bluuebunny/crossref_metadata_2025 huggingface dataset:
Protected long-time storage of a topological insulator
Authors: Liang Luo-Uei , Yen Yu-Hsiung , Chou Chia-Wei , Chen Ko-Hsuan Mandy , Lin Hsiao-Yu , Huang Sheng-Wen , Hong Minghwei , Kwo Jueinai , Hoffmann Germar
Published: February 2021

The physical investigation of surfaces and their properties crucially depends on their quality. Such investigations are commonly performed in an ultra-high vacuum environment. Thereby, the transfer of samples among different setups and under ambient conditions is desirable. The usage of a capping layer for the protection of surfaces against contaminations during long-time storage and transfer, and the subsequent temperature-controlled decapping is an established approach. However, a residual-free removal of the capping layer may present a challenge. Here, we systematically investigate the decapping process of a tellurium protected topological insulator Bi2Te3. We give evidence for the material segregation from the contaminated capping layer surface to the substrates. Therefore, a simple, temperature controlled decapping is not sufficient. We demonstrate that near perfect surfaces can be reliably obtained even after long-time storage through a combination of an initial argon ion sputtering process and a following heating for decapping. This approach is suitable for dedicated analysis systems as well as for industrial applications, large throughput of samples of arbitrary shapes, and is easily implemented in existing setups.
A systematic study of the dynamics of chain formation in electrorheological fluids
Authors: Fertig Dávid , Boda Dezső , Szalai István
Published: February 2021

We report a systematic study of the dynamics of chain formation in electrorheological fluids using Brownian dynamics simulations. The parameters of the system such as applied electric field, polarizability, dipole moment, friction coefficient, and number density are expressed in reduced units and changed in a wide range in order to map the system’s behavior as a function of them. We define time constants obtained from bi-exponential fits to time dependence of various physical quantities such as dipolar energy, diffusion constant, and average chain length. The smaller time constant is associated with the formation of shorter chains (pairs, triplets, and so on), while the larger time constant is associated with the formation of longer chains in the regime of those that overarch the simulation cell. We use the approximation that the dipole moments are induced by the applied electric field only, as usual in the literature. However, we report preliminary results for the case when particle–particle polarization is also possible.
Large lattice-relaxation-induced intrinsic shallow p-type characteristics in monolayer black phosphorus and black arsenic
Authors: Qiu Chen , Cao Ruyue , Wang Fei , Deng Hui-Xiong
Published: February 2021

Technological application of semiconductors depends critically on their defect properties. Recently, it has been experimentally observed that monolayer (ML) black phosphorus (BP) and black arsenic (BAs) are intrinsic p-type semiconductors, which conflict with the theoretical predictions previously acknowledged that there are no shallow defects in two-dimensional semiconductors. In this paper, we have systematically studied the properties of intrinsic defects in ML BP and BAs using the “transfer to real state” model. We confirmed that both P and As vacancies are shallow dominating acceptors, resulting in the p-type conductivity in ML BP and BAs, respectively. These shallow acceptor levels arise from the symmetry lowering induced by the large local structural distortion for the charged vacancy state. To validate our simulation, we also calculated the hole concentrations that are consistent with the experimentally measured p-type conductivity in both materials. Our results, therefore, help explain the origin of the intrinsic p-type conductivity in ML BP and BAs, which reinforces the comprehension for the defect properties in two-dimensional materials.
Efficient enumeration of bosonic configurations with applications to the calculation of non-radiative rates
Authors: Shaw Robert A. , Manian Anjay , Lyskov Igor , Russo Salvy P.
Published: February 2021

This work presents algorithms for the efficient enumeration of configuration spaces following Boltzmann-like statistics, with example applications to the calculation of non-radiative rates, and an open-source implementation. Configuration spaces are found in several areas of physics, particularly wherever there are energy levels that possess variable occupations. In bosonic systems, where there are no upper limits on the occupation of each level, enumeration of all possible configurations is an exceptionally hard problem. We look at the case where the levels need to be filled to satisfy an energy criterion, for example, a target excitation energy, which is a type of knapsack problem as found in combinatorics. We present analyses of the density of configuration spaces in arbitrary dimensions and how particular forms of kernel can be used to envelope the important regions. In this way, we arrive at three new algorithms for enumeration of such spaces that are several orders of magnitude more efficient than the naive brute force approach. Finally, we show how these can be applied to the particular case of internal conversion rates in a selection of molecules and discuss how a stochastic approach can, in principle, reduce the computational complexity to polynomial time.
Quantitative analysis of magnetic cobalt particles with an optically pumped atomic magnetometer
Authors: Bi Xin , Ruan Limeng , Liu Zehua , Li Kan , Ruan Yi , Zheng Wenqiang , Lin Qiang
Published: February 2021

Magnetic particles (MPs), a group of engineered particles in the nanometer and microscale, are valuable tools for separation of chemical or biological substance in environmental research, for target delivery of antibodies or proteins in biomedical applications, and for quantification of cells or biomolecules in biological systems. Despite the estimation of the amount of magnetic nanoparticles that were realized by magnetic particle spectroscopy, accurate quantification of MPs at single-particle resolution is still a challenge. Here, we used an elliptically optically pumped Mx atomic magnetometer combined with a peristaltic pump system to perform magnetic field measurements to quantify magnetic particles at the single-particle level under aqueous solution condition. Quantitative analysis of cobalt micro-nanoparticles revealed the volume-field linear character of magnetic particles. From the measured intensity of the magnetic field generated by MPs, we calculated the geometric parameters and numbers of MPs and estimated the detection limit of our developed atomic magnetometer. Our work paves a way for the practical use of MPs in the biomedical field as well as other applications in industry.
Observation of electrically detected electron nuclear double resonance in amorphous hydrogenated silicon films
Authors: Manning Brian R. , Ashton James P. , Lenahan Patrick M.
Published: February 2021

We report on the electrical detection of electron nuclear double resonance (EDENDOR) through spin-dependent tunneling transport in an amorphous hydrogenated silicon thin film. EDENDOR offers a many orders of magnitude improvement over classical ENDOR and is exclusively sensitive to paramagnetic defects involved in electronic transport. We observe hyperfine interactions with 1H nuclei very close to silicon dangling bond defects. These observations substantially extend recent EDENDOR observations involving silicon vacancy defects and 14N hyperfine interactions with fairly distant nitrogen atoms in 4H-SiC bipolar junction transistors. We have improved the detection scheme utilized in the earlier study by combining magnetic field modulation with RF amplitude modulation; this combination significantly improves the operation of the automatic power leveling scheme and the overall sensitivity.
Insights into radiation displacement defect in an insulated-gate bipolar transistor
Authors: Kim Kihyun , Kim Jungsik
Published: February 2021

The effects of the radiation displacement defect on an insulated-gate bipolar transistor are investigated using the computer-aided design simulation technology. DC characteristics, breakdown voltage, and power dissipation are analyzed according to the position, energy, and types of trap caused by the radiation effect. The on-current is degraded by 100% due to displacement defect, which is generated near the emitter–gate region. An acceptor-like trap with Ec − 0.4 eV shows the most significant degradation compared to an acceptor-like trap with Ec − 0.2 eV and a donor-like trap with Ev + 0.2 eV. At 300 K, the breakdown voltage is unaffected by radiation displacement defects but is significantly reduced in a high-temperature environment (425 K) because the depletion width becomes shorter due to the displacement defect. Power dissipation exhibits immunity to the displacement defect induced by radiation at both room temperature and high temperatures.
Spectral imaging of flexible terahertz coding metasurface
Authors: Wang Taofeng , Chen Benwen , Wu Jingbo , Yang Shengxin , Shen Ze , Cai Jiacheng , Li Weili , Zhang Caihong , Jin Biaobing , Chen Jian , Wu Peiheng
Published: February 2021

Coding metasurfaces have emerged as a promising venue for terahertz (THz) beam steering and beamforming. In this study, we designed a transmission metasurface with a complementary structure based on Babinet's principle. The beam-steering capability of the coding metasurface is implemented by encoding “0” and “1” elements with different phase responses and by controlling the coding sequences. The deflection angle can be controlled by changing the period of these 0 and 1 elements. Despite the development of beam-steering technology, measurements of the direction pattern of steered THz beams remain challenging. Systems for THz time-domain spectroscopy and spectral imaging are used to characterize the flexible coding metasurfaces. The THz imaging system can provide information on the directional pattern of the beam. To verify the performance of the proposed metasurface, the experimental measurements of beam deflection were found to be consistent with the values yielded by a simulation. Our study provides an effective platform for the design and measurement of THz beam steering.
Data driven forecasting of aperiodic motions of non-autonomous systems
Authors: Agarwal Vipin , Wang Rui , Balachandran Balakumar
Published: February 2021

In the present effort, a data-driven modeling approach is undertaken to forecast aperiodic responses of non-autonomous systems. As a representative non-autonomous system, a harmonically forced Duffing oscillator is considered. Along with it, an experimental prototype of a Duffing oscillator is studied. Data corresponding to chaotic motions are obtained through simulations of forced oscillators with hardening and softening characteristics and experiments with a bistable oscillator. Portions of these datasets are used to train a neural machine and make response predictions and forecasts for motions on the corresponding attractors. The neural machine is constructed by using a deep recurrent neural network architecture. The experiments conducted with the different numerical and experimental chaotic time-series data confirm the effectiveness of the constructed neural network for the forecasting of non-autonomous system responses.
Grain mineral composition of Argentinean-adapted wheat cultivars: a case study
Authors: D'Amico Iván , Silva Mauro , Moriconi Jorge I. , Santa-María Guillermo E. , Bainotti Carlos T. , Tabbita Facundo
Published: February 2021

Improvement of the nutritional quality of wheat (Triticum aestivum L.) has been quite challenging, due, in part, to the limited variation found in modern cultivars and the strong effect exerted by the environment, which hinder the selection process. The aim of this study was to characterise the mineral profile of grains of 35 Argentinean-adapted, mostly spring wheat cultivars in two successive years. Concentrations of most mineral nutrients in grains spanned approximately a two-fold range. Our study revealed a strong effect of the environment, but also that some key differences among genotypes are maintained over years. Correlation and principal component analyses showed the existence of a strong and stable association of variables determining the global elemental profile in grains of the wheat lines under analysis. In this regard, some cultivars displayed, over successive years, opposite global patterns of elemental composition, suggesting the existence of a genotype dependent ionome signature. Important negative correlations were found for the concentration of most, but not all, nutrients with yield, thus indicating a potential compromise among beneficial traits. The genotypic variation characterised in the present study has potential to be used in breeding programs aimed at improving wheat grain quality.
Fred Chow: the contributions of a quiet giant of photoinhibition and photoprotection
Authors: Zavafer Alonso , Campbell Douglas A.
Published: February 2021

Wah Soon (Fred) Chow has been a major contributor to photosynthesis research since the late 20th century. Fred, a quiet, gentle, smart and prolific writer, has contributed to our understanding of thylakoid structure, cyclic electron flow and the development of novel methods for phenotyping plants. However, a third of his productivity centres on the understanding of photoinhibition and photoprotection, which we honour herein. We give a brief biographical account of his academic trajectory, followed by a chronological and conceptual summary of his contributions to the field of photodamage and photoprotection. We thereby hope to introduce the work of Fred to young readers and non-experts in the field of photoinhibition.
Domestic dogs and water-availability effects on non-volant mammals in a protected area, south-eastern Brazil
Authors: Monteiro-Alves Priscila Stéfani , Ferreguetti Atilla Colombo , Allemand Marina Mello , Pereira-Ribeiro Juliane , Kajin Maja , Rocha Carlos Frederico Duarte , Bergallo Helena Godoy
Published: February 2021

Abstract Context Urbanisation and human population growth can generate conflicts, threatening biodiversity. Resource availability and vegetation complexity owing to human influence may increase the potential that a habitat would lose its species. Conservation biology aims to understand how to soften human influence and maintain viable in situ populations. Aims We evaluated the non-volant mammal’s richness and abundance in an Atlantic Forest protected area. Specifically, we tested (1) the effect of distance from water resource and vegetation (canopy and understorey cover) on richness and abundance and (2) the effects of anthropogenic pressure such as domestic dog abundance, distances from human settlements, and from the road on the community of non-volant mammals. Methods We collected the data from January through December of 2017 in 20 sampling sites by using live traps (for small mammals), active search, sand plots and camera traps. Key results We recorded 22 species of non-volant mammals, among them four endemic, two endangered and two invasive exotic species. The main covariates that affected the structure and composition of the non-volant mammal’s assemblage was the domestic dog abundance, which repels most of the species into the forest and water resources, which attract the species to forest edges. Conclusions Our results indicated that the negative impact of domestic dog presence in the non-volant mammal’s community is so evident that it could generate changes in the composition, richness, and local distribution of the species. Implications We suggest that management action in this protected area must initiate a control of domestic dogs to minimise their impact.
A machine-learning approach to map landscape connectivity in
Aedes aegypti
with genetic and environmental data
Authors: Pless Evlyn , Saarman Norah P. , Powell Jeffrey R. , Caccone Adalgisa , Amatulli Giuseppe
Published: February 2021

Significance

Aedes
mosquitoes are projected to continue expanding their ranges, which could expose millions more humans to the diseases they carry. The implementation of vector control methods ranging from traditional (e.g., insecticides) to cutting edge (e.g., genetic modification) could be improved with landscape connectivity maps and increased understanding of the factors that affect mosquito dispersal. Here we present an iterative random forest method for integrating genetic and environmental data to map landscape connectivity. We achieve a correlation of 0.83 between the model’s predicted genetic distance and actual genetic distance. We produce a genetic connectivity map for the southern tier of the United States and discuss important factors to consider in mosquito control, e.g., the release of genetically modified mosquitoes.
African burned area and fire carbon emissions are strongly impacted by small fires undetected by coarse resolution satellite data
Authors: Ramo Ruben , Roteta Ekhi , Bistinas Ioannis , van Wees Dave , Bastarrika Aitor , Chuvieco Emilio , van der Werf Guido R.
Published: February 2021

Significance

Fires burn an area comparable to Europe each year, emitting greenhouse gases and aerosols. We compared burned area (BA) based on 20-m resolution images with a BA derived from 500-m data. It represents an 80% increase in BA in sub-Saharan Africa, responsible for about 70% of global BA. This difference is predominately (87%) attributed to small fires (<100 ha), which account for 41% of total BA but only for 5% in coarse-resolution products. We found that African fires were responsible for emissions of 1.44 PgC, 31–101% higher than previous estimates and representing 14% of global CO
2
emissions from fossil fuel burning. We conclude that small fires are critically important in characterizing the most important disturbance agent on a global scale.
TIA1 potentiates tau phase separation and promotes generation of toxic oligomeric tau
Authors: Ash Peter E. A. , Lei Shuwen , Shattuck Jenifer , Boudeau Samantha , Carlomagno Yari , Medalla Maria , Mashimo Bryce L. , Socorro Guillermo , Al-Mohanna Louloua F. A. , Jiang Lulu , Öztürk Muhammet M. , Knobel Mark , Ivanov Pavel , Petrucelli Leonard , Wegmann Susanne , Kanaan Nicholas M. , Wolozin Benjamin
Published: February 2021

Significance

Phase separation of proteins is increasingly thought to play a fundamental role in biological processes. Recent studies show that tau protein phase separates, but the biological significance is unknown since artificial crowding agents are typically used and the resulting tau is not toxic. We now demonstrate that TIA1 potentiates RNA-mediated phase separation of tau, thereby enabling a process that occurs at physiological concentrations and also directs the formation of biologically active, highly neurotoxic oligomeric tau. Coordinated phase separation of functionally related proteins provides a general mechanism through which membraneless organelles can direct biological activities.
Bromodomain proteins regulate human cytomegalovirus latency and reactivation allowing epigenetic therapeutic intervention
Authors: Groves Ian J. , Jackson Sarah E. , Poole Emma L. , Nachshon Aharon , Rozman Batsheva , Schwartz Michal , Prinjha Rab K. , Tough David F. , Sinclair John H. , Wills Mark R.
Published: February 2021

Significance

Human cytomegalovirus (HCMV) reactivation is a major cause of posttransplant morbidity/mortality. One approach toward reducing this is purging the transplant donor and/or recipient of latently infected cells prior to stem-cell or organ harvest/engraftment. Our findings show the involvement of host bromodomain (BRD) proteins in regulation of HCMV latency and reactivation. Bromodomain and extra-terminal inhibitor (I-BET) treatment of latently infected cells causes reactivation of lytic gene expression by release of transcription activator P-TEFb (CDK9/CycT1) from BRD4-associated repressive complexes, with subsequent recruitment via host superelongation complex (SEC). This results in immune targeting and T cell-mediated killing of these otherwise latently infected cells and provides a therapeutic “shock and kill” strategy that could reduce HCMV-mediated disease in the transplant setting.
An increase in dendritic plateau potentials is associated with experience-dependent cortical map reorganization
Authors: Pagès Stéphane , Chenouard Nicolas , Chéreau Ronan , Kouskoff Vladimir , Gambino Frédéric , Holtmaat Anthony
Published: February 2021

Significance

Here we describe a mechanism for cortical map plasticity. Classically, representational map changes are thought to be driven by changes within cortico-cortical circuits, e.g., Hebbian plasticity of synaptic circuits that lost vs. maintained an excitatory drive from the first-order thalamus, possibly steered by neuromodulatory forces from deep brain regions. Our work provides evidence for an additional gating mechanism, provided by plateau potentials, which are driven by higher-order thalamic feedback. Higher-order thalamic neurons are characterized by broad receptive fields, and the plateau potentials that they evoke strongly facilitate long-term potentiation and elicit spikes. We show that these features combined constitute a powerful driving force for the fusion or expansion of sensory representations within cortical maps.
Personal and Professional Attitudes Associated with Nurses’ Motivation to Work with Patients with Opioid use and Opioid Use-Related Problems
Authors: Mahmoud Khadejah F. , Finnell Deborah S. , Sereika Susan M. , Lindsay Dawn , Schmitt Karen , Cipkala-Gaffin Janet , Puskar Kathryn R. , Mitchell Ann M.
Published: February 2021

Background

Opioid use and opioid use-related problems contribute significantly to increased morbidity rates and premature deaths as well as an increased economic burden. Nurses have key roles in providing care to this patient population; however, they often report low motivation toward working with these patients. Examining personal and professional attitudes associated with nurses’ motivation to work with this population can present a valuable opportunity to enhance their willingness to intervene at an earlier stage when patients do not have a diagnosable opioid use disorder.

Methods

A descriptive, correlational design was used. Nurses were recruited from four hospital settings in Southwestern Pennsylvania. Data on nurses’ demographic/background characteristics, personal attitudes, professional attitudes, and motivation related to working with patients with opioid use and opioid use-related problems were collected via a paper/pencil survey and analyzed using linear regression.

Results

A sample of 234 nurses were included in the final analyses. Personal attitudes associated with nurses’ motivation included personal experience with a family member related to alcohol and/or other drugs, and stigma perceptions (familiarity, perceived dangerousness, fear, social distance and personal responsibility beliefs). Professional attitudes associated with nurses’ motivation included working experience with substance use (SU), SU education as continuing education or other educational resources, role security, therapeutic commitment, role responsibility, and self-efficacy.

Conclusions

This study's findings provide valuable information regarding the bivariate relationships between nurses’ personal attitudes, professional attitudes, and motivation to work with patients with opioid use and opioid use-related problems. The study provides a base for future studies aimed at developing interventions to enhance nurses’ motivation to work with this patient population particularly related to preventing the progression of opioid use to a diagnosable disorder.
Understanding Barriers to Treatment among Individuals not Engaged in Treatment who Misuse Opioids: A Structural Equation Modeling Approach
Authors: Cavazos-Rehg Patricia , Xu Christine , Krauss Melissa J. , Min Caroline , Winograd Rachel , Grucza Richard , Bierut Laura J.
Published: February 2021

Background

Many individuals misusing opioids do not enter into treatment. The question of who enters into treatment for their opioid abuse and under what circumstances is complex and shaped by multiple factors. The objective of the current study is to explore the risk factors for wide-ranging and numerous barriers to treatment among social media users.

Method

Opioid-related forums within a popular social media platform were used to recruit non-treatment engaged individuals (≥15 years) who had misused opioids in the past month ( n = 144; 66% male; median age 28). Four treatment barrier factors were identified utilizing principle component analysis: (1) stigma, (2) awareness, (3) attitudinal, and (4) denial. A structural equation model (SEM) was then created to explore the risk factors for different types of barriers to OUD treatment.

Results

The most common barriers among participants not engaged in treatment for their opioid misuse were the belief that one should be able to help themselves with their condition (66%), treatment was too expensive (63%), and worries about being labeled or judged (57%). Additionally, SEM results demonstrate stigma barriers, awareness, and attitudinal barriers were associated with mental health comorbidities, opioid abuse and dependence severity, and treatment history. Denial barriers, however, were only associated with treatment history, and structural/financial barriers were only associated with opioid abuse and dependence severity.

Conclusions

Our research findings are relevant for underscoring the wide-ranging and numerous barriers to treatment faced by individuals misusing opioids that are especially concentrated among those who also struggle with comorbid mental illness.
Clinical features and outcomes of childhood polyarteritis nodosa: A single referral center experience
Authors: Tekgöz Nilüfer , Aydın Fatma , Kurt Tuba , Sezer Müge , Tekin Zahide , Karagöl Cüneyt , Çakar Nilgün , Acar Banu
Published: February 2021

Objectives

The aims of this study were to describe the clinical features, comorbidities and outcome of systemic childhood polyarteritis nodosa (PAN) and to evaluate PAN-like diseases in differential diagnosis.

Methods

The study group consisted of patients who were diagnosed as PAN in a referral center in Turkey. The files of all patients were reviewed retrospectively. Disease activity was evaluated with pediatric vasculitis activity score (PVAS).

Results

A total of 19 (13 boys/six girls) patients were enrolled in the study. The mean age of patients was 10.37 ± 3.6 years. The mean duration of follow-up was 5.73 ± 3.74 years. Eight patients (42.1%) were also diagnosed with familial Mediterranean fever (FMF). The cutaneous involvement was higher in patients with PAN than those with FMF-associated PAN (p = .03). The median (min–max) PVAS at diagnosis was 5 (3–7). There was no correlation between PVAS scores at the time of diagnosis and age, clinical findings and relapse. CECR1 mutation was detected in one patient leading to deficiency of adenosine deaminase 2.

Conclusion

The clinical presentation is variable in children with PAN. PAN-like diseases characterized by necrotizing vasculitis should be considered. The possibility of FMF should be kept in mind if inflammation cannot be controlled.
Single-nucleotide methylation specifically represses type I interferon in antiviral innate immunity
Authors: Gao Zheng-jun , Li Wen-ping , Mao Xin-tao , Huang Tao , Wang Hao-li , Li Yi-ning , Liu Bao-qin , Zhong Jiang-yan , Renjie Chai , Jin Jin , Li Yi-yuan
Published: February 2021

Frequent outbreaks of viruses have caused a serious threat to public health. Previous evidence has revealed that DNA methylation is correlated with viral infections, but its role in innate immunity remains poorly investigated. Additionally, DNA methylation inhibitors promote IFN-I by upregulating endogenous retrovirus; however, studies of intrinsically demethylated tumors do not support this conclusion. This study found that Uhrf1 deficiency in myeloid cells significantly upregulated Ifnb expression, increasing resistance to viral infection. We performed whole-genome bisulfite sequencing and found that a single-nucleotide methylation site in the Ifnb promoter region disrupted IRF3 recruitment. We used site-specific mutant knock-in mice and a region-specific demethylation tool to confirm that this methylated site plays a critical role in regulating Ifnb expression and antiviral responses. These findings provide essential insight into DNA methylation in the regulation of the innate antiviral immune response.
SIM.QM-S10: supplementary comparison for trace elements in skim milk powder
Authors: Grinberg Patricia , Mester Zoltan , Gatti Patricia , Acosta Osvaldo , Puelles Mabel , Delgado Mabel , Sena Rodrigo Caciano de , Almeida Marcelo Dominguez de , Rocha Marcia Silva da , Sandoval Soraya , Núñez Claudia , Vera Javier , Chao Wei , Xiao Li , Quezada Henry Torres , Torres Gina , Garzón Diego A , Ahumada Diego A , Padilla Jimmy Venegas , Ovares Katia Rosales , Calderón Jiménez Bryan , Vasco Evelyn , Contreras Laura Regalado , Osuna Mariana Arce , Jacimovic Radojko , Zuliani Tea , Laitip Nunnapus , Thiengmanee Usana , Ornthai Nattikarn , Phukphatthanachai Pranee , Taebunpakul Suttinun , Klich Hanen
Published: February 2021

Main text

SIM.QM-S10 was performed to assess the analytical capabilities of National Metrology Institutes (NMIs) and Designated Institutes (DIs) of SIM members (or other regions) for the accurate determination of trace metals in skim milk powder. The study was proposed by the coordinating laboratories National Research Council Canada (NRC) and INTI Argentina as an activity of Sistema Interamericano de Metrología (SIM) approved by the Inorganic Analysis Working Group (IAWG) of Consultative Committee for Amount of Substance - Metrology in Chemistry and Biology (CCQM). Participants included NMIs/DIs from twelve countries. No measurement method was prescribed by the coordinating laboratories. Therefore, NMIs used measurement methods of their choice. However, the majority of NMIs/DIs used closed vessel microwave system using a mixture of HNO3 and H2O2 for the digestion and ICP-MS and ICP-OES for the determination of the measurands. One laboratory used INAA technique.

This SIM.QM-S10 Supplementary Comparison provides NMIs/DIs with the needed evidence for CMC claims for trace elements in skim milk powder and similar matrices.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Applications of the Hawking energy on lightcones in cosmology
Authors: Stock Dennis
Published: February 2021

The past lightcone of an observer in a cosmological spacetime is the unique geometric structure directly linked to observations. After general properties of the Hawking energy along slices of the past lightcone have previously been studied, the present work continues along this path by providing explicit cosmological applications of the Hawking energy associated with a lightcone. Firstly, it is shown that amongst all two-dimensional non-trapped spheres with equal area and average matter density, a shear-free matter distribution maximizes the Hawking energy for sufficiently high densities. Secondly, a Robertson–Walker reference slice is constructed for every lightcone slice based on area and energy. Thirdly, after a few pedagogical examples in concrete FLRW spacetimes, the implications of monotonicity of the energy down the lightcone are explored, arriving at two new bounds on the cosmic fluid’s density and equation-of-state parameter.
Lamination of transparent conductive adhesives for tandem solar cell applications
Authors: Klein Talysa R , Young Michelle S , Tamboli Adele C , Warren Emily L
Published: February 2021

A transparent conductive adhesive (TCA) interlayer for mechanically stacked multijunction solar cells provides adhesive strength and electrical connection between sub-cells when stacked. The fabrication of TCA sheets from an ethyl-vinyl acetate (EVA) matrix and silver coated compliant conductive microspheres, similar to industry-standard EVA encapsulant sheets, compatible with a standard lamination process was developed. Blade coating TCA sheets using 3D printed blades and testing of vertical conduction through the interlayer with a TCA conductivity jig allowed for reproducible measurements and low-cost fabrication. The supplemental information provides design files to enable other researchers to produce their own blades and testing jigs. We identified 0.5 mm as an optimal blade height for producing lab-scale TCA sheets and 120 °C at 3 psi for 10 min as the optimal vacuum lamination process to minimize resistance and possible damage to samples. For TCA sheets with coverages between 0.75% and 9%, the series resistance was approximately 0.2 Ω cm2 which should result in minimal losses for one-sun photovoltaic applications.
Tuning plasma parameters to control reactive species fluxes to substrates in the context of plasma catalysis
Authors: Jiang Jingkai , Bruggeman Peter J
Published: February 2021

The key reactive plasma-produced gas phase species responsible for the enhanced conversion of chemicals in plasma catalysis compared to thermal catalysis have to date not been identified. This outstanding question is mainly due to the inherent large variety of plasma-produced species and the challenge of controlling and measuring the flux of each constituent of the cocktail of reactive species to a (catalytic) substrate. In this paper, we explore the possibility to control the dominant reactive species fluxes, relevant for plasma–catalysis, to a substrate in the effluent of an RF driven Ar–O2 plasma jet. The absolute species densities of the major reactive species (O, O2(a
1Δg), O3 and ions) were quantified by molecular beam mass spectrometry (MBMS) to assess the possibility of using treatment distance, O2 admixture concentration, plasma dissipated power, RF modulation frequency and duty cycle as well as the feed gas flow rate to alter the dominant species densities. Selected experimental results were also compared with a pseudo-1D plug flow model. The short-lived and long-lived species can be effectively separated by changing the treatment distance and the RF modulation frequency. Furthermore, adjusting the O2 admixture concentration enables to change the ratio of the O2(a
1Δg) and O3 density. The changes in the trend of ion and O flux were found to be very similar for nearly all investigated parameters. Nonetheless the gas flow rate was able to significantly change the ratio of the O and ion density in the plasma jet effluent. The impact of the surface-dependent loss probability and boundary layer reactions on the species flux to a substrate and how this qualitatively relates to the MBMS density measurements is further addressed.
Structure-activity correlation of Ti2CT2 MXenes for C–H activation
Authors: Niu Kaifeng , Chi Lifeng , Rosen Johanna , Björk Jonas
Published: February 2021

As a bourgeoning class of 2D materials, MXenes have recently attracted significant attention within heterogeneous catalysis for promoting reactions such as hydrogen evolution and C–H activation. However, the catalytic activity of MXenes is highly dependent on the structural configuration including termination groups and their distribution. Therefore, understanding the relation between the structure and the activity is desired for the rational design of MXenes as high-efficient catalysts. Here, we present that the correlation between the structure and activity of Ti2CT2 (T is a combination of O, OH and/or F) MXenes for C–H activation can be linked by a quantitative descriptor: the hydrogen affinity (E
H). A linear correlation is observed between the mean hydrogen affinity and the overall ratio of O terminations (x
O) in Ti2CT2 MXenes, in which hydrogen affinity increases as the x
O decreases, regardless to the species of termination groups. In addition, the hydrogen affinity is more sensitive to the presence of OH termination than F terminations. Moreover, the linear correlation between the hydrogen affinity and the activity of Ti2CT2 MXenes for C–H activation of both –CH3 and –CH2– groups can be extended to be valid for all three possible termination groups. Such a correlation provides fast prediction of the activity of general Ti2CT2 MXenes, avoiding tedious activation energy calculations. We anticipate that the findings have the potential to accelerate the development of MXenes for heterogeneous catalysis applications.
Tritium in environmental objects in the area affected by FSUE Mayak Production Association in 2014–15
Authors: Vostrotin V V , Yanov A Y , Finashov L V
Published: February 2021

Comparison of tritium volume activity (VA) rates in objects of environment in the Mayak Production Association (Mayak PA) affected area in the period from 2014 to 2015 with tritium VA rates in the same or similar objects of environment measured in the period from 2001 to 2013. Water samples from environmental objects—precipitations, ponds, wells—were the material for this research. Tritium VA in various environmental objects was measured using liquid scintillation method. The results were processed using parametric and nonparametric methods of statistical analysis. In samples collected in 2014–15 from open reservoirs located in Mayak PA affected area tritium VA was 1.4 times lower than the level of tritium VA in water samples from the same reservoirs collected in 2001–03. There was no statistically significant difference between tritium VA in water samples from the same open reservoirs collected in periods 2009–12 and 2014–15. Tritium VA in the water sample from production reservoir R-2 (lake Kyzyltash) in 2015 made 11 200 Bq l−1 that was 1.7 times higher than average rate in 2007–09. In water samples collected in 2014 from 11 wells and boreholes located in the affected area of Mayak PA tritium VA made in average 22 ± 5 Bq l−1. No statistically significant difference was detected in water samples taken from boreholes in 2005–06 and in 2014. Comparison of median values revealed a statistically significant 3.2 times decrease of tritium VA in samples of daily precipitations in Ozyorsk in the time interval between 2007 and 2014. In single samples of daily precipitation in 2007, 2014 and 2015 tritium VA in Ozyorsk made 1020, 145 and 3500 Bq l−1 respectively that in respect exceeded the median values 29 times in 2007, 13 times in 2014 and 160 times in 2015. This could indicate irregular tritium air emissions from Mayak PA that provides ground for necessity of tritium VA monitoring not only in daily precipitation but also in air vapor condensate. Decrease of tritium VA in water samples from open reservoirs from the period of 2001–03 to 2014–15 as well as decrease of the levels of tritium VA in samples of daily precipitation from 2007 to 2014 could be an evidence of possible decrease of tritium atmospheric emission from Mayak PA.
High stability of photovoltaic cells with phenethylammonium iodide-passivated perovskite layers and printable copper phthalocyanine-modified carbon electrodes
Authors: Wu Yue , Wang Shiyu , Ouyang Tao , Li Wenhui , Chen Mingyue , Lu Yu , Qi Pengcheng , Tang Yiwen
Published: February 2021

Defects caused by the structural disorder of perovskites and voltage loss resulting from mismatched band structure are important issues to address to improve the performance of carbon-based perovskite solar cells. Different from the conventional approaches of additive-based passivation of perovskite precursors and introducing a hole-transport layer between the perovskite layer and carbon electrode, herein we report a defect-healing method using phenethyl ammonium iodide (PEAI) treatment and band-structure modification using high-work-function inorganic copper phthalocyanine (CuPc). Because of its relatively smoother surfaces and lower defect content, the optimized device after PEAI-based passivation of the perovskite achieves a power conversion efficiency (PCE) of 11.74%. The PCE is further raised to 13.41% through the auxiliary energy-level matching and high hole extraction abilities of the CuPc-modified carbon electrode. The best-performing device exhibits excellent moisture tolerance and thermal stability with minor current density–voltage hysteresis.
Effect of ZnO nanorods and nanotubes on the electrical and optical characteristics of organic and perovskite light-emitting diodes
Authors: Mohammadnejad Shahram , Ahadzadeh Shabnam , Nouri Rezaie Mahdiyar
Published: February 2021

Due to their suitable electrical and optical properties, ZnO nanostructure-based organic light-emitting diodes (LEDs) and perovskite LEDs can be utilized in the optoelectronics industry. A combination of ZnO nanorods and nanotubes with various types of polymers or hybrid perovskites leads to better waveguides and transportation of carriers. Therefore, more efficient LEDs are offered to the industry. In this research, four devices, including ZnO nanorod (nanotube)/MEH-PPV (CH3NH3PbI3) LEDs are simulated by SILVACO TCAD software. To provide deeper understanding of the impact of applying nanorods and nanotubes in hybrid heterostructures, an ab initio study has been conducted and the electronic structure, density of states, absorption coefficient and dielectric function of each of these nanostructures have been scrutinized. Subsequently, the obtained data have been utilized in the SILVACO simulation, and characteristics such as the current–voltage curve, light power–voltage curve, electroluminescence (EL) spectra and radiative recombination rate of four devices have been investigated. By employing a combination of a perovskite layer and ZnO nanotubes, the turn-on voltage of the simulated devices has been decreased from 13.7 V to 1.1 V. Moreover, a drastic increment in ultraviolet emission from devices based on ZnO nanotubes can be seen, which stems from occurrence of the whispering gallery mode and low defects of nanotubes compared to nanorods. A redshift caused by a reduction in the band gaps of the nanostructures can also be observed in the EL spectra.
Inverting logic-in-memory cells comprising silicon nanowire feedback field-effect transistors
Authors: Park Young-Soo , Lim Doohyeok , Son Jaemin , Jeon Juhee , Cho Kyoungah , Kim Sangsig
Published: February 2021

In this paper, we propose inverting logic-in-memory (LIM) cells comprising silicon nanowire feedback field-effect transistors with steep switching and holding characteristics. The timing diagrams of the proposed inverting LIM cells under dynamic and static conditions are investigated via mixed-mode technology computer-aided design simulation to verify the performance. The inverting LIM cells have an operating speed of the order of nanoseconds, an ultra-high voltage gain, and a longer retention time than that of conventional dynamic random access memory. The disturbance characteristics of half-selected cells within an inverting LIM array confirm the appropriate functioning of the random access memory array.
Numerical analysis of magnetic levitation forces for bulk superconductors with different superconducting junctions between multiple-seed-growth domains
Authors: Sawamura Mitsuru , Izumi Mitsuru
Published: February 2021

We studied magnetic levitation forces for bulk superconductors through numerical analysis. We virtually varied the superconducting junctions between domains formed through multiple seeding (four seeds) and investigated the effect of the following parameters on the magnetic levitation force: (1) the critical current density
J
c
across grain boundaries (GBs) or superconducting junctions between crystal domains.
J
c
across GBs was varied from 0% to 100% of the base material’s
J
c
and (2) the depth of the insulation phase (0% of the base material’s
J
c
) formed between domains. For parameters in (a), we found that in the presence of superconducting junctions between crystal domains with less than 50% for the ratio of
J
c
to the base materials’
J
c
, the magnetic levitation force decreased significantly under the conditions where the superconducting bulk and the permanent magnet face each other like this study. Furthermore, for 100% of the base
J
c
, the largest levitation force was generated by the first layer (0–1 mm thick), while with a reduced superconducting junction (25% of
J
c
to 0% of
J
c
), the deeper layers also contributed to the levitation force. For the parameters in (2), even a thin insulation phase layer between crystal domains significantly affected the magnetic levitation force, and different bulk layers (each 1 mm thick) below the insulation phase showed different levels of contribution to the levitation force.
The role of fluid flow in the dynamics of active nematic defects
Authors: Angheluta Luiza , Chen Zhitao , Marchetti M Cristina , Bowick Mark J
Published: February 2021

We adapt the Halperin–Mazenko formalism to analyze two-dimensional active nematics coupled to a generic fluid flow. The governing hydrodynamic equations lead to evolution laws for nematic topological defects and their corresponding density fields. We find that ±1/2 defects are propelled by the local fluid flow and by the nematic orientation coupled with the flow shear rate. In the overdamped and compressible limit, we recover the previously obtained active self-propulsion of the +1/2 defects. Non-local hydrodynamic effects are primarily significant for incompressible flows, for which it is not possible to eliminate the fluid velocity in favor of the local defect polarization alone. For the case of two defects with opposite charge, the non-local hydrodynamic interaction is mediated by non-reciprocal pressure-gradient forces. Finally, we derive continuum equations for a defect gas coupled to an arbitrary (compressible or incompressible) fluid flow.
A novel polymer/ceramic composite film for different optical applications: optical linear, nonlinear, and limiting properties
Authors: Abdel-Aziz M M , Algarni H , Ali H Elhosiny , Yahia I S , Khairy Yasmin , Zahran H Y , Abdellahi M O , Al-Hagan O , Solyman S
Published: February 2021

New composite films based on ceramic/polymeric matrix materials were synthesized using facile casting procedures for different optical devices. Herein, the composite comprises a semi-crystalline polymer (Polyvinyl alcohol, PVAL) embedded with various weight percentages of PbTiO3. The structure and surface morphology change of PVAL were studied via XRD (Diffraction of x-ray) and SEM (Microscopy of Scanning Electron) analysis. The interactions between PVAL and PbTiO3, via the matrix’s hydroxyl group, demonstrate a significant reduction in polymer crystallinity. Different parameters, such as internal strain, dislocation density, and crystallite size, were estimated from the XRD Gaussian fitting. SEM images show that the particles’ agglomeration increased on the composite’s surface with the doping ratio, which can influence the PVAL optical properties. The energy of the bandgap is estimated using absorption fitting and Tauc’s relations. Nonlinear and refractive indices parameters- energy gap relations were studied. The nonlinear parameters χ
(3) and n

2
increased with rising the percentage of PbTiO3 in the PVAL matrix from 0.935 × 10−12 esu to 1.978 × 10−12 esu, and 1.67 × 10−11 esu to 3.29 × 10−11 esu. Moreover, the high-frequency dielectric (

ε

∞

) changes from 4.421 to 5.125. The behavior of optical limiting for the composites shows a decrease of He-Ne and green laser power. The present results indicate that the polymeric/ceramic films can be promising materials for laser CUT-OFF, optical fibers, and micro-optics applications.