Star is a brilliantly glowing sphere of hot gas whose energyis produced by an internalnuclear fusion process. Stars are contained in galaxies. A galaxy contains not only stars, but clouds of gas and dust. These clouds are callednebulae, and it is in a nebula where stars are born. In the nebula is hydrogen gas which is pulled together by gravityand starts to spin faster. Over millions of years, more hydrogen gas is pulled into the spinning cloud. The collisions which occur between the hydrogen atoms starts to heat the gas in the cloud. Once the temperature reaches 15,000,000 degrees Celsius, nuclear fusion takes place in the center, or core, of the cloud. The tremendous heat given off by the nuclear fusion process causes the gas to glow creating a protostar. This is the first step in the evolution of a star. The glowing protostar continues to accumulate mass. The amount of mass it can accumulate is determined by the amount ofmatter available in the nebula. Once its mass is stabilized, the star is known as a main sequence star. The new star will continue to glow for millions or even billions of years. As it glows, hydrogen is converted into helium in the core by nuclear fusion. The core starts to become unstable and it starts to contract. The outer shell of the star, which is still mostly hydrogen, starts to expand. As it expands, it cools and starts to glow red. The star has now reached the red giant phase. It is red because it is cooler than the protostar phase and it is a giant because the outer shell has expanded outward. All stars evolve the same way up to the red giant phase. The amount of mass a star has determines which of the following life cycle paths the star will take.
Answer:
Explanation:
Pharmacophore (pharmacology) - The molecular framework responsible for a drug's biological activity. According to IUPAC — A pharmacophore is the ensemble of steric and electronic features that is necessary to ensure the optimal supramolecular interactions with a specific biological target structure and to trigger (or to block) its biological response.
Privileged structures are defined as molecular frameworks which are able of providing useful ligands for more than one type of receptor or enzyme target by judicious structural modifications.
1) The 1,4-dihydropyridine ring is present in many biologically important molecules that acts as an important scaffold for cardiovascular drug - a calcium antagonists and although it is technically not considered as a pharmacophore, it is considered as a privileged structure.
1,4-Dihydropyridine (DHP), belongs to the class of calcium antagonist that inhibits the influx of extracellular Ca+2 through the L-type voltage-dependent calcium channels.
A positional substitution in the 4-position is feasible in the heterocyclic ring which in turn culminates in various calcium channel antagonist activities and this heterocyclic ring is the common feature for various pharmacological activities such as anti-inflammatory activity, analgesic activity,
antihypertensive, antianginal, antitumor, antitubercular activity and antithrombotic .
Position on the heterocyclic ring binds to the L-type channel and also to N-type channel on membranes.
2.) The bioisosteres are not a suitable bioisostere for the traditional C-4 aryl or heteroaryl substitution which is necessary for calcium ion blockage thereby inhibiting it to function with the mechanism shared above.
The earliest written use of the name, spelled Rontaks, was in 1724 by the French missionary Joseph-François Lafitau. He defined it as tree eaters. In the Mohawk language, Adirondack means porcupine, an animal that may eat bark. The Mohawks had no written language at the time so Europeans have used various phonetic spellings. An English map from 1761 labels it simply Deer Hunting Country and the mountains were named Adirondacks in 1837 by Ebenezer Emmons.
Answer:
many moons
Explanation:
None of Jupiter's moons have more than traces of atmosphere, so their skies are very nearly black. ... For an observer on Io, the closest large moon to the planet, Jupiter's apparent diameter would be about 20° (38 times the visible diameter of the Moon, covering 5% of Io's sky).