bluuebunny/crossref_metadata_2025 huggingface dataset:
Utility of CPR Machine Power and Change in Right Atrial Pressure for Estimating CPR Quality
Authors: Lee Do-Yeon , Kang Seong-Min , Choi Seong-Wook
Published: June 2019

When a cardiac arrest occurs, it is necessary to perform cardiopulmonary resuscitation (CPR) as soon as possible. This requires maintaining the pressure depth at 5 cm at a rate of 100 cpm. For CPR machines, which are frequently used in ambulances, the return of spontaneous circulation (ROSC) is not superior to that of manual CPR, although CPR machines can maintain the compression rate and reciprocal distance of the compression plate more accurately. When the thoracic cavity is deformed due to repeated chest compressions, CPR machines must be adjusted. It is necessary to develop a method for measuring whether adequate CPR is achieved using CPR machines. CPR was performed on two pigs with a CPR machine, commencing 1 minute after the heart was stopped. Four CPR modes were used, with compression rates of 60 or 100 cpm and compression depths of 3 or 5 cm. The CPR machine was equipped with a load cell for measuring compression force, and a potentiometer for measuring compression depth. The measurement results obtained from the sensor were used to calculate the frequency components. The compression force and depth data were used to calculate the mechanical power of the CPR machine and mechanical impedance of the thoracic cavity. Changes in end-tidal carbon dioxide (ETCO2), coronary perfusion pressure (CPP), carotid blood flow (CBF), and right atrial pressure (RAP) were measured during performance of CPR; change in RAP refers to variation therein with chest compressions. Continuous CPR in both animals resulted in deformation of the chest cavity and a steady decline in impedance. The correlation between CPR power and change in RAP was 0.78, and that between compression force and CBF was 0.64. Impedance was not correlated with blood pressure or CBF. When the condition of the animal deteriorated due to cardiac arrest, the CPP decreased and ETCO2 increased. The CPR power and RAP varied according to the CPR mode rather than the condition of the animal. Measuring the CPR machine power does not require a separate procedure, such as catheter intubation, so should be suitable as an index of the quality of CPR in emergency situations.
Aptness of Escherichia coli host strain CB390 to detect total coliphages in Colombia
Authors: Campos Claudia , Méndez Javier , Venegas Camilo , Riaño Luisa Fernanda , Castaño Paula , Leiton Natalia , Riaño Eliana
Published: June 2019

Fecal bacteria have been used for more than a century as indicators of fecal contamination in water. In recent years, the monitoring of somatic and F-specific coliphages has been gradually included in guidelines and regulations as an additional parameter to reinforce water safety. The Escherichia coli host strain CB390 was tailored to detect both somatic and F-specific coliphages in a single test. The efficacy of this strain for bacteriophage detection, previously evaluated in Western Europe and North America, was assessed here for the first time in South America. The detection of somatic and F-specific coliphages by the strain CB390, as well as by standardized methods, was performed in drinking and river water and municipal and abattoir wastewaters. No statistical difference was found in the numbers of total coliphages detected by strain CB390 and the sum of somatic and F-specific coliphages determined separately by the standardized ISO methods. The data presented here provide further validation of the effectiveness of the host strain E. coli CB390 for the detection of total coliphages in waters in a single test and demonstrate its suitability for application in upper-middle income countries of the Americas (World Bank category).
A dandelion-like liposomes-encoded magnetic bead probe-based toehold-mediated DNA circuit for the amplification detection of MiRNA
Authors: Kong Yancong , Liu Xiaowen , Liu Chunxue , Xue Qingwang , Li Xia , Wang Huaisheng
Published: June 2019

The development of facile and sensitive miRNA quantitative detection methods is a central challenge for the early diagnosis of miRNA-related diseases.
Simultaneous detection of carcinoembryonic antigen and neuron-specific enolase in human serum based on time-resolved chemiluminescence immunoassay
Authors: Mao Yanhua , Wang Nana , Yu Fei , Yu Songcheng , Liu Lie , Tian Yongmei , Wang Jia , Wang Yilin , He Leiliang , Wu Yongjun
Published: June 2019

We developed a novel, effective, reliable and convenient TRCLIA method for the simultaneous detection of CEA and NSE in serum.
Fluorescence analysis of cobalt(ii) in water with β-cyclodextrin modified Mn-doped ZnS quantum dots
Authors: Yang Shiwei , Fan Wanli , Wang Dongmei , Gong Zhengjun , Fan Meikun
Published: June 2019

The analysis of Co2+ in agricultural water is of great importance for the healthy growth and safe supply of crops.
A signal amplifying fluorescent nanoprobe and lateral flow assay for ultrasensitive detection of cardiac biomarker troponin I
Authors: Lou Doudou , Fan Lin , Ji Yongxin , Gu Ning , Zhang Yu
Published: June 2019

Novel functionalized nanoprobes based on a biotin–streptavidin system led to fluorescence signal amplification and the improvement of cTnI detection sensitivity.
Room temperature thiosulfate ion redox reaction-driven synthesis of a robust porous copper–cobalt–sulfur–oxygen nanowire coating on copper foam for highly-efficient and low-cost oxygen evolution reaction
Authors: Wang Yanqing , Li Yuemeng , Ding Liping , Ong Aaron , Ding Jun
Published: June 2019

Room temperature thiosulfate ion redox reaction-driven synthesis of robust porous Cu–Co–S–O NWC on copper foam for highly-efficient and low-cost OER.
A new Zn(ii)-based 3D metal–organic framework with uncommon sev topology and its photocatalytic properties for the degradation of organic dyes
Authors: Pan Ying , Ding Qiongjie , Xu Hongjia , Shi Chunyue , Singh Amita , Kumar Abhinav , Liu Jianqiang
Published: June 2019

A new Zn(ii) based 3D MOF having uncommon sev topology synthesized and used as efficient photocatalyst for the photodegradation of dyes methyl violet and rhodamine B.
Synthesis and electromagnetic wave absorption performance of NiCo2O4 nanomaterials with different nanostructures
Authors: Zhu Qinghai , Zhang Zilong , Lv Yangyang , Chen Xiqiao , Wu Zhuang , Wang Shuai , Zou Yanhong
Published: June 2019

Bayberry-like, needle array-like and urchin-like NiCo2O4 hierarchical structures were synthesized by simple hydrothermal reactions.
Pd local structure and size correlations to the activity of Pd/TiO2 for photocatalytic reforming of methanol
Authors: Abdullah Norli , Bahruji Hasliza , Rogers Scott M. , Wells Peter P. , Catlow C. Richard A. , Bowker Michael
Published: June 2019

The interaction between Pd and TiO2 for promoting photocatalytic activity was investigated by tailoring the size of Pd nanoparticles and monitoring the photocatalytic activity of methanol photo-reforming reaction for hydrogen gas production.
Assessing a thermal spike model of swift heavy ion–matter interactions via Pd1−xNix/Si interface mixing
Authors: Patra Paramita , Khan S. A. , Bala M. , Avasthi D. K. , Srivastava S. K.
Published: June 2019

A combination of density functional theory computations and swift heavy ion (SHI) mixing experiments is employed to assess the thermal spike model of SHI–matter interactions.
Distinguishing ice β-XV from deep glassy ice VI: Raman spectroscopy
Authors: Thoeny Alexander V. , Gasser Tobias M. , Loerting Thomas
Published: June 2019

Evidence for the existence of D2O-ice β-XV is given by the observation of its librational Raman band at 380 cm−1.
Characterization of chemically modified gold and silver clusters in gas phase
Authors: Hirata Keisuke , Tomihara Ryohei , Kim Kuenhee , Koyasu Kiichirou , Tsukuda Tatsuya
Published: June 2019

This perspective summarizes our recent efforts in the application of gas-phase characterization methods to ligand-protected Au/Ag clusters chemically synthesized with atomic precision.
Room temperature CO oxidation catalysed by supported Pt nanoparticles revealed by solid-state NMR and DNP spectroscopy
Authors: Klimavicius Vytautas , Neumann Sarah , Kunz Sebastian , Gutmann Torsten , Buntkowsky Gerd
Published: June 2019

A series of 1 and 2 nm sized platinum nanoparticles deposited on different support materials are investigated by solid-state NMR combined with dynamic nuclear polarization (DNP).
Highly open chalcogenide frameworks built from unusual defective supertetrahedral clusters
Authors: Xue Chaozhuang , Zhang Li , Wang Xiaoli , Wang Xiang , Zhang Jiaxu , Wu Tao
Published: June 2019

Two highly open chalcogenide frameworks built from unusual supertetrahedral SBUs.
A microporous metal–organic framework with naphthalene diimide groups for high methane storage
Authors: Ye Yingxiang , Lin Rui-Biao , Cui Hui , Alsalme Ali , Zhou Wei , Yildirim Taner , Zhang Zhangjing , Xiang Shengchang , Chen Banglin
Published: June 2019

A microporous metal–organic framework with open metal and carbonyl sites for high methane storage at room temperature.
Isolation of a C3-metalated indolizine complex and a phosphonium ring-fused bicyclic metallafuran from the osmium-induced transformation of pyridine-tethered alkynes
Authors: Chung Lai-Hon , Yeung Chi-Fung , Shek Hau-Lam , Wong Chun-Yuen
Published: June 2019

Isolation of the C3-metalated indolizine and bicyclic osmafuran complexes revealed the intermediacy of metal–vinylidene species regarding [Os(dppm)2Cl]+-mediated alkyne transformations.
Artificial photosynthesis – concluding remarks
Authors: Bozal-Ginesta C. , Durrant J. R.
Published: June 2019

This paper follows on from the Concluding Remarks presentation of the 3rd Faraday Discussion Meeting on Artificial Photosynthesis, Cambridge, UK, 25–27th March 2019. It aims to discuss the context for the research discussed at this meeting with an overview of the motivation for research on artificial photosynthesis and an analysis of the composition and trends in the field of artificial photosynthesis, primarily using the results of searches of publication databases.
Efficient synthesis of enantiopure amines from alcohols using restingE. colicells and ammonia
Authors: Houwman Joseline A. , Knaus Tanja , Costa Magda , Mutti Francesco G.
Published: June 2019

E. colicells co-expressing alcohol dehydrogenases and an amine dehydrogenase convert alcohols into enantiopure amines at the expense of ammonia.
Chitin in ionic liquids: historical insights into the polymer's dissolution and isolation. A review
Authors: Shamshina Julia L.
Published: June 2019

This comprehensive review provides an analysis of findings related to chitin dissolution in ionic liquids based on the polymer's quality.
Bioinspired hydrogel microfibres colour-encoded with colloidal crystals
Authors: Meng Zhi-Jun , Zhang Jing , Deng Xu , Liu Ji , Yu Ziyi , Abell Chris
Published: June 2019

The integration of microfluidic spinning and colloidal crystal microdots enable the colour-encoded hydrogel microfibres with facile and flexible manipulation of the encoding.
A smart AIEgen-functionalized surface with reversible modulation of fluorescence and wettability
Authors: Cai Xin , Xie Ni , Li Ying , Lam Jacky W. Y. , Liu Junkai , He Wei , Wang Jianguo , Tang Ben Zhong
Published: June 2019

An AIEgen-functionalized surface with tunable fluorescence and wettability is obtained by taking advantage of anion–π+ interactions.
Metal-free multiporous carbon for electrochemical energy storage and electrocatalysis applications
Authors: Chinnadurai Deviprasath , Karuppiah Pandi , Chen Shen-Ming , Kim Hee-jee , Prabakar Kandasamy
Published: June 2019

An electrocatalytic and electrochemical energy storage study of biomass-derived metal-free carbon is carried out.
Hollow sphere formation by the self aggregation of perovskite fluoride NaNiF3 nanocrystals and the application of these spheres as an electrode in an ultrahigh performance asymmetric supercapacitor
Authors: Hussain Nadeem , Wu Fangfang , Younas Waqar , Xu Liqiang
Published: June 2019

A stable hollow sphere NaNiF3//AC device with ultra-high energy and power density.
Facile and green synthesis of highly fluorescent nitrogen-doped carbon dots from jackfruit seeds and its applications towards the fluorimetric detection of Au3+ ions in aqueous medium and in in vitro multicolor cell imaging
Authors: Raji Kaviyarasan , Ramanan Vadivel , Ramamurthy Perumal
Published: June 2019

N-CDs are synthesized by an outright green method and employed as a selective fluorescent probe for Au3+ ions and is also used as a reducing agent to synthesize AuNPs.
Near-infrared light activatable hydrogels for metformin delivery
Authors: Chengnan Li , Pagneux Quentin , Voronova Anna , Barras Alexandre , Abderrahmani Amar , Plaisance Valérie , Pawlowski Valerie , Hennuyer Nathalie , Staels Bart , Rosselle Lea , Skandrani Nadia , Li Musen , Boukherroub Rabah , Szunerits Sabine
Published: June 2019

Drug loaded hydrogels have proven to be versatile controlled-release systems.
Mussel-inspired functionalization of semiconducting polymer nanoparticles for amplified photoacoustic imaging and photothermal therapy
Authors: Bao Biqing , Tong Li , Xu Yu , Zhang Jingjing , Zhai Xue , Su Peng , Weng Lixing , Wang Lianhui
Published: June 2019

Semiconducting polymer nanoparticles encapsulated with polydopamine as both the protection and bioconjugation layer for amplified photoacoustic imaging and photothermal therapy are proposed.
Succinylated heparin monolayer coating vastly increases superparamagnetic iron oxide nanoparticle T2 proton relaxivity
Authors: Xie Manman , Liu Shijia , Butch Christopher J. , Liu Shaowei , Wang Ziyang , Wang Jianquan , Zhang Xudong , Nie Shuming , Lu Qian , Wang Yiqing
Published: June 2019

Superparamagnetic iron oxide nanoparticles (SPIONs) have a history of clinical use as contrast agents in T2 weighted MRI, though relatively low T2 relaxivity has caused them to fall out of favor as new faster MRI techniques have gained prominence.
Screening of metal complex catalysts using bidentate Schiff base ligands for controlled cationic polymerization of vinyl ethers using in situ complexation method
Authors: Kigoshi Sensho , Kanazawa Arihiro , Kanaoka Shokyoku , Aoshima Sadahito
Published: June 2019

Appropriate ligand scaffolds in cationic polymerization were screened using various bidentate Schiff base ligand/ZrCl4 initiating systems.
Size control synthesis of melanin-like polydopamine nanoparticles by tuning radicals
Authors: Wang Xianheng , Chen Zhan , Yang Peng , Hu Junfei , Wang Zhao , Li Yiwen
Published: June 2019

We report the first effort to control the size of polydopamine nanoparticles via adding either strong free radical scavengers (i.e. edaravone) or stable free radicals (i.e. PTIO˙) during the polymerization.
Use of poly(vinylidene fluoride-co-vinyl dimethylphosphonate) copolymers for efficient extraction of valuable metals
Authors: Wehbi Mohammad , Bourgeois Damien , Améduri Bruno
Published: June 2019

The radical copolymerisation of vinylidene fluoride (VDF) with vinyl dimethyl phosphonate (VDMP) initiated by various kinds of initiators is presented.
Controlled grafting of dialkylphosphonate-based ionic liquids on γ-alumina: design of hybrid materials with high potential for CO2 separation applications
Authors: Pizzoccaro-Zilamy M. A. , Piña S. Muñoz , Rebiere B. , Daniel C. , Farrusseng D. , Drobek M. , Silly G. , Julbe A. , Guerrero G.
Published: June 2019

Grafting of diethylphophonate-based ILs onto γ-Al2O3 powder in solvothermal condition was achieved on mesoporous γ-alumina powder and membrane (A = organic spacer).
Multiple-engineering controlled growth of tunable-bandgap perovskite nanowires for high performance photodetectors
Authors: Ren Kuankuan , Wang Jian , Liu Kong , Huang Yanbin , Sun Yang , Azam Muhammad , Jin Peng , Wang Zhijie , Qu Shengchun , Wang Zhanguo
Published: June 2019

This new approach enables the growth of different halide perovskite nanowires, which demonstrate a high photoelectric detection performance.
Preparation of disperse inks for direct inkjet printing of non-pretreated polyester fabrics
Authors: Gao Chengyong , Xing Tieling , Hou Xueni , Chen Guoqiang
Published: June 2019

The preparation of disperse inks for direct inkjet printing was carried out using disperse dye, dispersant (TD-1109, hydrophilic polyacrylic acid block copolymer), wetting agent (DEG and EG), water-based polymers (PVA or waterborne polyester), deionized water,etc.
Micronutrients encapsulation in enhanced nanoliposomal carriers by a novel preparative technology
Authors: Dalmoro Annalisa , Bochicchio Sabrina , Lamberti Gaetano , Bertoncin Paolo , Janssens Barbara , Barba Anna Angela
Published: June 2019

Micronutrients administration by liposomal vectors is a growing strategy in fortification processes of staple and complementary foods to fight malnutrition and micronutrient deficiencies and related pathologies.
Relationship between teaching assistants’ perceptions of student learning challenges and their use of external representations when teaching acid–base titrations in introductory chemistry laboratory courses
Authors: Baldwin Nicole , Orgill MaryKay
Published: June 2019

Practicing chemists use models, diagrams, symbols, and figures to represent phenomena which cannot be detected by the human senses. Although research suggests that these external representations (ERs) can also be used to address the challenges that students have in learning chemistry, it is not clear how instructors' use of ERs aligns with their perceptions of student learning difficulties. In other words, do instructors use ERs to address what they perceive as students' major challenges in learning chemistry, or are they using ERs for other reasons? The answer to this question could have implications for the professional development of chemistry instructors, including both classroom instructors and laboratory facilitators. As a pilot study to guide the development of a larger project focused on the use and interpretation of ERs, we interviewed eleven general chemistry teaching assistants at a major university in the U.S. Southwest about their use of ERs when facilitating acid–base titration laboratory activities. Our data suggest that there is a lack of alignment between teaching assistants’ primary reported use of ERs and the primary challenge that they perceive their students have when learning about acid–base titrations. We discuss potential reasons for this misalignment, as well as implications for teaching assistant training related to the use of ERs in the laboratory learning environment.
Revisiting the use of concept maps in a large enrollment general chemistry course: implementation and assessment
Authors: Talbert Lance E. , Bonner James , Mortezaei Kiana , Guregyan Cybill , Henbest Grace , Eichler Jack F.
Published: June 2019

In an effort to improve student conceptual understanding and help students better connect pre-existing knowledge to new ideas, a concept map assignment was implemented in a first-year college level general chemistry course. This implementation included a quasi-experiment that was carried out in discussion group recitation sections within a third-quarter general chemistry course. Students enrolled in a single section of the course were divided into two groups in which a concept map treatment was compared to a control group that completed short journal entries. Comparison of a concept inventory post-test using an independent samples t-test indicates students in the concept map treatment appear to perform better than the students in the journal control group (t = 2.34, mean difference = 0.844, p < 0.05). However, a multi-variable regression analysis in which the concept inventory post-test scores were compared between the treatment and control groups, while traits related to incoming academic preparation were held constant, suggests there was no significant difference in performance (unstandardized b = 0.222, p = 0.540). The quality of the students’ concept maps was also evaluated and correlated to student performance on the concept inventory, and it appears students who were better at concept mapping made greater gains in conceptual understanding (Pearson's r = 0.295, p < 0.05). When the relationship between the quality of concept mapping and concept inventory post-test was determined while holding constant covariates related to incoming academic preparation, the unstandardized B coefficient was positive, but was not significant at the p = 0.05 level (unstandardized b = 0.215, p = 0.134) This study does not provide unequivocal evidence that a concept map treatment leads to greater gains in conceptual understanding compared to a control population, or that students with better concept mapping skills performed better on the concept inventory instrument. Nevertheless, a template for implementing a concept map assignment in a large enrollment course is provided, and the results presented herein might prompt chemistry instructors to consider including concept map assignments in their instructional toolbox.
Blended learning in a second year organic chemistry class: students’ perceptions and preferences of the learning support
Authors: Tekane Rethabile , Pilcher Lynne A. , Potgieter Marietjie
Published: June 2019

Although the implementation of blended learning in organic chemistry is rapidly growing, thus far, there are few studies published on the evaluation of supplemental types of blend in organic chemistry. This report covers a phenomenographic study that was designed to evaluate a supplemental type of blended learning approach implemented in a second-year organic chemistry course in a South African context. It offers a unique contribution in terms of catering to the needs of a diverse student body. Three open-ended questionnaires were used to probe: (1) students’ perceptions of the learning support; (2) students’ preferences for different types of learning support offered; and (3) students’ suggestions for improvement. Semi-structured individual interviews were used to obtain clarity on some of the responses from the questionnaires. Analysis of students’ responses revealed that the face-to-face component was highly valued as it gave the students the opportunity to ask questions and obtain answers in real time; the online component, especially Learnsmart, was found helpful for its flexibility and providing limitless opportunities to practice or revisit concepts. The discussion board was the least valued due to the overwhelming number of postings, and the students felt they were forced to participate in order to get marks. The students experienced the course as too fast-paced possibly reflecting cognitive overload, a potential weakness of the supplemental blend. The findings will be useful in many other contexts where the student body is diverse in terms of language proficiency and the level of preparation for the demands of organic chemistry as a discipline.
Insights from 125Te and 57Fe nuclear resonance vibrational spectroscopy: a [4Fe–4Te] cluster from two points of view
Authors: Wittkamp Florian , Mishra Nakul , Wang Hongxin , Wille Hans-Christian , Steinbrügge René , Kaupp Martin , Cramer Stephen P. , Apfel Ulf-Peter , Pelmenschikov Vladimir
Published: June 2019

Can sulfur-to-tellurium exchange serve as a method to understand iron–sulfur clusters of enzymatic systems?
Using cavitation rheology to understand dipeptide-based low molecular weight gels
Authors: Fuentes-Caparrós Ana M. , Dietrich Bart , Thomson Lisa , Chauveau Charles , Adams Dave J.
Published: June 2019

We show that combining cavitation and conventional rheology can be used to understand the underlying microstructure in gels.
Visualizing percolation and ion transport in hybrid solid electrolytes for Li–metal batteries
Authors: Zaman Wahid , Hortance Nicholas , Dixit Marm B. , De Andrade Vincent , Hatzell Kelsey B.
Published: June 2019

Hybrid solid state electrolyte structure was imaged using synchrotron nanotomography. Accessible surface area of ceramic particles in the electrolytes governs ion transport.
Organic quinones towards advanced electrochemical energy storage: recent advances and challenges
Authors: Han Cuiping , Li Hongfei , Shi Ruiying , Zhang Tengfei , Tong Jing , Li Junqin , Li Baohua
Published: June 2019

This review provides an up-to-date summary of the progress of organic quinones as electroactive materials for advanced electrochemical energy storage devices.
Ambient dinitrogen electrocatalytic reduction for ammonia synthesis
Authors: Chen Aling , Xia Bao Yu
Published: June 2019

Recent advances in the fabrication of novel electrocatalysts for dinitrogen reduction to ammonia synthesis under ambient conditions are comprehensively reviewed.
Binary cooperative flexible magnetoelectric materials working as self-powered tactile sensors
Authors: Zhang Xuan , Ai Jingwei , Ma Zheng , Du Zhuolin , Chen Dezhi , Zou Ruiping , Su Bin
Published: June 2019

This study will demonstrate the fabrication of binary cooperative flexible magnetoelectric materials and their application in self-powered tactile sensors.
Skeleton‐based action recognition with JRR‐GCN
Authors: Ye Fanfan , Tang Huiming
Published: June 2019

A novel joints relation‐reasoning, graph convolutional network (JRR‐GCN) is proposed to solve the problem of skeleton‐based action recognition (SAR). Different from the conventional spatial convolutional network‐based methods, the adjacency matrices of JRR‐GCN is reasoned by joints relation‐reasoning network (JRR) automatically, which results in generating a more realistic representation of skeleton topology and yields better adjacency matrices for every sample. JRR is trained with the reinforcement learning with a novel state‐action mapping scheme. Extensive experiments are conducted on two public SAR datasets, NTU‐RGB+D and kinetics. Also the obtained results demonstrate the effectiveness of JRR‐GCN comparing with the state‐of‐the‐art SAR methods.
Stethoscope with digital frequency translation for improved audibility
Authors: Aumann Herbert M. , Emanetoglu Nuri W.
Published: June 2019

The performance of an acoustic stethoscope is improved by translating, without loss of fidelity, heart sounds, chest sounds, and intestinal sounds below 50 Hz into a frequency range of 200 Hz, which is easily detectable by the human ear. Such a frequency translation will be of significant benefit to hearing impaired physicians and it will improve the stethoscope performance in a noisy environment. The technique is based on a single sideband suppressed carrier modulation. Stability and bias problems commonly associated with an analog frequency translator are avoided by an all‐digital implementation. Real‐time audio processing is made possible by approximating a Hilbert transformer with a time delay. The performance of the digital frequency translator was verified with a 16‐bit 44.1 Ks/s audio coder/decoder and a 32‐bit 72 MHz microcontroller.
Linear array of dual‐polarised slot‐coupled dielectric‐rod elements for wireless applications
Authors: Shokouhi Farid , Hossein Firouzeh Zaker
Published: June 2019

The design of a dual‐polarised series‐fed microstrip array antenna for wireless applications, especially in the 5150–5750 MHz band, is delineated in this study, which consists of 12 dielectric rods, fed by circular slots. The rod height can be exploited to improve antenna gain and control its azimuth beamwidth. Using circular slot elements with a central crossing point improves port isolation and cross polarisation. The array elements are fed via two series‐fed six‐element arms having 25 dB Taylor distribution in each polarisation. The given arms are fed from the centre. Regarding H‐polarisation, the arms are fed with a 180° phase shift to improve isolation between the ports as well as the cross polarisation. Additionally, a reflector plane is placed behind the array to suppress back‐lobe radiation. A prototype of the array antenna is fabricated and measured. The return loss of the antenna is over 10 dB, varying from 5.1 to 5.8 GHz, and the isolation exceeds 30 dB over the bandwidth. The measured and simulated patterns are presented for both polarisations.
High‐resolution spotlight spaceborne SAR focusing via modified‐SVDS and deramping‐based approach
Authors: Qian Yulei , Zhu Daiyin
Published: June 2019

Fine resolution spaceborne spotlight synthetic aperture radar (SAR) imaging is typically affected by the problems of curved orbit and azimuth spectral aliasing, especially when the resolution achieves the decimetre level. In order to overcome these difficulties, a method is proposed here, which consists of the modified singular value decomposition Stolt (SVDS) and the deramping‐based approach. The modified SVDS is designed to properly handle the influence induced by curved orbit, and the deramping‐based approach is utilised to solve the azimuth spectral aliasing problem. The modified SVDS is derived from the original SVDS by further taking the singular value into consideration, which is more concise and efficient. In addition, the deramping‐based approach is combined with numerical differentiation so as to accommodate the situation of curved orbit. The proposed method has smaller phase error and performs better than the generalised ωK method when resolution achieves decimetre level. Experiments carried out on point target simulation validate the effectiveness of the presented method. With focused scene size of 4 by 3 km, the range and azimuth resolutions can achieve 0.15 and 0.14 m, respectively.
Robust particle filter based on Huber function for underwater terrain‐aided navigation
Authors: Peng Dongdong , Zhou Tian , Folkesson John , Xu Chao
Published: June 2019

Terrain‐aided navigation (TAN) is a promising technique to determine the location of underwater vehicle by matching terrain measurement against a known map. The particle filter (PF) is a natural choice for TAN because of its ability to handle non‐linear, multimodal problems. However, the terrain measurements are vulnerable to outliers, which will cause the PF to degrade or even diverge. Modification of the Gaussian likelihood function by using robust cost functions is a way to reduce the effect of outliers on an estimate. The authors propose to use the Huber function to modify the measurement model used to set importance weights in a PF. They verify their method in simulations of multi‐beam sonar in a real underwater digital map. The results demonstrate that the proposed method is more robust to outliers than the standard PF (SPF).
Radiometric localisation of partial discharge sources inside Air‐insulated electrical substation
Authors: Kumar Mishra Dipak , Bhukya Anitha , Koley Chiranjib , Kumar Roy Nirmal
Published: June 2019

Monitoring partial discharge (PD) activities inside electrical substation using few ultra high frequency (UHF) sensors mounted around the periphery of the substation could be a useful and economical tool. In this work, an experimental study has been conducted in the laboratory and in substations to investigate the localisation ability of the UHF PD detection system. For localisation, one needs to calculate time difference of arrivals (TDOAs) between the UHF waveforms obtained from the multiple sensors mounted around the substation. After that these TDOAs are used for localisation of the PD sources. In this paper a novel joint entropy (JE)‐based TDOAs calculation method is proposed and also compared with the existing techniques. For localisation of PD sources, a modified direction of arrival (DOA)‐based method for the near field is proposed, as found to be suitable when the sensors are mounted around the substation. Obtained results in TDOA estimation using the proposed JE method is in line with other technique; however, it was found to provide consistent results and is useful in an extreme situation. Modified DOA‐based localisation algorithm found to provide improved performance due to the elimination of approximation as required in previously reported far‐field‐based localisation system for the air‐insulated substations.
Towards a methodology for the characterisation of the fabric of wet clays using X-ray scattering
Authors: Birmpilis Georgios , Ahmadi-Naghadeh Reza , Dijkstra Jelke
Published: June 2019

X-ray scattering is a promising non-invasive technique to study evolving nano- and micromechanics in clays. This study discusses the experimental considerations and a successful method to enable X-ray scattering to study clay samples at two extreme stages of consolidation. It is shown that the proposed sample environment comprising flat capillaries with a hydrophobic coating can be used for a wide range of voids ratios ranging from a clay suspension to consolidated clay samples, that are cut from larger specimens of reconstituted or natural clay. The initial X-ray scattering results using a laboratory instrument indicate that valuable information on, in principal evolving, clay fabric can be measured. Features such as characteristic distance between structural units and particle orientations are obtained for a slurry and a consolidated sample of kaolinite. Combined with other promising measurement techniques from Materials Science the proposed method will help advance the contemporary understanding on the behaviour of dense colloidal systems of clay, as it does not require detrimental sample preparation
A sample formation procedure to obtain homogeneous post-erosion particle size distribution
Authors: Li Shijin , Russell Adrian R.
Published: June 2019

Internal erosion (suffusion) is caused by water seeping through the matrix of coarse soil and progressively transporting out fine particles. The mechanical strength of soils within water retaining structures may be affected after internal erosion occurs. However, most experimental investigations on the mechanical consequences of internal erosion have used triaxial tests on samples having nonhomogeneous particle size distributions along their lengths. Such nonhomogeneities arise from the most commonly used sample formation procedure, in which seeping water enters one end of a sample and washes fine particles out the other. In this paper a new soil sample formation procedure is presented which results in homogeneous particle size distributions along the direction of seepage, that is at all locations along a sample's length.
Influence of fissure inclination and confining pressure on the local behaviour of natural clays
Authors: Tudisco Erika , Vitone Claudia , Mondello Cristina , Viggiani Gioacchino , Hall Stephen A. , Cotecchia Federica , Castellano Alessandra , Massaro Francesco
Published: June 2019

In this experimental study the influence of fissuring orientation and confinement pressure on the mechanical behaviour of natural clays is investigated. The tested material, the scaly clay from Santa Croce di Magliano (south of Italy), is characterised by an intense network of pre-existing fissures of single orientation. Several plane strain compression tests have been conducted, under different confinement pressures (i.e., from 50 to 600 kPa), on specimens having fissures with vertical, medium and horizontal inclination. Digital Image Correlation has been used to follow the deformation processes of the specimens throughout the tests by measuring incremental shear and volumetric strain maps. The results showed a strong coupling between the total confinement and the fissure inclination, that is controlling both the onset and the development of the patterns of the localisation processes. The new results have been compared with previous ones carried out on the same material without confinement. The comparison shed light on the role of total confinement that becomes particularly relevant from certain levels of pressures and fissuring inclination.
Microscope observation of cracks of clay
Authors: Liang Chen , Gui Yilin , van der Land Cees
Published: June 2019

Clay has wide application in engineered barriers. However, it is prone to crack if moisture content decreases at most circumstances. This research aimed to microscopically study drying shrinkage and associated cracking of two different clays: kaolin and sodium-based bentonite, using optical microscope-Leica DM2700 M, under controlled condition. The samples used were cylindrical with 20mm in diameter and 1mm in depth. During the observation, microscopic images were captured and saved. These images were used to analyse the cracking behaviour due to drying. The testing results showed that cracks initially occur in the middle of the sample and then propagate to the sample boundary. The length and width of the crack was increased as moisture decreased.
Shear modulus of hydrate bearing calcareous sand-fines mixture
Authors: Ji Litong , Chiu Abraham C.F. , Ma Lu , Jian Chao
Published: June 2019

This article presents a laboratory study on the maximum shear modulus of a THF hydrate bearing calcareous sand (CS)–fines mixture. The maximum shear modulus was inferred from the shear wave velocity measured from the bender elements installed in a temperature-controlled triaxial apparatus. The specimen preparation procedures were specially designed to mimic the hydrate formation inside the internal pores of CS. A trial test was conducted to validate whether the shear wave velocity is a feasible parameter to monitor the formation and dissociation of hydrate in the CS-fines mixture. Based on the bender element test results, hydrate has a more profound effect than confining pressure on enhancing the maximum shear modulus of CS-fines mixture.
Stress path dependent small strain stiffness of Shanghai clay
Authors: Gu Xiaoqiang , Li Youhong , Liang Fayun , Huang Maosong
Published: June 2019

The soil small strain stiffness plays an important role in many geotechnical applications such as machine foundations, deep excavations and earthquake ground response analysis. In this study, the small strain stiffness of saturated intact Shanghai clay specimen is measured in a hollow cylinder apparatus. The lateral earth pressure coefficient at rest is measured first during the one-dimensional consolidation. After consolidation, the very small strain stiffness is obtained by shear wave measurement using bender elements, while the degradation of small strain stiffness with strain is investigated by quasi-static loading with high resolution linear variable displacement transducers (LVDT). The effect of stress path on the small strain stiffness is also investigated. The results show that the small strain stiffness is nonlinear and significantly depends on the stress path.
A semi-empirical relationship for the small-strain shear modulus of soft clays
Authors: Taukoor Vashish , Rutherford Cassandra J. , Olson Scott M.
Published: June 2019

The small-strain shear modulus (Gmax) is a soil property that has many practical applications. The authors compiled a database of Gmaxmeasurements for 40 normally consolidated to slightly overconsolidated low to high plasticity clays. Using these data, the authors propose a semi-empirical relationship between Gmax, effective stress (σ'v or σ'c), preconsolidation stress (σ'p) and in-situ void ratio (e0) for four ranges of plasticity index (Ip): Ip < 30%, 30% ≤ Ip < 50%, 50% ≤ Ip < 80% and 80% ≤ Ip < 120%. With results from bender element tests on a Gulf of Mexico clay subjected to multiple load-unload consolidation loops, the authors were able to validate the proposed relationships for 30% ≤ Ip < 50% and 50% ≤ Ip < 80%. The proposed relationship for 30% ≤ Ip < 50% and 50% ≤ Ip < 80% captures changes in laboratory Gmaxresulting from variations in effective stress (σ'c), maximum past stress (σ'v,max), and void ratio. The proposed relationships are a simple and efficient tool that can provide independent insight on Gmaxif the stress history of a clay is known, or on stress history if Gmaxis known.
Creep behaviour of undisturbed London Clay in triaxial stress space
Authors: Le Truong , Airey David , Standing Jamie
Published: June 2019

The evolution of the creep strain component in triaxial stress space was investigated through performing a series of multistage drained compression tests on London Clay using a specially designed locally instrumented triaxial apparatus. Experiments along specifically defined stress paths showed significant rotation of the local creep strain component as the samples were sheared towards failure. The results indicate a need for a more complex plastic potential function to correctly predict incremental creep strains at different states in triaxial stress space. Creep deformations for stress path controlled drained compression tests were also found to require a reinterpretation of the classic secondary compression behaviour. Creep strain-rates were found to fall well outside the normal power decay function. Test data and previously reported drained creep test results on London Clay have been combined to provide a complete understanding of the incremental creep component. The experiments show how creep behaviour significantly depends on the stress conditions imposed and the approaching strain rate.
Effect of drainage and saturation on undrained shear strength for compacted sandy soils
Authors: Nakata Yukio , Tashita Tetsuya , Chibana Hiromu , Matsukata Kenji
Published: June 2019

Collapses of embankments have occurred due to heavy rainfall. It is very important to understand the strength properties under various unsaturated, partially saturated and fully saturated conditions of compacted materials. So, a series of unsaturated and saturated triaxial compression tests for compacted soils have been conducted to understand the effects of drainage and saturation on undrained strength. Soil samples were collected from several road embankments to carry out the experiments. The undrained (CU) strength of compacted material decreased with increase in the degree of saturation. Especially, the strength decreased from partially saturated condition to fully saturated condition was remarkable. The decrease of the materials with volume contractive behaviour was appeared clearly.
Mechanical behaviour of unsaturated undisturbed black volcanic ash soil under static and cyclic loading
Authors: Asfino Putra Okri , Yasufuku Noriyuki , Ishikura Ryohei , Alowaisy Adel , Kawaguchi Yuko
Published: June 2019

The mechanical behaviour of unsaturated undisturbed black volcanic ash soils was investigated using a constant volume direct shear apparatus. A series of static and cyclic tests were conducted under unsaturated and saturated samples. The cyclic test under two patterns were adopted. First type of pattern, cyclic one-sided shearing was applied. For the second type, two-sided shearing was conducted. For further understanding of the chemical content and microstructure, X-Ray Fluorescence analysis (XRF) and Scanning Electron Microscope (SEM) were evaluated. It was found that, under static shearing, the unsaturated sample exhibits a higher apparent cohesion and friction angle in comparison to the saturated sample. The normalized vertical stress under one-sided cyclic shearing in both overconsolidated and normally consolidated samples rapidly reduced at the beginning of shearing. This might be attributed to increase of the pore water pressure during shearing. Furthermore, there is a significant difference between the normalized shear stress under cyclic one-sided and two-sided shearing. For the two-sided cyclic shearing test, the normalized shear stress value is higher than the one-sided cyclic shearing test. In addition, the normalized shear stress under unsaturated condition is significantly larger. This can be related to the suction forces to the total strength of soils. The main chemical content of the black volcanic ash soil is allophane. Further, the microstructure of the black volcanic ash changes due to shearing. For the overconsolidated sample, particles of soil more severe damage than normally consolidated sample.
An experimental investigation on the water retention behaviour of a silty soil for the computation of the lateral earth thrust on a retaining wall
Authors: Speranza Gianluca , Ferrari Alessio , Pousse Maxime , Laloui Lyesse
Published: June 2019

Retaining structures often interact with soils in unsaturated conditions and their performance is influenced by environmental actions. Currently, geotechnical analysis and design approaches mainly consider the soils either totally dry or totally saturated. Environmental actions, like infiltration due to rainfall, can significantly affect the lateral earth pressure of soils, influencing the performance of both temporary or permanent retaining structures. This paper deals with the investigation of the water retention behaviour of a silty soil for the computation of the soil thrust on a retaining wall during rainfall events. In this regard, the retention property of the involved geomaterial is investigated in laboratory through the combined use of high capacity tensiometers (HCT) and a dew-point hygrometer (WP4C). Considering drying and wetting paths, the experimental results are employed to calibrate the water retention behaviour for the computation of the failure shear strength of the geomaterial. The importance to monitor volume change during the characterization of the water retention behaviour of fine soils is highlighted. A series of analytical uncoupled hydro-mechanical analyses is performed to estimate the changing in the thrust of an unsaturated soil on a retaining wall under several infiltration rates. An appropriate modelling of the soil water retention behaviour is resulted to be crucial for the computation of lateral earth thrust.
Effect of Suction on the Drained Seismic Compression of Unsaturated Sand
Authors: Rong Wenyong , McCartney John S.
Published: June 2019

Backfill soils in many geotechnical applications are compacted and are likely to be in an unsaturated state during operation. In earthquake-prone areas, seismic compression of unsaturated backfill soils should be understood as small settlements may have significant impacts on the performance of overlying infrastructure like bridge decks, roadways, or railways. Accordingly, the goal of this paper is to describe the results from a series of constant suction, drained, cyclic simple shear tests on unsaturated sands subjected to a range of shear strain amplitudes. A new cyclic simple shear apparatus was developed that involves control of the matric suction and monitoring of changes in degree of saturation using the hanging column approach along with monitoring of the matric suction using an embedded tensiometer.
The influence of particle breakage on stress-dilatancy relationship for granular soils
Authors: Szypcio Zenon
Published: June 2019

The influence of particle breakage on soil behaviour is important from theoretical and practical perspectives. Particle breakage changes the internal energy in two ways. First, internal energy is consumed for particle crushing and second, the internal energy changes because of additional volumetric strain caused by particle crushing. These two effects may be quantified by use of Frictional State Theory. The analysed drained triaxial compression tests of Toyoura sand, gravel and Dog's Bay sand at different stress level and stress path revealed that the effect of particle breakage is a function of soil gradation, strength of soil grains, stress level and stress path.
AE Signature Interpretation of Single Particle Crushing under Uniaxial Compression
Authors: Luo Sha , Ibraim Erdin , Diambra Andrea
Published: June 2019

Granular soils exhibit particle crushing under certain loading circumstances, and it significantly affects their mechanical behaviour. However, the estimation of the particle crushing is extremely challenging. Therefore, new a technic based on passive non-destructive Acoustic Emission (AE) monitoring is explored to infer the extent and evolution of soil's particle size distribution. However, in this paper only individual particles under uniaxial compression are studied and the results should inform the interpretation of the laboratory tests on small scale soil samples. Different material types from rigid to soft and brittle to ductile are used in order to probe the AE characteristics and deduce the AE signature attached to various particle crushing mechanisms. The particle size and material type are the main parameters considered, and clear variation of the AE signal characteristics are detected. These encouraging findings on the use of AE monitoring system offer the possibility to identify the micro crushing event of soil particle in the macro soils.