Physical Property Measurement System Research Articles

Probing Evolution of the Flux-Pinning Landscape in REBCO Coated Conductors Caused by Gamma Irradiation Using DC and AC Magnetometry: A Novel Approach to Tokamak Magnet Material Development

Optimisation of REBCO coated conductor tapes specifically for use in nuclear fusion will help improve the magnet component lifetimes in future tokamak reactor power plants. The focus of this work was exploration of a novel approach to irradiation studies on REBCO tapes, utilising multiple magnetic measurements to probe evolution of the REBCO flux-pinning landscape more deeply than reported in other studies, for the purpose of identifying primary limiting factors affecting performance. Gamma irradiation experiments were conducted, and pre-/post-irradiation results from DC and AC magnetic measurements using a Physical Property Measurement System (PPMS) are discussed. Magnetisation critical current density (Jc) decreased in all samples with increasing dose, except for the silver overlayer-only samples which did not contain artificial pinning centres (APCs), where Jc increased with dose. Removal of the copper stabiliser coupled with the presence of APCs allowed gamma irradiation to induce pinning force maximum peak shifts, from above 14 T before irradiation to below 9 T afterwards. Flux creep rate varied with the evolving pinning landscape, and the degree of Jc degradation directly correlated with creep rate fluctuations post-irradiation. Changes in critical temperature and diamagnetic saturation also corresponded with changes in Jc and flux creep rate. The major conclusion from this study was that minimisation of flux creep rate is the key to maintenance of performance under fusion-relevant operating conditions. Flux creep manifests as problematic AC losses in all high-temperature superconducting machines; therefore, future work will focus on reduction/prevention of the phenomenon to enhance longevity of performance in any application.

Thermodynamic data of a promising cathode material NaV6O15 and its synthesis/decomposition thermodynamic analysis

Sodium-ion batteries have emerged as a promising alternative to lithium-ion batteries due to their lower cost and similar electrochemical properties. The development of high-capacity and long-life electrode materials is crucial for advancing sodium-ion battery research. A significant amount of research has been conducted on the electrochemical properties of NaV6O15, however, there remains a dearth of data on its thermodynamic properties. Herein, NaV6O15 was synthesized using the solid-phase sintering method and thoroughly characterized. Thermodynamic data in the temperature ranges of 298.15–900 K, 15–303 K, and 573–873 K were determined using the Neumann-Kopp rule, low-temperature physical property measurement system, and MHTC 96 line, respectively. The heat capacity equation of NaV6O15 was derived and its enthalpy, entropy, and Gibbs free energy (298.15–800 K) were calculated. Moreover, the thermodynamics of NaV6O15-related formation and decomposition reactions were analyzed. The obtained heat capacity equation of NaV6O15 was Cp=517.05524+0.08612T−1.25053×107T−2(J/mol·K)(298.15∼873K). This study addresses the thermodynamic knowledge gaps of NaV6O15 and provides valuable insights for its preparation and decomposition in manufacturing processes.

Study on the welding properties of modified N50 CICC jacket for future fusion applications

The modified N50 (N50H) cable-in-conduit conductor CICC jacket developed by China will be applied in China Fusion Engineering Test Reactor (CFETR). Building upon the N50H material, China has developed a corresponding welding material and conducted R&D work on N50H jacket welding. We simulated the N50H jacket welded joint to replicate the entire process of CICC preparation, which includes extrusion, bending, straightening and aging. The magnetic properties of welded joints were evaluated at various temperatures using a physical property measurement system. In addition, the microstructure of the welded joint was studied by various microscopic analysis techniques, and the welded joint showed a stable austenitic structure. Furthermore, mechanical properties of the welded joints were investigated at different temperatures with particular emphasis on their behavior at 4.2 K. The circle-in-square ReBCO conductor jackets welding joint showed a yield strength greater than 1500 MPa, a fracture toughness KIC better than 260 MPa m1/2 and the elongation at break is more than 30 % at 4.2 K. However, a decrease in strength, ductility, and fracture toughness is observed within the welded joints of Nb3Sn conductor jackets after undergoing an aging process. This study will present experimental data on welding joints and discuss the feasibility of N50H as a high-magnetic field jacket material for next-generation fusion reactors.

Preparation, microstructure and corrosion resistance of Al2O3 coatings by cathodic plasma electrolytic deposition on sintered NdFeB permanent magnet

The Al2O3 ceramic coatings were prepared on the sintered NdFeB magnets by cathodic plasma electrolytic deposition (CPED) method in aluminum nitrate alcohol solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), thermal shock, hydrothermal weight loss, electrochemical corrosion and physical property measurement system (PPMS), respectively. The results show that the coatings mainly consist of γ-Al2O3 and α-Al2O3 phases, and the volume of α-Al2O3 increases with increasing the voltages. The surface of the coatings shows a typical coral reef structure, and the thickness of the coatings increases from 29 µm to 53 µm with increasing the voltages. The Al2O3 coatings have excellent thermal shock resistance as well as the excellent corrosion resistance in hydrothermal conditions. The corrosion resistance of the coatings enhances with increasing the voltages, reaching the strongest at 470 V, and then decreases. This study provides a new method for forming ceramic coatings on the surface of sintered NdFeB magnets to improve its corrosion resistance.

Green Synthesis, Characterization and Application of Proanthocyanidins-Functionalized Fe3O4 Magnetic Nanocomposites

In this study, proanthocyanidins-functionalized Fe3O4 magnetic nanocomposites were synthesized by the hydrothermal method. The prepared Fe3O4 nanocomposites were characterized by Fourier transform infrared spectrometer (FTIR), X-ray powder diffractometer (XRD), physical property measurement system (PPMS), particle size analyzer, scanning electron microscope (SEM), and transmission electron microscope (TEM). FTIR results indicated that the obtained products were coated with proanthocyanidins. The SEM and TEM results, as well as particle size distribution analysis, revealed that the obtained products were spherical particles with average diameter of [Formula: see text][Formula: see text]nm. XRD and PPMS characterization confirmed that the Fe3O4 nanoparticles have a cubic spinel structure with magnetic properties. The performance of the Fe3O4 nanocomposites for removing organic dyes in an aqueous solution was investigated. The synthesized products were found to be effective on removing various organic dyes, such as Methylene blue (MB), neutral red (NR) and Rhodamine B (RhB), indicating their considerable potential as efficient dyes adsorbents for wastewater treatment.

Methodology to Characterize Thermal Properties of Thin Film Superconductors Using a DynaCool Physical Property Measurement System

We describe a methodology to characterize heat capacity <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C<inline-formula><tex-math notation="LaTeX">$_{p}$</tex-math></inline-formula></b> of 1 μm thick Nb thin films at a temperature range of 60 K to 1.8 K. We used a commercially available relaxation calorimeter device by Quantum Design DynaCool Physical Property Measurement System (PPMS). The mass of thin films is negligible compared to the minimum coarse estimate required by the heat capacity module of the PPMS. To overcome this limitation, a vertical stack of multiple diced substrates of the same material with uniform dimensions of 2.5 mm x 2.5 mm was joined by cryogenically compatible grease to form a stack resulting in a larger effective mass of the target film. The critical behavior of heat capacity in the region of the transition temperature is demonstrated. The heat capacity of Nb thin films was measured by subtracting the total heat capacity of the joining grease and stack of substrate used as addenda. Results in this work prove that a vertical stacking approach is viable for measuring the behavior of deposited thin films.

High-$T_{C}$ Superconducting Quantum Interference Device Implemented on a Pulsed Tube Cooler for 1 to 50 K Materials Characterization

Here we report the fabrication and electrical characterization of high-transition temperature SQUIDs directly written by helium ion beam irradiation for use in Quantum Design's pulsed tube cooler based physical property measurement system. Our device consists of a SQUID with a direct coupled 300 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m diameter flux focusing pickup loop. When DC biased above the critical current, we observe a modulation in the voltage with a peak-to-peak amplitude of 500 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> V, while having periodicity of 275 nT per flux quantum. The SQUID chip was mounted to the temperature-controlled system equipped with optically aligned piezo scanners which allow the accurate positioning of the sample less than 100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m from the sensor. The system functions as a magnetic properties characterization tool which can operate over a wide temperature range (1 - 50K) without thermally isolating the SQUID from the sample.

The influence of magnetic particle incorporation on bisphenol A removal by β-cyclodextrin-derived sorbent

A novel, biomass-derived hybrid sorbent Ban-CD-EPI-Fe was successfully synthesized in a coprecipitation method, in which β-cyclodextrin copolymerized with banana peel extract and epichlorohydrin was grafted onto an iron oxide surface. The composition, presence of functional groups, morphology, thermal stability, and magnetic properties of the obtained material were characterized by Powder X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Thermogravimetric Analysis (TGA), and Physical Properties Measurement System (PPMS). The material bearing around 28% of β-cyclodextrin units has mesoporous structure with plate-like morphology and active surface area determined by BET and Langmuir models equal to 38.35 and 53.59 m2 g−1, respectively. The sorption studies aimed to remove an endocrine disruptor – bisphenol A (BPA), from water. The results showed that the time evolution could be fitted with pseudo-second kinetic order with a rate constant k equal to 0.05 g mg−1 min−1. According to the Langmuir isotherm, a monolayer is created during BPA sorption, and the maximum sorption capacity was estimated as 93.5 mg g−1. After BPA sorption, the hybrid material could be easily separated by an external magnet and regenerated under mild conditions keeping its recyclability in at least eight cycles.

Investigations on the polymorphism of K4CaSi6O15 at elevated temperatures.

In the present study, single crystals and polycrystalline material of K4CaSi6O15 were prepared from solid-state reactions between stoichiometric mixtures of the corresponding oxides/carbonates. Heat capacity (C p) measurements above room temperature using a differential scanning calorimeter indicated that two thermal effects occurred at approximately T 1=462 K and T 2=667 K, indicating the presence of structural phase transitions. The standard third-law entropy of K4CaSi6O15 was determined from low-temperature C p's measured by relaxation calorimetry using a Physical Properties Measurement System and amounts to S°(298K)=524.3±3.7 J·mol-1·K-1. For the 1st transition, the enthalpy change ΔH tr1=1.48kJ·mol and the entropy change ΔS tr1=3.25 J·mol-1·K-1, whereas ΔH tr2=3.33kJ·mol-1 and ΔS tr2=5.23 J·mol-1·K-1 were determined for the 2nd transition. The compound was further characterized by in-situ single-crystal X-ray diffraction between ambient temperature and 1063 K. At 773 K, the high-temperature phase stable above T 2 has the following basic crystallographic data: monoclinic symmetry, space group P21/c, a=6.9469(4) Å, b=9.2340(5) Å, c=12.2954(6) Å, β=93.639(3)°, V=787.13(7) Å3, Z=2. It belongs to the group of interrupted framework silicates and is based on tertiary (Q3-type) [SiO4]-tetrahedra. Together with the octahedrally coordinated Ca-cations, a three-dimensional mixed polyhedral network structure is formed, in which the remaining K-ions provide charge balance by occupying voids within the net. The intermediate temperature modification stable between T 1 and T 2 shows a (3+2)-dimensional incommensurately modulated structure that is characterized by the following q-vectors: q1=(0.057, 0.172, 0.379), q2=(-0.057, 0.172, -0.379). The crystal structures of the high- and the previously studied ambient temperature polymorph (space group Pc) are topologically equivalent and show a group-subgroup relationship. The index of the low- in the high-symmetry group is six and involves both, losses in translation as well as point group symmetry. The distortion is based on shifts of the different atom species and tilts of the 4- and 6-fold coordination polyhedra. Actually, for some of the oxygen atoms, the displacements exceed 0.5 Å. A more detailed analysis of the distortions relating to both structures has been performed using mode analysis, which revealed that the primary distortion mode transforms according to the Λ1 irreducible representation of P21/c. However, other modes with smaller distortion amplitudes are also involved.

Magnetic Analysis of MgFe Hydrotalcites as Powder and Dispersed in Thin Films within a Keratin Matrix.

Hydrotalcites (HTlcs) are a class of nanostructured layered materials that may be employed in a variety of applications, from green to bio technologies. In this paper, we report an investigation on HTlcs made of Mg and Fe, recently employed to improve the growth in vitro of osteoblasts within a keratin sponge. We carried out an analysis of powder materials and of HTlcs dispersed in keratin and spin-coated on a Si/SiO2 substrate at different temperatures. A magnetic study of the powders was carried out with a Quantum Design Physical Property Measurement System equipped with a Vibrating Sample Magnetometer. The data gathered prove that these HTlcs are fully paramagnetic, and keratin showed a very small magnetic response. Optical and Atomic Force Microscopy analyses of the thin films provide a detailed picture of clusters randomly dispersed in the films with various dimensions. The magnetic properties of these films were characterized using the Nano Magneto Optical Kerr Effect (NanoMOKE) down to 7.5 K. The data collected show that the local magnetic properties can be mapped with a micrometric resolution distinguishing HTlc regions from keratin ones. This approach opens new perspectives in the characterization of these composite materials.

Effects of low voltage ionized hydrogen ion bombardment in semi-insulating GaAs

In this paper, H+ is used to bombard N-type undoped GaAs substrates. This process imparts semiconductor-like electrical properties to GaAs substrates, which are inherently semi-insulating, semiconductor-like electrical properties. Atomic force microscopy, Transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy were used to measure the shape and structure of the sample, and the Physical Property Measurement System was used to test the electrical properties of the samples. According to the results, the treated GaAs substrate surface has hole-type conductivity at 84 K and electron-type conductivity at room temperature. This method not only does not cause damage to the lattice structure of the GaAs surface, but also realizes the transformation of the GaAs surface properties, which provides a new idea for the development of GaAs-based heterojunction devices in the future.

Chitosan-based nano-sorbents: synthesis, surface modification, characterisation and application in Cd (II), Co (II), Cu (II) and Pb (II) ions removal from wastewater

In contemplation of treating hazardous industrial wastewater, sodium tripolyphosphate (TPP) and vanillin (V)-modified chitosan-based magnetic nano-sorbents (TPP-CMN and V-CMN) were prepared, and the physical and surface properties of both nano-sorbents were characterised. The results of FE-SEM and XRD showed an average size of between 6.50 and 17.61 nm for Fe3O4 magnetic nanoparticles. The Physical Property Measurement System (PPMS) was carried out, and the saturation magnetisations for chitosan, Fe3O4 nanoparticles, TPP-CMN, and V-CMN were 0.153, 67.844, 7.211, and 7.772 emu.g−1, respectively. By using multi-point analysis, the BET surface areas of the synthesised TPP-CMN and V-CMN nano-sorbents were found to be 8.75 and 6.96 m2/g, respectively. The synthesised TPP-CMN and V-CMN were investigated as effective nano-sorbents to uptake Cd (II), Co (II), Cu (II), and Pb (II) ions, and the results were investigated by AAS. The adsorption process of heavy metals was investigated by the batch equilibrium technique, and the sorption capacity values of Cd (II), Co (II), Cu (II), and Pb (II) ions by TPP-CMN were 91.75, 93.00, 87.25, and 99.96 mg/g. By V-CMN, the values were 92.5, 94.00, 88.75, and 99.89 mg/g, respectively. The equilibrium times for adsorption were found to be 15 minutes for TPP-CMN and 30 minutes for V-CMN nano-sorbents. The adsorption isotherms, kinetics, and thermodynamics were studied to understand the adsorption mechanism. Furthermore, the adsorption of two synthetic dyes and two real wastewater samples was studied and obtained significant results. These nano-sorbents’ simple synthesis, high sorption capability, excellent stability, and recyclability may provide highly efficient and cost-effective nano-sorbents for wastewater treatment.

Thermodynamic properties study of polyoxometalate Na7[H2PV14O42

Lithium-ion batteries (LIBs) are widely used in electronic applications because of their high voltage, high specific energy, long lifespan, and other characteristics. Electrode materials have garnered interest as an indispensable component of LIBs. Na7[H2PV14O42] is used as an electrode material because of its excellent properties. In this study, Na7[H2PV14O42] was synthesized by the water bath method using NaVO3 as the raw material, experimentally characterized, and its thermodynamic data were measured using the Neumann-Kopp rule from 298.15 to 843K, a Physical Property Measurement System from 15 to 309K, and the MHTC 96 line from 473 to 773K. The data were fitted to the Debye-Einstein heat capacity equation at low temperatures and a polynomial function at higher temperatures. The heat capacity equation of Na7[H2PV14O42] was obtained from the fitted curves. The corresponding enthalpy (▵298.15 THm), entropy (▵298.15 TSm), and Gibbs energy (▵298.15 TGm) (from 298.15 to 800K) were calculated according to the heat capacity equation. The obtained heat capacity of Na7[H2PV14O42], as a function of temperature, was modeled as Cp = 1502.30 + 0.27T - 2.44E7T-2J mol-1K-1 (473-773K). This study can compensate for the thermodynamic deficiency of Na7[H2PV14O42].

Thickness-Dependent Topological Hall Effect in 2D Cr5 Si3 Nanosheets with Noncollinear Magnetic Phase.

Antiferromagnets with noncollinear spin order are expected to exhibit unconventional electromagnetic response, such as spin Hall effects, chiral abnormal, quantum Hall effect, and topological Hall effect. Here, 2D thickness-controlled and high-quality Cr5 Si3 nanosheets that are compatible with the complementary metal-oxide-semiconductor technology are synthesized by chemical vapor deposition method. The angular dependence of electromagnetic transport properties of Cr5 Si3 nanosheets is investigated using a physical property measurement system, and an obvious topological Hall effect (THE) appears at a large tilted magnetic field, which results from the noncollinear magnetic structure of the Cr5 Si3 nanosheet. The Cr5 Si3 nanosheets exhibit distinct thickness-dependent perpendicular magnetic anisotropy (PMA), and the THE only emerges in the specific thickness range with moderate PMA. This work provides opportunities for exploring fundamental spin-related physical mechanisms of noncollinear antiferromagnet in ultrathin limit.

An investigation on strain and magnetic properties of perovskite manganite superlattice films

The mixed-valence perovskite manganites attracted much attention because of their interesting electro-magnetic properties, and strain modulation on magnetic properties of perovskite manganites is worth exploring. In this paper, [La[Formula: see text]Ca[Formula: see text]MnO3/La[Formula: see text]Ca[Formula: see text]MnO3][Formula: see text] superlattice films with different La[Formula: see text]Ca[Formula: see text]MnO3 layer thicknesses are prepared by pulsed laser deposition (PLD). The crystal structures (lattice constants) of samples are measured by X-ray diffraction (XRD). The strain of the films is determined according to their crystal structures. The magnetic hysteresis loops (M-H loops) and magnetization versus temperature (M-T) curves of these superlattice films are measured by the physical property measurement system (PPMS). From the M-H loops, the coercive field (H[Formula: see text] of the samples can be measured. From the M-T curves, the Curie temperature (T[Formula: see text] of the samples can be obtained. All samples show a ferromagnetic to paramagnetic transition at TC, and the [La[Formula: see text]Ca[Formula: see text]MnO3/La[Formula: see text]Ca[Formula: see text]MnO3][Formula: see text] sample with the La[Formula: see text]Ca[Formula: see text]MnO3 layer thicknesses of 72[Formula: see text]Å has an antiferromagnetic Néel transition at TN. According to the strain state and magnetic phases, the magnetic properties are comprehensively analyzed. It is found that with the increase of ferromagnetic La[Formula: see text]Ca[Formula: see text]MnO3 layer thickness, the ferromagnetic phase is increased, and the double exchange effect can also be enhanced, resulting in the increase of TC. When the thickness of La[Formula: see text]Ca[Formula: see text]MnO3 reaches 96[Formula: see text]Å, the uneven strain distribution in the superlattice can induce the reduction of ferromagnetic phase compared with antiferromagnetic phase (even antiferromagnetic phase starts to appear), and the double exchange effect can be weakened, and finally leading to the decrease of TC. In addition, with increasing the La[Formula: see text]Ca[Formula: see text]MnO3 layer thickness, HC gradually decreases. The change of HC is related to strain states and magnetic phase interactions in the samples. The analysis of the strain and magnetism can contribute to the understanding of perovskite manganite superlattice films.

Magnetic and electrical properties of LaCoO3 - LaNiO3 epitaxial thin films on LaAlO3 substrate

The mixed transition metal oxide thin films having ABO3 structure noticed numerous applications due to their robust electrical and magnetic properties. Among them, Lanthanum cobalt oxide considered as promising material since it exhibits excellent properties as catalyst and mixed ionic-electronic conductors. In this manuscript, we successfully deposited the epitaxial lanthanum cobalt oxide (LaCoO3) and lanthanum nickel oxide (LaNiO3) thin films on single crystal lanthanum aluminate (LAO) substrate. Individual and bilayer thin films are grown by pulsed laser deposition (PLD). X-ray diffraction pattern reveals the epitaxial nature and phase purity of the deposited thin films. Morphological images has been captured using field-emission scanning electron microscopy (FE-SEM). The electrical and magnetic properties of individual and bilayer LaCoO3/LaNiO3 thin films are measured using four-probe and physical property measurement system (PPMS) respectively. There is a clear ferromagnetic transition in LaCoO3 thin film observed at 85 K. Surprisingly, the bilayer of LaNiO3/LaCoO3 thin films exhibited enhanced magnetic properties compared with individual LaCoO3 or LaNiO3 thin films. The bilayer films revealed the high magnetization and less coercive filed (3.76 emu/cm3, 2215H) respectively. These results given an idea that bilayer LaCoO3/LaNiO3 thin films are capable to exhibit enhanced multifunctional properties.

Study on Texture Formation of Sb2Te Thin Films for Phase Change Memory Applications

We investigated the texture formation of Sb2Te thin films for phase change memory applications. The Sb2Te thin films with different thicknesses were deposited on Si (100) wafers by the magnetron sputtering method. As-deposited Sb2Te thin films were annealed at various temperatures and times. The texture characterization was performed by using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). Experimental results show that the annealed Sb2Te thin films exhibit the 112¯0 and 101¯0 prismatic texture. The formation of prismatic texture is induced by the lattice strain, surface energy, and coarse grains, in which the lattice strain is the essential origin of prismatic preference. Electronic transport properties of Sb2Te thin films were monitored by a physical property measurement system (PPMS). It was found that the formation of prismatic texture promotes the increase of carrier mobility. The stability of the film–substrate interface was also assessed by calculating mismatch. The prismatic-preferred Sb2Te thin films exhibit higher mismatch with a silicon wafer, reducing the interface stability.

Block Copolymer-Assisted Synthesis of Iron Oxide Nanoparticles for Effective Removal of Congo Red.

Iron oxide nanoparticles (IONPs) were synthesized via a block copolymer-assisted hydrothermal method and the phase purity and the crystal structure were investigated by X-ray diffraction. The Rietveld analysis of X-ray diffractometer spectra shows the hexagonal phase symmetry of α-Fe2O3. Further, the vibrational study suggests Raman active modes: 2A1g + 5Eg associated with α-Fe2O3, which corroborates the Rietveld analysis and orbital analysis of 2PFe. The superparamagnetic behavior is confirmed by magnetic measurements performed by the physical properties measurement system. The systematic study of the Congo red (CR) interaction with IONPs using a UV-visible spectrophotometer and a liquid chromatography-tandem mass spectrometry system equipped with a triple quadrupole mass analyzer and an electrospray ionization interface shows effective adsorption. In visible light, the Fe2O3 nanoparticles get easily excited and generate electrons and holes. The photogenerated electrons reduce the Fe3+ ions to Fe2+ ions. The Fe2+/H2O2 oxidizes CR by the Fenton mechanism. The strong adsorption ability of prepared nanoparticles towards dyes attributes the potential candidates for wastewater treatment and other catalytic applications.

Heat capacity of cytisine – the drug for smoking cessation

The characterization of cytisine (CYT) and its blends with poly(lactic acid) was performed using thermal analysis, elemental analysis, infrared spectroscopy, and powder X-ray diffractometry. The heat capacities, total enthalpy, and phase transitions of CYT were established from 1.8 to 448.15 K (−271.35 – 175 °C) by advanced thermal analysis. Data were obtained using a Quantum Design Physical Property Measurement System (PPMS) and a differential scanning calorimetry (DSC). The low-temperature heat capacity of the crystalline CYT in the range of 1.8 to 300 K (−271.35 – 26.86 °C) was measured by PPMS and fitted to a theoretical model in the low temperature region below 11 K (−262.15 °C), to orthogonal polynomials in the middle range 5 K <T < 60 K (−268.15 °C < t < −213.15 °C) and to the Debye and Einstein functions in the high range of temperature above 60 K (−213.15 °C). The liquid heat capacity was calculated based on the approximated linear regression data above the molten state of the experimental heat capacity of CYT obtained by the standard DSC measurements, and it was expressed as Cpliquid = 0.0838T + 346.78 J·K−1·mol−1. The calculated heat capacity in the solid state was extended to a higher temperature and was used, together with liquid heat capacity, as the reference baselines for the advanced thermal analysis of CYT. The PPMS and DSC/TMDSC methods are complementary methods for thermal analysis of cytisine. The PPMS method allowed determination of the equilibrium heat capacity in the solid state, which together with the equilibrium heat capacity in the liquid state allowed to analyze of the experimental apparent heat capacity of cytisine obtained based on DSC. The melting temperature and the total heat of fusion of crystalline material were established as 431.8 K (158.65 °C) and 26.5 kJ·mol−1, respectively. The solid and liquid heat capacities and transition parameters of CYT were applied to calculate total enthalpies for fully amorphous and crystalline states. Analyses of DSC and X-ray confirmed the presence of the solid-solid transition linking with not so far described a polymorphism phenomenon of CYT. Based on the thermogravimetric analysis the temperature of degradation of CYT was determined as 460.5 K (187.35 °C). Also, a preliminary thermal analysis of the blends of cytisine and poly(lactic acid) as a new candidate for drug delivery system was presented.

Reprogrammable liquid-metal/NdFeB/silicone composite magnetic elastomer

Programming the patterned magnetization profile on the magnetic elastomer can enable the magnetic soft robot to produce controlled deformation. But the magnetization profiles are usually unchangeable, which leads to the single function of magnetic soft robot. This paper presents a reprogrammable mangetic elastomer based on liquid-metal/NdFeB/Silicone composites. Liquid-metal/NdFeB functional groups wrapped in silicone matrix can realize repeated magnetization through thermal-assisted magnetic programming. By using several liquid metals (melting points &amp;lt;60 °C), we have manufactured composite magnetic elastomer with regulate-temperature at 15.7, 29.7, 41.5 and 47 °C, respectively. SEM and EDS results exhibits the elastomer’s micromorphology and element content. The elstomer’s magnetic properties are tested by the comprehensive physical property measurement system (PPMS). The moment–temperature (M–T) curve shows the material’s moment jumps at the melt point of the liquid metal. And the moment–magnetic field (M–H) curves indicate that the elastomer exhibit hard and soft magnetic characteristics. At last, a hexagon-shape robot is manufactured and then programmed to two modals of grasping and standing. The experimental results verify the reprogrammability of the proposed composite elastomer. The elastomer is expected to be utilized to manufacture multi-modal magnetic soft robot.