Zirconium Facts (Atomic Number 40 or Zr)

Zirconium is a gray metal that has the distinction of being the last element symbol, alphabetically, of the periodic table. This element finds use in alloys, particularly for nuclear applications. Here are more zirconium element facts: ZirconiumBasic Facts Atomic Number: 40 Symbol: Zr Atomic Weight: 91.224 Discovery: Martin Klaproth 1789 (Germany); zircon mineral is mentioned in biblical texts. Electron Configuration: [Kr] 4d2 5s2 Word Origin: Named for the mineral zircon. Persian zargun: gold-like, which describes the color of the gemstone known as zircon, jargon, hyacinth, jacinth, or ligure. Isotopes: Natural zirconium consists of 5 isotopes; 28 additional isotopes have been characterized. The most common natural isotope is 90Zr, which accounts for 51.45 percent of the element. Of the radioisotopes, 93Zr has the longest half-life, which is 1.53x106 years. Properties: Zirconium is a lustrous grayish-white metal. The pure element is malleable and ductile, but the metal becomes hard and brittle when it contains impurities. Zirconium resists corrosion from acids, alkalis, water, and salt, but it does dissolve in hydrochloric or sulfuric aicd. Finely-divided metal may ignite spontaneously in air, especially at elevated temperatures, but the solid metal is relatively stable. Hafnium is found in zirconium ores and is difficult to separate from zirconium. Commercial-grade zirconium contains from 1% to 3% hafnium. Reactor-grade zirconium is essentially free of hafnium. Uses: Zircaloy(R) is an important alloy for nuclear applications. Zirconium has a low absorption cross section for neutrons, and is therefore used for nuclear energy applications, such as for cladding fuel elements. Zirconium is exceptionally resistant to corrosion by seawater and many common acids and alkalis, so it is used extensively by the chemical industry where corrosive agents are employed. Zirconium is used as an alloying agent in steel, a getter in vacuum tubes, and as a component in surgical appliances, photoflash bulbs, explosive primers, rayon spinnerets, lamp filaments, etc. Zirconium carbonate is used in poison ivy lotions to combine with urushiol. Zirconium alloyed with zinc becomes magnetic at temperatures below 35 °K. Zirconium with niobium is used to make low temperature superconductive magnets. Zirconium oxide (zircon) has a high index of refraction and is used as a gemstone. The impure oxide, zirconia, is used for laboratory crucibles that will withstand heat sh ock, for furnace linings, and by the glass and ceramic industries as a refractory material. Occurrence: Zirconium does not exist as a free element, primarily due to its reactivity with water. The metal has a concentration of around 130 mg/kg in the Earths crust and 0.026 ÃŽ ¼g/L  in sea water. Zirconium is found in S-type stars, the Sun, and meteorites. Lunar rocks contain a zirconium oxide concentration comparable to that of terrestrial rocks. The primary commercial source of zirconium is the silicate mineral zircon (ZrSiO4), which occurs in Brazil, Australia, Russia, South Africa, India, the United States, and in smaller amounts elsewhere in the world. Health Effects: The average human body contains about 250 milligrams of zirconium, but the element serves no known biological function. Dietary sources of zirconium include whole wheat, brown rice, spinach, eggs, and beef. Zirconium is found in antiperspirants and water purification systems. Its use as a carbonate to treat poison ivy has been discontinued because some people experienced skin reactions. While zirconium exposure is generally considered safe, exposure to the metal powder can cause skin irritation. The element is not considered to be either genotoxic or carcinogenic. Crystal Structure: Zirconium has an alpha phase and a beta phase. At room temperature, the atoms form close-packed hexagonal ÃŽ ±-Zr. At 863  Ã‚ °C, the structure transitions to body-centered ÃŽ ²-Zr. Zirconium Physical Data Element Classification: Transition Metal Density (g/cc): 6.506 Melting Point (K): 2125 Boiling Point (K): 4650 Appearance: grayish-white, lustrous, corrosion-resistant metal Atomic Radius (pm): 160 Atomic Volume (cc/mol): 14.1 Covalent Radius (pm): 145 Ionic Radius: 79 (4e) Specific Heat (20 °C J/g mol): 0.281 Fusion Heat (kJ/mol): 19.2 Evaporation Heat (kJ/mol): 567 Debye Temperature (K): 250.00 Pauling Negativity Number: 1.33 First Ionizing Energy (kJ/mol): 659.7 Oxidation States: 4 Lattice Structure: Hexagonal Lattice Constant (Ã…): 3.230 Lattice C/A Ratio: 1.593 References Emsley, John (2001). Natures Building Blocks. Oxford: Oxford University Press. pp. 506–510. ISBN 0-19-850341-5.Lide, David R., ed. (2007–2008). Zirconium. CRC Handbook of Chemistry and Physics. 4. New York: CRC Press. p. 42. ISBN 978-0-8493-0488-0.Meija, J.; et al. (2016). Atomic weights of the elements 2013 (IUPAC Technical Report). Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305 Return to the Periodic Table

Challenges Faced With Migrant Workers During An Aged Care...

The following section analyses the identified challenges supported by recent studies that deal with migrant workers in an aged care institutions. Language and Communication Oral and written English communication skills are a few of the challenges that managers face with the migrant care workers, which incorporates various dialects and accents. Elderly residents are usually not used to different accents and as a result, residents tend to lose patience with their carers. However, incompetency with language is also observed among residents. For instance, Ngocha-Chaderopa and Boon (2015) mentioned that in dementia unit, residents have a tendency to speak incoherently. Lovelock and Martin (2015) agrees that aged care workers face communication challenges with elderly especially for those residents with dementia. Moreover, residents tend to get frustrated and aggressive at times when they do not understand their carers, hence it is very important for carers to have patience as well when caring for elderly in general and specifically for dementia patients. Among the interviewees in Lovelock and Martin’s (2015) study, an eldercare worker has mentioned t hat communication is the most difficult challenge. The carer was badly injured when a frustrated resident did not understand and became violent despite the fact that they do not intend to hurt anyone. Migrant care workers mediate the experience of their work despite the challenges, for the reason of securing a permanent residencyShow MoreRelatedThe Practice of Social Policy in Botswana1892 Words   |  8 Pages2012). 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Imagery Foreshadowing Free Essays

Creating Suspense In the short story, â€Å"Three Skeleton Key† by George Outdoes, imagery and foreshadowing are important literary devices used in this story. Outdoes use s these two devices to help create suspense in the acts of the three lighthouse workers being data eked by sea rats. Foreshadowing is a literary device used by authors to give hints what is to co me later in the story. We will write a custom essay sample on Imagery Foreshadowing or any similar topic only for you Order Now Foreshadowing is a nonchalant warning for events that follow. Tout ouzo States, â€Å"Three Skeleton Key, the small rock on which the light stood, bore a bad reputation. † (peg 1) The author sees foreshadowing here to hint toward unfortunate events that happen later on. For example, the ship wrecks on the island. Eventually the rats take over the lighthouse, forcing the three men to be locked into one room of the lighthouse with no supplies. After the rat invasion ion, one of the men, Eel Glee, goes mad, another, Ithaca, dies from an infected rat bite. Too douse also states, â€Å"Watching her sail dead for us, a white wave boiling her bows, Eel Glee cried 0 UT, â€Å"What’s wrong with her crew? † (peg 2) The author uses foreshadowing here to hint tow arts the death of the crew from the ship, and the crew that worked on the lighthouse. The fate of the crew from the ship was that they had to abandon the ship because of the invasion of the shih p by sea rats. The crew had to abandon the ship, they were left for death in the middle of the co mean. The lighthouse crew was destined to a chaotic series of events dealing with the same sea rats . The crew is pretty much bound for death when trapped inside the room of the lighthouse with n o supplies. Foreshadowing is important in the act of creating the suspense in this story. Imagery is a literary device used by authors to visually describe their work. Im age rye helps reader to feel even close to the action in the story. Outdoes says, â€Å"If you u so much as harm one, his sharp cry will bring hordes of his fellows to swarm over you, and not cease until your flesh has been stripped from your bones. (peg 4) He uses imagery in this case to show how vengeful the rats truly are. These lines make you visualize the rats swarming o very and striping your flesh from your bones. How to cite Imagery Foreshadowing, Papers

Microbiology Study Guide free essay sample

The sum of all biological chemical reactions inside a cell or organism Differences in catabolism and anabolism: Catabolism is an enzyme-regulated chemical reaction that releases energy. Complex organic compounds such as glucose, amino acids, glycerol and fatty acids are broken down into simpler ones. The energy of catabolic reactions is used to drive the anabolic reactions. Anabolism is also enzyme regulated but requires energy for taking the simpler broken down components from the catabolism phase and building them into complex molecules such as starch, proteins and lipids What is the role of ATP? ATP is the driving force for catabolic and anabolic reactions. ATP stores energy that is produced from the catabolic reactions which is later released to drive the anabolic reaction and other cellular work. ATP is stored energy in cells (phosphate groups held together by high energy reacting bonds) ATP is required for synthesis and some of the energy is given off as heat What are enzymes and their components? Enzymes are biological catalysts (substances that speed up a chemical reaction without themselves being permanently altered) Components: Apoenzyme is the protein portion of an enzyme. Inactive by themselves, must be activated by cofactors Cofactor- non protein portion (IE: ions of iron, zinc, magnesium and calcium) ****If the cofactor is an organic molecule, it is called a coenzyme Holoenzyme- The apoenzyme+cofactor forms the holoenzyme. It is the active enzyme. If you remove the cofactor, the apoenzyme will not function. **Cofactors may assist the enzyme by accepting atoms removed from the substrate or by donating atoms required by the substrate. Substrate=the specific substance that an enzyme will act on) **The crucial function of enzymes is to speed up biochemical reactions at temperatures that are compatible with the normal functioning of the cell. What are metabolic pathways? The sequence of enzyme catalyzed chemical reactions within a cell. What is the Kreb’s cycle? A pathway that converts two-carbon compounds to CO2, transferring electrons to NAD+ and other carriers; also called tricarboxylic acid (TCA) cycle or citric acid cycle A series of biochem ical reactions in which a large amount of potential chemical energy stored in acetyl CoA is released step by step. In the cycle, a series of oxidations and reductions transfer that potential energy in the form of electrons to electron carrier coenzymes (mostly NAD+). The pyruvic acid derivatives are oxidized and the coenzymes are produced. Kreb’s cycle is for lipid catabolism. Glycerol is converted into dihydroxyacetone phosphate (DHAP) and catabolized via glycolysis and the Kreb’s cycle. Fatty acids undergo beta-oxidation, in which carbon fragments are spit off two at a time to form acetyl CoA which is catabolized by Kreb’s cycle. What is glycolysis? **Glycolysis creates to ATP molecules The main pathway for oxidation of glucose to pyruvic acid: Glycolysis is usually the first stage in carbohydrate catabolism. This occurs from the oxidation of glucose to pyruvic acid. Most microorganisms use this pathway and it occurs in most living cells. The term â€Å"glycolysis† means the splitting of sugar. The sugars are oxidized, release energy and then their atoms are rearranged to form 2 molecules of pyruvic acid. **Glycolysis does not require oxygen! Explanation of cellular respiration: Cellular respiration takes place after the glucose is broken down in pyruvic acid which is then channeled into the next step of either fermentation or cellular respiration. Cellular respiration is defined as the ATP-generating process in which most molecules are oxidized and the final electron acceptor is (almost always) an inorganic molecule. **operates via an electron transport chain * Aerobic respiration the final electron acceptor is O2 Anaerobic respiration the final electron acceptor is an inorganic molecule other than O2 What is an electron transport chain and why is it important? It is a system in which electrons pass through a series of different electron carriers to molecules or oxygen or other oxidized inorganic and organic molecules. The process occurs in the plasma membrane of the prokaryotes and in the mitochondrial membrane of eukaryotes. What is microbial growth? It is the growth in numbers of populations or an increase in the numb er of cells What are three physical requirements of microbial growth? PH, temperature and moisture Define psychotrophs: Are cold loving microbes, will usually be found growing in the refrigerator such as listeria (20-25oC) How does PH affect growth? Certain bacteria thrive in a specific PH environment. Acidophiles like a PH of 5. 4 or below whereas Neutrophiles (most human pathogens) prefer a more neutral environment (5. 5-7. 5 PH) Define halophiles: Extreme halophiles (obligate halophiles) are microbes that require a high salt concentration that is required for growth. Faccultative halophiles (most common) are microbes that do not require high salt concentrations for growth but can tolerate high salt solutions. How does osmotic pressure effect microbial growth? Microorganisms obtain most of all their nutrients in solutions surrounding water; therefore water is required for growth. They are composed of 80-90% water. High osmotic pressures have the effect of removing vital water from a cell. If a microbe is in a solution in which the concentration of solutes is higher than in the cell, the microbe is in a hypertonic environment which will create pressure on the cell. It will crush the cell causing the cells water to push out through the plasma membrane into the high solute concentration. What are some chemical requirements for microbes? Carbon- one of the most important for microbes next to water because it is the structural backbone Nitrogen- it is required for protein synthesis (requires some sulfur), also needed for DNA or RNA synthesis (needs some phosphorous) Vitamins and minerals- needed for essential function of enzymes, usually as co-factors. What are some organic growth factors? Essential organic compounds an organism is unable to synthesize are known as organic growth factors. They must be directly obtained by the environment. One group of organic growth factors is vitamins for human. What is a media? A media is a nutrient prepared for the growth of microorganisms. In the lab we use nutrient broths and nutrient agars. What are canophiles? Canophiles (aerobic bacteria) are microbes that grow better at high CO2 concentrations. Low oxygen high CO2 conditions resemble those found in the intestinal tract, digestive tract and other body tissues where pathogens grow. Why is a selective media desireable? Because a selective media will suppress the growth of unwanted bacteria while encouraging the growth of the desired microbes. How do prokaryotes reproduce? Reproduce by binary fission (most common) while others may go through a â€Å"budding† process 2 Categories used to control microbes (physical and chemical) Physical: Heat (dry heat such as flame or in hot ovens) heat will denature the protein causing the proteins shape to change making it no longer usable by the organism. Or (moist heat) such as with an autoclave which will force steam inside of the organism very quickly and cause it to break down Chemical: surfactants such as soaps which will work as a binding agen to the microorganism causing it to break off and be rinsed off or phenols which will disrupt the cell membrane or denature the protein therefore disrupting protein synthesis What are physical methods to control microbes? * Heat (dry and moist heat) * Cold * Radiation * Membrane filtration * Drying * Osmotic pressure What are the most common and effective ways of controlling microbes? An autoclave machine that utilizes heat, steam and pressure to kill microbes and their endospores in about 15 minutes (prions are not killed) Is it more effective to control or kill microbes? It is more effective to control the microbes because we can study live bacteria, but not if they are dead Why would we want to control microbial growth? Controlling microbes can prevent infections and food spoilage Compare and contrast chromosomes in prokaryotes and eukaryotes: Prokaryotes have 1 chromosome (only one allele) Eukaryotes have 2 chromosomes (2 alleles) DNA is not always the genetic material. What are the exceptions? How could mutations give rise to new alleles of a gene? How does translation differ from transcription? Transcription in the synthesis of a complementary strand of RNA from a DNA template Translation is the protein synthesis that involves decoding of nucleic acid and converting the information into the language of the proteins What are the differences between the leading and lagging strand? Leading strand gets replicated sequentially and gets filled first. The lagging is the strand that gets replicated sporadically based off of what is left. What are three types of RNA and what do they do? Messenger RNA (mRNA): carries genetic information from the nucleus to the cytoplasm. Transfer RNA (tRNA): transfers the necessary sequence by carrying the code. Ribosomal RNA (rRNA): helps in synthesis of proteins. Explain mutations: A mutation is the change in the base sequence of DNA. Some mutations are bad such as when the gene for an enzyme mutates. The enzyme encoded by the gene may become inactive or less active because its amino acid sequence has changed. But a mutation can also be beneficial such as when an altered enzyme encoded by the mutant gene suddenly has new or enhanced activity that will benefit the cell.