Switchable Phase Research Articles

Switchable crystal–amorphous states of NiSO4·6H2O induced by a Reddy tube

Dynamic shock wave induced switchable phase transitions between crystal and amorphous states of NiSO4·6H2O is reported.

Ternary switchable phase transition of CaCO3 by shock waves

In the present article, we disclose shock wave induced crystallographic switchable phase transition of calcium carbonate nano particles (CaCO3 NPs). The observed profiles of powder X-ray diffraction reveal that CaCO3 NPs undergoes phase transitions in the sequential order from Calcite-I to Calcite-II and Calcite-II to Calcite-III at 50 and 100 shocks, respectively. Interestingly, reversible phase transitions have been observed from Calcite-III to Calcite-II and Calcite-II to Calcite-I at 150 and 200 shocked conditions, respectively. Rotational order-disorder of oxy-anions (CO3) and displacement of cation (Ca) take place because of the impact of shock waves thereby the observed ternary switchable phase transition results paving the way for the design of new multifunctional materials.

The Role of Fluorine-Substituted Positions on the Phase Transition in Organic-Inorganic Hybrid Perovskite Compounds.

Although research on organic-inorganic hybrid perovskites (OIHPs) has grown exponentially in the past two decades, the high phase transition temperature of OIHP materials is still one of the insurmountable difficulties. Herein, a series of A2BX4 type OIHP materials [(2,n-DFBA)2PbCl4] (n = 3, for 1; n = 4, for 2; n = 5, for 3; n = 6, for 4) have been prepared by reactions of double-substituted difluorobenzylamine (difluorobenzylamine = DFBA) with lead chloride in concentrated HCl aqueous solution. It was found the OIHP compounds 1-3 proceed a switchable phase transition with phase transition temperatures (Tc) at 449 K (1), 462 K (2) and 500 K (3), higher than that of the parent compound [(BA)2PbCl4] (BA = benzylammonium) at 438 K, but compound 4 exhibits no phase transition. A crystal structure analysis elucidated that the organic template ligands DFBA lead in the inorganic part in compounds 1-3 to a two-dimensional (2D) perovskite structure, while that in compound 4 leads to a one-dimensional (1D) chain structure. The different double-substituted positions of fluorine atoms on benzylamine have important influences on the phase transition in compounds 1-4.

Micro-spectrophotometric determination of nickel in Gentiana rigescens after switchable hydrophilicity solvent-based ultrasound-assisted liquid phase microextraction

In this work, switchable hydrophilicity solvent-based ultrasound-assisted liquid phase microextraction (SHS-UA-LPME) was combined with micro-volume UV-vis spectrophotometry for the determination of trace nickel in the medicinal plant Gentiana rigescens Franch. ex Hemsl. (G. rigescens) samples for the first time. Micro-volume spectrophotometry has the characteristics of microanalysis, economy and low operation cost, which is feasible to be combined with miniaturized enrichment method. Dipropylamine (DPA) as a switchable solvent completed the extraction during the phase conversion process. It was changed from hydrophobic to hydrophilic under the action of HCl, and then completed phase transition under the action of NaOH. The parameters influencing the extraction efficiency were investigated. Under the optimal conditions, the enhancement factor (EF), the limit of detection (LOD), the limit of quantitation (LOQ) and relative standard deviation (RSD, n = 7) were 28, 0.02 µg/L, 0.067 µg/L and 1.4%, respectively. The established method was applied to the determination of G. rigescens samples collected from the local field with satisfactory results.

Development of a switchable solvent liquid phase extraction method for the determination of chlorthiamid, ethyl parathion, penconazole and fludioxonil pesticides in well, tap and lake water samples by gas chromatography mass spectrometry

This study presents a switchable solvent liquid phase extraction (SS-LPE) method for the enrichment of four pesticides, and their subsequent determination by gas chromatography mass spectrometry (GC–MS). Box-Behnken experimental design was utilized to attain optimum conditions of the SS-LPE method by navigating a design model developed according to parameter effects and their interactions. Significant parameters were evaluated using analysis of variance (ANOVA), and the optimum variables were selected from a list of combinations presented by the model predictor. The detection limits calculated for chlorthiamid, ethyl parathion, penconazole and fludioxonil were 0.58, 0.73, 0.33 and 0.28 ng/mL. These detection limits correlated to enhancement factors in the range of 60–150 folds. Repeatability based on intra-day and inter-day analysis produced percent relative standard deviations below 10%, a good indicator of high precision. Well water, tap water and lake water samples were employed as real sample matrices to test the trueness of the method and its applicability. The recovery results calculated for the samples spiked at different concentrations were satisfactory (90–105%), and this validated the method for real sample applications.

Dual-band and dual-polarized programmable metasurface unit with independent channels

Highly efficient aperture use and real-time control are important for current RF systems to achieve outstanding system performance. In this paper, we propose a novel dual-band and dual-polarized programmable metasurface unit (PMU) with two switchable phase states. Utilizing the dual-band and dual-polarized properties of parasitic patch antennas, the PMU can realize independent control of two channels by switching the PIN diodes. Because of the separation of frequency bands and orthogonal polarizations, the PMU posesses high isolation between two channels. Meanwhile, spoof surface plasmon polariton and choke structures are designed to further improve channel isolation. Each channel of the PMU has two states (state ‘0’ and state ‘1’) with a 180° phase difference between them, which is the basis for constructing programmable metasurfaces. The simulated and measured results illustrate the excellent performance of the proposed PMU. Through a detailed discussion of the functions of metasurfaces composed of the proposed PMU, the independent control of two channel beams is demonstrated in real time. Hence, the proposed dual-band and dual-polarized PMU may find wide applications in satellite communications, radar systems and other scenarios.

The switchable phase transition of sodium sulfate crystals activated by shock waves

A shock-wave-induced reversible phase-transformation from phase-V to phase-III of Na2SO4 is achieved, and the results are evidenced via XRD and Raman spectroscopy.

Switchable phase transition between crystalline and amorphous states of CuSO4·5H2O by dynamic shock waves

In this communication, we report the switchable phase transition occurring between the crystalline and amorphous states of CuSO4·5H2O, influenced by dynamic shock waves, and the results have been evaluated by XRD and Raman techniques.

A Switchable Solvent-Based Liquid Phase Microextraction Method for the Detection of Cadmium in Water Samples with Flame Atomic Absorption Spectrometry

The natural concentration of trace elements in water and soil depends on the geological, geomorphological, and climate characteristics of the region. The rapid increase of technology in recent years has increased concentrations of trace elements in nature. Separation and enrichment methods are needed to detect trace amounts of heavy metals that cannot be detected due to the detection limit of the instruments or the matrix effect in samples. Recently, low hazard solvents compatible with green chemistry have been used in preconcentration/separation studies of Cd(II). Switchable solvent-based liquid phase microextraction is an environmentally-friendly, simple, and fast procedure for the determination of Cd(II) ions in environmental samples combined with flame atomic absorption spectrometry (FAAS). The switchable polarity solvent was prepared with N,N-dimethyl-n-octylamine. 2-(5-Bromo-2-pyridylazo)-5-(diethylamino) phenol was used as the complexing agent. Important parameters such as pH, amount of switchable polarity solvent and NaOH, as well as ligand and sample volume, all of which might affect the microextraction efficiency were optimized. Under optimal experimental conditions, linear range was found to be between 5 and 500 µg/L. The limit of detection, preconcentration factor, and relative standard deviation were 0.89 μg/L, 150, and 3.2%, respectively. The accuracy of our method was confirmed by the analysis of certified reference material SPS-WW1 Batch 106 (Waste Waters). The developed procedure was successfully applied to determine the cadmium contents of environmental water samples. We believe that this environmentally-friendly method will be useful in detecting Cd(II) ions in water samples.

Active Manipulation of The Spin and Orbital Angular Momentums in a Terahertz Graphene-Based Hybrid Plasmonic Waveguide.

Angular momentums (AMs) of photons are crucial physical properties exploited in many fields such as optical communication, optical imaging, and quantum information processing. However, the active manipulation (generation, switching, and conversion) of AMs of light on a photonic chip remains a challenge. Here, we propose and numerically demonstrate a reconfigurable graphene-based hybrid plasmonic waveguide (GHPW) with multiple functions for on-chip AMs manipulation. Its physical mechanism lies in creating a switchable phase delay of ±π/2 between the two orthogonal and decomposed linear-polarized waveguide modes and the spin-orbit coupling in the GHPW. For the linear-polarized input light with a fixed polarization angle of 45°, we can simultaneously switch the chirality (with −ħ/+ħ) of the transverse component and the spirality (topological charge ℓ = −1/+1) of the longitudinal component of the output terahertz (THz) light. With a switchable phase delay of ±π in the GHPW, we also developed the function of simultaneous conversion of the charity and spirality for the circular-polarized input light. In addition, a selective linear polarization filtering with a high extinction ratio can be realized. With the above multiple functions, our proposed GHPWs are a promising platform in AMs generation, switching, conversion, and polarization filtering, which will greatly expand its applications in the THz photonic integrated circuits.

Simple and Green Vortex-Assisted Switchable Solvent Liquid Phase Microextraction for the Determination of Indium in Soil with Matrix Matching and Slotted Quartz Tube (SQT) – Flame Atomic Absorption Spectrometry (FAAS)

A novel preconcentration methodology to enhance the sensitivity of a flame atomic absorption spectrometer for indium determination was investigated in this study. The proposed methodology is based on the application of switchable solvent based liquid-phase microextraction combined with a slotted quartz tube. The isolation of indium was performed using N, N-dimethylbenzylamine as the extraction solvent after complexation with (E)-2,4-dibromo-6-(((3-hydroxyphenyl)imino)methyl)phenol. The detection power was enhanced by approximately 169-fold using the developed method with respect to the conventional flame atomic absorption spectrometry system. The quantification and detection limit values were 28.3 and 8.4 ng mL−1, respectively. The assessment of several interfering ions on the analyte was performed, and spike experiments were used to validate the method’s accuracy. Interferences were observed for a ratio of 1:10 analyte:interferent with a value of 27%. The recovery results obtained using matrix matching strategy indicated the applicability of the developed method for soil matrices.

The Role of Substitution in the Apex Position of the Bent-Core on Mesomorphic Properties of New Series of Liquid Crystalline Materials

We present the synthesis and mesomorphic properties of the new series of bent-core liquid crystals based on 3-hydroxybenzoic acid bearing a lateral substituent in the apex position. Four different substituents of various sizes and electronic properties have been used. We have found that only compounds substituted with fluorine are mesogenic and exhibit one mesophase, whose type differs when prolonging the terminal alkyl chain. For homologues with shorter alkyl chains (octyl, decyl), a columnar B1-type of a mesophase was observed, while materials with longer terminal chains (dodecyl, tetradecyl) exhibited a switchable lamellar SmCAPA phase. Calorimetric measurements, texture observations under a polarizing microscope were performed and electro-optical properties studied. Additionally, dielectric measurements were realized to characterize the molecular dynamics in the SmCAPA phase. All mesogenic compounds were further studied by X-ray measurements to confirm phase identification and obtain more information about their structural parameters.

Multivariate optimisation of a novel green microextraction method for Fe (III) determination in environmental samples by FAAS

ABSTRACT Industrial development has led to increased heavy metal pollution in bodies of water all over the world. Numerous methods are being developed with the aim of detecting and subsequently removing heavy metal ions from water with hopes of reversing pollution. Here, we present a novel and ecological switchable solvent-based liquid phase microextraction (SS-LPME) method that detects Fe (III) in water samples before they can be tested on flame atomic adsorption spectrometry. In this method, 2-(5-Bromo-2-pyridylazo)-5-(diethylamino) phenol was selected as a complexing agent and switchable polarity solvent was formulated with N, N-dimethyl-n-octylamine. Box–Behnken response surface design was used to investigate and optimise factors associated with the extraction recovery. When the optimal conditions were reached, a linear calibration curve was achieved at 0.05–400 µg L−1. The preconcentration factor was 200, the detection limit was 0.015 µg L−1 with the relative standard deviation (RSD) of 2.2% (at 30 µg L−1; n = 8). Water samples and wastewater reference material (SPSWW1) were used to test the applicability and success of the method.

Switchable Phase Transformation (Orthorhombic–Hexagonal) of Potassium Sulfate Single Crystal at Ambient Temperature by Shock Waves

In this research article, shock wave induced switchable phase transition (β to α and α to β) of potassium sulfate (K2SO4) crystal is demonstrated. The test crystals are subjected to shock waves of ...

Liquid crystal integrated metalens with tunable chromatic aberration

Overcoming chromatic aberrations is a vital concern in imaging systems in order to facilitate full-color and hyperspectral imaging. By contrast, large dispersion holds opportunities for spectroscopy and tomography. Combining both functions into a single component will significantly enhance its versatility. A strategy is proposed to delicately integrate two lenses with a static resonant phase and a switchable geometric phase separately. The former is a metasurface lens with a linear phase dispersion. The latter is composed of liquid crystals (LCs) with space-variant orientations with a phase profile that is frequency independent. By this means, a broadband achromatic focusing from 0.9 to 1.4 THz is revealed. When a saturated bias is applied on LCs, the geometric phase modulation vanishes, leaving only the resonant phase of the metalens. Correspondingly, the device changes from achromatic to dispersive. Furthermore, a metadeflector with tunable dispersion is demonstrated to verify the universality of the proposed method. Our work may pave a way toward active metaoptics, promoting various imaging applications.

Microstructural, crystallographic, and luminescent analysis after grinding high-temperature monoclinic bismuth phosphate

Phase transformation of inorganic materials is usually done via either the re-arrangement of structural units at high pressures and/or temperatures or bottom-up construction from cations and anions using solution chemistry-related approaches. The purpose of this study was to evaluate the microstructural, crystallographic, and luminescent changes after grinding a high-temperature monoclinic phase (H-BPO) of bismuth phosphate. Initially, the pre-ground H-BPO was formed by solid-state reaction of the starting materials. After mechanical grinding, the pre-ground H-BPO gradually transformed to another low-temperature monoclinic phase (L-BPO). Furthermore, a switchable phase transformation from L-BPO to H-BPO was observed for the sample after grinding followed by annealing at high temperature. For the samples obtained by grinding or grinding followed by annealing, the microstructure, crystallography, and luminescence properties were characterized by SEM, XRD with Rietveld analysis, FT-IR, Raman, and photoluminescence (PL) spectra in detail. The switchable phase transformation was elucidated by taking into account the effects of the particle size, and lattice strain as well as other structural factors such as the arrangements of BiO8 polyhedra and PO4 tetrahedra, unit lattice volume (V/Z), and the symmetry of PO4 groups. The phase transition from H-BPO to L-BPO occurred at a relatively low pressure generated under grinding, which is irreversible and 1st order nature. Moreover, with the switchable phase transformation, the luminescence properties including emission intensity, decay time, and quantum efficiency were assessed.

Determination of iron in hair samples by slotted quartz tube-flame atomic absorption spectrometry after switchable solvent liquid phase extraction

In this study, a green switchable solvent based liquid phase extraction (SS-LPE) method was developed for the determination of iron in human hair matrix at very low concentrations. The switchable solvent was synthesized from N,N-Dimethlybenzylamide (DMBA) and ultrapure water with the addition of dry ice for protonation, and used as the extraction solvent. The optimum conditions obtained for 8.0 mL aqueous solution after univariate optimization were 1.5 mL of pH 4.0 buffer solution, 0.75 mL of 0.015 % ligand solution, 0.75 mL of switchable solvent, 45 s vortex period for complexation and extraction, 1.25 mL of 1.50 M NaOH and 30 s vortex period after the addition of NaOH. Under the optimum conditions, a 92-fold improvement was obtained in the detection power of the flame atomic absorption spectrometry (FAAS). The limit of detection (LOD) and limit of quantification (LOQ) values were found to be 2.6 and 8.6 μg/L, respectively. Linear range of the developed method was between 11 and 75 μg/L, with a correlation coefficient (R2) value of 0.9992. Accuracy and the applicability of the proposed method were verified by recovery studies and the results obtained for 15, 20, 30 and 40 μg/L spiked concentrations were 113.3 ± 4.9, 90.6 ± 4.4, 102.8 ± 8.2 and 98.1 ± 7.5 %, respectively.

Switchable active phase modulation and holography encryption based on hybrid metasurfaces

Abstract Metasurfaces are planar devices containing delicately designed nanoantenna or resonator arrays that allow for beam shaping, super resolution imaging, and holography. Hybrid metasurface – by integrating with tunable materials such as two-dimensional materials and phase change materials (PCMs) – provides a potential platform for active modulation of wavefronts. Specifically, PCMs can flexibly switch between crystalline and amorphous states with nonvolatile property under external stimuli and provide a large refractive permittivity contrast. Using metasurfaces based on PCM to manipulate wavefronts may provide new opportunities for switchable functionalities. Here, we propose two types of metasurface devices based on whole PCM films to realize switchable holography and simultaneous phase and interference encryption. This feature can be used to encrypt information in a switched state and store camouflage information in the other state by simply applying external thermal stimuli to the entire metasurface. This method can be applied in areas such as beam shaping, optical encryption, and anti-counterfeiting.

Biofunctionalized chondrogenic shape-memory ternary scaffolds for efficient cell-free cartilage regeneration

Cartilage defect repair remains a great clinical challenge due to the limited self-regeneration capacity of cartilage tissue. Surgical treatment of injured cartilage is rather difficult due to the narrow space in the articular cavity and irregular defect area. Herein, we designed and fabricated chondrogenic and physiological-temperature-triggered shape-memory ternary scaffolds for cell-free cartilage repair, where the poly (glycerol sebacate) (PGS) networks ensured elasticity and shape recovery, crystallized poly (1,3-propylene sebacate) (PPS) acted as switchable phase, and immobilized bioactive kartogenin (KGN) endowed the scaffolds with chondrogenic capacity. The resultant scaffolds exhibited shape-memory properties with shape-memory fixed ratio of 98% and recovered ratio of 97% at 37°C for PPS/PGS/KGN-100, indicating a good potential for minimally invasive implantation. The scaffolds gradually degraded in Dulbecco's phosphate-buffered saline and released KGN up to 12 weeks in vitro. In addition, the scaffolds promoted chondrogenic differentiation while inhibiting osteogenic differentiation of bone marrow-derived mesenchymal stem cells in a concentration-dependent manner and cartilage regeneration in full-thickness defects of rat femoropatellar groove for 12 weeks. Consequently, the PPS/PGS/KGN-100 scaffolds stimulated the formation of an overlying layer of neocartilage mimicking the characteristic architecture of native articular cartilage even in the absence of exogenous growth factors and seeded cells. This study provides much inspiration for future research on cartilage tissue engineering. Statement of SignificanceThere are two crucial challenges for cartilage defect repair: the lack of self-regeneration capacity of cartilage tissue and difficult scaffold implantation via traditional open surgery due to space-limited joints. Herein, bioactive body-temperature-responsive shape memory scaffolds are designed to simultaneously address the challenges. The scaffolds can be readily implanted by minimally invasive approach and recover by body-temperature of patient. The integration of kartogenin endows scaffolds the bioactivity, leading to the first example of bulk shape-memory scaffolds for cell-free cartilage repair. These characteristics make the scaffolds advantageous for clinical translation. Moreover, our developed material is easy to be functionalized due to the presence of extensive free hydroxyl groups and provides a versatile platform to design diverse functional shape memory biomaterials.

Combination of ultrasound-assisted ethyl chloroformate derivatization and switchable solvent liquid-phase microextraction for the sensitive determination of l-methionine in human plasma by GC-MS.

A green and fast analytical method for the determination of l-methionine in human plasma is presented in this study. Preconcentration of the analyte was carried out by switchable solvent liquid phase microextraction after ethyl chloroformate derivatization reaction. Instrumental detection of the analyte was performed by means of gas chromatography-mass spectrometry. N,N-Dimethyl benzylamine was used in the synthesis of switchable solvent. Protonated N,N-dimethyl benzylamine volume, volume/concentration of sodium hydroxide, and vortex period were meticulously fixed to their optimum values. Besides, ethyl chloroformate, pyridine, and ethanol volumes were optimized in order to get high derivatization yield. After the optimization studies, limit of detection and quantitation values were attained as 3.30 and 11.0ng/g, respectively, by the developed switchable solvent liquid phase microextraction gas chromatography-mass spectrometry method that corresponding to 76.7-folds enhancement in detection power of the gas chromatography-mass spectrometry system. Applicability and accuracy of the switchable solvent liquid phase microextraction-gas chromatography-mass spectrometry method were also checked by spiking experiments. Percent recovery results were ranged from 97.8 to 100.5% showing that human plasma samples could be analyzed for its l-methionine level by the proposed method.