Stabilization Of Phase Research Articles

Soil carbon, nitrogen, and potassium regulate herbaceous community stability in the restoration phases of desertification land

AbstractSoil carbon, phosphorus, and nitrogen are crucial components that influence the stability of herbaceous plant communities in desertified land restoration. However, there is a dearth of data on the variables that impact the stability of herbaceous communities at various stages of restoration. This study investigated the variables of soil and plant communities on desertified land with varying recovery periods (recovery time less than 10 years, 10–20 years, and more than 20 years) to examine the alterations in the stability of herbaceous communities and the influence of soil nutrients on these changes. Our results indicated that the stability of herbaceous communities exhibited a positive correlation with recovery time. Further research suggests that total carbon (TC) and available nitrogen (AN) levels of soil significantly influenced the herbaceous community's stability when the recovery period was less than 10 years. Total nitrogen (TN) and TC levels of soil affected the community's stability when the recovery period ranged from 10 to 20 years. When the duration of recovery surpassed 20 years, available potassium (AK) in soil significantly impacted the community's stability. This suggested that soil nutrients influence the stability of the herbaceous community. Our findings suggest that soil nutrition is a crucial factor in the initial phase of ecological restoration on desertified land. These findings offer empirical evidence for comprehending the stabilizing mechanism of herbaceous communities in desertified land and provide theoretical backing for ecological restoration methods.

Capacitance Boosting of Antiferroelectric‐Hf0.2Zr0.8O2/Al2O3 Blocking Layer Using Y2O3 Interfacial Layer for Charge Trap Flash Memory

A Y2O3 interfacial layer is introduced to enhance the capacitance of the blocking layer stacked with antiferroelectric (AFE)‐Hf0.2Zr0.8O2 (HZO) and Al2O3 films in charge trap flash (CTF) memories. The ultrathin Y2O3 film, with a target thickness of 2 nm, intermixes with the HZO film during the atomic layer deposition (250 °C) of HZO and promotes stabilization of the AFE tetragonal phase during postmetallization annealing (600 °C). Significant increases in the spontaneous polarization and maximum dielectric constant are achieved in the AFE‐HZO/Y2O3 structure compared with the single‐layer AFE‐HZO structure. When Si3N4‐based CTF devices are fabricated with an AFE‐HZO/Al2O3 blocking layer utilizing the capacitance‐boosting effect, the introduction of a Y2O3 interfacial layer results in performance enhancement in terms of memory window and programming efficiency. These improvements are attributed to the enhanced negative capacitance effect, which stems from the increased spontaneous polarization in the AFE‐HZO film due to Y2O3 doping.

Phase Engineering of SnSeX (X = 1,2) Microstructures for High-Performance NO2 Chemiresistive Room-Temperature Sensor Systems: Toward Highly Reliable and Robust Detection Properties under Humidity and Interfering Gas Conditions.

Two-dimensional SnSeX (X = 1, 2) has emerged as a promising candidate for a NO2 chemiresistive sensor due to a remarkable affinity to NO2 gas adsorption. Although their gas sensing mechanism primarily relies on direct charge transfer, the underlying mechanisms of SnSe and SnSe2 remain unclear, despite various reported successes in phase engineering of SnSeX. Here, we investigate phase engineering of SnSeX in a hydrothermal route via 1-dodecanethiol (1-DDT), which served as a phase stabilizer, and comprehensively demonstrate phase-dependent NO2 detection properties. As the 1-DDT concentration increases, we directly confirm that the SnSe structure was gradually transformed to the SnSe2 one. This transformation correlates with a gradual increase in NO2 gas responses from 45 to 1430%, the highest value reported among SnSeX-based NO2 gas sensors. The obtained SnSe2-based sensors also exhibit a good NO2 discrimination without configuration of sensor arrays, under an interfering gas atmosphere in humidity conditions. Our computational calculation also unveils that these outstanding detection performances are attributed to well-constructed SnSe2 coupled with a single Se vacancy to enhance a stronger NO2 adsorption than SnSe. Finally, we demonstrate a sensor module system based on SnSe2, enabling real-time monitoring of NO2 gas.

Processing of Ti–5Al–4W–2Fe Alloy Using Different Powder Metallurgy Routes to Improve Its Implementation in Structural Applications

Abstract Titanium (Ti) alloys can be thoroughly improved by introducing aluminum (Al) as an $$\alpha$$ α -phase stabilizer and tungsten (W) as a $$\beta$$ β -phase stabilizer as well as iron (Fe) for enhancing the strength and the creep resistance. In the current study, Ti–5Al–4W–2Fe alloy was especially synthesized to meet the essential requirements of the structural products of Ti-based alloys. Three different PM routes have been adjusted for investigating both densification and mechanical properties improvement of this alloy. The first approach was pressure-less vacuum sintering (PLS) at 1100–1300 °C for 1 h, which showed inadequate achievement of densification. Unfortunately, using PLS 96% of the theoretical density (TD) was recorded. However, using hot pressing (HP) and sintering-forging (IF) resulted in a successful full densification of 100% TD. It is worth mentioning that adding W particles resulted in an effective grain refinement of the sintered Ti alloy. More interestingly, HP-sintered specimens demonstrated higher strength and plastic compression compared to the other specimens. For instance, the yield and fracture strength of this specimen showed 1463 MPa and 2408 MPa, respectively, which is considered as a remarkable achievement compared to similar studies. Surprisingly, the most economical technique PLS sintering led to the best hardness of 700 HV, compared to 470 HV and 480 HV for the forged specimen and the HP-sintered specimen, respectively.

Feasibility of phase stabilization for satellite-mediated twin-field quantum key distribution.

Quantum key distribution (QKD) is critical for future proofed secure communication. Satellites will be necessary to mediate QKD on a global scale. The limitations of the existing quantum memory and repeater technology mean that twin-field QKD (TF-QKD) provides the most feasible near-term solution to perform QKD with an untrusted satellite. However, the TF-QKD requires links between ground stations and satellites to be phase stable. We show that phase stabilization of the links to LEO and MEO satellites is feasible in spite of phase noise due to atmospheric turbulence, laser instability, and path length asymmetry while only incurring a quantum bit error rate (QBER) penalty of less than 1.5%. These results are also applicable to future untrusted satellite networks employing precisely synchronized quantum memories or quantum repeaters.

Discovery and Characterization of a Metastable Cubic Interstitial Nickel-Carbon System with an Expanded Lattice.

Metastable, i.e., kinetically favored but thermodynamically not stable, interstitial solid solutions of carbon in iron are well-understood. Carbon can occupy the interstitial atoms of the host metal, altering its properties. Alloying of the host metal results in the stabilization of the FeCx phases, widening its application. Pure nickel finds niche applications, mainly focusing on catalysis, while nickel alloys are widely applied, e.g., in gas turbines, reactors, and seawater piping. Nickel carbide (Ni3C) is the well-known stable Ni-C system displaying a rhombohedral (R3̅c) crystal structure. Some reports describe an elusive cubic Ni-C system, observed during certain catalytic reactions occurring on nickel and formed by the occupation of the interstitials of the metal with carbon: to date, the stabilization and characterization of this phase have not been accomplished. Hereby, we report on the synthesis of a cubic metastable NiCx phase using chemical vapor deposition of methane on supported nickel nanoparticles. The structure was predicted by DFT/ReaxFF, synthesized and monitored with in situ time-resolved synchrotron XRD, and experimentally confirmed by Rietveld refinement and (S)TEM-EELS under ambient conditions. The results show an Fm3̅m phase with a lattice parameter of a = 3.749 ± 0.037 Å at room temperature, with the highest ever reported atomic percentage of carbon occupying the octahedral interstices of 23.1%, resulting in a NiC0.3 phase. The degree of occupation of the interstitial voids by carbon can be controlled, enabling the tuning of the host metal's d-spacing and composition, highlighting the applicability of this synthesis route for catalytic nanoparticle preparation.

Insight Into the Film‐Forming Properties of Pea Protein Isolate Improved by Cellulose Nanocrystals From the Perspective of Water Phase Stabilization

ABSTRACTThis study is dedicated to explore the effect of cellulose nanocrystal (CNC) on the film formability of pea protein isolate (PPI) and propose the regulation mechanism from the perspective of water phase stabilization. Compared with PPI film, the CNC‐PPI composite films showed the improvement in mechanical properties and barrier properties of water/air. CNC reduced the proportion of free water in the PPI film and induced its conversion to immobilized water. From the microscopic observation of the films, it could be found that 0.25%–0.75% CNC made the dispersion of PPI more uniform, and formed more compact film structure. Meanwhile, the exposure of tyrosine and tryptophan in PPI molecules and the increase in the content of β‐sheet resulted in the improvement of film‐forming properties of PPI. The enhanced stability of water phase induced by CNC restrained the formation of water channels, thus improving the structural integrity of gel network and the film‐forming properties of PPI. This work provided a theoretical reference for regulation of the film‐forming properties of PPI with CNC, which was expected to improve the product performance of PPI films and enrich the application scenarios of PPI.

Interplay of irradiation stress and phase stabilizer in determining the direction of martensitic transformation in SS316

Interplay of irradiation stress and phase stabilizer in determining the direction of martensitic transformation in SS316

A novel water-soluble polymer nanocomposite containing ultra-small Fe3O4 nanoparticles with strong antibacterial and antibiofilm activity.

A novel water-soluble polymer nanocomposite containing ultra-small iron oxide nanoparticles, intercalated into a biocompatible matrix of 1-vinyl-1,2,4-triazole and N-vinylpyrrolidone copolymer has been synthesized for the first time. The use of an original polymer matrix ensured effective stabilization of the crystalline phase of iron oxides at an early stage of its formation in an ultra-small (2-8 nm, average diameter is 4.8 nm) nanosized state due to its effective interaction with the functional groups of copolymer macromolecules. At the same time, the copolymer ensures the long-term stability of iron oxide nanoparticles in a nanosized dispersion. The structure and physicochemical properties of the copolymer and nanocomposite were studied by elemental analysis, 1H and 13C NMR spectroscopy, gel permeation chromatography, Fourier-transform infrared spectroscopy, transmission and scanning electron microscopy, dynamic light scattering, thermogravimetric analysis and differential scanning calorimetry. The nanocomposite exhibits high antibacterial and antibiofilm activity against both Gram-negative and Gram-positive bacteria. The nanocomposite at a concentration of 500 and 1000 μg mL-1 leads to complete death of Escherichia coli cells after 24 and 3 hours of incubation, respectively. The nanocomposite at a concentration of 100 μg mL-1 leads to complete death of Staphylococcus aureus cells after 24 hours of incubation. Which indicates the potential of using the nanocomposite for the treatment of superficial wounds and purulent-inflammatory complications.

Leveraging ordered voids in microporous perovskites for intercalation and post-synthetic modification.

We report the use of porous organic layers in two-dimensional hybrid organic-inorganic perovskites (HOIPs) to facilitate permanent small molecule intercalation and new post-synthetic modifications. While HOIPs are well-studied for a variety of optoelectronic applications, the ability to manipulate their structure after synthesis is another handle for control of physical properties and could even enable use in future applications. If designed properly, a porous interlayer could facilitate these post-synthetic transformations. We show that for a series of copper-halide perovskites, a crystalline arrangement of designer ammonium groups allows for permanently porous interlayer space to be accessed at room temperature. Intercalation of the electroactive molecules ferrocene and tetracyanoethylene into this void space can be performed with tunable loadings, and these intercalated perovskites are stable for months. The porosity also enables reactivity at the copper-halide layer, allowing for facile halide replacement. Through this, we access previously unobserved reactivity with halogens to perform halide substitution, and even replace halides with pseudohalides. In the latter case, the porous structure allows for stabilization of new phases, specifically a novel copper-thiocyanate perovskite phase, only accessible through post-synthetic modification. We envision that this broad design strategy can be expanded to other industrially relevant HOIPs to create a new class of highly adjustable perovskites.

Interfacial seed-assisted FAPbI3 crystallization and phase stabilization enhance the performance of all-air-processed perovskite solar cells.

Formamidinium lead triiodide (FAPbI3) has received significant attention in the field of perovskite solar cells (PSCs) owing to its excellent optoelectronic properties and high thermal stability. However, the photoactive α-FAPbI3 perovskites are highly susceptible to degradation into non-perovskite δ-FAPbI3 phases, especially under humid conditions, which severely diminishes the device performance of FAPbI3 PSCs. Here, we propose an interfacial seeding strategy for regulating crystallization and stabilizing α-FAPbI3 perovskites in humid air. By post-treating an antisolvent-free, air-processed perovskite wet film with inorganic cesium lead triiodide (CsPbI3) nanocrystals, a functional seed layer is formed that effectively mitigates the erosion by humid air while facilitating the conversion of intermediates to the α-FAPbI3 phase. The interfacial seed-modified FAPbI3 perovskite films exhibit improved crystal quality and denser morphology. As a result, the efficiency of all-air-processed carbon-based PSCs is improved from 15.90% for the control to 18.04%. In addition, the unencapsulated PSCs based on interfacial seed-modified FAPbI3 films show improved environmental stability compared to their control counterparts, maintaining 80% of their initial efficiency after 60 days.

Spatiotemporal Retention of Structural Color and Induced Stiffening in Crosslinked Hydroxypropyl Cellulose Beads.

Hydroxypropyl cellulose (HPC) is known for its ability to form cholesteric liquid crystalline phases displaying vivid structural colors. However, these vibrant colors tend to fade over time when the material dries. This issue is a major bottleneck to finding practical applications for these materials. Here this problem is overcome by producing free-standing, millimeter-sized HPC structurally colored beads with spatiotemporal color retention, facilitated by a glutaraldehyde crosslinker. By leveraging the well-known chemically induced stabilization of cholesteric liquid crystalline phases, stable structural colors are achieved for at least three weeks. The presence of glutaraldehyde significantly increases the mechanical stiffness, with Young's modulus rising from 0.3± 0.1GPa to 1.8± 0.2GPa. This integrated approach of creating free-standing photonic HPC beads offers a strategy for developing robust and durable photonic HPC materials with enhanced stability, advancing photonic material applications with spatiotemporal color stability.

Effect of high-temperature shear deformation on the synthesis of TiB<sub>2</sub>‒ZrO<sub>2</sub> composite material under conditions of free SHS compression

Ceramic materials based on TiB2 and stabilized ZrO2 were obtained by self-propagating high-temperature synthesis (SHS). The stabilization of the high-temperature phases of ZrO2 was carried out by introducing Y2O3 into the initial mixture. The effect of the Y2O3 content on the combustion characteristics of the studied materials, as well as on the phase composition of synthesis products in the range of Y2O3 concentrations from 0 to 6,2 wt. %, was studied. Gorenje. To study the effect of high-temperature shear deformation on the synthesis process by free SHS compression, compact plates with dimensions of 50×50×7 mm were obtained based on the studied compositions. It has been established that as a result of the synthesis of materials obtained under conditions of high-temperature shear deformation and without pressure application, the reaction products have different phase compositions. The resulting compact plates are composite materials consisting of a matrix based on stabilized ZrO2 with TiB2 particles distributed in it.

Electrode Elastic Modulus as the Dominant Factor in the Capping Effect in Ferroelectric Hafnium Zirconium Oxide Thin Films.

The discovery of ferroelectricity in hafnia based thin films has catalyzed significant research focused on understanding the ferroelectric property origins and means to increase stability of the ferroelectric phase. Prior studies have revealed that biaxial tensile stress via an electrode "capping effect" is a suspected ferroelectric phase stabilization mechanism. This effect is commonly reported to stem from a coefficient of thermal expansion (CTE) incongruency between the hafnia and top electrode. Despite reported correlations between ferroelectric phase fraction and electrode CTE, the thick silicon substrate dominates the mechanics and CTE-related stresses, negating any dominant contribution from an electrode CTE mismatch toward the capping effect. In this work, these discrepancies are reconciled, and the origin of these differences deriving from electrode elastic modulus, not CTE, is demonstrated. Pt/M/TaN/Hf0.5Zr0.5O2/TaN/Si devices, where M is platinum, TaN, iridium, tungsten, and ruthenium, were fabricated. Sin2(ψ)-based X-ray diffraction measurements of biaxial stress in the HZO layer reveal a strong correlation between biaxial stress, remanent polarization, and electrode elastic modulus. Conversely, a low correlation exists between the electrode CTE, HZO biaxial stress, and remanent polarization. A higher elastic modulus enhances the resistance to electrode elastic deformation, which intensifies the capping effect during crystallization, and culminates in the tandem restriction of out-of-plane hafnia volume expansion and preferential orientation of the polar c-axis normal to the plane. These behaviors concomitantly increase the ferroelectric phase stability and polarization magnitude. This work provides electrode material selection guidelines toward the development of high-performing ferroelectric hafnia into microelectronic devices, such as nonvolatile memories.

Phase stabilization with motion compensated diffusion weighted imaging.

Diffusion encoding gradient waveforms can impart intra-voxel and inter-voxel dephasing owing to bulk motion, limiting achievable signal-to-noise and complicating multishot acquisitions. In this study, we characterize improvements in phase consistency via gradient moment nulling of diffusion encoding waveforms. Healthy volunteers received neuro ( ) and cardiac ( ) MRI. Three gradient moment nulling levels were evaluated: compensation for position ( ), position + velocity ( ), and position + velocity + acceleration ( ). Three experiments were completed: (Exp-1) Fixed Trigger Delay Neuro DWI; (Exp-2) Mixed Trigger Delay Neuro DWI; and (Exp-3) Fixed Trigger Delay Cardiac DWI. Significant differences ( ) of the temporal phase SD between repeated acquisitions and the spatial phase gradient across a given image were assessed. moment nulling was a reference for all measures. In Exp-1, temporal phase SD for diffusion encoding was significantly reduced with (35% of t-tests) and (68% of t-tests). The spatial phase gradient was reduced in 23% of t-tests for and 2% of cases for . In Exp-2, temporal phase SD significantly decreased with gradient moment nulling only for (83% of t-tests), but spatial phase gradient significantly decreased with only (50% of t-tests). In Exp-3, gradient moment nulling significantly reduced temporal phase SD and spatial phase gradients (100% of t-tests), resulting in less signal attenuation and more accurate ADCs. We characterized gradient moment nulling phase consistency for DWI. Using M1 for neuroimaging and M1 + M2 for cardiac imaging minimized temporal phase SDs and spatial phase gradients.

An unusual phase transition in a non-Hermitian Su–Schrieffer–Heeger model

This article studies a non-Hermitian Su-Schrieffer-Heeger model which has periodically staggered Hermitian and non-Hermitian dimers. The changes in topological phases of the considered chiral symmetric model with respect to the introduced non-Hermiticity are studied where we find that the system supports only complex eigenspectra for all values ofu ≠ 0 and it stabilizes only non-trivial insulating phase for higher loss-gain strength. Even if the system acts as a trivial insulator in the Hermitian limit, the increase in loss-gain strength induces phase transition to non-trivial insulating phase through a (gapless) semi-metallic phase. Interesting phenomenon is observed in the case where Hermitian system acts as a non-trivial insulator. In such a situation, the introduced non-Hermiticity neither leaves the non-trivial phase undisturbed nor induces switching to trivial phase. Rather, it shows transition from non-trivial insulating phase to the same where it is mediated by the stabilization of (non-trivial) semi-metallic phase. This unusual transition between the non-trivial insulating phases through non-trivial semi-metallic phase gives rise to a question regarding the topological states of the system under open boundary conditions. So, we analyze the possibility of stable edge states in these two non-trivial insulating phases and check the characteristic difference between them. In addition, we study the nature of topological states in the case of non-trivial gapless (semi-metallic) region.

Biphasic 1T/2H-MoS2 Nanosheets In Situ Vertically Anchored on Reduced Graphene Oxide via Covalent Coupling of the Mo-O-C Bond for Enhanced Electrocatalytic Hydrogen Evolution.

Transition-metal dichalcogenides (TMDs) have recently emerged as promising electrocatalysts for the hydrogen evolution reaction owing to their tunable electronic properties. However, TMDs still encounter inherent limitations, including insufficient active sites, poor conductivity, and instability; thus, their performance breakthrough mainly depends on structural optimization in hybridization with a conductive matrix and phase modulation. Herein, a 1T/2H-MoS2/rGO hybrid was rationally fabricated, which is characterized by biphasic 1T/2H-MoS2 nanosheets in situ vertically anchored on reduced graphene oxide (rGO) with strong C-O-Mo covalent coupling. The rGO substrate improves the conductivity and ensures high-dispersed 1T/2H-MoS2 nanosheets to expose plentiful highly active edges. More importantly, the strong heterointerface electrical interaction by the C-O-Mo covalent bond can enhance the charge-transfer efficiency and reinforce structural stability. Furthermore, the integration with the appropriate 2H phase is in favor of stabilization of the metastable 1T phase; thus, the ratio of 1T and 2H was precisely regulated to balance activity and stability. With these advantages, the 1T/2H-MoS2/rGO catalyst presents a satisfactory activity and stability, as confirmed by the relatively low overpotential (268 and 140 mV at 10 mA cm-2) and the small Tafel slope (102 and 86 mV dec-1) in alkaline and acidic media, respectively. The theory calculations disclose that the electronic structure redistribution has been optimized via the strong coupled C-O-Mo heterointerface and phase interface, significantly reducing the adsorption free energy of hydrogen and improving intrinsic activity.

Mechano-chemical competition in driven complex concentrated alloys

Mechanically driven complex concentrated alloys can be formed by three or more types of elemental powders mixing into a solid solution through severe plastic deformation at temperatures much lower than the melting point of each element. While competition between the thermal and mechanical driving forces during forced mixing of binary systems with positive enthalpy of mixing is relatively well understood, the physics of mechanically driven mixing of multiple elements with negative mixing enthalpies remained unclear. In this work, we combined mechanical alloying (MA), X-ray diffraction (XRD), and kinetic Monte Carlo (kMC) simulations to systematically study the interplay between the chemical pairing potential and the mechanical strength of elemental pairs during the formation process of mechanically driven complex concentrated alloys. We demonstrate that the chemical and mechanical forces play a competing role in the mixing of ternary complex concentrated alloys with negative mixing enthalpies. The chemical driving force favors a chemically ordered atomic structure, while the mechanical force encourages a random atomic arrangement. We reveal the energetic basis of this competition as the gain and loss in mixing enthalpy and configurational entropy. Following this fundamental understanding, three types of mixing mechanisms and their corresponding steady-state phases are defined. We show that the molar content of the element with the lowest average mixing enthalpy governs the mixing mechanisms and thus determines the energetic stabilization of the steady-state phases. A theoretical phase prediction map is provided for alloy design. We synthesized a nanocrystalline equiatomic NiCoCr coating under the guidelines of the map, which presents exceptional mechanical properties achieved by the mechano-chemical mixing.

(Invited) Novel Materials Chemistry for Applications in Energy Storage and Conversion

The current trend in various energy applications, ranging from batteries to electrolizers, lays in the control of structural, physicochemical and morphological properties of materials and their interfaces. During this presentation, recent scalable strategies for nanostructured materials synthesis, targeting energy and environmental applications will be discussed. Especially, we will focus on one-pot strategies for the fabrication of hybrid and complex nanomaterials focusing on the importance of the organic-inorganic and inorganic-inorganic interfaces. Among the examples presented, we will discuss the synthesis of complex nanostructures and the stabilization of metastable phases for applications in energy, catalysis and environmental remediation. We will see that nowadays the available strategies allow a control in terms of composition, crystalline structure, morphology and nanostructuration that would have been unimaginable just few years ago. Finally, the open challenges the field is currently facing and possible further developments which are needed to meet the always growing demand for high performing materials will be also discussed

Modeling spider silk supercontraction as a hydration-driven solid-solid phase transition

Spider silks have attracted significant interest due to their exceptional mechanical properties, which include a unique combination of high strength, ultimate strain, and toughness. A notable characteristic of spider silk, still debated from both mechanical and functional viewpoints, is supercontraction–a pronounced contraction of up to half its original length when an unconstrained silk thread is exposed to a wet environment. We propose a predictive model for the hygro-thermo-mechanical behavior of spider silks, conceptualizing this phenomenon as a solid–solid phase transition, similar to the glass transition in rubber, but driven by humidity. As wetting increases, the system undergoes a transition, at the network scale, from a hard, highly crystalline, dry state–where the material behavior is governed by stiff chains elongated along the fiber axis–to a soft, amorphous, wet state, regulated by a rubber-like response. We model these states using a two-well free energy function dependent on molecular stretch, with transition energy modulated by humidity. Based on the methods of Statistical Mechanics, we deduce that supercontraction can be interpreted as a solid–solid phase transition. We elucidate the important role of thermal fluctuations. In particular, the decrease of the critical humidity needed for supercontraction as temperature grows results as an effect of entropic stabilization of the softer rubbery phase. Our model quantitatively predicts the observed experimental behavior, capturing the temperature dependence of humidity-induced supercontraction effects and related cooperative properties.