Medical Laboratory Program Basic Physics Quiz

Medical Laboratory Program 1st Level Summer Course: Basic Physics

• Course Instructor: Prof. Dr. Soltan Soltan
• Department: Physics Department, Faculty of Science, Helwan University
• Focuses on how physics applies to medical laboratory devices and applications.

Introduction

• Medical Laboratory Devices: Does Physics Matter?: Examines the significance of physics in understanding medical devices.
• Basic Physics: Covers fundamental physics concepts relevant to medical devices.
• Heat: Effects of temperature on the structure of materials.
• Electricity: Properties like electron motion, conductivity, resistivity, and energy gap.
• Magnetism: Spin, moment, and electron spin resonance (ESR).
• Optics: Reflectivity, transmission, emission, and lenses.
• Applications and Devices: X-ray, magnetic imaging, and radiation.

Medical Laboratory Devices and Output Images

• XRD: X-Ray Diffraction, output images from this technique were shown.
• NMR: Nuclear Magnetic Resonance with associated output images.
• MRI: Magnetic Resonance Imaging, output images from this technique were shown.

Units of Measurement

• Table 1: Presents commonly used dimensionless numbers (percent, parts per million (ppm), etc.) and their values. Avoid using "ppt" (parts per trillion) and "ppq" (parts per quadrillion).

Course Content

• 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

Heat and Matter

• Heat energy given to a body causes reversible effects:
• Change in temperature (increase).
• Change in state (solid to liquid/liquid to gas).
• Change in phase (crystal structure).
• Change in size (expansion/contraction).
• Change in physical properties (electric/magnetic).
• Change in colour.

Heating and Cooling Curves

• Heat energy input causes an increase in temperature, or a change of state.
• Reverse changes (cooling) occur as well.

Phase Diagrams

• Most materials have more than one phase in their manufacture.
• Phase transformations are critical to many technologies, such as casting, metal treatment, and ceramic molding.
• Phase diagrams show the phases present in equilibrium for a material at various temperatures and pressures.
• Diagrams are classified as: unary, binary, ternary...etc., indicating the number of chemical components.

One Component Systems

• Typical features of a system with one component (e.g., water):
• Three distinct areas for solid, liquid, and gas phases.
• Three lines showing transformation points between different phases.
• Triple point: solid, liquid, and gas coexist in equilibrium.

One Component Systems - Classes of Substances

• Substances are categorized into two classes based on how they change upon solidification
• 1st class: Substances expand upon solidification (water, bismuth), Negative slope.
• 2nd class: Substances contract upon solidification (carbon dioxide, oxygen), Positive slope.

Phase Equilibria and Phase Rule

• Phase (P): homogeneously separate portion of the system.
• Number of components (C): the minimum number of constituents needed to express the composition of a phase,
• Degrees of freedom (F): number of variables that can be altered independently.
• Phase rule equation: F= C – P + 2
  • F = degrees of freedom
  • C = number of components
  • P = number of phases

Effect of Pressure on Phase Transformation

• Vapour pressure is a function of temperature and independent of volume.
• Curves of vapor pressure vs. temperature are presented graphically.
• Pressure affects boiling and sublimation points.
• Pressure increase causes vapor pressure to increase, leading to a rise in boiling and sublimation temperatures.

Effect of Pressure on Phase Transformation - Melting Points

• Pressure influences melting points, affecting substances that expand, or contract on melting or solidifying.

Change in Size

• Volume change is associated with phase transformation.
• Change in size is relevant when temperature changes, but there is no phase transformation (e.g. heating, or cooling).
• Energy goes primarily into atomic vibrations (amplitude variations).
• Measured interatomic distance is temperature dependent.

Vibrational Modes

• Vibrational modes are either longitudinal or transverse.
• Longitudinal: vibrations follow the bond direction.
• Transverse: perpendicular to the bond direction.

Change in Size (Fundamentals)

• Balance of forces affects expansion/contraction.
• Minimum energy corresponds to equilibrium lattice constant.
• Vibrational energy represented by horizontal lines (A₁A₂).
• Average interatomic distance is midway between A₁ and A₂ (A₀).

Equilibrium Bond Length at Temperatures

• Equilibrium bond length is at 0K.
• Elevated temperatures cause an increased average bond length.

Coefficient of Thermal Expansion

• Change in length is associated with temperature changes.
• Fractional change in length to change in temperature (α).
• Equations are given for changes in length, and area based on their respective coefficients (α, γ or β).

Negative Thermal Expansion (NTE)

• Some materials contract upon heating rather than expanding.
• Certain physical processes contribute to this behaviour: phase transitions, transverse vibrations, and rigid unit modes.

Transverse Vibrational Modes

• For complex systems (e.g., materials with M-O bonds), there can be contraction in volume based on the transverse vibrational mode.

Rigid Unit Modes

• Characteristics of some substances with strong M-O bonds and relatively short O-O distances.
• Coupled rotations can occur with no distortion of the intrapolyhedral bonding.

Animations of ZrW₂O₈

• Visual demonstrations of the potential structural flexibility of a material.

Change in Volume of Water

• Water shows anomalous behaviour regarding volume changes relative to temperature:
• Contracts upon melting.
• Decreases in volume from 0°C to 4°C.
• Increases in volume from 4°C to 100°C.
• Minimum volume and maximum density at 4°C.

Consequences of Anomalous Water Behaviour

• Water expands upon freezing so ice floats.
• Dense water sinks, while less dense water layers maintain temperature above 4°C.
• This creates thermal stratification that prevents freezing of the entire aquatic system.

Structure of Water (H₂O)

• Hydrogen bonds give water unique properties (high heat of vaporization).
• The open structure of ice makes it less dense than liquid water.

Dry Ice

• Solid carbon dioxide (CO₂).
• Sublimes at -78°C.
• Rapid expansion upon sublimation can form ‘dry ice’

Applications of Thermal Expansion

• Rivets: Heated and hammered to fit their holes creating a tight fit when cooled.
• Thermostats: Expansion/contraction of bimetallic strips trigger switching.

Positive Thermal Expansion

• Uses of materials that expand as temperature increases (e.g. thermostats).
• Examples like bi-metallic strips and temperature control devices.

Negative Thermal Expansion

• Importance in composite materials where overall expansion needs to be adjusted or eliminated to avoid damaging stresses.
• Applications include high precision optical components and mirrors.

Thermal Stresses

• Mechanical stress is induced because structural members are prevented from freely expanding/contracting with temperature changing.
• This occurs when: geometry prevents free movement, external constraints block the motion, or temperature gradients exist.

Test your knowledge of fundamental physics concepts as they relate to medical laboratory devices in this quiz. Topics include heat, electricity, magnetism, and optics, along with their applications in devices like X-ray and magnetic imaging. Perfect for students in the 1st level summer course.