Small Expansion Research Articles

Photopolymerization‐Driven Macroscopic Mechanical Motions of a Composite Film Containing a Vinyl Coordination Polymer

AbstractWe report a unique vinyl coordination polymer (CP), [Zn(4‐Fb)2(tkpvb)]n (1, 4‐HFb=4‐fluorobenzoic acid, tkpvb=1,2,4,5‐tetrakis(4‐pyridylvinyl)benzene) that undergoes a rare photopolymerization reaction to form a two‐dimensional CP integrated with a one‐dimensional linear organic polymer. Upon light irradiation at different wavelengths, 1 exhibits an unprecedented phenomenon of photoinduced nonlinear lattice expansion. 1 can be uniformly dispersed in polyvinyl alcohol (PVA) to form the composite film of 1‐PVA. When this film is exposed to UV light, internal minute stresses within crystallites are released by lattice expansion, resulting in a variety of photopolymerization‐driven macroscopic mechanical motions. The findings provide new insights into the conversion of small lattice expansions of CPs into macroscopic mechanical motions based on photopolymerization reactions, which can promote the development of CPs‐based smart photoactuators in the burgeoning field of microrobotics.

Bayesian optimization with active learning of design constraints using an entropy-based approach

The design of alloys for use in gas turbine engine blades is a complex task that involves balancing multiple objectives and constraints. Candidate alloys must be ductile at room temperature and retain their yield strength at high temperatures, as well as possess low density, high thermal conductivity, narrow solidification range, high solidus temperature, and a small linear thermal expansion coefficient. Traditional Integrated Computational Materials Engineering (ICME) methods are not sufficient for exploring combinatorially-vast alloy design spaces, optimizing for multiple objectives, nor ensuring that multiple constraints are met. In this work, we propose an approach for solving a constrained multi-objective materials design problem over a large composition space, specifically focusing on the Mo-Nb-Ti-V-W system as a representative Multi-Principal Element Alloy (MPEA) for potential use in next-generation gas turbine blades. Our approach is able to learn and adapt to unknown constraints in the design space, making decisions about the best course of action at each stage of the process. As a result, we identify 21 Pareto-optimal alloys that satisfy all constraints. Our proposed framework is significantly more efficient and faster than a brute force approach.

Schistonchus pumilae n. sp. isolated from syconia of a creeper fig, Ficus pumila L. from the Japanese warm temperate zone

Summary A Schistonchus species was isolated from the syconia of the creeping fig, Ficus pumila, collected from Miyazaki, Japan. The nematode was considered an undescribed species based on its typological characters, molecular profiles (near full length of small subunit and D3 expansion segment of large subunit of RNA) and phylogenetic status inferred from these two loci. The new species is characterised by the presence of flagellate sperm, spicule possessing small condylus, triangular rostrum with bluntly pointed tip and clear dorsal and ventral limbs, structure and arrangement of male caudal papillae, i.e., presence of papilliform P3 and P3a and small and gland opening-like P4 (glandpapillae), relatively short post-uterine sac and female tail forming elongate conoid. It is phylogenetically close to S. hirtus. However, the new species is distinguished from other nominal Schistonchus species by its female tail shape forming elongate conoid, the structure and arrangement of male caudal papillae and several other typological characters. In addition, the host fig of the nematode, F. pumila, is a creeper fig species belonging to subgenus Synoecia (section Rhizocladus; subsection Plagiostigma), from which no fig-associated nematode has been reported so far, i.e., the present study is the first report of Schistonchus (and other syconia-inhabiting nematodes) from the Ficus subgenus Synoecia.

SUBLEADING CORRECTION TO THE ASIAN OPTIONS VOLATILITY IN THE BLACK–SCHOLES MODEL

The short maturity limit [Formula: see text] for the implied volatility of an Asian option in the Black–Scholes model is determined by the large deviations property for the time-average of the geometric Brownian motion. In this note, we derive the subleading [Formula: see text] correction to this implied volatility, using an asymptotic expansion for the Hartman–Watson distribution. The result is used to compute subleading corrections to Asian options prices in a small maturity expansion, sharpening the leading order result obtained using large deviations theory. We demonstrate good numerical agreement with precise benchmarks for Asian options pricing in the Black–Scholes model.

Driving Small Business Expansion: Evaluating the Effects of Tax Exemption for Small Enterprises in Albania until 2029

This paper examines the effects of tax exemption on small enterprises in Albania until 2029, with a focus on driving business expansion. The study aims to assess the impact of this fiscal policy on small business growth and explore its implications for the Albanian economy. By evaluating the effects of tax exemption on various dimensions of small enterprises, including revenue generation, profitability, employment, and investment, this research provides valuable insights into the potential benefits and challenges associated with the policy. Drawing on both quantitative and qualitative data, the study employs a comprehensive approach, combining statistical analysis with in-depth interviews of small business owners and key stakeholders. The findings contribute to the existing literature by shedding light on the effectiveness of tax exemption as a tool to promote small business expansion and provide policy recommendations for policymakers and government authorities. The results of this research will inform decision-making processes related to fiscal policies aimed at supporting small businesses, ultimately fostering sustainable economic development in Albania.
 
 Received: 15 January 2023 / Accepted: 18 March 2023 / Published: 20 March 2023

Beef and pork processing plant labor costs

AbstractFederal and state legislators recently enacted policies to fund new and renovated small and local meat processors expansion with the aim of increasing the meat‐processing sector's resiliency. Wages must be competitive to attract employees for these new and renovated plants to be competitive. No previous studies have examined what has happened to employee labor costs at United States (US) meat‐processing plants since the early 2000s. This study estimates how meat‐processing firm size affects employee wages in the US. We use average employee wages for beef and pork processing plants from 2007 to 2019. We find larger plants pay higher wages than smaller ones, which is likely attributable to lower fixed costs resulting from economies of scale. Findings suggest that facilities with more than 500+ employees will most likely offer wage that are high enough to recruit workers in for this industry. Small plants will need to increase real wages that are higher than historical averages. Thus, if smaller facilities increase the sector's resiliency, then it will likely come at a cost in terms of higher wage bills. [EconLit Citations: Q12, Q18].

Strain fields and critical phenomena in manganites II: spin-lattice-energy Hamiltonians

The dynamic critical behavior at the paramagnetic-antiferromagnetic (PM-AFM) transition in manganites has recently been studied experimentally (Niermann et al 2015 Phys. Rev. Lett. 114 037204). We extend the Hamiltonian of paper I by incorporating an energy field, and study the corresponding Model C of critical dynamics. We use the dynamic renormalization group approach and calculate the dynamic critical exponents z, and the line-width exponent Δ to leading order in the small expansion parameters and . Here, d is the space dimension and σ is the long-range exponent. Using σ as an adjustable parameter, the theory gives us a good match to the experimentally available static and dynamic critical exponents at the PM-AFM transition.

Semiclassical analysis of Dirac fields on curved spacetime

We present a semiclassical analysis for Dirac fields on an arbitrary spacetime background and in the presence of a fixed electromagnetic field. Our approach is based on a Wentzel-Kramers-Brillouin approximation, and the results are analyzed at leading and next-to-leading order in the small expansion parameter $\ensuremath{\hbar}$. Taking into account the spin-orbit coupling between the internal and external degrees of freedom of wave packets, we derive effective ray equations with spin-dependent terms. These equations describe the gravitational spin Hall effect of localized Dirac wave packets. We treat both massive and massless Dirac fields and show how a covariantly defined Berry connection and the associated Berry curvature govern the semiclassical dynamics. The gravitational spin Hall equations are shown to be particular cases of the Mathisson-Papapetrou equations for spinning objects.

INVASION POTENTIAL OF DAREVSKIA ARMENIACA (MEHELY, 1909) IN UKRAINE: ASSESSMENT BASED ON GIS MODELING

The article is devoted to the actual problem of determining the invasive potential of the invader species, the Armenian rock lizard Darevskia armeniaca. A population of introduced parthenogenetic rock lizards Darevskia armeniaca has existed in the canyon of the Teteriv River (Zhytomyr region, Ukraine) for about 60 years. Their presence in the herpetofauna of Ukraine is the result of a scientific experiment aimed at studying the processes of acclimatization and the existence of a local population of clones in a limited area, the possibilities of hybridogenesis of parthenogenetic and bisexual species and other issues of population genetics.
 The invasive potential of rock lizards in this area was studied by the method of bioclimatic modeling of the ecological niche. The material was based on data from the Global Biodiversity Information System (GBIF.org (03 November 2021) GBIFOccurrenceDownload. To model the ecological niche, 19 bioclimatic variables, average monthly data on solar radiation intensity for the modern period (1970-2000), data on altitude from the WorldClim 2.1 database were used. Most of the significant parameters of the ecological niche for the introduced population are in the lower pessimum zone. The model built based on the entire collection of points of registration of the species shows that the territory where the species was introduced in Ukraine is one of the least suitable. Nevertheless, the population of introduced parthenogenetic rock lizards is now stable, thriving, numerous and slightly expanding its range by inhabiting new territories. Obviously, favorable conditions for the existence of D. armeniaca here are determined not by macroclimatic factors, but by microclimatic ones.
 The analysis of the model built on the basis of points of registration of the species in the introduced population shows that under existing climatic conditions, wide expansion of the species in this region of Ukraine is not possible, although a small expansion of its range is quite likely. There is also no reason to predict the transition of rock lizards to the number of invasive species.

Two new species of Pseudaphelenchus (Aphelenchoididae: Tylaphelenchinae) isolated from pine wood in Guangdong Province, China

Summary Pseudaphelenchus is considered an intermediate between tylenchids and Aphelenchoididae because it has both a tylench-like bursa and aphelench-like pharynx. Three nematode populations within this genus representing two new species, P. guangdongensis n. sp. and P. paraguangdongensis n. sp., were discovered from pine trees in Guangdong province, China. P. guangdongensis n. sp. most closely resembles P. vindai due to the possession of three lines in their lateral fields, whereas P. paraguangdongensis n. sp. is most like P. yukiae because they share a four-lined field. Morphological and morphometric differences of these two new species and similar species are discussed. Additionally, molecular phylogenetic trees inferred from rRNA small subunit and D2-D3 expansion domains of the rRNA large subunit revealed that P. guangdongensis n. sp. and P. paraguangdongensis n. sp. are separated from all known Pseudaphelenchus species; moreover, all Pseudaphelenchus species comprise a highly supported monophyletic clade, which is basal to the family Aphelenchoididae.

The flow and heat in the conical region of a rotating cone and an expanding disk

Purpose The fluid flow and heat transfer between a rotating cone above a stretching disk is the prime purpose of the current work. Making use of suitable similarity transformations, it is shown that the physical phenomenon is represented by a system of similarity equations, which is compatible with that of literature in the absence of wall expansion. Design/methodology/approach Numerical simulation of the system enables us to seize the physical character of fluid filling the conical section as well as of the heat transfer, from small to adequately large gap sizes. How the surface expansion will contribute to the momentum and thermal layers; moreover, to the swirl angle from the disk wall, and heat transports from the cone and disk surfaces is studied in detail. Findings The results are clear evidences that the wall stretching completely changes the flow and heat behaviors within the conical gap. For instance, the centripetal/centrifugal flow properties of disk/cone are completely altered and the flow swirling angles are increased by means of the wall deformation. Originality/value The original value is that at small gap angles faster expansion of the wall overall leads to near-disk surface cooling, while causing the heated region near the cone surface, which has physical implications in practical applications.

3D ordered amorphous and porous TiO2 framework anode with low insertion barrier and fast kinetics for K-ion hybrid capacitors

TiO2 is considered as a low cost, long-term stable, and safe anode for high power K-ion hybrid capacitors (KICs) due to its abundant reserve, small volume expansion rate, and sloping voltage plateau that avoids K-ion plating at high voltage polarization. However, the enhancement of its low capacity and sluggish kinetics caused by poor electroconductivity and high insertion barrier is still challenging to further develop high-performance KICs. Herein, the reduced graphene oxide (rGO) is embedded in the walls of 3D ordered macro-/mesoporous TiO2 (termed as TiO2@rGO framework) to create intimate TiO2/rGO interfaces, ensuring the effectively electron transportation during potassiation/depotassiation of TiO2 while maintaining rapid ions/electrolyte diffusion. Furthermore, the controlled amorphous TiO2 framework can further lower the lattice insertion energies, contributing to a fast accommodation of K-ion. As expected, the amorphous TiO2@rGO framework (TiO2@rGO-1) exhibits a superior rate capability (148.8 mAh g−1 at 5 A g−1) and cycling stability (171.2 mAh g−1 at 1 A g−1 after 800 cycles). The assembled KICs can reach a high energy/power density of 125.2 Wh kg−1/4267.4 W kg−1 as well as a long-term lifespan. This tactic provides a reliable and general way to design a TiO2-based anode with fast kinetics toward high-performance KICs.

Offshore wind power prediction method considering typhoon, cold wave and other meteorological features under transitory weather

With the large-scale development of offshore wind farms, China's offshore wind power process is becoming more and more perfect. How to accurately forecast offshore wind power, especially under the influence of transitional weather, is a difficult problem to be solved. Therefore, in order to accurately forecast offshore wind power in the extreme small sample event, this paper proposes a method for predicting wind power before the turning weather based on meteorological element selection and small sample learning and expansion. The method improves the prediction accuracy of offshore wind power under typhoons and cold waves by constructing meteorological features in transitional weather such as typhoons and cold waves, expanding the small sample using time series, and modelling the relationship between the expanded meteorological factors and wind power.

Penta-SiCN monolayer as a well-balanced performance anode material for Li-ion batteries.

Lithium-ion batteries (LIBs) remain irreplaceable for clean energy storage applications. The intrinsic metallic nature of penta-SiCN ensures its promising application in the electrodes of LIBs. Using first-principles calculations, we evaluate the performance of the intrinsic metallic penta-SiCN monolayer as the anode material for LIBs. Penta-SiCN exhibits a low diffusion energy barrier (0.107 eV) for Li atom migration on Si18C18N18, while the diffusion energy barrier for vacancy migration on Li17Si18C18N18 is only 0.006 eV. Additionally, penta-SiCN possesses a high theoretical capacity of 1485.98 mA h g-1, average open-circuit voltage of 0.97 V, and small volume expansion of 1%. Remarkably, penta-SiCN exhibits robust wettability towards the electrolytes (solvent molecules and metal salts) widely used in commercial LIBs, indicating the excellent compatibility in electrode applications. These intriguing theoretical findings make penta-SiCN a high performance anode material for LIBs.

Li/Na atoms' substitution effects on the structural, electronic, and mechanical properties of the CaSnO3 perovskite for battery applications

Calcium stannate perovskite CaSnO3 (CSO) is an interesting material for lithium- and sodium-ion batteries (LIBs and SIBs), due to their high hardness and mechanical resistance. In this work, we systematically investigate the effects of substituting lithium/sodium (Li/Na) atoms on the structural, electronic, and mechanical properties of LixCa1-xSnO3 and NaxCa1-xSnO3 perovskite compounds with concentrations × = 0.00, 0.25 and 0.50 using DFT-based in the generalized gradient approximation (GGA) and norm-conserving pseudopotential. This allows describing which substitution generates optimal conditions for structural, mechanical stability, and electronic properties for the CSO perovskite.Lattice parameters behavior as a function of the concentration shows a gradual decrease (increase) in a and c as Li (Na) amount increases. The Na configurations show a small volumetric expansion, on the other hand, the Li configurations have contractions. According to the cohesive energy analysis, it is demonstrated that Li concentrations are more stable than Na ones. The electronic band structure shows that all the Li and Na configurations have a metallic behavior. Finally, the mechanical properties indicate that Na degrades in a less proportion than the Li-substituted compounds; these results demonstrate that SIBs are more favorable than LIBs.

A facile complexing chemical reduction for the preparation of Sn/graphene nanocomposites and their high performance for lithium-ion batteries

The pursuit of simpler and more efficient methods for the preparation of high-performing lithium-storage materials is always considered to be an important job for researchers interested in lithium-ion batteries. Herein, a facile complexing chemical reduction strategy is successfully developed for the preparation of newly advanced Sn/graphene (Sn/G) nanocomposite as anode material LIBs. The complexing reagent of ethylenediamine tetraacetate disodium (EDTA-2Na) and reducing agent of NaBH4 added in the preparation process are both found to play pivotal roles in the controllable reduction of Sn2+ and formation of highly conductive graphene matrix. The Sn/G nanocomposite exhibits a loosely stacked structure with ultrafine Sn nanoparticles (20–40 nm) uniformly dispersing on graphene nanosheets. This specially designed morphology is proved to be beneficial for electrolyte infiltrating and highly efficient transport of Li-ions. The Sn/G nanocomposite displays outstanding lithium storage up to 1032 mAh g−1 after 150 cycles and a high rate performance of 535 mAh g−1 at 1 A g−1. The highly conductive and flexible network of graphene effectively alleviates the small absolute volume expansion of ultrafine Sn nanoparticles and maintains the structure stability. In addition, a fair low-temperature performance of 322 mAh g−1 at − 20 °C was also achieved due to the excellent structural features of the Sn/G nanocomposite. The work has managed to provide a simple and reliable method for the synthesis of Sn/C material as well as a potential candidate for low-temperature lithium storage applications.

Theory of thermal properties of magnetic materials with unknown entropy

Theoretical approaches to study thermal properties of magnetic materials typically require accurate models of magnetic interactions in order to define the entropy. Here we introduce a complementary approach for examining thermal properties in magnetic systems where an accepted model for such interactions does not exist. In place of a specific model for magnetic interactions, the approach integrates measurements of temperature dependent magnetization of the studied material into a first principles computational scheme. The approach calculates system pressure from thermally disordered microstates that properly incorporate vibrational and spin subsystems at each temperature as well as the coupling between these subsystems. We apply the approach to calculate phonon modes and to investigate the anomalously low thermal expansion of the classical Invar alloy ${\mathrm{Fe}}_{0.65}{\mathrm{Ni}}_{0.35}$. The calculated phonon dispersions for Invar are in excellent agreement with measured data. The Invar thermal expansion is shown to remain small between 50 K and room temperature, consistent with the experimentally observed low thermal expansion value in this same temperature range. This anomalously small thermal expansion is directly connected to a small positive contribution from lattice thermal disorder that is nearly canceled by a large negative magnetic disorder contribution. By contrast, calculations for bcc Fe show a much larger thermal expansion, consistent with experiment, which is dominated by a large contribution from lattice thermal disorder that is reduced only slightly by a small negative contribution from that of magnetism. These findings give insight into the unusual nature of magnetism and spin-lattice coupling in Invar and Fe. In addition, they give promising preliminary support to the presented methodology as a complementary way to investigate thermal properties of magnetic materials. The success achieved on Invar and Fe motivates future testing of the approach on other magnetic materials.

Negative inductor effects in nonlinear two-dimensional systems: Oscillatory neurons and memristors

Many chemical and physical systems show self-sustained oscillations that can be described by a set of nonlinear differential equations. The system enters oscillatory behavior by an intrinsic instability that leads to bifurcation. We analyze conducting systems that present oscillating response under application of external voltage or current. Phenomena like electrochemical corrosion and the spiking response of a biological neuron are well-known examples. These systems have applications in artificial neurons and synapses for neuromorphic computation. Their dynamical properties can be characterized by normal mode analysis of small expansion of the constituent nonlinear equations. The linearized model leads to the technique of ac frequency response impedance spectroscopy that can be obtained experimentally. We show a general description of two-variable systems formed by a combination of a fast variable (the voltage) and a slowing down internal variable, which produce a chemical inductor. A classification of bifurcations and stability is obtained in terms of the parameters of the intrinsic equivalent circuit including the case of a negative inductor. Thereafter, we describe a number of physical examples and establish the characterization of their properties: The electrocatalytic reaction with adsorbed intermediate species, an oscillating metal oxide memristor, and finally we discuss the signs of the equivalent circuit elements in the central model of neuroscience, the Hodgkin–Huxley model for an oscillating neuron.

Pure Anti-de Sitter Supergravity and the Conformal Bootstrap.

We consider graviton scattering in maximal supergravity on anti-de Sitter space (AdS) in d+1 dimensions for d=3, 4, and 6 with no extra compact spacetime factor. Holography suggests that this theory is dual to an exotic maximally supersymmetric conformal field theory (CFT) in d dimensions whose only light single trace operator is the stress tensor. This contrasts with more standard cases like type IIB string theory on AdS_{5}×S^{5} dual to N=4 super-Yang-Mills, where the CFT has light single trace operators for each Kaluza-Klein mode on S^{5}. We compute the one-loop correction to the pure AdS_{d+1} theory in a small Planck length expansion, which is dual to the large central charge expansion in the CFT. We find that this correction saturates the most general nonperturbative conformal bootstrap bounds on this correlator in the large central charge regime for d=3, 4, 6, while the one-loop correction to CFTs with string and M-theory duals all lie inside the allowed region.

Four-loop QCD cusp anomalous dimension at small angle

We calculate the small angle expansion of the four-loop QCD cusp anomalous dimension. As a byproduct of our calculation, we also obtain the four-loop anomalous dimension of the heavy-quark field in HQET. The validity of the calculational setup is cross-checked by the independent calculation of the four-loop QCD beta-function from heavy-quark-gluon vertex renormalization in HQET. We check the obtained results for the cusp anomalous dimension and heavy-quark field anomalous dimension against available analytical and numerical results. Finally, we find that the maximal transcendentality contribution to the QCD Bremsstrahlung function coincides, up to a factor 3/2, with the Bremsstrahlung function in mathcal{N} = 4 supersymmetric Yang-Mills theory, at least, through 4 loops.