Internal Cycling Research Articles

Ecosystem changes in eight Danish lakes after zebra mussel invasion

AbstractInvasion of zebra mussels (Dreissena polymorpha) can have profound effects on lake ecosystems. We investigated the overall ecological effects after invasion and fast expansion of zebra mussels in eight lakes in Denmark belonging to the same watercourse systems but with different morphological and eutrophication characteristics. A few years after the invasion, most of the lakes had experienced profound changes in lake water quality, e.g. chlorophyll a had been reduced by 18–62% and Secchi depth had increased by 38–171%. Nutrient concentrations also decreased, total phosphorus to 37–64% and total nitrogen to 49–77% of pre-invasion concentrations. Seasonally, differences between both summer and winter phosphorus and nitrogen concentrations diminished, suggesting a change in internal nutrient cycling after the invasion. In most lakes, the abundance of submerged macrophytes rose substantially, and often coverage increased by a factor 10 or more, and the maximum colonisation depth increased by up to 5.4 m. Plant species numbers increased markedly in four of the six lakes with macrophyte data. The fish community changed towards higher dominance of potential piscivorous perch and an increase in their body size. The profound effects of zebra mussel invasion may affect lake management and how ecological quality should be interpreted.

Research progress on structure and hydrological processes in the karst critical zone of southwest China

The southwestern region of China is the largest exposed karst area in the world and serves as an important ecological security barrier for the upstream of Yangtze River and Pearl River. Different from the critical zone of non-karst areas, the epikarst, formed by an interwoven network of denudation pores, is the core area of karst critical zone. Water is the most active component that participates in internal material cycle and energy flow within the critical zone. We reviewed relevant research conducted in the southwestern region from three aspects: the characte-rization of critical zone structure, the hydrological processes of soil-epikarst system, and their model simulations. We further proposed potential research hotpots. The main approach involved multi-scale and multi-method integrated observations, as well as interdisciplinary collaboration. Precisely characterizing the eco-hydrological processes of the vegetation-soil-epikarst coupling system was a new trend in the future research. This review would provide scientific reference for further studies on hydrological processes in critical zones and regional hydrological water resource management in karst areas.

Carbon and nutrient cycling in cocoa agroforests under organic and conventional management

In cocoa agroforestry systems, cycling of leaves, pods, and branches are key for organic matter sustenance. We investigated annual total litterfall, annual nutrient stocks in total litterfall, cocoa pods and beans, as well as cocoa leaf decomposition rates in cocoa agroforestry systems under conventional and organic management in Suhum Municipality, Eastern Region of Ghana. The study was conducted using six cocoa agroforests for each management selected from a total of four villages. Litterfall was collected monthly using litterboxes and a litterbag technique was employed to study the rates of leaf decomposition and nutrient release for 12 months. In June and July, total litterfall in organic farms were 94% and 65%, respectively, higher than in conventional farms, but management had no effect on average annual total litterfall of 8.8 t ha−1 yr−1 litterfall. Due to the trees’ reduced transpiration, 61% of the annual total litterfall occurred during the dry season. Whereas average leaf litter nitrogen (N) concentration was 17% higher in the rainy season than dry season, potassium (K) concentration was 38% higher during the dry season than rainy season. This likely reflected the contribution of N rich green leaves to litterfall in the rainy season and plant coping strategy to drought leading to K accumulation. Cocoa leaf decomposition was not affected by management. Annual potassium (K) and calcium (Ca) stocks in cocoa pod husk were four and nine-fold, respectively, higher than in cocoa beans. We conclude that organic versus conventional management had no effect on litterfall and cocoa leaf decomposition rather season influenced litterfall quantity and chemistry. Irrespective of management the spreading of cocoa pod husk after harvest will improve internal nutrient cycling in cocoa agroforestry systems.

Controls on distributions of aluminium, manganese and cobalt in the South Atlantic Ocean along GEOTRACES transect GA10

Trace metals (TMs) manganese (Mn), cobalt (Co), and aluminium (Al) have important geochemical and biological roles in the ocean. Here, we present full depth profiles of dissolved (d) and particulate Al, Mn, and Co along the latitude of 40 °S in the South Atlantic Ocean from the GEOTRACES GA10 cruises that operated in austral spring 2010 and summer 2011. The region is characterized by enhanced primary productivity and forms a key transition zone between the Southern Ocean and South Atlantic Subtropical Gyre. The mean concentrations of dAl, dCo, and dMn (±standard deviation) were 3.36 ± 2.65 nmol kg−1, 35.3 ± 17.6 pmol kg−1, and 0.624 ± 1.08 nmol kg−1, respectively. Their distributions in surface waters were determined by external sources and complex internal biogeochemical processes. Specifically, surface ocean dCo was controlled by the interplay between phytoplankton uptake, remineralization and external inputs; dMn was likely determined by the formation and photoreduction of Mn-oxides; and dAl was supplied by atmospheric deposition and removed by scavenging onto particles. Fluvial and sedimentary inputs near the Rio de La Plata estuary and benthic sources from the Agulhas Bank resulted in elevated dTM concentrations in near-shore surface waters. These externally sourced dTMs were effectively delivered to the open ocean by offshore diffusion and/or advection, and potentially facilitated enhanced primary productivity along the transect.The distributions of dTMs at depth were predominantly controlled by the mixing of North Atlantic Deep Water (NADW) and waters of Antarctic origin (e.g., Upper Circumpolar Water (UCDW) and Antarctic Bottom Water (AABW)). The calculated endmember concentrations of dAl and dCo in NADW showed minor decreases in the SASTG following north–south transport, suggesting removal rates of 0.064 nM/year and 0.035–0.075 pM/year, respectively. The endmember concentration of dCo in AABW was maintained at ∼30 pmol kg−1 without evidence for scavenging removal in the Southern Ocean and SASTG (time frame >400 years). The concentrations of dMn in NADW and AABW were between 0.1 and 0.16 nmol kg−1, and any elevated dMn concentrations were ascribed to local external inputs (e.g., from sediments in the Argentine Basin and hydrothermal activity near the Mid-Atlantic Ridge). Hence, four controlling factors (sources, internal cycling, water mass mixing and time) need to be considered when assessing TM distributions in the global ocean, even for TMs that are vulnerable to scavenging removal processes. Because the deep waters formed in high latitude oceans are crucial components of the global thermohaline overturning system, any processes (e.g., glacier melting, upwelling and sinking, and biological activity) that impact the preformed dTM concentrations in high latitude oceans will determine the downstream dTM distributions. Therefore, the sources and sinks of TMs and associated biological activity in high latitude oceans could engender basin to global scale impacts on seawater distributions of Al, Co, and Mn and their stoichiometric relationships with macronutrients, and the global biogeochemical cycles of these scavenged-type TMs.

Implementasi Sistem Penjaminan Mutu Internal dalam Meningkatkan Mutu Pendidikan di MIN 1 Rejang Lebong

ABSTRACTInternal quality assurance is carried out with reference to national educational standards in order to realize the educational goals of the country. Internal quality is currently used in basic and secondary education in addition to universities. This study aims to identify and explain the internal quality system cycle's implementation. Data collecting methods include observations, interviews, and documentary research. According to the findings of this study, Darul Farah Cihampelas Secondary School has implemented the following quality improvement activities in accordance with the stages of the SPMI cycle: first, a school self-evaluation based on the education quality report; second, quality improvement planning through the creation of a quality assurance committee and a re-analysis of the results of the school self-evaluation; third, implementation of quality improvement; and fourth. The evaluation of educational quality comes in second. Quality strategy for the fifth fiscal year, evaluation following quality improvement, and quality improvement results. Implementing internal quality assurance will have an influence on the development of more creative teaching methods, student and school performance, internal and external customer happiness, and the fulfillment of the eight National Education Standards.

Повышение энергетической эффективности газопоршневой ТЭС за счет комплексного использования тепловых вторичных энергоресурсов

Recently, the advantages and prospects to use piston gas internal combustion engines for the combined generation of electrical and thermal energy have become increasingly obvious. The range of single capacities of gas piston units (GPU) ranges from 0,1 MW to tens of MW, which makes them more attractive when designing various power facilities. Most brands of gas piston units can operate in co-generation mode, that is, as a combined heat and power plant that simultaneously generates electrical and thermal energy. The purpose of this study is to substantiate the possibility of integrated use of heat of the cooling systems of the gas piston engine of a thermal power plant (TPP). The studies conducted are carried out using well-known methods of thermodynamic calculation of the internal combustion engine cycle, of determination of the components of its thermal balance and thermal calculation of the equipment for utilization of secondary thermal energy resources. The results of the analysis of the heat losses of the GPU drive engine have showed that the total losses during its operation are about 11544,5 kW. Average potential heat losses with flue gases are 45,87 %, and low-potential heat losses with water in cooling systems and oil in lubrication systems are 53,14 %. A schematic diagram is proposed for the integrated utilization of thermal renewable energy resources (RES) at a gas piston thermal power plant. The main difference between the proposed scheme and the existing technical solutions is the utilization of the heat of the low-temperature charge air cooling system after the second section of the compressor and the heat of the engine lubrication system. An analysis of the expenditure part of the energy balance of the drive engine in case of the integrated use of thermal RES in the GPU cycle, has showed that the implementation of energy-saving measures will make it possible to usefully use up to 93,05 % of the supplied energy in the generation of electrical and thermal power.

Exploring nonlinear responses of lake nutrients and algal blooms to restoration measures: A three-dimensional flux network modelling approach

Excessive anthropogenic nitrogen (N) and phosphorus (P) inputs accelerate harmful algal blooms (HABs) and pose a significant global threat to lake ecosystems. Despite the adoption of extensive restoration measures to improve water quality, their effects on nutrient cycles and the underlying pathways remain unclear. In this study, a three-dimensional nutrient flux modelling approach was developed based on a validated Environmental Fluid Dynamics Code (EFDC) model and the Spatiotemporal Integral for Nutrient Networks (SINN) to compute nutrient storages and fluxes in lakes. We then conducted a scenario analysis, composed of 10 schemes, to assess the eight restoration measures in Lake Dianchi, China. The results showed that our model exhibited a high level of agreement with observed data and fluxes reported in previous studies. Of all the measures implemented, pollution interception by lakeshore wastewater treatment plants (WWTPs) accounted for the largest historical improvements in water quality, with reductions of total nitrogen (TN) by 9.3%, total phosphorus (TP) by 36.4%, and chlorophyll a (Chla) by 18.2%. Furthermore, combined implementation of transboundary water transfer and wastewater diversion contributed to a reduction of 13.3% in TN, 11.5% in TP, and 6.2% in Chla. To achieve greater improvements in water quality, efforts must be made to improve the emission standard of WWTPs and ensure compliance with water quality standard of inflow rivers. The cyanobacteria biomass catch can only be used as a supplementary approach to restrict the HAB peaks. The nonlinear responses of lakes were characterized by large loading abatement but slight changes in water quality. Through the SINN approach, we revealed that weakened internal cycling was the primary driver of water quality improvements in all restoration measures. Further analysis demonstrated that measures targeting reducing external loadings significantly weakened internal cycling processes. In contrast, measures targeting the internal loadings, such as sediment dredging, exhibited limited effectiveness in reducing the intensity of internal cycling and Chla in the lake. For eutrophic lakes with substantial legacy nutrients, the abatement of external loadings remains the principal strategy. The approach presented in this study can be used to assess and optimize lake restoration measures.

Synergistic redox and adsorption for enhanced Roxarsone removal: Heterogeneous Fenton-Like reaction with a novel composite of nanoscale zero-valent iron supported on γ-aluminum oxide

Roxarsone (ROX), a livestock growth enhancer, poses environmental and health hazards due to its remarkable stability, making traditional degradation methods ineffective. To tackle this issue, a novel Fenton-like composite, composed of nanoscale zero-valent iron supported on γ-aluminum oxide (nZVI/γ-Al2O3), was synthesized to boost ROX degradation. Results demonstrated nearly complete mineralization of the ROX organic matrix within just 180 min, facilitated by the Lewis acidity sites of γ-Al2O3. Significantly, this composite exhibited selective adsorption of released AsO43− ions on its surface, forming FeAsO4 and Fe-As-Al complexes. It also established an internal redox cycle involving Fe(0), Fe(II), and Fe(III), ensuring a continuous and efficient generation of primary reactive oxygen species (·OH and O2·−). Thus, a simultaneous redox process occurred on the composite surface can be attributed to the synergy of the reducibility of nZVI and the oxidation catalyzed by ·OH and O2·−. Initially, the nitro group of ROX was reduced by nZVI, forming more hydrophilic o-aminophenol, favoring subsequent oxidation and mineralization. Simultaneously, the As-C bonds in ROX were oxidized, yielding AsO43−, which was subsequently adsorbed over extended reaction times. This innovative approach offers a potential solution for treating wastewater contaminated with metalloid-organic composite pollutants, addressing the environmental and health concerns associated with ROX residues.

Intercalibration: A Cornerstone of the Success of the GEOTRACES Program

The international GEOTRACES program was developed to enhance knowledge about the distribution of trace elements and their isotopes (TEIs) in the ocean and to reduce the uncertainty about their sources, sinks, and internal cycling. Recognizing the importance of intercalibration from the outset, GEOTRACES implemented intercalibration efforts early in the program, and consensus materials were generated that included the full range of TEIs dissolved in seawater, in suspended particles, and from aerosols. The GEOTRACES section cruises include “crossover station(s)” that are occupied by two or more sections and whereby all aspects of sample collection, preservation, and processing can be compared and intercalibrated. Once datasets are generated, an international intercalibration committee reviews intercalibration reports and works with the community to address issues and provide intercalibrated data for intermediate data products. This process has resulted in a highly cooperative community that shares advances in protocols to strengthen capacity building and GEOTRACES outcomes, including an unprecedented oceanic atlas of TEIs, with data quality that is state-of-the-art. This article outlines the development and implementation of the successful GEOTRACES intercalibration process.

Mercury concentrations and potential methylation rates in Lake Erie

Abstract Little is known about external and internal loading and cycling of bioaccumulative methylmercury in Lake Erie, despite the lake having a world-renowned sport fishery. During the summer/early fall of 2018 to 2021, concentrations and fluxes of total mercury and methylmercury in the water column were examined near the Detroit and Maumee River discharges into western Lake Erie, as well as the junction between Sandusky Bay and central Lake Erie. Average unfiltered total mercury concentrations were similar near the Detroit River (5.4 ± 0.8 pM) and Sandusky Bay inputs (5.3 ± 0.9 pM), which were less than half of those near the Maumee River mouth (11.6 ± 2.8 pM). Similarly, unfiltered methylmercury concentrations near the Detroit River (0.29 ± 0.09 pM) and Sandusky Bay inputs (0.24 ± 0.06 pM) were less than half of those near the Maumee River mouth (0.63 ± 0.21 pM). Potential specific mercury methylation rates measured in central Lake Erie were 0.062 ± 0.027 day-1, 0.045 ± 0.012 day–1 near the Sandusky Bay input, and 0.031 ± 0.006 day–1 at the Detroit River input (Maumee Bay was below detection; rates were not different; Tukey, p >0.87). Compared to previous work, total mercury concentrations in the western basin observed in this study indicate a decrease of about 3.3% yr–1, which may reflect positive impacts of state, provincial, and national legislation (U.S. National Clean Water Act 1990, Ohio Clean Air and Water Act 2004, Ontario Clean Water Act 2006). However, methylmercury concentrations have increased in western Lake Erie from 2010 to 2019, which may reflect the impact of legacy mercury pollution.

Advances in Understanding the Marine Nitrogen Cycle in the GEOTRACES Era

Because nitrogen availability limits primary production over much of the global ocean, understanding the controls on the marine nitrogen inventory and supply to the surface ocean is essential for understanding biological productivity and exchange of greenhouse gases with the atmosphere. Quantifying the ocean’s inputs, outputs, and internal cycling of nitrogen requires a variety of tools and approaches, including measurements of the nitrogen isotope ratio in organic and inorganic nitrogen species. The marine nitrogen cycle, which shapes nitrogen availability and speciation in the ocean, is linked to the elemental cycles of carbon, phosphorus, and trace elements. For example, the majority of nitrogen cycle oxidation and reduction reactions are mediated by enzymes that require trace metals for catalysis. Recent observations made through global-scale programs such as GEOTRACES have greatly expanded our knowledge of the marine nitrogen cycle. Though much work remains to be done, here we outline key advances in understanding the marine nitrogen cycle that have been achieved through these analyses, such as the distributions and rates of dinitrogen fixation, terrestrial nitrogen inputs, and nitrogen loss processes.

Mewujudkan sistem penjaminan mutu internal berkelanjutan melalui pendampingan audit mutu internal

The Internal Quality Assurance System is a reference for universities to better manage and organize higher education, prepare students to compete at the global level, and make a greater contribution to the local community. Bumi Sebalo Management Academy Bengkayang faces challenges in implementing the Internal Quality Assurance System, such as a lack of understanding of the Internal Quality Assurance System concept, limited human resources and infrastructure, low commitment to quality culture, and not yet having a certified internal auditor. The purpose of this community service assistance is to support the implementation of the Internal Quality Assurance System through the second cycle of Internal Quality Audit using a Participatory Action Research approach consisting of the identification/assessment stage, planning, program design, implementation, and monitoring, and evaluation. As a result, Bumi Sebalo Management Academy Bengkayang successfully implemented the control cycle and can continue to the Internal Quality Assurance System improvement cycle. This is evidenced by the support of the Organizing Board, college management, the involvement of the entire academic community, and the preparation of the second cycle Internal Quality Audit report. Internal Quality Audit assistance is very useful in realizing a sustainable Internal Quality Assurance System at Bumi Sebalo Management Academy Bengkayang

IMPLEMENTASI SISTEM MUTU INTERNAL UNTUK MENINGKATKAN MUTU PENDIDIKAN DASAR

To implement state education goals, internal quality assurance is carried out in relation to national education standards. Internal quality is now applied not only to higher education, but also to primary and secondary education. We continue to ensure and lead educational quality assurance and compliance in primary and secondary school units. The aim of this research is to determine and describe the implementation of the internal quality system cycle. The techniques used in data collection are: Observation, interviews, documentary research. The results of the research show that the quality improvement steps implemented at Bawamai Pontianak Elementary School are in accordance with the SPMI cycle steps including: First, school self-evaluation based on education quality certificates; second, a plan to improve quality through the formation of a quality committee and analysis of the results of the Kermbali School self-evaluation; Implementation of quality improvement, fourth, evaluation of follow-up and results of quality improvement after quality improvement, and fifth, return to next year's quality plan. The results of implementing internal quality assurance influence a more innovative learning process, student and school performance, satisfaction and success of internal and external customers. Eight national education standards.

Research on Digital Economy Driving High Quality Development of China's Manufacturing Industry

With the profound changes in the global industrial economic situation, the industrial competition pattern is further adjusted, China's original reliance on the "demographic dividend" effect of the manufacturing industry expansion path is facing the challenge of low-end locking and marginalization, the urgent need to cultivate new kinetic energy. Get rid of the inherent low-cost competition and scale expansion mode, promote the digital transformation of the manufacturing industry, are the road to high-quality development of the manufacturing industry under the new development pattern. On the one hand, the digital economy has reconstructed the layout of the manufacturing industry chain in digital space and physical space, effectively unimpeded the domestic macrocycle; on the other hand, the digital economy can promote China's manufacturing industry to the high-end of the value chain, and win a larger profit space and the right to speak for the manufacturing industry to integrate into the international cycle. Therefore, under the new development pattern of internal and external double cycle, digital economy has become the new kinetic energy for the upgrading of China's manufacturing industry. This project combs through the domestic digital economy to drive the high-quality development of the manufacturing industry related literature, summarizes the economy to drive the high-quality development of the manufacturing industry measurement method, organizes the recent years of China's manufacturing industry development related research, consolidates the research foundation and expands the research perspective, constructs the "scale - structure", We construct a four-dimensional analytical framework of "scale-structure" and "circulation-external circulation" for the high-quality development of manufacturing industry, and explore the theoretical mechanism of digitalization-driven high-quality development of manufacturing industry. Through the use of econometric modeling methods to carry out empirical analysis of the digital economy driven manufacturing high quality, according to the empirical results, more scientific formulation of the digital economy driven China's manufacturing industry upgrading countermeasures recommendations.

Impacts of flue gas desulfurization (FGD) gypsum on water quality and the algal community in catfish aquaculture ponds

Catfish aquaculture ponds are at high risk of experiencing excessive algal growth, especially cyanobacteria, that can lead to negative water quality issues due to their consistent input through regular feedings and internal cycling of nutrients. Conventional algaecides used in aquaculture, such as copper sulfate, may be effective in the short-term but can potentially lead to developed resistance in phytoplankton over time or harmful effects on non-target species. An alternative nutrient management strategy, which has traditionally been used in land-based agriculture, is via flue gas desulfurization (FGD) gypsum, a form of calcium sulfate that is created as a by-product of carbon-based energy sources. A six-month field experiment was conducted on active catfish aquaculture ponds at a farm in west Alabama to test the effects of FGD gypsum on water quality, including its ability to manage excessive algal blooms throughout the growing season. In stark contrast to previous results from FGD gypsum application in eutrophic waters, it was discovered that FGD gypsum-treated ponds experienced a large increase in soluble reactive phosphorus (SRP) that led to a spike in phytoplankton abundance, specifically cyanobacteria. Supplementary microcosm experiments aided in determining that FGD gypsum could extract legacy phosphorus out of the nutrient-rich flocculant sediment found in aquaculture ponds. While these results were unexpected and ultimately undesired, we did discover that the use of FGD gypsum at the 500 mg/L concentration does not produce any trace metal contamination in the water column or in the fish tissue. Overall, this experiment discovered new results that FGD gypsum could produce when used in hypereutrophic waters with nutrient-rich sediments and provides the foundation for future research directions to determine the specific mechanisms behind the interaction of FGD gypsum with the sediment.

Energy efficiency enhancement of a thermal power plant by novel heat integration of Internal Combustion Engine, Boiler, and Organic Rankine Cycle

AbstractThe utilization of waste energy contributes to reducing carbon emissions and mitigating global warming. A novel heat integration system comprising an Internal Combustion Engine (ICE), Boiler, and Organic Rankine Cycle (ORC) coupling is techno‐economically examined in this study. The feasibility of waste heat recovery from industrial boilers of a thermal power plant (Gadoon Textile Mills Limited, Pakistan) having 2.66‐MW capacity was assessed. This was done by efficiently harnessing the waste heat from boiler exhaust gas by coupling an existing system with an ORC. A steady‐state simulation model of the ICE‐Boiler‐ORC system was developed through Power Plant Simulator and Designer (PPSD) software to perform a multiparametric study. Additional heat power (3710 kW) was extracted from the boilers' waste gases through ORC. Consequently, the overall plant thermal efficiency was enhanced from 61.84% to 82.68% and the overall net electric efficiency of the existing system was increased by 0.9%. The average payback period was found 4.2 years based on different plant operation scenarios and equipment prices (Chinese or European origin). Therefore, the proposed system holds significant technical and economic potential for enhancing energy efficiency through low‐grade waste heat and proves to be economically viable with a short payback period.

Estimation of transfer factor from soil to cassava in Ethiope East, Delta State, Nigeria

Cassava is a very important staple food crop in Delta state. The aim of this research is to assess the activity concentration level and determine the transfer factor of radionuclide from soil to cassava in Ethiope Local Government Area of Delta state, Nigeria. The activity concentration of 40K, 238U and 232Th in soil and cassava samples collected from the study area were analysed using gamma spectrometry. A lead-shielded 3 x 3 inch coaxial type Sodium Iodide Thallium [NaI(TI)] doped detector crystal (Model No. 802 series, Canberra Inc.) coupled to a Canberra series multichannel Analyzer (MCA) (Model N0.1104) through a preamplifier was used. The results of the activity concentration in soil samples indicate that, 40K has the highest mean activity concentration ((38.66 ± 3.69) BqKg−1) with the highest value ((62.47 ± 5.67) BqKg−1) recorded at E2. The mean activity concentrations of 238U and 232Th are 3.65 ± 0.90 BqKg−1 and 0.46 ± 0.05 BqKg−1respectively. The peak values of 238U and 232Th are 5.07 ± 1.17 BqKg−1 and 0.98 ± 0.11 BqKg−1. From cassava, 40K varies from 75.06 to 200.08 BqKg−1 with the highest mean activity concentration of 99.62 ± 8.32 BqKg−1 and 200.08 ± 14.90 BqKg−1 as the highest value noted at C5. The mean activity concentrations of 238U and 232Th are 3.89 ± 0.93 BqKg−1 and 0.81 ± 0.09 BqKg−1 respectively. The maximum values of 238U and 232Th determined from the computation from cassava samples are 11.10 ± 2.48 BqKg−1 and 1.70 ± 0.18 BqKg−1. The results of this study show that the activity concentration of 40K, 238U and 232Th in the study area are lower than world average values of 420, 30 and 35 BqKg-1 in soil and cassava respectively, and it is therefore not harmful if consumed. The mean transfer factor of 40K, 238U and 232Th from soil to cassava are 3.12 ± 0.44, 0.95 ± 0.31 and 2.96 ± 0.91 respectively. The range of values of 40K, 238U and 232Th varied as 1.41 to 5.82, BDL to 2.98 and 0.21 to 9.35 correspondingly. Peak values of the TF were noted as 5.82 for 40K at E8, C8, 2.98 for 238U at at E9, C9 and 9.35 for 232Th at E9, C9. The high value of TR is accredited to the richness of the organic matter in the soil. The quick recycling of natural radionuclides through the soil-cassava suggests the presence of an internal cycling that help the build-up of the natural radionuclides.

Fine Division of Internal Cycles of Glutenite based on INPEFA Technology and Wavelet Transform

In order to study the internal cycle characteristics of glutenite reservoirs, this study conducted high-resolution sequence division of glutenite based on INPEFA technology and wavelet transform technology. In this paper, the basic principles of INPEFA technology and wavelet transform technology are introduced in detail, and the differences and advantages and disadvantages of the two methods in high-resolution sequence division are compared. Taking Jilantai oilfield as an example, combined with INPEFA technology and wavelet transform technology, INPEFA processing and wavelet processing are innovatively carried out based on acoustic time difference curve, and the accuracy is verified by each other. On this basis, combined with logging, seismic, lithology and other data, the top and bottom interfaces of the third-order sequence of the K1g1 in the study area were identified, and on this basis, K1g1 was further divided into two oil groups, a total of eight layers.

Research on Classification Construction of Degree Programs Based on Life Cycle Theory

The development of degree programs is not achieved overnight, but also has a certain internal growth cycle and development stage. Drawing inspiration from the life cycle theory, a four-stage lifecycle theory of degree programs with incubation period, growth period, development period, and differentiation period was proposed. Then, combining eight key tasks related to degree program construction, including degree program cultivation, application, special qualification evaluation, periodic qualification evaluation, discipline evaluation, level evaluation of professional degree, quality special inspection, and dynamic adjustment, this paper shoot the arrow at the target based on the main work and tasks of degree program construction at different stages. Finally, taking Henan Polytechnic University (HPU) as an example, classified construction of degree programs was implemented, corresponding governance strategies were adopted to improve the construction level of degree programs in different states, and high-quality connotation development of degree programs was promoted.

Fatigue life prediction of rolling bearings based on damage accumulation considering residual stresses

The determination of the fatigue life of rolling bearings is recommended to be conducted using the standard calculation models defined in ISO 281. These models yield reliable results for rotating applications. The standard models are continuously refined to align with advancements in bearing production processes and material improvements. However, when dealing with rolling bearings exposed to complex load conditions including oscillatory movements, as seen in rotor blade bearings in wind turbines, a validated calculation model has yet to be established. In the domain of structural mechanics, fatigue life evaluation for steel components is based on S-N curves. Variable operational loads are treated as load collective, and the load cycle to failure N under given operational conditions is determined through the application of the linear damage rule. This paper introduces a novel model that integrates the linear damage rule with established conventional bearing theories. Within one internal stress cycle, all rolling contacts are regarded as an internal load collective. To evaluate the internal load collective, the stress state at each rolling contact is assessed based on the S-N curve determined in alternating torsional loads. The core rationale behind the selection of an S-N curve lies in the stress criterion τo based on Lundberg-Palmgren theory, which is incorporated in the new model. This paper includes a comprehensive step-by-step procedure for applying the new model, utilizing the cylindrical roller bearing NU 1006 as a reference. The results of this study indicate a favorable agreement between the fatigue life obtained using the new model and those determined according to ISO 281. Furthermore, a new approach is introduced to analytically account for residual stress - es when measured values are available. In this study, by applying this new approach, the results were observed to be in close agreement with the test results. Based on this investigation, it can be confirmed that the new model has the potential to provide reliable results without necessitating the bearing life exponent as well as the correction factors often required in conventional calculation models.