scholarly journals Rhombic calcite microcrystals as a textural proxy for meteoric diagenesis

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Mohammed S. Hashim ◽  
Stephen E. Kaczmarek
Keyword(s):  
Trace Elements ◽  
Laboratory Experiments ◽  
Crystal Form ◽  
Geochemical Data ◽  
Carbonate Sediments ◽  
Geochemical Evidence ◽  
Meteoric Diagenesis ◽  
Low Degree ◽  
Rock Record ◽  
High Degree

AbstractNumerous Phanerozoic limestones are comprised of diagenetic calcite microcrystals formed during mineralogical stabilization of metastable carbonate sediments. Previous laboratory experiments show that calcite microcrystals crystallizing under conditions similar to those that characterize meteoric diagenetic settings (impurity-free, low degree of supersaturation, high fluid:solid ratio) exhibit the rhombic form/morphology, whereas calcite microcrystals crystallizing under conditions similar to those that prevail in marine and marine burial diagenetic settings (impurity-rich, high degree of supersaturation, low fluid:solid ratio) exhibit non-rhombic forms. Based on these experimental observations, it is proposed here that rhombic calcite microcrystals form exclusively in meteoric environments. This hypothesis is tested using new and previously published textural and geochemical data from the rock record. These data show that the vast majority of Phanerozoic limestones characterized by rhombic microcrystals also exhibit petrographic and/or geochemical evidence (depleted δ13C, δ18O, and trace elements) indicative of meteoric diagenesis whereas non-rhombic forms are associated with marine burial conditions. By linking calcite microcrystal textures to specific diagenetic environments, our observations bring clarity to the conditions under which the various microcrystal textures form. Furthermore, the hypothesis that rhombic calcite microcrystals form exclusively in meteoric environments implies that this crystal form may be a useful textural proxy for meteoric diagenesis.

Rhombic Calcite Microcrystals as a Textural Proxy for Meteoric Diagenesis

2021 ◽  
Author(s):  
Mohammed S. Hashim ◽  
Stephen E. Kaczmarek
Keyword(s):  
Trace Elements ◽  
Laboratory Experiments ◽  
Geochemical Data ◽  
Carbonate Sediments ◽  
Geochemical Evidence ◽  
Meteoric Diagenesis ◽  
Rock Record ◽  
High Supersaturation

Abstract Numerous Phanerozoic limestones are characterized by diagenetic calcite microcrystals formed during mineralogical stabilization of metastable carbonate sediments in various diagenetic environments. Laboratory experiments show that calcite precipitating under conditions similar to those that characterize meteoric settings (impurity-free, low supersaturation, high fluid:solid ratio) exhibits the rhombic form, whereas calcite precipitating under conditions similar to those that prevail in marine burial settings (impurity-rich, high supersaturation, low fluid:solid ratio) exhibits non-rhombic forms. This prediction is tested here using new and previously published textural and geochemical data from the rock record. These data show that the vast majority of Phanerozoic limestones characterized by rhombic microcrystals also exhibit petrographic and/or geochemical evidence (depleted 𝛿13C, 𝛿18O, and trace elements) indicative of meteoric diagenesis. In contrast, non-rhombic forms are associated with marine burial conditions, suggesting that rhombic calcite microcrystals may provide a valuable textural proxy for meteoric diagenesis in Phanerozoic limestones.

scholarly journals Interactions Between Chill-Hours and Degree-Days Affect Carpogenic Germination in Monilinia vaccinii-corymbosi

2001 ◽  
Vol 91 (1) ◽  
pp. 77-83 ◽  
Author(s):  
H. Scherm ◽  
A. T. Savelle ◽  
P. L. Pusey
Keyword(s):  
Laboratory Experiments ◽  
Field Experiments ◽  
Degree Days ◽  
Carpogenic Germination ◽  
Conditioning Period ◽  
Low Degree ◽  
Heating Degree Days ◽  
Relationship Of ◽  
High Degree ◽  
The Relationship

The relationship of cumulative chill-hours (hours with a mean temperature <7.2°C) and heating degree-days (base 7.2°C) to carpogenic germination of pseudosclerotia of Monilinia vaccinii-corymbosi, which causes mummy berry disease of blueberry, was investigated. In two laboratory experiments, pseudosclerotia collected from rabbiteye blueberry in Georgia were conditioned at 5 to 6°C for 26 to 1,378 h prior to placement in conditions favorable for germination and apothecium development. The number of chill-hours accumulated during the conditioning period affected the subsequent proportion of pseudosclerotia that germinated and produced apothecia, with the greatest incidence of carpogenic germination occurring after intermediate levels of chilling (≈700 chill-hours). The minimum chilling requirement for germination and apothecium production was considerably lower than that reported previously for pseudo-sclerotia from highbush blueberry in northern production regions. The rate of carpogenic germination was strongly affected by interactions between the accumulation of chill-hours and degree-days during the conditioning and germination periods; pseudosclerotia exposed to prolonged chilling periods, once transferred to suitable conditions, germinated and produced apothecia more rapidly (after fewer degree-days had accumulated) than those exposed to shorter chilling periods. Thus, pseudosclerotia of M. vaccinii-corymbosi are adapted to germinate carpogenically following cold winters (high chill-hours, low degree-days) as well as warm winters (low chill-hours, high degree-days). Results were validated in a combined field-laboratory experiment in which pseudosclerotia that had received various levels of natural chilling were allowed to germinate in controlled conditions in the laboratory, and in two field experiments in which pseudosclerotia were exposed to natural chilling and germination conditions. A simple model describing the timing of apothecium emergence in relation to cumulative chill-hours and degree-days was developed based on the experiments. The model should be useful for better timing of field scouting programs for apothecia to aid in management of primary infection by M. vaccinii-corymbosi.

Stimulation of β-(l → 6)-glucanase production by oxidized pustulan

1972 ◽  
Vol 18 (10) ◽  
pp. 1543-1550 ◽  
Author(s):  
Robert G. Brown
Keyword(s):  
Enzyme Activity ◽  
Isoelectric Focusing ◽  
Gel Filtration ◽  
Tween 80 ◽  
Sole Source ◽  
Cellulase Production ◽  
Low Degree ◽  
Degree Of Oxidation ◽  
High Degree ◽  
Stimulation Of

A strain of Penicillium lilacinum, isolated from soil, produced pustulanase, β-(1 → 3)-glucanase, (EC. 3.2.1.6) and cellulase (EC.3.2.1.4) when cultivated on a medium containing pustulan as the sole source of carbon. If pustulan was replaced by ketopustulan, the production of pustulanase was stimulated about 10-fold although the amount of stimulation was dependent on the degree of oxidation of pustulan. β-(1 → 3)-Glucanase production was stimulated slightly by ketopustulan; however, the degree of oxidation did not affect significantly the yield of this enzyme. Cellulase production was either unaffected by the oxidized polymer, or at higher degrees of oxidation, decreased. Tween 80 stimulated the production of the three enzymes in media containing ketopustulan with a low degree of oxidation but was inhibitory to pustulanase and cellulase production in media containing ketopustulan with a high degree of oxidation. A combination of gel filtration and isoelectric focusing revealed that each enzyme activity was attributable to at least two proteins.

Dissolution and recrystallization in modern shelf carbonates: evidence from pore water and solid phase chemistry

1993 ◽  
Vol 344 (1670) ◽  
pp. 27-36 ◽  
Keyword(s):  
Organic Matter ◽  
Pore Water ◽  
Solid Phase ◽  
Chemical Exchange ◽  
Isotope Composition ◽  
Geochemical Data ◽  
Carbonate Sediments ◽  
Pore Waters ◽  
Carbonate Minerals ◽  
Carbonate Production

We present an overview of geochemical data from pore waters and solid phases that clarify earliest diagenetic processes affecting modern, shallow marine carbonate sediments. Acids produced by organic matter decomposition react rapidly with metastable carbonate minerals in pore waters to produce extensive syndepositional dissolution and recrystallization. Stoichiometric relations among pore water solutes suggest that dissolution is related to oxidation of H 2 S which can accumulate in these low-Fe sediments. Sulphide oxidation likely occurs by enhanced diffusion of O 2 mediated by sulphide-oxidizing bacteria which colonize oxic/anoxic interfaces invaginating these intensely bioturbated sediments. Buffering of pore water stable isotopic compositions towards values of bulk sediment and rapid 45 Ca exchange rates during sediment incubations demonstrate that carbonate recrystallization is a significant process. Comparison of average biogenic carbonate production rates with estimated rates of dissolution and recrystallization suggests that over half the gross production is dissolved and/or recrystallized. Thus isotopic and elemental composition of carbonate minerals can experience significant alteration during earliest burial driven by chemical exchange among carbonate minerals and decomposing organic matter. Temporal shifts in palaeo-ocean carbon isotope composition inferred from bulk-rocks may be seriously compromised by facies-dependent differences in dissolution and recrystallization rates.

Acaricide resistance in the red tick, Rhipicephalus evertsi Neumann.

1961 ◽  
Vol 51 (4) ◽  
pp. 755-764 ◽  
Author(s):  
G. B. Whitehead ◽  
J. A. F. Baker
Keyword(s):  
South Africa ◽  
Laboratory Experiments ◽  
Sodium Arsenite ◽  
Field Trials ◽  
Cross Resistance ◽  
Acaricide Resistance ◽  
The Past ◽  
High Degree

Early in 1959, observations on the farm Tayside, in the East London district of South Africa, suggested that populations of the ‘two-host’ red tick, Rhipicephalns evertsi Neum., were more difficult to control with toxaphene preparations than they had been in the past. Resistance to toxaphene was suspected, and both field and laboratory experiments were carried out to investigate this possibility. Field trials indicated an increase in tolerance by Tayside populations of the tick to toxaphene, γ BHC and dieldrin, but showed no increased tolerance to sodium arsenite or DDT. Similar results were obtained in laboratory experiments where Tayside adults were compared with those of other populations of the tick known to be sensitive to insecticides. Laboratory experiments with larvae indicated a high degree of resistance to toxaphene and γ BHC in the Tayside population, but no increased tolerance to sodium arsenite, Delnav, Sevin or DDT could be detected. This pattern of cross-resistance is similar to that occurring in resistant populations of Boophilus dccoloratus(Koch).

Leadership Styles of Public Schools Principals in the City of Hail in the Kingdom of Saudi Arabia: أنماط القيادة لدى مدراء مدارس التعليم العام في مدينة حائل في المملكة العربية السعودية

2021 ◽  
Vol 5 (41) ◽  
pp. 161-138
Author(s):  
Fahad Husain Alshammari Fahad Husain Alshammari
Keyword(s):  
Public Schools ◽  
Leadership Style ◽  
School Principals ◽  
Statistical Significance ◽  
Point Of View ◽  
Years Of Experience ◽  
Public School Principals ◽  
Low Degree ◽  
Study Population ◽  
High Degree

    This study aimed to: Identify the leadership style prevailing among public school principals in Hail from the teachers ’point of view, and to reveal the statistical significance of the differences in the estimates of the study sample individuals of the leadership style prevailing among school principals, which may due to variables of (educational stage, number of years of experience, and specialization). The researcher used the descriptive method, and prepared a questionnaire consisting of (24) statements distributed to (3) dimensions, which are: Democratic style, authoritarian style and chaotic style. The current study population included all the teachers of public education schools in Hail, who numbered (9390) teachers. The questionnaire was applied to a random sample of (296) teachers. The study found a set of results, the most important of which are: The prevailing leadership style among school principals is the democratic style, followed by the authoritarian style, and then the chaotic style. Where the democratic style obtained a mean (4.18) and a high degree of approval from the study sample, while the domineering style obtained a mean (1.83) and a low degree of approval from the study sample, and the chaotic style obtained an average (1.73) and a low degree of approval. Very members of the study sample. The results also showed that there are statistically significant differences in the degree of the study sample’s estimates of the leadership style prevailing among school principals due to the variable of years of experience, while there are no statistically significant differences in the degree of the study sample’s estimates of the leadership style prevailing among school principals due to the variables of the educational stage or specialization. In light of these results, the researcher recommended organizing training courses for school principals to enlighten them about the modern trends in educational leadership, and urged school principals to follow the democratic style of administration.

scholarly journals Genetic linkage map of Phaseolus vulgaris and identification of QTLs responsible for resistance to Xanthomonas axonopodis pv. phaseoli

2003 ◽  
Vol 28 (1) ◽  
pp. 5-10 ◽  
Author(s):  
Amaury S. Santos ◽  
Ricardo E. Bressan-Smith ◽  
Messias G. Pereira ◽  
Rosana Rodrigues ◽  
Claudia F. Ferreira
Keyword(s):  
Phaseolus Vulgaris ◽  
Common Bean ◽  
Linkage Map ◽  
Linkage Groups ◽  
Resistant Genotype ◽  
Xanthomonas Axonopodis ◽  
Low Degree ◽  
Phenotypic Variations ◽  
Genomic Regions ◽  
High Degree

Common bean (Phaseolus vulgaris) cultivars with a high degree of resistance to Xanthomonas axonopodis pv. phaseoli (Xap) are not available in Brazil. Despite many studies, a low degree of resistance to Xap continues to exist due to its complex genetic inheritance, which is not well known. The objectives of this research were to complement a common bean genetic map based on the cross between a susceptible genotype 'HAB-52' and a resistant genotype 'BAC-6', and to map and analyze genomic regions (quantitative trait loci – QTLs) related to Xap resistance. Eleven linkage groups were determined using 143 RAPD markers, covering 1,234.5 cM of the genome. This map was used to detect QTLs associated with Xap resistance on leaves and pods. The averages of disease severity on leaves (represented by the transformed disease index – TDI) and pods (represented by the diameter of lesion on pods – DLP) were added to the data of the linkage map. Five TDI QTLs and only one LDP QTL were detected. The TDI QTLs were placed in the A, B, G and J linkage groups, with phenotypic variations ranging from 12.7 to 71.6%. The DLP QTL explained 12.9% of the phenotypic variation and was mapped in a distinct linkage group. These results indicate that there are different genes involved in the control of resistance on leaves and pods.

scholarly journals Granulometry, heavy mineral and geochemical studies of stream sediments around Bula, Dass District, Northeast Nigeria

2020 ◽  
Vol 18 ◽  
pp. 63-73
Author(s):  
C. I. Adamu ◽  
E.E. Okon ◽  
D.O. Inyang
Keyword(s):  
Trace Elements ◽  
Stream Sediments ◽  
Stream Sediment ◽  
Heavy Mineral ◽  
Geochemical Data ◽  
Provenance Analysis ◽  
Sediment Samples ◽  
Granulometric Analysis ◽  
Elemental Analyses ◽  
Geochemical Studies

Active stream sediments generally consist of broken-down fragments of pre-existing rocks by the action of river (stream) flow. This makes them target materials for routine geochemical surveys and provenance analysis. Fifteen (15) stream sediment samples were collected in some parts of Bula and its environs, northeastern Nigeria, in order to determine their textural characteristics, heavy mineral and elemental composition. The sediments were subjected to granulometric, heavy mineral and elemental analyses. The result of granulometric analysis show that the streamsediments are poorly to moderately well sorted, very platykurtic to leptokurtic, fine to medium grained and positively skewed. Zircon, rutile and tourmaline are the dominant heavy mineral species occurring in the sediments. The computed Zircon-Tourmaline-Rutile (ZTR) index values for the samples range from 59.18 - 83.53, indicating mineralogical maturity. The geochemical data of the stream sediment samples show that the mean contents of the trace elements [Ti (0.73 ± 0.74%), Fe (0.39±0.19%), Cr (816±639ppm), Ni (258±108ppm), Pb (48±12.37ppm) and Zn (502±126ppm)] were higher than their respective average crustal values except for Fe. Computed threshold values indicate possible mineralization containing Fe and Ti. The elements have variable spatial distribution. The study shows that the trace elements composition of the stream sediments is majorly lithogenic. Because mineralization in rocks and sediments are often characterized by considerable variation in their trace elements contents, the metal concentrations in these sediments are large enough for Ilmenite and Rutile mineralization to be suspected within the study area.

scholarly journals TOLAK UKUR FUNGSI HATI BERDASARKAN DERAJAT FIBROSIS PENYAKIT HATI KRONIS (Liver Function Parameters based on Degree of Liver Fibrosis in Chronic Liver Disease)

2018 ◽  
Vol 21 (1) ◽  
pp. 57
Author(s):  
Rahmafitria Rahmafitria ◽  
Mutmainnah Mutmainnah ◽  
Ibrahim Abdul Samad
Keyword(s):  
Liver Disease ◽  
Liver Fibrosis ◽  
Liver Function ◽  
Chronic Liver Disease ◽  
Total Bilirubin ◽  
Chronic Liver ◽  
Low Degree ◽  
Significant Difference ◽  
The Mean ◽  
High Degree

Evaluating the degree of liver fibrosis degree is invasive as well as uncomfortable, therefore, non invasive examinations such as liverfunction tests and elastography (Fibro Scan) as a predictor‘s device of liver fibrosis degree are necessary. The aim of this study was toknow the differences of liver function parameters based on the fibrosis degree in patients with chronic liver disease. This study was a crosssectional design using data from chronic liver disease patients treated at the Dr. Wahidin Sudirohusodo Hospital. The elasticity of the liverwas measured using a fibro scan device during June 2010–July 2011. The analysis was carried out by ANOVA test on various parametersof liver function particularly on the fibrosis degree in chronic liver disease. In this study PT, albumin, total bilirubin and platelet countshowed a significant difference of 0.019, 0.009, 0.017 and 0.000 respectively. The mean values of PT and total bilirubin were significantlyhigher in the high degree of fibrosis compared to those with medium and low degree of fibrosis in the chronic liver disease patients. Basedon this study, the mean albumin levels and platelet count were significantly lower in the high degree of fibrosis compared with the mediumand low degree of fibrosis, however, no significant differences in AST, ALT, APTT and GGT were found.

scholarly journals A PERFORMANCE ANALYSIS OF REGIONAL BUDGET OF JAYAWIJAYA REGENCY FROM 2010 TO 2014

2017 ◽  
Vol 1 (3) ◽  
Author(s):  
Didi Yigibalom ◽  
Ida Ayu Purba Riani
Keyword(s):  
Central Government ◽  
Fiscal Decentralization ◽  
Overlay Analysis ◽  
External Funding ◽  
Revenue Growth ◽  
Low Degree ◽  
Regional Budget ◽  
Variant Analysis ◽  
High Degree ◽  
Budget Revenue

This study aims to assess performance of Regional Budget (APBD) which includes revenues, spending/expenditures and financing activities of Jayawijaya Government. The data used was the budgeted and realization of Revenue, Spending/Expenditure and Financing activities of Jayawijaya regency from 2010 to 2014. The analysis techniques used was a qualitative approach through various financial ratios. To calculate revenues performance this study employed Variant Analysis (differences of) Budget Revenue, Revenue Growth, Degree of Independence of the region, Regional Reliance to the central government, Degree of Decentralization, Local Tax Effectiveness and Overlay analysis to measure performance of the generated income. Meanwhile to measure expenditure used Variant Analysis (difference) Budgeted Expenditure, Growth of Regional Expenditure, Synchronization of Governmental Spending, Spending Effectiveness and Overlay analysis to measure overall spending/expenditures performance. Following the analysed data, the study obtained following results: 1) Jayawijaya’s revenue performance during 2010 to 2014 based on the overlay analysis was not good. The main caused was due to low degree of the region financial independence, high degree of fiscal dependence for external funding as well as the low degree of fiscal decentralization, 2) Spending/Expenditure Performance of Jayawijaya from 2010 to 2014 was good. This was because of the increasing growth of Jayawijaya’s spending/expenditure and the effectiveness of spending/expenditure in Jayawijaya. Keywords: Budget, Revenue, Spending/ Expenditure, Regional Budget Performance

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