The addition of a macromolecular crowding agent to a dilute solution of polymer exerts a compressive force that tends to reduce the size of the chain. We study here the effect of changing the size ratio between the random coil and the crowding agent. The compression occurs at lower crowding agent concentration, Φ when polymer molecular weight increases. The Flory exponent ν(Φ) decreases from ν(...

The dynamics of phase separation of a quenched polymer solution is studied using a stochastic molecular dynamics simulation. At early times, the elastic nature of the polymer chains generates a networklike domain morphology for sufficiently dense polymer solutions. However, at late times, this network structure breaks up into disconnected polymer-rich domains to minimize the interfacial energy....

This note is a summary of the state-of-the-art for determining molecular weight distributions from melt rheological properties. It consists of a short introduction, including a summary of the models used, and then focuses on the so-called “Modulus Model” with emphasis on an evaluation of the recently commercialized software from Rheometric Scientific, Inc. It will conclude with a short look int...

The aim of the present study was to determine the effect of post-exercise ingestion of a unique, high molecular weight glucose polymer solution, known to augment gastric emptying and post-exercise muscle glycogen re-synthesis, on performance during a subsequent bout of intense exercise. On three randomized visits, eight healthy men cycled to exhaustion at 73.0% (s = 1.3) maximal oxygen uptake (...

The tools for optically imaging cellular potassium concentrations in real-time are currently limited to a small set of molecular indicator dyes. Quantum dot-based nanosensors are more photostable and tunable than organic indicators, but previous designs have fallen short in size, sensitivity, and selectivity. Here, we introduce a small, sensitive, and selective nanosensor for potassium measurem...

Peptide self-assembly, ubiquitous in biology, is one of the most promising 'bottom-up' approaches for the generation of synthetic supramolecular architectures. However, directing the self-assembly of functional peptides into predictable ordered structures most often requires precise tuning of weak intermolecular forces. Existing strategies are generally based on specific interactions between mo...

A novel pH sensitive, colorimetric ionic liquid nanosensor based on phosphonium salts of fluorescein is reported. Herein, fluorescein salts of various stoichiometries were synthesized by use of a trihexyltetradecylphosphonium cation [TTP]+ in combination with dianionic [FL]2- and monoanionic [FL]- fluorescein. Nanomaterials derived from these two compounds yielded contrasting colorimetric respo...

A novel fluorescent nanosensor has been developed by combining super fluorescence quenching ability of graphene oxide and hybridization chain reaction amplification, which enables highly sensitive detection of base excision repair enzyme activity with a wide dynamic range from 0.0001 to 100 U mL(-1) and a detection limit of 0.00006 U mL(-1).

We present molecular dynamics friction calculations for confined hydrocarbon "polymer" solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: (a) polymer sliding against a hard substrate and (b) polymer sliding on polymer. We discuss the velocity dependence of the frictional shear stress for both cases. In our simulations, the polymer films are very thin (approxim...

Novel fluorescent (FL) ag-oxCDs are derived from expired agar and oxalate. selective for Fe 3+ ions detection (LOD ∼ 75 μM) via FL “turn ON” mechanism. nanosensor based on biomass with upscale potential is developed herein.