Mineral Salt Mixture Research Articles

Development of the wastewater treatment technology for the mine ‘Ternivska’ of the Kryvyi Rih iron ore plant

ABSTRACT Wastewater treatment in mining and mineral processing technology is a topical problem worldwide. The purpose of this study is to substantiate and develop the technology of complex wastewater treatment for the mine ‘Ternivska’ of the Public Joint Stock Company ‘Kryvyi Rih Iron Ore Plant’ with the production of highly purified water suitable for secondary use or ecologically safe discharge into surface water bodies. The proposed technology is based on the sequential application of the following stages: preliminary treatment of contaminated mine waters by coagulation and soda-lime softening methods to remove hardness, suspended solids, and colloidal substances; desalination via reverse osmosis; evaporation and crystallization of reverse osmosis concentrate in a vacuum evaporation unit; dehydration of salt sludge in a centrifuge with drying of salt crystals in a dryer. The treatment of mine water with an initial salinity of 80 g/L will give an annual effect of 1357 thousand m3 of desalinated water with a mineralization of up to 100 mg/L and 739.6 tons of mineral salt mixture. The purified water can serve as an additional source of fresh water for technological needs in industry or alternative purposes. The obtained solid salt product can be used as an alternative reagent for water-softening processes. In general, the proposed processing of mineralized mine water can be considered a zero-waste technology with clean water production and by-product utilization.

Energy-protein supplementation before and after parturition of Nellore primiparous cows in the Brazilian tropical savannah

Reproduction is associated to the profitability of beef herds, which affects the level of productivity and is influenced by nutritional level. The objective of this study was to evaluate the effect of protein and energy supplementation, before and after parturition, on reproductive variables of Nellore primiparous cows extensively raised in the Brazilian tropical savannah. Eighty pregnant heifers with parturition estimated for a 45 d period during the dry season were randomly divided into four treatments: Control, received a mineral salt and urea mixture pre and postpartum; PRE, protein-energy mixture from the 210th gestational day until parturition; POS, protein-energy mixture from parturition until 90 d afterwards; PREPOS, protein/energy mixture from the 210th gestational day until the 90th day after parturition. Number of days to complete uterine involution (UI) was 37.0 (Control); 31.3 (PRE); 33.1 (POST) and 25.3 (PREPOST) with differences (P<0.05). Calving Interval (CI) was 370.4 (Control), 369.5 (PRE); 365.9 (POST) and 343.7 (PREPOST) days, with differences (P<0.05). Pregnancy rate (PR) was 64.7%; 76.5%; 65.0%; and 55.0%, respectively, for CONTROL PRE, POS, PREPOS, without difference (p>0.05). In conclusion, energy-protein supplementation of Nellore primiparous cows raised in extensive systems under tropical conditions, before and after parturition, reduces days to uterine involution and calving interval.

Effect of different mineral salt mixtures and dough extraction procedure on the physical, chemical and microbiological composition of Şalgam: A black carrot fermented beverage

NaCl is utilized in Şalgam at 1–2% (w/w). The aim of this study was to reduce the NaCl content by addition of different concentrations of KCl and CaCl2 during production and evaluate their effects on quality. An innovation in production process was also employed, specifically dough extraction and use of the resulting liquid as a starter inoculum. Lactic acid bacteria (LAB) species (13) were identified using a combined approach of (RAPD)-PCR and 16S rRNA gene sequencing. Lactobacillus paracasei and Lactobacillus plantarum were dominant, but Leuconostoc mesenteroides subsp. jonggajibkimchii, Lactococcus lactis subsp. cremoris, Lactobacillus coryniformis subsp. coryniformis, Lactobacillus paraplantarum were also found. Mineral compositons were determined using ICP-OES and the most abundant were potassium, sodium, calcium, magnesium and phosphorus, respectively. A mixture of NaCl and KCl protected anthocyanin contents and improved colour parameters. Dough extraction also accelerated production of şalgam.

Oral \u03b2-hydroxybutyrate increases ketonemia, decreases visceral adipocyte volume and improves serum lipid profile in Wistar rats

BackgroundKetosis can be induced in humans and in animals by fasting or dietary interventions, such as ketogenic diets. However, the increasing interest on the ketogenic state has motivated the development of alternative approaches to rapidly increase ketonemia using less drastic interventions. Here, it was tested whether oral intake of a β-hydroxybutyrate (βHB) mineral salt mixture could increase ketonemia in Wistar rats without any other dietary changes, thereby being a useful model to study ketones effects alone on metabolism.MethodsβHB salts were orally administered to provoke elevation in the ketonemia. Effects of this intervention were tested acutely (by gavage) and chronically (4 weeks in drinking water). Acutely, a concomitant glucose overload was used to suppress endogenous ketogenesis and verify whether βHB salts were really absorbed or not. Long-term administration allowed to weekly evaluate the impact on ketonemia, blood glucose and, after 4 weeks, on body weight, visceral fat mass, lipid blood profile, serum lipolysis products and adiponectinemia.ResultsβHB salts increased ketonemia in acute and long-term administrations, improved blood lipid profile by raising HDL-cholesterol concentration and decreasing LDL/HDL ratio, while reduced visceral adipocyte volume. Mean ketonemia correlated positively with HDLc and negatively with adipocyte volume and serum lipolysis products.ConclusionsOral βHB can rapidly increase ketonemia and, therefore, be used as an acute and long-term animal model of ketosis. Long-term treatment points to important beneficial effects of ketone bodies in serum lipid concentrations and visceral fat mass. These results may help to explain the metabolic adaptations following ketogenic diets, such as a better body fat control and a serum lipid profile improvement.

Liquid organic fertilizer sprayed on shoots of Phaseolus vulgaris stimulates arbuscular mycorrhiza colonization and phosphate solubilizing microorganisms in soil

ABSTRACTProcessed organic agricultural byproducts such as liquid organic fertilizer (LOF) are promising alternatives that can improve crop productivity while reducing mineral fertilizer use and improving sustainability. The effects on beneficial soil organisms, such as arbuscular mycorrhizal (AM) fungi and phosphate solubilizing microorganisms (PSM), caused by LOF spraying on shoots is poorly understood. Therefore, we evaluated how AM colonization and soil PSM are affected by LOF spraying on common beans (Phaseolus vulgaris L.) grown in a greenhouse. The LOF was obtained by anaerobically fermenting a mixture of fresh water, cattle manure, bovine milk, sugarcane molasses and mineral salts. LOF was applied twice on the plant shoots. Fresh and dry mass of root and shoot, P content, P accumulation in the shoots and AMF spore counts in the soil were not LOF dose dependent. However, we found that a 5% LOF application stimulated AM colonization and led to dose-dependence for calcium and aluminium phosphate solubilizing bacteria and fungi. These results show that LOF sprayed on shoots causes responses on soil communities. We therefore endorse the use of LOF in low input agriculture.

Anaerobic digested sludge: a new supplementary nutrient source for ethanol production

Effluent sludge from an anaerobic digester was used as a source of nitrogen, phosphate, sulfur, and other nutrients in the culture medium of ethanol production by the yeast Saccharomyces cerevisiae. Several pretreatments (mechanical, chemical, thermal, and thermo-chemical) were performed on the anaerobic digested sludge (ADS) to make the nutrients accessible to the yeast cells. Preliminary experiments revealed that S. cerevisiae is not able to assimilate the carbon content of the ADS. However, when glucose was added to the medium, ethanol production was observed. The yield of ethanol using untreated ADS was only 10 % of the theoretical yield, but alkaline pretreatment improved it up to 43 %. By separating the hydrolysate of alkaline-treated ADS from the suspended solids, the ethanol yield from the supernatant was further improved up to 65 % of theoretical yield. Alkaline-treated ADS exhibited competitive performance with the mixture of yeast extract and mineral salts in ethanol fermentation.

Vanadium concentration in mineral salt mixtures used as supplementation in bovines

O comércio de suplementos minerais para bovinos no Brasil cresceu muito desde a última década. Muito embora seja necessária a utilização de matérias primas sem contaminantes, é possivel que alguns fabricantes ainda utilizem fontes de fósforo mais baratas. Essa situação pode veicular metais pesados na mistura mineral pronta, o que, em médio prazo, pode intoxicar os animais. Por essa razão, foi mensurada a concentração de Vanádio nas amostras de misturas de sal mineral usadas na suplementação de gado de corte nos estados do Paraná, Brasil. A concentração de vanádio foi determinada pela indução da espectrometria acoplada à emissão de plasma atômico. Das 22 amostras analisadas, 17 tinham valores maiores que 50 ppm (variando entre 66 e 128 ppm), a concentração máxima recomendada pelo Conselho Nacional de Pesquisa e pela Associação Americana de Controle Oficial de Alimentação. Esses resultados mostram a necessidade de um monitoramento industrial cuidadoso, porque algumas misturas de minerais contém quantidade suficiente de vanádio para causar intoxicação nos animais.

Optimization of Streptomyces sp.A11 Medium Cultivation on Cyclo(Tyrosyl-Prolyl) Production Using the Response Surface Methodology

The Response Surface Methodology is a three factorial design which provides the relationship between one or more measured dependent response and a number of input (independent) factors. Response surface methodology was used for optimization of fermentation medium for antibacterial agent cyclo(tyr-pro) production by Streptomyces sp. A11. The optimal response region of the significant factor was predicted by using a second order polynomial model fitted to the results obtained by applying the Central Composite Design (CCD) statistical design. Determination of the best production medium of cyclo(tyr-pro) showed among 6 carbon sources used, dextrin produced the highest cyclo(tyr-pro). Among the five nitrogen sources used, peptone produced the highest cyclo(tyr-pro), and the mineral salts group I produced the highest cyclo(tyr-pro) compared with others. The results of optimization showed that three variables (dextrin as a carbon source, peptone as nitrogen source, and mixture of mineral salts) used showed significantly affected to the activity of cyclo(tyr-pro). The mathematical model used, obtained by the composition of the three variables most optimum were concentration of dextrin was 32.55 g.L-1 , peptone concentration was 11.22 g L-1 , and 8.65 mL of mineral salts. By using the composition of mathematic model, cyclo(tyr-pro) was obtained 51.54 mg L-1 (model expectations) and 50.04 mg L-1 from experiments. The differences of experiment with expectation response value was 2.91%. Using the optimized parameters, the studies demonstrated an increase in the cyclo(tyr-pro) was 2.5 fold from 20 mg L-1 to 50 mg L-1

Production indices for dual purpose cattle in central Brazil

This study examined the effects of crossbreeding low genetic potential cows of Bos indicus origin characterized by Gyr crossed with Holstein-Friesian and Simmental bulls to produce animals in a low input dual purpose system. The farm is situated near Brasilia, in the savannah region of Brazil. The climate of the region is classified as Aw by Köppen. Data was available on 1580 calvings and completed lactations of cows with three genetic types: Gyr, Holstein-Friesian × Gyr and Simmental × Gyr. The bulls ran with the cows all year round and the diet comprised of pasture (mainly Brachiaria and Andropogon) during the summer (rainy season) and milled sugar cane with added urea during the winter (dry season). A mineral salt mixture was available ad libitum. Data was analysed using Statistical Analysis System. The results show that, under low input management conditions, the crossbred cows produce approximately twice the volume of milk per lactation, calve at a younger age and have a shorter open period, but there are no significant differences between crosses for growth rates of the calves or body condition of the cows. In this system, crossbred cows had production higher indices than zebu cattle. The best indices were found for cows calving in the rainy season (September to December) and thinner cows (with body condition 3-5 on a scale of 9).

Rumen acidosis: Possibilities of prevention using of mineral mix with buffering effect

Rumen acidosis is a very important pathophysiological disorder in intensive productive dairy cows, it is mostly a problem in early lactation when highly concentrated feeds are used in nutrition. The use of mineral salt mix based on bentonite, zeolite, magnesium oxide and sodium bicarbonate stabilizes and maintains pH of ruminal fluid in physiological values (6,79 to 6,92) and prevents the occurrence of rumen acidosis. In cows in the control group, the pH of ruminal fluid was at a low physiological level (6.01 to 6.25) and in some animals even lower. By adding this mixture of mineral salts to the concentrated part of feed (1%) optimal conditions are provided for activity and adequate numerous distribution of all species of infusoria in the rumen. The daily amount of milk produced and milk fat as well was 10 percent bigger in the experimental compared to the control group of cows.

Parâmetros ruminal, sangüíneo e urinário e digestibilidade de nutrientes em novilhas leiteiras recebendo diferentes níveis de monensina

Objetivou-se verificar a influência da inclusão de diferentes níveis do ionóforo monensina sódica na dieta sobre os parâmetros ruminal, sangüíneo e urinário e a digestibilidade aparente em novilhas leiteiras. Foram coletadas amostras de líquido ruminal (imediatamente antes e duas horas após a alimentação), sangue, urina e fezes de 28 novilhas da raça Holandesa mantidas em regime de confinamento por 84 dias. As dietas possuíam 32,84% de concentrado (grão de milho, farelo de soja, uréia e mistura mineral), 33,58% de silagem de milho e 33,58% de cana-de-açúcar na matéria seca. Os níveis de ionóforo avaliados foram 0, 14, 28 e 42 mg de monensina/kg de matéria seca da dieta. O experimento foi instalado conforme delineamento inteiramente casualizado, com quatro tratamentos e sete repetições, realizando-se estudos de regressão e contrastes ortogonais. Antes da alimentação, a monensina não influenciou o pH ruminal e a concentração de amônia e dos ácidos acético, propiônico e butírico, mas promoveu redução da relação acetato:propionato. Duas horas após a alimentação, verificou-se redução do pH e da relação acetato:propionato; e aumento da concentração de ácido propiônico. O estudo de contrastes revelou que ocorreu diminuição da concentração de amônia antes da alimentação. Não foram verificadas mudanças significativas nas concentrações de glicose e uréia sangüínea. A monensina também não influenciou os consumos de matéria seca (MS), matéria orgânica, proteína bruta, extrato etéreo (EE), carboidratos totais (CHOT) e fibra em detergente neutro. As digestibilidades da MS, EE e CHOT e a perda de nitrogênio urinário apresentaram respostas quadráticas.

Produção de proteína microbiana e estimativas das excreções de derivados de purinas e de uréia em vacas lactantes alimentadas com rações isoprotéicas contendo diferentes níveis de compostos nitrogenados não-protéicos

Foram objetivos do presente trabalho estimar a produção de proteína microbiana, utilizando-se a excreção total de derivados de purina (DP); comparar as excreções de DP e uréia obtidas a partir de coletas spot de urina com aquelas observadas em coletas de 24 horas; e avaliar as concentrações de N-uréia no plasma e no leite e as excreções de uréia. Utilizaram-se 16 vacas holandesas em quatro quadrados latinos balanceados 4 x 4, distribuídos de acordo com o período de lactação. Cada período experimental teve duração de 21 dias, sendo sete dias de adaptação e 14 dias para as coletas de amostras. As quatro rações experimentais, isoprotéicas, foram formuladas para conter na base da MS 60% de silagem de milho e 40% de concentrado. Foram utilizados níveis crescentes de uréia no concentrado: 0; 0,7; 1,4; e 2,1%, correspondentes aos níveis de proteína bruta na forma de compostos nitrogenados não-protéicos (NNP) das rações de 2,22; 4,18; 5,96; e 8,09%, respectivamente. O volume urinário foi estimado utilizando amostras de urina obtidas quatro horas após a alimentação (spot), dividindo-se a excreção diária média de creatinina pela concentração de creatinina na urina spot. O volume urinário e as excreções de DP e de uréia, estimados por meio da urina spot, não diferiram daqueles obtidos pela coleta de urina por 24 horas. As produções de N-microbiano estimadas e obtidas apresentaram valores máximos de 198,05 e 196,96 g/dia, nos níveis de compostos nitrogenados não-protéicos de 5,33 e 4,44%, respectivamente. A concentração de alantoína no leite decresceu linearmente com o aumento dos níveis de NNP na dieta e representou 4,5% da excreção total de DP. A excreção de creatinina não foi afetada pelos níveis de NNP na dieta (23,41 mg/kg PV), enquanto as excreções estimada e obtida de uréia, as concentrações de uréia e N-uréia no plasma e no leite aumentaram linearmente com os níveis de NNP na ração. Concentrações plasmáticas e no leite de N-uréia de 19 a 20 mg% e 24 a 25 mg%, respectivamente, representariam valores limites a partir dos quais ocorreriam perdas de compostos nitrogenados.

Concentration of lead in mineral salt mixtures used as supplements in cattle food

We measured lead concentrations in samples of mineral salt mixtures used in cattle feed in the states of Paraná and São Paulo, Brazil. Lead content was determined spectrometrically by the atomic plasma induction method. Of the 30 samples analyzed, 9 had lead concentrations above 30 ppm (range 35.7 to 284.5 ppm) which is the maximum concentration recommended by the National Research Council (NRC 1980). These findings show the necessity for careful industrial monitoring because some mineral mixtures contain sufficient lead to cause toxicity.

Can cow adaptability and carcass acceptability both be achieved?

Mineral supplementation programs in the cow-calf/stocker industry range from plain salt/sulfur blocks to highly formulated free-choice mineral supplements containing organic and inorganic sources of minerals. Choice of a mineral supplementation program that provides the greatest return on investment is important in a competitive marketplace. Many variables must be considered when designing the mineral supplement. Environmental condition, management practices, forage type, animal genetics, and physiological state of production make every production system different with respect to needs for mineral supplementation. However, to prevent tremendous complexity in managing mineral supplementation programs, average environments, forage mineral supplies, animal characteristics, and production levels are generally used as a starting point. In unique situations, formulations can be altered to account for variances from the norm. However, care must be taken to avoid critical negative mineral-to-mineral interactions that are known to exist. It is not uncommon to create a completely new problem when changing a mineral supplement program to fix an old problem. Choice of supplement ingredients is also critical to ensure adequate mineral absorbability. In addition, the mineral supplement providing the best mixture of mineral salts to meet production needs is of little value if consumption is not adequate. These issues are discussed with respect to forage supply of minerals meeting animal requirements.

Effects of energy supplementation and season on serum immunoglobulin and protein levels in Moxoto goats

A study was conducted to determine the influence of various levels of energy supplementation and season on total serum immunoglobulin and protein levels of female goats grazing native range (caatinga) in Northeast Brazil. The energy supplement was whole sorghum grain. One hundred and twenty female Moxoto goats weighing 10 to 12 kg were randomly assigned to one of four treatment groups consisting of 30 animals. Grain was supplemented at: 0, 0.6, 1.2 and 1.8%/BW on an as fed basis. The quantity of supplement offered was adjusted bi-weekly using the mean BW of goats from each of the treatment groups. Grain was offered individually in headlock feeders twice a day, before and after grazing (6 a.m. and 5 p.m.). Goats rotationally grazed three pastures of 65 ha each. A mineral salt mixture was offered ad libitum. The four groups did not show a statistical difference in total serum immunoglobulin levels. All groups, however, showed a seasonal variation in immunoglobulin levels. Immunoglobulin levels were highest during June to December (dry season) and lowest during January to May (rainy season). The lower levels of serum immunoglobulin levels may be a partial explanation for the increased incidence of major diseases recorded during this period of the year in Northeast Brazil. Goats receiving no sorghum grain supplementation had statistically significantly lower levels of serum protein during 8 of 19 months of this study. The most marked difference was between these animals and those receiving the highest level of energy supplementation. Seasonal variations in serum immunoglobulin levels may be a reflection of varying periods of immunocompetence and be of potential significance when assessing responses to immunogens.

The role of sugars in western spruce budworm nutritional ecology

Abstract. The western spruce budworm, Choristoneura occidentalis Freeman, and Douglas‐fir, Pseudotsuga menziesii (Mirb.) Franco, have been used to test the hypothesis that variation in levels of foliar sugars form part of the basis for plant resistance to herbivore attack. Budworm population growth was evaluated on artificial diets with 2–45% sucrose using a three generation bioassay. Diets with 1.2% and 3.9% N were tested to determine if responses to sugar were dependent on levels of protein. The 3.9% N diets were supplemented with a mineral salt mixture, so they had high levels of N and minerals. The response of budworm population growth to sucrose concentrations ≤20% was convex at 1.2% N and flat for 3.9% N. Population growth on the 1.2% N diet, which had levels of N and minerals similar to host foliage, was good with only 2% sugar, but optimal at the 6% sucrose level; the number of F1, F2 and F3 larvae produced declined substantially when sugar was increased to 11% and 20%. On the 3.9% N diets, population growth was equivalent for diets with 2% and 11% sucrose. Sucrose concentrations ≥29% were detrimental to the budworm at both N levels. Sugar concentrations in Douglas‐fir foliage varied between 5.7% and 18.4%. Thus, results from the 1.2% N experiment indicated that budworm performance was best on diets with sugar concentrations near the lower limit observed for host foliage. This implies that plants with higher foliar sugar may be inferior hosts for the budworm. Field observations supported this conclusion, as putatively resistant Douglas‐fir trees had significantly higher levels of sugars in their foliage than nearby paired susceptible trees. Variation in foliar sugars among individual trees may be part of the mechanism in Douglas‐fir resistance to C.occidentalis damage.

Activities and Regulation of Enzymes of Carbohydrate Metabolism in Spruce ( Picea abies)

Abstract Activities of the glycolytic enzymes were determined in seedlings, callus cultures and cell sus­ pension cultures of spruce (Picea abies) (L.) (Karst). The rate-limiting enzymes of the pathway were the hexokinases, ATP: phosphofructo-kinase, fructose-1,6-bisphosphatase and pyruvate kinase. Two phosphofructokinases were found: ATP : fructose-6-phosphate 1-phosphotransferase (PFK) and pyrophosphate :fructose-6-phosphate 1-phosphotransferase (PFP). In the presence of its activator fructose-2,6-bisphos-phate, PFP had a 4 -5-fold higher specific activity than PFK. PFP could be activated about 20-fold by fructose-2,6-bisphosphate at saturating concentrations of the substrates (fructose-6-phosphate and pyrophosphate). The increase of Vmax was accompanied by a strong increase in the apparent affinity of the enzyme for the substrates. Km for fructose-6-phosphate and pyrophosphate was 0.44 mM and 24 μM, respectively. Ka for fructose-2,6-bisphosphate was 24 nM. In seedlings, specific activity of the glycolytic enzymes was 30-300 percent higher in the hypocotyls, except for fructose-1,6-bisphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase, their activity being 100-150percent higher in the cotyledons, This distribution remained unchanged during periods of 2 -16 weeks of cultivation of the seedlings. In callus cultures and in cell suspension cultures, grown mixotrophically with different car­ bohydrates, all enzymes were between 1-and 7-fold higher than in autotrophically grown seed­ lings. Incubation of seedlings in mineral salt mixture containing a carbohydrate resulted in a rapid coordinate increase of the activities to the levels of callus-or cell suspension cultures. This induction required a carbohydrate and oxygen. During prolonged cultivation of cell suspension cultures, when carbohydrate became limiting, activity of the enzymes slowly declined.

The effects of culture conditions on the secretion of human lysozyme by Saccharomyces cerevisiae A2-1-1A.

The effects of initial glucose concentrations on the cell growth, glucose usage, and human lysozyme (HLY) secretion under the ENOl promoter were examined in the Saccharomyces cerevisiae strain A2–1–1A harboring a multicopy plasmid. By increasing the initial glucose from 2 % to 10 %, the HLY secretion increased 7 ~ 8 fold although the cell growth was not affected. By adding a mixture of mineral salts to the basal medium, the HLY secretion was increased about twice due to the continuity of the HLY expression at the stationary phase of cell growth.The high HLY secretion (5.5 mg per liter, 47-fold higher than the original level) was achieved by the strain A2–1–1A grown in the synthetic basal medium containing 10% initial glucose, and supplemented with mineral salts containing ammonium sulfate, potassium phosphate, potassium chloride, magnesium sulfate, and iron sulfate.

Methoprene Mineral Cattle Feed-Through Test for Pyrethroid Resistant Horn Fly Control, 1985

Abstract A test was initiated by feeding Morrman’s IGR Minerals (0.02% Methoprene) to 74 Angus cattle on 1 Jun. Straight mineral was placed in 2 sheltered mineral feeders which were situated near water and shade for the cattle. Prior to starting the IGR feeding test, all cattle were individually sprayed with 0.5% Vapona to knock down the existing horn fly population, which avg ca. 75 flies per cow. On 14 Jun the IGR consumption by the cattle was calculated to be 6 times more than required (according to label). Therefore, the mineral was diluted with salt to give a 67:33 mineral-salt mixture which provided the cattle with the correct amount of the IGR.

Near-ultraviolet photoelectron yield spectroscopy of rhodamine B adsorbed on NaCl(100); Correlations with contact charging

The density distribution of occupied states generated by the adsorption of rhodamine B on NaCl(100) in the energy region near the photoionization threshold has been estimated by measuring the wavelength dependent electrical charge of the sample arising from photoemission. Several substrate-dependent effects may determine this energy distribution, which is significant from the point of view of contact charging. This fact has a practical importance, since the contact charging of ionic crystals can be selectively controlled by certain adsorbed organic substances in the electrostatic separation procedure of mineral salt mixtures.