Concentrations Of SCN Research Articles

First observation of HO˙ reactivity in water under high energy ions at elevated temperature.

This communication reports the first observation of the formation of HO˙ produced under two different High energy ion beams, (18)O(8+) and (36)Ar(18+) having Linear Energy Transfers (LET) of 65 and 350 eV nm(-1) respectively, at temperatures up to 411 K. Both scavenging with various concentrations of SCN(-) and heavy-ion pulse radiolysis methods are used with an original temperature and pressure regulated optical cell. Deconvolution of kinetics is used to analyze the evolution of HO˙ track segment yields as a function of time and temperature. It takes care of involving the ionic strength effect and Arrhenius expression in the rate constants correction. The results show a fast decay of HO˙ yields in the 10(-10)-10(-8) s range which denotes an efficient reactivity of this species in the track structure of the ion beam. This effect is enhanced with the lowest LET of O(8+). Increasing the temperature also accelerates the decays for both ions. These observations are discussed in terms of temperature activation of reactions and the track structure exhibiting the formation of HO˙ in a "low LET" penumbra around the ionization tracks. HO˙ track segment yields at 100 ns, of 0.4 × 10(-7) and 0.6 × 10(-7) mol J(-1), respectively for 350 and 65 eV nm(-1), are not affected by temperature.

Normative concentrations of urine thiocyanate in cassava eating communities in Nigeria

Exposure to cyanide is a major public health problem where highly cyanogenic cassava foods are consumed. Thiocyanate (SCN), the biomarker of exposure to cyanide is present in several foods, and produced endogenously. Concentrations of urine SCN were measured in endemic and non-endemic areas of ataxic polyneuropathy in Nigeria. Cassava food consumption in the endemic area was twice that of non-endemic areas. Geometrical mean (95% CI) urine SCN was 20 µmol/l (18–24) for no consumption of cassava foods, 56 µmol/l (49–64) for daily consumption, 56 µmol/l (48–65) for twice daily consumption and 85 µmol/l (62–117) for thrice daily consumption. 95th percentile reference limit was 125 µmol/l for no consumption of cassava food, but 360 µmol/l for thrice daily consumption. Urine SCN is a useful biomarker of exposure to cyanide from cassava foods. There is strong ecological association of exposure to cyanide and endemicity of ataxic polyneuropathy.

Degradación de tiocianato por hongos aislados de ambientes mineros y evaluación de su capacidad degradativa

used in gold production this compound is very toxic especially for environment, by nature reaction with sulfur it converts into thiocyanate (-SCN). In this paper, we isolate -SCN degrading fungus from Junin and Tumbes mining zones. Strains were assayed on 5 to 600 mM -SCN concentration, at least thiocyanate degrading kinetic was assayed at 1.2 g.L-1 of KSCN initial concentration, then the best strains had been morphological, biochemical and molecular identified using ITS RNA molecular marker. From 58 isolated fungus we found 4 unparfait funguses with a great thiocyanate degrading capacity those strains could be used for bioremediation processes. Thiocyanate degrading capacity of these strains was 50 g.L-1 on plate into 72 hours and their average capacity was 10.05 mg.L-1 -SCN with an standard velocity of -SCN degradation of 28.77 mg.L-1.h-1. Two strains were molecular identified as Fusarium trincictum by using ITS rDNA gene.

Myeloperoxidase-derived chlorinating species induce protein carbamylation through decomposition of thiocyanate and urea: novel pathways generating dysfunctional high-density lipoprotein.

Protein carbamylation through cyanate is considered as playing a causal role in promoting cardiovascular disease. We recently observed that the phagocyte protein myeloperoxidase (MPO) specifically induces high-density lipoprotein (HDL) carbamylation, rather than chlorination, in human atherosclerotic lesions, raising the possibility that MPO-derived chlorinating species are involved in cyanate formation. Here, we show that MPO-derived chlorinating species rapidly decompose the plasma components thiocyanate (SCN) and urea, thereby promoting (lipo)protein carbamylation. Strikingly, the presence of physiologic concentrations of SCN completely prevented MPO-induced 3-chlorotyrosine formation in HDL. SCN scavenged a 2.5-fold molar excess of hypochlorous acid, promoting HDL carbamylation, but not chlorination. Cyanate significantly impaired (i) HDL's ability to activate lecithin-cholesterol acyltransferase; (ii) the activity of paraoxonase, a major HDL-associated anti-inflammatory enzyme; and (iii) the antioxidative activity of HDL. Here, we report that MPO-derived chlorinating species preferentially induce protein carbamylation-rather than chlorination-in the presence of physiologically relevant SCN concentrations. The carbamylation of HDL results in the loss of its anti-inflammatory and antioxidative activities. MPO-mediated decomposition of SCN and/or urea might be a relevant mechanism for generating dysfunctional HDL in human disease.

Capillary ion electrophoresis of inorganic anions and uric acid in human saliva using a polyvinyl alcohol coated capillary column and hexamethonium chloride as additive of background electrolyte

A combination of polyvinyl alcohol chemically coated capillary (PVA capillary) and background electrolyte (BGE) with ion-pair reagent (hexamethonium dichloride, HMC) was used on capillary ion electrophoresis-UV detection (CIE-UV) for analysis of Br−, I−, NO2−, NO3−, SCN− and uric acid in human saliva. The PVA capillary prepared in our laboratory minimized electro-osmotic flow (EOF) at the BGE in pH 3–10, and did not affect the UV detection at 210nm by the PVA-layer on capillary wall. Therefore, use of the PVA capillary was suitable for sensitive UV detection for analyte anions, as well as suppression of protein adsorption. In this study, we optimized the BGE of 10mM phosphate plus 10mM HMC with applying a voltage of −15kV. HMC as an additive to BGE could manipulate the electrophoretic mobility of anions, without electrostatic adsorption to the PVA capillary. The CIE-UV could separate and determine analyte anions in human saliva containing proteins by the direct injection without pretreatments such as dilution or deproteinization within 13min. The relative standard deviations (n=10) were ranged of 0.5–1.6% in migration times, 2.2–6.8% in peak heights and 2.8–8.4% in peak areas. The limits of detection (S/N=3) were ranged of 3.42–6.87μM. The peak height of anions in this system was gradually decreased through the successive injections of saliva samples, but the problem was successfully solved by periodically conditioning the PVA capillary. The quantifiability of anions in human saliva samples by the CIE-UV was evaluated through the recoveries by standard addition methods and comparison of other representative analytical methods, as well as identification by ion chromatography (IC). From the anion analyses in 12 different saliva samples, the CIE-UV demonstrated that can obtain obvious differences in concentrations of SCN− between of smoker and non-smoker and those of uric acid between male and female with satisfactory results.

Mechanistic Study of Shape Evolution of Silver Nanoprisms in The Presence of KSCN

Silver nanoprisms can be etched and transformed into silver nanodiscs in the presence of SCN– ions. However, the blue-shifts of SPR bands of silver colloids abnormally depend on the concentrations of SCN– ions; for example, the values of blue-shifts in this study were 40, 250, and 100 nm in the presence of 10–4, 3 × 10–4, and 3 × 10–3 M SCN–, respectively. Blue-shifts of SPR bands reached the maxima, and two isosbestic points were found in the time-course spectra in the presence of KSCN within the so-called critical concentration range, at approximately 3 × 10–4 to 5 × 10–4 M. These two isosbestic points indicate that silver nanoprisms were not etched gradually in the presence of a critical concentration range of KSCN, but transformed into nanodiscs directly and immediately without forming blunt intermediates. Time-course TEM images of silver nanostructures, which were protected by the modification of a thin layer of HS(CH2)15CO2H (MHA) on the surface of the nanoparticles, were recorded to verify the mech...

Anion transport by the cochlear motor protein prestin

Prestin is a member of the SLC26 solute carrier family and functions as a motor protein in cochlear outer hair cells. While other SLC26 homologues were demonstrated to transport a wide variety of anions, no electrogenic transport activity has been assigned so far to mammalian prestin. We here use heterologous expression in mammalian cells, patch clamp recordings and measurements of expression levels of individual cells to study anion transport by rat prestin. We demonstrated that cells expressing rat prestin exhibit SCN(-) currents that are proportional to the number of prestin molecules. Variation of the SCN(-) concentration resulted in changes of the current reversal potential that obey the Nernst equation indicating that SCN(-) transport is not stoichiometrically coupled to other anions. Application of external SCN(-) causes large increases of anion currents, but only minor changes in non-linear charge movements suggesting that only a very small percentage of prestin molecules function as SCN(-) transporters under these conditions. Unitary current amplitudes are below the resolution limit of noise analysis and thus much smaller than expected for pore-mediated anion transport. A comparison with a non-mammalian prestin from D. rerio - recently shown to function as Cl(-)/SO(4)(2-) antiporter - and an SLC26 anion channel, human SLC26A7, revealed that SCN(-) transport is conserved in these distinct members of the SLC26 family. We conclude that mammalian prestin is capable of mediating electrogenic anion transport and suggest that SLC26 proteins converting membrane voltage oscillations into conformational changes and those functioning as channels or transporters share certain transport capabilities.

Thiocyanate hydrometallurgy for the recovery of gold. Part V: Process alternatives for solution concentration and purification

The gold–thiocyanate system is of interest as it could offer a number of advantages over the gold-cyanide system such as acidic leaching and less toxicity. In the gold–thiocyanate system, the rate of leaching can be accelerated by employing ferric ion as an oxidant. Ultimately, this would lead to a contaminated gold-bearing leach solution that would need to be treated. In this regard, process alternatives for solution concentration and purification are considered including solvent extraction, cementation, and carbon adsorption. The effect of ferric ion on the extraction and stripping of gold was studied. It was demonstrated that ferric ion has an adverse effect on the rate of gold stripping with thiourea. This situation was overcome by controlling the system chemistry-relatively low SCN concentration (0.02M) in aqueous phase and low amine concentration (0.01–0.02M) in the organic phase. Strategies other than solvent extraction including cementation with iron and zinc as well as activated carbon adsorption were considered and results reported. Finally, based on this study a conceptual flowsheet is given for the recovery of gold through thiocyanate hydrometallurgy.

Effect of selected Hofmeister salts on textural and rheological properties of nonfat cheese

Three Hofmeister salts (HS; sodium sulfate, sodium thiocyanate, and sodium chloride) were evaluated for their effect on the textural and rheological properties of nonfat cheese. Nonfat cheese, made by direct acidification, were sliced into discs (diameter=50mm, thickness=2mm) and incubated with agitation (6h at 22°C) in 50mL of a synthetic Cheddar cheese aqueous phase buffer (pH 5.4). The 3 HS were added at 5 concentrations (0.1, 0.25, 0.5, 0.75, and 1.0M) to the buffer. Post-incubation, cheese slices were air dried and equilibrated in air-tight bags for 18h at 5°C before analysis. Small amplitude oscillatory rheology properties, including the dynamic moduli and loss tangent, were measured during heating from 5 to 85°C. Hardness was determined by texture profile analysis. Acid-base buffering was performed to observe changes in the indigenous insoluble (colloidal) calcium phosphate (CCP). Moisture content decreased with increasing HS concentration. Cheeses incubated in high concentrations of SCN− softened earlier (i.e., loss tangent=1) compared with other HS treatments. Higher melting temperature values were observed for cheeses incubated in high concentrations of SO42−. Hardness decreased in cheeses incubated in buffers with high concentrations of SCN−. The indigenous CCP profile of nonfat cheese was not greatly affected by incubation in Cl− or SCN−, whereas buffers with high concentrations of SO42− reduced the acid-base buffering contributed by CCP. The use of high concentrations (1.0M) of SCN− for incubation of cheeses resulted in a softer protein matrix at high temperatures due to the chaotropic effect of SCN−, which weakened hydrophobic interactions between CN. Cheese samples incubated in 1.0M SO42− buffers exhibited a stiffer protein matrix at high temperatures due to the kosmotropic effect of SO42−, which helped to strengthen hydrophobic interactions in the proteins during the heating step. This study showed that HS influenced the texture and rheology of nonfat cheese probably by altering the strength of hydrophobic interactions between CN.

Ion-pairing dynamics of Li+ and SCN− in dimethylformamide solution: Chemical exchange two-dimensional infrared spectroscopy

Ultrafast two-dimensional infrared (2DIR) spectroscopy has been proven to be an exceptionally useful method to study chemical exchange processes between different vibrational chromophores under thermal equilibria. Here, we present experimental results on the thermal equilibrium ion pairing dynamics of Li(+) and SCN(-) ions in N,N-dimethylformamide. Li(+) and SCN(-) ions can form a contact ion pair (CIP). Varying the relative concentration of Li(+) in solution, we could control the equilibrium CIP and free SCN(-) concentrations. Since the CN stretch frequency of Li-SCN CIP is blue-shifted by about 16 cm(-1) from that of free SCN(-) ion, the CN stretch IR spectrum is a doublet. The temperature-dependent IR absorption spectra reveal that the CIP formation is an endothermic (0.57 kJ∕mol) process and the CIP state has larger entropy by 3.12 J∕(K mol) than the free ion states. Since the two ionic configurations are spectrally distinguishable, this salt solution is ideally suited for nonlinear IR spectroscopic investigations to study ion pair association and dissociation dynamics. Using polarization-controlled IR pump-probe methods, we first measured the lifetimes and orientational relaxation times of these two forms of ionic configurations. The vibrational population relaxation times of both the free ion and CIP are about 32 ps. However, the orientational relaxation time of the CIP, which is ∼47 ps, is significantly longer than that of the free SCN(-), which is ∼7.7 ps. This clearly indicates that the effective moment of inertia of the CIP is much larger than that of the free SCN(-). Then, using chemical exchange 2DIR spectroscopy and analyzing the diagonal peak and cross-peak amplitude changes with increasing the waiting time, we determined the contact ion pair association and dissociation time constants that are found to be 165 and 190 ps, respectively. The results presented and discussed in this paper are believed to be important, not only because the ion-pairing dynamics is one of the most fundamental physical chemistry problems but also because such molecular ion-ion interactions are of critical importance in understanding Hofmeister effects on protein stability.

Colorimetric and Atomic Absorption Spectrometric Determination of Mucolytic Drug Ambroxol Through Ion-Pair Formation with Iron and Thiocyanate

Colorimetric and atomic absorption spectrometric methods have been developed for the determination of mucolytic drug Ambroxol. These procedures depend upon the reaction of iron(III) metal ion with the drug in the presence of thiocyanate ion to form stable ion-pair complex which extractable chloroform. The red-coloured complex was determined either colorimetrically at 510 nm or by indirect atomic absorption spectrometry (AAS) via the determination of the iron content in the formed complex. The optimum experimental conditions for pH, concentrations of Fe(3+) and SCN(-), shaking time, phase ratio, and the number of extractions were determined. Under the proposed conditions, linearity was obeyed in the concentration ranges 4.1x10(-6) - 5.7x10(-5) M (1.7-23.6 µg mL(-1)) using both methods, with detection limits of 4.6x10(-7) M (0.19 µg mL(-1)) for colorimetry and 1.1x10(-6) M (0.46 µg mL(-1)) for AAS. The proposed methods were applied for the determination of Ambroxol in tablet dosage forms. The results obtained were statistically analyzed and compared with those obtained by applying the high-performance liquid chromatographic method with diode-array detection.

Hypertonic saline increases lung epithelial lining fluid glutathione and thiocyanate: two protective CFTR-dependent thiols against oxidative injury

BackgroundCystic fibrosis is a debilitating lung disease due to mutations in the cystic fibrosis transmembrane conductance regulator protein (CFTR) and is associated with chronic infections resulting in elevated myeloperoxidase activity and generation of hypochlorous acid (HOCl). CFTR mutations lead to decreased levels of glutathione (GSH) and thiocyanate (SCN) in the epithelial lining fluid (ELF). Hypertonic saline is used to improve lung function however the mechanism is uncertain.MethodsIn the present study, the effect of GSH and SCN on HOCl-mediated cell injury and their changes in the ELF after hypertonic saline nebulization in wild type (WT) and CFTR KO mice was examined. CFTR sufficient and deficient lung cells were assessed for GSH, SCN and corresponding sensitivity towards HOCl-mediated injury, in vitro.ResultsCFTR (-) cells had lower extracellular levels of both GSH and SCN and were more sensitive to HOCl-mediated injury. In vivo, hypertonic saline increased ELF GSH in the WT and to a lesser extent in the CFTR KO mice but only SCN in the WT ELF. Finally, potential protective effects of GSH and SCN at concentrations found in the ELF against HOCl toxicity were examined in vitro.ConclusionsWhile the concentrations of GSH and SCN associated with the WT ELF protect against HOCl toxicity, those found in the CFTR KO mice were less sufficient to inhibit cell injury. These data suggests that CFTR has important roles in exporting GSH and SCN which are protective against oxidants and that hypertonic saline treatment may have beneficial effects by increasing their levels in the lung.

The myeloperoxidase-derived oxidant HOSCN inhibits protein tyrosine phosphatases and modulates cell signalling via the mitogen-activated protein kinase (MAPK) pathway in macrophages

MPO (myeloperoxidase) catalyses the oxidation of chloride, bromide and thiocyanate by hydrogen peroxide to HOCl (hypochlorous acid), HOBr (hypobromous acid) and HOSCN (hypothiocyanous acid) respectively. Specificity constants indicate that SCN− is a major substrate for MPO. HOSCN is also a major oxidant generated by other peroxidases including salivary, gastric and eosinophil peroxidases. While HOCl and HOBr are powerful oxidizing agents, HOSCN is a less reactive, but more specific, oxidant which targets thiols and especially low pKa species. In the present study we show that HOSCN targets cysteine residues present in PTPs (protein tyrosine phosphatases) with this resulting in a loss of PTP activity for the isolated enzyme, in cell lysates and intact J774A.1 macrophage-like cells. Inhibition also occurs with MPO-generated HOCl and HOBr, but is more marked with MPO-generated HOSCN, particularly at longer incubation times. This inhibition is reversed by dithiothreitol, particularly at early time points, consistent with the reversible oxidation of the active site cysteine residue to give either a cysteine–SCN adduct or a sulfenic acid. Inhibition of PTP activity is associated with increased phosphorylation of p38a and ERK2 (extracellular-signal-regulated kinase 2) as detected by Western blot analysis and phosphoprotein arrays, and results in altered MAPK (mitogen-activated protein kinase) signalling. These data indicate that the highly selective targeting of some protein thiols by HOSCN can result in perturbation of cellular phosphorylation and altered cell signalling. These changes occur with (patho)physiological concentrations of SCN− ions, and implicate HOSCN as an important mediator of inflammation-induced oxidative damage, particularly in smokers who have elevated plasma levels of SCN−.

The Myeloperoxidase-derived Oxidant HOSCN Inhibits Protein Tyrosine Phosphatases and Modulates Cell Signalling via the Mitogen-activated Protein Kinase (MAPK) Pathway in Macrophages

MPO (myeloperoxidase) catalyses the oxidation of chloride, bromide and thiocyanate by hydrogen peroxide to HOCl (hypochlorous acid), HOBr (hypobromous acid) and HOSCN (hypothiocyanous acid) respectively. Specificity constants indicate that SCN− is a major substrate for MPO. HOSCN is also a major oxidant generated by other peroxidases including salivary, gastric and eosinophil peroxidases. While HOCl and HOBr are powerful oxidizing agents, HOSCN is a less reactive, but more specific, oxidant which targets thiols and especially low pKa species. In the present study we show that HOSCN targets cysteine residues present in PTPs (protein tyrosine phosphatases) with this resulting in a loss of PTP activity for the isolated enzyme, in cell lysates and intact J774A.1 macrophage-like cells. Inhibition also occurs with MPO-generated HOCl and HOBr, but is more marked with MPO-generated HOSCN, particularly at longer incubation times. This inhibition is reversed by dithiothreitol, particularly at early time points, consistent with the reversible oxidation of the active site cysteine residue to give either a cysteine–SCN adduct or a sulfenic acid. Inhibition of PTP activity is associated with increased phosphorylation of p38a and ERK2 (extracellular-signal-regulated kinase 2) as detected by Western blot analysis and phosphoprotein arrays, and results in altered MAPK (mitogen-activated protein kinase) signalling. These data indicate that the highly selective targeting of some protein thiols by HOSCN can result in perturbation of cellular phosphorylation and altered cell signalling. These changes occur with (patho)physiological concentrations of SCN− ions, and implicate HOSCN as an important mediator of inflammation-induced oxidative damage, particularly in smokers who have elevated plasma levels of SCN−.

Nitration of the salivary component 4‐hydroxyphenylacetic acid in the human oral cavity: enhancement of nitration under acidic conditions

4-Hydroxyphenylacetic acid (HPA) and nitrite are present in human mixed whole saliva, and HPA can be nitrated by peroxidase/hydrogen peroxide (H(2)O(2))/nitrite systems in the oral cavity. Thus, the objectives of the present study were to estimate the concentrations of HPA, nitrated HPA [4-hydroxy-3-nitrophenylacetic acid (NO(2)HPA)], nitrite, and thiocyanate (SCN(-)) in saliva from 73 patients with periodontal diseases and to elucidate the conditions necessary to induce nitration of HPA. High concentrations of HPA, nitrite, and SCN(-) were found in the saliva of patients older than 50 yr of age. NO(2)HPA was detected in seven patients who were older than 60 yr of age. Nitrite-dependent formation of NO(2)HPA by a bacterial fraction prepared from mixed whole saliva was faster at pH 5.3 than at pH 7, and increased as the rate of H(2)O(2) formation increased. The formation of NO(2)HPA was inhibited by SCN(-) and by salivary antioxidants such as uric acid, ascorbic acid, and glutathione. These results suggest that nitration can proceed at an acidic site in the oral cavity where H(2)O(2) is produced under conditions of decreased concentrations of SCN(-) and of antioxidants.

Hypothiocyanous acid reactivity with low-molecular-mass and protein thiols: absolute rate constants and assessment of biological relevance

MPO (myeloperoxidase) catalyses the oxidation of chloride, bromide and thiocyanate by H(2)O(2) to HOCl (hypochlorous acid), HOBr (hypobromous acid) and HOSCN (hypothiocyanous acid, also know as cyanosulfenic acid) respectively. Specificity constants indicate that thiocyanate, SCN-, is a major substrate for MPO. HOSCN is also a major oxidant generated by other peroxidases including salivary, gastric and eosinophil peroxidases. Whereas HOCl and HOBr are powerful oxidizing agents, HOSCN appears to be a less reactive, but more thiol-specific oxidant. Although it is established that HOSCN selectively targets thiols, absolute kinetic data for the reactions of thiols with HOSCN are absent from the literature. This study shows for the first time that the reactions of HOSCN with low-molecular-mass thiol residues occur with rate constants in the range from 7.3 x 10(3) M(-1).s(-1) (for N-acetyl-cysteine at pH 7.4) to 7.7 x 10(6) M(-1).s(-1) (for 5-thio-2-nitrobenzoic acid at pH 6.0). An inverse relationship between the rate of reaction and the pKa of the thiol group was observed. The rates of reaction of HOSCN with thiol-containing proteins were also investigated for four proteins (creatine kinase, BSA, beta-lactoglobulin and beta-L-crystallins). The values obtained for cysteine residues on these proteins are in the range 1 x 10(4)- 7 x 10(4) M(-1).s(-1). These second-order rate constants indicate that HOSCN is a major mediator of thiol oxidation in biological systems exposed to peroxidase/H(2)O(2) systems at (patho)physiological concentrations of halide and SCN- ions, and that HOSCN may play an important role in inflammation-induced oxidative damage.

Iodine deficiency in children 7–19 years old in Eastern Province of Cameroon

To determine the prevalence of iodine deficiency in children in Eastern Province, Cameroon. Urinary iodine (I) and thiocyanate (SCN) excretion levels were assessed in 158 children (62 boys and 96 girls) aged 7-19 years. Mean urinary iodine excretion was 4.49 microg/dl for girls and 4.71 microg/dl for boys, lower than the 5.0 microg/dl minimal value defined by WHO. Overall 64.42% of subjects had urinary iodine excretion below the minimum, more than three times the population percentage (20%) at which a zone is declared endemic. Mean urine SCN concentration and mean I/SCN ratios of the study population were 2.57 +/- 1.43 mg/dl and 2.21 +/- 1.35 microg/mg for boys and 2.91 +/- 1.57 mg/dl and 1.91 +/- 1.1 microg/mg for girls. Iodine deficiency remains a problem in Eastern Province of Cameroon.

Ionic Thiocyanate (SCN−) Production, Fate, and Phytotoxicity in Soil Amended with Brassicaceae Seed Meals

Brassicaceae seed meals produce ionic thiocyanate (SCN (-)), a bioherbicidal compound. This study determined the fate of SCN (-) in a field soil amended with seed meals of Sinapis alba, Brassica juncea, and Brassica napus and quantified crop phytotoxicity by monitoring carrot ( Daucus carota) emergence. Meals were applied at 1 or 2 t ha (-1), and soils were sampled to 35 cm for SCN (-). Maximum SCN (-) (211 micromol kg (-1) of soil) was measured at 5 days in 0-5 cm samples from plots amended with S. alba meal at 2 t ha (-1). Less than 30 micromol of SCN (-) kg (-1) of soil was measured at soil depths below 15 cm. At 44 days, SCN (-) was <15 micromol kg (-1) of soil in all treatments. Emergence inhibition of carrots seeded 15-36 days after meal amendment was found only in S. alba treatments. The rapid decrease of SCN (-) concentrations in Brassicaceae meal-amended soil indicates limited potential for off-site environmental impacts.

Alternative strategies for activation of the natural lactoperoxidase system in cows' milk: trials in Tanzania

Thiocyanate content and lactoperoxidase activity of individual cow's milk of different breeds were determined, and the effects of different lactoperoxidase system (LP-s) activation strategies were compared. Lactoperoxidase activity varied significantly between Friesian and both Ayrshire and Tanzania Short Horn Zebu (TSHZ), but differences between Ayrshire and TSHZ were not significant. There was no significant variation in SCN- content between breeds. The LP-s was activated using three strategies based on SCN-: namely; equal concentrations of SCN- and H2O2 (7:7, 10:10, 15:15 mg/l), excess SCN- concentrations (15:10, 20:10, 25:10 mg SCN-:H2O2/l), and excess H2O2 concentrations (10:15, 10:20, 10:25 mg SCN-:H2O2/l), plus a fourth strategy based on I- (15:15 mg I-:H2O2/l). The keeping quality (KQ) was assessed using pH, titratable acidity, clot on boiling and alcohol stability tests. All activation strategies enhanced the shelf life of milk (typically increasing KQ from around 10 to around 20 h), but it was clear that the effectiveness of the LP-s depends on the type and concentrations of the activators of the system. The LP-s activated using I- as an electron donor was more effective than the LP-s activated using SCN- as an electron donor, increasing the KQ by a further 6-8 h compared with SCN-.

Some properties of a sequencing batch reactor for treatment of wastewater containing thiocyanate compounds

Thiocyanate (SCN) compounds in photo-processing wastewater (PPWW) could be treated by an SBR system without any release of thiocyanate to the atmosphere during the aeration step. An SCN loading greater than 84 g m −3 d −1 showed negative effects on the growth of bio-sludge and removal efficiencies of the system. The acclimatization period of the system was increased with an increase in SCN concentration or loading. The COD, BOD 5, TKN, and SCN removal efficiencies were 96.0±1.6%, 72±2%, 49±5%, and 82±3%, respectively, under an SCN loading of up to 84 g m −3 d −1. The removal efficiency of the system was repressed by SCN due to the repressed growth rate of nitrification bacteria. However, the removal efficiency could be increased with an increase in HRT or a decrease in SCN loading. Also, increases in HRT or decreases in SCN loading led to increased sludge age or solid retention time (SRT) and decreased the sludge volume index (SVI) value. The SRT and SVI of the system with synthetic wastewater containing 840 mg l −1 SCN under an HRT of 3 days (SCN loading of 280 g m −3 d −1) were 3.9±0.7 days and 65±4 ml g −1, respectively, while they were 11.2±0.8 days and 55±6 ml g −1, respectively under an HRT of 10 days (SCN loading of 84 g m −3 d −1).