Retene

It was demonstrated dial tlie dirral auxiliaiy can be recovered after die reaction as die corresponding stilfinamide MefFljNSfOjPb, witli virtually complete reten-bon of configurabon at die sulfur atom. 

Solute Retention Retention is determined by the relative rates of solute and solvent transport through the membrane. The impact of operation on solute retention Rj = 1 — Cp/c can be evaluated from Eq. (20-73) by using the mass balance J, = Assuming high reten-... 

The ProteinChip System from Ciphergen Biosystems uses patented SELDI (Surface-Enhanced Laser Desorption/Ionization) ProteinChip technology to rapidly perform the separation, detection, and analysis of proteins at the femtomole level directly from biological samples. ProteinChip Systems use ProteinChip Arrays which contain chemically (cationic, anionic, hydrophobic, hydrophilic, etc.) or biochemically (antibody, receptor, DNA, etc.) treated surfaces for specific interaction with proteins of interest. Selected washes create on-chip, high-resolution protein maps. This protein mass profile, or reten-tate map of the proteins bound to each of the ProteinChip Array surfaces, is quantitatively detected in minutes by the ProteinChip Reader. 

In Roman times tar and pitch from Pinaceae resinous wood were used to treat the inner surface of amphorae to store fluids such as wine [ 145,149] and to seal ship planks [89,144], Heating treatments applied to natural resins and resinous wood profoundly modify the chemical composition of the original material. Diterpenoid compounds undergo aromati-zation, demethylation and decarboxylation reactions, with the formation of new compounds of a lower molecular weight that show a high degree of aromatisation [87,88]. In tar and pitch produced from Pinaceae resin and woods, retene is considered as a stable end product of these reaction pathways and nor-abietatrienes, simonellite and tetrahydroretene represent the intermediates of these reactions [87,89,150]. 

Figure 3.17 shows the mass profile of the resinous material collected from the Roman amphora. It shows the presence of abietane skeleton diterpenoids due to the occurrence of the peaks at m/z 315, 299, 285, 253 and 239. Furthermore, a high degree of oxidation of the resin was ascertained by the abundance of peaks at m/z 315 and 253, deriving from 7-oxo-dehydroabietic acid, and those at m/z 331 and 329, from highly oxidised tricyclic diterpenoid molecules. Finally, the presence of retene was evidenced by the peaks at m/z 234 and 219. The results showed that a pitch from Pinaceae had been in the amphora. 

Figure 8.4 Total ion current chromatograms of the (a) acidic and (b)neutral fractions of a sample collected from an amphora recovered in Fayum. DDA, didehydroabietic acid DA, dehydroabietic acid 70DA, 7 oxo dehydroabietic acid 70A, 7 oxo abietic acid 15Hy70DA, 15 hydroxy 7 oxo dehydroabietic acid 5HyDA, 15 hydroxy dehydroabietic acid R, retene MDA, methyl dehydroabietate. Slf internal standard, hexadecane IS2, internal standard, tridecanoic acid...

The first sample, dating from the Ptolemaic period ( 300 BC), was found in a container from a tomb from Fayoum. The volatile compounds observed in this sample (see Table 10.1, column 11) were very similar to those of pine pitch. The two chromatograms are presented in Figure 10.21. The major compounds are guaiacol (11) and its para-n-alkyl derivatives (24, 35, 43) and the degradation products of diterpenic acids 19-norabieta-8,l 1,13-triene (95), 18-norabieta-8,11,13-triene (100), 10,18-bisnorabieta-5,7,9(10),ll,13-pentaene (102), retene (105) and methyldehydroabietate (106). The major compounds observed after... 

Reproducibility of monolithic columns has also been cited as a major concern because the monoliths are manufactured individually.34-35 An extensive study by Kele and Guiochon indicates that the reproducibility results of Chromolith columns were almost comparable to those from different batches of particle-packed columns.37 Other drawbacks of monolithic columns include weak reten-tivity for polar analytes,38 efficiency loss at high flow rates for larger (800 MW) molecules,39 and peak tailing, even for neutral non-ionizable compounds.36-38-40 Furthermore, silica-based monolithic... 

Beck et al. (1997) used GC-MS to monitor the increase in the proportion of retene in pine tars with increasing temperature, and 13C-NMR to monitor the increased aromatic signal resulting from dehydrogenation and decarboxylation reactions. These data allow approximate determinations of the production temperature of a tar from the molecular composition. Diterpenoid molecules of probable pine origin have been detected in many archaeological contexts and some detailed compositional studies have appeared (Robinson et al, 1987 Heron and Pollard, 1988 Beck et al., 1989 Reunanen et al., 1989 Beck et al, 1994). 

In addition to the symbols previously defined, Q will be taken as the volumetric flowrate of retenate at the intermediate point, C the concentration of solute in the retentate at this point, F and F2 the volumetric flowrates of membrane permeate in the first and second stages respectively, and Ai and A2 the required membrane areas in these respective stages. 

The phenanthrene/anthracene series is shown in Fig. 7 and the major peak in the m/z 234 trace has the retention index of retene which is generally derived from conifer wood burning. Sometimes there is a triplet of peaks in the same C4 plot due to benzonaphthothiophenes (C10H16S) which are components of some... 

Scott JA, Incardona JP, Pelkki K, Shepardson S, Hodson PV (2011) AhR2-mediated, CYPlA-independent cardiovascular toxicity in zebrafish (Danio rerio) embryos exposed to retene. Aquat Toxicol 101 165-174... 

Lepp, H.J.T. Oikari, A.O.J. The occurrence and bioavailability of retene and resin acids in sediments of a lake receiving BKME (bleached Kraft mill effluent). Water. Sci. Technol. 1999, 40 11-12), 131-138. 

Unwanted effects An increased incidence of thrombosis and embolism is attributed to the estrogen component in particular. Hypertension, fluid reten-Liillmann, Color Atlas of Pharmacology... 

During prolonged dieting by obese individuals on very low-calorie diets, there was a marked increase in sulfobromophthalein (BSP) reten-... 

As mentioned earlier, SEC is extremely reproducible with respect to retention volume, peak width, and height. The ratio of reten-... 

Cabral and coworkers [253] have investigated the batch mode synthesis of a dipeptide acetyl phenylalanine leucinamide (AcPhe-Leu-NH2) catalyzed by a-chymotrypsin in a ceramic ultrafiltration membrane reactor using a TTAB/oc-tanol/heptane reverse micellar system. Separation of the dipeptide was achieved by selective precipitation. Later on the same group successfully synthesized the same dipeptide in the same reactor system in a continuous mode [254] with high yields (70-80%) and recovery (75-90%). The volumetric production was as high as 4.3 mmol peptide/l/day with a purity of 92%. The reactor was operated for seven days continuously without any loss of enzyme activity. Hakoda et al. [255] proposed an electro-ultrafiltration bioreactor for separation of RMs containing enzyme from the product stream. A ceramic membrane module was used to separate AOT-RMs containing lipase from isooctane. Application of an electric field enhanced the ultrafiltration efficiency (flux) and it further improved when the anode and cathode were placed in the permeate and the reten-tate side respectively. 

Ramdahl, T., Retene—A Molecular Marker of Wood Combustion in Ambient Air, Nature, 306, 580-582 (1983a). 

Yefremov et al. [34] studied systems containing tetryl by thermal analysis and found that it forms additive compounds with phenanthrene, fluorene or retene in the mole ratio 1 1 which do not melt uniformly. It also forms an additive compound in the same ratio with naphthalene, m.p. 86.8°C. 

Higher flavor loads generally result in poorer flavor reten-... 

Substitutive thiocyanation in the 7-position of cholesterol and its benzoate have been reported.80 The same position attacked in halo-genation.282 233 Ready substitutive thiocyanation occurs9 in the side chains of aralkyl hydrocarbons, e.g., thiocyanation of the isopropyl group of retene.79 Ultraviolet irradiation is necessary and the substrate... 

---