Nutrient distributions and nitrogen-anomaly(N^(*))in the tropical North Pacific Ocean

Based upon cruise observations broadly covering the tropical North Pacific during July-November 2017,together with data obtained from the World Ocean Circulation Experiment Hydrographic Program,this study examined the distribution of dissolved inorganic nitrogen(DIN,nitrate(NO_(3)^(-))+nitrite(NO_(2)^(-))),dissolved inorganic phosphorus(DIP)and related N^(*)(nitrogen-anomaly,N^(*)=N-16P+2.9,where N and P are the concentrations of DIN(>1.0μmol/L)and DIP(>0.1μmol/L)),used as an index of N2fixation,in the upper 1000 m of the water column.Nutrient concentrations displayed distinct spatial variability in the upper ocean but became relatively constant at a depth of 1000 m:they were high at low latitudes and in the eastern region,with an obvious nutricline at~150 m(DIN,~32.0μmol/L;DIP,~2.4μmol/L)and then generally increased with depth;they decreased markedly(DIN,~1.2μmol/L;DIP,~0.1μmol/L;at~150 m)at high latitudes and in the western region,where a nutricline was not apparent.The N^(*)index showed significant meridional and zonal variation,with the most negative values located at low latitudes and in the eastern region(~10°N,~150°-170°E),while becoming positive towards the northwest(the north of~18°N,~160°E westward).A N^(*)concentration larger than 2.0μmol/L which often used as an indicator of N2fixation,was observed between 155°E and 165°E;N^(*)values were 2.0μmol/L to6.0μmol/L at~15°-28°N,i.e.,much higher than those in the southern sector(0-2.0μmol/L at~5°-10°N).Zonally,N^(*)decreased gradually from west(-2.0μmol/L to 4.0μmol/L,~145°-165°E)to east(-2.0μmol/L to-8.0μmol/L,~155°W)along~10°N,which was consistent with the distribution of Trichodesmium abundance and N2fixation rates.Furthermore,since such region was also supplied with aeolian deposition,high N^(*)was probably not only induced by N2fixation but also influenced by iron and/or nitrogen deposition.

Biaxial Constitutive Model of Active Coronary Media Based on Microstructural Information

Detailed morphological data of vascular smooth muscle cells (VSMC) of coronary arteries were limited. The present study was to quantify dimensions and orientation of swine coronary VSMC and to develop a micro-structural constitutive model of active media. It was found that geometrical parameters of VSMC (length, width, spatial aspect ratio, and orientation) follow normal distributions, and VSMCs orientate towards the circumferential direction of vessels with oblique and symmetrical angles. A micro-structural model of media layer was developed to?accurately predict biaxial active responses of coronary arterial media, based on experimental measurements. The present morphological data base and micro-structural model lead to a better understanding of biomechanics of muscular vessels.

A novel stochastic reaction-diffusion model of Ca^2＋ blink in cardiac myocytes

In cardiac myocytes,the sarcoplasmic reticulum(SR)is the main storage organelle of free Ca^(2+).The concentration of free Ca^(2+)in the SR is 0.5–1.0 mmol/L and is 2–3 orders of magnitude greater than that in the cytosol.The SR is composed of interconnected cisternae(junctional SR,i.e.,JSR)and tubules(free SR network,i.e.,FSR)that extend throughout the cytosol[1].Ca^(2+)is released from the JSR into the cytosol via Ca^(2+)release units(CRUs,

The abundance,characteristics and diversity of microplastics in the South China Sea:Observation around three remote islands

Surrounded by emerging markets with considerable plastic consumption,the South China Sea has been a focus area of microplastic research.A survey on the floating microplastics(>0.3 mm)and microplastics ingested by fish and mollusks was conducted around three remote islands here.Compared with the results from several previous studies,a high abundance of floating microplastics(with a median of 1.9×10^(5)items/km^(2) or 0.7 items/m^(3))was observed,revealing another“hot spot”for microplastics.Polyolefin,especially polypropylene,was the main component.The diversity index and evenness index were calculated and evaluated based on the composition of microplastics.The characteristic peaks of Raman spectra concerning pigmented microplastics were provided.Transparent sheets/films were predominant in the water sample,which was quite different from a similar study in this sea area(8.9%for film),and only 16.4%of floating microplastics(>0.3 mm)were fibers/lines,implying that the main sources of floating microplastics(>0.3 mm)might be household/agricultural consumption activities.The transparent fiber/line was also dominant in organisms.It is suggested that the main sources of microplastics ingested by organisms might be both fabric fibers and fishing/aquaculture.

Intra-and inter-specific scaling laws of plants and animals

The allometric scaling laws of metabolism in 447 animal and 1200 plant species showed convex and concave curvatures between mass and metabolic rate,respectively.The objective of the study is to explain the difference of curvatures between animals and plants based on fractal models.Several intraspecific scaling laws were derived from an asymmetric vascular tree with the fractal dimension(i.e.,a in k^(a)_(1)+k^(a)_(2)+…-=1,where k_(i)refers to the ratio of daughter to mother diameters).Based on the intraspecific scaling laws,the allometric scaling exponent of metabolism(i.e.,an interspecific scaling law)was shown to be equal to one-third of fractal dimension.Moreover,a novel piecewise-defined function in conjunction with the intraspecific scaling laws was proposed to explain the diverse metabolic scaling in animals and plants.The intraspecific and interspecific scaling laws showed good agreement with morphometric measurements.The experimentally-validated scaling models predict the diversity of intraspecific and interspecific scaling seen in nature.To our knowledge,this is the first study to use fractal models to explain the convex and concave forms of metabolic scaling in animals and plants.The study resolves the long-term controversies to use the resource-transport network models for explanation of the allometric scaling law of metabolism.