bluuebunny/crossref_metadata_2025 huggingface dataset:
Refracturing on Horizontal Wells in the Eagle Ford Shale in South Texas - One Operator's Perspective
Authors: Diakhate Mamadou , Gazawi Ayman , Barree Bob , Cossio Manuel , Tinnin Beau , McDonald Beth , Barzola Gervasio
Published: February 2021

This paper outlines a refrac pilot testing program conducted in the Eagle Ford Shale.

As wells in the Eagle Ford accumulate production over time and the pressure around the horizontal wellbore declines, it is important to also consider communication due to offset fracture stimulation. Refracturing trials in older fields, such as the Barnett Shale have yielded a positive enhancement of well performance (Siebrits et al., 2000). This paper evaluates the concept of diverting fluid and proppant along horizontal wells in the Eagle Ford, while considering any communication with older producing wells during refracturing operations.

Pumping data acquired during the refracturing is used to explain some of these concepts. Modeling of induced fracture geometry, considering the effect of current pore pressures, is conducted with a fully three-dimensional hydraulic fracture numerical simulator. The pressure of the subject zone may affect the containment and rate of growth of the new fractures, as well as the re-orientation of the existing fractures.

Refracturing an old horizontal well with 5,000 ft lateral length and more than 800 existing perforation holes in the casing is very challenging and requires a careful integration of reservoir knowledge, completions skills and experience. The technical team at Pioneer Natural Resources has developed an integrated workflow to design and execute a refracturing job for an Eagle Ford well. The work flow includes: 1) identification of the lower pressure areas along the lateral using surveillance data from the well, such as microseismic, tracer logs, and production data. 2) identifying which wells within the drilling schedule are offsetting older wells that have high cumulative production, and 3) designing a single fracturing job with several sub-stages separated by diverting agents. Each sub-stage is intended to target specific areas along the lateral, which were previously identified as low pressure zones. Volumes and pump schedules will be specific for each candidate and are based on but not limited to proximity to an offset well, lateral length, and existence of geological structures such as faults and fractures in the area. The results from this pilot testing program such as the radioactive tracers and the fracture gradient changes before and after refrac will be evaluated upon completion of the field execution.
Re-Fracturing in Eagle Ford and Bakken to Increase Reserves and Generate Incremental NPV - Field Study
Authors: Oruganti YagnaDeepika , Mittal Rohit , McBurney Cameron J. , Rodriguez Alberto
Published: February 2021

Due to the tight nature of the matrix in shale plays, the drainage area does not extend far into the reservoir and is defined by the shape and size of the hydraulic fractures. As a consequence of this, wells typically exhibit steep decline rates and one of the prevalent ways to arrest the decline of a field is to drill and complete more wells. However, re-fracturing is slowly gaining a foothold in the industry, and our study has shown tremendous re-frac potential in the Bakken and Eagle Ford. In this study, we analyzed horizontal wells from the Bakken and Eagle Ford to identify existing re-fractured wells and estimated incremental recovery, followed by an economic analysis, to show re-fracturing as a viable alternative to drilling new wells.

Production and completions data was retrieved from public sources for all horizontal wells in the Bakken and the Eagle Ford formations, and a proprietary algorithm was applied to identify wells with a production signature that is consistent with a recompletion event. These wells were individually screened and confirmed as being re-fractured or not. Production metrics were defined to understand the performance of the wells before and after re-fracturing. Cross plots were made between these parameters to understand trends between the ratios of production decline rates and b-factors before and after re-fracturing, taking into account the time of re-completion. Decline curves were fit to the production of these wells to estimate the incremental estimated ultimate recovery (EUR) upon re-fracturing, and a net present value (NPV) analysis was done to determine commercial viability.

A majority of the identified potentially re-fractured wells had positive incremental NPV based on the EUR increase, which was 53% and 69%, on an average, for the Eagle Ford and Bakken respectively. From the existing re-fractured wells that were analyzed, it was found that there was no discernible correlation between the time an operator produces a well before being refractured and the various performance metrics that were analyzed. Also, good decline curve fits were found without changing the b-factors post-refrac and secant decline rates were typically lower after re-fracturing.

The results show the potential of re-completing wells and increasing reserves without drilling new wells based on actual field examples, showing an alternative field development strategy to the current practice of replacing older wells with newly drilled ones. Also, if re-fracturing is to be implemented on a larger scale, wells must be completed so as to make subsequent recompletions much easier, thereby encouraging use of novel casing and diverting agent technologies. Positive economics shows the huge potential of cost savings with re-stimulation and makes a ‘second wave’ of Eagle Ford/Bakken production possible.
Water-Induced Fracture Conductivity Damage in Shale Formations
Authors: Zhang Junjing , Zhu D. , Hill A. D.
Published: February 2021

Shale fracture conductivity can be reduced significantly due to shale-water interactions. Factors that may influence shale fracture conductivity include shale mineralogy, proppant embedment, shale fines migration, proppant fines migration, brine concentration, longer term rock creep, and residual water in the fracture. The study of excessive proppant embedment has been reported in our previous work (Zhang et al. 2014a). This paper presents the studies of the rest of these factors.

Laboratory experiments were run to understand each of these factors. To study the effect of rock mineralogy, recovered fracture conductivities after water damage for the Barnett Shale, the Eagle Ford Shale, and Berea Sandstone were measured. During conductivity measurements, water flow directions were switched to study the effect of shale fines migration. The size of shale fines was measured by microscopic imaging techniques, and scanning electron microscopic observations are also presented. Proppant fines migration was examined by placing two colors of sand on each half of the fracture surface and a microscope was used to identify the migrated crushed sands of one color mixed in the other color sand. Fresh water and 2% KCl were injected to study the effect of brine concentration. After water injection, the proppant pack was either fully dried or kept wet to investigate the damage by residual water.

Results showed that clay content determines the fracture conductivity damage by water. Fines generated from the shale fracture due to fracture face spalling, slope instability, and clay dispersion can migrate inside the fracture and are responsible for approximately 20% of the conductivity reduction. There is no evidence of crushed proppant particle migration in this study. Longer term rock creep accounts for a 20% reduction of the fracture conductivity. Fresh water does not further damage the fracture conductivity when initial conductivities are above 65 md-ft. Removal of the residual water from the fracture by evaporation helps recover the fracture conductivity to a small extent.

A theoretical model of propped fracture conductivity was extended to include the effects of water damage on fracture conductivity. An empirical correlation for the damage effects in the Barnett shale was implemented in this model.
Challenging Assumptions About Fracture Stimulation Placement Effectiveness Using Fiber Optic Distributed Sensing Diagnostics: Diversion, Stage Isolation and Overflushing
Authors: Ugueto C. Gustavo A. , Huckabee Paul T. , Molenaar Mathieu M.
Published: February 2021

The connection of the wellbore to the hydrocarbon resource volumes via effective fracture stimulation is a critical factor in unconventional reservoir completions. Various well construction and dynamic placement methods are used to distribute treatment volumes into targeted sections of the wellbore. This paper provides some insights into the effectiveness of hydraulic fracture stimulation process using Fiber Optics (FO): distributed acoustic sensing (DAS) and distributed temperature sensing (DTS). This paper reviews examples from multiple wells where FO has been used to gain a better understanding of three highly debated fracture stimulation distribution topics: Diversion, Stage Isolation and Overflushing. Diversion is increasingly being used as a way to improve the efficiency of hydraulic fracture stimulation distributions. The effectiveness of the diversion techniques has traditionally been judged on the basis of surface pressure response during treatment and ultimately, from production comparisons to reference wells. Unfortunately, getting clear answers from production performance takes significant time. FO allows for monitoring of the diversion process in real-time. Analysis of DAS and DTS responses is used to quantify diversion efficiency in re-directing hydraulic fracture stimulation from dominant perforation clusters to those not being stimulated. Lack of isolation between stages has frequently been observed in wells with diagnostics. There is consensus amongst the completion community that communication between stages is highly undesirable because the energy and materials of the stimulation are partially or totally misdirected from the target interval to other portions of the wellbore. The analysis of DAS and DTS not only can help determine the frequency of occurrence of communication between stages in cemented and uncemented horizontal wells but also can provide insights about the different communication paths. Fiber Optic distributed sensing in conjunction with complementary diagnostics is also being used to investigate if connections are being maintained at the end of the treatment between the newly created fracs and the wellbore. The use of integrated diagnostics allows evaluation of the frequency in which overflushing (over-displacement) occurs in both vertical and horizontal wells and its impact on well inflow performance where production profiling data is available.
Calculation and Implications of Breakdown Pressures in Directional Wellbore Stimulation
Authors: Barree Robert D. , Miskimins Jennifer L.
Published: February 2021

In 1898, Kirsch published equations describing the elastic stresses around a circular hole that are still used today in wellbore pressure breakdown calculations. These equations are standard instruments used in multiple areas of petroleum engineering, however, the original equations were developed strictly for vertical well settings. In today's common directional or horizontal well situations, the equations need adjusted for both deviation from the vertical plane and orientation to the maximum and minimum horizontal in-situ stress anisotropy. This paper provides the mathematical development of these modified breakdown equations, along with examples of the implications in varying strike-slip and pore pressure settings. These examples show conditions where it is not unusual for breakdown pressure gradients to exceed 1.0 psi/ft and describes why certain stages in "porpoising" horizontal wells experience extreme breakdown issues during hydraulic fracturing treatments. The paper also discusses how, in most directional situations, the wellbore will almost always fail initially in a longitudinal direction at the borehole wall, after which the far-field stresses will take over and transverse components can be developed. Tortuosity and near wellbore friction pressure can actually add to forcing the initiation of such longitudinal fractures, which can then have cascading effects on other growth parameters such as cluster-to-cluster and stage-to-stage stress shadowing. Special considerations for highly laminated anisotropic formations, where shear failure of the wellbore may precede or preclude tensile failure, are also introduced. Such failure behaviors have significant implications on near wellbore conductivity requirements and can also greatly impact well production and recovery efforts.
Evolution of Completion Techniques in the Lower Shaunavon Tight Oil Play in Southwestern Saskatchewan
Authors: Schlosser D. J. , Johe M. , Humphreys T. , Lundberg C. , McNichol J. L.
Published: February 2021

The Oil and Gas industry has explored and developed the Lower Shaunavon formation through vertical drilling and completion technology. In 2006, previously uneconomic oil reserves in the Lower Shaunavon were unlocked through horizontal drilling and completions technologies. This success is similar to the developments seen in many other formations within the Williston Basin and Western Canadian Sedimentary Basin including Crescent Point Energy's Viewfield Bakken play in southeast Saskatchewan.

In the Lower Shaunavon play, the horizontal multistage completion era began in 2006, with horizontal divisions of four to six completion stages per well that utilized ball-drop sleeves and open-hole packers. By 2010, the stage count capabilities of ball-drop systems had increased and liners with nine to 16 stages per well were being run.

With an acquisition in 2009, Crescent Point Energy began operating in the Lower Shaunavon area. The acquisition was part of the company's strategy to acquire large oil-in-place resource plays. Recognizing the importance that technology brings to these plays, Crescent Point Energy has continuously developed and implemented new technology. In 2009, realizing the success of coiled tubing fractured cemented liners in the southeast Saskatchewan Viewfield Bakken play, Crescent Point Energy trialed their first cemented liners in the Lower Shaunavon formation.

At the same time, technology progressed with advancements in completion strategies that were focused on fracture fluids, fracture stages, tool development, pump rates, hydraulic horsepower, environmental impact, water management, and production.

In 2013, another step change in technology saw the implementation of coiled tubing activated fracture sleeves in cemented liner completions. Based on field trials and well results in Q4 2013, Crescent Point Energy committed to a full cemented liner program in the Lower Shaunavon.

This paper presents the evolution of Crescent Point Energy's Lower Shaunavon resource play of southwest Saskatchewan. The benefits of current completion techniques are: reductions in water use, increased production, competitive well costs, and retained wellbore functionality for potential re-fracture and waterflooding programs.
Unconventional Technology: The Difference Between Successful Application and Unsuccessful Application (North America and Overseas)
Authors: Casero A. , Rylance M.
Published: February 2021

The past two decades have seen the development and expansion of an approach to wellbore completions that has resulted in unlocking significant reserves from previously disregarded resource, and has been responsible for the North American shale gas ‘revolution’ or ‘evolution’ (depending upon how you see it). However, this approach has faced significant complications to appropriate, successful and economic deployment, when attempts have been made to export this process overseas.

This ground-breaking completion approach was achieved as a direct result of the combination of two well-known and widely applied industry technologies, from distinct disciplines: namely horizontal lateral drilling and propped hydraulic fracture stimulation. This simple combination is referred to by a number of different designations which are used to describe the process, but it is most commonly referred to simply as multi-stage horizontal well hydraulic fracturing.

The North American success story has been primarily accomplished through the application of two distinct variants of this technique, split by fundamental approach to the stage sequencing: namely the Plug & Perf approach and the Open Hole Multi-Stage completion system (typically ball-activated fracture ports). The Open Hole Multi-Stage completion system has typically been applied selectively, with a bias towards clastic formations, whereas Plug & Perf has been more widely applied and almost exclusively dominates the shale completion environment.

This paper will describe the engineering aspects of the multi-stage horizontal well hydraulic fracturing process, as well as those particular North America conditions and deliberate compromises that have been made, in order to encourage this approach to become established and develop further. Such analysis will include a holistic approach to the global market conditions, in order to better understand the local and regional factors that have played such a fundamental role in North American success, many of which have been erroneously overlooked elsewhere. This paper will investigate a number of these key issues and factors, particularly related to completion and reservoir interaction that should be considered carefully when choosing to export such techniques to new areas of application outside of North America. This will include an understanding of the key data that should be acquired, from the early exploration and subsequent appraisal wells, so that appropriate decisions can be made efficiently.
Quantitative and Visual Analysis of Proppant Transport in Rough Fractures and Aperture Stability
Authors: Raimbay A. , Babadagli T. , Kuru E. , Develi K.
Published: February 2021

The consensus reached in the literature is that the roughness of fractures plays a crucial role on proppant transport affecting the aperture sustainability of hydraulic fractures. In this paper, an experimental scheme to visually and quantitatively investigate the hydraulic characteristics of rough fractures in the presence of proppants was presented. Rock samples of different kinds (i.e., granite, marble, and limestone) were fractured under the Brazilian test and molded to manufacture 20x20 cm transparent replicas. Propping agents were injected in a similar fashion and were introduced into the well with fracking fluid at a constant rate. Two types of fracture models were used: (1) perfectly mating (joint) and (2) sheared fractures in polymeric solutions. During the experiments, the inlet pressure was continuously monitored to quantify the permeability changes due to proppant distribution caused by the roughness of fracture surfaces. Meanwhile, corresponding images were collected to trace the transport of proppants and their behavior was correlated to the measured permeability change. For a better visualization of proppants, the injected fluid was dyed with a fluorescent material.

In both joint and shear type fractures, existing closure areas controlled the proppant movement and permeability change significantly. The fracture roughness controlled by the lithological properties of the rocks was a critical factor affecting the permeability and proppant transport. After quantifying the roughness characteristics through the variogram fractal dimension, relationship between fracture permeability in the presence of proppant and rock types were presented. Also provided was a semi-quantitative analysis of the stability (or settlement) of proppants during injection with respect to the roughness type (and lithology). The quantitative and visual data collected for a wide range of rock types with original roughness characteristics are expected to be useful in fracking design and selection of proper proppants for different reservoirs.
A New Technical Standard Procedure to Measure Stimulation and Gravel-pack Fluid Leak-off under Dynamic Conditions
Authors: Asadi Mahmoud , Ainley Brain , Archacki David , Aubry Eric , Brannon Harold , Ghalambor Ali , Parker Mark , Watson Russell
Published: February 2021

Historically, leak-off analyses of stimulation fluids have been performed using in-house laboratory procedures. The lack of industry standard procedures to perform leak-off and wall building coefficient analyses of stimulation fluids has introduced inconsistency in both results and reporting for many years. A technical standard adopted in 2006 by both API and ISO for static conditions has provided the oil and gas industry with the first standardized procedure to measure and report leak-off1. However, the more complex testing under dynamic conditions was not addressed. As a result, a group of industry experts have compiled their years of experiences in developing a new technical standard to measure the leak-off characteristics of stimulation and gravel-pack fluids under dynamic flow conditions.

Stimulation and gravel-pack fluids are defined, for the purpose of this technical standard, as fluids used to enhance production from oil and gas wells by fracturing and fluids used to place filtration media to control formation sand production from oil and gas wells. Leak-off is the amount of fluid lost to porous media during these operations. The leak-off procedure was developed through the colaberation of several industry companies by evaluating numerous in-house laboratory techniques and conducting round robin testing to ensure that any modifications to these procedures were reliable and repeatable. The new standard provides a step-by-step procedure that includes fluid preparation, experimental equipment design, testing procedure and data analyses for fluids exhibiting viscosity controlled leak-off or wall building characteristics. Example calculations are reviewed within this paper.
Behavioural Evidence and Chemical Identification of a Female Sex Pheromone in Anagrus Atomus (Hymenoptera: Mymaridae)
Authors: Zanolli Penelope , Annoscia Desiderato , Zanni Virginia , Nazzi Francesco , Pavan Francesco
Published: February 2021

Anagrus atomus (L.) is an egg parasitoid used for the biological control of Empoasca vitis (Goethe) in vineyards. Sex pheromones play a crucial role in mate finding process of several parasitoid species and could be used for monitoring under field conditions. We carried out lab and field studies aiming at assessing the existence and identity of a possible A. atomus sex pheromone. We found that males were significantly attracted by virgin female independently from female age. Males were not attracted from individuals of the same sex but they were attracted by crude extract of an unmated female and its polar fraction. Eugenol (4-allyl-2-methoxyphenol) was identified as the attractive substance and proved to be attractive not only in the olfactometer but also in another laboratory bioassay and under field conditions. Attraction of males, but not females, confirms that this is not an aggregation pheromone. This is the first sex-pheromone component identified in Mymaridae but more compounds could be involved in the mating behaviour of A. atomus. The utility of a sex pheromone in A. atomus is discussed in the context of fitness returns.
Biometric and Genetic Stability Assessment of In Vitro Rooted Populus alba L. Micro-Shoots
Authors: Ahmed Mohamed Fathy , Ahmed Eman Zakaria , Hussien Eman Tawfik
Published: February 2021

Populus alba is a deciduous large woody tree. The plant was introduced to shooting, then rooting multiplication on MS media. This work's design depends on two factors (media power and sucrose concentrations) with different concentrations resulted in 12 treatments. There were nine responses measured in the new individuals. Some morphological parameters had a significant difference, such as shoot length, leaf and root numbers. Where in the physiological measurements, all the parameters measured had significant differences. RAPD-PCR molecular marker was applied to assess the variation in the new individuals' genetic stability from treatments with the two factors. Four RAPD primers gave reproducible bands and resulted in a total polymorphism percentage of 38.33%. The new individuals resulted from the tissue culture technique were identical to the mother plant and each other. However, in this work, the use of different media power and sucrose concentrations resulted in different values in morphological, physiological responses, and P. alba's molecular variation.
Application of electrochemical plasma on iron electrodes for treating 2,4-Dichlorophenoxyacetic acid (2,4-D) and 2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) in water environment
Authors: Tran Cong Van , Nguyen Hung Duc , Tran Dung Thi Ngoc , Nguyen Hoang Van
Published: February 2021

The herbicide compounds contain aromatic ring and chlorine atom such as 2,4-dichlorophenoxylacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic (2,4,5-T) cause serious environmental pollution. However, it is very difficult to decompose by chemical, physical and biological methods. The high voltage direct current electrochemical method can be control to form plasma on metallic electrodes. Thus, it creates active species like as H 2 , O 2 , H 2 O 2 and free radicals such as: H•, O•, OH•. Especially, OH• free radicals that has a high oxidation potential, so it is possible to oxidize benzene oring compounds more effective. The iron electrode is used in the studing to combine the dissolve process of the iron anode electrode with aims is to create Fe 2+ ions and electrochemical fenton reaction. Besides, the flocculation process by Fe(OH) 2 also happen. The plasma will appear with a voltage of 5 kV on the iron electrode in a solution of 30 mg/L 2,4-D or 2,4,5 T. After a period time of the reaction, the aromatic oring compounds contaning the chlorine was treated, the electric conductivity of the solution increases due to the amount of Cl - ions releasing in the solution. The degradable products of the 2,4-D and 2,4,5-T were analyzed qualitatively by the gas chromatograph mass spectrometer GC-MS 6890-5975 Agilent system. The results described that the straight chain carboxylic acids were formed in the solution. These compounds are easy to oxidize thoroughly under appropriate conditions in solution by OH• free radicals . Moreover, the 2,4-D and 2,4,5-T were also analyzed quantitatively by a calibration curve from GC-MS 6890-5975 Agilent system or high performance liquid chromatograph HPLC 1100 Agilent system. The treatmental process can be controlled to achieve optimum performance by technological factors such as input voltage, distance between anode and cathode electrodes, initial concentration of 2,4-D and 2,4,5-T as well as flowing air through solution. The analysis results showed that the degradation efficiency of 2.4-D and 2,4,5-T reached at 99.98%; 99.83%, respectively.
One-pot, multi-component synthesis of novel 2-amino-[1,2,4]triazolo[1,5-a] pyrimidine-6-carboxamide derivatives as antiproliferative agents 
Authors: Huo Xian-Sen , Ma Yu-Feng , Chen Zhi-Ru , Yuan Li-Li , Zheng Xiao-Lan , Li Xiong-Li , Liang Feng-Ting , You Wen-Wei , Zhao Peiliang
Published: February 2021

A novel series of 2-amino-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxamide derivatives has been achieved successfully via an efficient one-pot three-component Biginelli-like heterocyclization reaction between different benzaldehydes, 1H-1,2,4-triazole-3,5-diamine, and N-substituted acetoacetamides in the presence of p-toluenesulfonic acid as a catalyst. Moreover, the effects of different conditions on the reaction were well investigated. In addition, cancer cell growth inhibition activity for these target compounds was also explored, and analogue 5l demonstrated the most potent cytotoxic activity against different cancer cells. These finds indicat that 2-amino-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxamide core could be well worth further optimization as a potential scaffold for development of anticancer agents.
Human Papillomavirus and Chlamydia trachomatis in oral and genital mucosa of women with normal and abnormal cervical cytology
Authors: Mosmann Jessica Paola , Zayas Sofia , Kiguen Ana Ximena , Venezuela Raul Fernando , Rosato Otilio , Cuffini Cecilia Gabriela
Published: February 2021

Background. STI such as HPV and C.trachomatis are important to public health, because of the high risk of asymptomatic genital or oral infections could lead to complications and coinfections may be an important cofactor for the oncogenic transformation.Objective. Evaluate the prevalence of oral and genital HPV and C.trachomatis infection in women with normal and abnormal cervical cytology.Study design. The cross-sectional study included 200 oral and cervical swabs from 50 women with normal and 50 with abnormal cervical cytology. HPV and C.trachomatis infections were detected using PCR with specific primers. Results. HPV DNA was detected in 27% of women with normal and abnormal cytology. Out of 27 we detected HPV DNA in 18% of genital samples and 14% of oral samples. HPV genotypes detected were genotype 6 of low-risk and 16, 31, 52, 58 and 16-31 coinfection of high-risk. C.trachomatis DNA was detected in 49% of patients, out of 49 we detected C.trachomatis in 35% of genital samples and 31% of oral samples. There is statistically significant (p<0.05) between cytology and HPV and C.trachomatis infection but there is no statistically significant between cytology and the other characteristics.Conclusions. The morphological similarity between oropharyngeal and genital epithelia would allowed us to infer that the infection in one of this mucosa could occur in the other. Therefore, is important C.trachomatis detection and specific treatment in asymptomatic women because it is known that may increase the risk of HPV persistence and coinfection induces a pro-inflammatory environment that may promote the carcinogenesis. This study highlight the importance of identified possible cofactors for oncogenesis.
I’am hiQ – A Novel Accuracy Index for Imputed Genotypes
Authors: Rosenberger Albert , Tozzi Viola , Hung Rayjean J , Christiani David C , Caporaso Neil E , Liu Geoffrey , Bojesen Stig E , Marchand Loic Le , Albanes Demetrios , Aldrich Melinda C , Tardon Adonina , Fernández-Tardón Guillermo , Rennert Gad , Field John K , Davies Mike , Liloglou Triantafillos , Kiemeney Lambertus A , Lazarus Philip , Haugen Aage , Zienolddiny Shanbeh , Lam Stephen , Schabath Matthew B , Andrew Angeline S , Duell Eric J , Arnold Susanne M , Brunnsstöm Hans , Melander Olle , Goodman Gary E , Chen Chu , Doherty Jennifer A , Teare Marion Dawn , Cox Angela , Woll Penella J , Risch Angela , Muley Thomas R , Johansson Mikael , Brennan Paul , Landi Maria Teresa , Shete Sanjay S , Amos Christopher I , Bickeböller Heike
Published: February 2021

Background: Imputation of untyped markers is a standard tool in genome-wide association studies to close the gap between directly genotyped and other known DNA variants. However, high accuracy with which genotypes are imputed is fundamental. Several accuracy measures have been proposed and some are implemented in imputation software, unfortunately diversely across platforms. In the present paper we introduce I’am hiQ, an independent pair of accuracy measures that can be applied to dosage files, the output of all imputation software. I’am (imputation accuracy measure) quantifies the average amount of individual-specific versus population-specific genotype information in a linear manner. hiQ (heterogeneity in quantities of dosages) addresses the inter-individual heterogeneity between dosages of a marker across the sample at hand. Results: Applying both measures to a large case-control sample of the International Lung Cancer Consortium (ILCCO), comprising 27,065 individuals, we found meaningful thresholds for I’am and hiQ suitable to classify markers of poor accuracy. We demonstrate how Manhattan-like plots and moving averages of I’am and hiQ can be useful to identify regions enriched with less accurate imputed markers, whereas these regions would by missed when applying the accuracy measure info (implemented in IMPUTE2). Conclusion: We recommend using I’am hiQ additional to other accuracy scores for variant filtering before stepping into the analysis of imputed GWAS data.
Photoinduced Electron Transfer Reactions of Water Soluble Porphyrins in Zeolite Environment
Authors: Venkattappan Anbazhagan , Velappan Kandavelu , Rajalingam Renganathan
Published: February 2021

Excited state interactions of zeolite adsorbed porphyrins have been investigated by steady state luminescence quenching technique with certain antioxidants such as reduced glutathione, ascorbic acid and L-cysteine. The zeolite supported porphyrins, meso-tetra (N-methyl-4-pyridyl) porphyrin (H2TMPyP4+) and zinc tetra(N-methyl-4-pyridyl) porphyrin (ZnTMPyP4+) was prepared and characterized by various techniques such as Diffuse Reflectance Spectra (DRS), Scanning Electron Microscope (SEM), powder X-Ray Diffraction (XRD) and BET surface area. The interaction of zeolites with porphyrins are shown to increase the lifetime of the singlet excited state of porphyrins and decays are biphasic in nature. The splitting of the emission band of porphyrins occurs in 1:1 glycerol: water solution due to the changes in the dielectric of the solvation sphere associated with porphyrin. The Stern-Volmer plots of I0/I vs quencher total concentration [Q] were linear in the whole range of [Q] used. This study revealed effective quenching for zinc porphyrin compared to free base porphyrin. The effect of quenchers and zeolite acidity has also been studied. Quenching rate constant (kq) is on the order of 109 M−1 s−1. The quenching reaction obeys Rehm-Weller Equation and is shown to be due to thermodynamically favoured electron transfer from quenchers to the excited singlet state of porphyrins (reductive quenching).
Sequential Treatment of Afatinib and Osimertinib in Patients with Advanced Non-small Cell Lung Cancer Harboring EGFR Mutations: Results from a Real-world Study in South Korea
Authors: Kim Taeyun , Jang Tae Won , Choi Chang Min , Kim Mi-Hyun , Lee Sung Yong , Park Cheol-Kyu , Chang Yoon Soo , Lee Kye Young , Kim Seung Joon , Yang Sei Hoon , Ryu Jeong Seon , Lee Jeong Eun , Lee Shin Yup , Park Chan Kwon , Lee Sang Hoon , Jang Seung Hun , Yoon Seong Hoon
Published: February 2021

The optimal sequence for administration of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) for treating non-small cell lung cancer (NSCLC) is still unclear. This study aimed to evaluate the efficacy of sequential afatinib and osimertinib treatment in patients with NSCLC harboring EGFR mutations. Electronic records of patients with EGFR-mutated NSCLC, who were administered afatinib and osimertinib (group A) or other chemotherapy (group B) between October 2014 and October 2019, across 16 hospitals in South Korea were reviewed. The primary outcome, time on treatment (TOT), secondary outcome, and overall survival (OS) were estimated using the Kaplan-Meier method and log-rank test. Multivariate analyses were performed using the Cox proportional hazards model. Of the 737 patients who received frontline afatinib treatment, 360 with complete records were selected (group A:154, group B: 206). The median TOT was 33.9 months (95% confidence interval [CI]: 24.5−43.3) in group A and 21.3 months (95% CI: 19.4−23.1) in group B. The median TOT with afatinib was 12.9 months (95% CI: 11.8−14.0) overall, and 15.2 months (95% CI: 13.2−17.1) in group A. The 2- and 3-year survival rates were 86.0% and 69.3% in group A and 75.9% and 55.3% in group B, respectively. Sequential afatinib and osimertinib treatment resulted in better survival rates than treatment with afatinib followed by other chemotherapies. Therefore, this sequential treatment strategy may offer clinical benefits to patients with EGFR-mutated NSCLC.
Effect of Productive Capacities on Economic Complexity: Do Aid for Trade flows Matter?
Authors: GNANGNON Sèna Kimm
Published: February 2021

The COVID-19 health pandemic has exposed the strong vulnerabilities of countries, including developing ones to shocks, and underlined the need for exploring ways to strengthen countries' resilience to future shocks. The current paper uses the dataset made recently available by the United Nations Conference on Trade and Development (UNCTAD) to examine (for the first time) the effect of productive capacities on economic complexity. The analysis further investigates whether Aid for Trade (AfT) flows matter for the influence of productive capacities on economic complexity in recipient-countries. The analysis uses a sample of 126 countries (including both developed and developing countries) over the period 2002-2018, and adopts the two-step system Generalized Methods of Moments (GMM) approach. Results have shown that productive capacities exert a positive effect on economic complexity over the full sample. However, the magnitude of this positive effect varies across different sub-samples, with Least developed countries (LDCs) enjoying the lowest magnitude of this positive effect. Furthermore, total AfT flows are positively associated with economic complexity, with LDCs enjoying a higher positive effect than other countries. Interestingly, total AfT flows exert a higher positive effect on economic complexity in countries that experience low levels of overall productive capacities. The latter finding highlights the need for donor-countries to scale-up AfT flows in favour of countries (such as LDCs) that are characterized by low levels of productive capacities. Finally, the empirical outcomes indicate that productive capacities enhance economic complexity in countries that receive higher amounts of total NonAfT flows.
Hydrothermal Properties of Geologic Fluids
Authors: Steele-MacInnis Matthew , Manning Craig E.
Published: February 2021

Aqueous fluids are critical agents in the geochemical evolution of Earth’s interior. Fluid circulation and fluid–rock reactions in the Earth take place at temperatures ranging from ambient to magmatic, at pressures from ambient to extreme, and involve fluids that range from nearly pure H2O through to complex, multicomponent solutions. Consequently, the physical and chemical properties of hydrothermal fluids vary widely as functions of geologic setting; this variation strongly impacts fluid-driven processes. This issue will focus on the nature of geologic fluids at hydrothermal conditions and how such fluids affect geologic processes in some major settings.
Metamorphic Fluids in Orogenic Settings
Authors: Evans Katy A. , Tomkins Andrew G.
Published: February 2021

Metamorphic reactions within the Earth’s crust produce fluids of variable composition that play a major role in the evolution of continents. Metamorphic fluids facilitate reactions that alter crustal rheology, reduce melting temperature, cycle elements between geological reservoirs and form ore deposits. These fluids are relatively inaccessible, other than by study of fluid inclusions, so most studies rely on a combination of indirect evidence and predictive thermodynamic models to determine the characteristics and roles of the fluids. In this article, the origins, compositions, controlling phase equilibria, and roles of metamorphic fluids are reviewed, followed by a discussion of selected areas of current and future research.
Fluids in Submarine Mid-Ocean Ridge Hydrothermal Settings
Authors: Schwarzenbach Esther M. , Steele-MacInnis Matthew
Published: February 2021

Seawater interaction with the oceanic lithosphere crucially impacts on global geochemical cycles, controls ocean chemistry over geologic time, changes the petrophysical properties of the oceanic lithosphere, and regulates the global heat budget. Extensive seawater circulation is expressed near oceanic ridges by the venting of hydrothermal fluids through chimney structures. These vent fluids vary greatly in chemistry, from the metal-rich, acidic fluids that emanate from “black smokers” at temperatures up to 400 °C to the metal-poor, highly alkaline and reducing fluids that issue from the carbonate–brucite chimneys of ultramafic-hosted systems at temperatures below 110 °C. Mid-ocean ridge hydrothermal systems not only generate signifi-cant metal resources but also host unique life forms that may be similar to those of early Earth.
Magmatic-Hydrothermal Fluids
Authors: Audétat Andreas , Edmonds Marie
Published: February 2021

Magmatic-hydrothermal fluids play a key role in a variety of geological processes, including volcanic eruptions and the formation of ore deposits whose metal content is derived from magmas and transported to the site of ore deposition by means of hydrothermal fluids. Here, we explain the causes and consequences of fluid saturation in magmas, the corresponding fluid-phase equilibria, and the behavior of metals and ligands during the transition from magma to an exsolved hydrothermal fluid. Much of what we know about magmatic-hydrothermal systems stems from the study of fluid inclusions, which are minute droplets of fluids trapped within minerals during mineral growth.
Fluids in Geothermal Systems
Authors: Chambefort Isabelle , Stefánsson Andri
Published: February 2021

Hot fluids are nearly ubiquitous in volcanic environments in the Earth’s crust. Magma at depth heats groundwater which then ascends towards the Earth’s surface through faults, fractures, and otherwise permeable rocks. Fluids in geothermal systems offer direct insight into the many complex chemical and physical processes that occur in these extreme environments. They are also analogues of many ore-forming systems. Scientists have advanced our understanding of fluids in geothermal systems by studying wells sunk ~2–3 km deep into many geothermal fields. Today, we are targeting deeper and hotter reservoirs, at or near the contact of magmatic bodies, which provide unique opportunities to study, and potentially utilize, super-critical fluid resources in the near future.
Association between metabolic indicators and clinical endometritis during the transition period in Brown Swiss cows
Authors: YAZLIK MURAT ONUR , COLAKOGLU HATICE ESRA , PEKCAN MERT , KAYA UFUK , KURT SERDAL , KUPLULU SUKRU , KACAR CIHAN , VURAL RIFAT
Published: February 2021

The objective of the current study was to evaluate the relationship between the serum macromineral, metabolite profiles, and the clinical endometritis during the transition period in Brown Swiss dairy cows. Sixty Brown Swiss dairy cows were used in the present study. Blood samples collected at d 10 (± 4) antepartum and 3, 10 and 30 (± 4) days in milk (DIM) to determine calcium (Ca), phosphorus, glucose, cholesterol, non-esterified fatty acid (NEFA) levels. Beta-hydroxybutyric acid (BHB) concentration measured during the postpartum period. Receiver operating characteristics (ROC) curves were used to determine the cow-level thresholds for the subsequent development of clinical endometritis. In addition, pairwise comparisons were made of the area under the curve (AUC) of ROC curves for the thresholds of NEFA, Ca, and glucose predicting clinical endometritis. The mean Ca concentration at 3 DIM was 8.85 ± 0.20 mg/dL in healthy cows compared to 8.30 ± 0.22 mg/dL in cows that subsequently developed endometritis (P < 0.05). NEFA concentrations at 10 DIM and BHB concentration at 10 and 30 ± 4 DIM were higher (P < 0.05) in cows that subsequently developed endometritis. Serum NEFA concentration at 10 days postpartum is the best predictor for diagnosis of clinical endometritis with the AUC values of 0.741. The cows with clinical endometritis also had significantly higher values of glucose at 3 DIM and lower BCS at 10 DIM (P < 0.05). While 58.6% of the cows that developed clinical endometritis were cyclic, 64.5% were cyclic in healthy cows at 30 ± 4 DIM. Serum NEFA concentration was the only risk factor for clinical endometritis at 10 DIM. In addition, a decrease in serum Ca at 3 DIM and increase in NEFA and BHB concentrations at 10 and 30 ± 4 DIM may be associated with clinical endometritis and delayed resumption activity on the ovaries.
Genetic variability among canine parvovirus strains currently circulating in Poland
Authors: WÓJCIK ALICJA , ZIĘTEK JERZY , STANIEC MARTA , WINIARCZYK STANISŁAW
Published: February 2021

The aim of the study was to perform a molecular analysis of the CPV VP2 gene fragment isolated from faeces samples of 46 dogs (vaccinated, as well as non-vaccinated against parvovirosis) with clinical parvovirosis. In all animals, the infection was confirmed by PCR. The purified PCR products (fragment VP2 gene) were sequenced and compared to each other and to the sequences of CPV VP2 gene from NCBI GenBank. Readable sequences of the VP2 gene were obtained for 46 samples. In 23 out of 30 non-vaccinated dogs, the most frequently isolated CPV strain was 2b. In the remaining cases the dogs were infected with CPV-2a. The parvovirus strains isolated from faeces of vaccinated dogs were classified in most cases (14/16) as CPV-2b, one as CPV-2a and one as CPV-2c. Continuous monitoring of parvovirosis in dogs in Poland plays an important role in updating vaccines against the disease and developing effective methods of its prevention.
Dual direct torque control of doubly fed induction machine using second order sliding mode control
Authors: Boumaraf Farid , Boutabba Tarek , Belkacem Sebti
Published: February 2021

In this paper a dual direct torque control (DDTC) strategy with second-order sliding mode control (SOSMC) controller of the doubly fed Induction motor (DFIM) is presented in order to overcome some drawback such as ripples in torque, flux and to improve dual direct torque control (DDTC) performance toward the electrical parameters variations. This control strategy used in the doubly fed induction machine supplied, coupled by two voltage source inverters in rotor and stator sides witches are linked to two switching tables in order to determined the rotor and stator flux vector control. This controller based on super-twisting algorithm (STA). Comparative results between a classical controller (PI) and the proposed controller can prove the very satisfactory performance and robustness of this new controller.