bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miniaturized impedance inverter 2.4 GHz filter with optimal transmission zeroes
Authors: Soleiman Meiguni Javad , Mazdarani Alireza 
Published: June 2018

AbstractA compact bandpass microstrip filter with high selectivity capability is fully investigated in this article. The basic characteristics, circuit models, and design formulas are explained completely. This technique provides more freedoms for putting the transmission zeroes with negative coupling structures in appropriate frequencies and leads to highly selective, low profile and compact filters. To validate the procedure, 3 design examples based on impedance inverter (K), admittance inverter (J) and λ/4 resonators are presented. All of the filters operate at 2.4 GHz with the fractional bandwidth more than 10% but different values in source–resonator–load couplings. The latter is obtained by tilting the middle J‐inverter toward the main line. For tilt‐angle equal to 90°, more than 50 dB null‐depth has been achieved in filters stop‐band near 8% of passband edges showing the appropriate figure of merit for this symmetrical filter. Simulated results performed by CST Microwave Studio and measured results are in good agreement with the theoretical peers.
A compact UWB‐BPF based on microstrip‐to‐CPW transition with multiple transmission zeros
Authors: Ghazali Abu Nasar , Sazid Mohd , Virdee Bal 
Published: June 2018

AbstractA hybrid microstrip‐to‐coplanar waveguide (CPW) based broadside coupled ultra‐wideband (UWB) bandpass filter (BPF) of compact nature with multiple transmission zeros (TZ) is proposed. The CPW in ground consists of a short circuited multiple mode resonator (MMR), which is in conjugation with two microstrip lines on the top, arranged in back‐to‐back manner. Initially, the impedance ratio of the MMR is adjusted to place its resonant modes quasi‐equally within the UWB passband and later the dimensions of microstrip lines are optimized to enhance the broadside coupling. The setup generates a passband with reduced insertion loss, small group delay and multiple TZ. The presence of TZs provide sharp roll‐offs at either passband edges and a wide stopband. The experimental BPF is fabricated and its measured data validated against simulation results. The proposed structure measures 14.6 × 9.6 mm2.
Analytical expression for calculating large‐signal gain of RF power amplifiers
Authors: Guezzen Fethi , Tamoum Mohammed , Allam Rachid 
Published: June 2018

AbstractThis article provides simplified analytical expressions and methodology for predicting the power gain and output power of RF LDMOSFET power amplifier. This method avoids the use of the complex nonlinear device models and Harmonic Balance circuits simulators. For validation of our method, a 2.5 GHz‐10 W RF power amplifier is implemented. The measured, simulated and calculated results match very well.
High‐gain and wideband aperture coupled feed patch antenna using four split ring resonators
Authors: Yoon Na Nae , Ha‐Van Nam , Seo Chulhun 
Published: June 2018

AbstractIn this article, a high‐gain and wideband antenna that is adapted arrays of four split ring resonators (4SRRs) in S‐band was proposed. An aperture‐coupled patch array antenna was designed with wideband characteristics and arrayed in the 4 × 1 with high‐gain characteristics. To increase the gain more, arrays of 4SRRs based on metamaterial were used. The proposed metamaterial unit cell consists of four split ring resonators and an embedded capacitor to control the frequency characteristics easily. The proposed metamaterial's permeability was found to be near to zero. The proposed 4SRRs was arrayed and applied to the aperture‐coupled patch array antenna. The proposed arrays 4SRRs resonators improve the antenna gain by 2 dB, between 3 and 3.4 GHz.
Compact 3‐D eight elements UWB‐MIMO array
Authors: Khan M. S. , Rigobello F. , Ijaz Bilal , Autizi E. , Capobianco A. D. , Shubair R. , Khan S. A. 
Published: June 2018

AbstractAn eight elements, compact, ultra‐wideband multiple‐input‐multiple‐output (MIMO) 3‐D antenna array is reported. The proposed antenna system consists of eight monopole radiators, four elements are designed in planar configuration and four elements are placed perpendicularly to the planar configuration. Four elements are provided with a U‐shaped slot to match the input impedance over the entire bandwidth. All the monopoles are placed strategically to exploit polarization diversity which is believed to improve isolation. Good impedance matching and isolation higher than 15 dB are observed over the 3‐11 GHz frequency range. The proposed MIMO antenna array has a total size of 50
50
25 mm3 and measurements of prototype printed on a 1.524 mm thick Rogers TMM4 laminate resulted in good agreement with full wave numerical simulations. The proposed design provides high degree of isolation without compromise on compactness and also operated over wideband.
Design of ultra wide‐bandwidth double‐layer electromagnetic wave absorbers with square‐loop frequency selective surfaces
Authors: Liu Tian , Kim Sung‐Soo 
Published: June 2018

AbstractA thin and ultra wide‐bandwidth microwave absorber is demonstrated theoretically and experimentally through simple layering 2 square loop‐frequency selective surfaces (SL‐FSSs) with different geometries on a grounded dielectric substrate. The circuit parameters of the SL‐FSS inductance (L) and capacitance (C) are retrieved using the equivalent circuit model and are utilized in the design of the wide bandwidth absorber. The L and C values increase with increases in the unit cell dimension, and thereby the absorption frequency band can be controlled by the SL‐FSS geometries. The optimal control for the surface resistance of the SL‐FSSs and the spacer (assumed by air) thickness of the double‐layer absorber provide a 10 dB absorption bandwidth of 6.3–38.3 GHz with a total thickness of 6.4 mm. The free‐space measurement with the test samples fabricated by the screen printing process provides a still wide bandwidth of 5.6–30.8 GHz with the same total thickness.
Compact MIMO antenna for application to smart glasses using T‐shaped ground plane
Authors: Ryu Jongin , Kim Hyeongdong 
Published: June 2018

AbstractA compact multiple‐input multiple‐output (MIMO) antenna design for application to smart glasses is proposed in this letter. The proposed MIMO antenna system is comprised of two symmetrical meander antennas operating in the 2.4‐GHz wireless local area network band and a T‐shaped ground for high isolation. The operation mechanism of the proposed MIMO antennas can be explained using the analysis of a three‐port network. Accordingly, the T‐shaped ground plane operates as a decoupling structure such that the isolation between antennas can be controlled by tuning the T‐shaped ground plane. The reflection coefficient characteristic was measured to be less than −7.5 dB, whereas the isolation obtained was higher than 15 dB. The diversity performance was evaluated using the measured three‐dimensional radiation patterns, and the envelope correlation coefficients in the target band were less than 0.1.
Experimental results of the multi‐Gbps smartphone with 20 multi‐input multi‐output (MIMO) antennas in the 20 × 12 MIMO operation
Authors: Tsai Chih‐Yu , Wong Kin‐Lu , Li Wei‐Yu 
Published: June 2018

AbstractIt is experimentally demonstrated that 20 multi‐input multi‐output (MIMO) antennas operated in 3.5‐GHz band (3400∼3600 MHz) with acceptable antenna performance and low envelope correlation coefficients (ECCs < 0.1) can be embedded in the smartphone for fifth‐generation (5G) or future mobile communications. Additionally, in a 20 × 12 MIMO system with 12 transmitted MIMO streams, it is shown that the 20‐antenna smartphone as a receiver can achieve 5.5‐Gbps data throughput with 100‐MHz bandwidth (3450∼3550 MHz). That is, the smartphone can have a spectral efficiency of 55 bps/Hz. With the user's hand holding the 20‐antenna smartphone, about 5.3‐Gbps data throughput in the 20 × 12 MIMO operation can still be obtained, indicating that stable multi‐Gbps smartphone is promising to obtain. Details of the 20‐antenna smartphone for MIMO operation are described. Experimental results of the 20‐antenna smartphone in the 20 × 12 MIMO operation including the user's hand presence scenario are also presented and discussed.
Design and analysis of wideband composite antenna with dual‐sense circular polarization characteristics
Authors: Sahu Nikesh Kumar , Sharma Anand , Gangwar Ravi Kumar 
Published: June 2018

AbstractIn this article, a dual‐sense circularly polarized (CP) hybrid antenna is reported. The proposed hybrid antenna comprises of an asymmetrical square ring‐shaped printed line and a rectangular dielectric resonator (RDR). The asymmetricity present in the square ring is responsible for creating CP radiation with the opposite sense characteristics in the proposed antenna. Also, modified printed ring is used to excite TE111 mode in the loaded RDR. This loading enhances the overall impedance bandwidth of the proposed antenna. For practical verification, a prototype of the proposed antenna is fabricated and tested. The measured outcomes indicate a close concurrence with the simulated outcomes. The proposed antenna works over the frequency range 3.28 GHz–5.78 GHz with a fractional bandwidth of 55.18%. Dual CP wave with dual‐sense characteristics (Axial Ratio < 3 dB) are created in the frequency range 3.81–4.28 GHz and 4.98–5.28 GHz respectively. These responses make the proposed antenna suitable for WLAN and WiMAX applications.
A novel multifrequency mobile phone antenna with circularly polarized GPS application
Authors: Xi Lei , Zhai Huiqing , Li Long 
Published: June 2018

AbstractA novel multifrequency mobile phone antenna with circularly polarized Global Position System (GPS) application is presented in this research. The antenna is composed of a gradient T‐type feedline and a ring‐metal patch with 4 different branches. Specifically, T‐shaped feedline and the ring‐metal patch are contributed to resonate in 1300 MHz‐1900 MHz. Meanwhile, the phase difference generated by the four branches of varying lengths, the antenna produces circular polarization at 1575 MHz. The etching slot in the patch can make the antenna work in 2400 MHz–2700 MHz. The experimental results verify the simulations. The designed antenna can be covered in Global System for Mobile Communications/Digital Communication System/GPS/Long Term Evolution/Wireless Local Area Network/Worldwide Interoperability for Microwave Access and other system operating frequency bands, which is suitable for the current multisystem mobile phone.
Inverted L‐notch loaded hexa band circular patch antenna for X, ku/K band applications
Authors: Singh Vivek , Mishra Brijesh , Dwivedi Ajay Kumar , Singh Rajeev 
Published: June 2018

AbstractA novel hexa band circular shape patch antenna with four inverted L‐shape notches is proposed. The antenna results are discussed in terms of reflection coefficient, surface current density, radiation pattern (co and cross polarization), three‐dimensional gain distribution, and voltage standing wave ratio (VSWR). Measured resonating frequencies are observed at 11.6, 13.92, 17.11, 19.47, 21.11, and 23.05 GHz. Simulated gain of 7.39 dBi (11 GHz), 2.25 dBi (13.3 GHz), 6.65 dBi (16.6 GHz), 5.83 dBi (19 GHz), 6.02 dBi (20.6 GHz), and 7.31 dBi (22.2 GHz), respectively, is observed and the antenna is suitable for X‐band, Ku‐band, and K‐band applications. The performance of the proposed antenna is validated in terms of return loss (dB), VSWR, and radiation pattern by measurement.
Circularly polarized microstrip antenna with bidirectional radiation using dual‐layered arrow‐shape slot perturbation for CubeSat application
Authors: Lee Sunghee , Pyo Seongmin , Kim Jae‐Hyun 
Published: June 2018

AbstractThis article proposes a novel circularly polarized microstrip antenna supported with bidirectional opposite‐sense radiation using a dual‐layered arrow‐shaped slot perturbation. Unlike a conventional perturbation which is etched only on one side, the arrow‐shaped slot perturbation of the proposed antenna is divided into two diagonal half‐arrows and etched on both the top and bottom side. Consequently, the counter‐clockwise rotation of electric surface currents at the radiator side for right‐handed circular polarization and the clockwise rotation of those at the ground side for left‐handed circular polarization are successfully achieved. The measurement results of the proposed antenna show good agreement with the simulations of reflection coefficients, axial ratios, antenna gains, and radiation patterns.
Wide band compact coplanar waveguide with interdigital capacitor using left‐handed metamaterial
Authors: Yoon Ki‐Cheol , Ahn Seungyoung , Lee Jong‐Chul 
Published: June 2018

AbstractIn this article, a compact wide‐band transmission line (TL) with coplanar waveguide (CPW) using left‐handed metamaterial is presented. The proposed CPW TL has an interdigital capacitor and meander line inductor and shows compact size, low loss, and broad bandwidth. The proposed wide bandwidth CPW TL has a bandwidth of 180% from 12.03 to 30.0 GHz and a size of 1.46 × 3.43 mm2. Also, it shows insertion and return losses of 0.13 and 15.1 dB, respectively.
CEST MRI of sepsis‐induced acute kidney injury
Authors: Liu Jing , Han Zheng , Chen Guoli , Li Yuguo , Zhang Jia , Xu Jiadi , van Zijl Peter C.M. , Zhang Shuixing , Liu Guanshu 
Published: June 2018

Sepsis‐induced acute kidney injury (SAKI) is a major complication of kidney disease associated with increased mortality and faster progression. Therefore, the development of imaging biomarkers to detect septic AKI is of great clinical interest. In this study, we aimed to characterize the endogenous chemical exchange saturation transfer (CEST) MRI contrast in the lipopolysaccharide (LPS)‐induced SAKI mouse model and to investigate the use of CEST MRI for detecting such injury. We used a SAKI mouse model that was generated by i.p. injection of 10 mg/kg LPS. The resulting kidney injury was confirmed by the elevation of serum creatinine and histology. MRI assessments were performed 24 h after LPS injection, including CEST MRI at different B1 strengths (1, 1.8 and 3 μT), T1 mapping, T2 mapping and conventional magnetization transfer contrast (MTC) MRI. The CEST MRI results were analyzed using Z‐spectra, in which the normalized water signal saturation (Ssat/S0) is measured as a function of saturation frequency. Substantial decreases in CEST contrast were observed at both 3.5 and − 3.5 ppm frequency offset from water at all B1 powers, with the most significant difference obtained at a B1 of 1.8 μT. The average Ssat/S0 differences between injured and normal kidneys were 0.07 (0.55 ± 0.04 versus 0.62 ± 0.04, P = 0.0028) and 0.07 (0.50 ± 0.04 versus 0.57 ± 0.03, P = 0.0008) for 3.5 and − 3.5 ppm, respectively. In contrast, the T1 and T2 relaxation times and MTC contrast in the injured kidneys did not show a significant change compared with the normal control. Our results showed that CEST MRI is more sensitive to the pathological changes in injured kidneys than the changes in T1, T2 and MTC effect, indicating its potential clinical utility for molecular imaging of renal diseases.
Essential considerations in developing attention control groups in behavioral research
Authors: Aycock Dawn M. , Hayat Matthew J. , Helvig Ashley , Dunbar Sandra B. , Clark Patricia C. 
Published: June 2018

ABSTRACTAttention control groups strengthen randomized controlled trials of behavioral interventions, but researchers need to give careful consideration to the attention control activities. A comparative effectiveness research framework provides an ideal opportunity for an attention control group as a supplement to standard care, so participants potentially receive benefit regardless of group assignment. The anticipated benefit of the control condition must be independent of the study outcome. Resources needed for attention control activities need to be carefully considered and ethical considerations carefully weighed. In this paper we address nine considerations for the design and implementation of attention control groups: (1) ensure attention control activities are not associated with the outcome; (2) avoid contamination of the intervention or control group; (3) design comparable control and intervention activities; (4) ensure researcher training to adequately administer both treatment arms; (5) design control activities to be interesting and acceptable to participants; (6) evaluate attention control activities; (7) consider additional resources needed to implement attention control activities; (8) quantifying the effects of attention control and intervention groups; and (9) ethical considerations with attention control groups. Examples from the literature and ongoing research are presented. Careful planning for the attention control group is as important as for the intervention group. Researchers can use the considerations presented here to assist in planning for the best attention control group for their study.
Teachers as obligated bystanders: Grading and relating administrator support and peer response to teacher direct intervention in school bullying
Authors: Farley Jennifer 
Published: June 2018

AbstractThis study applied a theory of bystander intervention to teachers and has proven to have much utility in understanding how other bystanders may influence a teacher's direct intervention in instances of school bullying. Middle‐school teachers (n = 63) completed an online survey, which utilized video scenarios, and quantitative methods were utilized in analysis. Factors analyzed in relation to direct intervention included teacher accuracy in identifying bullying behavior, intended teacher response, perception of administrator support and peer response, and self‐efficacy. Results indicate that peer response (F(8, 58) = 6.067, p = .014) and administrator support (F(14, 58) = 6.515, p = .009) have significant impact on a teacher's direct intervention in incidents of school bullying. Results also suggest that all teachers do not perceive administrator support or effective peer response in incidents of school bullying.
Quantitative Secretomics Reveals Extrinsic Signals Involved in Human Pluripotent Stem Cell Cardiomyogenesis
Authors: Wolling Hanna , Konze Sarah A. , Höfer Anne , Erdmann Jelena , Pich Andreas , Zweigerdt Robert , Buettner Falk F. R. 
Published: June 2018

AbstractHuman pluripotent stem cells can be differentiated in vitro into cardiomyocytes (CMs) but the molecular mechanisms behind this process are still not fully understood. In particular, the identification of morphogens remained elusive because the mass spectrometry–based identification of secreted proteins from cell culture supernatants is impeded by high levels of albumin present in common differentiation media. An albumin‐free cardiomyogenic differentiation medium is established in this study and applied for secretomics at seven different time points during in vitro differentiation. By this analysis 4832 proteins are identified with 1802 being significantly altered during differentiation and 431 of these are annotated as secreted. Numerous extrinsic components of Wnt, TGFβ, Activin A, Nodal, BMP, or FGF signaling pathways are quantitatively assessed during differentiation. Notably, the abundance of pathway agonists is generally lower compared to the respective antagonists but their curves of progression over timer were rather similar. It is hypothesized that TGFβ, Activin A, and Nodal signaling are turned down shortly upon the initiation of cardiac differentiation whereas BMP signaling is switched on. Wnt and FGF signaling peaks between d0 and d3 of differentiation, and interestingly, Activin A and TGFβ signaling seem to be reactivated at the cardiac progenitor stages and/or in early CMs.
Predicting solvent effects in ionic liquids: Extension of a nucleophilic aromatic substitution reaction on a benzene to a pyridine
Authors: Hawker Rebecca R. , Haines Ronald S. , Harper Jason B. 
Published: June 2018

AbstractA nucleophilic aromatic substitution reaction involving a halopyridine electrophile was examined in a series of ionic liquid solvents. This reaction was chosen to test the known solvent effects of ionic liquids on this type of reaction mechanism, previously described with a halobenzene electrophile. The effect of varying the proportion of the ionic liquid in solution was determined, and it was shown that the more ionic liquid present in the reaction mixture, the greater the rate constant enhancement. Temperature‐dependent kinetic analyses yielded activation parameters that showed that the rate constant enhancements are controlled by a balance between enthalpic and entropic effects, depending upon the proportion of ionic liquid present. Overall, the rate enhancement is entropically driven, due to organisation of the ionic liquid about the electrophile. These results are consistent with what has been observed previously for the nucleophilic aromatic substitution reaction involving a halobenzene electrophile, demonstrating that the solvent effects observed for ionic liquids are general for this type of reaction mechanism and opening the possibility for extending their use through rational selection for reaction control.
Naturalistically observing noncancer conversations among couples coping with breast cancer
Authors: Robbins Megan L. , Karan Alexander , López Ana María , Weihs Karen L. 
Published: June 2018

AbstractObjectiveThis study revealed the landscape of noncancer conversations, identifying topics and types of everyday conversation, and examined links to psychological adjustment among couples coping with breast cancer.MethodsFifty‐two couples wore the Electronically Activated Recorder (EAR) over 1 weekend and self‐reported psychological adjustment while patients were on treatment. The EAR sampled 50 s of ambient sound every 9 minutes to estimate the frequency of noncancer conversation and reveal topics and types of conversation.ResultsAnalyses revealed noncancer conversations comprised over 93% of conversations. The most common topic discussed was people. Substantive conversation was associated with better, while emotional disclosure was associated with worse, well‐being for patients, but not spouses.ConclusionsResults revealed that ordinary conversations are frequent among couples who face breast cancer, and they are associated with patients' psychological adjustment, providing a foundation for potential interventions for coping with cancer that do not focus on illness.