Crystalline Systems Research Articles

Temperature dependence of the frequency shifts related to the thermodynamic quantities close to phase transitions in NaNO2

ABSTRACT This study examines a linear relationship between the frequency shifts, ( 1 / w ) ( ∂w / ∂T ) p , and the variation of the dielectric constant, ( 1 / ϵ ) ( ∂ϵ / ∂T ) p , close to phase transitions in ferroelectric crystalline systems, in particular, ferroelectric NaNO2 as studied here. Both quantities (frequency and dielectric constant) are described by the power-law formulae below the Curie temperature Tc (ferroelectric phase), Tc < T < Ti (incommensurate phase) and T > Ti (paraelectric phase). The divergence behaviour of the mode Grüneisen parameter (ɣp ) is obtained, whose temperature dependence can also be described by a power-law formula in NaNO2. It is also shown that the heat capacity Cp can be evaluated from the thermal expansion (αp ) by means of the same critical exponent since they exhibit similar critical behaviour near Tc and Ti in this crystal.

A note on purity of crystalline local systems

In this short note, we prove a purity result for crystalline local systems on a smooth p p -adic affine formal scheme. Our method is based on the prismatic description of crystalline local systems (see Du et al. [Compos. Math. 160 (2024), pp. 1101–1166]; cf. Guo and Reinecke [Invent. Math. 236 (2024), pp. 17–164]), which is different from the approach by Tsuji [Crystalline sheaves and filtered convergent F F -isocrystals on log schemes, preprint].

The role of the exact Hartree-Fock exchange in the investigation of defects in crystalline systems.

The role of the exact Hartree-Fock (HF) exchange in determining the band gap and other properties of defects in crystalline solids is investigated. Two defects in diamond, VHd1 and VHq1 (one first neighbour of the vacancy is saturated with hydrogen, and the three unpaired electrons combine to give a quadruplet, 3 spin up, or a doublet, two spin up and one down), are used as test cases. The results obtained with a gradient corrected functional, PBE, one range separate hybrid, HSE06, two full range hybrids, B3LYP and PBE0, and the Hartree-Fock Hamiltonian are compared. The crucial role of the exact HF exchange emerging from this comparison is confirmed by a set of calculations with a variable functional, PBE(X), in which X is the percentage of HF exchange, which is varied from 0 to 100, where PBE(0) coincides with PBE, and PBE(25) with PBE0.

Shrinkable muscular crystal with chemical logic gates driven by external ion environment

Biomimetic chemical logic gates that can reversibly transform their shape and physical properties in response to their environment are an important research field. Most artificial chemical logic gates, however, rely on changes in the microscopic properties of molecules and ions in solution. Hence, developing chemical logic gates that influence macroscopic properties, such as crystal structures and magnetic and electrical properties, is essential for mimicking in vivo phenomena more accurately. Here, we develop a reset-set flip-flop circuit based on a single crystal that reversibly transforms in the presence of Ca2+ ions in aqueous solutions and is analogous to the chemical logic gate in muscles. During the crystal transformation, the lattice volume undergoes ~39% shrinkage, and the magnetic and electrical properties change considerably. Compared with existing products, the constructed crystalline system more closely resembles the function of actual muscles, which is promising for advancing the field of biomimetics.

Measurement of stress optical coefficients for GFRP based on terahertz time-domain spectroscopy

Glass Fiber-Reinforced Polymer (GFRP) finds extensive applications in the high-end equipment manufacturing industry owing to its advantages of light weight, high strength, and corrosion resistance. Since the residual stress in GFRP builds up during the curing process and affect its mechanical properties and service life, the characterization of the residual stress in GFRP is crucial. In this study, we establish a theoretical model based on the anisotropic stress-optics law for the orthorhombic crystalline system to describe the terahertz-elasticity of GFRP and calibrate the stress optical coefficients of GFRP. First, the residual stress in GFRP at different curing temperatures are measured by fiber Bragg grating sensors. Then, the refractive index of GFRP with different residual stress are obtained based on transmission-type THz-TDS. Finally, based on the proposed photoelastic model of GFRP, the stress optical coefficients of GFRP are measured by combining the measurement results of residual stress and refractive index. The experimental results show that the refractive index of GFRP decreases with the increase of residual stress; the stress optical coefficients of GFRP are determined as q11 = −5.612 × 10−9 Pa−1, q12 = −2.548 × 10−9 Pa−1, q21 = −1.305 × 10−8 Pa−1, q22 = −1.408 × 10−9 Pa−1. The modeling of terahertz photoelasticity in GFRP and the determination of stress optical coefficients provide a basis for characterizing residual stress in GFRP by THz-TDS.

Topological superconductivity in Fibonacci quasicrystals

We investigate the properties of a Fibonacci quasicrystal (QC) arrangement of a one-dimensional topological superconductor, such as a magnetic atom chain deposited on a superconducting surface. We uncover a general mutually exclusive competition between the QC properties and the topological superconducting phase with Majorana bound states (MBS): there are no MBS inside the QC gaps and the MBS never behave as QC subgap states and, likewise, no critical or winding QC subgap states exist inside the topological superconducting gaps. Surprisingly, despite this competition, we find that the QC is still highly beneficial for realizing topological superconductivity with MBS. It both leads to additional large nontrivial regions with MBS in parameter space, that are topologically trivial in crystalline systems, and increases the topological gap protecting the MBS. We also find that shorter approximants of the Fibonacci QC display the largest benefits. As a consequence, our results promote QCs, and especially their short approximants, as an appealing platform for improved experimental possibilities to realize MBS as well as generally highlight the fundamental interplay between different topologies. Published by the American Physical Society 2024

Study on the crystallinity of PEG on the crystalline size of flavonoids in a crystalline dispersion system

Poor water solubility and low bioavailability of flavonoids present significant barriers to their development and application. To address these challenges, this study explores the use of crystalline solid dispersions (CSDs) to reduce drug crystalline size and enhance in vivo bioavailability. The CSDs were prepared using a spray-drying technique with chrysin (CHY) and quercetin (QUR) as model drugs and various molecular weights of polyethylene glycol (PEG) as carriers. The authors systematically investigated the factors influencing the interaction between flavonoids and PEG in CSDs. These factors included the relationships between intermolecular interactions and PEG molecular weight, crystallinity, microstructures such as crystalline domain size and crystal morphology of the flavonoids and PEG in CSDs, crystalline size of the drug in CSDs, and in vitro dissolution rate and in vivo pharmacokinetics. Our results indicated that the interaction between flavonoids and PEG in CSDs was influenced more by PEG crystallinity than by its molecular weight. Lower crystallinity of PEG, achieved through recrystallization, led to stronger intermolecular interactions with the drugs. Specifically, PEG8000 exhibited the lowest crystallinity, indicating a higher content of PEG in the amorphous state, which interacted more effectively with the amorphous drug in CSDs. This interaction significantly inhibited drug crystallization growth, resulting in a marked decrease in drug crystalline domain size and crystalline size. Consequently, PEG8000 was identified as the optimal carrier for preparing CSDs, achieving the best cumulative dissolution percentage. The QUR/PEG8000-CSD formulation increased the cumulative dissolution percentage and oral bioavailability of QUR by 18.76 and 20.66 times, respectively, compared to QUR alone. This study demonstrates that PEG crystallinity, following recrystallization, directly affects its intermolecular interactions with the drug, thereby impacting drug crystalline size and dissolution rate.

Induced blue phase and twist grain boundary phase in binary mixtures of chiral calamitic and achiral hockey stick-shaped liquid crystals

Frustrated phases in chiral liquid crystalline systems, such as the blue phase (BP) and the twist grain boundary (TGB) phase, can create new opportunities in liquid crystal research. These frustrated phases have unique optical properties which can be used for specific applications. A new binary mixture system composed of a chiral rod-like ferroelectric liquid crystal and an achiral hockey stick-shaped compound was designed. This binary system exhibits induced frustration, resulting in the emergence of the BP-III and TGB*A phases in addition to the chiral ferroelectric Smectic-C* phase. We report a comprehensive study on several binary mixtures (xH-22.5= 0.162, 0.25, 0.396, 0.562) designed of a chiral ferroelectric liquid crystal derived from the lactic acid, namely 4-(octyloxy)phenyl 3-methoxy-4-((4-((2-(pentyloxy)­propanoyl)­oxy)benzoyl)oxybenzoate and achiral hockey stick-shaped compound, namely (E)-4-((E-((3-(decyloxy)-2-methylphenyl)imino)methyl)-phenyl 3-(4-(dodecyloxy)phenyl)acrylate. These mixtures induced the blue phase (BP-III, ~2.5–6.2K) and the twist grain boundary Smectic-A*phase (TGB*A&amp;nbsp; ~1.8–6K). Polarizing optical microscopy, birefringence, and dielectric spectroscopy were employed to investigate the BP-III and &amp;nbsp;phases, as those techniques provide insights into their structural and dynamic properties. The ferroelectric behaviour of the SmC* mesophase was investigated by electro-optics. The obtained results are discussed in relation to the molecular structures of the used materials.

Representing crystal potential energy surfaces via a stationary-point network

A cornerstone of materials physics is the principle that all properties of crystalline systems are fundamentally determined based on the underlying potential energy surface (PES), which affects the structural stability and structure–property relations. Finding a proper representation of the PES is essential for the implementation of this principle, which has attracted considerable interest over the past decades; however, progress has been impeded by the lack of a firm theoretical basis for effectively exploring the vast configurational space. Here, we introduce a new method for constructing a crystal PES by using a solution landscape with an improved high-index saddle dynamic scheme, in which generalized coordinates are introduced to encode crystals that satisfy translational and rotational invariance. To represent the PES of periodic crystalline structures, we devise an advanced graph-based stationary-point network to visualize and analyze complex PES terrains, with nodes and edges representing stationary points and their connections, respectively. Crystalline GaN and Si are considered as exemplary case studies, and our newly devised approach leads to the discovery of several hidden transition paths with low enthalpy barriers associated with multistep processes; thus, the effectiveness of the approach is validated. Our method combined with the first-principles calculations offers a viable solution to long-standing problems associated with crystal PESs, such as the kinetics of activated processes, materials stability and synthesizability. These findings represent a notable advancement and offer a basis for future research.

Long-Chain Molecular Crystals Antimony(III) Alkanethiolates Sb(SCnH2n+1)3 (n ≥ 12): Synthesis, Crystal and Electronic Structures, and Supramolecular Self-Assembly via Secondary Interactions.

Currently, there is not much success in solving the molecular and crystal structures of long-chain metal alkanethiolate complexes [M(SCnH2n+1)m] at the atomic level. Taking Sb(SC16H33)3 (1) as an example, we herein disclose the structural characteristics of long-chain trivalent antimony(III) alkanethiolates Sb(SCnH2n+1)3 (n ≥ 12) by single-crystal X-ray crystallography. Specifically, the Sb atom is three-coordinated by alkanethiolate ligands and a slightly distorted triangular pyramid SbS3 core is formed owing to the unique intramolecular stereochemistry of three alkyl chains, namely, two of them almost parallel aligning and the third chain extending alone around the SbS3 core. We further determine the conformation, spatial orientation and packing density of alkyl chains in 1 along with a comparison to those in other long-chain crystalline systems, and reveal the roles of intermolecular van der Waals and Sb···S secondary interactions in molecular self-assembly, which enables 1 to be a layer-structured molecular crystal with a monoclinic P21/c unit cell. The band structures and the atomic orbital contributions to the valence band maximum and conduction band minimum for 1 have also been evaluated by DFT calculations and rationally correlated with its optical absorption property. This study will help understand and discover new structures and structure-property relations of long-chain chemical systems.

Anisotropic effect of shear zone on groundwater potentiality in crystalline hard rock terrain

Assessment of potential groundwater recharge sites and sustainable water resource management in semi-arid crystalline rock terrain is a challenging task. Globally, analysis of remote sensing satellite imagery data for delineation of groundwater potential zones over sheared crystalline hard rock terrains has been fairly successful. But there is no existing study present at our disposal which discusses the factors controlling the inconsistent groundwater potentiality that exits along the shear zones. This study attempts to analyse the major geological factors controlling the irregular groundwater potentiality of shear zones within older crystalline rock terrain. Therefore, the study area selected for this analysis is the Purulia district of West Bengal, NE India, composed mostly of Precambrian metamorphic rocks i.e., quartzite, granite gneisses, porphyroclastic granite-gneiss, quartzo-feldspathic-granite-gneiss, mylonitic granites, quartz-biotite-granite gneiss, quartzites, carbonatites and phyllites. Satellite imagery study of IRS-P6 LISS IV standard FCC image reveals the presence of two bifurcating shear zones namely North Purulia Shear Zone (NPSZ) and South Purulia Shear Zone (SPSZ) over the study area. Careful analysis of rock structure, different lithotypes, soil thickness, electrical resistivity tomography data and water table data with an emphasis on high water table fluctuation, shows a strong spatial relation between the potentially good groundwater recharge zones and the branching/confluence sites of shear zones present in the study area. The study constructs an attempt to demonstrate the relationship between shear zone conjunctions and significant groundwater recharge sites in Precambrian crystalline fractured-rock aquifer system.

Non-negligible Outer-Shell Reorganization Energy for Charge Transfer in Nonpolar Systems.

Many charge-transporting molecular systems function as ordered or disordered arrays of solid state materials composed of nonpolar (or weakly polar) molecules. Due to low dielectric constants for nonpolar systems, it is common to ignore the effects of outer-shell reorganization energy (λout). However, ignoring λout has not been properly supported and it can severely impact predictions and insights derived. Here, we estimate λout by two means: from experimental ultraviolet photoelectron spectra, in which vibronic progression in these spectra can be fitted with the widths of peaks determining the low-frequency component in reorganization energy, regarded to be closely associated with λout, and from molecular dynamic (MD) simulation of nonpolar molecules, in which disorder or fluctuation statistics for energies of charged molecules are calculated. An upper bound for λout was obtained as 505 and 549 meV for crystalline anthracene (140 K) and pentacene (50 K), respectively, by fitting of experimental data, and 212 and 170 meV, respectively, from MD simulations. These values are comparable to the inner-sphere reorganization energy (λin) arising from intramolecular vibration. With corresponding spectral density functions calculated, we found that λout is influenced both by low- and high-frequency dynamics, in which the former arises from constrained translational and rotational motions of surrounding molecules. In an amorphous state, about half of the λout's obtained are from high-frequency components, which is quite different from the conventional polar solvation. Moreover, crystalline systems exhibit super-Ohmic spectral density, whereas amorphous systems are sub-Ohmic.

High-Resistant Starch Based on Amylopectin Cluster via Extrusion: From the Perspective of Chain-Length Distribution and Structural Formation.

Resistant starch (RS) has the advantage of reshaping gut microbiota for human metabolism and health, like glycemic control, weight loss, etc. Among them, RS3 prepared from pure starch is green and safe, but it is hard to achieve structural control. Here, we regulate the crystal structure of starch with different chain-length distributions (CLDs) via extrusion at low/high shearing levels. The change in CLDs in extruded starch was obtained, and their effects on the fine structure (Dm, dBragg, dLorentz, degree of order and double helix, degree of crystal) of RS and its physicochemical properties were investigated by SAXS, FTIR, XRD and 13C NMR analyses. The results showed that the RS content under a 250 r/min extrusion condition was the highest at 61.52%. Furthermore, the crystalline system induced by high amylopectin (amylose ≤ 4.78%) and a small amount of amylose (amylose ≥ 27.97%) was favorable for obtaining a high content of RS3-modified products under the extruding environment. The control of the moderate proportion of the A chains (DP 6-12) in the starch matrix was beneficial to the formation of RS.

In Situ Eutectic Formation in a Polymeric Matrix via Hot-Melt Reactive Extrusion and the Use of Partial Least Squares Regression Modeling for Reaction Yield Determination.

There has been a significant volume of work investigating the design and synthesis of new crystalline multicomponent systems via examining complementary functional groups that can reliably interact through the formation of noncovalent bonds, such as hydrogen bonds (H-bonds). Crystalline multicomponent molecular adducts formed using this approach, such as cocrystals, salts, and eutectics, have emerged as drug product intermediates that can lead to effective drug property modifications. Recent advancement in the production for these multicomponent molecular adducts has moved from batch techniques that rely upon intensive solvent use to those that are solvent-free, continuous, and industry-ready, such as reactive extrusion. In this study, a novel eutectic system was found when processing albendazole and maleic acid at a 1:2 molar ratio and successfully prepared using mechanochemical methods including liquid-assisted grinding and hot-melt reactive extrusion. The produced eutectic was characterized to exhibit a 100 °C reduction in melting temperature and enhanced dissolution performance (>12-fold increase at 2 h point), when compared to the native drug compound. To remove handling of the eutectic as a formulation intermediate, an end-to-end continuous-manufacturing-ready process enables feeding of the raw parent reagents in their respective natural forms along with a chosen polymeric excipient, Eudragit EPO. The formation of the eutectic was confirmed to have taken place in situ in the presence of the polymer, with the reaction yield determined using a multivariate calibration model constructed by combining spectroscopic analysis with partial least-squares regression modeling. The ternary extrudates exhibited a dissolution profile similar to that of the 1:2 prepared eutectic, suggesting a physical distribution (or suspension) of the in situ synthesized eutectic contents within the polymeric matrix.

Groundwater quality evaluation of the weathering mantle in crystalline basement aquifer system, southern Brazil.

Groundwater is the main source of water for more than 2 billion people worldwide. In southern Brazil, the Crystalline Basement Aquifer System is composed of strategic groundwater reservoirs. Groundwater is mostly taken from shallow wells, and it is often used without any treatment, which poses a risk to public health. The present study aims to evaluate shallow groundwater quality and the geochemistry of shallow and deep groundwater located in the municipality of Canguçu, southern Brazil. The physicochemical and microbiological parameters of groundwater samples collected from shallow wells were monitored and analyzed using ANOVA variance analysis and water quality index (CCME WQI) approaches. Also, the results were compared with secondary data from deep wells. The monitored shallow wells had thermotolerant coliforms, Escherichia coli, pH, potassium, manganese, iron, and nitrate in disagreement with the guidelines of the World Health Organization. Moreover, variance analysis showed that the parameters temperature, dissolved oxygen, pH, chloride, and magnesium were the most influenced by seasonal variations. According to the CCME WQI, most samples had good quality (60%), 28% had fair quality, and 12% had poor quality. In addition, the field campaigns with higher precipitation rates also presented fair quality. Therefore, most of the shallow groundwater quality is affected by surface pollutants from the urban area, aggravated in rainy periods. Whereas deep groundwater is influenced by geochemistry mechanisms. The results revealed the risk of water consumption for public health and the urgent need for better maintenance of these wells and water treatment implementation.

Spin-Charge Conversion in Chiral Polymers with Hopping Conduction.

Organic and biological materials are often chiral. Chiral polymers, as recent experiments indicate, facilitate spin-charge conversion: a charge current results in a spin polarization and vice versa, dubbed chirality-induced spin selectivity (CISS) and inverse CISS (ICISS). While CISS/ICISS in crystalline chiral systems such as tellurium can be understood in terms of their chirality- and spin-dependent band structure, such a picture becomes inapplicable to disordered chiral polymers, where carrier transport is via hopping rather than band conduction. Here, we develop a microscopic theory to describe CISS and ICISS in disordered chiral organics, in which chirality-induced geometric spin-orbit coupling leads to a purely geometric spin-dependent Berry phase in electron hops involving triads, whose orientations are dictated by the material's chirality. Our theory reveals a central role of spin-flip hopping, which suppresses CISS but enables ICISS.

Two-Dimensional and Interface Superconductivity in Crystalline Systems

Two-Dimensional and Interface Superconductivity in Crystalline Systems

Tandem "One-Shot" Measurement of Residual Chemical Shift Anisotropy and Residual Dipolar Coupling using Biphasic Supramolecular Peptide Liquid Crystals.

Both solitary and tandem applications of residual chemical shift anisotropy (RCSA) and residual dipolar coupling (RDC) show great potential for the structural and configurational determination of organic molecules. A critical component of both RDC and RCSA methodologies is the alignment medium, whose availability is limited, especially for RCSA measurement. Moreover, reported RDC and RCSA acquisitions mainly rely on two experiments conducted under two different conditions, which are relatively time-consuming and easily cause experimental errors. Herein, a biphasic supramolecular lyotropic liquid crystalline (LLC) system was developed through the self-assembly of C21H43-CONH-V4K3-CONH2, which could act as an alignment medium for not only RDC but also RCSA extraction in DMSO-d6. Notably, the RCSA extraction was easily achieved via one-shot measurement from a single one-dimensional 13C NMR experiment, with no need for special instruments, devices, and correction. Relying on the biphasic LLC medium, meanwhile, RDC data were simply extracted from a single F1-coupled HSQC experiment, different from the standard protocol that requires two spectral acquisitions corresponding to the isotropic and anisotropic conditions. Collectively, the biphasic LLC medium is applicable for tandem RCSA and RDC measurements in one single sample, advancing the stereochemical elucidation of molecules of interest.

Visible‐Light Responsive Ionic Columnar Self‐Assemblies Exhibiting Fast Photothermal Energy Conversion at Room‐Temperature

AbstractA visible‐light responsive ionic liquid crystalline (LC) system based on gallic ester and tetra‐ortho‐substituted azobenzene is designed and synthesized. All the prepared derivatives exhibit columnar hexagonal mesophases at room temperature either in their pristine form or on cooling from isotropic states. The strategic design of these molecules allows for rapid photoisomerization, which is further aided by the dynamic LC phase. These systems attains photostationary states (PSSs) within 5 min of charging and discharging. The maximum Z conversion on charging in the solid‐state at room‐temperature is ≈80% with a highest temperature rise of 9.1 °C on discharging. This new molecular design enables the efficient working of solar thermal fuels (STFs) even in low sunlight intensity conditions, potentially promoting widespread adoption for mitigating global energy demands.

Hybridization of short-range and long-range charge transfer boosts room-temperature phosphorescence performance.

At present, mainstream room-temperature phosphorescence (RTP) emission relies on organic materials with long-range charge-transfer effects; therefore, exploring new forms of charge transfer to generate RTP is worth studying. In this work, indole-carbazole was used as the core to ensure the narrowband fluorescence emission of the material based on its characteristic short-range charge-transfer effect. In addition, halogenated carbazoles were introduced into the periphery to construct long-range charge transfer, resulting in VTCzNL-Cl and VTCzNL-Br. By encapsulating these phosphors into a robust host (TPP), two host-guest crystalline systems were further developed, achieving efficient RTP performance with phosphorescence quantum yields of 26% and phosphorescence lifetimes of 3.2 and 39.2 ms, respectively.