CB formulation

Widespread medicinal use of colloidal bismuth subcitrate (CBS) has prompted extensive studies of bismuth compounds involving the citrate anion. Bismuth citrate is essentially insoluble in water, but a dramatic increase in solubility with increasing pH has been exploited as a bio-ready source of soluble bismuth, a material referred to as CBS. Formulation of these solutions is complicated by the variability of the bismuth anion stoichiometry, the presence of potassium and/ or ammonium cations, the susceptibility of bismuth to oxygenation to Bi=0, and the incorporation of water in isolated solids. Consequently, a variety of formulas are classified in the literature as CBS. Solids isolated from various, often ill-defined combinations of bismuth citrate, citric acid, potassium hydroxide, or ammonium hydroxide have been assigned formulas on the basis of elemental analysis data or by determination of water and ammonia content, but are of low significance in the absence of complementary data other than thermal analysis (163), infrared spectroscopy (163), or NMR spectroscopy (164). In this context, the Merck index lists the chemical formula of CBS as KgfNHJaBieOafOHMCeHsCbh in the 11th edition (165), but in the most recent edition provides a less precise name, tripotassium dicitrato bismuthate (166). 

High resolution MAS techniques of 13C, DEPT, correlated spectroscopy (COSY), total correlation spectroscopy (TOCSY), heteronuclear chemical shift correlation (HETCOR) were used to examine conventional CBS and efficient TMTD vulcanisation of polybutadiene [37]. In conventional CBS vulcanisation, the major vulcanisate 13C NMR peak occurred at 44.9 ppm and was assigned to a trans allylic structure (-C=C-C-Sx with X=3 or 4). The efficient TMTD vulcanisation yielded as main product a 13C NMR peak at 54.0 ppm and was assigned to a cis allylic vulcanisate (-C=C-C-Sx x=l). While cyclic sulfur by-products were observed in both vulcanisation systems, the CBS formulations gave rise to a higher percentage postulated to be formed via a episulfide intermediate. 

As discussed in Chapters 4 and 5, CBPC formation is governed by the oxide solubility. The solubility, in turn, is related to the Gibbs free energy, which is a function of temperature and pressure. As a result, the CBS formulation depends on the downhole temperature and pressure. The effect of the temperature on the solubility has already been discussed in Section 6.4. The pressure effect can be assessed in a similar manner, but as we shall see, it is negligibly small and can be ignored for all practical purposes. 

If the formation has openings too large for the cement to plug them, much of the cement, pumped down the hole, may be lost. In such cases, it is necessary to first plug these openings by means of flash-setting cements. CBS formulations can be designed to flash set... 

CBS formulations produce very dense cements, and as we shall see below, the permeability of hardened CBS is always an order of magnitude lower than that of conventional oil-well cements. This characteristic indicates that CBPCs make an excellent sealant against gas migration. 

As Table 15.3 indicates, the heat offormation of Ceramicrete-based permafrost cement is typically 50-60% of the heat of formation of conventional cement. Even though the acid-base reaction is highly exothermic, i.e., it releases a significant amount of heat during setting. In CBS compositions, the binder that produces heat is only a part of the entire CBS formulation, and the remaining components are extenders. Thus, the net amount of heat generated is about half that in the equivalent amount of conventional cement. 

In general, the same compositions used for onshore wells also work for the offshore wells. Saline water retards the setting rate, and longer pumping time is available for the same CBS formulation in offshore wells compared with onshore wells. In addition, because the saline water contains dissolved solids, one needs to add more water in the slurry to obtain the same low initial Be. Results of the pumping time versus temperature are shown in Table 15.6 for formulations that are similar to those given in Table 15.5. 

The relative accuracy of the OSB and CB formulations have been discussed by Pitterle 123 and investigated by Greenspan 125) and by Kiefhaber (737). When the exact flux and importance function spectra are known, both formulations are exact, irrespective of the group structure used. The flux formulation [Eq. (236)] can cause significant errors for the same problems. In problems for which the cross-section averaging spectra were only slightly different from the exact spectra, the CB formulation was found (725) to be more accurate than the OSB formulation. Both formulations were much more accurate than the flux formulation. Conversely, Kiefhaber (737) examined problems with highly distorted spectra and found that the accuracy of the CB, OSB, and flux formulations for these problems is comparable. These results are too limited to allow conclusions about the relative accuracy and applicability of the two bilinear formulations. 

Now suppose that the rate constants have values such that the rate of change of Cb is very small relative to the rates of change of other concentrations then in the conventional formulation it is stated that Cb is at steady state, and the assumption Cb = 0 is made. With this assumption and Eq. (3-140) we find... 

Cannabinoids are highly lipophilic compounds making bioavailabihty very dependent on the formulation and the mode of administration. Cannabinoid occurrence in the plant is predominantly in the form of the carboxyhc acids, which are pharmacologically totally different and rather unstable, decarboxy-lating over time to their active neutral form. The carboxyhc acids, although not active at the CB receptor, nevertheless add to the overall effect as they possess antibiotic and anti-inflammatory effects. 

Okumoto [89] has reported an analytical scheme (Scheme 2.8) for automotive rubber products (ENB-EPDM vulcanisates). For high-resolution PyGC analysis, organic additives are first removed from the rubber/(CB, inorganics) formulation. Carbon-black and inorganic material hardly interfere with pyrolysis. For the analysis of the additives the extracted soluble... 

Hydrolysis of polyamide-based formulations with 6 N HC1 followed by TLC allows differentiation between a-aminocaproic acid (ACA) and hexamethylenedi-amine (HMD) (hydrolysis products of PA6 and PA6.6, respectively), even at low levels. The monomer composition (PA6/PA6.6 ratio) can be derived after chromatographic determination of the adipic acid (AA) content. Extraction of the hydrolysate with ether and derivatisa-tion allow the quantitative determination of fatty acids (from lubricants) by means of GC (Figure 3.27). Further HC1/HF treatment of the hydrolysis residue, which is composed of mineral fillers, CB and nonhydrolysable polymers (e.g. impact modifiers) permits determination of total IM and CB contents CB is measured quantitatively by means of TGA [157]. Acid hydrolysis of flame retarded polyamides allows to determine the adipic acid content (indicative of PA6.6) by means of HPLC, HCN content (indicative of melamine cyanurate) and fatty acid (indicative of a stearate) by means of GC [640]. Determination of ethylene oxide-based antistatic agents... 

Four pyrotechnic delay compositions given in 1961 edition of Ellern (Ref 44a) are listed in Vol 3 of Encycl, p D50. In regard to Exotic" Delay Mixtures, Dr Ellern remarks in the 1968 ed of his book (Ref 57, p 415), that these formulations were actually prepd and tested in his laboratory, but the limited investigation was not further pursued by him or by others. At the time of development of Nb(Cb)-Ta - Ba Chromate mixts, the delay mixts with Cr, Mo W(Tungsten) were classified in US. That is why Dr Ellern develops his own mixts which were not classified, although their components Niobium and Tantalum were rather expensive... 

Ca) Dynomites-gommes. They contained large amounts of NG, and small amounts of CC. Those contg 70 to 83% NG and small amt of CC contained other ingredients, as can be seen in Table -F15 Cb) Dynamites gllatinles. They contained smaller amounts of NG, slightly smaller amounts of CC, but larger amount of K nitrate. Two formulations are listed in Table F16... 

Where k0 denotes the standard rate constant. The overall Butler-Volmer equation assuming the reactant and product concentrations to be the same, cA = cB = c, can be formulated as... 

While writing the above expression, the facts that have been used are GsD = CSC, GsBD = CqC0, and (G ) 1 = (CsylC l. Note that the definition of GsBD is different from the previous formulation [9] this follows from the difference in definition of CB, which has been discussed before. Here Cs and C are the phase space correlation functions defined as... 

It is obvious that the formulation in terms of tia and tib is more straight forward than the formulation in terms of Ca and Cb ... 

Paech MJ, Lim CB, Banks SL, Rucklidge MW, Doherty DA. A new formulation of nasal fentanyl spray for postoperative analgesia a pilot study. Anaesthesia. 2003 58 740-744. 

Lipic PM, Bates FS, Hillmyer MA, J. Am. Chem. Soc., 120, 8963-8970 (1998). Pascault JP, Williams RJJ. In Polymer Blends, Volume 1 Formulation, Paul DR, Bucknall CB (eds), John Wiley Sons, New York, 2000, pp. 379-415. Pascault JP, Yalette L, Magny B, Barbeau P, French Patent 99/04042 (2000). 

Paul DR, Bucknall CB (eds), Polymer Blends, Volume 1 Formulation, John Wiley Sons, New York, 2000. 

Markovich RJ, Anderson Evans C, Coscolluela CB, Zibas SA, Rosen J. Spectroscopic identification of an amorphous-to-crystalline drug transition in a solid dispersion SCH-48461 capsule formulation. J Pharm Biomed Anal 1997 19 661-673. 

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