Stochasticity of the transfer of reactant molecules between nano-reactors affecting the reversible association A + B ⇆ C.

Theoretical analysis and computer simulations (Monte Carlo and numerical integration of differential equations) indicate that the statistical effect of a small number of reacting molecules is affected by transfer of reagent molecules between nanoreactors (droplets in this study). As a model reaction, a simple reversible association A + B ⇆ C was chosen, which was studied previously without reagent transfer processes. For sufficiently fast exchange of reactant molecules and a sufficiently high number of nanoreactors, the studied systems virtually do not differ from large volume systems if overall kinetics and thermodynamics of the chemical process are concerned.

Effect of the Configuration of a Bulky Aluminum Initiator on the Structure of Copolymers of l,l-Lactide with Symmetric Comonomer Trimethylene Carbonate.

The effect of configuration of an asymmetric bulky initiator 2,2'-[1,1'-binaphtyl-2,2'-diyl- bis-(nitrylomethilidyne)]diphenoxy aluminum isopropoxide () on structure of copolymer of asymmetric monomer ,-lactide () with symmetric comonomer trimethylene carbonate () was studied using polarimetry, dilatometry, Size Exclusion Chromatography (SEC), and Carbon Nuclear Magnetic Resonance (C NMR). When the -enantiomer of was used the distribution in copolymer chains at the beginning of polymerization is statistical, with alternacy tendency, changing next through a gradient region to homoblocks of . However, when - was used, the product formed was a gradient oligoblock one, with blocks prevailing at the beginning, changing to blocks dominating at the end part of chains.

Chain length distributions in linear polyaddition proceeding in nano-scale small volumes without mass transfer.

Computer simulations (Monte Carlo and numerical integration of differential equations) and theoretical analysis show that the statistical nature of polyaddition, both irreversible and reversible one, affects the way the macromolecules of different lengths are distributed among the small volume nano-reactors (droplets in this study) at any reaction time. The corresponding droplet distributions in respect to the number of reacting chains as well as the chain length distributions depend, for the given reaction time, on rate constants of polyaddition k and depolymerization k (reversible process), and the initial conditions: monomer concentration and the number of its molecules in a droplet. As a model reaction, a simple polyaddition process (M)+(M)⟶⟵(M), (M)+(M)⟶⟵(M) was chosen, enabling to observe both kinetic and thermodynamic (apparent equilibrium constant) effects of a small number of reactant molecules in a droplet.

Statistical effects related to low numbers of reacting molecules analyzed for a reversible association reaction A + B = C in ideally dispersed systems: An apparent violation of the law of mass action.

Theoretical analysis and computer simulations (Monte Carlo and numerical integration of differential equations) show that the statistical effect of a small number of reacting molecules depends on a way the molecules are distributed among the small volume nano-reactors (droplets in this study). A simple reversible association A + B = C was chosen as a model reaction, enabling to observe both thermodynamic (apparent equilibrium constant) and kinetic effects of a small number of reactant molecules. When substrates are distributed uniformly among droplets, all containing the same equal number of substrate molecules, the apparent equilibrium constant of the association is higher than the chemical one (observed in a macroscopic-large volume system).

Problems in treating bedsores in patients with significantly limited motor activity.

Bedsores are a treatment problem often encountered in patients with spinal injuries and other bedridden patients. It may occur in patients who do not receive proper nursing care. Failure to observe nursing standards may result in neglect, potentially leading to the death of the patient.