bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Efficient and Stable Planar Perovskite Solar Cells with Modulated Diffusion Passivation Toward High Power Conversion Efficiency and Ultrahigh Fill Factor
Authors: Zhou Long , Lin Zhenhua , Ning Zhijun , Li Tao , Guo Xing , Ma Jing , Su Jie , Zhang Chunfu , Zhang Jincheng , Liu Shengzhong , Chang Jingjing , Hao Yue
Published: August 2019

2D/3D perovskite heterostructures or composites are recognized as efficient strategies to improve the stability of perovskite solar cells. Herein, a novel solution process to develop 2D/3D perovskites with modulated diffusion passivation by introducing phenylethylammonium iodide (PEAI) and N,N‐dimethylformamide (DMF) additive, which could effectively enhance device performance and long‐term stability, is demonstrated. Compared with conventional devices, the device with PEAI and DMF solvent additive treatment exhibit enhanced charge transport, improved charge extraction, and suppressed nonradiative carrier recombination. The solar cells with an optimal 2D/3D perovskite passivation treatment exhibit an extremely high fill factor of 83.6% and an average power conversion efficiency of 21.4% (21.3% using integrated photocurrent from the incident photon‐to‐current efficiency spectra) based on the NiOx hole transport layer. Furthermore, the unencapsulated device exhibits excellent stability under continuously simulated sunlight illumination and outstanding air stability after 1000 h of storage under ambient air conditions.
Accessed or latent resources? Exploring new secondary science teachers' networks of resources
Authors: Navy Shannon L. , Nixon Ryan S. , Luft Julie A. , Jurkiewicz Melissa A.
Published: August 2019

Although new teachers clearly need resources and support, little is known about the types of resources new science teachers' access during their early years of teaching. To increase knowledge of their needs, the study described in this article focused on the primary resources (i.e., human, material, and social) and secondary resources (i.e., strategic and symbolic) new science teachers' access and how those resources interact in new teachers' instructional contexts. The participants for this qualitative study were 15 new secondary science teachers in the United States, and data sources included a contextual interview, teaching observations, and a follow‐up interview. Findings revealed that these teachers had a variety of resources available to them, of which social resources were particularly important. Some resources were not accessed and remained latent resources. In addition, some interactions of resources in the new teachers' context led to the development of the network of resources model to represent how resources can interact in contexts to support a new teacher. This model highlights the importance of considering the interaction of multiple resources in a teaching context.
Cultivating teacher responsiveness with emergent bilingual students through videotaped lesson analysis
Authors: Daniel Shannon M. , Pray Lisa C. , Pacheco Mark B.
Published: August 2019

This article describes how a videotaped lesson analysis afforded elementary teachers opportunities to learn during their yearlong English as a second language (ESL) endorsement program. The aim of the assignment was for teachers to attend and respond to student contributions through conducting a macroanalysis of the lesson overall as well as a microanalysis of a few minutes of instructional interactions. Through this analysis of their videotaped instruction, teachers noticed the rich capabilities of their students and how they afforded their students limited opportunities to negotiate meaning, practice language, and apply content‐area skills in their lessons. Upon realizing these minimal chances for students to contribute to classroom discourse, teachers wrote about potential adaptations to their instruction that would enable emergent bilinguals to engage more frequently in productive talk. Implications for teacher educators, including our team’s refinement of this process, are discussed.
Effects of environmental chemicals on the proliferation and differentiation of neural stem cells
Authors: Huang Min , Li Yingying , Wu Kexin , Hao Shaowen , Cai Qian , Zhou Zhi‐jun , Yang Hui‐fang
Published: August 2019

The objective of the present study was to explore the effects of environmental chemicals, such as methyl mercury, paraquat, and bisphenol A, on cell proliferation and apoptosis, as well as the expression levels of neuronal differentiation‐related genes in neural stem cells (NSCs). NSCs originated from human umbilical cord blood (HUCB‐NSCs) were used as cell models in the current study. CCK‐8 and flow cytometry experiments were performed to assess the effects of methyl mercury, paraquat, and bisphenol A on the proliferation and apoptosis of HUCB‐NSCs at different processes, including proliferation and differentiation stages. The expressions of neuronal differentiation‐related genes were determined by reverse transcription‐polymerase chain reaction and western blot analysis. The results showed that methyl mercury, paraquat, and bisphenol A treatments significantly inhibited cell proliferation and induced cell apoptosis in HUCB‐NSCs, as well as decreased the expressions of Oct4, Gdf3, and Sox1, whereas increased Pax6 and Ngn1 expressions at both mRNA and protein levels. In conclusion, this study demonstrates that environmental chemicals can impair the proliferation and differentiation of NSCs, which may cause abnormal development of the nervous system.
Correction to: Mathematics and Computation in Music
Authors: Montiel Mariana , Gomez-Martin Francisco , Agustín-Aquino Octavio A.
Published: August 2019

Maria Mannone was not given credit for the cover logo in the original version. This was corrected.

The original version of chapter 14, “Distant Neighbors and Interscalar Contiguities” was revised. This chapter was previously published non-open access. It was changed to open access retrospectively under a CC BY 4.0 license. The book has also been updated with the change.
Wavefunctions and Yukawa couplings on resolutions of T2/ℤN orbifolds
Authors: Kobayashi Tatsuo , Otsuka Hajime , Uchida Hikaru
Published: August 2019

Abstract

We propose matter wavefunctions on resolutions of T
2/ℤ

N
singularities with constant magnetic fluxes. In the blow-down limit, the obtained wavefunctions of chiral zero-modes result in those on the magnetized T
2/ℤ

N
orbifold models, but the wavefunctions of ℤ

N
-invariant zero-modes receive the blow-up effects around fixed points of T
2/ℤ

N
orbifolds. Such blow-up effects change the selection rules and Yukawa couplings among the chiral zero-modes as well as the modular symmetry, in contrast to those on the magnetized T
2/ℤ

N
orbifold models.
Real scalar dark matter: relativistic treatment
Authors: Arcadi Giorgio , Lebedev Oleg , Pokorski Stefan , Toma Takashi
Published: August 2019

Abstract

A stable real scalar provides one of the simplest possibilities to account for dark matter. We consider the regime where its coupling to the Standard Model fields is negligibly small. Due to self-coupling, the scalar field can reach thermal or at least kinetic equilibrium, in which case the system is characterized by its temperature and effective chemical potential. We perform a fully relativistic analysis of dark matter evolution, thermalization conditions and different freeze-out regimes, including the chemical potential effects. To this end, we derive a relativistic Bose-Einstein analog of the Gelmini-Gondolo formula for a thermal averaged cross section. Finally, we perform a comprehensive parameter space analysis to determine regions consistent with observational constraints. Dark matter can be both warm and cold in this model.
To the sphere and back again: de Sitter infrared correlators at NTLO in 1/N
Authors: Nacir Diana López , Mazzitelli Francisco D. , Trombetta Leonardo G.
Published: August 2019

Abstract

We analyze the infrared behavior of the two and four-point functions for the massless O(N) model in Lorentzian de Sitter spacetime, using the 1/N expansion. Our approach is based in the study of the Schwinger-Dyson equations on the sphere (Euclidean de Sitter space), using the fact that the infrared behavior in Lorentzian spacetime is determined by the pole structure of the Euclidean correlation functions. We compute the two-point function up to the NTLO in 1/N , and show that in the infrared it behaves as the superposition of two massive free propagators with effective masses of the same order, but not equal to, the dynamical mass m

dyn
. We compare our results with those obtained using other approaches, and find that they are equivalent but retrieved in a considerably simpler way. We also discuss the infrared behavior of the equal-times four-point functions.
Effects of primary care cost-sharing among young adults: varying impact across income groups and gender
Authors: Johansson Naimi , Jakobsson Niklas , Svensson Mikael
Published: August 2019

We estimate the price sensitivity in health care among adolescents and young adults, and assess how it varies across income groups and gender, using a regression discontinuity design. We use the age differential cost-sharing in Swedish primary care as our identification strategy. At the 20th birthday, the copayment increases from €0 to approx. €10 per primary care physician visit and close to this threshold the copayment faced by each person is distributed almost as good as if randomized. The analysis is performed using high-quality health care and economic register data of 73,000 individuals aged 18–22. Our results show that the copayment decreases the average number of visits by 7%. Among women visits are reduced by 9%, for low-income individuals by 11%, and for low-income women by 14%. In conclusion, modest copayments have significant utilization effects, and even in a policy context with relatively low income inequalities, the effect is substantially larger in low-income groups and among women.
A Systematic Review of eHealth Interventions Addressing HIV/STI Prevention Among Men Who Have Sex With Men
Authors: Nguyen Long Hoang , Tran Bach Xuan , Rocha Luis E. C. , Nguyen Huong Lan Thi , Yang Cui , Latkin Carl A. , Thorson Anna , Strömdahl Susanne
Published: August 2019

A systematic review was conducted to summarize and appraise the eHealth interventions addressing HIV/STI prevention among men who have sex with men (MSM), and characterize features of successful eHealth interventions. Fifty-five articles (17 pilots and 38 full efficacy trials) were included with the predominance of web-based interventions in the United States-based settings. Intervention modalities include web-based, short message service (SMS)/text messges/email reminder, online video-based, computer-assisted, multimedia-based, social network, live chat and chat room, virtual simulation intervention, and smartphone applications. Forty-nine eHealth interventions achieved a short-term behaviour change among participants. Four studies were conducted with 12-month follow-ups; and only one of them could maintain the behaviour change over this longer time period which could be due to the lack of booster interventions. Our study suggests that eHealth interventions can achieve short term behaviour change among MSM, however limited interventions could maintain behaviour change over 12 months. Further eHealth intervention strategies to promote HIV prevention among MSM should be conducted and rigorously evaluated.
Direct and indirect effects of strength‐based parenting on adolescents’ school outcomes: Exploring the role of mental toughness
Authors: Sağkal Ali Serdar
Published: August 2019

Introduction

Strength‐based parenting defined as recognizing and cultivating strengths in children is potentially linked to important child and adolescent outcomes. In this study, direct and indirect effects (via mental toughness) of strength‐based parenting on adolescents’ school outcomes, particularly, school engagement and burnout were examined.

Methods

The sample consisted of 350 high school students (ages 14–18 years; 49.7% female) using multistage cluster sampling from central school district of city of Aydın, Turkey. Participants completed a battery of questionnaires that assess strength‐based parenting, mental toughness, school engagement, and burnout.

Results

Results showed that strength‐based parenting is significantly and directly related to higher levels of school engagement, but not to school burnout. Furthermore, indirect effects of strength‐based parenting on both school engagement and burnout through the mechanism of mental toughness were statistically significant. A series of multigroup post hoc analyses suggested that the structural model was robust across gender and age.

Conclusions

The present findings suggest that strength‐based parenting plays a crucial role on adolescents’ school outcomes and these links are mediated by mental toughness. Implications and suggestions for future research are also discussed.
Cost‐effectiveness of a collaborative dementia care management—Results of a cluster‐randomized controlled trial
Authors: Michalowsky Bernhard , Xie Feng , Eichler Tilly , Hertel Johannes , Kaczynski Anika , Kilimann Ingo , Teipel Stefan , Wucherer Diana , Zwingmann Ina , Thyrian Jochen René , Hoffmann Wolfgang
Published: August 2019

Introduction

The purpose of this study was to determine the cost‐effectiveness of collaborative dementia care management (DCM).

Methods

The cost‐effectiveness analysis was based on the data of 444 patients of a cluster‐randomized, controlled trial, conceptualized to evaluate a collaborative DCM that aimed to optimize treatment and care in dementia. Health‐care resource use, costs, quality‐adjusted life years (QALYs), and incremental cost per QALY gained were measured over a 24‐month time horizon.

Results

DCM increased QALYs (+0.05) and decreased costs (−569€) due to a lower hospitalization and a delayed institutionalization (7 months) compared with usual care. The probability of DCM being cost‐effective was 88% at willingness‐to‐pay thresholds of 40,000€ per QALY gained and higher in patients living alone compared to those not living alone (96% vs. 26%).

Discussion

DCM is likely to be a cost‐effective strategy in treating dementia and thus beneficial for public health‐care payers and patients, especially for those living alone.
Rivers Are a Highway for Microplastics into the Ocean
Authors: Barbuzano Javier
Published: August 2019

New research shows that rivers are the main road for all the plastic pollution that gets into the ocean, including microplastics.
July May Turn Out to Be the Hottest Month in Recorded History
Authors: Cartier Kimberly
Published: August 2019

If this year’s record-breaking trend continues, we’re on track for 2015–2019 to be the hottest 5 years on record.
Murders of Environmentalists Have Doubled in 15 Years
Authors: Cartier Kimberly
Published: August 2019

Indigenous people defending their lands are particularly at risk, and watchdog groups warn that criminalization of environmental activism is also on the rise.
Middle‐ and High‐Latitude Mesosphere and Lower Thermosphere Mean Winds and Tides in Response to Strong Polar‐Night Jet Oscillations
Authors: Conte J. Federico , Chau Jorge L. , Peters Dieter H. W.
Published: August 2019

The dynamical behavior of the mesosphere and lower thermosphere (MLT) region during strongly disturbed wintertime conditions commonly known as polar‐night jet oscillations (PJOs) is described in detail and compared to other wintertime conditions. For this purpose, wind measurements provided by two specular meteor radars located at Andenes (69°N, 16°E) and Juliusruh (54°N, 13°E) are used to estimate horizontal mean winds and tides as an observational basis. Winds and tidal main features are analyzed and compared for three different cases: major sudden stratospheric warming (SSW) with (a) strong PJO event, (b) non‐PJO event, and (c) no major SSWs. We show that the distinction into strong PJOs, non‐PJOs, and winters with no major SSWs is better suited to identify differences in the behavior of the mean winds and tides during the boreal winter. To assess the impact of the stratospheric disturbed conditions on the MLT region, we investigate the 30‐year nudged simulation by the Extended Canadian Middle Atmosphere Model. Analysis of geopotential height disturbances suggests that changes in the location of the polar vortex at mesospheric heights are responsible for the jets observed in the MLT mean winds during strong PJOs, which in turn influence the evolution of semidiurnal tides by increasing or decreasing their amplitudes depending on the tidal component.
Research Applications for the Geostationary Lightning Mapper Operational Lightning Flash Data Product
Authors: Peterson Michael
Published: August 2019

The Lightning Cluster Filter Algorithm in the Geostationary Lightning Mapper (GLM) ground system identifies lightning flashes from the stream of event detections. It excels at clustering simple flashes but experiences anomalies with complex flashes that last longer than 3 s or contain more than 100 groups, leading to flashes being artificially split. We develop a technique that corrects these anomalies and apply it to the 2018 GLM data to document all lightning across the Americas. We produce statistics describing the characteristics and frequencies of reclustered GLM flashes and thunderstorm area features. The average GLM Americas flash rate in 2018 was 11.7 flashes per second with the greatest flash rate densities occurring over Lake Maracaibo (157 flashes per km2/year). Lloró, Chocó, Colombia had the most thunderstorm activity with 256 thunder days. The longest GLM flash spanned 673 km, the largest flash covered 114,997 km2, and the longest‐lasting flash had a 13.496‐s duration. The first case occurred over Rio Grande do Sul in Brazil, while the other two cases occurred in the central United States. All three extreme flashes are located in the stratiform regions of Mesoscale Convective Systems. The highest flash rate for a thunderstorm area feature was 17.6 flashes per second, while the largest thunderstorm was 216,865 km2 in size. Both storms occurred in South America. These initial results demonstrate the value that the development of a reprocessed GLM science product would offer and how such a product might be created at a reduced computational cost.
Volcanic Eruption Signatures in the Isotope‐Enabled Last Millennium Ensemble
Authors: Stevenson S. , Otto‐Bliesner B. L. , Brady E. C. , Nusbaumer J. , Tabor C. , Tomas R. , Noone D. C. , Liu Z.
Published: August 2019

Explosive volcanic eruptions are one of the largest natural climate perturbations, but few observational constraints exist on either the climate responses to eruptions or the properties (size, hemispheric aerosol distribution, etc.) of the eruptions themselves. Paleoclimate records are thus important sources of information on past eruptions, often through the measurement of oxygen isotopic ratios (δ18O) in natural archives. However, since many processes affect δ18O, the dynamical interpretation of these records can be quite complex. Here we present results from new, isotope‐enabled members of the Community Earth System Model Last Millennium Ensemble, documenting eruption‐induced δ18O variations throughout the climate system. Eruptions create significant perturbations in the δ18O of precipitation and soil moisture in central/eastern North America, via excitation of the Atlantic Multidecadal Oscillation. Monsoon Asia and Australia also exhibit strong precipitation and soil δ18O anomalies; in these cases, δ18O may reflect changes to El Niño‐Southern Oscillation phase following eruptions. Salinity and seawater δ18O patterns demonstrate the importance of both local hydrologic shifts and the phasing of the El Niño‐Southern Oscillation response, both along the equator and in the subtropics. In all cases, the responses are highly sensitive to eruption latitude, which points to the utility of isotopic records in constraining aerosol distribution patterns associated with past eruptions. This is most effective using precipitation δ18O; all Southern eruptions and the majority (66%) of Northern eruptions can be correctly identified. This work thus serves as a starting point for new, quantitative uses of isotopic records for understanding volcanic impacts on climate.
Analysis of Flow Resistance Equations in Gravel‐Bed Rivers With Intermittent Regimes: Calabrian fiumare Data Set
Authors: Mendicino G. , Colosimo F.
Published: August 2019

This study addresses the evaluation of flow resistance in natural gravel‐bed rivers. Through a new data set collected on 136 reaches of 78 gravel‐bed rivers (Calabrian fiumare) in southern Italy, different conventional flow resistance equations to predict mean flow velocity in gravel‐bed rivers were tested in their original form. These equations have shown considerable disagreement with observed data, especially in river reaches characterized by high bed load conditions and for the domains of intermediate‐ and large‐scale roughness. This disagreement produced in almost all the cases an underestimation of the flow resistance, which can be corrected by introducing the Froude number and a particular form of the Shields sediment mobility parameter into the Manning, Chezy, and Darcy‐Weisbach equations. Through analyses carried out both on the whole data set and on its subsets, we propose a semiempirical approach with which, on the one hand, the tractive forces exerted by the flow on the bed are taken into account by considering the ratio between the sediment mobility parameter and its critical value, and on the other hand, water surface distortions are evaluated using the Froude number. This approach has been further validated using a literature‐based data set showing, even in this case, excellent performances. Finally, the literature‐based data set allowed us to improve the performances of the proposed approach in the field of large‐scale roughness. Efficiency tests indicate that the new equations can better reproduce the flow velocity in river reach where conventional flow resistance equations are not able to explain the entire dissipative process.
On the Field Estimation of Moisture Content Using Electrical Geophysics: The Impact of Petrophysical Model Uncertainty
Authors: Tso Chak‐Hau Michael , Kuras Oliver , Binley Andrew
Published: August 2019

The spatiotemporal distribution of pore water in the vadose zone can have a critical control on many processes in the near‐surface Earth, such as the onset of landslides, crop yield, groundwater recharge, and runoff generation. Electrical geophysics has been widely used to monitor the moisture content (θ) distribution in the vadose zone at field sites, and often resistivity (ρ) or conductivity (σ) is converted to moisture contents through petrophysical relationships (e.g., Archie's law). Though both the petrophysical relationships (i.e., choices of appropriate model and parameterization) and the derived moisture content are known to be subject to uncertainty, they are commonly treated as exact and error‐free. This study examines the impact of uncertain petrophysical relationships on the moisture content estimates derived from electrical geophysics. We show from a collection of data from multiple core samples that significant variability in the θ(ρ) relationship can exist. Using rules of error propagation, we demonstrate the combined effect of inversion and uncertain petrophysical parameterization on moisture content estimates and derive their uncertainty bounds. Through investigation of a water injection experiment, we observe that the petrophysical uncertainty yields a large range of estimated total moisture volume within the water plume. The estimates of changes in water volume, however, generally agree within (large) uncertainty bounds. Our results caution against solely relying on electrical geophysics to estimate moisture content in the field. The uncertainty propagation approach is transferrable to other field studies of moisture content estimation.
Water Vapor Sorption Properties of Illinois Shales Under Dynamic Water Vapor Conditions: Experimentation and Modeling
Authors: Sang Guijie , Liu Shimin , Elsworth Derek
Published: August 2019

Water vapor adsorption/desorption isotherms are measured on five shales from Illinois basin by dynamic vapor sorption method. The experimental adsorption data are modeled by the Guggenheim, Anderson, and De Boer model and the Freundlich model over the entire range of measured relative humidity (Rh) values (0–0.95). Modeling results show that shale hydration is controlled by surface chemistry at low Rh through a strong intermolecular bonding, while is mainly influenced by the pore structure at high Rh (>0.9) through capillary condensation. This is consistent with the progressive decrease of isosteric heat of adsorption with water content, obtained by the Clausius‐Clapeyron equation. Exceptionally, for the one shale containing 8.6% montmorillonite, mesopore condensation only accounts for 33% of the measured water adsorption even at Rh ~0.95 due to the limited external pores and the important role of clay swelling. The specific surface area defined by Guggenheim, Anderson, and De Boer analysis as available for water adsorption is larger than that available for low‐pressure N2 adsorption due to the complex surface chemistry. The one shale rich in expansive montmorillonite and with a large interlayer capacity for water but inaccessible to N2 molecules conditions this result. Among the other four shales, one with high kerogen content behaves the highest water adsorption, possibly due to the high content of oxygen‐containing functional groups and the potentially high pore volume of kerogen. These findings contribute to a better understanding of water storage and transport behavior in shales and impact behavior relevant to structures and reservoirs founded in such media.
CCT α is a novel biomarker for diagnosis of laryngeal squamous cell cancer
Authors: Yang Jingpu , Zhang Zhuping , Zhao Yin , Cheng Jinzhang , Zhao Chang , Wang Zonggui
Published: August 2019

Choline phosphate-based delivery systems can target the acidic tumor microenvironment. In this study, we set out to evaluate the diagnostic value of Choline phosphate cytidylyltransferase-α (CCTα) in laryngeal squamous cell cancer (LSCC). The expression of CCTα was detected using immunohistochemistry in 50 LSCC patients’ tissues and 16 vocal polyps as control group. Then, clinical data was collected and we used receiver operating characteristic curve (ROC) to estimate the potential of CCTα as diagnostic biomarker. We found CCTα levels to be significantly high in the tissues derived from LSCC patients, (p < 0.001). Further, we observed a positive correlation of CCTα with tumor size (p < 0.001), TNM stage (p < 0.001), lymph node metastasis (p < 0.001) as well as the grade of LSCC malignancy (p < 0.001). Furthermore, AUC was determined to be 0.939 by ROC, and the optimal cutoff value 3.100, with 76.0% sensitivity and 100% specificity. We also found an epigenetic basis of CCTα over-expression in LSCC tissues with significantly reduced methylation of CCTα in LSCC tissues, compared to vocal polyps (p < 0.001). These results support epigenetically-induced over-expression of CCTα as a potential diagnostic marker for LSCC.
Pigmentation and Photoaging
Authors: Tobin Desmond J.
Published: August 2019

Casual comparison of the appearance and texture of unprotected photoexposed hand and face skin versus the skin of the secluded upper inner arm quickly reveals the striking impact of accumulated solar radiation on skin aging, particularly after the third or fourth decade of life. The basis of this change in superficial appearance can be revealed in a host of anatomical, histological, and ultrastructural changes in the epidermis and dermis of the skin, which result from alterations at the cellular and molecular levels. There is increasing evidence that environmental pollution (including exposure to car fuel-derived particulates with/without light activation) and even certain wavelengths of visible light can also contribute to the global ‘photoaging’ response. Evolution has equipped human skin with at least partially effective protective devices against such environmental damage; principal among them includes the synthesis of copious amounts melanin that acts as a near-universal stress absorber. This still-enigmatic indole biopolymer acts as a ‘sink’ for toxins, pollutants, drugs, as well as a redox buffer against a host of reactive oxygen species. The latter are derived from a raft of chemical reactions at the skin. Brown/black (or wild-type) melanin far outperforms the photolabile red/yellow pheomelanin, which increases the vulnerability of the skin to photodamage and therefore photocarcinogenesis. Interventions that can boost eumelanin levels, in a solar radiation-independent manner, may enhance protection against skin photodamage.
Proton coupled electron transfer: novel photochromic performance in a host–guest collaborative MOF
Authors: Shao Zhichao , Wu Qiong , Han Xiao , Zhao Yujie , Xie Qiong , Wang Hongfei , Hou Hongwei
Published: August 2019

Proton coupled electron transfer has been successfully introduced to a host–guest collaborative MOF material, which exhibits novel photochromic properties with reversible, controllable and efficient characteristics.
Persistent energy transfer in ZGO:Cr3+,Yb3+: a new strategy to design nano glass-ceramics featuring deep red and near infrared persistent luminescence
Authors: Castaing Victor , Sontakke Atul D. , Xu Jian , J. Fernández-Carrión Alberto , Genevois Cécile , Tanabe Setsuhisa , Allix Mathieu , Viana Bruno
Published: August 2019

ZnGa2O4:Cr3+,Yb3+ nanocrystals, elaborated via glass crystallisation, show strong deep red and near infrared persistent luminescence chargeable by red light.
Highly selective conversion of natural oil to alcohols or alkanes over a Pd stabilized CuZnAl catalyst under mild conditions
Authors: Guo Ziwei , Zhou Feng , Wang Hao , Liu Xiaohao , Xu Guangyue , Zhang Ying , Fu Yao
Published: August 2019

A novel and green catalytic system based on a Pd stabilized CuZnAl catalyst was designed for one-pot conversion of natural oil components to the corresponding alcohols or long-chain linear and branched alkanes with high selectivity and atom economy.
Partitioning of hydrogels in 3D-printed microchannels
Authors: Kim Yong Tae , Bohjanen Sara , Bhattacharjee Nirveek , Folch Albert
Published: August 2019

We demonstrated a stereolithographically 3D-printed chip for the straightforward injection of hydrogel barriers in microchannels and the facile measurement of molecular diffusivities through these hydrogels.
Organic cation directed hybrid lead halides of zero-dimensional to two-dimensional structures with tunable photoluminescence properties
Authors: Yue Cheng-Yang , Sun Hai-Xiao , Liu Quan-Xiu , Wang Xin-Ming , Yuan Zhao-Shuo , Wang Juan , Wu Jia-Hang , Hu Bing , Lei Xiao-Wu
Published: August 2019

A series of new inorganic–organic hybrid lead halides have been solvothermally synthesized and characterized with tunable luminescence properties from yellow, orange to red emissions with the largest reported Stokes shift.
On the unsuspected role of multivalent metal ions on the charge storage of a metal oxide electrode in mild aqueous electrolytes
Authors: Kim Yee-Seul , Harris Kenneth D. , Limoges Benoît , Balland Véronique
Published: August 2019

The hidden role of hexaaquo metal ion complexes in the proton-coupled electron charge storage at a metal oxide electrode.
In situ bottom–up growth of metal–organic frameworks in a crosslinked poly(ethylene oxide) layer with ultrahigh loading and superior uniform distribution
Authors: Ma Liang , Svec Frantisek , Lv Yongqin , Tan Tianwei
Published: August 2019

A mixed-matrix membrane combining an inorganic filler and polymer phase is an essential part of the scheme enabling improvements in gas separation.
Insights into the lithiation mechanism of CFx by a joint high-resolution 19F NMR, in situ TEM and 7Li NMR approach
Authors: Zhong Guiming , Chen Huixin , Cheng Yong , Meng Lingyi , Liu Haodong , Liu Zigeng , Zheng Guorui , Xiang Yuxuan , Liu Xiangsi , Li Qi , Zhang Qiaobao , Yue Hongjun , Lu Canzhong , Yang Yong
Published: August 2019

Lithiation reaction mechanism of CFx is revealed, determining that the fluorinated carbon with low fluorination level is produced along with carbon and LiF. Furthermore, the nucleation and growth processes of formed LiF are illustrated.
Design of salt-responsive and regenerative antibacterial polymer brushes with integrated bacterial resistance, killing, and release properties
Authors: Wang Yang , Wu Jiahui , Zhang Dong , Chen Feng , Fan Ping , Zhong Mingqiang , Xiao Shengwei , Chang Yung , Gong Xiong , Yang Jintao , Zheng Jie
Published: August 2019

The development of smart materials and surfaces with multiple antibacterial actions is of great importance for both fundamental research and practical applications, but this has proved to be extremely challenging.
Analysing impact of major solar flares on ionospheric TEC with RTISM model using IRNSS receiver, at SVNIT, Surat, India
Authors: Parmar Sonal , Dalal Upena , Pathak Kamlesh
Published: August 2019

Indian regional navigation satellite system (IRNSS) is a navigation system developed by the Indian Space Research Organisation (ISRO), India. The IRNSS receiver granted by Space Application Centre (SAC), ISRO, Ahmedabad is installed at SVNIT, Surat, India. A solar flare is a natural event that occurs when an unpredicted flash of distended Sun's illumination is observed near its surface. The ionosphere is greatly ionised by solar radiations. Hence it is a current challenge to investigate effects of ionospheric scintillation on IRNSS signals. This study examines impact of major solar flare events like Class ‘C’ solar flare happened on 22 July 2016 and class ‘M’ solar flare occurred on 23 and 24 July 2016, on IRNSS signals with measurement of total electron content (TEC). Real‐time ionospheric scintillation monitoring (RTISM) model based on empirical mode decomposition (EMD) and second‐order Daubechies (db2) wavelet is used for comparing measured and denoised TEC. The RTISM model is also used for determining automatic threshold using Neyman–Pearson detector, probability of detection and probability of false alarm. It is proven with analysis that EMD is giving more sharp results as compared to db2 wavelet for determining fluctuations in TEC during the solar flare events.
Optimisation‐based time slot assignment and synchronisation for TDMA MAC in industrial wireless sensor network
Authors: Chang Ching‐Lung , Chang Chuan‐Yu , Chen Shuo‐Tsung , Tu Shu‐Yi , Ho Kuan‐Yi
Published: August 2019

Wireless sensor network in the industrial environment [industrial wireless sensor network (IWSN)] has data delivery time constraint. Due to the dynamic routing and transmission collision, the data delivery time is unpredictable. The authors utilised time division multiple access (TDMA) MAC to avoid data collision and to provide bounded transmission delay. Moreover, a linear programming model is proposed to construct the TDMA schedules, which is focused on spatial reuse and fixed routing in IWSN. The objective function of the model is to minimise the time slot usage to increase the overall network bandwidth. Finally, both simulated annealing algorithm and particle swarm optimisation are applied to approximate the optimal solution of time slot usage.
Threshold‐voltage‐drift‐aware scheduling for belief propagation decoding of LDPC‐coded NAND flash memory
Authors: Liu Wenjie , Han Guojun , Fan Zhengqin , Fang Yi , Cai Guofa
Published: August 2019

With the continual increase of storage density, NAND flash memory cells are particularly vulnerable to channel noise, which significantly degrades the storage reliability. To overcome this issue, low‐density parity check (LDPC) codes have been considered as a preferable choice for flash memory systems. To further improve the efficiency of the decoder, the convergence speed and the error‐rate performance are the key performance indicators for LDPC‐coded NAND flash memory. In this study, a threshold‐voltage‐drift‐aware scheduling for belief propagation (BP) decoding of LDPC‐coded NAND flash memory is introduced to improve the convergence speed and the error‐rate performance. The basic idea of the proposed scheduling is to find an appropriate updated order of variable nodes according to their corresponding locations of threshold voltages. Since the proposed scheduling updates less reliable variable nodes with higher priority, it can improve the efficiency of BP decoding. Simulation results show that the proposed scheduling not only significantly improves the convergence speed, but also obtains better error‐rate performance than the conventional serial scheduling.
3D non‐stationary unmanned aerial vehicles' MIMO channel model
Authors: Jia Haolin , Chen Hui , Wang Shiwen , Zhang Yahong
Published: August 2019

The unmanned aerial vehicle (UAV) channel measurements have shown that the propagation environment of UAV channel is non‐stationary. In this study, a three‐dimensional (3D) non‐stationary UAV multiple‐input multiple‐output (MIMO) channel model is proposed. In order to sufficiently describe the propagation environment of UAV‐MIMO channel, the stationary scatterers and moving scatterers are investigated in the proposed model, which are mimicked using 3D cylinder and two‐dimensional (2D) disc, respectively. The Doppler shifts associated with moving scatterers are also considered in the proposed model. The movement of UAV, receiver, and moving scatterers results in non‐stationarities, and time‐variant distances, azimuth angles, and elevation angles are investigated in the proposed model. The statistical properties of the moving scatterers are also investigated in the proposed channel model. In order to validate the proposed model, the spatial correlation is compared with the measurement results, and the numerical results show that the proposed channel model is applicable to describe the UAV‐MIMO communication systems.
Robust secrecy energy efficiency optimisation in heterogeneous networks with simultaneous wireless information and power transfer: centralised and distributed design
Authors: Bo Zhang , Kai‐zhi Huang , Liang Jin , Ming Yi
Published: August 2019

With the ellipsoid‐bounded channel state information (CSI) errors, this study investigates the robust secrecy energy efficiency (SEE) optimisation in a wireless powered heterogeneous network. Specifically, the authors consider the network where multiple femtocell base stations (FBSs) are deployed under the coverage of one macrocell base station (MBS). Meanwhile, the MBS serves multiple macrocell users in the presence of a malicious multiple‐antenna eavesdropper (Eve) while each FBS serves a pair of information receiver (IR) and energy receiver (ER) with multiple antennas, where the ER attempts to wiretap the information of IR in the same femtocell. To promote the secrecy performance, artificial noise (AN) is aided into the downlink signal at the MBS and FBSs, and the problem of maximising SEE is formed in a cross‐tier multi‐cell AN‐aided transmit beamforming design. This problem is non‐convex while containing infinite constraints caused by CSI errors, which cannot be solved directly. In this regard, the authors resort to the successive convex approximation, semi‐definite relaxation techniques and Lagrange duality theory to acquire its solvable form. Moreover, to reduce the overhead of information exchange among coordinated BSs, they further propose a distributed approach based on alternative direction multiplier method. Finally, simulation results validate the effectiveness of the proposed design.
Robust state and fault estimation for non‐linear stochastic systems with unknown disturbances: a multi‐step delayed solution
Authors: Bessaoudi Talel , Hmida Fayçal Ben , Hsieh Chien‐Shu
Published: August 2019

A study on the simultaneous state and fault estimation for non‐linear discrete‐time stochastic systems subjected to unknown disturbances is presented. The augmented system approach, system reformation using the state‐dependent coefficient (SDC) factorisation, and unknown input filtering method are integrated to simultaneously estimate the state of the system and actuator and/or sensor faults. To achieve this aim, the non‐linear system with faults and unknown disturbances is first transformed into an equivalent augmented system by using delayed measurements and the SDC factorisation. Next, within the SDC factorised linear‐like augmented system and inspired by the robust two‐stage Kalman filter, a novel multi‐step estimator named as the robust simultaneous state and fault estimator is proposed to yield a robust state and fault estimation with a multi‐step delay. Moreover, a novel real‐time state estimator is designed based on the proposed hybrid fault reconstruction model in order to address the inherent time‐delay problem. A comparison of the performance of the proposed filters with those of existing methods from the literature is demonstrated using a non‐linear two‐link manipulator system with friction forces acting simultaneously at each joint.
State bounding for positive singular discrete‐time systems with time‐varying delay and bounded disturbances
Authors: Huu Sau Nguyen , Thuan Mai Viet
Published: August 2019

This study deals with the problem of state bounding for positive singular discrete‐time systems with time‐varying delay and bounded disturbances. First, the authors derive some new conditions for the existence of componentwise bounds of the state vector of the systems without disturbances. Then, in the case of systems with bounded disturbances, they obtain a sufficient condition for the existence of componentwise ultimate bounds. Since the conditions are given in terms of the spectral radius of the system matrices, they can check them easily and compute directly the smallest componentwise ultimate bound. In addition, the problem of state bounding for positive time‐varying singular systems is also investigated in this study. Finally, numerical examples are provided to illustrate the effectiveness and advantages of their results.
Stabilisation for switched positive systems under extended asynchronous switching
Authors: Liu Jiao , Yang Yake , Li Hongchao , Yang Dedong
Published: August 2019

This study first addresses an extended asynchronous switching control issue resulting from switching delay and false alarm for a family of switched positive systems. Based on a new set of switching signals superior to the average dwell time switching, the state‐feedback controller is designed to guarantee the positivity and global asymptotic stability for the closed‐loop system. In addition, the corresponding sufficient condition formulated in terms of linear programming problem is derived. Different from the previous works, the authors' established results further relax the restriction that all subsystems must be stabilisable in the normal‐running period with matched controller, and allow the increase of the Lyapunov function in the switching delay period, false alarm period, normal‐running period with matched controller and all switching instants. Finally, a numerical example with practical considerations is used to show the effectiveness and potential of the proposed theories.
Microstructure and dielectric properties of sub‐micron hollow sphere (Ba0.6 Sr0.4)TiO3 /PVDF composites
Authors: Guo Yiting , Zhang Kena , Meng Nan , Wu Wanli , Wang Yujian , Xu Jie , Pawlikowska Emilia , Szafran Mikołaj , Gao Feng
Published: August 2019

Hollow sphere (Ba0.6 Sr0.4)TiO3 (HS‐BST) powders with sub‐micron size and different shell thickness were synthesised through template‐assisted method. HS‐BST/poly(vinylidene fluoride) (PVDF) composites were prepared using tape casting method. The effects of particle size and shell thickness of HS‐BST on the microstructure, dielectric tunability, and energy storage properties of HS‐BST/PVDF composites were investigated. Results showed that all HS‐BST particles were uniformly dispersed in PVDF matrix without agglomeration. With decreasing the size of HS‐BST particles, the dielectric constant and loss of HS‐BST/PVDF composites decreased, while the breakdown strength initially decreased and then increased. In addition, the theoretical model of the dielectric tunability of inorganic/organic system related to the shape factor (n) of inorganic particles was used to simulate and n value of 0‐dimensional spherical particles was estimated. For HS‐BST/PVDF composite, the n in the model was 2–2.5, corresponding to HS‐BST particles with a diameter ranging from 0.44 to 2.57 μm, and a shell thickness ranging from 40 to 500 nm.
Fast and quantitative measurement of pulse current using interferometry
Authors: Zhu Yueyue , Li Mengying , Zhao Yan , Xue Liang
Published: August 2019

To perceive the advent of pulse current (PC) sensitively and evaluate the peak value accurately on a cost effective setup, an interferometric measurement is proposed first in this study. By extracting the phase information of the interference fringes effected by the PC quantitatively, the relative peak value of PC with random waveform is obtained in real time. Based on the theoretical analysis, the proposed method has been tested by the PC with the waveform of 8/20 μs and peak value of 3, 2.75 and 2.5 kA. The interferograms are collected online, and the phase recovery is completed in seconds. Repetitive experiments under the same conditions reveal the relationship between the peak value and the phase information, proving it a potential application to retrieve the PC peak value quantitatively in real time.
Improved‐efficiency quasi‐two‐stage current‐source‐mode SIMO LED driver
Authors: Dong Zheng , Li Xiaolu Lucia , Tse Chi Kong
Published: August 2019

Single‐inductor–multiple‐output (SIMO) light‐emitting‐diode (LED) drivers are attractive, practical solutions for lighting applications. An SIMO LED driver is usually constructed with conventional voltage‐source‐mode dc–dc converters. Current‐source‐mode (CSM) converters, though being highly suited for current driving, are less studied. Simple control, low cost and independent dimming function are among the advantages of CSM SIMO converters. The limiting factors of CSM SIMO converters, however, include the relatively low efficiency and the restricted number of outputs under low‐frequency pulse‐width modulation (PWM) dimming control. In this study, an adaptive current bus technique to the CSM SIMO converter is applied. Results show that a significant improvement in efficiency can be achieved. The low‐frequency PWM dimming method is also analysed and redesigned. Also, we compare the voltage stress in the CSM SIMO converter with traditional input‐series‐connected structure. Results show that the CSM SIMO converter achieves a high‐voltage step‐down ratio without the use of transformers. This study presents detailed analysis and experimental results of the CSM SIMO converter with adaptive current bus.