bluuebunny/crossref_metadata_2025 huggingface dataset:
Multistage Acid-fracturing Increases the Dolomite Production in High Temperature Deep Horizontal Well
Authors: Che Mingguang , Wang Yonghui , Zhou Changlin , Wang Meng , Liu Fei , Fu Haifeng , Dong Kai
Published: March 2021

The Sinian dolomite reservoirs in Southwest Oil and Gas Field, China, are characterized by HTHP, high stress, low porosity and permeability, large thickness, and presence of natural fractures and holes. Highly deviated well multistage acid fracturing can help expand the contacting area between wellbore and reservoir, thereby increasing the well production. Through experiments, acid fracturing simulations, staging optimization and field applications, some conclusions were obtained. Large-scale physical modelling experiments and numerical simulations show that, given the high horizontal stress difference, presence of natural fractures, can induce a complex fractures networks. The acid systems with different viscosities, such as self-generating acid, gelled acid and diverting acid, are optimized to, in conjunction with highrate injection and temporary diverting, improve the stimulated reservoir volume and conductivity of acid-fractures in the dolomite reservoirs. The combination of mechanical packers and sliding sleeves facilitate the effective isolation of HTHP dolomite reservoir. The positions of the sliding sleeves are designed according to the high-quality reservoir intervals determined by logging interpretation. The lateral of deviated well is 480m-970m long and stimulated by acid fracturing in 3-6 stages. The post-fracturing tracer testing proves the effectiveness of isolation. This technology was applied for 6 wells, with a daily gas production of (21–110) × 104m3/d after acid fracturing. It provides a new method to increase the production of highly deviated wells or horizontal wells in deep carbonate reservoirs.
Risk Analysis and Emergency Response to Marine Oil Spill Environmental Pollution
Authors: Chenhao Jin , Yupeng Xu
Published: March 2021

The offshore petroleum industry operates in a harsh environment, which poses a great safety risk and accident rescue difficulty. With the increasing volume of world offshore oil transportation and the vigorous development of the offshore oil exploration and development business, the number of marine oil spill accidents has increased significantly, which will cause huge pollution to the marine ecological environment and also attract widespread attention from the media and the public. This paper mainly analyzes the risk of marine oil spill pollution accidents in terms of causes, characteristics and hazards, and proposes specific measures and accident prevention and emergency disposal plans in accordance with relevant standards.
Degradation of metronidazole simulated water by nanosecond pulsed DBD plasma
Authors: Fan Yangyang , Cheng Jiushan , Chen Qiang
Published: March 2021

In this work, nanosecond pulsed dielectric barrier discharge (nsp-DBD) plasma was used to degrade metronidazole simulated water under Air gas. The effects of initial concentrations, pulse peak voltages and air flow rates on metronidazole degradation were investigated, respectively. The role of hydroxyl radical in the metronidazole degradation was emphasized. The variations of solution pH value and conductivity during the discharge process were measured. Experimental results show that nsp-DBD plasma can effectively degrade metronidazole simulated water. When the initial concentration was 100 mg/L, the pluse peak voltage was 15 kV, and the air flow rate was 3 L/min, the degradation efficiency and energy yield of metronidazole were 92% and 1.83g/kWh, respectively, after 25 min treatment. The mineralization rate reached 39% after 60 min of treatment. The scavenger experiment proved that the hydroxyl radical was the main active species in metronidazole degradation. The solution pH was significantly reduced, and the conductivity was greatly increased after plasma treatment, which were corresponded to the formation of NO3
−, NO2
− and intermediate products in the degradation process.
Analysis of Polar Components in Potato Wide Vermicelli by GC-MS
Authors: Yue Bin , Wen Yijun , Chen Weidong , Yin Zhuoxin , Xing Jiarui
Published: March 2021

In order to arouse the society’s attention to the ecological environment and food safety, the traditional food with rich nutrition - vermicelli was regarded the research object. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the polar components of potato wide vermicelli. The results showed that twenty more polar organic matters were detected in potato wide vermicelli, containing saturated fatty acids, unsaturated fatty acid and phthalate (PAEs). The content of unsaturated fatty acid on the surface of the wide vermicelli was higher than that on the inside. The phthalate only exists on the surface of the wide vermicelli. People should reduce the use of disposable plastic products to reduce the negative effects of plastics on human health and realize the healthy development of the human ecological environment.
Introduction of SOC estimation method
Authors: Ren Gaojian
Published: March 2021

This paper introduces the definition of SOC estimation and analyzes the common estimation methods, including discharge experiment method, open circuit voltage method, internal resistance method, ampere hour method, linear model method, neural network algorithm and Kalman filter method. Through the comparison and analysis of various methods, it provides a scientific choice for the SOC estimation method of nickel hydrogen battery.
Study and Application of quickly putting into Production Technology without well killing in Shale Oil
Authors: Liu Panfeng , Wang Junheng , Fu Daqi , Guo Qun , Ren Shiju
Published: March 2021

Low-producing shale oil wells are put into production after reservoir modification. But the dynamic fluid level drops significantly in the initial stage, which result in a reduction in sand carrying capacity and a significant reduction in pumping efficiency. It also results in a significant shortening of the pumping inspection cycle. After the checking pump operation with conventional killing well, wells were found that the capacity recovery period was long. And the period of operating under pressure was long and costly. Checking pump cost increased significantly. Based on the situation of low-producing shale oil wells in the DA oilfield, by optimizing the downhole temporary plugging of the tubular column and simulating the timing of down pump, a quickly put into production technology of rod pump in shale oil is proposed. The technology can achieve downhole temporary plugging fast before checking pump, and lift out or lower pump without killing well. The field application shows that this technology can reduce the contamination of tight reservoirs result by killing fluid and significantly shorten the production recovery cycle.
Analysis on the operation mechanism of spot mode adapting to the initial stage of China’s electricity spot market
Authors: Liu Dunnan , Zhang Tingting , Gao Yuan , Li Hua , Liu Mingguang , Jia Heping
Published: March 2021

In the new round of power system reform, the construction of power market is the top priority. It is particularly important to design a reasonable power market construction path for the smooth transition from planned mode to market mode and finally achieve the target market mode. This paper makes a comparative analysis of the decentralized market and the centralized market, and further analyses its applicability and the necessity of medium and long-term contracts according to its characteristics. It proposes to coordinate the generation resources, grid structure and load resources within the jurisdiction of the power grid, and implement the decentralized power market mode for the parts that have the ability to achieve self-balance, that is, the physical execution of medium and long-term contracts; For some units with large deviation and without physical execution or for some period of time, the centralized power market mode is implemented. The specific mode division adopts the principle of adjusting measures to local conditions, and strives to realize the smooth transition of market construction.
Optimal Power Flow Preventive Control Considering Wind Farm Access
Authors: Chen Fan , Liu Zhiqing , Qiu Jifu , Lu Zhipeng , Chen Ming , Niu Qingda , Dong Xiaoming
Published: March 2021

Renewable energy access will be an important trend in the development of the future power grid. In order to analyze the uncertainty brought by wind power access and improve the safety of the grid during steady-state operation, this paper models the uncertainty of wind power. An optimal power flow model considering the risk of power and voltage overruns is established. The model takes the optimal cost of power generation as the goal, takes into account the influence of transformer tap adjustment on system network parameters, and the constraint conditions take into account unit power and safety constraints, it is solved by the primal dual interior point method. The effectiveness of the model and algorithm proposed in this paper is verified by the IEEE14 test system.
Optimal operation of tidal plants based on nonlinear model predictive control strategy
Authors: Shen Yang , Nyman Per-Ole
Published: March 2021

Tidal range barrage is a well-recognized approach to extract energy from tides in a large scale. Nevertheless, the complexity of tide oscillation poses a challenge to efficaciously regulate this type of plants. Optimization of the process control may result in enhancement of energy yield with low influences on environment. This paper presents a framework where the whole tidal-electric system is modelled and coupled with a nonlinear model predictive control (NMPC) strategy to determine the optimal state of turbo-generators over a complete spring-neap cycle in a month. The method allows the system model to be nonlinear and dynamic under tight constraints, which would be extremely appropriate for the deployment of this highly predictable but frequently varied energy. A potential bay in Norway is chosen to be a proposal site to verify the benefits of the control strategy, by comparing the energy extraction between a simple barrage without sluices and a conventional one with sluices assembly. Results show the conventional barrage type is superior with respect to energy generation, while keeping the turbine blade diameter as as factor. For excessively large turbines, though, the revenue may be curtailed by costs due to environmental factors, and turbine construction.
Research on the Construction Elements of the New Generation Power System
Authors: Li Zhuonan , Zheng Kuan , Wu Shengyu
Published: March 2021

With the massive consumption of fossil energy, the traditional power system can no longer meet the high-quality development of the economy and society and the strict requirements of the ecological environment. The whole society urgently needs to build a new generation of power system to achieve the healthy development of the economy and society under increasingly strict constraints. For the new generation of power systems, the mainstream direction is that they should promote the deep replacement of fossil energy with electric energy in the energy consumption link, and increase the proportion of electricity in the final energy consumption and clean power generation. In addition, it should also include the informatization, intelligence and digitization of the power and even energy systems, and realize the iterative optimization of the whole system with faster communication and faster computer processing technology. In this paper, Dematel analysis method was used to identify and screen the construction elements of the new generation power system. And the role of each element in the construction process was analyzed, thus the key areas in the construction of the new generation power system were clarified.
Engineering design and static load test of Soil filling pile with spiral cone foundation
Authors: Jin Zhengchao , Fang Guangxiu , Zhao Shifan
Published: March 2021

This paper introduces the innovative soil filling pile with spiral cone technology, and through the soil filling pile with spiral cone foundation static load detection of phase 4 project of Bishui Gardens, Yanji City, Jilin Province, proposed the following design suggestions: When the diameter of the pile is 500mm, the length of the pile is 12-20m, the maximum settlement interval is 28.04 ∼ 44.85mm; the vertical ultimate bearing capacity of single pile is 3600∼4000KN. The pile can speed up the construction period, ensure the project quality and reduce the project cost. It has obvious technical advantages and has obtained good economic and social benefits. It is a new type of energy-saving and emission-reduction pile foundation with extensive application prospects.
Micro-scale investigation on the effect of waterflooding rate on oil recovery and residual oil distribution
Authors: Zhang Tongyao , Chen Ke , Zhang Xudong
Published: March 2021

Waterflooding is currently one of the most common and mature oil and gas development methods. However, when oil and gas fields enters the medium or high water-cut period, there is still a large amount of residual oil remaining untapped while residual oil characteristics and distribution could be complicated. Micromodel method is considered as a novel experimental method for studying residual oil characteristics and waterflooding. Unlike conventional core flooding, visualization of the whole process can be realized through micromodels. In this work, three different flooding rates were used to simulate the waterflooding process via micromodels. Consequently, oil recovery rates and residual oil distribution were obtained. It was observed that higher waterflooding rate increased the oil recovery. When the flooding rate was large, dispersed residual oil was observed after waterflooding. When the rate was small, residual oil exhibited more complicated configurations. For the trapped residual oil in the dead end pores in hydrophilic rock matrix, increasing the flooding rate or the viscosity of displacing phase could be beneficial to dislodge the residual oil.
Acidizing Treatment Reconstruction Practice for Limestone Resources
Authors: Taiwei Yang , Yu Yan , Shuzhao Guo , Qingqin Cai , Yang Yang , Yuqiao Du
Published: March 2021

With abundant oil and gas resources, limestone oil and gas resources are characterized by complex composition, uneven distribution, low natural productivity, and susceptibility to contamination, acidizing is an important measure to put this kind of oil and gas wells into production and increase production, but the effect of acidizing measure varies from block to block. This paper attempts to identify the difficulties in acidizing process by analyzing the reservoir character of multiple limestone reservoir systems in D Oilfield region, and to finalize matrix acidizing, retarded acidizing fracturing and multi-stage injection fracturing as three alternatives through single-well and block analysis, according to the permeability, pore throat development and lithological character. After the acidizing measure was implemented, good results were attained.
Operation Analysis of the Natural Gas Distributed Energy System
Authors: Zhao Lei
Published: March 2021

This paper analyzes the cold, heat and electric loads of a hospital in China’s severe cold area, and determines the equipment scheme of the natural gas distributed energy system. Based on the lowest cost, the operation principle of the energy supply system is determined, and the annual balance of cold, heat and electric loads in the hospital is analyzed.
Design of renewable energy consumption market system based on the interactive transaction of source-grid-load-storage
Authors: Liu Dunnan , Zhang Tingting , Li Hua , Liu Mingguang , Jia Heping
Published: March 2021

Renewable energy has the characteristics of clean, safe and low variable cost. High proportion of renewable energy access is of great significance for improving energy structure and improving power economy. However, with the continuous increase of renewable energy access ratio, in the case of full guaranteed acquisition, the peak load regulation capacity of power generation side will be insufficient, which can’t meet the requirements of full purchase of renewable energy, resulting in the phenomenon of power abandonment. It is urgent to stimulate the interactive ability of all users to participate in the consumption of renewable energy. Based on this, this paper puts forward a renewable energy consumption market system which includes medium and long-term, day ahead and real-time trading mode to promote the interaction between source network and load storage. Through the design of the mechanism, we can give full play to the regulatory potential of the user side and let the more efficient renewable energy units obtain more auxiliary service resources.
Technical Analysis of Grid Connection of High-speed Railway Power Through Lines
Authors: Chen Xiaolin
Published: March 2021

For the power communication system of the high-speed railway, the power through line is the core power supply line, and its operation effect has a vital effect on the safety and stability of the high-speed railway operation. However, because the power penetrating line is largely restricted by the power system, and the lightning protection measures and insulation level are relatively weak, the grid connection is also very difficult. In order to realize the effective grid connection of high-speed railway power through-line, this paper analyzes its grid connection technology. In this analysis, it first analyzes the overall overview of the high-speed rail power penetration system; then it analyzes the specific principles of grid connection of the high-speed rail power penetration line; Finally, the simulation calculation and analysis of the specific grid connection are carried out. It is hoped that this analysis can provide sufficient technical support for the grid connection of the high-speed rail power through-line, so as to improve its application effect and safety.
Fault location of hybrid distribution lines based on empirical mode decomposition
Authors: Song YunDong , Han Honggang , Liu Miao , Wang Guanyu
Published: March 2021

This paper presents a fault location method for cable hybrid distribution lines based on EMD and TEO algorithm. Firstly, the fault signal is decomposed by EMD. Then, the transient energy spectrum of high frequency imf1 component is obtained by using Teager energy operator. The first energy singularity is the time when the fault initial traveling wave head reaches the detection point. Finally, the fault location is carried out according to the fault search algorithm based on time variable. According to the simulation results, EMD and TEO methods have better fault extraction ability and higher accuracy in fault location.
Research on the Relationship of Symbiotic Subject in Urban Energy Saving Innovation Ecosystem
Authors: Hong Shuai , Li Zhiyu , Zhang Mengyuan
Published: March 2021

As an important space carrier of sustainable development of human settlements, cities are the basic regional units to promote energy saving innovation, improve energy efficiency and reduce emissions. It is very important to promote the process of urban sustainable development. On the basis of literature review, the government and energy saving enterprises are identified as the symbiotic subjects of urban energy saving innovation ecosystem. Based on logistic equation, this paper constructs a dual agent symbiosis model of urban energy saving innovation ecosystem. The simulation results show that the positive and negative of the symbiosis coefficient is an important parameter affecting the results of symbiosis equilibrium on urban energy saving innovation ecosystem. When the symbiosis coefficient is negative, the coordination and promotion between symbiotic subjects is greater than competition and competition, which makes the existing resources meet the needs of more symbiotic subjects to participate in urban energy saving.
Study on regeneration and desiliconization purification of pickling waste liquid of building steel
Authors: Shining Chen , Chengnian Tang
Published: March 2021

In this paper, Fe2O3 power was used to replace the scrap steel in the traditional process, as the medium for removing the free acid in the waste acid solution of the cold-rolled strip pickling. The removal effect of free acid and silicon of the system with Fe2O3 addition and crap steel were compared. The results indicated that the system with Fe2O3 addition obtained a better effect. Subsequently, the optimum dosage, optimum reaction temperature and time were determined by the orthogonal experiment. The effect of flocculants of polyacrylamide (PAM), PAC, PAM+PAC and MgCl2 with the desiliconization was explored.
The Assessment of Modern Community Security Risks in Megacities Based on the Dempster–Shafer Theory
Authors: Yin Ke , Zhou Haiyun , Chen Jimin , Zhao Chen
Published: March 2021

Through the study of community security risks in a megacity by employing the Dempster–Shafer theory, this paper developed an indicator system for the assessment of urban community security based on a combined array of both static and dynamic factors including natural disasters, man-made hazards, community administration and security support. A proper model was thereafter designed. Precluding content inadequacy, insufficient indicators and model inaccuracy and other problems occurred in preceding assessments predicted upon a combination of both static and dynamic factors, these efforts have enabled more effective urban community security assessment through a case study.
Research on Intelligent Trash Bin Design Based on Visual Recognition of Machine
Authors: Gu Junpei , Zhang Jianyi , Sui Haolin , Zou Bingxin
Published: March 2021

Objective: To help the public solve the problem of garbage classification by means of science and technology, make automatic garbage classification through an intelligent trash bin, realize harmless garbage disposal and reduce pollution, thus facilitating environmental protection.

Methods: The type of garbage is determined by visual recognition of a machine to achieve the effect of garbage classification. In terms of visual recognition, feature points of garbage pictures are compared by the combination of hardware and software, the data is trained and optimized with deep learning technology and images are compared based on the VGG16 convolutional neural network model.

Result: A simple and small intelligent trash bin is obtained. Conclusion: Theoretical support is provided for the application of intelligent classification trash bins.
Application Research of Intelligent Control Algorithm in Air Conditioning System
Authors: Yang Xin , Zhao Yuqing , Deng Jiayu , Tang Shengshi , Su Hexuan , Zhao Xinran
Published: March 2021

In order to reduce the energy consumption of HVAC system, we analyzed and compared modern intelligent control algorithm applied to HVAC control system, introduced the basic principles of fuzzy control, neural network and genetic algorithm, and analyzed the applicability of intelligent algorithm in HVAC system with engineering examples.
Sea Restoration and Assessment of Ecosystem in Ningbo City
Authors: Liu Hongdan , Jin Xinfei , Shen Chen , Ying Hong , Wu Weifei , Zhou Xuerong , Liu Xu , Dong Haiyang
Published: March 2021

From the perspective of the demand of marine ecosystem service function, this paper collects, sorts out and analyzes the marine ecological restoration related work by reclamation survey, mainland coastline survey, island coastline survey, blue bay application, coastal zone restoration project, ecological assessment and restoration of reclamation projects in counties (cities and districts). The successful experience of marine ecological restoration is analyzed, summarized and explored to present a relatively complete and typical marine ecological restoration scheme. Through the case study of typical ecological restoration, the optimized marine ecological restoration procedure is established. According to the development status and problems of different sea areas and coastal zones, the most suitable marine ecological restoration scheme is found, so as to solve specific marine environmental problems, and provide case reference and theoretical basis for subsequent marine ecological restoration.
Research on the Requirements of Artificial Intelligence on Applied Talents Cultivation
Authors: Liu Wenhua
Published: March 2021

Strengthening the training of artificial intelligence talents and developing the artificial intelligence industry should be the only way to gain a foothold in the future of technology and talent competition. At the same time, it can promote the establishment of the highland of independent innovation in the field of AI. Talents market situation provides new requirement to talents cultivation in universities. But it should also be noted that AI development in universities meets with pretty problems. These are the newly-constructed related programs just growing in recent few years, the weakening of AI faculties in universities, especially the fragmentary of education system. Therefore, universities should promote the development of quality programs in the field of AI to get a new goal of talents cultivating. Otherwise, we should strengthen the integration and cooperation between AI and other applied programs to perform AI program structure and keep on classified and stratified cultivating to form a brand-new mode of talents training in all the field of AI.
Influent property forecasting of sewage treatment based on big data analysis approach
Authors: Cheng Zhiwei , Xie Zhihong , Deng Yongsheng , Wang Xiaodan
Published: March 2021

Precise influent property forecasting is very important to maintain the stable operation of sewage treatment procedure. A big data analysis method of combining the wavelet packet transform (WPT) and adaptive network-based fuzzy inference system (ANFIS) is reported to solve this problem. In this approach, the WPT is used to decompose the influent property data in different cycles. The time sub-series, which are results of wavelet coefficients reconstruction, are employed to establish the forecasting system. The forecasting sub-results of each cycle are eventually integrated into an overall forecasting result. Furthermore, chaos theory is introduced to obtain the input structure of the multi-cycle regression models. The reported approach is verified by the historical influent property. A back propagation neural network and the standard ANFIS are used for a comparison test. The results demonstrate that the reported method has best ability in the peer models.
Whole-process Risk Identification of Urban Rainwater Resource Utilization and Construction of Evaluation Index System in Loess Plateau Region
Authors: Qin Li , Ma Chengxiang , Mu Yunxiao
Published: March 2021

The whole process from the external environment of urban rainwater resource development and utilization, urban natural and social characteristics, engineering system, to engineering operations management, etc. was taken as the basic environment for the risk identification of urban rainwater resource utilization, and it was proposed that the urban rainwater resource utilization risk was the positive or negative effect generated by all uncertainties in the whole urban rainwater development and utilization process on the urban rainwater resource utilization goals; based on the risk identification environment and risk definition, the urban rainwater resource utilization risk was divided into social environmental risk, ecological environmental risk, water volume risk, water quality risk, and water price risk, and an list of evaluation indexes, which consisted of target layer, criterion layer and index layer, was comprehensively established for the urban rainwater resource utilization risk; according to the characteristics and current situation of typical urban rainwater resource utilization in Loess Plateau region, the principal component analysis (PCA) was used to screen out 14 evaluation indexes reflecting the urban rainwater resource utilization risks in Loess Plateau region, and an evaluation index system was further constructed, thus laying a foundation for the risk evaluation and control of urban rainwater resource utilization.
Research and Development of Light Municipal Technology System Based on Green Development Concept
Authors: Huang Fei , Xue Xiaoning , Yin Wenchao , Xu Bin , Zhao Xin , Wei Guqiang , He Zirui
Published: March 2021

The application of a light municipal system will become an essential means to improve cities’ total carrying capacity and realize the sustainable development of green ecology in urban and rural areas. The green technology system adopted by a light municipal system’s regional development model can reduce traditional municipal facilities development’s initial cost. The saved investment cost of early facilities is enough to offset the increased late green technology application cost. While the region realizes green development, the overall economy can also be fully guaranteed. This paper analyses the light municipal system’s applicable conditions to popularize and apply this technical system in a broader range.
Modernisation of the Energy Charter Treaty in Environmental Protection: Challenges and China’s Role
Authors: Zuo Mengxue
Published: March 2021

The Energy Charter Treaty is the only legally binding multilateral framework in the field of energy, playing a key role in energy investment protection, green energy, and climate change solution. However, it is difficult to address the issues that have arisen as a result of the regional concentration of States parties, vague expression of the provisions, and the treaty’s role in protecting the environment and promoting sustainable development of energy. Therefore, the modernisation of Energy Charter Treaty becomes the inevitable choice at present. Only through emphasizing the respect for multiculturalism and concentrating on the industry’s interests can the right way to modernisation be found. During this process, China, a new major energy investor, seeks green development and clean energy, with the goal of sustainable development that is consistent with the principles of the Energy Charter Treaty. As a result, China plays a crucial role in the modernisation of the Energy Charter Treaty.
Conglomerate but not Homogenized
Authors: Rosen Jeremy
Published: March 2021

The essays collected in “Literature and Publishing, 1945–2020” consider the ways the conglomerated global publishing industry has incorporated and commodified varied genres and target publics. The essays employ intensive archival, ethnographic, and computational methods, and they dive into often-neglected genres, in order to fill in this familiar narrative outline with vivid detail, complicating it and at times discovering countervailing trends that persist within conglomerate publishing’s pursuit of short-term economic profit. While the contributors tend to emphasize the dominance of an increasingly homogenizing corporate aesthetic inimical to experiment, they also acknowledge the potential for individual writers, editors, and agents to intervene in the market, shifting and diversifying the field and preserving literary values, even as they attend to the fiscal bottom line. This commentary stresses the variability of genre, publishers’ persistent search for novelty, and conglomerates’ desire to compete for prestige with small but influential independent presses in order to explain the continued efflorescence of a dazzling diversity of contemporary literary production within a field that continues to consolidate dramatically at its top end, and whose retail side is dominated by a single behemoth.
Lichens buffer tundra microclimate more than the expanding shrub Betula nana
Authors: Mallen-Cooper Max , Graae Bente J , Cornwell Will K
Published: March 2021

Background and Aims

In tundra systems, soil-borne lichens are often the dominant groundcover organisms, and act to buffer microclimate extremes within or at the surface of the soil. However, shrubs are currently expanding across tundra systems, potentially causing major shifts in the microclimate landscape.

Methods

Here, we compared soil temperature and moisture underneath the dwarf birch Betula nana and seven abundant lichen species in sub-alpine Norway. We also examined mixtures of lichens and dwarf birch – an intermediate phase of shrubification – and measured several functional traits relating to microclimate.

Key Results

We found that all lichen species strongly buffered the daily temperature range, on average reducing maximum temperatures by 6.9 °C (± 0.7 s.d.) and increasing minimum temperatures by 1.0 °C (± 0.2 s.d.) during summer. The dwarf birch had a much weaker effect (maximum reduced by 2.4 ± 5.0 °C and minimum raised by 0.2 ± 0.9 °C). In species mixtures, the lichen effect predominated, affecting temperature extremes by more than would be expected from their abundance. Lichens also tended to reduce soil moisture, which could be explained by their ability to intercept rainfall. Our trait measurements under laboratory conditions suggest that, on average, lichens can completely absorb a 4.09 mm (± 1.81 s.d.) rainfall event, which might be an underappreciated part of lichen–vascular plant competition in areas where summer rainfall events are small.

Conclusions

In the context of shrubification across tundra systems, our findings suggest that lichens will continue to have a large effect on microclimate until they are fully excluded, at which point microclimate extremes will increase greatly.
New framework for recombination and adaptive evolution analysis with application to the novel coronavirus SARS-CoV-2
Authors: Wang Yinghan , Zeng Jinfeng , Zhang Chi , Chen Cai , Qiu Zekai , Pang Jiali , Xu Yutian , Dong Zhiqi , Song Yanxin , Liu Weiying , Dong Peipei , Sun Litao , Chen Yao-Qing , Shu Yuelong , Du Xiangjun
Published: March 2021

The 2019 novel coronavirus (SARS-CoV-2) has spread rapidly worldwide and was declared a pandemic by the WHO in March 2020. The evolution of SARS-CoV-2, either in its natural reservoir or in the human population, is still unclear, but this knowledge is essential for effective prevention and control. We propose a new framework to systematically identify recombination events, excluding those due to noise and convergent evolution. We found that several recombination events occurred for SARS-CoV-2 before its transfer to humans, including a more recent recombination event in the receptor-binding domain. We also constructed a probabilistic mutation network to explore the diversity and evolution of SARS-CoV-2 after human infection. Clustering results show that the novel coronavirus has diverged into several clusters that cocirculate over time in various regions and that several mutations across the genome are fixed during transmission throughout the human population, including D614G in the S gene and two accompanied mutations in ORF1ab. Together, these findings suggest that SARS-CoV-2 experienced a complicated evolution process in the natural environment and point to its continuous adaptation to humans. The new framework proposed in this study can help our understanding of and response to other emerging pathogens.
Attainment and maintenance of pubertal cyclicity may predict reproductive longevity in beef heifers
Authors: Nafziger Sarah R , Tenley Sarah C , Summers Adam F , Abedal-Majed Mohamed A , Hart Mariah , Bergman Jeffrey W , Kurz Scott G , Davis John S , Wood Jennifer R , Cupp Andrea S
Published: March 2021

We hypothesized the manner that heifers achieve puberty may indicate their future reproductive longevity. Heifers with discontinued or delayed cyclicity during puberty attainment may have irregular reproductive cycles, anovulation, and infertility in their first breeding season contributing to a shorter reproductive lifespan. Therefore, plasma progesterone (P4) was measured from weaning to breeding on 611 heifers born 2012–2017 and four pubertal classifications were identified: (1) Early; P4 ≥ 1 ng/ml < March 12 with continued cyclicity, (2) Typical; P4 ≥ 1 ng/ml ≥ March 12 with continued cyclicity, (3) Start-Stop; P4 ≥ 1 ng/ml but discontinued cyclicity, and (4) Non-Cycling; no P4 ≥ 1 ng/ml. Historical herd records indicated that 25% of heifers achieved puberty prior to March 12th in the 10 years prior to the study. Start-Stop and Non-Cycling yearling heifers were lighter indicating reduced growth and reproductive maturity traits compared with Early/Typical heifers. In addition, Non-Cycling/Start-Stop heifers were less responsive to prostaglandin F2 alpha (PGF2α) to initiate estrous behavior and ovulation to be artificially inseminated. Non-Cycling heifers had fewer reproductive tract score-5 and reduced numbers of calves born in the first 21-days-of-calving during their first breeding season. Within the Start-Stop classification, 50% of heifers reinitiated cyclicity with growth traits and reproductive parameters that were similar to heifers in the Early/Typical classification while those that remained non-cyclic were more similar to heifers in the Non-Cycling group. Thus, heifers with discontinued cyclicity or no cyclicity during puberty attainment had delayed reproductive maturity resulting in subfertility and potentially a shorter reproductive lifespan.
Trust your gut: vagal nerve stimulation in humans improves reinforcement learning
Authors: Weber Immo , Niehaus Hauke , Krause Kristina , Molitor Lena , Peper Martin , Schmidt Laura , Hakel Lukas , Timmermann Lars , Menzler Katja , Knake Susanne , Oehrn Carina R
Published: March 2021

Whereas the effect of vagal nerve stimulation on emotional states is well established, its effect on cognitive functions is still unclear. Recent rodent studies show that vagal activation enhances reinforcement learning and neuronal dopamine release. The influence of vagal nerve stimulation on reinforcement learning in humans is still unknown. Here, we studied the effect of transcutaneous vagal nerve stimulation on reinforcement learning in eight long-standing seizure-free epilepsy patients, using a well-established forced-choice reward-based paradigm in a cross-sectional, within-subject study design. We investigated vagal nerve stimulation effects on overall accuracy using non-parametric cluster-based permutation tests. Furthermore, we modelled sub-components of the decision process using drift-diffusion modelling. We found higher accuracies in the vagal nerve stimulation condition compared to sham stimulation. Modelling suggests a stimulation-dependent increase in reward sensitivity and shift of accuracy-speed trade-offs towards maximizing rewards. Moreover, vagal nerve stimulation was associated with increased non-decision times suggesting enhanced sensory or attentional processes. No differences of starting bias were detected for both conditions. Accuracies in the extinction phase were higher in later trials of the vagal nerve stimulation condition, suggesting a perseverative effect compared to sham. Together, our results provide first evidence of causal vagal influence on human reinforcement learning and might have clinical implications for the usage of vagal stimulation in learning deficiency.
Development and Validation of Two New Methods for the Determination of Rilmenidine in Bulk and Pharmaceutical Preparation
Authors: Özdemir Elif , Ergin Kizilçay Gamze , Ertürk Toker Sıdıka
Published: March 2021

In the present study, two new methods were developed and validated for the determination of rilmenidine in bulk and pharmaceutical preparation. Both methods are based on a derivatization reaction using 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl) as a fluorogenic substance. The drug reagent derivatives were formed by the reaction of rilmenidine with NBD-Cl at pH 9.0 at 70°C for 40 min. The reaction mixtures were analyzed by spectrofluorimetry in the first method and high performance liquid chromatography (HPLC) in the second method. Derivatives were determined at λex 493 nm and at λem 536 nm in the spectrofluorimetric method. The separation was performed place on a Phenomenex, C18 column (250 × 4.6 mm, 5 μm i.d) using a mobile phase comprising 0.2% formic acid and acetonitrile gradient elution mode in the HPLC method. Analytes were detected by a fluorescence detector at the same wavelength. The methods were validated for limit of quantitation, linearity, robustness, recovery, limit of detection, precision and accuracy. Calibration curves for the first and second methods were found to be linear in the range of 2.0–12.0 and 250–2000 ng/mL, respectively. Detection limits for the spectrofluorimetric and HPLC methods were calculated as 0.16 and 18.28 ng/mL, respectively. The validated methods were applied successfully to the determination of rilmenidine in bulk and pharmaceutical preparation.
Impact of Systemic Corticosteroids on Mortality in Older Adults With Critical COVID-19 Pneumonia
Authors: Piniella-Ruiz Esther , Bellver-Álvarez María Teresa , Mestre-Gómez Beatriz , Escolano-Fernández Belén , Vinat-Prado Sara , Cabezas-Olea Rita , Acedo-Gutiérrez María Soledad , Akasbi-Montalvo Mirian , Ryan-Murua Pablo , Bustamante-Fermosel Ana , Muñoz-Rivas Nuria , Santamaría-García Carmen , Pardo-Guimerá Virginia , Ulla-Anés Mariano , Franco-Moreno Anabel , Torres-Macho Juan
Published: March 2021

Background

The most susceptible population group to critical and fatal coronavirus disease 2019 (COVID-19) is older adults. In severe acute respiratory syndrome coronavirus 2 infection, the host immune response is thought to play a key role in the pathophysiological effects of lung damage. Therefore, corticosteroid therapy could modulate inflammation-mediated pulmonary injury and thereby reduce progression to severe respiratory failure and death. The aim of this study was to analyze the safety and clinical efficacy of corticosteroid therapy in older adults with severe COVID-19 pneumonia.

Method

We reviewed the clinical records of confirmed COVID-19 patients aged 75 years or older admitted to our hospital over a 3-month period (March 1–May 31, 2020). A total of 143 patients were included in the study cohort. From 2 April, 2020, in accordance with World Health Organization guidance on COVID-19, our hospital protocol added corticosteroid for COVID-19 treatment. We compared in-hospital mortality among patients with critical COVID-19 who received corticosteroids therapy and those who did not.

Results

In total, 88 patients (61.5%) were treated with corticosteroids, and 55 patients (38.4%) were not. Both groups were similar in baseline characteristics. The median age was 85 years (interquartile range: 82–89), and 61.5% (88/143) were male. In-hospital mortality was lower in the corticosteroid group (68.2%) compared with patients in the noncorticosteroid group (81.8%). Treatment with corticosteroids was an independent survival factor (hazard ratio: 0.61; 95% CI: 0.41–0.93; p = .006).

Conclusions

In critically ill older adults with COVID-19 pneumonia, the use of corticosteroid treatment resulted in lower mortality without severe adverse events.
Impaired Cognitive Flexibility Induced by Chronic Cerebral Hypoperfusion in the 5XFAD Transgenic Mouse Model of Mixed Dementia
Authors: Kim Min-Soo , Bang Jihye , Kim Bu-Yeo , Jeon Won Kyung
Published: March 2021

Cerebrovascular lesions are widely prevalent in patients with Alzheimer’s disease (AD), but their relationship to the pathophysiology of AD remains poorly understood. An improved understanding of the interaction of cerebrovascular damage with AD is crucial for the development of therapeutic approaches. Herein, we investigated the effects of chronic cerebral hypoperfusion (CCH) in a 5XFAD transgenic (Tg) mouse model of AD. We established CCH conditions in both Tg and non-Tg mice by inducing unilateral common carotid artery occlusion (UCCAO). Cognitive performance in mice was evaluated, and their brain tissue was examined for amyloid-beta (Aβ) pathology to elucidate possible mechanisms. We found that UCCAO-operated Tg mice showed impaired cognitive flexibility in the reversal phase of the hidden-platform water maze task compared to sham-operated Tg mice. Interestingly, UCCAO-operated Tg mice used fewer spatial cognitive strategies than sham-operated Tg mice during reversal learning. These cognitive deficits were accompanied by increased Aβ plaque burden and Aβ42 levels in the hippocampus and prefrontal cortex, 2 regions that play essential roles in the regulation of cognitive flexibility. Furthermore, changes in cognitive flexibility are strongly correlated with the expression levels of enzymes related to Aβ clearance, such as neprilysin and insulin-degrading enzymes. These findings suggest that, in 5XFAD mice, impaired cognitive flexibility is related to CCH, and that Aβ clearance might be involved in this process.
Serum and Cervicovaginal Fluid Antibody Profiling in Herpes Simplex Virus–Seronegative Recipients of the HSV529 Vaccine
Authors: Wang Kening , Dropulic Lesia , Bozekowski Joel , Pietz Harlan L , Jegaskanda Sinthujan , Dowdell Kennichi , Vogel Joshua S , Garabedian Doreen , Oestreich Makinna , Nguyen Hanh , Ali Mir A , Lumbard Keith , Hunsberger Sally , Reifert Jack , Haynes Winston A , Sawyer Jaymie R , Shon John C , Daugherty Patrick S , Cohen Jeffrey I
Published: March 2021

Previous herpes simplex virus type 2 (HSV-2) vaccines have not prevented genital herpes. Concerns have been raised about the choice of antigen, the type of antibody induced by the vaccine, and whether antibody is present in the genital tract where infection occurs. We reported results of a trial of an HSV-2 replication-defective vaccine, HSV529, that induced serum neutralizing antibody responses in 78% of HSV-1–/HSV-2– vaccine recipients. Here we show that HSV-1–/HSV-2– vaccine recipients developed antibodies to epitopes of several viral proteins; however, fewer antibody epitopes were detected in vaccine recipients compared with naturally infected persons. HSV529 induced antibodies that mediated HSV-2–specific natural killer (NK) cell activation. Depletion of glycoprotein D (gD)–binding antibody from sera reduced neutralizing titers by 62% and NK cell activation by 81%. HSV-2 gD antibody was detected in cervicovaginal fluid at about one-third the level of that in serum. A vaccine that induces potent serum antibodies transported to the genital tract might reduce HSV genital infection.
Are We Really Painting the Devil on the Walls? Polarization and Its Drivers in Sub-Saharan Africa in the Past Two Decades
Authors: Clementi Fabio , Fabiani Michele , Molini Vasco , Zizzamia Rocco
Published: March 2021

The development path of Sub-Saharan Africa (SSA) over the past two decades has been characterized by sluggish poverty reduction occurring alongside robust economic growth. Applying polarization measures to comparable survey data from 24 SSA countries, we find that there has been a generalizable increase in polarization over the past two decades—and in particular, an increased concentration of households in the lower tail of the welfare distribution of SSA countries. The polarization process is further analyzed by identifying the main drivers and singling out the effect of different covariates at different points in the consumption distribution. This investigation reveals that the drivers of polarization are relatively similar across SSA: demographic, urban/rural, regional variables and access to basic infrastructure are found to be the most important drivers of polarization in many countries.