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Longitudinal creep tests of a 6-ply unidirectional SCS-6/Beta21S metal matrix composite with 38 percent fiber volume fraction were performed at three temperatures of 450, 500 and 550°C at four stresses ranging from 900 to 1350MPa. Elongation and acoustic emission in the gage section were measured during creep testing, and the specimens were subjected to observation of the fibers exposed by etching the outer matrix layers after creep testing. Also performed were creep tests of the matrix material and tensile tests of the fibers extracted from a virgin specimen. In the creep tests of the composite it was observed that the increase of temperature hastened greatly creep rupture while fiber damage and acoustic emission occurred with little dependence on temperature. It was shown that the activation of matrix creep with temperature is mainly responsible for hastening creep rupture of the composite. Besides it was shown that the fiber bundle strength determined from the tensile tests of extracted fibers is effective in estimating the level of applied stress at which the composite survived long in the creep tests.

Four catechins, (–)-epicatechin (EC), (–)-epigallocatechin (EG), (–)-epicatechin gal late (ECg) and (–)-epigallocatechin gallate (EGg), extracted from tea were investigated with respect to the formation of radicals and chemiluminescence during autoxidation. An alkaline solution (0.05 n NaOH) of these catechins indicated ESR absorption accompanying a browning reaction. The spectra of EG and EGg showed a double triplet at the early stage of autoxidation, but the intensity of each decreased rapidly and the shape of the spectra changed with time, suggesting that most of the radicals disappeared and some changed into others. The spectrum of ECg showed a triplet of relatively strong intensity but decreasing slowly. EC exhibited a very weak spectrum due to EG and EGg being present as impurities. From these results, it was concluded that radicals were easily formed on the aromatic ring to which three hydroxyl groups are attached. The chemiluminescence of EG and EGg was strong and decreased rapidly, but was weak w...

An 1H and DSC study was done on the phase transition of a cetyl glucoside–water system. The system containing 23% water shows an exothermic peak at 45°C in the course of cooling due to the phase transition from liquid crystal to gel state. Above the transition temperature Tc, the NMR spectra consist of two peaks attributable to the water and the mobile alkyl chain. The latter disappeared when the temperature was lowered below Tc as the result of crystalization of the chains, and a weak peak emerged in the position between them. It was attributed to the water hydrated strongly on the glucosyl group in the inner part of the surface layer and not exchanging position with free water. After the temperature of the sample was kept at 3°C for four days, this signal disappeared, suggesting that the strongly hydrated water was expelled from the inner part and the surface structure was changed into a more riqid one. This change caused the elevation of Tc in the course of heating. The structures of the bilayer and th...

Two alkyl glycosides cetyl-β-glucoside (C16-Glu) and cetyl-β-galactoside (C16-Gal), were synthesized and the thermal properties of their water systems were examined using differential scanning calorimetry (DSC). These compounds form bilayer structures. The C16-Glu − H2O system shows five endothermic peaks due to the phase transition from gel to a liquid crystalline state at 86, 73, 68, 57, and 47°C, depending on the amount of added water, i.e., the degree of hydration. In the samples containing enough water, which means that free water coexists with hydrated water, the lowest two peaks at 47 and 57°C were observed and their intensity ratio changed in each run depending on the thermal history of the sample. It was explained by the presence of two kinds of hydrated states. An ESR study of the TEMPO parameter showed that these transitions come partly or wholly from the melting of the alkyl chains. The C16-Gal − H2O system showed three peaks, but did not show any hysteresis. The difference between C16-Glu and...

The state of water in the Aerosol OT (AOT) / isooctane reversed micelle solutions was studied by a microcalorimeter of conduction type. The molar enthalpy changes of water were obtained by mixing AOT solutions of various R values with those at R of zero, where R means the molar ratio of water to surfactant, AOT. The observed enthalpy values at larger were endothermic, whereas those at smaller R were exothermic. An enthalpy curve against R was drawn by adding consecutively the enthalpy changes, showing a maximum at R of 2. This feature was qualitatively discussed in terms of the state of water in reversed micelles.

When glucose was added to a washed suspension of yeast under aerobic conditions, the heat production curve showed three distinct phases which reflect the metabolic process. The first phase showed a sharp peak which may be attributed to the uptake of glucose the rate of which was proportional to the cell concentration. The results of chemical analyses suggest that the second phase is connected to the metabolism of ethanol, which is followed by the third phase of endogenous metabolism. The second and third phases were nearly absent under anaerobic conditions or when respiration was inhibited. The amount of cellular trehalose, which serves as an energy source, was reflected by the physiological state of the cells, but showed little effect on heat production. The heat produced was proportional to the glucose concentration, depending on the temperature. There were some differences between glucose metabolism and endogenous metabolism in the temperature effect on the rate of heat production. Some correlations between heat production and ATP were observed under anaerobic conditions, but no correlation was observed under aerobic conditions. A comparison was made of enthalpy change with different types of metabolism of yeast. The calorimetric measurements are considered to be a useful approach in studying sugar uptake processes.

A rotatory calorimeter of the conduction type was remodelled to fit the continuous study of microbiological processes. Provisions for aeration and agitation made it possible to be used for calorimetric studies of microorganisms aerobically growing in a 5-ml culture. The time constant of the calorimeter response was found to be 8min and the calorimeter could be used for most kinetic studies on microbial cultures.By using a separate culture apparatus, quantitative analyses can be made on samples taken from parallel culture and the results can be correlated with the thermogram obtained with the calorimeter. The performance of the instrument was demonstrated with the aerobic growth of Saccharomyces cerevisiae. Calorimetric study by the use of the present model may give a detailed information at the cellular level about microbial growth processes when combined with turbidity measurements.

Differential scanning calorimetry (DSC) of double stranded DNA was carried out using plasmid pJL3-TB5 DNA (5277 base pairs), whose entire nucleotide sequence has been determined. The DSC curve for the linear DNA of the plasmid used in the present study gave seven separate peaks including two main peaks which range from 82° to 98°, suggesting that DNA melts independently at several cooperative blocks along the chain. The DSC curve obtained agreed with the histogram of the frequency versus GC content which was constructed from the GC distribution map along the DNA chain of pJL3-TB5. These results are obvious evidence that the thermal transition of DNA occurs blockwise along the molecular chain. The two main peaks were estimated to be due to the heat transition of the two distinct regions, containing 46-50% and 54-58% GC, respectively. DSC of covalently closed circular (ccc-) DNA of the same plasmid did not show any heat transition peak, indicating that ccc-form is stabilized compared with linear form.

Differential scanning calorimetry of a linear double-stranded plasmid DNA showed a multimodal profile characteristic of the plasmid. This demonstrates that the helix-coil transition of DNA occurs blockwise along the DNA chain. From the results of the analysis of plasmid derivatives having deletions and duplications, the peaks of the DSC curves are assigned at regional sequences including DNA insertion element IS 1 present in the plasmid. The small change in a plasmid DNA sequence caused by cleavage of a plasmid with different restriction enzyme was also clearly reflected on their DSC curves.

SummaryA microcalorimetric method has been developed for the identification of 9 representative strains of lactic acid bacteria used in the dairy industry. A chemically defined medium containing several carbohydrates gave reproducible and characteristic growth patterns. The technique is proposed as a rapid alternative method for the identification of bacteria selected for commercial use.

Etude, en aerobiose ou en anaerobiose, de la production de chaleur par des spores d'Aspergillus oryzae ou de Bacillus cereus inoculees a du lait en poudre a teneur en eau prealablement equilibree. Parallelement on mesure, en anaerobiose, le taux d'O2 absorbe. Cette technique permet d'evaluer la correlation entre activite metabolique microbienne en dehors de toute multiplication cellulaire, et la teneur en eau du milieu

A rotatory microcalorimeter of the conduction type has been designed for the study of microbial metabolic processes under both aerobic and anaerobic conditions. The instrument can be performed in either batch mode or flow mode by changing the calorimeter vessels and the tube connections. The sensitivity and the time constant were determined by electrical calibrations. The heat sensitivity was 0.12 mV/mW with both yeast and other fungi. Because of the sufficient aeration and agitation, the calorimeter is available for studies on the fungi growth experiments of biotechnical interest.

ESR and DSC study was carried out to reveal the effect of glycyrrhizin (GR) on dipalmitoylphosphatidylcholine (DPPC) membrane. Temperature dependence of the TEMPO parameter showed that the pretransition of DPPC bilayer almost disappeared but the main transition was moved to higher temperature by the addition of GR. It was clearly ascertained by the fact that a broad endothermic peak was observed overlapping with the original one in the DSC curve. The shift to higher temperature is rare and suggests that the structure of the bilayer is stabilized by GR; nevertheless the membrane was dissolved. The order parameter of the spin-labeled phosphatidylcholine in this system was examined. It showed that the motion of the alkyl chain of DPPC is hindered by GR. From these results, a model of the fragmented bilayer is proposed and a discussion is given on the stability of the structure.

A considerable amount of heat was produced when a suspension of yeast was added to a suspending medium in the absence of an exogenous energy source. The amount of heat produced was proportional to the cell concentration and accompanied by oxygen consumption, suggesting that the exothermic reaction may be due to the endogenous metabolism of cells. The patterns of heat production varied with the physiological state of cells, which were influenced by several factors including culture conditions, methods of storage, starvation, temperature and the suspending medium used for calorimetric measurements.

Design and testing of a low temperature DSC of conduction type with high sensitivity using larger vessels of about 1.5 ml were described. The main technical characteristics of DSC are as follows: operational temperature range is −150–120°C; rate of cooling and heating is 0.01~1°C/min; volume of calorimetric vessels are 1 ml; sensitivity is 3.68μJ/sec/μV; accuracy of temperature recording is 0.1 °C. Test experiments on starches, proteins and alcoholic drinks indicate that the DSC is available for studies on dilute solutions and solids of biological materials and also on the biological-water systems.

Ribosomal particles of E. coli were examined by using a heat leakage scanning calorimeter. Remarkable changes were observed in thermograms of 70S ribosomes and their subunits when the Mg2+ concentration was raised from 1 mm to 10 mm. It was suggested that ribosomal subunits exist in more than one conformation, and changes in their conformation might be the primary cause of the association-dissociation process of ribosomes. Comparisons of thermograms of RNase- and chymotrypsin-treated, as well as non-treated SOS and 30S subunits suggest that conformational changes in each subunit may be ascribed to changes in rRNA.

The purpose of the present study is to investigate the relationship between the heat effects and the transport processes of glucose in S. cerevisiae by calorimetry and to gain the insight into the energy coupling between the transport and metabolic processes

By using a series of dry yeasts prepared to have various water contents, the resistivity to heat inactivation and cold medium treatment was studied.The heat resistance of the samples showed a marked dependence upon the water content, giving activation energies of 80kcal with relatively wet cells and 60kcal with relatively dried cells, respectively. The lowering of the biological activity shown after the rehydration with a cold medium was found to be prevented, at least partially, by preheating the sample at specified temperature before the rehydration procedure. This protective effect disappeared after several hour standing at room temperature, suggesting that the related physical state relaxed with a time constant of hours in order of magnitude.A domain map is presented to show diagrammatically the relationship between biological properties of the dry yeast and its related physical states in terms of the cell temperature and the cell water content.

We investigated the variation, of submerged amylase formation by Black Aspergilli in acidic media (added 0.2% of ammonium sulphate; pH of these media was kept at about 2.4 during the incubation) and neutral media (added 0.3% of calcium carbonate to acidic media; pH of these media was kept at about 6.0). In acidic media (Fig. 1) dextrinizing amylase did not appear, but after the weight of mycelium reached to maximum saccharogenic amylase and maltase remarkably increased and saccharifying power came to surpass 40%. Saccharifying power in mycelium was low, but maltase activity in mycelium was considerably high. In neutral media (Fig. 2) dextrinizing amylase was high, but inorease of saccharogenic amylase found in acidic media did not occur and saecharifying power stayed under 10%. Maltase was formed in early period of incubation and decreased, gradually. Since dextrinizing amylase (α-amylase) is inactivated at pH 2.4, so it was a matter of course that this amylase did'nt appear in acidic, media. But the low activity of saccharogenic amylase in neutral media can not be interpreted by inactivation, for the saccharogenic amylase is stable at pH 6.0 (Table 1). Ca.. ion also did not inhibit the formation of this enzyme (Table 2) and the weight of mycelium was nearly equal in both media. So we concluded that the acidic cultural environment is necessary for the formation of saccharogenic amylase. The superior strains for submerged mold amylase belonging to Asp. Usamii group, Asp. awamori., group and Asp. niger group have this property. But Asp. oryzae did'nt grow sufficiently in acidic media and saccharifying power was as low as in neutral media.

(1)It was experimentally shown that the pattern of angular distribution of light scattered by moderately large microbial cells is roughly presented by the FRAUNHOFER diffraction theory for a circular slit. (2) When a parallel beam is used as the incident rays, cuvettes of usual size give, however, smoothed scattering pattern due to the finite effective volume of scattering centre. The light was shown still to be strongly scattered as theoretically expected into the forward direction. (3) Practically all the scattered light could therefore, be collected by using a light receiver with a large aperture placed close to a thin cuvette. providing thus a convenient method of obtaining the true absorption spectra of cell suspensions.(4) In accordance with RAYLEIGH-GANS' first approximation to the cross section of microbial cells of moderate size, the total extinction is given by the sum of scattering and absorption attenuation. A true scattering spectra, therefore, could be obtained as the difference of the extinction spectra observed with a usual narrow beam spectrophotometer and the true absorption spectra obtained by use of a wide angle apparatus such as the one mentioned above.(5) Even in the case of fairly high-populated suspension of Chlorella, the observed apparent absorption spectra are mostly due to scattering loss. The local feature of the curves reflects the mode of anomalous dispersion of the real part of refractive indices of cells.(6) A slow rise experienced in the spectrum of yeast at 450mμ is also mainly due to scattering interference and partly to the existence of anomalous dispersion of refractive indices. In the single scattering region, the absorption of cell contributes to the attenuation only through modifying the real part of refractive index and not directly through its imaginary part.

1) Yeast cells suspended in a solution of cetyltrimethylammonium bromide (CTAB), a typical cationic detergent, rapidly bind CTAB cations. The binding process is nearly completed in less than 2min, while the germicidal action continues for at least 1hr.2) The shape of overall binding curve shown by yeast cells is similar to that of multilayer adsorption isotherm.3) The mortality of CTAB-treated cells depends upon the weight ratio of bound CTAB to yeast cells. Calculations show that 10 times the cell surface area must be covered by the bound CTAB to produce 100% killing of the samples.

The dependence of the turbidity in yeast suspensions treated with various amounts of cetyltrimethylammonium bromide (CTAB) on the percentage of killed cells provides a means for the determination of the germicidal effect. Empirical equations which describe the observed relationship between turbidity and mortality were derived, and turbidity measurements necessary to estimate the killed fractions of the sample were described. The time course of the germicidal action of CTAB upon yeast cells was observed by using this method. The turbidity change thereby observed can be accounted for by the change in cell volume resulting from the cell degeneration. Some observations on different microbes treated with various germicides suggest that the present method may be applicable to other kinds of germicides and microbes.

The process of bacteriophage T4 morphogenesis was studied using a heat leakage scanning calorimeter. Thermograms of defective mutant 49 (am NG727) in permissive and non-permissive cells of Escherichia coli showed a difference in thermal properties between packaged and non-packaged DNA molecules. In vivo , non-packaged DNA carried out their thermal transition at 85°C, the same temperature as that of T4 DNA melting measured in the standard saline citrate buffer, while the packaged DNA gave a sharper peak at 87°C due to some interaction with the head shell structure. Empty head shells showed a sharp heat absorption peak at 89°C both in vivo and in vitro , indicating the high degree of cooperativity in their conformational changes.

A photoelectric turbidimeter is described for use in measuring cell concentrations in thick suspensions. Its sample cuvette provides a path length continuously adjustable between 0.01 and 20.00 mm. By reducing the path length, it is possible to measure the optical density in thick cell suspensions without dilution. Moreover, the method described is rapid and simple, and only small amounts (less than 1 ml) of cell suspensions are required. The method is applicable to cell concentrations ranging up to 10 9 /ml for yeast.

Proton diffusion in the α-phase of polycrystalline 1-hexadecanol was studied using C16H33O3H and C15H31–14CH2OH. It was found that hydroxyl proton diffuses translationally more easily than the whole molecule. A value of (7±5)×10−7 cm2/s was obtained for the diffusion coefficient of the hydroxyl proton in the α-phase. This fast diffusion is ascribed to the presence of molecular rotation involving hydrogen-bond networks in the α-phase of the crystal. Since the mechanism for the proton diffusion seems to be the same as that for the protonic conduction in this α-phase, proton mobility can be calculated from the diffusion coefficient, assuming that molecular rotation makes the rate determining step in both processes.