FAILURE MECHANISMS OF TOMATO PERICARP TISSUE SUGGESTED BY LARGE AND SMALL DEFORMATION TESTS

Failure mechanisms of tomato pericarp tissue were investigated by measuring puncture and viscoelastic properties of tissue from fruit stored at 22C (nonchilled) or 5C (chilled) for 28 days, or at 5C for 15 days prior to transfer to 22C for an additional 13 days (prechilled) to facilitate ripening. The puncture properties of tissue remained unchanged during 28 days of chilling. However, tissue shear strength and rigidity increased with chilling, as demonstrated by increases in storage and loss moduli, and decreases in oscillatory strain and the loss tangent. Puncture failure force, failure firmness and storage and loss moduli of nonchilled and prechilled tissues decreased to low, constant levels by 12 and 9 days, respectively. Simultaneously, pseudoplastic and failure strains and oscillatory strain each increased. These data suggest that the loss of tissue compressive strengths and transition in the dominant mode of failure from cell relaxation and rupture to cell debonding occurred at a faster rate during ripening of prechilled (i.e., chill-injured) compared to nonchilled fruit.     

THE 7S PROTEIN FROM BRAZIL NUT1

The 7S (6.2S) protein of Brazil nut (Bertholletia excelsa) was isolated by ammonium sulfate solubilization from a high molecular weight fraction which contained primarily the major 11S (10.5S) nut globulin excelsin. Electrophoretic characterization of the protein showed that, in addition to sedimenting more slowly, it differed from excelsin in size, being smaller, and in subunit composition.     

THE EFFECTS OF TURGOR PRESSURE ON PUNCTURE AND VISCOELASTIC PROPERTIES OF TOMATO TISSUE

The effects of turgor pressure on puncture and viscoelastic properties of mature-green tomato pericarp were examined using tissue discs soaked in a range of osmotica (0.0–0.6 M mannitol) for at least 36 h at 4C. Turgor pressure was estimated from the osmotic potential of soaking solutions that induced incipient plasmolysis. Based on volume changes, the osmotic potential and turgor pressure of fresh tissue were estimated to be −0.56 ± 0.08 MPa and 0.20 MPa, respectively. However, puncture and viscoelastic properties corresponded to a turgor pressure of 0.15 MPa. The discrepancy between calculated and actual turgor pressures was attributed to the presence of apoplastic solutes. The data from this study revealed a general increase in cell wall stress, strain and elasticity with increasing turgor. With increases in turgor above that of untreated tissue both wall extensibility and elasticity became limiting and thus cell wall stiffness increased. Conversely, a decrease in turgor below that of untreated tissue led to an increase in viscoelasticity. Increases in bioyield and pseudoplastic bioyield strains with a variation in turgor from that of untreated tissue were consistent with cell debonding as a dominant mechanism of tomato tissue bioyielding. The reduced failure force, deformation and firmness with increasing turgor were consistent with cell rupture as a predominant mechanism of failure of mature-green tomato pericarp tissue.     

DOES INNER CITY PUBLIC HOUSING EXACERBATE THE EMPLOYMENT PROBLEMS OF ITS TENANTS?

ABSTRACT: This article analyzes whether inner city public housing exacerbates the employment problems of its tenants. Results from two evaluations of public housing demonstrations are used to test the potential impact of location, address discrimination, eligibility criteria, and rent schedules on tenant work behavior. To supplement this analysis, the effects of public housing on tenant employment, including self-employment, are estimated using a unique cross-sectional data set known as the Urban Poverty and Family Life Survey. The results do not support the claim that public housing, independent of tenant characteristics, contributes to employment patterns. While it is true that most public housing residents do not work, their counterparts in the private real estate market are no more likely to be employed or to have ever worked. Overall, these results indicate that the provision of public housing does not inhibit work behavior.     

ExperTAXsm: an expert system for corporate tax planing

Abstract: This paper describes the development of ExperTAX^sm, an expert system designed as a part of the service rendered by the audit and tax practices of the accounting firm of Coopers & Lybrand in the corporate tax accrual and planning function. The current operating environment is described and the expert system based solution is presented. The knowledge engineering process is described in detail and novel techniques for knowledge extraction are presented. The resulting system and its knowledge base is also presented together with a discussion on detailed knowledge acquisition and ongoing knowledge base maintenance facilities.     

CCD型束流截面探测器

CCD型束流截面探测器的主要特点是使用电荷耦合器件做传感器,用束流同步光中的可见光成份做为信号源。该探测器同时具有模拟量和数字量两种输出,工作周期短,速度高,不影响束团粒子寿命,在电子储存环物理运行中,是一种有效的探测设备。     

A MAJOR SOLUBLE GLYCOPROTEIN OF POTATO TUBERS1

The major soluble glycoprotein of potato tubers was isolated by chromatography on DEAE cellulose and Con A Sepharose. It contained about 5% neutral sugar and 1%hexosamine, exhibited a molecular weight of 45,000 by SDS gel electrophoresis, and consisted of 6–10 ionic forms as revealed by isoelectric focusing. This glycoprotein comprised about 20%of the soluble protein in all of the 31 tested potato cultivars.