Inhibition of trypsin by t-Butyloxycarbonyl-α-aza-(4-aminophenyl)alanine phenyl ester

T-Butyloxycarbonyl-α-aza-(4-aminophenyl)alanine phenyl ester (Fig. 1, III: R = NH₂) has been synthesized. The rate of inhibition of trypsin (EC 3.4.21.4) by this compound (due to acylation followed by slower deacylation) shows a marked pH maximum at approximately 6. The shape of the pH—rate curve is discussed in terms of (i) the normal pH—activity curve of trypsin reacting with a charged substrate, i.e. the protonated form of the amino compound, (ii) the deprotonation of the 4-amino group with pK_a 4·3, and (iii) the lower rate of reaction of the enzyme with the uncharged, deprotonated form of the ester.     

A SURVEY OF MICROBIOLOGICAL ASPECTS OF CIDER MAKING

Among the lactic microflora of ciders it was found that the species Leuconostoc oenos was predominant at the end of the alcoholic fermentation as well as at the end of the malo-lactic conversion. Among yeasts, the genera Saccharomyces was predominant at the end of fermentation. However, in the case of one juice characterised by a low initial level of bacteria, a high amount of phenolic compounds and a small quantity of total nitrogen, the whole lactic flora was no longer detected after a fortnight.     

Corrosion Behaviour of Manganese-Containing. Stainless steels. I. Galvanostatic measurements in H2SO4 solutions

The results of galvanostatic polarization experiments on four 17.3% Cr / 5.3% Ni stainless steels containing increasing amounts of Mn (upto 13.9%) are compared with those of an 18/8 stainless steel. All alloyes exhibit an initial step for the dissolution of Fe. A second arrest is recorded in dilute acid solutions and/or when applying high currents, and is related to the oxidation of the Cr. With an alloy containing traces of N₂, a third arrest is observed in dilute acid solutions; it is attributed to the oxidation of Cr₂N. The incorporation of Mn in CrNi steels is detrimental to their anti-corrosion characteristics. The content of this metal should be kept as low as feasible.     

Stearoyl-coenzyme a desaturase activity in the mammary gland and liver of lactating rats

Stearoyl-CoA desaturase activity in microsomes from lactating rat mammary gland is very low (0.05–0.15 nmol/min/mg of protein) regardless of lactating time. In such microsomes, reductase activities and content of cytochrome b₅ are several-fold lower than in normal rat liver microsomes. Preincubation of the mammary microsomes with purified terminal desaturase gives a 55-fold stimulation of stearoyl-CoA desaturase activity, whereas preincubation with cytochrome b₅ has no effect. However, preincubation of mammary microsomes with both cytochrome b₅ and terminal desaturase results in a 200-fold stimulation of overall desaturation. These observations suggest that negligible stearoyl-CoA desaturase activity in lactating rat mammary microsomes is due to a low cytochrome b₅ content and the absence of terminal enzyme. The hepatic stearoyl-CoA desaturase activity increases 9-fold during lactation. There is little or no change in the NADH-cytochrome c reductase activity or in the concentration of cytochrome b₅ during this period, but the activity of the terminal desaturase increases with the increase of overall desaturation. These results suggest that liver is one of the more important sources of oleic acid for milk triglycerides.     

Adaptive nonuniform polar quantization application to high quality speech compression

The logarithmic companding technique has shown to be extremely useful in speech quantization with rate of 8 bits/sample. However, for lower bit rates it is not the ideal solution for high quality speech coding. Because of that, in this paper we establish source coding scheme which enables better spectrum efficiency for input that has a large dynamic range. Since our wish is also to improve signal quality in comparison with quality defined with standards G.711 and G.712, we opt for adaptive technique application to the speech coding. Our research shows that proper design of forward gain-adaptive polar quantization can enable compression of about 1 bit/sample as well as significantly better quality than in case of using coder designed according to standard G.711. Furthermore, performances can be sustained over the whole speech dynamic range. Also, if the requisite speech quality is not supposed to be lower than G.712 standard quality, the achieved compression can be almost 1.5 bits/sample. Besides, we propose knew simple encoding rule which can additionally reduce bit rate for 0.1 bit/sample.     

Adsorption of cationic polyacrylamide onto sepiolite

The adsorption of PAM onto sepiolite from aqueous solutions has been investigated systematically as a function of some parameters such as calcination temperature of sepiolite, pH, ionic strength and temperature. The adsorption of cationic polyacrylamide (PAM) increases with pH from 5.50 to 11.00, temperature from 25 to 55 degrees C and ionic strength from 0 to 0.1molL(-1). The sepiolite sample calcined at 200 degrees C has a higher adsorption capacity than the other calcined samples. Adsorption isotherms of PAM onto sepiolite have been determined and correlated with common isotherm equations such as Langmuir and Freundlich isotherm models. The Langmuir isotherm model appeared to fit the isotherm data better than the Freundlich isotherm model. The physical properties of this adsorbent are consistent with the parameters obtained from the isotherm equations. The zeta potentials of sepiolite suspensions have been measured in aqueous solutions of NaCl and different PAM concentrations and pH. From the experimental results: (i) pH strongly alters the zeta potential of sepiolite, (ii) sepiolite has an isoelectric point at about pH 6.6 in water and about pH 8 in 250mgL(-1) PAM concentration, (iii) PAM changes the interface charge from negative to positive for sepiolite. Effect of temperature on adsorption has been quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy and entropy. The dimensionless separation factor (R(L)) has shown that sepiolite can be used for adsorption of PAM from aqueous solutions.     

Technological,Regulatory, and Ethical Aspects of In Vitro Meat: A Future Slaughter‐Free Harvest

Defined as meat cultured in a laboratory within a bioreactor under controlled artificial conditions, in vitro meat is a relatively recent area that has opened a whole universe of possibilities and opportunities for the meat sector. With improved chemical and microbial safety and varied options, in vitro meat has been proposed as a green, healthy, environmentally friendly, and nutritionally better product that is free from animal suffering and death. Cell culture and tissue culture are the most probable technologies for the development of this futuristic muscle product. However, there are many challenges in the production of a suitable product at an industrial scale under a sustainable production system and a great body of research is required to fill the gaps in our knowledge. Many materials used in the product development are novel and untested within the food industry and demand urgent regulatory and safety assessment systems capable of managing any risks associated with the development of cultured meat. The future of this product will depend on the actions of governments and regulatory agencies. This article highlights emerging biotechnological options for the development of cultured meat and suggests ways to integrate these emerging technologies into meat research. It considers the problems and possibilities of developing cultured meat, opportunities, ethical issues as well as emerging safety and regulatory issues in this area.