bluuebunny/crossref_metadata_2025 huggingface dataset:
Examination of possible high-pressure candidates of SnTiO3: The search for novel ferroelectric materials
Authors: Pielnhofer Florian , Diehl Leo , Jiménez-Solano Alberto , Bussmann-Holder Annette , Schön J. Christian , Lotsch Bettina V.
Published: February 2021

Following the recent successful synthesis and characterization of bulk SnTiO3, its energy landscape was studied by means of density functional theory, applying different exchange–correlation and hybrid functionals. Experimentally accessible structure candidates with composition ABX3 were identified by a database search and global exploration approach. Besides the common octahedral coordination of Ti, also fourfold and fivefold coordination spheres emerged to be reasonable structural motifs. Among the predicted high-pressure modifications, the tetragonal perovskite structure turned out to be stable at pressures between 11 GPa and 15 GPa. The possibility of a paraelectric-to-ferroelectric phase transition of the tetragonal perovskite structure was investigated by modeling the phonon spectra and soft mode behavior. Despite substantial long wavelength transverse optical mode softening, the predicted high c/a-ratio in tetragonal perovskite SnTiO3 inhibits the formation of a spontaneous reversible polarization.
Long-range oscillations of a laser-produced carbon plasma recorded by an electrostatic energy analyzer
Authors: Nica Petru-Edward , Ursu Cristian , Focsa Cristian
Published: February 2021

Understanding peculiar dynamics in transient laser-produced plasmas is of great importance for a number of applications such as energetic ion production, ion implantation, laser micro-machining, etc. Continuing a series of papers on the electrical and optical characterization of laser ablation plasma plumes, we report here on the observation of oscillations in the ionic and electronic currents at a long distance (17.5 cm) from the ablation target. An electrostatic energy analyzer was used to finely probe the dynamics of charge carriers in a carbon plasma generated in vacuum by KrF excimer laser ablation of a graphite target. A short-time Fourier transform data processing approach was applied to extract valuable information from the recorded currents. This method not only reveals different frequencies for two distinct expanding plasma structures, but also unveils different trends in their temporal evolution. These new experimental results corroborate previous studies supporting a scenario based on the plasma structuring in multiple double layers. A discussion with respect to an alternative scenario based on low-frequency sheath instabilities is also presented.
Developing solid-state photon upconverters based on sensitized triplet–triplet annihilation
Authors: Ronchi Alessandra , Monguzzi Angelo
Published: February 2021

Photon upconversion assisted by sensitized triplet–triplet annihilation (sTTA-UC) is a wavelength-shifting technique where high-energy photons are emitted from the radiative recombination of high-energy singlets populated through the annihilation of the metastable triplets of two annihilator/emitter molecules. The emitter triplets are previously populated via energy transfer from a light-harvester/sensitizer moiety that absorbs the incident low-energy photons. In solutions, this process is efficient even at low excitation powers, whereas the limited molecular mobility and short exciton lifetimes typically observed in solid matrices hinder the bi-molecular interactions making the sTTA-UC process rather ineffective. We show here that controlling the confinement of the upconverting dye pairs in nanostructured or nanosized materials results in an increased effective local density of the excitation energy. This also activates a specific sTTA-UC kinetics independent of the triplet excitons’ mobility that improves the material performance at low powers. We provide a complete modeling of the sTTA-UC process in confined systems. The results obtained afford useful guidelines for the future development of upconverting photonic devices operating at subsolar irradiances suitable for technological implementation.
Acoustic holograms for directing arbitrary cavitation patterns
Authors: Kim Jinwook , Kasoji Sandeep , Durham Phillip G. , Dayton Paul A.
Published: February 2021

Cavitation is an important phenomenon in biomedical acoustics. It can produce both desired outcomes (i.e., local therapeutic effects in vivo) and undesired outcomes (i.e., tissue damage), and it is, thus, important to both understand and direct cavitation fields. Through the use of three-dimensional-printed acoustic lenses and cavitation-sensitive acoustic phantoms, we demonstrate the generation of arbitrary shape two-dimensional (2D) microbubble cavitation fields. In this study, we demonstrate shaping a 1 MHz acoustic beam as the character “7” on a target plane that contains a higher mechanical index than the cavitation threshold for encapsulated microbubbles in a gelatin phantom. The lens pattern is first designed by calculating the phase map of the desired field using an angular spectrum approach. After lens implementation, acoustic pulsing through the lens generated the target acoustic field in a phantom and produced a cavitation map following the intended 2D pattern. The cavitation pattern was similar (with the structural similarity of 0.476) to the acoustic pressure map of the excitation beam.
Incommensurately modulated structures in Pb(Zr1−xSnx)O3 single crystals by x-ray diffraction
Authors: Jankowska-Sumara Irena , Paściak Marek , Podgórna Maria , Majchrowski Andrzej , Kopecký Miloš , Kub Jiří
Published: February 2021

Pb(Zr1−xSnx)O3 single crystals were characterized using x-ray diffraction as a function of temperature and composition. The information on the structure of two intermediate phases, situated between antiferroelectric and paraelectric phases in the composition–temperature phase diagram, has been obtained. The lower-temperature intermediate phase is characterized by incommensurate displacive modulations in the Pb sublattice. The higher temperature intermediate phase is characterized by distortions of the oxygen sublattice primarily in the form of anti-phase tilts of the oxygen octahedra. The structured diffuse scattering was also observed in the paraelectric phase along Γ–M and M–R lines pointing to the high-temperature correlated disorder of Pb ions and octahedral rotations, respectively.
Low-energy electron impact dissociative recombination and vibrational transitions of N2+
Authors: Abdoulanziz A. , Argentin C. , Laporta V. , Chakrabarti K. , Bultel A. , Tennyson J. , Schneider I. F. , Mezei J. Zs.
Published: February 2021

Cross sections and thermal rate coefficients are computed for electron-impact dissociative recombination and vibrational excitation/de-excitation of the N2+ molecular ion in its lowest six vibrational levels, for collision energies/temperatures up to 2.3 eV/5000 K.
Intense and recoverable piezoluminescence in Pr3+-activated CaTiO3 with centrosymmetric structure
Authors: Yang Liu , Li Lei , Cheng Long-Xiang , Jia Ting-Ting , Hu Fang , Yu Shu-Hui , Sun Rong , Wang Shanshan , Shi Xiaofeng , Zhang Jun-Cheng
Published: February 2021

Recoverable mechanoluminescence (RML) has shown attractive potential in diverse fields of stress sensors, lighting, displays, and bioexcitation. However, efficient RML materials are universally constructed with a noncentrosymmetric lattice as the matrix, encountering limitations in obtaining centrosymmetric lattice availability. In this work, we report an amazing RML in the well-known persistent phosphor CaTiO3:Pr3+ with a centrosymmetric structure, which exhibits intense, reproducible, and quantitative emission under the stimulation of mechanical compression and friction and even hand rubbing. The systematic investigations of thermoluminescence and piezoresponse force microscopy indicate that local piezoelectricity caused by structural defects plays a key role in detrapping the electrons captured by traps, thereby generating recoverable piezoluminescence in CaTiO3:Pr3+. Our results reveal the availability of the centrosymmetric lattice as the material matrix to achieve high-efficiency RML, which is expected to broaden the horizons of designing RML materials.
Comparison on the coercivity enhancement of the sintered NdFeB magnets by grain boundary diffusion with Tb70Cu30 powders prepared by different milling methods
Authors: Wong Y. J. , Hsu W. C. , Chang H. W. , Lee Y. I. , Chang W. C. , Chiu C. H. , Mo C. C.
Published: February 2021

Coercivity enhancement of the sintered NdFeB magnets by grain boundary diffusion (GBD) with Tb70Cu30 powders prepared by different milling methods has been compared. The commercial NdFeB sintered magnets with the magnetic properties of Br=14.0 kG, iHc= 17.5 kOe and (BH)max= 48.4 MGOe are chosen as original magnets. The coercivity increment of the NdFeB magnets is 7.6 kOe and 9.4 kOe after GBD with Tb70Cu30 alloy powders made by high energy ball milling (HEBM) and low-energy ball milling (LEBM), respectively. Higher coercivity increment can be obtained for the magnet GBD treated with Tb70Cu30 powders prepared by LEBM, mainly related to their platelet shape. The platelet shape powders may provide the wider contact area between GBD source and the surface of the magnets. The above effect is helpful in improving diffusion efficiency and enhancing coercivity accordingly. As a result, magnetic properties of Br=13.6 kG, iHc= 25.1 kOe and (BH)max= 46.1 MGOe are achieved.
A purple patch for evidence-based health policy?
Authors: Cormack Mark , Boxall Anne-marie , Hullick Carolyn , Booth Mark , Gruen Russell L.
Published: February 2021

The global focus on nation states’ responses to the COVID-19 pandemic has rightly highlighted the importance of science and evidence as the basis for policy action. Those with a lifelong passion for evidence-based policy (EBP) have lauded Australia’s and other nations’ policy responses to COVID-19 as a breakthrough moment for the cause. This article reflects on the complexity of the public policy process, the perspectives of its various actors, and draws on Alford’s work on the Blue, Red and Purple zones to propose a more nuanced approach to advocacy for EBP in health. We contend that the pathway for translation of research evidence into routine clinical practice is relatively linear, in contrast to the more complex course for translation of evidence to public policy – much to the frustration of health researchers and EBP advocates. Cairney’s description of the characteristics of successful policy entrepreneurs offers useful guidance to advance EBP and we conclude with proposing some practical mechanisms to support it. Finally, we recommend that researchers and policy makers spend more time in the Purple zone to enable a deeper understanding of, and mutual respect for, the unique contributions made by research, policy and political actors to sound public policy.
A chlamydia education and training program for general practice nurses: reporting the effect on chlamydia testing uptake
Authors: Wood Anna , Braat Sabine , Temple-Smith Meredith , Lorch Rebecca , Vaisey Alaina , Guy Rebecca , Hocking Jane
Published: February 2021

The long-term health consequences of untreated chlamydia are an increased risk of pelvic inflammatory disease, ectopic pregnancies and infertility among women. To support increased chlamydia testing, and as part of a randomised controlled trial of a chlamydia intervention in general practice, a chlamydia education and training program for general practice nurses (GPN) was developed. The training aimed to increase GPNs’ chlamydia knowledge and management skills. We compared the difference in chlamydia testing between general practices where GPNs received training to those who didn’t and evaluated acceptability. Testing rates increased in all general practices over time. Where GPNs had training, chlamydia testing rates increased (from 8.3% to 19.9% (difference=11.6%; 95% CI 9.4–13.8)) and where GPNs did not have training (from 7.4% to 18.0% (difference=10.6%; 95% CI 7.6–13.6)). By year 2, significantly higher testing rates were seen in practices where GPNs had training (treatment effect=4.9% (1.1 – 8.7)), but this difference was not maintained in year 3 (treatment effect=1.2% (−2.5 – 4.9)). Results suggest a GPN chlamydia education and training program can increase chlamydia testing up to 2 years; however, further training is required to sustain the increase beyond that time.
Mobile memory clinic: implementing a nurse practitioner-led, collaborative dementia model of care within general practice
Authors: Pond Dimity , Higgins Isabel , Mate Karen , Merl Helga , Mills Dianne , McNeil Karen
Published: February 2021

The limited capacity of secondary health services to address the increasing prevalence of dementia within the community draws attention to the need for an enhanced role for nurses working collaboratively with GPs in diagnosing and coordinating post-diagnostic care for patients with dementia. This study investigated the feasibility and acceptability of a nurse practitioner-led mobile memory clinic that was embedded within general practice and targeted to caring for patients and their carers in areas of socioeconomic disadvantage with poor access to specialist health services. Over the period from mid-2013 to mid-2014, 40 GPs referred 102 patients, with the nurse practitioner conducting assessments with 77 of these patients in their homes. Overall, there was a strong interest in this model of care by general practice staff, with the assessment and care provided by the nurse practitioner evaluated as highly acceptable by both patients and their carers. Nonetheless, there are financial and structural impediments to this model of care being implemented within the current Australian health service framework, necessitating further research investigating its cost-effectiveness and efficacy.
Hormone seasonality in medical records suggests circannual endocrine circuits
Authors: Tendler Avichai , Bar Alon , Mendelsohn-Cohen Netta , Karin Omer , Korem Kohanim Yael , Maimon Lior , Milo Tomer , Raz Moriya , Mayo Avi , Tanay Amos , Alon Uri
Published: February 2021

Significance

We provide a dataset of millions of hormone tests from medical records that shows seasonality with a winter−spring peak in hormones for reproduction, growth, metabolism, and stress adaptation. Together with a long history of studies on a winter−spring peak in human function and growth, the hormone seasonality indicates that, like other animals, humans may have a physiological peak season for basic biological functions. We further use the specific seasonal phases of the hormones to suggest a model for a circannual clock in humans and animals that can keep track of the seasons, similar in spirit to the circadian clock that keeps track of time of day.
Autophagy is required for proper cysteine homeostasis in pancreatic cancer through regulation of SLC7A11
Authors: Mukhopadhyay Subhadip , Biancur Douglas E. , Parker Seth J. , Yamamoto Keisuke , Banh Robert S. , Paulo Joao A. , Mancias Joseph D. , Kimmelman Alec C.
Published: February 2021

Significance

Pancreatic cancer utilizes autophagy to survive stress and promote therapeutic resistance. However, the metabolic contribution of autophagy in PDAC has not been fully elucidated. We report that SLC7A11 function requires autophagy machinery for proper membrane localization in PDAC, allowing proper cystine transport. Our findings continue to support the use of autophagy inhibition as a therapeutic strategy in pancreatic cancer by demonstrating that this leads to inactivation of SLC7A11 and disruption of cysteine homeostasis.
Two weeks of detraining reduces cardiopulmonary function and muscular fitness in endurance athletes
Authors: Chen Yun‐Tsung , Hsieh Yao‐Yi , Ho Jen‐Yu , Lin Tung‐Yi , Lin Jung‐Charng
Published: February 2021

We investigated the effects of 2 weeks of detraining on cardiopulmonary function and muscular fitness in 15 endurance‐trained male athletes (age: 19–26 years; height: 176.1 ± 7.5 cm; body mass: 68.3 ± 7.6 kg). VO2max, exercise time to exhaustion (ET), maximal stroke volume (SVmax), maximal heart rate (HRmax), isokinetic muscle strength, and muscle endurance were measured before and after 2 weeks of detraining. We determined that short‐term detraining resulted in a significant decrease (p < 0.05) in VO2max, ET, SVmax and isokinetic knee extensor strength but not in isokinetic knee flexor strength or muscle endurance. HRmax and body mass increased significantly (p < 0.05), whereas body fat percentage remained stable after detraining. Furthermore, significant correlations were identified between VO2max and SVmax (p < 0.01, r = 0.6) and between VO2max and knee extensor strength (p < 0.01, r = 0.6). The results suggest that 2 weeks of detraining reduces cardiopulmonary functions, possibly as a result of the attenuation of hemodynamic and neuromuscular adaptations. Moreover, we observed that short periods of detraining appeared to increase lean mass and maintain muscle endurance in endurance runners.

Highlights

Two weeks of detraining reduces VO2max, SVmax and muscle strength but maintains muscle endurance in male runners.

Short periods of detraining may enhance anabolic hormonal milieu and increase lean mass.

Detraining reduced cardiopulmonary function is associated with attenuation of hemodynamic and muscle adaptations.
Elasticity theory in general relativity
Authors: Brown J David
Published: February 2021

The general relativistic theory of elasticity is reviewed from a Lagrangian, as opposed to Eulerian, perspective. The equations of motion and stress–energy–momentum tensor for a hyperelastic body are derived from the gauge–invariant action principle first considered by DeWitt. This action is a natural extension of the action for a single relativistic particle. The central object in the Lagrangian treatment is the Landau–Lifshitz radar metric, which is the relativistic version of the right Cauchy–Green deformation tensor. We also introduce relativistic definitions of the deformation gradient, Green strain, and first and second Piola–Kirchhoff stress tensors. A gauge-fixed description of relativistic hyperelasticity is also presented, and the nonrelativistic theory is derived in the limit as the speed of light becomes infinite.
Some considerations for designing a pneumatic micro-droplet generator
Authors: Bao Weijie , Wang Yiwei , Yang Baojun , Wang Zhihai , Wang Yaohong
Published: February 2021

Micro-droplet ejection is a liquid dispensing technology that has potential applications in many fields. Specifically, pneumatic ejection is actuated by a solenoid valve, which is set to ‘conduction’ state for a brief period of time Δt. High pressure gas of P
0 enters the liquid reservoir, then releases through a venting tube, creating a oscillating pressure waveform P(t), forcing the liquid out through a tiny nozzle to form a micro-droplet. For each actuation, P(t) is acquired by a high-speed pressure sensor, and the ejection state is obtained by high-speed photography and image processing methods. Some issues for the design of pneumatic micro-droplet ejector are discussed. For simulation of P(t), it is proposed within an electro-acoustic analogy picture that the acoustic resistance of the venting tube is mainly due to viscous effect and may vary with time during the whole ejection process. Based on this assumption, the calculated P(t) is more consistent with the actual measurement. Experimentally, the droplet ejection process for different length of venting tube is studied. With P
0 and Δt set, by increasing the venting tube length L, both the peak value P
MAX1 and duration of the first positive pressure period increase, and more droplets are ejected from a single actuation. By setting different P
0, P
MAX1 for different L is tuned to an identical and appropriate value, so that single droplet is ejected due to the first positive pressure period. However, with the increase of L, the peak value of the second positive pressure period P
MAX2 increases. There is a certain probability that another droplet is ejected. It is realized that the increase of L can reduce gas consumption, but the multiple ejection is a drawback that should be considered in the design of pneumatic ejection system.
Composition uniformity and large degree of strain relaxation in MBE-grown thick GeSn epitaxial layers, containing 16% Sn
Authors: Rathore Jaswant , Nanwani Alisha , Mukherjee Samik , Das Sudipta , Moutanabbir Oussama , Mahapatra Suddhasatta
Published: February 2021

We systematically investigate the compositional uniformity, degree of strain relaxation (DSR), defect structure and surface morphology of GeSn epitaxial layers with 16% Sn, grown by low temperature molecular beam epitaxy (MBE) on Ge-buffered Si(001) substrates. Combining atom probe tomography, reciprocal space mapping, cross-sectional transmission electron microscopy, and atomic force microscopy analyses, we demonstrate that for a layer thickness of

t

GeSn

=
250

 nm

, a high DSR (∼70%) can be achieved, while maintaining compositional uniformity at the atomic scale. We find no evidence of Sn clustering in the bulk, or Sn segregation to the surface, for at least this value of

t

GeSn

. The observed compositional uniformity contrasts the well-established phenomenon of strain-relaxation enhancement of Sn content in chemical vapour deposition (CVD) growth of GeSn. The defect structure leading to strain relaxation in these MBE-grown GeSn epitaxial layers is also distinctly different from that observed in CVD growth of the alloy. We observe the co-existence of highly strain-relaxed and pseudomorphically strained regions in the grown epilayers, tentatively explained by bunching of threading dislocations. Considering that MBE growth of GeSn epitaxial layers, with such high-Sn content and layer thickness, has not been reported before, our results are encouraging for future improvements in design and fabrication of group-IV-based mid-infrared photonic devices.
Anisotropic thermal conductivity in lattice transition thermal rectifiers
Authors: Alvarez-Quintana J
Published: February 2021

Lattice transition materials can exist in two phases with different thermal conductivities. Because of this, phase change materials (PCMs) are considered as promising next-generation thermal rectifying materials. The performance of a thermal rectifier known as rectification factor (R) is evaluated by the ratio between the heat that preferentially flows in the forward direction and that in the reverse one. In this work, taking into consideration that PCMs have the striking characteristic of high anisotropy, we propose an analytical framework based on the thermal conductivity tensor theory for predicting the R of lattice transition thermal rectifiers. Because of lattice symmetries, model unveils that the rectification factor is ruled, as well as limited by the ratio of the principal thermal conductivity tensor components present in each phase and the thermal conductivity of the invariant phase material. Furthermore, to validate our predictions the model is applied to the existing experimental systems in the literature, providing accurately truthfulness on observed R. Hence, the analytical model is promising from both theoretical and experimental points of view to understand the effects which allow developing a procedure for engineering an enhanced performance thermal rectifying device.
Defect mediated improved charge carrier dynamics in hybrid bulk-heterojunction solar cell induced by phase pure iron pyrite nanocubes
Authors: Sharma Punit , Rana Aniket , Waheed Sobia , Pareek Saurabh , Karak Supravat
Published: February 2021

In this article, the synthesis of phase pure iron pyrite nanocubes (FeS2 NCs) and their various effects on the charge carrier dynamics and photovoltaic performances of P3HT:PC71BM based hybrid bulk-heterojunction solar cells have been studied. The optimum doping concentration of FeS2 NCs was found to be 0.3 wt%. For the optimally doped devices, the short-circuit current density was found to have improved from 5.47 to 7.99 mA cm−2 leading to an overall cell efficiency improvement from 2.10% to 3.22% as compared to the undoped reference devices. The enhancement in photovoltaic performance is mainly attributed to the formation of localized energy states near the band edges leading to higher carrier generation rate by 72% whereas carrier dissociation probability is also increased by 13%. Urbach energy estimation reveals that the optimally doped devices have achieved a relatively balanced amount of localized states resulting in reduced non-radiative recombination. Such localized defect states formation with FeS2 NCs doping was also found to have significant influence over the charge carrier dynamics of the active layer. Transient photocurrent and photovoltage studies revealed that FeS2 NCs assist in faster carrier extraction by reducing the transport time from 1.4 to 0.6 μs and by enhancing carrier recombination time from 51.7 to 78.9 μs for the reference and optimum devices respectively. Such an unorthodox approach of defect state assisted efficiency improvement demonstrates the importance of simultaneously understanding the charge carrier dynamics and photovoltaic performance for rational device optimization, and opens new prospects for developing high-efficiency solution processable hybrid devices.
Temporal feature prior-aided separated reconstruction method for low-dose dynamic myocardial perfusion computed tomography
Authors: Chen Zixiang , Zeng Dong , Huang Zhenxing , Ma Jianhua , Gu Zheng , Yang Yongfeng , Liu Xin , Zheng Hairong , Liang Dong , Hu Zhanli
Published: February 2021

Dynamic myocardial perfusion computed tomography (DMP-CT) is an effective medical imaging technique for coronary artery disease diagnosis and therapy guidance. However, the radiation dose received by the patient during repeated CT scans is a widespread concern of radiologists because of the increased risk of cancer. The sparse few-view CT scanning protocol can be a feasible approach to reduce the radiation dose of DMP-CT imaging; however, an advanced reconstruction algorithm is needed. In this paper, a temporal feature prior-aided separated reconstruction method (TFP-SR) for low-dose DMP-CT images reconstruction from sparse few-view sinograms is proposed. To implement the proposed method, the objective perfusion image is divided into the baseline fraction and the enhancement fraction introduced by the arrival of the contrast agent. The core of the proposed TFP-SR method is the utilization of the temporal evolution information that naturally exists in the DMP-CT image sequence to aid the enhancement image reconstruction from limited data. The temporal feature vector of an image pixel is defined by the intensities of this pixel in the pre-reconstructed enhancement sequence, and the connection between two related features is calculated via a zero-mean Gaussian function. A prior matrix is constructed based on the connections between the extracted temporal features and used in the iterative reconstruction of the enhancement images. To evaluate the proposed method, the conventional filtered back-projection algorithm, the total variation regularized PWLS (PWLS-TV) and the prior image constrained compressed sensing are compared in this paper based on studies on a digital extended cardiac-torso (XCAT) thoracic phantom and a preclinical porcine DMP-CT data set that take image misregistration into account. The experimental results demonstrate that the proposed TFP-SR method has superior performance in sparse DMP-CT images reconstruction in terms of image quality and the analyses of the time attenuation curve and hemodynamic parameters.
Edge turbulence in ISTTOK: a multi-code fluid validation
Authors: Dudson B D , Gracias W A , Jorge R , Nielsen A H , Olsen J M B , Ricci P , Silva C , Tamain P , Ciraolo G , Fedorczak N , Galassi D , Madsen J , Militello F , Nace N , Rasmussen J J , Riva F , Serre E
Published: February 2021

Fluid models used to study the edge plasma region need to be benchmarked against similar conditions given that models can strongly differ in complexity and therefore the results they produce. Via this validation study undertaken through the framework of EUROfusion Enabling Research, four state-of-the art models—GBS, Hermes/BOUT++, hot-edge-sol-electrostatic and TOKAM3X—are compared to experimental plasma turbulence measurements on the ISTTOK tokamak. Statistical comparisons of simulation and experiment data show that fluid models used here can replicate most of the experiment in terms of

I

sat

and

V

float

fluctuations despite their differences. Furthermore, it is shown that without including more complex information (like core turbulence information and domain geometry details and magnetic topological aspects) in fluid models, the results recovered vary from their experimental counterparts. Via the simulations using these codes, it is demonstrated that fluid models continue to be a good cost-effective tool in recovering many global aspects of edge plasma behaviour.
Review on performance analysis of P3HT:PCBM-based bulk heterojunction organic solar cells
Authors: Ghosekar Ishan C , Patil Ganesh C
Published: February 2021

Due to their low production costs, small weight, printability, solution processing, and the possibility of using flexible substrates, organic solar cells (OSCs) exhibit strong potential to be used in future solar cell technology. Major specifications for the commercialization of OSCs are the long life span of OSC devices, enhanced environmental stability and a sufficiently high power conversion efficiency (PCE). The development of low energy gap organic polymers, transport materials and multi-layer system architecture has been effective in achieving higher PCE. However, overcoming environmental stability and sustaining a longer life span are a major challenge. The instability of OSCs is the dynamic mechanism, mostly induced due to the combined impact of oxygen, incident light, and ambient, as well as processing, temperature. Studies have reported that thermal annealing of the active layer tends to a shift in the phase morphology, which typically occurs either because of the vertical phase separation or because of the process of donor–acceptor phase segregation. In this paper, various factors that affect the performance of the OSC have been comprehensively studied. Factors such as thermal stress, vertical phase segregation, material composition and tradeoff between thickness and light absorption have been discussed. This paper mainly reviews the measures carried out to improve the efficiency of conventional polymer-fullerene-based bulk-heterojunction OSCs and reports the different techniques to address these issues.
Three-dimensional constitutive model for shape-memory polymers considering temperature-rate dependent behavior
Authors: Kim Jinsu , Jeon Seung-Yeol , Hong Seokbin , An Yongsan , Park Haedong , Yu Woong-Ryeol
Published: February 2021

The temperature-rate dependent thermomechanical behavior of shape-memory polymers (SMPs) is challenging to study, because the microstructure of SMPs cannot rearrange instantaneously to an equilibrium configuration in response to temperature changes. Herein, we report a temperature-rate dependent three-dimensional constitutive model for SMPs based on a two-phase model consisting of rubbery and glassy phases. To describe the effect of temperature rate on SMPs, the variation of the volume fraction of each phase affected by temperature was considered under different temperature-rate conditions. Additionally, the temperature-rate dependent thermal strain was incorporated into the two-phase model. The developed constitutive model was validated by simulating the shape-memory behavior of SMPs, and by comparing the simulation and experimental results under different temperature-rate conditions.
Spatial-dependent probe transmission based high-precision two-dimensional atomic localization
Authors: Idrees Muhammad , Kalsoom Humaira , Bacha Bakth Amin , Ullah Arif , Wang Li-Gang
Published: February 2021

Herein, we propose a scheme for the realization of two-dimensional atomic localization in a λ-type three-level atomic medium such that the atom interacts with the two orthogonal standing-wave fields and a probe field. Because of the spatially dependent atom-field interaction, the information about the position of the atom can be obtained by monitoring the probe transmission spectra of the weak probe field for the first time. A single and double sharp localized peaks are observed in the one-wavelength domain. We have theoretically archived high-resolution and high-precision atomic localization within a region smaller than λ/25 × λ/25. The results may have potential applications in the field of nano-lithography and advance laser cooling technology.
Attenuation characteristics of obliquely incident electromagnetic wave in weakly ionized dusty plasma based on modified Bhatnagar–Gross–Krook collision model*
Authors: Wang Zhaoying , Guo Lixin , Li Jiangting
Published: February 2021

The attenuation characteristics of obliquely incident electromagnetic (EM) wave in L-Ka frequency band in weakly ionized dusty plasma are analyzed based on the modified Bhatnagar–Gross–Krook (BGK) collision model. According to the kinetic equation and the charging theory, the total complex dielectric constant of the weakly ionized dusty plasma is derived by considering that the minimum velocity of the electron accessible to the dust particle surface is non-zero and the second potential part of the collision cross-section contributes to the charging. The attenuation characteristics within the modified model are compared with those within the traditional model. The influence of the dusty plasma parameters and the incident angle of EM waves on the attenuation in weakly ionized dusty plasma is further analyzed. Finally, the influence of different reentry heights on the attenuation characteristics of the obliquely incident EM wave is discussed. The results show that the effect of the minimum electron velocity and the second term of the collision cross-section on the attenuation characteristics of EM waves cannot be ignored. When the dust density and dust radius are changed, the trends of the attenuation of obliquely incident EM waves are consistent, but the influence of dust density is weaker than that of dust radius due to the constraint of orbit-limited motion (OLM) theory. The plasma thickness, electron density, and incident angle are proportional to the attenuation amplitude of EM waves. The effect of different reentry heights on the attenuation obliquely incident EM waves is related to the electron density and plasma thickness.
Characterization of inner layer thickness change of a composite circular tube using nonlinear circumferential guided wave: A feasibility study*
Authors: Li Ming-Liang , Gao Guang-Jian , Deng Ming-Xi
Published: February 2021

The feasibility of using the nonlinear effect of primary circumferential guided wave (CGW) propagation for characterizing the change of inner layer thickness of a composite circular tube (CCT) has been investigated. An appropriate mode pair of the fundamental and double-frequency CGWs (DFCGWs) has been selected to enable the second harmonics of primary wave mode in the given CCT to accumulate along the circumferential direction. When changes in the inner layer thickness (described as the equivalent inner layer thickness) take place, the corresponding nonlinear CGW measurements are conducted. It is found that there is a direct correlation between change of equivalent inner layer thickness of the CCT and the relative acoustic nonlinearity parameter (Δβ) measured with CGWs propagating through one full circumference, and that the effect of second-harmonic generation (SHG) is very sensitive to change in the inner layer thickness. The experimental result obtained demonstrates the feasibility for quantitatively assessing the change of equivalent inner layer thickness in CCTs using the effect of SHG by primary CGW propagation.
Evaluation of effective area of air piston gauge with limitations in piston–cylinder dimension measurements
Authors: Thakur Vikas N , Sharipov Felix , Yang Yuanchao , Kumar Sandeep , Ram Jokhan , Omprakash  , Kumar Harish , Sharma Rina , Yadav Sanjay , Kumar Ashok
Published: February 2021

The air piston gauge (APG) has been established at the National Physical Laboratory, India (NPLI) for Pascal realization since 2002. The APG at NPLI has been considered a transfer pressure standard because it has been calibrated against the primary pressure standard, i.e. ultrasonic interferometer manometer. As per existing international protocol, the APG establishment as a primary standard, the effective area (A
e) of piston–cylinder (p–c) assembly and masses must be directly traceable to SI units. We have calculated A
e and associated uncertainty of p–c assembly using the theory of rarefaction gas dynamics, which is based on dimension measurements. The value of A
e is obtained for varying temperatures and radii of piston and cylinder in their respective uncertainty limits. The variation of the cylinder's inner radius within its uncertainty limit of 0.7 µm includes the expected effective area, i.e. 3.356 775 (5) cm2. The effective area’s expected values are obtained for the cylinder’s radius of 10.338 00 (2) mm, which is approximately 0.65 µm away from the value obtained from dimensional measurements and well within the uncertainty limit. Therefore, to get the effective area of 3.356 775 (5) cm2, the uncertainty of the cylinder’s radius should be at least one order less (similar to piston’s radius) than that of the present value. The precision in dimension measurement of the cylinder's internal radius is the critical parameter for effective area calculation of p–c assembly.
Monthly analyses of convection-related irregular flights and their linear projections for the future climate in China
Authors: Zhou Yuntao , Gong Hongjing , Fan Penglei , Li Na , Gu Lei
Published: February 2021

Convective weather such as thunderstorms and rain is one of the main causes of irregular flights including delays, cancelations, turnbacks and diversions. In China, summer (April–September) flights accounted for 94% of irregular flights due to convective weather in 2016–2019. The impact of summer convective weather conditions on irregular flights is however not well understood. In this research, we find that thunderstorms, as indicated by the lifted index (LI), are greatly related to these irregular flights over Southeast China. The global climate model ensemble indicates there will be robust increases in the occurrence of convective weather environments in response to further global warming. We also find that as the LI is decreasing over time, the likelihood of thunderstorm-related irregular flights is increasing. Such an increase indicates there will be a 17% increase in irregular flights by the end of the century.
Tribological behavior of polymeric 3D-printed surfaces with deterministic patterns inspired in snake skin morphology
Authors: Ballesteros Luis Miguel , Zuluaga Efraín , Cuervo Paula , Rudas J Sebastián , Toro Alejandro
Published: February 2021

Surface engineering can rely on biological systems to mimic characteristics of living specimens in order to develop and fabricate deterministic elements to modify friction. In this work, the tribological response of bio-inspired patterns obtained by 3D-printing for polymer-metal contact in dry conditions are discussed. The repetitive array of elements called ‘fibrils’ in the ventral scale of Phython regius snake was used as an inspiration to fabricate the deterministic surfaces. The texturized samples were 3D-printed with Nylon filament and the counterpart was AISI 304 stainless steel. The results showed that the friction coefficient was consistently lower in the tests carried out with the texturized samples in comparison to those performed with stochastic surfaces. Lower friction values were clearly correlated to geometrical descriptors of the texture patters including the Feature Slenderness Ratio (FSR) and the Feature Aspect Ratio (FAR). The analysis of polymer’s worn surfaces revealed adhesive damage, localized melting and roll formation as the main wear mechanisms.
Characterization and synthesis of Fe3O4@C nanoparticles by in-situ solid-phase method
Authors: Xiang Hengli , Ren Genkuan , Zhong Yanjun , Yang Xiushan , Xu Dehua , Zhang Zhiye , Wang Xinlong
Published: February 2021

Fe3O4@C nanoparticles were successfully synthesized by an in situ solid-phase method using FeSO4, FeS2, and PVP K30 as the starting materials under the nitrogen atmosphere. In addition, the mechanism of the synthetic of Fe3O4@C nanoparticles was studied through in situ characterizations. The results showed that the pyrolysis of PVP K30 participated in the solid-phase reaction and resulted in the formation of carbon shells and a reduction in particle size. The structure of the Fe3O4@C nanoparticles was core–shell with the average particle size of ∼30 nm and the thickness of the carbon shell of ∼2 nm. Besides, the Raman spectrum revealed that the carbon shell mostly existed in the form of amorphous carbon. The surface area and the pore volume of the Fe3O4@C nanoparticles were estimated to be 37.74 m2 g−1 and 0.227 cm3 g−1. Magnetization hysteresis curve exhibited the values of coercivity and remanence and saturation magnetization are found to be approximately 0.16 kOe, 12.8 emu g−1, and 77 emu g−1, respectively.
Study on the geometric structure and stability of AlnMgn (n = 2–12) clusters using density functional theory
Authors: Zhang Xiao-Pan , Shi Lei , Du Hao , Tian Yuan , Lv Fei , Yang Ming-Liang , Qu Tao
Published: February 2021

In this study, density functional theory was used to investigate the AlnMgn (n = 2–12) clusters on a microscopic scale. The stable structure of clusters was determined and used as the interaction energies parameter in Wilson equation to deepen the activity prediction of the Wilson equation. The properties of Mg2 and Al2 dimers calculated by using ab initio molecular dynamics were compared with experimental data to verify the reliability of the method. By characterizing the cluster structure, the average binding energy, fragmentation energy, second–order energy difference, vertical ionization potential, vertical electron affinity, chemical hardness, HOMO–LUMO gaps, and distribution of the Al–Mg clusters were determined. With an increase in the cluster size, the symmetry of the Al–Mg clusters decreased, and Al atoms gradually gathered at the center of the cluster, whereas Mg atoms were distributed on the surface of the cluster, which tended to combine with Al atoms. Clusters with even numbers were generally more stable than the adjacent odd–numbered clusters. In particular, the thermodynamic stability of the Al4Mg4 cluster was prominent and was considered as an ideal object to calculate the interaction energies in the activity prediction of Al–Mg alloys.
Generation of 6-C synthetic seismograms in stratified vertically transversely isotropic media using a generalized reflection and transmission coefficient method
Authors: Tang Le , Fang Xinding
Published: February 2021

We develop a generalized reflection and transmission coefficient method (GRTM) for generating six-component (6-C) synthetic seismograms in horizontally layered vertically transversely isotropic (VTI) media. Compared with the traditional seismic modelling approaches that only consider translational motion, our method can simultaneously produce three-component translational and three-component rotational data excited by a point vector force or a moment tensor source in a layered half-space. Horizontally layered models are widely used in near surface applications as the properties of near surface formations generally show small lateral variations and change mainly along the depth direction. The use of the VTI constitutive relation can make our method applicable to more general situations because it takes into account the characteristics of sedimentary formations. We compare our method with a finite-difference method (FDM) for a variety of velocity models and acquisition geometries. The numerical results demonstrate that accurate 6-C synthetic seismograms can be calculated using our method. The computational efficiency of our method for 6-C seismic modelling is much higher than the finite-difference method, because it can reduce a 3-D modelling problem to 2.5-D by eliminating the azimuthal dimension. Also, our method does not require to perform additional spatial interpolations to obtain the rotational components. These advantages make our method suitable to serve as a forward modelling tool for rotational seismology.
Recent advances in histone glycation: emerging role in diabetes and cancer
Authors: Mir Abdul Rouf , Habib Safia , Uddin Moin
Published: February 2021

Ever increasing information on genome and proteome has offered fascinating details and new opportunities to understand the molecular biology. It is now known that histone proteins surrounding the DNA play a crucial role in the chromatin structure and function. Histones undergo a plethora of posttranslational enzymatic modifications that influence nucleosome dynamics and affect DNA activity. Earlier research offered insights into the enzymatic modifications of histones; however, attention has been diverted to histone modifications induced by by-products of metabolism without enzymatic engagement in the last decade. Nonenzymatic modifications of histones are believed to be crucial for epigenetic landscape, cellular fate and for role in human diseases. Glycation of histone proteins constitutes the major nonenzymatic modifications of nuclear proteins that have implications in diabetes and cancer. It has emerged that glycation damages nuclear proteins, modifies amino acids of histones at crucial locations, generates adducts affecting histone chromatin interaction, develops neo-epitopes inducing specific immune response and impacts cell function. Presence of circulating antibodies against glycated histone proteins in diabetes and cancer has shown immunological implications with diagnostic relevance. These crucial details make histone glycation an attractive focus for investigators. This review article, therefore, makes an attempt to exclusively summarize the recent research in histone glycation, its impact on structural integrity of chromatin and elaborates on its role in diabetes and cancer. The work offers insights for future scientists who investigate the link between metabolism, biomolecular structures, glycobiology, histone–DNA interactions in relation to diseases in humans.
Art Criticism in the Contracted Field
Authors: Bowman Matthew
Published: February 2021

Just over a decade-and-a-half ago, a roundtable discussion published in the pages of October worried that the periodic renewal of critical discourses had slowed to a standstill and that art criticism was faced with obsolescence. Such an obsolescence should be understood in a broadly Hegelian manner: the danger is not that art criticism would disappear from the cultural field, but that it will continue—although drained of its previous necessity. Such fears perhaps run the risk of exaggeration, yet this article shall suggest that there seems a sense in which the field of art criticism has contracted in recent years. Self-reflexivity in art and the popularization of “para-curatorial” approaches, for instance, often underpin the artwork discursively before the arrival of art criticism upon the scene. To be sure, such circumstances are viewable positively as interdisciplinary dialogical opportunities, but the negative flipside here is that art criticism’s potential contribution becomes increasingly minimized. From another angle, critics such as Isabelle Graw have contended that the economic-cultural regime of post-Fordism, with its attention on intellectual labor and knowledge production, might actually hold possibilities for the contemporary art critic—but even here, I argue, art criticism becomes contracted, albeit in the other meaning of the word.