Presence Of Triethylene Glycol Research Articles

Advances in the greener synthesis of chromopyrimidine derivatives by a multicomponent tandem oxidation process

A hydrophilic cobalt/copper heterogeneous bimetallic catalyst named mTEG-CS-Co/Cu-Schiff-base/IL was successfully synthesized from chitosan polysaccharide. The new catalyst was investigated and confirmed using various techniques including FT-IR, FE-SEM, EDX-EDS, XRD, TEM, TGA, AFM, NMR and ICP. The catalyst exhibited powerful catalyst activity for the tandem one pot oxidative chromopyrimidine reaction from benzyl alcohols under mild conditions, utilizing air as a clean source in a green protocol. The catalyst was compatible with a wide range of benzyl alcohols, and aldehydes formed in situ, and bis-aldehydes synthesized were condensed with urea/4‑hydroxycumarin to provide favorable products in good yields for all derivatives (14 new derivatives). The presence of tri-ethylene glycol and imidazolium moieties with hydrophilic properties on the mTEG-CS-Co/Cu-Schiff-base/IL nanohybrid provides dispersion of the nanohybrid particles in water, leading to higher catalytic performance. Furthermore, the reaction exhibited several other notable features, including low catalyst loading, the ability to be recycled for up to 6 stages, high atom economy, a simple work procedure, short reaction time, utilization of an environmentally friendly nanohybrid, and the replacement of volatile and organic solvents with water solvent.

Efficient Pb (II) removal from wastewater by TEG coated Fe3O4 ferrofluid

Tri-ethylene glycol (TEG) coated Fe3O4 nanoparticles ferrofluid were used for Pb (II) removal from simulated wastewater. The samples were synthesized using a modified co-precipitation method. The prepared samples were characterized by different techniques including X-ray diffraction, Rietveld method, FTIR, FESEM, TEM, VSM, TGA, BET and atomic adsorption experiments. The crystallinity of nanoparticles with a cubic spinel ferrite structure and absence of impurity phases were verified using X-ray diffraction and Rietveld method. The presence of TEG was approved by FTIR and thermogravimetric analysis. The VSM results showed that the bonding between the TEG molecules and ferrite nanoparticles, reduces the surface spin disorder, influences the morphology and magnetization, and consequently increases the Pb (II) removal efficiency to a high value of 97%. The obtained high value of adsorption capacity of q=363.4 mg.g-1 with R= 91 % and q=129.4 mg.g-1 with R=97 %shows effective role of TEG coating on Pb (II) adsorption. The interesting results of this study imply that the TEG coated ferrofluid sample is suitable candidate for practical applications.

Semiconducting Nanocrystalline Bismuth Oxychloride (BiOCl) for Photocatalytic Reduction of CO2

The reduction of CO2 is relevant for the production of compounds as part of the carbon capture and utilization research approaches. Thus, photocatalytic reduction of CO2 over a tailored BiOCl-based photocatalyst (BTEG) was tested under UV light (365 nm). BTEG was synthesized in the presence of triethylene glycol, which gave 4-nm crystallites, much smaller than the 30 nm crystallites of commercial BiOCl. Commercial BiOCl reduced CO2 mainly to methane with a minor fraction of ethanol, and was inactivated after 20 h. BTEG was a more active catalyst for CO2 photoreduction, producing approximately equal amounts of methane, methanol, and ethanol while consuming 0.38 µmol g−1 h−1 of CO2 before the experiment was stopped after 43 h, with the catalyst still active. The different products formed by the BTEG photocatalyst samples were tentatively ascribed to its greater content of {110} facets. Thus, in addition to band-gap tuning, the relative fractions of BiOCl facets had a key role in the effective photocatalytic reduction of CO2, and the BiOCl-based BTEG catalyst promoted the formation of important compounds as methanol and ethanol.

Structure Differentiation of Hydrophilic Brass Nanoparticles Using a Polyol Toolbox.

Nano-brasses are emerging as a new class of composition-dependent applicable materials. It remains a challenge to synthesize hydrophilic brass nanoparticles (NPs) and further exploit them for promising bio-applications. Based on red/ox potential of polyol and nitrate salts precursors, a series of hydrophilic brass formulations of different nanoarchitectures was prepared and characterized. Self-assembly synthesis was performed in the presence of triethylene glycol (TrEG) and nitrate precursors Cu(NO3)2·3H2O and Zn(NO3)2·6H2O in an autoclave system, at different temperatures, conventional or microwave-assisted heating, while a range of precursor ratios was investigated. NPs were thoroughly characterized via X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmition electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and ζ-potential to determine the crystal structure, composition, morphology, size, state of polyol coating, and aqueous colloidal stability. Distinct bimetallic α-brasses and γ-brasses, α-Cu40Zn25/γ-Cu11Zn24, α-Cu63Zn37, α-Cu47Zn10/γ-Cu19Zn24, and hierarchical core/shell structures, α-Cu59Zn30@(ZnO)11, Cu35Zn16@(ZnO)49, α-Cu37Zn18@(ZnO)45, Cu@Zinc oxalate, were produced by each synthetic protocol as stoichiometric, copper-rich, and/or zinc-rich nanomaterials. TEM sizes were estimated at 20–40 nm for pure bimetallic particles and at 45–70 nm for hierarchical core/shell structures. Crystallite sizes for the bimetallic nanocrystals were found ca. 30–45 nm, while in the case of the core-shell structures, smaller values around 15–20 nm were calculated for the ZnO shells. Oxidation and/or fragmentation of TrEG was unveiled and attributed to the different fabrication routes and formation mechanisms. All NPs were hydrophilic with 20–30% w/w of polyol coating, non-ionic colloidal stabilization (−5 mV < ζ-potential < −13 mV) and relatively small hydrodynamic sizes (<250 nm). The polyol toolbox proved effective in tailoring the structure and composition of hydrophilic brass NPs while keeping the crystallite and hydrodynamic sizes fixed.

Synthesis of sulfone-containing non-ionic polyurethanes for electrophoretic deposition coating

The desire to develop a sustainable society has recently inspired polymer chemists to explore functional polyurethane materials because of their versatile material shape and thermoplasticity. To develop further functionalities of polyurethane materials and manipulation methods, here, we report the synthesis and a new method for coating non-ionic polyurethanes containing sulfonyl groups with utilizing electrophoretic deposition. The polyurethanes were synthesized via polyaddition of methylenediphenyl 4,4′-diisocyanate (MDI) with 2,2′-thiodiethanol in the absence or presence of triethylene glycol (TEG) as the soft ternary segment of the polymer, followed by oxone oxidation. The electrophoretic behaviors of the polyurethanes toward a stainless-steel electrode were investigated, and the peeling resistance and scratch resistance of a polyurethane film coated on a plate were evaluated by cross-cut adhesion and pencil hardness tests, respectively. These tests revealed that incorporation of soft TEG segments at an appropriate fraction can enhance both peeling resistance and scratch resistance. We also tested the enhancement in the transparency of the coated films, which do not lose their favorable peeling resistance and scratch resistance in the process, by replacing the aromatic diisocyanate component (MDI) with an alicyclic diisocyanate, dicyclohexylmethane 4,4′-diisocyanate (HMDI). A new manipulation technique of polyurethane materials via electrophoretic deposition (EPD) is proposed. Polyurethanes with sulfonyl groups are synthesized for the EPD coatings on a stainless-steel electrode plate at the anode side selectively. The coating properties, including peeling resistance, scratch resistance, and transparency, are improved by optimizing soft segment fraction and also by reducing aromaticity of the polyurethanes.

Novel biocompatible PBS-based random copolymers containing PEG-like sequences for biomedical applications: From drug delivery to tissue engineering

A series of random poly(butylene succinate)-based copolymers, (poly(butylene/triethylene succinate) (P(BSmTESn)), containing ether-oxygen atoms were successfully synthesized by melt polycondensation of succinic acid and 1,4-butanediol in the presence of triethylene glycol (TEG) (TEG content up to 40 mol%). The copolymers were characterized from the molecular, thermal, structural and mechanical point of view. Hydrolytic degradation studies were performed under physiological conditions. The biocompatibility of the samples under investigation through indirect and direct biocompatibility studies was investigated by using embryonic rat cardiac H9c2 cells. To evaluate the potential of these polymers also for controlled drug delivery systems, the diffusion profile of Dexamethasone, an anti-inflammatory drug, through nanoparticles prepared by oil-in-water miniemulsion process was investigated. Results showed that solid-state properties could be tailored nicely by simply varying copolymer composition. Crystallinity degree and hydrophobicity significantly decreased with the increase of triethylene succinate co-unit (TES) mol%. Moreover, hydrolytic degradation of PBS, depending on polymer crystallinity degree and hydrophilicity, was remarkably improved: the copolymer containing 40 mol% of triethylene succinate co-unit after 200 days lost over 22% of its initial weight. The newly developed biomaterials showed lack of cell cytotoxicity. Among them, PBS and the copolymers containing up to 20 mol% of TES co-units sustained a better cell adhesion and proliferation. In addition, such copolymers induced muscle phenotype commitment in H9c2 cells cultured onboard. Lastly, the release profile of Dexamethasone obeyed to a first order kinetic law, the copolymer richest in TES co-unit content showing the highest encapsulation capability and the fastest drug release kinetics. Anyway, PBS and the copolymers containing up to 20 mol% of TES co-unis sustained a better cell adhesion and proliferation, with the copolymers characterized by a myosin heavy chain expression, which appeared to be up to twofold increased on respect to the one of PBS homopolymer.

Prediction of the phase behavior of BTEX and alkane hydrocarbons in the presence of Tri-Ethylene Glycol (TEG) solvent

ABSTRACTA computational framework according to the CPA Equation of state by considering hydrogen bonding association and solvation effects has been proposed for accurate prediction of phase behavior of complex mixtures of triethylene glycol (TEG), BTEX aromatic hydrocarbons (benzene, toluene, ethylbenzene, and o-xlylene) and alkanes (methane, ethane, propane). The overall average absolute deviation between the predicted and measured phase compositions, regarding 150 data points is about 2.40% suggesting the accuracy of the presented approach. The presented model can be used for accurate design of BTEX containing natural gas dehydration plants in petroleum industry.

The effect of a TEG additive on hydrate formation

ABSTRACTIn gas industry, gas hydrate formation has both advantages and disadvantages. The best advantage of gas hydrate is Persian Gulf water sweetening, carbon dioxide capture, and gas storage, and its drawbacks are pressure drop, plugging, and explosion in pipelines. In recent years, using the inhibitors to prevent hydrate formation is being considered among researchers. In this study, the new equilibrium data for hydrate formation of inlet natural gas to Gachsaran NGL-1200 refinery with addition of Tri ethylene glycol (TEG) with mass concentration of 5% and 15% in distilled and Persian Gulf waters were measured by constant-volume method. The experimental results show that the hydrate formation conditions will be hard with the increase of TEG concentration in distillated and Persian Gulf waters. In other words, TEG addition to Persian Gulf water had more inhibitory effect in hydrate formation than TEG addition to distilled water. The hydrate formation temperature, in pressure range of 28–29 bars, reduced 0.3°C and 2.7°C for distilled water and 2.8°C and 4.6°C for Persian Gulf water in presence of TEG with mass concentration of 5% and 15%, respectively.

Ab Initio Molecular Dynamics Simulations of an Excess Proton in a Triethylene Glycol-Water Solution: Solvation Structure, Mechanism, and Kinetics.

We investigate the solvation shell structures, the distribution of protonic defects, mechanistic details, kinetics, and dynamics of proton transfer for an excess proton in bulk water and for an excess proton in an aqueous solution of triethylene glycol (TEG) via Car-Parrinello molecular dynamics simulations. The PW91, PBE, and PBE with the Tkatchenko-Scheffler (TS) density-dependent dispersion functionals were used and compared for bulk water and the TEG-water mixtures. The excess proton is found to reside predominantly on water molecules but also resides on hydroxyl groups of TEG. The lifetimes associated with structural diffusion time scales of the protonated water were found to be on the order of ∼1 ps. All three functionals studied support the presolvation requirement for structural diffusion. The highest level of theory shows a reduction in the free energy barrier for water-water proton transfer in TEG-water mixtures compared to bulk water. The effect of TEG shows no strong change in the kinetics for TEG-water mixtures compared to bulk water for this same level of theory. The excess proton displays burst-rest behavior in the presence of TEG, similar to that found in bulk water. We find that the TEG chain disrupts the hydrogen-bond network, causing the solvation shell around water to be populated by TEG chain groups instead of other waters, reducing the rigidity of the hydrogen-bond network. Methylene is a dominant hydrogen bond donor for the protonated water in hydrogen-bond networks associated with proton transfer and structural diffusion. This is consistent with previous studies that have found the hydronium ion to be amphiphilic in nature and to have higher proton mobility at oil-water interfaces.

Changes in hydrogen bonding in protein plasticized with triethylene glycol

ABSTRACTBloodmeal decolored with 4 wt % peracetic acid can be extruded into a semi‐transparent bio‐plastic through the addition of sodium dodecyl sulfate (SDS), water, and triethylene glycol (TEG). TEG is often used to plasticize protein thermoplastic materials because of its ability to form both hydrophobic and hydrogen bonds. Synchrotron‐based FT‐IR was used to monitor changes in the types of hydrogen bonding occurring in TEG plasticized protein during heating. Heating was found to overcome a portion of the weaker hydrogen bonds found within and between proteins, observed as a blue‐shift in the N‐H and O‐H stretching vibrations occurring at ∼3280 cm−1. TEG was shown to be involved in a larger array of hydrogen bonding environments after heating, evidenced by the broadening of the C‐OH stretch around 1076 cm−1, suggesting improved plasticizer‐protein interactions. Additionally, these bonds were found to be as strong as the original interactions, observed as a shift in the C‐OH peak back to its original wavenumber (∼1076 cm−1) during cooling. Initially, TEG was spatially distributed into distinct plasticizer‐rich and plasticizer‐poor domains, giving rise to two glass transitions. Heating allowed the migration and uniform dispersion of TEG throughout the material, and merged the two glass transitions into one broader glass transition region. Heating during DSC removed the peak around 60°C corresponding to the enthalpy of relaxation, which is associated with physical aging of amorphous and semi‐crystalline polymers. While physical aging occurred during the storage of DBM, in the presence of TEG it occurred to a lesser extent. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42166.

On the role of triethylene glycol in the preparation of highly active Ni-Mo/Al2O3 hydrodesulfurization catalysts: A spectroscopic study

The interaction of triethylene glycol (TEG) with alumina and its role in preparing improved NiMo/Al2O3 hydrodesulfurization catalysts was investigated by spectroscopic methods. The FT-IR study shows that TEG is mainly adsorbed on the corners and edges of the alumina microcrystals where the strongest Lewis sites and the higher νOH frequency hydroxyl groups are mainly located. It is also observed that the MoO stretching vibration of surface molybdenyl groups in the oxide catalyst precursor is shifted down in the presence of TEG, indicating a lower interaction with the alumina surface. The IR spectra of CO adsorbed on the reduced/sulfided NiMo/Al2O3 catalysts confirm that the amount of promoted phase (NiMoS sites) increases in the samples prepared with TEG. Accordingly, the activity measurements in the HDS of 4,6-dimethyldibenzothiophene show that the catalyst prepared with TEG is more active than the one prepared without it. It is proposed that TEG and its decomposition products, formed upon heating (mainly acetates) occupy preferably the strongly interacting edge and corner sites of the alumina crystals, forcing the Mo and Ni species to migrate mainly to the less reactive plane faces. This weakens the metal-support interaction allowing a better sulfidation and, at the same time, favoring the Ni–Mo interaction and the formation of the promoted NiMoS phase.

Facile fabrication of safe and robust polyimide fibrous membrane based on triethylene glycol diacetate-2-propenoic acid butyl ester gel electrolytes for lithium-ion batteries

Robust electrospun polyimide (PI) membranes are simply fabricated by polymerization of oxidianiline (ODA) and pyromellitic dianhydride (PMDA). The as-prepared PI membranes, with reliable safety (self-extinguishing) and excellent mechanical property, exhibit highly uniform morphology with an average fiber diameter ∼ 600nm, high porosity ∼67%, high electrolyte uptake ∼534% and good relative absorption ratio ∼75% of the initial absorption (electrolyte uptake until 240min). With the presence of triethylene glycol diacetate-2-propenoic acid butyl ester (TEGDA-BA) gel electrolytes, the resulting polyimide-gel electrolytes (PI-GEL) show a high ionic conductivity up to 2.0×10−3Scm−1 at 25°C, coupled with high electrochemical stability (>4.5V vs. Li/Li+). The Li/PI-GEL/LiFeO4 cells demonstrate remarkably stable charge/discharge performance and excellent capacity retention of ∼146.8mAhg−1 (0.1C) after 100 cycles. The results suggest a facile strategy for scalable fabrication of high-performance polymer electrolyte membrane for lithium ion batteries.

Influence of nanotube physicochemical properties on the decoration of multiwall carbon nanotubes with magnetic particles

Two types of commercial multiwall car- bon nanotubes (MWCNTs) with different diameters and physicochemical properties were decorated with iron oxide nanoparticles obtained by hydrolysis at high temperature in the presence of triethylene glycol and iron(III) chloride as metal precursor. A homoge- neous distribution of 2-9 nm diameter particles dec- orating the MWCNTs was achieved using a weight concentration of 1:1 or 1:2 of the nanotube with respect to the metal precursor for 30 min of reflux. Detailed characterization of the as-received MWCNTs allowed to correlate the influence of the initial nanotube physicochemical properties to their decoration. The results indicate that a more homoge- neous decoration and larger magnetization are achieved for MWCNTs with larger density of defec- tive/reactive sites and larger surface area.

Synthesis, structural, magnetic and electrical properties of Co1−xZnxFe2O4 (x = 0.0, 0.2) nanoparticles

Co1−xZnxFe2O4 spinel nanoparticles with Zn concentrations of x=0.0, 0.2 were prepared by a hydrothermal route in the presence of triethylene glycol (TEG). The structural, magnetic, electrical and dielectric properties of the prepared nanoparticles were studied. The XRD results confirmed the formation of single spinel ferrite structure with crystallite size 9 and 10nm for x=0.0 and 0.2 compositions respectively. The lattice parameter (a) increased with increasing Zn concentration. Temperature and frequency dependent electrical and dielectric properties of the prepared ferrites have also been investigated. Our findings show that overall conductivity of Co0.8Zn0.2Fe2O4 nanoparticle is lower than that of CoFe2O4 and roughly in the range of 10−11–10−7Scm−1 depending strongly temperature and frequency owing to the formation of stable electric bonds between the Zn2+ and Fe2+ ions, which localizes Fe2+ charge carriers. The ac conductivity showed a temperature dependent behavior at low frequencies and temperature independent behavior at high frequencies, which is an indication of ionic conductivity. dc conductivity of Co0.8Zn0.2Fe2O4 nanoparticle are found to obey the Arrhenius plot and can be classified into two regions over with activation energy of 0.113 and 0.163eV in the ranges of 20–40°C and 70–120°C, respectively when CoFe2O4 has an activation energy of 0.245eV.

Development of Stable, Water-Dispersible, and Biofunctionalizable Superparamagnetic Iron Oxide Nanoparticles

Water-dispersible superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by thermal decomposition of iron(III) acetylacetonate in the presence of triethylene glycol (TREG). The resulting TREG-coated SPIONs were not stable, undergoing agglomeration and loss of the TREG coating under prolonged storage at 37 °C or in the presence of increased saline concentrations. To avoid these problems, stable colloidal TREG-coated SPIONs were obtained by two different procedures: (i) dimercaptosuccinic acid (DMSA) ligand-exchange reactions to obtain DMSA-coated SPIONs and (ii) chemical modification of the TREG coating. Both procedures, but especially the DMSA exchange, increased the stability of the SPION suspension. Finally, the functionality of both types of particles for biological applications was demonstrated by conjugating a model antibody to the end carboxyl groups of the SPIONs and testing the immunoreactivity of the final antibody–particle conjugates by an enzyme-linked immunosorbent assay (ELISA).

The use of magnetite nanoparticles for implant-assisted magnetic drug targeting in thrombolytic therapy

Implant-assisted targeting of magnetic particles under the influence of an external magnetic field has previously been verified through mathematical modeling, in vitro studies, and in vivo studies on rat carotid arteries as a feasible method for localized drug delivery. The present study focuses on the development of nanoparticles for the treatment of in-stent thrombosis. Magnetic nanoparticles in the size-range 10–30 nm were synthesized in a one-pot procedure by precipitation of ferrous hydroxide followed by oxidation to magnetite. The nanoparticles were silanized with tetraethyl orthosilicate in the presence of triethylene glycol and/or polyethylene glycol. The surface coated magnetite nanoparticles were activated with either N-hydroxysulfosuccinimide or tresyl chloride for covalent immobilization of tissue plasminogen activator (tPA). Hysteresis loops showed saturation magnetizations of 55.8, 44.1, and 43.0 emu/g for the naked nanoparticles, the surface coated nanoparticles, and the tPA-nanoparticle conjugates, respectively. The hemolytic activity of the nanoparticles in blood was negligible. An initial in vivo biocompatibility test in pig, carried out by intravascular injection of the nanoparticles in a stented brachial artery, showed no short-term adverse effects. In vitro evaluation in a flow-through model proved that the nanoparticles were captured efficiently to the surface of a ferromagnetic coiled wire at the fluid velocities typical for human arteries. A preliminary test of the tPA-nanoparticle conjugates in a pig model suggested that the conjugates may be used for treatment of in-stent thrombosis in coronary arteries.

Osmolyte Changes the Binding Affinity and Mode of Interaction of Minor Groove Binder Hoechst 33258 with Calf Thymus DNA

The aim of this work was to investigate the effect of altered water activity on Hoechst 33258-calf thymus DNA (CtDNA) interaction by using osmotic stress approach. Water activity was changed by using osmolytes viz., sucrose and triethylene glycol (TEG). We have reported the results of thermal denaturation, absorption and fluorescence spectroscopy and binding affinity measurements as a function of osmolytes concentration. TEG dramatically lowered the thermal stability of CtDNA, ΔT(m)=-16 °C whereas sucrose induced very little decrease. Hoechst 33258 increases the stability of CtDNA, but in the presence of TEG, the ΔT(m) was -37 °C and a marginal decrease was observed with sucrose. Binding affinity of Hoechst 33258 with CtDNA was found to be reduced from 4.75×10⁷ to 0.16×10⁷ M⁻¹ in TEG and this was accompanied with the increased uptake of 74±2 water molecules. In the presence of sucrose this uptake of water molecules was found to be 30±1. Method of continuous variation suggests that the osmolytes lowered the stoichiometry of Hoechst 33258-CtDNA complex. On the contrary, van't Hoff plot revealed the hydrophobic interaction (ΔS=130.66 J mol⁻¹ K⁻¹) between the Hoechst 33258 and CtDNA. The detailed absorption and fluorescence spectral measurements including the fluorescence lifetime and anisotropy indicated bound state of Hoechst 33258 in osmotic stress condition. Fluorescence lifetime measurement revealed that the contribution from the planar conformer of Hoechst 33258 dominated the binding interaction with CtDNA in presence of TEG. These results can be useful for understanding of interaction of Hoechst 33258 with genomic DNA in a complex environment having altered water activity.

The influence of triethylene glycol derived from dental composite resins on the regulation of Streptococcus mutans gene expression

Bacterial microleakage along the tooth/composite resin dental restoration interface contributes to post-operative sensitivity, recurrent caries, pulp inflammation and necrosis. Studies have confirmed that saliva can catalyze the degradation of constitutive monomers in dental restorative composites, forming biodegradation by-products (BBPs) such as methacrylic acid (MA), and triethylene glycol (TEG). TEG accelerates the growth of Streptococcus mutans, a major etiological agent of dental caries. Restriction fragment differential display polymerase chain reaction (RFDD-PCR) in conjunction with single strand conformation polymorphism (SSCP) was used to identify S. mutans genes with differential expression when grown in the presence of TEG at pH levels 5.5 and 7.0. Quantitative real-time PCR (q-RT PCR) was utilized to study specific gene expression patterns. TEG modulated the expression levels of glucosyltransferase B ( gtfB) (involved in biofilm formation) and yfiV (a putative transcription regulator) in S. mutans. The expression patterns were dependent on the bacterial growth mode (planktonic vs. biofilm) as well as pH (5.5 vs. 7.0). The findings describe the effect of composite resin-derived BBPs on important physiological functions of S. mutans (at BBP concentration levels found in vivo), and indicate the potential influence of BBPs in biofilm formation and microbial survival on surfaces in the oral cavity.

The effect of glycol on phosphate-doped CoMo/Al 2O 3 hydrotreating catalysts

γ-Al 2O 3-supported CoMo catalysts doped with phosphate and prepared in the presence of triethylene glycol (TEG), ethylene glycol (EG), and triethylene dimethyl ether (TEG-DME) were tested in the hydrodesulfurization (HDS) of thiophene. The catalyst containing TEG showed a higher catalytic activity than the catalyst prepared without TEG. Laser Raman spectroscopy and EXAFS demonstrated that the impregnation solution containing the metal salts and phosphoric acid contained HP 2Mo 5 O 23 5 − diphosphopentamolybdate and that this anion was not affected by the presence of TEG. 31P NMR measurements of the impregnation solution showed a paramagnetic effect of cobalt, which proved that cobalt is complexed by the diphosphopentamolybdate, both in the presence and absence of TEG. DRIFT experiments with a γ-Al 2O 3 support treated with TEG proved that glycol interacts with the basic OH s groups and coordinatively unsaturated Al 3+ sites. The diphosphopentamolybdate complexes are decomposed by these sites on the γ-Al 2O 3 support, but EXAFS of the dried catalyst precursor showed that in the presence of glycol this decomposition was partially prevented. This favored the precipitation in the alumina pores of clusters in which Co and Mo are in close proximity. Because of their high Co / Mo atomic ratio, these complexes lead to an efficient decoration of the MoS 2 slabs by the promoter atoms during the sulfiding treatment, thus increasing the catalytic performance of the supported CoMo catalyst.

Effect of oligomers of ethylene glycol on thermotropic phase transition of dipalmitoylphosphatidylcholine multilamellar vesicles

The effect of oligomers of ethylene glycol (EG) on thermotropic phase transitions of dipalmitoylglycerophosphatidylcholine multilamellar vesicles (DPPC-MLV) were investigated. Diethylene glycol (di-EG) had a biphasic effect on transition temperature, reducing pre-transition temperature ( T p) at low concentrations but increasing main transition temperature ( T m) and extinguishing pre-transition at high concentrations. Results of the X-ray diffraction method and the excimer method indicated that di-EG induced interdigitated gel phase (L β1 phase) in the DPPC membranes at high concentration. Phase diagram of temperature-di-EG concentration for DPPC-MLV was determined by use of X-ray diffraction and differential scanning calorimetry, which was similar to that of temperature-EG concentration. The minimum concentration of di-EG where L β1 phase was induced was 42%(w/v), which was larger than that of EG (30%(w/v)). On the other hand, in the presence of triethylene glycol (tri-EG), T m and T p increased with an increase in tri-EG concentration, as well as poly(ethylene glycol). These differences, between the effects of di-EG and those of tri-EG, might be due to the differences of their sizes.