Rapid fermentation of beer using an immobilized yeast multistage bioreactor

The characteristics of yeast sulfite metabolism in a multistage bioreactor system for beer fermentation were investigated. No sulfite was produced in the continuous stirred-tank reactor (CSTR). However, large amounts were produced in the packed-bed reactor (PBR). Production of sulfite in the PBR seems to be inevitable when it is operated continuously. In order to control the sulfite level in the young beer, the yeast needs to be reactivated into the growth phase. One possible strategy to achieve this is to aerate and periodically remove yeast clogged in the reactor once every 6–7 months before the sulfite level exceeds a given concentration (e.g., 20 mg/L). It was confirmed that sulfite production is closely related to the growth condition of the yeast and is therefore important to consider in the control strategy for sulfite when using the immobilized yeast reactor for beer production.     

Electron correlations and transport effective mass in narrow-band systems and the Hubbard model

The Hubbard model is rederived from a tight-binding band calculation, showing that, as long as parameters are properly chosen, the model is justified for calculating electronic properties of narrow-band systems. The treatment is extended by including correlations and it was found that bound solutions called dimers exist. The concept of dimers is found to be very powerful for understanding the unusual properties of heavy fermion systems. However, a Mott-Hubbard-like model may be required to calculate properties of high T_c cuprates. © 1994 John Wiley & Sons, Inc.     

A new microbial electrode for BOD estimation

A new microbial electrode using immobilizedClostridium butyricum was prepared for biochemical oxygen demand (BOD) estimation of wastewaters. The current of the electrode was decreased with time until a steady state was reached. The steady state current was in all cases attained within 30-40 min at 37°C, and the maximum current output was obtained at 37°C and pH between 6.2 and 7.0. A linear relationship was obtained between the steady state current and BOD. The steady state current values were reproducible within ±7% of the relative error. The BOD of industrial wastewaters can be estimated by using the microbial electrode. Relative error of the BOD estimation of industrial wastewaters was within ± 10%. The current output of the microbial electrode was almost constant for 30 days.     

Catalyzed cycloaddition reactions of α-silyloxy-α,β-unsaturated ketone and aldehyde

The reactions of α-silyloxy-ga,β-unsaturated ketone and aldehyde with diene afforded [4+2] and [4+3] cycloadducts respectively in the presence of a catalyst.     

Extraction and spectrophotometric determination of zinc in coal fly ash and pond sediments with 2-[2-(3,5-dibromopyridyl)azo]-5-dimethylaminobenzoic acid

An extraction-spectrophotometric method is described for the determination of traces of zinc with 2-[2-(3,5-dibromopyridyl)azo]-5-dimethylaminobenzoic acid. The reagent forms a stable, blue 1:2 zinc/reagent complex that can be extracted into chloroform. The apparent molar absorptivity of the zinc(II) complex is 1.26 × 10⁵ l mol^?1 cm^?1 at 610 nm in chloroform. The reagent is relatively selective; interferences from cobalt, copper and nickel can be masked with dimethylglyoxime and aluminium and iron with a mixture of sodium fluoride and triethanolamine. The method is applied to the determination of zinc in coal fly ash and pond sediments with good precision and accuracy.     

Synthesis and antinociceptive activity of orally active opioid peptides: improvement of oral bioavailability by esterification

To improve the oral bioavailability of a dermorphin tetrapeptide analog, N(alpha)-1-iminoethyl-Tyr-D-MetO-Phe-MebetaAla-OH (III), which has a potent analgesic activity after oral administration, various derivatives were synthesized to increase lipophilicity by esterification of the C-terminal carboxyl group and/or acylation of the phenolic hydroxyl group on Tyr1. Antinociceptive activity was evaluated after subcutaneous or oral administration using the mouse tail pressure test. As a result, increased antinociceptive activity after oral administration as well as an improved ED50(p.o.)/ED50(s.c.) ratio, which is an indicator of oral bioavailability, were found for some compounds. With regard to the improvement of bioavailability, derivatives with acylation of the phenolic hydroxyl group on Tyr1 showed better results than derivatives with esterification of the C-terminal carboxyl group. In particular, an ED50(p.o.)/ED50(s.c.) ratio equivalent to that of morphine was found for an acetylated derivative, N(alpha)-1-iminoethyl-Tyr(COMe)-D-MetO-Phe-MebetaAla-OH (7a), as well as for a methoxycarbonylated derivative, N(alpha)-1-iminoethyl-Tyr(CO2Me)-D-MetO-Phe-MebetaAla-OH (7l).     

Site-directed 13C solid-state NMR studies on membrane proteins: strategy and goals toward revealing conformation and dynamics as illustrated for bacteriorhodopsin labeled with [1-13C]amino acid residues

We have so far demonstrated that well-resolved and site-specifically assigned (13)C peaks as recorded by site-directed NMR study on (13)C-labeled membrane proteins can serve as a convenient probe to reveal their local conformation and dynamics. We attempted here to clarify the extent to which (13)C NMR spectra of (13)C-labeled fully hydrated bacteriorhodopsin (bR) as a typical membrane protein are visible or well resolved in the presence of inherent fluctuation motions with frequency of 10(2)-10(8) Hz, especially at the membrane surfaces. Accordingly, we estimated the relative proportion of (13)C NMR signals from the surface areas with and without peak suppression by the accelerated transverse relaxation effect by surface-bound Mn(2+) ions, which could be effective for residues within 8.7 angstroms of the membrane surface. It turned out that the experimental findings are consistent with the predicted amount of amino acid residues under consideration located within 8.7 angstroms of the surface for [1-(13)C]Val- and Ile-labeled bR and also [3-(13)C]Ala-bR. In contrast, (13)C NMR peaks from such surfaces area are almost completely or partially suppressed for [1-(13)C]Gly-, Ala-, Leu-, Phe- and Trp-labeled bR, as a result of plausible interference of the fluctuation frequency with frequency of magic angle spinning (10(4) Hz). We further assigned several (13)C NMR signals of [1-(13)C] Val-, Trp- and Ile-labeled bR on the basis of a variety of site-directed mutants with reference to those of the wild type. Further, we recorded the (13)C NMR of bR in lipid bilayers to search for the optimal conditions to be able to obtain signals with the highest peak intensities and spectral resolution. Backbone dynamics turn out to be essential for recording (13)C NMR spectra so as to escape from motional frequencies of the order of 10(4)-10(5) Hz, either in the direction of accelerated fluctuation or slowed motions in the direction of forming the 2D array.     

Thermal stability of phthalate esters: Effect of substituents on the β-carbon atom

In order to clarify the mechanism conferring heat resistance on phthalate esters, those with a substituent on the β-carbon atom, such as bis(2-aminobutyl) phthalate, bis(2-nitrobutyl) phthalate, bis(2,4-diphenylbutyl) phthalate and dineopentyl phthalate, were synthesized and their thermal stabilities were studied by thermogravimetry and differential thermal analysis. The analytical results for these phthalate esters were compared with those for dibutyl phthalate, with a straight alkyl chain. As the temperatures required for a 3% weight loss of phthalate esters with a substituent, an electron-donating group (amino group) or an electron-accepting group (nitro group) on the β-carbon atom move to the higher end of the range, the effect of the adjacent group was recognized. The presence of a phenyl group in phthalate esters considerably improved the heat resistance. It is considered that the high heat resistance of bis(2,4-diphenylbutyl) phthalate is due to the obstruction of the planar configuration for cis elimination by the phenyl group and hindrance by the phenyl group of the formation of the six-membered cyclic transition state owing to the interaction between non-bondable molecules.     

7,10,14-Tri-t-butyl-3-amino-1,8-bisdehydro[14]annulene

Tri-t-butylcarboxybisdehydro[14]annulene was converted by the Curtius reaction into unstable aminoannulene, which could be characterized as N-acetyl derivative. The pK_a-value of the aminoannulene reflects aromatic nature of the annulene nucleus.