PARTIAL PURIFICATION AND CHARACTERIZATION OF A THERMOSTABLE TRYPSIN FROM PYLORIC CAECA OF TAMBAQUI (COLOSSOMA MACROPOMUM)

A 38.5 kDa alkaline protease from pyloric caeca of tambaqui (Colossoma macropomumj, a tropical freshwater fish, was partially purified in three steps: thermal treatment (45Cfor 30 min), salting‐out (ammonium sulfate at 40–80% of saturation) and gel filtration (Sephadex G‐75), The purification and yield were 51.2‐fold and 40%, respectively. The effects of pH, temperature, inhibitors, and substrates on proteolytic activities of partially purified enzyme were investigated. The optimum pH was 9.5, while the optimum temperature was 60C. This alkaline proteolytic activity remained unaltered after 30 min incubation at 55C. Active site inhibition provided additional evidence that this activity is attributed to a trypsin‐like enzyme.     

TEXTURAL CHANGES IN VEGETABLES DURING THERMAL PROCESSING. II. EFFECTS of ACIDIFICATION and SELECTED PRETREATMENTS ON TEXTURE of TURNIPS

The effect of different preprocessing treatments on the softening of vegetable tissues during acidification of turnips at different temperatures was studied. Texture was characterized by the maximum load force in a puncture test. the different preprocessing treatments considered were blanching alone and coupled with vacuum infusion, freezing/thawing and calcium chloride addition. Samples were acidified at different constant temperatures: 20, 50, 70 and 90C. Results were obtained by comparing the softening occurring for all samples and for non-preprocessed turnips. It was found that for low temperature processing the final result was mainly due to the effect of the preprocessing itself on the turnip texture while for high temperature processing the effect of the preprocessing on the tissues sensitivity to the processing was more important. Blanching alone caused greater softening when processing at 70C but lead to a firmer product when coupled with calcium chloride addition or vacuum infusion for processing at 70 and 90C.     

Solidification of Be-free Ni-based dental alloy

A novel, Nb- and Si-rich and Be-free Ni-based alloy was cast by two methods of investment casting and continuous casting to study the microstructure evolution during solidification and its mechanical properties. The solidification of the alloy started with the primary crystallization of FCC-γ, followed by a binary eutectic reaction, with the formation of a heterogeneous constituent: FCC-γ+G-phase, which replaced the low-melting eutectic (FCC-γ+NiBe) in the Be-bearing alloys. AlNi₆Si₃ and γ′ formed during the terminal stages of solidification by investment casting, while the formation of AlNi₆Si₃ was suppressed by continuous casting. The Scheil solidification model agreed very well with the experimental results.     

METHIONINE LIBERATION BY PEPSIN-PANCREATIN HYDROLYSIS OF BEAN PROTEIN FRACTIONS: ESTIMATION OF METHIONINE BIOAVAILABILITY

Albumin (ALB), globulin (GLO), globulin G1 (G1), glutelin (GLU), and a protease inhibitor-lectin rich fraction (PIL) were extracted from IAC-Carioca 80 SH (Phaseolus vulgaris) based on differential solubility. The purpose of the study was to search for different susceptibilities to proteolysis and methionine liberation among protein fractions. The fractions were submitted to pepsin digestion for 3 h, then to pancreatin digestion for another 3 h, under optimum pH and 37C. Degree of hydrolysis (DH) was followed by the TNBS reaction and methionine liberation (Met%) by the chloramine-T method. DH for undenatured proteins was higher for GLO, Gl and GLU (62–71%) and lower for ALB and PIL (51–53%). After denaturation, DH was higher for Gl, GLU and GLO (81–86%) and lower for PIL and ALB (66–78%). For undenatured proteins Met% was higher for GLO, Gl and GLU (42–48%), and lower for ALB and PIL (22–29%). For denatured proteins Met% was higher for Gl, ALB and GLO (66–73%) and lower for PIL and GLU (50–53%). Overall, hydrolysis and methionine liberation followed the same general pattern for both pepsin and pancreatin digestion, individually.     

COMMUNICATING KNOWLEDGE SYSTEMS: Part II—Big Talk among Small Systems

Abstract

A new model is introduced for describing societies of communicating knowledge systems from an artificial intelligence perspective. The society is defined as a time-evolving concept con-taining both static and dynamic knowledge. The static knowledge includes the components of the society, namely the actor types, the communication issue types, and the behavior pattern types. The dynamic knowledge specifies how the society can evolve. Each component is a metatheory described using a specific representation system. The metatheories representing the actor types include self-knowledge, knowledge about other actors, and knowledge about the real world. The communication issues always reflect the knowledge of the sending actor and produce some effect on the receiving actor, for instance, enrichments of its knowledge or conflicts with its own knowledge. Conflicts are of two forms: routine conflicts to be solved by mediating actors with no intelligent knowledge, or conflicts that require intelligent knowledge. and that must be solved by special actors called managers. Behavior pattern rules are theories that express cause-effect rules regarding the society behavior as a whole. Technically, modifications of the society are defined as parameterized theories whose argument specifies the requirements to be satisfied before a change of the situation and whose body introduces the modifications to be performed.     

NUTRITIONAL EVALUATION OF BEAN (PHASEOLUS VULGARIS) PROTEIN. IN VIVO VERSUS IN VITRO PROCEDURE

Digestibility (D), Biological Value (BV) and Net Protein Utilization (NPU) of whole bean flour and of the protein fractions glutelin (GLU), globulin (GLO), globulin GI (GI), albumin (ALB) and a protease inhibitor/lectin rich fraction (PIL) were determined, after autoclaving (121C, 15 min). For the whole bean flour both in vivo and in vitro procedures were used. For the in vivo assay a nitrogen balance with rats was performed. In vitro evaluation was based on the mean essential amino acid index (MEAAI) and in vitro protein digestibility. Results for the whole bean flour (BF) showed no statistical differences (p ≤ 0.01) between in vivo and in vitro techniques. In vitro digestibility ranged from 75–93% for the protein fractions and was 76% for the whole bean protein; biological value for the protein fractions ranged from 62–79%, and was 85% in the whole bean protein; calculated NPU ranged from 47–76% for the fractions, and was 65% for the whole bean protein.     

Experimental and numerical rolling contact fatigue study on the 32CrMoV13 steel

The aim of this work is to study pure rolling contact fatigue in 32CrMoV13 quenching and tempering steel. The study involves both experimental and numerical work. The influence of the roughness and the residual stresses on the mechanisms and zones of cracking were studied. The results show a rapid reduction in roughness during the first minute of test but even so there will be specimen deterioration. The residual stress profile after rolling contact tests have high compression values in the surface and at a depth of approximately 240 μm, which is related with the Hertzian maximal shear stress. The numerical simulation of the Hertzian loading was used both to determine the elastic shakedown of the material and to apply a high‐cycle multiaxial fatigue criterion. The three‐dimensional finite element analysis used in the numerical calculation includes elastic‐linear kinematic hardening plastic material and allows the introduction of an initial residual stress state. Taking into account the elastoplastic load induced by the Hertz pressure, low‐cycle fatigue tests were used to characterize the mechanical properties of the material. In order to validate the numerical simulation, the results of the calculation after elastic shakedown were compared with the values measured by X‐ray diffraction after rolling contact tests. The results showed a reasonable agreement between calculated and measured stresses. The Dang Van high‐cycle multiaxial fatigue criterion showed a good relationship with the experimental findings.     

STUDIES OF THE THERMALPERFORMANCE OF BUILDINGSIN SUMMER IN SOUTHERN EUROPE

This paper describes the studies carried out in project PASCOOL to document and assess the thermal performance of selected buildings in Southern Europe and to identify possible improvements. Twenty-three buildings from nine European countries were surveyed and monitored for a short period during summertime. The measurements and survey data obtained formed the basis for sensitivity studies with thermal simulation. The selection encompassed buildings of typical construction, including both recent and traditional, residential and non-residential. The sensitivity studies addressed the effects of shading, thermal inertia, ventilation, window orientation and colour of external surfaces, envelope insulation, and occupancy patterns. The paper presents the methodology adopted for the measurements and sensitivity studies and discusses the main conclusions drawn from the studies- It identifies options for improving occupant thermal comfort with little or no mechanical cooling.