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Algae Architects.

Sponge Gives Up Nano Secrets.

Biomimicry for Bones.

How do People and Researchers Look to Chinese Herbal Medicine?

Agilent 1200 Infinity Series.

Naturally derived biopolymers have been widely used for biomedical applications such as drug carriers, wound dressings, and tissue engineering scaffolds. Chitosan is a typical polysaccharide of great interest due to its biocompatibility and film-formability. Chitosan membranes with controllable porous structures also have significant potential in membrane chromatography. Thus, the processing of membranes with porous nanoscale structures is of great importance, but it is also challenging and this has limited the application of these membranes to date. In this study, with the aid of a carefully selected surfactant, polyethyleneglycol stearate-40, chitosan membranes with a well controlled nanoscale structure were successfully prepared. Additional control over the membrane structure was obtained by exposing the suspension to high intensity, low frequency ultrasound. It was found that the concentration of chitosan/surfactant ratio and the ultrasound exposure conditions affect the structural features of the membranes. The stability of nanopores in the membrane was improved by intensive ultrasonication. Furthermore, the stability of the blended suspensions and the intermolecular interactions between chitosan and the surfactant were investigated using scanning electron microscope and Fourier transform infrared spectroscopy (FTIR) analysis, respectively. Hydrogen bonds and possible reaction sites for molecular interactions in the two polymers were also confirmed by FTIR analysis.

We have investigated the crystal structure, the microstructural and morphological characteristics, as well as the magnetic properties of Co nanoparticles (NPs) synthesized by a hydrothermal method. A series of samples has been elaborated for different concentrations of sodium hydroxide. The analysis of X-ray diffraction patterns, using two different wavelengths, has evidenced the coexistence of both $\alpha$-Co and $\beta$-Co phases in the samples. The lattice parameter for both phases is in good agreement with those values expected for their bulk Co counterparts; the grain sizes of NPs were found to be dependent on the NaOH concentration. The scanning electron microscope micrographs show that Co NPs are agglomerated forming micrometer-sized entities whose shape evolves, indicating that the synthesis process affects the morphology of the powdered samples. Magnetic measurements indicate that the coercivity is slightly larger, $H_C>200$ Oe, for Co NPs with dendritic-like shape, probably due to an increase in the magnetocrystalline anisotropy.

Magnetometry and atomic force microscopy (AFM) were used to study the magnetic and structural properties of the R–Fe–B-type (R = Y, Nd, Gd, Ho) alloys. The alloys were synthesized by means of induction melting. The nanocrystalline state of the R–Fe–B-type alloys was reached, mainly, by melt spinning (MS). A multistage treatment of R–Fe–B-type alloys, which included severe plastic deformation of melt-quenched ribbons and subsequent heat treatment, was also used. The surface morphology of samples was studied in detail to interpret the observed magnetic hysteresis loops of the samples. It was found that the type of rare earth ion and treatment methods had the most important influence on the microstructure and magnetic properties.

The structural, electronic, magnetic, and optical properties of Au, Cu, Cr, Mn, Co, Ni, and Fe atoms doped 13-atom silver clusters were investigated by the density functional theory (DFT) in the theoretical frame of the generalized gradient approximation (GGA) exchange-collection function. The results show that all the ground state structures of Au, Cu, Cr, Mn, Co, Ni, and Fe atoms doped 13-atom silver clusters are icosahedral, respectively. The Au atom doped on the surface of Ag${}_{13}$ cluster is stable, while other atoms doped in the center of Ag${}_{13}$ cluster are stable. The electronic stability order from high to small is Ag${}_{12}$Cr₁, Ag${}_{12}$Cu₁, Ag${}_{12}$Co₁, Ag${}_{12}$Fe₁, Ag${}_{12}$Au₁, Ag${}_{12}$Mn₁, Ag${}_{12}$Ni₁. Their magnetic moments are not only related to the doping atom but also the doping location of the atom. The magnetic moments of the Cu, Au, Mn, Co, Ni, Fe, and Cr atoms doped in the Ag${}_{13}$ cluster are 5.0, 3.0, 1.0, 3.0, 4.0, 2.0, and 0.0${\mu }_B$, respectively. Compared with the optical absorption spectrum of the Ag${}_{13}$ cluster, the Au, Cr, and Mn atoms doped the Ag${}_{13}$ cluster leading to blue shift, and the Cu, Co, Ni, and Fe atoms doped the Ag${}_{13}$ cluster resulting in red shift. These studies provide a theoretical basis on applications for clusters in electronic, magnetic, and optical devices.

Cellulose with at least one of its dimensions less than or equal to 100 nm is termed as nanocellulose. It is a unique and promising natural material extracted from native cellulose and produced by certain microbial cells and cell-free systems. Nanocellulose has received immense consideration in last couple of decades owing to its abundance, renewability, remarkable physical properties, special surface chemistry, and excellent biological features (biocompatibility, biodegradability, and non-toxicity). Taking advantage of the structure and properties of nanocellulose, the current science of biomaterials aims at developing new and formerly non-existing materials with novel and multifunctional properties, in an attempt to meet current requirements in different fields such as biomedicine, the environment, energy, pharmaceutics, agriculture, food, etc. This chapter provides an overview of different synthesis methods of nanocellulose: mechanical approaches by applying high-pressure, grinding, crushing, sonication, and milling; chemical synthesis involving alkaline, acidic, oxidation, and enzymatic treatment; as well as by using bacteria and cell-free systems. It further discusses different morphological forms of nanocellulose including cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), bacterial nanocellulose (BNC), and cellulose produced by cell-free systems, in terms of their features such as chemical structure, macrostructural morphology, physico-mechanical properties, thermal and biological properties, rheology, optical behavior, and their interrelationships and applications.