Critical Core Research Articles

The Method to Predict First Critical Core Loading for Nuclear Reactors

Nuclear power plants have an important role in carbon free electricity production in the world. One of the important steps of commissioning a nuclear power plant is the first core loading. This is also called approaching the criticality. Since the number of fuel elements for the criticality is not known, precautions must be taken to prevent safety incidents. Although the procedure is performed on-line such that the neutron counts are measured at each loading of fuel elements to calculate sub-critical multiplication and the number of fuel element to reach criticality were predicted, computer simulations can also be used. In this study, inverse sub-critical multiplication method was applied to Istanbul Technical University TRIGA Mark II research reactor first criticality in 1979 by using Monte Carlo simulation code MCNP6.2. Full 3-D model of the reactor was generated for calculations. Both results, experimental and simulation, showed that reactor became critical with 62 fuel elements. The core excess reactivity of 23.1 cents was predicted as 21.7 with the code. The simulation results are in good agreement with experimental results. The methodology and simulations can be used for power reactor analysis as well.

A Core Outcome Set for Pediatric Critical Care*

More children are surviving critical illness but are at risk of residual or new health conditions. An evidence-informed and stakeholder-recommended core outcome set is lacking for pediatric critical care outcomes. Our objective was to create a multinational, multistakeholder-recommended pediatric critical care core outcome set for inclusion in clinical and research programs. A two-round modified Delphi electronic survey was conducted with 333 invited research, clinical, and family/advocate stakeholders. Stakeholders completing the first round were invited to participate in the second. Outcomes scoring greater than 69% "critical" and less than 15% "not important" advanced to round 2 with write-in outcomes considered. The Steering Committee held a virtual consensus conference to determine the final components. Multinational survey. Stakeholder participants from six continents representing clinicians, researchers, and family/advocates. Overall response rates were 75% and 82% for each round. Participants voted on seven Global Domains and 45 Specific Outcomes in round 1, and six Global Domains and 30 Specific Outcomes in round 2. Using overall (three stakeholder groups combined) results, consensus was defined as outcomes scoring greater than 90% "critical" and less than 15% "not important" and were included in the final PICU core outcome set: four Global Domains (Cognitive, Emotional, Physical, and Overall Health) and four Specific Outcomes (Child Health-Related Quality of Life, Pain, Survival, and Communication). Families (n = 21) suggested additional critically important outcomes that did not meet consensus, which were included in the PICU core outcome set-extended. The PICU core outcome set and PICU core outcome set-extended are multistakeholder-recommended resources for clinical and research programs that seek to improve outcomes for children with critical illness and their families.

ATS Core Curriculum 2020. Adult Critical Care Medicine.

The American Thoracic Society Core Curriculum updates clinicians annually in adult and pediatric pulmonary disease, medical critical care, and sleep medicine, in a 3- to 4-year recurring cycle of topics. These topics will be presented at the 2020 International Conference. Below is the adult critical care medicine core including complications of chemotherapy, acute-on-chronic liver failure, alcohol withdrawal syndrome, mechanical circulatory support, direct oral anticoagulants, upper gastrointestinal hemorrhage, and vasopressor selection.

Continuous-energy Monte Carlo calculation analysis of light-water moderation critical experiments with aqueous solution samples of B, Rh, Cs, Nd, Sm, Eu, Gd, and Er

ABSTRACT In order to validate the neutron absorption cross sections in the JENDL-4.0 nuclear data library, critical analysis was performed using a continuous-energy Monte Carlo calculation code for the light-water moderation UO2 cores loaded with the aqueous solution samples of eight elements (B, Rh, Cs, Nd, Sm, Eu, Gd, and Er). The concentrations of the elements in the solution samples were changed in the experiments, and the criticality water levels were measured. The calculated keff values of the critical cores for the different concentrations of each element were plotted against the reactivity worth of the solution samples calculated based on the differences in the critical water levels. They were fitted by an approximate linear curve to obtain the slope which was regarded as a negative value of a fractional bias of the absorption cross section in the thermal and epi-thermal neutron energy regions. The obtained fractional biases indicated that the absorption cross sections of Sm, Eu, and Gd agreed with the actual values with the uncertainties of about 3%, and those of B, Rh, and Er overestimated them by 6 3%, 5 3%, and 6 4%, respectively.

Building a Successful and Sustainable Academic Career in Gastroenterology.

Starting a new job as an academic gastroenterologist can be very exciting and anxiety provoking at the same time. This is particularly true when the junior faculty member is faced with the unique challenges of practicing medicine in today's world while still attempting to maintain work-life balance and avoid professional burnout. In discussions with several junior colleagues in the specialty over the years, it became clear that there is a relative lack of structured guidance in the literature regarding helping them navigate these turbulent waters in their early careers and setting them up for professional success in the long term. Although there is no guaranteed single formula or recipe for academic success, in this review, we attempt to outline in a stepwise fashion the critical components that we believe are important for junior faculty to consider as they embark on this journey. The significance and value of each step from job selection through promotion and mentorship is discussed in detail based on insights gleaned from experience and the published literature. The importance of citizenship, networking, mission and community-based activities, and work-life balance is highlighted as well. The concept of appreciating and enjoying the "journey," rather than focusing solely on the destination, is emphasized in this paper. We truly believe that these are critical core concepts for junior faculty to grasp that will allow them to derive immense professional gratification in the long run while building successful professional careers along the way.

Experimental study on dynamic mechanism of vortex evolution in a turbulent boundary layer of low Reynolds number

The dynamic mechanism of the vortex generation and evolution process in a fully developed turbulent boundary layer with Reθ =97–194 is experimentally investigated. In this study, a moving single-frame and long-exposure (MSFLE) imaging method and a moving particle image velocimetry/particle tracing velocimetry (M-PIV/PTV) are designed and implemented for measuring the temporal and spatial evolution of vortex cores in both qualitative and quantitative ways, respectively. On the other hand, the Liutex vector, which is a new mathematical definition and identification of the vortex core proposed by Liu’s group, is first applied in the experiment for the structural visualization and quantitative analysis of the local fluid rotation. The results show that an intuitional process of vortex evolution can be clearly observed by tracking the vortex using MSFLE and verify that the roll-up of the shear layer induced by shear instability is the origin of vortex formation in turbulence. Furthermore, a quantitative investigation in terms of the critical vortex core boundary (size) and its accurate rotation strength is carried out based on the Liutex vector field analysis by M-PIV/PTV. According to statistics of the relation between vortex core size and the rotation strength during the whole process, the phy sical mechanism of vortex generation and evolution in a turbulent boundary layer of low Reynolds number can be summarized as a four-dominant-state course consisting of the “synchronous linear segment (SL)-absolute enhancement segment (AE)-absolute diffusion segment (AD)-skewing dissipation segment (SD)”.

Trend in criticality calculation results of borated-water-moderation experimental cores relating to 10B(n, α) cross section

ABSTRACT In connection with the accuracy of the 10B(n, α) cross section in the thermal- and epithermal-neutron energy regions, criticality calculation results were examined for six benchmark sets of light-water-moderation critical experiments of UO2 and MOX fuel lattice cores with un-borated and borated water. Two of the benchmark sets were those implemented in the Tank-Type Critical Assembly (TCA). The others were taken from the International Handbook of Evaluated Criticality Safety Benchmark Experiments (ICSBEP), and the International Handbook of Evaluated Reactor Physics Benchmark Experiments (IRPhEP). The enrichments of the UO2 fuel range from 1.9 wt% to 2.6 wt%, and the Pu contents of the MOX fuel do from 2.0 to 6.6 wt%. The boron concentrations in water are up to 1511 ppm. The effective neutron multiplication factors (keff ) were taken from the published documents. They were calculated with continuous-energy Monte Carlo calculation codes in combination with JENDL-4.0, and other evaluated nuclear data libraries. It was confirmed that the keff values of the critical cores increased with the boron concentrations, which indicates that the 10B(n, α) cross section in the thermal- and epithermal-neutron energy regions should be larger than those in JENDL-4.0 and other libraries.

Discourses of Cultural Continuity among the Bakweri of Mount Cameroon National Park


 
 
 In recent years, the separation of people from their land through protected areas and conservation initiatives of local governance has been at the core of criticism in the people–park discourse. However, vital questions remain as to how people maintain cultural relations to parks and their peripheral zones. This paper explores circumstances where people are not entirely disconnected from their culture despite the state management of Mount Cameroon National Park (MCNP) in West Africa. In this example, people uphold subsistence activities and spiritual interaction with ancestors and deities steered under the umbrella of ritual beliefs. Based on an ethnographic inquiry among the Bakweri in the southwest region of Cameroon, we found that factors of remote settlement, an urge for collective assurances among people, and a sense of belonging in an ethnic group enhance a reciprocal attachment between people and place. This observation helps bridge gaps in people–park relations through cultural continuity.
 
 

Identification of Critical Core Genes of Sarcoma Based on Centrality Analysis of Networks Nodes

Genome-wide association studies (GWAS) are powerful tools for identifying pathogenic genes of complex diseases and revealing genetic structure of diseases. However, due to gene-to-gene interactions, only a part of the hereditary factors can be revealed. The meta-analysis based on GWAS can integrate gene expression data at multiple levels and reveal the complex relationship between genes. Therefore, we used meta-analysis to integrate GWAS data of sarcoma to establish complex networks and discuss their significant genes. Firstly, we established gene interaction networks based on the data of different subtypes of sarcoma to analyze the node centralities of genes. Secondly, we calculated the significant score of each gene according to the Staged Significant Gene Network Algorithm (SSGNA). Then, we obtained the critical gene set HYC of sarcoma by ranking the scores, and then combined Gene Ontology enrichment analysis and protein network analysis to further screen it. Finally, the critical core gene set Hcore containing 47 genes was obtained and validated by GEPIA analysis. Our method has certain generalization performance to the study of complex diseases with prior knowledge and it is a useful supplement to genome-wide association studies.

Polypropylene/Chemical Blowing Agent Foams: Effect of the Injection Speed and Core Back Distance on Microstructure and Mechanical Properties

In recent years, many parts of the automotive industry, previously made of metal, has been passed to polymers due to their light weight, ie lower carbon emission and fuel consumption advantage. The aim of this work was to investigate the microstructure and mechanical properties of chemical foaming agent added polypropylene foam samples produced by injection molding. In particular, the effects of injection speed and core back distance on the evolution of cell diameter, compact outer layer thickness, cell density and mechanical properties were examined. In the first step the effect of various injection speeds (110; 125; 140 mm/s) was investigated. Then, various core back positions (0; 0.7 and 1.5 mm) were analyzed at a constant injection speed (110 mm/s). The results showed an increase of the cell diameter, the compact outer layer thickness and the elastic modulus as the injection speed increases. In addition, an important effect of the core back distance was observed with the presence of a critical core back distance. Below this critical value, the cell diameter and the elastic modulus drop due to a notable decrease of the skin layer thickness. Above this critical value, the cells started to collapse and lose their circularity.

Experiencing Positive Health, as a Family, While Living With a Rare Complex Disease: Bringing Participatory Medicine Through Collaborative Decision Making Into the Real World.

Physician–patient collaboration was recognized as a critical core of participatory medicine more than a century ago. However, the subsequent focus on scientific research to enable cures and increased dominance of physicians in health care subordinated patients to a passive role. This paternalistic model weakened in the past 50 years—as women, minorities, and the disabled achieved greater rights, and as incurable chronic diseases and unrelieved pain disorders became more prevalent—promoting a more equitable role for physicians and patients. By 2000, a shared decision-making model became the pinnacle for clinical decisions, despite a dearth of data on health outcomes, or the model’s reliance on single patient or solo practitioner studies, or evidence that no single model could fit all clinical situations. We report about a young woman with intractable epilepsy due to a congenital brain malformation whose family and medical specialists used a collaborative decision-making approach. This model positioned the health professionals as supporters of the proactive family, and enabled them all to explore and co-create knowledge beyond the clinical realm. Together, they involved other members of the community in the decisions, while harnessing diverse relationships to allow all family members to achieve positive levels of health, despite the resistance of the seizures to medical treatment and the incurable nature of the underlying disease.

Zika Virus NS3 Protease Pharmacophore Anchor Model and Drug Discovery

Zika virus (ZIKV) of the flaviviridae family, is the cause of emerging infections characterized by fever, Guillain-Barré syndrome (GBS) in adults and microcephaly in newborns. There exists an urgent unmet clinical need for anti-ZIKV drugs for the treatment of infected individuals. In the current work, we aimed at the promising virus drug target, ZIKV NS3 protease and constructed a Pharmacophore Anchor (PA) model for the active site. The PA model reveals a total of 12 anchors (E, H, V) mapped across the active site subpockets. We further identified five of these anchors to be critical core anchors (CEH1, CH3, CH7, CV1, CV3) conserved across flaviviral proteases. The ZIKV protease PA model was then applied in anchor-enhanced virtual screening yielding 14 potential antiviral candidates, which were tested by in vitro assays. We discovered FDA drugs Asunaprevir and Simeprevir to have potent anti-ZIKV activities with EC50 values 4.7 µM and 0.4 µM, inhibiting the viral protease with IC50 values 6.0 µM and 2.6 µM respectively. Additionally, the PA model anchors aided in the exploration of inhibitor binding mechanisms. In conclusion, our PA model serves as a promising guide map for ZIKV protease targeted drug discovery and the identified ‘previr’ FDA drugs are promising for anti-ZIKV treatments.

Modeling of Gas Entrainment Flow Rate by Bathtub Vortex

In the design study on sodium-cooled fast reactors, .it is important to investigate the gas entrainment (GE) phenomena in detail. In fact, a lot of analytical, experimental and numerical studies have been conducted to clarify the onset condition of GE and some GE onset models have been proposed. However, few studies on the modeling of entrained gas flow rate has been conducted due to the difficulty on modeling the gas bubble entrainment at a free surface, which is accompanied by complicated free surface deformation. In this paper, the authors propose a mechanistic model to predict the entrained gas flow rate by a free surface vortex. The model contains the theoretical equation of transient gas core elongation and the empirical equation of critical gas core length for gas bubble detachment. The mechanistic model is applied to predict the entrained gas flow rate in a simple GE experiment. As a result, the predicted results show qualitatively good agreement with the experimental results of the entrained gas flow rate. Therefore, it is confirmed that the proposed mechanistic model can predict the entrained gas flow rate by a free surface vortex.

Development and Analysis of TREAT Neutronics Benchmarks

The Transient Reactor Test Facility (TREAT) was designed in the late 1950s to test nuclear fuels and materials under extreme conditions and has been recently restarted by the U.S. Department of Energy to provide the transient test capability to evaluate the performance of innovative nuclear fuels under accident conditions. Benchmark experiment data are required to support the operation of TREAT and to validate the computational analyses necessary to design and evaluate the experiments. Therefore, in this paper, benchmark problems based on the minimum critical (MC) core and M8 Power Calibration Experiment (M8CAL) core of TREAT were developed and analyzed using the Monte Carlo code Serpent. The eigenvalue, temperature coefficient, and flux distributions for both the MC core and the M8CAL cores were calculated and compared to the experimental data. All the calculated values compared well to the experimental data, and both problems were subsequently approved as International Reactor Physics Experiment Evaluation Project benchmarks.

How planets grow by pebble accretion

Context. Proto-planets embedded in their natal disks acquire hot envelopes as they grow and accrete solids. This ensures that the material they accrete – pebbles, as well as (small) planetesimals – will vaporize to enrich their atmospheres. Enrichment modifies an envelope’s structure and significantly alters its further evolution. Aims. Our aim is to describe the formation of planets with polluted envelopes from the moment that impactors begin to sublimate to beyond the disk’s eventual dissipation. Methods. We constructed an analytical interior structure model, characterized by a hot and uniformly mixed high-Z vapor layer surrounding the core, located below the usual unpolluted radiative-convective regions. Our model assumes an ideal equation of state and focuses on identifying trends rather than precise calculations. The expressions we derived are applicable to all single-species pollutants, but we used SiO2 to visualize our results. Results. The evolution of planets with uniformly mixed polluted envelopes follows four potential phases. Initially, the central core grows directly through impacts and rainout until the envelope becomes hot enough to vaporize and absorb all incoming solids. We find that a planet reaches runaway accretion when the sum of its core and vapor mass exceeds a value that we refer to as the critical metal mass – a criterion that supersedes the traditional critical core mass. The critical metal mass scales positively with both the pollutant’s evaporation temperature and with the planet’s core mass. Hence, planets at shorter orbital separations require the accretion of more solids to reach runaway as they accrete less volatile materials. If the solids accretion rate dries up, we identify the decline of the mean molecular weight – dilution – as a mechanism to limit gas accretion during a polluted planet’s embedded cooling phase. When the disk ultimately dissipates, the envelope’s inner temperature declines and its vapor eventually rains out, augmenting the mass of the core. The energy release that accompanies this does not result in significant mass-loss, as it only occurs after the planet has substantially contracted.

Electrochemical Mechanism of Trivalent Chromium Reduction in ChCl-EG Deep Eutectic Solvents Containing Trivalent Chromium

In this work, the cyclic voltammetry (CV) was used to investigate the redox process of Cr(III) on glassy carbon electrode (GC) in deep eutectic solvents (DESs), prepared using choline chloride (ChCl) and ethylene glycol (EG). The anode and cathode branches of the CV curve meant the process of deposition/dissolution equilibrium of trivalent chromium. The equilibrium potential (Eeq) of Cr(III)/Cr(0) was −0.964 V (vs Ag QRE). The analysis of the potentiostatic current density transient (chronoamperometry (CA)) results showed that the electrodeposition process of Cr(III) involved multiple processes, mainly jad, j3D and jWR. By calculating the amount of charge (Qad%, Q3D%, and QWR%) in each process, it can be found that the contribution rate could be controlled by the potential to increase Q3D%. The kinetic parameters of Cr nucleation/growth rate were determined from the standard model of 3D nucleation of diffusion-control, such as nucleation rate (A), active centre number density (N0), and diffusion coefficient (D). The ln(A) and η were used to calculate the nucleated Gibbs free energy (Δ∼G(nc)), the critical core size (nc), the current exchange density (j0), the transfer coefficient (α), and the surface tension (σ). The chromium coating was constituted by particles of Cr(0), Cr2O3 and Cr(OH)3.

Proteasome inhibition creates a chromatin landscape favorable to RNA Pol II processivity

Proteasome inhibition creates a chromatin landscape favorable to RNA Pol II processivity

RPEEE (Reasonable Prospects for Eventual Economic Extraction): The critical core to the SAMREC Code

SYNOPSIS Reasonable Prospects for Eventual Economic Extraction (RPEEE) is the critical basis for effective implementation of the SAMREC Code as it applies to Mineral Resources, and implicitly to Mineral Reserves that are derived from Mineral Resources. This implementation follows the founding principles of materiality, transparency, and competence. The SAMREC definition of a Mineral Resource specifically includes RPEEE. SAMREC provides guidance for all minerals on what RPEEE means, with some specific additional guidance for diamonds. SAMREC instructs the Competent Person that RPEEE must be demonstrated through reasoned assessment of multiple technical and non-technical parameters, and with disclosure in reporting. A recommended chapter in a CPR includes a sub-section for RPEEE. SAMREC definitions and guidance are presented with discussion of the factors that must be assessed to demonstrate RPEEE. Comparison with guidance in other reporting countries and examples of actual practice are presented. Keywords: reporting codes, Mineral Resources, definitions, disclosure, SAMREC.

Preliminary Discussion on the High Performance Adaptive Analysis for Numerical Computational Method

Numerical computation is one of the reliable ways to solve partial differential equations. In the past three decades, with the rapid growth of computer processing power and storage space, numerical computation has been successfully applied to many fields. It provides strong support for researchers to solve complex engineering practical problems and analyze complex physical phenomena. Most of the existing numerical methods are element-based, among which the finite element method is the most famous. Modern numerical analysis technology is developing towards high efficiency, high accuracy, low cost and high performance, while the traditional analysis technology has been unable to meet the requirements. The first step in industrial manufacturing is engineering design, and the most basic tool of engineering design is calculation and analysis software, and calculation method is the most critical core problem in calculation and analysis software. At present, the software industry of our country is almost completely monopolized by foreign software products. The serious lack of domestic computing simulation software with completely independent intellectual property rights will surely become the biggest weakness in the implementation of the intelligent manufacturing 2025 in China. The research and development of advanced core adaptive computing methods and analysis technology with completely independent intellectual property rights play an important role in improving the development level of engineering analysis software in China and cultivating the ability of independent research and development.

Analysis of Education Needs on Nursing Core Competencies of Nursing College Students Using Importance-Performance Analysis: A Case of College A

본 연구는 간호대학생의 간호사 핵심역량 요인과 항목들의 중요도와 실행도의 차이를 분석하고, IPA를 통해 간호사 핵심역량의 중요도와 실행도를 동시에 분석함으로써 대학 교육과정 및 임상실습현장의 시사점을 제시하고자 하였다. 서울 소재 간호대학에 재학 중인 4학년 간호대학생 178명을 대상으로 간호사 핵심역량에 대한 중요도와 실행도를 측정하였으며, 주요 연구결과는 다음과 같다. 첫째, 간호사 핵심역량 8개 요인별 중요도와 실행도 차이분석결과 모든 요인에서 중요도와 실행도 간에 통계적으로 유의한 차이를 보였다. 둘째, 간호사 핵심역량 30개 항목별 중요도와 실행도 차이분석결과 모든 항목에서 중요도와 실행도 간에 통계적으로 유의한 차이를 보였다. 셋째, 간호사 핵심역량 IPA분석 결과 1사분면(지속유지 필요 영역)에는 ‘간호전문직관’, ‘비판적 사고를 통한 통합적 간호’, ‘의사소통능력’, ‘리더십’, ‘스트레스 관리’ 요인과 이와 연관된 13개 항목이 포함되었다. 2사분면(과잉노력 지양 영역)에는 ‘비판적 사고를 통한 통합적 간호’, ‘생명존중’, ‘간호연구’ 요인과 이와 연관된 3개 항목이 포함되었다. 3사분면(우선순위 낮음 영역)에는 ‘비판적 사고를 통한 통합적 간호’, ‘생명존중’, ‘간호연구’ 요인과 이와 연관된 6개 항목이 포함되었다. 마지막으로 4사분면(개선노력 필요 영역)에는 ‘비판적 사고를 통한 통합적 간호’, ‘리더십’, ‘스트레스 관리’, ‘핵심간호술’ 요인과 이와 관련된 8개 항목이 포함되었다. 본 연구결과는 향후 간호대학생의 간호사 핵심역량 함양을 위해 교육시스템 구축 및 교육과정 재구성을 위한 기초 자료로 활용될 수 있을 것이다.The purpose of this study is to suggest methods for improving nursing core competencies of nursing college students by investigating the difference between nursing college students’s perception of importance and performance of nursing core competencies in order to understand educational needs. The nursing core competencies questionnaires survey, which was conducted for A women’s college of nursing’s students. The 178 questionnaires collected were analyzed using Importance-Performance Analysis(IPA). The results was analyzed that the means of importance of all sub-factors of nursing core competencies were higher than the means of performance, and the difference was statistically significant except for the stress management. Also it was analyzed that factors that should by urgently improved due to low performance and high degree of importance are the integrative nursing through critical thinking, leadership, stress management and core nursing. It is necessary to develop a nursing core competencies support system focusing on the sub-factors with high educational needs of the nursing college students.