bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent Advances in the Synthesis of Bioactive Glycohybrids via Click-Chemistry
Authors: Sagar Ram , Singh Kavita , Tyagi Rajdeep , Mishra Vinay Kumar , Tiwari Ghanshyam
Published: July 2023

Carbohydrates, traditionally known for their energy-providing role, have gained significant attention in drug discovery due to their diverse bioactivities and stereodiversity. However, pure carbohydrate molecules often exhibit limited bioactivity and suboptimal chemical and physical characteristics. To address these challenges, functional groups with bioactive scaffolds have been incorporated into carbohydrate to enhance their bioactivity and improve their overall properties. Among the various synthetic methods available, click chemistry has emerged as a powerful tool for the synthesis of carbohydrate-containing bioactive scaffolds, known as glycohybrids. Click chemistry offers several advantages, including high chemo- and regioselectivity, mild reaction conditions, easy purification, and compatibility with multiple functional groups. In the present review, we have emphasized the recent advances and most pertinent research on the development of 1,2,3-triazole-containing glycohybrids using the click reaction, their biological evaluations and the structure-activity relationship during 2017–2023. These newly synthesised glycohybrids could potentially be developed as new chemical entities (NCE) in pharmaceutical chemistry and may encourage the use of carbohydrates in drug discovery processes.

1 Introduction

2 CuAAC Click Chemistry Mediated Synthesis of Triazole-Based Glycohybrids and their Biological Activities

3 Conclusions and Perspective
Asymmetric Hetero-Diels–Alder Reaction of 4-Phenyl-1,2,4-triazole-3,5-dione with 2,4-Dienyl Carboxylic Acids
Authors: Ukaji Yutaka , Sato Yu , Ukei Takahiro , Tsugeno Hiromasa , Suga Takuya , Soeta Takahiro
Published: July 2023

The enantioselective hetero-Diels–Alder reaction of the cyclic azo compound 4-phenyl-1,2,4-triazole-3,5-dione with 2,4-dienyl carboxylic acids was performed using tartaric acid ester as the chiral auxiliary. The corresponding cycloadducts were obtained with enantioselectivities of up to 76% ee. The cis-carboxylic acid produced could be converted into the corresponding cis- and trans-methyl esters by varying the reaction conditions.
Greenium, credit rating, and the COVID-19 pandemic
Authors: Arat Emre , Hachenberg Britta , Kiesel Florian , Schiereck Dirk
Published: July 2023

We analyze green and conventional bonds during regular market periods and within times of extreme volatility, the COVID-19 pandemic. We find a negative premium (greenium) of 1.6 bp before the outbreak of COVID-19, but during the times of extreme market stress, this greenium widens to 3.5 bp as our results show a significant outperformance of green bonds. The results indicate that green bonds are more resilient during risk-off periods than non-green bonds. In addition, the greenium effect is moderated by the issuer's country environmental performance as the greenium is more pronounced for issuers from non-green countries prior to COVID-19. We do not find differences between green and non-green countries since COVID-19.
An exploration of machine learning models for the determination of reaction coordinates associated with conformational transitions
Authors: Naleem Nawavi , Abreu Charlles R. A. , Warmuz Krzysztof , Tong Muchen , Kirmizialtin Serdal , Tuckerman Mark E.
Published: July 2023

Determining collective variables (CVs) for conformational transitions is crucial to understanding their dynamics and targeting them in enhanced sampling simulations. Often, CVs are proposed based on intuition or prior knowledge of a system. However, the problem of systematically determining a proper reaction coordinate (RC) for a specific process in terms of a set of putative CVs can be achieved using committor analysis (CA). Identifying essential degrees of freedom that govern such transitions using CA remains elusive because of the high dimensionality of the conformational space. Various schemes exist to leverage the power of machine learning (ML) to extract an RC from CA. Here, we extend these studies and compare the ability of 17 different ML schemes to identify accurate RCs associated with conformational transitions. We tested these methods on an alanine dipeptide in vacuum and on a sarcosine dipeptoid in an implicit solvent. Our comparison revealed that the light gradient boosting machine method outperforms other methods. In order to extract key features from the models, we employed Shapley Additive exPlanations analysis and compared its interpretation with the “feature importance” approach. For the alanine dipeptide, our methodology identifies ϕ and θ dihedrals as essential degrees of freedom in the C7ax to C7eq transition. For the sarcosine dipeptoid system, the dihedrals ψ and ω are the most important for the cisαD to transαD transition. We further argue that analysis of the full dynamical pathway, and not just endpoint states, is essential for identifying key degrees of freedom governing transitions.
Ion-beam-milled graphite nanoribbons as mesoscopic carbon-based polarizers
Authors: Muszyński Marcin , Antoniazzi Igor , Camargo Bruno
Published: July 2023

We demonstrate optical reflectivity and Raman responses of graphite microstructures as a function of light polarization when the incident light is applied perpendicular to the material's stacking direction (c-axis). For this, we employed novel graphite nanoribbons with edges polished through ion-beam etching. In this unique configuration, a strong polarization dependence of the D, G, and 2D Raman modes is observed. At the same time, polarized reflectivity measurements demonstrate the potential of such a device as a carbon-based, on-chip polarizer. We discuss the advantages of the proposed fabrication method as opposed to the mechanical polishing of bulk crystals.
Influence of matching network and frequency on the effective quality factor and performance of a miniature radio frequency ion thruster
Authors: Jiang Wenjia , Wei Liqiu , Yang Xinyong , Yang Zhou
Published: July 2023

The radio frequency ion thruster (RIT) is an electric propulsion device that utilizes radio frequency (RF) power to ionize propellants; thus, its performance is influenced by the frequency and matching network of the RF. In this study, an L&T type wide-range matching network was employed to experimentally investigate the performance of a miniature RIT with 4 cm diameter at different frequencies. The experimental results show that changing the matching parameters of the L&T network at the same frequency leads to changes in the effective quality factor and varying performances of the thruster; under similar effective quality factors, changing the frequency does not significantly affect the performance of the thruster; however, the plasma resistance exhibits frequency dependence. As the frequency increases, the effective collision frequency increases, leading to an increase in plasma resistance, which is beneficial for improving the performance of the thruster at high frequencies. Finally, a set of methods for quickly comparing the performance of RITs was summarized based on the effective quality factor. These research results are also instructive for improving the ionization of induction-coupled discharge devices of other sizes.
Design and test a pneumatically actuated microgripper based on structural stiffness
Authors: Chen Xiaodong , Xie Zhimin , Tai Kang , Tan Huifeng , Chen Xueyan
Published: July 2023

In response to the problem that the actual amplification ratio of the compliant motion amplification mechanism cannot be further improved, this paper introduces a two-stage amplification microgripper based on structural stiffness that is driven by pneumatics. The mechanism not only has the advantages of good symmetry, compact structure, and large output displacement but can also reduce the relative error of the theoretical and experimental amplification ratios. The first-stage mechanism selects high-stiffness mechanisms and high-stiffness flexure hinges, and the second-stage mechanism uses low-stiffness mechanisms and low-stiffness flexure hinges. The arrangement order of the mechanism is determined by the working mode analysis. The specific dimensions of the mechanism and flexure hinges are determined through structural size optimization so that the amplification performance of the mechanism will be optimal. The experimental results show that the displacement amplification ratio of both the opening and closing of the microgripper is 41.8.
Ultrahigh porosity photoluminescent silicon aerocrystals with greater than 50% nanocrystal ensemble quantum yields
Authors: Gelloz Bernard , Canham Leigh , Asaka Koji , Nakamura Yuto , Kishida Hideo
Published: July 2023

Three types of mesoporous silicon flakes were fabricated by anodization in methanoic hydrofluoric acid from the same substrates (heavily doped p-type). Even though anodization current density, rinsing, drying method, and storage condition were the same for all three wafers, the resulting porous silicon (PSi) structures had very different properties. They had very different colors. Two of them showed quite high luminescence quantum yields (QYs), confirmed by very long luminescence lifetimes. The highest QY exceeded 50% for a peak photoluminescence wavelength of ∼750 nm. To date, this QY is the highest obtained for PSi and very importantly for silicon with large mesopores, which is typically not highly efficient (as opposed to silicon with small mesopores and microporous silicon). Large mesopores (>15 nm diameter) facilitate impregnation of various substances into luminescent material, such as metals for plasmonics and drugs for theranostics. The differing luminescent properties were correlated to electrolyte temperature during anodization, and evolution of the electrolyte batch (lowering of active fluoride content and buildup of hexafluorosilicate) used to anodize several wafers, whose effects are often overlooked when mass-producing PSi. Supercritical drying and completion of the slow growth of native oxide passivation in the dark leading to different final partially oxidized PSi structures are also important factors for the high QYs obtained. The highest QY was obtained with the structure having the most isolated Si nanocrystals in an amorphous Si oxide tissue.
Time-frequency analysis of (k,a)-generalized wavelet transform and applications
Authors: Boggarapu Pradeep , Mejjaoli Hatem , Mondal Shyam Swarup , Senapati P. Jitendra Kumar
Published: July 2023

The (k, a)-generalized wavelet transform is a novel addition to the class of wavelet transforms, which has gained a respectable status in the realm of time-frequency signal analysis within a short period of time. Since the study of time-frequency analysis is both theoretically interesting and practically useful, in this article, we investigated several subjects of time-frequency analysis for the (k, a)-generalized wavelet transform. First, we analyze the concentration of this transform on sets of finite measure. In particular, we prove Donoho–Stark and Benedicks-type uncertainty principles. We prove several versions of Heisenberg-type uncertainty principles for this transformation. Furthermore, involving the reproducing kernel and spectral theories, we investigate the time frequency and study the scalogram for the same wavelet transform. Finally, we provide Shapiro’s mean dispersion type theorems at the end.
A low power microwave room-temperature air plasma jet at atmospheric pressure
Authors: Wu Li , Zhang Xianyu , Liu Tao , Zhang Wencong , Tao Junwu , Cheng Fei
Published: July 2023

An atmospheric pressure low power microwave-induced air plasma source at 2.45 GHz is presented in this Letter. The device was capable of self-igniting air and generating plasma with only 50 W microwave input power and without any extra trigger. Its sustaining power was as low as 10 W, and the gas temperature of plasma tail flame measured by a fiber optic thermometer was about 32 °C. Spectroscopic measurements showed strong OH(A2Σ+→X2Π) bands at 306–310 nm and oxygen atomic lines OI (3p5P → 3s5S) at 777.1 nm and OI (3p3P → 3s3S) at 844.6 nm. NO−γ(A2Σ+→X2Πr) from 200 to 300 nm was also detected in this air plasma jet. This portable plasma apparatus offers potential for air plasma applications in the biomedical fields.
Long-lasting deformation potential effect in Ge induced by UV photoexcitation
Authors: Rathore R. , Singhal H. , Kamal C. , Chakera J. A.
Published: July 2023

Understanding ultrafast response of a semiconductor is necessary for next-generation optoelectronic device applications. Here, we investigate the ultrafast response of an archetypal semiconductor Ge [111] crystal upon photoexcitation at two pump wavelengths, 800 nm (fundamental) and 400 nm (second harmonic, UV radiation), using time-resolved x-ray diffraction (TXRD). The simulated TXRD profiles using a proposed four-layer model and Takagi–Taupin equations reveal that the strain propagation is primarily due to electron diffusion. Intriguingly, the initial (<100 ps) fast decrease in the induced strain for second harmonic excitation suggests that the strain originates from the deformation potential (DP) effect. The higher photon energy (second harmonic pump) excites the electrons to higher conduction band valleys, resulting in DP-induced strain compared to the fundamental pump, which only generates thermo-elastic strain. The DP strain, estimated from the DP coefficient (simulated via density functional theory-based electronic structure simulations) and electron density (simulated from experimental results), shows an excellent agreement with the observed strain. The strain after ∼100 ps delay for second harmonic excitation and strain from fundamental excitation are attributed to the thermo-elastic effect as confirmed by the density-dependent two-temperature model. Our study reveals the long-lasting DP effect in Ge [111], which provides an opportunity to avoid heating in optoelectronic devices due to the thermo-elastic effect at the initial time scale.
Solubility of NaCl under anisotropic stress state
Authors: Mahmoud Hawchar Bilal , Honorio Tulio , Vandamme Matthieu , Osselin Florian , Pereira Jean-Michel , Brochard Laurent
Published: July 2023

Salt solubility is generally determined under isotropic stress conditions. Yet, in the context of salt weathering of porous media, mechanical constraints on the in-pore growth of salt crystals are likely to be orientation-dependent, resulting in an anisotropic stress state on the crystal. In this paper, we determine by molecular simulation the solubility of NaCl in water when the crystal is subjected to anisotropic stress. Such anisotropy causes the chemical potential of the crystal to be orientation-dependent, and proper thermodynamic formulation requires describing the chemical potential as a tensor. The solute and crystal chemical potentials are computed from free energy calculations using Hamiltonian thermodynamic integration, and the usual condition of solubility is reformulated to account for the tensorial nature of the crystal chemical potential. We investigate in detail how the uniaxial compression of the crystal affects its solubility. The molecular simulation results led to revisiting the Correns law under anisotropic stress. Regarding the solute, the non-ideal behavior of the liquid phase is captured using Pitzer’s ion interaction approach up to high concentrations of interest for in-pore crystallization and beyond the concentrations addressed in the existing literature. Regarding NaCl crystals, the validity of the generalized Gibbs–Duhem equation for a tensorial chemical potential is carefully verified, and it is found that crystallization progresses almost orthogonally to the crystal surface even under high shear stresses. Comparing uniaxial and isotropic compression highlights the major differences in solubility caused by stress anisotropy, and the revisited Correns law offers an appropriate framework to capture this phenomenon.
On the influence of enthalpy of formation on lattice distortion and intrinsic ductility of concentrated refractory alloys
Authors: Shaikh Sufyan M. , Murty B. S. , Yadav Satyesh K.
Published: July 2023

Valence electron concentration (VEC), atomic size difference (δ), and Pugh’s ratio (B/G) are a few of the empirical parameters widely used to design ductile refractory alloys. Here, we used the intrinsic ductility parameter (D), which is the ratio of surface energy (γs) and unstable stacking fault energy (γusfe), to design ductile refractory alloy. We found that the D correctly captures the experimentally observed ductility in concentrated refractory alloys. Here, we studied the enthalpy of formation (ΔEf), lattice distortion, and D of 9 refractory metals and 36 equiatomic refractory alloys using density functional theory simulations. We found that the ΔEf strongly influences the D of concentrated refractory alloys. The positive ΔEf and δ lead to large lattice distortion in concentrated refractory alloys. However, we did not find a strong correlation between lattice distortion and D in the presently studied alloys. We found that the success of VEC and Pugh’s ratio in designing ductile refractory alloys has a strong dependence on the underlying ΔEf of the alloy. We have developed a bottom-up method, which drastically reduces the number of alloys to be studied, to design ductile concentrated refractory alloys that can be thermodynamically stable.
Voltage-margin limiting mechanisms of AlScN-based HEMTs
Authors: Döring P. , Krause S. , Waltereit P. , Brückner P. , Leone S. , Streicher I. , Mikulla M. , Quay R.
Published: July 2023

In this work, the off-state characteristics of AlScN/GaN high electron mobility transistors (HEMTs) grown by metalorganic chemical vapor deposition (MOCVD) were studied and directly compared to an AlGaN- and an AlN-HEMT grown in the same MOCVD. Pinch-off instability and leaky capacitive measurements were observed for AlScN-based HEMTs, which was correlated with a higher ideality factor and lower effective potential barrier height than the AlGaN and AlN-HEMTs. However, the reverse bias characteristics exhibited a sudden drain-current increase without a significant increase in gate-leakage current. The drain-leakage current is assumed to be related to a parasitic channel across the AlScN-barrier as a result of trap-assisted carrier transport with a Poole–Frenkel characteristic. The demonstrated pinch-off instability led to significant gain expansion in load-pull measurements and early soft-breakdown, which, in turn, limits the achievable voltage-margin. The results demonstrate a key issue to reveal the full potential of AlScN-based HEMTs for mm-wave applications.
John Staer (1850–1933): the patronym behind Eucalyptus staeri, the Albany Blackbutt
Authors: Ludewig Alexandra
Published: July 2023

Millennia of evolutionary ecology have seen Australia become one of the driest and flattest continents on Earth—and in the process, home to more than 700 species of Eucalyptus. Colonial scientists named them using a binomial system, thereby overwriting local vernaculars that had persisted for tens of thousands of years. This paper traces the man commemorated in the Albany Blackbutt, Eucalyptus staeri, a tree unique to the Great Southern region of Western Australia, traditionally the land of the Menang Noongar people. Using a biographical lens, the paper examines the intersection of Western science and commerce in plant collection and naming, and the ways in which these processes exclude or discount Indigenous knowledge. The paper argues that a more holistic and inclusive historical interpretation of herbarium specimens of E. staeri is achieved by correcting and re-analysing information about the German settler after whom it is named, John Staer, while at the same time acknowledging the Noongar people’s deep knowledge (kartijin) of plants that has been passed down over many thousands of years.
Genomic and geographical structure of human cytomegalovirus
Authors: Charles Oscar J. , Venturini Cristina , Gantt Soren , Atkinson Claire , Griffiths Paul , Goldstein Richard A. , Breuer Judith
Published: July 2023

Human cytomegalovirus (CMV) has infected humans since the origin of our species and currently infects most of the world’s population. Variability between CMV genomes is the highest of any human herpesvirus, yet large portions of the genome are conserved. Here, we show that the genome encodes 74 regions of relatively high variability each with 2 to 8 alleles. We then identified two patterns in the CMV genome. Conserved parts of the genome and a minority (32) of variable regions show geographic population structure with evidence for African or European clustering, although hybrid strains are present. We find no evidence that geographic segregation has been driven by host immune pressure affecting known antigenic sites. Forty-two variable regions show no geographical structure, with similar allele distributions across different continental populations. These “nongeographical” regions are significantly enriched for genes encoding immunomodulatory functions suggesting a core functional importance. We hypothesize that at least two CMV founder populations account for the geographical differences that are largely seen in the conserved portions of the genome, although the timing of separation and direction of spread between the two are not clear. In contrast, the similar allele frequencies among 42 variable regions of the genome, irrespective of geographical origin, are indicative of a second evolutionary process, namely balancing selection that may preserve properties critical to CMV biological function. Given that genetic differences between CMVs are postulated to alter immunogenicity and potentially function, understanding these two evolutionary processes could contribute important information for the development of globally effective vaccines and the identification of novel drug targets.
Climatic stability and geological history shape global centers of neo- and paleoendemism in seed plants
Authors: Cai Lirong , Kreft Holger , Taylor Amanda , Schrader Julian , Dawson Wayne , Essl Franz , van Kleunen Mark , Pergl Jan , Pyšek Petr , Winter Marten , Weigelt Patrick
Published: July 2023

Assessing the distribution of geographically restricted and evolutionarily unique species and their underlying drivers is key to understanding biogeographical processes and critical for global conservation prioritization. Here, we quantified the geographic distribution and drivers of phylogenetic endemism for ~320,000 seed plants worldwide and identified centers and drivers of evolutionarily young (neoendemism) and evolutionarily old endemism (paleoendemism). Tropical and subtropical islands as well as tropical mountain regions displayed the world’s highest phylogenetic endemism. Most tropical rainforest regions emerged as centers of paleoendemism, while most Mediterranean-climate regions showed high neoendemism. Centers where high neo- and paleoendemism coincide emerged on some oceanic and continental fragment islands, in Mediterranean-climate regions and parts of the Irano-Turanian floristic region. Global variation in phylogenetic endemism was well explained by a combination of past and present environmental factors (79.8 to 87.7% of variance explained) and most strongly related to environmental heterogeneity. Also, warm and wet climates, geographic isolation, and long-term climatic stability emerged as key drivers of phylogenetic endemism. Neo- and paleoendemism were jointly explained by climatic and geological history. Long-term climatic stability promoted the persistence of paleoendemics, while the isolation of oceanic islands and their unique geological histories promoted neoendemism. Mountainous regions promoted both neo- and paleoendemism, reflecting both diversification and persistence over time. Our study provides insights into the evolutionary underpinnings of biogeographical patterns in seed plants and identifies the areas on Earth with the highest evolutionary and biogeographical uniqueness—key information for setting global conservation priorities.
Cambrian explosion condensed: High-precision geochronology of the lower Wood Canyon Formation, Nevada
Authors: Nelson Lyle L. , Crowley James L. , Smith Emily F. , Schwartz Darin M. , Hodgin Eben B. , Schmitz Mark D.
Published: July 2023

The geologically rapid appearance of fossils of modern animal phyla within Cambrian strata is a defining characteristic of the history of life on Earth. However, temporal calibration of the base of the Cambrian Period remains uncertain within millions of years, which has resulted in mounting challenges to the concept of a discrete Cambrian explosion. We present precise zircon U–Pb dates for the lower Wood Canyon Formation, Nevada. These data demonstrate the base of the Cambrian Period, as defined by both ichnofossil biostratigraphy and carbon isotope chemostratigraphy, was younger than 533 Mya, at least 6 My later than currently recognized. This new geochronology condenses previous age models for the Nemakit–Daldynian (early Cambrian) and, integrated with global records, demonstrates an explosive tempo to the early radiation of modern animal phyla.
Increased gene expression variability hinders the formation of regional mechanical conflicts leading to reduced organ shape robustness
Authors: Trinh Duy-Chi , Martin Marjolaine , Bald Lotte , Maizel Alexis , Trehin Christophe , Hamant Olivier
Published: July 2023

To relate gene networks and organ shape, one needs to address two wicked problems: i) Gene expression is often variable locally, and shape is reproducible globally; ii) gene expression can have cascading effects on tissue mechanics, with possibly counterintuitive consequences for the final organ shape. Here, we address such wicked problems, taking advantage of simpler plant organ development where shape only emerges from cell division and elongation. We confirm that mutation in VERNALIZATION INDEPENDENCE 3 (VIP3), a subunit of the conserved polymerase–associated factor 1 complex (Paf1C), increases gene expression variability in Arabidopsis. Then, we focused on the Arabidopsis sepal, which exhibits a reproducible shape and stereotypical regional growth patterns. Invip3sepals, we measured higher growth heterogeneity between adjacent cells. This even culminated in the presence of negatively growing cells in specific growth conditions. Interestingly, such increased local noise interfered with the stereotypical regional pattern of growth. We previously showed that regional differential growth at the wild-type sepal tip triggers a mechanical conflict, to which cells resist by reinforcing their walls, leading to growth arrest. Invip3, the disturbed regional growth pattern delayed organ growth arrest and increased final organ shape variability. Altogether, we propose that gene expression variability is managed by Paf1C to ensure organ robustness by building up mechanical conflicts at the regional scale, instead of the local scale.
Lagrangian and Hamiltonian formulations of asymmetric rigid body, considered as a constrained system
Authors: Deriglazov Alexei A
Published: July 2023

This work is devoted to a systematic exposition of the dynamics of a rigid body, considered as a system with kinematic constraints. Having accepted the variational problem in accordance with this, we no longer need any additional postulates or assumptions about the behavior of the rigid body. All the basic quantities and characteristics of a rigid body, as well as the equations of motion and integrals of motion, are obtained from the variational problem by direct and unequivocal calculations within the framework of standard methods of classical mechanics. Several equivalent forms for the equations of motion of rotational degrees of freedom are deduced and discussed on this basis. Using the resulting formulation, we revise some cases of integrability, and discuss a number of peculiar properties, that are not always taken into account when formulating the laws of motion of a rigid body.
Seeing the invisible: convection cells revealed with thermal imaging
Authors: Guido Renzo , Dutra Mateo , Monteiro Martín , Martí Arturo C
Published: July 2023

Fluid instabilities are ubiquitous phenomena of great theoretical and applied importance. In particular, an intriguing example is the thermocapillary or Bénard-Marangoni instability which occurs when a thin horizontal fluid layer, whose top surface is free, is heated from below. In this phenomenon, after passing a certain temperature difference threshold, the fluid develops a regular pattern, usually hexagonal, of convection cells known as Bénard convection. In general, this pattern is not visible to the naked eye unless specific tracers are incorporated into the fluid. The use of thermal imaging is a simple alternative not only for directly observing this phenomenon but also for obtaining valuable quantitative information, such as the relationship between the critical wavelength and the thickness of the fluid layer. Here, we propose an experiment specially suited for laboratory courses in fluid mechanics or nonlinear physics that involves the use of thermal cameras, or appropriate smartphone accessories, to study Bénard convection.
Optical absorption spectra of GaSb/GaAs quantum-ring-with-dot structures and their potential for intermediate band solar cells
Authors: Kunrugsa Maetee
Published: July 2023

Optical absorption spectra of GaSb/GaAs quantum-ring-with-dot structures (QRDSs) are calculated using Fermi’s golden rule by which the electronic states involved in the optical transitions are obtained from the eight-band k ⋅ p method. The absorption spectra of multi-stacked QRDS layers show that the interband and intraband transitions are favorable to intermediate band solar cells (IBSCs). A drift-diffusion model with rate equations for a solar cell containing multi-stacked QRDS layers is formulated based on the absorption spectra. The external quantum efficiency (EQE) determined by the model with the AM1.5 solar spectrum and additional infrared light demonstrates that the confined hole states in the quantum ring (QR) parts of the QRDSs effectively function as an IB. The more efficient two-step photon absorption indicated by the enhancement of the EQE also suggests the potential of QRDSs for the IBSCs.
Effect of CF4 additive on dynamic surface charge deposited on dielectric by helium atmospheric pressure plasma jet
Authors: Han Wen-Hu , Zhang Bo , Guo Wang , Sun Yu-Hao , Fan Lei , Yang Xiong , Sun Ming-Yang , Zhao Hang , Zhang Guan-Jun
Published: July 2023

The addition of active trace components to non-thermal plasmas effectively enhances their chemical activity and has attracted considerable academic attention in the plasma community. It is essential to quantitatively estimate the effect of active addition on the properties of the plasma–surface interaction (PSI). In this study, we focus on the fundamental properties of dynamic surface charge deposited by a He-atmospheric pressure plasma jet (APPJ) with 0%–2% CF4 additive. The charge distribution is measured by a reflective optical measurement platform based on linear electro-optic effect, and is calculated with surface charge density inversion algorithm. Results show that a higher CF4 concentration can shrink the region of surface charge accumulation. Polarity effect is observed in aspects of maximum charge density when the CF4 concentration gradually rises. The negative charge deposition is suppressed by the addition of CF4, nearly disappearing at 2% concentration. While the maximum density of positive charge rises to ∼25 nC cm−2 at 0.5% CF4 before it decreases to ∼10 nC cm−2. The dispersions of total surface charge at 0.5% and 1.5% additives indicate the unstable periodic bombardment of ionization waves in He/CF4 APPJ. The double effect of CF4 additive on the surface charges by He-APPJ is also discussed. These results provide fresh and deep insights into the interaction between dielectric surface modification and ionization waves that occurs in other plasmas processing fed with composite gases.
Electron spin resonance study on the 4f honeycomb quantum magnet YbCl3
Authors: Sichelschmidt Jörg , Häußler Ellen , Vinokurova Ekaterina , Baenitz M , Doert Thomas
Published: July 2023

The local magnetic properties of Yb3+ in the layered honeycomb material YbCl3 were investigated by electron spin resonance on single crystals. For in-plane and out-of-plane field orientations the g-factor shows a clear anisotropy (

g
∥

=
2.97
(
8
)

and

g
⊥

=
1.53
(
4
)

), whereas the low temperature exchange coupling and the spin relaxation display a rather isotropic character. At elevated temperatures the contribution of the first excited crystal field level (

21
±
2

meV) dominates the spin relaxation.
An adaptive selective ensemble algorithm for fault classification
Authors: Zhang Xiaotao , Li Jiangcheng , Liu Fulong , Chen Wei , Dong Limin
Published: July 2023

With the aim of improving the classification performance of a single extreme learning machine (ELM) for fault diagnosis, an adaptive selective ensemble classification algorithm is proposed based on the idea of ensemble learning. The proposed algorithm achieves better classification performance than a single model and the selected ELM subnetworks are selected adaptively and the ensemble weights of selected ELM subnetworks are calculated adaptively, which avoids the complex process of manually selecting subnetworks and calculating ensemble weights. First, a regularized error weight adjustment ELM is constructed by introducing regularization parameters and error weight adjustment matrix to a standard ELM, where the error weight adjustment matrix is obtained by the method of adaptive Gaussian kernel density estimation. Then, discrepancy subnetworks are constructed using six different activation functionsand the ensemble weights of subnetworks are obtained adaptively according to the normalized ratio of mean and variance of subnetwork F-scores to achieve the ensemble of subnetworks. Finally, the adaptive selective ensemble classification algorithm is validated using the UCI dataset and experimental acoustic emission signals of gearbox faults. The results show that the adaptive selective ensemble method can improve the stability and accuracy of classification algorithms and the achieved classification accuracy for experimental acoustic emission was 0.9773.
A new mechanical compound fault diagnosis method based on morphological filter and RLS
Authors: Xue Zhuo , He Dan , Ni ZeXing , Wang Xiufeng
Published: July 2023

Mechanical compound fault diagnosis is a thorny issue in the industry. To overcome this problem, a method named morphological filter—recursive least squares (MF-RLS) is proposed in this paper. In the proposed method, MF-RLS is used to sequentially separate the different fault impulse features by decomposing the observed signal into a series of iterative morphological filtering components (IMFCs). First, the measured signal is decomposed into different scales by the multi-scale MF. Then, the product of kurtosis and envelope harmonic-to-noise ratio index is used to select the best IMFC. Finally, the IMFC is input to RLS to separate other fault features. After continuous iterations, the separation and extraction of the compound fault impulse features are achieved. The simulation and experiment of the mechanical compound fault have verified the effectiveness of the proposed method.
SOI-based 12 × 12 arrayed waveguide grating for fiber Bragg grating interrogation system
Authors: Li Ting , Yuan Pei , Li Shufeng , Li Ke , Zhu Lianqing
Published: July 2023

Fiber Bragg grating (FBG) interrogator is a scientific instrument that can indirectly monitor physical quantities such as temperature and pressure by detecting the center wavelength of FBG. The arrayed waveguide grating (AWG), one of the fundamental parts of the FBG interrogation system, is essential for driving the downsizing of the system and high-speed rate. In this paper, a 12-channel silicon on insulator based AWG with an average 3 dB bandwidth of 2.23

nm

, insertion loss of less than 5 dB, and crosstalk of −16.64 dB is designed and fabricated for a photonic integrated FBG interrogation system. The wavelength resolution of the FBG interrogation system of this AWG is 8

pm

, and the wavelength accuracy measured in the dynamic range of 0.8

nm

is 10.59

pm

. This AWG can be well used in FBG interrogation systems.
Radio-immune response modelling for spatially fractionated radiotherapy
Authors: Cho Young-Bin , Yoon Nara , Suh John H , Scott Jacob G
Published: July 2023

Objective. Radiation-induced cell death is a complex process influenced by physical, chemical and biological phenomena. Although consensus on the nature and the mechanism of the bystander effect were not yet made, the immune process presumably plays an important role in many aspects of the radiotherapy including the bystander effect. A mathematical model of immune response during and after radiation therapy is presented. Approach. Immune response of host body and immune suppression of tumor cells are modelled with four compartments in this study; viable tumor cells, T cell lymphocytes, immune triggering cells, and doomed cells. The growth of tumor was analyzed in two distinctive modes of tumor status (immune limited and immune escape) and its bifurcation condition. Main results. Tumors in the immune limited mode can grow only up to a finite size, named as terminal tumor volume analytically calculated from the model. The dynamics of the tumor growth in the immune escape mode is much more complex than the tumors in the immune limited mode especially when the status of tumor is close to the bifurcation condition. Radiation can kill tumor cells not only by radiation damage but also by boosting immune reaction. Significance. The model demonstrated that the highly heterogeneous dose distribution in spatially fractionated radiotherapy (SFRT) can make a drastic difference in tumor cell killing compared to the homogeneous dose distribution. SFRT cannot only enhance but also moderate the cell killing depending on the immune response triggered by many factors such as dose prescription parameters, tumor volume at the time of treatment and tumor characteristics. The model was applied to the lifted data of 67NR tumors on mice and a sarcoma patient treated multiple times over 1200 days for the treatment of tumor recurrence as a demonstration.
Implementation of cross-scale plane micro-scratching process driven by hybrid piezoelectric actuation
Authors: Su Qi , Sun Jianhua , Deng Jie , Liu Yingxiang , Zhang Shijing
Published: July 2023

The atomic force microscope tip-based mechanical machining technique has been used to fabricate complex micro-structures successfully. However, the machining scope and depth are limited, which holds back this technique severely. This work presents the design and evaluation of a piezoelectric manufacturing system (PMS) for implementation of cross-scale (large scale and high resolution) plane micro-scratching. The PMS has the two-dimensional (2D) micro-machining ability with depths up to 0.98 μm in the millimeter machining scope through the combination of a travel range XY positioning stage and a three-degree-of-freedom (3-DOF) sandwich piezoelectric manipulator. The tracing property of the PMS is feasible for large scale machining by controlling the multi-axis cooperative motion of the 2-DOF stage. The experiments show that the micro-triangles and micro-circles arrays with dimensions from 40 μm to 400 μm are machined successfully. The deviations of the position determination and machined depths for all the micro-structures are less than 5%. Further, it is verified that the manipulator has potential to be used in vibration-assisted cutting to improve machining quality. To sum up, the PMS shows great prospects in the applications of machining cross-scale and large depth planar micro-structures.
Study on helium gas bubble levitation in high field superconducting magnet
Authors: Wei Junwen , Huang Ziyi , Lei Zhiwen , Wu Qiong , Wang Yifan , Kang Xuyang , Li Zi , Yan Zhiyong , Yan Yufan , Jiang Donghui , Qu Timing , Tan Yunfei
Published: July 2023

The abnormal temperature rise and early quench often happened to the high field superconducting magnet, especially when the magnetic field is higher than 20 T. This phenomenon is attributed to helium gas bubbles levitation in the special high magnetic field environment. So, it is very important to accurately identify the formation and distribution of helium gas bubbles levitation for the development of high field superconducting magnet. In this paper, a new analytical method based on pressure is proposed to analysis the formation conditions and the spatial distribution of helium gas bubbles levitation. And a no-insulation REBCO insert coil was also developed to study the phenomenon of helium gas bubbles levitation. The REBCO insert coil was tested in high magnetic field produced by a water-cooled magnet. The new analytical method was used to simulate the formation conditions of helium gas bubbles levitation and the temperature distribution of the REBCO insert.
Investigation of electronic and optical properties of alkali atom doped CuInSe2 using density functional theory
Authors: Sharma Shikha , Khan Karina , Soni Mamta , Ahuja Ushma , Soni Amit , Sahariya Jagrati
Published: July 2023

In this study, the effect of alkali metal (Rb, Cs) doping on the electronic structure of CuInSe2 chalcopyrite have been investigated. The electronic structure of pure and doped chalcopyrites has been interpreted in terms of energy bands and density of states. The doping of Rb and Cs increases the band gap of CuInSe2 from 0.81 eV and attains its maximum value of 1.16 eV with 25% doping of Rb at Cu site. The forbidden gap of doped compounds is found to be suitable for optoelectronic and photovoltaic applications. Therefore, the investigations of various optical properties such as, dielectric tensors, absorption, reflection and refraction spectra, for Cu1−xAxInSe2 (A = Rb, Cs; x = 0, 0.125 and 0.25) compounds are performed to understand the optical performance of all these compounds. The imaginary part of dielectric tensor of pure and doped CuInSe2 are explained with the help of the various inter-band transitions. The refractive index for CuInSe2 is found to be 2.60 which reduces to 2.40 and 2.53 for Cu0.75Rb0.25InSe2 and Cu0.75Cs0.25InSe2 compounds, respectively. All investigations for Cu1−xAxInSe2 (A = Rb, Cs; x = 0, 0.125 and 0.25) compounds have been carried out using density functional theory. Present study shows that doping of Rb and Cs enhances the optoelectronic response of CuInSe2 for its utilization in photovoltaic and optoelectronic applications.
Dynamical behaviors of vertical-cavity surface-emitting lasers with an embedded saturable absorber subjected to an on-off keying (OOK) current modulation
Authors: Temgoua Loannis Pavel Gauss , Mbé Jimmi Hervé Talla , Woafo Paul
Published: July 2023

We numerically study the dynamics of VCSEL-SA when modulated by an analog on-off keying (OOK) current. It is found that the laser gives a pulse-like response when operated below the threshold current. After the threshold current, which is in the excitable phase, the laser generates single spikes (phasic spiking) and a series of spikes (tonic spiking) wherein the amplitude of the spikes varies as the form of the current. Complex dynamics such as bursting oscillations and chaotic dynamics are successfully generated at low frequencies (few MHz). After this excitable phase, the laser copies the OOK current with underdamped oscillations generated during the OFF phase of the OOK current.
Geometric eccentricity effect on thickness-shear vibration of an elliptical flexoelectric crystal plate
Authors: Zheng Yang , Sun Zhenbo , Huang Bin , Guo Yan
Published: July 2023

In this paper, a thickness-shear vibration model for a two-dimensional finite flexoelectric crystal plate with slowly varying thickness and elliptical cross section is presented. The influences of eccentricity and flexoelectricity on the fundamental frequencies of thickness-shear vibration and electric potential distributions under short circuit boundary condition are investigated. The proposed model uses the first order McLaughlin series to approximate the elliptical function and the first derivative of elliptical function is ignored since the plate thickness varies slowly. For the finite plate, the symmetric mode in length and antisymmetric mode in thickness are adopted for the displacement function. In addition, only the shear strain gradient through the thickness is used in the mathematical model for the thin and long flexoelectric crystal plate. By implementing the variational principle, the governing equations are obtained and further solved by the Galerkin method. The obtained frequencies of thickness-shear mode are expressed in terms of eccentricity and length-to-thickness ratio. The results show that the eccentricity has great influence on the nondimensional fundamental frequencies. A small reduction in eccentricity results in significant increment of the nondimensional frequency implying that it is possible to increase the fundamental frequency by changing the cross section of the elliptical flexoelectric plate. The flexoelectric effect is also found to affect the nondimensional frequency and electric potential distribution significantly. Thus, for accurate design of nano/micro scale high precision and high frequency flexoelectric/piezoelectric devices, flexoelectricity must be taken into consideration.
Method of generating roughening paths for shoe soles based on monocular encoded structured light
Authors: Song Limei , Xiang Zhonghao , Wang Yinan , Yang Yangang , Zhu Xinjun , Huang Haozhen
Published: July 2023

In this paper, we propose a monocular encoded structured light-based path generation method for sole roughening, and the obtained paths are used to guide a six-degree-of-freedom (DOF) robot for automatic roughening, which greatly improves the quality and efficiency of roughening. First, we selected monocular structured light as the vision system. To improve the calibration and reconstruction accuracy of the projector, we used an improved Three-Wavelength Phase-Shift Profilometry technique (TWPSP) to calibrate the projector, and the accuracy was improved by 26.29% compared with the conventional method. Then, we proposed a Three Coordinate Scanning Weighted-Principal Component Analysis (TCSW-PCA) algorithm as the path planning system. The experimental results show that the six-DOF-robot can automatically roughen different types of soles according to the generated roughening paths, and the processing efficiency and finished product quality of our proposed method of automatic roughening are better than other roughening methods, with an average improvement of 42% in roughening effect and an average improvement of 30.52% in roughness.