Paper concentration

Method 2. Place a mixture of 126-5 g. of benzyl chloride, 76 g. of thiourea and loO ml. of rectified spirit in a 500 ml. round-bottomed flask fitted with a reflux condenser. Warm on a water bath. A sudden exothermic reaction soon occurs and aU the thiourea passes into solution. Reflux the resulting yellow solution for 30 minutes and then cool in ice. Filter off the white crystals and dry in the air upon filter paper. Concentrate the filtrate to half its original volume and thus obtain a further small crop of crystals. The yield of crude hydrochloric acid as in Method 1 the m.p. is raised to 150°, although on some occasions the form, m.p. 175°, separates. 

This paper concentrates on option (2), the modification of existing crops. The other options are assessed in more detail by Epstein et al. (1980), Malcolm (1983) and O Leary (1984). 

The presentation in this paper concentrates on the use of large-scale numerical simulation in unraveling these questions for models of two-dimensional directional solidification in an imposed temperature gradient. The simplest models for transport and interfacial physics in these processes are presented in Section 2 along with a summary of the analytical results for the onset of the cellular instability. The finite-element analyses used in the numerical calculations are described in Section 3. Steady-state and time-dependent results for shallow cell near the onset of the instability are presented in Section 4. The issue of the presence of a fundamental mechanism for wavelength selection for deep cells is discussed in Section 5 in the context of calculations with varying spatial wavelength. 

The n-hexane layer is dried with ca 50 g of anhydrous Na2S04, filtered fhrough a funnel fitted with a filter paper, concentrated to about 1 mL under vacuum below... 

C. 3-n-Heplyl-5-cyanocytosine. In a 250-ml. Erlenmeyer flask are placed 33.8 g. (0.145 mole) of 3-w-heptylureidomethylenemalononitrile and 70 ml. of methanol then 8.5 g. (0.16 mole) of sodium methoxide (Note 6) is added carefully in small portions (Note 7). The resulting solution is allowed to stand at room temperature for 3 days in the stoppered flask. The contents of the flask are dissolved in 300 ml. of cold water in an 800-ml. beaker, and the solution is stirred as 11 ml. of glacial acetic acid is added. The precipitated solid is collected by suction filtration on a Buchner funnel and washed with three 40-ml. portions of distilled water. The undried product is dissolved in 600 ml. of hot ethyl alcohol then the solution is filtered into a 1-1. flask by gravity through a fluted filter paper, concentrated on the steam bath to 200 ml., and cooled in the refrigerator for 4 hours. The 3-w-heptyl-5-cyanocytosine crystallizes in white needles, melts at 192-197° (Note 8), and amounts to 29.7-31.1 g. (88-92%) (Note 9). 

Amine-terminated, G3 (PAMAM) dendrimer, (0.316 g 45.7 moles) was dissolved in anhydrous methyl sulfoxide (5 ml) in a 100 ml round-bottom flask flushed with dry nitrogen. After dendrimer had completely dissolved, succinic anhydride (Aldrich) (0.363 g 3.6 mmol) was added to the reaction mixture with vigorous stirring, and the mixture was allowed to react for 24 h at room temperature. The product solution was diluted with deionized water, transferred to 3500 MWCO dialysis tubing (Spectrum) and dialyzed against deionized water (18 Mil) for 3 d. The retentate solution was clarified by filtration through Whatman No. 1 filter paper, concentrated with a rotary evaporator, and lyophilized to yield a colorless powder (0.435 g, 94%). The product was analyzed by 13C-NMR, FT-IR, SEC and MALDI-MS. The analytical data were consistent with the expected carboxylic acid-terminated product. 

Water of various degrees of purity is the normal heat transfer fluid employed and a number of important problems with modern boiler water circuits are markedly influenced by solution composition. Most problems arise where solutions can concentrate and the compositions of such solutions can only be obtained by calculation from thermodynamic data. This paper concentrates on the kind of aqueous phase data which are currently most needed. Many of the needs overlap with those of geochemical interest. However, since Barnes (3) has recently reviewed the latter field, specifically geochemical needs will not be discussed. "High temperature" in this paper is generally taken to mean within about 100°C of the critical point of water (374 C), though some important problems which occur at lower temperatures are also considered. 

This time, there were no polemics and no fight over priority (neither of the principals had Keknle s driving ambition to be the first and only inventor of the theory) - in fact, in his snbseqnent papers on stereochemistry, van t Hoff was careful to point out Le Bel s contributions, and may have saved them from obscurity. In both 1874 papers, the authors asserted that the physical properties of organic compounds, especially their optical activity, could be accounted for by specifying that the molecules contained an asymmetric atom corresponding to a tetrahedron surrounded by four different groups. While van t Hoff s paper concentrated on the tetrahedron as the basis for optical activity, Le Bel s paper was more wide-ranging, and allowed other chiral shapes to be considered. 

The Perkin Elmer type tube packed with Tenax was used in a study of exposure to air pollutants of 100 office workers in Milan, Italy (Cavallo et al., 1997). Details of exposure time and analytical methods are not given in the paper. Concentrations of TVOC in homes (mean 411 ggrri ) as well as toluene and xylene concentrations were very similar to those measured in homes in other European studies although benzene concentrations (mean 28.8 Rgm"3) were considerably higher. 

This paper concentrates on a detailed description of the primary events occurring immediately after the absorption of a photon within a single titanium dioxide particle in an aqueous environment. This restriction was made, because 1) titanium dioxide seems to be the most active photocatalyst, and 2) the photocatalytic treatment of polluted water seems to be a promising application for an interfacial electron transfer serving the environment. 

Separate the organic phase and dry it over anhydrous sodium sulfate. Filter it through a fluted filter paper. Concentrate the filtrate under reduced pressure using a rotary evaporator to a volume of approximatively 15 mL. 

This book Is a collection of papers concentrating on pesticide formulation topics which are currently receiving the greatest attention and where the greatest advances are being made. These topics are listed below and make up the four sections of the book. The number of papers In each section Is given In parenthesis. 

In recent years kinetic and mechanistic studies have been done on the copper oxidases. Recent work has concentrated on laccase and tyrosinase, and since these two enzymes are good examples of the complexities involved, the rest of this paper concentrates on the enzymology of these two proteins. They also give rise to interesting comparisons since they have some substrates in common (e.g., catechol) but differ in certain aspects of their physicochemistry and mechanism. 

Breck at al (68) havs recently examined the reactivities of a number of saturated and unsaturated polymers towards singlet oxygen generated by microwave generator. The saturated ohain polymers as polystyrene,polyurethane and polyethylene were found to be inert within the experimental conditions with singlet oxygen,while the unsaturated polymers as poly-dienes were found to react quite readily.In this paper concentration of hydroperoxide groups has been measured. 

A number of papers concentrated on the analysis itself, with an eye to the ICH validation of that method before use in the field. Blanco et al. [14] discussed the determination of miokamycin in different dosage forms. The word validation is even in the title of the paper. As a European group, they would be concerned with ICH more than FDA regulations, but the similarities are greater than any differences. The same group also reported on a validated diffuse reflection NIR method [15]. In both papers, the word validation figures prominently. 

A number of papers and presentations concentrated on the validation of either the method or the software. Workman and Brown [26,27] presented a two-part series on the practice of multivariate quantitative analyses. These papers concentrated on the algorithms involved in validated NIR methods. 

This paper concentrates on three aspects of the application of molecular organic geochemistry to the interpretation of the biological origins of sedimentary organic matter and the use of such information in the evaluation of depositional environments. First, the basis... 

The engineering target is to eventually create a catalyst that is both highly selective and highly active over the entire operating temperature range of the diesel engine. This paper concentrates on evaluation and characterization of base-metal oxide catalysts and precious metal catalysts for total oxidation of ethanol. 

The first phase of this investigation was presented in Pettersson et al. (1995). The paper concentrated on precious metal catalysts. For detailed reviews of catalysts for alcohol vehicles refer to Pettersson (1991), and Pettersson and Jaras (1994). 

The next four papers concentrate on another emission source, hydrogen sulfide from Claus units. The Claus process has been used for several years to remove hydrogen sulfide from petroleum refinery waste gases. However, current environmental concerns require a more efficient recovery of the sulfur values. Some of the new technology to improve Claus plant efficiencies is discussed in these chapters. 

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