Spatial patterns of zooplankton abundance,biovolume,and size structure in response to environmental variables:a case study in the Yellow Sea and East China Sea

The Yellow Sea(YS)and East China Sea(ECS)are highly dynamic marginal seas of the northwestern Pacific Ocean.To gain an in-depth understanding of zooplankton community structure,zooplankton abundance,biovolume,and size structure in summer 2017 in the YS and ECS were assessed using ZooScan imaging analysis.Zooplankton abundance and biovolume ranged 2.94–1187.14 inds./m^(3)and 3.13–3438.51 mm^(3)/m^(3),respectively.Based on the biovolume data of the categorized size classes of 26 identified taxonomic groups,the zooplankton community was classified into five groups,and each group was coupled with distinctive oceanographic features.Under the influence of the Yellow Sea Cold Water Mass,the Yellow Sea offshore group featured the lowest bottom temperature(10.84±3.42℃)and the most abundant Calanoids(mainly in the 2–3 mm size class).In the Yellow Sea inshore group,Hydrozoans showed the largest biovolume and dominated in the 3–4-mm and>5-mm size classes.The East China Sea offshore group,which was affected by the Kuroshio Branch Current,featured high temperature and salinity,and the lowest bottom dissolved oxygen(2.58±0.5 mg/L).The lowest values of zooplankton abundance and biovolume in the East China Sea offshore group might be attributed to the bottom dissolved oxygen contents.The East China Sea inshore group,which was mainly influenced by the Zhejiang-Fujian Coastal Current and Changjiang Diluted Water,was characterized by high chlorophyll a and the largest biovolume of carnivorous Siphonophores(280.82±303.37 mm^(3)/m^(3)).The Changjiang River estuary offshore group showed the most abundant Cyclopoids,which might be associated with the less turbid water mass in this region.Seawater temperature was considered the most important factor in shaping the size compositions of Calanoids in different groups.

Literature overview of basic characteristics and flotation laws of flocs

Flocculation flotation is the most efficient method for recovering fine-grained minerals,and its essence lies in flotation and recovery of flocs.Fundamental physical characteristics of flocs are mainly determined by their apparent particle size and structure(density and morphology).Substantial researches have been conducted regarding the effect of floc characteristics on particle settling and water treatment.However,the influence of floc characteristics on flotation has not been widely studied.Based on the floc formation and flocculation flotation,this study reviews the fundamental physical characteristics of flocs from the perspectives of floc particle size and structure,summarizing the interaction between floc particle size and structure.Moreover,it thoroughly discusses the effect of floc particle size and structure on floc floatability,further revealing the influence of floc characteristics on bubble collision and adhesion and elucidating the mechanisms of interaction between flocs and bubbles.Thus,it is observed that floc particle size is not the only factor influencing flocculation flotation.Within the appropriate apparent particle size range,flocs with a compact structure exhibit higher efficiency in bubble collision and adhesion during flotation,thereby resulting in enhanced flotation performance.This study aims to provide a reference for flocculation flotation,targeting the development of more efficient and refined flocculation flotation processes in the future.

Temporal change of plankton size structure preserved by Lugol's solution:a FlowCAM study

Plankton size structure is crucial for understanding marine ecosystem dynamics and the associated biogeochemical processes.A fixation step by acid Lugol’s solution has been commonly employed to preserve plankton samples in the field.However,the acid Lugol’s solution can bias the estimation of size structure and the preserved plankton size structure can vary with time.Here,we explore the impact of sample storage time on the size-structure of the plankton community preserved by Lugol’s solution.Two short-term experiments and one long-term experiment were conducted to explore the change of plankton community size structure with the storage time:covering from a week to a month,and to nearly seven months based on particle-size data obtained by continuous Flow Cytometer and Microscope(FlowCAM)measurements.We found a linear change of plankton size with the storage time in short-term periods(less than 3 months)with a decrease of the slope but an increase of the intercept for the normalized biomass size spectrum(NBS S).However,there were opposite trends for NBSS with increasing slope but decreasing intercept after3 months.The potential causes of the distinct patterns of the NBSS parameters are addressed in terms of the interplay between particle aggregation and fragmentation.We found large changes in plankton biovolume and abundance among different size classes,which may indicate a distinct effect of acid Lugol’s solution on various plankton size classes.The mechanism driving temporal change in the size-structure of the Lugolfixed plankton community was further discussed in terms of particle aggregation and fragmentation.Finally,we emphasize that the effect of storage time should be taken into account when interpreting or comparing data of plankton community acquired from samples with various storage durations.

Inverse Calculation of Wave-Absorbing Structure Dimensions Based on Extended ANFIS Model

A new wave energy dissipation structure is proposed, aiming to optimize the dimensions of the structure and make the reflection of the structure maintain a low level within the scope of the known frequency band. An optimal extended ANFIS model combined with the wave reflection coefficient analysis for the estimation of the structure dimensions is established. In the premise of lower wave reflection coefficient, the specific sizes of the structure are obtained inversely, and the contribution of each related parameter on the structural reflection performance is analyzed. The main influencing factors are determined. It is found that the optimal dimensions of the proposed structure exist, which make the wave absorbing performance of the structure reach a perfect status under a wide wave frequency band.

A comparison between benthic gillnet and bottom trawl for assessing fish assemblages in a shallow eutrophic lake near the Changjiang River estuary

Two fishing methods including gillnetting and trawling to estimate attributes of fish assemblage were compared in Dianshan Lake from August 2009 to July 2010. Species composition dif fered significantly between the gears, with four significant contributors in gillnet catches and one in trawl catches. Trawling collected more proportions of benthic species by number and biomass than gillnetting. Size distribution was significantly influenced by fishing technique; gillnetting captured relatively less small-sized fishes and trawling captured less large-sized individuals. Trawling produced species richness closer to the one expected than gillnetting. On the whole, trawl catch was a quadratic polynomial function of gillnet catch and a significantly negative correlation was found between them, both of which varied as dif ferent polynomial functions of temperature. However, trawl and gillnet catches were significantly correlated only in one of five month groups. It is concluded that single-gear-based surveys can be misleading in assessments of attributes of fish assemblages, bottom trawling is a more ef fective gear for assessing fish diversity than benthic gillnetting, and using gillnet catches as an indicator of fish density depends on fishing season in the lake.

Longitudinal patterns of spring-intermonsoon phytoplankton biomass,species compositions and size structure in the Bay of Bengal

Vertical distributions of phytoplankton biomass, compositions and size structure were investigated during the spring-intermonsoon （April 22 to 30） of 2010 along transact 10°N of the Bay of Bengal, northern Indian Ocean. Surface phytoplankton biomass （Chl a） was （0.065±0.009） μg/L, being greater than 80% of which was contributed by pico-phytoplankton （〈3 μm）. The Chl a concen- tration vertically increased to the maximal values at deep chlorophyll maximum （DCM） layer that shoaled eastwards from 75 to 40 m. The Chl a biomass at DCM layer generally varied between 0.2 and 0.4 μg/L, reaching the maximum of 0.56 μg/L with micro-phytoplankton cells （~20 #m） accounting for 58% and nano- （3-20μm） or pico-cells for 15% and 27%, respectively. In particular, the cells concentration coupling well with phosphate level was observed at middle layer （75-100 m） of 87° to 89°E, dominated by micro-cells diatoms （e.g., Chaetoceros atlanticus v. neapolitana, Chaetoceros femur and Pseudonitzsehia sp.） and cyanobacteria （i.e., Trichodesmium hildebrandtii）, With the ceils concentration reached as high as 4.0 × 10^4 and 4.3 × 10^4 cells/L. At the rest of the trans- act however, dinoflagellates （e.g., Amphisdinium carterae and Prorocentrum sp.） were the dominant species, with the cells concentration varying from 0.3×10^3 to 6.8×10^3 cells/L. Our results also indicate that the regulation of large cells （micro-, nano-） on phytoplankton biomass merely occurred at DCM layer of the Bay.

Variability of phytoplankton absorption in the northern South China Sea:influence of the size structure and pigment composition of algal populations

Data from three cruises conducted in the Zhujiang River （ZR）, coastal waters of Guangdong （CWGD） and the northern South China Sea （NSCS） during 2003 and 2004 were examined for assessing the relative importance of pigment composition and packaging effect in modifying the specific absorption coefficients of phytoplankton. The three survey regions differ widely in their phytoplankton community with large cells dominating the ZR and CWGD waters and small cells dominating the NSCS region. Variations in the size structure and the accessory pigments have much effect on the chlorophyll a-specific absorption coefficient of phytoplankton. The size index accounted for about 42% and 33% of the variation of the specific absorption coefficient at 440 and 675 nm, respectively. Using the multiple regression analysis approach, pigment concentrations for each sample were calculated. The accessory pigments other than chlorophyll a contribute to absorption mainly in the blue - to - green region of the spectrum and their absorptions account for about 44%, 43% and 53% on the average of the total phytoplankton absorption at 440 nm for the ZR, CWGD and NSCS regions. Among the accessory pigments, the photosynthetic carotenoids （noted PSC） play a dominant role in the ZR and CWGD waters, while in the NSCS the nonphotosynthetic carotenoids （noted PPG） as well as PSC have important contributions. Because the variations of both the size structure and accessory pigments in algal populations contributed to the variability of the specific absorption coefficient in the study regions, these factors may be considered explicitly in future bio - optical algorithms to derive chlorophyll a concentration more accurately.

The Structure and Size-effect of Calcium Modified Lead Titanate Nanocrystal,Pb_(0.85)Ca_(0.15)TiO_3

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Phytoplankton pigment pattern in the subsurface chlorophyll maximum in the South Java coastal upwelling system, Indonesia

Upwelling occurs on the coast of Java between June and October, forced by local alongshore winds associated with the southeasterly monsoon. This causes variations in phytoplankton community composition in the upwelling zone compared with the surrounding offshore area. Based on pigments analysis with subsequent calculations of group contributions to total chlorophyll a(Chl a) using CHEMTAX, we studied the distribution and composition of phytoplankton assemblages in the subsurface chlorophyll maximum along the south coast of Java and the influence of upwelling. Nineteen phytoplankton pigments were identified using high-performance liquid chromatography, and CHEMTAX analysis associated these to ten major phytoplankton groups. The phytoplankton community in the coastal area influenced by upwelling was characterized by high Chl a and fucoxanthin concentrations, indicating the dominance of diatoms. In contrast, in the offshore area, the Chl a and fucoxanthin concentrations declined to very low levels and the community was dominated by haptophytes represented by 19′-Hexanoyloxyfucoxanthin. Accordingly, microphytoplankton was found to be the major size class in the coastal area influenced by upwelling, while nanophytoplankton was most abundant in the offshore area. Low concentrations of other accessory pigments indicated less contribution from dinoflagellates,prasinophytes, chlorophytes and cryptophytes. Photo-pigment indices revealed that photosynthetic carotenoids(PSCs) were the largest component of the pigment pool, exceeding the proportion of Chl a, with the average PSCTP up to 0.62. These distribution trends can mainly be explained by phytoplankton adaption strategies to upwelling and subsurface conditions by changing species composition and adjusting the pigment pool.

Topology-based analysis of pelagic food web structure in the central and eastern tropical Pacific Ocean based on longline observer data

The tropical Pacific Ocean supports many productive commercial fisheries.However,few studies of ecosystem structure in the tropical Pacific Ocean have been carried out.In this study,we analyzed the food web structure in the central and eastern tropical Pacific Ocean based on trophic relationships of 35 pelagic species collected by Chinese tuna longline observers from June to November in 2017.Topology indices(node degree,D;centrality indices,BC and CC;topological importance indices,TI^1,TI^3;keystone indices,K,K_t and K_b)and Key-Player algorithms(KPP-1,KPP-2)were used to select key species and construct a simplified food web combined with body size data.The Kendall rank correlation and hierarchical clustering analysis indicated that different topology indices resulted in consistent rankings of key species.Most key species were the same as those selected in other studies in the Pacific Ocean,such as Shortbill spearfish(Tetrapturus angustirostris),Swordfish(Xiphias gladius),Albacore tuna(Thunnus alalunga),cephalopods and scomber.The food web would be separated into many unconnected parts(F=0.632,FD=0.795,R^D=0.957)after the removal of the five key species,indicating the key roles of these species in the food web structure and stability.Body size was considered an influential indicator in constructing the simplified food web.This study can improve our understanding of the food web structure in the tropical Pacific Ocean and provide scientific basis for further ecosystem dynamics studies.

A plastidic ATP/ADP transporter gene, IbAATP, increases starch and amylose contents and alters starch structure in transgenic sweetpotato

A plastidic adenosine triphosphate（ATP）/adenosine diphosphate（ADP） transporter（AATP） is responsible for importing ATP from the cytosol into plastids. In dicotyledonous plants, increasing ATP supply is a potential way to facilitate anabolic synthesis in heterotrophic plastids. In this study, a gene encoding the AATP protein, named Ib AATP, was isolated from sweetpotato（Ipomoea batatas（L.） Lam.）. Transcripts of Ib AATP were predominantly detected in the storage roots and leaves and were induced by exogenous sucrose and subjected to circadian rhythm. Transient expression of Ib AATP in tobacco and onion epidermal cells revealed the plastidic localization of Ib AATP. The overexpression of Ib AATP in sweetpotato significantly increased the starch and amylose contents and led to enlarged starch granules. The IbA ATP-overexpressing plants showed altered fine structure of amylopectin, which contained an increased proportion of chains with a degree of polymerization（DP） of 10–23 and a reduced number of chains with a DP of 5–9 and 24–40. In addition, starch from the transgenic plants exhibited different pasting properties. The transcript levels of starch biosynthetic genes, including Ib AGP, Ib GBSSI, Ib SSIIV, and Ib SBE, were differentially regulated in the transgenic plants. These results revealed the explicit role of Ib AATP in the starch biosynthesis of sweetpotato and indicated that this gene has the potential to be used to improve starch content and quality in sweetpotato and other plants.

Skeletochronological Study on Age Structure of a Chinese Endemic Frog(Rana omeimontis)

We used skeletochronology to estimate age structure of the Omei Wood Frog, Rana omeimontis, from southwestern China.Average age differed significantly between males and females.Age at sexual maturity in both males and females was 1 year. Longevity was 6 and 7 years for males and females, respectively. Average body size differed significantly between the sexes, with females being larger than males. A non-significant correlation between age and body size was found within each sex in this population. The ANCOVA analysis revealed that females also had larger body size than males when the effect of age was controlled.

Size Effect on the Raman Spectra and Electronic Structure of the Glycine-alanine Oligopeptide Chains

A theoretical study on oligopeptide chains of glycine-alanine by density functional theory（DFT） is given in this paper. Raman spectra of the oligopeptide chains are examined. The geometric structures, frontier orbital, energy gap, atomic charge distribution, density of states and chemical activity of the side chain are studied at the B3LYP/6-31G（d） level. Results show that, with the number of residues increasing, vibrations of typical functional groups present Raman frequency shift, and the energy gap is gradually reduced. The HOMO and LUMO focus on the amino and carboxyl at the ends of oligopeptides. It is helpful for oligopeptides to self-assemble into chains. In addition, different residues（glycine or alanine） at the ends of chains result in the even-odd effect of orbital energy in the growth process. The size effects of physical and chemical properties only exist when the oligopeptides are shorter, and the phenomenon disappeared as the chain continues to grow.

Changes in Household Size and Structure in China

ased on the most recent data from the 1990 census, this paper analyses the trend of the changing household size and structure, and the socioeconomic causes beginning in the 1950s. The relationship between the household size and structure and China's population policy is also analyzed in the paper. Two different categories of socioeconomic factors have been identified which operate in opposition to each other, influencing the increase and decrease in the desirability of co-residence of domestic groups. The future household size and structure is determined by both of them.

Thermal conductivity of carbon-based nanomaterials:Deep understanding of the structural effects

The thermal conductivity of carbon-based nanomaterials(e.g.carbon nanotubes,graphene,graphene aerogels,and carbon fibers)is a physical property of great scientific and engineering importance.Thermal conductivity tailoring via structure engineering is widely conducted to meet the requirement of different applications.Traditionally,the thermal conductivity-temperature relation is used to analyze the structural effect but this relation is extremely affected by effect of temperature-dependence of specific heat.In this paper,detailed review and discussions are provided on the thermal reffusivity theory to analyze the structural effects on thermal conductivity.For the first time,the thermal reffusivity-temperature trend in fact uncovers very strong structural degrading with reduced temperature for various carbon-based nanomaterials.The residual thermal reffusivity at the 0 K limit can be used to directly calculate the structure thermal domain(STD)size,a size like that determined by x-ray diffraction,but reflects phonon scattering.For amorphous carbon materials or nanomaterials that could not induce sufficient x-ray scattering,the STD size probably provides the only available physical domain size for structure analysis.Different from many isotropic and anisotropic materials,carbon-based materials(e.g.graphite,graphene,and graphene paper)have Van der Waals bonds in the c-axis direction and covalent bonds in the a-axis direction.This results in two different kinds of phonons whose specific heat,phonon velocity,and mean free path are completely different.A physical model is proposed to introduce the anisotropic specific heat and temperature concept,and to interpret the extremely long phonon mean free path despite the very low thermal conductivity in the c-axis direction.This model also can be applied to other similar anisotropic materials that feature Van der Waals and covalent bonds in different directions.

Thermal reffusivity： uncovering phonon behavior, structural defects, and domain size

To understand the relation between different nanostructures and thermal properties, a simple yet effective model is in demand for characterizing the underlying phonons and electrons scattering mechanisms. Herein, we make a systematic review on the newly developed thermal reffusivity theory. Like electrical resistivity which has been historically used as a theory for analyzing structural domain size and defect levels of metals, the thermal reffusivity can also uncover phonon behavior, structure defects and domain size of materials. We highlight that this new theory can be used for not only metals, but also nonmetals, even for amorphous materials. From the thermal reffusivity against temperature curves, the Debye temperature of the material and the ideal thermal diffusivity of single perfect crystal can be evaluated. From the residual thermal reffusivity at the 0 K limit, the structural thermal domain （STD） size of crystalline and amorphous materials can be obtained. The difference of white hair and normal black hair from heat conduction perspective is reported for the first time. Loss of melanin results in a worse thermal protection and a larger STD size in the white hair. By reviewing the different variation of thermal reffusivity against decreasing temperature profiles, we conclude that they reflected the structural connection in the materials. Ultimately, the future application of thermal reffusivity theory in studying 2D materials and amorphous materials is discussed.

Microscopic origin and relevant grain size effect of discontinuous grain growth in BaTiO_(3)-based ferroelectric ceramics

Barium titanate[BaTiO_(3)(BT)]-based ceramics are typical ferroelectric materials.Here,the discontinuous grain growth(DGG)and relevant grain size effect are deeply studied.An obvious DGG phenomenon is observed in a paradigmatic Zr^(4+)-doped BT-based ceramic,with grains growing from∼2.2–6.6 to∼121.8–198.4μm discontinuously near 1320℃.It is found that fine grains can get together and grow into large ones with liquid phase surrounding them above eutectic temperature.Then the grain boundary density(D g)is quantitatively studied and shows a first-order reciprocal relationship with grain size,and the grain size effect is dependent on D g.Fine grains lead to high D g,and then cause fine domains and pseudocubic-like phase structure because of the interrupted long-range ferroelectric orders by grain boundary.High D g also causes the diffusion phase transition and low Curie dielectric peak due to the distribution of phase transition temperature induced by internal stress.Local domain switching experiments reveal that the polarization orientation is more difficult near the grain boundary,implying that the grain boundary inhibition dominates the process of polarization orientation in fine-grain ceramics,which leads to low polarization but a high coercive field.However,large-grain ceramics exhibit easy domain switching and high&similar ferroelectricity.This work reveals that the grain boundary effect dominates the grain size effect in fine-grain ceramics,and expands current knowledge on DGG and grain size effect in polycrystalline materials.

Spatiotemporal distribution of size-fractioned phytoplankton in the Yalu River Estuary,China

The grain size structure of phytoplankton has great influence on shellfish culture.The present study aimed to assess the spatial and temporal variation in the phytoplankton community structure in the Yalu River Estuary and to explore the relationship between the phytoplankton community structure and various environmental parameters in 2020.High-throughput sequencing was used in this study.The results showed that nanophytoplankton,especially Karlodinium veneficum,dominated the estuary throughout the year.The biomass ratio of picophytoplankton,nanophytoplankton,and microphytoplankton were 20:63:17 in spring,30:44:26 in summer,1:38:61 in autumn,and 2:45:53 in winter,respectively.Meanwhile,Dinophyta had the greatest biomass throughout the year,followed by Bacillariophyta.On the spatial dimension(Station average),COD,T,SST had a positive impact on total phytoplankton communities,and Dep had a negative impact.In the time dimension(Monthly average),the environmental factor that significantly controlled the phytoplankton community structure were NO2 and SST.

Crystalline phase of Y_2O_3 :Eu particles generated in a substrate-free flame process

In this study, factors affecting the crystal structure of flame-synthesized Y2O3 ：Eu particles were investigated, especially the particle size effect and its interaction with Eu doping concentration, Polydisperse Y2O3：Eu （size range 200 nm to 3μm） powder samples with Eu doping concentrations from 2,5 mol% to 25 mol% were generated in either H2/air or H2/O2 substrate-free flames. The crystal structure of the powder samples was determined by powder X-ray diffraction （XRD）, which was complemented by pho- toluminescence （PL） measurements. Single particle crystal structure was determined by single particle selected area electron diffraction （SAED）, and for the first time, by electron backscatter diffraction （EBSD）. H2/air flames resulted in cubic phase Y2O3：Eu particles with hollow morphology and irregular shapes, Particles from H2/O2 flames had dense and spherical morphology; samples with lower Eu doping concen- trations had mixed cubic/monoclinic phases; samples with the highest Eu doping concentrations were phase-pure monoclinic. For samples generated from H2/02 flames, a particle size effect and its interaction with Eu doping concentration were found： particles smaller than a critical diameter had the monoclinic phase, and this critical diameter increased with increasing Eu doping concentration, These findings suggest that the formation of monoclinic Y2O3：Eu is inevitable when extremely hot substrate-free flames are used, because typical flame-synthesized Y203 ：Eu particle sizes are well below the critical diameter, However, it may be possible to generate particles with dense, spherical morphology and the desired cubic structure by using a moderately high flame temperature that enables fast sintering without melting the particles.

Silica shell-assisted synthetic route for mono-disperse persistent nanophosphors with enhanced in vivo recharged near-infrared persistent luminescence

Near-infrared （NIR） persistent-luminescence nanoparticles have emerged as a new class of background-free contrast agents that are promising for in vivo imaging. The next key roadblock is to establish a robust and controllable method for synthesizing monodisperse nanoparticles with high luminescence brightness and long persistent duration. Herein, we report a synthesis strategy involving the coating/etching of the SiO2 shell to obtain a new class of small NIR highly persistent luminescent ZnGa2O4：Cr^3＋,Sn^4＋（ZGOCS） nanoparticles. The optimized ZGOCS nanoparticles have an excellent size distribution of -15 nm without any agglomeration and an NIR persistent luminescence that is enhanced by a factor of 13.5, owing to the key role of the SiO2 shell in preventing nanoparticle agglomeration after annealing. The ZGOCS nanoparticles have a signal-to-noise ratio -3 times higher than that of previously reported ZnGa204：Cr^3＋ （ZGC-1） nanoparticles as an NIR persistent-luminescence probe for in vivo bioimaging. Moreover, the persistent-luminescence signal from the ZGOCS nanoparticles can be repeatedly re-charged in situ with external excitation by a white light- emitting diode; thus, the nanopartides are suitable for long-term in vivo imaging applications. Our study suggests an improved strategy for fabricating novel high-performance optical nanoparticles with good biocompatibility.