Soybean Protein Aggregation by Sonication: Ultracentrifugal Analysis

Ultracentrifugal analysis was used to study aggregation of 7S globulin induced by ultrasonic treatment, of water extracts from defatted soybean flakes. In pH 7.6, 0.5 ionic strength buffer, aggregated 7S proteins sedimented as 40–50S species and represented 25–40% of the total proteins. Aggregates also existed at low ionic strength, but dialysis at 0.5 ionic strength caused additional aggregation of sonically modified 7S proteins. After exposure to 0.5 ionic strength, aggregates were stable to subsequent changes in ionic strength with one exception; some reversal of aggregation occurred when samples were dialyzed against water. Aggregates exhibited highest stability at pH 6.5–6.8 and were stable at room temperature for 9 hr or more. Sonic-induced aggregation of 7S proteins resembles the phenomenon observed on heating water extracts at 80°C.     

QUALITY AND STABILITY OF SOME FREEZE-DRIED FOODS IN "ZERO" OXYGEN HEADSPACE

SUMMARY— Excellent retention of fresh flavor quality in a series of freeze-dried foods of plant and animal origin was achieved in "zero" oxygen headspace, using an atmosphere of 5% hydrogen in nitrogen with a palladium catalyst. Freeze-dried, precooked carrots, sweet potatoes, green beans, peas, spinach, white potatoes, peaches, apricots, chicken, pork, beef, beef stew, chicken stew and shrimp were investigated for oxygen uptake, flavor quality and some for consumer acceptability. The rate of oxygen uptake during storage was greater in the animal products than in the plant products studied. For oxygen-sensitive products such as carrots and sweet potatoes, loss of quality was observed in packs with headspace containing as little as 0.5% oxygen within 1 month at 100°F reflected in the lower scores given by a technological panel. A flavor profile panel reported that all the foods packed with 5% hydrogen in nitrogen with palladium catalyst had aroma and flavor amplitudes after storage at 100°F for 6 months comparable to the original products. Randomly selected untrained consumer test panels preferred the foods packed in "zero" oxygen to those in 2% oxygen after brief storage at 100°F. This preference persisted throughout the test year.     

Solving hierarchies of finite-domain constraints

Abstract. In the past we presented an algorithm to solve ordered constraint hierarchies based on a non-trivial error function using standard constraint satisfaction techniques. We extended this previous work and herewith present a new method to transform hierarchies of inequalities over the integers based on global comparators into equivalent ordered constraint hierarchies. The correctness of this method is proven. Using the results of our previous work, we present another method transforming the resulting ordered constraint hierarchies into ordinary constraint systems. These systems of algebraic equalities and inequalities over the integer domain are soluble with available finite-domain constraint solvers. Finally, we propose some modifications and simplifications of the considered constraint hierarchies, improving the search for solutions and being useful in practical applications like job-shop scheduling. The modifications proposed are the combination of consecutive hierarchy levels in one level where the constraints are considered with different priorities weights and the simplifications proposed are incomplete search strategies resulting in run-time improvements and also in sub-optimal solutions.     

Electron tomography of III‐V quantum dots using dark field 002 imaging conditions

We present an evaluation of electron tomography of buried InAs quantum dots using dark field 002 imaging conditions. The compositional sensitivity of this imaging condition gives strong contrast among III‐V materials of differing compositions and, in principle, should allow an accurate 3D model of the buried structures to be produced. The large extinction distance allows specimens several hundred nanometres in thickness to be examined and reduces the effect of strain contrast in the images, with the advantage that it can be performed using conventional transmission electron microscopy techniques. A two‐beam condition must be maintained for all images, and the presence of other strong diffraction effects at certain specimen orientation results reduces the number of orientations available for tomography by approximately 10%. The data presented here are limited due to a lack of angular range in the data set but we find that an acceptable 3D model of a buried quantum dot may be produced by imposing cylindrical symmetry on the data set.     

Retro‐fitting an older (S)TEM with two Cs aberration correctors for 80 kV and 60 kV operation

For the characterization of light materials using transmission electron microscopy, a low electron acceleration voltage of 80 kV or even 60 kV is attractive due to reduced beam damage to the specimen. The concomitant reduction in resolving power of the microscope can be restored when using spherical aberration (C_s) correctors, which for the most part are only available in the latest and most expensive microscopes. Here, we show that upgrading of existing TEMs is an attractive and cost‐effective alternative. We report on the low‐voltage performance on graphitic material of a JEOL JEM‐2010F built in the early 1990s and retro‐fitted with a conventional imaging C_s corrector and a probe C_s corrector. The performance data show C_s retro‐fitted instruments can compete very favourably against more modern state‐of‐the‐art instruments in both conventional imaging (TEM) and scanning (STEM) modes.     

SELF-SUSTAINED OSCILLATIONS DURING CO OXIDATION ON A Pt/γ-Al2O3 CATALYST

A systematic study of the effect of reaction environment and catalyst surface on self-sustained oscillations during CO oxidation on a Pt/γ-Al2O, catalyst is presented in this paper. The catalyst, consisting of a fixed bed of small particles, was subjected to three different pretreatments: fresh, O2 - H2 treated and poisoned by SO2. Self-sustained oscillations, lasting for as long as desired, were manifest in a narrow range of temperatures and O2/CO ratios. The structure of the oscillatory pattern varied with catalyst pretreatment, however, in all cases the predominant feature consisted in transitions between low and high conversion levels (ignition-quenching). The amplitude and frequency of the oscillations varied with surface pretreatment, however, they decreased as temperature and O2:/CO ratio increases. Small temperature fluctuations of less than 6°C, which mirrowed concentration oscillations were also observed. A unique feature observed under certain conditions, was an overshoot of CO2 outlet concentration in excess to the 100% conversion, which indicated the participation of surface stored CO. The results are discussed in terms of competitive CO and O2 adsorption-reaction coupled with reactor and surface balances.     

ROTERM: A MICROPROCESSOR BASED CIPHER TERMINAL SYSTEM

Microprocessors are playing an increasingly important role in cryptographic systems. ROTERM is an implementation of a cipher terminal using an inexpensive microcomputer system. ROTERM behaves like a mechanical rotor system of eight rotors with 96 elements each. Control features have been implemented in ROTERM which permit keyboard and/or remote control of the encipherment and decipherment of ASCII character strings. Examples are given demonstrating the use of ROTERM in user-user communications as well as user-electronic mail system posting and reading of messages.     

TIME-TEMPERATURE BEHAVIOR OF DEEP-FROZEN READY-TO-SERVE ETHNIC FOODS FROM THE MIDDLE EAST REGIONS

Since in the Middle East no production of deep-frozen foods of any significance has been established, all products have to be imported. This implies that the entire product spectrum consists of products adapted to the requirements of European consumers. Foods prepared according to the preferences of the people of the Middle East have not yet been offered commercially. To collect initial experiences with food prepared to meet the preferences of people living in the Middle East, three dishes were prepared and kept under cold storage conditions suitable also for the existing frozen food chain in the Middle East. The ready-to-serve food products were evaluated sensorily.