Effects of Gel Properties and Water Migration during Ultra-High Pressure Coupled Heat Treatment on Bighead Carp Surimi

In order to elucidate the mechanism of the changes in gel properties of bighead carp surimi during ultra-high pressure coupled heat treatment, this paper investigated the changes in gel properties, protein structure and water migration of bighead carp surimi during ultra-high pressure coupled heat treatments (300 MPa/5 min, 40 ℃/30 min, 90 ℃/20 min), and carried out clustered heat maps and Pearson correlation analyses. The results showed that ultra-high pressure coupled heat treatment significantly improved the gel properties of bighead carp surimi (P<0.05). The gel strength, texture and whiteness of bighead carp surimi gel showed an increasing trend with ultra-high pressure, ultra-high pressure combined with one-stage heat treatment, and ultra-high pressure combined with two-stage heat treatment. The gel strength and whiteness of the ultra-high pressure coupled heat treatment (300PSH) surimi gels increased by 477.75% and 43.38%, respectively, compared to the atmospheric pressure treated samples (0.1P). The proportion of β-folded structure in the proteins of bighead carp surimi gels increased significantly (P<0.05) during the different treatments, and myosin heavy chain cross-linked aggregation. Meanwhile, the content of active sulfhydryl groups and surface hydrophobicity of surimi gel were significantly reduced (P<0.05), and the proteins formed a denser and more ordered network structure through disulfide bonds and hydrophobic interaction, leading to the migration of immobile water to bound water, which ultimately resulted in significant improvements in the gel strength, texture properties, whiteness and water holding capacity of surimi gel. This study can provide theoretical basis for application of ultra-high pressure coupled heat treatment technology and development of bighead surimi products

Provenance Discrimination of Siliciclastic Sediments in the Western Sea of Japan over the Past 30 kyr: Evidence from Major, Trace Elements, and Pb Isotopes

AbstractThe Sea of Japan (JS), a unique marginal sea without any large river influxes in the western Pacific, provides ample information about the evolution of sea level, East Asian monsoons (EAM), sea ice activity, and ocean currents in geological time. However, insufficient investigation in the western JS limits our knowledge of East Asian climate change. This study utilizes major and trace elements and Pb isotopes of fine siliciclastic components (&lt;63 μm) of core LV53-18-2 and determines the provenances using statistical methods and discrimination diagrams. The results show that the terrigenous debris of LV53-18-2 was mainly composed of aeolian dust from northeast China, ice-rafted debris (IRD), and volcanic materials from the Far East coast over the last 30 kyr. During the late last glacial period, sea ice activity carried weakly weathered IRD to the study area. Meanwhile, the strengthened East Asian winter monsoon (EAWM) brought dust from northeast China to the study site owing to the cold climate and enlarged sandy land. During the late last deglacial period to early Holocene (15-8 kyr), ascending boreal summer insolation drove the intense melting of sea ice. This led to the deposition of large amounts of weakly weathered IRD and remarkably influenced the chemical composition of the core. After 8 kyr, the global sea level rose to -15 m below the modern sea level and opened the Tatar Strait. Consequently, freshwater supplied by the Amur River entered the JS and gave birth to the Liman Cold Current (LCC), which transported more mafic materials from the Kema terrane upstream

Millennial-scale variations in sedimentary oxygenation in the western subtropical North Pacific and its links to North Atlantic climate

The deep-ocean carbon cycle, especially carbon sequestration and outgassing, is one of the mechanisms to explain variations in atmospheric CO2 concentrations on millennial and orbital timescales. However, the potential role of subtropical North Pacific subsurface waters in modulating atmospheric CO2 levels on millennial timescales is poorly constrained. An increase in the respired CO2 concentration in the glacial deep-ocean due to biological pump generally corresponds to deoxygenation in the ocean interior. This link thus offers a chance to study oceanic ventilation and coeval export productivity based on redox-controlled sedimentary geochemical parameters. Here, we investigate a suite of geochemical proxies in a sediment core from the Okinawa Trough to understand sedimentary oxygenation variations in the subtropical North Pacific over the last 50 000 years (50 ka). Our results suggest that enhanced mid-depth western subtropical North Pacific (WSTNP) sedimentary oxygenation occurred during cold intervals and after 8.5 ka, while oxygenation decreased during the Bölling-Alleröd (B/A) and Preboreal. The enhanced oxygenation during cold spells is linked to the North Pacific IntermediateWater (NPIW), while interglacial increase after 8.5 ka is linked to an intensification of the Kuroshio Current due to strengthened northeast tradewinds over the tropics. The enhanced formation of the NPIW during Heinrich Stadial 1 (HS1) was likely driven by the perturbation of sea ice formation and sea surface salinity oscillations in the high-latitude North Pacific. The diminished sedimentary oxygenation during the B/A due to a decreased NPIW formation and enhanced export production, indicates an expansion of the oxygen minimum zone in the North Pacific and enhanced CO2 sequestration at mid-depth waters, along with the termination of atmospheric CO2 concentration increase. We attribute the millennial-scale changes to an intensified NPIW and enhanced abyss flushing during deglacial cold and warm intervals, respectively, closely related to variations in North Atlantic Deep Water formation

Insight-HXMT observations of Swift J0243.6+6124 during its 2017-2018 outburst

The recently discovered neutron star transient Swift J0243.6+6124 has been monitored by {\it the Hard X-ray Modulation Telescope} ({\it Insight-\rm HXMT). Based on the obtained data, we investigate the broadband spectrum of the source throughout the outburst. We estimate the broadband flux of the source and search for possible cyclotron line in the broadband spectrum. No evidence of line-like features is, however, found up to $\rm 150~keV$. In the absence of any cyclotron line in its energy spectrum, we estimate the magnetic field of the source based on the observed spin evolution of the neutron star by applying two accretion torque models. In both cases, we get consistent results with $B\rm \sim 10^{13}~G$, $D\rm \sim 6~kpc$ and peak luminosity of $\rm >10^{39}~erg~s^{-1}$ which makes the source the first Galactic ultraluminous X-ray source hosting a neutron star.Comment: publishe

Overview to the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite

As China's first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band (1-250 keV) slat-collimator-based X-ray astronomy satellite with the capability of all-sky monitoring in 0.2-3 MeV. It was designed to perform pointing, scanning and gamma-ray burst (GRB) observations and, based on the Direct Demodulation Method (DDM), the image of the scanned sky region can be reconstructed. Here we give an overview of the mission and its progresses, including payload, core sciences, ground calibration/facility, ground segment, data archive, software, in-orbit performance, calibration, background model, observations and some preliminary results.Comment: 29 pages, 40 figures, 6 tables, to appear in Sci. China-Phys. Mech. Astron. arXiv admin note: text overlap with arXiv:1910.0443

Insight into the Effect of Ice Addition on the Gel Properties of Nemipterus virgatus Surimi Gel Combined with Water Migration

The effect of the amount of ice added (20–60%) on the gel properties and water migration of Nemipterus virgatus surimi gel obtained with two-stage heat treatment was studied. The gel strength and water-holding capability (WHC) of the surimi gel with 30% ice added were significantly higher than those of other treatment groups (p &lt; 0.05). The addition of 30% ice was conducive to the increase of protein β-sheet proportion during heat treatment, exposing more reactive sulfhydryl groups. These promoted the combination of protein-protein through disulfide bonds and hydrophobic-hydrophobic interactions, forming an ordered three-dimensional gel network structure. Meanwhile, the increase in hydrogen bonds promoted the protein-water interaction. Low-field nuclear magnetic resonance analysis showed that more bound water was locked in the gel system, reducing the migration of immobile water to free water and finally showing better gel properties. When the amount of ice added was insufficient (20%), the gel structure lacked the support of immobile water, resulting in deterioration of gel strength. However, excessive addition of ice (&gt;30%) was not conducive to the combination of protein-protein and protein-water, forming a large and rough gel structure, resulting in the migration of immobile water to free water and ultimately exhibited weak gel properties

Sedimentary mercury and antimony revealed orbital-scale dynamics of the Kuroshio Current

As an integral part of the Earth's climate system, the Kuroshio Current (KC) plays a crucial role in shaping the regional oceanography and climate in the Northern Hemisphere. However, how the KC dynamics have varied over glacial-interglacial cycles is still under debate. The dynamic transfer and accumulation of submarine hydrothermal source materials by deep-reaching KC offer us a unique opportunity to examine the variations in dynamics of the KC. Here, we used novel proxies of sedimentary mercury (Hg) and antimony (Sb) in core MD01-2404 retrieved from the middle Okinawa Trough (OT) to reconstruct the evolution of the KC hydrodynamics over the last 92,000 years. We infer the enrichments of sedimentary Hg and Sb to signify hydrothermal input, which is delivered laterally to the study site by deep circulation in association with the KC, thus indicating the dynamics of KC. Overall, both the sedimentary Hg and Sb in core MD01-2404 indicate a persistent influence on the KC dynamics within the OT over the last glacial-interglacial cycles. Furthermore, our Hg and Sb proxies suggest a significantly weakened influence during the last deglaciation and last glacial period while a strengthened influence during the Holocene and late Marine Isotope Stage 5. Our studies imply that the orbital-scale dynamics of KC are controlled by tropical atmosphere-ocean interactions induced by sea surface temperature changes and regulated by the extratropical climate conditions