Cleaning, Disinfection, and Sterilization Flashcards
what does the Spaulding classification system do?
Divides medical equipment into 3 categories based on risk?
environmental decontamination plays a role in decreasing
bioburden
what is considered an environmental surface?
non critical items in the SCS and high touch surfaces
what is the level of microbial inactivation for sterilization?
detroys all microrganisms including bacterial spores
what is the level of microbial inactivation for high level disinfection (HLD)?
destroys all microorganisms except high number of bacterial spores
what is the level of microbial inactivation for itnermediate level disinfection?
destroys vegetative bacteria, mycobacteria, most viruses, most fungi but not bacterial spores
what is the level of microbial inactivation for low level disinfection?
destroys vegetative bacteria, some fungi and viruses but not mycobacteria or bacterial spores
what are 3 methods of sterilization?
- high temperature
- low temperature
- liquid immersion
what are 2 methods of HLD?
- heat automated
- liquid immersion
____ _____ is the method of intermediate level and low level disinfection
liquid contact
low level disinfection would be used for what?
cleaning non critical patient care items with no blood
intermediate level disinfection would be used for what?
cleaning non critical patient care items with visible blood
an example of heat automated HLD is
pasteurization (for respirator equipment)
an example of equipmentthat uses liquid immersion HLD is
heat sensitive semicritical items (endoscopes, bronchoscpoes, endocavitary probes)
high temp sterilization would be used for what
heat tolerant critical and semi critical items (surgical tools)
low temp sterilization would be used for what?
heat sensitive critical and semi critical items
liquid immersion sterilization would be used for what?
heat sensitive critical and semi critical items that can be immersed
what are examples of low temp sterilization?
-ethylene oxide gas
-hydrogen peroxide gas plasma
-ozone
-hydrogen peroxide vapor
cleaning instruments after use reduces
spillage and aerosolizing of contaminants
Instruments should be kept ____ after the removal of contamination and before transport
moist
how can instruments be kept moist before transport?
-special containers
-pre treatment product
-towels moistened with water
instruments used in the ER that undergo sterile processing should be immediately sprayed with what?
an enzymatic cleaner
True or false. ER tools should not be cleaned throughout the procedure.
False. Clean them so bioburden doesn’t adhere
what is the most important step in the reusable medical equipment process?
cleaning and rinsing
contaminated items should be transported in what
-closable, puncture resistant, leak proof container marked biohazardous. Adhere to standard precautions.
what are 2 components to manual instrument cleaning?
friction and fluidics
fluidics is used for
removing soil and debris from inner channels after brushing and when the design does not allow for the passage of a brush through a channel
why does fluidics happen under what?
to prevent aerosolization
Mechanical units for instrument cleaning include
ultrasonic cleaners or washer disinfectors
how does ultrasonic cleaning remove soil?
by cavitation and implosion where waves of acoustic energy are propagated in acqueous solutions to disrupt the bonds that hold particulate matter to surfaces
with what cleaning unit can the cleaning fluid result in endotoxin contamination of surgical instruments that could cause severe inflammatory reactions?
ultrasonic cleaners
where are ultrasonic cleaners used?
-dentist office
-hospitals
-ambulatory care
describe washer decontaminators/disinfectors?
they act like a dish washer that uses water circulation and detergents to remove soil. . Sometimes subject instruments to heat (93C for 10 mins)
describe washer sterilizers
modified steam sterilizers that clean by filling the chamber with water and detergent through which steam is passed for agitation. Instruments are then rinsed and subjected to a short steam sterilization cycle.
Which cleaning unit is used for respiratory therapy equipment?
washer pasteurizers
items must be sterile when they enter what body areas
-stertile tissue
-bone
-the vascular system
True or false. Sterile items do not need to be purhcased as sterile p
False
critical instruments include
-surgical instruments
-urinary and cardiac catheters
-implants
-ultrasound probes that enter sterile body cavities
what is the preferred method of sterilization?
steam sterilization
what is a limitation of chemical sterilants?
Can’t be wrapped during processing which creates a challenge for maintaining sterility after processing and during storage
Do devices requrie rinsing after chemical sterilants?
yes with either sterile or filterered water
When should chemical sterilants be used?
for devices that are heat sensitive and incompatible with other sterilization methods.
what are examples of semicritical itesm
GI endoscopes, bronchoscopes, laryngoscopes, esophageal manometry probes, infrared coagulation devices, diaphragm fitting rings
true or false. Intact mucous membranes (those of the lungs and GI tract) are generally resistant to infection by common bacterial spores.
True
semi critical items minimally require what?
HLD with chemical disinfectants
What are some examples of high level disinfectants?
-Glutareldahyde
-hydrogen peroxide
-ortho-phthaladehyde
-improved hydrogen peroxide
-peracetic acid with hydrogen peroxide
-chlorine based products
How often should areas that do reprocessing be audited?
at least annually
non critical items can be divided into which 2 categories?
- non critical patient care equipment
- noncritical environmental surfaces
what are some advantages of local reprocessing?
-faster turnaround
-less instrument loss
-lower instrument inventory
what are biofilms?
microbial massess attached to surfaces immersed in liquids
What mechanisms do biofilms use to become resistant?
-high resistance of older biofilms
-genotypic variation of the bacteria
-microbial production of neutralizing enzymes
-physiologic gradients within the biofilm (i.e., pH)
biofilms are how many times more resistant than the same bacteria in suspension?
1000x
where have biofilms been found?
-whirpools
-dental unit waterlines
-pacemakers
-contact lenses
-urinary catheters
what causes TASS?
substances that enter the eye during surgery and breaches in disinfection and sterilization
-detergent residues, salt solutions, antiseptic agents, talc from gloves, impurities of autoclave steam, heat stable endotoxin
70% of cervical cancers are attributed to what HPV strans?
16 and 18
when is special prion reprocessing required?
when crticical and semi critical devices are contaminated wth high risk tissue (brain, spinal cord, eye) from a patient known or suspected with CJD
why do you want to maintain a moist environment with CJD at the point of use?
so the protein and prion amyloid can’t attach to the stainless steel surface
Define sterile or sterility
state of being free from all microorganisms. Usually a probability function.
Define sterility assurance level (SAL)
The probability of a single viable micoorganism occuring on a product after sterilization. It is an estimate of lethality of the entire sterilization process.
What process is defined as the process of preventing contact with microbes?
Asepsis
What is aseptic technique?
The process of carrying out activities that will maintain objects are areas free of microbes to the greatest extent possible.
Who developed the first presure steam sterilizer (autoclave)?
Charles Chamberland in 1876
Why is dry heat sterilization rarely used?
because of lengthly exposure times
True or false. Steam leaves behind chemical residues and byproducts
False
Subjecting items to the thermal energy from moist heat (steam) can be defined as
high temperature sterilization
What is the most important step in sterilization?
cleanining
What is the basic principle of steam sterilization?
expose each item to the steam contact at the required temperature and pressure for the specified time/
What are the 4 parameters of steam sterilization?
- Steam (moisture)
- Time
- Temperature
- Pressure
What are the 2 main types of steam sterilizers?
- dynamic air removal sterilizer
- gravity displacement sterilizer
most hospitals use what type of steam sterilizers?
jacketed
describe the anatomy of steam sterilizers
steam is applied through a main steam line, these units themselves do not generate steam. chamber walls will be heated by the steam in the jacket.
What are some components of a steam sterilizer?
-door
-gasket
-chamber drain
-thermostatic trap
What is the weakest part of a steam sterilizer?
the door
What is the role of a gasket in a steam sterilizer?
creates a tight seal so steam cannot escape
where is the chamber drain located in a steam sterilizer?
the front or center of the floor
what is the function of a thermostatic trap in a steam sterilizer?
allow air and water (condensate) to escape from the chamber. remove the condensate while preventing the passage of dry steam. they are usually temperature sensitive valves that close when heated past a certain set point.
what is the temperature of a gravity displacement steam sterilizer?
250F
which requires a lower temp gravity displacement or dynamic air removal?
gravity displacement
describe how a gravity displacement steam sterilizer works
steam is admitted at the top or sides of the sterilizing chamber and (because steam is lighter than air) forces air out the bottom of the chamber through the drain vent. Require more exposure time because air removal is more passive in nature.
What is the temperature of dynamic air removal sterilizers?
270-275F
What is an advantage of dynamic air removal sterilizers?
uses a vacuum pump so there is nearly instantaneous steam penetration even into porous loads
Describe the process of dynamic air removal sterilizers
aHigh-speed pre vacuum sterilizer. vacuum pump (or ejector) ensures air removal from the sterilizing chamber and load before the steam is admitted.
How do steam flush pressure pule sterilizers work?
removes air rapidly by repeatedly alternating steam flush and a pressure pulse above atmospheric pressure. Air is rapidly removed from the load as with the prevacuum sterilizer, but air leaks do not affect this process because the steam in the sterilizer is always above atmospheric pressure.
Which time of sterilization use to be referred to as flash?
immediate use
when would IUSS be used?
in an emergent situation like during a surgery and it has to be cleaned. A one of a kind instrument with no other way to clean it
the time required for flash sterilization depends on what?
the type of sterilizer and type of item (i.e., pourous or non-pourous)
Where would flash sterilizaton occur?
in a gravity displacement sterilizer
why is flash sterilization not recommended as a routine sterilization method?
-lack of biological indicators
-absence of protective packaging following sterilization
-possibility of contamination during transport
-sterilization cycle parameters are minimal
True or false. IUSS items can be stored for a later time?
False. They must be used immediately
True or false. One problem with IUSS is items are too hot to use right away?
True
When is low temp sterilization used?
unique devices with complex designs and/or those made of heat or moisture sensitive materials including fiber optics, polymers on cameras, flexible scopes, and certain plastics.
What are the cycle parameters for ETO?
-time
-temp
-concentration
-relative humidity
what are some fast facts about ETO?
-long chemical exposure time
-aeration needed after sterilization
-carcinogenic and mutagenic to humans’-penetrates well due to light molecular weight
-powerful alkylating agent
What are the cycle parameters for hydrogen gas plasma?
-time
-temp
-concentration
-plasma
-vacuum
What are some fast facts about hydrogen peroxide gas plasma?
reactive and unstable in its liquid state
-powerful oxidizer
-converts safely to H20 and O2
-has material and lumen size limitations
What are the cycle parameters of Ozone?
-time
-temp
-concentration
-relative humidity
What are some fast facts about ozone?
-not widely used
-powerful oxidizer
-converts safely back to O2 after cycle
-material limitations
-small sterilizer chamber size
-long cycle time
what are the cycle parameters of vapor phase hydrgen peroxide?
-time
-temp
-concentration
-relative humidity
What are some fast facts about vapor phase hydrogen peroxide?
-reactive and unstable in its liquid state
-powerful oxidizer
-converts safely to H20 and O2
-has material and lumen size limitation
What are the cycle parameters of liquid chemicals for sterilization?
-time
-temp
-concentration
What are some fast facts about liquid chemicals used for sterilization?
-not effective at penetrating biofilm barriers
-longer exposure times
-after exposure requirements hinder use
-thorough rinsing needed
What is the PEL (permissible exposure limit)?
a legal limit in the US for exposure of an employee to a chemical subtance or physical agent like a high level noise
Define time weighted average
the amount of exposure to a physical or chemical agent over a work shift (usually around 8 hours)
Which method of low temp sterilization is TOXIC AF?
ethylene oxide
why is ETO clasified as a toxic gas by OSHA?
carcinogen and reproductive hazard
Describe the ETO cycle
-ETO is provided in inidivudal dose cartridges that get placed inside the chamber
-2.5 hours not including aeration cycle
-items go through aeration which takes 8-12 hours to ensure ETO residue is removed
What are the ETO stages (hint there are 5)
- preconditioning and humidifcation
- gas introduction
- exposure
- evacuation
- aeration
describe alkylation
the replacement of a hydrogen atom with an alkyl group within cells prevents cellular metabolism and replication
describe the microbiocidal activity of ETO
-alkylation of protein, DNA, and RNA
-inactivates all microorganisms although bacterial spores (B. atrophaeus) are more resistant.
-B atrophaeous is the recommended BI or B thermophilus
describe the safety of ETO
-colorless gas
-flammable and expensive
-OSHA regulates acceptable ETO levels (1ppm average hours) due to health hazards
-acute exposure may result in irritation and CNS depression
-hematologic changes and increased risk of spontaenous abortions and cancer
What has chronic inhalation of ETO been linked to?
-formation of cataracts
-cognitive impairment
-neurologic dysfunction
-disabling polyneuropathies
___ ___ have been referred to as the fourth state of matter
Gas plasmas
what hydrogen peroxide solution range do gas plasmas use?
59-95%
why is hydrogen peroxide gas plasma popular?
-safer
-rapid cycle times
-faster turnaround time for medical devices
Describe the hydrgogen perxoide gas plasma low temp sterilization process
-gas plasmas are generated in an enclosed chamber under deep vacuum radio frequency or microwave energy to excite the gas molecules and produce charged particles many of which are in the form of free radicals.
-the sterilization chamber is evacuated and hydrogen peroxide solution is injected from a casette and vaproization to a concentration of 6mg/l. the hydrogen peroxide vapor diffuses through the chamber (50 mins) exposes all surfaces to steriliant and kills microorganisms.
Describe the bi-product of hydrogen peroxide gas plasma
-water, vapor and oxygen
-non toxic
-no need for aeration
-sterilized materials can be handled safety for immediate use or storage
What are examples of instruments that use hydrogen peroxide gas plasma
-single channel flexible endoscopes
-cameras
-rigid endoscopes
-light cords
-batteries
-power drills
what is hydrogen peroxide gas plasma not compatible with?
-liquids and powders
-any material that absorbs liquids
-items that contain cellulose (gauze, towels, cotton, paper or linen)
what may cause a hydrogen peroxide gas plasma cycle to abort?
excess moisture remaining on devices
Which low temp sterilization method is not FDA cleared?
VHP
True or false. VHP has less penetration capabilities than ETO?
True
What temp does ozone sterilization occur at?
97C
microbial efficacy has been demonstrated for ozone by achieving what?
a SAL of 10-6 (including the most resistant microorganism geobacillus stearothermaphilus)
describe the ozone sterilization process
the sterilizer creates its own sterilant internally from USP grade ozygen, steam quality water, and electrocity. The sterilant is converted back to oxygen and water vapor at the end of the cycle by a passing through a catalyst before being exhausted into the room.
When was ozone FDA approved?
2003
the destruction of pathgoenic microorganisms usually be physical or chemical means is defined as
disinfection
Define parametric release
Declaration by medical device manufactuerers that a product is sterile on the basis of chemical or physical process data after validating the cycle using BIs
Define event related sterility
concept that items are considered sterile unless the integrity of the packaging is compromised. Shelf life is indefinite.
Which liquid oxidizing agent is used in automated endoscope reprocessors?
peracetic acid
Items processed with this agent need to be used immediately because they are wet and cannot be packaged and stored for later use.
paracetic acid
What is a physical monitor?
a visible monitor (time, temp, printouts, gauges, pressure recorders) that enables the operator to determine if sterilizing parameters were met.
____ _____ can be defined as part of the CI labeling that provides a value or values of a critical variable at which the indiciator is designed to reach its end point as defined by the manufacturer
stated value
What are the 8 areas of sterile processing?
- point of use/transport
- physical environment of the sterile processing area
- decontamination
- preparation and packaging
- sterilization
- quality control
7 record keeping - storage
What is the goal of physical environment of the sterile processing area?
prevent environmental conditions that encourage microbial growth and cross contamination.
-ensure airflow from lower to higher contamination
-air exchagne frequency
-control temp and humidity
-good lighting
what is the goal of decontamination?
protect workers from contamination with infectious materials
-air pressure should be negative with 10 air exchanges per hour.
When manual cleaning during decontamination what should you document?
temp of the cleaning solution and soaking time
what are the proper environmental conditions for decontamination?
30-60 for humidity (less than 70%)
A device used to monitor the presence of one or more predefined process parameters required for a satisfactory sterilization process is known as
a chemical indicator
define aeration
a processing step using warm circulating air to enhance the removal of a chemical sterilization agent residue from processed items and wrapping material
which sterile processing steps renders the item safe for handling?
decontamination
which chemical that is used to sterile heat or moisture sensitive items is also used as a fumigant?
ETO
what are some physical storage requirement for sterilized items?
-8 to 10 inches from the floor
-18 inches from the ceiling if there is a sprinkler
-at least 2 inches from an outside vent
-away from sprinklers
-in areas of limited traffic
-airflow must be POSITIVE pressure
-open rack storage should have a solid bottom
-position packages so they cannot be bent, damaged, or punctured
-store heavy trays/containers on middle shelves but not stacked
define decontamination
the use of physical or chemical methods to remove, inactivate, or destroy bloodborne pathogens, rendering them no longer able to transmit infectious particiles and rendering them safe for handling.
define biological indicator
the device contains a viable population of highly resistant bacterial spores that are resitsant to the type or method of sterilization being monitored.
SP requires _____ airflow while decontamination requires ____ airlow
positive; negative
define positive airlofw
pushes air out of the work area into adjacent hallways
airflow should be ___ with ___ air exchanges per hour in SP
downdraft; 10
why should linen be in its own enclosed space in SP?
to reduce the accumulation of lint
how should devices be packaged?
-opened
-unlocked
-dissambled
-dry
True or false. Items like basins should be inverted so moisture does not accumulate during sterilization
true
can peel pouches be placed inside of sets or trays?
no because this could interfere with sterilization and drying
instrument sets should weigh no more than?
25 pounds
packing materials can be
-textile wraps (woven or non woven)
-peel pouches
-rigid containers (metal or plastic)
wrapping products may be
-single use
-disposable (no woven)
-reusable (woven textile)
when are peel pouches the preferred packaging method?
-when visibility of the item is important or when sterilizing one or more item
why are tip guards or foam sleeves placed over sharp points?
to prevent damage to the instrument and prevent puncture of the packaging
peel pouches are specific for what?
the type of sterilant used
true or false. Peel pouches can be stapled and air does not have to be forced out of the package before sealing
false
how is sealing done with peel pouches?
heat or self-sealing adhesives
true or false. You can write with permanent marker on the plastic side of a peel pouch?
True
is double peel pouching an acceptable practice?
no unless the peel pouch used has been validated for that
how many air exchanges per hour are require in sterile storage?
4; downdraft
negative airflow is required in which sterile work areas?
-soiled/decontamiation
-sterilizer equipment access rooms
sterile storage humidity is
70
which SP work area has an ideal humidity of 30-50
assembly and prep pack areas
what are some sterilization parameters examples
-temperature
-exposure time
-pressure
-vacuum levels
-moisture conditions or relative humidity
-chemical concentrations
-adequate air removal
How often should Bowie dick testing be done?
daily
when should Bowie dick testing be done?
-before the first processed load
-in each dynamic air removal steam sterilizer in all locations in the facility to detect air leaks, inadequate air removal, inadequate steam penetration, and the presence of noncondensable gases
a device that monitors the presence of one or more of the parameters of effective sterilization or monitors the sterilization equipment is called what
a chemical indicator
Does a pass CI response indicate that the item is sterile?
no
sterilization failures could result from what?
-incorrect packaging
-incorrect loading of the sterilizer
-malfunctions of the sterilzer
what are external CIs used for?
exposure control to determine if the item was processed
when should external CIs be read?
when unloading the sterilizer, dispensing or issuing the item for use, and before the item is opened in the OR
true or false. BIs can be replaced by the use of class 5 and 6 CIs
False
Which BIs are used to monitor EO and dry heat sterilization processes?
bacillus atrophaeues
Geobacillus stearothermphilus spores are used to montior which sterilization processes?
-steam
-hydrogen peroxide with or without gas plasma
-ozone sterilization
BI monitoring is not required for what?
liquid paracetic acid processor (spore strip containing G. steaothermophilus is available)
what is a process challenge device?
an item designed to create a challenge to the sterilization process and used for routine and qualification testing of sterilizers. AKA test pack
how are implant loads monitor
with a BI PCD
AAMI ST79 addresses recalls in what section?
10
when are recalls not needed?
if the cause of failure is immediately identifiable, usually the result of operator error and confined to one load
for documentation/record keeping, each item or package is labelled with what?
-lot control identifier (sterilizer identification number or code, date of sterilization, cycle number).
the storage area should be what temp and humidity?
24C (75F) and not exceed 70% humidity
can you use outside shipping containers as storage for sterile instruments?
No
True or false. Close or coovered cabinets are preferred for SP storage but open shelving may be used if there is limited access, monitored ventilation and frequent cleaning and disinfection
True
shelf life is considered
event related
define event related sterility
items are consideed sterile unless the integrity of the packaging is comprimised
what are some conditions that affect event related sterility?
-environmental sources of contamination
-barrier properties of packaging material
-storage and distribution practices (shelving)
-inventory control
-frequency of handling between distribution and user
what are the 4 steps in steam sterilizer cycles
- conditioning
- exposure
- exhaust
- drying
which requires a lower temp. Gravity displacement or dynamic air removal?
gravity displacement
what is an advantage of a vacuum pump (ie dynamic air removal)
nearly instant steam penetration even in porous loads
what are the 6 classes of chemical indicators? (according to AAMI ST79, ST41, and ST58)
Class 1 (process indicators)
Class 2 (bowdie-dick tests)
Class 3 (single-variable indicators)
Class 4 (multivariable indicators)
Class 5 (integrating indicators)
class 6 (emulating indicators)
______ spores are used to monitor EO and dry heat sterilization processes. _______ spores are used to monitor steam sterilization, hydrogen peroxide with or without gas plasma, and ozone sterilization processes
bacillus atrophaeus; geobacillus stearothermophilus
what is the difference between washer disinfectors and washer decontaminators?
washer decontaminators can also have a heat process
what are washer sterilizers?
modified steam sterilizers that have rotating arms for a wash cycle following by a steam sterilization cycle (285F)
what pH is best for cleaning solutions?
neutral to near neutral
what do alkaline based cleaning solutions do?
dissolve fat and protein residues but are corrosive
what enzymes can be added to neutral pH solutions?
proteases
lipase enzymes act on what
fats
amylase enzymes act on what
starches
neutral pH + enzymes=
compatible with metals, other materials, and are the best choice for cleaning delicate matrial like flexible endoscopes
what are 10 examples of liquid disinfecants?
QPOP: quats, phenolics, peracetic acid, ortho-phythaladehyde
The Hydes: formaldehyde and Glutaraldehyde
HPAC: hydrogen perxoide, alcohols, chlorine
Iodophors
what is the contact time of glut and OPA?
10-90 min 2% glut; 12 min with 0.55% OPA
chlorine based products and phenolics are not safe for what population?
Babies
which low level disinfectants have a 1 min exposure time?
chlorine based products, phenolics, improved hydrogen peroxide, quat ammonium
what is the processing time for steam?
40 mins 250-272F
what is the processing time for dry heat?
1-6 hours depending on temp
what is the ETO processing time?
15 hours twmp 67-147F
wht is the hydrogen peroxide gas plasma processing time?
28-52 minutes
what is the hydrogen peroxide vapor processing time?
55 mins
what is the ozone processing time?
4 hours
what are some characteristics of UV irradiation?
-an emerging technology
-less effective against bacterial spores
-limited mainly to detruction of airborne organisms and inactivation of microorganisms on surfaces
what are some no touch methods for decontamination?
-UV or hydrogen peroxide
-they supplement but do not replace standard cleaning or disinfection because physical cleaning is required first
what are some characteristics of HP vaporization/aerosolization?
-takes 4x longer
-effective at eradicating lots of pathogens like MRSA, TB, C. diff, serratia
what are 2 methods to determine is cleaning and disinfection has been completed effectively?
1 observation (direct or indirect)
2 Environmental monitoring
what are 2 methods to respond to gaps/errors discovered with environmental cleaning?
timely feedback
imrpoved education
what are 3 approaches to environmental monitoring?
- culture: OB, collaborate with PH, not routine
- ATP bioluminescence assay: assess cleaning efficacy, used after a special envirionmental surface swab to highlight amd measure residual organic debris
- Fluroescent marking: inexpensive, reliable, and immediate feedback
what are some advantages and disadvatnages of peracetic acid/hydrogen peroxide?
advantage: no activation, odor and irritation not significant
disadvantage: material compatability, skin and eye damage, limited clinical experience
what are some advantages and disadvantages of glutaraldehyde?
advatnage: inexpensive, material compatability
disadvantage: respiratory irration, odor, slow mycobactericidal activity, allergic contact dermatits, coagulates blood
what are some advantages and disadvantages of hydrogen peroxide?
advantage: no activation, no disposal issues, no odor or irrattation, inactivatives cryptosporidium, does not coaguate blood
disadvantage: material compatability; eye damage with contact
what are some advantages and disadvantages of OPA?
advantage: fast acting HLD, no activation or odor, mateiral compability, does not coagulate blood
disadvantage: expense, eye irration, slow sporicde, stains protein gray
