bluuebunny/crossref_metadata_2025 huggingface dataset:
Bandgap and vibration transfer characteristics of scissor-like periodic metamaterials
Authors: Li Yingli , Zhou Wenxi
Published: July 2021

A periodic mass-spring-truss chain based on a scissor-like structure and inertial amplification is proposed to seek for low-frequency vibration attenuation. The resonant and anti-resonant frequencies of a basic element are obtained analytically to explain the resonance and anti-resonance of the periodic chain. The formation of bandgaps is explored, revealing that the vertical movements of the vertices take the input kinetic energy away from the horizontal movement energy. The cut-off frequencies of three models are derived analytically to compare the effect of the inertia amplification, which can reach more than three times the classical mass-spring chain with a small angle. Also, the effect of stiffness amplification is presented when the spring mounted vertically, unlike the classical inertial amplification systems. Thus, the optimal configuration for low-frequency attenuation is obtained, that is, the spring mounted horizontally and the masses mounted at the upper and lower vertices. The chain with mass on the upper and lower vertices has the lowest cut-off frequency, which is 17.7% lower than that of the classical mass-spring chain. A diatomic chain is studied to find lower and wider bandgaps, where the central frequency is 25% lower than the classical mass-spring diatomic chain. The central frequency and width of the new bandgap can be tunable accordingly. The result shows that small angles or low stiffness ratios result in lower bandgaps. Meanwhile, the large angles, big differences of masses, or high stiffness ratios lead to wider bandgaps.
Ab initio study on the fast reversible phase transitions of Ge2Sb2Te5
Authors: Yang Fei , Tao Yue , Zhang Le , Han Junnan , Cao Xincheng , Zhuo Zhenguo , Zhu Ziyue , Liu Wenjin , Dai Yuehua
Published: July 2021

Ge2Sb2Te5 (GST) alloy has the ability to quickly transform between the amorphous phase and the crystalline phase; therefore, it can be used in non-volatile phase change storage. First-principles molecular dynamics was used to simulate the reversible phase change process of GST alloy, namely, amorphization and crystallization. The amorphous state was obtained by melting (∼3000 K) and cooling, and the amorphization process was characterized by the pair correlation function and bond angle distribution. The bond angles of amorphous GST were mainly distributed around 60°, 90°, and 110°, indicating the existence of octahedral and tetrahedral bonding configurations. The crystalline state was obtained by annealing at a temperature of 600 K, and the crystallization process was characterized by the pair correlation function, component disordered number, bond angle distribution, and dynamic atomic structure change. The results show that the bond angle of GST in crystallization is mainly distributed around 90°, and the structure mainly contains four-membered rings formed by Ge–Te and Sb–Te. By analyzing the optical properties, with the growth of crystallization time, the absorption coefficient, reflectivity, and conductivity of GST were significantly improved.
Label-free screening of brain tissue myelin content using phase imaging with computational specificity (PICS)
Authors: Fanous Michael , Shi Chuqiao , Caputo Megan P. , Rund Laurie A. , Johnson Rodney W. , Das Tapas , Kuchan Matthew J. , Sobh Nahil , Popescu Gabriel
Published: July 2021

Inadequate myelination in the central nervous system is associated with neurodevelopmental complications. Thus, quantitative, high spatial resolution measurements of myelin levels are highly desirable. We used spatial light interference microcopy (SLIM), a highly sensitive quantitative phase imaging (QPI) technique, to correlate the dry mass content of myelin in piglet brain tissue with dietary changes and gestational size. We combined SLIM micrographs with an artificial intelligence (AI) classifying model that allows us to discern subtle disparities in myelin distributions with high accuracy. This concept of combining QPI label-free data with AI for the purpose of extracting molecular specificity has recently been introduced by our laboratory as phase imaging with computational specificity. Training on 8000 SLIM images of piglet brain tissue with the 71-layer transfer learning model Xception, we created a two-parameter classification to differentiate gestational size and diet type with an accuracy of 82% and 80%, respectively. To our knowledge, this type of evaluation is impossible to perform by an expert pathologist or other techniques.
Thermally corrected solutions of the one-dimensional wave equation for the laser-induced ultrasound
Authors: Ruiz-Veloz Misael , Martínez-Ponce Geminiano , Fernández-Ayala Rafael I. , Castro-Beltrán Rigoberto , Polo-Parada Luis , Reyes-Ramírez Bartolome , Gutiérrez-Juárez Gerardo
Published: July 2021

When thermal and stress confinement conditions are satisfied, the propagation of laser-induced ultrasound (LIU) is governed by an inhomogeneous wave equation for pressure, and the laser temporal profile can be modeled by a Dirac delta distribution. If these conditions are not fulfilled, the coupled differential equations for temperature and pressure must be solved, considering a laser pulse with finite time-width. Here, an exact solution of the boundary value problem for the 1D-wave equation is obtained in both the frequency domain and the time domain. Since highly absorbent optical materials are out of the validity range of the confinement conditions, these are used as a numerical and experimental model. It is shown that the impulse-response model correctly predicts the time of flight of photoacoustic waves. However, when considering a laser pulse with finite time-width, the resultant theoretical amplitude of the LIU signal decays rapidly to zero, which is not observed in the experiment. To overcome this, we propose a thermal correction on the LIU source, defined typically as the optical penetration length, which imposes a redefinition of stress and thermal confinement in just one statement. Additionally, with the aim of comparing the corrected-theoretical results with the acquired electrical signals, the sensor and the oscilloscope were modeled as an RC circuit in parallel. It was found that the amplitude of the electrical signal was proportional to the difference of the LIU amplitudes at the faces of the sensor. It is demonstrated that even though the sensor impulse response is modeled as a Dirac delta distribution, this difference strongly affects the shape of the LIU electrical signals, hiding relevant information of the acoustic waves.
Development of a dedicated instrumentation for electrical and thermal characterization of chemiresistive gas sensors
Authors: Della Ciana M. , Valt M. , Fabbri B. , Bernardoni P. , Guidi V. , Morandi V.
Published: July 2021

This work presents the design and validation of a measuring instrumentation for an easy, complete, and tunable characterization of chemiresistive gas sensors based on metal-oxide semiconductors. The equipment, described in depth both as hardware and as software, was designed to monitor the electrical behavior of gas sensors in controlled thermodynamic conditions. The main goal of this setup is to synchronize the electrical characterization with different measuring conditions, i.e., operating temperature, relative humidity, and gas target concentration. This operation allows us to automate various measurement protocols, otherwise impossible to obtain manually. In particular, this instrumentation permits to correlate the response of a chemiresistive gas sensor to the applied voltage, to its working temperature, and to the gas concentration, automating the acquisition of the current–voltage characteristic and the current–temperature characteristic (Arrhenius plot) of sensing films. The experimental setup was validated by reporting the electrical characterization of a standard metal-oxide-based gas sensing material, such as SnO2, working under different thermodynamic conditions.
Crowding effects on water-mediated hydrophobic interactions
Authors: Sahu Rahul , Nayar Divya
Published: July 2021

Understanding the fundamental forces such as hydrophobic interactions in a crowded intracellular environment is necessary to comprehensively decipher the mechanisms of protein folding and biomolecular self-assemblies. The widely accepted entropic depletion view of crowding effects primarily attributes biomolecular compaction to the solvent excluded volume effects exerted by the “inert” crowders, neglecting their soft interactions with the biomolecule. In this study, we examine the effects of chemical nature and soft attractive energy of crowders on the water-mediated hydrophobic interaction between two non-polar neopentane solutes using molecular dynamics simulations. The crowded environment is modeled using dipeptides composed of polar and non-polar amino acids of varying sizes. The results show that amongst the non-polar crowders, Leu2 strengthens the hydrophobic interactions significantly, whereas the polar and small-sized non-polar crowders do not show significant strengthening. Distinct underlying thermodynamic driving forces are illustrated where the small-sized crowders drive hydrophobic interaction via a classic entropic depletion effect and the bulky crowders strengthen it by preferential interaction with the solute. A crossover from energy-stabilized solvent-separated pair to entropy-stabilized contact pair state is observed in the case of bulky non-polar (Leu2) and polar (Lys2) crowders. The influence of solute–crowder energy in affecting the dehydration energy penalty is found to be crucial for determining the neopentane association. The findings demonstrate that along with the entropic (size) effects, the energetic effects also play a crucial role in determining hydrophobic association. The results can be extended and have implications in understanding the impact of protein crowding with varying chemistry in modulating the protein free energy landscapes.
Temperature dependence of electronic bands in Al/GaN by utilization of invariant deep defect transition energies
Authors: Kim Ji Hyun , Bagheri Pegah , Washiyama Shun , Klump Andrew , Kirste Ronny , Mita Seiji , Reddy Pramod , Collazo Ramón , Sitar Zlatko
Published: July 2021

We show experimentally that deep point defect levels in GaN, AlN, and AlGaN are constant with respect to the vacuum level and can be used as invariant internal energy references. This offered a convenient and quick way to assess band shifts and impurity levels as a function of temperature via photoluminescence. For AlGaN, we determined that the band shift in the temperature range of 3–600 K occurred primarily in the valence band and that the lowering of the conduction band edge was comparatively small. The valence band shift (as a fraction of the Varshni bandgap shift) in AlGaN varies from ∼70% in AlN to ∼90% in GaN.
Reduction in the contact time of droplet impact on superhydrophobic surface with protrusions
Authors: Xu Yunjie , Tian Linlin , Zhu Chunling , Zhao Ning
Published: July 2021

Previous studies have pointed out that adding a single protrusion on the superhydrophobic surface can effectively reduce the contact time of droplets, which is of practical importance in applications like anti-icing, self-cleaning, and anti-frost. However, the droplet impact dynamics and the mechanism for contact time reduction are still far from completely understood. Therefore, in this paper, via a three-dimensional pseudopotential lattice Boltzmann model coupled with a modified curved boundary scheme (which satisfies mass conservation), the droplet impact dynamics is simulated in a wide range of Weber numbers (0 < We≤ 67.7), protrusion size (10 ≤ W ≤ 30), and protrusion shape (triangle, square, and circle), with particular interest in understanding their effects on the contact time. We demonstrate that the variation of contact time depends on the bouncing type as well as the retraction way. Among three possible bouncing types observed in the simulation, including non-break bouncing, two droplets bouncing, and three droplets bouncing, two droplets bouncing has less contact time and could be facilitated by increasing We and using triangle protrusion. However, with increasing of W or using square protrusion, the bouncing type may change from two droplets bouncing to three droplets bouncing, and the deformation of fragments may become definitely different, leading to a long contact time. In addition, a transition from twice-retraction to once-retraction can be obtained by increasing We or making the protrusion shape sharp. When the fragments resulting from droplet splitting only retract once on the bottom wall, the contact time can be effectively reduced.
Stable phosphor-in-glass realizing ultrahigh luminescence efficiency for high-power laser-driven lighting
Authors: Zhang Jiangdan , Yang Haisheng , Zhang Yujie , Liu Xiaodong , Zhang Yaqian , Liang Yueyuan , Li Huan , Ma Bo , Liang Xiaojuan , Xiang Weidong
Published: July 2021

All inorganic remote Ce3+:Y3Al3.5Ga1.5O12 (Ce:YAGG) phosphor-in-glass (PIG) is considered to be an ideal robust green-emitting light converter for high-quality laser diode applications. Herein, the preparation of Ce:YAGG PIGs using an economical solid state reaction is reported. The sintered composite materials have the advantages of yielding a high transparency of 53% in the visible region and a high internal quantum efficiency of 92.7%. Benefiting from remarkably superior thermal properties, a high thermal conductivity of 1.712 W m−1 K−1 and a high thermal stability that the luminescence intensity could maintain 91.6% at 503 K, and the PIG can withstand 3.49 W/mm2 blue laser radiation. When pumped by blue laser diodes and by controlling the phosphor content and a thickness of samples, the robust PIG materials produce green light with a luminous flux of 555.6 lm and a stable luminous efficiency of 254.5 lm/W as the blue laser density increasing up to 2.78 W/mm2. The above outstanding performance of Ce:YAGG PIGs indicates a strong perspective for future lighting source.
Variationally optimized orbital approach to trions in two-dimensional materials
Authors: Chang Yao-Wen , Chang Yia-Chung
Published: July 2021

In this work, trions in two-dimensional (2D) space are studied by the variational method with trial wavefunctions being constructed by 2D slater-type orbitals. Via this method, trion energy levels and wavefunctions can be calculated efficiently with fairly good accuracy. We first apply this method to study trion energy levels in a 2D hydrogen-like system with respect to a wide range of mass ratios and screening lengths. We find that the ground-state trion is bound for the whole parameter range, and an excited-state trion with antisymmetric permutation of electrons with finite angular momentum is bound for large electron–hole mass ratios or long screening lengths. The binding energies of ground-state trions calculated by the present method agree well with those calculated by more sophisticated but computationally demanding methods. We then calculate trion binding energies in various monolayer transition metal dichalcogenides (TMDCs) by using this method with the inclusion of electron–hole exchange (EHX) interaction. For TMDCs, we found that the effect of EHX can be significant in determining the trion binding energy and the possible existence of stable excited-state trions.
Methods to achieve ultra-high quality factor silicon nitride resonators
Authors: Ji Xingchen , Roberts Samantha , Corato-Zanarella Mateus , Lipson Michal
Published: July 2021

On-chip resonators are promising candidates for applications in a wide range of integrated photonic fields, such as communications, spectroscopy, biosensing, and optical filters, due to their compact size, wavelength selectivity, tunability, and flexible structure. The high quality (Q) factor is a main positive attribute of on-chip resonators that makes it possible for them to provide high sensitivity, narrow bandpass, and low power consumption. In this Tutorial, we discuss methods to achieve ultra-high Q factor on-chip resonators on a silicon nitride (Si3N4) platform. We outline the microfabrication processes, including detailed descriptions and recipes for steps such as deposition, lithography, etch, cladding, and etch facet, and then describe the measurement of the Q factor and methods to improve it. We also discuss how to extract the basic loss limit and determine the contribution of each loss source in the waveguide and resonator. We present a modified model for calculating scattering losses, which successfully relates the measured roughness of the waveguide interface to the overall performance of the device. We conclude with a summary of work done to date with low pressure chemical vapor deposition Si3N4 resonator devices, confinement, cross-sectional dimensions, bend radius, Q factor, and propagation loss.
Drag reduction of a D-shaped bluff-body using linear parameter varying control
Authors: Shaqarin T. , Oswald P. , Noack B. R. , Semaan R.
Published: July 2021

In this work, we report on a closed-loop flow control strategy that consistently reduces the drag of a D-shaped bluff body under variable freestream velocity conditions. The control strategy is guided by open-loop tests with pulsed Coanda blowing at two freestream velocities that yield optimal frequencies (Strouhal number of 0.33 and 1.3), which reduce the drag by up to 40%. The strong correlation between drag coefficient (Cd) and the wake fluctuations is exploited for the feedback signal, where a microphone signal is used to measure the pressure fluctuations at the model base. The results demonstrate the ability to perform accurate and robust H∞-based control for drag reduction using solely the wake pressure fluctuations at the model base as feedback signal. The robust control strategy at constant freestream velocity is shown to improve output stability and enhance performance in terms of settling time, even when employing simple models of the flow response with large uncertainty. Building on that success, an H∞-based linear parameter varying controller is designed and implemented to reduce drag under free stream variations and/or fluctuations. Similarly, the results demonstrate improved robustness and performance enhancements.
Review of Scientific Instruments New Products
Authors: Mandelis Andreas
Published: July 2021

In order to supplement manufacturers’ information, this department will welcome the submission by our readers of brief communications reporting measurements on the physical properties of materials, which supersede earlier data or suggest new research applications.
Unconditional bases in radial Hilbert spaces
Authors: Isaev K. P. , Yulmukhametov R. S.
Published: July 2021

We prove necessary and (separate) sufficient conditions for the existence of unconditional bases of reproducing kernels in abstract radial Hilbert function spaces that are stable under division, in terms of the norms of monomials.
On improved bounds and conditions for the convergence of Markov chains
Authors: Veretennikov A. Yu. , Veretennikova M. A.
Published: July 2021

We continue the work of improving the rate of convergence of ergodic homogeneous Markov chains. The setting is more general than in previous papers: we are able to get rid of the assumption about a common dominating measure and consider the case of inhomogeneous Markov chains as well as more general state spaces. We give examples where the new bound for the rate of convergence is the same as (resp. better than) the classical Markov–Dobrushin inequality.
The optimal start control problem for 2D Boussinesq equations
Authors: Baranovskii E. S.
Published: July 2021

We consider the problem of the optimal start control for two-dimensional Boussinesq equations describing non-isothermal flows of a viscous fluid in a bounded domain. Using the study of the properties of admissible tuples and of the evolution operator, we prove the solubility of the optimization problem under natural assumptions about the model data. We derive a variational inequality which is satisfied by the optimal control provided that the objective functional is determined by the final observation. We also obtain sufficient conditions for the uniqueness of an optimal control.
Weights of exact threshold functions
Authors: Babai L. , Hansen K. A. , Podolskii V. V. , Sun Xiaoming
Published: July 2021

We consider Boolean exact threshold functions defined by linear equations and, more generally, polynomials of degree

. We give upper and lower bounds on the maximum magnitude (absolute value) of the coefficients required to represent such functions. These bounds are very close. In the linear case in particular they are almost matching. This quantity is the same as the maximum magnitude of the integer coefficients of linear equations required to express every possible intersection of a hyperplane in

and the Boolean cube

or, in the general case, intersections of hypersurfaces of degree

in

and

. In the process we construct new families of ill-conditioned matrices. We further stratify the problem (in the linear case) in terms of the dimension

of the affine subspace spanned by the solutions and give upper and lower bounds in this case as well. There is a substantial gap between these bounds, a challenge for future work.
Foundations of Lie theory for -structures and some of its applications
Authors: Gorbatsevich V. V.
Published: July 2021

We construct an analogue of classical Lie theory in the case of Lie groups and Lie algebras defined over the algebra of dual numbers. As an application, we study approximate symmetries of differential equations and construct analogues of Hjelmslev’s natural geometry.
Extremal interpolation with the least value of the norm of the second derivative in
Authors: Shevaldin V. T.
Published: July 2021

In this paper we formulate a general problem of extreme functional interpolation of real-valued functions of one variable (for finite differences, this is the Yanenko–Stechkin–Subbotin problem) in terms of divided differences. The least value of the

-th derivative in

,

, needs to be calculated over the class of functions interpolating any given infinite sequence of real numbers on an arbitrary grid of nodes, infinite in both directions, on the number axis

for the class of interpolated sequences for which the sequence of

-th order divided differences belongs to

. In the present paper this problem is solved in the case when

. The indicated value is estimated from above and below using the greatest and the least step of the grid of nodes.
On the number of epi-, mono- and homomorphisms of groups
Authors: Brusyanskaya E. K. , Klyachko Ant. A.
Published: July 2021

It is well known that the number of homomorphisms from a group

to a group

is divisible by the greatest common divisor of the order of

and the exponent of

. We study the question of what can be said about the number of homomorphisms satisfying certain natural conditions like injectivity or surjectivity. A simple non-trivial consequence of our results is the fact that in any finite group the number of generating pairs

such that

is divisible by the greatest common divisor of fifteen and the order of the group

.
Analytic moduli for parabolic Dulac germs
Authors: Mardešić P. , Resman M.
Published: July 2021

This paper gives moduli of analytic classification for parabolic Dulac germs (that is, almost regular germs). Dulac germs appear as first return maps of hyperbolic polycycles. Their moduli are given by a sequence of Écalle–Voronin-type germs of analytic diffeomorphisms. The result is stated in a broader class of parabolic generalized Dulac germs having power- logarithmic asymptotic expansions.

Bibliography: 23 titles.
Equivariant minimal model program
Authors: Prokhorov Yu. G.
Published: July 2021

The purpose of the survey is to systematize a vast amount of information about the minimal model program for varieties with group actions. We discuss the basic methods of the theory and give sketches of the proofs of some principal results.

Bibliography: 243 titles.
Evaluation of dominance in tropically adapted composite beef cattle
Authors: Facy M. L. , Hebart M. L. , Oakey H. , McEwin R. A. , Popplewell G. I. , Pitchford W. S.
Published: July 2021

Context Significant opportunities have been identified in the northern Australian beef industry that can improve efficiency and profitability by using composite or crossbred cattle and genomic selection. The improved performance of composite cattle is partly due to heterosis. One of the major genetic bases of heterosis is dominance. Traditionally, dominance is ignored in genetic evaluation but could improve the accuracy of breeding values and help maintain genetic diversity. Aims The aim of this study is to describe the impact of including a dominance relationship matrix with different parameterisation methods and including heterozygosity fraction on estimated breeding values for 400-day weight in a composite population. Methods Genotype and phenotype data were obtained from 2364 tropical composite animals and were imputed to 27 648 single nucleotide polymorphisms. Genetic parameters and breeding values were estimated for 400-day weight from a linear mixed model using a genomic relationship matrix, heterozygosity fraction and three different parameterisation methods for the dominance relationship matrix, including genotypic, classical and the natural and orthogonal interaction approach. Genetic parameters and breeding values where compared over the three different parameterisation methods. Key results The heritability for all models when heterozygosity was not fitted ranged from 0.25 to 0.35, with the genotypic dominance model having the lowest additive heritability. Including heterozygosity fraction in the model as a fixed covariate resulted in substantial (39–49%) reductions in dominance variance across all models but a minimal change in the additive variance and, therefore, heritability (0.29–0.35). Conclusions and Implications In a composite population, including heterozygosity fraction in the model was important due to directional dominance. When heterozygosity fraction was not included, the genetic variance was incorrectly partitioned, and the dominance estimates were biased. Including the dominance relationship matrix improved the accuracy of breeding values. Parameterisation methods for forming the dominance relationship matrix are largely a matter of what estimates are required from the models and convenience. The additive values were largely independent of dominance parameterisation when heterozygosity was in the model.
Understanding uptake of community groundwater monitoring in rural Brazil
Authors: Cooperman Alicia , McLarty Alexandra R. , Seim Brigitte
Published: July 2021

Resource monitoring is often cited as important for effective common pool resources management. In practice, not all monitoring interventions are successful, particularly when the resource, such as groundwater, is challenging to monitor and measure. We conducted a field experiment on groundwater monitoring in Ceará, Brazil, where communities are increasingly reliant on groundwater yet do not engage in monitoring. Despite careful implementation, uptake of monitoring within the 80 treatment communities was low. To unpack this low uptake, we conduct multimethods exploratory research. We find that uptake is less likely in communities facing high coordination costs, either within the community leadership or across the broader community. Uptake is also less likely when there are physical barriers to monitoring, when there are more substitutes for groundwater, and when there is lower variability in water availability. Our findings can inform future monitoring interventions in similar contexts worldwide.
Citizen monitoring of waterways decreases pollution in China by supporting government action and oversight
Authors: Buntaine Mark T. , Zhang Bing , Hunnicutt Patrick
Published: July 2021

Significance

Approximately 70% of China’s rivers and lakes are unsafe for human use. Effective implementation of existing pollution standards can improve the health and well-being of people across China. In this randomized trial, pollution decreased when a nongovernmental organization enlisted volunteers to monitor the quality of urban waterways slated for remediation and disseminated that information to local and provincial authorities. Disseminating information to the public through posters did not have detectable effects on water quality. Nongovernmental organizations can support the efforts of authorities to remediate pollution by providing monitoring that guides action and facilitates oversight between different levels of government, particularly when authorities that set remediation targets have an active interest in responding to public complaints and using monitoring for oversight.
Community-based monitoring to facilitate water management by local institutions in Costa Rica
Authors: Bernedo Del Carpio María , Alpizar Francisco , Ferraro Paul J.
Published: July 2021

Significance

Elinor Ostrom won the Nobel Prize in Economics for demonstrating that humans can create rules and institutions that permit sustainable management of shared resources without resorting to privatization or government expropriation. One purported enabling condition for success is monitoring of the shared resource by community members. Whether such monitoring can be encouraged where it is absent, and thereby improve resource management, is not well understood. In a randomized trial, we assessed whether an externally encouraged, community-based monitoring program improved water management. After 1 y, we detect modest reductions in groundwater pumping and modest improvements in water quality and user satisfaction. Although replications are needed, the results imply that externally encouraged, community-based monitoring can improve the management of shared resources.
Volcanically extruded phosphides as an abiotic source of Venusian phosphine
Authors: Truong N. , Lunine J. I.
Published: July 2021

Significance

Published observations suggest small amounts of phosphine in the atmosphere of Venus, and various abiotic mechanisms for its generation have been rejected in the literature, including active volcanism. We reexamine a volcanic source and find it to be sufficient to supply the observed amount of phosphine given that Venus might be subject to episodes of active volcanism and magmas originating deep in the mantle and brought up by plume volcanism.
On design-based empirical research and its interpretation and ethics in sustainability science
Authors: Barrett Christopher B.
Published: July 2021

Generating credible answers to key policy questions is crucial but difficult in most coupled human and natural systems because complex feedback mechanisms can confound identification of the causal mechanisms behind observed phenomena. By using explicit research designs intended to isolate the causal effects of specific interventions on community monitoring of common property resources, and on the well-being of those resources and their human neighbors, the papers in this Special Feature offer an important advance in empirical sustainability science research. Like earlier advances in my own field of development economics, however, they suffer some avoidable interpretive and ethical errors. This essay celebrates the powerful potential of design-based sustainability science studies, much of it admirably reflected in this set of papers, while simultaneously flagging opportunities to improve future work in this tradition.
Telomere dysfunction instigates inflammation in inflammatory bowel disease
Authors: Chakravarti Deepavali , Lee Rumi , Multani Asha S. , Santoni Andrea , Keith Zachery , Hsu Wen-Hao , Chang Kyle , Reyes Laura , Rashid Asif , Wu Chang-Jiun , Li Jun , Zhang Jiexin , Shim Hong Seok , Chandra Krishna , Deng Pingna , Spring Denise J. , Nielsen Ole Haagen , Riis Lene Buhl , Mayigegowda Kavya Kelagere , Blutt Sarah E. , Zhang Jianhua , Younes Mamoun , DuPont Andrew , Thirumurthi Selvi , Vilar Eduardo , Estes Mary K. , Colla Simona , Shroyer Noah F. , DePinho Ronald A.
Published: July 2021

Significance

Inflammatory bowel disease (IBD) is a chronic debilitating condition with limited treatment options. Recently, we found that telomerase reactivation can ameliorate intestinal inflammation in a mouse model of IBD through the regulation of the YAP1/pro-IL-18 axis. This study aims to validate the therapeutic potential of this axis genetically and with the use of small molecule activators and inhibitors in the intestinal epithelium of IBD patients.
Economic evaluation of sea-level rise adaptation strongly influenced by hydrodynamic feedbacks
Authors: Hummel Michelle A. , Griffin Robert , Arkema Katie , Guerry Anne D.
Published: July 2021

Significance

As sea levels rise, coastal cities will rely on shoreline protection strategies such as levees and seawalls to mitigate flooding. Although these strategies provide local flood-reduction benefits, they can increase inundation along other shorelines within the same estuary or bay. Using hydrodynamic and economic models, we quantify previously unmeasured regional economic damages (up to $723 million per flood event) that result from the protection of individual shoreline segments in San Francisco Bay, CA. We also highlight and quantify opportunities to alleviate regional flood damage through strategic floodwater storage in low-lying areas. Integrating the findings into coordinated planning efforts that account for the regional impacts of local shoreline actions could provide opportunities to reduce shared risk in coastal regions globally.
Small-molecule modulators of INAVA cytosolic condensate and cell–cell junction assemblies
Authors: Chang Denis , Luong Phi , Li Qian , LeBarron Jamie , Anderson Michael , Barrett Lee , Lencer Wayne I.
Published: July 2021

Epithelial cells lining mucosal surfaces distinctively express the inflammatory bowel disease risk gene INAVA. We previously found that INAVA has dual and competing functions: one at lateral membranes where it affects mucosal barrier function and the other in the cytosol where INAVA enhances IL-1β signal transduction and protein ubiquitination and forms puncta. We now find that IL-1β–induced INAVA puncta are biomolecular condensates that rapidly assemble and physiologically resolve. The condensates contain ubiquitin and the E3 ligase βTrCP2, and their formation correlates with amplified ubiquitination, suggesting function in regulation of cellular proteostasis. Accordingly, a small-molecule screen identified ROS inducers, proteasome inhibitors, and inhibitors of the protein folding chaperone HSP90 as potent agonists for INAVA condensate formation. Notably, inhibitors of the p38α and mTOR pathways enhanced resolution of the condensates, and inhibitors of the Rho–ROCK pathway induced INAVA’s competing function by recruiting INAVA to newly assembled intercellular junctions in cells where none existed before.
Low-energy spin dynamics in rare-earth perovskite oxides
Authors: Podlesnyak A , Nikitin S E , Ehlers G
Published: July 2021

We review recent studies of spin dynamics in rare-earth orthorhombic perovskite oxides of the type RMO3, where R is a rare-earth ion and M is a transition-metal ion, using single-crystal inelastic neutron scattering (INS). After a short introduction to the magnetic INS technique in general, the results of INS experiments on both transition-metal and rare-earth subsystems for four selected compounds (YbFeO3, TmFeO3, YFeO3, YbAlO3) are presented. We show that the spectrum of magnetic excitations consists of two types of collective modes that are well separated in energy: gapped magnons with a typical bandwidth of <70 meV, associated with the antiferromagnetically (AFM) ordered transition-metal subsystem, and AFM fluctuations of <5 meV within the rare-earth subsystem, with no hybridization of those modes. We discuss the high-energy conventional magnon excitations of the 3d subsystem only briefly, and focus in more detail on the spectacular dynamics of the rare-earth sublattice in these materials. We observe that the nature of the ground state and the low-energy excitation strongly depends on the identity of the rare-earth ion. In the case of non-Kramers ions, the low-symmetry crystal field completely eliminates the degeneracy of the multiplet state, creating a rich magnetic field-temperature phase diagram. In the case of Kramers ions, the resulting ground state is at least a doublet, which can be viewed as an effective quantum spin-1/2. Equally important is the fact that in Yb-based materials the nearest-neighbor exchange interaction dominates in one direction, despite the three-dimensional nature of the orthoperovskite crystal structure. The observation of a fractional spinon continuum and quantum criticality in YbAlO3 demonstrates that Kramers rare-earth based magnets can provide realizations of various aspects of quantum low-dimensional physics.
Detangling the multilayer structure from an aggregated network
Authors: Zhang Aobo , Zeng An , Fan Ying , Di Zengru
Published: July 2021

Multiplex interactions are common and essential in real-world systems. In many cases, we can only obtain aggregated networks without detailed information regarding the type of links contained within. Such single-layer networks oversimplify the structural information and lead to misunderstandings of some properties of real systems. In this context, network splitting which aims to correctly separate an aggregated network into multilayer networks, is a meaningful problem to address. To this end, we propose a simulated-annealing-like algorithm based on the link clustering coefficient. We verify the validity of this algorithm with several synthetic networks. Inter-similarities of layers are also taken into consideration, and we can find that the proposed method is valid even if there is a certain proportion of overlapping links between layers. Finally, we apply the algorithm to real international trading networks, which results in accurate splits of different layers.
Generation of isolated soft x-ray attosecond pulses with mid-infrared driving lasers via transient phase-matching gating
Authors: Li Baochang , Wang Kan , Tang Xiangyu , Chen Yanbo , Lin C D , Jin Cheng
Published: July 2021

Isolated attosecond pulses (IAPs) in the soft x-ray (SXR) region are highly desirable for attosecond time-resolved experiments. Here we identify a transient phase matching gating method for the generation of such IAPs with mid-infrared (MIR) lasers. This gating method works when a loosely focused, long-duration MIR Gaussian driving beam is slightly reshaped during its propagation in the gas medium under the ‘critical’ ionization condition. Quantitatively, the calculated coherence length of high harmonic is used to analyze the mechanism of the gating method, by using one-dimensional plane-wave beams and by comparing 2000 nm and 800 nm lasers. The robustness of the generation method is checked by varying laser’s carrier-envelope-phase and gas pressure. This gating method provides with an alternative route to efficiently produce tabletop ultrashort attosecond SXR light sources with the emerging MIR lasers.
Radiation effects of 50-MeV protons on PNP bipolar junction transistors
Authors: Huang Yuan-Ting , Cui Xiu-Hai , Yang Jian-Qun , Ying Tao , Yu Xue-Qiang , Dong Lei , Li Wei-Qi , Li Xing-Ji
Published: July 2021

The effects of radiation on 3CG110 PNP bipolar junction transistors (BJTs) are characterized using 50-MeV protons, 40-MeV Si ions, and 1-MeV electrons. In this paper, electrical characteristics and deep level transient spectroscopy (DLTS) are utilized to analyze radiation defects induced by ionization and displacement damage. The experimental results show a degradation of the current gain and an increase in the types of radiation defect with increasing fluences of 50-MeV protons. Moreover, by comparing the types of damage caused by different radiation sources, the characteristics of the radiation defects induced by irradiation show that 50-MeV proton irradiation can produce both ionization and displacement defects in the 3CG110 PNP BJTs, in contrast to 40-MeV Si ions, which mainly generate displacement defects, and 1-MeV electrons, which mainly produce ionization defects. This work provides direct evidence of a synergistic effect between the ionization and displacement defects caused in PNP BJTs by 50-MeV protons.
M1 transition energy and rate in the ground configuration of Ag-like ions with 62 ⩽ Z ⩽ 94
Authors: Meng Ju , Li Wen-Xian , Li Ji-Guang , Wu Ze-Qing , Yan Jun , Wu Yong , Wang Jian-Guo
Published: July 2021

Systematic calculations and assessments are performed for the magnetic dipole (M1) transition energies and rates between the

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levels in the ground configuration 4d104f along the Ag-like isoelectronic sequence with 62 ⩽ Z ⩽ 94 based on the second-order many-body perturbation theory implemented in the Flexible Atomic Code. The electron correlations, Breit interaction and quantum electrodynamics effects are taken into account in the present calculations. The accuracy and reliability of our results are evaluated through comprehensive comparisons with available measurements and other theoretical results. For transition energies, our results are in good agreement with the recent experimental data obtained from the electron beam ion traps within 0.18%. The maximum discrepancy between our results and those obtained with the large-scale multiconfiguration Dirac–Hartee–Fock calculations by Grumer et al. [Phys. Rev. A
89 062501 (2014)] is less than 0.13% along the isoelectronic sequence. Furthermore, the corresponding M1 transition rates are also reported. The present results can be used as the benchmark and useful for spectra simulation and diagnostics of astrophysical and fusion plasmas.
SnO2/Co3O4 nanofibers using double jets electrospinning as low operating temperature gas sensor
Authors: Wang Zhao , Fan Shu-Xing , Tang Wei
Published: July 2021

SnO2/Co3O4 nanofibers (NFs) are synthesized by using a homopolar electrospinning system with double jets of positive polarity electric fields. The morphology and structure of SnO2/Co3O4 hetero-nanofibers are characterized by using field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectrometer (XPS). The analyses of SnO2/Co3O4 NFs by EDS and HRTEM show that the cobalt and tin exist on one nanofiber, which is related to the homopolar electrospinning and the crystallization during sintering. As a typical n-type semiconductor, SnO2 has the disadvantages of high optimal operating temperature and poor reproducibility. Comparing with SnO2, the optimal operating temperature of SnO2/Co3O4 NFs is reduced from 350°C to 250°C, which may be related to the catalysis of Co3O4. The response of SnO2/Co3O4 to 100-ppm ethanol at 250°C is 50.9, 9 times higher than that of pure SnO2, which may be attributed to the p–n heterojunction between the n-type SnO2 crystalline grain and the p-type Co3O4 crystalline grain. The nanoscale p–n heterojunction promotes the electron migration and forms an interface barrier. The synergy effects between SnO2 and Co3O4, the crystalline grain p–n heterojunction, the existence of nanofibers and the large specific surface area all jointly contribute to the improved gas sensing performance.
Electronic and magnetic properties of single vacancy graphene with hydrogen adsorptions analyzed using density functional theory method
Authors: Septya Maya Mahirotul , Asih Retno , Arifin Rizal , Darminto
Published: July 2021

Graphene has become an exciting material to be studied because of its unique properties. One of the interesting phenomena is the change of its electronic and magnetic properties due to impurities adsorption. By using the spin-polarized density functional theory (DFT) method, we simulate single vacancy graphene with the adsorption of hydrogen atoms around the dangling bond to determine the electronic and magnetic properties of the material. In this study, we use a 4×4×1 supercell of single-layered graphene. We have four models, i.e., single vacancy graphene, and graphene with hydrogen adsorption in the dangling bond site with the atom’s variation number (H = 1, 2, 3 atoms). Our results show that the modifications of graphene in the form of single vacancy and hydrogen adsorptions makes the graphene material metal, except for the SV+2H model which shows a semiconductor characteristic. The presence of a single vacancy affects the magnetic moment of the modeled graphene layer. A single vacancy on the modeled graphene layer results in a total magnetic moment of 0.69 µB/cell. In the single vacancy graphene with three hydrogen atoms adsorption, we acquire the total magnetic moment of 0.15 µB/cell. This study shows that defects in the forms of vacancies and adsorption of hydrogen atoms can initiate magnetism on graphene. These results open a way of using graphene to create nanomagnetic devices.
Effect of ultrasonic treatment on the preparation of zirconia pillared bentonite as a catalyst
Authors: Agustian E , Rachmawati A , Purba N D E , Rinaldi N , Juwono A L
Published: July 2021

Bentonite is material from soil and has unique properties. Because of these properties, bentonite has been exploited widely for different utilization. Bentonite has a simple structure that collapses at elevated temperatures. Then, it was required to prepare zirconia to be pillared with high surface area and particular active site. Ultrasonic treatment was an alternative technology for preparation of zirconia pillared bentonite. Modified of structure and surface active site with variable condition ultrasonic on power output (30%, 50%, 70%) with 20 kHz and 20 minutes preparation of zirconia pillared bentonite were studied using by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), chemisorption and Nitrogen gas sorption technique. The results were confirmed that the presence of polycation zirconium under ultrasonic indicated an increase in the basal spacing from 14.93 Å to 19.42 Å and 10 times increase of specific surface area from 25.150 m2/g to 265.076 m2/g. It was confirmed that ultrasonic treatment with three type variations caused significant change in the structure of bentonite and obtained the highest increase in surface area. Activity of catalytic provided an effective and efficient conversion on the esterification reaction. Finally, it was found that the higher power output ultrasonic treatment at 70% of power output resulted in partial damage of the pillar bentonite.
Synthesis of Pseudobrookite Fe2-xAlxTiO5 (0 ≤ x ≤ 0.5) Powders
Authors: Irhamsyah A. , Lusiana L. , Wannapaiboon S. , Baqiya MA. , Pratapa S.
Published: July 2021

Synthesis of Fe2-xAlxTiO5 (0≤x≤0.5) powders has been successfully conducted by using the solid state reaction method. The powders were made by mixing the ironstone-derived Fe2O3 and commercial TiO2 powder. Meanwhile, a commercial Al (NO3)3.9H2O precursor was used as the source of Al. The Fe2O3, TiO2, and Al(NO3)3.9H2O powders at the designated composition were mixed and then ground for 5 hours at 330 rpm in a planetary ball mill. Subsequently, the powder mixtures were calcined at 1100 °C for 1 h. Synchrotron x-ray diffractometry (SXRD) and scanning electron microscopy (SEM) techniques were used to characterize the phases and microstructures. SXRD data showed that a single-phase pseudobrookite Fe2TiO5 formed for all samples. A further quantitative analysis showed that the lattice parameter and cell volume values decreased with the increase of x which indicated the success of Al doping in the Fe2TiO5 structure. The morphology of Fe2-xAlxTiO5 grains from SEM images revealed an oval and elongated shapes, in accordance with the crystal structure of the phase.