bluuebunny/crossref_metadata_2025 huggingface dataset:
Morningness–eveningness assessment from mobile phone communication analysis
Authors: Roy Chandreyee , Monsivais Daniel , Bhattacharya Kunal , Dunbar Robin I. M. , Kaski Kimmo
Published: July 2021

Human behaviour follows a 24-h rhythm and is known to be governed by the individual chronotypes. Due to the widespread use of technology in our daily lives, it is possible to record the activities of individuals through their different digital traces. In the present study we utilise a large mobile phone communication dataset containing time stamps of calls and text messages to study the circadian rhythms of anonymous users in a European country. After removing the effect of the synchronization of East-West sun progression with the calling activity, we used two closely related approaches to heuristically compute the chronotypes of the individuals in the dataset, to identify them as morning persons or “larks” and evening persons or “owls”. Using the computed chronotypes we showed how the chronotype is largely dependent on age with younger cohorts being more likely to be owls than older cohorts. Moreover, our analysis showed how on average females have distinctly different chronotypes from males. Younger females are more larkish than males while older females are more owlish. Finally, we also studied the period of low calling activity for each of the users which is considered as a marker of their sleep period during the night. We found that while “extreme larks” tend to sleep more than “extreme owls” on the weekends, we do not observe much variation between them on weekdays. In addition, we have observed that women tend to sleep even less than males on weekdays while there is not much difference between them on the weekends.
Pivot burrowing of scarab beetle (Trypoxylus dichotomus) larva
Authors: Adachi Haruhiko , Ozawa Makoto , Yagi Satoshi , Seita Makoto , Kondo Shigeru
Published: July 2021

Many organisms live in the soil but only a little is known about their ecology especially movement style. Scarab beetle larvae do not have appendages to shovel soil and their trunk is thick compared to their body length. Hence, their movement through the soil is perplexing. Here, we established the observation and analysis system of larval movement and found that the last larval instars of Trypoxylus dichotomus burrow in two different ways, depending on the hardness of the soil. If the soil is soft, the larvae keep their body in a straight line and use longitudinal expansion and contraction; if the soil is hard, they flex and rotate their body. It is thought that the larvae adapt to diverse soil conditions using two different excavation methods. These results are important for understanding the soil ecology and pose a challenge to engineer of newer excavation technology.
Memory for spatio-temporal contextual details during the retrieval of naturalistic episodes
Authors: Foudil Samy-Adrien , Pleche Claire , Macaluso Emiliano
Published: July 2021

Episodic memory entails the storage of events together with their spatio-temporal context and retrieval comprises the subjective experience of a link between the person who remembers and the episode itself. We used an encoding procedure with mobile-phones to generate experimentally-controlled episodes in the real world: object-images were sent to the participants' phone, with encoding durations up to 3 weeks. In other groups of participants, the same objects were encoded during the exploration of a virtual town (45 min) or using a standard laboratory paradigm, with pairs of object/place-images presented in a sequence of unrelated trials (15 min). At retrieval, we tested subjective memory for the objects (remember/familiar) and memory for the context (place and time). We found that accurate and confident context-memory increased the likelihood of “remember” responses, in all encoding contexts. We also tested the participants' ability to judge the temporal-order of the encoded episodes. Using a model of temporal similarity, we demonstrate scale-invariant properties of order-retrieval, but also highlight the contribution of non-chronological factors. We conclude that the mechanisms governing episodic memory retrieval can operate across a wide range of spatio-temporal contexts and that the multi-dimensional nature of the episodic traces contributes to the subjective experience of retrieval.
Null-model-based network comparison reveals core associations
Authors: Röttjers Lisa , Vandeputte Doris , Raes Jeroen , Faust Karoline
Published: July 2021

Microbial network construction and analysis is an important tool in microbial ecology. Such networks are often constructed from statistically inferred associations and may not represent ecological interactions. Hence, microbial association networks are error prone and do not necessarily reflect true community structure. We have developed anuran, a toolbox for investigation of noisy networks with null models. Such models allow researchers to generate data under the null hypothesis that all associations are random, supporting identification of nonrandom patterns in groups of association networks. This toolbox compares multiple networks to identify conserved subsets (core association networks, CANs) and other network properties that are shared across all networks. We apply anuran to a time series of fecal samples from 20 women to demonstrate the existence of CANs in a subset of the sampled individuals. Moreover, we use data from the Global Sponge Project to demonstrate that orders of sponges have a larger CAN than expected at random. In conclusion, this toolbox is a resource for investigators wanting to compare microbial networks across conditions, time series, gradients, or hosts.
Distinctive modulation of optical anisotropy by halogens in α/β-Cd–P–X (X = Cl, Br, and I)
Authors: Zhang Kewang , Huang Junben , Chen Zhikang , Zhang Bei , Lee Ming-Hsien , Zhang Jun
Published: July 2021

Halogens modulating the polarizability anisotropy of the polyhedra caused a large birefringence changes (about 8 times) in α/β-Cd2P3X (X = Cl to I) by the synergistic effect of anion size and covalent interactions between halogens and metal cations.
Understanding the reactivity of geminal P/B and P/Al frustrated Lewis pairs in CO2 addition and H2 activation
Authors: Ramadhan Muhammad Dzulfahmi , Surawatanawong Panida
Published: July 2021

Despite having the stronger orbital interaction, the geminal P/B compound is less reactive than the geminal P/Al compound due to unfavorable core repulsion contribution and distortion contribution. The reactivity toward H2 is less than toward CO2.
Co0.85Se particles encapsulated in the inner wall of nitrogen-doped carbon matrix nanotubes with rational interfacial bonds for high-performance lithium-ion batteries
Authors: Chen Qi , Liang Qichen , He Shu-Ang , Cui Zhe , Liu Qian , Zhu Jinqi , Zou Rujia
Published: July 2021

The Co0.85Se@NCMT anode with both Co–N/C and Se–C bonds is prepared for LIBs via a safe and efficient self-generated sacrificial template method, exhibiting a high capacity, good rate performance and excellent cycling stability.
A dynamic tetranuclear gold(i)-cyclophane – gold(i)-centred chirality and fluxionality arising from an intramolecular shift of Au–S bonds
Authors: Ang Pau Lin , Nguyen Van Ha , Yip John H. K.
Published: July 2021

A dynamic tetranuclear gold(i)-cyclophane which shows gold(i)-centred chirality and fluxionality arising from ligand exchange.
Reaction intermediate-mediated electrocatalyst synthesis favors specified facet and defect exposure for efficient nitrate–ammonia conversion
Authors: Hu Qi , Qin Yongjie , Wang Xiaodeng , Wang Ziyu , Huang Xiaowan , Zheng Hongju , Gao Keru , Yang Hengpan , Zhang Peixin , Shao Minhua , He Chuanxin
Published: July 2021

An intermediate-mediated approach was proposed to synthesize copper, rich in (100) facets and defects, for highly efficient nitrate reduction.
Common principles of surface deformation in biology
Authors: Roux Aurélien
Published: July 2021

Living organisms are separated from their environment by an interface/surface. Herein I discuss principles by which living surfaces deform.
Synthesis of enantiopure α-Tfm-proline and α-Tfm-pipecolic acid from oxazolo-pyrrolidines and -piperidines
Authors: Sanchez Clément A. , Gadais Charlène , Diarra Sitan , Bordessa Andrea , Lensen Nathalie , Chelain Evelyne , Brigaud Thierry
Published: July 2021

Scalable synthesis of enantiopure (R) and (S)-α-Tfm-proline and α-Tfm-pipecolic acid.
Analysis of biochemistry students’ graphical reasoning using misconceptions constructivism and fine-grained constructivism: why assumptions about the nature and structure of knowledge matter for research and teaching
Authors: Rodriguez Jon-Marc G. , Towns Marcy H.
Published: July 2021

In this work, we discuss the importance of underlying theoretical assumptions in research, focusing on the conclusions reached when analyzing data from a misconceptions constructivist (stable, unitary) perspective in contrast to a fine-grained constructivist (resources, knowledge-in-pieces) perspective.
Deformation of membrane vesicles due to chiral surface proteins
Authors: Behera Arabinda , Kumar Gaurav , Akram Sk Ashif , Sain Anirban
Published: July 2021

Chiral rod like molecules induce membrane vesicles to generate cones and tubes.
The Assessment of Early Pragmatic Development: A Study of the Reliability and Validity of the Language Use Inventory-Italian
Authors: Longobardi Emiddia , Lonigro Antonia , Laghi Fiorenzo , O'Neill Daniela K.
Published: July 2021

Purpose

Pragmatics is receiving much attention in both the fields of developmental and clinical psychology; however, there is a dearth of instruments to assess pragmatic abilities specifically among young toddler-age children. The aim of the current study was to test the psychometric properties of the Italian version of the Language Use Inventory (LUI), named the LUI-Italian, a parent report measure assessing pragmatic language development in children 18–47 months of age.

Method

Parents of Italian-speaking children who ranged in age between 18 and 47 months completed the LUI-Italian at T1 (
N
= 389) and 1 week later (
N
= 53). At T1, children were also administered the First Language Test (Test del Primo Linguaggio [TPL]), a direct measure of pragmatics, vocabulary, and syntax.

Results

Cronbach's alpha values were at or above acceptable levels. Factor analysis and test–retest confirmed the strong structure and reliability of the LUI-Italian. Some evidence for concurrent validity was found, as shown by associations between the LUI-Italian and the TPL.

Conclusions

The LUI-Italian demonstrated good psychometric properties relating to reliability, thus providing a sound basis for proceeding to a standardization study, and supporting cross-cultural comparison of pragmatic development and further exploration of profiles of pragmatic competence for children displaying language impairments or delay. Future studies need to further test concurrent, divergent, and predictive validity of the LUI-Italian.
Multiwavelength analysis and modeling of OJ 287 during 2017–2020
Authors: Prince Raj , Agarwal Aditi , Gupta Nayantara , Majumdar Pratik , Czerny Bożena , Cellone Sergio A. , Andruchow I.
Published: July 2021

Context. The blazar OJ 287 has been proposed as binary black hole system based on its periodic optical outburst. Black hole binary systems are scarce among blazars with parsec scale jets, and hence this source is exciting to study

Aims. The BL Lac OJ 287 is an interesting object for multiwavelength study due to its periodic outbursts. We analysed the optical, X-ray and γ-ray data of OJ 287 for the period of 2017–2020. There are several high states in optical–UV and X-ray frequencies during this period. Based on the observed variability in optical and X-ray frequencies, the entire period 2017–2020 is divided in five segments, in this paper referred as A, B, C, D, and E. A detailed temporal and spectral analysis is performed to understand the nature of the flaring activities of OJ 287.

Methods. To understand the temporal variability in this source we studied the intraday and fractional variability for all the various states. In additon, fast variability time was also estimated in order to understand the nature of variability. Furthermore, the multiwavelength spectral energy distribution (SED) modeling was performed to know more about the physical processes responsible for the simultaneous broadband emission and the fast variability.

Results. The Fermi-LAT observations show a moderate flux level of this source in γ-ray frequency throughout this period, though flux variability has been observed. The source has shown a strong flux variability in X-ray, optical, and UV during early 2017 and mid 2020 when the source was in very high state. A single-zone synchrotron self-Compton emission model is considered to model the SED, and this helps us to explore the nature of this BL Lac with binary supermassive black holes.
The parallax zero-point offset from Gaia EDR3 data
Authors: Groenewegen M. A. T.
Published: July 2021

The second data release of Gaia revealed a parallax zero-point offset of −0.029 mas based on quasars. The value depended on the position on the sky, and also likely on magnitude and colour. The offset and its dependence on other parameters inhibited improvement in the local distance scale using for example the Cepheid and RR Lyrae period–luminosity relations. Analysis of the recent Gaia Early Data Release 3 (EDR3) reveals a mean parallax zero-point offset of −0.021 mas based on quasars. The Gaia team addresses the parallax zero-point offset in detail and proposes a recipe to correct for it based on ecliptic latitude, G-band magnitude, and colour information. This paper presents a completely independent investigation into this issue focusing on the spatial dependence of the correction based on quasars and the magnitude dependence based on wide binaries. The spatial and magnitude corrections are connected to each other in the overlap region in the range 17 < G < 19. The spatial correction is presented at several spatial resolutions based on the HEALPix formalism. The colour dependence of the parallax offset is unclear and in any case secondary to the spatial and magnitude dependence. The spatial and magnitude corrections are applied to two samples of brighter sources, namely a sample of approximately 100 stars with independent trigonometric parallax measurements from Hubble Space Telescope data, and a sample of 75 classical cepheids using photometric parallaxes. The mean offset between the observed GEDR3 parallax and the independent trigonometric parallax (excluding outliers) is about −39 μas, and after applying the correction it is consistent with being zero. For the classical cepheid sample the analysis presented here suggests that the photometric parallaxes may be underestimated by about 5%.
Solar Orbiter Radio and Plasma Waves – Time Domain Sampler: In-flight performance and first results
Authors: Soucek J. , Píša D. , Kolmasova I. , Uhlir L. , Lan R. , Santolík O. , Krupar V. , Kruparova O. , Baše J. , Maksimovic M. , Bale S. D. , Chust T. , Khotyaintsev Yu. V. , Krasnoselskikh V. , Kretzschmar M. , Lorfèvre E. , Plettemeier D. , Steller M. , Štverák Š. , Vaivads A. , Vecchio A. , Bérard D. , Bonnin X.
Published: July 2021

Context.The Radio and Plasma Waves (RPW) instrument on board Solar Orbiter has been operating nearly continuously since the launch in February 2020. The Time Domain Sampler (TDS) receiver of the RPW instrument is dedicated to waveform measurements of plasma waves and dust impact signatures in an intermediate frequency range from 0.2 to 200 kHz.

Aims.This article presents the first data from the RPW-TDS receiver and discusses the in-flight performance of the instrument and, in particular, the on-board wave and dust detection algorithm. We present the TDS data products and its scientific operation. We demonstrate the content of the dataset on several examples. In particular, we study the distribution of solar Langmuir waves in the first year of observations and one Type III burst event.

Methods.The on-board detection algorithm is described in detail in this article and classifies the observed waveform snapshots, identifying plasma waves and dust impacts based on the ratio of their maximum amplitude to their median and on the spectral bandwidth. The algorithm allows TDS to downlink the most scientifically relevant waveforms and to perform an on-board statistical characterization of the processed data.

Results.The detection algorithm of TDS is shown to perform very well in its detection of plasma waves and dust impacts with a high accuracy. The initial analysis of statistical data returned by TDS shows that sporadic Langmuir waves that are not associated with Type III events are routinely observed in the inner heliosphere, with a clear increase in occurrence rate closer to the Sun. We also present an example of RPW observations during an encounter of the source region of a Type III burst, which exploits the on-board calculated histograms data.
Glass transition in charge-density-wave systems o-TaS3
and K0.3MoO3
Authors: Staresinic D. , Biljakovic K. , Brutting W. , Hosseini K. , Monceau P.
Published: July 2021

We present experimental evidence for the glass transition in charge density wave (CDW) superstructure
of two quasi one-dimensional systems, o-TaS3 and K0.3MoO3. Low frequency dielectric response of both systems
exhibits typical glass-like phenomenology, featuring the splitting of the relaxational spectrum into two processes on
decreasing the temperature and the subsequent freezing of primary or a process at finite temperature of glass
transition Tg. Below Tg secondary, or β process becomes dominant. Activation energies obtained from the
temperature evolution of the characteristic relaxation times of a and β processes correspond to the activation
energies of the temperature evolution of the DC conductivity above and below Tg respectively. The results are
discussed in respect to the relevant theories of low frequency CDW dynamics, with the emphasis on the Coulomb
hardening of CDW in absence of screening by free carriers. An attempt to understand observed differences in
freezing of CDW in o-TaS3 and K0.3MoO3 is made.
Fractional-power law susceptibility and specific heat of o-TaSs
Authors: Biljakovic K. , Miljak M. , Staresinic D. , Lasjaunias J. C. , Souletie J. , Monceau P.
Published: July 2021

We report on the power-law dependence on temperature of the magnetic susceptibility and the specific
heat of the CDW (charge density wave) system o-TaS3. All the evidences are in favor of a typical REHAC (random
exchange Heisenberg antiferromagnetic chain) behaviour [I], however in the diluted limit of spins s=1/2. We
propose a consistent microscopic explanation of the corresponding elementary excitations within a new state
formed below the glass transition demonstrated recently in this system [2].
Theory of pseudogaps in charge density waves in application
to photo electron
spectroscopy
Authors: Matveenko S. I. , Brazovskii S.
Published: July 2021

For a one-dimensional electron-phonon system we consider the photon absorption
involving electronic excitations within the pseudogap energy range. Within the adiabatic approximation
for the electron - phonon interactions these processes are described by ronlinear configurations of
an instanton type. We calculate the subgap absorption as it can be observed by means of photo
electron or tunneling spectroscopies. In details we consider systems with gapless modes: 1D
semiconductors with acoustic phonons and incommensurate charge density waves. We found that
below the free particle edge the pseudogap starts with the exponential decrease of transition rates
changing to a power law deeply within the pseudogap, near the absolute edge.
Charge density wave, superconductivity, and non-metallic
behaviour under high pressure in ZrTe3
Authors: Igarashi K. , Yasuzuka S. , Inagaki K. , Tanda S. , Okajima Y. , Hedo M. , Uwatoko Y. , Yamaya K.
Published: July 2021

The charge-density-wave (CDW) order of low-dimensional inorganic conductor ZrTe3 is found to increase
with increasing pressure, while the superconductivity with filamentary nature is significantly suppressed. It was
evidenced in resistivity measurements under pressure up to 0.8 Cpa. The present results suggest that competition
between the superconductivity and the CDW is not simply explained by a nesting effect of the Fermi surface, but
other origin is needed. Non-metallic behaviour is also found below 4 K under high pressures above 0.6 Gpa. The
relationship between the non-metallic state and the pressure-enhanced CDW is expected, although yet inexplicable.
Quantum phase slips and thermal fluctuations in one-dimensional
disordered density waves
Authors: Glatz A. , Nattermann T.
Published: July 2021

The low temperature phase diagram of 1D disordered quantum systems like charge
or spin density waves, superfluids, and related systems is considered by a full finite
T renormalization group approach for the first time. At zero temperature the consideration of quantum
phase slips leads to a new scenario for the unpinning (delocalization) transition. In the strong
pinning limit the model is solved exactly. At finite T a rich crossover diagram with various
scaling regions is found which reflects the zero temperature quantum critical behavior.
Mode-locking and dynamic melting of vortex matter driven
through mesoscopic channels
Authors: Besseling R. , Kokubo N. , Kes P. H.
Published: July 2021

We investigated the dynamics of vortex matter confined to mesoscopic channels by means of mode
locking experiments. When vortices move coherently through the pinning (shear) potential provided by static
vortices in the channel edges, interference between the washboard frequency of the lattice and the frequency of
superimposed rf-currents causes (Shapiro-like) steps in the dc-IV curves. These steps allow to trace directly how the
number of moving rows in each channel and the frustration between row spacing and channel width, varies with
magnetic field. The flow stress (~ I,) surprisingly exhibits maxima for mismatching (defective) structures, originating
from traftic-jam-like flow due to disorder in the edges. We then focus on the behavior for higher fields, approaching
the 2D melting field Bm. In this regime the presence of the interference phenomenon, characteristic for crystalline
motion, strongly depends on the velocity (applied frequency) at which vortices are probed. The minimum velocity to
observe coherent, solid-like motion is found to diverge when the field is increased towards $E_{''}$ above which the
interference is absent for any frequency. This provides the first direct evidence for a velocity dependent, dynamic
phase transition of vortex matter moving through disorder, as predicted by Koshelev and Vinokur.
Hydrodynamic theory of plastic flows with conversion
Authors: Kirova N. , Brazovskii S.
Published: July 2021

Experimental studies show that the sliding state is essentially inhomogeneous with different
effects near contacts, in the bulk or at obstacles. We present a general scheme to approach the
space - time evolution of deformations, electric fields and currents with particular emphasize t o the
current conversion process in Charge Density Waves. We derive general equations for the multifluid
hydrodynamics of plastic flows which allow, in principle, to study the transformation of injected
carriers from normal electrons to new periods, collective motion in constrained geometry as well as
the plastic contribution to non-linear current-voltage characteristics.
Modalities of self-organized charge response in low dimensional
systems
Authors: Tomic S. , Vuletic T. , Pinteric M. , Korin-Hamzic B.
Published: July 2021

We present modalities of self-organized charge response in low dimensional systems, like diverse organic
and quantum spin systems, studied by the low-frequency (10 mHz – 1 MHz) dielectric spectroscopy. Density wave
structures with the order of commensurability N = 4 can be recognized as phasons in a random impurity potential,
whereas those with N = 3 can be viewed as topological defects like charge domain wall pairs in the background
domain structure.
The charge ordered state and the possible 2kF-CDW state
with Fermi surface nesting in organic conductor
θ-(BEDT-TTF)2MM'(SCN)4 (MM' = RbZn, CsCo)
Authors: Watanabe M. , Noda Y. , Nogami Y. , Oshima K. , Mori H.
Published: July 2021

Two-dimensional organic conhctor θ-(BEDT-TTF)2RbZn(SCN)4 and
θ-(BEDT-TT)2CsCo(SCN)4 were investigated by X-ray diffraction measurements. Both salts exhibit an isostructural
crystal structure at room temperature (RT). However, the RbZn salt unkrgoes a metal-insulator transition
associated with superlattice formation of $2c$. The charge ordered state below TMI, was observed by aystal
structure analysis taking into account of the superlattice. This mohlation of $2c$ has no relation to the
topology of the calculated Fermi surface nesting vector at all. Below TMI, the systematic & formations of
BEDT-TTF molecular shape indicatedcharge disproportionation between BEDT-TTFs possibly caused by the
electron correlation effect. On the other hand, in the CsCo salt, another incommensurate lattice modulation was
found under high pressure of 1 GPa This incommensurate mohlation vector of (2/3 0 0.29) is in agreement
with the nesting vector of Fermi surface under high pressure. In this system, it seems that small change caused
by chemical substitution can vary the electronic state from the charge ordered state to the CDW state.
Stripe fractionalization I: The generation of king local symmetry
Authors: Nussinov Z. , Zaanen J.
Published: July 2021

This is part one in a series of two papers dedicated to the notion that the destruction of
the topological order associated with stripe phases is about the simplest theory controlled by local
symmetry: Ising gauge theory. This first part is intended to he a tutorial- we will exploit the simple
physics of the stripes to vividly display the mathematical beauty of the gauge theory. Stripes, as they
occur in the cuprates, are clearly `topological' in the sense that the lines of charges are at the same
time domain walls in the antiferromagnet. Imagine that the stripes quantum melt so that all what
seems to be around is a singlet superconductor. What if this domain wall-ness is still around in a
delocalized form? This turns out to be exactly the kind of `matter' which is described by the Ising
gauge theory. The highlight of the theory is the confinement phenomenon, meaning that when the
domain wall-ness gives up it will do so in a mcat-and-potato phase transition. We suggest that this
transition might be the one responsible for the quantum criticality in the cuprates. In part two [1] we
will become more practical, arguing that another phase is possible according to the theory. It might be
that this quantum spin-nematic has already been observed in strongly underdoped $La_{2-x}Sr_xCuO_4$.
Charge and orbital ordering in transition metal oxides
Authors: Khomskii D.
Published: July 2021

Transition metal oxides with strongly correlated d-electrons show an astonishing variety of
properties. This is largely determined by an interplay of different degrees of freedom: charge,
spin, orbital, lattice ones. Often there appear in them various superstructures. In this talk I will
consider different types of superstructures in transition metal oxides, especially charge and
orbital ordering, willdiscuss the main mechanisms leading to their formation and consider
specific examples of superstructures in manganites, cobaltites and in some frustrated systems.
Relative role of purely electronic mechanisms and of the electron-phonon interaction will be
discussed. In particular, I will show that the elastic interactions can naturally lead to different
superstructures, including stripes. Special features of charge and, especially, orbital ordering
in frustrated systems, where frustrations may be caused both by the geometric structure of the
lattice and by the special features of orbital interactions, will be considered, and it will be
shown that the order-from-disorder mechanism can lead to a unique ordered ground state in
many of these cases..
Deformation of sliding charge density wave in Rb0.3MoO3
Authors: Le Bolloc'h D. , Ravy S. , Senzier P. , Pasquier C. , Detlefs C.
Published: July 2021

The correlation length of the charge density wave ordering in Rb0.3, MoO, has been studied by x-ray
diffraction under electric field applied along the one-dimensional axis. The (10, 0.25, -5.5) satellite reflection has
been measured in 3D, using high Q-resolution available at the ESRF. Under electrical field, the satellite reaches two
stable positions depending on the temperature. It can switch from one to another as a function of the temperature and
the current with very long relaxation times ($\rm 10^{th}$ of minutes). After several cycling with T and E, the satellite
reflection is found to shift in the 3 main directions. The width of the satellite is reduced by a factor of two in the
k-direction and an increase of the transverse correlation length is observed in the two others: the ordered domains look
elongated, reaching until 5000 Å in the direction of the applied field and around 1OOO Å, in the perpendicular
directions.
Stiff liquid and solid of electrons in two dimensions
Authors: Pudalov V. M.
Published: July 2021

Electrons in two-dimensional (2D) layers at semiconductor interfaces may be driven to a solid
phase by reducing their density. Understandmg of this electron liquid-solid transition at mK-temperatures
and the origin of the 2D electron solid phase remain challenging. The experimental system under study is
subject to strong interactions and disorder. Charge transport in the electron solid phase demonstrates
many features anticipated for the pinned crystal, though no direct imaging of a spatial charge- or
magnetic-ordering is available by now. Rich information has been recently obtained for dilute electron
liquid phase on strong renormalization of the Pauli spin susceptibility, magnetization, and the effective
mass. These data provide a set of the Fermi-liquid coupling parameters for densities down to and at the
transition. The steep density dependence of the susceptibility is intriguing because it might indicate a
developing magnetic transition, though it is more likely reflects a tendency to crystallization.
Instability and reconstruction of a thin charged helium films
Authors: Shikin V. B.
Published: July 2021

Reconstruction of thin charged liquid films is discussed within of the multielectron dimple formation
scenario. It is shown, that two multielectron dimples on bulk helium can form metastabile bound statc with the
equilibrium dimple-dimple distance around capillary length. Such a property is a suitable indicator for the possibility
of periodical bulk chat-ged liquid surface reconstruction. In the case of thin helium films dimple-dimple bound state
don't exists. And therefore the periodical reconstruction becomes impossible.
Peculiar vortex structures in Fulde-Ferrell-Larkin-Ovchinnikov
phase
Authors: Buzdin A. , Houzet M.
Published: July 2021

A long time ago, it was predicted by Larkin and Ovchinnikov and Fulde and Ferrell that the non-uniform
superconducting state (FFLO state) must appear in the magnetic field acting on the electron spins. Up to now, there
have been no unambiguous experimental proofs in the favour of this state observation. We discuss the unusual
properties of such a state, which can permit its identification. It is demonstrated that in 2D (or quasi 2D)
superconductors the FFLO state leads to an appearance of a very special oscillatory - like dependence of the upper
critical field versus the angle with the respect to the layers. The new solutions, corresponding to the higher Landau
level functions are realized, and the vortex lattice structures are quite exotic. Corresponding vortex states reveal the
zeros of superconducting order parameter with high winding numbers. The predicted quasi-oscillatory angular and
temperature dependence of Bc2, as well as a cascade of first order transitions must permit the unambiguous
identification of mysterious FFLO state. Very recently the magnetic-field-induced superconductivity has been
observed in the quasi two-dimensional (2d) organic conductor (BETS)2FeCI4 which is an excellent candidate for the
observation of the discussed effects.
Fulde-Ferrell-Larkin-Ovchinnikov state in D-wave superconductors
Authors: Maki M. , Won H.
Published: July 2021

Recently a few works have been reported on Fulde-Ferrell-Larkin-Ovchinnikov (FFLO)state
in d-wave superconductors in layered compounds. In strong contrast to 3D s-wave
superconductors where the stripe like state appears, the square lattice like state
is formed in d-wave superconductors in quasi-2D system and in a magnetic field within the conducting
plane. Indeed there have been reported that FFLO state in beta-(ET) salts and
lambda-(BEDT)_ 2GaC1_ 4,though they are not conclusive. We review our recent works on this
subject. We propose NMR, STM or transport measurement will provide a definitive test for
FFLO state.
Simulation of thermal processes: Solutions studied
in the automotive industry
Authors: Plateau M.
Published: July 2021

The aim of simulation for industry is reducing the cost of prototyping. Manufacturing of automotive parts uses thermal processes: heat treatment, welding, forging and casting. In some few applications, we succeed in having good results. But, nowadays, we cannot say we earn a lot of money thanks to simulation because the available tools are not completely adapted to our problematic and we have a large lack of data. That is the reason we work with other industries, schools and software producers.
The rate of solidification and the effects of local composition on the subsequent nucleation of Al2Cu2Mn3 dispersoid phase in Al-4Cu-0.3Fe-0.4Mn-0.2Si alloys
Authors: Zoeller T. L. , Sanders T. H.
Published: July 2021

Following solidification, an aluminum alloy microstructure is highly segregated. The microstructure consists of cored dendrites with various soluble and insoluble phases present in the inter-dendritic regions. The solidification rate has a marked effect on the amount of coring as well as grain dimensions and second phase particle size and spacing. Post-solidification cooling rates as well as subsequent heat treatments also affect the evolution of the microstructure. Understanding the effects of these thermal treatments is important in explaining differences in microstructures that are observed in alloys of identical compositions. The focus of this study is to determine the interaction between the coring of copper across dendrites during solidification and the precipitation of dispersoids during the homogenization treatments of an alloy. An aluminum alloy whose composition is in the range of Al-4Cu-0.3Fe-0.4Mn-0.2Si is ideally suited for this study for several reasons. First it is similar to a host of commercial aluminum copper alloys, and the presence of Mn, Fe, and Si affect the distribution of particles that control grain morphology in these alloys. Preliminary experimental results are discussed. Current numerical analysis techniques will be examined and possible methods to treat the problem will be presented.
Modelling of phase transformations and hardening of carbonitrided steels
Authors: Przyłęcka M. , Gęstwa W. , Totten G. E.
Published: July 2021

There are a variety of opinions regarding the influence of retained austenite and carbides on the properties exhibited by carbonitrided steels. In this paper, the development of a model marking relationship between phase composition, and properties of hardened carbonitrided steel has been presented. A summary of the impact of structure on properties is provided in Table 1. In the study reported here, the impact of thermal processing conditions on retained austenite and carbides was examined for carbonitrided and hardened 20 (C22), 20H (20Cr4), 15HN (17CrNi6-6) and 16HG (16MnCr5) steels. The models that are reported were experimentally validated. In particular, the results obtained for structure with respect to hardness and abrasive wear resistance were discussed for carbonitrided and hardened 20H (20Cr4) steel.
Numerical simulation of welding stresses and distortions under consideration of temporal and local changes of strain rate
Authors: Ossenbrink R. , Wohlfahrt H. , Michailov V.
Published: July 2021

As a result of high temperature changing rates in the heat affected zone (HAZ) the elevated strain rates during welding may have a high influence of the yield stresses. Higher yield stresses as a result of high strain rates can be observed in hot tensile tests for several materials.
A model has been developed and integrated in a multi-purpose FEA-program (ANSYS®) to investigate strain rate effects in numerical welding simulation. The routine calculates the current yield stress as a function of the local strain rates. The influence of the resulting stresses and distortions has been analyzed in comparative numerical welding simulations.
Thermal stresses in hexagonal materials –heat treatment influence on their mechanical behaviour
Authors: Gloaguen D. , Freour S. , François M. , Guillen R. , Royer J.
Published: July 2021

Internal stresses due to anisotropic thermal and plastic properties were investigated in rolled zirconium and titanium. The thermal stresses induced by a cooling process were predicted using a self-consistent model and compared with experimental results obtained by X-ray diffraction. The study of the elastoplastic response during uniaxial loading was performed along the rolling and the transverse direction of the sheet, considering the influence of the texture and the thermal stresses on the mechanical behaviour. An approach in order to determine the thermal behaviour of phases embedded in two-phase materials is also presented.
Modelling of changes in physical and mechanical properties of structural materials during long-term exposures at elevated temperatures
Authors: Kohout J.
Published: July 2021

Long-term exposures of various industrial structural materials at sufficiently elevated temperatures cause substantial changes in materials structures and, consequently, substantial changes in their physical and materials properties. The paper is focused to the influence of thermodegradation of glass-fibre-reinforced polyamide 66 in dry air and gear oil on its mechanical properties. As the thermodegradation of polymer materials is diffusion controlled process, the paper starts with the description of water diffusion in tested material. Then a very simple degradation mechanism is proposed for modelling the main features of real degradation processes. Regression functions describing the changes in mechanical properties of polyamide details during exposure are verified by the fit of experimental results. In the end of the paper some general considerations about the changes in other structural materials during exposures are done and supported by some experimental results.
Crack spacing in strained films
Authors: Guzina B. B. , Timm D. H. , Voller V. R.
Published: July 2021

Consider a thin film resting on a relatively thick substrate. When the substrate is subjected to an axial strain transverse cracks, normal to the direction, of the applied strain may appear in the film. It is observed that, for a given strain, the spacing between such cracks is uniform, with a clearly identifiable characteristic length scale that can be used to provide bounds on the spacing. Further, as the strain is increased, there is a densification of the cracks up to a saturation limit. Beyond the saturation limit additional strain produces no further cracks and the characteristic crack length scale for the given system remains fixed. This paper presents analytical models that can be used to predict the characteristic length scale both at the saturation limit and during the densification process. The models are shown to be applicable across a wide range of length scales; with abilities to determine the crack space length scale in both asphalt pavements (~100m) subjected to a thermal loading and strained ceramic films (~100μm).
The computer simulation of the boost diffusion oxidation process for the deep-case hardening of titanium alloys
Authors: Luo J. , Zhang Z. , Dong H. , Bell T.
Published: July 2021

A one dimensional finite difference diffusion model for simulating the Boost Diffusion Oxidation (BDO) process of titanium alloys is developed and implemented as a window-based program. The program can simulate the BDO process for both constant diffusion coefficient and concentration dependent diffusion coefficient. It is found that to accurately simulate the BDO process, the concentration dependence of oxygen diffusion has to be taken into account. If the concentration dependence is taken as the Shamblen and Redden’s equation, the simulation results agree well with the experimental results.
Simulating welding with shell elements
Authors: Faure F. , Bergheau J.-M. , Leblond J.-B.
Published: July 2021

Finite element simulations can be used to evaluate residual stresses and distortions induced by welding. Such simulations must account for complex interactions between thermal, metallurgical and mechanical phenomena. “Local” simulations are often sufficient for satisfactory predictions of residual stresses in the heat-affected zone (HAZ), but 3D “global” simulations are often necessary to calculate distortions, which can be important even far from the HAZ. In order to avoid such heavy calculations, a special shell element is proposed for the simulation of welding of thin structures. The thermal calculation involves only one nodal degree of freedom but fully accounts for boundary conditions on the faces of the shell. The metallurgical and mechanical calculations are based on a “multi-layer” approach. Due account is taken of transformation plasticity in the mechanical calculation. Numerical results obtained with this approach are compared to those of experiments and some 3D simulation.
A model of the interface between plasma jet simulation and the simulation of coating formation during atmospheric plasma spraying (APS)
Authors: Lugscheider E. , Nickel R. , Papenfuß-Janzen N.
Published: July 2021

The atmospheric plasma spraying (APS) process can be divided into sub-processes, which are simulated by different numerical methods. The balance equations of momentum, mass and energy of the plasma jet are solved numerically by applying the finite volume method (FVM) using a CFD (Computational Fluid Dynamics) software tool. On the other hand the solution of the thermo-mechanical problem of the coating formation on the substrate is estimated using the finite element method (FEM). The movement of the plasma jet above the surface of the substrate during the spraying process causes a time dependent boundary condition for the FEM-analysis. The heat transfer from the plasma jet to the substrate has to be taken into account. There is also a mass and heat transfer of heated particles to the substrate surface, which is responsible for the formation of the coating. Not only the plasma jet influences the boundary conditions of the coating formation, but the substrate is also a boundary for the plasma jet. This has to be considered during the plasma jet simulation, as well. This article describes the physical and mathematical background of the plasma jet/substrate heat transfer interface model, the implementation in the overall simulation process and its use in the simulation of the formation of a thermal barrier coating (TBC) made of partially yttria stabilized zirconia on a turbine blade during atmospheric plasma spraying.
Computer predictions of thermo-mechanical behavior and residual stresses in spray coating process
Authors: Ju D.-Y. , Ji V. , Gassot H.
Published: July 2021

This paper presents a numerical method in order to forecast the thermo-mechanical behavior and the residual stresses in the thermal spray coating process by using high velocity oxygen fuel (HVOF). A set of coupled equations of the heat conduction and stress/strain and solidification based on the metallo-thermo-mechanical theory is introduced into the simulation of thermal spraying. Here, an inelastic constitutive equation with capacity to represent relation of stress/strain during rapid solidification is employed. The numerical modelling based on the finite element method is proposed to solve the heat conduction associated with solidification in the sprayed layer and residual stresses on the interface between multi-layer materials, especially. In this paper, the simulated results of the temperature field, solidified domain and residual stresses in the sprayed layer including interfacial combinations between substrate and spray layer are presented, and the validity of the calculated results is discussed in comparison with the measured results obtained by X-ray diffraction.
Simulation of laser cladding
Authors: Wilden J. , Frank H. , Theiler C. , Seefeld T. , Sepold G.
Published: July 2021

Nickel and titanium aluminides already show a high potential for use in lightweight applications at elevated temperatures; however, the strength of these intermetallics can be increased by directional solidification. These materials show a brittle behaviour at temperatures less than 600°C. Strength and ductility of aluminides are controlled by phase formation during solidification. The problem of crack formation had to be solved for laser rapid prototyping of intermetallics, and the process conditions for formation of directionally solidified structures have to be specified in order to generate directionally solidified TiAl parts properly. A model was developed to determine the influence of the process parameters on melt pool geometry, solidification time, and the formed structure. Temperature gradients and cooling rates were calculated using a simulation that also included feedstock material injection rate and process parameters. The experimental results were analysed using these simulations, and the process parameters were optimised so that crack-free laser-generated TiAl parts exhibiting a partially directionally solidified structure could be produced. The comparison of the simulated and experimental results led to process guidelines for laser generation of directionally solidified TiAl components.
Metallic thin films heated by pulsed lasers. Numerical simulation of the thermal field and the melting kinetics
Authors: Semmar N. , Boulmer-Leborgne C.
Published: July 2021

This modeling is especially applied to the pulsed laser induced heating and melting of a metallic film deposited on a substrate. Study of the thermal field over a surface is usually performed by considering the assumption of ‘semi-infinite medium’. However, a thin film deposited on a rough substrate surface induces bad thermal contacts commonly known as ‘thermal contact resistance’. This interfacial thermal resistance affects the melting kinetics mainly when the film thickness (Z) is small comparatively to the heat diffusion length (ZT). In this work the heat conduction equation and related boundary conditions are resolved by using the implicit finite differences method. The heat source (i.e. the laser intensity) is treated as a surface boundary layer. The thermal contact resistance is introduced in the computation procedure when the heat wave propagation reaches the thin film/substrate interface. It is then possible to calculate the critical temperatures and the melting threshold fluence for high and low contact resistance values. Under these conditions, the temperature profile and melting depth are plotted considering different thickness.. Finally, for 750 mJ/cm² excimer laser fluence and 0.1 cm²/s thin film apparent diffusivity results show that for Z/ZT higher than 0.5, there is no sensitive effect of the thermal contact resistance on the melting kinetics.