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Slags, sludges, and dust from steelmaking industries have been probed as adsorbents for Pb(II) removal from synthetic water solutions, and these residues have showed good potential in the treatment of industrial effluents contaminated with this heavy metal. Adsorption and precipitation of Pb(II) have been postulated as the main mechanisms to remove Pb(II) from aqueous solutions by using steelmaking residues. The significant effect of pH on Pb(II) removal has been well studied but few studies explicitly address the effect of chemical and mineralogical composition of steelmaking residues and a better understanding of this key parameter is still needed for full elucidation and optimization of the Pb(II) removal process. In this study, samples obtained from different sections of a dust collector system (BFD) in a steelmaking factory, were used to evaluate the effect of BFD sample’s chemical composition on the removal of Pb(II) from synthetic aqueous solution. BFD samples were characterized to determine their chemical composition, particle size distribution and isoionic point. Equilibrium and transient experiments of Pb(II) removal from aqueous solutions were conducted a 25 °C and initial pH = 5.0. Results showed that CaO and MgO, as well as metallic Fe and FeO had a positive linear effect BDF samples Pb(II) adsorption capacity. Pb(II) removal process may take place by ion exchange with CaO and MgO, and by precipitation on the surface of metallic Fe and FeO. MgO and FeO promoted the Pb(II) removal in lesser extend that CaO and metallic Fe, respectively, because the surface ion exchange with MgO and FeO are less thermodynamic favourable and their lower composition in the sample. Bimolecular ion exchange process between Pb(II) ions and Ca and Fe species was supported by results from equilibrium and transient adsorption studies. Results of this work clearly showed that removal of Pb(II) from aqueous solutions is a strong function of the chemical composition of BFD samples and it provided further insight to promote the valorisation and optimization of steelmaking residues as heavy-metal adsorbents.

The RNA N(6)-methyladenosine (m(6)A) methylation is installed by the METTL3-METTL14 methyltransferase complex. This modification has critical regulatory roles in various biological processes. Here, we report that deletion of Mettl14 dramatically reduces mRNA m(6)A methylation in developing B cells and severely blocks B cell development in mice. Deletion of Mettl14 impairs interleukin-7 (IL-7)-induced pro-B cell proliferation and the large-pre-B-to-small-pre-B transition and causes dramatic abnormalities in gene expression programs important for B cell development. Suppression of a group of transcripts by cytoplasmic m(6)A reader YTHDF2 is critical to the IL-7-induced pro-B cell proliferation. In contrast, the block in the large-pre-B-to-small-pre-B transition is independent of YTHDF1 or YTHDF2 but is associated with a failure to properly upregulate key transcription factors regulating this transition. Our data highlight the important regulatory roles of the RNA m(6)A methylation and its reader proteins in early B cell development.

Plasma-based technology is an alternative to produce universal polymer coatings with the appropriate requirements of robustness and stability for antibacterial applications. Here, we proposed a sequential two-step alternative to synthesize antibacterial polymer coatings. A non-isothermal plasma reactor, operated at atmospheric pressure (Patm) and room temperature (Troom), was used to induce free radical polymerization of 4-vinyl pyridine (4VP) on high-density polyethylene (PE). In a subsequent step, the poly-4VP (P4VP) films were treated with a bromoethane/He gas stream to produce quaternized P4VP (P4VPQ) films. Chemical structure of polymer films was validated by infrared and UV–visible spectroscopy, and morphology was evaluated by optical and atomic force microscopy; scanning electron microscopy was used to determine films thickness, which was then used to estimate the surface charge density. The bactericidal capacity was determined with a standard test by using Escherichia coli. Both types of films had an estimated charge density in the order of 1016 positive charges per cm2; P4VP films removed about 95–99% of bacteria, whereas 4PVPQ films eliminated 100%. The methodology proposed for the synthesis of antibacterial polymer coatings is simpler, faster, and more environmentally friendly than other plasma-based methods; operation at Troom and Patm may also have a significant effect on the economics and the ease of implementation of the process at commercial scale. The suggested approach may facilitate the development of new universal coatings, and operating plasma conditions could be extrapolated for engineering antibacterial coatings in industrial areas where bacterial attachment is of concern.

Oxygenated surface sites on Activated Carbon (AC) exhibit low acid strength but are still useful to catalyze reactions of industrial interest. A series of AC-based acid catalysts was prepared by modifying a basic-character AC with an O 2 plasma using a rotary dielectric barrier discharge reactor, to get further insight of the catalytic potential of the oxygenated acid sites generated by this technique. The O 2 plasma treatment time (t PO2 ) had an important effect on the catalysts morphology and the oxygenated surface sites distribution. The non-isothermal O 2 plasma configuration used to oxidize AC was a suitable alternative to generate strong and weak carboxylic acids sites that were active and selective for the gas phase dehydration of isopropanol to propene, being the weak carboxylic acid sites less active but more stable. A maximum activity (Turnover frequency) was found as a function of t PO2, which was explained in terms of the balance between the density and the strength of oxygenated acid sites. The approach used in this study shows the benefits and limitations of non-isothermal plasma technology to generate oxygenated acid sites on AC-based catalysts.

Copper-palladium bimetallic catalysts supported on TiO2 were developed for the aqueous phase hydrodeoxygenation (HDO) of glycerol. Na-promoted bimetallic catalysts had higher activity than monometallic catalysts while maintaining high 1,2-propanediol (1,2-PDO) selectivity (76–93%) characteristic of Cu catalysts. The best results were obtained with CuPd/TiO2-Na. At 220 °C and 0.7 MPa H2 the initial turnover frequency (TOF based on Cu + Pd sites) was 0.14 s−1; the selectivity to 1,2-PDO reached 85%. Characterization of the samples was performed by H2-temperature programed reduction (H2-TPR), X-ray diffraction and high-resolution electron microscopy (HRTEM) plus selected area electron diffraction (SAED), and their results were consistent with the formation of CuPd alloy nanoparticles with their surface enriched in Cu, hence explaining the high selectivity to 1,2-PDO of the bimetallics. The increased activity of the Pd-Cu bimetallic catalysts stems from the significantly smaller average diameter of the CuPd alloy nanoparticles when compared with the Cu or Pd nanoparticles of the monometallic catalysts. Besides the effect upon the nanoparticle structure, Pd promoted HDO in part by the activation of glycerol aqueous phase reforming to produce H2 at the surface level. Cu was stabilized in the bimetallic samples by the formation of the alloy with Pd and by the presence of Na in the catalyst. As a result, CuPd/TiO2-Na can be reused while maintaining high stable activity and 1,2-PDO selectivity. The HDO reaction proceeds through the formation of 1-hydroxy-2-propanone (acetol), followed by its hydrogenation to form 1,2 PDO. Formation of acetol or an acetol-like surface intermediate presumably occurs on support sites, whereas the hydrogenation to 1,2-PDO occurs on the metal sites. The first step is enhanced when basic sites are added to the support, while the hydrogenation step on Cu sites is improved by raising the H2 pressure and/or by the formation of H2 via reforming on Pd sites.

In this work, the removal of cyanide from aqueous solutions was accomplished by using the synergetic effect of activated carbon and an oxidizing agent. A basic-character coconut shell activated carbon (CAC) was used; experiments were conducted in a semi-batch reactor, at 25 °C, initial pH of 11.5, and using cyanide solutions with initial concentration up to 1200 mg/mL. In particular, the beneficial effect of an oxidizing agent such as air, oxygen or ozone on the removal of cyanide by CAC was evaluated. At the optimum operating conditions found in this study, 1200 mg/mL of cyanide were totally decomposed in about 3 h, by using 1 g of CAC and about 2 mgO3/min. The experimental results were rationalized based on different mechanisms reported in the literature. The findings provide the basis to optimize the removal of cyanide from aqueous solutions in mining or metallurgical effluents by using the synergetic effect of CAC and ozone.

The stability of TiO 2 particles in water was increased through plasma polymerization of acrylic acid (AA) onto the particles surface. The polymerization was carried out directly upon TiO 2 powder by using two radiofrequency (RF) plasma reactors: one inductively coupled and another capacitively coupled. In both cases, a cross-linked polyacrylic acid (PAA) film was formed on TiO 2 particles surface, which was characterized by Energy Dispersive Spectroscopy (EDS), Fourier-transformed infrared spectroscopy, (FTIR), Raman Spectroscopy, and X-ray photoelectron spectroscopy (XPS). The stability of the PAA-coated TiO 2 particles was determined by their precipitation in water. It was found that a moderate plasma treatment effectively improved the stability of PAA-coated TiO 2 particles. At low levels of AA polymerization, the TiO 2 particles surface was not modified enough to improve their stability in water; on the other hand, a high degree of AA polymerization led to the formation of large agglomerates, induced by the PAA film, and these particles were not stable. As expected, the particle size and the Z-potential of the PAA-coated particles determined their stability in water. Under the optimum operating conditions of this study, the treated TiO 2 particles showed stability as good as that of TiO 2 particles modified with a dispersant.

Several attempts have been made to optimize the process and reduce operating costs of the acid leaching of low grade sulphide copper ores. In this study, we conducted acidic leaching of low-grade chalcopyrite by using ferric ion and ozone as oxidants, at 25°C. In particular, we used a Taguchi L9 experimental design (four factors, three levels) to determine the effects of particle size, ferric ion and sulphuric acid concentrations ([Fe+3] and [H2SO4]) and ozone (O3) mass flow rate, on the amount of copper extracted. Statistical analysis showed that [Fe+3] had the greatest effect on the amount of copper extracted followed by particle size and O3 mass flow rate. [H2SO4] had no statistical significance. The highest copper leaching yield was obtained for [Fe+3] = 0.5 M, O3 flow rate = 0.5 g/h, [H2SO4] = 0.1 M and particle size=398 μm. Resume On a fait plusieurs essais d'optimisation du procede et de reduction des couts d'operation de la lixiviation acide de minerais de sulfure de cuivre a faible teneur...

Laboratory experiments were performed to study the growth rate and phosphorus (P) and nitrogen (N) uptakes of eight benthic microalgae species isolated from different sources of pig manure. Cells immobilized in calcium alginate beads were cultured with three replicates for each species. P removal rates obtained for the unicellular self-aggregating benthic species (Palmellopsis gelatinosa, Chlorosarcinopsis sp., and Macrochloris sp.) were markedly higher than those obtained in previous published experiments. N removal rates were highest for Macrochloris sp., Chlorosarcinopsis sp., and Euglena sp. 2 and comparable to the maximum rates obtained by other authors. Our results show an excellent efficiency of autochthonous benthic species for nutrient removal, especially for P, and call attention to their use for wastewater treatment.

We study the anchoring of 4-dimethyl-amino substituted azobenzene dyes doped liquid crystals and the formation of permanent gratings in the nematic liquid crystal 5CB. The increase on the dipolar interaction due to trans-cis isomerization, and the resulting anchoring to the substrate, is not enough to explain the formation of permanent gratings as it is commonly believed. We demonstrate that a strong interaction of the acid group in the 4-dimethylamino-2′-carboxylic acid substituted azo (Methyl Red, MR) dye can occur with the solid substrate through hydrogen bonding intermolecular interaction leading to permanent gratings in methyl red doped liquid crystal cells.

A microkinetic model for methanol decomposition on platinum is presented. The model incorporates competitive decomposition pathways, beginning with both O–H and C–H bond scission in methanol, and uses results from density functional theory (DFT) calculations [Greeley and Mavrikakis, J. Am. Chem. Soc. 124 (2002) 7193, Greeley and Mavrikakis, J. Am. Chem. Soc. 126 (2004) 3910]. Results from reaction kinetics experiments show that the rate of H2 production increases with increasing temperature and methanol concentration in the feed and is only nominally affected by the presence of CO or H2 with methanol. The model, based on the values of binding energies, pre-exponential factors and activation energy barriers derived from first principles calculations, accurately predicts experimental reaction rates and orders. The model also gives insight into the most favorable reaction pathway, the rate-limiting step, the apparent activation energy, coverages, and the effects of pressure. It is found that the pathway beginning with the C–H bond scission (CH3OH→H2COH→HCOH→CO) is dominant compared with the path beginning with O–H bond scission. The cleavage of the first C–H bond in methanol is the rate-controlling step. The surface is highly poisoned by CO, whereas COH appears to be a spectator species.

Laboratory experiments were performed to study the growth rate and phosphorus (P) and nitrogen (N) uptake of two nanoplanktonic algal species, Scenedesmus intermedius Chod. and Nannochloris sp. that were isolated from different sources of pig manure. Experiments were carried out for immobilized and free cell cultures simultaneously, with three replicates for each type of culture. Algal immobilization was prepared in calcium alginate beads. The growth rate (measured as chlorophyll increase per hour) and the P and N uptake rate (measured as P and N increase per hour) were estimated by linearization of the logistic growth and nutrient uptake curves, which allowed us to apply proper statistical comparative analyses. P and N uptake rates for S. intermedius were 0.014 and 0.012 mg P h−1 and 0.022 and 0.009 mg N h−1 for free and immobilized cells. Rates for Nannochloris sp. were 0.006 and 0.009 mg P h−1 and 0.011 and 0.006 mg N h−1 for free and immobilized cells. P and N removal rates obtained in the present study, which used species isolated from wastewater, are markedly higher than rates described in experiments that used commercial species, probably because the former species are better adapted to high nutrient concentrations. Utilizing autochthonous species for wastewater treatment may be a simple method to increase nutrient removal efficiency.

Reaction kinetics data were collected for the conversion of isobutane over H-mordenite and β -zeolite, under conditions where reaction was initiated primarily by addition of isobutylene to the feed and where stable catalyst performance was achieved. We successfully extended our kinetic model, previously developed to describe the conversion of isobutane over USY, to describe the reaction kinetics data of the present study. Catalyst performance for isobutane conversion is controlled primarily by composite activation energies, defined in terms of the energies of transition states relative to gas-phase reactants. The composite activation energies of monomolecular activation steps are lower by about 20–25 kJ mol −1 over H-mordenite and β -zeolite compared to USY. In addition, the composite activation energies for hydride transfer and oligomerization/ β -scission steps are lower by about 20–30 kJ mol −1 over H-mordenite and β -zeolite compared to USY. This result suggests that the same zeolitic interactions responsible for stabilizing the transition states for monomolecular activation are also important for stabilizing the transition states for hydride transfer and oligomerization/ β -scission reactions. Our results also suggest that the heats of adsorption of olefins are more exothermic on H-mordenite and β -zeolite compared to USY, again implying that the same interactions responsible for stabilizing the transition states for monomolecular and bimolecular reactions are also important in stabilizing adsorbed reaction intermediates.

Reaction kinetics analyses were conducted for isobutane and 2-methylhexane conversion over USY zeolite (both calcined and steam-treated) at 773 K, where reaction is initiated by activation of the reactant paraffin. These analyses indicate that increasing the severity of catalyst steam treatment leads to an increase in the composite activation barriers of kinetically significant steps (initiation and hydride transfer), except for the reaction step involving dehydrogenation of the reactant paraffin, which may be enhanced by extraframework aluminum species introduced via steam treatment. We use sensitivity analyses to probe the degrees of rate control for all reaction steps as a function of the extent of conversion, reaction temperature, and size of the reactant molecule. Initiation steps (i.e., monomolecular reactions) have a high degree of rate control for both isobutane and 2-methylhexane at low conversions and high temperature, whereas the degree of rate control for hydride transfer steps becomes more si...

Reaction kinetics studies were conducted for isobutane conversion over a USY zeolite catalyst at a total pressure of 1 atm and for temperatures of 523 and 573 K. The catalyst is inactive for isobutane conversion in the absence of feed olefins at these temperatures; however, a stable catalyst performance was achieved for levels of isobutylene in the feed ranging from approximately 50 to 400 ppm. The rates of production of n -butane, propane, isopentane, propylene, 1-butylene, cis -2-butylene, and trans -2-butylene were measured for the aforementioned temperatures and isobutylene feed concentrations at isobutane inlet concentrations of 20 and 80%. A kinetic model for isobutane conversion over USY zeolite was developed based on the following families of reactions: adsorption/desorption steps, oligomerization/β-scission processes, isomerization steps, hydride transfer processes, and initiation steps. This kinetic model describes the reaction kinetics data collected in the present study of isobutane conversion at low temperatures, and it also describes reaction kinetics data collected at higher temperatures (733–773 K) over a USY zeolite catalyst, where the reaction was initiated by the activation of isobutane.

Microcalorimetric measurements of the adsorption of H2 and C2H4 were carried out at 300 K on a Pt–Zn/X-zeolite catalyst (Pt : Zn atomic ratio equal to 1 : 1). The initial heats of H2 and C2H4 adsorption were equal to 75 and 122 kJ/mol, respectively, and these values are weaker than the values of 90 and 155 kJ/mol typically observed for supported Pt catalysts. Reaction kinetics measurements for isobutane dehydrogenation over the Pt–Zn/X-zeolite catalyst were carried out at temperatures from 673 to 773 K, at isobutane pressures from 0.01 to 0.04 atm, and at hydrogen pressures from 0.1 to 0.7 atm. The catalyst shows high activity and selectivity for dehydrogenation of isobutane to isobutylene. The reaction kinetics can be described with a Horiuti–Polanyi reaction scheme. DFT calculations were carried out for the adsorption of ethylene on slabs of Pt(111), Pt3Zn(111) and PtZn(011). Results from these calculations indicate that addition of Zn to Pt weakens the binding energies of π-bonded ethylene, di-σ-bonded ethylene, and ethylidyne species on atop, bridged, and three-fold Pt sites, respectively. These effects are most significant for the bonding of ethylidyne species, and they are least significant for π-bonded ethylene species. Results from DFT calculations for the adsorption of formaldehyde show that addition of Zn to Pt weakens the di-σ-bonding at Pt–Pt sites; however, this weakening effect of Zn on formaldehyde adsorption is less significant than the effect on ethylene adsorption. Moreover, the preferred location for adsorption of formaldehyde on PtZn(011) is a Pt–Zn site, whereas the preferred location for adsorption of ethylene is a Pt–Pt site. Thus, formaldehyde is adsorbed more strongly by 53 kJ/mol on PtZn(011) compared to the di-σ-adsorption of ethylene, whereas formaldehyde and ethylene adsorb in the di-σ-forms with comparable energies on Pt(111). This preferred adsorption of formaldehyde compared to ethylene on PtZn(011) may be at least partially responsible for the enhanced selectivity of Pt–Zn-based catalysts for hydrogenation of C=O groups compared to C=C bonds in α,β-unsaturated aldehydes.

Microcalorimetric, infrared spectroscopic, and reaction kinetics measurements are combined with quantum-chemical calculations based on density-functional theory to investigate the selective reduction of acetic acid, methyl acetate, and ethyl acetate over silica-supported copper catalysts. Experimental values for initial heats of dissociative adsorption of methyl acetate, ethyl acetate, acetaldehyde, methanol, and ethanol on silica-supported copper are estimated to be 124, 130, 130, 128, and 140 kJ mol−1, respectively. These values are in agreement with adsorption energies predicted from DFT calculations using Cu13 clusters. Experimental values of activation energies for the dissociation of acetic acid, methyl acetate, ethyl acetate, and acetaldehyde on copper are estimated to be 83, 67, 62, and 75 kJ mol−1, respectively. Results from DFT calculations also indicate that the activation energy for dissociation decreases from acetic acid to methyl acetate to ethyl acetate. The rate of reduction of n-alkyl acetates appears to be determined by the dissociative adsorption of these molecules and by the hydrogenation of surface acyl species.

The adsorption isotherms of fluoride from an aqueous solution on plain and aluminum-impregnated activated carbons were measured in this study. The impregnated carbon was prepared by impregnation with an aluminum nitrate solution at a fixed pH, followed by calcination under nitrogen at temperatures above 300°C. The adsorption of fluoride on impregnated carbon was shown to be dependent upon both the pH of the impregnating solution and the temperature of calcination. Impregnated carbon was shown to have a fluoride adsorption capacity of 3 to 5 times that of plain activated carbon.

The cyanide is the main process for the extraction of gold from its ores. This process produces rich cyanide solutions containing gold and silver, and waste cyanide solutions with different metal compounds such as copper, zinc and iron. These elements or compounds can be extracted in the form of high-value compounds as nanoparticles. This work presents some result of the remove and recovery of metallic values from waste cyanide solutions to obtain novel metallic nanoparticles. These materials were obtaining by modified sol-gel method from an industrial cyanide waste solution previously treated by advanced oxidation. This work reports the characterization from the nanoparticles by DRX and SEM-EDX. The results indicate that multimetallic nanoparticles can be obtained from cyanidation effluents.

Reaction kinetics data were collected for isobutane conversion over a series of ultra stable Y (USY) zeolite catalysts with and without rare earth cations and subjected to various extents of dealumination by steaming. We conducted these reaction studies at low temperatures (523-573 K) using isobutane feed streams containing known levels of isobutylene (100-400 ppm) so that the kinetics were controlled by bimolecular hydride transfer and oligomerization/beta-scission processes with little or no participation of monomolecular initiation reactions. These experimental conditions led to stable catalyst performance with the main products of isobutane conversion being propane, n-butane, and isopentane, with smaller amounts of propylene, trans-2-butene, and cis-2-butene. The rates of formation of these products per Brønsted acid site (as counted by pyridine adsorption) depended exponentially on Brønsted acid site density, regardless of whether the catalyst contained rare earth cations. Kinetic modeling showed an exponential dependence of hydride transfer and oligomerization/ beta-scission reaction rates on Brønsted acid site density which translated into composite activation energies for these reactions having a linear relationship with site density. Based on results in the literature from theoretical calculations, we suggest that increasing Brønsted acid site density in zeolite Y leads to larger zeolite elasticity, increased stabilization of cationic transition states, and lower composite activation barriers for hydride transfer and beta-scission steps. The role of rare earth cations, therefore, is to ensure the retention of high Brønsted acid site density under hydrothermal conditions, such as in fluid catalytic cracking (FCC) regenerators, where steam would dealuminate the Y zeolite framework and reduce this site density. It is for this reason that hydride transfer reaction rates are high in the presence of rare earth cations and lead to higher yields of less olefinic gasoline during FCC.

a7PAMspreserve spatio-temporal patternsofnAChRactivationand unlike AChE inhibitors, activate only the a7 nAChR subtype, which should provide a better side effect profile. We have performed detailed characterization of BNC375, a Type I positive allosteric modulatorofa7nAChR.ActionofBNC375ona7nAChRs invitrowas examined in GH4C1 cells stably, expressing rat a7 nAChR. Manual patch-clamp recordings were made with a fast-application add-on (Dynaflow Resolve, Cellectricon, Sweden). A concentration– response curve of a7 nAChR potentiation by BNC375 yielded an EC50 1.9mM, nH 1.62, Emax 1572% for peak current and 1.3mM, 1.60, 2616% for areaunder curve (AUC), respectively. In the presence of 2mM ( EC50) BNC375 the concentration–response of acetylcholine exhibited 10 fold leftward shift (EC50 14.5mM vs. 127.7mM, nH 1.66 vs. 1.76) as well as 246% potentiation of a saturating ACh concentration. BNC375 had a minimal effect on the kinetics of potentiated currents and in contrast to a classical Type II a7 PAM PNU-120596, was not able to re-activate a7 nAChRs after desensitization with 0.5–1 mM ACh. The cognition-enhancing properties of BNC375 were evaluated using reversal of scopolamine-induced memory deficits in the mouse T-maze Continuous Alternation Task (T-CAT) and the rat novel object recognitionmodel (NOR). In the T-CAT, BNC375 at doses from 0.003 to 3 mg/kg p.o. dose-dependently reversed the memory-impairing effect of scopolamine from0.03 mg/kg. In the NOR all three doses (0.1, 0.3, 1 mg/kg p.o.) showed a significant reversal of scopolamine-induced deficits. In summary, we show that BNC375 potently enhances a7 nAChRmediated currents in vitro and has a favourable PAM Type I-like kinetic profile. The compound is efficacious in a broad range of agonist concentrations – from subthreshold to saturating. BNC375 demonstrates cognition-enhancing properties in two different in vivo animal models of episodic and working memory with a broad therapeutic window (100 fold).

In this work, we studied a newly reported class of colossal nonlinear effects observed near the nematic-isotropic temperature transition. We show that the origin of this nonlinearity may be attributed to the onset of critical opalescence. Large diffraction efficiency (23%) and colossal nonlinear refractive index (n2 ≈ 50 cm2/W) has been measured in randomly oriented thin (1 μm) films of 5CB liquid crystals doped with small quantities of the azo dye methyl red (1%wt).

1. Lithium was investigated for its possible use as a marker for identifying the various sources of NaCl in the diet. Micromolar concentrations of lithium can be detected in various vegetables, tap water and also in urine specimens of adult volunteers. The lithium content of vegetables varied from 6.1 to 24.5 μmol of lithium/kg dry weight, with the exception of spinach and aubergines which had much higher concentrations. The excretion of the element in 24 h urine specimens ranged from 2 to 4 μmol of lithium/day. 2. Experiments were performed to assess whether both lithium and sodium would penetrate foods at the same rate during cooking. The rates of penetration into food for both elements were proportional to their concentration in the cooking water despite a sodium/lithium ratio of 50:1. 3. Physiological experiments were conducted to investigate the handling of small doses of lithium by the body. A dose of 250 μmol of lithium was chosen as optimal and given orally to healthy volunteers in either single or continuous aqueous doses of lithium carbonate. The recoveries of oral lithium in urine were 92 ± 5% (sd) and 97 ± 4 (sd) (n = 5) for single and continuous doses respectively. 4. The daily addition of 100 mmol of oral NaCl to the diet of volunteers receiving a standard dose of lithium did not affect urinary lithium excretion rates nor the final recovery of the administerd lithium. 5. These studies suggest that lithium carbonate may be a useful marker for the uptake of NaCl into cooked food; after eating lithium-enriched food the monitoring of urinary lithium output may then be used to quantify the amount of sodium derived from the specific foods.

Statistical analyses suggest that 25-50% of the salt intake of Western populations is derived from the discretionary use of cooking and table salt. Yet direct estimates of discretionary salt use by a lithium technique show that in one community in Britain this source contributed only 15% to total intake. The estimates of discretionary salt use in Finland, the United States, and Britain have been exaggerated because salt losses in cooking water were not considered. Only about a quarter of cooking salt actually enters the consumed food; allowance for this in statistical calculations makes data on dietary intake similar to those assessed from urinary sodium excretion. Daily salt intake in Britain averages about 10.7 g for adult men and 8.0 g for women, figures similar to those from countries in northern Europe. The natural salt content of food provides about 10% intake, the remaining 75% being derived from salt added by manufacturers; drinking water provides a negligible amount. Any programme for reducing the salt consumption of a population should therefore concentrate primarily on a reduction in the salt used during food processing.

1. An epidemiological study was conducted in the market town of March, Cambridgeshire, to assess the quantitative importance of cooking and table salt to total dietary salt intake by the use of a fused mixture of lithium carbonate and sodium chloride. 2. Men and women aged 20–60 participated in a 12 day study with sequential 24 h urine collections to assess salt sources over a 7 day period. 3. Total salt consumption estimated from urinary chloride excretion amounted to 10.6 ± 0.55 (sem) g in 33 men and 7.4 ± 0.29 (sem) g in 50 women. The cooking salt eaten was only 0.45 ± 0.09 (sem) g in men and women, with men eating more table salt (0.77 g/day) than women (0.46 g/day). 4. Discretionary sources, i.e. cooking and table salt use, contributed only 15% to the total intake. Salt from manufacturing foods and catering in purchased food therefore provided on average 85% of total salt intake. These results are consistent even when an allowance is made for the slightly poorer pouring quality of the lithium-tagged salt. 5. The importance of food as a source of salt was reflected in the significant relationship between the weight of the individual and the amount of salt eaten (for males P < 0.05 and for females P < 0.001). 6. Cooking salt consumption did not relate to the amount of salt derived from purchased food nor did table salt use relate to the amount of salt in cooked foods. 7. Husbands and wives showed a high correlation in their salt use but the husbands had higher intakes of salt from purchased food and from cooking salt. They also used more table salt than their wives.

We examined the response of the plankton community to strong changes in the volume of oligotrophic Lake La Caldera through the ice-free period of 1995-1997. As consequence of the changes in the precipitation regime, the lake volume diminished to 2 m depth during the extremely dry year of 1995. The increase in phosphorus availability for this year caused the diversification of the planktonic community, and the autotrophic:heterotrophic (A/H) ratio was below 1. In spite of the sporadic dust loads associated to atmospheric events, the quick recovery of the lake volumen in 1996 led to a severe phosphorus limitation. Phytoplankton community was dominated by Chrysophyceae (>90% of abundance) and large zooplankters were very scarce (

We analyzed the changes in epilimnetic total nitrogen (TN), total phosphorus (TP), dissolved inorganic nitrogen (DIN), and soluble reactive phosphorus (SRP) in 31 small high-mountain lakes in the Sierra Nevada (Spain) during an annual cycle, just after the spring thaw, and in the middle of the growing season. Chlorophyll a, TN, and TP increased, whereas the TN:TP ratio fell substantially between the two periods, reaching values generally between 25 and 10 (by weight). On the contrary, DIN, SRP, and DIN:SRP ratios were similar for both periods in each lake. DIN:SRP ratios generally ranged from 5 to 20 (by weight). This ratio was low in the lakes with small catchment areas and increased progressively with catchment basin size. A regression analysis for the smallest catchments showed that chlorophyll a concentrations were not accounted for by variability in TP concentration. The results obtained are discussed in relation to the influence of episodes of Saharan dust, rich in P, reaching the Southern Mediterranean area. Resume : Nous avons analyse les variations de l'azote total (NT), du phosphore total (PT), de l'azote inorganique dissous (NID) et du phosphore soluble reactif (PSR) de l'epilimnion de 31 petits lacs de haute montagne de la Sierra Nevada (Espagne) pendant un cycle annuel, tout juste apres le degel du printemps et au milieu de la saison de croissance. Les concentrations de chlorophylle-a, de NT et de PT ont augmente tandis que le rapport NT:PT a diminue de facon appreciable entre les deux periodes pour atteindre des valeurs se situant generalement entre 25 et 10 (en poids). Au contraire, les concentrations de NID et de PSR de meme que le rapport NID:PSR etaient semblables au cours des deux periodes et dans chaque lac. Le rapport NID:PSR se situait generalement entre 5 et 20 (en poids). Le rapport etait faible dans les lacs a bassin versant peu etendu et augmentait progressivement avec la superficie du bassin. Une analyse de regression portant sur les bassins les plus petits a montre que les concentrations de chlorophylle-a ne se refletaient pas dans la variabilite de la concentration de PT. Les resultats obtenus sont traites dans le contexte de l'influence de vents en provenance du Sahara qui transportaient de la poussiere, riche en P, et atteignait le sud de la Mediterranee.