Zvi Ludmer

Allicin Purified From Fresh Garlic Cloves Induces Apoptosis in Colon Cancer Cells Via Nrf2

Allicin (diallyl thiosulfinate) is the best-known biologically active component in freshly crushed garlic extract. We developed a novel, simple method to isolate active allicin, which yielded a stable compound in aqueous solution amenable for use in in vitro and in vivo studies. We focused on the in vitro effects of allicin on cell proliferation of colon cancer cell lines HCT-116, LS174T, HT-29, and Caco-2 and assessed the underlying mechanisms. This allicin preparation exerted a time- and dose-dependent cytostatic effect on these cells at concentrations ranging from 6.2 to 310 μM. Treatment with allicin resulted in HCT-116 apoptotic cell death as demonstrated by enhanced hypodiploid DNA content, decreased levels of B-cell non-Hodgkin lymphoma-2 (Bcl-2), increased levels of bax and increased capability of releasing cytochrome c from mitochondria to the cytosol. Allicin also induced translocation of NF-E2-related factor-2 (Nrf2) to the nuclei of HCT-116 cells. Luciferase reporter gene assay showed that allicin induces Nrf2-mediated luciferase transactivation activity. SiRNA knock down of Nrf2 significantly affected the capacity of allicin to inhibit HCT-116 proliferation. These results suggest that Nrf2 mediates the allicin-induced apoptotic death of colon cancer cells.

Stratified laminar countercurrent flow of two liquid phases in inclined tubes

Abstract The effects of inclination on the characteristics of laminar countercurrent liquid–liquid flow are investigated both experimentally and theoretically. Experimental results show that with a slight off-vertical inclination the phases tend to segregate and the basic flow pattern in inclined tubes is stratified flow. Moreover, for fixed operational conditions, there exist two stable modes of stratified configuration that differ in the in situ holdup, velocity profiles and the pressure drop, and both may co-exist in the column. The application of the two-fluid and the two-plate models for the prediction of the characteristics of countercurrent flow is explored. Both models predict the existence of the two modes that have been observed in the column and their associated holdups. The TP model confirms the experimental finding that back flow (opposite to the feed direction) is an inherent characteristic of countercurrent flow and generally, is expected in the thicker layer. The findings of this study are applicable for improving the throughput of phase transition extraction columns.

Novel continuous multistage extraction column based on phase transition of critical-solution mixtures

Abstract A novel continuous extraction technique is described, namely the PTE (phase-transition extraction) column. The PTE column is based on the use of partially miscible liquid solvents that have a critical solution temperature. In the column, the conventional mixing and settling sections are replaced by heating and cooling sections. The countercurrent feed and solvent streams passing those sections are heated and cooled across their coexistence curve and thereby undergo phase transitions which alternate between states of two distinct liquid phases and a single homogeneous phase. The operation and mass-transfer performance of the PTE column were studied in single-stage and three-stage laboratory-scale columns. Continuous operation with countercurrent flow of the solvents was shown to be feasible and complete mixing of the solvents in the mixing sections was achieved without the use of any mechanical agitation. The experiments also indicated that each heating-cooling stage acts as one theoretical stage, regardless of the number of stages in the column. This suggests that a large number of heating and cooling stages can be assembled into a tall PTE column without loss of efficiency. Furthermore, the PTE column has a design advantage in that it operates without any moving parts. Tests showed that systems with a high emulsifying tendency are handled in the PTE column without forming emulsions. A basic theoretical model was developed to descibe the flow pattern of the solvents in the PTE column. The model predicts the existence of back-flow streams between the mixing and settling sections of each stage. These streams affect the heat consumption but have a negligible impact on column efficiency. The model was consistent with the experimental measurements. The PTE column could provide significant advantages for difficult separation processes such as: separations that require a large number of theoretical stages, separations of large molecules that can be damaged by high shear stresses and separations of easily emulsifiable systems.

PHASE SEPARATION OF PARTIALLY MISCIBLE SOLVENT SYSTEMS: FLOW PHENOMENA AND HEAT AND MASS TRANSFER APPLICATIONS

The phenomena associated with phase separation via spinodal decomposition (SD) and nucleation of binary and ternary partially miscible solvent systems are reviewed. The pertinent literature includes many theoretical, numerical and experimental studies which were conducted in order to follow the flow phenomena during the phase separation of solutions of critical and off-critical compositions. The unique characteristics of phase transition in partially miscible solvent systems include efficient mass transfer in the single phase region, rapid phase separation, low sensitivity to presence of emulsifiers and solids, high penetration of solvents to wetted pores, and convective motion of the separating droplets due to chemical potential gradients. These have been utilized for the development of a novel extraction process, denoted as Phase Transition Extraction (PTE) for difficult tasks, and for enhancing convective heat transfer rates. Interesting aspects of the phase separation phenomena in these solvent systems and their wide range potential practical applications are demonstrated and discussed.

Phase Transition of Partially Miscible Solvents Induced by Heating Cycles: Application for the Remediation of Contaminated Sediments and Sludge

A novel process entitled “Sediments Remediation Phase Transition Extraction” (SR-PTE) is being developed for a simultaneous removal of both heavy metals and organic pollutants from contaminated sediments or sludge. The process uses partially miscible solvent mixtures, where one of the components is water. By heating the mixture above a certain temperature, a single phase is formed. This allows the organic solvent, containing an appropriate chelating agent, to penetrate the wetted sediment voids and efficiently extract simultaneously the organic and heavy metal pollutants. The phase separation, occurring during the cooling stage, is fast and allows the pollutants to propagate and concentrate in the lighter organic phase, leaving the sediments and the lower aqueous phase practically clean. The SR-PTE technology was tested on authentically polluted river sediments and on heavily contaminated sludge from a waste-water treatment plant. The extraction efficiency was found to improve by the phase transition cycle induced by temperature variation (about twice than that obtained when the extraction was carried out isothermally). Additionally, with the induced phase transition, the formation of stable emulsions is prevented albeit the presence of natural surfactants in the treated media. The process was tested on lab scale and bench-scale reactor. No significant effects of the process up-scaling from lab to bench scale were observed.Copyright