Precipitation is the creation of a solid from a solution. When the reaction occurs in a liquid solution, the solid formed is called the'precipitate'; the chemical that causes the solid to form is called the'precipitant'. Without sufficient force of gravity to bring the solid particles together, the precipitate remains in suspension. After sedimentation when using a centrifuge to press it into a compact mass, the precipitate may be referred to as a'pellet'. Precipitation can be used as a medium; the precipitate-free liquid remaining above the solid is called the'supernate' or'supernatant'. Powders derived from precipitation have historically been known as'flowers'; when the solid appears in the form of cellulose fibers which have been through chemical processing, the process is referred to as regeneration. Sometimes the formation of a precipitate indicates the occurrence of a chemical reaction. If silver nitrate solution is poured into a solution of sodium chloride, a chemical reaction occurs forming a white precipitate of silver chloride.
When potassium iodide solution reacts with lead nitrate solution, a yellow precipitate of lead iodide is formed. The precipitation may occur. Precipitation may occur from a supersaturated solution. In solids, precipitation occurs if the concentration of one solid is above the solubility limit in the host solid, due to e.g. rapid quenching or ion implantation, the temperature is high enough that diffusion can lead to segregation into precipitates. Precipitation in solids is used to synthesize nanoclusters. An important stage of the precipitation process is the onset of nucleation; the creation of a hypothetical solid particle includes the formation of an interface, which requires some energy based on the relative surface energy of the solid and the solution. If this energy is not available, no suitable nucleation surface is available, supersaturation occurs. Precipitation reactions can be used for making pigments, removing salts from water in water treatment, in classical qualitative inorganic analysis.
Precipitation is useful to isolate the products of a reaction during workup. Ideally, the product of the reaction is insoluble in the reaction solvent. Thus, it precipitates. An example of this would be the synthesis of porphyrins in refluxing propionic acid. By cooling the reaction mixture to room temperature, crystals of the porphyrin precipitate, are collected by filtration: Precipitation may occur when an antisolvent is added, drastically reducing the solubility of the desired product. Thereafter, the precipitate may be separated by filtration, decanting, or centrifugation. An example would be the synthesis of chromic tetraphenylporphyrin chloride: water is added to the DMF reaction solution, the product precipitates. Precipitation is useful in purifying products: crude bmim-Cl is taken up in acetonitrile, dropped into ethyl acetate, where it precipitates. Another important application of an antisolvent is in ethanol precipitation of DNA. In metallurgy, precipitation from a solid solution is a useful way to strengthen alloys.
An example of a precipitation reaction: Aqueous silver nitrate is added to a solution containing potassium chloride, the precipitation of a white solid, silver chloride, is observed. AgNO 3 + KCl ⟶ AgCl ↓ + KNO 3 The silver chloride has formed a solid, observed as a precipitate; this reaction can be written emphasizing the dissociated ions in a combined solution. This is known as the ionic equation. Ag + + NO 3 − + K + + Cl − ⟶ AgCl ↓ + K + + NO 3 − A final way to represent a precipitate reaction is known as a net ionic reaction. Many compounds containing metal ions produce precipitates with distinctive colors; the following are typical colors for various metals. However, many of these compounds can produce colors different from those listed. Other compounds form white precipitates. Precipitate formation is useful in the detection of the type of cation in a salt. To do this, an alkali first reacts with the unknown salt to produce a precipitate, the hydroxide of the unknown salt. To identify the cation, the color of the precipitate and its solubility in excess are noted.
Similar processes are used in sequence – for example, a barium nitrate solution will react with sulfate ions to form a solid barium sulfate precipitate, indicating that it is that sulfate ions are present. Digestion, or precipitate ageing, happens when a freshly formed precipitate is left at a higher temperature, in the solution from which it precipitates, it results in bigger particles. The physico-chemical process underlying digestion is called Ostwald ripening. Coprecipitation Salting in Salting out Effervescence Zumdahl, Steven S.. Chemical Principles. New York: Houghton Mifflin. ISBN 0-618-37206-7. Precipitation reactions of certain cations Digestion Instruments A Thesis on pattern formation in precipitation reactions
Gian P. Gentile is a retired US Army colonel, who served for many years as a history professor at the United States Military Academy at West Point. Gentile has been a visiting fellow at the Council on Foreign Relations and a senior historian at the RAND Corporation, he is a leading critic of U. S. military counter-insurgency doctrine. Gentile enlisted in the US Army in 1975 and graduated from UC-Berkeley's ROTC program in 1986, he completed a PhD in history at Stanford University in 2000. He served two tours in Iraq, first as the executive officer of a combat brigade in Tikrit in 2003 and as a squadron commander in western Baghdad in 2006. Gentile's post-graduate academic work was on the topic of military air power. How Effective is Strategic Bombing?, published in 2001, challenged the conclusions of the Strategic Bombing Survey. Reflecting on Gentile’s work, the book review editor for The Journal of Conflict Studies wrote that “strategic bombing seems to have adapted itself nicely to the exigencies of democratic government.
But that “it is left to Gian Gentile... to pose the question US policy-makers should be asking: How effective is strategic bombing?” The reviewer opined that “Gentile's answers are fresh because he... show the reader that the question has been answered or in some cases, competently.” He echoed Gentile’s central point that “the US Air Force among others has and sometimes purposely, failed to distinguish between the effects of strategic bombing and its effectiveness,” emphasizing that the “effects, physically observed and measured, are easy to see and to report--and impress the public with.” However, “the effectiveness of same is wide open for debate.”Gentile's second book, Wrong Turn: America's Deadly Embrace of Counterinsurgency, appeared in July 2013. Andrew Rosenbaum, in the New York Journal of Books, said: "Col. Gentile capably shows that counterinsurgency, which can be summed up as a'nation-building' strategy, didn’t work in the past, when the British tried it in Malaysia, nor when the U.
S. tried it in Vietnam, that it did not work in Iraq and Afghanistan, despite the hype it received when it was tried. A separate chapter is dedicated to each of these efforts, Col. Gentile goes into sufficient detail to make a good case. Col. Gentile shows that the strategy is fundamentally flawed, cannot work in the form that it has been proposed." Gentile is a prominent critic of the U. S. military's use of counter-insurgency. He believes that the 2007 surge was not the primary cause of the reduction in violence in Iraq and that effective counter-insurgency tactics were practiced by American troops in Iraq starting in 2004, rather than being introduced in 2007. Instead, Gentile argues that paying Sunni insurgents to help coalition forces eradicate al-Qaeda in Iraq and Muqtada al-Sadr's decision to call a cease fire in southern Iraq were the main causal factors, he further argues that the U. S. military is now concentrating excessively on counter-insurgency, to the detriment of its capacity to fight conventional wars.
Following Andrew Bacevich, Gentile believes that the prominence of counterinsurgency has led to an unrealistic view of the American military's power and capacity to change the world
Live A Live is a role-playing video game developed and published by Square for the Super Famicom, released on September 2, 1994. It was never released outside Japan, but it has been unofficially translated into English and Chinese, it was released on the Virtual Console for Nintendo Wii U on June 24, 2015 and New Nintendo 3DS on November 28, 2016 in Japan. Live A Live's story begins with a series of seven unrelated chapters that can be played in any order, based on popular genres such as Western, science fiction, mecha; each chapter has its own plot and characters. Although the basic gameplay is the same throughout the game, every chapter has its own unique gimmick, such as the stealth elements in the ninja chapter. After the first seven chapters are completed, the game's final sequence plays out, linking the previous chapters together and resolving the story. Live A Live contains the basic elements of a role-playing video game; the characters explore dungeons, towns, or similar areas, fight enemies, gain experience points to level up.
However, the game eschews some elements typical of the genre, such as money. The game has tactical battles that play out on a grid. Certain attacks can change tiles into damage zones. More powerful skills have long charge times, which commits the character to that single attack for a long time, gives the enemy an opportunity to interrupt them. Characters can be inflicted with status ailments, certain items and skills can raise or lower a character or enemy's stats while in battle; when a character's hit points reach zero, they collapse and are unable to move, but can be revived by using a healing item or spell. However, if they are hit when in the knocked-out state, they permanently disappear from the battle. In addition to these basic gameplay mechanics, each chapter contains some variations on the standard formula. Live A Live has a large number of characters; the main character of the prehistoric chapter, Pogo, is a young caveman who has just come of age, only capable of saying the word "love".
Master Xin Shan Quan is an old kung-fu master seeking to pass on his art. Oboro-maru is a ninja of the Enma with great potential sent on an important mission; the Sundown Kid is a wandering cowboy famous for his skill with a gun. Masaru Takahara is a wrestler with the dream of being the strongest fighter in the world who possesses a strong sense of justice. Akira Tadokoro is an orphan in the near future with psychic powers. Cube is a self-aware robot created by the mechanic Kato aboard the spaceship Cogito Ergosum. Oersted is a famous knight in the realm of Lucretia, betrothed to the King's only daughter. Odio, whose name is Latin for hate, is the main antagonist of the game; the first seven chapters can be played in any order, the final two chapters open up after they are completed. In prehistoric times, a tribe of cavemen prepares to sacrifice a woman named Bel to their deity, a living Tyrannosaurus rex named O-D-O, she escapes to the south and hides in a cave belonging to another tribe, stealing their food to survive.
She is discovered by a young caveman named Pogo, who falls in love with her and decides to help her hide from the rest of the tribe. The northern tribe attacks to retrieve her. However, Bel is discovered in the process, the elder exiles them. Pogo is forced to fight O-D-O, is assisted by a warrior of the northern tribe named Zaki. After the beast is defeated, peace is established between the two tribes and the first word, "Love", is said. In ancient China, an old kung-fu master of the Xin Shan Quan tradition takes on three students to pass on his art before he dies. While the master is away one day, the dojo is attacked by a rival dojo seeking revenge for an insult. Two of the students are killed, prompting the master and the surviving student to avenge their deaths; the rival school, led by Odi Wang Lee, is defeated, but the master dies afterward, having used the last of his strength in the fight. The student takes a new generation of students. In feudal Japan, a mysterious figure named; the ninja clan Enma sends one of their ninja named Oboro-maru to rescue a prisoner who can stabilize Japan kill Ode Iou.
After being rescued, the prisoner joins Oboro in the battle with Ode Iou. After Ode Iou is slain, the prisoner reveals. Oboro is given the choice of returning to the Enma or joining Ryōma in his plans to rebuild Japan; this chapter takes place in the American Old West. An outlaw called the Sundown Kid and his rival, a bounty hunter named Mad Dog, arrive in Success Town, a place terrorized by a group of bandits called the Crazy Bunch, led by O. Dio, the last remaining survivor of the 7th Cavalry. Sundown stands up to the bandits, they decide to raze the town in retaliation. Mad Dog agrees to help the townsfolk prepare the town's defenses. After the town emerges from the battle victorious, Mad Dog challenges Sundown to one final duel; the player has the option of running away. The