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Chinese Journal Of Geochemistry 2005年第2期24卷 129-135页

作者： ukaegbu v.u. EKWuEME B.N. Department of Geology University of Port Harcourt Port Harcourt NigeriaDepartment of Geology University of Calabar Calabar Nigeria.

Rock samples representing various igneous and metamorphic rocks of southern Obudu Plateau were analyzed for rare-earth element (REE) behavior by ICP-MS. Results of the analyses indicate a range of REE abundances and distinctive patterns from highly fractionated patterns with negative Eu anomalies in granitic rocks to relatively low abundances and less REE fractionated flat patterns with little Eu anomaly in some paragneisses, schists, enderbites and dolerites to unfractionated patterns with positive Eu anomalies in some paragneisses and charnockites. Over all, there are low to high ∑REE contents with negative to positive Eu anomalies. The ratios of different parameters, especially La/Yb and Ce/Yb, show behaviors consistent with crustal to mantle derivation. The heterogeneity of REE abundances and REE patterns reflects mantle to crustal petrogenetic variations of different rock suites on the Plateau. The LREE content is higher than the HREE content in the highly differentiated rocks, as evidenced by their La/Yb, Ce/Yb and La/Sm ratios, which are normally higher in residual products than in primary melts. The dominantly intermediate nature of the source rock of the orthogneisses is suggested by the generally low {∑REE}. The granites enriched in LREE and depleted in HREE and some of the charnockites with negative Eu anomalies were probably formed by partial melting and crystallization.

关键词：稀土元素地球化学丰度 Obudu高原变质岩

Trace and rare-earth element geochemistry: A tool for petrogenetic and geotectonic modeling of ensimatic ortho-amphibolites from Pan-African belt of Obudu Plateau, Southeastern Nigeria

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Chinese Journal Of Geochemistry 2009年第1期28卷 19-27页

作者： ukaegbu v.u. Beka F.T. Department of Geology University of Port Harcourt Port Harcourt Nigeria

A model for the petrogenetic affinity and original geotectonic setting of ortho-amphibolites from the Obudu Plateau was tested using the distribution patterns of trace and rare-earth elements from the geochemical analyses of twelve representative amphibolite samples. Discrimination plots, normalized patterns of the incompatible trace elements against average MORB, low ratios of Ba/Nb (9–23) and Ba/Ta (130–327) and other geochemical characteristics suggest that the protoliths were dominantly of tholeiitic MORB composition. The values of the ratios of La/Ta (8.13–10.8), Rb/Sr (0.04–0.07), Th/u (mainly 4.43–5.43) and Hf/Ta (2.35–2.88) further indicate that the ortho-amphibolites demonstrate E-type MORB characteristics. These features are related to substantial ocean floor divergent tectonic boundary setting rather than marginal basin tectonic setting. This evolutionary pattern appears to be controlled by limited progressive partial melting and fractional crystallization of a single mantle source region, irrespective, however, of variations due to local source heterogeneities. The tholeiitic magmas were most probably generated by hotspot activities on the constructive plate margins and subsequently modified by subduction-related low-K tholeiitic chemistry due to narrowing of a proto oceanic basin between the West African craton and eastern Sahara plate. A likely model, therefore, is that the amphibolites of the Obudu Plateau represent ophiolitic suites with characteristics of enriched mid-ocean floor tholeiites, which were deformed and metamorphosed during a reversed plate motion involving subduction and collision within the Obudu Plateau in the Pan-African orogenic episode.

关键词： REE 微量元素地面沉陷角闪岩地球化学

Rare-earth and trace element imprints on the origin and tectonic setting of gabbro-diorite complex in the Pan-African belt of Southeast Obudu Plateau,Nigeria

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Chinese Journal Of Geochemistry 2009年第3期28卷 239-247页

作者： ukaegbu v.u. Beka F.T. Department of Geology University of Port HarcourtPort HarcourtNigeria

A gabbro-diorite plutonic complex from the Southeast Obudu Plateau, representing limited volumes of magma, was studied for its trace and rare-earth element characteristics, in an attempt to document its genetic and geodynamic history. Geochemical studies indicate that the gabbro samples are characterized by variable concentrations and low averages of such index elements as Cr (40×10-6–200×10-6; av. 80×10-6), Ni (40×10-6–170×10-6; 53.33×10-6) and Zr (110×10-6–240×10-6; 116.67×10-6); variable and high averages of Rb (3×10-6–270×10-6; 80.67×10-6), Sr (181×10-6–1610×10-6; 628.17×10-6) and u (0.14×10-6–3.46×10-6; 1.51×10-6), and fairly uniform Co (34×10-6–49×10-6; 36.33×10-6) and Sc (23×10-6–39×10-6; 34.5×10-6), while the diorite samples exhibit higher trace element compositions. The range of REE contents and distinctive chondrite-normalized patterns indicate moderate fractionation with slight positive Eu anomaly in the diorites to very low fractionation with flat patterns and slight positive Eu anomaly in the gabbros. However, the general element systematics of the samples, especially LILE (Ba, Rb, Sr, Cs and Pb), HFSE (Zr, Th, u, Hf, Mo, W, Nb and Sn), relatively immobile elements (Zr, Ni, Cr) and REE, suggests a differentiation model, involving fractional crystallization of olivine and clinopyroxene from a partial melt generated beneath an island arc complex. A possible model for the complex is therefore an island arc setting, the development of which was dominated by calc-alkaline magmatism across the Obudu Plateau.

关键词：构造环境微量元素尼日利亚辉长岩闪长岩起源高原痕迹

Petrology and geochemical characteristics of Precambrian granitic basement complex rocks in the southernmost part of North-Central Nigeria

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Chinese Journal Of Geochemistry 2009年第4期28卷 377-385页

作者： Obiora S.C. ukaegbu v.u. National Geophysical Research Institute Geological Studies DivisionUppal Road Hyderabad-500007 India Department of Geology University of NigeriaNsukka Nigeria Department of Geology University of Port HarcourtPort Harcourt Nigeria

The Precambrian basement complex in the southernmost part of North-Central Nigeria is underlain by migmatitic banded gneisses, granitic intrusions and dykes of dolerite, rhyolite porphyry and pegmatite. The rocks are generally felsic, containing modal and normative hypersthene, as well as normative corundum. The basement complex has experienced high-grade regional metamorphism as indicated by the presence of hypersthene and plagioclase of andesine composition. Anatectic melting is suggested by the occurrence of ptygmatic folds, folded gneissose foliation, numerous quartzo-feldspathic veins and lenses of dark-colured, micaceous schistose rocks. Geochemically, the rocks have magnesian, calc-alkalic and strongly peraluminous characteristics. Their overall characteristics suggest derivation from progressive (fractional) partial melting of pelitic rocks during high-grade regional metamorphism, possibly associated with intense hydrothermal activities. The magnesian characteristics reflect close affinity to relatively hydrous, oxidizing melts and source regions in settings broadly related to subduction.

关键词：岩石地球化学特征前寒武纪基底尼日利亚花岗岩中央区域变质作用流纹斑岩叶状结构

Rare-earth elements as source indicators of Pan-African granites from Obudu Plateau,Southeastern Nigeria

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Chinese Journal Of Geochemistry 2008年第2期27卷 130-134页

作者： ukaegbu v.u. Beka F.T. Department of Geology University of Port HarcourtPort HarcourtNigeria

The rare-earth element (REE) concentrations of representative granite samples from the southeast of the Obudu Plateau, Nigeria, were analyzed with an attempt to determine the signatures of their source, evolutionary history and tectonic setting. Results indicated that the granites have high absolute REE concentrations (190×10-6-1191×10-6; av.=549×10-6) with the chondrite-normalized REE patterns characterized by steep negative slopes and prominent to slight or no negative Eu anomalies. All the samples are also characterized by high and variable concentrations of the LREE (151×10-6-1169×10-6; av.= 466×10-6), while the HREE show low abundance (4×10-6-107×10-6; av.=28×10-6). These are consistent with the variable levels of REE fractionation, and differentiation of the granites. This is further supported by the range of REE contents, the chondrite-normalized patterns and the ratios of LaN/YbN (2.30-343.37), CeN/YbN (5.94-716.87), LaN/SmN (3.14-11.68) and TbN/YbN (0.58-1.65). The general parallelism of the REE patterns, suggest that all the granites were comagmatic in origin, while the high Eu/Eu* ratios (0.085-2.807; av.=0.9398) indicate high fO2 at the source. Similarly, irregular variations in LaN/YbN, CeN/YbN and Eu/Eu* ratios and REE abundances among the samples suggest behaviors that are related to mantle and crustal sources.

关键词：指示剂稀土元素非洲花岗岩

Petrogenesis and geotectonic setting of the Pan-African basement rocks in Bamenda Massif, Obudu Plateau, southeastern Nigeria: Evidence from trace element geochemistry

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Chinese Journal Of Geochemistry 2006年第2期25卷 122-131页

作者： ukaegbu v.u.EKWuEME B.N Department of Geology University of Port Harcourt Port Harcourt Nigeria Department of Geology University of Calabar Calabar Nigeria

The rocks of the Obudu Plateau range from high-grade metagreywacke-pelite sequence to metaigneous (granitic to tholeiitic) and polymagmatic (calc-alkaline granitic to olivine tholeiitic) igneous rocks. Several co-variance diagrams and other parameters indicate that the trace elements of rocks in southern Obudu Plateau exhibit systematic variations and suggest highly heterogeneous protoliths. The tectonic setting of the rocks indicates rifting and collisional to non-orogenic emplacements in oceanic to ensialic environments. The calc-alkaline and tholeiitic nature of the magmatism as well as the greywacke-pelite sequence is suggestive of an Andean-type continental environment.

关键词：微量元素岩石成因论地壳构造花岗岩橄榄石

Old-growth mixed dipterocarp forests show variable losses and gains in aboveground biomass and standing carbon over forty years

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Forest Ecosystems 2024年第1期11卷 14-23页

作者： Sisira Ediriweera Champika Bandara Tithira Lakkana Shanika Jayasinghe David Woodbury Arun Dayanandan B.M.P.Singhakumara Xiangcheng Mi I.A.u.N.Gunatilleke C.v.S.Gunatilleke Mark SAshton Department of Science and Technology Uva Wellassa UniversityBadullaSri Lanka The Forest School Yale School of the EnvironmentYale UniversityNew HavenCT06511USA Department of Forestry and Environmental Science University of Sri JayewardenepuraNugegodaSri Lanka State Key Laboratory of vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing100093China Botany Department University of PeradeniyaPeradeniyaSri Lanka

Background:No studies have documented long-term trends in aboveground biomass(AGB)for mixed-dipterocarp forests(MDF),the dominant rain forest type in tropical wet equatorial Asia.In our study,we sought to document such trends over forty years across three sites representing lowland to lower montane elevations.Methods:To do this,we established fifty 100 m×25 m plots in 1978 across three sites sampled along an elevation gradient,identified as mature old-growth forest.We measured trees for diameter at breast height that we identified to species and tagged.We took wood samples to calculate species wood-specific gravity.We re-measured plots in 1998 and again in 2018.Results:We show standing AGB for all sites combined to be 517.52 Mg·ha^(-1)in 1978,but this declined by 17%over 40 years to 430.11 Mg·ha^(-1).No differences exist among sites in AGB primarily because of considerable within site variation;but interactions of time with site show declines across sites were not uniform,one remained about the same.Relatively few species represented a high proportion of the AGB with the top five species comprising between 34%and 65%,depending upon site and year sampled.One species,Mesua nagassarium,represented a disproportionately large amount of AGB and decline over time,particularly at the low elevation site.Conclusions:Our results are directly relevant to estimating AGB and standing carbon sequestered in MDF.Our study is the first to demonstrate varying but overall,declining trends in amounts of AGB among forests making predictions of biomass and standing carbon in MDF difficult over wide regions.

关键词： Western ghats Shorea spp. Southeast Asia Sri Lanka Tropical rain forest Wood specific gravity

How the Flat Space Cosmology Model Correlates the Recombination CMB Temperature of 3000 K with a Redshift of 1100

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Journal of Modern Physics 2024年第2期15卷 174-178页

作者： Eugene Terry Tatum u. v. S. Seshavatharam Independent Researcher Bowling Green Kentucky USA I-SERvE Hitech City Hyderabad India

This paper shows how the Flat Space Cosmology model correlates the recom-bination epoch CMB temperature of 3000 K with a cosmological redshift of 1100. This proof is given in support of the recent publication that the Tatum and Seshavatharam Hubble temperature formulae can be derived using the Stephan-Boltzmann dispersion law. Thus, as explained herein, the era of high precision Planck scale quantum cosmology has arrived.

关键词： Hubble Constant Cosmic Microwave Background Quantum Cosmology Stephan-Boltzmann upsilon Coupling Constant Flat Space Cosmology ΛCDM Cosmology

Inhibition of Ehrlich ascites carcinoma growth by melatonin:Studies with micro-CT

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Oncology Research 2024年第1期32卷 175-185页

作者： SEHER YILMAZ ZÜLEYHA DOĞANYIĞIT MERT OCAK EvRIM SuNA ARIKAN SÖYLEMEZ ASLI OKAN OFLAMAZ SÜMEYYE uÇAR ŞÜKRÜATEŞ AMMAD AHMAD FAROOQI Department of Anatomy Faculty of MedicineYozgat Bozok UniversityYozgatTurkey Department of Mechanical and Aerospace Engineering Case Western Reserve UniversityClevelandOhioUSA Department of Histology and Embriology Faculty of MedicineYozgat Bozok UniversityYozgatTurkey Department of Anatomy Faculty of DentistryAnkara UniversityAnkaraTurkey Department of Medical Biology Faculty of MedicineAfyonkarahisar Health Sciences UniversityAfyonTurkey Department of Anatomy Faculty of MedicineErciyes UniversityKayseriTurkey Department of Molecular Oncology Institute of Biomedical and Genetic Engineering(IBGE)IslamabadPakistan

Melatonin is a versatile indolamine synthesized and secreted by the pineal gland in response to the photoperiodic information received by the retinohypothalamic signaling pathway.Melatonin has many benefits,such as organizing circadian rhythms and acting as a powerful hormone.We aimed to show the antitumor effects of melatonin in both in vivo and in vitro models through the mammalian target of rapamycin(mTOR)signaling pathway and the Argyrophilic Nucleolar Regulatory Region(AgNOR),using the Microcomputed Tomography(Micro CT).Ehrlich ascites carcinoma(EAC)cells were administered into the mice by subcutaneous injection.Animals with solid tumors were injected intraperitoneally with 50 and 100 mg/kg melatonin for 14 days.volumetric measurements for the taken tumors were made with micro-CT imaging,immunohistochemistry(IHC),real-time polymerase chain reaction(PCR)and AgNOR.Statistically,the tumor tissue volume in the Tumor+100 mg/kg melatonin group was significantly lower than that in the other groups in the data obtained from micro-CT images.In the IHC analysis,the groups treated with Tumor+100 mg/kg melatonin were compared when the mTOR signaling pathway and factor 8(F8)expression were compared with the control group.It was determined that there was a significant decrease(pund in the total AgNOR area/nuclear area(TAA/NA)ratio in the treatment groups(purthermore,there were significant differences between the amount of mTOR mRNA for the phosphatidylinositol 3-kinase(PI3K),AKT Serine/Threonine Kinase(PKB/AKT)genes(pvaluated with Annexin v in an in vitro study with different doses of melatonin;It was observed that 100µg/mL melatonin dose caused an increase in the apoptotic cell death.In this study,we have reported anti-tumor effects of melatonin in cell culture studies as well as in mice models.Comprehensive characterization of the melatonin-mediated cancer inhibitory effects will be valuable in advancing our fundamental molecular understanding and

关键词： Signaling pathway Apoptosis Real-time PCR AgNOR

An examination of thematic research,development,and trends in remote sensing applied to conservation agriculture

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International Soil and Water Conservation Research 2024年第1期12卷 77-95页

作者： Zobaer Ahmed Aaron Shew Lawton Nalley Michael Popp v.Steven Green Kristofor Brye Center for Advanced Spatial Technologies University of ArkansasFayettevilleARUSA Environmental Dynamics Program University of ArkansasFayettevilleARUSA Department of Agricultural Economics and Agribusiness University of ArkansasFayettevilleARUSA College of Agriculture Arkansas State UniversityJonesboroARUSA university of Arkansas System Division of Agriculture Little RockARUSA Department of Crop Soiland Environmental SciencesUniversity of ArkansasFayettevilleARUSA

Conservation agriculture seeks to reduce environmental degradation through sustainable management of agricultural land.Since the 1990s,agricultural research has been conducted using remote sensing technologies;however,few previous reviews have been conducted focused on different conservation management practices.Most of the previous literature has focused on the application of remote sensing in agriculture without focusing exclusively on conservation practices,with some only providing a narrative review,others using biophysical remote sensing for quantitative estimates of the bio-geo-chemical-physical properties of soils and crops,and few others focused on single agricultural management practices.This paper used the preferred reporting items for systematic review(PRISMA)methodology to examine the last 30 years of thematic research,development,and trends associated with remote sensing technologies and methods applied to conservation agriculture research at various spatial and temporal scales.A set of predefined key concepts and keywords were applied in three databases:Scopus,Web of Science,and Google Scholar.A total of 188 articles were compiled for initial examination,where 68 articles were selected for final analysis and grouped into cover crops,crop residue,crop rotation,mulching,and tillage practices.Publications on conservation agriculture research using remote sensing have been increasing since 1991 and peaked at 10 publications in 2020.Among the 68 articles,94%used a pixel-based,while only 6%used an object-based classification method.Prior to 2005,tillage practices were abundantly studied,then crop residue was a focused theme between 2004 and 2012.From 2012 to 2020,the focus shifted again to cover crops.Ten spectral indices were used in 76%of the 68 studies.This examination offered a summary of the new potential and identifies crucial future research needs and directions that could improve the contribution of remote sensing to the provision of long-term operational services for various conservation agricult

关键词： Remote sensing Conservation agriculture Classification algorithm Spatial resolution Satellite Spectral indices PRISMA