bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance of 6 Different Global Navigation Satellite System Receivers at Low Latitude Under Moderate and Strong Scintillation
Authors: de Paula E. R. , Martinon A. R. F. , Moraes A. O. , Carrano C. , Neto A. C. , Doherty P. , Groves K. , Valladares C. E. , Crowley G. , Azeem I. , Reynolds A. , Akos D. M. , Walter T. , Beach T. L. , Slewaegen J.‐M.
Published: December 2020

After sunset, in the equatorial regions ionospheric plasma irregularities are generated due to the generalized Rayleigh‐Taylor instability. Under favorable conditions these irregularities develop in the equatorial region while mapping along the magnetic field lines giving rise to large plasma depletion structures called Equatorial Plasma Bubbles with embedded smaller structures on their walls. The global navigation satellite system (GNSS) L1 band frequency is sensitive to irregularities of the size of 300–400 m in the first Fresnel zone, which cause scattering and diffraction of the signal and produce amplitude and/or phase scintillation. Severe scintillation of GNSS signals can in turn cause loss of lock of the receiver code and/or carrier loops. As a result, GNSS navigation and positioning solution can be adversely affected by the ionospheric scintillation. There are multiple GNSS receivers designed to monitor scintillations. These receivers are based on different hardware designs and use different methodologies to process the raw data. When using simultaneous data from different GNSS scintillation monitors it is important to evaluate and compare their performances under similar scintillation conditions. The scintillation monitoring techniques may be useful for many applications that use GNSS signal. The aim of this work is to evaluate the performance of six different GNSS receivers located at São José dos Campos (23.1°S, 45.8°W, dip latitude 17.3°S) during moderate and strong scintillation activity. The amplitude (S4) and phase (σϕ) scintillation indexes from these receivers were analyzed and compared for the nights February 20–21 and November 27–28, 2013.
Influence of High Latitude Sudden Stratospheric Warming on Tropical Weather: Observations From a 205 MHz Stratosphere Troposphere Radar and Surface Meteorological Parameters
Authors: Remya R. , Manoj M. G. , Rakesh V. , Mohanakumar K. , Sivan C.
Published: December 2020

The study illustrates the evidence of dynamical coupling between the high‐latitude sudden stratospheric warming (SSW) events that occurred in three consecutive winter seasons and the concomitant changes in the wind pattern in the lower stratosphere and troposphere observed with a state‐of‐the‐art 205 MHz stratosphere‐troposphere wind profiling Radar, located at Cochin (10.03°N, 77.33°E), a tropical station in southwest peninsular India. Associated with the occurrence of SSW, the tropical region experiences a change in zonal wind speed and direction at upper tropospheric altitudes after the central day of warming. The zonal wind in the troposphere also reversed its prevailing direction. Downward propagation of zonal wind during the SSW period is noticed, which is also supported by the reanalysis data set. In the lower troposphere, vertical wind experienced sudden fluctuations with varying amplitudes soon after the peak day of the SSW event. The surface meteorological parameters in an area (8°–12°N, 74°–78°E), centered at Cochin, from ERA‐Interim are also examined. An abrupt fall in outgoing longwave radiation, followed by convection and unusual rainfall in the tropical region 5–6 days before the peak of SSW events, is a unique and exciting feature noted in the study. Detailed analysis of the past 20 years of SSW events confirmed the observational evidence of unusual rainfall over the low latitude region related with the onset of SSW. Comprehensive observational and numeric modeling studies are needed to understand the mechanism for the SSW events in high latitudes and the associated convective activity and precipitation in the low latitude region.
Increased Turbulence in the Eurasian Upper‐Level Jet Stream in Winter: Past and Future
Authors: Lv Yanmin , Guo Jianping , Li Jian , Han Yi , Xu Hui , Guo Xiaoran , Cao Lijuan , Gao Wenhua
Published: December 2020

Anthropogenic activities have been increasingly strengthening the meridional temperature gradient in the upper atmosphere, which has a profound impact on the wind shear and turbulence in mid‐latitudes. Here we examined the trends of the wintertime jet stream and clear‐air turbulence at 250 hPa over the Eurasian. The zonal wind speed showed a significantly increasing trend in the region between 40°N and 60°N where the meridional temperature gradient between the equator and the pole were increasing sharply in the past 4 decades (1980–2019). In addition, there existed a clear trend toward stronger vertical shear at 250 hPa in the latitudinal zone between 30°N and 40°N where the zonal wind increased, while a declining trend was shown to the south of 30°N, according to three different reanalysis datasets, including ERA5, JRA55, and NCAR/NCEP, which may be related to the poleward shift of the subtropical jet stream. The turbulence, closely related to the occurrence of vertical wind shear, was found to become stronger in the latitudinal zone between 30°N and 40°N consequently. The projections based on Phase 6 of Coupled Model Intercomparison Project models show that the zonal wind speed in the mid‐latitudes will increase significantly for the period 2015–2100, especially between the latitudinal zone between 40°N and 60°N, and the corresponding vertical wind shear in this area tend to dramatically increase. The findings not only help us better understanding of turbulence occurrence in the past 40 years, but also have profound implications for the projection of turbulence occurrence under global warming over mid‐latitude regions of North Hemisphere.
Pore Size Distribution Controls Dynamic Permeability
Authors: Li Jimmy X. , Rezaee Reza , Müller Tobias M. , Sarmadivaleh Mohammad
Published: December 2020

Probing the flow permeability of porous media with elastic waves is a formidable challenge, also because the wave‐induced oscillatory motion renders the permeability frequency dependent. Existing theoretical models for such a dynamic permeability assume that the frequency dependence is primarily controlled by a single characteristic length scale of the pore space. However, the fact that in most natural porous media there exists a distinct range of pore sizes is ignored. To overcome this limitation, we develop a dynamic permeability model that explicitly incorporates the pore size distribution. We show that the pore size distribution has a first‐order effect on the dynamic permeability. Since the pore size distribution can be deduced from techniques such as nuclear magnetic resonance, our results indicate the possibility to jointly use remote‐sensing technologies for improved permeability determination and cross‐fertilization of laboratory and in‐field techniques.
Assessing the Influence of COVID‐19 on the Shortwave Radiative Fluxes Over the East Asian Marginal Seas
Authors: Ming Yi , Loeb Norman G. , Lin Pu , Shen Zhaoyi , Naik Vaishali , Singer Clare E. , Ward Ryan X. , Paulot Fabien , Zhang Zhibo , Bellouin Nicolas , Horowitz Larry W. , Ginoux Paul A. , Ramaswamy V.
Published: December 2020

The Coronavirus Disease 2019 (COVID‐19) pandemic led to a widespread reduction in aerosol emissions. Using satellite observations and climate model simulations, we study the underlying mechanisms of the large decreases in solar clear‐sky reflection (3.8 W m−2 or 7%) and aerosol optical depth (0.16 W m−2 or 32%) observed over the East Asian Marginal Seas in March 2020. By separating the impacts from meteorology and emissions in the model simulations, we find that about one‐third of the clear‐sky anomalies can be attributed to pandemic‐related emission reductions, and the rest to weather variability and long‐term emission trends. The model is skillful at reproducing the observed interannual variations in solar all‐sky reflection, but no COVID‐19 signal is discerned. The current observational and modeling capabilities will be critical for monitoring, understanding, and predicting the radiative forcing and climate impacts of the ongoing crisis.
High Altitude Echoes From the Equatorial Topside Ionosphere During Solar Minimum
Authors: Derghazarian S. , Hysell D. L. , Kuyeng K. , Milla M. A.
Published: December 2020

We describe a new class of nonthermal plasma density irregularities observed in the postmidnight topside equatorial ionosphere under low solar flux conditions. They are distinct from irregularities associated with equatorial spread F (ESF) in terms of their morphology and because they exhibit strong spectral sidebands at the lower‐hybrid frequency. The coherent echoes were observed in a series high‐altitude radar experiments performed at Jicamarca utilizing long‐ and coded double‐pulse modes and a dual‐beam mode. The coded double‐pulse mode was used to measure the low‐frequency characteristics of the echoes with fine range resolution. Doppler shifts of the main backscatter line were observed to fall between ±150 m/s. The long‐pulse mode was employed for high‐frequency spectral analysis which revealed the presence of strong spectral sidelobes at the lower‐hybrid frequency. A dual‐beam mode was used to investigate the horizontal structure of the echoes. Zonal drift speeds of 50–70 m/s were inferred with this mode, and longitudinal dimensions of approximately 270 km were estimated. The study summarizes with a discussion of different mechanisms that may be responsible for the phenomenon and the lower‐hybrid sidebands in particular.
Propagation of Ultralow‐Frequency Waves from the Ion Foreshock into the Magnetosphere During the Passage of a Magnetic Cloud
Authors: Takahashi Kazue , Turc Lucile , Kilpua Emilia , Takahashi Naoko , Dimmock Andrew , Kajdic Primoz , Palmroth Minna , Pfau‐Kempf Yann , Soucek Jan , Motoba Tetsuo , Hartinger Michael D. , Artemyev Anton , Singer Howard , Ganse Urs , Battarbee Markus
Published: December 2020

We have examined the properties of ultralow‐frequency (ULF) waves in space (the ion foreshock, magnetosheath, and magnetosphere) and at dayside magnetometer stations (L = 1.6–6.5) during Earth's encounter with a magnetic cloud in the solar wind, which is characterized by magnetic fields with large magnitudes (∼14 nT) and small cone angles (∼30°). In the foreshock, waves were excited at ∼90 m Hz as expected from theory, but there were oscillations at other frequencies as well. Oscillations near 90 mHz were detected at the other locations in space, but they were not in general the most dominant oscillations. On the ground, pulsations in the approximate Pc2–Pc4 band (5 mHz–120 mHz) were continuously detected at all stations, with no outstanding spectral peaks near 90 mHz in the H component except at stations where the frequency of the third harmonic of standing Alfvén waves had this frequency. The fundamental toroidal wave frequency was below 90 mHz at all stations. In the D component spectra, a minor spectral peak is found near 90 mHz at stations located at L < 3, and the power dropped abruptly above this frequency. Magnetospheric compressional wave power was much weaker on the nightside. A hybrid‐Vlasov simulation indicates that foreshock ULF waves have short spatial scale lengths and waves transmitted into the magnetosphere are strongly attenuated away from noon.
Modeling the GABLS4 Strongly‐Stable Boundary Layer With a GCM Turbulence Parameterization: Parametric Sensitivity or Intrinsic Limits?
Authors: Audouin O. , Roehrig R. , Couvreux F. , Williamson D.
Published: December 2020

The representation of stable boundary layers (SBLs) still challenges turbulence parameterizations implemented in current weather or climate models. The present work assesses whether these model deficiencies reflect calibration choices or intrinsic limits in currently‐used turbulence parameterization formulations and implementations. This question is addressed for the CNRM atmospheric model ARPEGE‐Climat 6.3 in a single‐column model/large‐eddy simulation (SCM/LES) comparison framework, using the history matching with iterative refocusing statistical approach. The GABLS4 case, which samples a nocturnal strong SBL observed at Dome C, Antarctic Plateau, is used. The standard calibration of the ARPEGE‐Climat 6.3 turbulence parameterization leads to a too deep SBL, a too high low‐level jet and misses the nocturnal wind rotation. This behavior is found for low and high vertical resolution model configurations. The statistical tool then proves that these model deficiencies reflect a poor parameterization calibration rather than intrinsic limits of the parameterization formulation itself. In particular, the role of two lower bounds that were heuristically introduced during the parameterization implementation to increase mixing in the free troposphere and to avoid runaway cooling in snow‐ or ice‐covered region is emphasized. The statistical tool identifies the space of the parameterization free parameters compatible with the LES reference, accounting for the various sources of uncertainty. This space is non‐empty, thus proving that the ARPEGE‐Climat 6.3 turbulence parameterization contains the required physics to capture the GABLS4 SBL. The SCM framework is also used to validate the statistical framework and a few guidelines for its use in parameterization development and calibration are discussed.
Ensemble Methods for Neural Network‐Based Weather Forecasts
Authors: Scher Sebastian , Messori Gabriele
Published: December 2020

Ensemble weather forecasts enable a measure of uncertainty to be attached to each forecast, by computing the ensemble's spread. However, generating an ensemble with a good spread‐error relationship is far from trivial, and a wide range of approaches to achieve this have been explored—chiefly in the context of numerical weather prediction models. Here, we aim to transform a deterministic neural network weather forecasting system into an ensemble forecasting system. We test four methods to generate the ensemble: random initial perturbations, retraining of the neural network, use of random dropout in the network, and the creation of initial perturbations with singular vector decomposition. The latter method is widely used in numerical weather prediction models, but is yet to be tested on neural networks. The ensemble mean forecasts obtained from these four approaches all beat the unperturbed neural network forecasts, with the retraining method yielding the highest improvement. However, the skill of the neural network forecasts is systematically lower than that of state‐of‐the‐art numerical weather prediction models.
Impact of visuomotor feedback on the embodiment of virtual hands detached from the body
Authors: Seinfeld Sofia , Müller Jörg
Published: December 2020

It has been shown that mere observation of body discontinuity leads to diminished body ownership. However, the impact of body discontinuity has mainly been investigated in conditions where participants observe a collocated static virtual body from a first-person perspective. This study explores the influence of body discountinuity on the sense of embodiment, when rich visuomotor correlations between a real and an artificial virtual body are established. In two experiments, we evaluated body ownership and motor performance, when participants interacted in virtual reality either using virtual hands connected or disconnected from a body. We found that even under the presence of congruent visuomotor feedback, mere observation of body discontinuity resulted in diminished embodiment. Contradictory evidence was found in relation to motor performance, where further research is needed to understand the role of visual body discontinuity in motor tasks. Preliminary findings on physiological reactions to a threat were also assessed, indicating that body visual discontinuity does not differently impact threat-related skin conductance responses. The present results are in accordance with past evidence showing that body discontinuity negatively impacts embodiment. However, further research is needed to understand the influence of visuomotor feedback and body morphological congruency on motor performance and threat-related physiological reactions.
Diazanyl and SnO2 bi-activated g-C3N4 for enhanced photocatalytic CO2 reduction
Authors: Su Fengyun , Chen Yanli , Wang Ruiping , Zhang Sheng , Liu Kecheng , Zhang Yezhen , Zhao Wei , Ding Chenghua , Xie Haiquan , Ye Liqun
Published: December 2020

A bi-activated g-C3N4 were prepared by transforming surface amino groups to diazanyl groups and in situ deposing SnO2 for enhanced photocatalytic CO2 reduction by promoting CO2 capture and separation of photo-generated carriers.
Predictive Processing and Developmental Language Disorder
Authors: Jones Samuel David , Westermann Gert
Published: December 2020

Purpose

Research in the cognitive and neural sciences has situated predictive processing—the anticipation of upcoming percepts—as a dominant function of the brain. The purpose of this article is to argue that prediction should feature more prominently in explanatory accounts of sentence processing and comprehension deficits in developmental language disorder (DLD).

Method

We evaluate behavioral and neurophysiological data relevant to the theme of prediction in early typical and atypical language acquisition and processing.

Results

Poor syntactic awareness—attributable, in part, to an underlying statistical learning deficit—is likely to impede syntax-based predictive processing in children with DLD, conferring deficits in spoken sentence comprehension. Furthermore, there may be a feedback cycle in which poor syntactic awareness impedes children's ability to anticipate upcoming percepts, and this, in turn, makes children unable to improve their syntactic awareness on the basis of prediction error signals.

Conclusion

This article offers a refocusing of theory on sentence processing and comprehension deficits in DLD, from a difficulty in processing and integrating perceived syntactic features to a difficulty in anticipating what is coming next.
Autism and Neurodiversity: Addressing Concerns and Offering Implications for the School-Based Speech-Language Pathologist
Authors: DeThorne Laura S. , Searsmith Kelly
Published: December 2020

Purpose

The purpose of this article is to address some common concerns associated with the neurodiversity paradigm and to offer related implications for service provision to school-age autistic students. In particular, we highlight the need to (a) view first-person autistic perspectives as an integral component of evidence-based practice, (b) use the individualized education plan as a means to actively address environmental contributions to communicative competence, and (c) center intervention around respect for autistic sociality and self-expression. We support these points with cross-disciplinary scholarship and writings from autistic individuals.

Conclusions

We recognize that school-based speech-language pathologists are bound by institutional constraints, such as eligibility determination and Individualized Education Program processes that are not inherently consistent with the neurodiversity paradigm. Consequently, we offer examples for implementing the neurodiversity paradigm while working within these existing structures. In sum, this article addresses key points of tension related to the neurodiversity paradigm in a way that we hope will directly translate into improved service provision for autistic students.

Supplemental Material

https://doi.org/10.23641/asha.13345727
Distribution system reconfiguration in presence of Internet of things
Authors: Mohseni Moaiad , Joorabian Mahmood , Lashkar Ara Afshin
Published: December 2020

Network reconfiguration (NR) has undergone new changes to adapt to smart grid evolution. Internet of things (IoT) has found its way to smart grids especially in the distribution systems. Demand‐side management can be more efficient in the presence of IoT. IoT‐based energy management systems can have bidirectional communication with smart grids and decide according to their preferences, time‐of‐use (TOU) pricing, and their flexible devices. Therefore, customers would consume electricity more interactively. Consequently, the total load profile will be changed and a new NR approach must be adopted to meet load demands. So, the selection of critical switches must be modified to achieve the most effective network resource utilisation. For this purpose, a mixed‐integer linear programming model for feeder reconfiguration is presented considering the customers’ behaviours in the IoT environment. At first, the customer manner is investigated at different prices and preferences. Then the total load profile is calculated considering the normal distribution of uncertain customer preference factors. Finally, the identification of critical switches is obtained using the proposed method. The optimisation is done in YALMIP and MOSEK toolboxes. Results show the effectiveness of the proposed method to efficient utilisation of IoT potentials and renewable energy benefits.
Monitoring of power system dynamics under incomplete PMU observability condition
Authors: Ortiz Gabriel , Rehtanz Christian , Colomé Graciela
Published: December 2020

This work presents a hybrid state estimation procedure that allows power system dynamics associated to slow and fast transient events to be accurately monitored considering a limited amount of phasor measurement units. The proposal represents an enhanced version of a previously developed static state estimation approach. This time, two main changes are introduced. First, a weighted least absolute value estimator instead the conventional weighted least square technique is used to estimate bus voltages in transient regime. This makes the estimation process more robust at fast scan rates. Second, an extended Kalman filter based dynamic state estimator is integrated. Thus, the proposed scheme is able to estimate, along with static variables, dynamic variables of all generators and motors in the power system regardless of the availability of phasor measurement unit measurements at terminal buses. This is possible thanks to a novel data‐mining based methodology for full phasor measurement unit observability restoration. Performance parameters such as accuracy, computing time and convergence properties are assessed by applying the estimation procedure to the New England benchmark system under different operating conditions.
A content‐dependent Daltonization algorithm for colour vision deficiencies based on lightness and chroma information
Authors: Shen Xuming , Feng Jianhua , Zhang Xiandou
Published: December 2020

To help CVD (colour vision deficiency) observers distinguish among different colours in digital images, this study proposes a content‐dependent Daltonization algorithm based on lightness and chroma information. This improves the trade‐offs in contrast, naturalness, and colour consistency deficiencies found in existing methods. Chroma remapping and brightness adjustments on image content are utilized to increase contrast and maximize the preservation of the original hue. In a quantitative study, the proposed method proved more useful for dichromats than did existing methods. The evaluation by research subjects showed that the method was superior to the current methods in balancing contrast, naturalness, and colour consistency.
Meaningful ciphertext encryption algorithm based on bit scrambling, discrete wavelet transform, and improved chaos
Authors: Jing Shiwei , Guo Yuan , Chen Wei
Published: December 2020

This paper proposes a meaningful ciphertext encryption algorithm of good practicability and strong robustness. The plaintext undergoes pre‐encryption of bit scrambling and secondary encryption of discrete wavelet transform (DWT) to obtain meaningful ciphertext. In the pre‐encryption stage, only the higher three bit pages that are not all 0 or 1 are scrambled. The embedding method in the secondary encryption process is to add the hundreds and tens’ digit and ones’ digit of the middle ciphertext to the scrambled detail information obtained by DWT of the cover image. The information entropy of the intermediate ciphertext obtained by this method can reach 7.997, the correlation coefficient between the ciphertext and the cover image can reach 0.99, and the decrypted image of the ciphertext under high‐intensity pollution can still be identified. It shows that the pre‐encryption can conceal the plaintext information well, and the secondary encryption can eliminate the ciphertext texture characteristics while retaining the good robustness. Finally, the improved three one‐dimensional chaos are used to generate random sequences, and the plaintext hash value is associated with the chaotic key. The improved chaos greatly improves the randomness of the sequence and broadens the range of parameters. The hash value SHA‐256 of the plaintext is added to make the key stream adaptively change with the plaintext, which greatly improves the sensitivity of the plaintext and the ability to resist selected plaintext and ciphertext attacks. Experiments have also verified that the encryption algorithm can encrypt images of different types and shapes and has strong practicability, good bit scrambling effect, and high sensitivity to scrambling.
Artefact‐free image stitching via a better normed seam‐cutting energy function
Authors: Qiu Xiangyan , Li Qiaoliang
Published: December 2020

Image stitching, as the important field of computer graphics and vision, has received much attention in recent years. Image stitching techniques are generally decomposed into two phases: image alignment, which aligns target images with the reference images; and image composition, which fixes ghosting and visual artefacts. This work aims to propose a new strategy for the seam‐cutting method which provides visually appealing result. Seam‐cutting is one of the most influential methods in image composition, which can relieve artefacts and produce plausible results. However, it is observed that the state‐of‐the‐art seam‐cutting approaches usually lead to undesirable seams in some challenging scenes. Here, the authors put forward a novel seam‐cutting method by defining a new energy function. This method uses power of norm as a colour difference which can magnify the weight of colour distinction to avoid undesirable seams and artefacts. The proposed method can be easily implemented. The test images are collected from the public available challenging datasets and taken by ourselves. Experiments demonstrate that the proposed method can create comparable or even better stitching results compared to other state‐of‐the‐art seam‐cutting approaches.
Encapsulated virgin coconut oil as a nanoscale in vitro solution against multiple drug resistant Staphylococcus aureus
Authors: Talib A. , Manzoor K. N. , Ijaz A. , Adnan F. , Javed F. , Khan A. A.
Published: December 2020

Niosomes are excellent nanoscale vehicular systems that can carry a variety of drugs and (bioactive) compounds entrapped inside them. Virgin coconut oil (VCO) is the finest grade of coconut oil that is highly enriched with phenolic content, antioxidant activity and also comprises medium chain triglycerides. In this work, niosomes were encapsulated with VCO synthesized by a simple chemical method. The electron microscopy confirmed that spherical nanostructured lipid carrier molecules with a diameter in the range of 180–190 nm were produced. A zeta potential value of −42 mV was a testimony that these nanovehicles were having good stability. The natural oil loaded nanocarrier spheres proved to be potent antibacterial nano‐antibiotics against multiple drug resistant (MDR) bacteria. The antibacterial activity of these magic nano‐spheres was found to be better than ZnO (metallic oxides) nanoparticles. The nano‐antibiotics resulted in 17, 14 and 12 mm zones of inhibition against methicillin‐resistant Staphylococcus aureus (MRSA), vancomycin‐resistant S. aureus (VRSA) and a (general) MDR strain of S. aureus in contrast to nanoparticles that resulted in zones of inhibitions 7, 8 and 6 mm for the same bacterial strains. Niosomes prove to be an excellent nanocarrier system that can encapsulate a number of bio‐active compounds.
Lubrication of sliding silicon MEMS devices using ferrofluids‐based magnetic matrix texture
Authors: Tonggang Liu , Chhattal Muhammad , Kun You , Zili Lin
Published: December 2020

This paper aims to explore the possibility of using ferrofluids for the lubrication of MEMS devices under the influence of different magnetic field texture configurations. For the investigation of proposed work, a novel silicon‐based pin‐on‐disk friction pair is designed in such a way that it mimics MEMS devices. The ferrofluids‐based magnetic matrix texture was formed by low viscous ferrofluids and specially arranged thin cylindrical magnets matrix. For the investigation of the lubrication performance of ferrofluids lubricated specimens, tribological tests, and surface morphology analysis were carried out under different magnetic textures on a reciprocating tribometer and an optical microscope. The results show that the magnetic textures distributions on the friction‐pair have a significant influence on the lubrication properties of ferrofluids. This magnetic texture has the potential to properly position and retains the ferrofluids on friction‐pair, increase the load‐bearing capacity, and result in a significant reduction in wear and friction. The results also show that there exists the optimal magnetic matrix texture configuration which shows the best tribological performance when lubricated with ferrofluids.
Influence of thickness of SiO2 layer on the performance of SINW sensors
Authors: Wang Hui , Chen Shixing , Wang Yuelin , Li Tie
Published: December 2020

Silicon nanowire devices employed traditional MEMS technology has the advantages of low cost and easy to batch fabricated, which can be applied for high‐sensitivity biological and chemical species detection. In the preparation process, the device performance would be greatly influenced by the BOE corrosion process of silicon oxide outside silicon nanowires, which will define the performance of devices in subsequent test. In this paper, pH solution test was used to characterize the response sensitivity of silicon nanowires in different etching times, with the help of SEM and I–V characteristics before and after corrosion, it can be found that the thickness of silicon oxide layer enclosed nanowires was gradually reduced until completely etched in about five minutes to expose the silicon nanowires, which revealed that the silicon nanowires could start to sense and respond to external stimulus only when the silicon oxide was very thin even disappeared. The effect of corrosion could be equivalent to the influence of silicon oxide thickness on device performance. It provides an effective way to control the fabrication process of high performance devices.
In situ synthesis of metal‐free N‐GQD@g‐C3N4 photocatalyst for enhancing photocatalytic activity
Authors: Cao Yang , Sheng Luyang , Cheng He , Wang Congxue , Sun Youyi , Fu Qiang
Published: December 2020

Graphitic carbon nitride modified with N‐doped graphene quantum dot (N‐GQDs/g‐C3N4) was prepared by an in situ method, in which the g‐C3N4 was synthesized in the presence of N‐GQD. Furthermore, the structure and photocatalytic degradation performance of in situ synthesised N‐GQDs/g‐C3N4 were investigated and compared with N‐GQDs/g‐C3N4 prepared by traditional mixing method. The removal efficiency was about 98.0% for the photocatalytic degradation of RhB after 70 min, which was larger comparing with other GQDs/g‐C3N4 reported in previous works. The result was attributed to uniform distribution of N‐GQDs on surface of g‐C3N4, leading to more photogenerated electrons transfer. This work did not only report a new synthesis method of N‐GQDs/g‐C3N4, but also provided a new method to improve photodegradation performance of photocatalyst based on g‐C3N4.
Au/CQDs‐TiO2 composite nanorod array film with simple preparation route and enhanced visible light response
Authors: Wang Meiling , Jian Aoqun , Jia Huaping , Yang Ting , Zhang Xuming , Sang Shengbo
Published: December 2020

This paper successfully prepared a unique titanium dioxide nanorod arrays nanocomposite doped with carbon quantum dots and gold nanoparticles as a high‐efficiency photocatalyst. Due to their enhanced electron–hole separation efficiency and strong light‐scattering effects, one‐dimensional nanostructured titanium dioxide nanorods were utilised as the basic material for photocatalysis. Furthermore, gold nanoparticles and carbon quantum dots modified on the surface of titanium dioxide nanorods were used as visible light absorbers and photosensitisers, respectively. As a result, a photocurrent of 14 mA·cm‐2 was achieved by Au/CQDs‐TiO2 nanorods composite in the photoelectrochemical measurements, which exceed five times that of pure titanium dioxide nanorods. The synergistic effect of gold nanoparticles and carbon quantum dots was demonstrated by several characterisation techniques. The proposed Au/CQDs‐TiO2 nanorods nanocomposite film developed by simple successive ionic layer adsorption and reaction and hydrothermal methods offers a practical solution for current environmental and energy issues.
Preparation and electrochemical performance of chemical‐activated carbon foam
Authors: Wu Ye , Bao Wenyun , Xie Yibing , Yao Chen
Published: December 2020

Three‐dimensional porous carbon foam is fabricated by thermal pyrolysis of melamine foam and applied for energy storage electrode material. The increase of carbonization temperature is beneficial to improving graphitization degree and meanwhile lowing mechanical stability of carbon foam. KOH and Ni(NO3)2‐activated carbonization is applied to further improve graphitization of carbon foam, leading to the improved conductivity. The ohmic resistance declines from 305 Ω cm–1 for bare carbon foam to 198 Ω cm–1 for KOH‐activated one and 58 Ω cm–1 for Ni(NO3)2‐activated one. The specific capacitance increases from 0.371 mF cm–2 for bare carbon foam to 0.905 mF cm–2 for KOH‐activated one and 1.267 mF cm–2 for Ni(NO3)2‐activated one at the current density of 0.1 mA cm–2. The activation thermal carbonization can improve the electroactivity of carbon foam. The fractured framework lowers mechanical stability of the chemical‐activated carbon foams. Ni(NO3)2‐activated carbon foam shows higher graphitization degree and electrical conductivity than KOH‐activated one, accordingly contributing to higher electrochemical capacitance and rate capability. Ni(NO3)2‐activation become more effective to enhance graphitization degree of carbon foam.
A high‐power quality battery charger for light electric vehicle using switched inductor PFC converter
Authors: Kushwaha Radha , Singh Bhim
Published: December 2020

This work is focused on a new power quality improved battery charger for electric vehicle using a two switch power factor correction (PFC) single‐ended primary inductance converter (SEPIC) at the front‐end followed by a flyback converter. The single‐ended primary inductance converter is a high step‐up PFC converter with a switched inductor configuration at the input. Over a conventional single‐ended primary inductance converter, this new configuration operates with reduced duty ratio for a given DC‐link voltage. By using few additional components, this new single‐ended primary inductance converter offers reduced switch voltage stress to produce the same DC‐link voltage. The operation at lower duty cycle, gives the improved efficiency over a conventional SEPIC PFC converter. The built‐in advantage of soft switching in devices, is achieved due to discontinuous conduction mode based design for both power factor correction converter and flyback converter. The power quality improvement in charger is validated at steady state as well as under variation in input voltage and DC‐link voltage, to meet the IEC 61000‐3‐2 regulations. Performance of this charger is verified in constant current mode with high step‐up gain of power factor correction converter and lower stress across the devices over a conventional single‐ended primary inductance configuration.
A single‐stage step‐up inverter with reduced devices count
Authors: Hu Xuefeng , Liu Xing , Zhang Yujia , Yu Zhixiang , Li Yan , Yao Zhilei , Yang Yunhu
Published: December 2020

This study presents a single‐phase single‐stage step‐up inverter (SSSI), which can be used as an interface converter in micro‐source generation systems such as photovoltaic (PV) and fuel cells. The proposed inverter has several appealing features. (1) It can provide an AC output voltage higher than its DC input because of the built‐in boost circuit. (2) It has characteristics of a simple structure and reduces the component counts and cost. (3) The shoot‐through problem for the power devices can be avoided in the proposed SSSI. (4) metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) can be used without reverse recovery issues of body diodes. Therefore, high system reliability and efficiency can be obtained. This study describes the operating principles in discontinuous conduction mode (DCM), pulse‐width modulation strategy, and parameter design guidelines. In order to verify the feasibility and performance of the converter, experimental results are obtained from a lab prototype.
Research on balance control strategy of single capacitor clamped five‐level inverter clamping capacitor
Authors: Ye Manyuan , Wei Qiwen , Li Song , Ren Wei , Song Guizhi
Published: December 2020

A five‐level inverter composed of a single capacitor clamped three‐level topology and a half‐bridge is introduced, and a new SPWM control strategy for this topology is proposed. The strategy uses two modulation waves with opposite directions to modulate the positive and negative half‐cycle interleaved carriers. By controlling the charging and discharging times of the clamping capacitor in each carrier cycle, the voltage balance control of the clamping capacitor is achieved. At the same time, a single‐phase capacitor clamped five‐level inverter is taken as an example to analyse the principle of the capacitor balance control strategy in detail, and to verify the correctness and feasibility of the control strategy through simulation research and experimental results.
Small signal modelling and stability analysis of internal ramp compensated constant on‐time controller with improved output voltage accuracy for point of load application
Authors: Peng Kang , Chen Keng , Petruzzi Luca , Chen Min , Lee BangSup , Clavette Danny
Published: December 2020

This paper investigates a constant on‐time controller (COT) with internal ramp compensation and improved output voltage accuracy for point of load applications. The pulse width modulation (PWM) output is generated based on internal ramp: by sensing the regulated output voltage and comparing it to an internal reference target, an error signal is generated. This error signal is used to generate a reference for an added ramp signal, which is compared against an error voltage to generate a PWM trigger signal. An adaptive constant on‐time scheme ensures a fairly constant switching frequency over a wide range of input and output voltages. This COT control algorithm is able to achieve high accuracy regulation (±0.5% of target) and fast transient response during load step change. A frequency domain small signal model is proposed, and an open loop gain transfer function is developed for this COT control system. The proposed small signal model and design analyses are verified with SIMPLIS simulations and experimental results.
A new enhanced‐boost switched‐capacitor quasi Z‐source network
Authors: Hosseini Seyyed Majid , Ghazi Reza , Nikbahar Ali , Eydi Mohammad
Published: December 2020

This paper proposes a new enhanced‐boost non‐transformer‐based impedance source network. The strong boosting ability of the proposed topology is realized by making use of the switched capacitor concept in the formerly introduced enhanced‐boost quasi Z‐source network (EB‐qZSN) without any additional active switch. Meanwhile, the advantages of the EB‐qZSN such as input current continuity and shared ground between the input and the output are maintained. In addition to the lower shoot‐through requirement to obtain high voltage gains, the proposed impedance network takes advantage of a smaller size of passive components along with a lower input current ripple to achieve higher power density and higher efficiency. Moreover, the lower total rating of the switching elements, defined by switching device power, directly translates to lower cost for the proposed method. The operation principles and the design guideline of components are explained in detail and a thorough comparison with other ZSN is presented. A 240W DC–DC prototype converter was built to validate the performance principles and properties of the proposed impedance network.
The Outcome of Blood Transfusions in Conservative and Surgical Necrotizing Enterocolitis and Spontaneous Intestinal Perforation
Authors: Karila Kristiina , Koivusalo Antti
Published: December 2020

Introduction In necrotizing enterocolitis (NEC), blood transfusions (BTs) are a disputed factor concerning the etiology and the outcome. We assessed retrospectively the effects of preonset BT on the outcome of NEC and spontaneous intestinal perforation (SIP).

Materials and Methods With ethical consent, we reviewed the hospital records of 113 neonates from 2002 to 2019 with surgical NEC (NECs) (n = 57), conservatively treated NEC (NECc) (n = 20), and SIP (n = 36). The onset was defined as the day of surgery (NECs and SIP) or diagnosis (NECc). The effects of preonset BT (total, beyond 48 hours, and within 48 hours) were compared with the effects of birth weight (BW), gestational age (GA), intracerebral hemorrhage, respiratory distress syndrome, septicemia, and patent ductus arteriosus. Main outcome measure was 2-week mortality, and secondary measures were small intestinal loss and days on parenteral nutrition (PN).

Results Overall mortality (8.9%) was predicted independently by BT total and BT beyond 48 hours, risk ratio (RR) = 1.1 to 1.2 (95% confidence interval [CI] = 1.0–1.4), p = 0.01 to 0.02, and BW and GA, RR = 0.7 to 1.0 (95% CI = 0.5–1.0), p = 0.02 to 0.04. Mortality in NECs (12%) was predicted by BT total and BT beyond 48 hours only, RR = 1.1 to 1.2 (95% CI = 1.0–1.5), p = 0.03 to 0.04. BT within 48 hours of onset did not predict mortality. No factors were related with secondary outcome measures or with mortality in patients with SIP or NECc.

Conclusion In NECs, preoperative BT and BT given more than 48 hours before surgery were correlated with slightly increased 2-week mortality but not with small intestinal loss or duration of PN.
Histomorphological Assessment of Formalin versus Nonformalin Fixatives in Diagnostic Surgical Pathology
Authors: Shetty Jayaprakash Kubalady , Babu Hannah Fathima , Hosapatna Laxminarayana Kishan Prasad
Published: December 2020

Introduction Fixation is the critical step in the preservation of tissues in diagnostic pathology. The formalin is an economical and excellent fixative with the inherent property of adequate fixation. The well-established side effects of formalin include mucosal irritation, upper respiratory diseases, and corrosive injury to the gastrointestinal tract. In addition, substantial evidence exists regarding the potential role of formaldehyde as a human carcinogen. The carcinogenic and toxic effects of formalin encourage searching for alternative fixatives for tissue fixation. However, “the formalin dogma” has severely hampered the search for alternative fixatives for many years.

Material and Methods Ninety tissues of liver and skeletal muscle obtained during autopsies were immersed in adequate amounts of the following fixatives: formalin (10%), methyl alcohol (70%), and acetone (100%). The comparison among the three was made based on time for fixation, preservation of tissue architecture, cell borders, cytoplasm, nuclear contours, chromatin texture, and uniformity of staining.

Results The tissue preserved in formalin undergoes rapid fixation compared with alcohol and acetone. The tissue architecture, cell border characteristics of alcohol and acetone was found satisfactory compared with formalin. The cytoplasm and nuclear contour were superior with the formalin. The chromatin texture and uniformity of staining were similar with all the three fixatives.

Conclusion The formalin is considered superior to most of the parameters, whereas both methyl alcohol and acetone showed nearly equivalent scores. Hence, owing to the potential human health hazards and carcinogenicity of formalin, no rational reasons hamper the complete substitution of formalin with alternative fixatives such as alcohol and acetone in diagnostic pathology and medical research.
Spiky piñata-shaped gold nanoparticles optimized for cancer treatments
Authors: Johnson-Groh Mara
Published: December 2020

Researchers have discovered ways to improve gold nanoparticles to create targeted, personalized cancer treatments.
A Novel Imidazophenazine-Based Stimuli Responsive Chemosensor for Highly Selective and Sensitive Fluorescence Detection of CN
Authors: Shi Haixiong , Hou Juanjuan , Jiang Pengwei , Yang Quanlu , Lin Qi , Wei Taibao , Yao Hong , Zhang Youming , Wu Shang
Published: December 2020

A fluorescent imidazophenazine-based derivative (S) has been successfully synthesised, and can be used as a chemsensor for relay recognition of CN– in DMSO/H2O (7 : 3, v/v) solution, which exhibited external stimuli-responsiveness. The sensor immediately responded with obvious colour changes (from red to purple) and fluorescent quenching when CN– was added to the S solution. Its detection limit for CN– is 2.16 × 10−7 M. In addition, NMR spectroscopy and density function theory calculations were also used to confirm the recognition mechanism. In particular, the fluorescence responding circle could be repeated three times by the sequential addition of CN– and CH3COO– or CN– and HSO4–. Moreover, a CN– detection test paper was prepared using S, providing a convenient method for CN– identification.
Optimal utility and probability functions for agents with finite computational precision
Authors: Juechems Keno , Balaguer Jan , Spitzer Bernhard , Summerfield Christopher
Published: December 2020

Significance

When making economic decisions, humans can evaluate probabilities and magnitudes of outcomes in an idiosyncratic way that can lead to poor decisions. This suggests that the internal functions that map objective quantities onto subjective utilities are nonlinear. Here, we ask why utility functions take this form, making the assumption that human decisions are intrinsically variable (corrupted by noise). Using simulations, we show that the canonical nonlinear form of these functions maximizes reward and minimizes uncertainty for a noisy decision agent. We demonstrate in two experiments that humans adapt optimally to manipulations of outcome certainty. Thus, our results suggest that observed subjective functions may represent an optimal adaptation within the constraints imposed by biology.