Decoupling of high-resolution surface pH and DO reveals temporal algal bloom dynamics on the East China Sea.

The stoichiometric ratio between seawater CO2 and dissolved oxygen (DO) during phytoplankton metabolism holds significant importance in evaluating ecological and biogeochemical processes. We collected high-resolution underway temperature, salinity, DO, and pH data in the East China Sea inner shelf in May 2017. Our results revealed high pH (8.36) and supersaturated DO (171 %) in the outer Changjiang Estuary, indicating the occurrence of an algal bloom event. They were significantly correlated with a regression slope of 0.0029, which roughly followed the Redfield ratio. In contrast, a much higher ratio (0.0088) manifested in a low-salinity patch on north of the Changjiang Estuary, featuring a pH of 8.40 and oxygen saturation of approximately 123 %. The substantially faster air-sea equilibrium rate of O2 than CO2 probably caused such decoupling, offering insight into the temporal evolutions of algal bloom. Theoretically, a steeper regression slope implies an earlier onset of algal bloom. An end-member mixing model was constructed to exclude the physical mixing influences on dissolved inorganic carbon (ΔDIC) and DO (ΔDO). Furthermore, we conducted simulations to explore the temporal variations of ΔDIC-ΔDO regression slope with time. Comparing slopes derived from simulation and mixing model suggested that the biological signal of the decoupled waters likely preceded our observations by 6-10 days. Satellite results captured high-Chl a waters southwest of the low-salinity patch a week before our observation, potentially transported northward by prevailing southwest wind. Given that oxygen and pH are frequently measured in aquatic environments, their combined assessment could be a valuable method for assessing temporal algal bloom dynamics.

Characterization and Discrimination of Marigold Oleoresin from Different Origins Based on UPLC-QTOF-MS Combined Molecular Networking and Multivariate Statistical Analysis.

Marigold oleoresin is an oil-soluble natural colorant mainly extracted from marigold flowers. Xinjiang of China, India, and Zambia of Africa are the three main production areas of marigold flowers. Therefore, this study utilized ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) technology, combined with Global Natural Products Social Molecular Networking (GNPS) and multivariate statistical analysis, for the qualitative and discriminant analysis of marigold oleoresin obtained from three different regions. Firstly, 83 compounds were identified in these marigold oleoresin samples. Furthermore, the results of a principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) indicated significant differences in the chemical compositions of the marigold oleoresin samples from different regions. Finally, 12, 23, and 38 differential metabolites were, respectively, identified by comparing the marigold oleoresin from Africa with Xinjiang, Africa with India, and Xinjiang with India. In summary, these results can be used to distinguish marigold oleoresin samples from different regions, laying a solid foundation for further quality control and providing a theoretical basis for assessing its safety and nutritional aspects.

Copper Nanoparticles Confined in a Silica Nanochannel Film for the Electrochemical Detection of Nitrate Ions in Water Samples.

The nitrate ion (NO3-) is a typical pollutant in environmental samples, posing a threat to the aquatic ecosystem and human health. Therefore, rapid and accurate detection of NO3- is crucial for both the aquatic sciences and government regulations. Here we report the fabrication of an amino-functionalized, vertically ordered mesoporous silica film (NH2-VMSF) confining localized copper nanoparticles (CuNPs) for the electrochemical detection of NO3-. NH2-VMSF-carrying amino groups possess an ordered perpendicular nanochannel structure and ultrasmall nanopores, enabling the confined growth of CuNPs through the electrodeposition method. The resulting CuNPs/NH2-VMSF-modified indium tin oxide (ITO) electrode (CuNPs/NH2-VMSF/ITO) combines the electrocatalytic reduction ability of CuNPs and the electrostatic attraction capacity of NH2-VMSF towards NO3-. Thus, it is a rapid and sensitive electrochemical method for the determination of NO3- with a wide linear detection range of 5.0-1000 µM and a low detection limit of 2.3 µM. Direct electrochemical detection of NO3- in water samples (tap water, lake water, seawater, and rainwater) with acceptable recoveries ranging from 97.8% to 109% was performed, demonstrating that the proposed CuNPs/NH2-VMSF/ITO sensor has excellent reproducibility, regeneration, and anti-interference abilities.

Dynamics of Bacterioplankton Communities during Wet and Dry Seasons in the Danjiangkou Reservoir in Hubei, China.

Water quality is directly linked to drinking water safety for millions of people receiving the water. The Danjiangkou Reservoir is the main water source for the Middle Route of the South-to-North Water Diversion Project (MR-SNWDP), located in the vicinity of Henan and Hubei provinces in China. Aquatic microorganisms are key indicators of biologically assessing and monitoring the water quality of the reservoir as they are sensitive to environmental and water quality changes. This study aimed to investigate the spatiotemporal variations in bacterioplankton communities during wet (April) and dry (October) seasons at eight monitoring points in Hanku reservoir and five monitoring points in Danku reservoir. Each time point had three replicates, labeled as wet season Hanku (WH), wet season Danku (WD), dry season Hanku (DH), and dry season Danku (DD) of Danjiangkou Reservoir in 2021. High-throughput sequencing (Illumina PE250) of the 16S rRNA gene was performed, and alpha (ACE and Shannon) and beta (PCoA and NDMS) diversity indices were analyzed. The results showed that the dry season (DH and DD) had more diverse bacterioplankton communities compared to the wet season (WH and WD). Proteobacteria, Actinobacteria, and Firmicutes were the most abundant phyla, and Acinetobacter, Exiguobacterium, and Planomicrobium were abundant in the wet season, while polynucleobacter was abundant in the dry season. The functional prediction of metabolic pathways revealed six major functions including carbohydrate metabolism, membrane transport, amino acid metabolism, signal transduction, and energy metabolism. Redundancy analysis showed that environmental parameters greatly affected bacterioplankton diversity during the dry season compared to the wet season. The findings suggest that seasonality has a significant impact on bacterioplankton communities, and the dry season has more diverse communities influenced by environmental parameters. Further, the relatively high abundance of certain bacteria such as Acinetobacter deteriorated the water quality during the wet season compared to the dry season. Our findings have significant implications for water resource management in China, and other countries facing similar challenges. However, further investigations are required to elucidate the role of environmental parameters in influencing bacterioplankton diversity in order to devise potential strategies for improving water quality management in the reservoir.

The Changjiang River plume shifts from carbon source to sink when net community production exceeds a threshold in early autumn.

Estuaries are crucial components of the global ocean carbon cycle due to their high productivity. However, our understanding of the carbon source-sink dynamics at the air-sea interface of estuaries is incomplete, largely due to the rapidly changing environmental conditions. To address this, we conducted a study in early autumn 2016 using high-resolution biogeochemical data collected through buoy observations in the Changjiang River plume (CRP). Using a mass balance approach, we examined the factors driving changes in the sea surface partial pressure of carbon dioxide (pCO2) and quantified the net community production (NCP) in the mixed layer. We also explored the relationship between NCP and the carbon source-sink dynamics at the air-sea interface. Our results revealed that biological activities (64.0 %) and seawater mixing (19.7 %, including lateral transport and vertical mixing) were the dominant factors controlling changes in sea surface pCO2 during the study period. Moreover, NCP in the mixed layer was affected by factors such as light availability and the presence of respired organic carbon associated with vertical mixing of seawater. Notably, we observed a strong correlation between NCP and the difference in pCO2 between air and sea (δpCO2), with a threshold NCP value of 308.4 mmol m-2 d-1 identified as an indicator of the transition from a CO2 source to a sink in the CRP. Hence, we suggest that the NCP in a specific ocean box has a threshold, beyond which the air-sea interface in estuaries will change from a carbon source to a carbon sink, and vice versa.

Constructing Effective Hole Transport Channels in Cross-Linked Hole Transport Layer by Stacking Discotic Molecules for High Performance Deep Blue QLEDs.

The inadequate hole injection limits the efficiency and lifetime of the blue quantum dot light-emitting diodes (QLEDs), which severely hampers their commercial applications. Here a new discotic molecule of 3,6,10,11-tetrakis(pentyloxy)triphenylene-2,7-diyl bis(2,2-dimethylpropanoate) (T5DP-2,7) is introduced, in which the hole transport channels with superior hole mobility (2.6 × 10-2 cm2 V-1 s-1 ) is formed by stacking. The composite hole transport material (HTM) is prepared by blending T5DP-2,7 with the cross-linked 4,4'- bis(3-vinyl-9H-carbazol-9-yl)-1,1'biphenyl (CBP-V) which shows the deep highest occupied molecular orbital energy level. The increased hole mobility of the target composite HTM from 10-4 to 10-3 cm2 V-1 s-1 as well as the stepwise energy levels facilitates the hole transport, which would be beneficial for more balanced carrier injection. This composite hole transport layer (HTL) has improved the deep-blue-emission performances of Commission International de I'Eclairage of (0.14, 0.04), luminance of 44080 cd m-2 , and external quantum efficiency of 18.59%. Furthermore, when L0 is 100 cd m-2 , the device lifetime T50 is extended from 139 to 502 h. The state-of-the-art performance shows the successful promotion of the high-efficiency for deep blue QLEDs, and indicates that the optimizing HTL by discotic molecule stacking can serve as an excellent alternative for the development of HTL in the future.

Microplastics contamination in the surface water of the Yangtze River from upstream to estuary based on different sampling methods.

In this study, we investigated microplastic contamination of the Yangtze River from the upper reaches to the estuary using different sampling methods to understand extensive information on microplastic pollution. The microplastic samples were collected at 10 sites using two conventional methods: trawling and filtering water. The results showed that the average abundance of microplastics ranged from 1.62±0.61 × 105 to 4.25±3.87 × 106 items/km2 (trawling samples) and 800.0±300.0 to 3088.9±330.6 items/m3 (filtering water samples). The average abundance (by trawling) in the Three Gorges Reservoir (2.80±1.86 × 106 items/km2) was one order of magnitude higher than that of other sections, which affirmed the barrier effect of dams on microplastic distribution. The barrier effect was more obvious on larger size particles by comparing the results of two methods. The abundances near the left, right banks, and in the midstream showed no significant difference by both two methods, illustrating that sampling at each bank along the Yangtze River was also representative in one section. Characteristics analysis demonstrated that fragments (47.9%) dominated in trawling samples and fiber (63.4%) dominated in filtering water samples. Microplastics of small sizes (<1 mm) and transparent were dominant in samples collected by the two methods. Polyethylene (PP) and polypropylene (PE) were the dominant polymer types in the detected microplastics. In this study, we provided detailed information on microplastic pollution of the Yangtze River from the upstream to the estuary, which is useful for microplastic management and control in this area.

Dataset for atmospheric transport of nutrients during a harmful algal bloom.

The data presented in this article are related to the research article entitled "Atmospheric transport of nutrient matter during a harmful algal bloom"[1]. These data provide the concentration of nutrients (nitrate, ammonium and FeⅡ) in the atmosphere and their deposited flux in the East China Sea prior to the harmful algal bloom on May 3-8, 2006. They can be helpful for analyzing the source of nutrients causing the harmful algal blooms.

Elevated carbon flux in deep waters of the South China Sea.

We measured particulate organic carbon (POC) fluxes from the euphotic zone into the twilight zone and deep waters (>1000 m) that occurred between the shelf and the basin in the South China Sea (SCS) and at the SouthEast Asia Time Series Station (SEATS) using floating sediment trap arrays. Additionally, selected sinking particles were imaged by scanning electron microscope (SEM) to reveal particle morphology and composition. Results showed large variations in POC fluxes with elevated values (32-104 mg-C m-2 d-1) below the euphotic zone and a trend towards lower values in the deep SCS. Vertical POC fluxes measured in deep waters between the shelf and the SCS basin were much higher than those estimated by Martin's attenuation equation. These elevated POC fluxes in deep waters were attributed to lateral particle transport as opposed to enhanced settling out of the euphotic zone. SEM images of sinking particles at 150 m show abundant marine biogenic detritus, while those in deep waters contained a higher proportion of lithogenic material. A great deal of the spatial variability in POC fluxes across the twilight zone and deep waters of the SCS cannot be represented by current biogeochemical models.

Algae explosive growth mechanism enabling weather-like forecast of harmful algal blooms.

As a global problem in coastal environments, harmful algal blooms (HABs) have seriously affected the health of coastal ecosystems and regional economies. Here we report an aerosol-trigger mechanism for the occurrence of HABs based on long-term field data and laboratory experiments. The occurrence times of HABs and aerosol events had a significant correlation from 2005 to 2013 in the East China Sea, indicating that aerosol transport was probably an alternative trigger of HABs. HABs mostly occur in the transition time between winter and summer, during which northwest monsoon transport substantial aerosol (rich in phosphate, iron and other trace metals) to coastal waters, as revealed by chemical measurements, transmission electron microscope and electron microprober results. Such nutrients can stimulate algal growth in our incubation experiments, suggesting that such aerosol transport can be important nutrient sources for the East China Sea where phytoplankton growth is relatively phosphate limited. Air-borne nutrients are available for algal growth by rapid downward air flow, which additional results a clear weather condition, and thus adequate light intensity for algal growth. At last, the transition from northwest monsoon to warm southwest monsoon establishes favorable seawater temperature for algal blooms. Such weather-related aerosol-trigger mechanism suggests possibly forecast of HABs.

Elevated particulate organic carbon export flux induced by internal waves in the oligotrophic northern South China Sea.

To understand the biogeochemical response to internal waves in the deep basin of the northern South China Sea (NSCS), particulate organic carbon (POC) export fluxes were quantified for the first time during the passage of large internal waves using drifting sediment traps attached with hydrographic sensors. Results revealed large variations in temperature, nitrate and chlorophyll a (Chl a) concentrations during and after internal waves, suggesting that cold nutrient-replete waters may be brought to the euphotic zone in the dissipation zone during and after the passage of internal wave packets, resulted in phytoplankton flourished. Most importantly, POC export fluxes (110.9 ± 10.7 mg C m-2 d-1) were significantly enhanced after internal waves compared to non-internal wave area (32.6-73.0 mg C m-2 d-1) in the NSCS. Such elevated POC fluxes may be induced by downward flourished biogenic particles, particle aggregation or converged particles from mixed layer triggered by internal waves.

The bioaccessibility of iodine in the biofortified vegetables throughout cooking and simulated digestion.

Biofortification of crops with exogenous iodine is a novel strategy to control iodine deficiency disorders (IDD). The bioaccessibility of iodine (BI) in the biofortified vegetables in the course of soaking, cooking and digestion, were examined. Under hydroponics, the concentration of iodine in leafstalks of the celery and pakchoi increased with increasing exogenous iodine concentration, 54.8-63.9% of the iodine absorbed by pakchoi was stored in the soluble cellular substance. Being soaked in water within 8 h, the iodine loss rate of the biofortified celery was 3.5-10.4% only. More than 80% of the iodine in the biofortified celery was retained after cooking under high temperature. The highest BI of the biofortified vegetables after digestion in simulated gastric and intestinal juice amounted to 74.08 and 68.28%, respectively. Factors influencing BI included pH, digestion duration, and liquid-to-solid ratio. The high BI of the biofortified vegetables provided a sound reference for the promotion of iodine biofortification as a tool to eliminate the IDD.

Synergistic effect of Au and Rh on SrTiO3 in significantly promoting visible-light-driven syngas production from CO2 and H2O.

A novel photocatalyst constructed by Rh, Au, and SrTiO3 was developed to realize syngas photosynthesis from low-cost CO2 and H2O feedstock under visible-light irradiation. The synergistic effect of Rh and Au on SrTiO3 contributed to a 22- and 153-fold photoactivity magnification for syngas yield in contrast to Au@SrTiO3 and Rh@SrTiO3 samples, respectively.

Designing Au Surface-Modified Nanoporous-Single-Crystalline SrTiO3 to Optimize Diffusion of Surface Plasmon Resonance-Induce Photoelectron toward Enhanced Visible-Light Photoactivity.

Nanoporous single-crystalline SrTiO3 is fabricated at a low temperature of 60 °C via a novel approach of sol-gel alkali-dissolution-exothermal reaction. The plasmon-active metal Au is loaded on the nanoporous single-crystalline SrTiO3 material to construct a new kind of plasmonic photocatalyst. Due to the single-crystalline nature and the space confinement effect of pores for Au growing, not only the promoted diffusion efficiency of surface plasmon resonance (SPR)-induce photoelectron is achieved, but also the diffusion region are well optimized via changing the loading amount of Au. Therefore, an optimal sample with 4.8 wt % Au loading exhibits a more than 40-fold photoactivity enhancement under visible-light irradiation compared to the common nanosized SrTiO3 (a commercially available sample) loaded with 5.3 wt % Au which was prepared under the same condition. Furthermore, combining the special nanostructure of Au surface-modified nanoporous-single-crystalline SrTiO3 with photocatalytic properties, estimation of the diffusion mean free path of SPR-induce photoelectron can be achieved. This study proposes an alternative approach to enhance the photoactivity of plasmonic photocatalyst via fine designing the semiconductor substrate.

Structural and Functional Insights into the Unwinding Mechanism of Bacteroides sp Pif1.

Pif1 is a conserved SF1B DNA helicase involved in maintaining genome stability through unwinding double-stranded DNAs (dsDNAs), DNA/RNA hybrids, and G quadruplex (G4) structures. Here, we report the structures of the helicase domain of human Pif1 and Bacteroides sp Pif1 (BaPif1) in complex with ADP-AlF4(-) and two different single-stranded DNAs (ssDNAs). The wedge region equivalent to the ß hairpin in other SF1B DNA helicases folds into an extended loop followed by an α helix. The Pif1 signature motif of BaPif1 interacts with the wedge region and a short helix in order to stabilize these ssDNA binding elements, therefore indirectly exerting its functional role. Domain 2B of BaPif1 undergoes a large conformational change upon concomitant binding of ATP and ssDNA, which is critical for Pif1's activities. BaPif1 cocrystallized with a tailed dsDNA and ADP-AlF4(-), resulting in a bound ssDNA bent nearly 90° at the ssDNA/dsDNA junction. The conformational snapshots of BaPif1 provide insights into the mechanism governing the helicase activity of Pif1.

Effect of band structure on the hot-electron transfer over Au photosensitized brookite TiO2.

Au photosensitization can endow TiO2 visible-light-driven photocatalytic properties. Herein, via facet-optimized brookite TiO2 with tunable electronic band structures as the substrate, we found that intense visible light excitation of Au will result in the accumulation of hot-electrons, which will negatively shift the EF of Au and lower the Schottky barrier, thus ensuring their consecutive injections into the CB of TiO2; in this case, hot-electrons with more reduction potential will lead to superior photocatalytic activity.

Crystallization and preliminary X-ray crystallographic analysis of a putative nonribosomal peptide synthase AmbB from Pseudomonas aeruginosa.

AmbB is a putative nonribosomal peptide synthase from Pseudomonas aeruginosa, which is involved in the production of IQS, a potent cell-cell communication signal molecule that integrates the quorum-sensing mechanism and stress response. It consists of 1249 amino acids and contains an AMP-binding domain, a phosphopantetheine-binding (PB) domain and a condensation (C) domain. In this report, a truncated form of AmbB that contains the PB domain and the condensation domain was overexpressed with an N-terminal GST tag in Escherichia coli and purified as a monomer using affinity and size-exclusion chromatography. The recombinant AmbBc (comprising residues 727-1249 of full-length AmbB) was crystallized using the hanging-drop vapour-diffusion method and a full data set was collected to 2.45 Šresolution using a synchrotron-radiation source. The crystals belonged to space group P6122 or P6522, with unit-cell parameters a = b = 87.81, c = 286.8 Å, α = 90, ß = 90, γ = 120°, and contained one molecule per asymmetric unit.

An innovative approach for iodine supplementation using iodine-rich phytogenic food.

Iodine, as one of the essential trace elements for human body, is very important for the proper function of thyroid gland. In some regions, people are still suffering from iodine deficiency disorder (IDD). How to provide an effective and cost-efficient iodine supplementation has been a public health issue for many countries. In this review, a novel iodine supplementation approach is introduced. Different from traditional iodine salt supplement, this approach innovatively uses cultivated iodine-rich phytogenic food as the supplement. These foods are cultivated using alga-based organic iodine fertilizer. The feasibility, mechanics of iodine absorption of plants from soil and the bioavailability of iodine-rich phytogenic food are further discussed.

[Study on the method of measurement of respiratory mechanical parameters].

Respiratory mechanical parameters are the key indexes in evaluating the respiratory function of an anaesthetized patient during operation. The measurement of respiratory parameters plays an important role in clinic, and can dynamically monitor the working state of a respirator, direct the use of a respirator and monitor the respiratory function of a patient in intensive care unit(ICU). This paper introduces a new method that will break the traditional limitations, can measure eleven respiratory parameters and demonstrate the results by digital and diagrams.

[A design of the circuit of a monitoring system for respiratory mechanical parameters].

The circuit of a monitoring system for respiratory mechanical parameters is designed based on the detection of respiratory flow and pressure. Breaking through the restrictions of traditional methods that can only monitor respiratory rate, this design is able to monitor more than 10 respiratory parameters simultaneously and thus provides a good technical support for improving the properties of homemade monitors.