bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Continuous Circulation in Geothermal Wells to Improve Drilling Performance and Reduce NPT Related to Wellbore Stability
Authors: Petrie Scott William , Doll Rick
Published: March 2021

Continuous Circulation Systems (CCS) have been used in the past to help drill wells where interactions between the mud weight and theformation may increaserisks, thereby allowing the well to be drilledwithout encountering drilling problems or damaging the formation, whilst reaching total depth in the planned time. Previous systems have,however,relied on people working in the red zone. This paper discusses the process of making drill pipe connections, with continuous circulation,utilising a fully automatic deployment system to add value by removing the risk of people around the drill pipe during the connection, working in conjunction with other automated rig systems todeliver the advantages of continuously circulation over each connection.

The continuous circulation subs are installed in every stand of drill pipe to be used in the drilled interval and facilitate circulation while the next stand is picked up and made up to the stump. A valve manifold is utilised to divert flow from the pumps to the subs, instead of the top drive, during the connection. During each connection, circulation is maintained down the drill string, from bit to surface, at drilling rates. Once the connection has been made the continuous circulation surface equipment is disconnected from the drill string allowing drilling to resume.

After deploying the continuous circulation system on a number of geothermal projects, the results of using the system for top hole and intermediate sections suggest that while drilling with low rheology water-based mud systems,a high percentage of cuttings are returned to surface while the next stand of drill pipe is being picked up,limiting any hole loading and allowing the driller to increase the rate of penetration (ROP) through these sections. Fewer hole collapse issues were observed while drilling through volcanic tuff and ash, where wellbore stability is low due to poorly consolidated rock formations, thereby reducing non-productive time associated with stuck pipe and the costs of lost bottom hole assemblies (BHA's) and sidetracks. Most Geothermal projects work on very tight budgets and geothermal exploration costs need to be kept low. Improved drilling performance has improved the viability of these projects and increased the number of exploration wells that can be drilled in a campaign by reducing the days versus depth P90 estimate, that being the 90% probability of the rig matching the days v's depth curve predicted.
A Novel Use of Digital Technologies for More Effective Multi-Party Well Planning and Execution
Authors: Isbell Matthew Ray , Manocha Malini Raman , Mangold Brian Rodney , Laing Moray Lamond , Boone Scott , Annaiyappa Pradeep
Published: March 2021

Operators, service providers, and contractors are improving the well construction system using transformative digital technologies across multiple companies and within levels of disparate organizations. Well plans are managed in a new way with the creation,execution and continuous improvement of processes to materially deliver value from the onset.

A typical operator’s well planning process involves developing a well program across multiple internal and external entities in the design and plan stages while various requirements and details are considered and confirmed. As the well gets closer to being drilled, the well plan must also consider the capabilities and technologies supported by the service companies and drilling contractor.This people-based process leads to variability in assumptions and objectives in standardized plans which can result in execution risk and variations in safety, quality, delivery, and cost (SQDC) performance. One major variability source occurs because of the disconnected nature in which people move data between one another in well planning documents and then to field operations. The authors propose a new way to manage this process across organization and discipline boundaries to reduce this variability. This paper details how digital technologies were incorporated into an agile pilot program to create a common framework for the exchange and management of the well plan. It follows the plan from its development to implementation in a unified, seamless process. Further the authors will demonstrate how the solution was developed across multiple organizations to deliver material value to all parties.

Three companies created a collaborative business model to deliver a new digital system enhancing well construction planning and execution in terms of speed and completeness of data transfer, ease of access,and availability for building new data-based workflows and reporting. This business model continues to drive alignment throughout the companies’ well delivery business functions.

This paper illustrates, "What is the value that digital transformation brings to my organization or job function".The simple answer is that if executed effectively, the transformation should produce a material improvement or outcome for the business. Digital technology creates material business value as a project management tool directly coupled with wellsite technologies. This approach, in turn, will enable improvement of the well design and SQDC performance in the delivery of the well plan.
A Way to Reduce the Uncertainties, Optimize and Reduce Time During the Multistage Cut and Retrieve Operations for Surface Plug Placement
Authors: Volkov Maxim , Evans Mal , Haggart Garry , Gaifutdinov Ruslan , Beagrie Robert
Published: March 2021

Planning and execution of the well plug and abandonment(P&A) requires detailed knowledge of the downhole barrier's integrity status and position of its downhole completion elements.[Maxim Volkov] This input is utilized for the determination of zones for permanent plugs, casing cuts and retrieval procedures. The last one can be significantly optimized if conducted across the zones with minimal total wall thickness. Cutting the casing across casing collars, fins or casing decentralization may extend the operation requiring more time and resources to achieve success.

However, the detailed completion information is not always available due to several well handover. This may result in casing cut performed blindly, based on the position of the first casing collars revealed by caliper or ultrasound surveys. This may result in an increase of the RIG operation timing from few hours to few days.

The paper shows results of downhole scanning during three subsea wells P&A campaign at the stage of environmental plug deployment. This included cutting and pulling out of casing wellhead elements (casing stumps) after milling works, before setting environmental cement plug in seabed zone. Casing wellhead design may include the first 13 3/8" and 20" casing joint welded fins to centralize casings. Typical casing joint with fins (rigid type) is shown in figure 1. The abandonment program included milling of these casings and the cutting through the minimal or nominal wall thicknesses with avoiding fins and collars of the casings. The depth of the cutting window initially was set from the available well diagrams, which were not available in all the wells. Thus, the main role of the scanning was to verify and optimize the casings cut window depth to perform the process with minimal issues.

Figure 1 Casing joint with rigid centralizers-fins.
Comprehensive Analysis of Borehole Stability with Temperature, Swelling, and Pore Pressure Change for Layered and Orthotropic Formations
Authors: Kaneshima Takuma , Bai Fuqiao , Morita Nobuo
Published: March 2021

Borehole stability depends on various parameters such as rock strength, rock deformations, in-situ stress, borehole trajectory, shale swelling, pore pressure change due to osmosis, overbalance mud weight and temperature. The objective of this work is to construct analytical and numerical equations to predict borehole failure including all these parameters, and to comprehensively propose a methodology to improve the borehole stability.

Analytical solutions are developed for inclined wells with respect to in-situ stress, shale swelling, pore pressure change due to osmosis, overbalance mud weight and temperature. A numerical model is developed for 3D inclined wells with orthotropic formation and layered formation. Using the analytical and the numerical models, stress state around inclined wells are evaluated. The breakout angle is predicted based on Mohr-Coulomb, Mogi, Lade and Drucker-Prager failure theories. Polar diagrams of mud weights are compared to judge the effect of each parameter and the magnitude predicted by the different failure theories.

Shale swelling and pore pressure change due to osmosis are the most difficult to estimate among above-mentioned parameters. The laboratory measured swelling of cores obtained from various formations showed that the magnitude to induce breakouts caused by swelling was the largest comparing with other parameters. Therefore, when shale stability problems occur, we need to estimate the magnitude of shale swelling and osmosis due to water potential difference. Then, to overcome the shale stability problem, we evaluated the sensitivity of human controllable parameters on borehole stability. The parameters which can be controlled by drilling engineers are overbalance, type of mud, borehole temperature and borehole trajectory. If the shale swelling is small, the borehole stability is improved by the mud weight. However, from the swelling tests from the cores of Nankai-Trough, we estimated unless we used a swelling inhibitor to reduce the swelling less than 0.1%, the well was not possible to drill through. Actually, the well was abandoned due to instability after trying side track several times.

Unlike previous works, this paper uses all important parameters (swelling, temperature, pore pressure, orthotropic formation, layered formation) to estimate the stresses around inclined wells with the same formation conditions for quantitative analysis. Failure analysis include Mohr, Mogi, Lade and Drucker-Prager. Finally, the polar diagrams of critical mud weight are used to judge whether we can choose well trajectory, orientation with respect to bedding planes, mud weight, shale inhibitor, and temperature to stabilize the borehole.
Game Changing Cementless Annular Isolation Improving Economical Returns in Deep Water Wells
Authors: Bledou Manfred , Caillon Didier , Groschaus Benjamin , Viger Guillaume , Singh Harpal , Bagal Joseph , Hallaire Maximilien , Onadeko Olugbenga , Hazel Paul , Vasquez Ricardo , Wallach Mathieu , Fürstnow Mette
Published: March 2021

This paper will discuss a game-changing and innovative technology that enabled cementless annular isolation (liner to borehole) across the reservoir, removing the risk of previous experienced cost and time overrun from complex cement operations and securing the full economical return on the wells. The technology has been deployed in four Moho North Albian wells, drilled through a complex reservoir with highly laminated lithology requiring efficient zonal isolation for both acid treatment and water shut off.

During the earlier field development, many cementing challenges were encountered that increased risk and cost and the ability to deliver effective isolation across the reservoir. Poor isolation leads to poor matrix acid stimulation, higher skin and a higher risk of water production. To address this the operator sponsored an industry challenge to achieve reservoir isolation with cost and risk reduction and to deliver overall efficiency gains. Through dialogue between the Operator and a leading service provider in Open Hole Zonal Isolation, a solution was identified that would effectively replace the cement across the reservoir with a metal expandable annular sealing system.

Time for delivery was a key driver to meet the drilling schedule and materialize the cost and risk reductions on the remaining wells. A scope of work was completed that included extensive qualification, manufacture and field deployment. The solution has proven to deliver benefits that address several fundamental aspects which were associated with the cemented liners: Substantial reduction in risk and cost associated with drilling the extended rat hole (shoe track) into the highly pressurized water zone (+/- 100mMD)Removed the risk and cost for the additional run to under ream the 6 ½″ hole to 7 ¼″ (low-ROP)Provided more certainty for zonal isolation whilst delivering effective acid stimulation and maintaining the low skin values.

The technology has many different applications within wells where conventional cement is challenged beyond its capabilities and inherently not fit for purpose, due to factors such as well trajectory, hole geometry, reservoir uncertainty, downhole environment (pressure, Temp, ECD) etc. Within these environments, the technology developed for Moho North adds a proven solution to the Operators toolbox, a technology that is already finding alternate applications and planned deployments.
Compatibility Between API Equations and Design Limits Plots for Ellipse and Circle of Plasticity
Authors: Romero Juan Manuel , Aasen Jan Aage
Published: March 2021

This paper presents a methodology to superimpose the American Petroleum Institute (API TR 5C3 2018) uniaxial and triaxial limits on tubular design limits plots. Complications due to a recent change of axis are resolved, producing practical design limits plots that avoid the horizontal shift of the API vertical limits, currently done by the industry. The commonly used slanted ellipse is compared against an adaptation of the circle of plasticity in the form of a horizontal ellipse, showing the convenience of this last one with examples.

After the new collapse formulation was made part of the main body of standard API TR 5C3 (2018), the horizontal axis on the standard industry well tubular design limits plot changed. The present study evaluates this redefinition of the horizontal axis. One consequence of this modification is a difficulty plotting the API tension and compression limits. The API horizontal limits (uniaxial burst and collapse) are found to be independent of load case, while the API vertical design limits (uniaxial tension and compression) are dependent on inside and outside tubular pressures. The approaches used by commercial software and industry publications to solve this challenge are reviewed. A new design methodology is developed to link API uniaxial limits to the triaxial theory.

The main objective of the study is to establish a mathematical relationship between API tubular design limits and the von Mises triaxial theory (API TR 5C3 2018). A methodology that allows plotting the API uniaxial force limits on the design limit plot is developed. The study also shows that the results obtained from the industry standard slanted ellipse are identical to those obtained from the horizontal ellipse and circle. One important difference is that the slanted ellipse is based on zero axial stress datum while the horizontal ellipse/circle uses neutral axial stress datum. The horizontal ellipse/circle is well suited for calculations involving buckling, it is compatible with the information used in field operations and its formulations are less complicated than the tilted ellipse. Therefore, attention is called to it.
Analysis and Evaluation of Problematic Hazard Elements in Drilling through Collapse Features, A Case from Challenging Drilling in Persian Gulf
Authors: Salehi Ehsan , Daneshkhah Vahid , Hosseini Shoar Behnam
Published: March 2021

Complete mud loss is a severe costly drilling problem which increases drilling time and makes wells challenging to control. Such situation was encountered during drilling of three wells from a platform in an offshore field in Persian Gulf. This unexpected problem occurred while other wells from this platform were drilled and completed according to the routine plan. Further investigations using 3D seismic data showed that, these wells had penetrated through a massive collapse feature causing extended drilling times. Buried collapse features are developed as result of karstification due to dissolution of carbonate rocks. Although karstification may be evaluated as a disturbing parameter of reservoir properties, the most critical concern about this phenomenon is difficulties in forecasting drilling mud weight due to highly unpredictable fluid transmissibility. Collapse feature has different viscoelastic properties from its surrounding sediments, therefore, it generates different seismic responses in terms of amplitude and frequency. This aspect was utilized for identification of encountered collapse feature where, a practical semi-automated approach based on seismic derived multi-attributes cubes and neural network analysis was taken. Once a sinkhole cube was generated based on the above approach, geobody of the collapse feature was extracted. Results then were thoroughly validated by mud loss intervals at wells. Close investigation of the sinkhole cube revealed that seven collapse features exist in the area of study in which, problematic wells pass through one of them. It was discovered that all collapse features are interconnected with deep-seated faults which acted as hydrocarbon migration conduit. This incident obviously emphasizes role of geohazards analysis before any offshore drilling, even in a developed field with several number of wells. As experienced, a significant part of well non-productive time can be avoided if an integrated multi-disciplinary approach is taken. The authors will describe an effective proactive approach towards geohazards and present lessons learned in the case presented to address unexpected geo-drilling incidents.
Top-Hole Technology Overcomes Challenging Sand-Based Seabed Conditions and Enables Record Drilling Performance in an Offshore Exploration Well
Authors: Cardenas Camilo , Hansen Hans Erik , Hanssen Sigvald , Blikra Harald , Mathis Wolfgang , Holen Ole Kristian , Kort Arjen , Zhang Youhu
Published: March 2021

Top hole construction is a critical part of any well design, especially for subsea wells. It is considered to be the foundation for the well, and it is crucial for ensuring well integrity. Uncertainties and conditions of the seabed and top layers could compromise the stability of the chosen solution. This paper describes the first implementation of the conductor anchor node (CAN®) technology in sand-based conditions and demonstrates its positive impact on the drilling performance for an offshore exploration well in the North Sea.

The main challenges identified in the top-hole design for this well were the presence of boulders down to 65 m below the seabed, and hard soil that consisted mainly of very dense sand and high strength sandy-clay layers. Different solutions were evaluated using a risk-based approach, looking to optimize operational performance and decrease the environmental footprint. A technology which consists of a pre-installed short conductor within a CAN was chosen. This solution enabled the operator to establish a competent well foundation above the boulder interval and increase operational efficiency by reducing the critical rig time. However, the CAN technology had not been deployed in this type of soil previously. Thus, the feasibility of its installation became one of the main milestones of the project. This was made possible due to a set of contingencies and modifications that were the result of a strategic collaboration among the parties involved.

The CAN was successfully installed by a crane vessel before the rig arrived at location, and the set of contingencies and modifications mentioned in this paper were decisive to ensure it reached the required penetration depth. Furthermore, this paper demonstrates that the CAN technology was crucial for the project to achieve top performance results and become one of the fastest exploration wells drilled in the Norwegian basin. This solution reduced uncertainties related to the conductor cementing, load and fatigue capacities, and deep surface casing cement. Improvement in the drilling performance is determined by estimating the decrease in drilling time, materials and consumables. Those results are then used to perform a cost comparison which demonstrates that the CAN technology reduced the top-hole construction cost significantly on this offshore well. In addition, the reduction in the well environmental footprint is quantified, and its contributions to the projects health and safety goals are highlighted.
Derivation to Calculate Pipe Collapse Performance using a Combined Loading Equivalent Grade Accounting for Axial Stress, Internal Pressure, Bending and Torsion
Authors: Besse Jean-Guillaume
Published: March 2021

This paper proposes a new analytical derivation to incorporate bending and torsion into collapse calculation, further pushing the already existing approach of combined loading equivalent grade proposed in API TR 5C3 (2019) Clause 8.4.6 Eq. (42) for axial stress and internal pressure (identical to ISO TR 10400 Clause 8.4.7) used to calculate a differential collapse pressure.

This new derivation is also based on Hencky-von Mises maximum distortion criterion. The interest of developing such combined loading equivalent grade is to enable the use of the four collapse types described in Clause 8 i.e., Yield Strength, Plastic, Transition and Elastic. The formulae are adapted to a closed-form equation similar to current Eq. (42), enabling pipe collapse performance calculation. Newly derived formulae are checked against a size governed by yield strength collapse to verify consistency. The restrictions regarding collapse performance under compression are discussed.
New Triaxial Connection Safety Factor for Tubular Design
Authors: Goodman Malcolm A
Published: March 2021

The API equation for internal leak of API connections is uniaxial since it ignores axial force and external backup pressure. ISO 13679 for qualification of premium connections is biaxial at best. It includes tension/compression but ignores backup pressure for both internal and external leak tests. For tubular design, this paper introduces a new fully triaxial safety factor for threaded connections with dependence on thread shear and hydrostatic pressure. Hydrostatic behavior is modelled with the Mean Normal Stress, and thread shear behavior is modelled with the shear component of the von Mises Stress. A Leak Line for use like the pipe body ellipse is proposed for quick leak assessment. Leak ratings are presented for an example case of 7-in. 35-ppf N80 LTC. The new triaxial safety factor with two connection constants applies to all types of threaded connections, including tubing, casing, and drill pipe, so long as the two constants are evaluated with appropriate but simple physical tests.
Culture and Coronavirus Disease Statistics Public Health Through the Lens of Hofstede’s Cultural Dimensions, A Multiple Regression Analysis
Authors: Wang Jiali , Bandera Cesar , Yan Zhipeng
Published: March 2021

Background Hofstede’s Culture Dimensions (HCD) are the most prevalent metrics with which social scientists distinguish cultural differences between countries. In this study, we examine the relationships between HCD and the COVID-19 pandemic. In particular, we investigate how differences in COVID-19 infection, death and recovery between countries correlate with differences in individualism (IDV), indulgence (IVR) and power distance index (PDI).Method We use multiple linear regressions to interpret statistical and economic significances. Results IDV is found to be significantly associated with death rate and recovery rate globally, while IVR and PDI do not seem to be significantly relevant. None of the three dimensions are significantly related to the global infection rate. Conclusions These results have implications for the design of public health campaigns on preventing COVID-19 infection and compliance with vaccination campaigns. Some practical strategies have been proposed for public health officials to help mitigate COVID 19 spread.
Mechanical Properties of Group Iv Single-walled Nanotubes: A Finite Element Approach Based on the Density Functional Theory
Authors: Dastmard Mohammad , Ansari Reza , Rouhi Saeed
Published: March 2021

In this article, the density functional theory is applied to investigate the mechanical properties of single-walled nanotubes of group IV of periodic table including carbon nanotube, silicon nanotube, germanium nanotube and stanene nanotube. (10,10) armchair nanotube is selected for the investigation. By establishing a link between potential energy expressions in the molecular and structural mechanics, a finite element approach is proposed for modeling the nanotubes. In the proposed model, the nanotubes are considered as an assemblage of beam elements. Young’s modulus of the nanotubes is computed by the proposed finite element model. Young's modulus of carbon, silicon, germanium, and tin nanotubes are obtained as 1029, 159.82, 83.23 and 18.15 GPa respectively, using the density functional theory. Also, the finite element approach gives the values as 1090, 154.67, 85.2 and 82.6 GPa respectively. It is shown that the finite element model can predict the results of the density functional theory with a good accuracy.
Identification of Tumor Necrosis Factor-Alpha (Tnf-α) Inhibitor in Rheumatoid Arthritis Using Network Pharmacology and Molecular Docking
Authors: Yu Jun , Zhou Peng
Published: March 2021

Background: This study aimed to investigate the molecular mechanism of Radix Paeoniae Alba (White peony, WP) in treating rheumatoid arthritis (RA) and tumor necrosis factor-alpha (TNF-α) inhibitor (TNFi) by using network pharmacology and molecular docking. Methods: In this study, the ingredient of WP and the potential targets of RA were obtained from the Traditional Chinese Medicine Systematic Pharmacology Database, GeneCard and OMIM databases, respectively. Establishment of RA-WP potential target genes interaction network using STRING database. Network maps of WP-RA-potential target genes network was constructed using Cytoscape software. gene ontology (GO), and biological pathway (KEGG) pathway enrichment analysis were used to further explore the RA mechanism and therapeutic effects of WP. Using molecular docking technology to analyze the optimal effective components from WP to docking with TNF-α. Results: 13 active ingredients and 71 target genes were screened from WP, 49 of which intersect with RA target genes and are considered as potential therapeutic targets.Network pharmacological analysis showed that the WP active ingredients of mairin, DPHCD, (+)-catechin, beta-sitosterol, paeoniflorin, sitosterol, and kaempferol showed better correlation with RA target genes such as PGR, PTGS1, PTGS2, NR3C2, TNFSF15, CHRM2. The signaling pathways of the active ingredients for the treatment of RA are TNF-α signaling pathway, toll-like receptor signaling pathway, cell apoptosis, interleukin-17 signaling pathway, C-type lectin receptor signaling pathway, mitogen-associated-protein kinase, etc. Molecular docking results suggest that mairin was the most appropriate natural TNFi.Conclusions: Our findings provide the essential role and basis, for further studies into the molecular mechanisms of WP and TNFi development in RA.
A Machine Learning Method Based on the Combination of Nonlinear and Texture Features to Diagnose Malignant Melanoma From Dermoscopic Images
Authors: Ghahfarrokhi Sepehr Salem , Khodadadi Hamed
Published: March 2021

Skin cancer affects people of all skin tones, including those with darker complexions. Melanomas are known as the malignant tumors of skin cancer, resulting in an adverse prognosis, responsible for most deaths relating to skin cancer. Early diagnosis and treatment of skin cancer from dermoscopic images can significantly reduce mortality and save lives. Although several Computer-Aided Diagnosis (CAD) systems with satisfactory performance have been introduced in the literature for skin cancer detection, the high false detection rate has made it inevitable to have an expert physician for more examination. In this paper, a CAD system based on machine learning algorithms is provided to classify various skin cancer types. The proposed method uses the Online Region-based Active Contour Model (ORACM) to extract the Region Of Interest (ROI) of skin lesions. This model uses a new binary level set equation and regularization operation such as morphological opening and closing.Additionally, various combinations of different textures and nonlinear features are extracted for the ROI to show the multiple aspects of skin lesions. Several metaheuristic optimization algorithms are used to remove redundant or irrelevant features and reduce the feature space dimension. These are applied to the combination of the extracted features in which, Non-dominated Sorting Genetic Algorithm (NSGA II) as a multi-objective optimization algorithm has the best performance. Furthermore, various machine learning algorithms include K-Nearest Neighbor (KNN), Support Vector Machine (SVM), Fitting neural network (Fit net), Feed-Forward neural network (FF net), and Pattern recognition network (Pat net) are employed for the classification. Accordingly, the best-obtained precision of 99.24% based on five-fold cross-validation is attained by the selected features of texture and nonlinear indices through NSGA II, applying the pattern net classifier. Also, the comparison between this paper's experimental results and other similar works with the same dataset demonstrates the proposed method's efficiency.
Cognitive and Motor Dual Task on Multi-area Brain Activation and Gait Performance in Individuals with Parkinson’s Disease
Authors: Liu Yan-Ci , Yang Yea-Ru , Yeh Nai-Chen , Ku Pei-Hsin , Lu Chia-Feng , Wang Ray-Yau
Published: March 2021

Background In people with Parkinson’s disease (PD), gait performance deteriorating during dual task walking compared to single-task walking has been noted in previous studies. However, the effects of different types of dual task on gait performance and brain activation were still unknown. Methods This study investigated the walking performance changes and multi-area brain activities during cognitive and motor dual task walking in people with PD. Twenty-eight participants with PD were recruited and performed single walking (SW), walking while performing a cognitive task (WCT), and walking while performing a motor task (WMT) at their self-selected speed. Gait performance including walking speed, cadence, stride length, stride time, swing cycle, temporal and spatial variability and dual task cost (DTC) were recorded. Brain activation of the prefrontal cortex (PFC), premotor cortex (PMC), and supplementary motor areas (SMA) were measured by functional near-infrared spectroscopy during walking. Results Results showed the walking performance deteriorated upon performing a secondary task, especially the cognitive task. Also, a higher and sustained activation in PMC and SMA during WCT as compared with WMT and SW in the late phase of walking was found. Moreover, gait performance was negatively correlated with PMC and SMA activity during different walking tasks. Conclusions Individuals with PD demonstrated gait deterioration during dual task walking, especially WCT. The SMA and PMC were further activated in people with PD when performing cognitive dual task walking. Trial registrationTCTR20190118010. Registered 18 January 2019, retrospectively registered.
A Facile Approach for the Synthesis of Zinc Ferrite/Alkali Cellulose as an Effective Magnetic Photocatalyst for the Degradation of Methylene Blue in Aqueous Solution
Authors: Charradi Khaled , Ahmed Zakarya , Moussa Mohamed , Beji Zyed , Brahmia Ameni , Othman Israa , Haija Mohammad Abu , Chtourou Radhouane , Keshk Sherif
Published: March 2021

The spinel zinc ferrite/alkali cellulose composite has been successfully fabricated as a magnetic photocatalyst and assessed for its photocatalytic activity toward the degradation of methylene blue (MB) in an aqueous solution. The Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), thermogravimetric analysis (TGA), BET, and zeta potential were used to evaluate the magnetic photocatalyst composite and investigate its adsorption mechanism. Furthermore, the adsorption behavior of the composite was studied under various conditions. The ZnFe2O4/alkali cellulose composite effectively degraded (100%) MB after 180 min at a pH of 6.5 compared to cellulose, alkali cellulose and ZnFe2O4. The regeneration of the loaded composite was studied using the alcohol/water solution and reused upon a certain variation in the efficiency after the fourth cycle. The adsorption process was found to be consistent with the pseudo-second-order kinetic model.
Comparative Population Genetics of Two Korean Aedes Mosquito Species with Vector Potential based on Mitochondrial DNA
Authors: Shin Jiyeong , Jung Jongwoo
Published: March 2021

Background: Mosquitoes of the genus Aedes are important invasive species contributing to the spread of chikungunya, dengue fever, yellow fever, Zika virus, and other dangerous vector-borne diseases. Aedes albopictus is native to southeast Asia with rapid expansion due to human activity, showing a wide distribution in the Korean peninsula. Aedes flavopictus is considered to be native to East Asia with a broad distribution in the region, including in the Korean peninsula. Gaining a better understanding of the genetic diversity of these species is critical for establishing strategies for disease prevention and vector control. Methods: We obtained DNA from 148 specimens of Ae. albopictus and 166 specimens of Ae. flavopictus in Korea, and amplified two mitochondrial genes (COI and ND5) to compare the genetic diversity and structure of the two species.Results: We obtained a 658-bp sequence of COI and a 423-bp sequence of ND5 from the two mosquito species. We found low diversity and an insignificant population genetic structure in Ae. albopictus, and high diversity and an insignificant structure in Ae. flavopictus for these two mitochondrial genes. Ae. albopictus had less haplotypes with respect to the number of individuals, and a slight mismatch distribution was confirmed. By contrast, Ae. flavopictus had a large number of haplotypes compared with the number of individuals, and a large unimodal-type mismatch distribution was confirmed. Although the genetic structure of both species was insignificant, Ae. flavopictus exhibited higher genetic diversity than Ae. albopictus.Conclusions: Ae. albopictus appears to be an introduced species, whereas Ae. flavopictus is an endemic species to the Korean peninsula, and the difference in genetic diversity between the two species is related to their adaptability and introduction history. As an endemic species, Ae. flavopictus is likely to have a larger population size than expected. Further studies on the genetic structure and diversity of these two mosquito species will provide useful data for vector control.
Metagenomic Insights Into Ecological and Phylogenetic Significances of Candidatus Natranaeroarchaeales, a Novel Abundant Archaeal Order in Soda Lake Sediment
Authors: Zhou Heng , Zhao Dahe , Zhang Shengjie , Xue Qiong , Zhang Manqi , Yu Haiying , Zhou Jian , Li Ming , Xiang Hua
Published: March 2021

BackgroundArchaea were originally discovered in extreme environments, and thrive in many extreme habitats including soda lakes with high pH and salinity. Characteristic and diverse archaeal community played a significant role in biogeochemical cycles; however, the archaeal community and their functions are still less-studied in the intricate sediment of soda lakes. ResultsIn this article, the archaeal community of the deep sediment (40-50 cm depth) of five artificially-separated ponds with a salinity range from 7.0% to 33.0% in a soda saline lake was systematically surveyed using culture-independent metagenomics combined with the next-generation sequencing of the archaeal 16S rRNA amplicons. Nine archaeal phyla were detected, which accounted for 2.2% to 35.73% of microbial community in the five deep sediments. Besides the well-known class Halobacteria, one novel archaeal order (Candidatus Natranaeroarchaeales) of the class Thermoplasmata was even more abundant than Halobacteria in some deep sediment samples. Of 69 dereplicated archaeal metagenome-assembled genomes (MAGs), 30 MAGs belonged to Ca. Natranaeroarchaeales. Different genera of the Ca. Natranaeroarchaeales preferred to inhabit in the different salinities, and the divergent halophilic adaptation strategies (salt-out or salt-in) suggested the fast evolution adaptation within this lineage. Most high-quality MAGs had the genes of Wood-Ljungdahl pathway, organic acid fermentation and sulfur respiration, suggesting the putative functions in carbon fixation and sulfur reduction. Interestingly, heterodisulfide reductase and F420-non-reducing hydrogenase complex HdrABC-MvhADG were widely distributed in Ca. Natranaeroarchaeales and may play the core roles in energy metabolism from hydrogen. The regeneration of CoM-S-S-CoB was coupled to succinate or 2-oxoglutarate production in Ca. Natranaeroarchaeales instead of methanogenesis in the close related Methanomassiliicoccales. It suggested that methyl-coenzyme M reductase in Methanomassiliicoccales may be laterally transferred from other methanogens. ConclusionA novel archaeal order Ca. Natranaeroarchaeales of Thermoplasmata was found by culture-independent approaches. This order was the most abundant archaeal lineage in the deep sediment of soda lakes, with the characteristic environmental adaptation and biogeochemical potentials in carbon fixation and sulfur reduction. The difference in fermentation products coupled to energy metabolism between methanogens and Ca. Natranaeroarchaeales provided additional insights into the origination of methanogenesis in Thermoplasmata from the energy metabolism perspective.
Evaluation of the adhesion of pregnant women to intermittent presumptive treatment with Sulfadoxine-Pyrimethamine in a rural area of Gabon.
Authors: Mirembou-Boukoumba Fleuramie , Maghendji-Nzondo Sydney , Matsiegui Pierre Blaise , Pegha-Moukandja Irene , Mendene-Abessolo Davy Tanguy , Lekana-Douki Jean Bernard
Published: March 2021

Background: Gestational malaria remains one of the most complex forms of malaria. To fight it, several African countries adopted intermittent presumptive treatment with Sulfadoxine-Pyrimethamine (IPT-SP) and the use of preventive measures such as insecticide-treated bed nets (ITNs), indoor residual sprays (IRS) and popular education on good practices to fight against malaria. In Gabon a country of central Africa, no study has investigated the use of IPT-SP in rural areas since its implementation. The aim of this study was to investigate the adhesion level of pregnant women to IPT-SP, coverage of ITNs and IRS, and knowledge on the good practices about malaria in a rural area of Gabon. Using a questionnaire, we led a retrospective study including pregnant women from January 5th 2016 to January 31st 2018 and a cross-sectional survey including women seen for antenatal care and all febrile patients in consultation from February 2nd to May 31st 2018. Malaria was diagnosed using rapid diagnostic tests. Statistical analyses were done. Results: We included 607 pregnant women before their delivery. Women between 20 and 25 years old were the most prevalent (37.26%, n=229). Among them, 74.53% were unemployed and 47.21% living in the villages surrounding the rural town of Fougamou. The rate of adhesion to IPT-SP was 94.37% (n=573). Among them, 47.8% (n=274) had received 3 doses of IPT. Among the pregnant women included during the cross-sectional survey, only 8.7% (n=14) were infected with Plasmodium. Bed nets were used by 80.12% (n=129) of women. Conclusion: Data showed a near complete adhesion of IPT-SP in the rural area of Fougamou. Clinical trials are needed to investigate the efficacy of IPT-SP and antimalarial drug markers.
First Report of Lophomonas spp. in German Cockroaches (Blattella Germanica) Trapped in Hospitals, Northern Iran
Authors: Motevalli-Haghi Seyyed Farzad , Shemshadian Atyeh , Nakhaei Maryam , Faridnia Roghiyeh , Dehghan Omid , Shafaroudi Majid Malekzadeh , Kelarijani Mehrasa Nejadi , Nikookar Seyed Hassan , Kalani Hamed , Fakhar Mahdi
Published: March 2021

Cockroaches are considered to be important reservoirs for protozoan and helminth parasites ,particularly an emerging Lophomonas spp., protozoan parasite. German cockroaches, Blattella germanica (B. germanica), are domestic pest distributed worldwide. However, little information is available regarding the burden of Lophomonas spp. infestation among domestic cockroach population worldwide. The present study investigated parasitic agents, emphasizing Lophomonas spp. infestation among B. germanica in northern Iran. During spring and summer 2018, a total of 496 adults B. germanica (265 males and 231 females) were trapped by hand and glass traps from the teaching hospitals in Mazandaran, Sari, northern Iran. All cockroaches were identified using taxonomic keys. Each cockroaches was anesthetized with chloroform and the alimentary tract removed. Each section was smeared onto a glass slide. All the smears were examined under light microscopy to determine the presence of the parasites. Ten genera of parasites were identified from the trapped B. germanica; overall, 233 (47%) were found to be positive for helminths (n=135) and protozoa (n=98). The helminths included Aspiculuris tetraptera egg (67/233, 28.7%), Oxiuros sp. (39/233; 16.7%), Dentostomella translucida (17/233; 7.3%), and nematodes Ova (12/233; 5.2%). The protozoan parasites identified Gregarina sp. (61/233; 26.2%), Entamoeba sp. (19/233; 8.2%), Blastocystis sp. (5/233; 2.1%), Lophomonas (4/233; 1.7%), Nyctotherus sp. (4/233; 1.7%), unclassified flagella (5/233; 2.1%). Lophomonas spp. was detected within the gut of B. germanica, for the first time, in Iran. It has previously been identified in the gut of cockroaches a long time ago, however, this is the first attempt to detect Lophomonas in cockroaches housing in hospitals. Thereby, it possibly presenting pose a serious respiratory infection risk for patients and health care personnel.
Ultrafast time-evolution of chiral Néel magnetic domain walls probed by circular dichroism in x-ray resonant magnetic scattering.
Authors: Lévéillé Cyril , Burgos-Parra Erick , Sassi Yanis , Ajejas Fernando , Chardonnet Valentin , Pedersoli Emanuele , Capotondi Flavio , De Ninno Giovanni , Maccherozzi Francesco , Dhesi Sarnjeet , Burn David , Laan Gerrit van der , Latcham Oliver , Shytov Andrei , Kruglyak Volodymyr , Jal Emmanuelle , Cros Vincent , Chauleau Jean-Yves , Reyren Nicolas , Viret Michel , Jaouen Nicolas
Published: March 2021

Non-collinear spin textures in ferromagnetic ultrathin films are attracting a renewed interest fueled by possible fine engineering of several magnetic interactions, notably the interfacial Dzyaloshinskii-Moriya interaction. This allows the stabilization of complex chiral spin textures such as chiral magnetic domain walls (DWs), spin spirals, and magnetic skyrmions. We report here on the ultrafast behavior of chiral DWs after optical pumping in perpendicularly magnetized asymmetric multilayers, probed using time-resolved circular dichroism in x-ray resonant magnetic scattering (CD-XRMS). We observe a picosecond transient reduction of the CD-XRMS, which is attributed to the spin current-induced coherent and incoherent torques within the continuously dependent spin texture of the DWs. We argue that a specific demagnetization of the inner structure of the DW induces a flow of spins from the interior of the neighboring magnetic domains. We identify this time-varying change of the DW texture shortly after the laser pulse as a distortion of the homochiral Néel shape toward a transient mixed Bloch-Néel-Bloch texture along a direction transverse to the DW.
Coupled lines with double shields for microwave hybrids of various types of directivity with transforming properties
Authors:   Tomsk State University of Control Systems and Radioelectronics (TUSUR), Sychev A. N. , Bondar V. A. ,   Tomsk State University of Control Systems and Radioelectronics (TUSUR), Zharov K. K. ,   Tomsk State University of Control Systems and Radioelectronics (TUSUR), Anisimov V. V. ,   Tomsk State University of Control Systems and Radioelectronics (TUSUR), Dagba K. B.-B. ,   Tomsk State University of Control Systems and Radioelectronics (TUSUR), Stepanyuga A. I. ,   Tomsk State University of Control Systems and Radioelectronics (TUSUR)
Published: March 2021

Asymmetric coupled double-shielded lines in an inhomogeneous dielectric medium, which have special properties that allow us to create microwave hybrids of a given directionality type are investigated. For the first time, a new model and method of synthesis are proposed, which takes into account both the asymmetry and the inhomogeneity of the dielectric, which makes it possible to synthesize co-, counter- and transdirectional couplers that have both the transforming and required phase properties. The research results will be useful for finding new design solutions of the next generation microwave circuits.
Impact of climate change on groundwater resource in a region with a fast depletion rate: the Mississippi Embayment
Authors: Ouyang Ying , Wan Yongshan , Jin Wei , Leininger Theodor D. , Feng Gary , Han Yuguo
Published: March 2021

Mississippi Embayment (ME) is one of the fastest groundwater depletion regions around the world, while the impacts of climate change on groundwater resources in the region are complex and basically unknown. Using the U.S. Geological Survey's Mississippi Embayment Regional Aquifer Study (MERAS) model, such a challenge was addressed through the base, wet, and dry simulation scenarios. Over the 137-year simulation period from 1870 to 2007, the cumulative aquifer storage depletions were 1.70 × 1011, 1.73 × 1011, and 1.67 × 1011 m3, respectively, for the base, dry, and wet scenarios. As compared with that of the base scenario, the aquifer storage depletions were only 1.76% more for the dry scenario and 1.8% less for the wet scenario. A multiple regression analysis showed that the aquifer storage depletion rate was controlled more by the groundwater pumping and stream leakage rates and less by the groundwater net recharge rate. Groundwater table variation in the forest land was much smaller than in the crop land. Results suggested that groundwater pumping rather than climate change was a key driving force of groundwater depletion in the ME. Our findings provide a useful reference to water resource managers, foresters, and farmers in the ME and around the world when developing their groundwater supply strategies.
Improving the implementation of water and resource recovery in Canada
Authors: Nixdorff Heather , Noga Jacqueline , Amsalu Dareskedar , Springett Jane , Ashbolt Nicholas
Published: March 2021

Globally there is a need to rethink water use and wastewater disposal. One view is to consider wastewater as a resource via treatment for fit-for-purpose water and resource recovery (WRR). To understand what has worked in Canada according to those directly involved in WRR, we used interviews with individuals involved in various WRR projects. Seventeen semi-structured interviews were completed with participants from regions across Canada. Three main findings pertaining to the question ‘what is needed for WRR project implementation?’ emerged from the interviews: government and institutional support; community engagement, education, and acceptance; and comprehensive planning. Based on the interview findings, WRR projects require foundational guidance, something that is currently lacking in the Canadian context. To improve WRR implementation and success in Canada, guidance on community engagement, technology, costs, and impact assessments should be built into a policy for WRR.