Specific Properties Research Articles

Theoretical Design of Thorium Nitride MXenes.

Actinides with 5f6d7s valence orbitals feature special physicochemical properties different from those of the other elements. Actinide-based two-dimensional (2D) materials combine the distinctive physics of actinides with the quantum size effect of 2D materials, but relevant studies are scarce. Since Th has a valence electron configuration of 6d27s2 like Ti, and Ti-based MXenes show excellent stability and versatile applications, whether Th can form stable MXenes has become an intriguing question. Herein, we designed Th2N, Th3N2, and Th4N3 MXenes and investigated their physical properties, functionalization, and potential applications using density functional theory. Their stabilities are validated by global minimum search, phonon spectra, ab initio molecular dynamics, enthalpy of formation, and energy above the hull. All the Th-N MXenes exhibit metallic properties and are stabilized by the electrostatic interaction between Th and N ions, as well as the covalent bonding interaction between the Th 6d/5f and N 2p/2s orbitals. The H-, O-, and F-functionalization3N2 MXene improve its stability while preserving its metallicity, and the O-functionalized Th3N2 MXene shows promising catalytic activity for hydrogen evolution. The thorium nitride MXenes enrich the family of actinide-based 2D materials and extend our understanding of the structures and properties induced by actinide elements in low-dimensional materials.

Anthropogenic noise and impact on marine species : Acoustic metamaterials as a reduction solution

Anthropogenic underwater noise generated by offshore maritime activities poses a significant threat to nearby ecosystems due to elevated sound levels. Efforts have to be undertaken on noise reduction solutions, depending both on the offshore activities and on the marine species. In this context, leveraging the recent advances in underwater acoustic metamaterials seems crucial, due to their special properties in terms of scattering and absorption. This endeavor aligns with advancing Marine Renewable Energies while minimizing environmental impact. In this communication, a synthetic review is first proposed to define the various maritime works targeted, as well as their associated sound levels and frequency ranges of emission. In a second part, a cartography is outlined by classifying different marine species according to their hearing type, depth of immersion and auditory threshold. Then, in relation with the two previous analyses, solutions based on metamaterials for deep sea immersions are proposed. In particular, a multi-periodic arrangement of bars is proposed that exhibits several band gaps (i.e. frequency ranges in which propagation is forbidden), in order to limit the transmission of sound waves in a large frequency range. The concept can be easily extended depending on the targeted offshore activities and marine species.

Chebyshev subdivision and reduction methods for solving multivariable systems of equations

We present a new algorithm for finding isolated zeros of a system of real-valued functions in a bounded interval in Rn. It uses the Chebyshev proxy method combined with a mixture of subdivision, reduction methods, and elimination checks that leverage special properties of Chebyshev polynomials. We prove the method has quadratic convergence locally near simple zeros of the system. It also finds all nonsimple zeros, but convergence to those zeros is not guaranteed to be quadratic. We also analyze the arithmetic complexity and the numerical stability of the algorithm and provide numerical evidence in dimensions up to five that the method is both fast and accurate on a wide range of problems. Our tests show that the algorithm outperforms other standard methods on the problem of finding all real zeros in a bounded domain. Our Python implementation of the algorithm is publicly available at https://github.com/tylerjarvis/RootFinding.

SPECIAL LEGAL CAPACITY OF LAWYERS: LAWYER, NOTARY AND EXECUTOR

The research object of this paper is the special legal capacity of lawyers, specifically, the special legal capacity for the performance of advocacy activities, regulated by the Law of Advocacy, the special legal capacity for providing notarial services, according to the Law on notaries, and the special legal capacity of the executors, according to the Law on Enforcement. Full legal capacity is the abstract possibility of physical and legal persons to be the provider of rights and obligations. All physical persons have full legal capacity, however, some physical persons, because they fulfill special properties, acquire special legal capacity. The research in this paper has two mail purposes. The first intention is to analyze two assumptions necessary for achieving the special legal skills: 1. professional technical conditions requirements that must be completed by the natural person to operate the professional activities and 2. providing the authorization by the government. The second goal is to show the specifics of the three types of professional activities, notion, acquire, cease and termination. The project will analyze more closely the termination of the special legal capacity because of the loss of one from the two-expectations necessary for its acquisition (obtaining a lawyer's license, terminating the notary or the executor).

Cu-trimesate and mesoporous silica composite as adsorbent showing enhanced CO2/CH4 and CO2/N2 selectivity for biogas and flue gas separation

Due to their diverse structure, high porosity, and tunable functionality, Metal-Organic Frameworks (MOFs) hold great potential as materials for diverse applications, including gas separation. Material science researchers are focusing on creating flexible materials that have special properties. Most of the latest research mainly concentrates on fabricating composite materials of MOFs and other functional materials. These MOF-based composites can mitigate the limitations of pure MOFs and may even perform better than the individual components. Here, we present a systematic study on the effect of solvent in synthesising a composite (Cu-BTC@SBA-15) of Cu-trimesate MOF (aka CuBTC) and ordered mesoporous silica SBA-15, showing considerable improvement in selectivity for CO2 adsorption from the flue gas and biogas. The pristine Cu-BTC, SBA-15 and the composites with different content of Cu-BTC were characterized by PXRD, BET, FT-IR, SEM, TEM and TGA techniques. The pure gas adsorption isotherms were measured for CO2, CH4, and N2 gases. Ideal Adsorbed Solution Theory (IAST) is used for the binary selectivity calculations for gas systems such as CO2/CH4 and CO2/N2 in the context of biogas and flue gas separation. The composite exhibited an increase in CO2/CH4 selectivity by 39 % compared to pure Cu-BTC and 85 % compared to pure SBA-15. For the CO2/N2 system, the composite showed 38 % higher selectivity than Cu-BTC. The work has significance in the design of effective MOF-based composites for CO2 separation. Our work might open up a new route to design multifunctional materials for worldwide applications through an adsorptive and or mixed matrix membrane route.

Deep insight into the effect of smithsonite particle size on surface heterogeneity and adsorption behavior: A case of fatty acid system

The studies for microfine mineral flotation have focused on the two main directions of increasing the apparent mineral particle size and reducing the bubble size, while little research has been reported on the special surface properties and adsorption mechanisms of mineral particles of different sizes. In this study, sodium oleate was chosen as a typical surfactant. The mechanism of the effect of smithsonite particle size on the heterogeneity and adsorption behavior of the mineral surface was explored in depth. Through microflotation experiments, BET area tests, Washburn contact angle tests, particle agglomeration tests, adsorption tests and inorganic carbon analysis, it was pointed out that the smaller the size of the particles, the greater the surface wettability, and the smaller the density and thickness of adsorbed oleate on the surface. The difficulty of encapsulating the mineral surface with a hydrophobic layer of oleate hydrocarbon chains, as well as suboptimal particle aggregation sizes, are key reasons for the poor flotation behavior of fine smithsonite. Furthermore, the inhomogeneity of active sites and charge distribution of surface components of smithsonite with different sizes was revealed from a microscopic point of view by DRIFT spectroscopic analysis, XPS analysis and zeta potential measurements. As the particle size of smithsonite decreases, the positive charge density on the surface is higher and the hydration tendency is more intense, hindering the adsorption of oleate. This work is expected to guide the full particle size recovery of minerals in the flotation from a novel microscopic point of view.

Specification and ω-chaos in non-compact systems

In this paper, we demonstrate conditions under which a Lindelöf dynamical system exhibits ω-chaos. In particular, if a system exhibits a generalized version of the specification property and has at least three points with mutually separated orbit closures, then the system exhibits dense ω-chaos.

Observation on Switching Properties of WO3-Based H2 Sensor Regulated by Temperature and Gas Concentration.

Transition metal oxide semiconductors have great potential for use in H2 sensors, but in recent years, the strange phenomena about gas-sensitive performance associated with their special properties have been more widely discussed in research. In some cases, the resistance of transition metal oxide gas sensors will emerge with some changes contrary to their intrinsic semiconductor characteristics, especially in gas sensor research of WO3. Based on the hydrothermal synthesis of WO3, our work focuses on the abnormal change of tungsten oxide resistance to different gases at low temperature (80-200 °C) and high temperature (above 200 °C). Through in situ FT-IR and in situ XPS, combined with density functional theory calculations, a new reasonable explanation of WO3 is proposed for the abnormal resistance change caused by temperature and the strange response due to gas concentration. The occurrence of these findings can be attributed to the synergistic effect resulting from the presence of two contributing factors. One of them is attributed to the alteration in the surface valence state of WO3 induced by gas, resulting in the reduction of W6+. The other one is due to the reaction between gas and adsorbed oxygen on the surface of WO3. This work presents a novel and rational concept for addressing the reaction mechanism between gas and transition metal oxide semiconductors, thereby paving the way for the development of highly efficient gas sensors based on transition metal oxide semiconductors.

Probing the role of hydrogen bond donors on the speciation and electrochemical behavior of Eu(III) in choline chloride-based DESs

This study explores the electrochemical properties and speciation of Eu(III) ions in choline chloride (ChCl)-based deep eutectic solvents (DESs), focusing on how different hydrogen bond donors—urea (U), ethylene glycol (EG), and malonic acid (MA)—influence the stability of europium complexes. Employing electrochemical methods, spectroscopic analysis, and theoretical approaches, the research examines how changes in hydrogen bonding during complexation affect Eu(III) coordination. Cyclic voltammetry highlights the role of complex formation and DES viscosity in controlling mass transport and electron transfer rates. Theoretical and experimental data show that the ChCl:1MA DES forms the most stable europium complex, driven by strong hydrogen bonding and robust Eu-DES interactions, as supported by optimized geometries and favorable electrochemical stability. This stability is further confirmed by the high negative binding and formation free energies of Eu(NO3)3·5H2O in all three DES systems. Photoluminescence spectroscopy reveals fluorophore formation due to interactions between hydrogen bonds and functional groups such as –NH2, –COOH, and –OH, enhancing the understanding of Eu3+-DES complexes for potential applications in materials science. By clarifying how hydrogen bond donors affect Eu(III) speciation and reactivity, this research advances lanthanide chemistry in DESs and opens avenues for designing Eu(III)-based materials with specialized properties for various technological uses.

EVALUATION OF TECHNOLOGICAL PLASTICITY OF HIGH BORON CORROSION-RESISTANT STEEL DURING HOT DEFORMATION OF PIPES USED FOR SPENT NUCLEAR FUEL STORAGE

Statement of the problem. The sustainable development of the global nuclear power industry in the future depends on how effectively the problems of radiation safety and nuclear proliferation are addressed. Such problems occur, among other things, at the final stage of the nuclear fuel cycle – spent fuel management. This task is currently on the agenda of both the international community and national governments of countries that develop or intend to develop nuclear energy [1−3]. Today, in connection with ensuring the safety of nuclear energy, boron-containing steels are widely used in the world practice as a material for biological protection and for the manufacture of special equipment parts. This is due to the fact that the B10 isotope in steels provides neutron capture [4]. Hexagonal pipes made of high-boron steel were needed to shield the support cover of the compacted spent fuel storage facility at nuclear power plants. Corrosion-resistant steels alloyed with boron are widely used in the nuclear power industry due to their special nuclear properties. During the operation of nuclear power plants, fuel assemblies that have served their useful life must be stored in special storage facilities using containers – hexagonal tubes made of 04Сr14Ti3B2V steel. To reduce costs during in the construction and operation of NPPs, part of the spent nuclear fuel management should be performed at Ukrainian enterprises. This will provide a significant import substitution effect. To manufacture hexagonal tubes from 04Сr14Ti3B2V steel according to the ingot-hot deformation-profiling-heat treatment scheme, it is necessary to develop the parameters of hot deformation and subsequent technological operations. The use of these pipes in compacted spent fuel storage facilities of NPPs will allow to increase the storage capacity by 2 times, which will give a significant national economic effect Material and methods of research. Material used for the study was steel 04Сr14Ti3B2V (CS-82), smelted using two variants (vacuum-induction – “VI” and vacuum-induction followed by vacuum-arc remelting – (“VD”). Steel grade 04Сr14Ti3B2V belongs to high-alloy, corrosion-resistant ferritic steels with a high boron content of up to 2 %. The method of differential thermal analysis was used to study the phase transformation temperatures in the steel. X-ray diffraction and micro-X-ray spectral analysis were used to assess the phase state. The steel samples were tested for weldability After cooling, the welded samples were subjected to X-ray transmission [5]. Hot twisting tests and mechanical tests at high temperatures were also performed. The macro- and microstructure of the metal was studied. Results. The macro- and microstructure of steel was evaluated depending on the smelting method. The phase composition of the steel was studied. The study of the plastic properties of steel ChS-82 by means of penetration and hot twisting tests showed that the temperature range of maximum plasticity is in a wide range (from 1 025 to 1 150 0C) with a rather low resistance to deformation. During hot deformation in the temperature range of 1 175 0C and above, metal fracture was observed along the grain boundaries at the melting points of the Cr−Fe−B boride phase. The optimal temperature range for hot deformation of steel ChS-82 is 1 000−1 050 ⁰С. Scientific novelty. For corrosion-resistant high boron steel used for spent nuclear fuel storage, the temperature range of hot deformation was selected and the structural and phase composition was estimated, which will allow deforming the metal on the piercing mill and manufacturing pipes.

The amalgamated impact of bimetals, amino groups, and cross-linked structures of MOF on MOF for the removal of cationic dyes

To protect the environment, it is important to develop effective materials/methods for eliminating or decomposing pollutants. Metal-organic frameworks (MOFs) have attracted considerable interest due to their special properties, including their exceptional porosity and customizable architecture, which make them highly adaptable for many applications. In this study, bimetallic (Ce/Zr) NH2-UiO-66@NH2-MIL-125 was prepared and characterized by, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric and BET analysis. The prepared bimetallic (Ce/Zr) NH2-UiO-66@NH2-MIL-125 served as a potent adsorbent for the efficient removal of cationic dyes via electrostatic, hydrogen bonding, ionic bonding, and π–π stacking. The adsorption of RhB and MB dyes by bimetallic (Ce/Zr) NH2-UiO-66@NH2-MIL-125 includes both isothermal and kinetic studies. The equilibrium adsorption data was found to conform to the Langmuir isotherm, whereas the kinetic adsorption process followed a pseudo-second-order model. The cross-linked structure of MOF on MOF enhances the stability of the adsorbent, and has the potential to efficiently adsorb and release organic dyes over multiple cycles. The aforementioned interactions as well as stability and reusability make the bimetallic (Ce/Zr) NH2-UiO-66@NH2-MIL-125 one of the most promising adsorbent for the removal of dyes from water.

An empirical isochrone archive for nearby open clusters

Context. The ages of star clusters and co-moving stellar groups contain essential information about the Milky Way. Their special properties and placement throughout the galactic disk make them excellent tracers of galactic structure and key components to unlocking its star formation history. Yet, even though the importance of stellar population ages has been widely recognized, their determination remains a challenging task often associated with highly model-dependent and uncertain results. Aims. We propose a new approach to this long-standing problem, which relies on empirical isochrones of known clusters extracted from high-quality observational data. These purely observation-based data products open up the possibility of relative age determination, free of stellar evolution model assumptions. Methods. For the derivation of the empirical isochrones, we used a combination of the statistical analysis tool principal component analysis for preprocessing and the supervised machine learning method support vector regression for curve extraction. To improve the statistical reliability of our result, we defined the empirical isochrone of a color-magnitude diagram (CMD) of a cluster as the median calculated from a set of nboot = 1000 curves derived from bootstrapped data. The algorithm requires no physical priors, is computationally fast, and can easily be generalized over a large range of CMD combinations and evolutionary stages of clusters. Results. We provide empirical isochrones in all Gaia DR2 and DR3 color combinations for 83 nearby clusters (d < 500 pc), which cover an estimated age range of 7 Myr to 3 Gyr. In doing so, we pave the way for a relative comparison between individual stellar populations based on an age-scaling ladder of empirical isochrones of known clusters. Furthermore, due to the exceptional precision of the available observational data, we report accurate lower main sequence empirical isochrones for many clusters in our sample, which are of special interest as this region is known to be especially complex to model. We validate our method and results by comparing the extracted empirical isochrones to cluster ages in the literature. We also investigate the added information that empirical isochrones covering the lower main sequence can provide on case studies of the IC 4665 cluster and the Meingast 1 stream. Conclusions. The archive of empirical isochrones offers a novel approach to validating age estimates and can be used as an age-scaling ladder or age brackets for new populations and serve as calibration data for further constraining stellar evolution models.

Progress of Hole-Transport Layers in Mixed Sn-Pb Perovskite Solar Cells.

Hybrid organic-inorganic lead halide perovskite solar cells (PSCs) have rapidly emerged as a promising photovoltaic technology, with record efficiencies surpassing 26%, approaching the theoretical Shockley-Queisser limit. The advent of all-perovskite tandem solar cells (APTSCs), integrating Pb-based wide-bandgap (WBG) with mixed Sn-Pb narrow-bandgap (NBG) perovskites, presents a compelling pathway to surpass this limit. Despite recent innovations in hole transport layers (HTLs) that have significantly improved the efficiency and stability of lead-based PSCs, an effective HTL tailored for Sn-Pb NBG PSCs remains an unmet need. This review highlights the essential role of HTLs in enhancing the performance of Sn-Pb PSCs, focusing on their ability to mitigate non-radiative recombination and optimize the buried interface, thereby improving film quality. The distinct attributes of Sn-Pb perovskites, such as their lower energy levels and accelerated crystallization rates, necessitate HTLs with specialized properties. In this study, the latest advancements in HTLs are systematically examined for Sn-Pb PSCs, encompassing organic, self-assembled monolayer (SAM), inorganic materials, and HTL-free designs. The review critically assesses the inherent limitations of each HTL category, and finally proposes strategies to surmount these obstacles to reach higher device performance.

Drug Delivery System That Self-Emulsify: Transportation of Drug From Gut to Target Organs

Microemulsions are highly popular for their specific uses, including vivid applications and this is due to their special properties, which include very high interfacial interactions with demonstrated stability from a thermodynamics point of view, and on the other hand, also very low interfacial tension, which is required to solubilize highly immiscible dispersions. This review’s goal is to briefly outline potential uses of micro-emulsion systems, their uses, limitations and possible in-vitro and in-vivo techniques. To characterise such dispersion systems, it is commonly known that adding the right surfactant or surfactant mixture can combine large amounts of two non-dissolving-target liquids, such as water and oil, into a single phase that is macroscopically homogeneous but microscopically heterogeneous. Owing to the advantages of lymph drug delivery, the drug-lipid conjugates, when they enter the lymph route, become an ideal approach for enhancing the absorption of such drugs to combat metastatic cancers of the lymph nodes and their drainage to specific organ systems where the cancer is already spread. As the route of lymph delivery is important where a tumor has already been cancerous, this formulation approach has distinct opportunities to transport needy molecules to cancerous sites in various organs, which also includes the lymph nodes. This review, particularly, lays more stress on an overview of microemulsions in general, the in-vivo and in-vitro characterization methods and potential applications related to target drug delivery via the lymphatic circulatory system.

Emerging chemistry in improving the metabolism or degradability of organic/polymeric conjugated materials for biomedical applications

AbstractOrganic/polymeric conjugated materials are playing an increasingly important role in biomedical field. Their special properties such as fluorescence, photosensitization, and photothermal conversion make them promising candidates for disease diagnosis and phototherapy. However, these conjugated materials are usually extremely hydrophobic, so they tend to take a relatively long time to be excreted or metabolized after theranostics, leading to unpredictable side effects, which has made their clinical implementation a daunting task. In this review, we will focus on the safety of organic/polymeric conjugated materials for biomedical applications and discuss in detail the general strategies to improve their metabolism or degradability by rational molecular design, based on representative examples. Finally, the challenges and opportunities are also presented by considering further perspectives.

Hausdorff dimension of the parameters for (α,β)-shifts with the specification property

In this paper, we consider the specification property for ( α , β ) -shifts. When α = 0 , Schmeling shows that the set of β > 1 for which the β-shift has the specification property has the Lebesgue measure zero but has the full Hausdorff dimension [Schmeling. Symbolic dynamics for β-shifts and self-normal numbers, Ergodic Theory Dyn. Syst. 17 (1997), pp. 675–694]. So it is natural to ask what happens when α > 0 . Buzzi shows that for fixed α the set of β > 1 for which the ( α , β ) -shift has the specification property has Lebesgue measure zero. Hence we consider the Hausdorff dimension of the parameter space of ( α , β ) -shifts.

Polysaccharides from Inonotus obliquus employing subcritical water extraction: Extraction optimization, physiochemical properties and bioactivities analysis

As one of the main components in Inonotus obliquus, polysaccharides was potentially to be developed for the special physiochemical properties and bioactivity. However, the low extraction efficiency of Inonotus obliquus polysaccharides (IOP) significantly hindered the in-depth research and development. To achieve a higher extraction yield of IOP, subcritical water was selected and optimized by Box-Behnken Design (BBD) with a more reasonable yield investigation method in the present study. In addition, for the comparative analysis, the physiochemical properties and bioactivity of the subcritical water extracted polysaccharides (IOP-S), purified polysaccharides (IOP-P) and hot water extracted polysaccharides (IOP-W) were all investigated and analyzed. The results showed that the optimal extraction conditions were 200°C, 13.24 min and 30:1 (mL/g), which corresponded to a polysaccharide yield of 14.14±0.17 %. With simple purified process, the IOP-P with high purity (total sugar content of 87.55 %) was suitable for the further study. Compared to IOP-W, a wider molecular weight range (3.4–98 kDa) of polysaccharide was found in IOP-S, as well as higher sugar and polyphenol content, which might be the main reason for the well antioxidant and digestion enzyme inhibition activity. There were also various differences in the monosaccharide composition, micro-morphology and other physiochemical properties, which all suggested that the subcritical water could efficiently extract a special IOP for the fourthly study and development. In summary, the present study proved that subcritical water extraction could significantly improve the extraction efficiency of IOP, and the basic information in physiochemical properties and bioactivities of IOP would promote the development of IOP in the future.

Why shouldn't teacher education produce ‘ready-to-teach’ graduates? Mapping a pathway to alternative teacher education and teacher becomings

ABSTRACT Teacher education reforms worldwide have reinforced a narrative that ‘high-quality’ teaching and teachers are the most significant contributors to raising education achievement, reducing societal inequities, and boosting economic development. Consequently, countries have put substantial efforts into regulating initial teacher education (ITE) to ensure graduates are ‘ready’ to deliver ‘high-quality’ practice tackling education and societal issues. This paper problematises the widespread narrative of ITE by critiquing the construction of ‘ready to teach’ graduates in a leading New Zealand ITE regulatory policy. I argue that teaching and assessing ‘readiness’ via ITE has reinforced ‘linearity’ and ‘technical rationalism’ in defining what it is to be a teacher. It has also reflected humanist-colonial discourses that placed solely human agency, capacity, and achievement at the centre of global progress. I propose making a qualitative shift in conceptualising ITE and moving away from defining ‘quality’ and ‘achievement’ through a set of ‘special properties essential to the human knowing subject’. Recognising that the knowing subject is never the teacher alone, but is a living constellation of human, nonhuman, and more-than-human elements with distributed agency is vital for inviting alternative teacher becomings that societies need to change the status quo.

Tunable polarization-dependent defect modes and lateral shifts of one-dimensional photonic crystals containing Dirac semimetal-based hyperbolic metamaterials and chiral materials

The transmission and lateral shift properties of the one-dimensional photonic crystals containing Dirac semimetal-based hyperbolic metamaterials and chiral material defects are theoretically investigated by using the transfer matrix method in terahertz. It is found that the angle-independent omnidirectional photonic bandgaps (PBGs) for p-polarization can be realized in the photonic crystals made of dielectric and the Dirac semimetal-based hyperbolic metamaterials. However, the PBGs are blue-shifted with the incident angle for s-polarized wave. The omnidirectional PBGs can be tunable with the Fermi energy of the Dirac semimetal, the thickness ratio of the constitute layers and the structural parameters. When one or two isotropic chiral material layers are introduced in the photonic crystals, double or four polarization-dependent defect modes are found in the bandgap under oblique incidence due to the coupling and conversion between different polarized waves in the chiral defects. The frequency interval of the defect modes changes with the chirality parameter and the incident angle. It is also found that when a light is incident on the defective photonic crystals, the giant positive and negative Goos-Hänchen shifts of co-polarization reflected waves can be induced around the defect modes, which are sensitive to the polarization, the incident angle, the incident frequency and the chirality. The special optical properties of the proposed defective multiplayers provide possibilities for practical applications in designing polarization sensitive optical devices, such as filter and sensor.

Minimal and proximal examples of -stable and -approachable shift spaces

Abstract We study shift spaces over a finite alphabet that can be approximated by mixing shifts of finite type in the sense of (pseudo)metrics connected to Ornstein’s $\bar {d}$ metric ( $\bar {d}$ -approachable shift spaces). The class of $\bar {d}$ -approachable shifts can be considered as a topological analog of measure-theoretical Bernoulli systems. The notion of $\bar {d}$ -approachability, together with a closely connected notion of $\bar {d}$ -shadowing, was introduced by Konieczny, Kupsa, and Kwietniak [Ergod. Th. & Dynam. Sys.43(3) (2023), 943–970]. These notions were developed with the aim of significantly generalizing specification properties. Indeed, many popular variants of the specification property, including the classic one and the almost/weak specification property, ensure $\bar {d}$ -approachability and $\bar {d}$ -shadowing. Here, we study further properties and connections between $\bar {d}$ -shadowing and $\bar {d}$ -approachability. We prove that $\bar {d}$ -shadowing implies $\bar {d}$ -stability (a notion recently introduced by Tim Austin). We show that for surjective shift spaces with the $\bar {d}$ -shadowing property the Hausdorff pseudodistance ${\bar d}^{\mathrm {H}}$ between shift spaces induced by $\bar {d}$ is the same as the Hausdorff distance between their simplices of invariant measures with respect to the Hausdorff distance induced by Ornstein’s metric $\bar {d}$ between measures. We prove that without $\bar {d}$ -shadowing this need not to be true (it is known that the former distance always bounds the latter). We provide examples illustrating these results, including minimal examples and proximal examples of shift spaces with the $\bar {d}$ -shadowing property. The existence of such shift spaces was announced in the earlier paper mentioned above. It shows that $\bar {d}$ -shadowing indeed generalizes the specification property.