Low Reduction Degree Research Articles

Contributions to the chemistry of human hair: III. Protein chemical aspects of permanent waving treatments

Synopsis The influence of permanent waving on hair proteins was studied in order to obtain additional information about the chemistry of this cosmetic treatment. It was shown by amino acid analysis that with increasing reduction time during treatment fewer disulphide bonds were reformed in hair during subsequent reoxidation. Simultaneously, an increasing amount of sulphur-containing material is liberated from the hair, as demonstrated by the sulphur balance calculated from the sulphur-containing amino acids. The amount liberated is increased when an extensive soaking of the samples in water between the reduction and reoxidation step is performed. Comparing treatments with the use of reducing solutions of pH values between 7.5 and 10.0, it was found that the largest amount of cystine cleavage occurs at pH 9.0. All hair samples reduced at pH values above pH 8.5 showed incomplete reformation of the disulphide bonds during subsequent reoxidation. This was indicated by the content of free SH-groups and cysteic acid, as quantified by amino acid analysis. The damage to the hair proteins due to permanent waving was further confirmed by the determination of the pronase solubility. The reductive treatment of hair at pH 7.5 led to a relatively low degree of reduction, however all sulphur bonds were reformed during subsequent reoxidation.

A QUANTITATIVE ESR STUDY OF Mo5+ FORMED ON DODECAMOLYBDOPHOSPHORIC ACID

Abstract The esr signal of Mo5+ on reduced 12-molybdophosphoric acid was found to be significantly affected by the degree of hydration, the degree of reduction (DR) and recording temperature. The spin concentrations of samples with low DR ( < 1 e/anion) could quantitatively be measured when the relaxation time of Mo5+ was made sufficiently large by sample evacuation at 300°C followed by recording at −100°C. For samples with DR > 1 e/anion the dilution of reduced anions with unreduced ones was effective. It was suggested that the interaction between Mo5+ ions within a polyanion remains weak even when 4 Mo5+ are produced in a polyanion.

A macroscopic model describing yield and maintenance relationships in aerobic fermentation processes

AbstractThe present paper presents a generalized treatment of the principles of elemental and enthalpy balances which are applied to aerobic fermentation processes. It is shown that strict relations do exist between the various yield factors of biomass or product on substrate, oxygen, carbon dioxide, and between the various maintenance coefficients. These relations are confirmed from the existing body of literature data on yield and maintenance coefficients. Another consequences of the application of elemental balances is the existence of limits for the maximum biomass yield on substrate and oxygen, which depend on the degree of reduction of the substrates with different degree of reduction. It appears from this model that substrates with a high degree of reduction are C limited and substrates with a low degree of reduction are energy limited. Finally the effects of temperature on yield and maintenance coefficients are analyzed from the existing body of literature data. It can be concluded that the maintenance coefficients follow an Arrhenius type of relationship and that yield is temperature independent. The literature data seem to indicate that a degree of reduction of about 4 is optimal for the carbon and energy needs for biomass formation.

Application of macroscopic principles to microbial metabolism

AbstractGeneral expressions for mass, elemental, energy, and entropy balances are derived and applied to microbial growth and product formation. The state of the art of the application of elemental balances to aerobic and heterotrophic growth is reviewed and extended somewhat to include the majority of the cases commonly encountered in biotechnology. The degree of reduction concept is extended to include nitrogen sources other than ammonia. The relationship between a number of accepted measures for the comparison of substrate yields is investigated. The theory is illustrated using a generalized correlation for oxygen yield data. The stoichiometry of anaerobic product formation is briefly treated, a limit to the maximum carbon conservation in product is derived, using the concept of elemental balance. In the treatment of growth energetics the correct statement of the second law of thermodynamics for growing organisms is emphasized. For aerobic heterotrophic growth the concept of thermodynamic efficiency is used to formulate a limit the substrate yield can never surpass. It is combined with a limit due to the fact that the maximum carbon conservation in biomass can obviously never surpass unity. It is shown that growth on substrates of a low degree of reduction is energy limited, for substrates of a high degree of reduction carbon limitation takes over. Based on a literature review concerning yield data some semiempirical notions useful for a preliminary evolution of aerobic heterotrophic growth are developed. The thermodynamic efficiency definition is completed by two other efficiency measures, which allow derivation of simple equations for oxygen consumption and heat production. The range of validity of the constancy of the rate of heat production to the rate of oxygen consumption is analyzed using these efficiency measures. The energetic of anaerobic growth are treated—it is shown that an approximate analysis in terms of an enthalpy balance is not valid for this case, the evaluation of the efficiency of growth has to be based on Gibbs free energy changes. A preliminary analysis shows the existence of regularities concerning the free energy conservation on anaerobic growth. The treatment is extended to include the effect of growth rate by the introduction of a linear relationship for substrate consumption. Aerobic and anaerobic growth are discussed using this relationship. A correlation useful in judging the potentialities for improvement in anaerobic product formation processes is derived. Finally the relevance of macroscopic principles to the modeling of bioengineering systems is discussed.

Effect of the form and degree of plastic deformation on the mechanical properties of high-strength tubes with low-temperature thermomechanical treatment

1. The strength characteristics of 25.5-mm-diam. high-strength tubing made by low-temperature thermomechanical treatment have lower values in the direction transverse to rolling than those obtained in the longitudinal direction and are determining in rating the strength of tubular parts in general. As a result and taking into consideration the loading conditions of tubing in service, for a rapid method of inspecting the quality of high-strength tubing it would be desirable to test tubular samples by loading them with internal pressure. 2. For the purpose of providing increased tubing strength in the transverse direction it is necessary to choose low-temperature thermomechanical treatment methods characterized by a low degree of thinning of the wall and a large degree of reduction in diameter. An increase in the wall thickness during rolling is undesirable. To provide increased tubing strength in the longitudinal direction the low-temperature thermomechanical treatment methods must be distinguished by a low degree of reduction in diameter and a quite high degree of thinning. In order to provide uniformity of strength in the tubing it is necessary to use the methods used for producing the 35- and 38-mm-diam. tubing.

冷間加工を施したFe-Cu-Mn系合金の磁気的性質

Magnetic properties of Fe-Cu-Mn ternary alloys of 45 Fe-Cu-Mn and 80 Fe-Cu-Mn were investigated. Additions of less than 3 wt% manganese did not change the dendritic structures of Fe-Cu alloys, retaining their good workability. The addition of manganese to Fe-Cu binary alloys improved the coercivity, squareness and residual induction even with a low degree of cold reduction. The heat-treatment at 350∼500°C after the cold-reduction was necessary to obtain such high values of magnetic properties as Br 15.5 kG, Hc 55 Oe and Br⁄B100≥0.96 for 80 Fe-1.7 Mn-Cu alloy, and Br 7.5 kG, Hc 350 Oe for 45 Fe-1.8 Mn-Cu alloy.Magnetic torque measurments indicated that the improvement of squareness by heat-treatment was due to a strong uniaxial magnetic anisotropy which was induced by the application of cold-reduction and subsequent heat treatment. The values of coercivity and residual induction (Br) were changed by a combined effect of heating time (t) and heating temperature (T), obeying the following equations: Hc∝−logt and Hc∝exp(±E⁄RT), respectively. These equations are very convenient to control the magnetic properties of Fe-Cu-Mn ternary alloys.