ARYA LAB

09/11/2025

A projector microscope is a compound microscope equipped with a projection system that throws the magnified image of the specimen onto a screen for group viewing.

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⚙️ Main Parts
• Light source – Provides illumination (usually halogen or LED).
• Condenser – Focuses light onto the specimen.
• Objective lenses – Magnify the image (usually 10×, 40×, 100×).
• Projection lens/system – Projects the final image onto a screen.
• Stage – Holds the slide/specimen.
• Screen – For image display (inbuilt or external).

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🧪 Uses
• Teaching in schools, colleges, or veterinary labs.
• Demonstrating slides to groups.
• Viewing microorganisms, tissue sections, and other samples together.
• Recording or capturing projected images for reports.

30/10/2025

🔬 What it Is
An autoclave is essentially a heavy-duty pressure chamber designed to achieve temperatures far exceeding the boiling point of water at standard atmospheric pressure. It is considered the most reliable method for sterilization, as it effectively kills all forms of microbial life, including highly resistant bacterial spores.
⚙️ How it Works
The sterilization process relies on the direct relationship between pressure and temperature:
1. Steam Generation: Water is heated within the chamber to produce steam.
2. Pressure Build-up: The chamber is sealed, and the pressure is increased. This higher pressure raises the boiling point of water, allowing the steam to reach sterilization temperatures, typically 121°C (250°F) or 134°C (273°F).
3. Sterilization: The high-temperature pressurized steam rapidly penetrates the materials, transferring immense heat energy. This heat quickly denatures (damages/unfolds) the essential proteins and structures of microorganisms, leading to their death.
4. Holding Time: The materials are held at the required temperature and pressure for a specific duration (e.g., 15–20 minutes) to ensure complete microbial kill.
🏥 Common Uses
Autoclaves are essential in:
• Healthcare: Sterilizing surgical instruments, dressings, and medical waste.
• Laboratories: Sterilizing media, glassware, and reusable equipment in microbiology and research labs.
• Industry: Sterilizing pharmaceuticals and ensuring the safety of certain food products.

02/09/2025

📚 Gram Stain (Gram’s Staining)

🔹 Principle

Gram staining is based on the structural differences in the bacterial cell wall:
• Gram Positive bacteria have a thick peptidoglycan layer, which retains the primary stain (crystal violet).
• Gram Negative bacteria have a thin peptidoglycan layer and an outer lipid membrane, so they lose the primary stain and take up the counterstain (safranin).

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🔹 Steps of Gram Staining
1. Primary Stain – Crystal Violet
→ All bacteria appear purple.
2. Mordant – Iodine
→ Forms a crystal violet–iodine complex, fixing the dye.
3. Decolorizer – Alcohol/Acetone
• Gram positive → dye retained (remain purple)
• Gram negative → dye lost (colorless)
4. Counterstain – Safranin (or Fuchsin)
• Gram positive → remain purple/blue
• Gram negative → turn pink/red

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🔹 Results
• Gram Positive bacteria → Purple (e.g., Staphylococcus aureus, Bacillus subtilis)
• Gram Negative bacteria → Pink/Red (e.g., E. coli, Salmonella)

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🔹 Applications
• Differentiation of bacteria (Gram + vs Gram –)
• Important in clinical diagnosis of infections
• Helps in antibiotic selection

02/04/2025

22/07/2024

ARYA LAB

20/05/2023

21/01/2022

🔬🔭

16/10/2021

AFB

17/01/2021

Gram staining?