bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevention and Countermeasures of Urea Crystallization in SCR Urea Pyrolysis System
Authors: Su JingCheng , Xue FangMing , Li PeiPei , Zhang Yulong
Published: January 2021

The reasons for urea crystallization in the SCR urea pyrolysis system are analyzed, and system design, flow field control, equipment selection, process water and compressed air quality requirements and other aspects are optimized and selected, in order to improve the urea crystallization of pyrolysis furnace Phenomenon to effectively prevent and provide targeted countermeasures. In the process of pyrolysis of urea to produce ammonia, a slight deviation will easily form crystals. In severe cases, pipeline blockage and insufficient ammonia supply in the system will occur. However, based on the feedback of multiple application projects in the past ten years, there has not been a situation that has affected the operation of the pyrolysis system due to serious urea crystallization, and as long as the system design, flow field control, equipment selection, process water and compression Optimization and selection of air quality requirements and other aspects can effectively prevent and control the phenomenon of urea crystallization. The urea pyrolysis ammonia production system is a safe and effective source of ammonia, which can ensure the long-term safe and stable operation of the SCR system, so it will be more and more widely used.
Research on Urban Eco-clean Watershed in Northwest China
Authors: Shen Yongkang , Zhang Di
Published: January 2021

Ecological clean urban watersheds play some important roles for environment protection in Northwest China, however urban eco-clean watersheds were rarely focused on living water environment. Some technology projects and integrated management measures for water sources, urban flood disaster and living water environment are concluded by some studies on problem-oriented. Based on high quality urban development in the Huanghe river basin, some advice on cooperation development and technological measures on sponge city were suggested for cities and towns in Northwest China.
Study on the Application of PCA Data Analysis Method in Frontal Rainstorm Forecast
Authors: Wang Pin , Xiao Zongna
Published: January 2021

According to the principle of weather dynamics, there are three principal components affecting rainstorm, namely ascending motion, unstable condition and water vapor condition. According to these three types, the forecast factor group of rainstorm is formed. The original multi-index is transformed into a few independent comprehensive indexes by principal component analysis (PCA). After standardization of various factor indexes, the comprehensive index of rainstorm forecast is obtained based on PCA. After all kinds of factors are standardized, the comprehensive index of rainstorm forecast is obtained based on PCA. The test results show that there is a good correspondence between the rainstorm and the forecast comprehensive index, and the trend basically corresponds to the peak and valley values. The forecast of the comprehensive index rainstorm has certain indication significance. Through the comparison between each classification index and independent samples, the threshold system of rainstorm forecast is established combined with comprehensive index and circulation classification, which has reference value for the presence or absence of rainstorm process forecast and is a beneficial discussion on the quantification of weather conceptual model forecasting method.
Design of water quality monitoring platform based on Embedded System
Authors: He Yuxiao
Published: January 2021

This paper designs and develops an embedded aquaculture intelligent water quality monitoring system based on STM32F103VET6, serial communication module and RS485 interface circuit. The system uses sensors to collect the temperature, pH value, dissolved oxygen, turbidity and other information of aquaculture water quality in real time. Through the water quality monitoring platform established in this paper, the water quality index method is used to evaluate the water quality, so that the farmers can obtain the abnormal alarm information and water quality comprehensive situation in time, and get the water quality improvement suggestions.
Study on the Construction of a New Third-Party Governance Model for Environmental Pollution
Authors: Mo Jianjian
Published: January 2021

In recent years, China’s environmental pollution control focuses on public participation. As an important measure of pollution control, the marketization and specialization of pollution control is a historical trend. Some scientific research institutes and environmental protection enterprises have begun to practice the third- party governance system. Looking at the practical effect, there are many deficiencies in the current third-party governance model, mainly for the lack of promotion power of the third-party governance model, the imperfect third-party governance supervision system, and the inability to distinguish the scope of responsibility between the main body of pollutant discharge and the main body of pollution control. In this paper, from the perspective of “operation mechanism, legal relationship and central subject”, the paper creatively constructs the “three-in-one” third-party governance mode to effectively solve the problem of responsibility definition between the pollutant discharge, pollution treatment subject and the government.
Study on Stress Distribution Law and Stress Performance Characteristics of Multiple Data Mining for Harbour Portal Crane Detection
Authors: Wen Haobai , Li Yiqin
Published: January 2021

Taking the actual test of harbour portal crane as the sample, the evident high-stress measure points have been selected through the potential high-stress measure points, and the high-risk structure have been identified. Then stress distribution law and stress performance characteristics of the high-risk structure have been studied. The basis for the safety production of the port have been provided.
Analysis of the influence of heat source well parameters on pumping temperature of groundwater source heat pump
Authors: Min Wu
Published: January 2021

In this paper, MATLAB software is used to simulate the influence of parameters of different heat source wells on pumping temperature in groundwater source heat pump system. The absolute value of horizontal permeability coefficient of aquifer will not affect its pumping temperature, but when the permeability coefficient ratio increases from 1 to 10, the pumping temperature decreases by 1.1°C; When the specific heat capacity increases from 2000 kJ / m3 · °C to 3000 kJ / m3 · °C, the pumping temperature decreases by 0.8 °C; When the degree of thermal dispersion increases from 1m to 3m, the pumping temperature decreases by 0.4°C.
Correlative Study of Accra Water Supply Project
Authors: Li Junfeng , Zhai Zhongwen
Published: January 2021

Accra Water Supply Project adopted TOPSIS method which is based on Multiple-attribute Decision Making Theory to establish decision making model. After sorting based on distance measure, the best scheme was recommended, which met the requirements of comprehensive comparison proposed by the proprietor.
Utilization of Vanadium Extraction from Vanadium-bearing Steel Slag
Authors: Ding Mantang
Published: January 2021

Vanadium extraction from vanadium-containing steel slag mainly includes fire method and wet method. The advantages and disadvantages of various ways of vanadium extraction from vanadium-containing steel slag are discussed and analyzed. The prospects and suggestions for future development were put forward to. It is proposed that the submerged arc furnace carbothermal reduction method, the sub- molten salt method, the production of vanadium alloys, calcification roasting-acid leaching, and two-part acidification to extract vanadium are the future development directions.
The effect of interfacial tension of ASP system on the initial migration of film-like microscopic residual oil
Authors: Cao Ruibo
Published: January 2021

Use glass etching microscopic visualization model to carry out oil displacement experiment to detect the interfacial tension and viscoelasticity of the ASP system with different surfactant concentrations. By recording dynamic images during the displacement process, the effect of interfacial tension on the initiation of the film-like residual oil migration was studied. The results show that under the condition of the same concentration of polymer and surfactant, the higher the concentration of surfactant, the lower the interfacial tension of the ASP system, and the lower the storage modulus and energy consumption modulus; when the interfacial tension is 0.188mN/m, the film-like residual oil is slightly deformed at the enriched part of the displacement front; when the interfacial tension is 0.0188mN/m, the oil displacement system reduces the contact area between the oil film and the wall by changing the wettability of the residual oil in the film-like shape, and the overall migration; when the interfacial tension is 0.00188mN/m, the oil displacement system breaks out oil droplets and starts to migrate the residual oil in a thin film.
A brief review of the development of high temperature gas cooled reactor
Authors: Li Huan
Published: January 2021

With the continuous development of nuclear energy, the high temperature gas cooled reactor (HTGR) is considered as one of the advanced reactor types of the fourth generation nuclear power system because of its new inherent safety concept, modular concept, high economic competitiveness and increasing construction flexibility. In this paper, the development history of high temperature HTGR is briefly summarized and the latest research is summarized.
Facile synthesis of hierarchically porous carbon for supercapacitor derived from water-soluble pitch
Authors: Zhang Jinliang , Liu Junqing , Kang Danmiao , Su Zhijiang , Liang Wenbin , Zhi Linjie
Published: January 2021

Hierarchical porosity carbons have been synthesized via carbonization and activation using water-soluble pitch as carbon source. By further introducing potassium acetate as an activation agent, the obtained materials have a high specific BET surface area of 1108 m2 g-1 with N, O and S doping. The effects of different activation temperatures on the pore structure and composition of the carbon were investigated. The obtained carbon samples exhibits a maximum gravimetric capacitance of 208 F g-1 when evaluated as an electrode material in 6 mol L-1 KOH aqueous solution and good rate capability of 69.5% retention at 20 A g-1. Furthermore, it demonstrates good cyclic stability, showing a high capacitance retention of 96.3% over 10000 charge-discharge cycles at a current density of 2 A g-1.
Beijing-Tianjin-Hebei Energy Demand Combination Forecast Analysis
Authors: Li Jian , Zhang Xiaoqian
Published: January 2021

Energy demand forecasting is the basis for responding to high-quality economic development requirements and targeted adjustments to the Beijing-Tianjin- Hebei energy structure. This paper selects five main factors that affect energy demand, constructs a combined forecasting model of a combination of multi-factor gray neural network and ARIMA-BP neural network, and introduces the idea of chaos optimization on this basis to simulate and analyse data from 2012 to 2016, and predict the energy demand in the Beijing-Tianjin-Hebei region in 2020 and 2025.The results show that: 1. Compared with the CGA-ARIMA-BP model and the CGA-GNN model, the CGA-GNN-ARIMA-BP model has higher prediction accuracy; 2. It is estimated that in 2020 and 2025, the energy demand in the Beijing-Tianjin-Hebei region will reach 493 and 552 million tons of standard coal.
Identification on standard connection modes of distribution network based on topological features and pattern recognition
Authors: Wu Tianchen , Lv Bing
Published: January 2021

The distribution network has multiple points, long lines, wide coverage, complex structure, and intersecting management links. In order to improve the quality of the analysis and evaluation of the standard grid structure of the distribution network, this approach uses the 10kV medium voltage distribution network as the object to identify the standard connection Research. First, abstract the wiring diagram of the distribution network, extract the characteristics of standard connection types, establish a eigenvector expression model and standard connection type feature library. Second, use breadth-first search to form the network topology structure, and check data to detect the transfer capacity of closed loops, islands, and contact switches. Then use the principle of statistics to calculate the content of the eigenvector expression. Finally, use the pattern recognition method to match the eigenvector expression of the connection group to be identified with the standard wiring type feature library. Based on the statistical standard connection characteristics, this approach adopts the method of pattern recognition to judge the standard grid, which has a good recognition effect and accuracy on the actual distribution network wiring, and is of great significance to the later power grid transformation.
Research on Rolling Optimal Scheduling Model of Integrated Energy System for Park Energy Internet
Authors: Yin Shuo , Bai Hongkun , Yang Meng , Chai Zhe , Yan Jing , Zhang Peng , Bao Peng , Zhang Han
Published: January 2021

As the physical carrier of the energy internet, the reasonable scheduling of the integrated energy system has become the focus of current research. In this paper, based on the demand for energy internet construction, renewable energy and demand- side load fluctuations are considered, and the price-type and substitution-type demand side response characteristics are utilized to establish day-ahead and intra-day optimization scheduling model, which takes into account the demand side response. According to the difference of electricity, cold/heat and gas dispatching time, a three- layer rolling optimal dispatching model is proposed. The case study shows that the multi-time scale optimal scheduling model with demand-side response can restrain the fluctuation of intraday renewable energy and load, improve the stability of the system, and further reduce the operating cost of the system.
Study on Dynamic Response of a New Type Ultra High Voltage AC-DC Hybrid Power Grid
Authors: Zhu Haoqing , Shi Linjun , Xing Chunchen
Published: January 2021

The new high-capacity condenser can better meet the dynamic reactive power demand brought by the large-scale development of UHVDC System, and its electrical parameters are bound to be different from the traditional condenser. In this paper, the influence of electrical parameters on the transient process and sub transient process of the condenser is analyzed, and the key parameters of the dynamic optimization of the new high-capacity condenser are extracted. Then, based on epri-36 bus system and PSASP simulation platform, the DC sending and receiving system with the new high-capacity condenser is simulated and analyzed. The simulation results show that the condenser is in UHV AC / DC system. The hybrid system plays a positive role in fault response.
Multi - objective distribution network reconstruction based on decimal coding
Authors: Wu Tianchen
Published: January 2021

The distribution network reconfiguration problem is a highly complex mixed integer, nonlinear, multi-objective planning problem. According to the closed-loop design and open-loop operation of the distribution network, this paper proposes a loop- based decimal coding method to reduce the space of infeasible solutions. At the same time, combined with breadth-first search to form and test feasible solutions. The text takes the network loss and voltage deviation as the target, uses the NSGA-II algorithm for multi-objective optimization, and uses the Newton Raphson method to check and evaluate the reconstruction scheme. Finally, an IEEE-33 node test case is used to verify the algorithm. The results show that the algorithm can quickly calculate an approximate global optimal network reconstruction scheme.
Design and Fabrication of a Scaled Down Self Load Pneumatic Modern Trailer
Authors: Praveena B A , Shetty Balachandra P , Arvind R , Gagan Deep J G , Kumar Gaurav Satish , Pavan Kalyan K , Vasu Vikram Kedambadi , Lokesh N
Published: January 2021

This research work has mainly concentrated on the difficulty of the movement of 3 axes on a modern trailer and hence a suitable arrangement has been designed such that the materials can be unloaded from the trailer in three axes without application of any impact force. Our survey is in the regard of several automobile industries that revealed some facts which are most likely difficult methods that were adopted in weighing load especially in difficulties of unloading the materials from the trailer. It is difficult to unload the materials in small, compact streets and roads; therefore, in our project these issues are rectified to unload the trailer in all three sides with ease. The control valve of the trailer is activated manually and hence the compressed air passes to the pneumatic cylinder through the valve. The ram of the pneumatic cylinder acts as a lifting arm of the trailer cabin. This project also focuses on application of self-load weighing such that the material loading and unloading weight display is viewed to cross check while unloading. The automobile engine drive is coupled to the compressor engine, so that it stores the compressed air when the vehicle is running. This compressed air is used to activate the pneumatic cylinder when the valve is activated. Also, rotation of the trailer is done with the help of gear drive system operated by the motor. The whole mechanism is controlled by the operator or driver which is near the driving seat that helps them to operate safely and easily.
Investigation of effect of mechanical properties and Influence of Heat treatment on AISI 4140 steel
Authors: Nagaraja T. K.
Published: January 2021

The optimization methods in metal heating processes, considered to be a vital tool for continual improvement of output quality in products. In order to optimize the gains from the raw material of AISI 4140 alloy steel, an accurate process must be constructed. The carbon content in AISI4140 steel ranges from 0.38 to 0.43%. In this approach the mechanical properties mainly like Hardness, Yield Strength, Wear Resistance are amenable to modification via heat treatment. In the present work the objective is to test the chosen steel with various heat treatment processes and also analyze their microstructure. A comparative study made across the properties vs. heat treat processes. Finally, to choose the best heat treatment process and optimal properties that can be achieved.
Solid State Diffusion Bonding Process-A Review
Authors: Aravinda T , Niranjan H B , Satish Babu B , Udaya Ravi M
Published: January 2021

The present paper reports on the various diffusion bonding techniques using atomic diffusion of elements at the interface. The bonding process is used mainly for joining dissimilar metals. However, two similar metals can also be bonded with or without using an interlayer. Dissimilar materials include metalceramic; interlayer can also be used if necessary, in between the interfaces. The other methods of joining would probably interfere with the microstructure of the base metal at the point of interface. Various methods of joining like welding create reaction between the materials in the molten pool. Residual stresses would not appear at the bonding site, neither has it created thermal gradients using diffusion technique. Distortion observed in diffusion bonding is quite less compared to other joining process. It is also observed that the interface retains similar mechanical and physical properties as that of the base material. The strength at the interface depends on parameters like temperature, pressure and time taken for contact while forming the solid state bond.
Assessment and Modelling of Cutting Forces in Turning of Aluminium Metal Matrix Composite Using Response Surface Methodology
Authors: Vivek Bhandarkar V N , Pal Bhaskar , Shanmuganathan S.P.
Published: January 2021

The conventional materials are nowadays replaced by Metal matrix composites owing to their excellent Mechanical and machining phenomena. The growing/up-trending growth in Automobile and aerospace sector paves / necessitates the need for accuracy / closer tolerance in machining parameters. The constraints while machining MMC’s are surface roughness and cutting force parameters. The present study focuses on the cutting parameters, condition influencing the surface roughness in terms of material composition, tool wear, speed feed, during the machining of LM6/SiC composites. The mathematical model has been established using Taguchi technique (L16 orthogonal array). By using the RSM approach empirical relation for various machining attributes has been generated to assess the output parameters namely, Feed force (Ff), Cutting force (Fc), Radial force (Fd) and surface roughness (Ra). Desirability function approach is used to find the optimal machining condition. The influence of various parameters in machining of LM6/SiC composite have been analyzed in detail. The study showed that the optimized outputs for the machining of LM6/SiC composite for the input parameters 0% Reinforcement, new tool flank wear(0mm), speed in the range of 684 rpm and 0.1mm feed rate respectively are 7.827 N, 11.196N, 7.890 N and 10.786μm.
Vertical Axis Wind Turbine Performance Enhancement Via Utilizing the Repulsive Characteristics of Permanent Magnets
Authors: Hegde Sandesh , Ramachandra C G
Published: January 2021

Humans have been using wind power for past thousands of years to propel sailboats and ships. But from calendar year 1980s, in the energy sector we can see dramatic development in the form of wind energy. Today in renewable power, other than the hydropower, together with solar power, the wind is also most important source energy. Here the wind energy conversion system; consist of turbine which transforms the kinetic energy available in the wind into the mechanical energy, then the mechanical energy is boosted up with the help of gearbox and then generators are used to transform the rotational mechanical energy into the electrical energy. Now this paper mainly concentrates on the implementation of “magnetic propelling phenomenon” to improve the efficiency of the VAWT system and technology will be implemented between the rotating plane and fixed plane below the turbine, in such way that like polarities facing each other to create magnetic repulsion. The natural property of magnetic repulsion which is created between like poles of magnets can be used as a source of energy. Thus this system will operate with an additional feature like, magnetic repulsion characteristics. The force which is created as the result of the magnetic repulsion will also adds kinetic energy to the turbine while converting the wind kinetic energy into the rotational mechanical energy by the turbines, Hence here our PMP-VAWT system has the ability to operate in the both high & low wind speed environment condition with better efficiency due to the implementation of magnetic repulsive characteristics, and here our choice is to demonstrate the efficiency of PMP-VAWT system as compared to the Traditional VAWT system.
A Review on Adsorption Chilling Systems And Viable Future Focus In Refrigeration
Authors: Aalderik Jude J , Dandotiya Devendra , Pal Bhaskar
Published: January 2021

The adsorption refrigeration system has gained significant insight in recent years as it has paved an important way of utilizing low-grade thermal energy and eco-friendly refrigerant efficiently. However, it is yet to be commercially viable due to its low Coefficient of Performance (COP) and specific cooling power (SCP) in comparison to the traditional chilling technologies. This paper reviews various validation in incorporating different strategies to maximize the performance and cooling power of the system, out of which, prominent stages include-waste heat recovery, mass recovery, multi-bed, multi-stage, and revamp functionality.

This study acknowledges different parameters and allied substitution, for instance, low evaporative temperature, low generative temperature functioning can be controlled by infusing the mass recovery technique. Furthermore, other variables like appropriate cycle time and switching time are discussed to attain optimum performance of the system as it Is regarded that the adsorption chiller greatly relies on the functionality of the system. Besides, to the above-stated variables, an adsorbent material is employed and this assures a considerably desirable performance.

This study further extended in briefing the economic criterion, increasing the power to mass ratio, and also improving the knowledge regarding the potential performance of the system in the long run when the energy-driven is either solar or waste heat energy source.
State of the Art of Phase Change Material (PCM) for the Purpose of Heat Storage and Transfer in Cylindrical and Rectangular/Square Shells/Tubes – A Review
Authors: Prashanth S P , Dandotiya Devendra , Surendra Kumar A M
Published: January 2021

The state of the art of the PCM’s reveals enabled characteristics that opens the door for multiple heat transfer and storage phenomena. The PCM absorbs, stores, and releases the energy during its phase change thus it most widely helps in latent heat transfer techniques. Nowadays Nano-fluid and Nano-phase change materials are replacing the general phase change materials because of its high heat transfer and storage capability. Further, varieties of passive heat transfer techniques such as heat exchangers of shell/tube type of various patterns and geometries are utilized to optimize the thermal energy. The artificial neural network is embedded in the system to recognize the pattern for faster processing. In this article, the PCM heat storage and transfer techniques are critically reviewed in comparison with the Cylindrical and Rectangular/Square shells/tubes based on the effect of parameters such as solidification/melting performance, enthalpy, fluid flow pattern in the liquid molten state, types of PCM used, etc. The numerical/analytical and experimentation techniques are categorized based on the results of various researcher and conclusion is established.
Power Generation to the Coastal Areas with an Approach to Wave Energy Device-A Prototype
Authors: Rupesh P L , Rana Hitesh Kumar , Shashidar Soma , Satya Sai Darshan M , Varun Teja G
Published: January 2021

Ocean cover more than 70% of earth surface and ocean waves carries enormous wave power. The substantial part of world electricity can be supplied by utilizing the largest source of untapped clean energy (wave energy). Wave energy is more predictable compare to wind energy and can be forecast 24 hours ahead. In this work, the concept of utilization of wave energy in the power generation has been delivered. The approach to wave energy has been done by using the combination of a buoy and a piston. The work described in this paper aims at the design and fabrication of a wave energy device. A numerical study of the power production by the fabricated device has been done for the implementation of this device in the Indian coastal areas for a clean and sustainable power production in future.
Experimental Analysis of Influence of Injection Pressure on Compression Ignition Engine With Biodiesel and Nanoparticles Blend
Authors: Mendonca Sharun , Bhat Thirumaleshwara , Prabhu Ravikantha , Dsouza Rudolf
Published: January 2021

The scarcity of conventional fuel and stringent emission norms made researchers to look after alternative fuels to run an internal combustion engine. One of the possible alternatives for the Compression Ignition engine is biodiesel. Although there are some challenges such as high viscosity, low calorific value, carbon deposit on the injector nozzle, etc. To overcome these challenge nanoparticles are added which will bring most properties near to virgin diesel. Simarouba a non-edible biodiesel feedstock used and aluminum oxide nanoparticles are added with 50 nm size. Using a probe-type Ultrasonication process nano-biodiesel blend is prepared. To improve stability SDS surfactants are added. The characterization of nanoparticles studied using SEM image. The performance of the engine tested for different dosage levels of nanoparticles mainly 25 ppm, 50 ppm, and 75 ppm. The injection timing, injector pressure, and speed kept constant, whereas injection pressure is varied 200 bar, 225 bar, and 250 bar. There is found a 5.2% increase in brake thermal efficiency for nanoparticles added blend biodiesel at 250 bar compare to 200 bar pressure. For the same thing brake specific fuel consumption decreased by 9%. Most of emissions such as Carbon monoxide, unburnt hydrocarbons decreased, whereas there is a significant amount of increase in oxides of nitrogen emission found.
Experimental Model of a Mobile Platform for Moving on Orthogonal Routes
Authors: Mazur Vitaliy V , Panchak Sofiia T
Published: January 2021

The paper considers an experimental model of a mobile platform for moving on orthogonal routes. The advantages of orthogonal routes for planning and ensuring the movement of the platform are shown. The structural scheme of the mobile platform and the organization of functioning of its subsystems are developed. The platform’s construction and digital control system for ensuring its motion and positioning on the marked surface are offered. Methods of traffic organization and routes planning for platform movement are proposed. Peculiarities of using the experimental model of the platform in the educational process of the CAD Department are considered.
Information Technology of Robotic Prosthesis Computer-Aided Design Based on Parametric Modeling
Authors: Parkhomenko A V , Gladkova O M , Zalyubovskiy Y I , Parkhomenko A V
Published: January 2021

The features of modern technologies of three-dimensional parametric modeling were investigated in this paper. It was shown that the application of tabular parameterization makes it possible to increase the efficiency of the computer-aided design of biomedical products by accelerating the development of similar components in their composition. An information technology for the computer-aided design of a robotic prosthesis prototype in the PTC Creo environment has been developed. The functionality of the virtual and physical prototypes of the robotic prosthesis was checked with the usage of digital kinematic simulation and real tests. The developed tabular parametric model makes it possible to control the mass-dimensional characteristics of the product during the development of individual prostheses, taking into account the anatomical features of a particular patient.
Patterns of multimorbidity trajectories and their correlates among Korean older adults
Authors: Lee Sun Ah , Joo Susanna , Chai Hye Won , Jun Hey Jung
Published: January 2021

Objective

This study aims to identify distinct patterns of 10-year multimorbidity trajectory among Korean older adults and examine factors associated with the patterns.

Methods

Data were drawn from the six waves of the Korean Longitudinal Study of Ageing (KLoSA, 2006–2016). We examined trajectories of multimorbidity of 1,705 older adults aged 65 and older using Growth Mixture Modeling. Then, the identified patterns were used as dependent variables to examine the correlates of multimorbidity trajectories. Explanatory variables considered were sociodemographic, psychological, health behavioural and interpersonal factors at baseline.

Results

Four distinct patterns of multimorbidity trajectories were identified: ‘maintaining-low’ (59.4%), ‘chronically-high’ (7.5%), ‘moderately-increasing’ (26.0%) and ‘rapidly- increasing’ (7.1%). Gender, depressive symptoms, life satisfaction and frequency of contacts with others were associated with trajectory membership. Specifically, women were more likely to be in the ‘chronically-high’ group than any other groups. Compared to the ‘maintaining-low’ group, those with higher levels of depressive symptoms and lower levels of life satisfaction were more likely to belong to the ‘chronically-high’ group and ‘moderately-increasing’ group, respectively. Respondents who had less frequent meetings with others in close relationships were more likely to be in the ‘rapidly-increasing’ group than the ‘maintaining-low’ group.

Discussion

These findings are suggestive of distinct trajectories of multimorbidity across older adulthood, indicating that multimorbidity experiences might differ among older adults. Moreover, results suggest that there may be gender inequalities in multimorbidity trajectories, and that levels of psychological well-being and social engagement could be useful in identifying older adults who are at higher risk of worsening multimorbidity.
Ability of Pelvic Magnetic Resonance Imaging to Predict Clinical Course of Perianal Fistula in Paediatric Crohn’s Disease Patients
Authors: Kim Pyeong Hwa , Kim Seo Hee , Cho Young Ah , Yoon Hee Mang , Lee Jin Seong , Jung Ah Young , Oh Seak Hee , Kim Dae Yeon , Namgoong Jung-Man , Kim Kyung Mo
Published: January 2021

Background and Aims

Evidence is limited regarding clinical course and magnetic resonance imaging [MRI] features of perianal fistula [PAF] in Korean children with Crohn’s disease [CD]. We investigated MRI features of PAF and associations with long-term outcomes.

Methods

We retrospectively analysed 243 patients with pelvic MRI for diagnosis of CD. Incidence of clinically evident PAF at diagnosis was determined, as were the proportions of patients with clinical failure [failure to achieve fistula healing within 1 year] and recurrence [new/recurrent PAF after fistula healing within 1 year]. Associations between outcomes and MRI features, specified in modified Van Assche index and MAGNIFI-CD, were evaluated. Associations between later development of clinically evident PAF and subclinical PAF detected on MRI at diagnosis were evaluated.

Results

Among 243 included patients, 108 [44.4%] and 76 [31.3%] had clinically evident and subclinical PAF at diagnosis, respectively; 66.4% of the patients with clinically evident PAF achieved fistula healing within 1 year, and 32.7% of those patients developed recurrence. Fistula length and dominant features of the tracts were associated with clinical failure, and fistula length was associated with recurrence. Clinically evident PAF developed in 17.0% of the patients without clinically evident PAF at diagnosis. We did not find statistically significant association between subclinical PAF and later development of clinically evident PAF [adjusted hazard ratio, 2.438; p = 0.15].

Conclusions

A considerable proportion of Korean paediatric CD patients had clinically evident and subclinical PAF. Fistula length and dominant feature of the tract on MRI are useful predictors of outcomes.
Organization of the micronuclear genome of oxytricha nova.
Authors: Jahn C L , Prescott K E , Waggener M W
Published: January 2021

In the hypotrichous ciliated protozoan Oxytricha nova, approximately 95% of the micronuclear genome, including all of the repetitive DNA and most of the unique sequence DNA, is eliminated during the formation of the macronuclear genome. We have examined the interspersion patterns of repetitive and unique and eliminated and retained sequences in the micronuclear genome by characterizing randomly selected clones of micronuclear DNA. Three major classes of clones have been defined: (1) those containing primarily unique, retained sequences; (2) those containing only unique, eliminated sequences; and (3) those containing only repetitive, eliminated sequences. Clones of type one and three document two aspects of organization observed previously: clustering of macronuclear destined sequences and the presence of a prevalent repetitive element. Clones of the second type demonstrate for the first time that eliminated unique sequence DNA occurs in long stretches uninterrupted by repetitive sequences. To further examine repetitive sequence interspersion, we characterized the repetitive sequence family that is present in 50% of the clones (class three above). A consensus map of this element was obtained by mapping approximately 80 phage clones and by hybridization to digests of micronuclear DNA. The repeat element is extremely large (approximately 24 kb) and is interspersed with both macronuclear destined sequences and eliminated unique sequences.
Molecular evolution of the Escherichia coli chromosome. II. Clonal segments.
Authors: Milkman R , Stoltzfus A
Published: January 2021

Remarkable sequence similarities in the trp region among Escherichia coli strains of diverse natural origins imply the existence of worldwide clones of very recent origin. This in turn implies a low rate of fixation of new universally favorable alleles, which carry adjacent stretches of chromosome to high frequency. These clonal segments begin as entire chromosomes; recombination shortens them progressively by substituting less closely related homologous DNA. The rate of this recombination, comprising the introduction of a homologous chromosomal fragment to a cell and the replacement of part of the original chromosome, is estimated from observations.
The mutation bronze-mutable 4 derivative 6856 in maize is caused by the insertion of a novel 6.7-kilobase pair transposon in the untranslated leader region of the bronze-1 gene.
Authors: Klein A S , Clancy M , Paje-Manalo L , Furtek D B , Hannah L C , Nelson O E
Published: January 2021

The Ds-controlled allele, bz-m4 Derivative 6856 [bz-m4 D6856], is reported to have an altered temporal- and tissue-specific pattern of gene expression. We have cloned this allele and have characterized it at the molecular level. The mutation was caused by the insertion of a complex transposon-like structure 36 base pairs downstream from the Bz mRNA cap site. The insert is 6.7-kbp long. Ds elements, each approximately 2 kbp in length, are at both ends of the insert. The sequence between the Ds elements is a partial duplication of flanking sequences from the 3' end of the Bz gene. These data suggest that Ds initially inserted near the 3' end of the gene and mobilized adjacent sequences as it transposed.
Identification and characterization of mutations affecting sporulation in Saccharomyces cerevisiae.
Authors: Smith L M , Robbins L G , Kennedy A , Magee P T
Published: January 2021

Mutations affecting the synthesis of the sporulation amyloglucosidase were isolated in a homothallic strain of Saccharomyces cerevisiae, SCMS7-1. Two were found, both of which were deficient in sporulation at 34 degrees. One, SL484, sporulated to 50% normal levels at 30 degrees but less than 5% at 34 degrees or 22 degrees. The other, SL641, failed to sporulate at any temperature. Both mutants were blocked before premeiotic DNA synthesis, and both complemented spo1, spo3, and spo7. Genetic analysis of the mutation in SL484 indicated linkage to TRP5 and placed the gene 10 map units from TRP5 on chromosome VII. A plasmid containing an insert which complements the mutation in SL484 fails to complement SL641. We therefore conclude that these two mutations are in separate genes and we propose to call these genes SPO17 and SPO18. These two genes are (with SPO7, SPO8, and SPO9) among the earliest identified in the sporulation pathway and may interact directly with the positive and negative regulators RME and IME.
Mutations in elongation factor EF-1 alpha affect the frequency of frameshifting and amino acid misincorporation in Saccharomyces cerevisiae.
Authors: Sandbaken M G , Culbertson M R
Published: January 2021

A mutational analysis of the eukaryotic elongation factor EF-1 alpha indicates that this protein functions to limit the frequency of errors during genetic code translation. We found that both amino acid misincorporation and reading frame errors are controlled by EF-1 alpha. In order to examine the function of this protein, the TEF2 gene, which encodes EF-1 alpha in Saccharomyces cerevisiae, was mutagenized in vitro with hydroxylamine. Sixteen independent TEF2 alleles were isolated by their ability to suppress frameshift mutations. DNA sequence analysis identified eight different sites in the EF-1 alpha protein that elevate the frequency of mistranslation when mutated. These sites are located in two different regions of the protein. Amino acid substitutions located in or near the GTP-binding and hydrolysis domain of the protein cause suppression of frameshift and nonsense mutations. These mutations may effect mistranslation by altering the binding or hydrolysis of GTP. Amino acid substitutions located adjacent to a putative aminoacyl-tRNA binding region also suppress frameshift and nonsense mutations. These mutations may alter the binding of aminoacyl-tRNA by EF-1 alpha. The identification of frameshift and nonsense suppressor mutations in EF-1 alpha indicates a role for this protein in limiting amino acid misincorporation and reading frame errors. We suggest that these types of errors are controlled by a common mechanism or closely related mechanisms.
INOSITOL-REQUIRING MUTANTS OF SACCHAROMYCES CEREVISIAE
Authors: Culbertson Michael R , Henry Susan A
Published: January 2021

Fifty-two inositol-requiring mutants of Saccharomyces cerevisiae were isolated following mutagenesis with ethyl methanesulfonate. Complementation and tetrad analysis revealed ten major complementation classes, representing ten independently segregating loci (designated in01 through inol0) which recombined freely with their respective centromeres. Members of any given complementation class segregated as alleles of a single locus. Thirteen complementation subclasses were identified among thirty-six mutants which behaved as alleles of the inol locus. The complementation map for these mutants was circular.—Dramatic cell viability losses indicative of unbalanced growth were observed in liquid cultures of representative mutants under conditions of inositol starvation. Investigation of the timing, kinetics, and extent of cell death revealed that losses in cell viability in the range of 2-4 log orders could be prevented by the addition of inositol to the medium or by disruption of protein synthesis with cycloheximide. Mutants defective in nine of the ten loci identified in this study displayed these unusual characteristics. The results suggest an important physiological role for inositol that may be related to its cellular localization and function in membrane phospholipids. The possibility is discussed that inositol deficiency initiates the process of unbalanced growth leading to cell death through the loss of normal assembly, function, or integrity of biomembranes—Part of this work has been reported in preliminary form (CULBERTSON and HENRY1 974).
A NEW TYPE OF MUTATION IN SCHIZOSACCHAROMYCES POMBE: VEGETATIVE IODINE REACTION
Authors: Meade James H , Gutz Herbert
Published: January 2021

Colonies of Schizosaccharomyces pombe that contain ascospores (e.g., colonies of homothallic strains) turn black after treatment with iodine vapors. Heterothallic strains of S. pombe normally do not show this reaction. In experiments with the latter strains we found mutants which exhibit a positive iodine reaction though they do not contain ascospores. This phenotype is due to mutations in a new gene, vir1 (vegetative iodine reaction). The vir1 locus is not linked with the mating-type genes.—Strains of mating-type h-s are known not to give any spontaneous mating-type mutations. Mating-type mutations were also not found after treatment with nitrous acid.
IMMUNE RESPONSE AND THE B BLOOD GROUP LOCUS IN CHICKENS
Authors: Pevzner Igal , Nordskog Arne W , Kaeberle Merlin L
Published: January 2021

Chickens of three blood group genotypes, B1B1, B1B2 and B1B19, were compared in their ability to produce antibodies. The B locus is the major histocompatibility locus in this species. Homozygous B1 pullets had significantly higher adult mortality than did the B1 heterozygotes. In two separate experiments the B1B1 females produced significantly fewer antibodies to Salmonella pullorum than did the B1 heterozygotes. Also the B1B1 pullets responded with lower antibody titers following immunization with ferritin, bovine serum albumin and parainfluenza-3 virus, although the differences were not significant. The results of this study suggest that an immune response gene is associated with the major histocompatibility locus in chickens, paralleling the H-2 locus and Ir genes in mice.
POPULATION GENETICS OF ALLOZYME VARIATION IN NEUROSPORA INTERMEDIA
Authors: Spieth P T
Published: January 2021

Electrophoretically detectable variation in the fungus Neurospora intermedia has been surveyed among isolates from natural populations in Malaya, Papua, Australia and Florida. The principal result is a pattern of genetic variation within and between populations that is qualitatively no different than the well documented patterns for Drosophila and humans. In particular, there is a high level of genetic variation, the majority of which occurs at the level of local populations. Evidence is presented which argues that N. intermedia has a population structure analogous to that of an annual vascular plant with a high level of vegetative reproduction. Sexual reproduction appears to be a regular feature in the biology of the species. Substantial heterokaryon function seems unlikely in natural populations of N. intermedia. Theoretical considerations concerning the mechanisms underlying the observed pattern of variation most likely should be consistent with haploid selection theory. The implications of this constraint upon the theory are discussed in detail, leading to the presentation of a model based upon the concept of environmental heterogeneity. The essence of the model, which is equally applicable to haploid and diploid situations, is a shifting distribution of multiple adaptive niches among local populations such that a given population has a small net selective pressure in favor of one allele or another, depending upon its particular distribution of niches. Gene flow among neighboring populations with differing net selective pressures is postulated as the principal factor underlying intrapopulational allozyme variation.
Anisotropic a posteriori error estimate for the virtual element method
Authors: Antonietti P F , Berrone S , Borio A , D’Auria A , Verani M , Weisser S
Published: January 2021

We derive an anisotropic a posteriori error estimate for the adaptive conforming virtual element approximation of a paradigmatic two-dimensional elliptic problem. In particular, we introduce a quasi-interpolant operator and exploit its approximation results to prove the reliability of the error indicator. We design and implement the corresponding adaptive polygonal anisotropic algorithm. Several numerical tests assess the superiority of the proposed algorithm in comparison with standard polygonal isotropic mesh refinement schemes.
Early Differences in Cytokine Production by Severity of Coronavirus Disease 2019
Authors: Tjan Lidya Handayani , Furukawa Koichi , Nagano Tatsuya , Kiriu Tatsunori , Nishimura Mitsuhiro , Arii Jun , Hino Yasuhisa , Iwata Sachiyo , Nishimura Yoshihiro , Mori Yasuko
Published: January 2021

Most patients with coronavirus disease 2019 (COVID-19) experience asymptomatic disease or mild symptoms, but some have critical symptoms requiring intensive care. It is important to determine how patients with asymptomatic or mild COVID-19 react to severe acute respiratory syndrome coronavirus 2 infection and suppress virus spread. Innate immunity is important for evasion from the first virus attack, and it may play an important role in the pathogenesis in these patients. We measured serum cytokine levels in 95 patients with COVID-19 during the infection’s acute phase and report that significantly higher interleukin 12 and 2 levels were induced in patients with asymptomatic or mild disease than in those with moderate or severe disease, indicating the key roles of these cytokines in the pathogenesis of asymptomatic or mild COVID-19.