Researchers reveal new cellular mechanical transducer
A research team has uncovered a novel regulator governing how cells respond to mechanical cues. Their findings appear in Nature Cell Biology.
A research team has uncovered a novel regulator governing how cells respond to mechanical cues. Their findings appear in Nature Cell Biology.
Cell & Microbiology
12 hours ago
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2
A research team consisting of NIMS and the Tokyo University of Science observed charge density waves (CDWs) within niobium diselenide (NbSe2)—a layered compound—at cryogenic temperatures and discovered that they form ...
Condensed Matter
May 9, 2024
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62
Infanticide and adoption in the animal kingdom have long puzzled scientists. While both males and females of many species are known to kill the babies of their rivals to secure sexual or social advantage, other animals have ...
Plants & Animals
May 7, 2024
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12
Hydrogen energy is considered a promising solution with high energy density and zero pollution emissions. Currently, hydrogen is mainly derived from fossil fuels, which increases energy consumption and greenhouse gas emissions, ...
Nanomaterials
May 6, 2024
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1
Primordial black holes are hypothetical objects formed during the earliest moments of the universe. According to the models, they formed from micro-fluctuations in matter density and spacetime to become sand grain-sized mountain-massed ...
Astronomy
May 6, 2024
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90
Inexpensive and readily available copper-based catalysts are considered ideal for the electrochemical CO2 reduction reaction (CO2RR) to produce multi-carbon products. The presence of copper oxides is crucial for generating ...
Nanomaterials
Apr 29, 2024
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1
A team of physicists from several institutions across the U.S. working with a colleague from China, at the DIII-D National Fusion Facility, in San Diego, California, has devised a way to overcome two key hurdles standing ...
The California Fish and Game Commission has formally recognized the Mojave desert tortoise as endangered.
Plants & Animals
Apr 22, 2024
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14
Scientists at the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) and their international collaborators have recently developed a new method for efficiently extracting information from galaxy ...
Astronomy
Apr 19, 2024
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1000
The idea that the universe is expanding dates from almost a century ago. It was first put forward by Belgian cosmologist Georges Lemaître (1894–1966) in 1927 and confirmed observationally by American astronomer Edwin Hubble ...
General Physics
Apr 15, 2024
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661
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ (the Greek letter rho). In some cases (for instance, in the United States oil and gas industry), density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight. Different materials usually have different densities, so density is an important concept regarding buoyancy, purity and packaging. Osmium and iridium are the densest known metal elements at standard conditions for temperature and pressure but not the densest materials.
Less dense fluids float on more dense fluids if they do not mix. This concept can be extended, with some care, to less dense solids floating on more dense fluids. If the average density (including any air below the waterline) of an object is less than water (1000 kg/m3) it will float in water and if it is more than water's it will sink in water.
In some cases density is expressed as the dimensionless quantities specific gravity (SG) or relative density (RD), in which case it is expressed in multiples of the density of some other standard material, usually water or air/gas. (For example, a specific gravity less than one means that the substance floats in water.)
The mass density of a material varies with temperature and pressure. (The variance is typically small for solids and liquids and much greater for gasses.) Increasing the pressure on an object decreases the volume of the object and therefore increase its density. Increasing the temperature of a substance (with some exceptions) decreases its density by increasing the volume of that substance. In most materials, heating the bottom of a fluid results in convection of the heat from bottom to top of the fluid due to the decrease of the density of the heated fluid. This causes it to rise relative to more dense unheated material.
The reciprocal of the density of a substance is called its specific volume, a representation commonly used in thermodynamics. Density is an intensive property in that increasing the amount of a substance does not increase its density; rather it increases its mass.
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