Experimental procedure

Typical Experimental Procedures for Generation of Titanium Enolates 

The crude products were purified by fiash chromatography on silica gel. 

Oxazolidinethione-derived Titanium Enolate for syn Aldol Reactions (Crim-mins s Procedure, Section 2.4.1.2.1). To a dry round-bottomed fiask under nitrogen was added 0.250 g (1.0 mmol) oxazolidinethione in 6 mL CH2CI2. 

The solution was cooled to 0 °C and TiCl4 (1.05 mmol, 0.115 mL) was added dropwise and the solution was stirred for 5 min. To the yellow slurry or suspension was added (—)-sparteine (2.5 mmol). The dark red enolate was stirred for 20 min at 0 °C. Freshly distilled aldehyde (1.1 mmol) was added dropwise and the reaction stirred for 1 h at 0 °C. The reaction was quenched with half-saturated NH4CI and the layers were separated. The organic layer was dried over Na2S04, filtered, and concentrated. Purification of the crude material by column chromatography afforded the main diastereomer. 

In this brief experimental section we wish to present some procedures for the preparation of several simple 1-cyano- and 1-halogenoacetylenes which we have been using for several years. None of these procedures is original rather, these descriptions represent optimizations of methods previously published with the appropriate references already given in the main sections of this review. For the procedures for preparing 1-chloroacetylene (93) and 1,2-diiodo-acetylene (105) we are indebted to Professor Dr. E. Kloster-Jensen (University of Oslo). 

After completion of the dehydration the solvent may be recovered by distillation. 

A solution of 23 g (0.162 mol) of dimethyl acetylenedicarboxylate in 30 mL of diethyl ether is slowly added to 200 mL of liquid ammonia kept at —40 °C. After a short time, acetylenedi-carboxamide (7) begins to precipitate. To complete the reaction, the mixture is stirred for 8 h at — 40°C. The excess tunmonia is evaporated at room temperature, and the residue is extracted with 50 mL of boiling ethanol followed by the same amount of methanol. After cooling these extracts to room temperature, the precipitate formed is isolated by filtration and dried under high vacuum 11-16 g (0.10-0.14 mol, 62-88%) of 7. 

Into a 500-mL three-necked flask equipped with dropping funnel and mechanical stirrer and connected via a U-tube filled with glass wool to a cold trap cooled to -78°C, 100 mL of freshly distilled sulfolane is placed and 25 g (88 mmol) of P4O10 is added. The apparatus 

The remainder of the chapter is concerned with increasingly specialized developments in the study of gas adsorption, and before proceeding to this material, it seems desirable to consider briefly some of the experimental techniques that are important in obtaining gas adsorption data. See Ref. 22 for a review of traditional methods, and Ref 23 for lUPAC (International Union of Pure and Applied Chemistry) recommendations for symbols and definitions. 

Adsorption isotherms conventionally have been determined by means of a vacuum line system whereby pressure-volume measurements are made before and after admitting the adsorbate gas to the sample. For some recent experimental papers, see Refs. 24 and 25. 

If the total surface area is small (say, a few hundred square centimeters), the amount adsorbed becomes so little that measurements are difficult by normal procedures. Thus the change in pressure-volume product on admitting gas to the adsorbent becomes so small that precision is impaired. 

One way of avoiding this problem is to set Ti so that the vapor pressure of the liquid adsorbate is very low (e.g., krypton at -195°C [26, 27]. Monolayer 

Alternatively, gas chromatography may be used Fig. XVII-5 shows a schematic readout of the thermal conductivity detector, the areas under the peaks giving the amount adsorbed or desorbed. 

External Detector (EDM) methods have been extensively used for apatite and the EDM has now become the standard procedure in most laboratories. Galbraith (1984) describes the statistical treatment of analytical data derived by both these methods, and interlaboratory comparisons have mostly demonstrated excellent reproducibility using both procedures (Miller et al. 1985, 1990). 

The apparatus used for reductions in liquid ammonia is a three-necked flask equipped with a stirrer, dropping funnel and soda lime drying tube. The flask is filled from one-third to no more than one-half its capacity, to aid in control of foaming which occurs in some instances toward the end of alcohol addition. 

To a solution of 1.38 g of estradiol 3-methyl ether (mp 118-119°) in 110 ml of anhydrous ether is added 140 ml of liquid ammonia followed by 1.4 g (42 eq per mole) of lithium wire in small pieces, and 10 min later 16 ml of absolute alcohol is added dropwise over a 10- to 20-min period. Occasionally frothing occurs during the last part of this addition but is easily controlled by stopping the stirrer temporarily. After removing most of the ammonia and carefully adding cold water, the product is extracted with ether, washed with Claisen alkali, water and saturated salt solution, and dried over sodium 

Birch Reductions in Ammonia-Tetrahydrofuran-t-Butyl Alcohol  

For large scale laboratory reductions ca. 100 g of an aromatic steroid) the dry ice reflux condenser may be omitted, but the reaction flask should be 

Reductions with alcohols other than t-butyl alcohol are carried out using the general procedure given above and replacing the -butyl alcohol by an equivalent amount of the other alcohol. 

A detailed procedure for the use of MCPBA recently appeared in Reagents for Organic Synthesis by Fieser and Fieser. The commercially available MCPBA (Aldrich) is 85% pure the contaminant, m-chlorobenzoic acid, can be removed by washing with a phosphate buffer of pH 7.5. The epoxidation is usually performed as follows a solution of 3 -acetoxy-5a-androst-16-ene (2.06 g, 6.53 mmoles) in 25 ml of chloroform (or methylene dichloride) is chilled to 0° in a flask fitted with a condenser and drierite tube and treated with a solution of commercial MCPBA (1.74 g, 20% excess) in 25 ml chloroform precooled to the same temperature. The mixture is stirred and allowed to warm to room temperature. After 23 hr (or until TLC shows reaction is complete) the solution is diluted with 100 ml chloroform and washed in sequence with 100 ml of 10% sodium sulfite or sodium iodide followed by sodium thiosulfate, 200 ml of 1 M sodium bicarbonate and 200 ml water. The chloroform extract is dried (MgS04) and evaporated in vacuo to a volume of ca. 10 ml. Addition of methanol (10 ml) followed by cooling of the mixture to —10° yields 0.8 gof 16a,17a-epoxide mp 109.5-110°. Additional product can be obtained by concentration of the mother liquor (total yield 80-90%). 

Perbenzoic acid and monoperphthalic acid are used in the same manner as MCPBA but a fresh solution of these reagents is usually required syntheses for these reagents can also be found in Fieser and Fieser s Reagents for Organic Synthesis. A microtechnique for perbenzoic acid epoxidation has also been described.  

Commercial 40% peracetic acid (containing 1% sulfuric acid) may be employed for this reaction. However, it is necessary to neutralize the sulfuric acid with sodium or potassium acetate to prevent further reactions. 

A solution of 17-cyanoandrosta-5,16-dien-3jS-ol acetate (46 g) and anhydrous potassium acetate (0.46 g) in methylene dichloride (310 ml) is treated with a mixture of 40% peracetic acid (37 ml) and anhydrous potassium acetate (1.84 g) in methylene dichloride (46 ml), the temperature of the solution being maintained below 25°. The mixture is stored at room temperature for 4 hr and then washed successively with water, 5% sodium bicarbonate solution (aqueous sodium bisulfite, 10g/150g water, has been used to decompose excess reagent before workup) and water until neutral. Evaporation of the dried solution and addition of ether gives 24.1 g of 5oc,6a-epoxy-17-cyanoandrost-16-en-3 -ol acetate mp 187-190°. One recrystallization from methanol gives 20.4 g of oxirane melting at 191-194°. 

Epoxidation of a, -Unsaturated Ketones with Alkaline Hydrogen Peroxide  

2-Decyl-5-methoxy-l-naphthol [Reduction of a Secondary Benzylic Alcohol to a Methylene Group with Concomitant Loss of a MOM Protecting Group].167 

Cyclohexane [Aluminum Chloride Catalyzed Reduction of a Dichloroal-kane to a Hydrocarbon].189 After a solution of m-l,2-dichlorocyclohexane (0.1582 g, 1.033 mmol) in CH2C12 (3 mL) was cooled to 0°, Et3SiH (0.299 g, 2.57 mmol) and A1C13 (0.0345 g, 0.173 mmol) were added. The mixture was stirred for 30 minutes and then quenched with water (10 mL). Heptane (23.1 mg, 0.231 mmol) was added as an internal standard and the aqueous layer was separated and extracted with CH2C12. The combined organic layer was dried (MgS04) and analyzed by GLC 0.064 g (74%). 

A mixture of ethyl dodecanoate (2.18 g, 10.0 mmol) and triethoxysilane (3.77 g, 23.0 mmol) was added to CsF (1.52 g, 10.0 mmol) under nitrogen. The reaction was followed by IR spectroscopy. After 30 minutes at 60°, 12 N HC1 (1 mL) in acetone (5 mL) was added. After 30 minutes, the mixture was extracted 

Dibenzyl Ether [Brpnsted Acid Promoted Reduction of an Aldehyde to a Symmetrical Ether].311 To a stirred solution of benzaldehyde (5.4 g, 0.05 mol) and TFA (11.4 g, 0.1 mol) under argon was added dropwise, with cooling, Et3SiH (8.1 g, 0.07 mol) at a rate such that the temperature of the reaction mixture did not exceed 40°. The solution turned a crimson color that gradually disappeared. Analysis by GLC showed the complete absence of the aldehyde immediately after addition of all of the silane. The products were separated by vacuum distillation at 20 Torr, collecting the fractions up to 125°. Dibenzyl ether was obtained from the residue by freezing out 4 g (0.02 mol, 80%) mp 3-6° nD25 1.5608. 

The hypobromite method for the quantitative estimation of the amount of urea in urine was developed about 1870. Alkaline hypobromite released nitrogen from urea, which was measured volumetrically  

The enzyme urease was discovered in soybeans by Takeuchi in 1909 it catalyzed the conversion of urea to ammonium carbonate. Jack beans were another excellent source of the enzyme. Jack bean powder could be stored for considerable periods and very active, soluble, urease extracted. After the action of urease, the ammonia could be estimated colorimetrically by Nesslerisation or titrimetrically. The Conway diffusion apparatus was specially developed for the estimation of urea titrimetrically and remained in use into the 1950s. 

In 1927, Van Slyke devised a micromethod using urease. Instead of determining ammonia released by alkali from ammonium carbonate, carbon dioxide was liberated after acidification. This was successfully 

Perfusion experiments before oxygenation problems were solved often gave incomplete or misleading information. Embden s work on fatty acid oxidation in liver (see Chapter 7) suggested acetoacetate was a normal metabolite, although in the intact animal free acetoacetate is only detected when glucose oxidation is impaired. 

This is a slight modification of the method of Fischer [1], D-Arabinose (250 g, 1.66 mol) is dissolved at room temperature in 37% hydrochloric add (230 mL) in a 1-L Erienmeyer flask, and cooled at once to 0°C. Technical ethanethiol (230 mL) is added, die flask is stoppered, and the two layers ate shaken vigorously. Copious crystallization occurs after 13 min and, after 30 min, the crude product is collected by filtration and washed with ice cold water Recrystallization from water affords the pure dithioacetal (380 g, 91%) mp 124-125°C, [a], 0° (c 3.0, pyridine). 

D-Xylase (30 g, 0.3 mol) is dissolved in 37% aqueous hydrochloric add (30 mL) in an Erienmeyer flask, and the solution is cooled to 0°C. Ethanethiol (50 mL) is added, the flask stoppered, and the triphasic mixture shaken at 0°C for 1 h. The resultant purple solution is 

Concentrated hydrochloric add (9.0 mL) is cooled to 0°C and saturated with hydrogen chloride gas. D-Riboee (3.0 g, 20 mmol) and benztaethioi (3.6 mL) are added, and the mixture is shaken for 2 h at 0°C and then for 20 min at room temperature. The solution is then poured into cold water (100 mL), and the resultant syrupis decanted from the water layer. This syrup it then dissolved in ethyl acetate (SO mL), the solution dried over sodium carbonate, and evaporated. After dissolving the syrup hi benzene (100 mL), die product crystallizes slowly (-2 days) at 0°C and is collected by filtration (3.0 g, 40%, collected in two crops). Recrystallization is effected from ethanol-ether and then ethanol-water to afford the pure diphenyl dithioacetal mp 101.3-102.0 0, [a] +423 (c 1, pyridine). 

D-Lyxoee (3.0 g, 20.0 mmol) and 1,2-ethanedithioi (1 08 mL, 10.0 mined) are placed in concentrated hydrochloric add (3.0 mL) and the mixture is shaken in a stoppered bottle for 10 min at room temperature. The mixture is poured into ice water (20 mL), and the homogeneous solution is passed through a column (1.8 x 20 cm) of anion-exchange resin 

Freshly fused zinc chloride (8.0 g) is dissolved in ethanethlol (GO mL), which has previously been dried, in a stoppered flask. The solution is cooled in an ice-salt bath and anhydrous sodium sulfate (15 g) and 1,3,4,5,fr-penta-O-acetyl-kero-D-fructose (20 g, 51.3 mmol) is added with shaking. The flask is stoppered and then stored in the freezing mixture for 4 h. The mixture is then poured carefully into saturated sodium hydrogencarbonate solution (-150 mL). The resultant precipitate is filtered off and extracted into warm chloroform the original filtrate is also extracted with chloroform. The combined extracts are dried and evaporated to a syrup, from which petroleum ether is evaporated repeatedly until crystallization occurs. The solid can be recrystallized from ether-petroleum ether (10.9 g, 43%), mp 76-78°C (83 C after further recrystallization), [a] +20 (c 3.7, chloroform). 

100 cc. of 48% hydrofluoric add and 260 cc. of water in a platinum dish, Which is then heated on the water bath. The mixture is stirred and heated until a dry, sandy powder is obtained. This powder is immediately scraped off the walls, crushed in the bottom of a platinum crudble, and then heated for an hour on the water bath. The salt must be removed from the dish and stored immediately in tightly stoppered copper or resin containers. The-yield is about 80 g. Analysis indicates the product to be essentially pure mercurous fluoride. The use of organic solvents for washing and drying does not simplify the process, and the use of chemical reagents inferior to the chemically pure grade causes complications. 

Preparation of Antimony Trifluorodichloride (SbF3Cl2). This is made in the steel reaction vessel, described on p. 59. A known quantity of antimony fluoride is placed in the vessel the vessel is evacuated, the needle valve is closed, and the whole is weighed. Connection is established to a chlorine cylinder, and the needle valve is opened to permit qhlorine to fill the vessel. Part of it is absorbed rapidly by the salt, with evolution of heat. Soon the reaction slows down as indicated by the rate of pressure fall when the needle valve is dosed. Weighing indicates the amount of chlorine present in the vessel. When the absorption practically ceases, the valve is closed, and the connection with the chlorine tank is removed. The reaction vessel is alternately heated gently, then allowed to cool in order to permit SbFsCl2, which is a viscous liquid, to flow and expose fresh surfaces of crystalline antimony trifluoride. The operation is ended after the absorption of the desired quantity of chlorine. 

Adult male Wistar rats (Charles River, Calco, Como, Italy) were housed under controlled environmental conditions with ambient temperature of 22 °C, relative humidity of 65%, and 12 h light 12 h dark cycle, with free access to food and water. 

Mercaptosuccinic acid (1.5-150 mg/kg, Sigma-Aldrich, Milan, Italy) or vehicle (0.01 M phosphate buffered saline (PBS), 1 ml/kg) were administered i.p. 15 min or 1 h before MCAo, or at the onset of reperfusion. 

All the experimental procedures were carried out in accordance with the European Community Council Directive on 24 November, 1986 (86/609/ EEC), included in the D.M. 116/1992 of the Italian Ministry of Health. All efforts were made to minimize the number of animals used and their suffering. 

To allow reperfusion, rats were briefly reanaesthetized with isoflurane, and the nylon filament was withdrawn 2 h after MCAo. After the discontinuation of isoflurane and wound closure, the animals were allowed to awake and were kept in their cages with free access to food and water. 

Cerebral blood flow (CBF) was monitored in the cerebral cortex of the ischemic hemisphere corresponding to the supply territory of the middle cerebral artery by laser-doppler flowmetry (DRT4, Moor Instruments, Devon, UK). To this aim, a rectangular bent laser-doppler probe was glued onto the parietal bone (2 mm posterior and 5 mm lateral from bregma) and local CBF was continuously measured from 20 min before the onset of ischemia until 10 min after reperfusion, keeping the animal under isoflurane anaesthesia. Flow values were collected every 5 min before MCAo and after reperfusion whereas data were collected at 10 min intervals during occlusion. 

Nevertheless a compromise must be reached between the optimal reaction conditions and the stability of the biological preparation and most crosslinking experiments with imidates have been performed in the range pH 8 to 8.5 with high concentrations of reagents (e.g. Kiehm and Ji, 1977 Ji et al., 1980 Rinke et al., 1980 Markwell and Fox, 1980). Similar dilemmas often arise with other reagents. 

Two-dimensional gel electrophoresis is the method of choice for analysing the products of crosslinking experiments. The usual one-dimensional electrophoretic techniques are rarely useful except in the simplest cases, Huang and Richards (1977), for example, used slab gels to follow the 

It will be noticed that in this, and in all other examples of photochemical crosslinking, that crosslinking is far from complete and it seems that a substantial proportion of the photogenerated intermediates must react with buffer components or water, or form highly unstable bonds. Intramolecular crosslinks may be reflected in spots above the diagonal or worse as streaks in the first dimension (Huang and Richards, 1977). 

Since all novel furans 95 and pyrroles 98 exhibit a strong blue fluorescence with considerable Stokes shifts, where the absorption maxima are found in the range 7.max, abs = 312-327 nm and the emission occurs at 7,max at,s = 401-451 nm, this multi-component approach to fluorophores can be exploited for combinatorial optimization of emission properties. 

A mixture of the methylthioiminium salt 13 (0.04 mmol) and the rhodanine 14 (0.40 mmol) in a filter tube, capped with a septum at the bottom, was suspended in acetonitrile (1.6 mL). To the mixture was added NEt3 at room temperature and 

To a mixture of 2,2-diphenyldimethyl-(2-pyrimidyl)vinylsilane (42) (95.6 mg, 0.30 mmol), 4,4 -diiodobiphenyl (41.1 mg, 0.10 mmol) and PdCl2(PhCN)2 (3.9 mg, 10.2 pmol) in dry THF (0.8 mL) was added a solution of Bu4NF (0.30 mmol, 1.0 M) in THF at room temperature. The mixture was stirred at 60 °C for 4 h under argon. After cooling the reaction mixture to room temperature, the catalyst and salts were removed by filtration through a short silica gel pad (EtOAc). gel permeation chromatography (CHC13) of the crude mixture afforded 47.6 mg (92%) of the extended jt-system 44 as pale-yellow solid. 

A thiazole 56 (0.05 mol) or a methylene base 57 (0.05 mol), a hydroxypyridone (60) (0.05 mol) and dimethylformamide (0.075 mol, 5.5 g) were heated at 90°C in acetic anhydride (20-30 mL) for about 3 h. The solid that precipitated upon cooling to room temperature was filtered off, washed thoroughly with 2 -propanol and/or aqueous ethanol until the color of the filtrate changed from violet to red and subsequently dried in a vacuum-drying cabinet at 50 °C. For physical characterization, the dyes were recrystallized from acetic anhydride, toluene or toluene-hexane mixtures. 

One-pot, three-component synthesis of the push-pull chromophore 87e by a Sonogashira coupling-aminovinylation sequence [84] 

A linear duplex DNA at a concentration of 5 p.mol in 10 pA of exonuclease III buffer (70 mM Tris-HCl, pH 8.0, 1.0 mM MgCl2, 10 mM dithiothreitol) is degraded at an approximate rate of 500 base pairs/hour/duplex end at 20°C using an enzyme concentration of 0.5 units//d of exonuclease III (Smith, 1980). One unit of enzyme activity is as described by Richardson et al. (1964). Usually the DNA to be sequenced will be a linear duplex of approximately known length derived from a restriction digest. Digestion may be 

It is then redissolved in water or 5 mM Tris-HCl, pH 7.6 to the appropriate concentration for the annealing step or 3 -end blocking reaction. 

3 -end blocking (necessary except where a limit Exo III digest is used) 

The restriction fragment in question is annealed to the exonuclease Ill-prepared template as follows  

This is carried out as described previously (Section 3.1.2.). Two microlitres of the annealed DNA solution are dispensed into five capillary tubes and one microlitre of the different reaction mixes (NTP° mixes) added as before except that the C° mix is added to two of the capillaries. Chain termination in one of the C° capillaries is brought about by the addition of 1 p of 40 mM arabinosyl-dCTP. The appropriate amounts of ddNTP s are added to the other four capillaries and the extension and chase reactions carried out as normally (Section 3.1.2.). If subsequent cleavage of the primer is not required the reactions are terminated by the addition of 1 /xl of 0.2 M EDTA and the sample prepared for loading on the gel. 

Most of the cationic polymerizations and the polymer syntheses thereby, discussed in Chapters 4 and 5, may be carried out conveniently under the dry and inert gas atmosphere (nitrogen or argon) by the so-called syringe technique. Except for highly elaborated kinetic experiments, stringent high-vacuum technique is not required to maintain the control of the polymerizations and polymer architectures. 

All monomers and solvents should be distilled at least twice over calcium hydride. For vinyl ether monomers, see Section VII.A.2. Immediately after the distillation, the monomers are sealed in brown glass vials under dry nitrogen and stored in a refrigerator. The final cut of the distilled solvent is collected over 4A molecular sieves in a glass flask equipped with a three-way stopcock and stored in a desiccator rubber septa may 

Alkyl vinyl ethers (CH2=CH—OR R = ethyl or higher alkyl) are washed successively with 10% aqueous sodium hydroxide solution and deionized water and distilled at least twice over calcium hydride. The final cut is distributed into small brown ampoules under dry nitrogen and sealed immediately before being stored in a refrigerator. The following show some physical properties needed for experiments  

This monomer is prepared by the substitution reaction of 2-chloroethyl vinyl ether (CEVE) with sodium acetate in the presence of a phase-transfer catalyst (tetra-n-butylammonium iodide) [17]. All reagents are of commercial sources and employed without further purification except for vacuum drying when necessary. 

In a 500-mL, three-necked, round-bottomed flask equipped with a reflux condenser, a Teflon paddle stirrer, and a drying tube (calcium chloride), and a thermometer are placed CEVE (240 mL, 2.4 mol), sodium acetate (82 g, 1.0 mol), and tetra-n-butylammonium iodide (ca. 2 g). The mixture is stirred for 8 hr at 80-90° C in a water bath and cooled to room temperature. The resulting sodium chloride is filtered off and extracted with 200 mL diethyl ether. The ether extract is combined with the reaction mixture, and the ether and unreacted CEVE are removed by evaporation. 

Image formation is a crucial step in image analysis. Quantitative image analyzers consist of a high linearity television camera that can be interfaced with a microscope, macroviewer or videotape. An electron probe interface 

Signals from the image received by the camera are processed by a central processing unit that contains circuits for measuring areas of features, number counts and size distributions based on selected diameters. Parameters such as ratio of maximum to minimum diameters may also be determined. The area under examination is displayed on a screen and interaction is either via a teletype keyboard or menu driven. Using this unit, objects can be selected for examination, objects can be deleted and touching particles can be separated. 

4 Block diagram of image analysis system, indicating the six major functions[ 117] 

Images require a great deal of computer memory because an image is actually an array of numbers i.e. intensity at every location 1 For 

A digital image has a discrete number of pixels (picture elements), each of which contains an intensity value, usually scaled from 0-255. The 

Backman and De Vries also filed nylon 66 submerged in liquid nitrogen using a small rotary Be. Exact details of the method employed were not provided, as is often the case in papers on grindit and milling. 

Several devices have been developed for the irtrsitu tensile testing of fibres and filaments. To combat the poor sensitivity of the spectrometers, it is usual to strain several fibres simultaneously. Verma and Peterlin looped nylon 6 fibres between two holders, so that the fibres passed through the cavity, with the holders outside the active zone. The holders formed sealed ends to suprasfl quartz tube which could be evacuated to 10 mm Hg. One holder was fixed, while the other holder was moved by a hand operated screw jack. No provision was made for simultaneously measuring load/deformation curves, which had to be obtained from conventional tensile tests on other fibres. 

Reference to Fig. 12 soon indicates that there are considerable experimental problems in conducting in-situ tensile tests. 

De Vries et give outline detail of a system they developed for a Varian 

E-3 spectrometer. A servo-hydraulic system was built which allowed loading of the samples in a wide variety of modes, and permitted tensile tests to be conducted at constant stress rate, at constant stress (creep), in cyclic fatigue, at constant strain rate, at constant strain or step strain. Provision was made for the simultaneous recording of stress-strain data and ESR spectra and a variable temperature control unit was employed. 

1 Reaction of 1-Alkenylboronates with Vinylic Halides Synthesis of (lZ,3E)-l-Phenyl-l,3-octadiene [176] 

Methyl 6-0-benzyl-2-deoxy-3-O-(phenylcarbamoyl)-2-phthalimido-l-thio-fi-D-glucopyrano-side (14) [51] 

Capozzi, G., Falciani, C., Menichetti, S., and Nativi, C., unpublished results. 

8 Selective Glycosidation Reactions and Their Use in Medicinal Chemistry 

A solution of 1 M BH3 in THF (10 mL) was added to a 50 mL dry flask containing compound 15 at 0°C and the solution was stirred for 5 min. A solution of 1 M Bu2BOTf in CH2C12 (1 mL) was then added slowly to the clear solution. After 1 h at 0°C,TLC showed that the starting material had disappeared. Triethylamine (0.5 mL) was then added to the reaction mixture followed by careful addition of methanol until the evolution of H2 had ceased. The reaction mixture was co-distilled with methanol three times before being put on the silica gel column. Elution with 1 1 hexane/ethyl acetate gave the pure 3,4-dibenzyl derivative 16. 

A mixture of the glycoside 17 (1 mmol) and dibutyltin oxide (1 mmol) in benzene was refluxed for 16 h with azeotropic removal of water. The solution was evaporated to ca. 25 mL, tetrabutylammonium iodide (1 mmol) and allyl bromide (0.5 mL) were added, and the mixture was heated at 60 °C for 8 h. Evaporation to dryness gave a residue which was processed by column chromatography on silica gel (chloroform/methanol, 95 5). Crystals (18, 85%), m.p. 105 °C (Et20), [a]D -20° (2.0, dichloromethane). 

The use of imprinted polymers for radioimmunoassays has also been described [74, 82,160]. In this case, imprinted polymers were used instead of antibodies. It is clear that these compounds cannot compete with monoclonal antibodies with regard to selectivity, but they are much easier to prepare and might therefore find application in several cases. 

Reactions inside imprinted cavities are another interesting area. Of great importance to the field is catalysis with imprinted polymers and imprinted silicas. For a broader application of molecularly imprinted polymers further improvement of the method will be necessary. The following problems are in the forefront of investigation today  

Direct preparation of microparticles by suspension or emulsion polymerization. This problem has already been discussed. 

Imprinting with high-molecular-weight biopolymers or even with bacteria. This is difficult high-molecular-weight compounds cannot be extracted from a highly crosslinked bulk polymer, and therefore a type of surface imprinting has to be applied. 

Development of new and better binding sites in imprinting, as has been indicated in Section 2.4.3. 

Bujfers Tris-HCl and potassium phosphate buffer (or phosphate-buffered saline, PBS) are used for the microsomal stability assays, while PBS is often the choice for the metabolism in hepatocyte suspensions. 

These various in vitro systems each have value for certain applications and provide information that might be used to predict metabolic stability in vivo. 

Nevertheless, 1 and 10 xM are often arbitrarily selected as the initial concentrations for metabolic stability assays (MacKenzie et al., 2002 Obach and Reed-Hagen, 2002). The effects of organic solvents on enzyme activities have been carefully investigated (Busby et al., 1999 Chauret et al., 1998 Easterbrook et al., 2001). For the purpose of data comparability for enzyme activities, the levels of organic vehicles should, in principle, be kept as low as possible, and consistent in all incubations in a given experiment. Dimethyl sulfoxide (DMSO) and methanol (or acetonitrile), the most commonly used vehicle solvents, should be kept at levels equal to, or preferably less than, 0.2 and 2% (v/v), respectively (Easterbrook et al., 2001 Hickman et al., 1998). 

Studies on metabolic stability using hepatocyte suspensions are not feasible for automation/HTS, but these studies do provide rather complete profiles of hepatic biotransformation without the supplements of cofactors and cosubstrates. The use of S9 in metabolic stability studies can be evaluated in a manner similar to that used for the microsomal assays, but with the possible addition of a broader panel of cofactors or cosubstrates. These include NADPH for CYP/FMO-mediated reactions, NADH for xanthine oxidoreductase and quinone oxidoreductase 2, NADPH-dependent reductions by carbonyl reductases, and NADPH/NADH-dependent reductions catalyzed by aldo-keto reductases, uridine 5 -diphosphate 

Some of these potential factors will be further diseussed when appropriate. 

Sheets of EVAc (ethylene-vinyl acetate, of type 28-40 with 28% vinyl acetate and a melt index of 40) are used (Atochem). The thickness of the sheets is around 0.05 cm when they are free from liquid. Sheets of 3 x 3 x 0.051 cm are immersed in n-heptane (density = 0.684 g/cm. As the thickness of these sheets is smaller than the other dimensions, the effect of transfer through the edges is negligible, and all the diffusing substance enters through the plane faces. 

The sheets are immersed in the liquid, and the kinetics of absorption followed either by weighing at intervals or by measuring the dimensions. The values obtained for the sample are given in the Table 7.3 [15]. 

Volumic expansion factor Linear expansion factor Dimensions (cm X cm x cm) Diffusivity (cmVs) 

Two other important characters of SEIRA should be addressed. First, the enhanced surface EM field around the metal particles is essentially polarized along the surface normal at any point on the particles, as shown by the small arrows in Fig. 8.3 [25]. Consequently, only the vibrations that give transition dipole components perpendicular to the local surface can be excited. The surface selection rule can be explained also by the interaction of the adsorbate dipole with its image induced in the metal the adsorbate dipole that is perpendicular to the surface constructively interacts with its image dipole to enhance the absorption, while the adsorbate dipole that is parallel to the surface destmctively interacts with its image dipole to reduce the absorption [26]. The surface selection rule is identical to that in IRAS [27] and the orientations of adsorbed molecules can be elucidated by using this rule, as will be described in more detail later. 

The second issue is that the distance dependence of the enhanced electric field is approximately proportional to 1/r (where r stands for the distance from the point dipole induced in a metal particle p) [25]. The interaction between adsorbed molecules and metal particles is also a ftinction of 1/r. Therefore, the enhancement is expected to be a function of 1/r . That is, the enhancement is relatively short ranged and is mainly confined to the adsorbed molecules. 

The SEIRA spectra can be simulated by using effective medium theories and the Fresnel equations [8-11, 17, 19, 24). Such simulations predict that (i) the SEIRA effect is not limited to coinage metals and can also occur on most transition metals, (ii) the enhancement factor is primarily a function of the size, shape, and proximity between the metal particles, and (iii) the band shapes of the enhanced absorption depend on the morphology of the metal film. These predictions have been well confirmed by experiments. 

Materials. Alpha cellulose (4% pentosans) and amylose (70%) were obtained from Sigma France. Starches from all other sources were kindly supplied firom INRA Nantes, France. Vegetal oils were obtained fixrm Sidobre-Sinova (France). Other chemicals were of reagent grade and were purchased from usual providers and were used without further purification or treatment. 

Esterification reaction. A homogeneous mixture of polysaccharide (cellulose or amylose), water or ethanol, soap (added or created in situ) and fatty (octanoic) acid was obtained by emulsification at 2000 rpm using a high speed stirrer (homogenizer). Water or ethanol were then distilled off at 130°C for 30 min followed by the esterification reaction at 195 C for 2-6 hr. 

Degree of substitution (DS). 0.5 g of purified sample was stirred for 30 min in 40 ml of aqueous ethanol (70%). After addition of 20 ml of a 0.5 N NaOH aqueous solution, the stirring was continued for 48 h at 50 C. The unreacted NaOH was back-titrated with 0.5 N aqueous HCl. The solid was recovered by filtration and thoroughly washed with deionized water and ethanol, then oven-dried at 50°C for 48 h. The absence of ester functions in the saponified solid was confirmed by FTIR spectroscopy. Ester content was calculated as  

EC (%) = [ A-B) xNb- iP-C) X Na] X M/(10 x w), where A and B are respective volmnes of NaOH solution added to sample and blank (ml) Nb and Na are respective normality of NaOH and HCl solutions D and C are respective volumes of HCl added to sample and blank (ml) M is the molecular weight of the grafted acyl residue and w is the weight of sample (dry basis in g). 

Recovery yield (RY). The RY is defined as the ratio of the precipitated fi action to the theoretical total cellulose ester. It is assumed that the DS of the non-precipitated part is the same as that of the precipitated fiaction. The RY is calculated as  

Data presented herein was derived from a combination of handmix and high pressure impingement-mixing machine produced foam. Foams were prepared using several general types of formulations for toluene diisocyanate (TDI) and two general types of formulations for methylenediphenyl diisocyanate (MDI) which are representative of currently utilised formulations in the automotive interior component industry. In addition, an all water blown formulation was used to represent the flexible slabstock industry. 

The mobile phase used in most high-temperature SEC is toxic, and handling operations must be carried out with considerable care. Polymer solution preparation and solvent distillation have to be carried out in a fume cupboard, and under a blanket of nitrogen. Addition of anti-oxidants is important to reduce oxidative degradation, and typically 200 ppm of Santanox-R is added to polymer solutions. 

Solution preparation on the Waters 150C can be carried out automatically by adding the weighed polymer sample directly to a sample vial. This is then 

In preparing solutions it is important that the solutions and the mobile phase are from the same source, and it is good practice to remove solvent from the SEC reservoir for this purpose. Spurious impurities in the solvent should not then interfere with the analysis. It is important to adopt a rigorous 

Standard of purity for the mobile phase, if SEC is to be used for extensive periods at high temperature, and column lifetimes are to be acceptable. Depending on the solvent, this can involve prior purification, but drying, fractional distillation under nitrogen and passing through a 0.5/im filter must be considered the very minimum. 

The maximum concentrations which can be injected without peak broadening and change in elution volume are listed for various injection volumes and molecular weights in Table 4.1(d). These values vary with column characteristics and are not transferable, but they illustrate how the column loading must be substantially reduced as the molecular mass of the sample increases. It arises from the reduction in pores within the gel which separate higher-molecular-mass species, and also because of localized viscosity effects. 

The stereochemistry observed during the reaction was most likely established during the formation of the Ni species 243, where the chiral ligands would exert their influence on the alkyl radical during the formation of the new stereogenic center. 

To a 1-dram vial was charged with anhydrous powdered K3PO4 (670 mg, 3.16 mmol, 7.2 equiv). The reaction vessel was flamed dried and cooled down to room temperature under N2. 4-Methoxyboronic acid (268 mg, 1.76 mmol, 4.0 equiv), NiCl2(PCy3)2 (30 mg, 0.0439 mmol, 10 mol%), and phenyl diethylcarbamate (85 mg, 0.439 mmol, 1.0 equiv) were then added and the reaction vessel was evacuated and refilled with N2 three times. Toluene (1.5 ml) was added to the reaction mixture, and the mixture was stirred at room temperature for 1 h followed by heating at 130 °C for 24 h. After heating, the reaction mixture was cooled to room 

To evaluate the degree of clay exfoliation in the polymer which is essential for property enhancement, XRD measurements were carried out in a Rigaku D/MAX 2200 X-ray diffractometer with CuKa radiation (X = 1.54 A) with a scanning speed of 1 °/min and operating at 40 kV and 30 mA. During the XRD experiments, the samples were analyzed in the reflection mode. 

2 Weight change and surface morphology upon conditioning 

GFRP samples were weighed with a Mettler AT250 digital balance (precision 0.01 mg). The percent weight change as a function of time was calculated using equation [21.1]  

A Unitron ZST optical microscope (OM) and a JEOL JSM 5800 scanning electron microscope (SEM) were used to study the effect of exposed conditions on neat and nanoclay-incorporated GFRP samples. The gradual change in color after the exposed conditions was evaluated using an image analyzer. 

Photographs were taken of the exposed specimens, and the luminance values were calculated using the standard RGB (red, green, blue) system. After selecting a 4 mm x 3 nun region of interest (ROI), the luminance value of about 3000 average pixels in the ROI was estimated. 

A number of other methods (chronopotentiometry [24], polarography with dropping electrolyte electrode [25], faradaic impedance measurement [26], current scan voltammetry [27] etc.) were also applied to the study of electrolysis at ITIES. 

Alkylation under strongly basic conditions (anionic benzylation). 

The use of a dipolar aprotic solvent (DMF) enhances the nucleophilicity of the alkoxide by solvating the metal counter-ion. 

Round bottomed flask (100 ml) with rubber septum and magnetic stirrer bar Source of inert gas Syringes (10 and 20 ml) 

Preparation of methyl-4-0-benzyl-2-deoxy-3,6-di-0-pivaloyl-2-trichloroaceta-mido- (3-d -galactopyranoside. 

For the equilibrium experiments, a well prepared mixture of master salt and master alloy (as described in Section 6.1.3.3) according to the CuCl2/Hf ratio (1-3 stoichiometric) was charged in an alumina crucible, and placed in a carbolite electrical resistant tube furnace under a purified argon atmosphere. The master alloy 

Sample CuClj (wt%) NaCI (wt%) CaClj (wt%) LiCI (wt%) MgClj (wt%) CuCl2/Hf stoichiometric ratio 

The samples were placed in small Alsint crucibles which were inside a larger crucible. In this way, the same experimental conditions such as temperature and atmosphere could be guaranteed for the different salt/metal (CuCl2/Hf) ratios. The crucible was placed in a gas-tight chamber furnace. The samples were heated to 850 °C and maintained at equilibrium temperature for 4h. After cooling to room temperature, the metal phase was separated from the salt and cut into smaller pieces of about 1 -3 g for analysis. These pieces were dissolved in a combination of 10 ml hydrofluoric acid and 20 ml nitric acid, made up to 100 ml with demineralised water. The leachate was filtered and then analysed with ICP-OES using a PerkinElmer Optima 5300DV. 

The equilibrium conditions and results are given in Table 6.1.3. The hafnium removal efficiency (q) is determined as the relative difference of Hf concentration in the alloy before and after salt extraction compared to the original Hf concentration, as shown in Equation 6.1.9  

Remark The reacted samples are named after the salt system and the ratio of CuClj in salt to Hf in master alloy relative to stoichiometric (S/M), 

Unless otherwise noted, all operations were carried out under a dry, oxygen-free N2 atmosphere. Molecular weight analyses were performed using two 30 X 75 cm GPC columns (10 A 10 p and 500 A 5 p) eluted with THE at 60 °C (flow rate 1.0 mL/min). Molecular weight results were based on eight polystyrene standards (M = 52000, 30300, 9200, 7000, 5050, 2950, 1060, and 

Compound 27. See the preparation of 21 for the synthetic protocol. Used were the 20/23 coupled product (0.22 g, 0.17 mmol), MeOH (5 mL), CH2CI2 (5 mL), and K2CO3 (1.42 g, 10.3 mmol) for 5 h. No purification was necessary to afford 0.20 g (96 %) of the title compound as yellow-orange solid that, due to its oxidative instability, was carried on immediately for the preparation of 29. 

2 Iterative Approaches to oligo(l,4-phenylene ethynylene)s Molecular Wires, Properties and Experimental Details 

The hardness of conventional Cr films (unannealed) implanted with N at 90 keV, as a function of the total ion dose and the load, is shown in Fig. 19. For 

Studies of the combination of coating and ion implantation have been per-fonned with two kinds of Cr layers, both implanted with N ions. It has been shown that N implantation of both conventional and ABCD films results in an increase in the near-surface hardness of the Cr layers. The extent of this increase was greater for those films of both types that had been annealed at 400 C. AES depth profile analysis showed that the concentration of N in the implanted layer should not exceed 40 at.%. Implantation beyond that amount led to a broadening of the nitrogen profile. Analysis of film composition of the implanted Cr layers showed that the films consisted of Cr, C and N in the case 

This example emphasizes that it is important for the understanding of changes in tribological performance after ion implantation to analyze the compositions of the altered layers by methods such as AES or XPS. 

The control apparatus would typically consist of a potentiostat with a sufficiently large current output to support the total photoelectrochemicai process. Most examples of photoelectrochemicai processing are carried out at constant potential, but some examples exist of galvanostatic control. The course of the photoelectrochemicai process is monitored as the Integrated current, which may be related directly to the amount of etched or deposited material. A coulometer or integrating computer may be used for this purpose. 

Source Spectral Range (nanometers) Major Lines (nanometers) 

Prior to DSC and thermomicroscopic measurements, gas chromatography analyses were carried out for both palm oil and rapeseed oil methyl esters. 

Blends of palm oil methyl ester and rapeseed oil methyl ester with diesel fuel (DF) have been realized on a gravimetric basis. Blend ratios were 0, 10, 20, 30 and 100%. 

Palm and rapeseed biodiesels were mixed with cold flow improvers (additives) after adding them to DF. The additives were mixtures of ethylene vinyl acetate (EVA) copolymers and naphthenic distillates. 

DSC measurements were carried out using a DSC 820 Mettler-Toledo apparatus. Calibrations for temperature and enthalpy were performed using the melting point 

For each scan, approximately 20 mg of sample was hermetically sealed in a 40 p,L aluminum pan and tested against an empty pan. Two scans (heating and cooling) have been run for each sample. For the heating run, the samples were cooled and held isothermally at -150 °C for 2 min before heating to 50 at 5 C/min, while for 

This biosensor allows experiments to be organized in different ways. The choice can be made as to which interacting partner to immobilize on the chip matrix and which to inject in solution. Different immobilization strategies may be applied, and both purified samples or extracts can be used for the measurements. Interaction analyses are either performed by direct binding to the immobilized molecule, or as an inhibition assay with both partners free in solution. 

With this flexibility, the easy handling of the instruments, and a wide diversity of standardized protocols, each user has the opportunity to immediately start their analysis. On the other hand, many assays can be carried out in different ways. Therefore, it is recommended to obtain a general view of the technology and to clearly define the goal for each measurement, in order to structure an analysis in the best way. 

mylitta. Tassar is a multivoltine type of silk and is mostly produced by tribal by rearing silkworms on forest plants Terminalia arjuna, Terminalia tomentosas and Shorea robusta). Tassar silk fibre has its own distinctive colour and is coarse to feel but has higher tensile strength, elongation and stress-relaxation values than the mulberry silk fibre secreted by Bombyx mori. 

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It is not uncommon for this situation to apply, that is, for a Gibbs mono-layer to be in only slow equilibrium with bulk liquid—see, for example. Figs. 11-15 and 11-21. This situation also holds, of course, for spread monolayers of insoluble substances, discussed in Chapter IV. The experimental procedure is illustrated in Fig. Ill-19, which shows that a portion of the surface is bounded by bars or floats, an opposing pair of which can be moved in and out in an oscillatory manner. The concomitant change in surface tension is followed by means of a Wilhelmy slide. Thus for dilute aqueous solutions of a methylcellu-... 

The experimental procedure used by Hansen and co-workers involved the use of a loudspeaker magnet to drive a rod touching the surface (in an up-and-down motion) and... 

Everett and co-workers [141] describe an improved experimental procedure for obtaining FJ quantities. Some of their data are shown in Fig. XI-10. Note the negative region for n at the lower temperatures. More recent but similar data were obtained by Phillips and Wightman [142]. 

The selection of the operating principle and the design of the calorimeter depends upon the nature of the process to be studied and on the experimental procedures required. Flowever, the type of calorimeter necessary to study a particular process is not unique and can depend upon subjective factors such as teclmical restrictions, resources, traditions of the laboratory and the inclinations of the researcher. 

Unfortunately, in most cases not all the available information on a reaction is given in the reaction equation in a publication, and even less so in reaction databases. To obtain a fuller picture of the reaction that was performed, the text describing the experimental procedure in the publication or a lab journal) would have to be consulted. Reaction products that are considered as trivial, such as water, alcohol, ammonia, nitrogen, etc., are generally not included in the reaction equation or mentioned in the text describing the experimental work. This poses serious problems for the automatic identification of the reaction center. It is highly desirable to have the full stoichiometry of a reaction specified in the equation. 

Method 3 (F. Adickes, 1930). The experimental procedure is similar to that described in Method 2 except that excess of ethyl formate (b.p. 

The experimental procedure to be followed depends upon the products of hydrolysis. If the alcohol and aldehyde are both soluble in water, the reaction product is divided into two parts. One portion is used for the characterisation of the aldehyde by the preparation of a suitable derivative e.g., the 2 4-dinitrophenylhydrazone, semicarbazone or di-medone compound—see Sections 111,70 and 111,74). The other portion is employed for the preparation of a 3 5-dinitrobenzoate, etc. (see Section 111,27) it is advisable first to concentrate the alcohol by dis tillation or to attempt to salt out the alcohol by the addition of solid potassium carbonate. If one of the hydrolysis products is insoluble in the reaction mixture, it is separated and characterised. If both the aldehyde and the alcohol are insoluble, they are removed from the aqueous layer separation is generally most simply effected with sodium bisulphite solution (compare Section Ill,74),but fractional distillation may sometimes be employed. 

Alternatively a mixture of 90 g. of sodium benzenesulphonate and 60 g. (36 ml.) of phosphorus oxychloride may be used. The experimental procedure is identical with that for phosphorus pentachloride, but the yield is slightly better. 

The following experimental procedure is suitable for ketones boiling above 175-200°. 

In considering the differential energy of adsorption, it is useful to picture an experimental procedure which allows the adsorption to proceed at constant temperature and in infinitely small stages. Then... 

Mercury porosimetry is generally regarded as the best method available for the routine determination of pore size in the macropore and upper mesopore range. The apparatus is relatively simple in principle (though not inexpensive) and the experimental procedure is less demanding than gas adsorption measurements, in either time or skill. Perhaps on account of the simplicity of the method there is some temptation to overlook the assumptions, often tacit, that are involved, and also the potential sources of error. 

A vast amount of research has been undertaken on adsorption phenomena and the nature of solid surfaces over the fifteen years since the first edition was published, but for the most part this work has resulted in the refinement of existing theoretical principles and experimental procedures rather than in the formulation of entirely new concepts. In spite of the acknowledged weakness of its theoretical foundations, the Brunauer-Emmett-Teller (BET) method still remains the most widely used procedure for the determination of surface area similarly, methods based on the Kelvin equation are still generally applied for the computation of mesopore size distribution from gas adsorption data. However, the more recent studies, especially those carried out on well defined surfaces, have led to a clearer understanding of the scope and limitations of these methods furthermore, the growing awareness of the importance of molecular sieve carbons and zeolites has generated considerable interest in the properties of microporous solids and the mechanism of micropore filling. 

Designing an experimental procedure involves selecting an appropriate method of analysis based on established criteria, such as accuracy, precision, sensitivity, and detection limit the urgency with which results are needed the cost of a single analysis the number of samples to be analyzed and the amount of sample available for... 

What criteria were considered in designing the experimental procedure ... 

Following the movement of airborne pollutants requires a natural or artificial tracer (a species specific to the source of the airborne pollutants) that can be experimentally measured at sites distant from the source. Limitations placed on the tracer, therefore, governed the design of the experimental procedure. These limitations included cost, the need to detect small quantities of the tracer, and the absence of the tracer from other natural sources. In addition, aerosols are emitted from high-temperature combustion sources that produce an abundance of very reactive species. The tracer, therefore, had to be both thermally and chemically stable. On the basis of these criteria, rare earth isotopes, such as those of Nd, were selected as tracers. The choice of tracer, in turn, dictated the analytical method (thermal ionization mass spectrometry, or TIMS) for measuring the isotopic abundances of... 

Numerous examples of standard methods have been presented and discussed in the preceding six chapters. What we have yet to consider, however, is what constitutes a standard method. In this chapter we consider how a standard method is developed, including optimizing the experimental procedure, verifying that the method produces acceptable precision and accuracy in the hands of a single analyst, and validating the method for general use. 

Our objectives in this section are twofold to describe and analyze a mechanical model for a viscoelastic material, and to describe and interpret an experimental procedure used to study polymer samples. We shall begin with the model and then proceed to relate the two. Pay attention to the difference between the model and the actual observed behavior. 

All of the experimental procedures we have discussed in this chapter yield, among other things, information concerning the average molecular weight of a... 

This chapter is the narrowest in scope of any chapter in this book. In it we discuss a single experimental procedure and its interpretation. It is appropriate to examine light scattering in considerable detail, since the theory underlying this method is relatively unfamiliar to students and the interpretation yields information concerning a variety of polymer parameters. 

The experimental procedures depend to a large extent on the use to which the explosive is to be put. Comparison is often made to proven explosives of known performance. Many of the most commonly used tests in the various categories of concern are as follows ... 

It is experimentally easy to generate Raman spectra using polarized light and to observe the partial depolarization of the spectra. Bands of totally symmetric vibrations are strongly polarized in Hquid or solution spectra. AH other bands in Hquid or solution are depolarized. Polarization effects are essential to elucidate stmctures, but are usuaHy ignored in most other appHcations. Details of the theory and experimental procedure can be found in the Hterature (15,16). 

Experimental procedures have been described in which the desired reactions have been carried out either by whole microbial cells or by enzymes (1—3). These involve carbohydrates (qv) (4,5) steroids (qv), sterols, and bile acids (6—11) nonsteroid cycHc compounds (12) ahcycHc and alkane hydroxylations (13—16) alkaloids (7,17,18) various pharmaceuticals (qv) (19—21), including antibiotics (19—24) and miscellaneous natural products (25—27). Reviews of the microbial oxidation of aUphatic and aromatic hydrocarbons (qv) (28), monoterpenes (29,30), pesticides (qv) (31,32), lignin (qv) (33,34), flavors and fragrances (35), and other organic molecules (8,12,36,37) have been pubflshed (see Enzyp applications, industrial Enzyt s in organic synthesis Elavors AND spices). 

Thixotropy and Other Time Effects. In addition to the nonideal behavior described, many fluids exhibit time-dependent effects. Some fluids increase in viscosity (rheopexy) or decrease in viscosity (thixotropy) with time when sheared at a constant shear rate. These effects can occur in fluids with or without yield values. Rheopexy is a rare phenomenon, but thixotropic fluids are common. Examples of thixotropic materials are starch pastes, gelatin, mayoimaise, drilling muds, and latex paints. The thixotropic effect is shown in Figure 5, where the curves are for a specimen exposed first to increasing and then to decreasing shear rates. Because of the decrease in viscosity with time as weU as shear rate, the up-and-down flow curves do not superimpose. Instead, they form a hysteresis loop, often called a thixotropic loop. Because flow curves for thixotropic or rheopectic Hquids depend on the shear history of the sample, different curves for the same material can be obtained, depending on the experimental procedure. 

The role of yeast in fermenting dough maturation is even less clear. The alcohol and carbon dioxide developed during fermentation must influence the elastic properties of the protein matrix. However, experimental procedures that would permit this to be checked in the absence of yeast have not been developed. 

An automated system for clinical analysis consists of the instmment (hardware), the reagents, and the experimental conditions (time, temperature, etc) required for each deterrnination. The reagents plus the experimental conditions are sometimes referred to as the chemistry of the system. The chemistry employed is generally similar to that used in manual assays because most automated assay methods have been adapted from the manual ones. However, automated analy2ers rarely afford the flexibiUty of experimental procedure that is possible in manual analysis. 

These values make it evident that the contact angles must be observed rather carefliUy to obtain a value close to 90°. The following experimental procedure is practical to obtain good stabiUty. A container with the particles is placed on the bottom of an ofl-filled vessel with parallel walls, and a drop of the aqueous phase is placed on the powder. The shape of the droplet decides the action to be taken. 

Many reagents are able to chlorinate aromatic pyrazole derivatives chlorine-water, chlorine in carbon tetrachloride, hypochlorous acid, chlorine in acetic acid (one of the best experimental procedures), hydrochloric acid and hydrogen peroxide in acetic acid, sulfuryl chloride (another useful procedure), etc. iV-Unsubstituted pyrazoles are often used as silver salts. When methyl groups are present they are sometimes chlorinated yielding CCI3 groups. Formation of dimers and trimers (308 R = C1) has also been observed. 

Two reactions of the non-aromatic 4,4-disubstituted pyrazolones are worthy of mention. Carpino discovered that 4,4-dihalogenopyrazolones (365) and 4-substituted 4-halogenopyrazolones (366) when treated with bases yield a, 8-alkynic and -alkenic acids, respectively (66JOC2867). The reaction proceeds through an oxopyrazolenine (2,3-diazacyc-lopentadienone (367) (B-74M140408). A modification of the experimental procedure transforms (365) into bimanes (368) (82JOC214), which are formed from (367 R = X),... 

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