Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

Significant advances in biomaterials, stem cell biology, and microscale technologies have enabled the fabrication of biologically relevant tissues and organs. Such tissues and organs, referred to as organ-on-a-chip (OOC) platforms, have emerged as a powerful tool in tissue analysis and disease modeling for biological and pharmacological applications. A variety of biomaterials are used in tissue fabrication providing multiple biological, structural, and mechanical cues in the regulation of cell behavior and tissue morphogenesis. Cells derived from humans enable the fabrication of personalized OOC platforms. Microscale technologies are specifically helpful in providing physiological microenvironments for tissues and organs. In this review, biomaterials, cells, and microscale technologies are described as essential components to construct OOC platforms. The latest developments in OOC platforms (e.g., liver, skeletal muscle, cardiac, cancer, lung, skin, bone, and brain) are then discussed as functional tools in simulating human physiology and metabolism. Future perspectives and major challenges in the development of OOC platforms toward accelerating clinical studies of drug discovery are finally highlighted.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adhm.201800734

Organ-On-A-Chip Platforms: A Convergence of Advanced Materials, Cells, and Microscale Technologies.

Silver nanoparticles (Ag-NPs) readily transform in the environment, which modifies their properties and alters their transport, fate, and toxicity. It is essential to consider such transformations when assessing the potential environmental impact of Ag-NPs. This review discusses the major transformation processes of Ag-NPs in various aqueous environments, particularly transformations of the metallic Ag cores caused by reactions with (in)organic ligands, and the effects of such transformations on physical and chemical stability and toxicity. Thermodynamic arguments are used to predict what forms of oxidized silver will predominate in various environmental scenarios. Silver binds strongly to sulfur (both organic and inorganic) in natural systems (fresh and sea waters) as well as in wastewater treatment plants, where most Ag-NPs are expected to be concentrated and then released. Sulfidation of Ag-NPs results in a significant decrease in their toxicity due to the lower solubility of silver sulfide, potentiall...

Environmental Transformations of Silver Nanoparticles: Impact on Stability and Toxicity

Recent advances in new oxidizers for solid rocket propulsion

Enhanced thermal decomposition properties of ammonium perchlorate through addition of 3DOM core-shell Fe2O3/Co3O4 composite

Graphite oxide (GO) is receiving increased attention due to its special surface properties and layered structure for the synthesis of GO containing nanocomposites. It is possible that integration of GO sheets and iron oxide nanoparticles may result in enhanced properties and enlarge the application range. Herein, we report the effect of Fe2O3–GO nanocomposite as a new class of catalyst for the decomposition of ammonium perchlorate (AP), a rocket propellant oxidizer, and study the effect of Fe2O3 : GO ratio on the catalytic activity. The material was characterized by X-ray diffraction and Raman spectroscopy and the formation of Fe2O3 and GO were confirmed. FESEM analysis showed that the Fe2O3 nanoparticles are highly dispersed between and on the graphene layers. With the addition of 3% of the composite with 1 : 1 Fe2O3–GO ratio, the decomposition temperature of AP was reduced by 45 °C, showing a high catalytic activity for the new composite. The high catalytic activity of the in situ synthesized Fe2O3–GO composite may be attributed to the uniform distribution of iron oxide nanoparticles which in turn provide a number of active sites on the surface due to the presence of GO.

Graphite oxide–iron oxide nanocomposites as a new class of catalyst for the thermal decomposition of ammonium perchlorate

Copper oxide alumina composite via template assisted sol–gel method for ammonium perchlorate decomposition

Functionalized white graphene – Copper oxide nanocomposite: Synthesis, characterization and application as catalyst for thermal decomposition of ammonium perchlorate

Fe2O3 is a well-known catalyst for thermal decomposition of ammonium perchlorate (AP). Amorphous Fe2O3 nanoflakes were biosynthesised by a novel sol–gel method using Aloe vera leaf extract, and its catalytic effect on thermal decomposition of AP was investigated. The precursor ferric nitrate–Aloe vera gel was calcined at three different temperatures. The oxides were characterised by Fourier-transform infrared spectroscopy, X-ray powder diffraction, atomic force microscopy, field emission scanning electron microscopy and transmission electron microscopy. Microscopy analyses revealed that Fe2O3-250 consists of a porous structure as aggregates of many nanoflakes of ~ 2 nm diameter. The catalytic activity of the synthesised products on thermal decomposition of AP was evaluated using thermogravimetry–differential scanning calorimetry. The presence of 2.0% of mesoporous Fe2O3-250 catalyst (surface area of 208 m2 g−1) enhanced the rate of high-temperature decomposition of AP by decreasing the peak decomposition temperature from 367 to 337 °C. Average activation energy of thermal decomposition of AP was calculated using Flynn–Wall–Ozawa method reduced from 145 to 128 kJ mol−1 in the presence of the catalyst. The high surface area of mesoporous Fe2O3-250 originated from its amorphous nature makes it a potential catalyst for thermal decomposition of AP.

Rajeev Raghavan

Papers

Graphite oxide–iron oxide nanocomposites as a new class of catalyst for the thermal decomposition of ammonium perchlorate

Copper oxide alumina composite via template assisted sol–gel method for ammonium perchlorate decomposition

Functionalized white graphene – Copper oxide nanocomposite: Synthesis, characterization and application as catalyst for thermal decomposition of ammonium perchlorate

Aloe vera leaf extract-assisted facile green synthesis of amorphous Fe 2 O 3 for catalytic thermal decomposition of ammonium perchlorate

Decomposition of ammonium perchlorate: Exploring catalytic activity of nanocomposites based on nano Cu/Cu2O dispersed on graphitic carbon nitride