bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantum Steenrod squares and the equivariant pair-of-pants in symplectic cohomology
Authors: Wilkins Nicholas
Published: April 2021

We relate the quantum Steenrod square to Seidel’s equivariant pair-of-pants product for open convex symplectic manifolds that are either monotone or exact, using an equivariant version of the PSS isomorphism. We define continuation maps between different Hamiltonians in [Formula: see text]-equivariant Floer cohomology, and prove expected properties of them. We prove a symplectic Cartan relation for the equivariant pair-of-pants product, pointing out the difficulties in stating it. We give a nonvanishing result for the equivariant pair-of-pants product for some elements of [Formula: see text]. We finish by calculating the symplectic square for the negative line bundles [Formula: see text], proving an equivariant version of a result due to Ritter.
Existence and global exponential stability of equilibrium for impulsive neural network models with generalized piecewise constant delay
Authors: Chiu Kuo-Shou
Published: April 2021

In this paper, we investigate the models of the impulsive cellular neural network with generalized constant piecewise delay (IDEGPCD). To guarantee the existence, uniqueness and global exponential stability of the equilibrium state, several new adequate conditions are obtained, which extend the results of the previous literature. The method is based on utilizing Banach’s fixed point theorem and a new IDEGPCD’s Gronwall inequality. The criteria given are easy to check and when the impulsive effects do not affect, the results can be extracted from those of the non-impulsive systems. Typical numerical simulation examples are used to show the validity and effectiveness of the proposed results. We end the paper with a brief conclusion.
Streets, Sidewalks and COVID-19: Reimaging New York City’s Public Realm as a Tool for Crisis Management
Authors: Finn Donovan
Published: April 2021

The 2020 COVID-19 outbreak has caused significant disruption to economic and social systems. New York City, as the United States’ largest city and among the nation’s most densely populated, was an early epicenter of the crisis. Modifications to the design, planning and operations of the city’s public realm have been important components of the city’s overall response to mitigate the effects of the pandemic while also facilitating economic recovery and providing social, educational, and recreational opportunities for city residents. This commentary provides an overview of New York City’s urban design responses to COVID-19, highlighting some of the successes and limitations of the city’s programs. We conclude by arguing that, in order to be effective, short-term crisis response efforts such as these must eventually be turned into government policies that not only address immediate urgent crises but also begin to facilitate durable long-term recovery and address longstanding systemic inequalities and vulnerabilities.
Unsupervised Anomaly Detectors to Detect Intrusions in the Current Threat Landscape
Authors: Zoppi Tommaso , Ceccarelli Andrea , Capecchi Tommaso , Bondavalli Andrea
Published: April 2021

Anomaly detection aims at identifying unexpected fluctuations in the expected behavior of a given system. It is acknowledged as a reliable answer to the identification of zero-day attacks to such extent, several ML algorithms that suit for binary classification have been proposed throughout years. However, the experimental comparison of a wide pool of unsupervised algorithms for anomaly-based intrusion detection against a comprehensive set of attacks datasets was not investigated yet. To fill such gap, we exercise 17 unsupervised anomaly detection algorithms on 11 attack datasets. Results allow elaborating on a wide range of arguments, from the behavior of the individual algorithm to the suitability of the datasets to anomaly detection. We conclude that algorithms as Isolation Forests, One-Class Support Vector Machines, and Self-Organizing Maps are more effective than their counterparts for intrusion detection, while clustering algorithms represent a good alternative due to their low computational complexity. Further, we detail how attacks with unstable, distributed, or non-repeatable behavior such as Fuzzing, Worms, and Botnets are more difficult to detect. Ultimately, we digress on capabilities of algorithms in detecting anomalies generated by a wide pool of unknown attacks, showing that achieved metric scores do not vary with respect to identifying single attacks.
Modeling Temporal Patterns of Cyberbullying Detection with Hierarchical Attention Networks
Authors: Cheng Lu , Guo Ruocheng , Silva Yasin N. , Hall Deborah , Liu Huan
Published: April 2021

Cyberbullying is rapidly becoming one of the most serious online risks for adolescents. This has motivated work on machine learning methods to automate the process of cyberbullying detection, which have so far mostly viewed cyberbullying as one-off incidents that occur at a single point in time. Comparatively less is known about how cyberbullying behavior occurs and evolves over time. This oversight highlights a crucial open challenge for cyberbullying-related research, given that cyberbullying is typically defined as intentional acts of aggression via electronic communication that occur
repeatedly
and
persistently
. In this article, we center our discussion on the challenge of modeling temporal patterns of cyberbullying behavior. Specifically, we investigate how temporal information within a social media session, which has an inherently hierarchical structure (e.g., words form a comment and comments form a session), can be leveraged to facilitate cyberbullying detection. Recent findings from interdisciplinary research suggest that the temporal characteristics of bullying sessions differ from those of non-bullying sessions and that the temporal information from users’ comments can improve cyberbullying detection. The proposed framework consists of three distinctive features: (1) a hierarchical structure that reflects how a social media session is formed in a bottom-up manner; (2) attention mechanisms applied at the word- and comment-level to differentiate the contributions of words and comments to the representation of a social media session; and (3) the incorporation of temporal features in modeling cyberbullying behavior at the comment-level. Quantitative and qualitative evaluations are conducted on a real-world dataset collected from Instagram, the social networking site with the highest percentage of users reporting cyberbullying experiences. Results from empirical evaluations show the significance of the proposed methods, which are tailored to capture temporal patterns of cyberbullying detection.
Study on Spinel Iron-Based Chalcogenides as Bi-Functional Cathode Catalysts for Li-O2Battery
Authors: Wang Yanqing , Ding Shengqi , Li Jingjuan , Wu Liang , Jiang Zhidong , Ma Zi-Feng , Yuan Xianxia
Published: April 2021

Spinel iron-based chalcogenides of Fe3O4and Fe3S4are successfully synthesized via a MOF-based calcination and facile one-step hydrothermal method, respectively, and their electrochemical performance as cathode catalysts of Li-O2battery is comparatively investigated. The results reveal that the battery with Fe3S4has better performance including higher discharge capacity and voltage, lower overpotential, higher energy conversion efficiency and longer lifespan. The performance difference of Fe3O4and Fe3S4is analyzed and discussed with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and density functional theory (DFT) calculations.
An Electrochemical Study of the Effect of High Salt Concentration on Uniform Corrosion of Carbon Steel in Aqueous CO2 Solutions
Authors: Madani Sani Fazlollah , Brown Bruce , Nesic Srdjan
Published: April 2021

Uniform

C

O

2

corrosion of carbon steel facilities is often a major problem when handling produced water in the oil and gas fields. High amounts of dissolved salts are often present in produced water. A limited number of research studies has been conducted on the effect of salt concentration on uniform

C

O

2

corrosion. In this study, the effect of NaCl concentration on uniform

C

O

2

corrosion of X65 carbon steel was investigated in

C

O

2

saturated aqueous solutions using a rotating cylinder system at 30 °C, autogenous pH, and 1 bar total pressure in an NaCl concentration range of 0‒4.27 molality (m) (0‒20 wt.%). With increasing NaCl concentration, the corrosion rate increased sharply and reached its maximum value at ∼0.17 m (1 wt.%) NaCl and then decreased with further increase in NaCl concentration. The observed trend in the corrosion rate with increasing NaCl concentration was primarily a consequence of the change in the cathodic limiting current density, which was the main factor controlling the rate of the overall corrosion process. The additional factor was the change in the rate of the anodic reaction with salt concentration.
Comparative Study on the Macroscopic and Microscopic Properties of UHPC Mixed with Limestone Powder and Slag Powder
Authors: Yang Menghui , He Zhen , Chen Xia , Li Mingxia , Peng Ziling
Published: April 2021

This paper explores the development laws of the fluidity, compressive strength, and autogenous shrinkage of ultrahigh performance cement (UHPC) mixed with limestone powder (LP) and highly active ground slag powder (SP). A microscopic analysis was conducted on the hydration products and pore structures. Through quantitative research on the packing density and fractal dimension of particles in different systems, the relationship between particle characteristics and UHPC properties was established. As a result, the packing densities of the UHPC mixed solely with LP (binary system) and UHPC mixed with LP and silica fume (ternary system) are higher than those of UHPC mixed with the same amount of SP and the benchmark UHPC system; fractal dimension of particle size distribution is closely related to packing density. The LP-cement-silica fume ternary system was lowly hydrated, but it has a good grain composition and high density of slurry, which improved the compressive strength of UHPC. The compressive strength of UHPC mixed with 50% LP witnessed a more obvious decline than that of the ternary system and the one with the same amount of SP. The reason lies in the decrease in slurry due to a lack of sufficient active constituents, and the hydration products were far from enough to fill the pores in the system. LP can also inhibit autogenous shrinkage to the greatest degree for the LP-mixed binary system performed best in such inhibition.
Deep Learning Based on Residual Networks for Automatic Sorting of Bananas
Authors: Helwan Abdulkader , Sallam Ma’aitah Mohammad Khaleel , Abiyev Rahib H. , Uzelaltinbulat Selin , Sonyel Bengi
Published: April 2021

This study presents the design of an intelligent system based on deep learning for grading fruits. For this purpose, the recent residual learning-based network “ResNet-50” is designed to sort out fruits, particularly bananas into healthy or defective classes. The design of the system is implemented by using transfer learning that uses the stored knowledge of the deep structure. Datasets of bananas have been collected for the implementation of the deep structure. The simulation results of the designed system have shown a great generalization capability when tested on test (unseen) banana images and obtained high accuracy of 99%. The simulation results of the designed residual learning-based system are compared with the results of other systems used for grading the bananas. Comparative results indicate the efficiency of the designed system. The developed system can be used in food processing industry, in real-life applications where the accuracy, cost, and speed of the intelligent system will enhance the production rate and allow meeting the demand of consumers. The system can replace or assist human operators who can exert their energy on the selection of fruits.
ANPrAod: Identify Antioxidant Proteins by Fusing Amino Acid Clustering Strategy and
N
-Peptide Combination
Authors: Xi Qilemuge , Wang Hao , Yi Liuxi , Zhou Jian , Liang Yuchao , Zhao Xiaoqing , Zuo Yongchun
Published: April 2021

Antioxidant proteins perform significant functions in disease control and delaying aging which can prevent free radicals from damaging organisms. Accurate identification of antioxidant proteins has important implications for the development of new drugs and the treatment of related diseases, as they play a critical role in the control or prevention of cancer and aging-related conditions. Since experimental identification techniques are time-consuming and expensive, many computational methods have been proposed to identify antioxidant proteins. Although the accuracy of these methods is acceptable, there are still some challenges. In this study, we developed a computational model called ANPrAod to identify antioxidant proteins based on a support vector machine. In order to eliminate potential redundant features and improve prediction accuracy, 673 amino acid reduction alphabets were calculated by us to find the optimal feature representation scheme. The final model could produce an overall accuracy of 87.53% with the ROC of 0.7266 in five-fold cross-validation, which was better than the existing methods. The results of the independent dataset also demonstrated the excellent robustness and reliability of ANPrAod, which could be a promising tool for antioxidant protein identification and contribute to hypothesis-driven experimental design.
Linear Regression Algorithm against Device Diversity for the WLAN Indoor Localization System
Authors: Zhang Liye , Meng Xiaoliang , Fang Chao
Published: April 2021

Recent years have witnessed a growing interest in using WLAN fingerprint‐based methods for the indoor localization system because of their cost‐effectiveness and availability compared to other localization systems. In this system, the received signal strength (RSS) values are measured as the fingerprint from the access points (AP) at each reference point (RP) in the offline phase. However, signal strength variations across diverse devices become a major problem in this system, especially in the crowdsourcing‐based localization system. In this paper, the device diversity problem and the adverse effects caused by this problem are analyzed firstly. Then, the intrinsic relationship between different RSS values collected by different devices is mined by the linear regression (LR) algorithm. Based on the analysis, the LR algorithm is proposed to create a unique radio map in the offline phase and precisely estimate the user’s location in the online phase. After applying the LR algorithm in the crowdsourcing systems, the device diversity problem is solved effectively. Finally, we verify the LR algorithm using the theoretical study of the probability of error detection. Experimental results in a typical office building show that the proposed method results in a higher reliability and localization accuracy.
A Comparative Study of the Micropore Structure between the Transitional and Marine Shales in China
Authors: Jiao Pengfei , Yao Genshun , Zhou Shangwen , Yu Zhe , Wang Shiluo
Published: April 2021

To compare the micropore structure of marine-continental transitional shale with marine shale, organic geochemical, field emission scanning electron microscopy, and low-temperature nitrogen adsorption experiments were conducted on shale samples from the Shanxi Formation in the eastern Ordos Basin and the Longmaxi Formation in the southern Sichuan Basin. The results show that Shanxi Formation shale has a smaller specific surface area and pore volume than Longmaxi Formation shale; therefore, the transitional shales fail to provide sufficient pore spaces for the effective storage and preservation of natural gas. Both the transitional and marine shales are in an overmature stage with high total organic carbon content, but they differ considerably in pore types and development degrees. Inorganic pores and fractures are dominantly developed in transitional shales, such as intragranular pores and clay mineral interlayer fractures, while organic nanopores are rarely developed. In contrast, organic pores are the dominant pore type in the marine shales and inorganic pores are rarely observed. The fractal analysis also shows that pore structure complexity and heterogeneity are quite different. These differences were related to different organic types, i.e., type I of marine shale and type III of transitional shale. Marine Longmaxi shale has experienced liquid hydrocarbon cracking, gas generation, and pore-forming processes, providing good conditions for natural gas to be preserved. However, during the evolution of transitional Shanxi shale, gas cannot be effectively preserved due to the lack of the above evolution processes, leading to the poor gas-bearing property. The detailed comparison of the micropore structure between the transitional and marine shales is of great importance for the future exploitation of marine-continental transitional shale gas in China.
Autophagy Is Required for Hepatic Differentiation of Hepatic Progenitor Cells via Wnt Signaling Pathway
Authors: Zeng Jianxing , Jing Yingying , Wu Qionglan , Zeng Jinhua , Wei Lixin , Liu Jingfeng
Published: April 2021

The molecular mechanisms regulating differentiation of hepatic progenitor cells (HPCs), which play pivotal roles in liver regeneration and development, remain obscure. Autophagy and Wnt signaling pathways regulate the development and differentiation of stem cells in various organs. However, the roles of autophagy and Wnt signaling pathways in hepatic differentiation of HPCs are not well understood. Here, we describe the effects of autophagy and Wnt signaling pathways during hepatic differentiation of HPCs. We used a well‐established rat hepatic progenitor cell line called WB‐F344, which was treated with differentiation medium to promote differentiation of WB‐F344 cells along the hepatic phenotype. Firstly, autophagy was highly activated in HPCs and gradually decreased during hepatic differentiation of HPCs. Induction of autophagy by rapamycin or starvation suppressed hepatic differentiation of HPCs. Secondly, Wnt3a signaling pathway was downregulated, and Wnt5a signaling pathway was upregulated in hepatic differentiation of HPCs. At last, Wnt3a signaling pathway was enhanced, and Wnt5a signaling pathway was inhibited by activation of autophagy during hepatic differentiation of HPCs. In summary, these results demonstrate that autophagy regulates hepatic differentiation of hepatic progenitor cells through Wnt signaling pathway.
Research on New Types of Suspension Vibration Reduction Systems (SVRSs) with Geometric Nonlinear Damping
Authors: Yang Meng , Zhang Jian , Luo Xingjiu
Published: April 2021

Firstly, this paper puts forward two new types of suspension vibration reduction systems (SVRSs) with geometric nonlinear damping based on general SVRS (GSVRS), which only has geometric nonlinear stiffness. Secondly, it derives the motion differential equations for the two new types of SVRS, respectively, and discusses the similarities and differences among the two types and GSVRS through the comparison of motion differential equations. Then, it conducts dimensionless processing of the motion differential equations for the two new types of SVRS and carries out a comparative study on the vibration isolation performance of the two types of SVRS under impact excitation and random excitation, respectively. At last, it performs the optimal computation of the chosen new type of SVRS through the ergodic optimization method and studies the influence rule of SVRS parameters on vibration isolation performance so as to realize the optimization of vibration isolation performance.
An Adolescent with Transient Hyperthyroxinemia after Blunt Trauma to Head and Neck
Authors: Romijn Michelle , Geeraedts Leo M. G. , Verbeke Jonathan I. M. L. , Finken Martijn J. J.
Published: April 2021

Background. Thyroid storm is a well-known complication of surgical procedures in the lower neck, but is rare after a blunt neck trauma. The cases described previously have mainly focussed on adults with pre-existent thyroid disease. In this case report, we describe the disease course of a previously healthy adolescent who had asymptomatic hyperthyroxinemia after a blunt trauma of the jaw and neck. Case Presentation. A 17-year-old girl presented at our emergency department after she fell on her head while roller blading. On physical examination, among other injuries, she had a swelling in the lower neck, which appeared to involve the thyroid gland. Subsequent laboratory analysis was indicative of primary hyperthyroxinemia, with a free T4 of 59 pmol/L (reference range: 12–22) and a TSH of 0.46 mU/L (reference range: 0.5–4.3), but the patient had no symptoms fitting with this. Four weeks after the initial presentation, the patient reported only complaints regarding tenderness in the jaw and neck region. She was no longer hyperthyroidic on biochemical evaluation (with a free T4 level of 15.6 pmol/L and a TSH level of 0.33 mU/L), and antibodies against thyroid peroxidase or TSH receptor were not present. Conclusions. This case might indicate that hyperthyroxinemia following a neck trauma may go unnoticed if hyperthyroid symptoms are mild or absent and thyroid function tests are not performed.
Rational Type Fuzzy-Contraction Results in Fuzzy Metric Spaces with an Application
Authors: Rehman Saif Ur , Chinram Ronnason , Boonpok Chawalit
Published: April 2021

This paper aims to introduce the new concept of rational type fuzzy-contraction mappings in fuzzy metric spaces. We prove some fixed point results under the rational type fuzzy-contraction conditions in fuzzy metric spaces with illustrative examples to support our results. This new concept will play a very important role in the theory of fuzzy fixed point results and can be generalized for different contractive type mappings in the context of fuzzy metric spaces. Moreover, we present an application of a nonlinear integral type equation to get the existing result for a unique solution to support our work.
The Relationship between Achievement Motivation and Job Performance among Chinese Physicians: A Conditional Process Analysis
Authors: Guo Botang , Qiang Binbin , Zhou Jiawei , Yang Xiuxian , Qiu Xiaohui , Qiao Zhengxue , Yang Yanjie , Cao Depin
Published: April 2021

Background. To explore the relationship between achievement motivation and job performance among physicians, this study investigated the impacts of different personality traits on job performance among the physicians. Methods. This cross‐sectional study was conducted in 2017 and 1,523 physicians from eight tertiary grade A hospitals in Harbin, China. The type of data collected included the achievement motivation of the physicians, job performance, organizational commitment, personality traits, and other demographic variables. To assess and compare the demographic data, independent t‐test and ANOVA were applied. Further, Pearson correlation coefficients were used to evaluate the correlation among the variables. Moderated mediation analysis was performed to test the correlation among the job performance, achievement motivation, organizational commitment, neuroticism, extraversion, openness, agreeableness, and conscientiousness. Results. Achievement motivation directly influences job performance and organizational commitment partially mediates the direct effects of achievement motivation on job performance. Additionally, our findings demonstrated that agreeableness and conscientiousness moderate the strength of the relationships between achievement motivation and job performance mediated by organizational commitment. Conclusion. We propose that hospital managers should pay attention to the personal growth of the physicians and improve their organizational commitment via creating a positive working climate and training for career planning and education. Moreover, managers should identify conscientiousness and agreeableness individuals and increase their responsibilities geared towards improving the performance of the organization.
Clinical Efficacy and Safety of Zoledronic Acid Combined with PVP/PKP in the Treatment of Osteoporotic Vertebral Compression Fracture: A Systematic Review and Meta‐Analysis of Randomized Controlled Trials
Authors: Sun Yan , Ma Haoning , Yang Feng , Tang Xiangsheng , Yi Ping , Tan Mingsheng
Published: April 2021

Objective. We conducted this meta‐analysis to provide better evidence of the efficacy and safety of zoledronic acid (ZA) combined with percutaneous vertebroplasty/kyphoplasty (PVP/PKP) on osteoporotic vertebral compression fracture (OVCF) and proposed a protocol for its application in clinical practice. Methods. All randomized controlled trials (RCTs) of ZA combined with PVP or PKP compared to individual PVP/PKP for the management of patients with OVCFs were included in this study. Electronic database searches were conducted from database inception to November 2020, including the Cochrane Library, PubMed, Web of Science, and Embase. The pooled data were analyzed using RevMan 5.3 software. Results. Seven RCTs with 929 subjects were finally included. All included studies reported visual analog scores (VAS), and no statistically significant differences were identified at follow‐ups of 3 d and 1 w (P > 0.05). In contrast, significant differences were observed at the 1 mo, 3 mo, 6 mo, and 12 mo follow‐ups (P < 0.05). Two trials reported the Cobb angle and vertebral body height (VBH), including 182 subjects without significant differences at the 12 mo follow‐up (P > 0.05). In addition, significant differences in the bone mineral density (BMD), β‐isomerized C‐terminal telopeptide of type I collagen (β‐CTX), N‐terminal propeptide of type I collagen (PINP), and N‐terminal molecular fragment (N‐MID) levels were observed between the two groups (P < 0.05). All trials reported side effects. Significant differences in recurrent fractures, fever, flu‐like symptoms, and arthralgia or myalgia were identified (P < 0.05); however, no significant difference in postoperative leakage was detected (P > 0.05). Conclusion. Compared to PVP/PKP alone, an additional ZA injection had advantages of long‐term analgesic effects with improved bone metabolism indexes. Moreover, combination therapy significantly prevented complications and drug reactions were well tolerated. Overall, this systematic review revealed that ZA combined with PVP/PKP was an effective, safe, and comprehensive therapy for patients with OVCFs.
Influence of Electric Current and Magnetic Flow on Firing Patterns of Pre-Bötzinger Complex Model
Authors: Ji Wenchao , Liu Moutian , Duan Lixia
Published: April 2021

The dynamics of neuronal firing activity is vital for understanding the pathological respiratory rhythm. Studies on electrophysiology show that the magnetic flow is an essential factor that modulates the firing activities of neurons. By adding the magnetic flow to Butera’s neuron model, we investigate how the electric current and magnetic flow influence neuronal activities under certain parametric restrictions. Using fast-slow decomposition and bifurcation analysis, we show that the variation of external electric current and magnetic flow leads to the change of the bistable structure of the system and hence results in the switch of neuronal firing pattern from one type to another.
Antibacterial Effects of Erbium Chromium Laser along with/without Silver Nanoparticles in Root Canals Infected by Enterococcus faecalis
Authors: Hendi Seyedeh Sareh , Amiri Negin , Poormoradi Banafsheh , Alikhani Mohammad Yousef , Afshar Saeid , Farhadian Maryam
Published: April 2021

This study investigates the antibacterial effects of erbium chromium laser at 2780 nm, silver nanoparticles, and erbium chromium along with silver nanoparticles on Enterococcus faecalis in comparison with sodium hypochlorite. In the present study, 90 extracted human single-rooted teeth were selected and standardized to a length of 15 mm. The canals were prepared by V-taper Gold rotary files and then incubated with E. faecalis for 21 days. The samples were divided into four experimental groups including hypochlorite sodium, silver nanoparticle, erbium chromium laser, and erbium chromium laser along with silver nanoparticle groups. Results showed that there was a significant reduction in colony count for all groups after interventions. Moreover, there was a significant reduction in the colony count for sodium hypochlorite group in comparison with another groups, and this group showed the highest reduction of colony count. There was a significant difference between silver nanoparticles and erbium chromium laser groups in colony count. According to the results, the silver nanoparticles offered strong antibacterial effects on E. faecalis and therefore can decrease bacterial colonies, while the use of the laser, despite the reduction of the bacterial colony, could not be sufficiently used for disinfection of root canal system.
Analysis of Vibration Characteristics of Centrifugal Pump Mechanical Seal under Wear and Damage Degree
Authors: Luo Yin , Zhang Wenqi , Fan Yakun , Han Yuejiang , Li Weimin , Acheaw Emmanuel
Published: April 2021

Mechanical seal is a kind of shaft sealing equipment. Face wear is one of the main causes of mechanical seal failure. Mechanical seal condition is also related to the reduction of energy consumption and carbon emission. Therefore, we need to detect the centrifugal pump seal condition. At present, vibration signal is a common method for fault monitoring and diagnosis of centrifugal pump. In this paper, the vibration signal under the condition of damaged centrifugal pump seal is measured by studying the characteristics of vibration signal after the end face damage of centrifugal pump. Statistical indicators such as RMS and kurtosis were taken to analyze the average energy and shock wave energy of vibration signal. The time‐frequency characteristics of vibration signal are analyzed by frequency spectrum. The results show that there are a large extent variation of vibration amplitude in the direction of base and axis and a weak variation of vibration amplitude in the direction of radial and vertical. With the increasing of flow rate, the RMS of vibration signal falls at first, then keeps steady, and mounts at last when the flow rate is over the design flow rate. It can be shown from the time‐frequency spectrum that there is a shock wave and pause signals caused by the shock wave, which are reflected by the higher frequency band components of the vibration signal that can provide a reference to the diagnosis of the occurrence of damaged mechanical seal. From the analysis, the energy of vibration signal is related to the running condition, we can find that the occurrence of mechanical seal wear makes the centrifugal pump to produce high‐frequency vibration signal, and the axial vibration is the strongest and the instability in the fluid makes the vibration signal produce high amplitude characteristics. Analyzing the vibration signal characteristics of centrifugal pumps with damaged mechanical seal is of great significance to find the mechanical seal failure of the centrifugal pumps and adjust the operating parameters.
Continuous Inhibition of Sonic Hedgehog Signaling Leads to Differentiation of Human-Induced Pluripotent Stem Cells into Functional Insulin-Producing β Cells
Authors: Lee Song , Joo Jae Hyun , Oh Ju Yun , Seo Eun Ha , Kim Yang Hee , Jun Eunsung , Shim In Kyong , Kim Song Cheol
Published: April 2021

Human-induced pluripotent stem cell- (iPSC-) derived insulin-producing cells (IPCs) can be used for islet cell transplantation into type 1 diabetic patients and as patient-specific cells for the development of novel antidiabetic drugs. However, a method is needed to generate functional IPCs from iPSCs and simplify the protocol. We compared combinations of small molecules that could induce the differentiation of cells into a definitive endoderm and preferentially into islet precursor cells. When generated using an optimal combination of small molecules, IPCs secreted insulin in response to glucose stimulation. We constructed spheroid IPCs and optimized the culture and maturation conditions. Quantitative PCR revealed that the expression of definitive endoderm-specific markers differed depending on the combination of the small molecules. The small molecule, N-[(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)methylene]-4-(phenylmethyl)-1-piperazinamine, induced the differentiation of cells into functional IPCs by inhibiting Sonic hedgehog signaling. Images of the 2D culture showed that IPCs formed spheroids from day 5 and continuously secreted insulin. We developed a simple differentiation method using small molecules that produced functional IPCs that responded to glucose stimulation within a relatively short period. We posit that this method along with further refinement of the differentiation process can be applied to culture IPCs that can be used in clinical trials.
Performance of Polypropylene Fiber‐Reinforced Solidified Soil
Authors: Hu Cheng , Weng Xingzhong , Liu Cong , Jiang Le , Liu Junzhong , Li Wenlei
Published: April 2021

Urgent repair and construction of airstrips is a research hotspot in global airport engineering. Selecting the proper structural materials is a key component of the airstrip repair process. First, with unconfined compressive strength and splitting tensile strength, the fiber length and content of polypropylene (PP) fiber‐reinforced solidified soil were optimized. Then, using a scanning electron microscope, the reinforcing mechanism of PP fiber on soil and the influence mechanism of fiber parameters on fiber‐reinforced soil were discussed and analyzed. Lastly, a full‐scale test section was paved, on which static and dynamic loading tests were performed to verify the carrying capacity and deformation characteristics of the full‐scale test section. The above research provides a theoretical foundation and data support for the urgent repair and construction of airstrip. Results indicate that PP fiber with length of 12 mm and fiber content of 0.3% has optimal performance and economic cost. The reinforcing mechanism of fiber‐reinforced soil can be summarized to be the effect of a one‐dimensional lacing wire and the effect of a three‐dimensional network structure. Fibers show two failure modes of pull‐out and tensile failure. After 20000 dynamic loading cycles, the stress at the bottom of each structural section varies less, the graded plastic deformation is stable, and the cumulative plastic deformations of the fiber‐reinforced soil base, solidified soil base, and cemented soil base pavement structures are 0.83 mm, 0.93 mm, and 1.2 mm, respectively. Pavement structure composed of fiber‐reinforced solidified soil can meet the load capacity requirements for use in airstrips under the characteristics of time‐sensitive application.
Effect of Seepage Force on the Wellbore Breakdown of a Vertical Wellbore
Authors: Zhou Desheng , Wang Haiyang , Liu Yafei , Liu Shun , Ma Xianlin , Cai Wenbin , Huang Hai
Published: April 2021

As a fluid flows through a porous media, a drag force, called seepage force in the paper, will be formed on the matrix of the media in the fluid flowing direction. However, the seepage force is normally ignored in the analysis of wellbore fracturing during hydraulic fracturing operation. In this paper, an analytical model for seepage force around a vertical wellbore is presented based on linear elasticity theory, and the effect of the seepage force on wellbore breakdown has been analyzed. Also studied are the effects of the two horizontal principal stresses and the reservoir permeability on the action of seepage force. The paper proves that seepage force lowers formation breakdown pressure of a vertical wellbores; the deeper a formation is, the greater action of the seepage force; seepage force contributes more to breakdown formation with small difference of the two horizontal stresses such as unconventional reservoirs; seepage force increases as rock permeability decreases, and it should not be ignored in hydraulic fracturing analysis, especially for low-permeability formation.
Green Technology Collaboration Network Analysis of China’s Transportation Sector: A Patent-Based Analysis
Authors: Huang Lufei , Xu Ying , Pan Xiaohui , Zhang Tao
Published: April 2021

The development of green transportation technologies in China has grown rapidly due to increasing concerns about climate change and environmental pollution. Collaboration innovations covering kinds of participating entities and various linked relationships have become one of the critical drivers for the transportation sector. Some researchers have analysed the collaborative innovation of scientific literature in this field. However, fewer studies have investigated the current performance of collaborative technology innovation represented by patents in the transportation sector. In this context, a research framework based on the social network analysis approach is proposed for collaboration green transportation technologies. The purpose of the research is to establish an analytical framework for the green transportation innovation network and seek the key collaboration activities and strategies. Subsequently, a collaborative innovation network based on the patent data of green transportation technologies was built and analysed. Especially, the innovation entities in the collaboration network are divided into four groups: business enterprises, individuals, universities, and research institutions, so that more detailed information in the network could be obtained. The results show that the proposed research framework based on patent data and social network analysis method helps examine the critical nodes and links in the network, as well as their types and characteristics of the collaboration network. The increasing number of green transportation technologies shows active cooperation in this field. The study also found that business enterprises node gradually plays a major role in cooperative innovation. The corresponding policy recommendations are also provided.
Risk Factors for Failure in First-Time Hearing Screening Tests among High-Risk Neonates in Neonatal Intensive Care Unit
Authors: Zhai Feng , Fang Xuhua , Li Yanbo , Chen Haoliang , Chen Jie
Published: April 2021

Objective: The aim of the study was to investigate into the risk factors for failure in the first-time screening test among high-risk neonates in neonatal intensive care unit (NICU) in order to further clarify the etiology of neonatal hearing impairment, thus providing insights into early prevention and intervention. Methods: We performed automated auditory brainstem response (AABR), distortion product otoacoustic emission (DPOAE), and acoustic immittance (AI) on 2,194 high-risk neonates admitted into the NICU of Shanghai Children’s Medical Center from January 2015 to December 2019, and the risk factors, including premature birth, hyperbilirubinemia, and infant respiratory distress syndrome, were analyzed retrospectively by the univariate χ2 test and multivariate stepwise logistic regression analysis. Results: The pass rates of AABR, DPOAE, and AI were 70.21, 78.44, and 93.12%, respectively, in 2,194 cases of high-risk neonates screened, which are significantly lower than those of healthy controls. The most common diagnoses included artificial feeding, preterm birth, C-section, low birth weight (LBW), neonatal hyperbilirubinemia (NHB), neonatal respiratory distress syndrome (NRDS), congenital heart disease (CHD), gestational diabetes mellitus, pregnancy-induced hypertension syndrome, advanced maternal age (AMA), twins, and in vitro fertilization. Stepwise logistic regression analysis indicated that the AABR pass rate was negatively correlated with LBW (p = 0.002), NHB (p < 0.001), NRDS (p = 0.007), artificial or mixed feeding (p = 0.018), and CHD (p = 0.005). The pass rate of DPOAE was negatively correlated with artificial or mixed feeding (p = 0.041), NHB (p < 0.001), LBW (p = 0.007), very LBW (VLBW) (p = 0.008), and C-section (p < 0.001). The pass rate of AI was negatively correlated with revised AMA (≥40 year) (p < 0.001), NHB (p = 0.043), C-section (p = 0.005), and artificial/mixed feeding (p = 0.036). Conclusion: The hearing screening pass rates of high-risk neonates in the NICU were lower than those of normal neonates, among which the rate of AABR was significantly lower than that of DPOAE. NRDS, NHB, LBW, revised AMA, CHD, C-section, and artificial feeding are potential risk factors of hearing impairment. The combination of different hearing screening tests is necessary for accurate diagnosis of congenital hearing disorders.
Application of Copy Number Variation Sequencing in Genetic Analysis of Miscarriages in Early and Middle Pregnancy
Authors: Luo Shiqiang , Chen Xingyuan , Yan Tizhen , Ya Jiaolian , Xu Zehui , Cai Pengfei , Yuan Dejian , Tang Ning
Published: April 2021

High-throughput sequencing based on copy number variation (CNV-seq) is commonly used to detect chromosomal abnormalities. This study identifies chromosomal abnormalities in aborted embryos/fetuses in early and middle pregnancy and explores the application value of CNV-seq in determining the causes of pregnancy termination. High-throughput sequencing was used to detect chromosome copy number variations (CNVs) in 116 aborted embryos in early and middle pregnancy. The detection data were compared with the Database of Genomic Variants (DGV), the Database of Chromosomal Imbalance and Phenotype in Humans using Ensemble Resources (DECIPHER), and the Online Mendelian Inheritance in Man (OMIM) database to determine the CNV type and the clinical significance. High-throughput sequencing results were successfully obtained in 109 out of 116 specimens, with a detection success rate of 93.97%. In brief, there were 64 cases with abnormal chromosome numbers and 23 cases with CNVs, in which 10 were pathogenic mutations and 13 were variants of uncertain significance. An abnormal chromosome number is the most important reason for embryo termination in early and middle pregnancy, followed by pathogenic chromosome CNVs. CNV-seq can quickly and accurately detect chromosome abnormalities and identify microdeletion and microduplication CNVs that cannot be detected by conventional chromosome analysis, which is convenient and efficient for genetic etiology diagnosis in miscarriage.
Faktoren für die Langzeitprognose des klinischen Erfolgs nach interventioneller Bronchoskopie bei Patienten mit narbiger zentraler Atemwegsstenose
Authors: Sun Kunyan , Zhang Hong , Zhang Wei , Cheng Yuan , Wang Guangfa
Published: April 2021

Hintergrund: Die narbige Stenose der zentralen Atemwege (scarring central airway stenosis, SCAS) ist eine potenziell lebensbedrohliche Erkrankung mit stark belastenden Symptomen. Immer häufiger wird die interventionelle Bronchoskopie eingesetzt, um die Symptome von Patienten mit SCAS zu lindern, doch kommt es häufig zu rezidivierenden Stenosen. Zur langfristigen Prognose der interventionellen Bronchoskopie bei SCAS liegen nur wenige Daten vor. Ziel der vorliegenden Arbeit war es, die prognostischen Faktoren von bronchoskopischen Interventionen bei Patienten mit SCAS zu bewerten, um die Therapie zu verbessern. Methoden: Es handelt sich um eine retrospektive Studie, in die 119 konsekutive Patienten mit SCAS aufgenommen wurden, die zwischen Januar 2010 und April 2019 an unserer Einrichtung behandelt worden waren. Klinischer Langzeiterfolg war definiert als eine Atemwegsstenose von weniger als 50%, keine Einschränkung der körperlichen Aktivität und ein stabiler Zustand für mehr als 12 Monate nach der letzten Intervention. Wir verglichen die demografischen Daten der Patienten, die Charakteristika der Atemwegsstenose und die interventionellen Verfahren in der erfolgreich behandelten Gruppe mit denen der erfolglos behandelten Gruppe und identifizierten mithilfe univariater und multivariater logistischer Regressionsanalysen relevante prädiktive Faktoren für das langfristige Behandlungsergebnis. Ergebnisse: Insgesamt wurden 119 Patienten mit 577 therapeutischen Bronchoskopien eingeschlossen. Von diesen wurden 75 Patienten (63%) als langfristig erfolgreich klinisch behandelt eingestuft. Gemäß der univariaten Regressionsanalyse waren ein höheres Lebensalter, männliches Geschlecht, Rauchen, erhöhte CRP (C-reaktives Protein)-Spiegel, eine subglottische Stenose, Stent- oder T-Tubus-Implantation, eine frühere interventionelle Behandlung sowie mehrere Interventionen pro Jahr potenziell mit erfolglosen Langzeitergebnissen assoziiert. Ein aktueller Raucherstatus (Odds Ratio [OR]: 5,70, 95%-Konfidenzintervall [KI]: 1,35–24,17, p = 0,018), eine subglottische Stenose (OR: 4,35, 95%-KI: 1,31–14,46, p = 0,017) und eine Stent-Implantation (OR: 4,96, 95%-KI: 1,33–18,48, p = 0,017) waren in der multivariaten logistischen Regressionsanalyse mit einer geringeren Wahrscheinlichkeit für langfristigen Erfolg verbunden. Bedeutsam ist, dass kein signifikanter Unterschied in der Erfolgswahrscheinlichkeit zwischen ehemaligen Rauchern und Nichtrauchern zu beobachten war. Schlussfolgerungen: Ein aktueller Raucherstatus, eine subglottische Stenose und Stentimplantation sind als unabhängige Faktoren mit einer verringerten Langzeitwirksamkeit der interventionellen Bronchoskopie bei SCAS assoziiert. Um das Ergebnis der therapeutischen Bronchoskopie zu verbessern, sollte die Empfehlung lauten, das Rauchen aufzugeben.
Hybrid PSO-GSA algorithm-based optimal control strategy for performance enhancement of a grid-connected wind generator
Authors: Amin Mina N. , Soliman Mahmoud A. , Hasanien Hany M. , Abdelaziz Almoataz Y.
Published: April 2021

Due to the great level of wind energy penetration in the existing network, huge efforts have been directed to enhance the grid-connected wind generator performance. This paper shows an application of a hybrid algorithm of the particle swarm optimization and the gravitational search algorithm (PSO-GSA) to enhance the transient stability of the grid-tied wind energy conversion system. The variable-speed wind turbine (VSWT) direct-drive permanent-magnet synchronous generator is connected to the network through a full-scale converter. The generator- and grid-side converters are controlled by utilizing an optimum proportional-integral (PI) controller. The criterion of the integral squared error is utilized as an objective function. The PSO-GSA based-PI controller efficacy is validated by comparing its results with that are obtained by utilizing the genetic algorithm (GA)-based-PI controller. The performance of the suggested control scheme is checked during various fault conditions. The control scheme quality is legalized by the simulation results that are obtained using MATLAB/Simulink program
Factual power loss reduction by enriched black hole algorithm
Authors: Lenin Kanagasabai
Published: April 2021

This paper presents enriched black hole algorithm (EBHA) for solving optimal reactive power problem. In this work black hole algorithm based on membrane computing is projected. In black hole algorithm evolution of the population is through pushing the candidates in the course of the most excellent candidate in iterations and black hole which swap with those in the search space. Membrane computing is also branded as P system and it has multisets of objects with evolution rules in the membrane structure. Membrane structure is alike ingrained tree of section that demarcate the areas, and root is labelled as skin. Chemical substances (multisets of objects) are there inside the section (membranes) of a cell and the chemical reactions (evolution rules) that take place within the cell. Proposed enriched black hole algorithm (EBHA) has been evaluated in IEEE 14,300 bus test system. Loss reduction achieved.
Editorial V16 N2
Authors: Ornstein Sheila Walbe , Andery Paulo Roberto Pereira , Fabricio Márcio Minto
Published: April 2021

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