Search Results (41)

Diamond, a crucial carbon phase in the deep Earth, forms under ultrahigh-pressure (UHP, P > 4 GPa) conditions and serves as an important indicator mineral for the UHP environment. Based on their host rocks, diamonds are classified into mantle-derived diamonds, UHP metamorphic diamonds, impact diamonds, etc. While carbon constitutes the primary component of diamonds, nitrogen represents one of the most significant impurity elements. The study of the occurrence mode of nitrogen and the C-N isotope composition is essential for exploring the formation mechanism of diamond. Nitrogen primarily exists in diamonds as either isolated atoms (N) or aggregated forms (N2 or N4), with the dominant mode being controlled by temperature and residence time in the mantle. As temperature and residence time increase, isolated nitrogen progressively transforms into aggregated forms. As a result, mantle-derived diamonds typically contain nitrogen predominantly as N2 or N4, whereas metamorphic diamonds and impact diamonds mainly retain isolated N. Global C-N isotopic composition of over 4400 diamonds reveals a wide compositional range, with δ¹³C ranging from −38.5‰ to +5.0‰, and δ¹⁵N from −39.4‰ to +15.0‰. These values significantly exceed the typical mantle δ¹³C and δ¹⁵N values of −5‰ ± 3‰, indicating that the diamond formation may be influenced by subducted crustal materials. During crystallization, diamonds can encapsulate surrounding materials as inclusions, which are divided into three types based on their formation sequence relative to the host diamond: preformed, syngenetic, and epigenetic. Syngenetic inclusions are particularly valuable for constraining crystallization conditions and the genesis of diamonds. Furthermore, geochronology studies of radioactive isotope-bearing syngenetic inclusions are helpful to clarify the age of diamond formation. Usually, mantle-derived diamonds exhibit Archean age, whereas metamorphic diamonds are associated with subduction, showing younger ages that could be associated with metamorphic events. Therefore, the formation conditions and genesis of diamonds can be clearly constrained through integrating investigations of inclusions, nitrogen occurrence modes, and C-N isotopic compositions. The characteristics of occurrence modes, inclusions, and C-N isotope compositions of different types of diamonds are systematically reviewed in this paper, providing critical insights into their genesis and contributing to a deeper understanding of diamond formation processes in Earth’s interior. Full article

This study investigated the synergistic effects of ultra-high pressure (UHP) and egg white protein (EWP) on the gel properties of sodium-reduced shrimp surimi. A Box–Behnken design targeting UHP pressure (200–400 MPa), duration (10–20 min), and EWP/myofibrillar protein (MP) ratio (1:9–5:5) was implemented to optimize gel strength, water holding capacity (WHC), and whiteness. Optimal conditions (290 MPa/15 min/EWP:MP = 3:5) yielded the following validated improvements, versus conventional processing: 282.27 g·mm gel strength, 14.90% WHC enhancement, and 16.63% reduced cooking loss. Texture profile analysis demonstrated superior elasticity in composite gels. Magnetic resonance imaging and scanning electron microscopy revealed a denser microstructure with enhanced water-binding capacity, corroborated by the rheological evidence of strengthened viscoelasticity. UHP promotes the partial expansion of MP, exposing hydrophobic groups and sulfhydryl groups, thereby enhancing intermolecular interactions. It also promotes the expansion of EWP, enabling the formation of disulfide bonds between molecules and facilitating the formation of network structures. These findings propose a scalable strategy for developing clean-label salt-reduced aquatic surimi products. Full article

This study explores the antioxidant activity and antioxidant mechanism of phenolic compounds (including free (FP), esterified (EP), and bound phenolic (BP)) from Dendrobium fimbriatum Hook (DFH) stems, before and after ultra-high pressure (UHP) treatment. A total of 374 compounds were identified, with 149 showing significant differences in DFH phenolic extracts before and after UHP treatment. UHP treatment significantly increased the total phenolic content (TPC) and total flavonoid content (TFC) and enhanced antioxidant activity in vitro. Particularly, the UEP-DFH, IC₅₀ values in ABTS and DPPH were reduced by 49.6% and 64.1%, respectively. In H₂O₂-treated HepG2 cells, the extracts demonstrated significant cytoprotective effects, including increased cell viability, ROS reduction, and enhanced GSH levels by 17.8% (UFP-DFH) and 12.5% (UEP-DFH). The activities of GS, GCL, GR, GSH-Px, SOD, CAT, NQO1, and HO-1 were also elevated in UHP-treated extracts. DAPI staining indicated that the extracts promoted nuclear Nrf2 expression, particularly UFP-DFH and UEP-DFH. Molecular docking indicated that vanillic acid could competitively bind to the Keap1-Kelch domain, facilitating activation of the antioxidant pathway. Overall, UHP treatment enhanced both extraction efficiency and antioxidant activity, making it a promising method for improving the bioactivity of DFH in the food and functional food industries. Full article

The aim of this study was to compare the effects of glycation and ultra-high pressure (UHP) treatment on the structure and IgG immunobinding activity of Salangidae icefish PV. The Circular Dichroism (CD) and Fluorescence Spectroscopy (FS) findings indicated that the glycation significantly affected both the secondary and tertiary structures of PV. However, the impact of UHP processing on the structure of PV was found to be less significant compared to the glycation. Western Blot analysis also revealed that the glycation markedly reduced the antigen specificity of PV. Conversely, UHP treatments at 300 MPa and 400 MPa slightly decreased the antigen specificity, whereas lower or excessively high pressures did not have a substantial impact. This research contributes valuable insights into strategies for reducing the allergenic potential of Salangid icefish. Full article

The application of ultra-high-pressure (UHP) water jets for rock slotting in the bottom hole has been recognized as a highly effective approach to enhance rock-breaking efficiency. However, the current downhole intensifiers are confronted with various limitations, including the short duration of UHP pulse water jet output and challenges in attaining both controllable and adjustable output frequencies, consequently leading to compromised slotting efficiency. In this study, a novel intensifier controlled by an electromagnetic valve was designed, and a visual test platform was constructed to investigate the output pressure characteristics and their influencing factors. The output characteristics of the intensifier consist of a mixed pulse jet composed of high-pressure and low-pressure jets, resulting in a square wave-like output waveform with an adjustable frequency. The output pressure characteristics of the intensifier are primarily influenced by the input pressure and the switching time of the electromagnetic valve, assuming that the structural parameters are constant. Increasing the input pressure raises the peak pressure, thereby enhancing the slotting capability of the jet stream. Aligning the switching time of the electromagnetic valve with the rotation period of the drill bit improves the slotting efficiency. In the lab tests, the output pressure of the intensifier was successfully increased to 118.2 MPa, with a sustained duration of a high-pressure jet segment for 2.1 s. These research findings offer a new method for enhancing drilling efficiency in deep hard rock formations. Full article

The Dabie–Sulu Orogen hosts the largest area of ultrahigh-pressure (UHP) rocks in the world. There is still significant divergence regarding the exhumation process and mechanism of UHP rocks in the Dabie Orogen, which mainly resulted from the erosion of large volumes of rocks in the Orogen during the post-collisional stage. Based on detailed field investigations, this study discovered the occurrence of E–W-trending sinistral shear belts that developed on the northeastern Dabie Orogen. These shear belts formed under greenschist facies conditions and are characterized by steep foliation and gentle mineral lineation. E–W-trending shear belts developed in HP rocks with metamorphic ages ranging from 227 to 219 Ma and were cut by the older phase of ductile shear belts of the Tan-Lu Fault Zone, indicating that they were formed around 219–197 Ma. Based on a comprehensive analysis of existing data, it can be concluded that E–W-trending shear belts were formed during the exhumation process of HP–UHP rocks. When HP rocks returned to the shallow crust and the lower UHP rocks continued to move, stress concentration occurred in the HP rocks and further resulted in the formation of E–W-trending shear belts. The development of E–W-trending shear belts indicates that HP–UHP rocks had essentially returned to the shallow crust by the Late Triassic, marking the near completion of the exhumation process. Full article

Gastrodiae Rhizoma (GE), a popular food in China, is stored and consumed after steaming, which can lead to the degradation of active substances and a decrease in its quality. Therefore, this study explored the potential application of ultra-high-pressure (UHP)-assisted hot air drying in improving the quality of GE. The results indicated that UHP pre-treatment could preserve the original cross-sectional color of GE and increase the degrees of freedom of water in GE samples. Compared with traditional steaming pre-treatment (18 h), UHP pre-treatment at 500 MPa significantly shorted the time (10 h) required for the GE samples to reach drying equilibrium. Meanwhile, the UHP-assisted hot air drying method (60 °C) could reduce the activity of β-D-glucosidase and avoid the degradation of active substances. Finally, UHP pre-treatment improved the neuroprotective activity in vivo. Overall, UHP-assisted hot air drying could improve the quality of GE samples. This study provides a simple method for improving the quality of GE samples and offers a reference for subsequent research on the influence of UHP on GE. Full article

Coconut chips are a popular leisure food, but the residual crumbly feeling after chewing affects the eating experience. To address this problem, we investigated the mechanism of degradation of insoluble dietary fiber (IDF) from coconut chips by ultra-high pressure (UHP). The optimal conditions for UHP treatment were 100 MPa and 40 min. After UHP treatment, the hardness decreased by 60%, and the content of soluble dietary fiber (SDF) increased by 55%. So far, the meaning of SDF has not been defined. The microstructure of IDF was damaged and the surface was rough. There was no obvious change in the chemical structure. The position of the characteristic diffraction peaks was basically unchanged, but the crystallinity dropped by almost three times. The thermal stability decreased, and the composition of the monosaccharides changed. Together, UHP treatment can improve the problem of the residual crumbly feeling after chewing coconut chips and improve the quality of the product. Full article

The impact of the roasting degree on ultra-high-pressure cold brew (UHP) coffee remains unclear, although it has been found that UHP technology accelerates the extraction of cold brew (CB) coffee. Therefore, this study investigated the effects of three different degrees of roasting (light, medium, and dark) on the physicochemical characteristics, volatile and non-volatile components, and sensory evaluation of UHP coffee. Orthogonal partial least-squares-discriminant analysis (OPLS-DA) and principal component analysis (PCA) were used to assess the effects of different roasting degrees. The results showed that most physicochemical characteristics, including total dissolved solids (TDSs), extraction yield (EY), total titratable acidity (TTA), total sugars (TSs), and total phenolic content (TPC), of UHP coffee were similar to those of conventional CB coffee regardless of the degree of roasting. However, the majority of physicochemical characteristics, non-volatile components, including the antioxidant capacity (measured based on DPPH and ABTS) and melanoidin, caffeine, trigonelline, and CGA contents increased significantly with an increase in roasting degree. The sensory evaluation revealed that as the roasting degree rose, the nutty flavor, astringency, bitterness, body, and aftertaste intensities increased, while floral, fruity, and sourness attributes decreased. The HS-SPME-GC/MS analysis showed that most volatile components increased from light to dark roasting. Moreover, 15 representative differential compounds, including hazelnut pyrazine, linalool, butane-2,3-dione, and 3-methylbutanal, were identified by calculating the odor-active values (OAVs), indicating that these contributed significantly to the odor. The PCA showed that the distance between the three roasting degree samples in UHP coffee was smaller than that in CB coffee. Overall, the effect of roasting degrees on UHP coffee was less than that on CB coffee, which was consistent with the results of physicochemical characteristics, volatile components, and sensory evaluation. Full article

The East Kunlun Orogenic Belt (EKOB), northwestern China, recording long-term and multiple accretionary and collisional events of the Tethyan Ocean, belongs to a high-pressure to ultra-high-pressure (HP-UHP) metamorphic belt that underwent complex metamorphic overprinting in the early Paleozoic. In this contribution, we carry out an integrated study, including field investigations, petrographic observations, whole-rock analyses, zircon U-Pb dating, and P-T condition modeling using THERMOCALC in the NCKFMASHTO system for the eclogites, especially for the newly discovered UHP eclogite in the eastern part of EKOB. The eclogites exhibit geochemistry ranging from normal mid-ocean ridge basalt (N-MORB) to enriched mid-ocean ridge basalt (E-MORB). Zircons from the eclogites yield metamorphic ages of 416–413 Ma, indicating the eclogite facies metamorphism. Coesite inclusions in garnet and omphacite and quartz exsolution in omphacite and pseudosection calculation suggest that some eclogites experienced UHP eclogite facies metamorphism. The eclogites from the eastern part of EKOB record peak conditions of 29–33 kbar/705–760 °C, first retrograde conditions of 10 kbar at 9.5–12.5 kbar/610–680 °C, and second retrograde conditions at ~6 kbar/<600 °C. New evidence of the early Paleozoic UHP metamorphism in East Kunlun is identified in our study. Thus, we suggest that these eclogites were produced by the oceanic crust subducting to the depth of 100 km and exhumation. The presence of East Gouli and Gazhima eclogites in this study and other eclogites (430–414 Ma) in East Kunlun record the final closure of the local branch ocean of the Proto-Tethys and the evolution from subduction to collision. Full article

This study aimed to investigate the efficacy of supercritical CO₂ (SC-CO₂) extraction in enhancing the extraction rate, purity, and antioxidant activity of Indocalamus latifolius (Keng) McClure (Poaceae) leaf terpenoids (ILLTs). Crude extracts obtained from leaves were subjected to qualitative and quantitative analyses, revealing neophytadiene, phytol, β-sitosterol, β-amyrone, squalene, and friedelin as the primary terpenoid constituents, identified through gas chromatography–mass spectrometry (GC-MS). Compared with steam distillation extraction (SD), simultaneous distillation extraction (SDE), ultra-high pressure-assisted n-hexane extraction (UHPE-Hex), ultra-high pressure-assisted ethanol extraction (UHPE-EtOH), ultrasound-assisted n-hexane extraction (UE-Hex), and ultrasound-assisted ethanol extraction (UE-EtOH), SC-CO₂ exhibited a superior ILLT extraction rate, purity, and antioxidant activity. Scanning electron microscopy (SEM) observations of the residues further revealed more severe damage to both the residues and their cell walls after SC-CO₂ extraction. Under optimal parameters (4.5 h, 26 MPa, 39 °C, and 20% ethyl alcohol), the ILLT extraction rate with SC-CO₂ reached 1.44 ± 0.12 mg/g, which was significantly higher than the rates obtained by the other six methods. The subsequent separation and purification using WelFlash C18-l, BUCHI-C18, and Sephadex LH-20 led to an increase in the purity of the six terpenoid components from 12.91% to 93.34%. Furthermore, the ILLTs demonstrated cytotoxicity against HepG2 cells with an IC₅₀ value of 148.93 ± 9.93 μg/mL. Additionally, with increasing concentrations, the ILLTs exhibited an enhanced cellular antioxidant status, as evidenced by reductions in both reactive oxygen species (ROS) and malondialdehyde (MDA) levels. Full article

The Dabie–Sulu Orogen hosts the largest province of ultrahigh-pressure (UHP) rocks in the world. The post-collisional extension eroded and transported volumes of rocks from the Dabie Orogen to adjacent basins, causing a lack of information about the orogen and thus obstructing our understanding of the exhumation process of UHP rocks. In addition, the mechanisms that triggered the post-collisional extension and affected the petrological-tectonic units of the orogen are still unclear. This study is focused on the time in which the present tectonic framework in the Dabie Orogen took place, selecting Early Cretaceous plutons in the eastern part of the orogen and carrying out detailed zircon LA-ICP-MS U-Pb dating and crystallization depth calculation. The zircon dating results show that the emplacement time of the Meichuan and Luannitan plutons and the Penghe superunit of the Zhubuyuan pluton are all ~128 Ma, while the Huangbai superunit of the Zhubuyuan pluton and the Longmianzhai pluton formed at ~125 Ma. The emplacement time and later anatexis of the Baimajian pluton occurred at ~128 and ~122 Ma, respectively. The results of the Al-in-hornblende geobarometer show that plutons of ~128 Ma have a similar crystallization depth, while plutons of ~125 Ma range from 7.6 to 9.5 km. The Baimajian pluton has a greater crystallization depth. Combined with the existing achievements, a conclusion can be drawn that the present tectonic framework of the Dabie Orogen began to form from ~128 Ma. Full article

The ultra-deep genesis of ophiolitic peridotite has reshaped our perception of the genesis of the oceanic mantle. Although ultra-high pressure (UHP) mineral assemblages have been unearthed in dozens of ophiolites in different orogenic belts around the world, the vast majority of them have been limited to podiform chromitites formed in suprasubduction zone (SSZ) settings, leaving uncertainty about whether such UHP minerals are intrinsic to the oceanic mantle or influenced by a specific mantle rock type. Here, we report on the occurrence of diamonds recovered from the harzburgites within the Skenderbeu massif, Mirdita ophiolite. The whole-rock, mineralogical major and trace element compositions, and redox states of the harzburgites align with modern abyssal harzburgites. Trace element modeling of clinopyroxene indicates that harzburgites have endured varying degrees of garnet-facies melting (~2%–5%) before progressing to spinel-facies melting (~10%–12%). Mineralogical characteristics further support that the Skenderbeu harzburgites underwent late-period MORB-like melt metasomatism in a forearc spreading center. An unusual mineral assemblage of diamonds has been separated from the studied harzburgites. The first occurrence of ophiolite-hosted diamonds discovered in the forearc harzburgites, together with previous similar discoveries in the SSZ ophiolitic chromitites, suggest that the ophiolite-hosted diamonds are not specific to certain mantle rocks. Full article

In this study, ultra–high–pressure sterilization (UHPS) of Xinli No. 7 juice (XL7) was explored and optimized. A challenge to implement UHPS in juice as a full alternative to thermal treatment could be represented by the adoption of a pressure level of up to 500 MPa for 20 min at one cycle followed by the packaging in aseptic conditions. It was found that UHPS and HS treatments could effectively kill the microorganisms in XL7 juice but HS treatment would inevitably lose the nutritional quality in the juice, while UHPS treatment could better maintain the glyconic acid content, functional components, and antioxidant activity and reduce Browning degree and improve the stability of XL7 juice. The deterioration rate of UHPS and HS–treated XL7 juice increased with the increased storage temperature. The predicted shelf life of UHPS and HS–treated XL7 juice was 68 and 41 days at 4 °C, respectively. Collectively, UHPS treatment combined with low–temperature storage might be an effective way to prolong the shelf life of XL7 juice. Full article

Phase-change energy-storage paraffin regulates the thermal management of buildings, and the material can regulate room temperature as it absorbs and discharges heat. As a porous adsorbent material, bamboo has high permeability. The aim of this study was to increase the amount of paraffin inside bamboo and the latent heat of the phase change. It was performed using vacuum pressurization (VP) and ultra-high-pressure (UHP) impregnation treatments. The effect of UHP impregnation and properties of bamboo were studied. The weight gain, paraffin loss and dimensional changes were measured and compared. The morphology of UHP-impregnated bamboo were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The main conclusions are as follows: After UHP impregnation, the highest weight gain was 42%. The loss of paraffin was low, and a high weight percentage gain was maintained. The crystallinity of cellulose decreased to 24% at 100 MPa. The latent heat of the bamboo slices was up to 25.66 J/g at 50 MPa, and the phase change temperature was close to room temperature. At 150 MPa, the hydroxyl content was reduced, and the hydrophilicity decreased. In addition, the content of substances such as hemicellulose in the amorphous zone was reduced under UHP, no new characteristic peaks appeared, and no chemical modifications occurred. The vascular bundles were compressed and dense, and the pores and cell gaps decreased. The thin-walled cells were deformed, and the original cell structure was completely destroyed. The surface of the cells was wrapped or covered with paraffin, confirming that the paraffin could impregnate the bamboo cells under UHP. Therefore, bamboo impregnated with paraffin can regulate temperature and save energy in buildings. It is resistant to biological attacks, and UHP improves the impregnation efficiency. Full article