Mean Sb Research Articles

Sedimentary antimony stable isotope record of anthropogenic contamination in a karst lake in southwestern China

Anthropogenic sources of antimony (Sb) are an important driver of pollution in the Earth environment, but their roles in the historical changes of Sb pollution in lake ecosystems are currently poorly understood. This study documents the sedimentary Sb deposition fluxes in Hongfeng lake (HFL), in southwestern China during 1958–2021 and quantifies the changes of anthropogenic contributions to sediments using Sb stable isotopes. Mean Sb concentration (mean: 1.89 mg kg−1) and deposition flux (mean: 302.1 ng cm−2 a−1) in lake sediments remained relatively stable from 1958 to 1980. Sb deposition fluxes increased rapidly since 1980, peaked at 990.8 ng cm−2 a−1 in 2000, and then decreased consistently, reaching 306.9 ng cm−2 a−1 in 2021. Generally, the historical changes in Sb isotopes were anticorrelated with Sb deposition fluxes and enrichment factors, suggesting a lower ε123Sb signature in anthropogenic loading sources, and highlight the ability of Sb isotopes to distinguish anthropogenic signatures from natural processes in complex hydrological systems. Using a binary end-member mixing model, the contributions of anthropogenic sources to the accumulated of Sb in the lake sediments were estimated to be 20 % before 1980s and increased approximate 58 % during 2000–2015, then decreased to 24 % in 2021, likely reflecting the changes of degree in regional industrial activities. Our results help to better understand the response of Sb pollutions to anthropogenic activities and would in turn benefit the controls Sb contamination in lake ecosystems.

Structure of binary antimony phosphate glasses by diffraction methods

Antimony phosphate glasses (Sb2O3)x(P2O5)1-x with x = 0.05 and 0.80 were measured by neutron and X-ray diffraction with high real-space resolution. The P−O and O−O distance peaks of the PO4 tetrahedra were found with the expected parameters. For the glass of x = 0.80 the Sb−O and O−O coordination numbers and distances suggest highly distorted SbO3 and SbO4 environments according to strong lone-pair effects of the Sb3+. The fraction of SbO4 has the right portion that all oxygens can form Sb−O−Sb or Sb−O−P bridges. Significant numbers of secondary Sb−O bonds (> 0.25 nm) are extracted. The first diffraction peak at 13 nm−1 is related to distances between stacked layers of corner-connected oxygen triangles as in the orthorhombic Sb2O3. For the glass of x = 0.05 the medium-range order reminds that of vitreous P2O5. Its SbO4 units are formed with mean Sb−O bonds of 0.210 nm.

Impact of alternative irrigation practices on rice quality

AbstractBackground and objectivesCurrent global concerns about water scarcity present a need to investigate more water‐efficient rice production methods. Alternate wetting and drying (AWD) is fast emerging as a water‐saving irrigation practice, but its effects on rice quality are largely unknown. To ascertain the impact of water‐saving irrigation practices on rice quality, three irrigation treatments, namely continuous flooding with cascade delivery (four fields); continuous flooding with multiple‐inlet delivery (four fields); and AWD with multiple‐inlet delivery (four fields), were established on 12 production‐sized (16.2 ha) fields in 2017.FindingsResults of rice quality evaluations showed that irrigation treatment had a significant (p < 0.05) effect on chalkiness. Samples harvested from the AWD fields had slightly greater mean chalkiness (5.6%) than samples harvested from the two continuously flooded fields (5.1–5.2%). Milling yields were not affected (p > 0.05) by irrigation treatments. The average milled rice and head rice yields across irrigation treatments were 73% and 59%, respectively. Regarding pasting properties, while peak and breakdown viscosities were not affected (p > 0.05) by the irrigation treatments, setback viscosity (SB), which is often linked with cooked rice texture, was impacted. Among the irrigation treatments, mean SB was least for the AWD treatment (146 cP), while the mean SB for the continuously flooded fields was similar at 168–169 cP.ConclusionsIn summary, the use of AWD with multiple‐inlet delivery did not impact milling yields of rice relative to the conventional practices of continuous flooding. However, rice harvested from the AWD treatment fields had slightly greater chalkiness and lesser SB.Significance and noveltyThis study addresses a gap in literature concerning the impact of emerging water‐saving irrigation techniques, especially AWD as it involves subjecting rice to a certain level of water stress, on rice grain quality characteristics.

Antimony speciation and potential ecological risk of metal(loid)s in plain wetlands in the lower Yangtze River valley, China

Increasing attention is being paid to Sb as a primary hazardous substance, and further systematic studies of Sb behavior in freshwater wetlands are required. The plain wetlands in Lake Taihu basin located in lower Yangtze River valley, are heavily populated and economically developed area in China. The plain wetlands receive polluted water from point sources (textile and printing plants). In this study, Sb speciation in plain wetlands was investigated and the potential ecological risk of 8 metal(loid)s (As, Cd, Cr, Cu, Ni, Pb, Zn, Sb) were assessed. The mean Sb concentration in the wetlands water is 7.03 μg L−1, which consist of pentavalent, trivalent, organic Sb dissolved in water and a great part that attached to suspend solids (SS). Statistical analysis indicated that Sb(Ⅲ) is dissolved from SS and then further oxided to Sb(V) accompanied with tailing water discharged into wetlands; presence of organic Sb is related to microorganic in eutrophic environment; precipitation of SS is the dominant factor for distribution of bioavailable Sb in surficial sediment. The toxicity coefficient factor for Sb is proposed as 10 and ambient background of 8 metal(loid)s are set up. The potential ecological risk for plain wetlands was 135, which was low level. As, Cd and Sb were main contributors to the ecological risks. The wetlands are threatened by Sb pollution, which should be restrict by reducing the concentration of SS and Sb in tailing water from local water treatment facilities.

Comportamento sedentário como critério discriminador do excesso de peso corporal em idosos


 
 
 O objetivo do estudo foi analisar o comportamento sedentário como discriminador de excesso de peso corporal em idosos. Estudo transversal, com 310 idosos (idade ≥ 60 anos), de ambos os sexos, residentes no município de Ibicuí, Bahia. Foram investigadas informações sobre características sociodemográficas e pessoais; hábitos de vida e comportamento sedentário (CS), avaliado por meio do Questionário Internacional de Atividade Física - IPAQ. O índice de massa corporal (IMC) foi calculado pela divisão da massa corporal (kg) pelo quadrado da estatura (m2). Para identificação do CS (total/dia) como discriminador de excesso de peso, foi adotada análise das curvas Receiver Operating Characteristic (ROC) com IC95%. Os resultados apontaram tempo médio de CS de 414,14 (± 243,80) min/dia e a prevalência de excesso de peso (IMC > 27 kg/m2) foi de 39,7%. A área total sob a curva ROC entre CS e o excesso de peso foi 0,59 (IC95%: 0,50-0,67) para homens e 0,54 (IC95%: 0,43-0,58) para mulheres. Os melhores pontos de corte para discriminar a presença de excesso de peso foram de 390 min/dia ou mais e 270 min/dia ou mais para homens e mulheres, respectivamente. Nesse sentido, observa-se que o tempo gasto em CS apresenta uma boa capacidade preditiva para discriminar o excesso de peso em idosos.
 
 

Analysis ofSpitzer-IRS spectra of hyperluminous infrared galaxies

Hyperluminous infrared galaxies (HLIRG) are the most luminous persistent objects in the Universe. They exhibit extremely high star formation rates, and most of them seem to harbour an AGN. They are unique laboratories to investigate the most extreme star formation, and its connection to super-massive black hole growth. The AGN and SB relative contributions to the total output in these objects is still debated. Our aim is to disentangle the AGN and SB emission of a sample of thirteen HLIRG. We have studied the MIR low resolution spectra of a sample of thirteen HLIRG obtained with the IRS on board Spitzer. The 5-8 {\mu}m range is an optimal window to detect AGN activity even in a heavily obscured environment. We performed a SB/AGN decomposition of the continuum using templates, successfully applied for ULIRG in previous works. The MIR spectra of all sources is largely dominated by AGN emission. Converting the 6 {\mu}m luminosity into IR luminosity, we found that ~80% of the sample shows an IR output dominated by the AGN emission. However, the SB activity is significant in all sources (mean SB contribution ~30%), showing star formation rates ~300-3000 solar masses per year. Using X-ray and MIR data we estimated the dust covering factor (CF) of these HLIRG, finding that a significant fraction presents a CF consistent with unity. Along with the high X-ray absorption shown by these sources, this suggests that large amounts of dust and gas enshroud the nucleus of these HLIRG, as also observed in ULIRG. Our results are in agreement with previous studies of the IR SED of HLIRG using radiative transfer models, and we find strong evidence that all HLIRG harbour an AGN. This work provides further support to the idea that AGN and SB are both crucial to understand the properties of HLIRG. Our study of the CF supports the hypothesis that HLIRG can be divided in two different populations.

Preliminary Data on the Bioturbation Activity of Hediste Diversicolor (Polychaeta, Nereididae) from the Loire Estuary, France

The ragworm Hediste diversicolor (O. F. Muller, 1776) plays a key role in the estuarine water-sediment interface. This scientific project comes under the framework of the International network Nereis Park Experiment gathering 27 laboratories from all over the world. The experiments were carried out concurrently in spring 2007 using a common protocol. In the Loire estuary, the samples were collected in the intertidal zone of the Saint-Nazaire Bridge. During the field experiment, we estimated the surface area of the burrow walls (Sb) value varied from Sb = 0.26 m2.m-2 to 2.18 m2.m-2 (mean Sb = 0.75 m2.m-2), and the pumping rate (Pr) value from Pr = 0.9 l.d-1m-2 to 7.7 l.d-1 m-2 (mean value Pr = 2.7 l.d-1m-2). The density and the biomass of H. diversicolor populations largely controlled the amount of reworked sediment. In the laboratory, we estimated the pseudo-diffusive mixing, Db value varied from Db = 1.2 to 1.6 (mean Db = 1.5). The non-local transport (r) from the upper layers to the bottom of the tubes varied from r = 1 to 7.2 (mean r = 4.3). A positive relationship could be established between Db and the temperature while on the contrary a negative relationship could be established between the Db and biomass. It seems that small individuals are more efficient reworkers than big ones.

031 Use of the novel sideguard dedicated bifurcation stent: a real world experience

IntroductionPCI treatment of bifurcation disease is technically challenging. Dedicated bifurcation stents have been developed to address some of the challenges associated with bifurcation lesions. The aim of this study is...

Antimony as a traffic-related element in size-fractionated road dust samples collected in Buenos Aires

The growing interest of public opinion in environmental problems conducted us to investigate the levels of a toxic traffic-related element such antimony in 19 size-fractionated street dust samples. Samples were collected in the megacity of Buenos Aires during two months at 19 sites with different urban characteristics and traffic profile. Samples were sieved in four fractions (F1 < 37 µm, F2: 37–55 µm, F3: 55–75 µm and F4: 55–100 µm) before elemental analysis. A mixture of aqua regia and hydrofluoric acid was used to digest all samples. Antimony concentrations were quantified by inductively coupled plasma optical emission spectrometry (ICP OES) or flow injection hydride generation-atomic absorption spectrometry (FI-HG-AAS). Twenty four out of 73 sub-samples analyzed showed Sb levels < 0.05 µg g − 1 ; in the rest of the samples mean Sb concentrations varied from 1.4 to 20.4 µg g − 1 . Maximum and minimum concentrations (in µg g − 1 ) found in individual samples in the four fractions were: Fraction 1, < 0.05–20.4; Fraction 2, < 0.05–18.4; Fraction 3, < 0.05–6.3; Fraction 4, < 0.05–7.7. Antimony was found to be enriched in the smallest size fraction of road dust, with mean enrichment factors varying between 27 (F3) and 272 (F1). Concentrations of Sb were correlated with those of other traffic-related elements such as Cu and Pb and higher levels were found in areas with medium and high traffic densities.

Synthesis, structure, and stability of the high-temperature 6H-type perovskite phase Ba3BaSb2O9

The structure of Ba(3)BaSb(2)O(9) is reported for the first time as a high-temperature phase with an ideal hexagonal BaTiO(3)-type structure (space group P6(3)/mmc) and Rietveld-refined against high-temperature synchrotron X-ray powder diffraction data. The structure is remarkable for the extreme size difference between the pairs of face-sharing Sb(5+)O(6) octahedra (with mean Sb-O bonds of 1.99 Angstroms) and the single corner-sharing Ba(2+)O(6) octahedra (with mean Ba-O bonds of 2.46 Angstrom), which is greater than for any other reported 6H perovskite. This is consistent with the very different ionic radii of Sb(5+) (0.60 Angstroms) and Ba(2+) (1.35 Angstroms), and accounts for the instability of this phase at room temperature. The known symmetry-lowering modes of closely related 6H perovskites such as Ba(3)SrNb(2)O(9) and Ba(3)SrTa(2)O(9) are considered, but found not to account for the behaviour of Ba(3)BaSb(2)O(9) on cooling from high temperatures.

Enthalpies of formation of adducts of antimony(III) iodide with pyridine and methyl-pyridines

Solid adducts of formula SbI 3·L (L = pyridine or 2-, 3- or 4-methylpyridine abbreviated as Py, 2MPy, 3MPy or 4MPy) were synthesized and characterized by elemental analysis, IR spectroscopy and thermal analysis. IR data showed that coordination to antimony is through nitrogen. Thermal degradation of adducts starts at 431, 423, 413 and 411 K for Py, 2MPy, 3MPy and 4MPy, respectively. Reaction-solution calorimetry was used to evaluate the enthalpy change of reaction: SbI 3(cr) + L(l) = SbI 3·L(cr), 61.13 ± 1.75, −82.60 ± 1.55, −67.50 ± 0.97 and −74.10 ± 1.19 kJ mol −1, respectively. Enthalpy change values for decomposition of adducts, lattice enthalpies and enthalpies of the Lewis acid–base reaction in the gas phase were calculated through appropriate thermochemical cycles. Mean Sb N bond enthalpies were estimated as 134 ± 3, 154 ± 3, 140 ± 3 and 147 ± 4 kJ mol −1, for Py, 2MPy, 3MPy and 4MPy, respectively.

Biomonitoring of a worker population exposed to low antimony trioxide levels

Antimony trioxide (Sb 2O 3) is used as a flame retardant in the textile industry. We carried out a study in a factory for the evaluation of antimony (Sb) occupational exposure and urinary levels in workers exposed to Sb 2O 3. Urinary levels and airborne Sb 2O 3 personal exposure values were very low when compared to international occupational standards (500 μg/m 3, as Sb). The range of forty-two personal exposures was 0.01–0.55 μg Sb/m 3, while twenty-four area samplings ranged from < 0.01 μg Sb/m 3 to 1.45 μg Sb/m 3. The mean urinary Sb levels at the beginning (n = 39) and end of the shift (n = 39) were 0.31 ± 0.25 μg/L and 0.35 ± 0.29 μg/L respectively, without any significant statistical difference. When the workers were divided into two subgroups according to “higher” and “lower” exposure levels, a statistical difference (P < 0.001) was observed between the mean Sb urinary levels of the two subgroups during the workweek, both at the beginning and end of the shift. A statistical difference was also observed between the above mentioned subgroups and the controls (n = 15). No correlation was found between personal Sb 2O 3 exposure and the difference in urinary Sb levels at the beginning and end of the workshift on the day the flame retardant was utilized. This lack of correlation could be due to low airborne Sb 2O 3 levels and Sb dietary intake, estimated as 3 μg/day in UK, but not yet fully investigated in Italy. Any accidental occupational Sb per os exposure however low, could further enhance the lack of correlation.

121Sb Mössbauer Study of Sb2S3–As2S3–Tl2S Glasses

The local environment of antimony atoms in vitreous samples of the ternary system Sb2S3–As2S3–Tl2S is studied by121Sb Mössbauer spectroscopy. The results have been interpreted by means of EBV (empirical bond valence) and EBLV (empirical bond length valence) calculations. Variations in isomer shifts are attributed to changes in the environment of antimony atoms. The isomer shift is found to be a very sensitive parameter reflecting variations in the mean coordination number and in the mean Sb–S bond length. The results presented here confirm the random substitution of As by Sb in the binary system As2S3–Sb2S3and the competitive effects—breaking of As–S–As bridges by Tl and formation of As–S–Sb bridges—in the ternary system Sb2S3–As2S3–Tl2S, in agreement with previous XAFS studies.

A BVRIJKHα Survey of 355 Nearby Galaxies

A multiband CCD-survey of 355 UGC galaxies in our local cosmological neighbourhood is undertaken in collaboration with S.D.M. White (MPI-fAstrophysik Garching), S. McGaugh (IoA, Cambridge), M. Dennefeld (IAP Paris), H. Ferguson (STScI), M. Rieke, A. Grauer (Steward Obs. Arizona). Optical observations are obtained on Calar Alto (MPIA Heidelberg) and at La Palma (RGO) – with data 40% complete at the moment. The selection criterion is diameter 1.5′ &lt; D25 &lt; 2.5′. A database of local galaxy properties is being established (including total luminosities, mean SB, diameters, colours, colour gradients, D/B-ratios, present SFRs). Using theoretical evolution models we can predict the bona fide appearance of the galaxy population at any given redshift and thus provide a secure reference point to interpreting galaxies observed at intermediate and high z (e.g. faint galaxy counts).

Controlled hydrolysis reactions of the Group 15 element–azamacrocyclic complexes MCl3L (M = As, Sb or Bi; L = 1,4,7-trimethyl-1,4,7-triazacyclononane). Formation and crystal structures of [AsCl2L][As2OCl5], [H2L]2[Sb2OCl6]Cl2, [HL]I and [H2L]2[Sb2Cl9]Cl·MeCN·H2O

Reactions of MCl3(M = As, Sb or Bi) and 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3[9]aneN3= L) gave the respective 1 : 1 adducts as white-yellow microcrystalline solids which were characterised by microanalytical and spectroscopic (IR and 1H NMR) data. Addition of water to AsCl3L under controlled stoichiometry in acetonitrile solution led to the formation of the white crystalline salt [AsCl2L][As2OCl5]1. A crystal structure determination revealed the cation as five-co-ordinate with ψ-octahedral metal geometry featuring a cis-AsCl2+ unit co-ordinated to the three donor nitrogen atoms of the ligand (fac) and a stereochemically active lone pair occupying the sixth site [As–Cl 2.462(7), 2.520(7) and As–N 2.18(2), 2.12(2), 2.10(2)A with the latter directly opposite to the lone pair]. The anion is made up of a dinuclear (µ-oxo) Cl2As–O–AsCl2 unit with a single Cl– anion linked symmetrically to the two separate arsenic atoms [mean As–Clterminal 2.216(8), As–Clbridge 2.795(8)A]. Controlled hydrolysis of SbCl3L in acetonitrile solution provided colourless needle crystals of [H2L]2[Sb2OCl6]Cl22 as identified by X-ray diffraction studies. The structure of the dication shows protonation of two of the three nitrogen atoms with strong intramolecular hydrogen bonding N–H ⋯ N 2.70–2.85 A involving the third amine centre. This is the first structural characterisation of the diprotonated form of L. The structure of the accompanying chlorooxoantimony(III) anion can be described as a single (µ-oxo) Cl2Sb–O–SbCl2 unit linked to two chloride ions via secondary Sb ⋯ Cl bonding involving the two metal centres [mean Sb–Clterminal 2.435(3), Sb–Clbridge 2.863(3)A]. Each of the antimony(III) centres is further associated with a unique chloride anion, Sb ⋯ Cl– 3.550(7)A, which, in turn, forms close contacts with the two protonated nitrogen atoms of the triazamacrocycle Cl ⋯ H–N 3.07, 3.02 A. Treatment of L and SiMe3I in acetonitrile solution provided yellow needle crystals of [HL]I 3. X-Ray (diffraction) crystallographic characterisation revealed a monoprotonated ring (L) in which the single proton is bonded directly to one nitrogen atom and to the remaining two via intramolecular hydrogen N–H ⋯ N 2.71 A. The product isolated from the reaction of L and SiCl4 in the presence of antimony(V) chloride as halide abstractor in acetonitrile was identified by a crystal structure determination as [H2L]2[Sb2Cl9]Cl·MeCN·H2O 4. The structure reveals two [H2L]⋯Cl moieties which have dimensions similar to those found for 2. Conformational analyses have been carried out on free L and its mono-, di- and tri-protonated forms and the results are consistent with the experimental conformations observed in this work and elsewhere.

Redox behaviour and reactions of (PhCH 2) 3Sb; syntheses and structures of [(PhCH 2) 3SbMe]I and [(PhCH 2) 3SbMe] 3Sb 3I 12

(PhCH 2) 3Sb ( 1) reacts with MeI to form [(PhCH 2) 3SbMe]I ( 2). The action of excess I 2 on 2 gives [(PhCH 2) 3SbMe] 3Sb 3I 12 ( 3). 3 is synthesized in 78% yield by addition of SbI 3 to 2. The crystal structures of 2 and 3 are reported. The cations of 2 have a distorted tetrahedral coordination at Sb with SbC bond distances of 210.5(20)–215.7(20) pm and SbC 2 angles between 103.1° and 121.7°. Sb ⋯ I contacts of 373.3 pm increase the coordination at Sb to distorted trigonal bipyramids with Me and I in the axial positions. The crystals of 3 contain distorted tetrahedral [(PhCH 2) 3SbMe] + cations and (Sb 3I 12) 3− anions with the approximate structure of two SbI 3 molecules (mean SbI bond distances 283.2 pm) capping opposite planes of a SbI 3− 6 octahedron (mean SbI distance 302.4 pm). In addition to the preparative results the electrochemical properties of 1 are communicated and discussed.

Comparison of Scores on the WISC-R and the Stanford-Binet, Fourth Edition, for Rural Gifted Students

The WISC-R and Stanford-Binet, Fourth Edition scores of 40 gifted students were compared. The results indicate that the mean WISC-R Full Scale IQ was 13.52 points higher than the mean SB:FE composite score. The T-test between the two scores was significant at the .001 level. Eleven of the fifteen possible correlations were significant, with two at the .001 level, three at the .01 level, and six at the .05 level.

The abundance and distribution of antimony in red-beds of the Devonian Catskill Formation, eastern Pennsylvania, U.S.A.

A total of 195 sandstones and shales from red-beds of the Catskill Formation have been analyzed for Sb by epithermal neutron activation and for major elements by plasma emission spectrometry. The mean Sb content is 1.5 ppm for shales and 0.7 ppm for sandstone, in good agreement with the relatively few previous determinations for sedimentary rocks. Sb correlates positively with components of the fine-grained fraction (mica, Fe-oxide, chlorite) and with chemical elements in this fraction (Fe, Al, Mg, K, etc.), and correlates inversely with quartz and SiO 2. Gray-green sandstones and shales average slightly less Sb than red sandstones and shales, probably because of diagenetic redistribution of Sb, which is concentrated along with Cu, Ag, As and U in red-bed Cu occurrences of the region. The strongest correlation is with Fe, suggesting that Fe-oxides may be a major host. Factor analysis also suggests an affinity with Ca and Na, indicating diagenetic changes or red-beds derived from differing source areas.

Comparison of scores for intellectually gifted students on the WISC-R and the fourth edition of the Stanford-Binet

The WISC-R and the Fourth Edition of the Stanford-Binet (SB: FE) were compared in the identification and assessment of 48 intellectually gifted students in the primary and secondary grades. While only a 3.2-point difference between the mean SB: FE Composite score and the mean WISC-R Full Scale score was found, (r = .393, p. ⩽ .01), the t test between the two scores was significant (t = 2.30, p ⩽ .05). Correlations between the three scales of the WISC-R and the SB: FE four broad area and Composite scores ranged from −.219 (SB: FE Abstract/Visual Reasoning with WISC-R Verbal) to .599 (SB: FE Short-Term Memory with WISC-R Full Scale). Within the correlational matrix, only 5 of the 15 correlations were significant. Both the SB: FE Abstract/Visual Reasoning and Quantitative Reasoning Area scores had no significant correlations with any of the WISC-R scores.

Studies on nitrogen metabolism in rats of different age fed on a protein-free diet. 3. Urinary endogenous nitrogen excretion in relation to body size and protein-free feeding duration.

The influence of the time (t = 3, 6, 9, 12 and 16 days) of feeding on a protein-free diet (PFD) and the size of shrunk body mass (SB), increasing with age but decreasing with the duration of feeding on PFD, on the excretion of endogenous urinary nitrogen (EUN) were investigated. The experiment was on 350 male rats from 23 to 275 days of age and mean SB from 39 to 430 grammes, divided into 14 age groups (k = 14). The material and the method of the experiment as well as the composition of PFD were described in detail in part one of this work (Beza, 1986). The linear analysis of covariance showed that the EUN excreted after 3, 6, 9, 12 and 16 days on PFD as well as the average daily EUN did not significantly correlate with the initial body mass (SBi). It were calculated: 1. In relationship EUN(t) the slope ratios bk and intercepts ak, differed between the groups of age significantly. The ak values but not the bk, were closely correlated with the initial body mass SBi (r for ak values = 0.947***) indicating that the amount but not the rate of EUN excretion was closely related to SBi; 2. the daily EUN excretion at 1, 3, 6, 9, 12 and 15 days on PFD in relation to body mass in these days-EUNd(SBd) is described by the equation: EUNd = Ad.SBd 0.872 less than 1, in which Ad decreased from 287 mg N/SBd 0.872 on the first day to 167 mg N/SBd 0.872 on the 15th day on PFD; 3. the daily excretion of EUN(y) in relation to the daily body mass (x1) and to the day on PFD (x2) is described by the equation: EUNd(y) = 286.8.x1(0.872).x2(-0.1993); R = 0.987*** with N in mg, SB in kg. There was a directly proportional relationship between EUNd and SB0d 0.872 only (b1 = 1), whereas between EUNd and SBd 0.67 as well as between EUNd and SBd 0.75 the slope ratios b1 were 1.308 and 1.163, respectively and were significantly higher than one. With prolonged feeding on PFD for 15 days, the rate of EUNd excretion decreased in accordance to b2 = -0.1993 less than 0**, independently of the age and the initial SB of the rats.(ABSTRACT TRUNCATED AT 400 WORDS)