Medical Laboratory Program 1st Level Summer Course - Basic Physics PDF

Medical Laboratory Program st 1 Level Summer Course Basic Physics Prof. Dr. Soltan Soltan Professor of Materials Science Physics Department Faculty of Science Helwan University Introduction: Medical Laboratory Devices: D...

Medical Laboratory Program st 1 Level Summer Course Basic Physics Prof. Dr. Soltan Soltan Professor of Materials Science Physics Department Faculty of Science Helwan University Introduction: Medical Laboratory Devices: Does Physics Matter??? What we can learn from Physics in order to understand Device applications? Basic Physics : Heat Effects of temperature on structure, Phase State,….etc. Electricity Electron motion, Conductivity, Resistivity, energy gap. Magnetism Spin, moment, Electron spin resonance (ESR) Optics : Reflectivity, Transmission, Emission, Lenses’, ……. Applications and Devices: X-ray, Magnetic Imaging, Radiation, ……. Medical Laboratory Devices and Output Images NMR Nuclear Magnetic Resonance XRD MRI X-Ray Diffraction Magnetic Resonance Imaging  Table 1. Some commonly used symbols for dimensionless numbers, with their commonly accepted meanings and examples of their use. The last three entries in this table are rarely seen, and are best not used. See also comments in the text concerning the meaning of billion and trillion. Name Symbol Value Examples of use Possible replacement Percent, or part percent, or The degree of dissociation was % or pph 10−2 Use % rather than pph parts per hundred 1.5 % The mole fraction of CO2 in the part per million ppm 10−6 atmosphere is about x(CO2) = µmol/mol 300 ppm The air quality standard for nmol/mol for mole fraction, or part per billion ppb 10−9 ozone is a volume fraction nL/L for volume fraction of φ = 120 ppb The volume fraction of NO in air part per trillion ppt 10−12 pmol/mol or pL/L is φ = 140 ppt part per quadrillion ppq 10−15 rarely used Use percent or ppm with a The mole fraction of CO2 in the part per thousand, or permille ppt, or ‰ 10−3 power of ten. Avoid using ppt atmosphere is 0.3 ‰, or 0.3 ppt which is clearly ambiguous. The mass fraction of impurity in part per hundred million pphm 10−8 the metal was less than 5 pphm Physics Department Helwan University Contents Chapter I: Heat Phenomena and Thermal Physics Chapter II: Heat and Matter Chapter III: Calorimetry Chapter IV: Thermometry Chapter V: Heat Transfer Chapter VI: Thermal Analysis Physics Department Helwan University Heat and Matter When heat energy is given to a body one or more of the following reversible effects are observed: (i) Change in temperature (Body gets hotter). (ii) Change in state (solid to liquid or liquid to vapour). (iii) Change in phase (crystallographic structure). (iv) Change in size (expansion or contraction). (v) Change in physical properties (electric or magnetic). (vi) Change in colour. Physics Department Helwan University Change of State Physics Department Helwan University Heating & Cooling Curves Heat energy substance increase of temperature change of state. Reverse changes take place on cooling. Such changes can be studied by heating or cooling curves. Physics Department Helwan University Heating and Cooling Curves 120 100 W+V vapour Vapour 80 boiling Temperature, oC 60 40 20 0 water Water -20 I+W melting ice Ice Time = Thermal energy Physics Department Helwan University Phase Diagrams # Most materials are subjected to one or more phase transformations in the course of their manufacture. # Phase transformation is associated with many important technologies, e.g., casting of metals, heat treatment of steel, sintering of ceramics and molding of polymers. # Phase diagram: Shows phases that exist in equilibrium for a material of given chemical composition. Determines nature and amount of each phase. Called unary, binary, ternary, …… constitutional diagrams for one, two, three, …… different chemical Physics Department Helwan University One Component Systems Common features: [A] Three areas represent solid (S), liquid (L) & gaseous (G) state: where only one phase exists. B [B] Three lines: Loci of values of pressure and C temperature at which one phase transfers to other if heat is supplied or removed, or at which two (L) phases can exist if a substance is isolated. (S) O (OA): Equilibria of Solid-Gas = “sublimation point” vs pressure (OB): Equilibria Solid-Liquid = “melting point” (G) A or “freezing point” vs pressure. (OC): Equilibria Liquid-Gas = “boiling or condensation point” vs pressure. Pressure-Temperature equilibrium phase diagrams Slop of OA and OC is always +ve. [C] Triple point (O): solid, liquid & vapour of one component system coexist in equilibrium. Physics Department Helwan University One Component Systems # Pressure-temperature equilibrium phase diagrams of one component system are divided into: two classes: Distinction between the two classes of substances is reflected in the slop of OB: 1st class:- substances which expand on solidification: slope of OB curve is –ve (such as water and bismuth). 2nd class: substances which contract on solidification: slope of OB curve is +ve (such as carbon dioxide and oxygen). When change in volume is very small, OB curve becomes almost vertical. Physics Department Helwan University Phase Equilibria and Phase Rule Phase (P): homogenous, physically distinct portion of system that is separated from other portions of the system by bounding surface # Two-phase system: water and its vapour. # Three-phase system: mixture of ice, water and vapour. Number of Components (C): smallest number of constituents by which composition of each phase in a system can be expressed in form of a chemical formula or equation # One component: mixture of ice, water and vapour since composition of all three phases is described by one chemical formula H2O. # Two components: three-phase system, CaCO3 + CaO + CO2, the composition of each phase can be expressed by a combination of any two of the chemical species (phases) present. For example, CaCO3 and CO2 are chosen; one can write CaO as [CaCO3 - CO2] or CaCO3 as [CaO + CO2]. Degrees of freedom (F): number of variables that can be varied within Physics Department Helwan University Phase Rule F=C–P+2 Number of Degrees System Comments phases of freedom gas, liquid or 1 F=1-1+2=2 Bivariant system: lies anywhere within solid the area marked (G, L or S). gas-liquid, 2 F=1-2+2=1 Univariant system: lies anywhere liquid-solid or along a line between two phases gas-solid regions (AO, BO or CO). gas-liquid-solid 3 F=1-3+2=0 Invarient system: can only lie at the triple point (O). Physics Department Helwan University Effect of Pressure on Phase Transformation Vapour pressure of material: Pressure of its vapour in equilibrium with solid or liquid at certain temperature. Curves OA and OC are graphs of vapour pressure versus temperature. Vapour pressure is only a function of temperature and is independent on the volume of each phase does not depend on relative amount of vapour, solid or liquid present in vessel containing vapour in equilibrium with solid or liquid at constant temperature Physics Department Helwan University Effect of Pressure on Phase Transformation Boiling point (OC): Temperature at which vapour pressure equals external pressure. # Increases as pressure increases. Sublimation temperature (OA): # Increases as pressure increases. Melting point (OB): # Raises in case of substance that expands on melting or contract on solidification by an increase in (pressure acts as constraint). # Reduces in case of substance that contracts on melting or expands on solidification (pressure helps process). O A Physics Department Helwan University Change in Size: Fundamentals There is change in volume associated with phase transformation. Change in size during heating or cooling body is considered in rang of temperature where no change in phase. Considerable part of the thermal energy of solid is in the form of atomic vibrations: varying amplitude. measured lattice spacing between Mechanical atoms is mean figure depends model upon temperature. Physics Department Helwan University Vibrational Modes Atomic vibrations can Longitudinal or Transverse In Longitudinal Vibration: Atoms vibrate along bond direction. In Transverse Vibration: Atoms vibrate perpendicular to bond direction. Physics Department Change in Size : Helwan University Fundamentals Balance in force between repulsion of neighboring ion-cores due to their electron shells overlapping and attraction of particular bonding type (ionic, covalent or metallic) lattice constant for particular solid. Minimum in dependence of potential energy upon interatomic distance equilibrium lattice constant. Addition of vibrational energy to atom is represented by horizontal line A1A2. Mean interatomic distance is midway between A1 and A2, at A0. Maximum kinetic energy of vibration = height “Asymmetric nature” above O. of potential energy Physics Department Helwan University Change in Size: Fundamentals r0 is the equilibrium bond length at 0K r is the average bond length (the distance between neighboring atoms) at elevated temperatures. Physics Department Helwan University Coefficient of Thermal Expansion In case of a body in the form of wire or rode, only change in length with temperature is, usually, considered. T2 T T1 L  L0 T =  L0 T = L - L0 =  L0 T L0 L L = L0 [1 +  (T2 – T1)] L  = fractional change in length to change in temperature. = (dL /L) / dT =1/L. dL/dT Physics Department Helwan University Coefficient of Thermal Expansion In case of a sheet of dimensions W0 and L0, the change in area (A) is, usually, considered. T2 T WW T1 0 L = L0 (1 +  T) W = W0 (1 +  T) L0 L.W = L0. W0 (1 +  T)2 L A = A0 (1 + 2 T+  2 T2) = A0 (1 + 2T) = A0 (1 + T)  = 2 Physics Department Helwan University Coefficient of Thermal Expansion Coefficient () of area (planer) expansion is defined in deferential form as ratio between fractional change in area (dA/A) to change in temperature dT:  = (dA /A) /dT = 1/A. (dA/dT) unit is K-1. 1 dA 1 dL2 = = 2 A dT L dT 1 dL2 dL 1 dL = (. ) = ( 2L ) L2 dL dT L2 dT 1 dL =2 = 2 L dT Physics Department Helwan University Coefficient of Thermal Expansion In case of a rectangular parallelepiped with dimension a0, b0 and c0, the change in volume (V) is, usually, considered. c c0 a0 a b0 a.b.c = a0.b0.c0 (1+  T)3 b Neglecting the high power of  V = V0 (1+ 3 T) = V0 (1+ T)  = 3 In a differential form:  = (dV /V) / dT = 1/V. dV/dT Physics Department Helwan University Coefficient of Thermal Expansion Coefficient () of area (planer) expansion is defined in deferential form as ratio between fractional change in volume (dV/V) to change in temperature dT:  = (dV /V) /dT = 1/V. (dV/dT) unit is K-1. 1 dV 1 dL3 = = 3 V dT L dT 1 dL3 dL 1 2 dL = 3 (. ) = 3 (3L ) L dL dT L dT 1 dL =3 = 3 L dT Physics Department Helwan University Negative Thermal Expansion (NTE) Physicochemical process some materials contract upon heating rather than expanding as most materials do. There are physical processes which may cause contraction with increasing temperature: 1) Phase transition. 2) Transverse vibrational modes. 3) Rigid unit modes. Physics Department Helwan University Transverse Vibrational Mode For complex systems, there are certain categories of materials contraction in volume. a) Longitudinal vibration along an M–O–M bond expansion of M–O and M–M distance will increase. b) Transverse vibration: M–O distance remains essentially unchanged M–M distance will decrease transverse “guitar string” vibrations negative thermal expansion. M M a: Longitudinal vibration b: Transverse vibration Physics Department Helwan University Rigid Unit Modes Relatively stiff individual tetrahedra or octahedra (strong M–O bonds and relatively short O–O distances preventing distortion of such polyhedra) but joined by relatively “loose” hinges; M–O–M bending potentials being as much as 100 times weaker than the stiffness of individual polyhedra Framework minerals such as β-quartz can show negative thermal expansion at high temperatures. Coupled rotations of these polyhedra can occur with no distortion of intrapolyhedral bond distances and angles.  Physics Department Helwan University Animations showing the potential structural flexibility of ZrW2O8 Physics Department Helwan University Change in Volume of Water There are exceptions to general rules (anomalous behaviour): Ice (solid) contracts on vapour melting. ice water As temperature of water raised from 0 to 4oC, the volume decreases. From 4 to 100 oC, volume increases as usual. Water has its minimum volume and maximum density at 4 oC. Physics Department Helwan University Consequence of Anomalous Behaviour of Water Water expands upon freezing ice bergs float. Physics Department Helwan University Consequence of Anomalous Behaviour of Water As air temperature falls: water at the surface cools Air temperature below 0oC becomes denser sinks to the bottom. When the surface water is cooled below 4 oC: it does not sink. Continues surface cooling freezing takes place. # Sea and pond animals and plants can live in slightly Physics Department Helwan University Structure of H2O Hydrogen bonds, with their extra attractive energy, are the cause of many of unusual properties of water, including its large heat of vaporization and its expansion upon freezing. The open solid structure ice is less dense than water. Water structure Ice structure Physics Department Helwan University Dry Ice It is solid carbon dioxide. Sudden expansion of pressed CO2 dry ice. It sublimes at –78°C extremely cold gas. Physics Department Helwan University Applications of Thermal Expantion The Rivet: # It is hammered into its hole while it is red-hot. #On cooling, it contracts and pulls the plates together very tightly. Physics Department Helwan University A) Positive Thermal Expansion Thermostat (automatic control (a) Large → expansion  Small expansion of temperature): Cooled Heated Cooled Heated Switch current on or off. (b) # Depends on expansion. # Depends on the bending of bi-metal strip when heated or cooled. Physics Department Helwan University A) Positive Thermal Expansion 1. Outer dial enables to set temperature at which thermostat switches on and off. 2. Bimetal ("two metal") strip is made of two separate metal strips fastened together: piece of brass bolted to a piece of iron. 3. Iron expands less than brass as it gets hotter, so bimetal strip curves inward as temperature rises. 4. Bimetal strip forms part of electrical circuit: a-When strip is cool, it is straight, so it acts as abridge through which electricity can flow. Circuit is on and so is heating. b- When strip is hot, it bends and breaks circuit, so no electricity can flow. Now circuit is Physics Department Helwan University B) Negative Thermal Expansion Thermal expansion causes many problems in engineering, and indeed in everyday life. The most obvious is in composite materials where overall expansion coefficient of body can be precisely tailored to specific positive, negative or even zero value. If one mix negative thermal expansion material with a "normal" material which expands on heating, it could be possible to make zero expansion composite material. Tendency of dental fillings to expand, when drinking cold or hot drink, by an amount different from teeth toothache. Zero expansion composites can be employed in high precision optical mirrors thin metallic layers are coated on substrate; use of zero expansion substrate leads to mirror whose optical properties do not degrade as temperature is varied. Physics Department Helwan University Thermal Stresses Mechanical stress induced in body when some or all of its parts are not free to expand or contract in response to changes in temperature → it "can't". Thermal expansion or contraction may not occur freely in all directions because of: 1) Geometry. 2) External constraints. 3) Temperature gradients. Stresses are produced. Physics Department Helwan University Thermal Stresses What does it happen when structure or member is constrained, so it can not expand or contract? Let rode expand freely due to thermal expansion L0 A ∆LT =  ∆T Lo L = Lo + ∆ LT = Lo (1 +  ∆T) L0 Thermal Expansion ∆LT Compress it back to its original length L0+∆LT (mechanical deformation). Mechanical / = (F/A) / (∆Lm/L) = Y compression ∆Lm ∆Lm = (1/Y) (F/A) [L0 (1 + ∆T)] F (L0+∆LT)-∆Lm F = (1/Y) (F/A) L0, ←[∆T