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Answer: The following table lists diffraction angles for

Materials Science and Engineering: An Introduction | 9th Edition | ISBN: 9781118324578 | Authors: William Callister ISBN: 9781118324578 140

Solution for problem 3.76 Chapter 3

Materials Science and Engineering: An Introduction | 9th Edition

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Materials Science and Engineering: An Introduction | 9th Edition | ISBN: 9781118324578 | Authors: William Callister

Materials Science and Engineering: An Introduction | 9th Edition

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Problem 3.76

The following table lists diffraction angles for the first three peaks (first-order) of the x-ray diffraction pattern for some metal. Monochromatic x-radiation having a wavelength of 0.0711 nm was used. (a) Determine whether this metals crystal structure is FCC, BCC, or neither FCC or BCC, and explain the reason for your choice. (b) If the crystal structure is either BCC or FCC, identify which of the metals in Table 3.1 gives this diffraction pattern. Justify your decision.

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Chapter 17: Physiology of the Kidneys Primary function of kidneys is in the regulation of the extracellular fluid (plasma and interstitial fluid) environment of the body • Accomplished through formation of urine o During this process, kidneys regulate § Volume of blood plasma à contribute significantly to the regulation of blood pressure § Concentration of waste products in blood § Concentration of electrolytes (Na, K, HCO3, etc.) § pH of plasma • Kidneys considered most potent acid-­‐base regulator Gross Anatomy of the Urinary System • Kidneys: lie on either side of the vertebral column below the diaphragm and liver o About the size of a fist o Coronal Section of kidney has 2 regions § Outer renal cortex – reddish brown and granular because of numerous capillaries § Deeper renal medulla – striped due to the presence of microscopic tubules and blood vessels • Composed of 8-­‐15 conical renal pyramids separated by renal columns o Cavity of the kidney is divided into several portions § Minor calyx – small depression that each pyramid projects into § Major calyx – formed by union of several minor calyces à major calyces join to form renal pelvis • Renal pelvis: cavity where urine produced in the kidneys is drained to o Urine then channeled from the kidneys to the urinary bladder through the ureters o Ureters: long ducts that undergo peristalsis (wave-­‐like contractions) § Pacemaker of these peristaltic waves is located in the renal calyces and pelvis, which contain smooth muscle – renal calyces and pelvis also undergo peristalsis to aid emptying of urine from kidney • Urinary bladder: storage sac for urine o Shape is determined by amount of urine it contains § Empty = pyramidal § As it fills = ovoid and bulges into abdomen o Drained inferiorly by urethra o Has a muscular wall – detrusor muscle Microscopic Anatomy of the Kidney • Nephron – functional unit of the kidney o Responsible of urine formation o Comprised of renal corpuscle and renal tubules § Renal corpuscle – glomerulus and Bowman’s capsule • Glomerular filtration § Renal tubules – proximal convoluted tubule, distant convoluted tubulues and Loop of Henle • Tubular secretion • Tubular absorption o 2 types: § Cortical – original in the outer 2/3 of the cortex • More numerous § Juxtamedullary – originate in the inner 1/3 of the cortex (next to the medulla) • Have longer nephron loops • Play an important role in kidney’s ability to produce a concentrated urine • Glomerular (Bowman’s) capsule: surrounds the glomerulus o Contains an inner visceral layer and outer parietal layer o Space between the two layers is continuous with the lumen of the tubule o Filtrate that enters glomerular capsule passes into lumen of the proximal convoluted tubule § Proximal convoluted tubule contains millions of microvilli to increase surface area for reabsorption § See absorption o Fluid passes from the proximal convoluted tubule to the nephron loop (Loop of Henle) § This fluid is carries into the medulla in the descending limb of the loop and returns to the cortex in the ascending limb o Distal convoluted tubule: coiled tubule in the cortex § See secretion § Shorter than proximal tubule § Relatively few microvilli § Terminates as it empties into a collecting duct o Collecting duct: receives fluid from the distal convoluted tubule of several nephrons § Fluid is drained by the collecting duct from the cortex to the medulla as the collecting duct passes through a renal pyramid § Fluid is now called urine à passes into minor calyx à funneled through renal pelvis out of the kidney into the ureter • Vasculature o Renal artery: where arterial blood enters kidney o Renal artery divides into interlobular arteries that pass between pyramids through the renal columns o Arcuate arteries branch from interlobular arteries at the boundary of the cortex and medulla o Afferent arterioles: microscopic arterioles formed from branching of Arcuate arteries § Deliver blood into glomeruli (capillary network that produce a blood filtrate that enters the urinary tubules) o Efferent arteriole: where remaining blood in the glomerulus leaves through § Delivers blood into another capillary network – peritubular capillaries surrounding the renal tubules § This blood is drained into veins that parallel the course of the arteries in the kidney à interlobular, arcuate, and interlobar veins § Interlobar veins leave kidney as a single renal vein à empties into inferior vena cava o Arrangement of blood vessels is unique § Only one in which capillary bed is drained by an arteriole instead of a venule and delivered to a second capillary bed downstream Glomerular Filtration • Urine formation begins with the filtration of plasma from glomerular capillaries into Bowman’s capsule à glomerular filtration – results in formation of filtrate • Process utilizes a pressure gradient • Endothelial cells of the glomerular capillaries have large pores (fenestrae) o Causes glomerular capillaries to be 100-­‐400x more permeable to plasma water and dissolved solutes than skeletal muscle capillaries o Pores are still small enough to prevent entry of RBC, WBC and platelets • Before fluid in blood plasma can enter the interior of the glomerular capsule, it must pass through 3 layers of selective filters o Fluid entering is referred to as filtrate – will become modified as it passed through the different segments of the nephron tubules to become urine o Capillary fenestrae – first potential filtration barrier § Large enough to allow proteins to pass but are surrounded by charges that may present some barriers to plasma proteins o Glomerular basement membrane – second potential barrier § Layer of collagen and proteoglycans lying immediately outside the endothelium § Most resists fluid flow into the capsule lumen § Offer some barrier to plasma proteins o Slit Diaphragm – third potential barrier § Visceral layer of glomerular capsule is made up of podocytes § Unique epithelial cells with a bulbous cell body, primary processes and thousands of foot processes § Processes are attached to the basement membrane § Narrow slits between adjacent foot processes provide passageways for molecules entering the interior of the glomerular capsule as glomerular filtrate § Slit diaphragm – links interdigitating foot processes and presents the last potential filtration barrier Forces Involved in Filtration • Filtration occurs due to opposing forces o Important elements § Blood pressure § Protein concentration in plasma compared to filtrate (not many proteins in filtrate) • Glomerular filtration rate (GFR) o Volume filtered from the glomeruli into Bowman’s capsule per unit time § Average ~115-­‐125mL/min § Consider average blood volume is 5.5L à total blood volume is filtered every 40 minutes • Osmotic pressure established by presence of protein in plasma and not really in filtrate o Greater colloid osmotic pressure of plasma promotes the osmotic return of filtered water o Net filtration pressure of about 10 mmHg – since glomerular capillaries are extremely permeable and have a large surface area, this modest filtration pressure produces an extraordinary large volume of filtrate Regulation of GFR • Vasoconstriction or vasodilation of afferent arterioles affects rate of blood flow into glomerulus • Observe variety of intrinsic and extrinsic mechanisms to ensure GFR is high enough to eliminate wastes and regulate blood pressure – but not too high as to cause excessive water loss o Sympathetic nerve endings § Vasoconstriction occurs in afferent arterioles § Helps to preserve blood volume and divert blood to the muscles and heart o Renal auto regulation § Observe relatively constant GFR with fluctuation BP • Afferent arterioles dilate when BP falls below average and constrict when BP is above average • Changes in efferent arterioles are of secondary importance § Myogenic regulation • Smooth muscle of afferent arterioles sensitive to stretch – result in vasoconstriction when stretched § Result of effects of locally produced chemicals on the afferent arterioles • Tubuloglomerular feedback o Macula densa: specialized cells that act as the sensor – part of a larger functional unit (Juxtaglomerular apparatus) • Increased delivery of NaCl and H2O to the distal tubule causes macula densa to release chemical signal causing constriction of the afferent arteriole Renal Reabsorption • Most salt and water filtered return to blood via reabsorption o Defined as the return of filtered molecules from the renal tubules to the blood o Proximal convoluted tubule facilitates reabsorption • Obligatory water loss – minimal volume needed to ensure excretion of metabolic wastes o ~400 mL of urine a day • Observe that transport of water is passive, occurring via osmosis à therefore a concentration gradient must be established between filtrate and blood that favors osmotic return o Filtrate is iso-­‐osmotic to plasma, so we must use interstitial fluid o In some cases, active transport of solute concentrations is used to facilitate osmosis • Process begins in the epithelial cells of the proximal convoluted tubule o Epithelial cells are joined by apically located tight junctions – create regions for exchange • Sodium drives reabsorption o Sodium concentration in filtrate and plasma are equal but lower in the cytoplasm of the epithelial cells § Low NA+ concentration due to low permeability and Na/K pump moving Na into interstitial fluid § A potential difference is created across the proximal tubule epithelial cell wall à electrically favors Cl-­‐ movement from tubular fluid to interstitial fluid o An increase in osmotic pressure of interstitial fluid surround proximal tubule cells creates an osmotic gradient between interstitial fluid and tubular filtrate o The proximal tubule is permeable to water so water moves out by osmosis • As water moves, solute concentration in tubular fluid increases, if mechanisms in place then solute moves o Thus solutes follow solvents – explains how the passive absorption of these solutes occur o Also observe use of Na gradient for co-­‐transport of solute • Transport maximum is limited – if concentration exceeds saturation, there is a loss of urine • Obligatory water reabsorption: water is moved through osmosis by settling up sodium gradient • Fluid components are kept Osmotically balanced due to properties of the renal tubule o ~85% of original filtrate is reabsorbed in early regions leaving ~15% to enter the distal convoluted tubule and collecting ducts § 15% x GFR of 180L/day = 27L/day § This is still an excessive amount so it must be reabsorbed to varying degrees to in accordance with the needs of the body § This is fixed by hormones that act on the distal tubule and collecting duct Countercurrent Multiplier System and Countercurrent Exchange • For organism survival with limited water intake, a mechanism must be in place to produce a concentrated (hyperosmotic) urine • Human kidney can produce a maximum urinary concentration of 1400mosm/L o Almost 5x the plasma osmolality o Occurs in medullary collecting ducts § Presence of ADH allows the reclaim of water o How does the medullary interstitial fluid become so concentration § Functions of the loop of Henle in the Juxtamedullary nephrons, vasa recta and trapping of urea in kidney medulla • Ascending Limb of the Loop of Henle: o Divided into two regions: § Thin segment near the tip of the loop § Thick segment carries the filtrate into the distal convoluted tubule in the renal cortex o NaCl is actively extruded from the thick segment § Na moves passively down its concentration gradient from the filtrate into the cells à powers inward secondary active transport of K+ and Cl-­‐ § Na is then transported into the interstitial fluid via the Na/K pump • Cl-­‐ passively follows the Na+ due to the electrical attraction • K+ passively diffuses back into the filtrate o The ascending limb is not permeable to water so water cannot follow the flow of salt as seen in the proximal tubule à by the time the filtrate reaches the distal tubule the filtrate is very dilute and the interstitial fluid is hypertonic to it • Descending Limb of the Loop of Henle o Does not actively transport salt and is impermeable to the passive transport of it o Unlike the ascending limb, the descending limb is permeable to water § Allows it to release water Osmotically § Increases the salt concentration arriving in the ascending limb à increases salt transport by the ascending limb so that the NaCl concentration of the interstitial fluid is multiplied • Countercurrent Multiplication o Positive feedback mechanism is created by the interactions of the proximal and distal tubule effecting the concentrations of filtrate and interstitial fluid § The more salt extruded by the ascending limb, the more concentrated the fluid that is delivered to it from the descending limb will be § Positive feedback mechanism that multiplies the concentration of the interstitial fluid and descending limb fluid is called the countercurrent multiplier system • Steps of the mechanism: Start with isosmotic fluid leaving descending and reaching ascending à NaCl is pumped out actively à NaCl trapped in interstitial fluid by vasa recta (blood vessels) o NaCl pumped out of ascending limb causes interstitial fluid to be hypertonic o The hypertonic interstitial fluid causes the descending limb to release water through osmosis à causes filtrate to be somewhat hypertonic when it reaches back to the ascending limb o The now higher NaCl concentration in the ascending limb allows it to pump out more NaCl than it did before because more NaCl is available to carriers à causes interstitial fluid to become even more concentrated o The increased concentration of interstitial fluid causes even more water to be drawl out of the descending limb à causes filtrate to be even more hypertonic when it reaches back to the ascending limb o The progression repeats to a higher extend each time until the maximum concentration is reached in the inner medulla – the maximum value is determined by the capacity of the active transport pumps working along the lengths of the thick segments of the ascending limbs • What does the countercurrent multiplier accomplish o Increases concentration of renal interstitial fluid from 300 mOsm in the cortex to 1200 mOsm in the inner medulla – the hypertonicity of the renal medulla is critical because it serves as the driving force of water reabsorption through the collecting ducts • Vasa recta: o Vessels that parallel the nephron loop o Have urea transporters and aquaporins in the plasma membrane § Allows for them to gain salt and urea and lose water o Countercurrent exchange: mechanism allowing vasa recta to maintain hypertonicity § Salt and other dissolved solutes found in high concentration in the interstitial fluid diffuse into descending vasa recta § The same solutes passively diffuse out of the ascending vasa recta and back into the interstitial fluid à completes countercurrent exchange § This constant circulation allows for the solute to be trapped in the medulla o Net action of the vasa recta is to remove water from the interstitial fluid of the renal medulla Effects of Urea § Urea functions as an osmotically active molecule o Trapped within the medullary interstitial fluid because of constant recycling – supports this regions high osmolality § Presence of NaCl and urea make interstitial fluid very hypertonic, creating an environment so that water can leave via osmosis from the collecting ducts Collecting Duct and ADH: § The collecting duct is impermeable to NaCl but has aquaporins allowing water to flow § Since the interstitial fluid is hypertonic, water flows out of the collecting duct via osmosis o The water does not dilute the surrounding interstitial fluid because it is transported back to general circulation in the vascular system § The force driving osmosis is created by the countercurrent multiplier system o Concentration gradient is thus kept relatively constant but can change based on variations in permeability to water made by regulating the number of aquaporins § Aquaporins – water channels in the plasma membrane of the collecting duct epithelial cells § When plasma osmolality increases by as little as 1%, the anterior pituitary secretes arginine vasopressin – functions as antidiuretic hormone (ADH) o In response, cAMP is produced and after a series of reactions inserts aquaporins on the plasma membrane o Increased number of aquaporins increases the collecting ducts permeability to water and allows for increased water reabsorption à facultative water reabsorption o Decreased release of ADH decreases the number of aquaporins in the membrane, decreasing water permeability, decreasing water reabsorption and causing for more dilute urine excretion in larger volumes § ADH release is stimulated by Osmoreceptors in the hypothalamus due to change in blood plasma osmolality § In cases of extreme dehydration increasing amounts of ADH will be released o Urine excretion will decrease until it reaches the obligatory water loss ~400 mL/day o Decrease in urine excretion is limited to this value because urine cannot become more concentrated than the interstitial fluid § Note: even in the complete absence of ADH some water will still be reabsorbed through the collecting ducts Renal Plasma Clearance § Renal clearance – ability of kidneys to remove molecules from blood plasma by excreting urine – “clearing” blood of particular solutes o Clearing occurs due to glomerular filtration and tubular secretion o Reabsorption decreases renal clearance § Excretion rate = (filtrate rate + secretion rate) – reabsorption rate o After filtration, if a solute is neither secreted or reabsorbed, the excretion rate = filtration rate o Under that assumption, the glomerular filtration rate can be determined and used to assess the health of the kidneys § Glomerular filtration rate = volume of blood plasma filtered per minute § While most substances produced in the body are always either secreted or reabsorbed, insulin is not à rate of insulin filtration is exactly equal to rate of excretion of it o GFR = (V x U) / P § V = rate of urine formation § U = concentration of substance in urine § P = concentration of substance in plasma § Renal plasma clearance is the volume of plasma from which a substance is completely removed in one minute by excretion in the urine o When the substance is neither reabsorbed nor secreted, GFR = renal plasma clearance o Renal plasma clearance = GFR = (VU)/P o If a solute is reabsorbed, the renal plasma clearance of a substance must be less than the GFR o If a solute is secreted, the renal plasma clearance will be less than the GFR § Glucose and amino acids are easily filtered from blood through Bowman’s capsule but are not found in excreted urine à indicates they must be completely reabsorbed o Reabsorption of these occurs on the proximal convoluted tubule via secondary active transport of carrier proteins o Carrier proteins exhibit property of saturation § One carrier = 1 molecule at a take § Transport maximum: exists when the transported molecule is present in such high concentrations that all carrier proteins are occupied and the transport rate reaches a maximum Renal Control of Electrolytes § Kidneys assist with regulation of several electrolytes by matching urinary excretion with dietary intake o 90% of filtered Na and K are reabsorbed by the proximal convoluted tubule § Occurs at a constant rate § Not subjected to hormonal regulation but in regard to body needs § Role of aldosterone in Na and K balance – modifies o Regulation can occur via the mineralocorticoid aldosterone § Na reabsorption • Excrete ~30mg a day in urine • Na concentration can diminish to 0 in the presence of aldosterone • Induces synthesis of all channels and pumps in collecting duct § Filtration relies on blood pressure and radius of afferent/efferent arteriole § Potassium secretion o Occurs in distal convoluted tubule and collecting ducts § Aldosterone-­‐dependent potassium secretion • Potassium rich mean increases blood potassium and stimulated adrenal cortex to release aldosterone – results in potassium secretion into filtrate § Also can occur via aldosterone-­‐independent potassium secretion • Potassium rich meal causes insertion of potassium channels into plasma membrane of cortical collecting duct cells due to concurrent elevation in blood potassium concentration o Another mechanism – sensory: § With increased sodium due to increase flow in filtrate, it is “sensed” by a primary cilium § So as flow “bends” the cilium it activated potassium channels leading to increased potassium secretion § Explains how some diuretics can cause low blood potassium levels Control of aldosterone secretion § Aldosterone promotes Na retention and K secretion – thus with a rise in blood K levels aldosterone secretion is increased (direct mechanism) § However, with Na the process is more complex and typically involves a fall in blood volume along with activation of the renin-­‐angiotensin-­‐aldosterone system (indirect mechanism) Atrial Natriuretic Peptide § With an increased blood volume, observe salt secretion and water loss which is due in part to inhibition of aldosterone release § However, natriuretic peptides are involved in long-­‐term Na and water balance (also blood volume and pressure) o Natriuretic peptides – serve as a counter-­‐regulatory system for the renin-­‐angiotensin-­‐aldosterone system § Produces in cells in the atria and other areas such as the brain § Cause an increase in GFR § Produces: • Natriuesis – increased sodium excretion • Diuresis – increased fluid in excretion § K sparing: since Na is secreted, spare K will be taken up Relationship Between Na, K and H § Blood K concentration indirectly affects blood H concentration § Observe that as extracellular H+ concentration increases in the collecting duct, some H+ moves into the cell and causes cellular K to diffuse outward into extracellular fluid o Reestablishes proper ratio of these ions in extracellular fluid with same occurring in distal convoluted tubule cells § As Na moves, K and or H are secreted to maintain charge balance o In acidosis – observe an increase in blood K concentration (not secreted) o In alkalosis – observe a decrease in blood K concentration (secreted) o Hyperkalemia (too much K in blood) leads to acidosis because when K is secreted, H is retained Renal Acid-­‐Base Regulation § Kidneys assist with blood pH regulation by excreting H+ and reabsorbing bicarbonate § H+ enters filtrate by glomerular filtration and secretion into renal tubules à the acidification of urine § Tubule cells are impermeable to bicarbonate so its absorption is indirect § During acidosis, proximal convoluted tubule can make more bicarbonate via glutamine metabolism o Bicarbonate goes into blood and formed NH3 buffers urine § During alkalosis, less bicarbonate is reabsorbed due to less H in filtrate o Excretion assists with compensation for alkalotic condition Urinary Buffers § As blood pH falls below 7.35, urine pH typically falls below 5.5 o Note that the nephron cannot produce a urine below 4.5 o To excrete more H+ it must be buffered § Bicarbonate cannot accomplish this because it is mostly reabsorbed § Alternatives: phosphates and ammonia

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Chapter 3, Problem 3.76 is Solved
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Textbook: Materials Science and Engineering: An Introduction
Edition: 9
Author: William Callister
ISBN: 9781118324578

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Answer: The following table lists diffraction angles for