bluuebunny/crossref_metadata_2025 huggingface dataset:
The principle of minimum pressure gradient: An alternative basis for physics-informed learning of incompressible fluid mechanics
Authors: Alhussein H. , Daqaq M.
Published: April 2024

Recent advances in the application of physics-informed learning in the field of fluid mechanics have been predominantly grounded in the Newtonian framework, primarily leveraging Navier–Stokes equations or one of their various derivatives to train a neural network. Here, we propose an alternative approach based on variational methods. The proposed approach uses the principle of minimum pressure gradient combined with the continuity constraint to train a neural network and predict the flow field in incompressible fluids. We describe the underlying principles of the proposed approach, then use a demonstrative example to illustrate its implementation, and show that it reduces the computational time per training epoch when compared to the conventional approach.
High-pressure structures of solid hydrogen: Insights from ab initio molecular dynamics simulations
Authors: Li Cong
Published: April 2024

Understanding the structural behavior of solid hydrogen under high pressures is crucial for uncovering its unique properties and potential applications. In this study, starting from the phase I of solid hydrogen—free-rotator hcp structure, we conduct extensive ab initio molecular dynamics calculations to simulate the cooling, heating, and equilibrium processes within a pressure range of 80–260 GPa. Without relying on any structure previously predicted, we identify the high-pressure phase structures of solid hydrogen as P21/c for phase II, P6522 for phase III, and BG1BG2BG3 six-layer structure for phase IV, which are different from those proposed previously using the structure-search method. The reasonability of these structures are validated by Raman spectra and x-ray diffraction patterns by comparison with the experimental results. Our results actually show pronounced changes in the c/a ratio between phases I, III, and IV, which hold no brief for the experimental interpretation of an isostructural hcp transformations for phases I–III–IV.
Robust multi-band acoustic router by hybridizing distinct topological phases
Authors: Hu Yang , Zhang Zhiwang , Cheng Ying , Liu Xiaojun
Published: April 2024

The acoustic router, capable of guiding sound waves along specific paths, holds a significant value in both science and engineering. Compared to traditional methods of implementing acoustic routing, the recently developed concept of topological acoustics, with its nontrivial topological phases, offers the potential to achieve a robust acoustic routing device. However, current investigations primarily focus on individual topological phases within a single bandgap, thereby limiting the exploration of diverse topological phases in multiple bandgaps and their hybridizations. In this study, we utilize topological acoustics to construct a robust dual-band acoustic router, which is challenging to achieve with traditional acoustics. By calculating Chern and valley topological phases in different bands, we reveal the competitive relations between different topological phases in a specific bandgap. Furthermore, by modifying the boundary meta-atoms, we have increased the operational frequency bands and proposed a triple-band acoustic router.
Identification of superior genotypes for leaf architecture traits in Sorghum bicolor through GGE biplot analysis
Authors: Wang Runfeng , Zhao Yingxing , Wang Hailian , Chen Erying , Li Feifei , Huang Shaoming , Qin Ling , Yang Yanbing , Guan Yan’an , Liu Bin , Zhang Huawen
Published: April 2024

Context Well-organised leaf architecture produces compact canopies and allows for greater sunlight penetration, higher photosynthetic rates, and thus greater yields. Breeding for enhanced leaf architecture of sorghum (Sorghum bicolor L.), a key food source in semi-arid regions, benefits its overall production. Aims The study focuses on selecting useful genotypes with excellent leaf architecture for grain sorghum improvement. Methods In total, 185 sorghum genotypes were subjected to multi-environment trials. Leaf flagging-point length, leaf length, leaf width, leaf angle and leaf orientation value (LOV) were characterised under field conditions. Genotype + genotype × environment interaction (GGE) biplot analysis was used to identify the most stable genotypes with the highest LOV. Key results Statistical analysis showed significant effects of genotype × environment interaction (P < 0.001), and high broad-sense heritability for the traits. Correlation analysis demonstrated negative correlations (P < 0.001) between LOV and its components. Singular value decomposition of LOVs in the first two principal components explained 89.19% of the total variation. GGE biplot analysis identified G55 as the ideotype with the highest and most stable LOV. Conclusions Leaf architecture optimisation should be given greater attention. This study has identified a genotype with optimal and stable leaf architecture, laying the foundation for improvement in breeding to increase overall yields of sorghum. Implications Genotype G55 can be utilised as a parent with other parents that display economically important characteristics in breeding programs to produce offspring that can be planted densely to increase population yields. Genotypes identified with loose leaf architecture are useful in dissecting genes controlling leaf architecture by crossing with G55 to construct genetic mapping populations.
The roles of non-structural carbohydrates in fruiting: a review focusing on mango (Mangifera indica)
Authors: Rossouw Gerhard C. , Orr Ryan , Bennett Dale , Bally Ian S. E.
Published: April 2024

Reproductive development of fruiting trees, including mango (Mangifera indica L.), is limited by non-structural carbohydrates. Competition for sugars increases with cropping, and consequently, vegetative growth and replenishment of starch reserves may reduce with high yields, resulting in interannual production variability. While the effect of crop load on photosynthesis and the distribution of starch within the mango tree has been studied, the contribution of starch and sugars to different phases of reproductive development requires attention. This review focuses on mango and examines the roles of non-structural carbohydrates in fruiting trees to clarify the repercussions of crop load on reproductive development. Starch buffers the plant’s carbon availability to regulate supply with demand, while sugars provide a direct resource for carbon translocation. Sugar signalling and interactions with phytohormones play a crucial role in flowering, fruit set, growth, ripening and retention, as well as regulating starch, sugar and secondary metabolites in fruit. The balance between the leaf and fruit biomass affects the availability and contributions of starch and sugars to fruiting. Crop load impacts photosynthesis and interactions between sources and sinks. As a result, the onset and rate of reproductive processes are affected, with repercussions for fruit size, composition, and the inter-annual bearing pattern.
Widespread, bipartisan aversion exists to neighbors owning AR-15s or storing guns insecurely
Authors: Sola Justin L. , Pickett Justin T.
Published: April 2024

Over 45,000 gun deaths occur annually in the United States, a country with more than 100 million gun owners and more than 350 million guns. Nevertheless, passing legislation to reduce gun violence is difficult because the issue is intensely polarized. Polls asking about general gun policies (e.g., AR-15 restrictions) demonstrate that, at least in the abstract, Americans disagree vehemently about whether civilians should be able to keep and bear arms. It is possible, however, that a hidden consensus exists in America, which has thus far escaped attention—specifically, that when the focus is on their immediate environments and daily lives, even traditionally pro-gun groups may exhibit aversion to certain types of gun ownership and storage practices. To test this, we conducted two preregistered survey experiments with a large national sample. The first was a conjoint analysis where respondents chose between neighbors (n = 33,596 choices) who randomly varied on seven attributes, including gun ownership (none, pistol, AR-15). No group of respondents, not even traditionally pro-gun groups (e.g., Republicans), exhibited a significant preference for living near gun owners, and every group was averse to AR-15-owning neighbors. The second experiment, per debates about safe-storage laws, was a picture-based factorial vignette that randomized a neighbor’s gun storage practices (n = 2,098). Every group of respondents was averse to interacting with a neighbor who stored guns outside of a locked safe. Our findings demonstrate that there is widespread agreement that certain types of gun ownership and storage practices are undesirable for communities.
Grow now, pay later: When should a bacterium go into debt?
Authors: Lopez Jaime G. , Hein Yaïr , Erez Amir
Published: April 2024

Microbes grow in a wide variety of environments and must balance growth and stress resistance. Despite the prevalence of such trade-offs, understanding of their role in nonsteady environments is limited. In this study, we introduce a mathematical model of “growth debt,” where microbes grow rapidly initially, paying later with slower growth or heightened mortality. We first compare our model to a classical chemostat experiment, validating our proposed dynamics and quantifyingEscherichia coli’s stress resistance dynamics. Extending the chemostat theory to include serial-dilution cultures, we derive phase diagrams for the persistence of “debtor” microbes. We find that debtors cannot coexist with nondebtors if “payment” is increased mortality but can coexist if it lowers enzyme affinity. Surprisingly, weak noise considerably extends the persistence of resistance elements, pertinent for antibiotic resistance management. Our microbial debt theory, broadly applicable across many environments, bridges the gap between chemostat and serial dilution systems.
Genetic mechanism regulating diversity in the placement of eyes on the head of animals
Authors: Puli Oorvashi Roy , Gogia Neha , Chimata Anuradha Venkatakrishnan , Yorimitsu Takeshi , Nakagoshi Hideki , Kango-Singh Madhuri , Singh Amit
Published: April 2024

Despite the conservation of genetic machinery involved in eye development, there is a strong diversity in the placement of eyes on the head of animals. Morphogen gradients of signaling molecules are vital to patterning cues. During
Drosophila
eye development, Wingless (Wg), a ligand of Wnt/Wg signaling, is expressed anterolaterally to form a morphogen gradient to determine the eye- versus head-specific cell fate. The underlying mechanisms that regulate this process are yet to be fully understood. We characterized
defective proventriculus (dve)
(
Drosophila
ortholog of human SATB1), a K50 homeodomain transcription factor, as a dorsal eye gene, which regulates Wg signaling to determine eye versus head fate. Across
Drosophila
species, Dve is expressed in the dorsal head vertex region where it regulates
wg
transcription. Second, Dve suppresses eye fate by down-regulating retinal determination genes. Third, the
dve
-expressing dorsal head vertex region is important for Wg-mediated inhibition of retinal cell fate, as eliminating the Dve-expressing cells or preventing Wg transport from these
dve
-expressing cells leads to a dramatic expansion of the eye field. Together, these findings suggest that Dve regulates Wg expression in the dorsal head vertex, which is critical for determining eye versus head fate. Gain-of-function of SATB1 exhibits an eye fate suppression phenotype similar to Dve. Our data demonstrate a conserved role for Dve/SATB1 in the positioning of eyes on the head and the interocular distance by regulating Wg. This study provides evidence that dysregulation of the Wg morphogen gradient results in developmental defects such as hypertelorism in humans where disproportionate interocular distance and facial anomalies are reported.
Theoretical considerations and empirical predictions of the pharmaco- and population dynamics of heteroresistance
Authors: Levin Bruce R. , Berryhill Brandon A. , Gil-Gil Teresa , Manuel Joshua A. , Smith Andrew P. , Choby Jacob E. , Andersson Dan I. , Weiss David S. , Baquero Fernando
Published: April 2024

Antibiotics are considered one of the most important contributions to clinical medicine in the last century. Due to the use and overuse of these drugs, there have been increasing frequencies of infections with resistant pathogens. One form of resistance, heteroresistance, is particularly problematic; pathogens appear sensitive to a drug by common susceptibility tests. However, upon exposure to the antibiotic, resistance rapidly ascends, and treatment fails. To quantitatively explore the processes contributing to the emergence and ascent of resistance during treatment and the waning of resistance following cessation of treatment, we develop two distinct mathematical and computer-simulation models of heteroresistance. In our analysis of the properties of these models, we consider the factors that determine the response to antibiotic-mediated selection. In one model, heteroresistance is progressive, with each resistant state sequentially generating a higher resistance level. In the other model, heteroresistance is non-progressive, with a susceptible population directly generating populations with different resistance levels. The conditions where resistance will ascend in the progressive model are narrower than those of the non-progressive model. The rates of reversion from the resistant to the sensitive states are critically dependent on the transition rates and the fitness cost of resistance. Our results demonstrate that the standard test used to identify heteroresistance is insufficient. The predictions of our models are consistent with empirical results. Our results demand a reevaluation of the definition and criteria employed to identify heteroresistance. We recommend that the definition of heteroresistance should include a consideration of the rate of return to susceptibility.
Rubber-glass nanocomposites fabricated using mixed emulsions
Authors: Chen Zheqi , Zhang Guogao , Luo Yingwu , Suo Zhigang
Published: April 2024

Many composites consist of matrices of elastomers and nanoparticles of stiff materials. Such composites often have superior properties and are widely used. Embedding elastomers with nanoparticles commonly necessitates intense shear, using machines like extruders and roll millers, which cut polymer chains and degrade properties. Here, we prepare a rubber-glass nanocomposite by using two aqueous emulsions. Each emulsion is separately prepared with a single species of polymer chains. Each polymer chain is copolymerized with a small amount of silane coupling agent. Upon mixing the two emulsions, as water evaporates, the glassy particles retain the shape, and the rubbery particles change shape to form a continuous matrix. Subsequently, the silane coupling agent condensates, which cross-links the rubbery chains and interlinks the rubbery chains to the glassy particles. The cross-links and interlinks stabilize the nanostructure and lead to superior properties. The nanocomposite simultaneously achieves high modulus (~30 MPa), high toughness (~100 kJ m
−2
), and high fatigue threshold (~1,000 J m
−2
). The method of mixed emulsion is environmentally friendly and compatible with various open-air manufacturing processes, such as coat, cast, spray, print, and brush. Additionally, the silane coupling agent can interlink the nanocomposite to other materials. The method of mixed emulsion can be used to fabricate objects of complex shapes, fine features, and prescribed spatial variations of compositions.
Bordering and crisis narratives to illiberal ends
Authors: Szalai Andras
Published: April 2024

This paper draws lessons from security and populism studies to theorize how radical right-wing populism (RRWP)
utilizes borders as a symbolic resource in crisis narratives to clearly frame an “Us” and a threatening “Them”. By analyzing the
Hungarian Orbán regime’s evolving rhetoric on borders, the paper illustrates how populists employ crisis narratives not to
mitigate, but exacerbate ontological insecurities, and thereby facilitate de-democratization by (re)shaping voter attitudes (cf.
Homolar & Scholz 2019; Steele & Homolar
2019). The paper suggests that populists-in-power rely on crisis and bordering narratives beyond voter mobilization:
such narratives are in fact designed to legitimize and affirm illiberal practices that undermine liberal democracy itself, and
contribute to regime building. Border crises, and crisis politics, hence become a template for the manipulation of individuals’
security-of-being, and thereby a tool in the politics of reassurance and control at the broader, societal level.
From war to crime rhetoric
Authors: D’Ottone Silvana , Varela Micaela , Castro Diego , Carvacho Héctor
Published: April 2024

In October 2019, Chile witnessed an unprecedented social uprising, with millions of citizens rising against social
inequalities and injustice. The government employed various strategies to end demonstrations, including the speeches delivered by
President Piñera. This study aims to explore the representation of protests and their actors in the presidential discourse and how
it evolved over the course of events. Our analysis of themes, discursive actions, and attitudinal appraisals, coupled with a
temporal framework, reveals that the initial framing of the uprising as a war shifted to crime rhetoric, possibly in response to
negative reactions from the audience. Despite the President adopting a seemingly softer rhetoric later on, our study suggests that
violence and division remained prominent themes in his speeches. Examining discourse shifts and fluctuations throughout the
timeline of the social upheaval provides a comprehensive understanding of how political discourse is shaped in the midst of an
unparalleled social uprising
The links between evidentiality, modality, and grammaticalization
Authors: Mélac Eric
Published: April 2024

This paper introduces the main notions that are addressed in this special issue, namely evidentiality, modality,
and grammaticalization. It defines each notion and briefly synthesizes the literature. It also presents some of the controversies
which surround the ideas that prevail in these research fields. Crosslinguistic examples illustrate the main evidential and modal
categories, and clarify why the two domains are both distinct and related. The paper then sketches the main pathways of
grammaticalization of modal and evidential markers as they have been documented in typological work. Finally, it introduces the
contributions to this special issue, highlights the new insights, and discusses what remains to be investigated on the links
between evidentiality, modality, and grammaticalization.
Cytorhabdovirus lactucanecante
Authors: CABI  , EPPO
Published: April 2024

A new distribution map is provided for Cytorhabdovirus lactucanecante Rhabdoviridae: Cytorhabdovirus Host: lettuce (
Lactuca sativa
).
Grapevine virus A
Authors: CABI  , EPPO
Published: April 2024

A new distribution map is provided for Grapevine virus A Betaflexiviridae: Vitivirus Host: grapevine (
Vitis spp
.)
Ibipora lolii (Siviour) Siviour & McLeod
Authors: CABI  , EPPO
Published: April 2024

A new distribution map is provided for Ibipora lolii (Siviour) Siviour & McLeodNematoda: Belonolaimidae Hosts: turfgrasses especially kikuyu grass (
Pennisetum clandestinum
)
Ralstonia syzygii subsp. indonesiensis Safni et al.
Authors: CABI  , EPPO
Published: April 2024

A new distribution map is provided for Ralstonia syzygii subsp. indonesiensis Safni et al. Betaproteobacteria: Burkholderiales: Burkholderiaceae Host: Solanaceae.
Raspberry leaf mottle virus
Authors: CABI  , EPPO
Published: April 2024

A new distribution map is provided for Raspberry leaf mottle virus Closteroviridae: Closterovirus Host: Rubus spp.
Venturia asperata Samuels & Sivan.
Authors: CABI  , EPPO
Published: April 2024

A new distribution map is provided for Venturia asperata Samuels & Sivan. Dothideomycetes: Venturiales: Venturiaceae Host: apple (
Malus spp
.)
Strong nonlinear-polarization in ZnMgO epitaxial thin-films with Li incorporation
Authors: Meng Lei , Chai Hongyu , Gao Junjie , Lv Zunren , Yang Xiaoguang , Liu Wenkai , Zhai Tianrui , Yang Tao
Published: April 2024

The second-order nonlinear-polarization originated from the interaction between thin-film materials with second-order nonlinear susceptibility (χ
(2)) and high-power laser is essential for integrated optics and photonics. In this work, strong second-order nonlinear-polarization was found in a-axis oriented Zn1-x
Mg
x
O (ZnMgO) epitaxial thin-films with Li incorporation, which were deposited by radio-frequency magnetron sputtering. Mg incorporation (x > 0.3) causes a sharp fall in the matrix element χ
33 of χ
(2) tensor, although it widens optical bandgap (E
opt). In contrast, moderate Li incorporation significantly improves χ
33 and resistance to high-power laser pulses with a little influence on E
opt. In particular, a Zn0.67Mg0.33O:Li [Li/(Zn + Mg + Li) = 0.07] thin-film shows a |χ
33| of 36.1 pm V−1 under a peak power density (E
p) of 81.2 GW cm−2, a resistance to laser pulses with E
p of up to 124.9 GW cm−2, and an E
opt of 3.95 eV. Compared to that of ZnO, these parameters increase by 37.8%, 53.4%, and 18.6%, respectively. Specially, the Zn0.67Mg0.33O:Li shows higher radiation resistance than a Mg-doped LiNbO3 crystal with a comparable E
opt. First-principle calculations reveal the Li occupation at octahedral interstitial sites of wurtzite ZnO enhances radiation resistance by improving structural stability. X-ray photoelectron spectroscopy characterizations suggest moderate Li incorporation increases χ
33 via enhancing electronic polarization. These findings uncover the close relationship between the octahedra interstitial defects in wurtzite ZnMgO and its nonlinear-polarization behavior under the optical frequency electric field of high-power laser.
The mechanism of EP/SiC coating modulated DC flashover characteristics of epoxy composites in SF6/N2 mixtures
Authors: Li Zhen , Gao He , Mao Zirui , Zhu Bo , Sun Lei , Bi Xuefei , Zhu Yuanwei , Han Yongsen , Min Daomin , Liu Ji , Li Shengtao
Published: April 2024

Surface flashover is an inevitable insulation issue for basin-type insulators in gas-insulated switchgears/lines, which significantly challenges the reliability of the electrical power systems. Previous studies have indicated that polymer/semiconductor-filler composite coatings effectively improve the insulation properties; however, the influence mechanism of the coating materials on flashover has not been demonstrated from a molecular perspective. In this work, epoxy/silicon-carbide (EP/SiC) composites were coated onto an EP substrate. The energy-level structure, surface trap, surface charging, and DC flashover voltage in SF6/N2 were calculated and characterized, and the process by which the tailored molecular energy level influences surface charge transport and flashover characteristics was elucidated. The incorporating of SiC particles reduced the width of the bandgap and introduced shallow traps, which improved carrier mobility and surface conductivity. Quantitative analysis of charge transport indicated that the improved carrier mobility and reduced surface trap level accelerated the surface charge dissipation. This reduced the tangential electrical field distortion and surface charge density and further impeded gas ionization. When the SiC concentration was 15 wt%, the flashover performance improved by 20.88%. This study describes the mechanism by which the EP/SiC coating regulates the surface charge distribution to improve the surface flashover performance by establishing a relationship among the microscopic molecular energy-level structures, mesoscopic charge transport, and macroscopic discharge phenomena.
Enantioselectivity from inelastic electron tunnelling through a chiral sensor
Authors: Pandey Nidhi , Samal Ashutosh , Saha Archishman , Ganguly Swaroop
Published: April 2024

The vibration theory of olfaction, which explains it as the sensing of odorant molecules by their vibrational energies through inelastic electron tunnelling spectroscopy (IETS) has inspired olfactory sensor ideas. However, this theory has been presumed inadequate to explain the difference in smell between enantiomers (chiral molecules, which are mirror images of each other), since these have identical vibrational spectra. Going beyond phenomenological assumptions of enantioselective tunnelling, we show on the basis of ab initio modelling of real chiral molecules, that this drawback is indeed obviated for IETS-based olfactory sensors if they are chiral. Our treatment unifies IETS with chirality induced spin selectivity, which explains that charge polarization in chiral molecules by accompanied by spin polarization. First, we apply ab initio symmetry adapted perturbation theory to explain and illustrate enantioselective coupling of chiral odorant molecules and chiral olfactory sensors. This naturally leads to enantioselective coupling of the vibrational mode of an odorant to electron transport (electron-vibron coupling) in an IETS-based sensor when both odorant and sensor are chiral. Finally, we show, from phenomenological quantum transport calculations, that that in turn results in enantioselective IET spectra. Thus, we have demonstrated the feasibility of enantioselective sensing within a vibration framework. Our work also limns the possibility of quantum biomimetic electronic nose sensors that are enantioselective, a feature which could open up new sensing applications.
Grain boundary diffusion mechanism in Dy-diffused Nd–Fe–B sintered magnets
Authors: Dai Zhiming , Li Kai , Wang Zhenhua , Wang Tingting , Liu Wei , Zhang Zhidong
Published: April 2024

Grain boundary diffusion (GBD) is an effective method to enhance the thermal stability of Nd–Fe–B based permanent magnets. When developing a high-performance magnet, it is essential to carry out a study on its mechanisms, in order to reveal the distribution regulation of diffusion solutes and microstructural evolution. In the present work, the phase-field method is applied to investigate the thermodynamic features and the heavy rare-earth Dy migration in a Dy-diffused Nd–Fe–B magnet during the GBD process. In the simulation process, the grain phase transformation and volume diffusion were taken into consideration and the effects of the diffusion mode, initial diffusion source concentration, grain size, and grain boundary (GB) width were explored in a set of magnet models with various grain sizes. An optimized fitting function was introduced to evaluate the solute distribution in grain boundaries and the effective diffusion coefficient. It is shown that the diffusion mode and the GB width have significant impacts on the effective diffusion coefficient. The results provide a theoretical scheme concerning the quantitative evaluation of GBD efficiency based on thermodynamic analysis.
PMFSE: a video phase-based micro-vibration measurement algorithm for bridge cables in complex background
Authors: Zhang Gang , Yang Xuezhi , Zang Zongdi
Published: April 2024

The cable serves as the primary structural component in cable-stayed bridges, suspension bridges, and other cable-supported bridge designs. Accurate measurement of cable tension holds paramount importance for ensuring the overall safety and stability of bridge structures. Cable tension can be inferred from the vibration frequency, making precise measurement of cable vibration frequency of utmost practical significance. Presently, video-based methodologies, such as phase-based vibration extraction, present notable advantages in terms of speed, efficiency, and non-contact capabilities over conventional acceleration sensor approaches. However, these methods face challenges in accurately discerning the micro-vibration of cables in complex background interference. To address this problem, a phase magnification-based feature signal extraction (PMFSE) algorithm is proposed, which is suitable for detecting small vibration in complex background. The overall idea is to combine the small vibration enhancement method in spatial domain with the signal separation method in time domain. Specifically, in the spatial domain, edge phase information is amplified through phase amplitude weighting and phase enhancement techniques to mitigate non-edge noise. In time domain, cable signals are extracted based on distinguishing features between the cable signal and noise signal. The efficacy of PMFSE is evaluated in various outdoor experiments. Compared with the state-of-the-art methods, PMFSE exhibits substantial improvements on the cable micro-vibration frequency measurement in complex background.
A novel portable microchip electrophoresis system for rapid on-site detection of soil nutrient ions
Authors: Liu Yaping , Lu Zihao , He Wenhe , Wu Yanyan , Li Jingmin , Sun Cuimin
Published: April 2024

The conventional techniques for soil nutrient ion detection face challenges, including prolonged preparation periods and the necessity for distinct instruments tailored to each specific ion. To address these issues, we have engineered a cutting-edge soil nutrient ion detection apparatus: the Microchip Electrophoresis Soil Nutrient Ion Portable Detection System (ME-SNI-PDS). This system, leveraging microchip electrophoresis with a capacitively coupled contactless conductivity detector (ME-C4D), simplifies the detection process with user-friendly touchscreen controls. Our system is capable of simultaneous detection of key soil nutrient ions—ammonium (NH4
+), calcium (Ca2+), magnesium (Mg2+), potassium (K+), nitrate (NO3
−), and dihydrogen phosphate (H2PO4
−)—in a swift 180 s, facilitated by precise voltage regulation. We have refined the buffer solution, consisting of 20 mM 2-(N-morpholinyl)-ethanesulfonic acid and L-histidine, with the addition of 0.01 mM cetyltrimethylammonium bromide and 10 mM 18-crown-6, to ensure the complete resolution of soil nutrient ions. Following this, we established highly accurate peak height-to-concentration correlations for the six aforementioned ions, each with a coefficient of determination (R2) exceeding 0.99. The detection limits for these ions stand at a remarkably low concentration of 0.05 mM, translating to 0.9 mg l−1 for NH4
+, 2.0 mg l−1 for Ca2+, 1.2 mg l−1 for Mg2+, 1.96 mg l−1 for K+, 3.1 mg l−1 for NO3
−, and 4.85 mg l−1 for H2PO4
−. Subsequent soil leachate analysis via the ME-SNI-PDS has yielded ion content data that, upon comparison with results from continuous flow analyser (CFA) and inductively coupled plasma atomic emission spectrometry, confirm the system’s exceptional integration, compactness, portability, speed, and efficiency. The ME-SNI-PDS shows immense promise for application in precision agriculture and the prevention of surface soil pollution. It is poised to make a significant impact in the realm of crop fertilization and environmental stewardship.
An acoustic weighing method based on oscillation signal and feature enhanced network
Authors: Wang Yingwei , Li Xinbo , Jiang Liangxu , Sun Meiqi , Zhang Han , Sun Xiaodong
Published: April 2024

Acoustic weighing is a promising method for non-contact mass measurement of tiny objects as it avoids contamination and contact losses. However, due to the highly nonlinear nature of the acoustic field, some parameters of the mechanism model of acoustic weighing cannot be accurately simulated, thereby reducing the accuracy of acoustic weighing. To improve the accuracy of acoustic weighing, we propose an acoustic weighing method based on oscillating signals and feature enhancement network. Firstly, to drive the object oscillation and collect oscillation data, an acoustic levitation-based data acquisition system is constructed. Then, to break the limitations of the mechanism model, a feature enhancement network named CNN-BiLSTM-SE is proposed, which directly establishes the correlation between oscillating signals and actual mass. Finally, these data are used to train and test the proposed network model, validating the effectiveness of the model. Experimental results show that the method achieves high accuracy in measuring object mass, following the actual measurements with remarkable consistency. In addition, our approach is also suitable for acoustic weighing of small and sensitive objects, opening up new perspective for the study and application of nonlinear acoustic systems.
Exact computation of projected sphere centres in cone beam x-ray projections
Authors: Burkhard Simon , Küng Alain
Published: April 2024

A method is presented for fitting the projected centres of spheres in cone beam x-ray imaging. By using a suitable coordinate system, the method allows direct and exact calculation of the sphere centre without fitting the projection shape with an ellipse and correcting from the ellipse centre to the sphere centre. Advantages in numerical implementation result from the number of unknown variables being reduced compared to ellipse fits. Additionally, the orientation of the detector relative to the x-ray source can be obtained from fitting the shapes of projections of multiple spheres without knowledge of the positions or dimensions of the spheres. The accuracy of the method is compared to other techniques using simulated x-ray projections.
Characterisation of the interplay between microstructure and opto-electronic properties of Cu(In,Ga)S2 solar cells by using correlative CL-EBSD measurements
Authors: Hu Yucheng , Kusch Gunnar , Adeleye Damilola , Siebentritt Susanne , Oliver Rachel
Published: April 2024

Cathodoluminescence and electron backscatter diffraction have been applied to exactly the same grain boundaries (GBs) in a Cu(In,Ga)S2 solar absorber in order to investigate the influence of microstructure on the radiative recombination behaviour at the GBs. Two different types of GB with different microstructure were analysed in detail: random high angle grain boundaries (RHAGBs) and Σ3 GBs. We found that the radiative recombination at all RHAGBs was inhibited to some extent, whereas at Σ3 GBs three different observations were made: unchanged, hindered, or promoted radiative recombination. These distinct behaviours may be linked to atomic-scale grain boundary structural differences. The majority of GBs also exhibited a small spectral shift of about ±10 meV relative to the local grain interior (GI) and a few of them showed spectral shifts of up to ±40 meV. Red and blue shifts were observed with roughly equal frequency.
Vanishing viscosity limit for incompressible axisymmetric flow in the exterior of a cylinder
Authors: Liu Jitao
Published: April 2024

In this paper, we study the initial boundary value problem and vanishing viscosity limit for incompressible axisymmetric Navier–Stokes equations with swirls in the exterior of a cylinder under Navier-slip boundary condition. In the first part, we prove the existence of a unique global solution with the axisymmetric initial data

u

0

ν

∈

L

σ

2

(
Ω
)

and axisymmetric force

f

∈

L
2

(
[
0
,
T
]
;

L
2

(
Ω
)
)

. This result improves the initial regularity condition on the global well-posedness result obtained by K Abe and G Seregin (2020 Proc. R. Soc. Edinburgh A 150 1671–98) and extends their boundary condition. In the second part, we make the first attempt to investigate the inviscid limit of unforced viscous axisymmetric flows with swirls and prove that the viscous axisymmetric flows with swirls converge to inviscid axisymmetric flows without swirls under the condition

‖
r

u

0
θ

ν

‖

L
2

(
Ω
)

=

O

(

ν

)

. Some new uniform estimates, independent of the viscosity, are obtained here. The second result can be thought as a follow-up work to the previous work by K Abe (2020 J. Math. Pures Appl.
137 1–32), where the inviscid limit for the same equations without swirls in an infinite cylinder was studied.
b-MAR: bidirectional artifact representations learning framework for metal artifact reduction in dental CBCT
Authors: Song Yuyan , Yao Tianyi , Peng Shengwang , Zhu Manman , Meng Mingqiang , Ma Jianhua , Zeng Dong , Huang Jing , Bian Zhaoying , Wang Yongbo
Published: April 2024

Objective. Metal artifacts in computed tomography (CT) images hinder diagnosis and treatment significantly. Specifically, dental cone-beam computed tomography (Dental CBCT) images are seriously contaminated by metal artifacts due to the widespread use of low tube voltages and the presence of various high-attenuation materials in dental structures. Existing supervised metal artifact reduction (MAR) methods mainly learn the mapping of artifact-affected images to clean images, while ignoring the modeling of the metal artifact generation process. Therefore, we propose the bidirectional artifact representations learning framework to adaptively encode metal artifacts caused by various dental implants and model the generation and elimination of metal artifacts, thereby improving MAR performance. Approach. Specifically, we introduce an efficient artifact encoder to extract multi-scale representations of metal artifacts from artifact-affected images. These extracted metal artifact representations are then bidirectionally embedded into both the metal artifact generator and the metal artifact eliminator, which can simultaneously improve the performance of artifact removal and artifact generation. The artifact eliminator learns artifact removal in a supervised manner, while the artifact generator learns artifact generation in an adversarial manner. To further improve the performance of the bidirectional task networks, we propose artifact consistency loss to align the consistency of images generated by the eliminator and the generator with or without embedding artifact representations. Main results. To validate the effectiveness of our algorithm, experiments are conducted on simulated and clinical datasets containing various dental metal morphologies. Quantitative metrics are calculated to evaluate the results of the simulation tests, which demonstrate b-MAR improvements of >1.4131 dB in PSNR, >0.3473 HU decrements in RMSE, and >0.0025 promotion in structural similarity index measurement over the current state-of-the-art MAR methods. All results indicate that the proposed b-MAR method can remove artifacts caused by various metal morphologies and restore the structural integrity of dental tissues effectively. Significance. The proposed b-MAR method strengthens the joint learning of the artifact removal process and the artifact generation process by bidirectionally embedding artifact representations, thereby improving the model’s artifact removal performance. Compared with other comparison methods, b-MAR can robustly and effectively correct metal artifacts in dental CBCT images caused by different dental metals.
Evaluation of low-dose computed tomography reconstruction using spatial-radon domain total generalized variation regularization
Authors: Niu Shanzhou , Zhang Mengzhen , Qiu Yang , Li Shuo , Liang Lijing , Liu Qiegen , Niu Tianye , Wang Jing , Ma Jianhua
Published: April 2024

The x-ray radiation dose in computed tomography (CT) examination has been a major concern for patients. Lowing the tube current and exposure time in data acquisition is a straightforward and cost-effective strategy to reduce the x-ray radiation dose. However, this will inevitably increase the noise fluctuations in measured projection data, and the corresponding CT image quality will be severely degraded if noise suppression is not performed during image reconstruction. To reconstruct high-quality low-dose CT image, we present a spatial-radon domain total generalized variation (SRDTGV) regularization for statistical iterative reconstruction based on penalized weighted least-squares (PWLS) principle, which is called PWLS-SRDTGV for simplicity. The presented PWLS-SRDTGV model can simultaneously reconstruct high-quality CT image in space domain and its corresponding projection in radon domain. An efficient split Bregman algorithm was applied to minimize the cost function of the proposed reconstruction model. Qualitative and quantitative studies were performed to evaluate the effectiveness of the PWLS-SRDTGV image reconstruction algorithm using a digital 3D XCAT phantom and an anthropomorphic torso phantom. The experimental results demonstrate that PWLS-SRDTGV algorithm achieves notable gains in noise reduction, streak artifact suppression, and edge preservation compared with competing reconstruction approaches.
Numerical optimization of longitudinal collimator geometry for novel x-ray field
Authors: Insley Benjamin , Bartkoski Dirk , Balter Peter , Prajapati Surendra , Tailor Ramesh , Jaffray David , Salehpour Mohammad
Published: April 2024

Objective. A novel x-ray field produced by an ultrathin conical target is described in the literature. However, the optimal design for an associated collimator remains ambiguous. Current optimization methods using Monte Carlo calculations restrict the efficiency and robustness of the design process. A more generic optimization method that reduces parameter constraints while minimizing computational load is necessary. A numerical method for optimizing the longitudinal collimator hole geometry for a cylindrically-symmetrical x-ray tube is demonstrated and compared to Monte Carlo calculations. Approach. The x-ray phase space was modelled as a four-dimensional histogram differential in photon initial position, final position, and photon energy. The collimator was modeled as a stack of thin washers with varying inner radii. Simulated annealing was employed to optimize this set of inner radii according to various objective functions calculated on the photon flux at a specified plane. Main results. The analytical transport model used for optimization was validated against Monte Carlo calculations using Geant4 via its wrapper, TOPAS. Optimized collimators and the resulting photon flux profiles are presented for three focal spot sizes and five positions of the source. Optimizations were performed with multiple objective functions based on various weightings of precision, intensity, and field flatness metrics. Finally, a select set of these optimized collimators, plus a parallel-hole collimator for comparison, were modeled in TOPAS. The evolution of the radiation field profiles are presented for various positions of the source for each collimator. Significance. This novel optimization strategy proved consistent and robust across the range of x-ray tube settings regardless of the optimization starting point. Common collimator geometries were re-derived using this algorithm while simultaneously optimizing geometry-specific parameters. The advantages of this strategy over iterative Monte Carlo-based techniques, including computational efficiency, radiation source-specificity, and solution flexibility, make it a desirable optimization method for complex irradiation geometries.
Study of ablation phase in double-wire Z-pinch based on optical Thomson scattering
Authors: Wang Wei , Wu Jian , Jiang Zhiyuan , Lu Yuanbo , Wang Zhenyu , Zhao Yiming , Shi Huantong , Chen Li , Li Xingwen , Qiu Aici
Published: April 2024

Measurement of plasma parameters during the ablation phase in the Z-pinch is crucial for investigating the dynamic behaviors. In this study, optical Thomson scattering was employed to measure the temperature and velocity of the ablation plasma in a double-wire Z-pinch. The scattering spectra profiles were fitted using a model that considered the velocity distribution. The experimental results revealed the energy evolution of ablation plasma, the establishment of the global magnetic field and the development of axial non-uniformities. The precursor plasma was found to play a key role in strengthening the global magnetic field. A resistive layer near the wire core with a size of 1.5 mm was observed in the ablation plasma after the precursor plasma column formed. The plasma underwent rapid heating in this layer, the electron temperature rises from 17 eV to 22 eV. Upon leaving this layer, electron the temperature is stable at around 22 eV. The radial distribution of the ablation rate increases and decreases, indicating the axial motion of the ablation plasma, which could be caused by the tilt motion of the stream and the secondary modulation of the natural wavelength.
Design and development of a variable structure gripper with electroadhesion
Authors: An Shunan , Xiang Chaoqun , Ji Cuicui , Liu Shilong , He Lei , Li Lijie , Wang Yanjie
Published: April 2024

Soft grippers are a novel kind of front-end actuators for robotics that offer great benefits such as easy control, superior grabbing capability, and close contact with the environment. They have vast application possibilities in numerous industries such as agricultural picking, item sorting, and medical rehabilitation. In this paper, a soft gripper with a variable structure and electrostatic adsorption is proposed. The gripper includes three fingers uniformly dispersed in the shape of a circle, which can adapt to varying sizes of grabbing objects by dynamically modifying the opening angle of the fingers. Aimed at addressing the existing issue of lacking multi fingers soft pneumatic grippers (SPGs) in grabbing tiny flat items, it is enhanced by embedding an electroadhesion (EA) films at the bottom of the soft pneumatic fingers of the gripper. It is simulated that the diameter adjustment range of this gripper is 0–482 mm, and the angle adjustment range is 0–180° via ABAQUS simulation. Finally, the adaptive grabbing capacity of the soft gripper was validated via experiments. The trials reveal that the gripper can grab items of different sizes by altering the opening angle of the fingers and the maximum load of the gripper can reach 10.91 N during specific grasping operations. The findings confirm that the SPGs with variable structure and EA described in this paper has a high gripping range and the capacity to grab thin flat items. We believe that its excellent gripping performance will encourage different uses of this gripper in everyday life and industry.
Insight into single-helix intelligent shape memory polymer cables: modeling and optimization under finite sliding contact
Authors: Enferadi Alireza , Ostadrahimi Alireza , Li Guoqiang , Baniassadi Majid , Baghani Mostafa
Published: April 2024

This pioneering study focuses on the finite element analysis (FEA) of thermomechanical properties of shape memory polymer (SMP) wire ropes and their components under both small- and finite-sliding contact deformation. To validate the FEA, we need to validate both geometric modeling and non-linear material behavior. Owing to intricate geometry, as well as excessive wire interactions in the structure, this part is studied by simulating a 1 × 37 steel wire rope and then comparing it with existing experimental data. To evaluate the response of non-linear material behavior, we employ the available numerical results to model the thermomechanical property of an SMP rectangular bar under a uniaxial test and then verify both constrained and unconstrained recovery behavior. After rigorous validation, two configurations of 1 × 7 and 1 × 27 SMP cables are modeled based on the thermo-visco-hyperelastic constitutive framework for acrylate polymer systems. Upon exerting an axially tensile load on these 1 × 7 and 1 × 27 SMP wire ropes, the response of force and shape recovery, as well as the normal and shear stress distributions, are measured under constrained and unconstrained conditions. For a deeper physical understanding, the influences of different temperature rates (5 and 1 °C min−1), inter-wire sliding frictional coefficient (0.1–0.6), and multiple-shape programming on the stress-strain-temperature relations of these SMP cables are also investigated. Furthermore, based on optimizing two cable factors of diameter and helix angle, and using the design of experiments method, the specific energy of a 1 × 6 SMP cable is maximized. Under different thermomechanical loadings, this study tries to cast light on the remarkable features and possible potential applications of these newly developed SMP actuators which may foster unparalleled advancements in various industries.