There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Microwave assisted organic synthesis-a review

Dingcai Wu,*,† Fei Xu,† Bin Sun,† Ruowen Fu,† Hongkun He,‡ and Krzysztof Matyjaszewski*,‡ †Materials Science Institute, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, People's Republic of China ‡Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States

Design and Preparation of Porous Polymers

Introduction Cationic domino reactions Anionic domino reactions Radical domino reactions Pericyclic domino reactions Photochemically induced domino processes Transition metal catalysis Domino reactions initiated by oxidation or reduction Enzymes in domino reactions Multicomponent reactions Special techniques in domino reactions

Domino Reactions in Organic Synthesis

Currently, cancer is the second largest cause of death worldwide and has reached critical levels. In spite of all the efforts, common treatments including chemotherapy, photodynamic therapy, and photothermal therapy suffer from various problems which limit their efficiency and performance. For this reason, different strategies are being explored which improve the efficiency of these traditional therapeutic methods or treat the tumor cells directly. One such strategy utilizing the Fenton reaction has been investigated by many groups for the possible treatment of cancer cells. This approach is based on the knowledge that high levels of hydrogen peroxide exist within cancer cells and can be used to catalyze the Fenton reaction, leading to cancer-killing reactive oxygen species. Analysis of the current literature has shown that, due to the diverse morphologies, different sizes, various chemical properties, and the tunable structure of nanoparticles, nanotechnology offers the most promising method to facilitate the Fenton reaction with cancer therapy. This review aims to highlight the use of the Fenton reaction using different nanoparticles to improve traditional cancer therapies and the emerging Fenton-based therapy, highlighting the obstacles, challenges, and promising developments in each of these areas.

Cancer Treatment through Nanoparticle-Facilitated Fenton Reaction

A novel reduced iron metal-organic framework nanoparticle with cytotoxicity specific to cancer cells is presented. This nanoparticle was prepared via a hydrothermal method, reduced using hydroquinone, and finally conjugated with folic acid (namely, rMOF-FA). The synthesized nanoparticle shows the controlled release of iron in an acidic ex-vivo environment. Iron present on the rMOF-FA and released into solution can react with high levels of hydrogen peroxide found specifically in cancer cells to increase the hydroxyl radical concentration. The hydroxyl radicals oxidize proteins, lipids, and/or DNA within the biological system to decrease cell viability. In vitro experiments demonstrate that this novel nanoparticle is cytotoxic to cancer cells (HeLa) through generation of OH• inside the cells. At low concentrations of rMOF-FA, the cancer cell viability decreases dramatically, with no obvious reduction of normal cell (NIH-3T3) viability. The calculated half-maximum inhibitory concentration value (IC50) was 43 μg/mL for HeLa cells, which was significantly higher than 105 μg/mL for NIH-3T3. This work thus demonstrates a new type of agent for controlled hydroxyl radical generation using the Fenton reaction to kill the tumor cells.

MOF-Mediated Destruction of Cancer Using the Cell's Own Hydrogen Peroxide

Ultrathin metal-organic framework (MOF) nanosheets show great potential in various separation applications. In this study, MOF nanosheets are incorporated as a gutter layer in high-performance, flexible thin-film composite membranes (TFCMs) for CO2 separation. Ultrathin MOF nanosheets (∼3-4 nm) were prepared via a surfactant-assisted method and subsequently coated onto a flexible porous support by vacuum filtration. This produced an ultrathin (∼25 nm), extremely flat MOF layer, which serves as a highly permeable gutter with reduced gas resistance when compared with conventional polydimethylsiloxane gutter layers. Subsequent spin-coating of the ultrathin MOF gutter layer with a polymeric selective layer (Polyactive) afforded a TFCM exhibiting the best CO2 separation performance yet reported for a flexible composite membrane (CO2 permeance of ∼2100 GPU with a CO2/N2 ideal selectivity of ∼30). Several unique MOF nanosheets were examined as gutter layers, each differing with regard to structure and thickness (∼10 and ∼80 nm), with results indicating that flexibility in the ultrathin MOF layer is critical for optimized membrane performance. The inclusion of ultrathin MOF nanosheets into next-generation TFCMs has the potential for major improvements in gas separation performance over current composite membrane designs.

Ultrathin Metal-Organic Framework Nanosheets as a Gutter Layer for Flexible Composite Gas Separation Membranes

Star-microgels were prepared in a two-step process known as the arm first approach by Atom Transfer Radical Polymerization (ATRP) Living linear poly(methyl methacrylate)
				(PMMA), with molecular weight (Mn) of 10000 and 20000, was reacted with ethylene glycol dimethacrylate (EGDMA) as crosslinker and varying amounts of methyl methacrylate (MMA) as spacer, under ATRP conditions, to produce star-microgels with Mn ranging from 03 × 106 to 10 × 106 and number of arms, n(arms) from 11 to 74 As Mn of the arm was increased, a decrease in molecular weight and in the number of arms in the microgel was observed Star-microgels, with MMA spacer incorporated in the core, were found to have lower molecular weight and lower arm number The microgels were used as precursors to form honeycomb films The films were cast under conditions of high humidity which produces condensed water droplets which act as the template for a precipitating polymer This is the first report of the use of well defined star-microgels to cast highly ordered porous films It is shown that the pore diameters decrease with increasing number of PMMA arms and with increasing molecular weight of the star-microgel

From well defined star-microgels to highly ordered honeycomb films

Separately, Fenton and starvation cancer therapies have been recently reported as impressive methods for tumor destruction. Here, we introduce natural hemoglobin and glucose oxidase (GOx) for efficient cancer treatment following combined Fenton and starvation therapies. GOx and hemoglobin were encapsulated in zeolitic imidazolate frameworks 8 (ZIF-8) to fabricate a pH-sensitive MOF activated by tumor acidity. In the slightly acidic environment of cancer cells, GOx is released and it consumes d-glucose and molecular oxygen, nutrients essential for the survival of cancer cells, and produces gluconic acid and hydrogen peroxide, respectively. The produced gluconic acid increases the acidity of the tumor microenvironment leading to complete MOF destruction and enhances hemoglobin and GOx release. The Fe ions from the heme groups of hemoglobin also release in the presence of both endogenous and produced H2O2 and generate hydroxyl radicals. The produced OH˙ radical can rapidly oxidize the surrounding biomacromolecules in the biological system and treat the cancer cells. In vitro experiments demonstrate that this novel nanoparticle is cytotoxic to cancer cells HeLa and MCF-7, at very low concentrations (<2 μg mL-1). In addition, the selectivity index values are 5.52 and 11.04 for HeLa and MCF-7 cells, respectively, which are much higher than those of commercial drugs and those of similar studies reported by other research groups. This work thus demonstrates a novel pH-sensitive system containing hemoglobin and GOx for effective and selective cancer treatment using both radical generation and nutrient starvation.

Paul A. Gurr

Papers

Cancer Treatment through Nanoparticle-Facilitated Fenton Reaction

MOF-Mediated Destruction of Cancer Using the Cell's Own Hydrogen Peroxide

Ultrathin Metal-Organic Framework Nanosheets as a Gutter Layer for Flexible Composite Gas Separation Membranes

From well defined star-microgels to highly ordered honeycomb films

Combined Fenton and starvation therapies using hemoglobin and glucose oxidase