bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation of Induced Low Frequency Axial Vibration on Drilling Response of a PDC Bit
Authors: Trivedi Ajesh Sanjay , Mostofi Masood , Shor Roman J
Published: March 2021

This study investigates the impact of induced low frequency axial excitations on drilling actions of Polycrystalline Diamond Compact (PDC) bits. Variations in drilling efficiency have been documented through a series of experiments at different intensities (frequency and amplitude) of axial excitations. Prior work has identified the challenges of bit wear due to high frequency oscillations and an experimental validation is conducted to incorporate vibration related force changes into mechanical specific energy (MSE) to allow for identification while drilling. Axial vibrations were induced using a controlled linear actuator at the cutter-rock interface, in low frequency regime (up to 5 Hz) using a rotary experimental setup, based on state-of-the-art modified lathe machine. Through imposition of bit kinematics of angular velocity and rate of penetration (ROP), a PDC cutter was used to drill several cores of donnybrook sandstone, at a constant angular velocity of 100 revolutions per minute (RPM). A piezoelectric triaxial sensor measured the cutting forces: normal (weight) and shear (torque) force, at the cutter-rock interface. The results quantify variation of drilling response under several combinations of frequency, amplitude and cutting speed. It was observed that forces required to penetrate through rock were reduced with minimum effect on degree of wear on the cutter, mainly due to lower intensity of induced oscillations. This shows that once periodic axial oscillations are imposed, a lesser amount of energy is required to achieve same rate of penetration (ROP), thereby indicating improvement in cutting efficiency of the drilling process. The results from this study also provides experimental evidence for the need to incorporate vibration induced force losses into the equation of drilling efficiency for correct estimations of rock strength downhole.
Time-Series Data Augmentation Techniques for Improving Automated Drilling Dysfunction Classifiers
Authors: Yi Michael , Ramos Dawson , Ashok Pradeepkumar , Thetford Taylor , Bohlander Spencer , Noworyta Mickey , Behounek Michael
Published: March 2021

Detecting drilling dysfunctions from surface data is not always easy as downhole vibrations tend to get damped before they reach surface sensors. Building machine learning models to recognize patterns in the surface data requires vibration signals captured by downhole sensors for training purposes. Such datasets are not widely available and therefore a methodology to expand these datasets is highly desirable. This work explores ways to utilize data augmentation to artificially diversify and increase datasets to build better models.

Stick-slip (including full-stick), bit bounce, whirl, and bit balling are the primary dysfunctions considered in this work. Bayesian networks are used as classifiers to keep the model intuitive, and address situations where some input data is missing or unavailable. Once the dysfunction events in the downhole dataset were labeled, data augmentation techniques were used to generate synthetic data for scenarios where data was sparse.

The dataset used in the project consisted of nine wells (with 19 bit runs). Most of the bit runs had a downhole vibration sensor at the bit, while some had sensors along the string as well. Of these 19 bit runs, 15 were used for training and four were used to test the models. Various data augmentations techniques were applied, and validated manually as appropriate synthetic data. In the case of full-stick event detection, the saw tooth pattern in the surface torque signal was captured and provided as an input to the classifier. The classifiers thus trained were able to detect the dysfunctions using data from surface sensors to a high level of accuracy and with low false alarm rates.

This paper presents models to predict downhole dysfunctions from surface data alone. This paper also provides guidance on data augmentation techniques that use sparse downhole datasets to improve machine learning drilling advisory models. For identifying drilling dysfunction from surface data, the tortuosity of the well is also taken into account.
A Hybrid Test Environment for Verification of Drilling Automation Systems
Authors: Gravdal Jan Einar , Sui Dan , Nagy Attila , Saadallah Nejm , Ewald Robert
Published: March 2021

The transition towards drilling automation put high demands on new software for controlling or assisting during drilling. Along with the software development, adequate infrastructures for testing and verification of this software need to be in place. In other industries, such as aviation, the development of advanced simulators goes hand in hand with the technological developments and ensures a fit for purpose test environment at all time.

Since 2017, a high-fidelity online drilling simulator has been available to the public. The purpose has been to facilitate and accelerate the development and testing of real-time drilling automation systems.

The simulator can be accessed through a web Application Programming Interface (API) and run from a web client, or in a Hardware-in-the-loop (HIL) simulator from a control system environment with programmable logic controllers (PLCs) from leading industry vendors. To facilitate testing and verification of systems also on real data, recent developments have enabled a user-friendly access to openly available drilling data through the web API. Automatic functions have been developed to create model configurations from recorded data sets. This setup enables benchmarking of simulation models against recorded data and allows efficient verification of drilling automation systems.

The web enablement makes the infrastructure suitable for development projects and software verification from anywhere in the world without any installation needed. Better availability of realistic and scalable test environments for automated drilling systems is expected to speed up the qualification of new drilling technologies. This will in turn reduce costs and minimize the carbon footprint from drilling operations.

This paper describes the hybrid test environment and key learnings from the developers and user's perspective.
Improving Surface Oscillation Tools Performance Using Time-Domain Dynamics and Torque and Drag Models
Authors: Mahjoub Mohamed , Dao Ngoc-Ha , Nguyen Khac-Long , Badri Seif , Summersgill Matthew , Menand Stéphane
Published: March 2021

Overcoming friction in sliding mode represents a challenging task when drilling an unconventional well with a long lateral section. Among the possible ways to reduce these frictional forces is to use a surface oscillation tool (SOT). By alternating the rotation at surface between the forward and reverse directions, a part of the friction forces is transferred from the axial to tangential direction. Hence, a better transmission of the weight to the drill bit and increased rate of penetration can be achieved. To take full advantage of this tool, an accurate and fast modeling of the influence of its oscillation characteristics is necessary.

The SOT is operated at surface by changing its rotation speed and number of wraps in forward and reverse directions. If these characteristics are underestimated, the torsional oscillationsare quickly stopped by the friction moments, and the rate of penetration is not increased enough. However, if they are over estimated, the torsional oscillations can reach the bent motor, and destabilize the tool face orientation (TFO). In this paper, a full time-domain dynamics model and a simplified model coupled with a stiff-string torque and drag model are used to identity the influence length of the SOT, and hence provide an opportunity to optimize its operating parameters.

Full and simplified models are compared to each other to ensure their validity. Namely, the effect of the drillstring-wellbore contact distribution is showed to have a substantial impact on the SOT performance. Consequently, it was proved that optimal SOT characteristics Off-Bottom are generally not enough to overcome the friction when drilling. In addition, the torque and drag model is applied to a real case study of an unconventional well with surface and downhole data. It helps provide the driller with a guideline of recommendations on the SOT parameters. These results open some very interesting perspectives in terms of TFO accuracy and slide optimization.

The use of modelling in the calibration of the SOT characteristics and the development of the simplified model are both novelties introduced here. This work should lead to significant improvement to extend the length of laterals with steerable mud motor with minimum tortuosity.
Integrated Approach for Successful Well Abandonment Under Challenging Well Conditions – A Case Study
Authors: Isgenderov Islam , Osayande Victor , Nafikova Svetlana , Prasetyo Fajar Budi , van El Wouter Alexander
Published: March 2021

Emerging technologies, stringent permanent well abandonment regulations, and increasing well complexity affect the way we execute well intervention operations. One of the major operators in the Netherlands had an objective to set underbalanced cement plugs in brine across a deviated section using managed-pressure equipment to overcome high reservoir bottomhole pressure. The project involved several challenges: large-diameter production casing with a requirement to maintain high shut-in wellhead pressure, complex wellbore geometry, operations from a workover rig with zero discharge allowance, corrosive salt environment, and small cement slurry volume. These challenges had to be addressed to complete well abandonment to minimize safety risks, maximize efficiency, and achieve compliance with industry standards and regulatory requirements.

This paper discusses two case studies involving underbalanced pump-and-pull and conventional balanced plug placement techniques. Thorough analysis and risk assessment, engineering design approach, comprehensive laboratory testing, and fit-for-purpose surface equipment and downhole tools enabled flawless job execution and placement and achievement of long-term zonal isolation. The first well-barrier elements were successfully verified by tagging and pressure testing in both cases.

Results of this study include the following observations and conclusions: Managed-pressure cementing was proven to be an ideal solution for a well abandonment in a reservoir environment of high bottomhole pressure.Highly magnesium-resistant cement slurry design should be considered when setting cement plugs across an extremely corrosive salt environment.Successful verification of the first well-barrier element simplifies operations for subsequent cement plugs.

Cost-effective solutions for permanent well abandonment under challenging downhole conditions attracts increasing interest from petroleum engineers due to increasing well complexity and low oil prices that challenge the economics of wells, leading to abandonment. The current paper describes the challenging conditions under which the wells had to be abandoned, thorough analysis of the risks involved, and an effective solution. The design strategy, execution, evaluation, and results for these two wells are discussed in detail and will help to guide success and solve problems related to permanent well abandonment under similar challenging conditions.
Multi-Trajectory Hydraulic Model for More Accurate Geosteering Constraints
Authors: Alyaev Sergey , Daireaux Benoit
Published: March 2021

At the well-planning stage target selection usually accounts for drillability. However, during geosteering operations the drilling constraints are not updated and some fixed limits in terms of maximal inclination, dogleg severity, etc., are used instead. We demonstrate a methodology that uses fast physical models of the drilling hydraulics to calculate constraints and costs for geosteering dynamically during an operation.

In field development, many companies have adopted workflows that use ensemble-based methods for decision support. A real-time variation of such a decision support system (DSS) has been recently proposed for geosteering. The DSS is capable of optimization full well trajectories across all realizations of the earth model and can consider multiple objectives and constraints simultaneously. We present a method that makes steady-state hydraulic computations for all possible trajectories ahead-of-bit simultaneously at a low added cost. The output of the computation can provide more precise constraints (geo-pressure margins and cuttings transport) and cost estimates for the DSS.

In this paper we focus on verification and testing of the proposed multi-trajectory hydraulic model (MTHM). Discretization of the model acts as a trade-off between the preciseness of the computation and the computational speed. On our benchmark cases, a simulation that computes the hydraulic parameters for all trajectories with acceptable errors is fast enough for real-time geo-steering applications. Furthermore, we present a case based on data from the Norwegian Continental Shelf for which we demonstrate how hydraulic computations would influence the decisions of steering and stopping. Applying the DSS with the MTHM allows to precisely update the allowed steering interval, thus achieving safe operation while maximizing the expected well profit.

We emphasize that integration of the drilling processes modelling as part of the decision support for the geosteering operation enables better decisions. This is facilitated by the digitalization of the oil industry, but still requires development of new approximate models of the drilling processes. This paper demonstrates the MTHM as an initial step towards integration of drilling and geosteering modelling.
Analysis Behind Casing to Assess Zonal Isolation and Casing Deterioration in a High Pressure Exploratory Well - ABC to Z of Well Integrity Barrier Evaluation
Authors: Ahmed Hassaan , Khan Mohammad Rasheed , Bari Abdul , Rashid Kamran , Ali Syed Dost , Dhawan Sandeep , Zubair Talha , Anjum Usman , Sookram Neil
Published: March 2021

The UHP exploratory well subject of this study faced with myriad challenges, including fishing, side-tracking, and other undesirable incidents with consequences to the 9-7/8" production casing. Torque and drag analysis, preliminary casing wear simulations, and actual drilling parameters pointed towards multiple uncertainties concerning barrier integrity. Consequently, a multi-physics evaluation was conducted including well-integrity logs in a combination of thickness-mode with flexural-mode of the casing. Signals from these independent measurements are then processed to provide robust interpretation of solid-liquid-gas behind casing using acquired flexural attenuation and acoustic impedance data. In addition, casing wear is quantified by thickness changes measured through the resonance frequency of the waveform and represented in the form of a joint-by-joint corrosion summary, reporting the average metal loss. Furthermore, propagation of flexural wave-fronts as it leaks to the third interface is tracked to produce a unique image of the annulus geometry in terms of casing eccentricity and acoustic velocity of the medium. Subsequently, the former, provides a quantifiable, unique in-situ casing standoff measurement to be used for centralization evaluation.

Application of the developed data-integrated workflow allowed for comprehensively analyzing well integrity barrier condition. Cement barriers were assessed with confidence by flexural imaging, which were difficult to determine solely with pulse-echo. Additionally, annulus imaging using third interface-echo (TIE) helped in characterizing the potential causes of casing wear and quality of cement behind casing by providing actual in-situ casing standoff. It was observed that casing wear was at the low side of the wellbore where the casing had the least standoff as shown by flexural waveform TIE arrivals. Moreover, high percentage of metal loss was correlated to regions with centralization lower than 40-50%. Integration of these results with casing side forces and remaining casing strength (under worst case scenario) was performed to evaluate casing endurance for future drilling, production, and injection operations.
Oil and Gas Drill Bit Technology and Drilling Application Engineering Saves 77 Drilling Days on the World’s Deepest Engineered Geothermal Systems EGS Wells
Authors: Cardoe Jennifer , Nygaard Gunnar , Lane Christopher , Saarno Tero , Bird Marc
Published: March 2021

An Engineered Geothermal System (EGS) pilot project was commissioned to prove the economic viability of an industrial scale geothermal heat plant in Finland. The project aims to generate 40 MW of emission free heat energy, supplying up to 10% of the city of Espoo’s district heating needs. Two wells of 6400 m MD and 6213 m MD (measured depth) were drilled through formations of hard, abrasive granitic gneiss with maximum measured 560 MPa UCS (unconfined compressive strength). Typical dull conditions of lost and worn cutting structure and gauge diameter wear of between 3/16-in to ¼-in contributed to excessive torque, stuck incidences, low rate of penetration (ROP) and difficulties achieving build rate. To address these drilling challenges, this paper explores the interplay between new cemented carbide compact technology, drill bit design, and drilling parameter road mapping.

The directional section of the first well was drilled with an average ROP below 2 m/hr and run length averaging 56 m per bit. The well took 246 drilling days and 44 BHAs (bottom hole assemblies) to achieve TD (total depth). Between the first and second well an application specific drill bit design package and step-wise parameter program were implemented. Design enhancements included improved gauge protection, bit hydraulics for minimizing cone erosion and subsequent TCI (tungsten carbide insert) compact loss. Novel hybrid TCI materials technology was introduced having a 100% improvement in wear resistance and durability as compared with conventional grades, to drill these hard and abrasive granitic formations.

New BHAs and drilling plan were selected based on the bit design selection to reduce wear on BHA components, improve directional control and reducing drilling dysfunctions. Once these factors were under control, a low risk approach to extending the bit revolution limits (krev) for the roller cone sealed bearings could be implemented based on downhole parameters and previous bit dulls, leading to longer run lengths.

The combination of bit design and material enhancements with a properly selected BHA and drill plan increased run lengths and ROP. The second well’s 8.5-in directional section was drilled with a 13% increase in average ROP and a 69% increase in average run length without exceeding krev limits. Well on well, a 77 day reduction in AFE (authorization for expenditure) was realized.

We demonstrated the combination of oil and gas bit and BHA design, drilling plan, and new cutting material capabilities can reduce EGS well construction costs in order to make these renewable energy sources economical.
Drill Bit Failure Forensics using 2D Bit Images Captured at the Rig Site
Authors: Ashok Pradeepkumar , Chu Jian , Witt-Doerring Ysabel , Yan Zeyu , Chen Dongmei , van Oort Eric
Published: March 2021

Identifying the root cause of damage of a pulled bit as soon as possible will aid preparation for future bit runs. Today, such bit damage analyses are often anecdotal, subjective and error-prone. The objective of this project was to develop a software algorithm to automatically analyze 2D bit images taken at the rig site, and to quickly identify the root cause of bit damage and failure.

A labelled dataset was first created whereby the damage seen in bit photos was associated with the appropriate root cause of failure. Particular attention was given to the radial position of the cutters that were damaged. Using the 2D bit images (which can be obtained at the rig site), a convolutional neural network along with other image processing techniques were used to identify the individual cutters, their position on the bit, the degree of wear on each cutter. A classifier was then built to directly identify root cause of failure from these images.

This work utilized a large dataset of wells which included multiple bit images, surface sensor data, downhole vibration data, and offset well rock strength information. This dataset helped relate the type of dysfunction as seen in the downhole and surface sensor data to the damage seen on the bit. This dataset however only covered some types of dysfunctions and some types of bit damage. It was therefore augmented with bit images for which the type of failure was determined through analysis by a subject- matter expert. A classifier was subsequently developed which properly identified the root causes of failure when the bit photo quality met certain minimum standards. One key observation was that bit images are not always captured appropriately, and this reduces the accuracy of the method.

The automated forensics approach to Polycrystalline Diamond Compact (PDC) bit damage root cause analysis described in this paper can be performed using 2D bit photos that can be easily captured on a phone or camera at the rig site. By identifying the potential root causes of PDC damage through image processing, drilling parameters and bit selection can be optimized to prolong future bit life. The algorithm also enables uniformity in bit analysis across a company's operations, as well as the standardization of the process.
Association Between Serum Chemokine Cc-motif Ligand 17 and Prognosis of Patients at Risk for Coronary Heart Disease
Authors: Tian Ran , Feng Si-Qin , Wang Lei , Wang Yi-Fei , Wang Yi-Yang , Chen Yu-Xiong , Wang Hui , Liu Hong-Hong , Zhang Shu-Yang
Published: March 2021

BackgroundIt has been reported chemokine CC-motif ligand 17 (CCL17), an inflammatory mediator modulating T cells function to affect formation and stableness of atherosclerotic plaque and is associated with the severity of coronary heart disease (CHD). This research aims to further explore the relationship between serum CCL17 and the prognosis of patients at risk for CHD.MethodThis study retrospectively enrolled 495 patients receiving coronary angiogram at Peking Union Medical College Hospital from January 2012 to December 2013. Serum CCL17 was measured on admission and annual routine telephone follow-up was carried out till December 2020. The prognosis of patients was evaluated by the incidence of major adverse cardiovascular events (MACE). Cox survival analysis have been applied for univariate and multivariate models setting., Machine learning and data imbalance methods were also added to improve the model performance.ResultsCompared with patients with low serum CCL17 level, patients with medium and high serum CCL17 demonstrated elevated risk to develop MACE, with the hazard ratio (HR) being 4.53 [95% confidence interval (CI) 2.08-9.88] and 6.38 (95% CI 3.07-13.28) respectively. CCL17 served as an independent risk factor to predict the incidence of MACE and the addition of CCL17 to the baseline risk model significantly increase the predictive ability for MACE (Area under curve: baseline risk model 0.803±0.021 vs baseline risk model+CCL17 0.836±0.021, p for comparison<0.001).ConclusionsElevated CCL17 functions as an independent predictor for MACE in patients at risk for CHD and the potential mechanisms deserved more exploration in the future.
Percutaneous Radiofrequency Rhizotomy for Prompt Pain Management in Peculiar Cases of Trigeminal Neuralgia
Authors: Zaragita Nadya , Prasetya Mustaqim , Sulistyanto Adi
Published: March 2021

Background: Trigeminal neuralgia is a neurological condition characterized by episodes of intense stabbing or electric shock-like pain caused by disorder of the fifth cranial nerve. Most TN cases are caused by vascular compression, but rarely it can be caused by tumor or autoimmune diseases (e.g. multiple sclerosis). Case presentation: We report two rare cases of secondary trigeminal neuralgia caused by tumors. The 1st patient is a 38 year old male with intractable pain and MRI result suggestive of trigeminal schwannoma at the left cerebellopontine region, while the 2nd patient is a pregnant 26 year old female with MRI result suggestive of an epidermoid cyst at left cerebellopontine region compressing the trigeminal and and facial nerve. Surgical option was declined by both patients because of the associated risks although immediate pain relief was needed. Percutaneous radiofrequency rhizotomy (PRFR) was chosen for prompt pain management and results showed immediate pain relief. Conclusion: We conclude that PRFR is an effective option for pain management in secondary trigeminal neuralgia patient in whom primary treatment for the underlying cause is not feasible.
Impact of relative humidity and water availability on the life history of the predatory mite Amblyseius swirskii
Authors: San Phyu Phyu , Tuda Midori , Takagi Masami
Published: March 2021

The predatory mite Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) is currently used as an efficient biological control agent of thrips, whiteflies and spider mites, which are economically damaging pests of ornamental plants and vegetable crops grown in greenhouses and fields worldwide. Currently, the effects of relative humidity (RH) and water availability on the optimal growth of A. swirskii are unknown. Here, we test the combined effects of different levels of RH (33%, 53%, 73% and 92%) and water availability on the development and reproduction of male and female A. swirskii feeding on the dried fruit mite, Carpoglyphus lactis (Linnaeus). While eggs failed to hatch at 33% RH, the survival rates of the immature stages at ≥ 53% RH increased solely in response to water availability and not due to changes in RH. Regarding growth and development, low RH extended the egg–adult duration and pre-oviposition period. We also found that the negative effects of low RH on adult longevity and fecundity were partially or completely eliminated when drinking water was available. For the life table parameters, the highest values of net reproductive rate (R0) and intrinsic rate of natural increase (r) were achieved at the highest RH when drinking water was available. Overall, water availability mitigated the negative effect of low RH on female reproduction, and female development was more sensitive to water availability than male development. Lastly, a comparison of similar research on A. swirskii suggested that water availability and RH are more influential on r than food source or temperature.
Coastal wetlands mitigate storm flooding and associated costs in estuaries
Authors: Fairchild Tom , Bennett William , Smith Greg , Day Brett , Skov Martin , Möller Iris , Beaumont Nicola , Karunarathna Harshinie , Griffin John
Published: March 2021

As storm-driven coastal flooding increases under climate change, wetlands such as saltmarshes are held as a nature-based solution. Yet evidence supporting wetlands’ storm protection role in estuaries - where both waves and upstream surge drive coastal flooding - remains scarce. Here we address this gap using numerical hydrodynamic models within eight contextually diverse estuaries, simulating storms of varying intensity and coupling flood predictions to damage valuation. Saltmarshes reduced flooding across all studied estuaries and particularly for the largest – 100-year – storms, for which they mitigated average flood extents by 35% and damages by 37% ($8.4M). Across all storm scenarios, wetlands delivered mean annual damage savings of $2.7M per estuary, exceeding annualised values of better-studied wetland services such as carbon storage. Spatial decomposition of processes revealed flood mitigation arose from both localised wave attenuation and estuary-scale surge attenuation, with the latter process dominating: mean flood reductions were 17% in the sheltered top third of estuaries, compared to 8% near wave-exposed estuary mouths. Saltmarshes therefore play a generalised role in mitigating storm flooding and associated costs in estuaries via multi-scale processes. Ecosystem service modelling must integrate processes operating across scales or risk grossly underestimating the value of nature-based solutions to the growing threat of storm-driven coastal flooding.
Enhanced Cercosporin Production by Co-culturing Cercospora Sp. JNU001 With Leaf-Spot-Disease-Related Endophytic Bacteria
Authors: Zhou Tingan , Yu Shiyu , Hu Yifan , Zhang Yan , Song Yuechen , Chu Jieyu , Liu Changmei , Rao Yijian
Published: March 2021

Background: Owing to the excellent properties of photosensitization, cercosporin, one of naturally occurring perylenequinonoid pigments, has been widely used in photodynamic therapy, or as an antimicrobial agent and an organophotocatalyst. However, because of low efficiency of total chemical synthesis and low yield of current microbial fermentation, the limited production restricts its broad applications. Thus, the strategies to improve the production of cercosporin were highly desired. Besides traditional optimization methods, here we screened leaf-spot-disease-related endophytic bacteria to co-culture with our previous identified Cercospora sp. JNU001 to increase cercosporin production. Results: Bacillus velezensis B04 and Lysinibacillus sp. B15 isolated from leaves with leaf spot diseases were found to facilitate cercosporin secretion into the broth and then enhance the production of cercosporin. After 4 days of co-culture, Bacillus velezensis B04 allowed to increase the production of cercosporin from 128.2 mg/L to 984.4 mg/L, which was 7.68-fold of the previously reported one. Lysinibacillus sp. B15 could also enhance the production of cercosporin with a yield of 626.3 mg/L, which was 4.89-fold higher than the starting condition. More importantly, we found that bacteria B04 and B15 employed two different mechanisms to improve the production of cercosporin, in which B04 facilitated cercosporin secretion into the broth by loosening and damaging the hyphae surface of Cercospora sp. JNU001 while B15 could absorb cercosporin to improve its secretion.Conclusions: We here established a novel and effective co-culture method to improve the production of cercosporin by increasing its secretion ability from Cercospora sp. JNU001, allowing to develop more potential applications of cercosporin.
The structural transformation comparison of the human Prion protein mutants V176G, E196A, and I215V by using molecular dynamics simulation
Authors: Jomah Ashraf Fadhil , Parvizpour Sepideh , Razmara Jafar , Shamsir Mohd Shahir
Published: March 2021

The point mutations in the gene coding of prion protein (PrP) originate human familial prion protein (HuPrP) diseases. Such diseases are caused by several amino acid mutations of HuPrP including V176G, I215V, and E196A located at the second, third native helix and in their loop, respectively. Determining the transition from cellular prion protein (PrPc) to pathogenic conformer (PrPSc) in the globular domain of HuPrP that results in pathogenic mutations is the key issue. The effects of mutation on monomeric PrP are detected in the absence of an unstructured N-terminal domain only. A MD simulation for each of these wild type mutants is performed to examine their structure in the aqueous media. The structural determinants are discerned to be different for wild-type HuPrP (125–228) variants compare to that of HuPrP mutations. These three mutations exhibiting diverse effects on the dynamical properties of PrP are attributed to the variations in the secondary structure, solvent accessible surface areas (SASAs), and salt bridges in the globular domain of HuPrP. High fluctuations that are evidenced around residues of the C-terminus of the helix 1 for V176G cause Gerstmann-Straussler-Scheinker (GSS) syndrome. Conversely, the occurrence of fluctuations around residues of helix 2, helix 3, and the loss of salt bridges in these regions for E196A and I215V mutants is responsible for Creutzfeldt-Jakob disease. Furthermore, small changes in the overall SASAs mutations strongly influence the intermolecular interactions during the aggregation process. The comparative results in this study demonstrate that the three mutants undergo different pathogenic transformations.
Comparison of Properties Determined Using Electromechanical Assessment (Arthro-BSTTM) With Macroscopic and Histological Properties in Symptomatic Human Articular Cartilage of the Hip
Authors: Ukai Taku , Sato Masato , Wasai Shiho , Takahashi Takumi , Omura Haruka , Watanabe Masahiko
Published: March 2021

Background: Cartilage degeneration is assessed using various methods. Although macroscopic evaluation can measure cartilage degeneration directly, it cannot accurately assess cartilage properties. Histological examination is one of the most accurate methods for evaluating cartilage degeneration. However, it is invasive and requires collection of cartilage tissue. By contrast, the Arthro-BSTTM probe can assess cartilage properties noninvasively. This study aimed to evaluate the effectiveness of the Arthro-BST for assessing cartilage degeneration by comparing macroscopic evaluation (International Cartilage Repair Society [ICRS] classification) and histological evaluation (modified Mankin score and Osteoarthritis Research Society International [OARSI] histological grade).Methods: Fourteen femoral heads were excised from 13 patients during surgery to treat hip osteoarthritis or femoral fracture. The ICRS score was used for macroscopic evaluation of cartilage degeneration. The Arthro-BST was applied at sites matching the areas of cartilage damage. The sites assessed using the ICRS classification and Arthro-BST were evaluated histologically (modified Mankin score and OARSI histological grade), and these were compared with the Arthro-BST results.Results: ICRS classification identified significant differences between grades 1 and 3 (p < 0.01), grades 1 and 4 (p < 0.01), grades 2 and 3 (p < 0.01), and grades 2 and 4 (p < 0.01). Significant correlations were observed between the Arthro-BST results and the ICRS score, modified Mankin score (structure, cellularity, matrix staining, total score), and OARSI histological grade.Conclusions: In the assessment of hip osteoarthritis, Arthro-BST results correlated with those of macroscopic and histological evaluation. The Arthro-BST is useful for assessing hip osteoarthritis and may be helpful for the noninvasive assessment of cartilage degeneration.
Trichinella spiralis ESP inhibits tumor cell growth by regulating the immune response and inducing apoptosis
Authors: Ding Jing , Liu Xiaolei , Tang Bin , Bai Xue , Wang Yang , Li Shicun , Li Jian , Liu Mingyuan , Wang Xuelin
Published: March 2021

Background

Although Trichinella spiralis (T. spiralis) causes zoonotic diseases, it has a strong immunomodulatory effect and has therapeutic potential for various autoimmune diseases and cancers. Our previous study results showed that T. spiralis infection can inhibit the growth of liver cancer cells, but the specific mechanism has not been elucidated.
Methods

BALB/c mice injected with H22 cells and then infected with T. spiralis were used to detect tumor inhibition rate. Cell proliferation and apoptosis of H22 cells treated with excretory-secretory product (ESP) were measured by Cell-Counting Kit 8 (CCK-8) and Flow Cytometry (FCM). The expression of apoptosis-related genes in H22 cells and tumor tissues was detected by western blotting and real-time quantitative PCR (qPCR). IL-2, IFN-γ and IL-4 production in the spleens were measured by qPCR and enzyme-linked immunosorbent assay(ELISA).
Results

The growth of tumors in tumor model mice infected with T. spiralis was significantly inhibited compared with those uninfected tumor model mice. ESP could inhibit H22 cell proliferation and induce apoptosis through the mitochondrial pathway both in vitro and in vivo. Additionally, the levels of Th1 cytokines with antitumor effects were significantly increased in the early stage of T. spiralis infection, while Th2 cytokines increased later than Th1 cytokines.
Conclusions

ESP can directly induce tumor cell apoptosis and indirectly inhibit tumor cell growth through the host immune system, which is the potential antitumor mechanism of T. spiralis infection.
Single-Cell Conventional Pap Smear Image Classification Using Pre-Trained Deep Neural Network Architectures
Authors: Mohammed Mohammed Aliy , Abdurahman Fetulhak , Ayalew Yodit Abebe
Published: March 2021

Background: Automating Pap smear based cervical cancer screening could alleviate the challenge related to the shortage of skilled manpower, mainly pathologists in developing countries. The astonishing accuracy and reproducibility of deep neural networks in computer vision have made them a frontline candidate to tackle such challenges. In this regard, the main purpose of this research project is to classify single-cell Pap smear microscopic images using the architectures of the pre-trained deep convolutional neural network image classifiers. We have trained five class single-cell Pap smear images from SIPaKMeD on top ten pre-trained image classification architectures. The architectures were selected from Keras Applications based on their top 1% accuracy. Then, the output layers of the selected architectures were fine-tuned from 1000 classes to five classes and retrained. Results: Our experimental result demonstrated that DenseNet169 outperformed the selected 10 pre-trained architectures with an average accuracy, precision, recall and f1-scores of 0.990, 0.974, 0.974 and 0.974, respectively. Moreover, it dashed the benchmark accuracy proposed by the creators of the dataset with 3.70%. Conclusions: Even though the size of DenseNet169 is small compared to the experimented architectures, still it is not suitable for mobile and edged devices. It is required to experiment with mobile or small size image classification neural network architectures.
Association of Serum Magnesium and Blood Pressure in Patients with Hypertensive Crises: A Retrospective Cohort Study
Authors: Onor IfeanyiChukwu O. , Hill Lashira M. , Famodimu Modupe M. , Coleman Mallory R. , Huynh Carolkim H. , Beyl Robbie A. , Payne Casey J. , Johnston Emily K. , Okogbaa John I. , Gillard Christopher J. , Sarpong Daniel F. , Borghol Amne , Okpechi Samuel C. , Norbert Ifeyinwa , Sanne Shane E. , Guillory Shane G.
Published: March 2021

Background: The role of magnesium in blood pressure has been studied among hypertensive patients, however, no study has explored the role of magnesium in hypertensive crises. The primary objective of this study is to evaluate the relationship between serum magnesium and blood pressure in patients with hypertensive crises.
Methods: This study is a single-center, retrospective, chart review, cohort study of patients with hypertensive crises. Patients were included in the study cohort if they were eighteen years of age or older with an international classification disease ninth revision (ICD-9) code of 401.9 (hypertensive crises: emergency or urgency) and a documented magnesium level on their electronic medical record. The primary outcome of the study was to assess the correlation between serum magnesium on blood pressure (systolic blood pressure and diastolic blood pressure) in patients with hypertensive crises. The secondary outcomes were to assess the association between serum calcium, corrected calcium, and serum potassium on blood pressure in patients with hypertensive crises and to determine the effects of covariates in modulating the relationship between serum magnesium and blood pressure.
Results: Two hundred and ninety-three patients were included in the study. The primary outcome result showed that serum magnesium was positively correlated with systolic blood pressure (r=0.143, p=0.014), but not diastolic blood pressure. Serum calcium was also found to be positively correlated with systolic blood pressure, but not diastolic blood pressure. After adjusting for covariates in the solution for fixed effects analysis, serum magnesium, serum calcium, corrected calcium, and use of home proton pump inhibitors were correlated with systolic blood pressure at crises; while age, serum calcium, and corrected calcium were significantly correlated with diastolic blood pressure at crises.
Conclusion: This study found a significant positive association between magnesium and systolic blood pressure, but not diastolic blood pressure among patients with hypertensive crises. This positive association of serum magnesium with systolic blood pressure was maintained after adjusting for covariates. This study findings suggests a potential role of magnesium in blood pressure among patients with hypertensive crises. Future studies should evaluate the role of serum magnesium modifying therapies in controlling blood pressure in patients with hypertensive crises.
Extension of In-Gap Electronic-State Spectrum Extraction Technique Based on Transient Photo-Voltage Measurement
Authors: Lin Zedong
Published: March 2021

This article puts forward a novel insight for extraction of trap state density (DOST) based on the transient photo-voltage (TPV) experimental data. Inspired by the method based on the Gauss distribution model, we introduce a universal general distribution model and present a general technique of DOST distribution from the experimental data of TPV measurement. The method based on the exponential (Gauss) distribution model is the one (two) order special case of our method. Compared to the method based on the exponential model (applicable only when the TPV result satisfies linear relation) and Gauss model (applicable only when the TPV result satisfies quadratic function relation), our work is effective for arbitrary TPV result.
Changes in Oral Health-Related Quality of Life during Pregnancy
Authors: Gil-Montoya José Antonio , Leon-Rios Ximena , Rivero Tania , Expósito-Ruiz Manuela , Perez-Castillo Iñigo , Aguilar-Cordero María José
Published: March 2021

PurposeTo evaluate the evolution of perceived quality of life in relation to oral health during pregnancy and to determine the risk factors involved in this process. MethodsA follow-up study was carried out with pregnant Spanish women. Two oral examinations and an oral health-related quality of life (OHRQoL) assessment, using the OHIP-14 questionnaire, were performed in the first and third trimester of pregnancy. Data on sociodemographic characteristics, medical history, O’Sullivan Test measures, oral hygiene habits, history of caries, and periodontal status of participants were collected through structured medical-dental questionnaires. ResultsA complete dataset comprising 246 pregnant women was available for analysis. Overall scores for negative impacts on the OHIP questionnaire were significantly higher during late pregnancy (74%). This indicated a deterioration in oral health-related quality of life amongst participants. Items describing “painful aching”, “self-consciousness”, “unsatisfactory diet”, and “interrupted meals” showed the greatest increase between the first and third trimester of gestation. Multivariate analysis showed that pre-gestational/gestational diabetes mellitus and poor oral hygiene habits during the first trimester of gestation were directly associated with worse oral health-related quality of life during the third trimester of gestation (hyperglycemia: OR: 2.86; 95% CI: 1.019-8.050: p=0.043 / Oral Hygiene: OR: 1.33; 95% CI: 0.970-1.836; p=0.076). ConclusionsIn the present research, hyperglycemia during pregnancy and poor oral hygiene habits during the first trimester of gestation led to a higher risk of poor oral quality of life during late pregnancy.
Neural Network-Based Event-triggered Adaptive Asymptotic Tracking Control for Switched Nonlinear Systems
Authors: Li Baomin , Xia Jianwei , Sun Wei , Shen Hao , Zhang Huasheng
Published: March 2021

This paper addresses the event-triggered based adaptive asymptotic tracking control problem for switched nonlinear systems with unknown control directions based on neural network technique. A novel asymptotic tracking controller, in which Nussbaum functions are introduced to address the issue of unknown control directions, is designed by combining neural network control technology and event-triggered strategy. Different from the existing tracking control schemes, the proposed controller in this paper can guarantee that the tracking error ς 1 asymptotically converges to the origin and reduce the communication burden from the controller to the actuator. Finally, the effectiveness of the presented control design is proved by numerical examples.
Prediction Score Project for the Incidence of Cerebrovascular Events in Patients With Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention
Authors: Zhao Xiaoxiao , Liu Chen , Zhou Peng , Sheng Zhaoxue , Li Jiannan , Zhou Jinying , Chen Runzhen , Wang Ying , Chen Yi , Song Li , Zhao Hanjun , Yan Hongbing
Published: March 2021

BackgroundWe sought to develop and validate a novel marker-based risk score to improve stroke prognostication in patients with myocardial infarction (MI) undergoing primary percutaneous coronary intervention (PCI).MethodsA retrospective study was conducted and internally validated a new biomarker-based risk score for the incidence of stroke in 4103 patients with MI undergoing primary PCI who were randomized into a derivation and a validation cohort. Predictive values of markers and clinical variables were evaluated using Cox regression models and least absolute shrinkage and selection operator regression. The most important variables were included in the score, with weight proportional to the model coeﬃcients.ResultsSignificant predictors of the incidence of cerebrovascular events were age, history of atrial fibrillation, history of hypertension, Killip class, blood pressure group, target lesion involving branches, percutaneous transluminal coronary angioplasty, and thrombus aspiration. The models had good calibration and discrimination in derivation and internal validation. The areas under the curve (AUC) of the receiver operating characteristic (ROC) curve analysis for predicting cerebrovascular events were 0.773 and 0.766 for the derivation and validation cohorts, respectively, at 5-year follow-up. Survival ROC curves exported the best cut-off values and divided them into low-risk and high-risk groups using the R language. We conducted Kaplan–Meier survival analysis for the two groups. Both groups displayed significant difference in the derivation and validation cohorts (P=0.00003 and P=0.009, respectively). We compared the new prediction model to the CHADS-VASc score; the AUCs were 0.773 and 0.754, respectively.ConclusionThe prediction model was internally validated and calibrated in large cohorts of patients with MI receiving primary PCI therapy. This risk score incorporates allows re-evaluation of the risk of cerebrovascular events after undergoing primary PCI.