18F-labeled compounds


Substitution of deuterium for hydrogen at the a carbon atom of an aldehyde or a ketone is a convenient way to introduce an isotopic label into a molecule and is readily carried out by treating the carbonyl compound with deuterium oxide (D2O) and base  [c.768]

Numerous bacterial and fungal genera have species able to degrade hydrocarbons aerobically and the pathways of degradation of representative abphatic, naphthenic and aromatic molecules have been well characterized in at least some species (8). Other organisms, such as algae and plants, do not seem to play a very important role in the biodegradation of hydrocarbons. It is a tmism that the hallmark of an oil-degrading organism is its abdity to insert oxygen atoms into the hydrocarbon, and there are many ways in which this is achieved. Figures 2 and 3 show the most weU-studied. Once a hydrocarbon possesses a carboxylate or alcohol functionahty it is almost invariably a readdy degradable compound. A simple example at the human level is the difference between oleic acid, a high calorie food, and octadecane, present in mineral od, which is so inert that it serves as an intestinal lubricant  [c.27]

The flavor portion of a flavor compound gives it its name, acceptabiUty, and palatabiUty, and provides character fixation of the flavor, ie, relatively high boiling point soflds, usually in combination, are used at concentrations above thek threshold values at use level so that upon dilution the levels remain above threshold value and the perception of the flavor does not change.  [c.16]

Kinetic Control. In direct fluorination processes, concentration, time, and temperature can be controUed. In most previous work, the fluorine was diluted with an inert gas such as nitrogen, helium, or even carbon dioxide. However, the concentration of fluorine in the reactor was kept at a constant level, usuaUy 10% or greater, by premixing the inert gas with fluorine in the desired proportion and then introducing this mixture into the reactor. The rate of reaction between a hydrocarbon compound and a 10% fluorine mixture is relatively high, and this very exothermic process can lead to fragmentation and, in some cases, to combustion. The initial stages of reaction are most critical nearly aU the fragmentation occurs at this time. An initial concentration of 10% fluorine or more is, for most compounds, much too high for nondestmctive fluorination.  [c.275]

Random screening techniques have provided 50% of herbicides available (ca 1993). Chemicals that act on one biological screen frequentiy act on other pesticidal, plant growth regulator, or pharmaceutical screens. However, a steadily increasing number of chemicals must be tested to uncover a single compound with pesticidal potential. The time required for the discovery of one new compound with good herbicidal activity, which also meets tightening biological and environmental standards, is becoming progressively longer. On the average, more than 20,000 chemicals must be screened to produce one new product. The screening process is compHcated further by large numbers of false positives and significant discrepancies between field and screening environments. Carefully balanced judgment of apparent activity must always take iato accouat the level and specificity of biological action, the chemical and action novelty with respect to patenting requirements, and the potential and scope for commercial exploitation.  [c.38]

For each specific appHcation of a mbber compound as an iasulating material, there is a minimum value of resistivity below which it does not function satisfactorily. In addition, iasulating compounds are required to withstand the effect of water, moist atmosphere, or heat without their resistivity values falling below a satisfactory level. Insulation resistance measurements frequently serve as useful control tests to detect impurities and manufactuting defects ia mbber products.  [c.325]

Analytical Approaches. Different analytical techniques have been appHed to each fraction to determine its molecular composition. As the molecular weight increases, complexity increasingly shifts the level of analytical detail from quantification of most individual species in the naphtha to average molecular descriptions in the vacuum residuum. For the naphtha, classical techniques allow the isolation and identification of individual compounds by physical properties. Gas chromatographic (gc) resolution allows almost every compound having less than eight carbon atoms to be measured separately. The combination of gc with mass spectrometry (gc/ms) can be used for quantitation purposes when compounds are not well-resolved by gc.  [c.167]

Gravimetric methods of analysis of PGM compounds have been largely superseded by spectroscopic methods, which are not only more versatile and selective, but require significantly less labor (12). The methods most often used are inductively coupled plasma-emission spectroscopy (icp-es), flame atomic absorption spectroscopy (faas), and graphite furnace atomic absorption spectroscopy (gfaas). For routine determinations where the PGM compound can be dissolved in aqueous or organic solution, icp-es is generally preferred to faas, because the former is freer from chemical interference caused by differences between the sample and standard matrix. The preferred method for trace level determinations is gfaas, which can also be used for sohd samples and small (as Httie as 1 p.L) samples (12) (see Trace and residue analysis). The analysis of noble metals by classical and spectroscopic methods as well as a variety of specialized spectroscopic methods has been reviewed (12—14).  [c.177]

Compound Stmcture number Flash point °C DOT label "  [c.333]

The compound cycle (Fig. 7) achieves temperatures ca —100° C by using two or three compressors in series and a common refrigerant. This keeps the individual machines operating within their appHcation limits. A refrigerant gas cooler is normally used between compressors to keep the final discharge temperature at a satisfactory level. Below — 100°C, most refrigerants with suitable evaporator pressures have excessively high condensing pressures. For some refrigerants, the specific volume of refrigerant at low temperature may be so great as to require compressors and other equipment of uneconomical size. In other refrigerants, even though the specific volume of refrigerant is satisfactory at low temperature, the specific volume may become too small at the condensing condition.  [c.65]

Compound cycles using reciprocating compressors or any cycle using a multistage centrifugal compressor allow the use of economizers or intercoolers between compression stages. Economizers reduce the discharge gas temperature from the preceding stage by mixing relatively cool gas with the discharge gas before entering the subsequent stage. Either flash-type economizers, which cool refrigerant by reducing its pressure to the intermediate level, or surface-type economizers, which subcool the refrigerant at condensing pressure, may be used to provide the cooler gas for mixing. This keeps the final discharge temperature low enough to avoid overheating of the compressor and improves compression efficiency.  [c.67]

FDA s mission has traditionally been consumer protection. However, the manner in which the agency accomplishes its regulatory mission has been changing with the explosion of advances within analytical chemistry and toxicology. Because new and better compounds are continuously being developed, increased attention is being devoted to the dilemma of speeding their entry into the market while ensuring their safety and effectiveness. Scientists must not only develop new compounds, but also explain how the benefits outweigh the risks so that society can benefit from their work. Because no compound is completely safe, FDA must make an assessment of the intended use and determine whether the level of risk is acceptable. Only when FDA is able to make timely, scientifically based judgments on data will society reap the rewards of science. For example, FDA has taken the position that society is willing to accept a higher degree of risk for a life-saving device or dmg than for a cosmetic or food additive. Making these judgments in a scientific and pohtical context is the responsibiUty of FDA.  [c.83]

Latex compound viscosity obviously forms an important aspect of dipped product manufacture. Accurate measurement by a Brookfield or similar viscometer is desirable to estabhsh the fundamental viscosity of a compound, but Flow-Cup viscometers (Ford B.3 Cup) are more commonly used for day-to-day control of latex compounds during compounding and product manufacture. It is necessary to ensure that only stainless steel flow cups are used, if the measured latex is allowed to return to the production tanks brass cups yield an unacceptable level of copper contamination, which adversely affects aging properties of products made from copper-contaminated mbber compound.  [c.261]

Once the abiUty to control the randomization of solution SBR was understood and established, the commercialized SSBR began to displace some of the ESBR in tire applications. It was found that the SSBR alone could achieve the same desired properties that blends of ESBR and polybutadiene gave, thus simplifying the compound recipes. The combination of low rolling resistance and high wet traction without sacrificing abrasion resistance (tread wear) is attainable with SSBR but not with ESBR alone. Also, by controlling the vinyl microstmcture to a low level, a lower T is achieved than for ESBR at the same styrene content. This allows for a higher level of oil and carbon black to be added (31).  [c.498]

Mannitol is a food additive permitted in food on an interim basis. Usage levels in foods, outlined by 21 CFR 180.25, include 98% in pressed mints and 5% in all other candy and cough drops, 31% in chewing gum, 4% in soft candy, 8% in confections and frostings, 15% in nonstandardized jams and jeUies, and 2.5% in all other foods. The label of food where the reasonably foreseeable consumption may result in a daily ingestion of 20 grams of mannitol shall bear the statement "Excess consumption may have a laxative effect". Because mannitol is nonhygroscopic, it has been the bulking agent of choice for sugar-free chocolate-flavored coatings and compound coatings. Where the cooling effect of mannitol is undesirable, maltitol is used as a replacement. Mannitol is also used as a plasticizer in sugar-free chewing gum and as a dusting agent on the gum to prevent it from sticking to the wrapper.  [c.53]

Another typical customer question is "why did product X do Y in my process " This is the troubleshooting, consultative part of the technical service function. The range of effort required to answer this question is as broad as for the first example. Consider the case of a converter firm that produces acrylonitrile—butadiene—styrene (ABS) compounds containing carbon black for use in the downstream manufacture of telephone housings. The customer reports that the L, ie, a color measurement parameter, of a large batch of compound was too high for sale. Upon visiting the customer, the technical service person investigates the situation and finds that the mixers used to prepare the compound were not being operated in a manner to ensure a proper level of shear during mixing. As such, the level of dispersion of the carbon black in the ABS was not sufficient, leading to the drop in color as deterrnined by a measurement of L.  [c.378]

The quantum dynamics of unimolecular decomposition may be studied by solving the time-dependent Schrodinger equation, i.e. equation (A3.12.2T For some cases the dissociation probability of the molecule is sufficiently small that one can introduce the concept of qiiasi-stationary states. Such states are conmronly referred to as resonances, since the energy of the unimolecular prodiict(s) in the continuum is in resonance with (i.e. matches) the energy of a vibrational/rotational level of the unimolecular reactant. For unimolecular reactions there are two types of resonance states. A shape resonance occurs when a molecule is temporarily trapped by a fairly high and wide potential energy barrier and decomposes by tunnelling. The second type of resonance, called a Feshbach or compound-state resonance, arises when energy is initially distributed between molecular vibrational/rotational degrees of freedom which are not strongly coupled to the decomposition reaction coordinate motion, so drat there is a time lag for unimolecular dissociation.  [c.1028]

On a modest level of detail, kinetic studies aim at detemiining overall phenomenological rate laws. These may serve to discrimmate between different mechanistic models. However, to it prove a compound reaction mechanism, it is necessary to detemiine the rate constant of each elementary step individually. Many kinetic experiments are devoted to the investigations of the temperature dependence of reaction rates. In addition to the obvious practical aspects, the temperature dependence of rate constants is also of great theoretical importance. Many statistical theories of chemical reactions are based on themial equilibrium assumptions. Non-equilibrium effects are not only important for theories going beyond the classical transition-state picture. Eventually they might even be exploited to control chemical reactions [24]. This has led to the increased importance of energy or even quantum-state-resolved kinetic studies, which can be directly compared with detailed quantum-mechanical models of chemical reaction dynamics [25, 26].  [c.2115]

Boron halides are all covalently bonded with melting and boiling points increasing as expected with the increasing molecular weight. All boron trihalides exist as monomers in the vapour state and have regular trigonal planar configurations. They are electron-deficient compounds since in each halide the boron atom has only six electrons in its second quantum level and consequently they are electron pair acceptor molecules, i.e. Lewis acids. The ready hydrolysis of all the boron halides probably begins with the formation of a coordination compound with water, the oxygen atom donating a pair of electrons this is rapidly followed by loss of hydrogen chloride, this process continuing to give finally BfOH),. i.e. boric acid.  [c.152]

On heating the pentahydrate, four molecules of water are lost fairly readily, at about 380 K and the fifth at about 600 K the anhydrous salt then obtained is white the Cu " ion is now surrounded by sulphate ions, but the d level splitting energy does not now correspond to the visible part of the spectrum, and the compound is not coloured. Copper(Il) sulphate is soluble in water the solution has a slightly acid reaction due to formation of [CufHjOijOH] species. Addition of concentrated ammonia  [c.412]

Dissolve 68 g, of crystallised sodium acetate in 100 ml. of water, and dilute to 120 ml. Add 50 ml. of this solution to the reaction mixture and stir for a further 4 hours eUminate any appreciable amoimt of foamy solid by the addition of a few drops of ethyl acetate. Allow the mixture to stand overnight in an ice box or in a refrigerator the temperature must be kept below 7°. Then add the remainder of the sodium acetate solution with stirring to the mixture cooled in an ice bath, stir for an additional period of 2-3 hours, and allow the temperature to rise to 20-25° during 24 hours. Introduce just sufficient sodium hydroxide solution with stirring to cause the mixture to have a distinct odour of dimethylaniline (24 ml. of a 40 per cent, solution are usually required), and allow to stand at room temperature (20-25°) for 48 hours or longer. (The formation of the azo compound is a very slow reaction, but is accelerated by increasing the pH of the solution.) Filter off the sohd at the pump, wash it first with water, then with 40 ml. of 10 per cent, acetic acid (to remove the dimethylanihne), and finally with water (the last filtrate is pale pink) drain well. Dry the sohd in the air for 24 hours. Suspend the sohd in 400 ml. of methyl alcohol in a 1500 ml, bolt-head flask stir the mixture on a water bath under a reflux condenser for 1 hour, cool in ice and filter. Wash with 400 ml. of cold methyl alcohol and dry in the air. The yield of crude methyl red is 85 g. (2). Purify by extraction with 700 ml. of boiling toluene (3) in a Soxhlet apparatus (Fig. II, 44, 5 or 6). When the extraction is complete, remove the flask containing the almost boihng toluene to a bath containing water at 90-100° and arrange that the level of the water is shghtly above that of the toluene in the flask. The temperature thus falls slowly and large crystals are obtained. Finally allow to cool to room temperature. Filter off the crystals and wash with a Uttle toluene. The yield of methyl red, m.p. 181-182°, is 79 g.  [c.626]

For nitrations in sulphuric and perchloric acids an increase in the reactivity of the aromatic compound being nitrated beyond the level of about 38 times the reactivity of benzene cannot be detected. At this level, and with compounds which might be expected to surpass it, a roughly constant value of the second-order rate constant is found (table 2.6) because aromatic molecules and nitronium ions are reacting upon encounter. The encounter rate is measurable, and recognisable, because the concentration of the effective electrophile is so small.  [c.46]

It will be seen from table 3.6 that whilst in 68-3 % sulphuric acid the limiting rate of nitration is about 38 times and in 61-05% perchloric acid about 80 times, in the organic solvents it is 300-400 times the rate of nitration of benzene. Furthermore the limiting rate is very sharply defined for the mineral acids but much more diffuse for the organic solvents. In the mineral acids it seems that complete or partial control by the encounter rate must be operating even for a compound so weakly activated as toluene, whilst with the aqueous organic solvents the limit is reached at the level of reactivity represented roughly by w-xylene. The factors which determine the point of onset of control by encounter have been discussed but are not really understood. One interesting conclusion drawn from the results was that whilst in 68-3 % sulphuric acid the value of the ratio [N02" ]/[HN03] is about 3 x io , in the aqueous organic solvents it is about The absolute values are doubtful, but these figures do bring out at what very small concentrations the nitronium ion remains the effective nitrating agent.  [c.48]

Beyond pharmaceutical screening activity developed on aminothiazoles derivatives, some studies at the molecular level were performed. Thus 2-aminothiazole was shown to inhibit thiamine biosynthesis (941). Nrridazole (419) affects iron metabohsm (850). The dehydrase for 5-aminolevulinic acid of mouse liver is inhibited by 2-amino-4-(iS-hydroxy-ethyl)thiazole (420) (942) (Scheme 239). l-Phenyl-3-(2-thiazolyl)thiourea (421) is a dopamine fS-hydroxylase inhibitor (943). Compound 422 inhibits the enzyme activity of 3, 5 -nucleotide phosphodiesterase (944). The oxalate salt of 423, an analog of levamisole 424 (945) (Scheme 240),  [c.152]

The phenoxy-herbicide, 2,4-D, has been successfully bioremediated in a soil contaminated with such a high level of the compound (710 ppm) that it  [c.33]

As had been noted in the previous edition of this Eniyclopedia, the removal of solvents by condensing them from an inert gas in a water-cooled condenser is inefficient, and may create a potentially ha2ardous condition at the point of discharge. Vapor pressures of most solvents are relatively high. Therefore, at temperatures obtainable in a water-cooled heat exchanger, these substances maintain an appreciable partial pressure in the discharging gas. An environmentally unacceptable high VOC (volatile organic compound) level in the emitted gas, and the fact that the remaining solvent concentration is in many cases above the lower explosive limit, makes a water-cooled heat exchanger an unlikely instmment for solvent removal to an environmentally acceptable level.  [c.254]

Commercial urea generally contains a small amount of the compound biuret [108-15-0] NH2CONHCONH2. For fertilizer use other than foflar apphcation, biuret contents of about 1.5% or less are not harmful, and under usual production conditions it is not difficult to avoid higher biuret levels. For most fohar apphcation, however, the level should not exceed 0.1%, and special production modifications are usually requited to ensure such a low level.  [c.220]

Geo has been used to find a subtie but distinctive odor note common in the grapes grown in North America, ie, Vitis rotundifolia (southern Fox Grape) and Vitis labruscanna (northern Fox Grape). Grapes of these species have been characterized as having a sweet fox-like smell methyl anthranilate traditionally has been the only component identified in grapes that could explain this character. However, many cultivars, eg, Catawaba, have a sweet foxy smell but have sub threshold levels of methyl anthranilate [134-20-3]. A serendipitous discovery in Japan led to the recognition that the waxy contents of the anal sac of the Japanese and Korean weasels contain an intense odor similar to that of the native American grapes (52,66). The odor was found to be due to the presence of o-amino acetophenone in both the weasel and the grape. The most odor-potent compound in the grape was phenylethyl alcohol, a characteristic odor of all grapes and yeast fermented juices however, the o-amino acetophenone was the odorant that characterized these grapes as labruscanna. The high level in the weasel allowed easy identification and once this standard was available verification of the presence at much lower levels in the grape was easy.  [c.6]

Hydrocarbon propellants, eg, propane, isobutane, butane, are the most commonly used in mousses. These are insoluble in the mousse concentrate therefore, vigorous shaking of the can before use is requited to properly disperse the propellants. Most products use a blend of two or more hydrocarbons. The more volatile the propellant blend, the faster a foam stmcture is formed and the less dense it is. An exception to this is the use of hydrofluorocarbon 152A [75-37-6] (HFC) which has partial solubiUty in mousse concentrates and a high volatility. The high volatility creates an immediate foam stmcture but the partial solubiUty leads to a creamy, dense foam. HFC is not an ozone depleting propellant as are its cousins the chlorofluorocarbons (CFCs) additionally, it is not considered a volatile organic compound by the states of California and New York due to its low activity in reactions that create ground level ozone.  [c.453]

Environmental Regulation. In 1978, federal regulation banned the use of chlorofluorocarbons in hair sprays. This forced a dramatic change in the technology of aerosol hair sprays, requiring new formulations and new dispensing parts to accommodate hydrocarbon propellants. In the early 1990s, California and New York enacted strict limits on allowable VOC content VOCs are defined as any compound containing at least one atom of carbon, but no more than 12 atoms, with a vapor pressure of 13.3 Pa (0.1 mm Hg) or more at 20°C. The regulations were enacted due to the role that VOCs play in creating ground level ozone. In 1992, California allowed a maximum of 80% VOC content in finishing sprays, with reduction to 55% maximum VOC content by 1998 (25). In New York the regulations are almost the same, and other states are expected to foUow.  [c.455]

Ultrasonic. Ultrasonic level devices are based on measuring the propagation of inaudible sound waves through air, Hquids, or metals at a frequency range of 20 kH2 to 4 mH2. This is a mechanical process of compression and expansion initiated by a vibrating material. This vibration is induced by a pie2oelectric crystal with an alternating current of a frequency equal to the frequency at which the material vibrates most easily. The pie2oelectric crystals are typically made from a lead 2irconate or barium titanate compound which converts electrical energy to mechanical energy and vice versa.  [c.214]

Inhalation of particulate manganese compounds, such as manganese dioxide, can lead to an inflammatory response in the lungs of both humans and animals. This response is characteristic of all inhalable particulate matter, however, suggesting that the manganese compound is not specifically responsible. Inhalation of soluble manganese compounds does not cause an inflammatory response in the lungs of test rabbits (197). There are reports of increased susceptibiUty to lung infections reported for both humans and animals where there is a chronic exposure to manganese dusts. This is considered secondary to the irritation caused by the inhaled particulate matter. General population exposure to manganese compounds in the air in nonurban areas is about 5 ng/m in urban areas, 33 ng/m and in source dominated areas, 135 ng/m (198). In the soil, manganese is estimated to be in the 40-900 mg/kg range. The maximum reported is 7000 mg/kg (199). The lowest observed adverse effect level (LOAEL) (200) reported for Mn by inhalation is 0.14 mg/m. This results in a chronic exposure by inhalation minimal risk level (MRL) of 0.3 //g/m. The dermal absorption of inorganic manganese compounds is not considered toxicologicaHy significant. The primary exposure of the general population to manganese compounds is from diet.  [c.525]

In 1964, the presence of nootkatone [4674-50-4] (63), a known molecule, was confirmed in grapefmit oil (34). Some have considered nootkatone responsible for the characteristic aroma of grapefmit oil, but highly purified (+)-nootkatone (63) actually displays very weak odor properties. This was also observed in 1983 in a report that grapefmit oil contains a series of nootkatone analogues, one of which, (+)-8,9-didehydronootkatone [5090-63-1] (64), displays a particularly valuable grapefmit aroma similar to, but definitely stronger than, that of (+)-nootkatone (63) itself (35). Just prior to this work, investigators characterized the tme character-donating component of grapefmit oil and juice as p-rr enthene-8-thio1 (4). This compound is present in fresh grapefmit juice (in which it naturally occurs at or below the ppb level) (36).  [c.310]

PhosgenePhosgene [75-44-5] [75-44-5] (carbonyl chloride, carbon oxychloride, chloroformyl chloride), CI2CO, is a colorless, low boiling liquid. The compound was first prepared in 1812 by J. Davy from the photochemical reaction of carbon monoxide and chlorine. Phosgene may be formed at elevated temperatures by oxidation of chlorinated solvents (1 5). Aside from its use as a warfare agent in World War I, phosgene has been used in the preparation of a great variety of chemical intermediates. It is widely used in the preparation of isocyanates which are used in the preparation of polyurethanes (see Urethane polymers), in the manufacture of polycarbonate, and in the synthesis of chloroformates and carbonates which are used as intermediates in the synthesis of pharmaceuticals and pesticides (see Carbonic and carbonochloridic esters). Because of its toxicity, a high level of safety technology has been developed to help ensure the safe handling of phosgene.  [c.311]

The confidence level in the identification capabiUty for gc /ir /ms is enhanced by the abiUty to perform computer Hbrary searching of large spectral databases. Unknown spectra are searched against reference databases and a hit quaUty number, indicating how well the unknown spectmm matches the hbrary spectra, is generated. For the very small peak at 19 min in Figure 4, peak 6 in the TIC, the Hbrary search identified the component as a-pheUandrene [99-83-2] C qH, for both the it and ms data. Because these data are complementary and generated from two completely independent principles of detection, this method provides virtually irrefutable evidence as to a component s correct identity. The complementary nature of the data is further demonstrated by another component in this essential oil. Late in the chromatogram is a long-chain aHphatic alcohol. The mass spectral data confirmed an unsaturated aHphatic chain of specific length, but because of dehydration in the ion source of the ms no alcohol group was evident. On the other hand, the infrared spectmm indicated the presence of an alcohol functionaHty, but gave Htfle evidence with regard to the length of the aHphatic chain. Thus the combination of complementary ir and ms data was the key to the correct identification of this compound.  [c.403]

Pharmacokinetics. The aminoglycosides are not rehably absorbed following oral dosing, so they are adininistered primarily by intravenous infusion or intramuscular injection (75—77). Distribution throughout the vascular and interstitial space occurs fairly rapidly. Because these antibiotics are polycationic and relatively large, biological membranes are not readily crossed, unless transport mechanisms exist as in the kidney proximal tubule cells, and intracellular levels are generally low. Levels in the cerebrospinal fluid (CSF), bronchial secretions, and saUva are also low. Aminoglycoside excretion takes place almost entirely via the kidneys. Most of the compound is eliminated unmetaboli2ed in a relatively rapid beta phase having a half-life of 2 —3 h. A small portion, however, is excreted in a slow gamma phase, half-life 35—200 h. Because of the relatively short beta-phase half-life, dosing is usually two or three times per day. Efficient clearance is dependent on glomerular function and, when glomerular filtration rate is reduced because of age or kidney disease, particular care in dosing must be exercised to prevent accumulation of toxic aminoglycoside levels (78). Some studies have shown that, for certain clinical apphcations, an aminoglycoside can be adininistered once a day and efficacy is unchanged while toxicity is decreased (79—82). A possible contributor to the success of this strategy is the observation of a post-antibiotic effect (83), in which growth inhibition of some bacterial species continues for a period of time after the semm concentration of the aminoglycoside drops below the presumed inhibitory level.  [c.481]

It is truly possible to imagine the characteristics of an ideal radiopharmaceutical only in the context of a specific disease and organ system to which it might be appHed. Apart from the physical factors related to the radioisotope used, the only general characteristic that is important in defining the efficacy of these materials is the macroscopic distribution in the body, or biodistribution. This time-dependent distribution at the organ level is a function of many parameters which may be divided into four categories factors related to deUvery of the radiopharmaceutical to a particular tissue factors related to the extraction of the compound from circulation factors related to retention of the compound by that tissue and factors deterrnined by clearance. The factors in the last set are rarely independent of the others.  [c.473]

AminoethylIsothiuronium Bromide Hydrobromide and 5-Hydroxy-L- Tryptophan. Synergistic protection by the thiol compound aminoethylisothiuronium bromide hydrobromide (ART) and 5-hydroxy-L-tryptophan (5-HTP) at doses of each agent that were iadividuaHy iaeffective and nontoxic has been described (75,76). Treating mice with ART (20 mg/kg) plus 5-HTP (100 mg/kg ip) 30 min before TBI modified the decline ia sperm couats, significantly decreased the level of sperm abaormahties, and protected against stetihty associated with oligospermia. This same combination of agents markedly protected normal hemopoietic mouse tissues, showiag a - 1.76-fold iacrease ia well as enhanced recovery of  [c.490]

Bark beetle management in European forests has been successful using combinations of sex pheromones and tree volatiles. RepeUents that were tested in Louisiana to deter attacks of the southern pine beetle afforded protection of high value lobloUy pines by using the host tree compound 4-aUylanisole [140-67-0] (49). The aggregation inhibitor 4-aUylanisole (21) eliminated tree deaths for the length of the 30-d test by placing nine vials with wicks containing 20 g each of repeUent verticaUy on the lower tmnk of each tree being protected, using the tree as a flagpole. A patent has been issued on this technology (49).  [c.119]

Sweetness potency denotes how many times a given compound is more potent than sugar on the same weight basis. For example, because it takes 0.75 g/L of aspartame, a nonnutritive sweetener, to match the sweetness of a 10% (100 g/L) sucrose solution, aspartame is assigned a 133(=100/0.75) -times (commonly written as 133X) sweetness potency. When compared to a lower concentration of sugar solution, the sweetness potency is usually much higher, eg, 180x for aspartame when compared with the sweetness of a 2% sucrose solution. Therefore, reported sweetness potencies must be iaterpreted carefully, preferably with the % concentration of the matching sucrose solution also iadicated. Because sweet beverages commonly employ about 10% sucrose, sweetness iatensity matching this sucrose solution is commonly used. The determination of sweetness potency is rather subjective and can be greatly affected by the sensitivity and experience of tasters other iagredients ia the solution, eg, pure water vs flavored beverage texture of the food pH temperature of the samples etc. Therefore, the pubUshed potency should be used only as a guideline and a food technologist should optimize the sweetener level ia each product.  [c.272]


See pages that mention the term 18F-labeled compounds : [c.289]    [c.41]    [c.151]    [c.158]    [c.105]    [c.41]    [c.102]    [c.617]    [c.47]    [c.447]    [c.382]   
Chemistry of Organic Fluorine compounds II (1995) -- [ c.0 ]