1.55-mum and infrared-band photoresponsivity of a Schottky barrier porous silicon photodetector

We have investigated the spectral responsivity of porous silicon Schottky barrier photodetectors in the wavelength range 0.4-1.7 mum . The photodetectors show strong photoresponsivity in both the visible and the infrared bands, especially at 1.55 mum . The photocurrent can reach 1.8 mA at a reverse bias of 6 V under illumination by a 1.55-mum , 10-mW laser diode. The corresponding quantum efficiency is 14.4%.     

Surface Functionalization of Fe3O4 Magnetic Nanoparticles via RAFT‐Mediated Graft Polymerization

Summary: Surface functionalization of Fe₃O₄ magnetic nanoparticles (MNP) via living radical graft polymerization with styrene and acrylic acid (AAc) in the reversible addition‐fragmentation chain transfer (RAFT)‐mediated process was reported. Peroxides and hydroperoxides generated on the surface of Fe₃O₄ nanoparticles via ozone pretreatment facilitated the thermally initiated graft polymerization in the RAFT‐mediated process. A comparison of the MNP before and after the RAFT‐mediated process was carried out using transmission electron microscopy (TEM) analysis, Fourier transform infrared (FTIR), and X‐ray photoelectron spectroscopy (XPS). Gel permeation chromatography (GPC) was used to determine the molecular weight of the free homopolymer in the reaction mixture. Well‐defined polymer chains were grown from the MNP surfaces to yield particles with a Fe₃O₄ core and a polymer outer layer. The resulting core–shell Fe₃O₄‐g‐polystyrene and Fe₃O₄‐g‐poly(acrylic acid) (PAAc) nanoparticles formed stable dispersions in the organic solvents for polystyrene (PS) and PAAc, respectively.

Schematic illustration of thermally induced graft polymerization of styrene and AAc with the ozone‐treated Fe₃O₄ MNP.     

Polypyrrole Nanospheres with Magnetic and Cell‐Targeting Capabilities

The preparation of polypyrrole/Fe₃O₄ nanospheres by a facile mini‐emulsion polymerization method is investigated using poly(ethylene glycol), poly(ethylene oxide), poly(vinyl alcohol), and hyaluronic acid as surfactants. Hyaluronic acid is deemed the most suitable surfactant since it results in well‐dispersed nanospheres of 80–100 nm, and offers the advantages of biocompatibility, cell adhesive property, and the availability of functional groups for attachment of other molecules. These polypyrrole/Fe₃O₄ nanospheres are magnetic and can be further functionalized with a cancer antibody, herceptin. Our results show that this combination of hyaluronic acid and herceptin results in high specific uptake of the nanospheres by cancer cells.

     

Recent Trends in Green and Sustainable Chemistry & Waste Valorisation: Rethinking Plastics in a circular economy

The review presents the recent trends in green and sustainable chemistry, as well as waste valorization and their applicability to understand and realize the concept of a circular economy. It also provides a comprehensive global perspective of the linear plastics economy and makes the case for its transformation into a circular plastics economy. Furthermore, bioconversion in a food waste biorefinery to produce fructose as an example of a high value-added product is given as a case study to demonstrate the feasibility of a circular economy.     

Aqueous Two-Phase Flotation for the Recovery of Biomolecules

Aqueous two-phase flotation (ATPF), a novel technique which integrates the principles of aqueous two-phase systems and mass transfer mode of solvent sublation, has been successfully applied for the separation and purification of biological materials in the field of biotechnology. From the studies done so far, ATPF has demonstrated as an effective, economical and environment-friendly technique for separation of labile biomolecules from their crude aqueous extracts of natural plants or fermentation broths, under mild separation condition. In this article, the basic principles, experimental apparatus set up, key design variables of ATPF, ATPF applications and a comparative study between ATPF and other conventional methods are discussed. This review is intended to present a comprehensive summary on the research works carried out so far related to ATPF since its introduction in 2009 until present, which will be helpful for further research in ATPF.     

Brain site-specific proteome changes in aging-related dementia

This study is aimed at gaining insights into the brain site-specific proteomic senescence signature while comparing physiologically aged brains with aging-related dementia brains (for example, Alzheimer''s disease (AD)). Our study of proteomic differences within the hippocampus (Hp), parietal cortex (pCx) and cerebellum (Cb) could provide conceptual insights into the molecular mechanisms involved in aging-related neurodegeneration. Using an isobaric tag for relative and absolute quantitation (iTRAQ)-based two-dimensional liquid chromatography coupled with tandem mass spectrometry (2D-LC-MS/MS) brain site-specific proteomic strategy, we identified 950 proteins in the Hp, pCx and Cb of AD brains. Of these proteins, 31 were significantly altered. Most of the differentially regulated proteins are involved in molecular transport, nervous system development, synaptic plasticity and apoptosis. Particularly, proteins such as Gelsolin (GSN), Tenascin-R (TNR) and AHNAK could potentially act as novel biomarkers of aging-related neurodegeneration. Importantly, our Ingenuity Pathway Analysis (IPA)-based network analysis further revealed ubiquitin C (UBC) as a pivotal protein to interact with diverse AD-associated pathophysiological molecular factors and suggests the reduced ubiquitin proteasome degradation system (UPS) as one of the causative factors of AD.     

In Situ Synthesis and Nonvolatile Rewritable‐Memory Effect of Polyaniline‐Functionalized Graphene Oxide

A new polyaniline (PANI)‐functionalized graphene oxide (GO‐PANI) was prepared by using an in situ oxidative graft polymerization of aniline on the surface of GO. Its highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), ionization potential (IP), and electron affinity (EA) values experimentally estimated by the onset of the redox potentials were ?5.33, ?3.57, 5.59, and 3.83 eV, respectively. A bistable electrical‐switching effect was observed in electronic device with the GO‐PANI film sandwiched between the indium tin oxide (ITO) and Al electrodes. This device exhibited two accessible conductivity states, that is, the low‐conductivity (OFF) state and the high‐conductivity (ON) state, and can be switched to the ON state under a negative electrical sweep, and can also be reset to the initial OFF state by a reverse (positive) electrical sweep. The ON state is nonvolatile and can withstand a constant voltage stress of ?1 V for 3 h and 10⁸ read cycles at ?1 V under ambient conditions. The nonvolatile nature of the ON state and the ability to write, read, and erase the electrical states, fulfill the functionality of a rewritable memory. An ON/OFF current ratio of more than 10⁴ at ?1 V achieved in this memory device is high enough to promise a low misreading rate through the precise control of the ON and OFF states. The mechanism associated with the memory effects was elucidated from molecular simulation results.