin C. Samples from the horses in each group were taken on the 14th day (2 weeks), 28th day (4 weeks), 42nd day (6 weeks), 56th day (8 weeks), and 84th day (12 weeks) after treatment, and the amount of EPG in each sample was determined.Results:Overall, nematodes were found in 65% of the horses examined. P. equorum was most frequently recorded (42.1%) followed by Strongylidae gen. spp. (27.9%). The strongyles ERP after therapy with albendazole and ivermectin was estimated on 42 days (6 weeks). The growth of P. equorum eggs in the feces was observed from the 56th day (8 weeks) after therapy with fenbendazole, from the 42nd day (6 weeks) after therapy with ivermectin, and was observed from the 84th day (12 weeks) after the use of aversectin.Conclusion:Our study shows widespread reductions in nematode ERPs across the Moscow Region after ivermectin therapy in horses, suggesting that additional monitoring of these farms is needed for effective control of anthelmintic resistance.