Addition Of MgSO Research Articles

A comparative study between the addition of MgSO4against dexamethasone to bupivacaine in the prolongation of ultrasound-guided interscalene nerve block for shoulder arthroscopy

Background Local anesthetic adjuvants have been studied previously to prolong the duration of analgesia after peripheral nerve block and thus reduce postoperative adverse reactions associated with excessive systemic analgesic intake. The aim of this study was to compare the addition of MgSO 4 against dexamethasone to bupivacaine in the prolongation of ultrasound-guided interscalene brachial plexus block (ISPB) for shoulder arthroscopy. Patients and methods A total of 63 patients, ASA I and II grades, undergoing arthroscopic rotator cuff repair were enrolled in this study. The ISPB was performed with 0.5% bupivacaine 20 ml plus either 5 ml of 10% MgSO 4 (group M) or 5 ml of normal saline containing dexamethasone 8 mg (group D) or 5 ml of 0.9% NaCl (group C). The following data were collected: the onset of sensory block, the analgesic duration (time of the first call for analgesics), the occurrence of satisfactory motor block, the motor block duration, and postoperative analgesic consumption. Results The magnesium sulfate group and the dexamethasone group patients showed significantly higher analgesic duration values and significantly lower total meperidine consumption values than control group patients. Conclusion The addition of either magnesium sulfate or dexamethasone to bupivacaine in ISPB prolongs the analgesic duration significantly and also decreases the postoperative analgesic consumption.

A mechanism by which the osmotic laxative magnesium sulphate increases the intestinal aquaporin 3 expression in HT-29 cells

Aims We have suggested that an osmotic laxative, magnesium sulphate (MgSO 4), may act as a cathartic in a very rational manner by increasing the aquaporin 3 (AQP3) expression level and by changing osmotic pressure in the colon. In this study, we examined the mechanism by which MgSO 4 increases the intestinal AQP3 expression level by using the human colon cancer HT-29 cell line. Main methods After the addition of MgSO 4 to HT-29 cells, the expression levels of AQP3 mRNA and protein were measured using real-time RT-PCR and western blotting, respectively. The intracellular Mg 2+ concentration, adenylate cyclase (AC) activity and protein kinase A (PKA) activity were also determined. The phosphorylated cAMP response element-binding protein (CREB) expression levels were determined by western blotting. Key findings The AQP3 mRNA expression level started to increase significantly at 1 h after MgSO 4 addition and peaked at 9 h, at a level 3 times as high as the control levels. The AQP3 protein expression level started to increase 6 h after the addition and reached a level almost twice as high as the control levels by hour 12. In the HT-29 cells treated with MgSO 4, there was a 1.4-fold increase in the intracellular Mg 2+ concentration, a 1.5-fold increase in AC activity, a 1.6-fold increase in PKA activity, and a significant increase in phosphorylation of the CREB. Significance These results suggest that the AC activation caused by an increase in the intracellular Mg 2+ concentration may trigger CREB phosphorylation through PKA activation and promote AQP3 gene transcription.

Yields of H 2S and gaseous hydrocarbons in gold tube experiments simulating thermochemical sulfate reduction reactions between MgSO 4 and petroleum fractions

The aim of this work was to assess the ability of four representative fractions (saturated, aromatic, polar and asphaltene) of crude oils to participate in thermochemical sulfate reduction (TSR) and thus to evaluate their pyrolysis behaviors, which is of great relevance to the stability of reservoir hydrocarbons. Experiments simulating reactions between oil fractions and magnesium sulfates (anhydrous MgSO 4 and hydrated MgSO 4·7H 2O) at a constant temperature of 420 °C and under a pressure of 50 MPa were conducted over a period of 24 h using a gold tube confined system. The yields of non-hydrocarbon and hydrocarbon gases and their δ 13C values were measured and compared in order to reveal the main control factors on TSR under practical geological conditions. In pure blank pyrolysis experiments with oil fractions cracking without TSR, different pyrolysis rates were seen for the four petroleum fractions with a sequence of saturated > asphaltene > polar ≫ aromatic. Minimal yields of C 1–C 5 hydrocarbons in the aromatic fraction can mainly be attributed to the greater thermal stability of aromatic compounds, which was also reflected by their positive δ 13C signatures. Upon addition of anhydrous MgSO 4 to the saturated fraction, a small quantity of H 2S was generated, indicating that only a weak TSR occurred in this series. Upon addition of hydrated MgSO 4·7H 2O to the four petroleum fractions, high yields of H 2S were generated, indicating that water plays an important role in the occurrence of TSR. The presence of nitrogen and/or oxygen containing heteroatomic compounds in the polar fraction decreases the yields of H 2S when subjected to MgSO 4 TSR. Similar yields of H 2S from the saturated, aromatic and asphaltene fractions revealed that TSR occurring in the aromatic fractions is unlikely to be associated with the opening of benzene rings but closely related to availability of hydrogen atom in the alkyl moiety. The addition of MgSO 4·7H 2O, TSR can significantly enhance the yield of methane, also reflected in an increase in its δ 13C value. Besides methane, the other gaseous hydrocarbons (C 2, C 3) in the MgSO 4·7H 2O series also showed some less negative δ 13C values relative to the blank series, irrespective of the fraction type. Relative to the other fractions (saturated, polar and asphaltene), low yields of C 1–C 5 gaseous hydrocarbons derived from the aromatic fraction could be attributed to the greater stability of the benzene ring and indicate that paraffinic oils may be more susceptible to thermal or thermochemical alterations than aromatic oils under the conditions of real subsurface reservoirs.

Enhanced absorption process of NO 2 in CaSO 3 slurry by the addition of MgSO 4

In this study, CaSO 3, the by-product of flue gas desulfurization (FGD) process, was used as an absorbent for NO 2 absorption. As the CaSO 3 content exceeded 0.1 mol L −1, the absorption efficiency of NO 2 could reach more than 70%. Three types of additives, MgSO 4, Na 2SO 4 and MgCl 2, were also investigated for the enhancement of NO 2 absorption, and it was found that MgSO 4 was the most effective. When MgSO 4 was added, the NO 2 absorption efficiency could increase significantly from 70.8% to 86.0%, and the oxidation rate of CaSO 3 became around 10 times higher than that of additive free condition. Furthermore, the addition of MgSO 4 would also lead to the raise in the ratio of NO 2 − to the total NO 2 absorption products. All these aspects could be ascribed to the increment of the capacity of dissolved sulfite species (CDSS) which resulted from the combined effects of SO 4 2− and Mg 2+. Firstly, SO 4 2− would react with Ca 2+ and promote the dissolution of CaSO 3, resulting in the increase of CDSS. And then the neutral MgSO 3 0 ion pair would form in the absorbent slurry, which could play the same role as dissociated SO 3 2− in the NO 2 absorption.

Possible therapeutic effect of magnesium sulfate in pre-eclampsia by the down-regulation of placental tumor necrosis factor-alpha secretion

To examine the effect of magnesium sulfate (MgSO(4)) on tumor necrosis factor-alpha (TNF-alpha) secretion by preeclamptic placentas. Cotyledons of six, term, normotensive and ten, pre-eclamptic placentas were dually perfused for six hours (6h), with MgSO(4) (6-7 mg %) in the maternal reservoir [normotensive (n = 3); pre-eclamptic (n = 5)], and with control medium (without MgSO(4)) [normotensive (n = 3); pre-eclamptic (n = 5)]. Perfusate samples from the maternal and the fetal circulations were collected every 30 min throughout the 6h of perfusion, and examined for TNF- alpha levels using ELISA. Statistical significance was determined using a 2-way analysis of variance. Pre-eclamptic placentas perfused with control medium (without MgSO(4)) secreted higher levels of TNF-alpha into the fetal and the maternal circulations (1.60 +/- 0.59 pg/mL/g of cotyledon and 14.28 +/- 2.69 pg/mL/g of cotyledon, respectively), as compared to the fetal and maternal circulations of normotensive placentas (0.25 +/- 0.09 pg/mL/g of cotyledon and 6.73 +/- 1.11 pg/mL/g of cotyledon, respectively) (p < 0.01). Addition of MgSO(4) to normotensive placentas did not affect TNF-alpha levels in the fetal or maternal circulations. However, exposure of pre-eclamptic placentas to MgSO(4) significantly decreased TNF-alpha levels in both the fetal (0.89 +/- 0.09 pg/mL/g of cotyledon versus 1.6 +/- 0.59 pg/mL/g of cotyledon; p < 0.05) and the maternal circulations (4.74 +/- 2.78 pg/mL/g of cotyledon versus 14.28 +/- 2.69 pg/mL/g of cotyledon; p < 0.01). Down-regulation of placental TNF-alpha secretion by MgSO(4) in pre-eclampsia might indicate a possible therapeutic effect for this agent in reducing maternal, endothelial dysfunction and in improving neonatal outcome in pre-eclampsia, by reducing TNF-alpha levels in maternal and fetal circulations.

Mechanism and Consequences of Anaerobic Respiration of Cobalt byShewanella oneidensisStrain MR-1

Bacteria from the genus Shewanella are the most diverse respiratory organisms studied to date and can utilize a variety of metals and metal(loid)s as terminal electron acceptors. These bacteria can potentially be used in bioremediation applications since the redox state of metals often influences both solubility and toxicity. Understanding molecular mechanisms by which metal transformations occur and the consequences of by-products that may be toxic to the organism and thus inhibitory to the overall process is significant to future applications for bioremediation. Here, we examine the ability of Shewanella oneidensis to catalyze the reduction of chelated cobalt. We describe an unexpected ramification of [Co(III)-EDTA](-) reduction by S. oneidensis: the formation of a toxic by-product. We found that [Co(II)-EDTA](2-), the product of [Co(III)-EDTA](-) respiration, inhibited the growth of S. oneidensis strain MR-1 and that this toxicity was partially abolished by the addition of MgSO(4). We demonstrate that [Co(III)-EDTA](-) reduction by S. oneidensis requires the Mtr extracellular respiratory pathway and associated pathways required to develop functional Mtr enzymes (the c-type cytochrome maturation pathway) and ensure proper localization (type II secretion). The Mtr pathway is known to be required for a variety of substrates, including some chelated and insoluble metals and organic compounds. Understanding the full substrate range for the Mtr pathway is crucial for developing S. oneidensis strains as a tool for bioremediation.

Bench-scale recovery of phosphorus from flushed dairy manure wastewater

Recovery of phosphorus (P) from flushed dairy manure in an easily-dewatered form would enable farmers to manage P as a resource rather than land-apply it in excess at environmental risk. The purpose of this study was to evaluate (i) the feasibility of P recovery and (ii) the form of recovered P from flushed dairy manure wastewater using crystallization in a fluidized-bed reactor. Wastewater was pumped directly from a dairy farm reservoir and continuously fed in parallel through four bench-scale fluidized-bed reactors deployed on-site. Chemical additives (NaOH and MgSO 4) required for recovery were injected directly into the zone of fluidization. Recovered P forms were assessed by X-ray diffraction, scanning electron microscopy, and micro-elemental analysis. Recovery of P as poorly-crystalline hydroxylapatite (HAP) was documented in coatings ultrasonically removed from quartz seed grains following fluidization at elevated pH in conjunction with MgSO 4 injection. Addition of MgSO 4 was required to prevent CaCO 3 precipitation upon pH elevation and hence enable calcium phosphate precipitation. It is likely that MgSO 4 inhibited CaCO 3 via formation of MgCO 3 (aq). Periclase (MgO), which also served as an effective seed material, generated sufficient alkalinity at grain surfaces to precipitate abundant CaCO 3 and in some cases detectable Ca phosphate even without NaOH addition to elevate pH of bulk solution.

Magnesium Sulfate Diminishes the Effects of Amide Local Anesthetics in Rat Sciatic-Nerve Block

Magnesium sulfate (MgSO(4)) is well known as an antagonist of N-methyl-d-aspartate receptors and was used for intrathecal analgesia a century ago. However, the effects of MgSO(4) combined with local anesthetics (LAs) on peripheral nerves are unclear. We tested the hypothesis that MgSO(4) could be used as an adjuvant to prolong and intensify conduction block by amide-type LAs in a rat sciatic-nerve block model. Further, the mechanism of possible synergy between LAs and MgSO(4) was investigated in whole-cell mode patch-clamp experiments. Sciatic nerves were exposed to 2%/73.9 mM lidocaine, 0.25%/7.7 mM bupivacaine, and 0.5%/15.4 mM ropivacaine, with or without addition of 1.25%, 2.5%, or 5% MgSO(4)/50.7 mM, and nerve block characteristics were assessed. To elucidate the LA-MgSO(4) interaction, voltage-dependent inactivation curves were determined in cultured rat GH(3) cells that expressed neuronal Na(+) channels. Unexpectedly, the addition of MgSO(4) overall significantly shortened the duration of block by lidocaine, bupivacaine, and ropivacaine. The steady-state inactivation of Na(+) channels in the presence of 300 muM lidocaine was almost unchanged by the addition of 10 mM MgSO(4), indicating that MgSO(4) does not affect the potency of lidocaine toward the inactivated Na(+) channel. MgSO(4) coadministered with amide-type LAs shortened the duration of sciatic-nerve block in rats. Therefore, it does not seem to be useful as an adjuvant for peripheral-nerve block. The mechanism of this observed antagonism is unclear but appears to be independent of the action of LAs and MgSO(4) at the LA receptor within the Na(+) channel.

Comparison of effectiveness of different ashing auxiliaries for determination of phosphorus in natural waters, aquatic organisms and sediments by ignition method

An improved method for the determination of phosphorus in natural waters, aquatic organisms and sediments by ignition method is proposed. The recoveries of phosphorus (P) from selected inorganic and organic P-containing compound standards after ignition with different auxiliaries, such as MgSO 4, Mg(NO 3) 2, MgCl 2, Mg(Ac) 2 and CaCl 2, were compared. We found that the phosphorus from most compound standards could not be completely recovered when these compounds were ignited (450–500°C) with the MgSO 4 as auxiliary and the baked residue was extracted with 0.2 mol l −1 HCl for 30 min at 80°C or at room temperature. P recoveries, for example, were poor, less than 85%, if pyrophosphate and metaphosphate were ignited with the addition of MgSO 4 prior to the extraction of the baked residue with 0.2 mol l −1 HCl at 80°C for 30 min. In contrast, MgCl 2, Mg(Ac) 2 and CaCl 2, as well as Mg(NO 3) 2, could all yield complete P recoveries at routine ashing temperatures (450–500°C). The results demonstrate that MgCl 2 is a more effective auxiliary agent for the determination of phosphorus in natural waters, aquatic organisms and sediments by ignition method than MgSO 4 which is commonly used.

Involvement of N-methyl- D-aspartate receptors for the Ptychodiscus brevis toxin-induced depression of monosynaptic and polysynaptic reflexes in neonatal rat spinal cord in vitro

The effects of Ptychodiscus brevis toxin (PbTx) on the Ia-α motoneuron synaptic transmission in neonatal rat spinal cord in vitro was examined. The stimulation of a dorsal root evoked monosynaptic (MSR) and polysynaptic reflex (PSR) potentials in the segmental ventral root in Mg 2+-free medium. Superfusion with PbTx (2.8–84 μM) depressed the MSR and the PSR in a concentration-dependent manner. At 2.8 μM of PbTx, the depression of MSR and PSR was 24±8.3% and 37±9.7%, respectively. The maximal depression was seen at 84 μM of the toxin (78% for MSR and 96% for PSR). The concentration of toxin required to produce 50% depression was 28.3±6.4 μM for MSR and 5.5±1.1 μM for PSR. The PbTx (28 μM) did not alter the magnitude of the dorsal root or the ventral root potentials. Addition of MgSO 4 (1.3 mM) or DL-2-amino-5-phosphonovaleric acid (APV; 10 μM) to the physiological solution abolished the PSR totally and decreased the MSR by about 30%. In both the conditions, the PbTx-induced depression of the MSR was attenuated significantly. The PbTx-induced depression was blocked completely in the presence of APV+6-cyano-7-nitroquinoxaline-2,3-dione (0.1 μM). NMDA (1 μM) by itself did not alter the magnitude of MSR or PSR but enhanced the PbTx-induced depression (28 μM) of PSR significantly. 7-Chlorokynurenic acid (3 μM; glycine B antagonist) did not block the PbTx-induced depression of MSR. D-serine (glycine B agonist) did not reverse the PbTx-induced depression of reflexes although it reversed the 7-chlorokynurenic acid-induced depression of PSR. The results indicate that the PbTx depressed the spinal reflexes without altering the magnitude of dorsal root or ventral root activity. The depression of the PSR involved NMDA receptors while that of the MSR involved NMDA and non-NMDA receptors. The PbTx actions did not involve the glycine B site of the NMDA receptor.

The effect of added salts on the viscoelastic properties of fish skin gelatin

The effects of various salts on the viscoelastic properties of a class A gelatin (obtained by a mild acid pretreatment) from megrim ( Lepidorhombus boscii) skins were examined and compared with their effects on commercial tilapia skin gelatin. Although salts generally extended the setting time of gelatins, it was found that the melting temperature was increased considerably by the addition of MgSO 4, (NH 4) 2SO 4, or NaH 2PO 4. Of all the salts assayed, only MgSO 4 improved the rheological characteristics in suitable conditions of pH and ionic strength, which differed between megrim and tilapia gelatin. Notable differences were found in the amino acid compositions of the two species, especially in the hydroxyproline content.

Efficacy of magnesium sulfate in acute adult asthma: A meta-analysis of randomized trials

The purpose of this article was to review of the literature to determine whether MgSO 14 provides an additive improvement in adults with acute asthma in the emergency department (ED). English-language published and unpublished studies (1968–1998) were retrieved using MEDLINE, SCIENCE CITATION INDEX, CURRENT CONTENTS, bibliographic reviews of primary research, review articles, consultation with experts, and the register of Medical Editors' Trial Amnesty. Meta-analysis of randomized, placebo controlled trials. The five selected trials included 374 patients with acute asthma (mean age 38.3 ± 13.4 years, 30% men, 70% women). The main outcome measure was pulmonary function; admission rate was evaluated as a secondary goal. Individual and pooled effect sizes (ES) were determined for pulmonary function data. Binary outcome (admission rate) was combined and reported as odds ratio (OR). The overall summary ES (95% confidence interval [CI]) of the five trials satisfying all inclusion criteria, weighted by sample size was nonsignificant (ES = 0.02, −0.20 to 0.24, P = .84). This pooled ES was equivalent to 1.7%, 95% CI: −9.8 to 13.1%) greater in pulmonary function the MgSO 4 compared with the control group. On the other hand, four studies addressed the effect of MgSO 4 administration on hospital admissions. Pooled results revealed that MgSO 4 did not decrease significantly admission rates (OR = 0.68, 95% CI: 0.41 to 1.15). The existing evidence reveals that the addition of MgSO 4 to ED patients with moderate to severe asthmatic exacerbations does not alter treatment outcomes. Nevertheless, the number and size of studies being pooled remain small.

Primary nucleation of citric acid monohydrate: influence of selected impurities

An experimental study is presented concerning solubility and primary nucleation kinetics of monohydrate citric acid from pure and selectively impure (KH 2PO 4, MgSO 4·7H 2O and FeSO 4·7H 2O) aqueous solutions. The metastable range of pure solutions is wide, ranging from 6 to 14°C, and the order of primary nucleation, equal to 2.51, is quite low. The addition of the tested impurities, which are usual fermentation aids, at concentrations lower than wt. 1%, produces negligible effects on the solubility and slightly enhances the primary nucleation rate. However, the presence of these compounds modifies the crystal habit at birth: in particular, the addition of MgSO 4·7H 2O and FeSO 4·7H 2O makes these crystals more elongated, but this effect diminishes as the crystals grow.

Fermentation optimization of plantaricin 423, a bacteriocin produced by Lactobacillus plantarum 423

More than 15 bacteriocins of Lactobacillus plantarum have been described. However, little information has been published on the fermentation optimization of these peptides. Plantaricin 423, produced by L. plantarum 423, is produced during exponential growth and reaches a maximum activity [6000 activity units (AU)/ml] at the beginning of stationary growth ( i.e. after 15 h). This activity level is maintained for 3 h, but declines to 2600 AU/ml towards the end of fermentation ( i.e. after 31 h). The increase in plantaricin 423 activity coincided with a decrease in pH from 5.8 to 4.0 during the first 15 h of fermentation. However, when the number of cells are taken into account (OD max-value), a higher concentration of plantaricin 423 is produced in medium with an initial pH of 4.90 (2961 AU/ml/OD max) than at pH 5.80 (2368 AU/ml/OD max). A much lower activity of plantaricin 423 was obtained during the same fermentation period (15 h) when cells were grown in MRS broth (Merck) with an initial pH of 6.9. The production of plantaricin 423 increased from 6000 AU/ml in MRS broth (Merck) to 9600, 12,800 and 19,200 AU/ml when the medium was supplemented with 1.9% (w/v) meat extract (Oxoid), 3.4% (w/v) casaminoacids (Oxoid) or 1.9% (w/v) tryptone (Oxoid), and 1.7% (w/v) bacteriological peptone (Oxoid), respectively. The activity of plantaricin 423 was even further increased with the addition of 1% (w/v) tween 80 to MRS broth (Merck). Low concentrations of MnSO 4·H 2O (0.014%, w/v) stimulated the growth of strain 423 and increased the activity of plantaricin 423. Although the addition of MgSO 4·7H 2O had the same stimulating effect on the growth of strain 423, the activity of plantaricin 423 was not increased.

Production of β-fructofuranosidase by Aspergillus japonicus

A newly isolated strain, TIT-90076, which produces β-fructofuranosidase (FFase, EC 3.2.1.26) with a high transfructosylating activity was identified as Aspergillus japonicus. The optimal conditions for the enzymatic transfructosylating reaction occur at pH 5.0 and 55°C. Sucrose is the best carbon source and yeast extract the best nitrogen source for enzyme production. Addition of MgSO · 7H 2O and K 2HPO 4 shifted the morphology of the fungal growth from filamentous to pellet form; however, these salts did not affect FFase production. Antifoam-289 was the best additive for enzyme production among the polymeric and surfactant additives investigated. A central composite experimental design (CCD) and response surface methodology (RSM) were employed to derive a statistical model for the effects of sucrose and yeast extract on FFase production, and an initial concentration of 26.6% sucrose and 2.6% yeast extract was found to be optimal for the final enzyme production in batch cultures.

Compression of polyethylene glycol chains grafted onto silicon nitride surface as measured by scanning force microscopy

Monomethoxypolyethylene glycol (PEG) with a molecular weight of 2000 Da has been grafted to a silicon nitride surface that has been silanized with 3-aminopropyltriethoxysilane (APS). A scanning force microscope (SFM) was used to measure a force—distance profile between the PEG-modified surface and the unmodified silicon nitride SFM tip. In 0.1 M KNO 3 solution the force increased monotonically with distance, showing no adhesion between the SFM probe and the PEG-modified surface. The monotonically increasing force is interpreted as a steric repulsion force. Increasing solution concentration of MgSO 4 caused the appearance of a weak attractive force between the SFM probe and the PEG-modified surface. The magnitude of the attractive force increased with increasing MgSO 4 solution concentration. The addition of MgSO 4 generated poor solvent conditions for grafted PEG chains and eliminated the steric repulsion force, probably through a collapse of the tethered chains. The interpretation of the MgSO 4 effect on the tethered PEG chains is hindered by the fact that surfaces treated with APS alone caused a cantilever instability at a separation distance of approximately 25 nm. An attractive force at this large separation distance suggested that APS treatment resulted in a surface coating thicker than a monolayer.

The effects of foaming agents, and their interaction with antimony, manganese and magnesium, on zinc electrowinning from synthetic acid sulphate electrolyte

The effects of Dowfroth and Saponin, alone and in various combinations with antimony and with manganese and magnesium sulphates, on zinc deposition current efficiency and on the morphology and orientation of 24 h zinc deposits electrowon at 430 A/m 2 and 35°C from synthetic acid sulphate electrolyte were determined. Both Dowfroth and Saponin decreased the zinc deposition current efficiency and also changed the deposit morphology and orientation. Dowfroth and Saponin had a positive interaction with antimony, such that certain combinations of these reagents maximized the current efficiency and improved the deposit quality. The addition of MnSO 4 to an electrolyte containing 10 mg/l Dowfroth increased the current efficiency for zinc deposition and changed the deposit morphology. The current efficiency was further increased by adding antimony, but the addition of MgSO 4 had no effect. The addition of Saponin to an electrolyte containing optimum concentrations of Dowfroth and antimony lowered the current efficiency; however, this current efficiency decrease was more than offset by adding MnSO 4 to the electrolyte.

A laboratory study of struvite precipitation after anaerobic digestion of piggery wastes

A dilute (0·3% TS) but relatively strong (COD 10 000 mg litre −1) piggery wastewater was used as feed in 1·6-litre laboratory anaerobic digesters. During batch digestion (56 days), NH 3-N increased from 500 to 800 mg litre −1 and PO 4-P from 21 to 30 mg litre −1 while Mg concentrations decreased from 32 to 20 mg litre −1. A continuously fed digester (mean residence time of 64 days) produced similar increases in NH 3-N concentrations and reductions in concentrations of PO 4-P (22 to 10 mg litre −1) and Mg from 32 to 20 mg litre −1. X-ray diffraction of the digester sludge indicated that langbeinite (K 2Mg(SO 4) 3) was precipitated whilst it appeared that very fine crystals of Ca, Mg and PO 4 compounds remained in suspension. The addition of MgSO 4 to the batch supernate raised to a pH of 9 led to a reduction in PO 4-P concentrations from 33 to 7 mg litre −1 and the supernate from the continuous digester at a pH of 9 from 10 to 0·1 mg litre −1. The precipitate formed by this reaction was comprised of struvite (MgNH 4PO 4.6H 2O), apthitatite (K 3Na(SO 4) 2) and thermarite (Na 3SO 4). The reduction of PO 4-P concentrations to less than 1 mg litre −1, a significant water quality criterion in the management of eutrophication, is of importance. The production of struvite as a valuable fertilizer may offset much of the cost of this form of wastewater treatment.

Effect of manganese, magnesium, sodium and potassium sulphates on zinc electrowinning from synthetic acid sulphate electrolytes

The effects of manganese, magnesium, sodium and potassium sulphates on the current efficiency, morphology and orientation of 24 h zinc deposits electrowon at 430 A/m 2 and 35°C from synthetic acid sulphate electrolyte have been determined. Increasing concentrations of MnSO 4 in the electrolyte decreased the current efficiency and increased the size of the zinc platelets; the preferred deposit orientation remained intermediate, but the [112] and [114] components became more prominent. The addition of MgSO 4 to the electrolyte resulted in a slight increase in current efficiency and the deposit orientation changed from intermediate to basal. At 50 g/l MgSO 4 the current efficiency decreased slightly and the deposit orientation changed from basal to [101]. Increasing concentrations of MnSO 4 in the presence of 50 g/l MgSO 4 decreased the current efficiency and changed the deposit orientation from [101] to [112] [114] [102] [103] [101]. The addition of Na 2SO 4 resulted in a small increase in current efficiency. Although the deposit orientation remained intermediate, the zinc grain size was reduced at high Na 2SO 4 concentrations. The current efficiency initially decreased with the addition of K 2SO 4 to the electrolyte, but subsequently increased and reached a maximum value at 5 g/l K 2SO 4. The current efficiency was always less at a given K 2SO 4 concentration than for an equivalent concentration of Na 2SO 4. The presence of K 2SO 4 resulted in a zinc deposit having a vertical orientation that reverted to intermediate when the electrolyte also contained MnSO 4 and MgSO 4.

Influence of the medium on the heat and acid denaturation of IgE

The denaturation of IgE immunoglobulin induced by heating at 56°C or by treatment at low pH is inhibited in the presence of high concentrations of salts or hexoses. Between 50 and 100% of the IgE anaphylactic activity (PCA) of rat and mouse antisera is recovered after heating at 56°C for 1,5 or 5 h, respectively, in 1 M MgSO 4 or 2 M glucose, mannose or fructose. Anaphylactic activity of IgE monoclonal anti-DNP mouse antibody is equally preserved. The specific antigenic determinants of human and rat IgE myeloma proteins are also thermostable in these conditions. The addition of MgSO 4 or glucose protects IgE anaphylactic antibodies against denaturation at pH 2. It is suggested that IgE denaturation is the consequence of interactions between molecules of immunoglobulin and that such interactions are diminished by steric hindrance in a medium containing high concentrationsof ions or hexone molecules.