D5W (5 D/W)
One of the most prevalent of LVPs (also see: LVP (Large Volume
Parenteral)). Five percent dextrose in water. Presence of dextrose presents
significant filtration problems. Usually requires activated charcoal
pretreatment.
Dalton
The unit of molecular weight, equal to the weight of a hydrogen atom.
Data Integrity
The validity of data and their relationships. For electronic records to be
trustworthy and reliable, the links between raw data, metadata, and results
must not be compromised or broken. Without data integrity, it is not
possible to regenerate a previous result reliably.
Data Migration
The process of translating data from one system to another when a company
replaces the current computing systems with a new one. CFR 21 Part 11
mandates that data migration implementation create accurate and complete
copies of the records when they are moved to a new system.
DDC (Direct Digital Control)
A collection of control units (analog and discrete) connected into a data
highway, usually with a host or alarming/recording computer attached.
D Value
The time under a stated set of exposure conditions (temperature in an
autoclave) required to reduce a microbial population by a factor of 90%
(e.g. from 10,000 to 1,000).
Dead Leg
An area of entrapment in a vessel or piping run that could lead to
contamination of the product. In a piping system, a non-flowing pocket, tee,
or extension from a primary piping run that exceeds a defined number of pipe
diameters from the ID of the primary pipe. Denoted by the term L/D or L/A,
where L is equal to the leg extension perpendicular to the normal flow
pattern or direction, A is the annular gap width, and D is equal to the ID
(or inside dimension) of the extension or leg. In some existing standards,
the dimension L is measured from the centerline of the primary pipe. For
bioprocessing systems, an L/D of 2:1 is achievable with today's component
technology for most valving and piping configurations.
Decontamination
A process that reduces contaminating substances to a defined acceptance
level.
Deflagration
An exothermic reaction, such as the extremely rapid oxidation of a
combustible dust or flammable vapor in air, in which the reaction progresses
through the unburned material at a rate less than the velocity of sound. A
deflagration can have an explosive effect.
Degrading
Deterioration of a surface finish so that pieces of the finish (or
substrate) material large enough to be visible to the unaided eye, dislodge
without any direct physical contact and fall from the surface of the
material.
Deionization
Removing dissolved ions from solution by passing the solution through a bed
of ion exchange resin, consisting of polymer beads that exchange hydrogen
ions for cations and hydroxyl ions for anions in solution. The ionic
impurities remain bound to the resins and the hydrogen and hydroxyl ions
combine with each other to form water.
Deletion Map
A description of a specific chromosome that uses defined mutations -
specific deleted areas in the genome - as "biochemical signposts",
or markers for specific areas.
De Minimis Release
The release of viable microbiological agents or eukaryotic cells that does
not result in the establishment of disease in healthy people, plants, or
animals; or in uncontrolled proliferation of any microbiological agents or
eukaryotic cells.
Dementia
Severe impairment of mental functioning.
Demineralization
Sometimes used interchangeably with deionization, it refers to the removal
of minerals and mineral salts using ion exchange. Water softening is a
common form of demineralization.
Denaturation
The loss of the native structure of a macromolecule resulting, from heat
treatment, extreme pH changes, chemical treatment, etc. It is accompanied by
loss of biological activity. For example, proteins may be denatured by heat,
pH extremes, or addition of agents such as urea or guanidinium
hydrochloride.
Dent
A typical stainless steel interior surface anomaly that refers to a large,
smooth-bottomed depression whose diameter or width is greater than its depth
and which will not produce an indication.
Deoxyribonucleotide
Depyrogenation
The removal or destruction of endotoxins.
Desalination
The removal of dissolved salts from brine to produce potable water.
Design Condition
The specified range or accuracy of a controlled variable used by the
designer to determine performance requirements of an engineered system.
Design Specification
A specification that defines the design of a system or system component.
Desiccant
Chemical salt used to dehumidify air, to control moisture in materials
contacting that air.
Desiccators
Closed containers, usually made of glass or plastic, with an airtight seal
used for drying materials.
Detonation
An exothermic reaction characterized by the presence of a shock wave in a
material that establishes and maintains the reaction. The reaction zone
progresses through the material at a rate greater than the velocity of
sound. The principal heating mechanism is one of shock compression.
Detonations have an explosive effect.
Deuteromycetes
Molds that cannot reproduce by sexual means. Some pathogenic fungi such as
Trichophyton, which causes athlete's foot, belong to this family.
DHL Vaccine
A tri-valent vaccine. Also, the most common veterinary vaccine that has a
combination of viral and bacterial vaccines. Used for distemper, hepatitis
(canine), and leptospira.
Diagnostic
A substance or group of substances used to identify a disease by analyzing
the cause and symptoms.
Dialysis
The separation of low-molecular weight compounds from high molecular weight
components by diffusion through a semipermeable membrane. Frequently
utilized to remove salts, introduce salts, remove biological effectors such
as nicotinamide adenine dinucleotides, nucleotides phosphates, etc. from
polymeric molecules such as protein, DNA, RNA, etc. Commonly used membranes
have a molecular weight cutoff around 10,000 but other membrane pore sizes
are available.
Diatom
Any minute, unicellular or colonial algae of the class Bacillariophyceae
having siliceous cells walls consisting of two overlapping symmetrical
parts.
Diatomaceous Earth, Diatomite, Kiselguhr (DE)
Fine silicaceous powder used as a filter aid.
Diffusion
The random thermal motion of particles, which causes them to flow from a
region of higher concentration to one of lower concentration until they are
uniformly distributed.
Digestion
The enzymatic hydrolysis of major nutrients in the gastrointestinal system
to yield their building-block components.
Digital
A series of on and off pulses arranged to convey information.
Digital Certificate
An attachment to an electronic message used for security purposes. The most
common use of a digital certificate is to verify that a user sending a
message is who he or she claims to be and to provide the receiver with the
means to encode a reply.
Digital Representation
Biometric parameters such as a fingerprint or retinal pattern are turned
into data that a computer understands: the digital representation of the
biometric. The pattern in the biometric divides it into a grid of boxes, and
a zero or a one, depending on whether the box is filled in, marks each box.
Digital Signature
An electronic signature based upon cryptographic methods of originator
authentication, computed by using a set of rules and a set of parameters
such that the identity of the signer and the integrity of the data can be
verified.
Dilution
Lowering the concentration of a solution by adding more solvent.
Dilution Factor
The ratio of solvent to solute by volume.
Diploid
A full set of genetic material, consisting of paired chromosomes one
chromosome from each parental set. Most animal cells except the gametes have
a diploid set of chromosomes. The diploid human genome has 46 chromosomes.
Diplophase
A phase in the life cycle of an organism where the organism has two copies
of each gene. The organism is said to be diploid.
Direct Impact System
An engineering system that may have a direct impact on product quality.
Disaster
Any event (i.e. fire, earthquake, power failure etc.), which could have a
detrimental effect upon an automated system or its associated information.
Discoloration (welding)
Any change in surface color from that of the base metal. Usually associated
with oxidation occurring on the weld and heat affected zone (HAZ) on the
outside diameter and inside diameter of the weld joint as a result of
heating the metal during the welding. Colors may range from pale bluish-gray
to deep blue, and from pale straw color to a black crusty coating.
Disinfection
Process by which viable microbiological agents or eukaryotic cells are
reduced to a level unlikely to produce disease in healthy people, plants, or
animals. These processes may use chemical agents, heat, ultraviolet light,
etc. to destroy most (but not necessarily all) of the harmful or
objectionable microorganisms, pathogens, and potential pathogens.
Disinfection does not necessarily result in sterilization.
- 1. "High level disinfection" inactivates fungi, viruses,
and bacteria. High-level chemical disinfectants maybe ineffective
against bacterial spores if they are present in large numbers. Extended
exposure times may be required.
- 2. "Intermediate level disinfection" destroys fungi, some
viruses (lipid and most non-lipid medium-size and small viruses),
mycobacteria, and bacteria.
- 3. "Low level disinfection" kills vegetative forms of
bacteria, some fungi, and some medium-size and lipid-containing viruses.
Low-level disinfectants do not reliably kill bacterial spores,
mycobacteria, or small or non-lipid viruses.
- Dispensing
The pouring or transferring of any material from a container, tank or
similar vessel, whereby vapors, dusts, fumes, mists or gases may be
liberated to the atmosphere.
Dissimilation
The breakdown of food material to yield energy and building blocks for
cellular synthesis.
Dissolved Solids
The amount of nonvolatile matter dissolved in a water sample, usually
expressed in parts per million (PPM) by weight.
Distillation
The process of separating water from impurities by heating until it
changes into vapor and then cooling the vapor to condense it into purified
water.
DNA (Deoxyribonucleic Acid)
The molecule of which the genetic material is composed. It consists of
two chains joined together as a double helix. Each chain is composed of a
polymer of nucleotides (consisting of a nitrogenous base, a
deoxyribosesugar ring, and a phosphate group) joined together by
phosphodiester bonds between the 5'-phosphate of one nucleotide and the
3'-hydroxyl of the next. The two chains run in opposite directions and are
held together by hydrogen bonds between the bases in equivalent positions
in the two chains. There are various forms of double helical DNA. They
are:
- 1. B-DNA (first described by Crick and Watson) is a right-handed
helix with 10.6 base pairs per turn and is probably the main form of
cellular DNA.
- 2. A-DNA is also a right-handed helix but is somewhat skewed and
contains about 11 base pairs per turn. It is the form taken By DNA-RNA
hybrid double helixes.
- 3. Z-DNA is a left-handed helix with 11 base pairs per turn. It is
favored by regions rich in guanine cutosine base pairs and probably
occurs infrequently in cellular DNA.