Filter, molecular

Phillips, S.C. Essex, J.W. Edge, C.M., Digitally filtered molecular dynamics the frequency specific control of molecular dynamics simulations, J. Chem. Phys. 2000,112, 2586-2597... 

Dauber-Osguthorpe, P., and Osguthorpe, D. J. (1990) Analysis of intramolcular motions by filtering molecular dynamics trajectories, 7. Am. Chem. Soc. 112, 7921-7935. 

D Complex filter Molecular properties that are more complicated to compute (basicity, acidity, drug-likeness, etc.) 0.1 to 10 s... 

The crystal suspension was filtered through a membrane filter of 0.45 yun (filtrate A). Part of the filtrate A was further filtered ti ugh an ultra filter (molecular mass cut off 100 kD) (filtrate B). The filtrate A included particles of thermolysin smaller than 0.45 im. The filtrate B mainly consisted of thermolysin molecules because the molecular mass of thermolysin is 34.6 kD. Both filtrates were analyzed by gel filtration lugh performance liquid chromatography (HPLC). In the analysis, the filtrates were adjust to pH 11.0 before use as sample solutions to dissolve the crystals which had precipitated in the filtrates after the filtration. 

Systems designed to vent the containment atmosphere and to filter molecular iodine from the vented flow are in service and a body of research results characterizing the effectiveness of these systems also exists. Application of the research data to other systems of different design is possible in principle. Retention capability of wet scrubbers for organic iodides are not well established. 

Two ATA activity peaks were found ATAi at pH 7.2 and ATA2 at pH 6.8. Active fractions of each were pooled and applied to a second polybuffer exchange column (0.7 cm x 20 cm) and eluted using the same conditions as described above except with a flow rate of 7.0 ml/hr. The active fractions were concentrated using a Mllllpore Immersible GX-10 filter (molecular weight cut off of 10,000). 

For high filtration efficiency, a fibrous material should have adequate characteristics needed to fulfill influential filter parameters. Such parameters include small diameter and high porosity which makes electrospun nanofibers attractive to the application [80, 81-83], Further studies revealed that filtration efficiency of air filters molecular filters and dust filter bags were improved using various polymers [84-85],... 

Figure Bl.19.28. Molecular-scale image (2 mu x 20 mu) of a barium arachidate bilayer. Image was produced by averaging six images, but without filtering data. (Taken from [135], figure 1.)...

Most practical implementations of drug-likeness use a computational model which takes as input the molecular structure, together with various properties, and predicts whether the molecule is drug-like or not. Some of these models may be very simple, such as a series of substructural filters. Only those molecules which pass all of these filters are output, Such filters can be used to eliminate molecules that contain inappropriate functionality. 

When an amine, or a solution of its hydrochloride, is added to an aqueous solution of chloroplatinic acid, a salt of the base with the cliloroplatinic acid, of general formula BjiHiPtCle (where B is one molecule of the base) is formed and usually crystallises out, for these chloroplatinates hai e normally a rather low solubility in cold water. The chloroplatinate can be filtered off, dried, and then analysed by direct ignition, when only the metallic platinum ultimately remains. Knowing the percentage of platinum in the chloroplatinate, the molecular weight of the latter, and hence of the constituent base, can readily be calculated. 

Picrates, Many aromatic hydrocarbons (and other classes of organic compounds) form molecular compounds with picric acid, for example, naphthalene picrate CioHg.CgH2(N02)30H. Some picrates, e.g., anthracene picrate, are so unstable as to be decomposed by many, particularly hydroxylic, solvents they therefore cannot be easily recrystaUised. Their preparation may be accomplished in such non-hydroxylic solvents as chloroform, benzene or ether. The picrates of hydrocarbons can be readily separated into their constituents by warming with dilute ammonia solution and filtering (if the hydrocarbon is a solid) through a moist filter paper. The filtrate contains the picric acid as the ammonium salt, and the hydrocarbon is left on the filter paper. 

To a solution of 0-5 g. of the salt in 5 ml. of water and 2-3 drops of O li hydrochloric acid (or to a solution of the acid treated as above), add a shght excess of a cold, 15 per cent, aqueous solution of benzyl-wo-thiourea hydrochloride (if the molecular weight of the compound is not known, use a solution of 1 g. of the reagent in 5 ml. of water), and cool in ice. Filter off the crystaUine derivative and recrystaUise it from 50 per cent, alcohol. 

Reflux gently in a test-tube under a short air condenser 1 g. of the base with 2 5 mols or 3 0 g. (3 0 ml.) if the molecular weight is unknown of redistilled acetic anhydride for 10-15 minutes. Cool the reaction mixture and pour it into 20 ml. of cold water (CAUl ION). Boil to decompose the excess of acetic anhydride. When cold, filter the residual insoluble acetyl derivative and wash it with a little cold water. Recrystal-/ise from water or from dilute alcohol. 

Treat 1 g. (1 ml.) of the amine with 4 mols of 10 per cent, sodium or potassium hydroxide solution (say, 20 ml,), and add 1 -5 mols (or 3 g. if the molecular weight is unknown) of benzenesulphonyl or p-toluenesulphonyl chloride in small portions with constant shaking. To remove the excess of acid chloride, either shake vigorously or warm gently. Acidify with dilute hydrochloric acid and filter off the sulphonamide. Recrystallise it from alcohol or dilute alcohol. 

Dissolve 0-5 g. of the phenol in 2 -5 ml. of pyridine, and add one equivalent of dlphenylcarbamyl chloride (or 0- 0-5 g. if the molecular weight is uncertain). Reflux the mixture for 30-60 minutes on a boiling water bath, and then pour into about 25 ml. of water. Filter the derivative, wash with a little sodium bicarbonate solution, and recrystallise from alcohol benzene, light petroleum (b.p. 60-80°) or carbon tetrachloride. 

Method 2. The procedure described under Benzenesulphonyl Chloride, Method 2 (Section IV,206) may be used with suitable adjustment for the difierence in molecular weights between sodium p-toluenesulphonate (Section IV,30) and sodium benzenesulphonate. When the reaction product is poured on to ice, the p-toluenesulphonyl chloride separates as a sohd. This is filtered with suction it may be recrystaUised from hght petroleum (b.p. 40-60°) and then melts at 69°. 

Method B. Place 125 g. (106 -5 ml.) of diethyl phthalate and 25 g. of molecular sodium (sodium sand see Section 11,50,6) in a 500 ml. round-bottomed flask fitted with a reflux condenser and dropping funnel. Heat the flask on a steam bath and add a mixture of 122 5 g. (136 ml.) of dry ethyl acetate and 2 5 ml. of absolute ethanol over a period of 90 minutes. Continue the heating for 6 hours, cool and add 50 ml. of ether. Filter the sodium salt (VI) on a sintered glass funnel and wash it with the minimum volume of ether. Dissolve the sodium salt (96 g.) in 1400 ml. of hot water in a 3-htre beaker, cool the solution to 70°, stir vigorously and add 100 ml. of sulphuric acid (3 parts of concentrated acid to 1 part of... 

MacroModel (we tested Version 6.5) is a powerful molecular mechanics program. The program can be run from either its graphic interface or an ASCII command file. The command file structure allows very complex simulations to be performed. The XCluster utility permits the analysis and filtering of a large number of structures, such as Monte Carlo or dynamics trajectories. The documentation is very thorough. 

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