Variation In Ash Content Research Articles

Effect of Coal Rank and Coal Facies on Nanopore-Fracture Structure Heterogeneity in Middle-Rank Coal Reservoirs.

Considerable variations in microscopic and industrial components (ash, moisture, volatile matter, etc.) have been reported within identical coal seams. These disparities in coal quality and pore structure within the same coal seam profoundly affect the drainage of deep coalbed methane (DCBM). This study focuses on 22 coal samples collected from two wells in the Benxi Formation of the central and eastern parts of the Ordos Basin. First, the coal facies were determined for all samples using submicroscopic components, and then, the adsorption pore and seepage pore structures were studied through CO2/N2 adsorption and mercury intrusive tests. Subsequently, the study delves into the correlation between coal rank, coal facies, and the distribution of the pore structures across various pore sizes, elucidating the primary controlling factors influenced by coal rank and coal phase. The results are as follows: (1) For a given coal seam, R o,max exhibits minimal variation among the samples, which suggests R o,max is not the primary factor affecting pore structure. Conversely, the ash content occupies the pore space, thereby revealing a negative correlation between the ash content and adsorption pore volume (PV). (2) On the basis of the texture preservation index (TPI) and gelatification index (GI), coal facies were classified into moist forest swamp facies (type A), moist herbaceous swamp facies (type B), and water-covered herbaceous swamp facies (type C). Type A is characterized by higher TPI, lower GI, and ash content, whereas type C exhibits lower TPI, higher GI, and ash content. (3) Type A samples, with the lowest ash content, display larger PV and specific surface area (SSA) compared with type B, while type C has the lowest values. Type C, with the highest vitrinite content, predominantly consists of semibright and bright coal, prone to microcracks, which results in a higher seepage PV compared with types A and B. (4) The coal facies represent variations in ash content and microscopic components, which significantly impacts both adsorption and seepage pores. Moist forest swamp facies samples are characterized by micropore development and the highest content of adsorbed gas. Herbaceous swamp facies samples display macropore development and the highest content of free gas.

Evaluation of different probiotics on growth, body composition, antioxidant capacity, and histoarchitecture of Mugil capito

We investigated the dietary effects of the single application of Saccharomyces cerevisiae, Lactobacillus bulgaricus, and their combination on growth, proximate composition of whole fish body, antioxidant defense, and histoarchitecture of hapa-reared Mugil capito. Healthy fish (Fish weighed = 10.30 ± 0.10 g at first) were randomly allocated into 4 equal groups, each with three replicates. These groups were designed as follows: (1) a group fed a basal diet without probiotics (control), (2) a group fed a diet containing S. cerevisiae (4 g/kg diet), (3) a group fed a diet containing L. bulgaricus (2 g/kg diet), and (4) the last group fed a diet containing a combination of both, all for a duration of 60 days. Probiotic-treated groups showed significantly better growth and nutrition utilization than the control group. Significant differences were observed in the crude fat and crude protein contents among the groups, with the combination group exhibiting the highest levels. However, there were no significant variations in ash content across all groups. The highest hepatic antioxidant capacity (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) enzyme activities) was observed in the combination group. Thiobarbituric acid reactive substance (TBARS) concentrations were decreased significantly in all probiotic groups, suggesting improved oxidative stress resilience in these groups. The histomorphological analysis of the hepatopancreatic tissues revealed well-arranged parenchyma, increased glycogen storage, and melanomacrophage centers in probiotic-treated groups, particularly the combined probiotics group. Furthermore, the probiotic supplementation improved the histoarchitecture of the intestinal villi compared to the control group. To put it briefly, combined dietary administration of these probiotics improved growth, body composition, antioxidant defenses, and hepatic and intestinal health in hapa-reared M. capito, highlighting their promising role in promoting welfare and productivity.

FORMATION OF WATER ABSORPTION CAPACITY OF FLOUR ON MILLS OF DIFFERENT PRODUCTIVITY

This article presents the results of a study of the quality indicators of flour streams, which affect the formation of the water absorption capacity of the final flour. The studies were carried out on five mills with a productivity of 60 to 300 tons per 24 hours. With the help of an original technique for removing the quantitative balance of the milling process, the yield of each individual flour stream and the yield of the final flour were determined, which depended on the productivity of the mill and varied from 75.9-76.1% – for mills with low productivity to 79.0-80.6% – for mills with productivity above 150 tones per 24 hours. Significant changes in the quality indicators of flour streams have been established. During milling at the mill plant with productivity of 150 t / 24 h ash content increased from 0.39% to 2.21%, protein content – from 11.0% to 17.4%, starch damage – from 17.6 UCD to 32.5 UCD. As result the water absorption capacity increases during the milling process from 54.0 to 69.6%. The variation in ash content, protein content, starch damage and other properties of the mill streams are due to the anatomical parts they come from, as result it influence the quality of the final flour. A simple correlation analysis carried out made it possible to evaluate the effect of ash content, protein content, and damaged starch content on the evolution of water absorption capacity. The variations of starch damage and ash content in the flour streams seems to be the principal factor of the increase in water absorption variation, while protein content has the least influence. Despite fluctuations in flour quality indicators on individual systems, it was found that strongly determines the overall quality of the final flour is the mill stream flour yield. That’s why optimization of grinding and sieving modes of systems (B1, B2, C1, C2, B3, Siz1) which have flour streams with the highest yield and the greatest impact on the grinding process is a fundamental step in achieving the set values for the final flour quality indicators. Knowledge and understanding of the patterns of change on individual systems of values of flour yield and their quality indicators that affect water absorption capacity will allow to more effectively manage the water absorption capacity. This will make it possible to optimize the properties of the dough according to the requirements of specific technological lines and to regulate the quality of the finished product at bakery and confectionery enterprises.

Net primary productivity and its control of the Middle Jurassic peatlands: An example from the southern Junggar coalfield

The Jurassic is an important period of global coal formation, including the development of several large coalfields in central Asia and northern China. Individual seams within these peatlands represent sustained periods of terrestrial carbon accumulation and a key environmental indicator attributed to this record is the rate of carbon accumulation. Determining the rate of carbon accumulation requires a measure of time contained within the coal and this study aimed at determining the rate via the identification of Milankovitch orbital cycles using spectral analysis. Spectral analyses of geophysical data from two thick coal seams, No. 43 (35.9 m) and No. 3 (13.2 m), of the Middle Jurassic of the southern Junggar coalfield were conducted to identify significant signals of variations in ash content. The results showed that the variations in ash content of the coal showed spatial cycles at 0.2, 0.7 and 1.1 m−1, which were interpreted to represent 123 ka (eccentricity), 37.1 ka (obliquity), and 21.2 ka (precession) orbital periodicities, respectively. Using this timeframe, the depositional time of the No. 43 and No. 3 coal seams were calculated to be 876–970 and 322–357 ka, respectively. In combination with an understanding of carbon loss during coalification, the carbon accumulation rates of these Middle Jurassic peatlands were calculated to be 58.6–64.9 and 60.3–66.8 g C m−2 a−1 for the No. 43 and No. 3 coal seams, respectively. Given that the net primary productivity ( NPP ) was 4.3 times the value of the carbon accumulation in a mid-latitude region of 40°–45°N, an NPP of 251.8–279.1 and 259.1–287.1 g C m−2 a−1 was calculated for the No. 43 and No. 3 coal seams, respectively. In the context of the same paleolatitude (40°–45°N) and peat type, the NPP values of the Middle Jurassic strata in the study area were higher than those of the peatlands of the Holocene and Permian, and were similar to the NPP values of Early Cretaceous peatlands. Considering the NPP of a peatland is predominantly controlled by atmospheric CO2 and O2 levels and temperature, the lower content of CO2 and an excessive O2 level in the temporal atmosphere would lead to a decrease in peatland NPP . Therefore, it is inferred that the CO2 level during the Middle Jurassic was higher than that of the icehouse Permian and Holocene periods, and it was similar to the CO2 level of the greenhouse Cretaceous period. The results are consistent with the global CO2 variation curve of Berner. In conclusion, Milankovitch orbital cycles calculated from geophysical logs can be used to infer the NPP of temporal peatlands during different geological periods, based on which the deep-time paleoclimates can be analyzed.

The influence of ash content on thermophysical properties of ethylene glycol based graphite/diamonds mixture nanofluids

Since the second half of the twentieth century, nanofluids are very promising engineering materials that can find numerous applications in the processes of heat exchange. Scientist and engineers are developing new and more advanced nanosuspensions which may differ from their physical properties, production costs and practical use. The aim of this paper is to study the differences between two nanofluids containing a mixture of graphite and nanodiamonds with various ash content. Here, ethylene glycol was used as a base fluid. Rheological properties, thermal and electrical conductivities at a constant temperature 298.15K were investigated for nanoparticle volume content ranging from 0.004 to 0.023. It was presented that ash content in nanofluids changes significantly rheological properties of nanofluids containing graphite/nanodiamonds mixture nanoparticles. While the variation in ash content does not affect thermal conductivity of nanofluids, a big impact on electrical conductivity is reported.

A correction method for thermogravimetric wood analysis under pyrolytic conditions using autosampler and a vertical balance system

Thermogravimetric analysis is a quick method for identifying the material composition of polymers and wood composites through differences in the thermal stability of their components. Scots pine stemwood usually exhibits an average ash content of 0.5 %. However, a large variation in ash content was found when analyzing the composition of Scots pine sapwood sampled with an autosampler and analyzed with a PerkinElmer Thermogravimetric analyzer Pyris 1 TGA, which was equipped with a vertical balance system. An increase in ash content was found with increasing order of analysis due to tar accumulation on the weighing system during pyrolysis in an inert and subsequent combustion in an oxidative atmosphere. This mass increase falsifies the individual ash content and initial sample mass readings. Uncorrected, the method can therefore give a biased interpretation of the composition of wood compounds. A method that provides a mathematical correction of the false ash contents and adjusts for a false initial mass of the sample is presented in this paper. The ash content could be calculated by this correction method to a close approximation.

Impact of Dry Climate on the Distribution of Mineral Elements in Soil Layers and its Relationship with Plant Development

Aim: This study evaluates the effect of dry climate on mineral distribution in soil and its correlation with their plant growth. Methods: Soil samples from different depths (0.0-100 cm) and ten developing plants above them were collected for one year from three districts (Old-Dir’iyah, Jenadriah and Muzahimiyah) in Riyadh, KSA. Results: The results revealed that all soil samples had alkaline pH and contain high total carbonates concentrations. Total dissolved salts recorded the highest content in Muzahimiyah area under Zygophyllum migahidii, Moricandia sinaica and Heliotropium bacciferum plants which indicates their high-salinity tolerance. Chemical analysis of soil samples showed great variation in the anions and cations content. Among the studied anions in soil samples, sulphate had the highest record while phosphorus was the lowest. Calcium and iron were the highest and the lowest cations found in soil content respectively. Sodium, potassium and magnesium were varied in different regions among different soil depths under the plants. Accumulation of sodium, magnesium, potassium, phosphorus and total carbonates were recorded in the studied plants which assist them to confront drought in both the summer and winter. Results showed that there is variation in ash content among different plants. Conclusion: Mineral persistence inside plants revealed their defiance to drought.

Comparative evaluation of the mineralogical composition of Sphagnum peat and their corresponding humic acids, and implications for understanding past dust depositions

With 6.5 m of peat accumulated during the past ca. 15,000 years, Etang de la Gruère (EGr) represents the longest continuous record of atmospheric dust deposition in northern hemisphere. This paper presents a comparative study of the mineralogical composition of Sphagnum peat samples and their corresponding humic acids (HA) from a peat core collected at EGr bog. The purpose of this study was to better understand the dominant process responsible for the amount and distribution of mineral matter in ombrotrophic (i.e., rain-fed) peat. Specifically, the goal was to separate the relative importance of the changing rates of atmospheric mineral dust deposition (during the past two millennia) from the mineralization of organic matter (OM), for the distribution of the ash fraction of the peat profile.The results suggest that variations in ash content at EGr are mainly the result of an increase in the rate of supply of dust particles and cannot be attributed simply, or exclusively, to differences in the degree of OM decay: evidence is provided by both acid insoluble ash (AIA) profiles and the correlations among lithogenic elements (Al, Si, Ti, Y, and Zr), total ash content and AIA. Moreover, our findings suggest that part of the AIA occurring in peat extremely is stable, and is unaffected by the extreme chemical conditions used to extract the HA fraction: this may be partly due to the inherent stability of quartz and “heavy minerals” such as zircon and rutile, but organic coatings developed on mineral surfaces during peat diagenesis, or the formation of some other kind of organo-mineral complex, might also play a role. Consequently, testimonies of past dust depositions can be observed also into the recalcitrant HA fraction of the peat.

A Comprehensive Genotype and Environment Assessment of Wheat Grain Ash Content in Oregon and Washington: Analysis of Variation

ABSTRACTA comprehensive analysis of the variation in wheat grain ash content has not been previously conducted. This study assessed the relative contribution of genotype and environment to variation in ash content, with a particular aim of ascertaining the potential for manipulating the trait using contemporary adapted germplasm. A total of 2,240 samples were drawn from four years of multilocation field plots grown in the wheat production areas of Oregon and Washington states. Genotypes included commercial cultivars and advanced breeding lines of soft and hard winter, and soft and hard spring wheats with red and white kernel color, several soft white club wheats, and one soft white spring waxy wheat cultivar. In addition to ash, protein content, test weight, and Single Kernel Characterization System kernel hardness, weight and size were also measured. In total, 20 separate fully balanced ANOVA results were conducted. Whole model R2 values were highly significant, 0.62–0.91. Nineteen of the 20 ANOVA results indicated significant genotype effects, but the effects were not large. In contrast, environment effects were always highly significant with F values often one to two orders of magnitude larger than the genotype F values. The grand mean for all samples was 1.368% ash. For individual data sets, genotype means across environments varied ≈0.1–0.3% ash. The genotypes judged noteworthy because they had the highest least squares mean ash content were OR9900553 and ClearFirst soft white winter, NuHills hard red winter, Waxy‐Pen and Cataldo soft white spring, and WA8010 and Lochsa hard spring wheats. Genotypes with lowest least squares mean ash were Edwin (club) soft white winter, OR2040073H hard red winter, WA7952 soft white spring, and WA8038 hard spring wheats. In conclusion, wheat grain ash is more greatly influenced by crop year and location than by genotype. However, sufficient genotype variation is present to plausibly manipulate this grain trait through traditional plant breeding.

Impact of Petrographic Properties on the Burning Behavior of Pulverized Coal Using a Drop Tube Furnace

The combustion behavior of three Indian coals of different rank with wide variation in ash content and maceral compositions were studied using a drop tube furnace (DTF). Each coal was pulverized into a specific size (80% below 200 mesh) and fed into the DTF separately. The DTF runs were carried out under identical conditions for all of the coals. The carbon burnout was found out from the chemical analyses of the feed coals and the char samples collected from different ports of the DTF. Char morphology analyses was carried on the burnout residues of the top port. The top port results show better burnout of the lower rank coals which however was not observed in the last port. An attempt has been made to account for this variation in terms of rank and petrographic parameters of the respective coals.

Evaluation of an On-Line Ash Analysis System for Low-Grade and Inhomogeneous Greek Lignite

The possibility of using commercial on-line analysis systems for monitoring the ash content of low-grade lignites was investigated by carrying out numerous bench- and pilot-scale trials in the mines of Public Power Corporation SA, Greece. Pilot-scale trials were based on a dual-energy {gamma}-ray transmission analyzer, which was installed on the conveyor belt that transports lignite from the pit to the bunker of Kardia mine, Ptolemais. According to the obtained results, the accuracy of the on-line measurements was not adequate and did not allow lignite quality monitoring in real time. The deterioration of the on-line measurements' accuracy, compared to previous applications in other mining sites, was related to the intense variation of the lignite ash content and ash composition, which distorted the calibration of the analyzer. The latter is based on certain assumptions regarding the average atomic number of the organic and mineral matter contained in the lignite. Further experimental work is needed to investigate solutions for successful implementation of this method to low-grade lignites that exhibit large variation in ash content and composition. 17 refs., 15 figs., 7 tabs.

Variations in ash content, pulp yield, and fibre properties of reed canary-grass

This study examines the effect of the variety of reed canary-grass (RCG), location, soil type, and yearly variation on the ash content of the stem, the RCG's pulp yield, and the RCG's fibre properties. Thirteen RCG varieties were grown in 11 locations in northern Europe. The RCGs were harvested using the delayed harvesting method. Two years (1997 and 1998) were included to obtain information of the yearly variation. The yearly variation had the greatest influence on the pulp properties. The ash content of the stem fraction of RCG mainly depends on location and soil type. The overall variation in the measured properties, however, was within reasonable limits, and a substantial reduction of the variation could be achieved by selecting varieties suitable to the climatic and soil conditions of the location.

Briquetting and combustion of spring-harvested reed canary-grass: effect of fuel composition

The purpose of this study was to increase the understanding how spring-harvested reed canary-grass briquettes with various chemical compositions with respect to ash content influence the formation of emissions during combustion in a 180 kW burner. Furthermore, an objective was to investigate possible ash problems during the combustion. Five fuels were used in the study consisting of three reed canary-grass samples with different ash contents from different growing sites in Sweden and additionally one of these materials was separated into a stem and leaf fraction. Flue gas emissions were measured and fuels and ashes were analysed. The variation in ash content did not affect the production of briquettes. Further, fuel containing only stem fraction showed the highest mechanical strength. The variation in ash content did not effect the flue gas emissions. The presented results showed low mean values for carbon monoxide ( <42 mg/ MJ , except one experiment) and particles in the flue gas (<150 mg/ Nm 3) (no purification of flue gas). Emissions of nitrogen oxides were <110 mg/ MJ . The ash formed light voluminous big chunks where small parts showed a tendency to be sintered. The combustion experiments imply that spring-harvested reed canary-grass can be burned with success in combustion equipment that is designed for the differences in ash content.

Elemental composition of Mysis mixta (Crustacea, Mysidacea) and energy costs of reproduction and embryogenesis under laboratory conditions.

Mysis mixta were reared under laboratory conditions (temperature: 9-10 degrees C; salinity: 7 per thousand, ad libitum food). Dry weight, ash, total carbon and nitrogen content of mysids (muscle tissue, eggs, and embryos of different developmental stages) have been analyzed. We found significant variations in ash content and elemental composition during growth and maturation for both sexes. The proportion of carbon in abdominal muscle decreased gradually from juveniles with body weight of 3-4 mg (42.9%) to males and gravid females ( approximately 40.0%). The nitrogen content was relatively constant (11.4% in average) with significant differences only between juveniles (11.3%) and mature females (11.6%). In embryos, carbon and nitrogen content were highest in early stages (58.6 and 14.3%, respectively). By the end of the marsupial development, carbon had decreased to 51.4% and nitrogen to 12.6%. The C:N ratio reflected the change in somatic carbon content, and the ratio decreased 6.2% from juveniles to gravid females, indicating lipids to be an energy source during maturation and reproduction. The weight-specific female investment in reproduction increases with body size. In gravid females, intersegmental growth during brooding period was observed, while males appear to store energy only for copulation and die after mating. Ontogenetic variation in body composition has implications for elemental budgets of M. mixta, its value as prey for fish and in modeling energy and nutrient cycling.

Enrichment and Depletion of Elements in a Subbituminous Coal and in Its 120°C, 400°C and 800°C Ashes

This study reports on the enrichment and depletion of elements in selected suites of subbituminous coals from the Highvale Mine, Alberta, Canada and in their 120°C, 400°C and 800°C ashes. All elements analyzed in the raw coal are within the world range for coals and some small variations in elemental concentration were noted due to variations in ash content of the samples. Ashing at 120°C resulted in an enrichment of all elements by a factor of 1.5 × to 6.5 × in one suite of samples and by a factor of 5 × to 11× in the other suite. Generally, the elements Br and Se are enriched by a lower factor than other elements, Mo is absent in all 120°C ashed samples and the samples with the higher ash content show a smaller elemental enrichment than samples with lower ash content (cleaner coals). All elements in the 400°C ashed samples are enriched by a factor of 1.5 × to 6.5 × in one suite of samples and by 1.5 × to 9.5 × in the other. Surprisingly, the elements Br, CI and Se are enriched two- to sixfold, pointing ...

Geochemistry of Subbituminous Coals from the Highvale Mine, Alberta, Canada

Coals from the Highvale Mine, central Alberta Plains, were studied in order to determine the quantity (range and mean values), affinity and mode of occurrence of the elements present in these subbituminous coals. Detailed elemental analyses were carried out for all coal seams and interburden in two drillholes, HV901-84 and HV904-84. In total, 49 samples were analyzed from the 16-m-deep HV904-84 drillhole (approximately three samples per meter of succession) and 33 samples from the 10.8-m-deep HV901-84 drillhole (also three samples per meter of succession). Mean concentration of various elements in the Highvale Mine coals are as follows, all others are below detection limits: Sb, 0.74 ppm; As, 3.82 ppm; Br, 286.4 ppm; CI, 72.3 ppm; Cr, 11.5 ppm; Co, 3.25 ppm; Cu, 20.6 ppm; F, 74.3 ppm; Hg, 0.012 ppb, Se, 1.65 ppm; U, 2.57 ppm; Th, 5.6 ppm; and V, 17.1 ppm. By world standards, all mean concentrations, except Br in some instances, are relatively low and the coals are not enriched in any environmentally or industrially hazardous elements. Therefore, the Highvale coals are considered “clean” by world standards and suitable for utilization. The concentration of elements associated with minerals (clays and/or carbonates), such as K, Mg, Na, Th, U, V and Zn, follows similar repetitive trends within coal seams throughout the coal-bearing succession, indicating that the pattern of coal formation is often cyclic and that these geochemical trends are related to the ash content of the coal and the parting location within the coal-bearing succession. Consistent seam-by-seam variations in the concentrations of elements generally do not occur, although some of the elements, such as Al, As, Sc, Th and the rare earthelements, tend to decrease from the roof toward the floor of coal seams. Only a few elements show a higher concentration in the middle or lower parts of the seam and it is believed that these trends may be more related to variations in ash content of the samples than to stratigraphic controls. Almost all the elements whose concentrations consistently exceed the detection limit appear to have strong inorganic associations. Exceptions are Cl, Br and B, which appear to be associated predominantly with the organic fraction in coal and a few elements, such as Mn, which appear to have an intermediate affinity.

Trace elements in coal samples from active mines in the Foreland Belt, British Columbia, Canada

Concentrations of Sb, As, B, Br, Cd, Cl, Cr, Co, Cu, F, Pb, Hg, Mo, Se, Th, U and Zn have been determined in channel samples collected at all active mines in the Peace River (northeastern B.C.) and East Kootenay (southeastern B.C.) coalfields. Means in whole-seam samples from both regions (30 samples), excepting those elements which are below detection limits in some samples, are as follows: Sb 1.0 ppm; As 1.6 ppm; Br 1.0 ppm; Cl 136 ppm; Cr 21 ppm; Co 2.3 ppm; Cu 18 ppm; F 518 ppm; Hg 50 ppb; Th 3.2 ppm; and U 1.8 ppm. By world standards, mean concentrations of Cl, Br, Co, As, Hg and Pb in B.C. coals are relatively low, while concentrations of F are relatively high. Mean values of Cl and Th are statistically higher in Peace River Coals than in East Kootenay coals; concentrations of other elements are similar in the two regions. Consistent stratigraphic variations in the concentrations of elements generally do not occur, although several of the elements, namely Sb, As, Cr, Co, Cu, F, Th aand U, achieve their highest concentrations in the middle one-third of the Mist Mountain Formation (East Kootenay) and in the upper one-half of the Gates Formation coal-bearing section (Peace River). These trends may be more related to variations in ash content of the samples than to stratigraphic controls. Based on correlations, almost all of the eleven elements whose concentrations consistently exceed detection limit appear to have strong inorganic associations. Exceptions are Cl and Br, which appear to be associated predominantly with the organic fraction.

Variations in the temperatures of coal-char particles during combustion: A consequence of particle-to-particle variations in ASH-content

Experimental evidence is provided that supports our hypothesis that the wide variations in the temperatures and burning rates of pulverized-coal char particles of nominally the same size are primarily a consequence of particle-to-particle variations in ash-content. In situ size, temperature, and velocity measurements on the char particles of two uncleaned, run-of-mine coals and on the char particles of their physically-cleaned products are presented. The cleaning process reduced the total mineral matter content of the coals. It is shown that the variations in particle temperatures are reduced with cleaning. The higher the mineral matter content of the coal, the wider the variations in the ash-content of individual particles and hence, the wider the variations in the temperatures of particles of nominally the same size. Wide variations in particle temperatures lead to wide variations in particle burning rates. It is also shown that the temperature-dependence of the chemical reactivity of the particle material remains unchanged throughout the early to late stages of burning. Further, the data indicate that catalysis by mineral matter is negligible at particle temperatures exceeding 1500 K.

養殖ハマチの成長にともなう一般成分と無機成分の季節的変動

The seasonal variations with growth in the proximate compositions and mineral contents of cultured yellowtail, Seriola quinqueradiata, were examined during a 20 month period from Febru-ary, 1985 to November, 1986. The muscle of yellowtail was divided into four parts: dorsal, ventral, caudal, and dark muscles, and for each part the amounts of moisture, crude protein, crude lipid, ash, and 13 kinds of minerals were analyzed. The following results were obtained. The moisture content was higher in the caudal muscle than in the other parts. In all the muscles moisture contents tended to increase in the summer. Crude protein contents were slightly higher in one year old fish than those in two years old. In lipid contents, there was a remarkable variation according to growth, and the lowest level was found in the summer. A negative correlation was noticed (n=160, r=-0.692) between the contents of moisture and crude lipid. The seasonal variations in ash content in the dorsal, ventral, caudal muscles were relatively slight.Seasonal variations of Ca, Na, and K contents in the muscles were significant; values of P, Fe, K, Mg, Cu, and Mn in dark muscle were different considerably from those in other parts. Higher contents of Fe, Cu, and Mn were noticed in the dark muscle. Heavy metals such as Pb, Hg, and Cd in all the muscles tested were within the dietary safety levels. The mean value of the edible portion of all samples assayed during a 20 month period was as follows: moisture 55.3g, crude protein 23.6g, crude lipid 14.0g, ash 1.8g, Ca 3mg, P 265mg, Fe 1.1mg, Na 26mg, and K 336mg per 100g. These results indicate that several components differ in value from those listed in the standard tables of food composition in Japan.

A fluvioglacial and glaciolacustrine deltaic depositional model for permo-carboniferous coals of the Northeastern Karoo Basin, South Africa

With the northward retreat of the late Palaeozoic Gondwana ice sheet a series of glacial valleys, partially filled with diamictite, dominated the landscape along the northern edge of the Karoo basin in South Africa. Consequent outwash sediments accumulated as fluvioglacial and glaciolacustrine deltaic deposits. Density underflow generated turbidity currents from which bottomset sediments were deposited. These comprise distal varved siltstones and shales, stratified pebbly-mudstones with dropstones, and proximal ripple-drift cross-laminated sandstones and siltstones. Delta foresets comprise large-scale accretionary cross-beds up to 5 m in thickness. Overlying outwash plain conglomerates and sandstones constitute the topset deposits. These are structured mainly by planar cross-beds which resulted from linguoid bar migration at high discharge. During falling-water stages plane-bedded and ripple-cross-laminated sandstones formed on bar surfaces under variable flow regime conditions. Upon abandonment of the outwash plain, shallow-rooted Arctic vegetation developed. Resulting peats exceeded 10 m in thickness and constituted precursors to coal seams in which variations in ash content are attributed to overbank splaying from recognisable anastomosing channels within the coal swamps. This study has illustrated a characteristic paraglacial sedimentation sequence; maximum depositional rates occur immediately after glacial retreat followed by decelerating sedimentation rates through time, leading finally to the development of extensive peats.