Peer Review Publications

N Garti, A Aserin, and S Ezrahi. 1994. “An attempt to develop a new fire-resistant hydraulic fluid based on water-in-oil microemulsions.” Southern Brazilian Journal of Chemistry, 2, 2, Pp. 83–104. Abstract
The strategy for the development of microemulsion-based fire-resistant hydraulic fluids was expounded. Phase diagrams were constructed for mixts. of water, oil and nonionic surfactants with and without cosurfactants. From these phase diagrams the boundaries of the monophasic area were outlined. After the major components had thus been detd., several preliminary formulations were developed by incorporating suitable additives into the oleic ingredient of the hydraulic fluid. The resulting microemulsion-based compns. complied with most of the requirements set for fire-resistant hydraulic fluids. Model systems pertinent to such formulations were utilized to investigate structural factors, which induce enhanced water solubilization. The role played by alcs. in this context was elucidated in terms of an empirical equation. Scattering and NMR methods have demonstrated the variations in the microstructure of a high water content model system. Sub-zero differential scanning calorimetry (DSC) techniques have revealed the existence of two types of water (free and bound) and detd. their relative concns. [on SciFinder(R)]
Shaw-Tao Lin, Donald L Wharry, Robert L Yates, Nissim Garti, Julianto Pranata, Samuel Siegel, and Peter. Skrabal. 1994. “Catalytic Hydrogenation of [2.2]Paracyclophane. Unsaturated Intermediates.” Journal of Organic Chemistry, 59, 23, Pp. 7056–7060. Abstract
The catalytic hydrogenation of [2.2]paracyclophane (1) was repeated to det. whether the claim that 1 yields an octahydro[2.2]paracyclophane (2) which contains a 1,4-cyclohexadienic structural unit can be substantiated. Decahydro[2.2]paracyclophane and three isomeric dienes as well as perhydroparacyclophane are isolated. The NMR spectra (1H and 13C) of the dienes are inconsistent with the earlier proposal, and the failure of the dienes to be aromatized by treatment with DDQ indicates that the trisubstituted double bonds reside in different six-membered rings. Computations of conformational energies aid the assignment of structures to the dienes. [on SciFinder(R)]
I Nir, Y Feldman, A Aserin, and N Garti. 1994. “Surface properties and emulsification behavior of denatured soy proteins.” Journal of Food Science, 59, 3, Pp. 606–610. Abstract
Soy protein isolate was phys. (heat pretreatment) and chem. (urea, guanidine-HCl, and cleavage of SS bonds) modified in order to dissoc. subunits, unfold the protein, and improve surface properties: hydrophobicity, emulsification capability, and stability. Heat pretreatment as well as chem. treatment with urea or guanidine-HCl or redn. of disulfide bonds, will improve emulsification performance in comparison to native soy protein isolate. Significant differences in redn. of surface tension of water in the presence of native and modified proteins were obsd. (45 and 35 dynes/cm, resp.). Measurements of fluorescence indicated that the relative hydrophobicity of the soy protein was also improved (from 600 to 1360) after heat pretreatment or contacting the soy protein with an 8M urea soln. [on SciFinder(R)]
Y SELA, S MAGDASSI, and N Garti. 1994. “Newly designed polysiloxane-graft-poly (oxyethylene) copolymeric surfactants: preparation, surface activity and emulsification properties.” Colloid and Polymer Science, 272, 6, Pp. 684–691. Abstract
Two sets of comb-grafted polymeric surfactants based on poly(methylhydrogen siloxane) (PHMS) and/or poly(dimethylsiloxane) (PHMS-PDMS) were prepd. by silylation of the active Si-H group with an active $ømega$-vinyl group of specially designed undecenoic-polyethylene glycol esters (UPEG) to formation "newly-designed" polysiloxane-grafted-polyethylene glycol comb-copolymeric surfactants. The hydrophilic moieties are hooked to the hydrophobic backbone through a "spacer" (undecenoic acid). The variation in the surfactants' structures were in the length and d. of the grafted hydrophilic moieties, the chain length (DP) and nature of the hydrophobic backbone. The first 12 different polymeric surfactants (set 1), termed PHMS-UPEG, were ineffective emulsifiers with limited ability to stabilize oil-in-water emulsions. The second set of surfactants, named PHMS-PDMS-UPEG comb-grafted copolymers, significantly reduced the oil-water interfacial tension and efficiently stabilized several types of oil-in-water emulsions. The best emulsifier of this set (PHMS-PDMS-52-UPEG-45), seems to be one whose anchor backbone (PHMS-PDMS) dissolves (rather than spreads) in the oil phase, and whose stabilizing moieties are sufficiently long (45 EO units) and "hooked" to the silicone backbone at high d. (52% substitution). [on SciFinder(R)]
Y SELA, S MAGDASSI, and N Garti. 1994. “Polymeric surfactants based on polysiloxanes-graft-poly(oxyethylene) for stabilization of multiple emulsions.” Colloids and Surfaces, A: Physicochemical and Engineering Aspects, 83, 2, Pp. 143–150. Abstract
Attempts have been made to produce and use new polymeric surfactants based on polysiloxane-graft-poly(oxyethylene) for stabilization of water-in-oil-in-water (W/O/W) multiple emulsions. Hydrophobic comb-grafted copolymers have been used at the inner interface to obtain stable small droplet size water-in-oil emulsions. Hydrophilic comb-grafted copolymers with similar structures but with high d. grafting and long poly(oxyethylene) chains have been used to stabilize the outer interface of the W/O/W emulsion. Stable multiple emulsion formulations with very slow release rates can be obtained when using the two types of silicone emulsifier. [on SciFinder(R)]
Yuri Feldman, Nissim Garti, and Bronislava. Milgotin. 1993. “Time domain dielectric spectroscopy as a tool for studying hydration of proteins.” Conference Proceedings - Italian Physical Society, 43, Water-Biomolecule Interactions, Pp. 131–134. Abstract
Dielec. investigation of myoglobin aq. soln. over a wide temp. range -80°C - +30°C was accomplished with the help of Time Domain Dielec. Spectroscopy. Three relaxation processes ($\beta$, $δ$1,$δ$2, with characteristic times ≈10-8 s, ≈10-9S and ≈10-10s resp.) were obsd. in the overlapped time window 10-5-10-10 s. The nature of this processes are discussed in this article. [on SciFinder(R)]
H Furedi-Milhofer, R BLOCH, D Skrtic, N Filipovic-Vincekovic, and N Garti. 1993. “Induction of crystallization of specific calcium oxalate hydrates in micellar solutions of surfactants.” Journal of Dispersion Science and Technology, 14, 3, Pp. 355–371. Abstract
The influence of octaethylene glycol mono-n-hexadecyl ether (I) and SDS on the crystn. of Ca oxalate from 0.3 mol dm-3 NaCl solns. was investigated. The crit. micellar concn. (CMC) of I in H2O and 0.3 mol dm-3 NaCl was detd. by surface tension measurements (CMCH2O:CMCNaCl = 7.2.10-6 mol·dm-3). The kinetics of pptn. of Ca oxalate was followed by Coulter counter, and solid phases were characterized by polarized microscopy, thermal anal., and x-ray powder diffraction patterns. Under the pptn. conditions employed, the thermodynamically stable monohydrate, CaC2O4·H2O was the predominant cryst. form. In the presence of micellar solns. of I, pptn. of this phase was facilitated as evidenced by higher initial pptn. rates and higher ppt. vol. and no. of particles, as compared to the controls. Micellar solns. of SDS retarded pptn. but induced crystn. of Ca oxalate dihydrate, CaC2O4·(2+x)H2O (COD, x ≤ 0.5). Thus at c(SDS)\textgreaterCMC, the ppts. contained ≥85 mass % COD. The results were discussed in relation to previously reported data on the pptn. of Ca oxalate in the presence of dodecyl ammonium chloride. [on SciFinder(R)]
H FurediMilhofer, R BLOCH, D Skrtic, N FilipovicVincekovic, and N Garti. 1993. “INDUCTION OF CRYSTALLIZATION OF SPECIFIC CALCIUM-OXALATE HYDRATES IN MICELLAR SOLUTIONS OF SURFACTANTS.” JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY, 14, 3, Pp. 355–371. Abstract
The influence of octaethylene glycol mono-n-hexadecyl ether (C16EO8) and sodium dodecyl sulphate (SDS) on the crystallization of calcium oxalate from 0.3 mol dm-3 sodium chloride solutions has been investigated. The critical micellar concentration (CMC) of C16EO8 in water and 0.3 mol dm-3 NaCl was determined by surface tension measurements (CMCH2O=CMCNaCl = 7.2.10(-6) mol dm-3). The kinetics of precipitation of calcium oxalate was followed by Coulter counter, and solid phases were characterized by polarized microscopy, thermal analysis and X-ray powder diffraction patterns. Under the precipitation conditions employed, the thermodynamically stable monohydrate, CaC2O4.H2O (COM) was the predominant crystalline form. In the presence of micellar solutions of C16EO8 precipitation of this phase was facilitated as evidenced by higher initial precipitation rates and higher precipitate volume and number of particles, as compared to the controls. Micellar solutions of SDS retarded precipitation but induced crystallization of calcium oxalate dihydrate, CaC2O4.(2+x)H2O (COD, x less-than-or-equal-to 0.5). Thus at c(SDS)\textgreaterCMC the precipitates contained greater-than-or-equal-to 85 mass % COD. The results are discussed in relation to previously reported data on the precipitation of calcium oxalate in the presence of dodecyl ammonium chloride.
N Garti, R FELDENKRIEZ, A Aserin, S Ezrahi, and D SHAPIRA. 1993. “Hydraulic fluids based on water-in-oil microemulsions.” Lubrication Engineering, 49, 5, Pp. 404–411. Abstract
Hydraulic fluids based on water-in-oil microemulsions and non-ionic emulsifiers were prepd. Phase diagrams of the microemulsions were constructed with the intention of using the most suitable of them for formulation of hydraulic fluid with and without additives. Up to 22 wt.% water could be solubilized when a carefully designed mixt. of nonionic ethoxylated alcs. was used as the surfactant; up to nearly 35 wt.% water could be solubilized when a mixt. of paraffinic oil and pentanol was used as the oil phase and the same mixt. of nonionic ethoxylated alcs. was used as the surfactant. Droplet size, stability, and other phys. characteristics were evaluated. [on SciFinder(R)]
N Garti, A ROSSANO, and Y AVNI. 1993. “GRAFT-COPOLYMERS AS EMULSIFIERS .1. GRAFTED POLYETHYLENEGLYCOL ON POLYMETHYLMETACRYLATE.” JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY, 14, 1, Pp. 47–70. Abstract
Polymeric surfactants, based on grafted polyethyleneglycol (PEG) with different chain lengths on polymethylmetacrylate (PMMA), have been prepared and studied. The `'stabilizing moiety'', PEG, was grafted by a transesterification reaction on the -OCOCH3 groups of the `'anchoring moiety'' PMMA, obtaining comb type substituted PMMA. The amphiphilic polymers reduce only slightly the water/air surface However, interfacial tension of certain `'oil phases'' such as toluene were significantly reduced. The best polymeric surfactant, reducing interfacial tension practically to zero, was PMMA of MW 130000 grafted with 6.5 wt% PEG consisting of 22 ethylene oxide (EO) units. Spontaneous emulsification was achieved with very low polymer concentration (\textless1.0%). Flocculation was observed in emulsion in which excess emulsifier was used or in systems containing free ungrafted PEG.
Nissim Garti and Dov. Reichman. 1993. “Hydrocolloids as food emulsifiers and stabilizers.” Food Structure, 12, 4, Pp. 411–426. Abstract
A review with 45 refs. Gum arabic is compared to colloidal microcryst.-cellulose (MCC) and galactomannans in view of their ability to reduce surface tension, interfacial tension and to stabilize oil-in-water emulsions via the steric and mech. stabilization mechanisms. While gum arabic adsorbs strongly and effectively onto the oil droplets via its proteinaceous moieties, guar gum and locust bean gum (LBG) adsorb weakly and for the most part only "ppt." on the oil surface, and form birefringent layers of the polymer oriented with its hydrophobic mannose backbone facing the oil. The stabilization with MCC is claimed to be achieved via adsorption of solid particles on the oil droplets (mech. stabilization). [on SciFinder(R)]
Nissim Garti, Anat Rosano, and Yair. Avni. 1993. “Graft copolymers as emulsifiers. Part I. Grafted polyethylene glycol on poly(methyl methacrylate).” Journal of Dispersion Science and Technology, 14, 1, Pp. 47–70. Abstract
Polymeric surfactants, based on grafted poly (ethylene glycol) (I) with different chain lengths on PMMA are prepd. and studied. The graft copolymer is prepd. by a transesterification reaction on the -OCOCH3 groups of the PMMA. The amphiphilic polymers reduce only slightly the H2O/air surface tension. However, interfacial tension of oil phases such as toluene are significantly reduced. The best polymeric surfactant, reducing interfacial tension practically to zero, is PMMA of mol. wt. 130,000 grafted with 6.5 wt% I consisting of 22 ethylene oxide units. Spontaneous emulsification is achieved with very low polymer concn. (\textless1.0%). Flocculation is obsd. in emulsion in which excess emulsifier is used or in systems contg. free ungrafted I. [on SciFinder(R)]
Y SELA, N Garti, and S MAGDASSI. 1993. “SURFACE-ACTIVITY AND EMULSIFICATION PROPERTIES OF NEW POLYETHYLENEGLYCOL BASED NONIONIC SURFACTANTS.” JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY, 14, 2, Pp. 237–247. Abstract
10-undecenoic acid chloride was esterified with several well-defined polyethyleneglycolmonomethylethers to obtain new ethoxylated monofatty acid esters. The new surfactants will, at a later stage, be grafted into a silicone backbone to obtain polymeric surfactants. The monomeric surfactants have shown interesting surface properties, and here we report their characterization compared to other known ethoxylated alcohols (Brijs) and acids (Mirjs). It was observed that the CMC (critical micelle concentration), and area per molecule (a), at the air-water interface were much higher than the similar commercial Brijs, due to the special structure of the new surfactant allowing preferred orientation at the interface.
Y SELA, N Garti, and S MAGDASSI. 1993. “Surface activity and emulsification properties of new polyethylene glycol-based nonionic surfactants.” Journal of Dispersion Science and Technology, 14, 2, Pp. 237–247. Abstract
New ethoxylated monofatty acid esters are obtained by esterification of 10-undecenoic acid chloride with several well defined polyethylene glycol mono-Me ethers. The monomeric surfactants show interesting surface properties, and they are characterized and compared to other known ethoxylated alcs. (Brijs) and acids (Mirjs). The crit. micelle concn. and area per mol. at the air-water interface are much higher than the similar com. Brijs, due to the special structure of the new surfactant allowing preferred orientation at the interface. [on SciFinder(R)]

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