Resolution-Adapted All-Atomic and Coarse-Grained Model for Biomolecular Simulations

We develop here an adaptive multiresolution method for the simulation of complex heterogeneous systems such as the protein molecules. The target molecular system is described with the atomistic structure while maintaining concurrently a mapping to the coarse-grained models. The theoretical model, or force field, used to describe the interactions between two sites is automatically adjusted in the simulation processes according to the interaction distance/strength. Therefore, all-atomic, coarse-grained, or mixed all-atomic and coarse-grained models would be used together to describe the interactions between a group of atoms and its surroundings. Because the choice of theory is made on the force field level while the sampling is always carried out in the atomic space, the new adaptive method preserves naturally the atomic structure and thermodynamic properties of the entire system throughout the simulation processes. The new method will be very useful in many biomolecular simulations where atomistic details are critically needed

Pitfall in Quantum Mechanical/Molecular Mechanical Molecular Dynamics Simulation of Small Solutes in Solution

Developments in computing hardware and algorithms have made direct molecular dynamics simulation with the combined quantum mechanical/molecular mechanical methods affordable for small solute molecules in solution, in which much improved accuracy can be obtained via the quantum mechanical treatment of the solute molecule and even sometimes water molecules in the first solvation shell. However, unlike the conventional molecular mechanical simulations of large molecules, e.g., proteins, in solutions, special care must be taken in the technical details of the simulation, including the thermostat of the solute/solvent system, so that the conformational space of the solute molecules can be properly sampled. We show here that the common setup for classical molecular mechanical molecular dynamics simulations, such as the Berendsen or single Nose–Hoover thermostat, and/or rigid water models could lead to pathological sampling of the solutes’ conformation. In the extreme example of a methanol molecule in aqueous solution, improper and sluggish setups could generate two peaks in the distribution of the O–H bond length. We discuss the factors responsible for this somewhat unexpected result and evoke a simple and ancient technical fix-up to resolve this problem

Palladacycle-Catalyzed Deacetonative Sonogashira Coupling of Aryl Propargyl Alcohols with Aryl Chlorides

An efficient and general protocol for the deacetonative Sonogashira coupling of aryl propargyl alcohols with aryl chlorides is described. The reaction proceeded smoothly with the catalyst system of palladacycle/Xphos. This result represents the first successful deacetonative Sonogashira version for electron-poor, electron-neutral, and even inactive sterically hindered electron-rich aryl chlorides

Supplementary document for Terahertz 3-D fast line-scanning imaging enabled by 3-D printed devices - 6803521.pdf

Some simulation results and photo

Computing p<i>K</i>_a Values with a Mixing Hamiltonian Quantum Mechanical/Molecular Mechanical Approach

Accurate computation of the p<i>K</i>_a value of a compound in solution is important but challenging. Here, a new mixing quantum mechanical/molecular mechanical (QM/MM) Hamiltonian method is developed to simulate the free-energy change associated with the protonation/deprotonation processes in solution. The mixing Hamiltonian method is designed for efficient quantum mechanical free-energy simulations by alchemically varying the nuclear potential, i.e., the nuclear charge of the transforming nucleus. In p<i>K</i>_a calculation, the charge on the proton is varied in fraction between 0 and 1, corresponding to the fully deprotonated and protonated states, respectively. Inspired by the mixing potential QM/MM free energy simulation method developed previously [H. Hu and W. T. Yang, <i>J. Chem. Phys.</i> <b>2005</b>, <i>123</i>, 041102], this method succeeds many advantages of a large class of λ-coupled free-energy simulation methods and the linear combination of atomic potential approach. Theory and technique details of this method, along with the calculation results of the p<i>K</i>_a of methanol and methanethiol molecules in aqueous solution, are reported. The results show satisfactory agreement with the experimental data

Results from generalized linear model analysis (Schizophrenia).

<p>Results from generalized linear model analysis (Schizophrenia).</p

PGMA-Based Cationic Nanoparticles with Polyhydric Iodine Units for Advanced Gene Vectors

It is crucial for successful gene delivery to develop safe, effective, and multifunctional polycations. Iodine-based small molecules are widely used as contrast agents for CT imaging. Herein, a series of star-like poly­(glycidyl methacrylate) (PGMA)-based cationic vectors (II-PGEA/II) with abundant flanking polyhydric iodine units are prepared for multifunctional gene delivery systems. The proposed II-PGEA/II star vector is composed of one iohexol intermediate (II) core and five ethanolamine (EA) and II-difunctionalized PGMA arms. The amphipathic II-PGEA/II vectors readily self-assemble into well-defined cationic nanoparticles, where massive hydroxyl groups can establish a hydration shell to stabilize the nanoparticles. The II introduction improves cell viabilities of polycations. Moreover, by controlling the suitable amount of introduced II units, the resultant II-PGEA/II nanoparticles can produce fairly good transfection performances in different cell lines. Particularly, the II-PGEA/II nanoparticles induce much better in vitro CT imaging abilities in tumor cells than iohexol (one commonly used commercial CT contrast agent). The present design of amphipathic PGMA-based nanoparticles with CT contrast agents would provide useful information for the development of new multifunctional gene delivery systems

Characteristics of literature synthesis.

<p>Characteristics of literature synthesis.</p

Selective Synthesis of Multisubstituted Olefins Utilizing <i>gem</i>- and <i>vic</i>-Diborylated Vinylsilanes Prepared by Silylborylation of an Alkynylboronate and Diborylation of Alkynylsilanes

The synthesis of a series of <i>gem</i>- and <i>vic</i>-diborylated vinylsilanes was accomplished via highly selective transition-metal-catalyzed <i>syn</i>-dimetalation to the alkynylmetal species. This protocol served as a general synthetic method toward regio- and stereodefined multisubstituted olefins. The key steps are the diastereoselective Suzuki–Miyaura cross-coupling reactions of <i>gem</i>- and <i>vic</i>-diborylated vinylsilanes, in which the two boron groups showed discrete reactivities to afford diverse precursors of multisubstituted olefins

Raw cost and meta-analysis of direct medical costs.^†

<p>Raw cost and meta-analysis of direct medical costs.<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147169#t005fn002" target="_blank">^†</a></p