High-pressure Technique Research Articles

Pressure-driven dome-shaped superconductivity in topological insulator GeBi2Te4

The discovery of new superconductors based on topological insulators always captures special attention due to their unique structural and electronic properties. High pressure is an effective way to regulate the lattice as well as electronic states in the topological insulators, thus altering their electronic properties. Herein, we report the structural and electrical transport properties of the topological insulator GeBi2Te4 by using high-pressure techniques. The synchrotron x-ray diffraction revealed that GeBi2Te4 underwent two structural phase transitions from R-3m (phase I) to C2/m (phase II) and then into Im-3m (phase III). Superconductivity was observed at 6.6 GPa to be associated with the first structural phase transition. The superconducting transition temperature Tc reached a maximum value of 8.4 K, accompanied by the RH sign changing from negative to positive at 14.6 GPa, then gradually decreased with increasing pressure in phase III, showing a dome-shaped phase diagram. The present results provide a platform for understanding the interplay between the crystal structure and superconductivity by the regulation of pressure in the topological insulator materials.

Optimization of process parameters for bevacizumab-loaded nanodispersion for lung cancer treatment

Lung cancer is one of the most common and lethal types of cancer worldwide, needing novel therapeutic approaches to enhance patient outcomes. Nanotechnology has emerged as a viable approach to cancer treatment, providing precise drug administration and increased therapeutic efficacy. In this research, we have developed pH-responsive nanodispersion for targeted drug delivery to non-small cell lung cancer. Bevacizumab and calcium phosphate nanoparticle-loaded nanodispersion (BZ-CaP-NDs) were synthesized using a high-pressure homogenization technique. BZ-CaP-NDs are optimized by means of particle size and encapsulation efficiency, and further subjected to the analysis of zeta potential, FTIR, molecular docking, in-vitro release, hemolytic potential assay, and erythrocyte aggregation assay. The analysis for particle size and zeta potential of the optimized BZ-CaP-NDs was found to be 182 ± 1.1 nm and −25.6 mV (Trial 4), respectively. In-vitro drug release showed the efficiency of BZ-CaP-NDs to release BZ at acidic conditions (85.65 ± 1.2%, 72.11 ± 0.98% was released in pH 6.5 and pH 7.4 at 48 h, respectively). Molecular docking studies resulted efficient binding of bevacizumab to VEGF-A protein. The results of the erythrocyte aggregation and hemolytic potential assays indicated that BZ-CaP-NDs were not hazardous, which indicates that, using them for intravenous drug delivery is safe. Thus, the developed BZ-CaP-NDs would be a promising solution for non-small cell lung cancer treatment.

Anomalous metallic conductivity and short-range ferromagnetic correlation in high-pressure synthesized pyrochlore

Iridates show fascinating properties due to the unpredictable ground states of their Ir cations. Generally, Ir5+(5d 4) systems exhibit insulating nonmagnetic states owing to the strong spin-orbit coupling (SOC). Herein a new pyrochlore iridate Hg2Ir2O7 with an Ir5+ charge state synthesized by high-pressure technique is reported. Hg2Ir2O7 crystallizes in the typical cubic pyrochlore crystal structure. The Ir5+ valence state is evidenced by the XAS spectrum. Surprisingly, Hg2Ir2O7 displays short-range ferromagnetic correlations at low temperatures as evidenced by S-shape field-dependent magnetization curves, positive magnetoresistance, and magnetic excitations in specific heat. Furthermore, it also shows metallic conduction and large electron component of specific heat. These results all indicate that Ir5+ in Hg2Ir2O7 deviates from SOC-dominated insulating nonmagnetic states.

Synthesis and characterization of onion-like carbon /TiN0.3 enhanced Si3N4 composites

Research on how to obtain Si3N4 composites with high hardness and toughness at lower temperatures is important. Si3N4 composites with onion-like carbon (OLC)-TiN0.3 were prepared using high pressure and high temperature techniques. The effects of TiN0.3 and OLC additives on the mechanical properties and microstructure of the silicon nitride ceramics were analyzed. During the sintering process, the vacancies in TiN0.3 promoted the formation of the TiC0·3N0.7 interface between the three compositions, whose particles were homogeneously dispersed in the silicon nitride matrix with strong bonding to the substrate. OLC (10 vol%)-TiN0.3 (10 vol%)-Si3N4 composites were prepared at 5 GPa, 1500 °C and held for 15 min. The Vickers hardness and fracture toughness were determined to be 18.6 GPa and 6.6 MPa m1/2, flexural strength of 531 MPa, and showed higher high-temperature hardness. This was higher than the typical values reported for Si3N4 ceramics (15–17 GPa). This work provides a new strategy for low-temperature of Si3N4 composites with both high hardness and high toughness.

Recovery of phenolic compounds from peach pomace using conventional solvent extraction and different emerging techniques.

The study compared high-pressure, microwave, ultrasonic, and traditional extraction techniques. The following extraction conditions were implemented: microwave-assisted extraction (MAE) at 900W power for durations of 30, 60, and 90s; ultrasonic-assisted extraction (UAE) at 100% amplitude for periods of 5, 10, and 15min; and high-pressure processing (HPP) at pressures of 400 and 500MPa for durations of 1, 5, and 10min. The highest yield in terms of total phenolic content (PC) was obtained in UAE with a value of 45.13±1.09mg gallic acid equivalent (GAE)/100g fresh weight (FW). The highest PC content was determined using HPP-500MPa for 10min, resulting in 40mg GAE/100g, and MAE for 90s, yielding 34.40mg GAE/100g FW. The highest value of antioxidant activity (AA) was obtained by UAE in 51.9%±0.71%. The PCs were identified through the utilization of Fourier transform infrared (FTIR) spectroscopy and high-performance liquid chromatography (HPLC). Utilizing multivariate analysis, the construction of chemometric models were executed to predict AA or total PC of the extracts, leveraging the information from IR spectra. The FTIR spectrum revealed bands associated with apigenin, and the application of HPP resulted in concentrations of 5.41±0.25mg/100g FW for apigenin and 1.30±0.15mg/100g FW for protocatechuic acid. Furthermore, HPLC analysis detected the presence of protocatechuic acid, caffeic acid, p-coumaric acid, and apigenin in both green extraction methods and the classical method. Apigenin emerged as the predominant phenolic compound in peach extracts. The highest concentrations of apigenin, p-coumaric acid, and protocatechuic acid were observed under HPP treatment, measuring 5.41±0.25, 0.21±0.04, and 1.30±0.15mg/kg FW, respectively.

Nanostructuring of Additively Manufactured 316L Stainless Steel Using High-Pressure Torsion Technique: An X-ray Line Profile Analysis Study.

Experiments were conducted to reveal the nanostructure evolution in additively manufactured (AMed) 316L stainless steel due to severe plastic deformation (SPD). SPD-processing was carried out using the high-pressure torsion (HPT) technique. HPT was performed on four different states of 316L: the as-built material and specimens heat-treated at 400, 800 and 1100 °C after AM-processing. The motivation for the extension of this research to the annealed states is that heat treatment is a usual step after 3D printing in order to reduce the internal stresses formed during AM-processing. The nanostructure was studied by X-ray line profile analysis (XLPA), which was completed by crystallographic texture measurements. It was found that the as-built 316L sample contained a considerable density of dislocations (1015 m-2), which decreased to about half the original density due to the heat treatments at 800 and 1100 °C. The hardness varied accordingly during annealing. Despite this difference caused by annealing, HPT processing led to a similar evolution of the microstructure by increasing the strain for the samples with and without annealing. The saturation values of the crystallite size, dislocation density and twin fault probability were about 20 nm, 3 × 1016 m-2 and 3%, respectively, while the maximum achievable hardness was ~6000 MPa. The initial <100> and <110> textures for the as-built and the annealed samples were changed to <111> due to HPT processing.

Pressure-driven superconductivity in layered isostructural germanium phosphides

The discovery of superconductivity and its modulation are long-standing cutting-edge research topics in condensed matter physics. As a powerful tool, the high-pressure technique can be used to achieve novel superconductors and tune their physical properties. One typical example is binary germanium phosphides with different stoichiometries, which exhibit abundant physical properties with layered lattice structures similar to blue phosphorus. The detailed phase diagrams of the Ge–P systems are important for understanding the influence of stoichiometry on pressure-driven superconductivity, but it remains unexplored. Here, we measured and compared the detailed superconducting phase diagrams of the Ge–P systems of layered isostructural germanium phosphides GeP3 and GeP5 under pressure. Even though these two binary phosphides exhibit obviously different atomic occupations in the crystal structure due to their distinct stoichiometric ratios, the onset superconducting transition temperatures Tc of GeP3 and GeP5 both show dramatic enhancements from ∼2.5 K at 12.0 GPa to the maximum values of ∼9.0 K at 28.0 GPa, which are higher than those of other binary metal phosphides. Such pressure-enhanced superconductivity therein is accompanied by significant pressure-induced phonon mode softening, which is confirmed via in situ high-pressure Raman measurements. Our observations deepen the physical understanding of pressure-driven superconductivity in phosphorous-rich layered compounds and pave the way for potential applications in microsuperconducting devices.

New insight into π–π interactions: realization of full color emission from blue to red under hydrostatic pressure without exogenous intramolecular charge transfer

A new strategy to disclose the relationship between π–π stacking without exogenous ICT and photophysical properties was propounded through the construction of smart piezochromic materials with a discrete π–π dimer and high-pressure technique.

The preparation, characterization, and antibacterial activity evaluation of nanoliposomes incorporated with terebinth extract

Nanoliposomes are drug release systems that increase bioavailability and are used for encapsulation of therapeutic active ingredients. Terebinth, which is a medicinal plant that grows in many parts of Türkiye, has antibacterial, antioxidant, and anti-inflammatory activity. The antibacterial activity of nanoliposomes incorporated with ethanol extract of terebinth leaves (TLE) was investigated to determine the effects of formulation. The nanoliposome formulation was prepared in two steps which were high pressure and high intensity homogenization techniques. Characterization parameters (zeta potential, particle size and distribution, polydispersity index, and encapsulation efficiency) were determined. After third cycle of microfluidization, the zeta potential charge of nanoliposome dispersion was measured -66.6 mV and 91.13 nm in size. The PDI was 0.231. Also, the nanoliposome encapsulation efficiency was calculated as 91.90%. The TLE was encapsulated with nanoliposomes and their antibacterial activity was examined by disk diffusion and minimum inhibition concentration tests against Escherichia coli ATTC 25922 and Staphylococcus aureus ATTC 25923. Nanoliposome encapsulated TLE (NLTLE) has antibacterial activity against S. aureus ATTC 25923. While NLTLE has less active substance, it displays the same antibacterial activity as TLE.

Optical Pump-Terahertz Probe Diagnostics of the Carrier Dynamics in Diamonds.

Diamond is a promising material for terahertz applications. In this work, we use a non-invasive optical pump-terahertz probe method to experimentally study the photoinduced carrier dynamics in doped diamond monocrystals and a new diamond-silicon composite. The chemical vapor deposited diamond substrate with embedded silicon microparticles showed two photoinduced carrier lifetimes (short lifetime on the order of 4 ps and long lifetime on the order of 200 ps). The short lifetime is several times less than in boron-doped diamonds and nitrogen-doped diamonds which were grown using a high temperature-high pressure technique. The observed phenomenon is explained by the transport of photoexcited carriers across the silicon-diamond interface, resulting in dual relaxation dynamics. The observed phenomenon could be used for ultrafast flexible terahertz modulation.

Pressure modified upconversion luminescence of Yb3+ and Er3+-doped Bi3TeBO9 ceramics

Yb3+ and Er3+-doped Bi3TeBO9 ceramics exhibit efficient upconversion luminescence in the visible spectral range upon laser diode excitation at 975 nm. Bi3TeBO9:Yb3+/Er3+ powder was prepared by means of the modified Pechini method. A series of Bi3TeBO9:Yb3+/Er3+ ceramic samples was fabricated using the high-pressure low-temperature technique, by sintering Bi3TeBO9:Yb3+/Er3+ powder under different pressures (2, 4, 6 or 8 GPa). The structure and morphology of the above-mentioned samples were analyzed using XRD, SEM and EDX measurements. The phonon energy of Bi3TeBO9 matrix associated with the vibrations of TeO6 and BO3 molecular groups was revealed using μ-Raman spectroscopy. The low phonon energy of Bi3TeBO9 matrix allows the effective energy transfer between Yb3+ and Er3+ ions as well as the 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions from the excited to ground states of Er3+ ions, resulting in efficient upconversion emission at 523, 540 and 653 nm, respectively. The decay times determined for all analyzed emissions were longer for Bi3TeBO9:Yb3+/Er3+ ceramics than for the powder sample. The highest values of decay times were detected for the ceramics obtained under a pressure of 8 GPa and were equal to 174, 172 and 175 μs for the emissions at 523, 540 and 653 nm, respectively. The obtained results suggest that Bi3TeBO9:Yb3+/Er3+ ceramics can be proposed as efficient spectral converters in the new type solar cells enhancing the efficiency of the photovoltaic effect.

Application of Microfluidization in the Food Industry

Microfluidization is a high-pressure homogenization technique that applies a number of forces such as high impact force, shear force, sudden pressure drop, and cavitation force in order to subdivide the particles into smaller sizes. The technology of micro fluidization is based on a double-acting intensifier pump and an interaction chamber. The intensifier pump creates the pressure required to force the raw material into the interaction chamber. It is widely used in the food industry for a variety of applications, including the formation of micro- and nano-sized emulsions, the encapsulation of easily degradable bioactive compounds, and the enhancement of functional properties of proteins, polysaccharides, and dietary fibers. It was first used to emulsify milk products before being used in other food products such as fruit juices, proteins, gums, cereals, and cereal by-products.

Sr Substitution Effect on Ca Site for 32522-Type Ca&lt;sub&gt;3&lt;/sub&gt;Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5-&lt;i&gt;y&lt;/i&gt;&lt;/sub&gt;Fe&lt;sub&gt;2&lt;/sub&gt;As&lt;sub&gt;2&lt;/sub&gt; Superconductor

We have prepared multi-layered iron-based 32522-type (Ca, Sr)3Al2O5-yFe2As2 superconductor with the double perovskite-based “325” structure using high-pressure technique. In this paper, we have investigated iso-valent cation Sr substitution effect on Ca site for 32522-type (Ca, Sr)3Al2O5-yFe2As2. By the Sr atom substitution for Ca site, superconducting transition temperature (Tc) was slightly increasing, the critical current density (Jc) was kept under magnetic field near Tc and the irreversibility field (Hirr) value was also increasing.

Synthesis, characterization, and application of novel aryldiazenyl disperse dyes on polyester fabrics

Azo dyes are widely used for dyeing polyester fabrics but require optimization of properties like color strength and fastness. Fourteen novel disperse azo dyes were synthesized from 2,3-naphthalenediol and aniline derivatives to examine their potential for polyester dyeing. The dyes were prepared via diazotization and coupling reactions and characterized using FT-IR, UV–Vis, 1H NMR, 13C NMR, and elemental analysis. Furthermore, several techniques were employed to study the azo-hydrazone tautomerism, including UV–Vis spectroscopy, NMR spectroscopy, and computational methods. DFT computations revealed hydrazone tautomers were more stable than azo tautomers. The prepared azo dyes were applied on polyester fabrics at 2% depth using a high temperature pressure technique in water utilizing DYEWELL-002 as a dispersing agent. The color shading of dyed polyester samples ranged from peach amber to apple of my eye, depending on the coupler moieties. The fastness properties, assessed using a grey scale of dyed polyester fabrics, indicated very good to excellent grades for most dyes. Additionally, measurements of color strength (K/S), dye exhaustion (%E), as well as colorimetric colors CILAB of dyed polyester fabrics values, were measured and discussed in terms of the effect of substituents. The findings provide new insights into structure-performance relationships to design optimized disperse dyes for polyester coloration. Overall, the synthesized aryldiazenyl dyes are promising candidates for dyeing polyester fabrics across a spectrum of shades with good fastness properties.

Development and characterization of inhaled nintedanib-loaded PLGA nanoparticles using scalable high-pressure homogenization technique

Presently, non-invasive targeted drug delivery to the lungs represents a routinely investigated approach to treat challenging disorders such as pulmonary fibrosis. Nintedanib (Nint) is an FDA-approved drug for treating idiopathic pulmonary fibrosis and certain interstitial lung diseases. Nint acts as a multiple tyrosine kinase inhibitor, demonstrating anti-neoplastic effects in non-small cell lung cancer. However, limitations of oral administration of Nint include low bioavailability and high dose requirement for adequate therapeutic efficacy, resulting in adverse effects like abdominal pain, sickness, diarrhea, and vomiting. In this project, Nint was reformulated into PLGA nanoparticles (Nint-NPs) for direct-lung administration to address these deficiencies and enhance its potential. In this project, Nint-NPs were designed utilizing a high-pressure homogenization (HPH) approach with excellent reproducibility and scale-up feasibility. Selected Nint-NP formulation revealed 43.3 ± 4.0 % of entrapment efficiency and 179.8 ± 3.1 nm of size. In-vitro release study showed an initial burst release of 36.0 ± 7.5 % within 30 min, followed by sustained release up to 71.0 ± 4.3 % by 96 h. Further, Nint-NPs were found to be stable after 1-month of storage in refrigerated and accelerated conditions. Interestingly, the results of lung deposition demonstrated ideal MMAD values less than 5 μm in all three nebulizer types tested (jet, breath-actuated jet, and vibrating mesh nebulizers), indicating Nint-NPs are appropriate for deep-lung delivery. In-vitro cellular uptake analysis exhibited higher internalization of NPs in alveolar epithelial cells and lung fibroblasts while avoiding macrophage uptake. Toxicity studies on normal lung cells indicated Nint-NPs were safe for use. Taken together, inhalation therapy of Nint-NPs offers a favorable alternative to oral capsules for treating respiratory diseases.

Significant strength enhancement of high-entropy alloy via phase engineering and lattice distortion

The extraordinary mechanical properties of high-entropy alloys (HEAs) hold great promise for their applications under extreme conditions (high pressure, high temperature, etc.). However, investigations on the mechanical properties of HEAs under extreme conditions (especially at high pressures) are extremely scarce, preventing their future applications. In this study, significant strength enhancement of Cantor (CoCrFeMnNi) HEA is achieved via phase engineering by using high-pressure techniques. The pressure-induced fcc-hcp phase transition of Cantor HEA leads to a strength increase of 65 % across the phase transition. Consequently, the hcp-Cantor HEA behaves as strongly as typical superhard ceramic B4C and surpasses corundum at moderate pressures. Moreover, the hcp-Cantor HEA quenched to ambient pressure is 47 % harder than the pristine fcc phase. In addition, by substituting the Mn atom with the Pd atom to introduce a severe lattice distortion in Cantor HEA, the CoCrFePdNi HEA turns out to be almost twice harder than Cantor HEAs at ambient pressure. The excellent mechanical properties of HEAs promise their potential applications at high pressures. These results also demonstrate that phase engineering and the introduction of severe lattice distortion represent two promising methods of developing high-strength HEAs in the future.

Thermal and Modern, Non-Thermal Method Induction as a Factor of Modification of Inulin Hydrogel Properties.

The aim of the study was to compare the properties of inulin hydrogels obtained with different methods, e.g., the traditional-thermal method and new, non-thermal methods, used in food production, like ultrasonic, high-pressure homogenization (HPH), and high hydrostatic pressures (HHPs). It was found that each of the compared induction methods allowed for obtaining inulin hydrogels. However, the use of non-thermal induction methods allows for obtaining a gel structure faster than in the case of thermal induction. In addition, hydrogels obtained with new, non-thermal methods differ from gels obtained with thermal treatment. They were characterized by higher stability (from 1.7 percent point-of-stability parameters for HHP 150 MPa to 18.8 for HPH II cycles) and in most cases, by improved microrheological properties-lower solid-liquid balance toward the solid phase, increased elasticity and viscosity indexes, and lowering the flow index. The gels obtained with the new, non-thermal method were also characterized by a more delicate structure, including lower firmness (the differences between thermal and non-thermal inductions were from 0.73 N for HHP at 500 MPa to 2.39 N for HHP at 150 MPa) and spreadability (the differences between thermal and non-thermal inductions were from 7.60 Ns for HHP at 500 MPa to 15.08 Ns for HHP at 150 MPa). The color of ultrasound-induced inulin gels, regarding the HPH and HHP technique, was darker (the differences in the L* parameter between thermal and non-thermal inductions were from 1.92 for HHP at 500 MPa to 4.37 for 10 min ultrasounds) and with a lower a* color parameter (the differences in the a* parameter between thermal and non-thermal inductions were from 0.16 for HHP at 500 MPa to 0.39 for HPH II cycles) and b* color parameter (the differences in the b* parameter between thermal and non-thermal inductions were from 1.69 for 5 min ultrasounds to 2.68 for HPH II cycles). It was also found that among the compared induction methods, the high-pressure technique has the greatest potential for modifying the properties of the created inulin hydrogels. Thanks to its application, depending on the amount of applied pressure, it was possible to obtain gels with very different characteristics, both delicate (i.e., soft and spreadable), using HHP at 150 MPa, and hard, using HHP at 500 MPa, the closest in characteristics to gels induced with the thermal method. This may allow the properties of hydrogels to be matched to the characteristics of the food matrix being created.

Coexistent, Competing Tunnelling, and Hopping Charge Transport in Compressed Metal Nanocluster Crystals.

Understanding charge transport among metal particles with sizes of approximately 1 nm poses a great challenge due to the ultrasmall nanosize, yet it holds great significance in the development of innovative materials as substitutes for traditional semiconductors, which are insulative and unstable in less than ∼10 nm thickness. Herein, atomically precise gold nanoclusters with well-defined compositions and structures were investigated to establish a mathematical relation between conductivity and interparticle distance. This was accomplished using high-pressure in situ resistance characterizations, synchrotron X-ray diffraction (XRD), and the Murnaghan equation of state. Based on this precise correlation, it was predicted that the conductivity of Au25(SNap)18 (SNap: 1-naphthalenethiolate) solid is comparable to that of bulk silver when the interparticle distance is reduced to approximately 3.6 Å. Furthermore, the study revealed the coexisting, competing tunneling, and incoherent hopping charge transport mechanisms, which differed from those previously reported. The introduction of conjugation-structured ligands, tuning of the structures of metal nanoclusters, and use of high-pressure techniques contributed to enhanced conductivity, and thus, the charge carrier types were determined using Hall measurements. Overall, this study provides valuable insight into the charge transport in gold nanocluster solids and represents an important advancement in metal nanocluster semiconductor research.

Spatially Separated Active Sites Enable Selective CO Oxidation Reaction on Oxide Catalyst.

The search for efficient non-noble-metal catalysts able to perform selective oxidation reactions is of great importance, with relevance to many catalytic processes. However, this is often hampered because the origin of the selectivity remains controversial, particularly for reactions catalyzed by oxides. Here, combining high-pressure surface imaging techniques and theoretical calculations, we identify that spatially separated active sites for O2 activation and H2 adsorption on an ultrathin Mn3O4 surface enable selective oxidation of CO over H2. Theoretical calculations reveal that Mn-O pairs for H2 dissociation are separated from Mn-Mn pairs for the formation of adsorbed O2* so that H2 has to surmount much higher barriers for both H2 dissociation and H diffusion while CO can directly react with O2* following the Eley-Rideal process. Our study sheds light on the atomic-level understanding of the surface structure-dependent selective oxidation reaction on oxide catalysts.

High Gas Pressure and High-Temperature Synthesis (HP-HTS) Technique and Its Impact on Iron-Based Superconductors

The high-pressure growth technique generally plays an important role in the improvement of sample quality and the enhancement of various physical and magnetic properties of materials. The high gas pressure technique provides a large sample space (10–15 cm) to grow various kinds of materials. In this paper, we introduce the high gas pressure and high-temperature synthesis (HP-HTS) technique that is present at our institute and is applied to the growth process of different kinds of superconducting materials, particularly iron-based superconductors. More details and the working principle of this HP-HTS technique are discussed. We have also demonstrated the current results based on iron-based superconductors by using this unique HP-HTS technique. These results demonstrate the enhancement of the superconducting properties with improved sample quality compared to the conventional synthesis process at ambient pressure.