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Journal of Geoscience and Environment Protection 2022年第1期10卷 13-28页

作者： Stephen Twumasi Annan Bright Frimpong collins owusu-fordjour Bismark Yeboah Boasu Department of Integrated Science Education Faculty of Science Education University of Education Winneba Ghana Department of Programmes Planning Monitoring and Evaluation Environmental Protection Agency Accra Ghana Department of Environment and Resource Studies SD Dombo University of Business and Integrated Development Studies Wa Ghana

The study assesses the quality of hand dug wells in relation to distance from soakaway septic tanks in three selected peri-urban communities in the Ga West Municipality near Accra, Ghana. Water quality analyses of bio-physico-chemical variables (pH, Temperature, EC, turbidity, DO, BOD, TSS, TDS, sodium, potassium, nitrate, nitrite, ammonia, sulphate, chloride, salinity, total alkalinity, total coliform, fecal coliforms and isolation of E. coli) were determined. Concentrations of the major nutrient anion sulphate, nitrate, phosphate, and chlorides in water samples at distances between 0 - 30 m radial distances from the septic tank were above the WHO permissible limit of drinking water compared to the control. All the water samples had high fecal and total coliform counts that exceeded the international standard of 0 per 100 mL of potable water with counts ranging from 0 - 143 cfu/100 ml and 53 - 463/100 ml for FC and TC respectively. High fecal coliform and detection of E. coli in most samples is an indication of fecal pollution possibly from their close proximity to soak away septic sewage. The high nutrient levels detected in samples at distances between 0 - 30 m as compared to the controls may a

关键词： Groundwater Water Quality Localized Contamination Peri-Urban

Plant-available water capacity of soils at a regional scale:Analysis of fixed and dynamic field capacities

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Pedosphere 2024年第3期34卷 590-605页

作者： Vinod PHOGAT Paul RPETRIE Casandra collins Marcos BONADA South Australian Research and Development Institute GPO Box 397Adelaide SA 5001(Australia) School of Agriculture Food and WineWaite Research InstituteUniversity of AdelaideWaite CampusPMB1Glen Osmond SA 5064(Australia) College of Science and Engineering Flinders UniversityBedford Park SA 5042(Australia) The University of New South Wales Sydney NSW 2052(Australia) ARC Training Centre for Innovative Wine Production University of AdelaidePMB1Glen Osmond SA 5064(Australia)

Estimation of the plant-available water capacity(PAWC)of soils at a regional scale helps in adopting better land use planning,developing suitable irrigation schedules for crops,and optimizing the use of scarce water *** the current study,72 soil profiles were sampled from the Barossa region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil *** functions were then used to estimate the fixed(10 and 33 kPa)and dynamic pressure head(h_(fc))water contents at field capacity(FC)for minimum drainage flux(0.01 and 0.001 cm d^(-1)),which serves as the upper boundary for plant-available water in *** estimated residual water content was corrected for subsoil constraints,especially the exchangeable sodium percentage(ESP).The results showed that the mean values of h_(fc)in sand-dominated light and medium textured soils(i.e.,sand,loamy sand,sandy loam,and loam)varied in a narrow range(15.8-18.2 kPa),whereas those in the clay-dominated heavy textured soils(i.e.,clay loam)showed a wide range(11.3-49.3 kPa).There were large differences in PAWC for dynamic FC(PAWC_(fc))and fixed FC at 10 kPa(PAWC10),33 kPa(PAWC33),and a mix of 10and 33 kPa(PAWC_(10,33))pressure heads depending on soil ***,the difference between PAWC at 10 kPa and h_(fc)(ΔPAWC_(10))was positive,whereas that between 33 kPa and h_(fc)(ΔPAWC_(33))was negative across all ***,the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures(i.e.,PAWC_(10,33))for sandy,clay,and silty soils reduced the difference between fixed and dynamic pressure PAWCs to<10% across the *** estimation of PAWC was improved by incorporating the impact of subsoil constraints,such as high ESP,which was more pronounced for clay and silty *** findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic FC estimations in *** heterogeneity,intra-texture variability,subsoil constraints,and swell

关键词： crop lower limit drained upper limit pedo-transfer function soil hydraulic parameter soil texture

Modelling the brittle rock failure by the quaternion-based bonded-particle model in DEM

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Rock Mechanics Bulletin

Rock Mechanics Bulletin 2024年第2期3卷 87-95页

作者： Tao Zhao Philip E.F.collins Department of Civil and Environmental Engineering Brunel University LondonLondonUB83PHUnited Kingdom

This paper presents an investigation of brittle rock failure by the quaternion-based bonded-particle model in discrete element method(DEM).Unlike traditional approaches that utilize Euler angles or rotation matrices,this model employs unit quaternions to represent the spatial rotations of *** method simplifies the rep-resentation of 3D rotations,providing a more intuitive framework for modelling complex interactions in granular *** numerical model was validated by the uniaxial compression tests on rock,with good agreement with well-documented experimental data in terms of the rock uniaxial compression strength(UCS)and failure *** loading,the rock sample demonstrated a linear-elastic response at an axial strain of smaller than 0.45%.However,as internal bond breakage accumulated,this linear relationship weakened,and the stress-strain curve began to deviate from its initial linear *** bond breakage and the overall deformation of the rock were primarily controlled by the shear bonding *** UCS was achieved at an axial strain of 0.625%,at which point the internal shear bonding force chains were predominantly aligned *** brittle failure occurred when the internal damage of solids nucleated to form an interconnected failure plane,accompanied by a sharp rise in the internal damage *** area of failure plane increased with the loading strain rate,gradually transforming the failure pattern from the local damage to a complete fragmentation.

关键词： Brittle failure Quaternion DEM bonded model Uniaxial compression test Rate dependent Internal damage

Development and characterization of 3D-printed electroconductive pHEMA-co-MAA NP-laden hydrogels for tissue engineering

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Bio-Design and Manufacturing 2024年第3期7卷 262-276页

作者： Sara De Nitto Aleksandra Serafin Alexandra Karadimou Achim Schmalenberger John J.EMulvihill Maurice N.collins DIBRIS Polytechnic Inter-School Section University of Genoa16126 GenoaItaly School of Engineering Bernal InstituteUniversity of LimerickLimerick V94 T9PXIreland School of Natural Sciences Department of Biological SciencesUniversity of LimerickLimerick V94 T9PXIreland Health Research Institute University of LimerickLimerick V94 T9PXIreland AMBER University of LimerickLimerick V94 T9PXIreland

Tissue engineering(TE)continues to be widely explored as a potential solution to meet critical clinical needs for diseased tissue replacement and tissue *** this study,we developed a poly(2-hydroxyethyl methacrylate-co-methacrylic acid)(pHEMA-co-MAA)based hydrogel loaded with newly synthesized conductive poly(3,4-ethylene-dioxythiophene)(PEDOT)and polypyrrole(PPy)nanoparticles(NPs),and subsequently processed these hydrogels into tissue engineered constructs via three-dimensional(3D)*** presence of the NPs was critical as they altered the rheological properties during ***,all samples exhibited suitable shear thinning properties,allowing for the development of an optimized processing window for 3D *** were 3D printed into pre-determined disk-shaped configurations of 2 and 10 mm in height and diameter,*** observed that the NPs disrupted the gel crosslinking efficiencies,leading to shorter degradation times and compressive mechanical properties ranging between 450 and 550 *** conductivity of the printed hydrogels increased along with the NP concentration to(5.10±0.37)×10^(−7)S/*** vitro studies with cortical astrocyte cell cultures demonstrated that exposure to the pHEMA-co-MAA NP hydrogels yielded high cellular viability and proliferation ***,hydrogel antimicrobial studies with staphylococcus epidermidis bacteria revealed that the developed hydrogels affected bacterial *** together,these materials show promise for various TE strategies.

关键词： Conductive nanoparticles Hydroxyethyl methacrylate(HEMA) Ultraviolet(UV)polymerization 3D printing

Correlative Thinking in the Yijing: Impossibility of English Translation

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走进孔子(中英文) 2024年第5期 120-128页

作者： Eris collins the Special Training Program in Comparative Philosophical Hermeneutics at Nishan Birthplace of the Sage Academy

Introduction The Yijing易经,or Book of Changes,is said to be the most influential philosophical text of the ancient classics of *** over 2000 years ago,initially it was a manual for divination(the Zhouyi),and later the appendices were added,which created the foundation for Neo-Confucian(SongMing Confucianism) cosmology and"metaphysics"(although in abstraction from human experience).

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Assessment of Occupational Radiation Exposure for Radiotherapy Healthcare Workers at Kenyatta National Hospital Using Thermoluminescence Dosimeter LiF:Mg,Ti

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Journal of Geoscience and Environment Protection 2024年第7期12卷 14-24页

作者： collins Omondi Margaret Chege Samson Omondi Department of Physics Kenyatta University Nairobi Kenya College of Health Physics Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya

Kenyatta National Hospital (KNH) is the largest public referral hospital with a comprehensive cancer treatment facility in East and Central Africa. Occupational radiation monitoring is a significant technique for demonstrating compliance of radiation regulatory limits. The objective of the study was to carry out assessment of occupational radiation exposure among radiotherapy personnel at KNH using thermoluminescence dosimeter, TLD. KNH staff were monitored using dosimeter type TLD-100 made of LiF:Mg,Ti, on monthly basis. The reader system used for analysis was Harshaw 8800. The measurement established the average monthly accumulated occupational personnel dose for KNH to be 0.21 mSv and 0.29 mSv for Hp (10) and Hp (0.07) respectively. The accumulated dose results were within the maximum acceptable dose of 1.67 mSv/month and 41.6 mSv/month for Hp (10) and Hp (0.07) respectively. The investigation results were higher than the acceptable public limit of 0.08 mSv/month. Moreover, incidences were noted where the fetus dose limit 0.42 was also exceeded. Evaluation of statistical dose exposure among doctors, nurses and radiographers’ measurement results were within ±0.02 mSv. The study established the average KNH occupational radiation exposure levels for both Hp (10) and Hp (0.07) were within the ICRU recommendation, validating radiation protection safe practice. Data analysis of healthcare workers did not indicate exposure trend biased to any healthcare profession. Hence radiation risk cut across all professional categories. It is recommended that Radiation Monitoring program be reviewed to include non-clinical staff who access the facility. Radiation reporting should not be limited to one facility, but reflect cases where workers are involved in multiple multiple jobs.

关键词： Occupational Monitoring Exposure Thermoluminescence Dosimeter and Radiotherapy

Evaluation of Dosimetric Impact of Uncertainty of Measurement in Estimating External Radiotherapy Dose

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Open Journal of Applied Sciences 2024年第8期14卷 1985-1995页

作者： collins Omondi Margaret Chege Samson Omondi Physics Department Kenyatta University Nairobi Kenya College of Health Physics Jomo Kenyatta University of Agriculture and Technology Juja Kenya

Cancer is a major societal public health and economic problem, responsible for one in every six deaths. Radiotherapy is the main technique of treatment for more than half of cancer patients. To achieve a successful outcome, the radiation dose must be delivered accurately and precisely to the tumor, within ± 5% accuracy. Smaller uncertainties are required for better treatment outcome. The objective of the study is to investigate the uncertainty of measurement of external radiotherapy beam using a standard ionization chamber under reference conditions. Clinical farmers type ionization chamber measurement was compared against the National Reference standard, by exposing it in a beam 60Co gamma source. The measurement set up was carried out according to IAEA TRS 498 protocol and uncertainty of measurement evaluated according to GUM TEDDOC-1585. Evaluation and analysis were done for the identified subjects of uncertainty contributors. The expanded uncertainty associated with 56 mGy/nC ND,W was found to be 0.9% corresponding to a confidence level of approximately 95% with a coverage factor of k = 2. The study established the impact of dosimetry uncertainty of measurement in estimating external radiotherapy dose. The investigation established that the largest contributor of uncertainty is the stability of the ionization chamber at 36%, followed by temperature at 22% and positioning of the chamber in the beam at 8%. The effect of pressure, electrometer, resolution, and reproducibility were found to be minimal to the overall uncertainty. The study indicate that there is no flawless measurement, as there are many prospective sources of variation. Measurement results have component of unreliability and should be regarded as best estimates of the true value. .

关键词： Absorbed Dose to Water Radiotherapy Uncertainty of Measurement Secondary Standards Dosimetry Laboratory Ionizing Chamber

Unifying concepts in methanogenic,aerobic,and anammox sludge granulation

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Environmental Science and Ecotechnology 2024年第1期17卷 17-30页

作者： Simon Mills Anna Christine Trego Marco Prevedello Jo De Vrieze Vincent O’Flaherty Piet N.L.Lens Gavin collins Microbial Communities Laboratory School of Biological and Chemical SciencesNational University of Ireland GalwayUniversity RoadGalwayH91 TK33Ireland Microbial Ecology Laboratory School of Biological and Chemical Sciences University of GalwayUniversity RoadGalwayH91 TK33Ireland Center for Microbial Ecology and Technology(CMET) Ghent UniversityCoupure Links 653B-9000GentBelgium University of Galway University RoadGalwayH91 TK33Ireland

The retention of dense and well-functioning microbial biomass is crucial for effective pollutant removal in several biological wastewater treatment *** solids retention is often achieved through aggregation of microbial communities into dense,spherical aggregates known as granules,which were initially discovered in the *** granules have since been widely applied in upflow anaerobic digesters for waste-to-energy ***,granular biomass has been applied in aerobic wastewater treatment and anaerobic ammonium oxidation(anammox)*** mechanisms underpinning the formation of methanogenic,aerobic,and anammox granules are the subject of ongoing *** each granule type has been extensively studied in isolation,there has been a lack of comparative studies among these granulation *** is likely that there are some unifying concepts that are shared by all three sludge *** these unifying concepts could allow a unified theory of granulation to be ***,we review the granulation mechanisms of methanogenic,aerobic,and anammox granular sludge,highlighting several common concepts,such as the role of extracellular polymeric substances,cations,and operational parameters like upflow velocity and shear *** have then identified some unique features of each granule type,such as different internal structures,microbial compositions,and quorum sensing ***,we propose that future research should prioritize aspects of microbial ecology,such as community assembly or interspecies interactions in individual granules during their formation and growth.

关键词： Granule Granulation Anaerobic digestion Anammox Aerobic granule

Evaluation of Air-Kerma and Absorbed Dose to Water for External Radiotherapy Beam Using Ionization Chamber

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Open Journal of Radiology 2024年第3期14卷 113-124页

作者： collins Omondi Margaret Chege Samson Omondi Kenyatta University Nairobi Kenya Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya

Radiotherapy is the most widely applied oncologic treatment modality utilizing ionizing radiation. A high degree of accuracy, reliability and reproducibility is required for a successful treatment outcome. Measurement using ionization chamber is a prerequisite for absorbed dose determination for external beam radiotherapy. Calibration coefficient is expressed in terms of air kerma and absorbed dose to water traceable to Secondary Standards Dosimetry Laboratory. The objective of this work was to evaluate the level of accuracy of ionization chamber used for clinical radiotherapy beam determination. Measurement and accuracy determination were carried out according to IAEA TRS 398 protocol. Clinical farmers type ionization chamber measurement and National Reference standard from Secondary Standards Dosimetry Laboratory were both exposed to cobalt-60 beam and measurement results compared under the same environmental conditions. The accuracy level between National Reference Standard and clinical radiotherapy standard was found to be −1.92% and −2.02% for air kerma and absorbed dose to water respectively. To minimize the effect of error and maximize therapeutic dose during treatment in order to achieve required clinical outcome, calibration factor was determined for air kerma (Nk) as 49.7 mGy/nC and absorbed dose to water ND, as 52.9 mGy/nC. The study established that radiotherapy beam measurement chain is prone to errors. Hence there is a need to independently verify the accuracy of radiation dose to ensure precision of dose delivery. The errors must be accounted for during clinical planning by factoring in calibration factor to minimize the systematic errors during treatment, and thereby providing enough room to achieve ±5% dose delivery to tumor target as recommended by ICRU.

关键词： Absorbed Dose to Water Air Kerma Co-60 Source Calibration SSDL Radiotherapy Beam Metrology Accuracy and Accuracy

地球演化历史中氧逸度变化对壳幔循环启动、风化和超大陆循环的指示

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Science Bulletin 2024年第1期69卷 97-102页

作者：王瑞邬绍宸 Roberto F.Weinberg William J.collins Peter A.Cawood State Key Laboratory of Geological Processes and Mineral Resources Institute of Earth SciencesChina University of GeosciencesBeijing 100083China Frontiers Science Center for Deep-time Digital Earth China University of Geosciences(Beijing)Beijing 100083China School of Earth Atmosphere and EnvironmentMonash UniversityClayton VIC 3800Australia The Institute for Geoscience Research Curtin UniversityPerth WA 6102Australia

We apply a zircon redox index to a global compilation of detrital zircons to track the variation of oxidation state,expressed asΔFMQ,through Earth's *** from I-type rocks,which comprise mantle and crustal igneous protoliths,including tonalite–trondhjemite–granodiorites(TTGs),generally have a high oxidation state(ΔFMQ>0).In contrast,zircons from igneous rocks derived from supracrustal source rocks(S-type)are commonly reduced(ΔFMQ0 over the last 3 *** that the redox state of magmas is independent of crustal thickness and silica variation,and elevated values are likely more closely related to tectonic setting,we suggest that the consistent averageΔFMQ>0 from ca.3.5 Ga onwards relates to recycling of oceanic lithosphere back into the mantle in what eventually became established as subduction *** more reduced magmas associated with sedimentary sources,became established at 2.6 Ga,presumably in response to continental rocks rising above sealevel,and follow peaks of productivity associated with the supercontinent cycle.

关键词： Oxidation state Supercontinent Weathering Subduction Zircon Granite