The Physicochemical Attributes, Volatile Compounds, and Antioxidant Activities of Five Plum Cultivars in Sichuan.

Plum (Prunus salicina Lindl.) is an important stone fruit crop in Sichuan that is increasingly in demand by consumers owing to its flavor and outstanding nutraceutical properties. The physicochemical characteristics, antioxidant capacity, and volatile profiles of five traditional and new plum cultivars in Sichuan were determined using high-performance liquid chromatography and gas chromatography time-of-flight mass spectrometry. The results showed that all plums exhibited an appropriate quality profile for fresh consumption; the new cultivar 'ZH' exhibited the highest soluble solids content, sugar-acid ratio, total phenolic content, total flavonoid content, and antioxidant capacity. High sugar-low acid properties were observed in five plum cultivars. Sucrose was the main sugar, while quinic acid and malic acid were the main organic acids. The plums were rich in volatile compounds and had specific volatile characteristics. A total of 737 volatiles were identified in the plum fruit, and orthogonal partial least-squares discriminant analysis was employed to screen 40 differential volatiles as markers for cultivar distinction. These findings offer comprehensive information on the physicochemical characteristics, antioxidant capacity, and volatile profiles of plums.

Dynamic link between Neo-Tethyan subduction and atmospheric CO2 changes: insights from seismic tomography reconstruction.

Volcanic arc degassing contributes significantly to atmospheric CO2 levels and therefore has a pivotal impact on paleoclimate changes. The Neo-Tethyan decarbonation subduction is thought to have played a major role in Cenozoic climate changes, although there are still no quantifiable restrictions. Here we build past subduction scenarios using an improved seismic tomography reconstruction method and calculate the subducted slab flux in the India-Eurasia collision region. We find remarkable synchronicity between calculated slab flux and paleoclimate parameters in the Cenozoic, indicating a causal link between these processes. The closure of the Neo-Tethyan intra-oceanic subduction resulted in more carbon-rich sediments subducting along the Eurasia margin, as well as continental arc volcanoes, which further triggered global warming up to the Early Eocene Climatic Optimum. The abrupt termination of the Neo-Tethyan subduction due to the India-Eurasia collision could be the primary tectonic cause of the âˆ¼50-40 Ma CO2 drop. The gradual decrease in atmospheric CO2 concentration after 40 Ma may be attributed to enhance continental weathering due to the growth of the Tibetan Plateau. Our results contribute to a better understanding of the dynamic implications of Neo-Tethyan Ocean evolution and may provide new constraints for future carbon cycle models.

Wedge tectonics in South China: constraints from new seismic data.

Collisional orogens form when tectonic forces amalgamte fragments of Earth's continental lithosphere. The sutures between individual fragments, or terranes, are potential sites of weakness that facilitate subsequent continental breakup. Therefore, the lithospheric architecture of collisional orogens provides key information for evaluating the long-term evolution of the continental interior: for example, the South China Block (SCB), where the tectonic history is severely obscured by extensive surface deformation, magmatism, and metamorphism. Using new passive-source seismic models, we show a contrasting seismic architecture across the SCB, with three prominent crustal dipping structures across the Jiangnan Orogen. Combined with constraints from multi-disciplinary regional geophysical datasets, these pronounced dipping patterns are interpreted as relict wedge-like lithospheric deformation zones initiated in the fossil collisions that assembled the Yangtze Block and the SCB. The overall trend of these tectonic wedges implies successive crustal growth along paleo-continental margins and is indicative of northward subduction and docking of accretional terranes. In contrast, no such dipping structures are preserved in the Cathaysia Block, indicating a weak and reorganized lithosphere. The variations in the deformation responses across the SCB reflect the long-term modifications of the lithosphere caused by prolonged collision and extension events throughout the tectonic history of the SCB. Our results demonstrate the critical roles that suture zones played in the successive growth and evolution of the continental lithosphere.

Unraveling the contribution of pre-salting duration to microbial succession and changes of volatile and non-volatile organic compounds in Suancai (a Chinese traditional fermented vegetable) during fermentation.

Pre-salting is an important pre-treatment during production of Suancai as it provides flavor precursor and microbial community for subsequent fermentation. To investigate the effect of pre-salting duration on fermentation of Suancai, the physicochemical properties, microbial composition, non-volatile and volatile organic compounds profiles of Suancai pre-salted for 1 month (1 M) and 7 months (7 M) were analyzed during fermentation for 30 days. Results showed that 7 M led to higher salt content, faster depletion of reducing sugars, and more titratable acidity. Additionally, more lactic acid and acetic acid, and less umami amino acid (Glu) and GABA were observed in 7 M. Longer pre-salting duration (7 M) promoted formation of mild-flavor volatile compounds, and significantly reduced isothiocyanates with pungent off-flavor. Moreover, 7 M promoted abundance of genera Chromohalobacter, Vibrio and Pichia, while reducing abundance of Lactobacillus, Debaryomyces and Kazachstania throughout fermentation. These results implicated that longer pre-salting duration facilitated more acidic, milder flavor and less pungent off-odor in Suancai. This study provided a perspective for pre-salting as a control point for improving quality of fermented vegetable.

Seismological evidence for the earliest global subduction network at 2 Ga ago.

The earliest evidence for subduction, which could have been localized, does not signify when plate tectonics became a global phenomenon. To test the antiquity of global subduction, we investigated Paleoproterozoic time, for which seismic evidence is available from multiple continents. We used a new high-density seismic array in North China to image the crustal structure that exhibits a dipping Moho bearing close resemblance to that of the modern Himalaya. The relict collisional zone is Paleoproterozoic in age and implies subduction operating at least as early as ~2 billion years (Ga) ago. Seismic evidence of subduction from six continents at this age is interpreted as the oldest evidence of global plate tectonics. The sutures identified can be linked in a plate network that resulted in the assembly of Nuna, likely Earth's first supercontinent. Global subduction by ~2 Ga ago can explain why secular planetary cooling was not appreciable until Proterozoic time.

Author Correction: Evidence for a serpentinized plate interface favouring continental subduction.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Evidence for a serpentinized plate interface favouring continental subduction.

The dynamics of continental subduction is largely controlled by the rheological properties of rocks involved along the subduction channel. Serpentinites have low viscosity at geological strain rates. However, compelling geophysical evidence of a serpentinite channel during continental subduction is still lacking. Here we show that anomalously low shear-wave seismic velocities are found beneath the Western Alps, along the plate interface between the European slab and the overlying Adriatic mantle. We propose that these seismic velocities indicate the stacked remnants of a weak fossilised serpentinite channel, which includes both slivers of abyssal serpentinite formed at the ocean floor and mantle-wedge serpentinite formed by fluid release from the subducting slab. Our results suggest that this serpentinized plate interface may have favoured the subduction of continental crust into the upper mantle and the formation/exhumation of ultra-high pressure metamorphic rocks, providing new constraints to develop the conceptual and quantitative understanding of continental-subduction dynamics.

Simultaneous Determination of ß-Cypermethrin and Its Metabolite 3-Phenoxybenzoic Acid in Microbial Degradation Systems by HPLC-UV.

The wide use of pesticides in agriculture is necessary to guarantee adequate food production worldwide. However, pesticide residues have caused global concern because of their potential health risk to consumers. In this study, we could identify ß-cypermethrin (ß-CY) and its degradation product 3-phenoxybenzoic acid (3-PBA) by liquid chromatograph-mass spectrometry. Few studies on the simultaneous determination of ß-CY and its metabolites have been carried out so far; hence, we established a high-performance liquid chromatography method to determine the concentrations of both ß-CY and 3-PBA simultaneously in microbial degradation systems. In this study, a novel ß-CY degrading strain, Bacillus licheniformis B-1, was isolated from a tea garden soil, utilizing ß-CY as a growth substrate. Good linear relationships between ß-CY and 3-PBA were observed and the concentrations of reference solutions were between 0.50 and 60.00 µg/mL. Satisfactory stability and intra- and interday precision were obtained. The limits of detection were 0.06 and 0.13 µg/mL for ß-CY and 3-PBA, respectively, and the corresponding limits of quantification were 0.21 and 0.34 µg/mL, respectively. Spiking recoveries for ß-CY varied from 98.38 to 105.80%, with relative standard deviations (RSDs) varying from 1.49 to 3.93%. Spiking recoveries for 3-PBA varied from 99.59 to 101.20%, with RSDs varying from 0.58 to 3.64%. The proposed method has advantages of simplicity, rapidity, high accuracy, good separation and reproducibility; thus, it is ideally suitable for simultaneous determination of ß-CY and 3-PBA in microbial degradation systems.

Characterization of a novel ß-cypermethrin-degrading Aspergillus niger YAT strain and the biochemical degradation pathway of ß-cypermethrin.

Aspergillus niger YAT strain was obtained from Chinese brick tea (Collection number: CGMCC 10,568) and identified on the basis of morphological characteristics and internal transcribed spacer (ITS) sequence. The strain could degrade 54.83 % of ß-cypermethrin (ß-CY; 50 mg L(-1)) in 7 days and 100 % of 3-phenoxybenzoic acid (3-PBA; 100 mg L(-1)) in 22 h. The half-lives of ß-CY and 3-PBA range from 3.573 to 11.748 days and from 5.635 to 12.160 h, respectively. The degradation of ß-CY and 3-PBA was further described using first-order kinetic models. The pathway and mechanism of ß-CY degraded by YAT were investigated by analyzing the degraded metabolites through high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). Relevant enzymatic activities and substrate utilization were also investigated. ß-CY degradation products were analyzed. Results indicated that YAT strain transformed ß-CY into 3-PBA. 3-PBA was then gradually transformed into permethric acid, protocatechuic acid, 3-hydroxy-5-phenoxy benzoic acid, gallic acid, and phenol gradually. The YAT strain can also effectively degrade these metabolites. The results indicated that YAT strain has potential applications in bioremediation of pyrethroid insecticide (PI)-contaminated environments and fermented food.

A pretreatment method for HPLC analysis of cypermethrin in microbial degradation systems.

In this paper, a pretreatment method for high-performance liquid chromatography (HPLC) determination of cypermethrin (CY) in microbial degradation systems was systemically studied, primarily to solve the problem of inaccurate determination of CY concentration caused by its uneven distribution in the systems. A suitable pretreatment method was established, including sampling, extraction and dehydration of CY. Partial sampling could be taken for bacterial and yeast systems in which CY was uniformly dispersed by an emulsifying agent, while total sampling was only suitable for mold systems with or without an emulsifying agent. CY could be fully extracted from the samples in which microbial cells were disrupted by ultrasonic treatment with acetonitrile under ultrasonic condition. The extract could be effectively dehydrated and purified by passing it through an anhydrous Na(2)SO(4) column followed by an elution with acetonitrile. The determination of CY in the pretreated sample by HPLC showed a high precision [relative standard deviation (RSD) = 1.14%, n = 5] and a good stability over a period of five days (RSD = 1.57%, n = 5). The recoveries of CY in microbial degradation systems at three different spiked levels ranged from 95.68 to 108.09% (RSD = 0.50-5.87%, n = 5).

Lithospheric layering in the North American craton.

How cratons-extremely stable continental areas of the Earth's crust-formed and remained largely unchanged for more than 2,500 million years is much debated. Recent studies of seismic-wave receiver function data have detected a structural boundary under continental cratons at depths too shallow to be consistent with the lithosphere-asthenosphere boundary, as inferred from seismic tomography and other geophysical studies. Here we show that changes in the direction of azimuthal anisotropy with depth reveal the presence of two distinct lithospheric layers throughout the stable part of the North American continent. The top layer is thick ( approximately 150 km) under the Archaean core and tapers out on the surrounding Palaeozoic borders. Its thickness variations follow those of a highly depleted layer inferred from thermo-barometric analysis of xenoliths. The lithosphere-asthenosphere boundary is relatively flat (ranging from 180 to 240 km in depth), in agreement with the presence of a thermal conductive root that subsequently formed around the depleted chemical layer. Our findings tie together seismological, geochemical and geodynamical studies of the cratonic lithosphere in North America. They also suggest that the horizon detected in receiver function studies probably corresponds to the sharp mid-lithospheric boundary rather than to the more gradual lithosphere-asthenosphere boundary.