Planning tool requirements for flexible manufacturing: an analytical approach

The problem of tool and fixture resources dimensioning is considered and examined for a productive environment with flexible features. With reference to previous studies, different tool management strategies are pointed out and commented upon; a further control policy based on workpiece batching is suggested and tested. In the second section of the paper, an analytical interpretation of the question in hand is presented and discussed; the effectiveness of the procedure itself is tested by comparing analytical data with results derived from the detailed simulation of a real tool management area. Results are shown in the last section     

HEAT TRANSFER COEFFICIENTS to NEWTONIAN LIQUIDS IN AXIALLY ROTATED CANS

Overall heat transfer coefficients to water and silicone fluids in cans rotating in a steam retort were correlated by (Eq. A): ((A)) where the Reynolds number, pND²/μ, based on the rotational speed of the can, was varied over the range 12 < Re <44,000, the Prandtl number c₀μ/k was tested between 2.2 and 2300, the can length to diameter ratio was varied over 1.11 < L/D<1.61, and the ratio of bulk to wall viscosities, μb/μw, was varied between 1.22 and 1.79. All fluid properties were evaluated at the arithmetic average of the initial and final temperatures of the can wall. Data for 106 trials were correlated with a multiple regression correlation coefficient of R’= 0.916. Internal film coefficients were about 7% higher than U values and can be calculated by h = (1.07 ± 0.04) U.     

PURIFICATION AND CHARACTERIZATION OF THREEISOZYMES OF PECTIN METHYLESTERASE FROM TOMATO FRUIT

Three isozymes of pectin methylesterase (EC 3.1.1.11) have been purified to homogeneity from tomato (var. S. marzano). The isozymes were separated by affinity chromatography on Heparin-Sepharose column. They exhibited a molecular mass of 31 kDa when analyzed in sodium dodecyl sulfate gel electrophoresis and of 35 kDa in gel-filtration chromatography in native conditions. The isoelectric points of all three isozymes were found to be higher than 9.3. The K_ms calculated for the three isozymes were different toward citrus pectin used as substrate; one had a K_m of 9.7 mM (by expressing the pectin concentration as mmoles/L of methoxy groups) and the other two had similar K_ms of 3.0 and 2.6 mM, respectively. The isozyme having the higher K_m for substrate was inhibited by citrus pectin (which had a degree of methylation of 70%) at concentrations higher than 5 mM, but no inhibition was found using a pectin with a degree of methylation of 30% at concentrations up to 13 mM (i.e. 9 mg/ml) with a K_m of 14.7 mM. Furthermore, this isozyme showed a more broad range of activity in a pH range 5–10 with respect to that exhibited by the other two isozymes. All three isozymes were found to be glycosylated, although to different extents.     

Food contamination by diisopropylnaphthalenes from cardboard packages

A GC/MS investigation performed on two kinds of foods (rice and 'pasta') and their packages showed the presence of six diisopropylnaphthalene isomers. It has been demonstrated that such compounds, chemical components of carbonless and thermal copy paper, are present in cardboard, usually obtained with recycled paper. This work also demonstrates that diisopropylnaphthalenes can migrate from boxes to foods.     

MODELLING of TEMPERATURE HISTORIES DURING VENTING of STILL RETORTS

Experimental tests were carried on a pilot retort to gather information on the temperature evolution inside batch retorts during the venting stage. to fit the coming-up curves the equation for the response of an over-damped second-order system to a step input was proposed. the parameters that characterize this equation were related to steam flow, initial temperature and retort load. Results allow the prediction of coming-up curves for different operating conditions.     

DESIGNING HOPE: RATIONALES OF MIXED‐INCOME HOUSING POLICY

Rationales used to legitimize forced dispersal and mixed‐income housing policies are socially constructed based on assumptions about concentrated poverty. This study evaluates qualitative data on public housing residents who were in the process of being dispersed as part of a HOPE VI program in order to examine their thoughts about their original home and neighborhood. Residents’ thoughts about their neighborhood are compared to policy rationales. Results indicate that current policy rationales are mostly in line with the goals and motivation of the city but are largely incongruent with the perceptions residents have of their pre‐relocation home and neighborhood. The article concludes with policy recommendations for increasing and incorporating residents’ views into policy design.     

AUTOMATA AND DIGITAL COMPUTERS

A discrete time system representation of automata and abstract digital computers is investigated. Morphisms between these time systems recapture the hierarchial ordering of the classical automata. Digital computers may be also viewed as discrete time systems. The relationship between computers may be also viewed as discrete time systems. The relationship between computers so viewed and automata is investigated.     

Intracellular life of protozoan <i>Toxoplasma gondii</i>: Parasitophorous vacuole establishment and survival strategies

Toxoplasma gondii is a protozoan of worldwide distribution and the agent of toxoplasmosis. It is estimated that 30%–50% of the world population could be infected with this parasite. Although the infection in immunocompetent individuals is mostly asymptomatic, the disease in immunosuppressed and pregnant is a risk condition. As a member of the phylum Apicomplexa, T. gondii has an obligatory intracellular lifestyle; therefore, invading a host cell and establishing it inside a parasitophorous vacuole (PV) are mandatories for the survival of this parasite. The construction of a perfect intracellular niche for T. gondii requires the secretion of an arsenal of proteins from unique secretory organelles. These proteins will remodel the vacuolar environment and the host cell organization and functions, allowing the parasite to access essential nutrients and stay “invisible” inside a host cell. In the present review, we will discuss the main steps involved in the PV formation and its differentiation to tissue cyst, focusing mainly on the strategies employed in the acquisition of nutrients and proteins involved in host cell modification.