bluuebunny/crossref_metadata_2025 huggingface dataset:
Brain volume, energy balance, and cardiovascular health in two nonindustrial South American populations
Authors: Kaplan Hillard , Hooper Paul L. , Gatz Margaret , Mack Wendy J. , Law E. Meng , Chui Helena C. , Sutherland M. Linda , Sutherland James D. , Rowan Christopher J. , Wann L. Samuel , Allam Adel H. , Thompson Randall C. , Michalik David E. , Lombardi Guido , Miyamoto Michael I. , Eid Rodriguez Daniel , Copajira Adrian Juan , Quispe Gutierrez Raul , Beheim Bret A. , Cummings Daniel K. , Seabright Edmond , Alami Sarah , R. Garcia Angela , Buetow Kenneth , Thomas Gregory S. , Finch Caleb E. , Stieglitz Jonathan , Trumble Benjamin C. , Gurven Michael D. , Irimia Andrei
Published: March 2023

Little is known about brain aging or dementia in nonindustrialized environments that are similar to how humans lived throughout evolutionary history. This paper examines brain volume (BV) in middle and old age among two indigenous South American populations, the Tsimane and Moseten, whose lifestyles and environments diverge from those in high-income nations. With a sample of 1,165 individuals aged 40 to 94, we analyze population differences in cross-sectional rates of decline in BV with age. We also assess the relationships of BV with energy biomarkers and arterial disease and compare them against findings in industrialized contexts. The analyses test three hypotheses derived from an evolutionary model of brain health, which we call the embarrassment of riches (EOR). The model hypothesizes that food energy was positively associated with late life BV in the physically active, food-limited past, but excess body mass and adiposity are now associated with reduced BV in industrialized societies in middle and older ages. We find that the relationship of BV with both non-HDL cholesterol and body mass index is curvilinear, positive from the lowest values to 1.4 to 1.6 SDs above the mean, and negative from that value to the highest values. The more acculturated Moseten exhibit a steeper decrease in BV with age than Tsimane, but still shallower than US and European populations. Lastly, aortic arteriosclerosis is associated with lower BV. Complemented by findings from the United States and Europe, our results are consistent with the EOR model, with implications for interventions to improve brain health.
Non-White scientists appear on fewer editorial boards, spend more time under review, and receive fewer citations
Authors: Liu Fengyuan , Rahwan Talal , AlShebli Bedoor
Published: March 2023

Disparities continue to pose major challenges in various aspects of science. One such aspect is editorial board composition, which has been shown to exhibit racial and geographical disparities. However, the literature on this subject lacks longitudinal studies quantifying the degree to which the racial composition of editors reflects that of scientists. Other aspects that may exhibit racial disparities include the time spent between the submission and acceptance of a manuscript and the number of citations a paper receives relative to textually similar papers, but these have not been studied to date. To fill this gap, we compile a dataset of 1,000,000 papers published between 2001 and 2020 by six publishers, while identifying the handling editor of each paper. Using this dataset, we show that most countries in Asia, Africa, and South America (where the majority of the population is ethnically non-White) have fewer editors than would be expected based on their share of authorship. Focusing on US-based scientists reveals Black as the most underrepresented race. In terms of acceptance delay, we find, again, that papers from Asia, Africa, and South America spend more time compared to other papers published in the same journal and the same year. Regression analysis of US-based papers reveals that Black authors suffer from the greatest delay. Finally, by analyzing citation rates of US-based papers, we find that Black and Hispanic scientists receive significantly fewer citations compared to White ones doing similar research. Taken together, these findings highlight significant challenges facing non-White scientists.
Nonspherical ultrasound microbubbles
Authors: Dasgupta Anshuman , Sun Tao , Palomba Roberto , Rama Elena , Zhang Yongzhi , Power Chanikarn , Moeckel Diana , Liu Mengjiao , Sarode Apoorva , Weiler Marek , Motta Alessandro , Porte Céline , Magnuska Zuzanna , Said Elshafei Asmaa , Barmin Roman , Graham Adam , McClelland Arthur , Rommel Dirk , Stickeler Elmar , Kiessling Fabian , Pallares Roger M. , De Laporte Laura , Decuzzi Paolo , McDannold Nathan , Mitragotri Samir , Lammers Twan
Published: March 2023

Surface tension provides microbubbles (MB) with a perfect spherical shape. Here, we demonstrate that MB can be engineered to be nonspherical, endowing them with unique features for biomedical applications. Anisotropic MB were generated via one-dimensionally stretching spherical poly(butyl cyanoacrylate) MB above their glass transition temperature. Compared to their spherical counterparts, nonspherical polymeric MB displayed superior performance in multiple ways, including i) increased margination behavior in blood vessel–like flow chambers, ii) reduced macrophage uptake in vitro, iii) prolonged circulation time in vivo, and iv) enhanced blood–brain barrier (BBB) permeation in vivo upon combination with transcranial focused ultrasound (FUS). Our studies identify shape as a design parameter in the MB landscape, and they provide a rational and robust framework for further exploring the application of anisotropic MB for ultrasound-enhanced drug delivery and imaging applications.
Proteasome inhibitor bortezomib stabilizes and activates p53 in hematopoietic stem/progenitors and double-negative T cells in vivo
Authors: Xue Yuezhen , San Luis Boris , Dress Regine J. , Murad Katzrin Binte Ahmad , Ginhoux Florent , Barker Nick , Lane David
Published: March 2023

We have previously shown that proteasome inhibitor bortezomib stabilizes p53 in stem and progenitor cells within gastrointestinal tissues. Here, we characterize the effect of bortezomib treatment on primary and secondary lymphoid tissues in mice. We find that bortezomib stabilizes p53 in significant fractions of hematopoietic stem and progenitor cells in the bone marrow, including common lymphoid and myeloid progenitors, granulocyte-monocyte progenitors, and dendritic cell progenitors. The stabilization of p53 is also observed in multipotent progenitors and hematopoietic stem cells, albeit at lower frequencies. In the thymus, bortezomib stabilizes p53 in CD4
−
CD8
−
T cells. Although there is less p53 stabilization in secondary lymphoid organs, cells in the germinal center of the spleen and Peyer’s patch accumulate p53 in response to bortezomib. Bortezomib induces the upregulation of p53 target genes and p53 dependent/independent apoptosis in the bone marrow and thymus, suggesting that cells in these organs are robustly affected by proteasome inhibition. Comparative analysis of cell percentages in the bone marrow indicates expanded stem and multipotent progenitor pools in p53R172H mutant mice compared with p53 wild-type mice, suggesting a critical role for p53 in regulating the development and maturation of hematopoietic cells in the bone marrow. We propose that progenitors along the hematopoietic differentiation pathway express relatively high levels of p53 protein, which under steady-state conditions is constantly degraded by Mdm2 E3 ligase; however, these cells rapidly respond to stress to regulate stem cell renewal and consequently maintain the genomic integrity of hematopoietic stem/progenitor cell populations.
Associative learning in the cnidarian
Nematostella vectensis
Authors: Botton-Amiot Gaelle , Martinez Pedro , Sprecher Simon G.
Published: March 2023

The ability to learn and form memories allows animals to adapt their behavior based on previous experiences. Associative learning, the process through which organisms learn about the relationship between two distinct events, has been extensively studied in various animal taxa. However, the existence of associative learning, prior to the emergence of centralized nervous systems in bilaterian animals, remains unclear. Cnidarians such as sea anemones or jellyfish possess a nerve net, which lacks centralization. As the sister group to bilaterians, they are particularly well suited for studying the evolution of nervous system functions. Here, we probe the capacity of the starlet sea anemone
Nematostella vectensis
to form associative memories by using a classical conditioning approach. We developed a protocol combining light as the conditioned stimulus with an electric shock as the aversive unconditioned stimulus. After repetitive training, animals exhibited a conditioned response to light alone—indicating that they learned the association. In contrast, all control conditions did not form associative memories. Besides shedding light on an aspect of cnidarian behavior, these results root associative learning before the emergence of NS centralization in the metazoan lineage and raise fundamental questions about the origin and evolution of cognition in brainless animals.
Overcoming the adhesion paradox and switchability conflict on rough surfaces with shape-memory polymers
Authors: Linghu Changhong , Liu Yangchengyi , Tan Yee Yuan , Sing Jun Heng Marcus , Tang Yuxuan , Zhou Aiwu , Wang Xiufeng , Li Dong , Gao Huajian , Hsia K. Jimmy
Published: March 2023

Smart adhesives that can be applied and removed on demand play an important role in modern life and manufacturing. However, current smart adhesives made of elastomers suffer from the long-standing challenges of the adhesion paradox (rapid decrease in adhesion strength on rough surfaces despite adhesive molecular interactions) and the switchability conflict (trade-off between adhesion strength and easy detachment). Here, we report the use of shape-memory polymers (SMPs) to overcome the adhesion paradox and switchability conflict on rough surfaces. Utilizing the rubbery–glassy phase transition in SMPs, we demonstrate, through mechanical testing and mechanics modeling, that the conformal contact in the rubbery state followed by the shape-locking effect in the glassy state results in the so-called rubber-to-glass (R2G) adhesion (defined as making contact in the rubbery state to a certain indentation depth followed by detachment in the glassy state), with extraordinary adhesion strength (>1 MPa) proportional to the true surface area of a rough surface, overcoming the classic adhesion paradox. Furthermore, upon transitioning back to the rubbery state, the SMP adhesives can detach easily due to the shape-memory effect, leading to a simultaneous improvement in adhesion switchability (up to 103, defined as the ratio of the SMP R2G adhesion to its rubbery-state adhesion) as the surface roughness increases. The working principle and the mechanics model of R2G adhesion provide guidelines for developing stronger and more switchable adhesives adaptable to rough surfaces, thereby enhancing the capabilities of smart adhesives, and impacting various fields such as adhesive grippers and climbing robots.
Synchronization of the circadian clock to the environment tracked in real time
Authors: Fang Mingxu , Chavan Archana G. , LiWang Andy , Golden Susan S.
Published: March 2023

The circadian system of the cyanobacterium
Synechococcus elongatus
PCC 7942 relies on a three-protein nanomachine (KaiA, KaiB, and KaiC) that undergoes an oscillatory phosphorylation cycle with a period of ~24 h. This core oscillator can be reconstituted in vitro and is used to study the molecular mechanisms of circadian timekeeping and entrainment. Previous studies showed that two key metabolic changes that occur in cells during the transition into darkness, changes in the ATP/ADP ratio and redox status of the quinone pool, are cues that entrain the circadian clock. By changing the ATP/ADP ratio or adding oxidized quinone, one can shift the phase of the phosphorylation cycle of the core oscillator in vitro. However, the in vitro oscillator cannot explain gene expression patterns because the simple mixture lacks the output components that connect the clock to genes. Recently, a high-throughput in vitro system termed the in vitro clock (IVC) that contains both the core oscillator and the output components was developed. Here, we used IVC reactions and performed massively parallel experiments to study entrainment, the synchronization of the clock with the environment, in the presence of output components. Our results indicate that the IVC better explains the in vivo clock-resetting phenotypes of wild-type and mutant strains and that the output components are deeply engaged with the core oscillator, affecting the way input signals entrain the core pacemaker. These findings blur the line between input and output pathways and support our previous demonstration that key output components are fundamental parts of the clock.
A mineral-based origin of Earth’s initial hydrogen peroxide and molecular oxygen
Authors: He Hongping , Wu Xiao , Zhu Jianxi , Lin Mang , Lv Ying , Xian Haiyang , Yang Yiping , Lin Xiaoju , Li Shan , Li Yiliang , Teng H. Henry , Thiemens Mark H.
Published: March 2023

Terrestrial reactive oxygen species (ROS) may have played a central role in the formation of oxic environments and evolution of early life. The abiotic origin of ROS on the Archean Earth has been heavily studied, and ROS are conventionally thought to have originated from H
2
O/CO
2
dissociation. Here, we report experiments that lead to a mineral-based source of oxygen, rather than water alone. The mechanism involves ROS generation at abraded mineral–water interfaces in various geodynamic processes (e.g., water currents and earthquakes) which are active where free electrons are created via open-shell electrons and point defects, high pressure, water/ice interactions, and combinations of these processes. The experiments reported here show that quartz or silicate minerals may produce reactive oxygen-containing sites (≡SiO•, ≡SiOO•) that initially emerge in cleaving Si–O bonds in silicates and generate ROS during contact with water. Experimental isotope-labeling experiments show that the hydroxylation of the peroxy radical (≡SiOO•) is the predominant pathway for H
2
O
2
generation. This heterogeneous ROS production chemistry allows the transfer of oxygen atoms between water and rocks and alters their isotopic compositions. This process may be pervasive in the natural environment, and mineral-based production of H
2
O
2
and accompanying O
2
could occur on Earth and potentially on other terrestrial planets, providing initial oxidants and free oxygen, and be a component in the evolution of life and planetary habitability.
Structure-based design of a SARS-CoV-2 Omicron-specific inhibitor
Authors: Yang Kailu , Wang Chuchu , Kreutzberger Alex J. B. , White K. Ian , Pfuetzner Richard A. , Esquivies Luis , Kirchhausen Tomas , Brunger Axel T.
Published: March 2023

The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) introduced a relatively large number of mutations, including three mutations in the highly conserved heptad repeat 1 (HR1) region of the spike glycoprotein (S) critical for its membrane fusion activity. We show that one of these mutations, N969K induces a substantial displacement in the structure of the heptad repeat 2 (HR2) backbone in the HR1HR2 postfusion bundle. Due to this mutation, fusion-entry peptide inhibitors based on the Wuhan strain sequence are less efficacious. Here, we report an Omicron-specific peptide inhibitor designed based on the structure of the Omicron HR1HR2 postfusion bundle. Specifically, we inserted an additional residue in HR2 near the Omicron HR1 K969 residue to better accommodate the N969K mutation and relieve the distortion in the structure of the HR1HR2 postfusion bundle it introduced. The designed inhibitor recovers the loss of inhibition activity of the original longHR2_42 peptide with the Wuhan strain sequence against the Omicron variant in both a cell–cell fusion assay and a vesicular stomatitis virus (VSV)-SARS-CoV-2 chimera infection assay, suggesting that a similar approach could be used to combat future variants. From a mechanistic perspective, our work suggests the interactions in the extended region of HR2 may mediate the initial landing of HR2 onto HR1 during the transition of the S protein from the prehairpin intermediate to the postfusion state.
Anaphoric potential of pseudo-incorporated bare objects in Persian
Authors: Modarresi Fereshteh , Krifka Manfred
Published: March 2023

This paper investigates the syntax, semantics and discourse effects of bare nominal objects in Persian, analysed as an instance of pseudo-incorporation, in contrast to objects marked by the indefinite article yek and to objects marked by the object marker -rā. The main experimental result is that bare objects readily allow for anaphoric uptake, in contrast to claims in previous literature about Persian and pseudo-incorporated objects in other languages. However, anaphoric uptake is less readily available than with yek-marked objects.

We account for this difference, elaborating on Krifka & Modarresi (2016), where we argue for existential closure over the vP (Diesing 1992) as analyzed in Modarresi (2014) and an interpretation of bare objects as definites dependent on this existential closure. We give an implementation in Discourse Representation Theory (Kamp & Reyle 1993) which provides a model for our experimental findings. We consider -rā as marking constituents that moved out of the existential closure. Thus BNs if marked with -rā are definite and if not are definites dependent on existential closure similar, leading to weak definite effects. This also explains semantic features like the number-neutrality of bare objects, the specific/definite interpretation of rā-marked objects, and the similarity of bare objects to weak definites in languages like English.
Ezafe and the article
Authors: Karim Shuan Osman
Published: March 2023

There are a variety of different nominal systems within the Western Iranian languages. Nominals in some of these languages are maximally sensitive to case, number, gender, animacy, ezafe (modification), and definiteness. However, most of these languages only inflect for a subset of these categories. An additional peculiarity of these systems is that some of these languages feature wildly differing systems when inflectional features interact. For instance, Zazaki features a caseless system on indefinite nouns, a bicasual (two case) system on definite nouns, and as many as four cases (following Paul, 1998a) on modified nouns. This paper explores, synchronically and diachronically, the nominal systems observed in Western Iranian languages focusing on the interaction between (in)definiteness and modification by attributive adjectives. This constitutes a near-comprehensive juxtaposition of data that can serve as an essential reference for anyone who seeks to study and understand Ezafe and the article in New Western Iranian.
Mood selection in complement clauses in Persian
Authors: Nematollahi Narges
Published: March 2023

Similar to Romance and Balkan languages, Persian makes a formal distinction between indicative and subjunctive moods in its complement clauses. This paper proposes several generalizations about the distribution of the two moods, and evaluates the current theories of mood selection against Persian data. The proposal is that indicative appears when the complement is propositional, i.e., of type , and when one of the two other conditions holds: (1) the matrix predicate entails the content of the complement clause is in attitude holder’s context set, in which case the indicative mood makes no special semantic contribution, OR (2) the content of the complement clause or its negation is in speaker’s context set, in which case indicative signals the epistemic commitment of the speaker. Subjunctive, on the other hand, is selected when the conditions for the indicative are not met. As such, I argue that mood selection in complement clauses in Persian makes references to (1) the semantic type of the complement, (2) the semantics of the matrix predicate in terms of (non)veridicality, and (3) the speaker’s stand about the complement.
Three types of verb stem levelling in Tat
Authors: Suleymanov Murad
Published: March 2023

This paper explores phenomena affecting to various degrees the historical opposition of two verb stems in Tat, an Iranian language spoken in the Caucasus. Using corpora from a number of Tat varieties collected by different authors throughout the past century and a half as well interviews with modern-day native speakers, I illustrate the gradual blurring of the distinction between the stems resulting from what appears to be a morphological change in progress.
Semi-anticausatives
Authors: Kasraie Kilakjani Davood
Published: March 2023

Based on data from Persian, this study argues that what I refer to here as “semi-anticausatives” behave like a canonical unmarked anticausative with respect to the agentivity tests. However, further investigation shows that they appear with a voice head. This is contrary to the previous assumption that unmarked anticausatives do not constitute a voice head (Schäfer 2008; Alexiadou et al. 2015). I argue that semi-anticausatives, among other things, may license hidden “agentive causers”.
The nature and licensing of hi:tʃ elements in Persian
Authors: Storoshenko Dennis R. , Nakhaei Mahyar
Published: March 2023

This paper examines the nature of elements such as hi:tʃkӕs “anyone” in Persian, which have been described as either Negative Polarity Items (Taleghani 2006) or Negative Concord Items (Kwak 2010) in prior literature. Such claims have typically been used to motivate analyses of Persian NegP as being high in the clause structure, above TP. This is in contrast to more recent analyses which have argued for a low position of negation (Kahnemuyipour 2017). Here, we present experimental evidence showing that c-commanding negation is not sufficient for licensing hi:tʃ elements, unlike English any. We also show that hi:tʃ elements have many properties in common with similar elements in Japanese and Korean, where there is less certainty in designating these as Negative Concord Items, and where negation is independently argued to be low. Thus, we claim, the distribution of hi:tʃ elements cannot be upheld as a proof of syntactically high negation, under either a polarity item or concord item analysis. We close the paper with a typological discussion, suggesting that the properties of hi:tʃ elements and their kin seem to be broadly shared among OV languages more generally.
Vocabulary suitability of science TED talks for English for science teaching and learning
Authors: Vuković-Stamatović Milica
Published: March 2023

With a view to advancing their students’ listening comprehension and vocabulary, English for Science teachers are frequently in search of new and interesting audio and video materials. TED Talks on science topics are a good option for this purpose. But just how suitable, vocabulary-wise, are they for English for Science learners? This study explores the lexical profile of TED Talks on science and compares it against non-science TED Talks and science academic lectures. We use a 5-million-word TED Talk corpus, with a 1.3-million-word science subsection. Of the two categories of TED Talks, it is the science ones that are lexically more similar to science academic lectures. Science TED Talks also feature significantly more technical vocabulary than non-science TED Talks. Reasonable listening comprehension is achieved at 4,000 words for science TED Talks, while ideal comprehension is achieved at 8,000 words for both categories. These results recommend science TED Talks for English for Science listening.
Phasal polarity in Tunisian Arabic
Authors: Fischer Jens G. , Persohn Bastian , Ritt-Benmimoun Veronika
Published: March 2023

This paper gives a corpus-based descriptive account of the phasal polarity system (still,already,not yet, andno longer) in the Arabic vernacular of Tunisia. The aim is to broaden the empirical foundations for cross-linguistic research in this domain, and to narrow the gap between typologically oriented and philological research on Arabic varieties. Like many languages (van Baar 1997: 118), Tunisian Arabic has autochthonous expressions for the three conceptsstill,not yet, andno longer.stillis primarily expressed via a construction < ‘has not ceased’. Despite its conceptual transparency, this appears to be a cross-linguistically uncommon source.not yetis expressed via the inner negation ofstill, andno longervia a construction < ‘has not repeated’. Foralready, northern sedentary varieties have borrowed from French (replacing an older autochthonous expression), whereas southern Bedouin varieties have a “gap” in their system. The description further includes notes on the synchronic and diachronic variation of individual items, and functions of these outside the realm of phasal polarity.
Soyon Hong: My role is to empower
Authors: Van Emmenis Lucie
Published: March 2023

Soyon Hong is a group leader at the UK Dementia Research Institute at UCL. Her lab is interested in investigating how multiple cell types work together to maintain brain function, and how these interactions are affected and altered in neurodegenerative disease states such as Alzheimer’s disease. Here, Soyon talks about how she got interested in science, what she’s currently working on, and the importance of good mentorship throughout your academic career.
Markov chain Monte Carlo methods for graph refinement in spinfoam cosmology
Authors: Frisoni Pietropaolo , Gozzini Francesco , Vidotto Francesca
Published: March 2023

We study the behavior of the Lorentzian Engle-Pereira-Rovelli-Livine spinfoam amplitude with homogeneous boundary data, under a graph refinement going from five to twenty boundary tetrahedra. This can be interpreted as a wave function of the Universe, for which we compute boundary geometrical operators, correlation functions, and entanglement entropy. The numerical calculation is made possible by adapting the Metropolis-Hastings algorithm, along with recently developed computational methods appropriate for the deep quantum regime. We confirm that the transition amplitudes are stable against such refinement. We find that the average boundary geometry does not change, but the new degrees of freedom correct the quantum fluctuations of the boundary and the correlations between spatial patches. The expectation values are compatible with their geometrical interpretation and the correlations between neighboring patches decay when computed across different spinfoam vertices.
Inconsistent black hole kick estimates from gravitational-wave models
Authors: Borchers Angela , Ohme Frank
Published: March 2023

The accuracy of gravitational-wave (GW) models of compact binaries has traditionally been addressed by the mismatch between the model and numerical-relativity (NR) simulations. This is a measure of the overall agreement between the two waveforms. However, the largest modelling error typically appears in the strong-field merger regime and may affect subdominant signal harmonics more strongly. These inaccuracies are often not well characterised by the mismatch. We explore the use of a complementary, physically motivated tool to investigate the accuracy of GW harmonics in waveform models: the remnant’s recoil, or kick velocity. Asymmetric binary mergers produce remnants with significant recoil, encoded by subtle imprints in the GW signal. The kick estimate is highly sensitive to the intrinsic inaccuracies of the modelled GW harmonics during the strongly relativistic merger regime. Here we investigate the accuracy of the higher harmonics in four state-of-the-art waveform models of binary black holes. We find that the SEOBNRv4HM_ROM, IMRPhenomHM, IMRPhenomXHM and NRHybSur3dq8 models are not consistent in their kick predictions. Our results enable us to identify regions in the parameter space where the models require further improvement and support the use of the kick estimate to investigate waveform systematics. We discuss how NR kick estimates could be used to calibrate waveform models further, proposing the first steps towards kick-based gravitational-wave tuning.
Combining x-ray real and reciprocal space mapping techniques to explore the epitaxial growth of semiconductors
Authors: Magalhães S , Cabaço J S , Concepción O , Buca D , Stachowicz M , Oliveira F , Cerqueira M F , Lorenz K , Alves E
Published: March 2023

In the present work, the importance of determining the strain states of semiconductor compounds with high accuracy is demonstrated. For the matter in question, new software titled LAPAs, the acronym for LAttice PArameters is presented. The lattice parameters as well as the chemical composition of Al1−x
In
x
N and Ge1−x
Sn
x
compounds grown on top of GaN- and Ge- buffered c-Al2O3 and (001) oriented Si substrates, respectively, are calculated via the real space Bond’s method. The uncertainties in the lattice parameters and composition are derived, compared and discussed with the ones found via x-ray diffraction reciprocal space mapping. Broad peaks lead to increased centroid uncertainty and are found to constitute up to 99% of the total uncertainty in the lattice parameters. Refraction correction is included in the calculations and found to have an impact of 0.001 Å in the lattice parameters of both hexagonal and cubic crystallographic systems and below 0.01% in the quantification of the InN and Sn contents. Although the relaxation degrees of the nitride and tin compounds agree perfectly between the real and reciprocal-spaces methods, the uncertainty in the latter is found to be ten times higher. The impact of the findings may be substantial for the development of applications and devices as the intervals found for the lattice match the condition of Al1−x
In
x
N grown on GaN templates vary between ∼1.8% (0.1675–0.1859) and 0.04% (0.1708–0.1712) if derived via the real- and reciprocal spaces methods.
Ag nanodot/Mg/Al reflective Ohmic contacts simultaneously suitable for n-type and p-type GaN
Authors: Jin Nan , Zhou Yugang , Guo Yan , Pan Sai , Zhang Rong , Zheng Youdou
Published: March 2023

This work reports on high-reflectivity Ag nanodot (AgND)/Mg/Al Ohmic contacts suitable for both p-GaN and n-GaN. The lowest specific contact resistances are found to be 2.25 × 10−2 Ω·cm2 on p-GaN and 2.56 × 10−5 Ω·cm2 on n-GaN. Ag was deposited and converted into AgNDs by annealing, and Mg/Al was then deposited. A second annealing process at different temperatures was performed to check the thermal stability of the contacts. Both the p-GaN and n-GaN contacts were Ohmic after annealing at 300 °C or below. The AgND/Mg/Al contacts annealed at 250 °C or less showed a reflectivity of over 91% for wavelengths from 400 to 550 nm. X-ray photoelectron spectroscopy and x-ray diffraction measurements were performed to investigate the contact mechanisms. We propose that in AgND/Mg/Al on p-GaN, the effective barrier is lowered due to the presence of an Ag2O intermedia layer and the tunneling effect enables Ohmic contact. When the annealing temperature is 350 °C or higher, the Ag2O changes to β-AgGaO2 or is decomposed and the height and width of the barrier for holes increase, which causes the Ohmic contact to deteriorate. The Ohmic behavior of AgND/Mg/Al contacts on n-GaN is assumed to be mainly due to the high direct coverage ratio of Mg and the good Ohmic contact behavior of Mg/n-GaN. These results show that AgND/Mg/Al Ohmic contacts can be fabricated simultaneously on both p-GaN and n-GaN, which is a possible solution for improving the density of both GaN-based ICs and micro-light emitting diodes (LEDs). This contact scheme can also improve the light output efficiency of GaN-based LEDs.
Hydrogen production by microwave plasma decomposition of H2S at atmospheric pressure with cooling implemented in its afterglow
Authors: Li Shou-Zhe , Xie Shi-Hui , Niu Yu-Long , Zhao Zilu , Yang Dezheng , Zhang Jialiang , Wang Wenchun , Li Xuechen
Published: March 2023

In this work, H2S is decomposed with the use of a N2 microwave (MW) plasma torch at atmospheric pressure with hydrogen as the main product as well as elemental sulfur. The variation of the conversion rate of H2S into H2 is investigated with respect to various dilution ratios of H2S to N2 as the carrier gas, MW power, total flow rate, and arrangement of the cooling rods in the reaction chamber. It is experimentally found that direct cooling of the afterglow by introducing a cooling rod downstream in the reaction chamber enhances the conversion rate, and an optimum for each conversion curve is determined, which is dependent of MW power, gas flow rate, and relative distance of the cooling rod in the afterglow.
Layer-resolved electronic behavior in a Kondo lattice system, CeAgAs2
Authors: Datta Sawani , Prakash Pandeya Ram , Bikash Dey Arka , Gloskovskii A , Schlueter C , Peixoto T R F , Singh Ankita , Thamizhavel A , Maiti Kalobaran
Published: March 2023

We investigate the electronic structure of an antiferromagnetic Kondo lattice system CeAgAs2 employing hard x-ray photoemission spectroscopy. CeAgAs2, an orthorhombic variant of HfCuSi2 structure, exhibits antiferromagnetic ground state, Kondo like resistivity upturn and compensation of magnetic moments at low temperatures. The photoemission spectra obtained at different photon energies suggest termination of the cleaved surface at cis-trans-As layers. The depth-resolved data show significant surface-bulk differences in the As and Ce core level spectra. The As 2p bulk spectrum shows distinct two peaks corresponding to two different As layers. The peak at higher binding energy correspond to cis-trans-As layers and is weakly hybridized with the adjacent Ce layers. The As layers between Ce and Ag-layers possess close to trivalent configuration due to strong hybridization with the neighboring atoms and the corresponding feature appear at lower binding energy. Ce 3d core level spectra show multiple features reflecting strong Ce-As hybridization and strong correlation. Intense f
0 peak is observed in the surface spectrum while it is insignificant in the bulk. In addition, we observe a features at binding energy lower than the well-screened feature indicating the presence of additional interactions. This feature becomes more intense in the bulk spectra suggesting it to be a bulk property. Increase in temperature leads to a spectral weight transfer to higher binding energies in the core level spectra and a depletion of spectral intensity at the Fermi level as expected in a Kondo material. These results reveal interesting surface-bulk differences, complex interplay of intra- and inter-layer covalency, and electron correlation in the electronic structure of this novel Kondo lattice system.
Radioactivity of residues from waste incineration facilities in Finland
Authors: Kallio Antti , Virtanen Sinikka , Leikoski Niina , Iloniemi Eeva , Kämäräinen Meerit , Hildén Timo , Mattila Aleksi
Published: March 2023

Waste incineration in Europe has been increasing in the past few decades as there is a need to reduce the burden on landfills and their associated environmental concerns. While incineration reduces the volume of the waste, the volume of slag and ash is still substantial. To find out potential radiation risks that incineration residues could set to workers or the public, the levels of radioactive elements in these residues were investigated from nine waste incineration plants in Finland. Natural and artificial radionuclides were detected in the residues, but in general the activity concentrations were low. This study shows that the level of Cs-137 in the fly ash from municipal waste incineration follows the pattern of 1986 fallout zones in Finland, although the levels are significantly lower than in ash from bioenergy production from the same areas. Am-241 was also detected in many samples, although the activity concentrations were very low. Based on the findings in this study, the typical ash and slag residues from municipal waste incineration do not need radiation protection measures for workers or the public even in regions that received up to 80 kBq m−2 of Cs-137 fallout in 1986. The further use of these residues need not be restricted due to radioactivity. Hazardous waste incineration residues and other special cases need to be considered separately, depending on the original waste composition.
Selective LASER melting part quality prediction and energy consumption optimization
Authors: Sabuj MD Rokibujjaman , Afshari Sajad Saraygord , Liang Xihui
Published: March 2023

Selective LASER Melting (SLM) popularity is increasing because of its ability to quickly produce components with acceptable quality. The SLM process parameters, such as LASER power and scan speed, play a significant role in assuring the quality of customized SLM products. Therefore, the process parameters must be tuned appropriately to achieve high-quality customized products. Most existing methods for adjusting the SLM’s parameters use multiple inputs and one or two outputs to develop a model for achieving their desired quality. However, the number of the model’s input and output parameters to be considered can be increased to achieve a more comprehensive model. Furthermore, energy consumption is also a factor that should be considered when adjusting input parameters. This paper presents a multi-inputs-multi-outputs (MIMO) artificial neural network model to predict the SLM product qualities. We also try to combine training data from different sources to achieve a more general model that can be used in real applications by industries. The model inputs are LASER power, scan speed, overlap rate, and hatch distance. Moreover, four critical product quality measures: relative density, hardness, tensile strength, and porosity, are used as the model’s outputs. After finding a proper model, an energy optimization method is developed using the genetic algorithm in this paper. The objective of the optimization is to minimize the energy consumption of SLM manufacturing with a less compromised output quality. The results of this study can be used in the industry to decrease energy consumption while maintaining the required quality.
Directional vapor transported and water-proof nanofibrous membranes for liquid desiccant dehumidification systems
Authors: Yao Ye , Su Yazhou , Li Wenhua , Shi Lingxiang , Sun Xiaoxia
Published: March 2023

The membrane-based liquid desiccant dehumidification system is a newly developed method in the field of air dehumidification. In this study, double-layer nanofibrous membranes (DLNMs) with directional vapor transport and water repellency for liquid dehumidification were fabricated by a simple electrospinning process. Specifically, the combination of thermoplastic polyurethane nanofibrous membrane and polyvinylidene fluoride (PVDF) nanofibrous membrane forms a cone-like structure in DLNMs, resulting in directional vapor transportation. The nanoporous structure and rough surface of PVDF nanofibrous membrane provide waterproof performance for DLNMs. Compare with the commercial membranes, the proposed DLNMs have a significantly higher water vapor permeability coefficient, which is as high as 539.67 g·μm m−2·24 h·Pa. This study not only provides a new route to construct a directional vapor transport and waterproof membrane, but also demonstrates the huge application prospect of the nanofibrous membrane formed by electrospinning in the field of solution dehumidification.
On the link between mechanics and thermal properties: mechanothermics
Authors: Collin Eddy , Golokolenov Ilya , Maillet Olivier , Saminadayar Laurent , Bourgeois Olivier
Published: March 2023

We report on the theoretical derivation of macroscopic thermal properties (specific heat, thermal conductivity) of an electrically insulating rod connected to two reservoirs, from the linear superposition of its mechanical mode Brownian motions. The calculation is performed for a weak thermal gradient, in the classical limit (high temperature). The development is kept basic as far as geometry and experimental conditions are concerned, enabling an almost fully analytic treatment. In the modeling, each of the modes is subject to a specific Langevin force, which enables to produce the required temperature profile along the rod. The theory is predictive: the temperature gradient (and therefore energy transport) is linked to motion amplitude cross-correlations between nearby mechanical modes. This arises because energy transport is actually mediated by mixing between the modal waves, and not by the modes themselves. This result can be tested on experiments, and shall extend the concepts underlying equipartition and fluctuation–dissipation theorems. The theory links intimately the macroscopic size of the clamping region where the mixing occurs to the microscopic lengthscale of the problem at hand: the phonon mean-free-path. This clamping region, which is key, has received recently a renewed attention in the field of nanomechanics with topical works on ‘phonon shields’ and ‘soft clamping’. We believe that our work should impact the domain of thermal transport in nanostructures, with future developments of the theory toward the quantum regime.
An accordion superlattice for controlling atom separation in optical potentials
Authors: Wili Simon , Esslinger Tilman , Viebahn Konrad
Published: March 2023

We propose a method for separating trapped atoms in optical lattices by large distances. The key idea is the cyclic transfer of atoms between two lattices of variable spacing, known as accordion lattices, each covering at least a factor of two in lattice spacing. By coherently loading atoms between the two superimposed potentials, we can reach, in principle, arbitrarily large atom separations, while requiring only a relatively small numerical aperture. Numerical simulations of our ‘accordion superlattice’ show that the atoms remain localized to one lattice site throughout the separation process, even for moderate lattice depths. In a proof-of-principle experiment, we demonstrate the optical fields required for the accordion superlattice using acousto-optic deflectors. The method can be applied to neutral-atom quantum computing with optical tweezers, as well as quantum simulation of low-entropy many-body states. For instance, a unit-filling atomic Mott insulator can be coherently expanded by a factor of ten in order to load an optical tweezer array with very high filling. In turn, sorted tweezer arrays can be compressed to form high-density states of ultracold atoms in optical lattices. The method can also be applied to biological systems where dynamical separation of particles is required.
Study of the structure of MgSiO3 system under compression by using ring statistics and voronoi analysis
Authors: Nguyen Hoang Anh , Van Hong Nguyen
Published: March 2023

The structural change of MgSiO3 liquid under compression is still one of the most interesting challenges. In this paper, we perform the molecular dynamics simulation to study the structural change of MgSiO3 liquid from 0 to 200 GPa. Ring statistics are analyzed to clarify the intermediate-range order, to explain why the second peak of Si–Si PRDFs splits into 2 subpeaks at 200 GPa, and to show the heterogeneity of MgSiO3. Large rings which form at high pressures would capture the oxygen atoms. Oxygen atoms which have negative charge attract Mg2+ ions, creating magnesium-rich regions. Besides, the Voronoi and Q
n
distribution changes on the ring with pressure are clarified to give more information about the rings.
Frequency regulation of Terahertz quantum cascade lasers by changing barrier thickness
Authors: Luo Jiawen , Chen Fengwei , Jiang Tao , Zhan Zhiqiang , Wang Xuemin , Yang Qi , Zou Ruijiao , Li Jia , Zeng Yong , Wu Weidong , Xu Lixin
Published: March 2023

Terahertz (THz) sources with different frequency are important to gas detection. THz quantum cascade lasers (QCLs) based on resonant phonon structure with different frequency emission by changing transition barrier thickness are hereby presented. By theoretically calculation, a 0.19 nm thickening change of transition barrier would cause an approximately 350 GHz regulation range in frequency, and is then confirmed by experimental results. The corresponding far field beam profile keeps almost unchanged. With the increase of the transition barrier thickness, the output power only decreases by 15%, but the threshold current density decreases 24%. This simple method contributes to a satisfactory gas-detection approach with a stability of relative high output power.
A theoretical study of the effects of electric field, hydrostatic pressure, and temperature on photoionization cross-section of a donor impurity in (Al, Ga)N/AlN double triangular quantum wells
Authors: Belaid Walid , El Ghazi Haddou , Zaki Shrouk E , Basyooni Mohamed A , Tihtih Mohammed , Ennadir Redouane , Kılıç Hamdi Şükür , Zorkani Izeddine , Jorio Anouar
Published: March 2023

The aim of this research is to analyze the influence of various factors on the photo-ionization cross-section in (Al, Ga)N/AlN double triangular quantum wells. Using the finite difference method, the effects of the electric field, hydrostatic pressure, temperature, and Ga concentration were investigated within the effective mass and parabolic approximations. Our findings show that the photo-ionization cross-section (PICS) is highly dependent on all the variables under consideration. The optical spectra were blue-shifted with increasing electric field and pressure and red-shifted with increasing temperature and impurity displacement far from the center of the structure. Furthermore, it was found that changes in gallium content and impurity position can increase the PICS amplitude. A comparison of the obtained results with the existing literature as a limiting case of the reported problem is also provided, and excellent agreement is found.
Testing gravitational wave propagation with multiband detections
Authors: Baker Tessa , Barausse Enrico , Chen Anson , de Rham Claudia , Pieroni Mauro , Tasinato Gianmassimo
Published: March 2023

Effective field theories (EFT) of dark energy (DE) — built to parameterise the properties of DE in an agnostic manner — are severely constrained by measurements of the propagation speed of gravitational waves (GW). However, GW frequencies probed by ground-based interferometers lie around the typical strong coupling scale of the EFT, and it is likely that the effective description breaks down before even reaching that scale. We discuss how this leaves the possibility that an appropriate ultraviolet completion of DE scenarios, valid at scales beyond an EFT description, can avoid present constraints on the GW speed. Instead, additional constraints in the lower frequency LISA band would be harder to escape, since the energies involved are orders of magnitude lower. By implementing a method based on GW multiband detections, we show indeed that a single joint observation of a GW150914-like event by LISA and a terrestrial interferometer would allow one to constrain the speed of light and gravitons to match to within 10-15. Multiband GW observations can therefore firmly constrain scenarios based on the EFT of DE, in a robust and unambiguous way.