bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving Shale Wellbore Integrity through Membrane Efficiency and Geomechanics Solutions
Authors: Buranaj Hoxha Besmir , Ettehadi Reza , Porter Justin , Prasad Umesh , Ong See Hong
Published: November 2020

Drilling through shale is an inevitable endeavor for both conventional and unconventional oil and gas reservoirs, where for the latter acts as a source and trap rock – substantiating its position in operational difficulty. Shale formations tend to be anisotropic and typically characterized by high in-situ stresses. In certain shales, geomechanics is very important in understanding how to stabilize the wellbore. Overall, it can prescribe a correct mud weight (or rather the overbalance) to provide the mechanical stability (stress-induced). However, this over-balance can be rapidly destroyed due to the rise in shale pore pressure associated with the different potentials (hydro-, chemo-, thermo-) acting at the shale-fluid interface. These ‘potentials’ can have an effect on the borehole stability, where in several cases, create phenomena that are just recently being wholly understood.

From a chemo-mechanical perspective, designing the proper fluid that will maintain the stability of shale formation, over time, requires the knowledge of membrane efficiency that is crucial for the geomechanical effects on the wellbore. However, in current industry practices there are limited studies that integrate geomechanics with comprehensive drilling fluid properties. Typically, inputs are arbitrary assumptions when utilizing geomechanical software. Classic workflow during geomechanics design includes selecting suitable mud-weight window which do not exceed the fracture gradient (to prevent losses) or remain well above the collapse pressure (or pore pressure) whichever is more suitable to prevent kicks or blowout.

The work presented herein takes the workflow a step further, by introducing key parameters of relevant shale characteristics/behavior to current geomechanical software to provide more accurate wellbore stability simulations as a function of fluid properties (i.e. membrane efficiency). Two different shale types, Mancos and Pierre shale II, which significantly vary in their physical, chemical, mineralogical, and mechanical properties are selected for wellbore stability analysis. The methodology consisted of three phases, (1) shale characterization, (2) pore pressure transmission and membrane efficiency calculations, (3) wellbore stability simulations via geomechanics software. The software is an integrated software used to assess stress and wellbore stability by calculating a "borehole stress and failure orientation" module to perform concurrent simulations to determine stability parameters (mud weight, fluid activity, membrane efficiency) needed for drilling through complex shale.
Development of a New Oriented Perforating System for a Challenging Subsurface Environment
Authors: Haigh Mike , Morrison Alan , Crabtree Phil , Doornbosch Fokko
Published: November 2020

The Gorgon Stage 2 (GS2) project is a brownfield expansion of the existing Chevron-operated Gorgon Foundation Project (GFP). GS2 will maintain gas supply to the Gorgon liquified natural gas (LNG) plant by expanding the existing infrastructure with additional subsea wells in the Gorgon and Jansz-Io gas fields. Low installation risk and high life-cycle reliability were primary objectives of the GS2 well completions due to the high costs associated with subsea installation and intervention. The Gorgon subsurface environment is hostile with temperatures reaching 165°C, high concentrations of CO2 and predicted sand production. The risk to long-term sandface completion reliability is reduced significantly when the perforations are aligned toward the plane of maximum stress. To achieve the primary well objectives the GS2 project team selected shoot-and-leave, cased hole, oriented perforating (CHOP) as the Gorgon completion design.

Chevron partnered with a leading supplier of tubing-conveyed perforating (TCP) equipment to develop a highly reliable, internally oriented perforating system manufactured from corrosion-resistant alloy (CRA) material, an industry first. The development and engineering phase consisted of defining project requirements, component design, manufacture of test equipment, testing, and system integration tests. Charge testing was conducted under reservoir conditions to verify that perforating performance met minimum requirements. Other tests included verification of gun orientation accuracy at Gorgon down-hole temperatures, a significant undertaking by the TCP supplier.

Testing and qualification activities were performed at the TCP supplier's technology center with local Chevron oversight. Quality assurance (QA) procedures were revised to be more aligned with those typically used for completion equipment, because in the industry, TCP equipment has traditionally relied on vendor-specific QA procedures and in-house oversight. Quality plans were updated to reflect the changes and enable third-party inspection (TPI) during product manufacturing.

This paper will share the collaborative efforts of Chevron and the TCP supplier to design and qualify a CRA oriented perforating system and answer important questions such as "How will we build confidence that the TCP guns will orient correctly?" and "Will the perforating charges perform as required under Gorgon down-hole conditions?"
Influences of Proppant Embedment and Deformation on Micro-Sized Graded Proppant Injection Scheme
Authors: Liu Huifeng , Li Jiaxue , Xu Zhixiong , Yuan Zebo , Liu Jv , Ren Dengfeng , Feng Jueyong
Published: November 2020

The method of micro-sized graded proppant injection has been proposed in the industry to increase the size of the stimulated zone in naturally fractured reservoirs, especially CBM. However, big discrepancies between the modelling results of graded proppant injection and the experimental results have been observed. An analytical model of graded proppant injection with consideration of proppant embedment and deformation is established in this paper, and the influences of proppant embedment and deformation are investigated.

An analytical model of calculating the permeability of a fracture filled with partial monolayer proppant is established, and a linear elastic model of calculating proppant embedment and deformation is coupled into it to investigate the influences of proppant embedment and deformation on propped fracture permeability. The influences of proppant embedment and deformation on propped fracture permeability and the optimal proppant packing ratio are investigated. The influences of properties of proppant and rock on propped fracture permeability and the optimal proppant packing ratio are also studied. The graded proppant injection schedules with and without consideration of proppant embedment and deformation are compared and practical understandings are obtained.

The results show that the propped fracture permeability is reduced by more than 50% when the embedment or deformation extent reaches 18%. Neglecting proppant embedment and deformation will lead to an under-estimation of 15%-18% for the optimal proppant concentration during graded proppant injection. Proppant diameter has little influence on the optimal proppant packing ratio. Lower Elastic Modulus in the proppant or rock and/or smaller proppant particles leads to a higher optimal proppant packing ratio and lower permeability correction factors. Poisson's ratio of proppant or rock has very little influence on both optimal proppant packing ratio and permeability correction factor. Proppant concentrations at different stages of graded proppant injection with consideration of proppant embedment and deformation are 21.8% higher than those neglecting the two factors. Proppant embedment and deformation must be considered during planning of the graded proppant injection schedule.
Field Application of Nano Polymer Microspheres Profile Control: A Pilot Test in Ultra-Low Permeability Oil Reservoir
Authors: Hou Ganggang , Yuan Xinyu , Han Penggang , Lu Fan , Jiao Zhen , Diwu Pengxiang , Liu Tongjing , Hou Jirui
Published: November 2020

During the development of low permeability oil reservoirs, the problems of rapid breakthrough of water, non-uniform water-absorbing of injection well and the low efficiency of water flooding are usual facing. The application of polymer microspheres (PMs) for in-depth profile control is considered to be an effective method to solve these problems. This paper systematically reports a field application case of nanoscale PMs for in-depth profile control in the ultralow permeability oil reservoir. In the paper, the characteristics of static geological and dynamic production of Block A in Changing oilfield are analyzed in detail. Meanwhile, the production history and facing problems of the Block A are clarified. According to the analysis results, the pilot test area for the application of PMs in-depth profile control is selected, and its characteristics are described. Then, a detailed implementation scheme is made for the pilot test area. Finally, according to the evaluation parameters of production wells and injection wells, the performance of PMs in the pilot test area is evaluated. The performance evaluation results show that the application of PMs in the pilot test area is very successful, and the PMs can be used for in-depth profile control in the ultralow permeability oil reservoir. More specifically, the average injection pressure of single well increased by 1.1 MPa, and the average thickness of water absorption layer increased by 1.2 m after PMs injection. The success ratio of in-depth profile control was 37.3%, and the total oil production increment of production wells was 4609.2 t. In addition, comparing the performance of well groups that use the PMs with different calibration diameter, it indicates that the application of PMs with appropriate particle size and the reasonable implementation schemes are critical to the success of in-depth profile control. For the pilot test area, the PMs with the calibration diameter as 300 nm is more suitable.
New Cementing Spacer Technology Cures Total Lost Circulation in an Offshore Exploratory Well
Authors: Abad Juan , Ekwue Ann-Marie , Bermudez Francisco
Published: November 2020

During the drilling process of exploratory wells, the formation data is often limited; most of the time drilling engineers must estimate the pore pressure and fracture gradients. This information is critical for designing the drilling fluid, spacers, and cement slurry as to provide the necessary density and rheological properties.

An error in estimating the pore pressure or fracture gradients can induce wellbore instability and lost circulation. If these losses are not controlled, during the cementing job the programmed top of cement (TOC) will not be achieved, zonal isolation will be compromised, and the casing string will not be fully supported. These problems can lead to additional expenses such as remedial jobs, non-productive rig time, use of additional materials, costly logistics, etc.

This paper presents a case history with a critical cementing job in which the operator was drilling an offshore exploratory well in Southern Mexico when an area with constant gas flow with a narrow pore-pressure to fracture-gradient window was encountered. The operator had to increase the density of the drilling fluid, which in turn induced total losses.

The cementing company recommended pumping a unique spacer technology that enabled circulation to be regained while pumping the cementing job. This technology is an ultra-low invasion cementing spacer that creates an impermeable barrier on the face of the formation through differential pressure. This barrier helps to isolate the formation from the total equivalent circulating density (ECD), thus allowing circulation even in situations where the ECD approaches or slightly exceeds the fracture gradient.
Experimental Study on the Impact of Supercritical CO2 Soak Pre-Treatment on Re-Fracturing of Shale Oil Reservoirs
Authors: Tao Jiaping , Meng Siwei , Cao Gang , Gao Yang , Liu He
Published: November 2020

Initial hydraulic fracturing of shale oil reservoirs has often resulted in disappointing results, with low connected volumes and productivity degradation with depletion. To improve the single well production and oil recovery, re-fracturing techniques have received increased attention, but face the challenges of economy, applicability and feasibility.

In this paper, the propagation mechanism during re-fracturing operations is explored through laboratory experiments. Firstly, mechanical analysis and fracturing simulation experiments were performed using the formation cores. After the fracturing simulation experiment, the fractured core was soaked in supercritical CO2 to enhance the re-fracturing effect. Then a re-fracturing simulation experiment was performed to analyze the fracturing propagation mechanism. Meanwhile, some new cores are soaked into supercritical CO2 to explore the changes of mechanical properties under different soak time.

The mechanical analysis experiment showed that supercritical CO2 soak has a strong influence on the uniaxial compressive and tensile strength of shale. With an increase of soak time, both the compressive and tensile strength clearly decreased. During the first fracturing operation, fractures propagated only along the horizontal bedding and could not open the rock matrix. After supercritical CO2 soak, re-fracturing could open the horizontal bedding more easily as well as extend to the rock matrix, creating a more complex fractured system, enhancing oil recovery.
Fast Modelling of Gas Reservoirs Using POD-RBF Non-Intrusive Reduced Order Modelling
Authors: Samuel Jemimah-Sandra , Muggeridge Ann Helen
Published: November 2020

We demonstrate that the non-intrusive reduced order model (NIROM) based on proper orthogonal decomposition and radial basis function interpolation is capable of gas reservoir simulation predictions with computational speed-ups of at least an order of magnitude and potentially many orders of magnitude. It can estimate 3-dimensional spatial pressure and saturation distributions as well as production data for unseen gas reservoir simulation scenarios produced at constant bottom hole pressure or gas rate control.

The NIROM is created from a series of training simulations performed using a commercial simulator. These simulations produce "snapshots" of the pressure and saturation distributions at equally spaced time intervals. Proper Orthogonal Decomposition (POD) is then used to project these data into a higher dimensional hyperspace. Radial basis functions (RBF) are then used to both estimate the dynamics of the system and the behaviour for unseen inputs (such as well BHP or rate). The approach is demonstrated using 3 different reservoir models, including a realistic reservoir model using data taken from the Norne field.

The NIROM simulations produce satisfactory predictions when compared to a commercial simulator, provided the unseen inputs are within the range of training parameters and time scale covered by the simulation. On average, these results were obtained using 10 training runs. The overall improvement in speed is insensitive to reservoir model complexities, such as local grid refinement, water coning or the presence of aquifers. Reservoir models with significant water production require more NIROM simulation subspace vectors to estimate performance, compared with cases without water production. Furthermore, we show that although NIROM works well for constant well controls over time it is less accurate when estimating behaviour when the imposed well rate changes quickly at different times in the simulation.

This is the first time that POD-RBF NIROM has been applied and evaluated for pressure depletion problems, such as occur in gas reservoir performance prediction.
Pushing Malaysia's Drilling Industry into a New Frontier: How a Distinctive Wellhead Design Enable Implementation of a Fully Offline Well Cementing Resulting in Significant Shift in Operational Efficiency
Authors: Abbas Fauzi , M. Nor Azrynizam , Chang Daryl , Czapor Wojciech
Published: November 2020

Traditionally, rigs are positioned over a well from the moment the surface casing is drilled till the installation of the wellhead Christmas Tree. This resulted in the loss of precious rig time as the rig is idling during online cementing. However, in Field A, offshore of Terengganu, Malaysia, a new approach has managed to eliminate such inefficiency drastically. This paper discusses the employment of offline cementing techniques made possible with distinctive wellhead technology, that enabled a fast, efficient, and safe drilling and completion.

In this offshore drilling program, five wells were successfully batched drilled and cemented offline by ingenious planning and skidding of the rig. As the first well has reached its depth, offline adapters with pressure compatible cementing heads and accessories are installed on the wellhead. This allowed the rig to skid to the adjacent wells to continue drilling while the previous well was being cemented with the use of full bore offline cementing adapters. Full bore offline cementing adapters helped maintained familiarity by allowing the use of simple conventional wiper plugs. These offline adapters are compatible with both mandrel and slip hangers and have pressure bleed off and monitoring capabilities. These steps were then repeated in all of the wells, from the surface casing till the tubing of these mono bore completions. Besides that, production and casing hangers come with barrier plug profiles allowing plugs to be pre-made up and tested. This reduced installation time on the rig floor and ensure that there was a positively tested barrier, before nippling down the riser. Hangers with seals also allowed for a single trip installation, further reducing rig time.

The five wells were drilled and completed in record-breaking time at an average of 7 days per well and below budget, resulting in a time saving of 31 hours and 18.5% of cumulative savings. In conclusion, this wellhead technology introduced a new approach to drilling and completion allowing vast improvement to the field economics and profitability to the development of marginal fields.
Unconventional Gas Development in Queensland, Australia: How Well Does it Align with the ‘Golden Rules’ of Gas?
Authors: Witt Katherine , Garnett Andrew
Published: November 2020

In 2012, the International Energy Agency (IEA) released the ‘Golden Rules for a Golden Age of Gas’ - a set of best practice guidelines for unconventional gas development designed to address key environmental and social risks and gain public acceptance of the industry. This study sought primarily to understand the extent to which the experience of developing a large-scale coal seam gas (CSG) to liquefied natural gas (LNG) industry in Queensland, Australia was seen to have aligned with the Golden Rules, and how well the Golden Rules were seen to contribute to public acceptance of the industry.

An evaluation tool was developed where the seven Golden Rules and their subclauses were adopted as criteria in a scorecard approach. We conducted interviews with 32 senior people who had been directly involved in the development of the CSG industry in Queensland, from local, state and federal governments, gas companies, host communities as well as researchers and consultant ‘experts’.

The Queensland experience of unconventional gas development rated reasonably well in relation to the Golden Rules, with scores of three or higher out of five for four of the seven rule categories. Across all the Golden Rules, industry performance scored more highly than the effectiveness of the policy/regulatory environment, highlighting the complex and sometimes conflicted roles of governments in developing a new industry. The rules addressing baseline measurement, full disclosure and engagement were seen as most important for public acceptance.

This study developed a new tool to evaluate perceived social and environmental performance of industry and effectiveness of governance in unconventional gas development applicable across different jurisdictional contexts. This application suggests that baseline measurements, open disclosure and public engagement should be the focus for building public acceptance. For new gas developments, these findings highlight the importance of having a robust regulatory environment in place that can coordinate activities and manage cumulative impacts.
Combating Production Loss Due to Paraffin Deposition: A Success Story of Thermochemical Stimulation in Western India
Authors: Qamruzzaman Mohammed , Khan Mandeep , Roy Dhirendra Chandra , Raman Ravi , Arora Sunil
Published: November 2020

Wax deposition during production and transport of paraffinic crude is one of the serious problems faced in downhole and surface operations. Crude oil often contains paraffins which precipitate and adhere to the liner, tubing, sucker rods and surface equipment as the temperature of the producing stream decreases in the normal course of production. Conventional methods of removal of paraffin deposits include chemical dissolution, hot oil/water circulation, mechanical scrapping and pigging. As an alternate to the conventional methods of paraffin removal, wax removal by exothermic chemical reaction also known as thermochemical stimulation is the technique in which the energy liberated from a suitable exothermic reaction is utilized for melting the paraffin deposits and has been shown to be more effective than the conventional treatments in literature.

A major challenge faced while execution of this technique is to control the reaction rate and provide sufficient delay time so that heating can be targeted to the desired depth of paraffin deposits without affecting the integrity of well completion equipment. Towards achieving this goal, this paper describes the key aspects of job design and execution that may significantly enhance the success of exothermic stimulation in wells susceptible to paraffin/organic deposition. The challenges encountered and respective solutions executed are presented through a case study of implementation in 5 onshore wells of western India. The paper also presents a lab validated mathematical model that may be used to predict the behavior of the exothermic formulation and help in optimization and quality control. The job execution procedure including solution preparation, quality testing, pumping, placement and monitoring has been streamlined from field experience to develop a standard operating procedure that may be referred for an effective implementation of this technique.
Effects of Gas Sorption Hysteresis on Gas Production from Organic-Rich Gas Shale Reservoirs
Authors: Ekundayo Jamiu , Rezaee Reza , Fan Chunyan
Published: November 2020

Gas desorption is one of the major gas transport mechanisms in shale gas reservoirs. However, its actual contribution to gas production is often masked by the indiscriminate use of adsorption-derived parameters for desorbed gas volumes during gas production calculations at reservoir conditions. Traditionally, it is believed that gas adsorption is fully reversible at the high-pressure, high-temperature conditions found in shale gas reservoirs.

In this paper, we studied methane adsorption and desorption isotherms using three shale samples at a reservoir temperature of 80oC. The resulting isotherms were modelled using the Langmuir model, following the conversion of measured excess amounts to absolute values. Lastly, a compositional 3D dual-porosity model was developed with CMG-GEM to test the effect of sorption hysteresis on gas production from a shale rock. For each sample, a base scenario, equivalent to a "zero-sorption" case, was compared against two other scenarios representing the two sorption processes.

For each sample, significant hysteresis was observed between the adsorption and desorption isotherms, with the desorption isotherms resulting in lower Langmuir parameters than the corresponding adsorption isotherms. For each process, Langmuir volumes showed a positive correlation with total organic carbon (TOC) contents. Also, the simulation results showed that gas production was lowest for the base case and highest for the adsorption case for each sample. This implies that neglecting the contribution of gas desorption can result in under-prediction of the gas production performances. On the other hand, using adsorption parameters to simulate desorbed gas volume could result in over-estimation of gas production performances.
A New Mixed Wettability Evaluation Method for Organic-Rich Shales
Authors: Tao Liang , Guo Jianchun , Halifu Mirinuer , Zeng Jie , Li Ming , Chen Chi , Zhao Yuhang
Published: November 2020

Rock wettability is the key factor affecting the microscopic distribution of fluids in rock pores and the interaction between fluid and rock. However, the shale from the Longmaxi Formation (LF) in Sichuan Basin is rich in organic minerals, which make the quantitative test of mixed wettability of shale very difficult. In this study, firstly, the micro-pore structure of shale was quantitatively characterized by scanning electron microscope (SEM). Secondly, a new experimental apparatus for shale water spontaneous imbibition under the conditions of formation temperature and confining pressure was designed. Finally, the wettability index was proposed to quantitatively evaluate the water wettability, oil wettability and mixed wettability of shale. The experimental results shown that the organic-rich shale has complex mixed wettability, which was both water-wet and oil-wet. The contact angle of shale samples tested with distilled water were 13.5° and 70.5°, and the contact angles tested with kerosene were 0° and 9.6° at room temperature. The higher temperature the stronger shale hydrophilicity will be, and the water wettability of shale increases with the imbibition time.Therefore, a large amount of fracturing fluid spontaneously permeates into the shale micro-nano pores in the process of hydraulic fracturing, which is an important reason for the low flowback efficiency of shale gas wells. The research results provide effective guidance for the optimization of flowback system.
A Protocol for Developing a Clinical Practice Guideline of Moxibustion in the Treatment of Lumbar Disc Herniation
Authors: Hua Fanghui , Xiong Jun , Zhang Haifeng , Xiang Jie , Huang Shouqiang
Published: November 2020

Background: Lumbar disc herniation(LDH), as a disease with great disturbance to life and work, is known as the origin of the severe and disabling forms of nerve root pain. Recognized as an increasingly widely accepted treatment, the efficacy of moxibustion on LDH has been affirmed. However, clinical practice guidelines (CPG) for the treatment of LDH with moxibustion have not been developed. Therefore, we will carry out this work following the accepted methodological quality standards.Methods: The new CPG will be developed according to the Institute of Medicine (IOM), the Appraisal of Guidelines for Research & EvaluationⅡ (AGREEⅡ) and WHO guideline handbook. And then determine recommendations based on high-level evidence. We will set up a Guideline Working Group and define clinical issues according to the PICO principles (Population, Intervention, Comparison, Outcomes). After evidence syntheses and several rounds of Delphi process, we will reach the consensus. In making the guideline, Patient values or preferences, results of peer review, and interest statements are all within the bounds of what we must consider. Results: As the study is not yet complete, no results can be reported.Conclusion: So far, we will develop the first CPG for moxibustion of LDH strictly based on systematic methodologies in China. This CPG will establish the standard of LDH in moxibustion therapy.Registration number: IPGRP-2020CN034.
Microbiome in Acute Exacerbation and Stable Phase of COPD: A Descriptive and Comparative Study of 16s rRNA Sequencing and Metagenomic Sequencing
Authors: Chang Kang , Zou Xiaohui , Li Zhengtu , Yang Zifeng , Gao Jianpeng , Yang Guoru , Zhang Yong , Li Xue , Zhang Xiaoqi , Liu Yingmei , Cao Bin
Published: November 2020

Background: The role of bacteria in different courses of chronic obstructive pulmonary disease (COPD) has not been very clarified. In this study, sputum samples from patients at different courses of COPD were collected to analyze the differences of the structure and function of respiratory microbiome in different courses of COPD.Results: Our study involved 38 patients with acute exacerbation of COPD (AECOPD). Among them, 42 sputum samples were collected from the acute exacerbation of COPD (Of these 38 patients, 4 patients also collected sputum from the second acute exacerbation phase), and 12 sputum samples were collected from the stable phase of COPD (6 of the above 38 patients). Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria dominated the phylum in all the COPD samples, while Streptococcus, Neisseria, Haemophilus and Prevotella is the top 4 species in the cohort. Salmonella, Salmonella, Pseudomonas and Proteobacteria achieved higher abundance in AECOPD group. Samples from AECOPD patients showed higher α diversity. Moreover, genes annotated to K07481(the function is related to transposase) and K16087(the function is related to hemoglobin/transferrin/lactoferrin receptor protein) in stable subgroup showed higher abundance than that in acute exacerbation subgroup. Compared to samples from stable COPD, Proteobacteria contributed the most antibiotic resistance genes. Conclusions: There are differences in the function and metabolism of respiratory microbiome in patients with different course of COPD. Word count: 218/350
Investigation of Radiation Shielding Efficacy of Vanadium–Tellurite–Antimonite Semiconducting Glasses
Authors: Rammah Yasser , Olarinoye I.O. , El-Agawany F.I. , Mahmoud K A , Akkurt Iskender , Yousef El Sayed
Published: November 2020

Effects of antimony trioxide (Sb2O3) on neutron and gamma-radiation shielding parameters of tellurite vanadio-antimonite glasses with compositions 40TeO2-(60-x)V2O5-xSb2O3: 0 ≤ xSb2O3 ≤ 10 mol% coded as (TVS0-TVS10) were investigated. The mass attenuation coefficients (MAC) were evaluated using the Monte Carlo simulation code (MCNP-5) and WinXcom program for photon energies in the range of 15 keV to 15 MeV. The SRIM program was used to compute the stopping power and projected range of the charged particles, such as proton and alpha particles, on the investigated glass samples. Based on the theoretically evaluated MAC, some shielding parameters were computed, such as linear attenuation coefficient, electric cross-section, atomic cross-section, effective atomic number, half-value thickness (HVT), and the mean free path. The EXABCal program was applied to predict the level of the photons accumulation in the investigated glass samples (buildup factors). The effective cross-section for fast neutrons was computed theoretically based on the fast neutron effective removal cross-section (ΣR ) for the constituting components. Results revealed that the maximum values of MAC exceed in the range between 28.9-31.3 cm2/g with increasing the Sb2O3 substitution ratio between 0-10 mol %, respectively. In contrast, the HVT values decrease with an increase in the increment of Sb2O3 rate. The maximum (ΣR) was obtained for glass coded TVS0 among the investigated glasses. Results concluded that the higher Sb2O3 concentration in TVS glasses leads to an increase in their capability to apply in several radiation shielding applications.
Expression of Wilms’ Tumor Gene 1 and Its Clinical Significance in Children with Acute Lymphocytic Leukemia
Authors: Yin Mengmeng , Liu Aiguo , Zhang Ai , Wang Yaqin , Hu Qun
Published: November 2020

Background: Wilms’ Tumor Gene 1 (WT1) is a potential valuable parameter in prognosis of childhood acute lymphoblastic leukemia (ALL). However, studies on prevalence of WT1 and its correlation to clinical features and prognosis in pediatric patients were not well done. In this study we attempted to identify the correlation between WT1 and childhood ALL.Methods: The expression levels of WT1 in bone marrow cells of 188 children diagnosed with ALL from 2015 to 2018 were detected using real-time quantitative polymerase chain reaction (RQ-PCR). The relationship between expression levels of WT1 and patients’ characteristics, remission status (complete remission/relapse), fusion genes and prognosis of childhood ALL were analyzed and revealed. Results: 1. 147 (78.2%) cases had positive WT1 expression, and the average level was 1.76 (0.3, 6.03) %. 2. The CR and relapse rates of ALL children with positive WT1 were not significantly different from those of WT1 negative group, respectively (87.76% vs 82.93%, P=0.42 and 14.29% vs 17.1%, P=0.658). 3. The WT1 expression level in patients at CR was significantly lower than when at diagnosis (P<0.001) and the expression of WT1 increased obviously after induction therapy in 21 patients who relapsed (P=0.003) .4. The WT1 expression was related to lymphadenectasis (P=0.004) and immunophenotyping (P=0.009), but not to fusion genes (P=0.912). Conclusion: The WT1 in ALL children can be employed as an independent tool to evaluate the prognosis and curative effect of the disease.
Safety of reopening universities and colleges using a combined strategy during coronavirus disease 2019 in China: a cross-sectional study
Authors: Cai Guoqi , Luo Sihui , Zheng Xueying , Yue Tong , Zhou Peng , Jin Tengchuan , Chu Xinmin , Lu Zhaohui , Hu Xiaowen , Shen Zuojun , Xue Tian , Weng Jianping
Published: November 2020

Background There is no consensus as to when and how to reopen schools during the coronavirus disease 2019 (COVID-19) pandemic. This study aimed to evaluate the safety of reopening universities and colleges using a combined strategy in China.Methods This cross-sectional study included 13,116 staffs and postgraduate students who have returned to the four campuses of the University of Science and Technology of China from 17 February (students returned from 12 May) to 2 July 2020. The returning to school was guided by a combined strategy including use of personal protective equipment, management of transportation, serological and nucleic acid tests for COVID-19, quarantine, and restrictions in and out of campus. Epidemiology history and COVID-19 related symptoms (fever, cough, and dyspnoea) were recorded in a subset of participants using an online questionnaire.Results Among 13,116 participants, 4067 tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid and no positive results were identified. Of 9049 participants who chose to conduct antibody tests, 28 (0.3%) tested positive but no one was confirmed by the additional viral nucleic acid tests. Online questionnaires were collected from 5741 participants (mean 25.1 years, 35% female). High-risk exposures and COVID-19 related symptoms were reported in 8.3% and 7.4% of participants, respectively. Comorbidities (hypertension, diabetes, chronic pulmonary disease, and chronic kidney disease) were rare (0.2%-1.5%). Conclusions Using a combined strategy for COVID-19 prevention and control, safely reopening of universities and colleges in low-risk regions is possible and laboratory screening for SARS-CoV-2 infection may not be necessary. Further studies need to cautiously evaluate the safety of reopening schools, if any, in the middle- and high-risk regions.
Preparation of students and residents of human medicine in the first four months of the Covid-19 pandemic. Implications for a second wave.
Authors: Wohlfarth Benny , Gloor Beat , Hautz Wolf
Published: November 2020

Introduction: In the Covid-19 pandemic, medical students and residents find themselves in a healthcare environment with measures and policies changing by the hour. Reports regarding those in training were scarce and scattered in the early pandemic, what made an overarching insight a challenge. This review compiles and analyzes the literature addressing the preparation of students and residents in the first four months of the Covid-19 pandemic to find gaps and implications for the current pandemic as well as for future scenarios.Methods: We performed a systematic literature search and content analysis (CA) for articles available in English language that focus on the preparation of students and residents in human medicine within the first four months of the Covid-19 pandemic.Results: We retrieved 82 articles from a wide range of journals, professional backgrounds and countries. CA identified five recurring subgroup topics of «faculty preparation», «uncertainty and mental health», «clinical knowledge», «rights and obligations» and «(self-) support and supply». Within these subgroups the main concerns of «(re)deployment», «interruption of training and career», «safety issues», «transmission of disease», and «restricted social interaction» were identified as potential stressors that hold a risk for fatigue, loss of morale and burnout.Discussion: Students and residents are willing and able to participate, when provided with appropriate deployment, thorough supervision, Personal Protective Equipment (PPE) and valid knowledge. Faculties and policymakers should be in close contact with the youngest in training to value their concerns and intrinsic creativity on the scenario. The use of new technology for interaction and knowledge provision, interviews for voluntary deployment and the provision of mental health support seem appropriate measures to support students and residents under the current pandemic.Conclusion: Our review holds thorough implications for faculties and policymakers. Not only for surge capacity, but also for the safety and the professional identity formation of those in training, it is crucial to understand their needs and concerns. Leaders should strive for a close communication with students and residents, value their intrinsic creativeness and constantly evaluate on their needs regarding knowledge aspects, safety measures, legal concerns and well-being for the construction of nation-wide homogenous policies.
Dexmedetomidine alleviates inflammation-induced neuropathic pain by suppressing NLRP3 via activation of Nrf2
Authors: Shan Wenyan , Liao Xiaoyun , Tang Yixun , Liu Jitong
Published: November 2020

Objective: To investigate the mechanism of dexmedetomidine (DEX) involving Nrf2-dependent inhibition of NLRP3 in relieving neuropathic pain in chronic constriction injury (CCI) rat models.Methods: The CCI rat models were constructed through sciatic nerve ligation. The CCI rats were treated with DEX, Nrf2 inhibitor (ML385), NLRP3 antagonist (MCC950) and NLRP3 activator (Nigericin). Mechanical withdrawal threshold (MWT) was measured to test the pain sensitivity of CCI rats. H&E staining detected spinal injury of the rats and TUNEL staining was applied to test apoptosis in the spinal cords. ELISA measured the expressions of inflammatory factors. The expressions of Nrf2 and NLRP3 were also detected.Results: Decreased MWT, enhanced spinal cord injury, promoted apoptosis and increased inflammatory factors were detected in CCI rats. The expressions of the above indicators were retraced in DEX-treated CCI rats. Increased MWT, reduced spinal cord injury, inhibited apoptosis and decreased inflammatory factors were detected in rats treated with MCC950 or ML385 while opposite expression patterns were found in rats treated with Nigericin. The expressions of these indicators were retraced in both DEX+ML385 group and MCC950+ML385 group compared to ML385 group and MCC950 group respectively.Conclusion: DEX reduces neuropathic pain of CCI rats by suppressing NLRP3 through activation of Nrf2.
Effects of Grape NAC Transcription Factor DRL1 on Floral Organogenesis in Tobacco
Authors: Li Guirong , Quan Ran , Yan Chaohui , Hou Xiaojin , Hu Huiling
Published: November 2020

Grape (Vitis vinifera) is among the world’s most important fruit crops and is a commonly used woody plant for genomics and post-genomics research. NAC transcription factors play central roles in plant growth and development, floral organ morphogenesis, and responses to biological stress. It is therefore important to identify key transcription factors from grape and clarify their mechanisms of action to generate genetic resources for grape molecular improvement. Our research group previously cloned a NAC transcription factor from V. vinifera ‘Yatomi Rosa’ [drought and leaf roll gene 1 (DRL1)] and demonstrated that it caused dwarfing of tobacco (Nicotiana benthamiana) plants when overexpressed. In the present work, we demonstrate that overexpression of DRL1 in transgenic tobacco delays flowering time and markedly reduces pollen viability. Furthermore, crosses between male DRL1 transgenic tobacco and female wild-type tobacco exhibit substantially lower fruit set, fruit and seed weights, fruit and seed shape indices, and seed germination rates than selfed wild-type plants or crosses with a transgenic female parent. DLR1 overexpression strongly influences flowering time and reproduction in transgenic tobacco, primarily through its effects on pollen development. These results provide a foundation for further functional characterization of DLR1 in grape.
WAYS OF IMPROVING THE RESULTS OF SURGICAL TREATMENT OF GASTRIC MALIGNANT TUMORS, COMPLICATED BY GASTROINTESTINAL BLEEDING IN THE CONDITIONS OF EMERGENCY CARE
Authors: Ivanchov Pavlo , Prudnikova Oksana , Kurbanov Anton
Published: November 2020

The aim is to improve the results of surgical treatment of patients with gastric malignant tumors, complicated by gastrointestinal bleeding, by developing and implementing in clinical practice a new treatment tactic. Materials and methods. The study was conducted on the basis of the Kyiv City Center for Emergency Care of Patients with Gastrointestinal Bleedings and at the Kyiv City Clinical Ambulance Hospital (Ukraine) for the period from 2010 to 2020. A comprehensive examination and analysis of reatment’s results of 140 patients with malignant gastric tumors complicated by acute gastrointestinal bleeding, which amounted to 2.2 % of all reated patients with gastrointestinal bleeding during this period. Results. Radical operations were performed in 97 (69.3 %) patients, palliative and symptomatic – in 43 (30.7 %). Comparing the frequency of complications in the two periods of treatment of patients, a decrease in the second period, compared with the first period, the frequency of complications from 27.2 % to 11.4 % due to a decrease of 1.8 times (from 68.8 % to 37,5 %) complications after emergencies and related fatalities from 36.4 % to 0 and 2.2 times (from 20.8 % to 9.6 %) the incidence of complications after early delayed operations with a decrease in frequency fatalities from 20.9 % to 18.2 %. Conclusions. Operations at the height of acute bleeding in patients with gastric cancer are too dangerous due to the high postoperative mortality. The optimal standard is the use of a set of minimally invasive methods of endosurgical hemostasis to stop active bleeding and prevent its recurrence and operate on patients in the early delayed period. Adherence to such tactics is expedient from the point of view of reduction of risk for a life of the patient and possibility of carrying out radical operations.
FORECASTING THE BURDENED COURSE OF SURGERIES AND EARLY POSTOPERATIVE PERIOD IN PATIENTS WITH PULMONARY TUBERCULOSIS ON THE BASIS OF DENSITOMETRIC ANALYSIS OF PREOPERATIVE COMPUTER TOMOGRAPHY OF CHEST ORGANS
Authors: Kalabukha Ihor , Maietnyi Ievgen
Published: November 2020

Topicality – the success of the use of densitotometry in computed tomography of the lungs to assess the condition of the lungs prompted to determine the possibility of predicting the course of the disease in the surgical treatment of patients with pulmonary tuberculosis. The aim – to determine densitometric criteria for prognosis of burdened intra- and postoperative course in patients operated on for pulmonary tuberculosis. Methods – the analysis of preoperative densitometry indices in CT of the lungs in the upper and lower pulmonary fields on the side of the operation in 40 patients operated on for chemoresistant pulmonary tuberculosis with a burdened intra- and postoperative period and the effect of densitometric abnormalities on intra-operative period. Results – in all examined patients the deviation of values of densitometry from conditional norm was revealed. In most patients with high parenchymal density there was obliteration of the pleural cavity and between the lobular fissures, fibrous changes in the root of the lung, with low density in most cases there was bleeding and insufficient tightness of the parenchymal suture, which together aggravates the early postoperative period. Conclusions – the relationship between deviations in the density of the lung parenchyma before surgery and the possibility of aggravating factors in the process of surgical treatment of patients with pulmonary tuberculosis was discovered; it was determined that predicting the occurrence of certain aggravating factors in the process of surgical treatment of patients with pulmonary tuberculosis can help prevent complications of the operation or significantly reduce their manifestations.
Is Medical Education Inclusive? Exploring LGBT Health Topics in Portuguese Medical Courses
Authors:   Portuguese Medical Students Association (anem/pormsic), Braga, Portugal, Lopes L. , Andrade B. ,   Portuguese Medical Students Association (anem/pormsic), Braga, Portugal, Costa D. ,   Portuguese Medical Students Association (anem/pormsic), Braga, Portugal, Castro G. ,   Portuguese Medical Students Association (anem/pormsic), Braga, Portugal, Dias R. ,   Portuguese Medical Students Association (anem/pormsic), Braga, Portugal, Matos M. I. ,   Portuguese Medical Students Association (anem/pormsic), Braga, Portugal, Valido T. ,   Portuguese Medical Students Association (anem/pormsic), Braga, Portugal, Couto M. ,   Portuguese Medical Students Association (anem/pormsic), Braga, Portugal, Esteves M. ,   Faculty of Medicine, University of Porto, Porto, Portugal
Published: November 2020

Objective: The importance of addressing LGBT health topics is increasingly recognized. This study aimed to explore whether Portuguese medical schools cover LGBT health topics from the perspective of undergraduate medical students. Design and Method: Undergraduate students enrolled in Portuguese medical schools were invited to participate in an anonymous online questionnaire between March and June 2015 about Medical Education in Human Sexuality. Medical students from the ‘clinical’ years also answered a section on LGBT health topics. Descriptive statistics, comparison by Chi-Square statistical analysis and regression analysis were used. Statistical significance was settled at p<0.05. Results: The analysis included 939 completed responses. Despite the diversity of realities found in Portuguese medical schools, more than half of medical students (59,3%) reported that they did not learn to perform inclusive questions when collecting a sexual history from patients. In fact, students that didn’t learn to ask inclusive questions reported more frequently to never use them (79,2% vs. 16,3%, p<0,001) and to always assume that patients are heterosexual (17,1% vs. 4%, p<0,001), when compared to student who have learned. Nevertheless, almost three quarters of students (71,1%) considered the allocation of curricular time on LGBT health topics as “Important” or “Very Important”. Conclusions: Portuguese medical students recognize the importance of LGBT health in their curricula although these topics appear to be insufficiently addressed. Learning about LGBT health can change this scenario and should be more focused by medical schools.