Presence Of Polyethylene Glycol Research Articles

Gold and gold–copper nanoparticles in 2-propanol: A radiation chemical study

The studies on the reduction of Au 3+ to gold nanoparticles in presence and absence of Cu 2+ under deoxygenated conditions in 2-propanol by radiolytic method have been carried out. On γ-radiolysis, preliminary yellow colored solution of Au 3+ changed to purple color owing to gold nanoparticles formation, which exhibits an absorption peak at around 540 nm. In the presence of Cu 2+, absorption of gold–copper nanoparticles, which was also produced during γ-radiolysis, was red shifted in contrast to the system containing no Cu 2+. Under DLS studies the sizes of gold nanoparticles in the absence and the presence of Cu 2+ were found to be larger (>400 nm). However, in presence of polyethylene glycol, a stabilizer the nanoparticle sizes became smaller, sizes measured for gold and gold–copper nanoparticles are 40 and 140 nm, respectively. Moreover, the change in UV–vis spectra in the Cu 2+ and Au 3+ mixed system highlights the formation of gold–copper nanoparticles in core–shell type arrangement.

Water soluble polymer stabilized iron(0) nanoclusters: A cost-effective and magnetically recoverable catalyst in hydrogen generation from the hydrolysis of sodium borohydride and ammonia borane

Water soluble polymer stabilized iron(0) nanoclusters were prepared from the reduction of iron(III) chloride by sodium borohydride (SB) and ammonia borane (AB) mixture in the presence of polyethylene glycol (PEG) as stabilizer and ethylene glycol as solvent at 80°C under nitrogen atmosphere. PEG stabilized iron(0) nanoclusters were isolated from the reaction solution by centrifugation and characterized by UV–Vis, TEM, HRTEM, XRD, ICP-OES and FT-IR methods. The particle size of PEG stabilized iron(0) nanoclusters ranges from 4.0nm to 8.5nm with a mean value of 6.3nm. They are redispersible in water and yet highly active catalysts in hydrogen generation from the hydrolysis of SB and AB. They provide a turnover frequency of TOF=6.2 and 6.4min−1 for the hydrolysis of SB and AB at 25.0±0.5°C, respectively. The TOF values are the best ever reported for the iron catalysts and comparable to other non-noble metal catalyst systems in both hydrolysis reactions. Kinetics of hydrogen generation from the hydrolysis of AB in the presence of PEG stabilized iron(0) nanoclusters was also studied by varying the catalyst concentration, substrate concentration, and temperature. This is the first kinetic study on the hydrolysis of AB in the presence of an iron catalyst. Moreover, PEG stabilized iron(0) nanoclusters can be separated magnetically from the catalytic reaction solution using a magnet and show catalytic activity even after tenth run.

A one-pot multicomponent reaction for synthesis of 1-amidoalkyl-2-naphthols catalyzed by PEG-based dicationic acidic ionic liquids under solvent-free conditions

A mild and efficient method was developed for preparation of amidoalkyl naphthols via one-pot three-component condensation of aldehydes with amides and 2-naphthol in the presence of polyethylene glycol (PEG)-based dicationic acidic ionic liquid as a powerful catalyst under solvent-free conditions. Excellent yields, short reaction time, simple work-up, and reusable catalyst are advantages of this procedure.

Visualization of the synergistic effect of lithium acetate and single-stranded carrier DNA on Saccharomyces cerevisiae transformation

Transformation is an indispensable method for the genetic manipulation of cells. Saccharomyces cerevisiae can be transformed by incubating intact cells and plasmid DNA in the presence of polyethylene glycol alone. Lithium acetate (LiAc) and single-stranded carrier DNA (ssDNA) enhance the transformation efficiency, but the mechanism underlying this enhancement has remained elusive. In this study, we first confirmed that LiAc and ssDNA synergistically improve the transformation efficiency of S. cerevisiae intact cells. We then used transmission electron microscopy to observe the cell walls of yeast incubated with both LiAc and ssDNA in the presence of negatively charged Nanogold (in this context, a mimic of DNA). Under these conditions, the cell walls exhibited protruded, loose, and porous structures. The Nanogold was observed within the cell wall, rather than on the surface. We also made observations using YOYO-1, a fluorescent DNA probe. Based on the transmission electron microscopy and fluorescence data, we speculated that ssDNA covers the whole cell and enters, at least partially, into the cell wall structure, causing the cell wall to become protruded, loose, and porous; meanwhile, LiAc produces effect on the cell wall. Together, the two compounds synergistically enhance the transformation efficiency and frequency.

Mechanical properties of some pigmented and unpigmented aqueous-based film coating formulations applied to aspirin tablets.

The Brinell hardness and Young's modulus of pigmented and unpigmented films of hydroxypropyl methylcellulose alone, and in combination with either polyethylene glycol 400 (plasticizer) or polyvinyl alcohol, which were applied to aspirin tablets, have been measured. Generally hardness and modulus data showed similar trends. The hardness and modulus of hydroxypropyl methylcellulose fell in the presence of polyethylene glycol 400 as a result of its plasticizing action. On the other hand, the hardness and modulus of the film former rose slightly when polyvinyl alcohol was initially incorporated, probably due to the crystalline phase of the additive, and then decreased when the level of the additive was further raised. Hardness and modulus were higher in films pigmented with talc than in those containing titanium dioxide because of the plate-like shape of talc and its greater interaction with the polymer systems. Some correlation was found between the Young's moduli of the applied films and those of the corresponding free films, with the moduli of the latter two 2-5 times greater. Ageing at 37 degrees C and 75% r.h. was found to cause a decrease in the mechanical properties of the unplasticized film coating systems probably as a result of decreased molecular order and enhanced polymer chain mobility.

Crystallization and preliminary X-ray diffraction analysis of recombinant chlorocatechol 1,2-dioxygenase from Pseudomonas putida.

Chlorocatechol 1,2-dioxygenase from the Gram-negative bacterium Pseudomonas putida (Pp 1,2-CCD) is considered to be an important biotechnological tool owing to its ability to process a broad spectrum of organic pollutants. In the current work, the crystallization, crystallographic characterization and phasing of the recombinant Pp 1,2-CCD enzyme are described. Reddish-brown crystals were obtained in the presence of polyethylene glycol and magnesium acetate by utilizing the vapour-diffusion technique in sitting drops. Crystal dehydration was the key step in obtaining data sets, which were collected on the D03B-MX2 beamline at the CNPEM/MCT - LNLS using a MAR CCD detector. Pp 1,2-CCD crystals belonged to space group P6(1)22 and the crystallographic structure of Pp 1,2-CCD has been solved by the MR-SAD technique using Fe atoms as scattering centres and the coordinates of 3-chlorocatechol 1,2-dioxygenase from Rhodococcus opacus (PDB entry 2boy) as the search model. The initial model, which contains three molecules in the asymmetric unit, has been refined to 3.4 Å resolution.

Polyethylene glycol이 3가크롬 전기도금에 미치는 효과

The effect of organic additives, polyethylene glycol (PEG), on the trivalent chromium electroplating was analysed in the view point of current efficiency, solution stability and metallurgical structure. It was measured that PEG-containing trivalent chromium solution had about 10% higher current efficiency than pure solution and controlled the micro-crack density of electrodeposits. PEG exhibited profound effect on the solution stability by reducing the consumption rate of formic acid which acts as a complexant to lower the activation energy required for electrochemical reduction of trivalent chromium ions. It was also revealed that the formation of chromium carbide layer was facilitated in the presence of polyethylene glycol, which meant easier electrochemical codeposition of chromium and carbon, not single chromium deposition. Trivalent chromium layer formed from PEG-containing solution was amorphous with local nano-crystalline particles, which were prominently developed on the entire surface after non-oxidative heat treatment.

Enhanced Dechlorination of Tetrachloroethylene by Zerovalent Silicon in the Presence of Polyethylene Glycol under Anoxic Conditions

The combination of zerovalent silicon (Si(0)) with polyethylene glycol (PEG) is a novel technique to enhance the dechlorination efficiency and rate of chlorinated hydrocarbons. In this study, the dechlorination of tetrachloroethylene (PCE) by Si(0) in the presence of various concentrations of PEG was investigated under anoxic conditions. Several surfactants including cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Tween 80 were also selected for comparison. Addition of SDS and Tween 80 had little effect on the enhancement of PCE dechlorination, while CTAB and PEG significantly enhanced the dechlorination efficiency and rate of PCE by Si(0) under anoxic conditions. The Langmuir-Hinshelwood model was used to describe the dechlorination kinetics of PCE and could be simplified to pseudo-first-order kinetics at low PCE concentration. The rate constants (k(obs)) for PCE dechlorination were 0.21 and 0.36 h(-1) in the presence of CTAB and PEG, respectively. However, the reaction mechanisms for CTAB and PEG are different. CTAB could enhance the apparent water solubility of PCE in solution containing Si(0), leading to the enhancement of dechlorination efficiency and rate of PCE, while PEG prevented the formation of silicon dioxide, and significantly enhanced the dechlorination efficiency and rate of PCE at pH 8.3 ± 0.2. In addition, the dechlorination rate increased upon increasing PEG concentration and then leveled off to a plateau when the PEG concentration was higher than 0.2 μM. The k(obs) for PCE dechlorination by Si(0) in the presence of PEG was 106 times higher than that by Si(0) alone. Results obtained in this study would be helpful in facilitating the development of processes that could be useful for the enhanced degradation of cocontaminants by zerovalent silicon.

ChemInform Abstract: Novel Method for Preparing NH4NiPO4·6H2O: Hydrogen Bonding Coacervate Selective Self‐Assembly.

AbstractThe title compound is synthesized for the first time by room temperature solid state reaction of NiSO4·6H2O and (NH4)3PO4·3H2O in the presence of polyethylene glycol PEG‐400 surfactant (grinding, 40 min).

Exploring the Folding Landscape of RNA in Crowded Solutions

Crowder molecules in solution alter the configuration potential energy landscape of biological macromolecules. It is therefore critical to account for the influence of these other molecules when describing the folding of RNA inside the cell. Small angle x-ray scattering experiments were used to measure folding of a 64 kDa bacterial group I ribozyme in the presence of polyethylene-glycol with different molecular weights. We find that crowder molecules stabilize more compact states of the unfolded RNA, and also stabilize the folded state with respect to the unfolded state, as measured via the lowering of the folding midpoint on a MgCl2 titration. In addition, stopped-flow SAXS experiments with millisecond resolution show that the addition of crowder molecules speeds up the folding of RNA, even when the stability of the final folded state is held constant. These data indicate that crowder molecules change the folding landscape for RNA, allowing it to fold efficiently in Mg2+ concentrations that are well within the physiological range.

Effect of cation–oligomer interactions on the size and reducibility of NiO particles on NiRu/SiO2 catalysts

A NiRu/SiO2 catalyst was prepared by a new method. The presence of polyethylene glycol (PEG) molecules allows their oligomer groups to interact with the metallic ions in the liquid, which creates small NiO particles (∼6 nm) that closely contact with RuO2 particles, while the PEG-free process forms large NiO particles (∼11 nm) with separated RuO2 on SiO2 after calcination in air. The formation of close contacts between NiO and RuO2 particles improves the promotional efficiency of Ru. Therefore, small NiO particles can be reduced at lower temperature than that of large NiO particles on SiO2, a finding that contrasts with the dispersion–reducibility dependence inherent to the oxide-supported nickel-based catalyst. This leads to smaller Ni particles (∼11 nm) on the PEG-additive-derived NiRu/SiO2-CP catalyst, in contrast to NiRu/SiO2-C (∼28 nm) catalyst prepared by the PEG-free process. In the methanation reaction, the NiRu/SiO2–CP catalyst has a lower initial turnover frequency (TOF) per mole of surface Ni, however, it shows better long-term stability. Instead, as a result, the NiRu/SiO2-CP catalyst has a higher TOF after reaction for 30 h than the NiRu/SiO2-C catalyst, which deactivates due to the deposition of less reactive carbon species.

Study on visible light photocatalytic activity and mechanism of spherical Bi12TiO20 nanoparticles prepared by low-power hydrothermal method

Bismuth titanate (Bi12TiO20) nanoparticles with spherical structures and good dispersion were synthesized hydrothermally using C6H13BiN2O7·H2O and TiCl3 in the presence of polyethylene glycol (PEG). Only 2h of hydrothermal process was needed which means the whole process of preparation was a less power consumption. X-ray diffraction (XRD) proved that the samples were in pure cubic phase. UV–vis diffuse reflection spectra showed the band gap of Bi12TiO20 is about 2.65eV. Brunauer–Emmett–Teller (BET) analysis showed that the Bi12TiO20 samples have higher surface areas. Visible-light-induced photodegradation of acid orange 7 (AO7) on Bi12TiO20 was investigated. It was found that Bi12TiO20-assisted photocatalytic degradation of AO7 occurs via two processes: the photocatalytic process of Bi12TiO20 semiconductor and the photosensitized process of AO7. Photocatalytic experiments in the presence of N2 and the radical scavenger suggested that OH and O2− are two main active species in the whole degradation process.

Soybean Peroxidase‐Catalyzed Removal of an Aromatic Thiol, 2‐Mercaptobenzothiazole, from Water

This paper demonstrates, for the first time, the capability of soybean peroxidase (SBP), an enzyme, for catalyzing the removal of an aromatic thiol, 2-mercaptobenzothiazole (MBT), from aqueous solution. The optimum pH for enzymatic conversion of MBT in aqueous buffer was found to be in the range 6.0 to 9.0. The optimum hydrogen peroxide (H2O2): MBT stoichiometry was 0.6. In terms of standard units (U) of catalytic activity, the minimum SBP concentration required for 95% conversion of 1.0 mM MBT in 3 hours was found to be 0.9 U/mL. The presence of polyethylene glycol at 50 mg/L can reduce the enzyme concentration required for the same conversion by 3-fold. It is proposed that these findings should be the basis for viable and cost-effective treatment of MBT in industrial wastewater and/or process water.

PEG-6000 Assisted Growth of Copper Dendrites

Highly uniform copper dendrites were successfully prepared in large quantities by a simple wet chemical approach using hydrazine hydrate as reducant in the presence of polyethylene glycol 6000 (PEG-6000) at room temperature. Scanning electron microscopy (SEM), ultraviolet (UV)-vis absorption spectroscopy, and x-ray diffraction (XRD) have been used to characterize the obtained products. It is found that the architecture of copper particles is drastically influenced by the mass ratio of PEG-6000/CuSO4(aq), PEG-6000/N2H4 · H2O, CuSO4(aq)/N2H4 · H2O and the concentration of precursors. It is revealed that PEG-6000 might play both capping reagent and dispersion reagent roles.

Synergistic inhibition effect of polyethylene glycol–polyvinyl pyrrolidone blends for mild steel corrosion in sulphuric acid medium

AbstractThe corrosion inhibition of mild steel in sulphuric acid solution in the presence of polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP), and their blends was investigated using weight loss and hydrogen evolution techniques at temperature range of 30–60°C. It was found that inhibition efficiency (η%) increases with increase in concentration of the homopolymers and decreases with increase in temperature. Inhibition efficiency was found to be synergistically enhanced on blending the two polymers with highest inhibition efficiency obtained for (PEG : PVP) blending ratio of 1 : 3. The experimental data obtained fitted well into Temkin adsorption isotherm model. Physical adsorption mechanism is proposed from the trend of inhibition efficiency with temperature. The proposed mechanism is also corroborated by kinetic and thermodynamic parameters obtained. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

ChemInform Abstract: A Convenient and New Modified Preparation of Nitrosubstituted Aryl Fluorides.

Nitrosubstituted aryl fluorides are easily prepared in good yields from chloro-nitrobenzenes and potassium fluoride in dimethyl sulfoxide and in the presence of polyethylene glycol 5090.

Stability of Human Salivary Lactate Dehydrogenase in the Present of Ethylenediaminetetraacetic Acid, Glycerol and Polyethylene Glycol at Various Temperatures: Preliminary Study

This study aims to determine the best storage condition for salivary lactate dehydrogenase due to decreased in native enzyme’s activity after seven days of storage. Saliva samples were collected from five healthy and good oral hygiene patients. The specific enzyme activities were measured after 0 (control), 1 and 2 weeks of storage treated with 2.5 mM ethylenediaminetetraacetic acid, 10% (v/v) glycerol or 15% (w/v) polyethylene glycol at three different temperatures, i.e., room temperature, 4 and -20°C. Enzyme activity (unit mL-1) was based on the rate of Nicotinamide Adenine Dinucleotide oxidations standardized at 30°C. The rate of oxidation directly proportional to enzyme’s activity was measured at 340 nm. The specific activity (unit mg-1) was determined through estimated protein content using Bradford analysis. The data were statistically analyzed with paired t-test based on average percentage of enzyme activities from three independent experiments. After two weeks, saliva sample in the presence of polyethylene glycol showed no significant different (p>0.01) at all three temperatures compared to Lactate dehydrogenase basal activity. Lactate dehydrogenase activity of sample in the presence of ethylenediaminetetraacetic acid remained stable (p>0.01) only after a week at room temperature. On the other hand, glycerol managed to stabilize salivary lactate dehydrogenase activity for two weeks at 4 and -20°C. As conclusion, polyethylene glycol showed as the best additive for salivary lactate dehydrogenase storage whereas, ethylenediaminetetraacetic acid suitable only at room temperature for a week. In addition, glycerol was suitable only in cooler conditions.

Synthesis of mesoporous ZSM-5 by one-pot method in the presence of polyethylene glycol

Mesoporous ZSM-5 was synthesized by using dual templates and one step hydrothermal crystallization method under alkali conditions. Mesopores were created by using cetyltrimethylammonium bromide (CTAB) as the template and the crystallized pore wall framework was formed by using tetrapropylammonium bromide (TPAB) as the template. The specific influences of the polyethylene glycol (PEG) and ammonium fluoride (NH 4F) addition, hydrothermal crystallization temperature, TPAB/Si and Al/Si ratio to the mesostructure and crystallinity of the obtained samples were carefully studied. In this system, PEG plays an important role in the maintenance of the mesoporous pore ordering and the zeolite crystallinity. Moreover, the study on the hydrothermal stability of the sample with best mesoporous pore ordering and zeolite crystallinity showed this kind mesoporous zeolite has extremely high hydrothermal stability in boiling water.

Small angle neutron scattering study of structural aspects of nonionic surfactants (Tween 20 and Tween 80) in the presence of polyethylene glycols and triblock polymers

AbstractSmall angle neutron scattering (SANS) technique has been used to study the micellar behavior of nonionic surfactants, Tween 20 and Tween 80 with additives like polyethylene glycols (PEG with molecular mass 400, 6000, and 15,000) and triblock polymers (TBPs) of varying composition. Surfactant‐additive interactions have been explained on the basis of parameters like aggregation number (Nagg), core radius (Rc), hard sphere radius (Rhs), volume fraction (ϕ) and axial ratio (b/a). The SANS analysis indicate the reduction in values ofNaggof Tween on addition of PEG additive. Shape of Tweens (3 wt %) micelles in the presence of PEG (10 wt %) is found to oblate ellipsoidal. Similarly, the shape of Tween (3 wt %) micelles is oblate ellipsoidal at low concentration of TBPs (1 wt %); however, they become spherical as the concentration of TBP increases to 10 wt %. The shape of micelles of pure TBPs also comes out to be spherical. Results reflects that at low concentration of TBP shape is controlled by surfactant (Tween 20 and Tween 80) while at high concentration of TBP shape of mixed micelle is controlled by TBP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Sonochemical synthesis, characterization and thermal and optical analysis of CuO nanoparticles

Nanoparticles of CuO were prepared by a novel sonochemistry route from copper acetate and sodium hydroxide in the presence of polyethylene glycol (PEG), polypropylene glycol (PPG) and polyvinyl alcohol (PVA). Variations in several parameters and their effects on the structural properties of nanoparticles (particle size and morphology) were investigated. 0.05 M solution of copper acetate in the presence of PEG gave the best results. The characterizations were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), IR spectroscopy, thermal gravimetry analysis and differential thermal analysis (TGA/DTA).