REGULATION OF PHENYLALANINE AMMONIA-LYASE ENZYME IN ANNONA FRUIT: KINETIC CHARACTERISTICS AND INHIBITORY EFFECT OF AMMONIA

In this work, we analyzed the kinetic properties of phenylalanine ammonia‐lyase (PAL) extracted from “cherimoya” (Annona cherimola Mill.) fruits ripened at ambient temperature (20C) and stored under several environmental conditions, including high CO₂ levels (20%) and low temperature (6C). The effect of different ammonia‐related compounds on cherimoya PAL activity was also evaluated. PAL exhibited two different K_mvalues for L‐phenylalanine (L‐Phe ) and negative substrate cooperativity, with Hill coefficient (n_app) values reaching 0.64 and 0.71 for low temperature and high CO₂ levels, respectively. The kinetic analysis revealed that ammonia produced mixed inhibition of PAL enzyme, with inhibition constants (K_i and K_i′) values of 0.57 ± 0.2 mM and 2.54 ± 0.2 mM. We propose that the regulation of PAL by ammonia inhibition and the negative cooperativity may be essential in adjusting the active phenylpropanoid metabolism in Annonas to the requirement of L‐Phe and in consequence, to the carbon skeleton demand for other anabolic pathways.     

PASSIVE AND HYBRID COOLING OF BUILDINGS – STATE OF THE ART

This paper deals with the state of the art on Passive and Hybrid Cooling of buildings. The existing techniques and components to prevent thermal gains and to dissipate excess energy to environmental heat sinks are reviewed. Topics dealing with the control of internal heat gains and with the occupant activities are discussed. The state of the art on design tools is presented. Thirteen European buildings using passive and hybrid cooling techniques and components are analyzed. Finally, future research needs are discussed. This work summarizes the findings of a Horizontal study on Passive Cooling carried out by the authors (1), as part of the Building 2000 research program of the European Communities.     

Numerical modeling of multiphase flow,heat transfer and titanium flow behavior in blast furnace hearth

Understanding the complex phenomena in BF hearth is essential to increase furnace productivity and to extend furnace campaign.We have developed several continuum-based mathematical/numerical models to simulate the multi-phase flow,heat transfer and chemical reactions in the BF hearth.These models have generated an improved insight on the mechanisms for liquid drainage efficiency,lining erosion and wall protection in BF hearth under operational conditions.The current paper gives an overview of these studi...     

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.     

DETERMINATION OF VARIABLE DIFFUSION OF SODIUM DURING DEBITTERING OF GREEN OLIVES

Time‐variable average effective diffusion coefficients of sodium in the skin and flesh were determined using Macroscopic Mass Balances from experimental data obtained during debittering of green olives, variety Arauco at temperatures of 15, 20 and 25C and lye concentrations of 1.50, 2.25 and 3.00% of NaOH. The effective diffusion coefficient of sodium increased with treatment time at both surfaces of the skin, while it varied very little within the flesh, and in many cases, remained almost constant during the debittering process. In general, the diffusion coefficients determined in the present study were within an order of magnitude of 10^?10 m²/s for the flesh during most of the treatment time, while for the skin, they were of the order of 10^?12 m²/s for the initial treatment times. Macroscopic mass balances are a simple mathematical method that can be used in lieu of more common numerical techniques, to evaluate variable diffusion coefficients providing accuracy and greater detail of the whole phenomena.     

A MODEL FOR DIFFUSION of SODIUM IN GREEN OLIVES AT DIFFERENT TEMPERATURES and LYE CONCENTRATIONS

A diffusion model for a composite flat plate, consisting of a thin skin of thickness o, and a thicker flesh of thickness L, with constant flesh and skin effective diffusion coefficients (D_F and D_S) was successfully adjusted to the experimental data obtained during the debittering of green olives variety Arauco (also known as Criolla) at 15C, 20C and 25C and lye concentrations of 1.50%, 2.25% and 3.00% of NaOH. the D_F values ranged between 1.64 × 10^?10 and 9.20 × 10^?10 m²/s, and increased with increasing temperature and lye concentration. the D_S values ranged between 1.27 × 10^?12 and 5.63 × 10^?12 and also increased with increasing lye concentration and temperature. Activation Energies (Ea) of diffusion in the flesh and the skin were evaluated with an Arrhenius‐type relationship. the Ea values for the flesh were 93.2, 72.7 and 64.8 kJ/mol, and 92.7, 91.46 and 33.67 for the skin for lye concentrations of 1.50%, 2.25% and 3.00%, respectively.     

SHELF-LIFE OF FRESH-LIKE READY-TO-USE DICED SQUASH

The shelf-life of fresh-like ready-to-use diced squash during storage for 16 days at 10–12C and 95% of relative humidity was investigated. The ascorbic acid (AA) content, moisture, soluble solid content, titratable acidity, pH, weight loss and microbiological counts were determined. At the end of storage, a 1.5% weight loss was observed. Water content did not show significant changes during storage. The soluble solids content and the Brix/titratable acidity ratios increased during storage, following a linear correlation. The evolution of AA content followed a 2° polynomial correlation, with a maximum between 7–9 days of storage and a final value of 17 mg AA/100 g of fresh weight. The total microbial count increased continuously throughout storage but showed an acceptable level until day 10.     

Probiotics for the young and the not so young

Although interest in the effects of the intestinal flora on health dates from the beginning of the 20th century, controlled clinical trials did not begin until its end. Oral administration of probiotic lactobacilli has been shown to alleviate and prevent atopic eczema. Similar effects were accomplished by administering fructose and glucose oligosaccharides (prebiotics) which encouraged the proliferation of endogenous lactobacilli and bifidobacteria. Nonpathogenic Escherichia coli has been shown to protect premature infants from infection. Twenty years later, infants given this E. coli were still found to be less allergic. Meta-analyses have confirmed that Lactobacillus rhamnosus strain GG prevents and treats rotavirus diarrhoea. By reversing the changes in bowel flora which occur with age comes the prospect of rejuvenating ageing immune systems, preventing Clostridium difficile infections and bowel cancer, thereby fulfilling the early promise of prolongation of life.     

Conformational Change in Actomyosin from Post-spawned Hake Stored on Ice

The changes that lead to a decrease in the viscosity of actomyosin of post-spawned hake stored on ice were investigated. Surface hydro-phobicity of actomyosin from hake increased significantly in the first 3 days of storage. Compared with that stored 3 days, the viscosity of actomyosin from day 0 was greater and its changes suggested greater hydrophylic surface area. Electron microscopy showed changes in the filamentous structure of actomyosin during ice storage. Actomyosin from hake stored in ice is hypothesized to undergo conformational changes including exposure of hydrophobic groups resulting in drastic changes in hydrodynamic properties and a loss of the characteristic arrowhead structure of fresh acotmysin.