Protection factor/ratio

Different protection factors have been defined. One method is to define it as the ratio of the concentration of a contaminant in the exhaust duct (CJ to the concentration in the breathing zone (C[,) of a person standing in front of the enclosure, for example, a laboratory fume hood ... 

Protection factors based on the ratio of the breathing zone concentration to the concentration inside the enclosure have been defined. Without complete mixing of air inside the enclosure, considerable variations in the concentration are expected. The best evaluation for enclosure concentration without complete mixing is the measurement of the concentration in the exhaust duct. 

Protection Factor The ratio of the concentration outside the personal protective equipment to the concentration inside the personal protective equipment. Measurement site are critical for proper determination (e.g., for a protective mask, the measurement inside the mask would be made at a subject s breathing zone, and the measurements outside the mask would be made in a corresponding zone). 

The frequency of application of sunscreen is guided by the SPF (sun protection factor) of the preparation. This derived value is the ratio of the time of ultraviolet exposure that causes erythema with the sunscreen to the time that causes erythema without the sunscreen. The higher the SPF, the less frequent the needed application of sunscreen. SPFs of available preparations vary from 2 to 50. 

Liver toxicity is a rare side effect of CBZ therapy (Trimble, 1990), although a recent study reported that 9% of children on CBZ had mildly elevated aspartate aminotransferase (Camfield and Camfield, 1985). Higher mean serum total cholesterol (TC) levels, mean low-density lipoprotein level, and mean TC/high-density lipoprotein ratio have been reported in children with epilepsy treated with CBZ, compared with controls (Sozuer et ah, 1997). Conversely, an increase in serum high-density lipoproteins was reported in a smaller sample of patients treated with CBZ, and was therefore interpreted as a possible protective factor against atherosclerosis (Yalcin et ah, 1997). 

Protection Factor (PF) The ratio of contaminant concentration outside of the respirator facepiece to that inside. It is taken as an indication of fit. PF values are established by manufacturers for specific types of respirators and are indicators only. Actual protection will depend on how a specific respirator fits a specific individual. Refer also to Fit Factor. 

The sun protection factor (SPF) of a given sunscreen is a measure of its effectiveness in absorbing erythrogenic ultraviolet light. It is determined by measuring the minimal erythema dose with and without the sunscreen in a group of normal people. The ratio of the minimal erythema dose with sunscreen to the minimal erythema dose without sunscreen is the SPF. Fair-skinned individuals who sunburn easily are advised to use a product with an SPF of 15 or greater. 

The exposure to effect-level concentration ratio for AS yields a protection factor of >27 for C14AS. Because of the rapid AS biodegradation observed in natural water and toxicity amelioration or attenuation resulting from sorption to solids, this safety factor is expected to be conservative. Additional C14AS chronic-toxicity studies with full analytical support to confirm exposure concentrations are suggested to validate the safety of C14AS in the aquatic environment. 

The protection factor, pi, for the amide proton of residue i is given by the ratio of the rate constants fejnt,i and fe0bs,i f°r the intrinsic chemical exchange and the respective observed exchange reactions for residue i as follows ... 

To quantify the protective effect of textiles, the solar protection factor (SPF) is determined. The SPF is the ratio of the potential erythemal effect to the actual erythemal effect transmitted through the fabric by the radiation and can be calculated from spectroscopic measurements. The larger the SPF, the more protective the fabric is to UV radiation. In Europe and Austraha, the SPF is referred... 

While the residue stability constants are purely thermodynamic quantities defined for all residues, the protection factors also contain non-thermodynamic contributions and are defined only for a subset of residues. For example, proline residues lack the amide group and therefore are not included. From a statistical standpoint, the protection factor for any given residue] can be defined as the ratio of the sum of the probabilities of the states in which residue j is closed, to the sum of the probabilities of the states in which residue] is open ... 

The Sun Protection Factor (SPF) is the ratio of the amount of UVB radiation that is just enough to produce sunburn on protected skin to the amount that will produce the same effect on unprotected skin. For example, skin protected by a sunscreen with an SPF of 10 should be able to withstand a given intensity of UVB rays for 10 times as long as unprotected skin before burning. As no assessment of UVA protection is included, the SPF should not be used as the basis for recommending a sunscreen to a patient who is sensitive to UVA. 

The resistence to oxidation was related to the high content of polyphenols removal of polyphenols greatly reduced oxidative stability [39]. The subsequent studies were devoted to identifying the compoimds which more contribute to oil stability and the mechanism of protection. Hydroxytyrosol and caffeic acid were better protection factors than BHT tyrosol and other monohydroxy phenols gave little contribution to oil stability [43] oil shelf-life was positively correlated to hydroxytyrosol / tyrosol ratio [44]. 

Furthermore, a diet with low contents of FA may be involved in the development of insulin resistance, which suggests that an appropriate dietary intake of n-3 PUFA is considered protective against metabolic syndrome [183]. In addition, diverse psyquiatric impairs (depression, bipolar disorders, schizophrenia, autism) and neurodegenerative diseases such as Alzheimer disease have been associated to decreased blood levels of n-3 HUFA. Besides, there are many examples about the use of pol)nmsaturated FA as drugs. Thus, EPA has shown efficacy as adjunctive treatment, and in some cases as the only treatment in several psyquiatric disorders [184]. It is suggested that the potential of n-3 FA to prevent recurrence and metastasis of mammary cancer when used in adjuvant therapy is associated with a n-6 to n-3 ratio lower than 2 1 [185], On the other hand, fish intake is considered as a protective factor for preventing prostate cancer in addition, in humans low levels of ALA in mammary adipose tissue are associated with an increased risk of breast cancer in women [186]. 

SPF is the ratio of the length of time of solar radiation exposure required for the skin to show redness (erythema) with and without protection. The term SPF or UPF (ultraviolet protection factor) has been introduced such that a garment of UPF 15 will provide the same amount of protection against solar ultraviolet radiation as a sunscreen of SPF 15. Garments with a UPF value of 20-29 offer high protection (UVR transmission 5.0-3.3%). A UPF value of 30-40 (UVR transmission 3.3-2.5%) offers very high protection and a UPF value of 40 + offers maximum protection with a UVR transmission of 2.5%. 

The protection afforded by a respirator is usually expressed as the protection factor (PF), i.e. the ratio of the concentration of agent outside to that inside the respirator. Respirators are tested on real people using simulated agents most testing is carried out in the laboratory, but work-place/field testing is increasingly being used. 

The major measurement of sunscreen photoprotection is the sun protection factor (SPF), which defines a ratio of the minimal dose of incident sunlight that will produce erythema or redness (sunburn) on skin with the sunscreen in place (protected) and the dose that evokes the same reaction on skin without the sunscreen (unprotected). The SPF provides valuable information regarding UVB protection but is useless in documenting UVA efficacy because no standard systems have been developed to measure UVA protection. Such protocols are needed because more than 85% of solar ultraviolet radiation reaching earth s surface is UVA, which penetrates more deeply into human skin than does UVB and appears to play an important role in photoaging and photocarcinogenesis. 

Sunscreens have sun protection factors listed prominently on their labels. The sun protection factor (SPF) is defined as the ratio of time required to produce a perceptible erythema on a site protected by a specified dose of the sunscreen to the time required for minimal erythema development on unprotected skin. An SPE of 4, for example, would provide four times the skin s natural sunburn protection. The time required for sunburn depends on an individual s skin... 

These products are given a Sun Protection Factor (SPF) rating. The SPF value is a ratio of the amount of time required to tan (or burn) with versus without the product. An SPF value of 10, for example, indicates that when using the product, you can be exposed to the sun 10 times as long without burning. 

Protection factor is the ratio of the contaminant concentration outside the facepiece to the concentration inside. 

Figure 3.67 shows the reaction without an antioxidant and the reaction in its presence. It is clear that antioxidants prolong the induction period (slow autoxidation), but do not affect the rate of the subsequent rapid oxidation. The ratio of the length of the induction period of inhibited and uninhibited reactions is called the protection factor. It is usually expressed as a percentage of increased stability (extension of the induction period). 

Another method used for evaluating the resistance to oxidation of steels is Cu K X-ray diffraction with a glancing angle technique. This method aims to determine the area (A) of peaks at 29 = 35.5 (Fc304 + a-Fe203) and 29 = 44.6 (a-Fe) for uncoated (Ra) and coated (Re) samples. The ratio ilu/-R-c determines the degree of oxidation, which is expressed as the protection factor (PF) (Gugliemi, 1992). 

The interest in lecithin as a protective factor against heart disease arose from the finding that high ratios of cholesterol to to phospholipids in the blood were correlated with the severity of atherosclerosis." Furthermore, it is established that the phospholipids of the platelet plasma membrane play an important role in blood coagulation."... 

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