Procedure Text and Technical Instructions – Materi & Latihan TKA Bahasa Inggris SMA/MA

1. Objective: To freeze and cryopreserve human CD34+ hematopoietic stem cells (HSCs) at liquid nitrogen temperatures (-196°C) while maintaining post-thaw cellular viability above 85%.

2. Reagents and Equipment: Controlled-rate programmable freezer; sterile cryovials; dimethyl sulfoxide (DMSO) cryoprotectant (USP grade); heat-inactivated fetal bovine serum (FBS); sterile laminar flow biosafety cabinet; personal protective cryogenic gloves and face shield.

3. Procedural Steps:
- Step 1: Centrifuge the isolated HSC cell suspension at 300 × g for 10 minutes at 4°C. Gently decant the supernatant, leaving the pelleted cells undisturbed.
- Step 2: Prepare the freezing medium by combining 80% FBS, 10% basal culture medium, and 10% DMSO. **Caution:** Pre-chill the mixture to 4°C prior to cell contact, as DMSO generates exothermic dissolution heat that is cytotoxic at ambient room temperatures.
- Step 3: Resuspend the cell pellet in the chilled freezing medium dropwise over three minutes, achieving a target concentration of 5 × 10^6 cells per milliliter. Immediately transfer 1.0 mL aliquots into sterile labeled cryovials.
- Step 4: Transfer cryovials into a controlled-rate freezer executing a cooling gradient of exactly -1°C per minute until reaching -80°C. *Note:* Fast uncontrolled freezing forms intracellular ice crystals that rupture cellular membranes, while excessively slow cooling induces severe osmotic cell shrinkage.
- Step 5: Upon reaching -80°C, rapidly transfer the cryovials into the vapor phase of a liquid nitrogen storage tank (-150°C to -196°C) for long-term archiving.

1. Objective: To freeze and cryopreserve human CD34+ hematopoietic stem cells (HSCs) at liquid nitrogen temperatures (-196°C) while maintaining post-thaw cellular viability above 85%.

2. Reagents and Equipment: Controlled-rate programmable freezer; sterile cryovials; dimethyl sulfoxide (DMSO) cryoprotectant (USP grade); heat-inactivated fetal bovine serum (FBS); sterile laminar flow biosafety cabinet; personal protective cryogenic gloves and face shield.

3. Procedural Steps:
- Step 1: Centrifuge the isolated HSC cell suspension at 300 × g for 10 minutes at 4°C. Gently decant the supernatant, leaving the pelleted cells undisturbed.
- Step 2: Prepare the freezing medium by combining 80% FBS, 10% basal culture medium, and 10% DMSO. **Caution:** Pre-chill the mixture to 4°C prior to cell contact, as DMSO generates exothermic dissolution heat that is cytotoxic at ambient room temperatures.
- Step 3: Resuspend the cell pellet in the chilled freezing medium dropwise over three minutes, achieving a target concentration of 5 × 10^6 cells per milliliter. Immediately transfer 1.0 mL aliquots into sterile labeled cryovials.
- Step 4: Transfer cryovials into a controlled-rate freezer executing a cooling gradient of exactly -1°C per minute until reaching -80°C. *Note:* Fast uncontrolled freezing forms intracellular ice crystals that rupture cellular membranes, while excessively slow cooling induces severe osmotic cell shrinkage.
- Step 5: Upon reaching -80°C, rapidly transfer the cryovials into the vapor phase of a liquid nitrogen storage tank (-150°C to -196°C) for long-term archiving.

1. Objective: To freeze and cryopreserve human CD34+ hematopoietic stem cells (HSCs) at liquid nitrogen temperatures (-196°C) while maintaining post-thaw cellular viability above 85%.

2. Reagents and Equipment: Controlled-rate programmable freezer; sterile cryovials; dimethyl sulfoxide (DMSO) cryoprotectant (USP grade); heat-inactivated fetal bovine serum (FBS); sterile laminar flow biosafety cabinet; personal protective cryogenic gloves and face shield.

3. Procedural Steps:
- Step 1: Centrifuge the isolated HSC cell suspension at 300 × g for 10 minutes at 4°C. Gently decant the supernatant, leaving the pelleted cells undisturbed.
- Step 2: Prepare the freezing medium by combining 80% FBS, 10% basal culture medium, and 10% DMSO. **Caution:** Pre-chill the mixture to 4°C prior to cell contact, as DMSO generates exothermic dissolution heat that is cytotoxic at ambient room temperatures.
- Step 3: Resuspend the cell pellet in the chilled freezing medium dropwise over three minutes, achieving a target concentration of 5 × 10^6 cells per milliliter. Immediately transfer 1.0 mL aliquots into sterile labeled cryovials.
- Step 4: Transfer cryovials into a controlled-rate freezer executing a cooling gradient of exactly -1°C per minute until reaching -80°C. *Note:* Fast uncontrolled freezing forms intracellular ice crystals that rupture cellular membranes, while excessively slow cooling induces severe osmotic cell shrinkage.
- Step 5: Upon reaching -80°C, rapidly transfer the cryovials into the vapor phase of a liquid nitrogen storage tank (-150°C to -196°C) for long-term archiving.

1. Purpose: Synthesis of continuous, high-mobility monolayer graphene on high-purity copper (Cu) foil substrates utilizing atmospheric-pressure chemical vapor deposition (APCVD).

2. Substrate Preparation and Tube Evacuation:
- Place a 25-micron-thick polycrystalline Cu foil into a 50% glacial acetic acid bath for 10 minutes to remove surface copper oxide (CuO). Rinse thoroughly with deionized water and dry using compressed nitrogen (99.999% purity).
- Insert the Cu foil into the isothermal hot zone of a horizontal quartz tube furnace. Seal the flanges and evacuate the chamber to a base vacuum below 10^-3 Torr using a turbomolecular pump to eliminate ambient atmospheric oxygen.

3. Thermal Annealing and Carbon Synthesis:
- Backfill the quartz tube with ultra-pure argon (Ar) at 500 standard cubic centimeters per minute (sccm) and hydrogen (H2) at 50 sccm until reaching atmospheric pressure. Ramp furnace temperature to 1,035°C at a rate of 20°C per minute.
- Anneal the substrate at 1,035°C for 30 minutes under H2 flow to enlarge copper grain boundaries and suppress surface nucleation defect sites.
- Initiate graphene growth by introducing high-purity methane (CH4) precursor gas at 5 sccm for exactly 15 minutes, maintaining constant furnace temperature.

4. Rapid Cooling and Safety Interlocks:
- Cease CH4 flow immediately at the 15-minute mark. *Critical Hazard:* Do not open the quartz tube furnace while temperature exceeds 200°C; exposure of hot hydrogen gas to atmospheric oxygen triggers instantaneous flammable deflagration. Slide the furnace away from the quartz tube to achieve rapid convective cooling (>50°C/min) down to ambient temperature under continuous Ar shielding.

1. Purpose: Synthesis of continuous, high-mobility monolayer graphene on high-purity copper (Cu) foil substrates utilizing atmospheric-pressure chemical vapor deposition (APCVD).

2. Substrate Preparation and Tube Evacuation:
- Place a 25-micron-thick polycrystalline Cu foil into a 50% glacial acetic acid bath for 10 minutes to remove surface copper oxide (CuO). Rinse thoroughly with deionized water and dry using compressed nitrogen (99.999% purity).
- Insert the Cu foil into the isothermal hot zone of a horizontal quartz tube furnace. Seal the flanges and evacuate the chamber to a base vacuum below 10^-3 Torr using a turbomolecular pump to eliminate ambient atmospheric oxygen.

3. Thermal Annealing and Carbon Synthesis:
- Backfill the quartz tube with ultra-pure argon (Ar) at 500 standard cubic centimeters per minute (sccm) and hydrogen (H2) at 50 sccm until reaching atmospheric pressure. Ramp furnace temperature to 1,035°C at a rate of 20°C per minute.
- Anneal the substrate at 1,035°C for 30 minutes under H2 flow to enlarge copper grain boundaries and suppress surface nucleation defect sites.
- Initiate graphene growth by introducing high-purity methane (CH4) precursor gas at 5 sccm for exactly 15 minutes, maintaining constant furnace temperature.

4. Rapid Cooling and Safety Interlocks:
- Cease CH4 flow immediately at the 15-minute mark. *Critical Hazard:* Do not open the quartz tube furnace while temperature exceeds 200°C; exposure of hot hydrogen gas to atmospheric oxygen triggers instantaneous flammable deflagration. Slide the furnace away from the quartz tube to achieve rapid convective cooling (>50°C/min) down to ambient temperature under continuous Ar shielding.

1. Scope: Mandatory emergency response guidelines for responding to Level-2 or Level-3 releases of anhydrous ammonia (NH3) vapor in industrial cold-storage facilities.

2. Initial Alarm and Personal Protection:
- Upon activation of acoustic toxic gas alarms (>25 parts per million [ppm] NH3), all non-emergency personnel must immediately evacuate crosswind and upwind toward designated muster points.
- Designated HAZMAT emergency response technicians must don Level-A fully encapsulating vapor-protective suits with self-contained breathing apparatus (SCBA) operating under positive internal pressure before crossing the exclusion boundary.

3. Source Isolation and Vapor Suppression:
- Deploy wide-angle fog nozzles to establish a high-pressure water curtain around the vapor plume. **Danger:** Never spray water directly onto liquid pools of anhydrous ammonia; liquid ammonia boils violently upon contact with water, drastically accelerating toxic gas vaporization.
- Approach the refrigeration compressor manifold from upwind. Locate emergency shutoff quarter-turn valve V-101. Manually pull the lever 90 degrees clockwise to isolate the high-pressure liquid receiver.
- If valve V-101 is physically distorted or inaccessible due to ice accumulation, activate the pneumatic emergency remote dump switch located outside Bay 4 to divert liquid ammonia into the underground neutralizing water diffusion tank.
- Continue fog water deluge until ambient air monitoring displays NH3 concentrations below the OSHA Permissible Exposure Limit (PEL) of 50 ppm for thirty consecutive minutes.

1. Scope: Mandatory emergency response guidelines for responding to Level-2 or Level-3 releases of anhydrous ammonia (NH3) vapor in industrial cold-storage facilities.

2. Initial Alarm and Personal Protection:
- Upon activation of acoustic toxic gas alarms (>25 parts per million [ppm] NH3), all non-emergency personnel must immediately evacuate crosswind and upwind toward designated muster points.
- Designated HAZMAT emergency response technicians must don Level-A fully encapsulating vapor-protective suits with self-contained breathing apparatus (SCBA) operating under positive internal pressure before crossing the exclusion boundary.

3. Source Isolation and Vapor Suppression:
- Deploy wide-angle fog nozzles to establish a high-pressure water curtain around the vapor plume. **Danger:** Never spray water directly onto liquid pools of anhydrous ammonia; liquid ammonia boils violently upon contact with water, drastically accelerating toxic gas vaporization.
- Approach the refrigeration compressor manifold from upwind. Locate emergency shutoff quarter-turn valve V-101. Manually pull the lever 90 degrees clockwise to isolate the high-pressure liquid receiver.
- If valve V-101 is physically distorted or inaccessible due to ice accumulation, activate the pneumatic emergency remote dump switch located outside Bay 4 to divert liquid ammonia into the underground neutralizing water diffusion tank.
- Continue fog water deluge until ambient air monitoring displays NH3 concentrations below the OSHA Permissible Exposure Limit (PEL) of 50 ppm for thirty consecutive minutes.

1. Scope: Mandatory emergency response guidelines for responding to Level-2 or Level-3 releases of anhydrous ammonia (NH3) vapor in industrial cold-storage facilities.

2. Initial Alarm and Personal Protection:
- Upon activation of acoustic toxic gas alarms (>25 parts per million [ppm] NH3), all non-emergency personnel must immediately evacuate crosswind and upwind toward designated muster points.
- Designated HAZMAT emergency response technicians must don Level-A fully encapsulating vapor-protective suits with self-contained breathing apparatus (SCBA) operating under positive internal pressure before crossing the exclusion boundary.

3. Source Isolation and Vapor Suppression:
- Deploy wide-angle fog nozzles to establish a high-pressure water curtain around the vapor plume. **Danger:** Never spray water directly onto liquid pools of anhydrous ammonia; liquid ammonia boils violently upon contact with water, drastically accelerating toxic gas vaporization.
- Approach the refrigeration compressor manifold from upwind. Locate emergency shutoff quarter-turn valve V-101. Manually pull the lever 90 degrees clockwise to isolate the high-pressure liquid receiver.
- If valve V-101 is physically distorted or inaccessible due to ice accumulation, activate the pneumatic emergency remote dump switch located outside Bay 4 to divert liquid ammonia into the underground neutralizing water diffusion tank.
- Continue fog water deluge until ambient air monitoring displays NH3 concentrations below the OSHA Permissible Exposure Limit (PEL) of 50 ppm for thirty consecutive minutes.

1. Purpose: Synthesis of continuous, high-mobility monolayer graphene on high-purity copper (Cu) foil substrates utilizing atmospheric-pressure chemical vapor deposition (APCVD).

2. Substrate Preparation and Tube Evacuation:
- Place a 25-micron-thick polycrystalline Cu foil into a 50% glacial acetic acid bath for 10 minutes to remove surface copper oxide (CuO). Rinse thoroughly with deionized water and dry using compressed nitrogen (99.999% purity).
- Insert the Cu foil into the isothermal hot zone of a horizontal quartz tube furnace. Seal the flanges and evacuate the chamber to a base vacuum below 10^-3 Torr using a turbomolecular pump to eliminate ambient atmospheric oxygen.

3. Thermal Annealing and Carbon Synthesis:
- Backfill the quartz tube with ultra-pure argon (Ar) at 500 standard cubic centimeters per minute (sccm) and hydrogen (H2) at 50 sccm until reaching atmospheric pressure. Ramp furnace temperature to 1,035°C at a rate of 20°C per minute.
- Anneal the substrate at 1,035°C for 30 minutes under H2 flow to enlarge copper grain boundaries and suppress surface nucleation defect sites.
- Initiate graphene growth by introducing high-purity methane (CH4) precursor gas at 5 sccm for exactly 15 minutes, maintaining constant furnace temperature.

4. Rapid Cooling and Safety Interlocks:
- Cease CH4 flow immediately at the 15-minute mark. *Critical Hazard:* Do not open the quartz tube furnace while temperature exceeds 200°C; exposure of hot hydrogen gas to atmospheric oxygen triggers instantaneous flammable deflagration. Slide the furnace away from the quartz tube to achieve rapid convective cooling (>50°C/min) down to ambient temperature under continuous Ar shielding.

1. Objective: To freeze and cryopreserve human CD34+ hematopoietic stem cells (HSCs) at liquid nitrogen temperatures (-196°C) while maintaining post-thaw cellular viability above 85%.

2. Reagents and Equipment: Controlled-rate programmable freezer; sterile cryovials; dimethyl sulfoxide (DMSO) cryoprotectant (USP grade); heat-inactivated fetal bovine serum (FBS); sterile laminar flow biosafety cabinet; personal protective cryogenic gloves and face shield.

3. Procedural Steps:
- Step 1: Centrifuge the isolated HSC cell suspension at 300 × g for 10 minutes at 4°C. Gently decant the supernatant, leaving the pelleted cells undisturbed.
- Step 2: Prepare the freezing medium by combining 80% FBS, 10% basal culture medium, and 10% DMSO. **Caution:** Pre-chill the mixture to 4°C prior to cell contact, as DMSO generates exothermic dissolution heat that is cytotoxic at ambient room temperatures.
- Step 3: Resuspend the cell pellet in the chilled freezing medium dropwise over three minutes, achieving a target concentration of 5 × 10^6 cells per milliliter. Immediately transfer 1.0 mL aliquots into sterile labeled cryovials.
- Step 4: Transfer cryovials into a controlled-rate freezer executing a cooling gradient of exactly -1°C per minute until reaching -80°C. *Note:* Fast uncontrolled freezing forms intracellular ice crystals that rupture cellular membranes, while excessively slow cooling induces severe osmotic cell shrinkage.
- Step 5: Upon reaching -80°C, rapidly transfer the cryovials into the vapor phase of a liquid nitrogen storage tank (-150°C to -196°C) for long-term archiving.

1. Purpose: Synthesis of continuous, high-mobility monolayer graphene on high-purity copper (Cu) foil substrates utilizing atmospheric-pressure chemical vapor deposition (APCVD).

2. Substrate Preparation and Tube Evacuation:
- Place a 25-micron-thick polycrystalline Cu foil into a 50% glacial acetic acid bath for 10 minutes to remove surface copper oxide (CuO). Rinse thoroughly with deionized water and dry using compressed nitrogen (99.999% purity).
- Insert the Cu foil into the isothermal hot zone of a horizontal quartz tube furnace. Seal the flanges and evacuate the chamber to a base vacuum below 10^-3 Torr using a turbomolecular pump to eliminate ambient atmospheric oxygen.

3. Thermal Annealing and Carbon Synthesis:
- Backfill the quartz tube with ultra-pure argon (Ar) at 500 standard cubic centimeters per minute (sccm) and hydrogen (H2) at 50 sccm until reaching atmospheric pressure. Ramp furnace temperature to 1,035°C at a rate of 20°C per minute.
- Anneal the substrate at 1,035°C for 30 minutes under H2 flow to enlarge copper grain boundaries and suppress surface nucleation defect sites.
- Initiate graphene growth by introducing high-purity methane (CH4) precursor gas at 5 sccm for exactly 15 minutes, maintaining constant furnace temperature.

4. Rapid Cooling and Safety Interlocks:
- Cease CH4 flow immediately at the 15-minute mark. *Critical Hazard:* Do not open the quartz tube furnace while temperature exceeds 200°C; exposure of hot hydrogen gas to atmospheric oxygen triggers instantaneous flammable deflagration. Slide the furnace away from the quartz tube to achieve rapid convective cooling (>50°C/min) down to ambient temperature under continuous Ar shielding.

1. Scope: Mandatory emergency response guidelines for responding to Level-2 or Level-3 releases of anhydrous ammonia (NH3) vapor in industrial cold-storage facilities.

2. Initial Alarm and Personal Protection:
- Upon activation of acoustic toxic gas alarms (>25 parts per million [ppm] NH3), all non-emergency personnel must immediately evacuate crosswind and upwind toward designated muster points.
- Designated HAZMAT emergency response technicians must don Level-A fully encapsulating vapor-protective suits with self-contained breathing apparatus (SCBA) operating under positive internal pressure before crossing the exclusion boundary.

3. Source Isolation and Vapor Suppression:
- Deploy wide-angle fog nozzles to establish a high-pressure water curtain around the vapor plume. **Danger:** Never spray water directly onto liquid pools of anhydrous ammonia; liquid ammonia boils violently upon contact with water, drastically accelerating toxic gas vaporization.
- Approach the refrigeration compressor manifold from upwind. Locate emergency shutoff quarter-turn valve V-101. Manually pull the lever 90 degrees clockwise to isolate the high-pressure liquid receiver.
- If valve V-101 is physically distorted or inaccessible due to ice accumulation, activate the pneumatic emergency remote dump switch located outside Bay 4 to divert liquid ammonia into the underground neutralizing water diffusion tank.
- Continue fog water deluge until ambient air monitoring displays NH3 concentrations below the OSHA Permissible Exposure Limit (PEL) of 50 ppm for thirty consecutive minutes.

1. Purpose: Synthesis of continuous, high-mobility monolayer graphene on high-purity copper (Cu) foil substrates utilizing atmospheric-pressure chemical vapor deposition (APCVD).

2. Substrate Preparation and Tube Evacuation:
- Place a 25-micron-thick polycrystalline Cu foil into a 50% glacial acetic acid bath for 10 minutes to remove surface copper oxide (CuO). Rinse thoroughly with deionized water and dry using compressed nitrogen (99.999% purity).
- Insert the Cu foil into the isothermal hot zone of a horizontal quartz tube furnace. Seal the flanges and evacuate the chamber to a base vacuum below 10^-3 Torr using a turbomolecular pump to eliminate ambient atmospheric oxygen.

3. Thermal Annealing and Carbon Synthesis:
- Backfill the quartz tube with ultra-pure argon (Ar) at 500 standard cubic centimeters per minute (sccm) and hydrogen (H2) at 50 sccm until reaching atmospheric pressure. Ramp furnace temperature to 1,035°C at a rate of 20°C per minute.
- Anneal the substrate at 1,035°C for 30 minutes under H2 flow to enlarge copper grain boundaries and suppress surface nucleation defect sites.
- Initiate graphene growth by introducing high-purity methane (CH4) precursor gas at 5 sccm for exactly 15 minutes, maintaining constant furnace temperature.

4. Rapid Cooling and Safety Interlocks:
- Cease CH4 flow immediately at the 15-minute mark. *Critical Hazard:* Do not open the quartz tube furnace while temperature exceeds 200°C; exposure of hot hydrogen gas to atmospheric oxygen triggers instantaneous flammable deflagration. Slide the furnace away from the quartz tube to achieve rapid convective cooling (>50°C/min) down to ambient temperature under continuous Ar shielding.