The visible and near-infrared (vis-NIR) fluorescence of graphene oxide nanosheets (GO) shows a reversible and sensitive response to ionic strength and pH, in particular a linear physiological pH dependence for monitoring extracellular pH evolution during growth and metabolism of normal and cancer cells.

An experimental study on colloidal aggregation in two dimensions is presented. This study shows that a high amount of electrolyte concentration is necessary to screen the particle interactions and to induce the aggregation process. Our results indicate that the stability of the colloidal particles, with a diameter of 735 nm, increases when they are trapped at the air-water interface. The reason...

We demonstrate the utility of electrospray gas-phase ion-mobility analysis as a new method to investigate nanoparticle flocculation, or aggregation. Au nanoparticle (Au-NP) solutions were sampled via electrospray (ES), followed by differential ion-mobility analysis (DMA) to determine the particle mobility distribution. Multimodal size distributions obtained with ES-DMA indicated the presence of...

The ability of Escherichia coli O157:H7 to survive in acidified vegetable products is of concern because of previously documented outbreaks associated with fruit juices. A study was conducted to determine the survival of E. coli O157:H7 in organic acids at pH values typical of acidified vegetable products (pH 3.2 and 3.7) under different dissolved oxygen conditions (< or = 0.05 and 5 mg/liter) ...

The adsorption of polyacrylic acid (PAA) on hydroxyapatite (HAP) from HAP saturated solutions was studied in this work as a function of PAA concentration, temperature, pH and ionic strength. In all experiments, the adsorption was studied under conditions of negatively charged adsorbent and adsorbate, respectively. These conditions ensured that adsorption was not electrostatically favored. The s...

Increasing the intramuscular stores of total creatine [TCr = creatine (Cr) + creatine phosphate (CrP)] can result in improved muscle performance during certain types of exercise in humans. Initial uptake of Cr is accompanied by an increase in cellular water to maintain osmotic balance, resulting in a decrease in myoplasmic ionic strength. Mechanically skinned single fibers from rat soleus (SOL)...

Deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase (EC 2.7.7.6) from Acinetobacter calcoaceticus was purified to apparent homogeneity and its properties were compared with those of the Escherichia coli B enzyme. The molecular weights of the two native active enzymes as well as their alpha and beta subunits appeared to be similar. No subunit corresponding to that of sigma fr...

Interaction between the Gla-domain of coagulation proteins and negatively charged phospholipid membranes is essential for blood coagulation reactions. The interaction is calcium-dependent and mediated both by electrostatic and hydrophobic forces. This report focuses on the electrostatic component of factor IX activation via the extrinsic pathway. Effective charges during the reaction are measur...

Ionic liquids (ILs) were synthesized inside a porous metal-organic framework (MIL-101) via a ship-in-bottle (SIB) technique. Unlike previously reported IL-incorporated MIL-101s, IL@MIL-101 prepared by the SIB approach was very stable over several cycles for the liquid phase adsorption of benzothiophene from liquid fuel.

The Hildebrand solubility parameters have been calculated for eight ionic liquids. Retention data from the inverse gas chromatography measurements of the activity coefficients at infinite dilution were used for the calculation. From the solubility parameters, the enthalpies of vaporization of ionic liquids were estimated. Results are compared with solubility parameters estimated by different me...