Phonon Structure, Infra-Red and Raman Spectra of LiMnO by First-Principles Calculations.

The layer-structured monoclinic LiMnO is a key material, mainly due to its role in Li-ion batteries and as a precursor for adsorbent used in lithium recovery from aqueous solutions. In the present work, we used first-principles calculations based on density functional theory (DFT) to study the crystal structure, optical phonon frequencies, infra-red (IR), and Raman active modes and compared the results with experimental data. First, LiMnO powder was synthesized by the hydrothermal method and successively characterized by XRD, TEM, FTIR, and Raman spectroscopy.

The Infiltration of Silver Nanoparticles into Porous Silicon for Improving the Performance of Photonic Devices.

Hybrid nanostructures have a great potential to improve the overall properties of photonic devices. In the present study, silver nanoparticles (AgNPs) were infiltrated into nanostructured porous silicon (PSi) layers, aiming at enhancing the optoelectronic performance of Si-based devices. More specifically, Schottky diodes with three different configurations were fabricated, using Al/Si/Au as the basic structure.

Hydrothermal control of the lithium-rich LiMnO phase in lithium manganese oxide nanocomposites and their application as precursors for lithium adsorbents.

Lithium manganese oxides (LMOs) are key materials due to their role in Li-ion batteries and lithium recovery from aqueous lithium resources. In the present work, we investigated the effect of the crystallization temperature on the formation by hydrothermal synthesis of LMO nanocomposites with high Li/Mn ratios. It is demonstrated that LMOs with a high Li/Mn ratio can be formed by systematically favoring the lithium-rich layered monoclinic phase (LiMnO) in a mixture of monoclinic and spinel crystalline phases.

Hybrid Nanostructured Porous Silicon-Silver Layers for Wideband Optical Absorption.

As subwavelength nanostructures are receiving increasing attention for photonic and plasmonic applications, we grew nanostructured porous silicon (n-PS) and hybrid n-PS/Ag layers onto silicon substrates and measured their reflection and absorption characteristics as functions of the wavelength, angle of incidence, and polarization state of incident light. The experimental results show that the absorption characteristics of the hybrid n-PS/Ag layer can be controlled by selecting the appropriate combination of its thickness and porosity, together with the density of infiltrant silver nanoparticles. The observed wideband optical absorption characteristics of the hybrid n-PS/Ag layers might be useful in light-harvesting devices and photodetectors, since the overall efficiency will be increased as a result of increased field-of-view for both s- and p-polarization states of incident light.

Nanostructured porous silicon: the winding road from photonics to cell scaffolds - a review.

For over 20 years, nanostructured porous silicon (nanoPS) has found a vast number of applications in the broad fields of photonics and optoelectronics, triggered by the discovery of its photoluminescent behavior in 1990. Besides, its biocompatibility, biodegradability, and bioresorbability make porous silicon (PSi) an appealing biomaterial. These properties are largely a consequence of its particular susceptibility to oxidation, leading to the formation of silicon oxide, which is readily dissolved by body fluids.

Nanostructured copper/porous silicon hybrid systems as efficient sound-emitting devices.

In the present work, the photo-acoustic emission from nanostructured copper/porous silicon hybrid systems was studied. Copper nanoparticles were grown by photo-assisted electroless deposition on crystalline silicon and nanostructured porous silicon (nanoPS). Both the optical and photo-acoustic responses from these systems were determined.

Bioreplicated visual features of nanofabricated buprestid beetle decoys evoke stereotypical male mating flights.

Recent advances in nanoscale bioreplication processes present the potential for novel basic and applied research into organismal behavioral processes. Insect behavior potentially could be affected by physical features existing at the nanoscale level. We used nano-bioreplicated visual decoys of female emerald ash borer beetles (Agrilus planipennis) to evoke stereotypical mate-finding behavior, whereby males fly to and alight on the decoys as they would on real females.

Nanostructured porous silicon-mediated drug delivery.

Introduction: The particular properties of nanostructured porous silicon (nanoPS) make it an attractive material for controlled and localized release of therapeutics within the body, aiming at increased efficacy and reduced risks of potential side effects. Since this is a rapidly evolving field as a consequence of the number of research groups involved, a critical review of the state of the art is necessary.

Areas Covered: In this work, the most promising and successful applications of nanoPS in the field of drug delivery are reviewed and discussed.

Laser fabrication of porous silicon-based platforms for cell culturing.

In this study, we explore the selective culturing of human mesenchymal stem cells (hMSCs) on Si-based diffractive platforms. We demonstrate a single-step and flexible method for producing platforms on nanostructured porous silicon (nanoPS) based on the use of single pulses of an excimer laser to expose phase masks. The resulting patterns are typically 1D patterns formed by fringes or 2D patterns formed by circles.

Adhesion and proliferation of human mesenchymal stem cells from dental pulp on porous silicon scaffolds.

In regenerative medicine, stem-cell-based therapy often requires a scaffold to deliver cells and/or growth factors to the injured site. Porous silicon (pSi) is a promising biomaterial for tissue engineering as it is both nontoxic and bioresorbable. Moreover, surface modification can offer control over the degradation rate of pSi and can also promote cell adhesion.

Optimized development of sebaceous fingermarks on nonporous substrates with conformal columnar thin films.

A form of physical vapor deposition, called the conformal-evaporated-film-by-rotation (CEFR) method, was optimized for the conformal deposition of columnar thin films (CTFs) on sebaceous fingermarks. Relying on the surface topology of the fingermark, the CTF development technique is different from traditional development techniques. After the optimization of the development conditions, the CTF development technique was found to be superior to traditional development methods on several nonporous substrates: the smooth side of Scotch(®) Multitask, Gorilla(®) , and Scotch(®) Duct tapes; clear and black soft plastics; stained and sealed walnut and cherry woods; partial bloody fingermarks on stainless steel; and discharged cartridge casings.

Laser fabrication of porous silicon-based platforms for cell culturing.

In this study, we explore the selective culturing of human mesenchymal stem cells (hMSCs) on Si-based diffractive platforms. We demonstrate a single-step and flexible method for producing platforms on nanostructured porous silicon (nanoPS) based on the use of single pulses of an excimer laser to expose phase masks. The resulting patterns are typically 1D patterns formed by fringes or 2D patterns formed by circles.

Characterization of hybrid cobalt-porous silicon systems: protective effect of the Matrix in the metal oxidation.

In the present work, the characterization of cobalt-porous silicon (Co-PSi) hybrid systems is performed by a combination of magnetic, spectroscopic, and structural techniques. The Co-PSi structures are composed by a columnar matrix of PSi with Co nanoparticles embedded inside, as determined by Transmission Electron Microscopy (TEM). The oxidation state, crystalline structure, and magnetic behavior are determined by X-Ray Absorption Spectroscopy (XAS) and Alternating Gradient Field Magnetometry (AGFM).

Silicon-based photonic crystals fabricated using proton beam writing combined with electrochemical etching method.

A method for fabrication of three-dimensional (3D) silicon nanostructures based on selective formation of porous silicon using ion beam irradiation of bulk p-type silicon followed by electrochemical etching is shown. It opens a route towards the fabrication of two-dimensional (2D) and 3D silicon-based photonic crystals with high flexibility and industrial compatibility. In this work, we present the fabrication of 2D photonic lattice and photonic slab structures and propose a process for the fabrication of 3D woodpile photonic crystals based on this approach.

Nanostructured porous silicon micropatterns as a tool for substrate-conditioned cell research.

The localized irradiation of Si allows a precise patterning at the microscale of nanostructured materials such as porous silicon (PS). PS patterns with precisely defined geometries can be fabricated using ion stopping masks. The nanoscale textured micropatterns were used to explore their influence as microenvironments for human mesenchymal stem cells (hMSCs).

Aging of porous silicon in physiological conditions: cell adhesion modes on scaled 1D micropatterns.

The surface properties of porous silicon (PSi) evolve rapidly in phosphate-buffered saline. X-ray photoelectron spectra indicate the formation of a Si-OH and C-O enriched surface, which becomes increasingly hydrophilic with aging time. Multiscale stripe micropatterns of Si and PSi have been fabricated by means of a high-energy ion-beam irradiation process.

Engineering of silicon surfaces at the micro- and nanoscales for cell adhesion and migration control.

The engineering of surface patterns is a powerful tool for analyzing cellular communication factors involved in the processes of adhesion, migration, and expansion, which can have a notable impact on therapeutic applications including tissue engineering. In this regard, the main objective of this research was to fabricate patterned and textured surfaces at micron- and nanoscale levels, respectively, with very different chemical and topographic characteristics to control cell-substrate interactions. For this task, one-dimensional (1-D) and two-dimensional (2-D) patterns combining silicon and nanostructured porous silicon were engineered by ion beam irradiation and subsequent electrochemical etch.

High surface water interaction in superhydrophobic nanostructured silicon surfaces: convergence between nanoscopic and macroscopic scale phenomena.

In the present work, we investigate wetting phenomena on freshly prepared nanostructured porous silicon (nPS) with tunable properties. Surface roughness and porosity of nPS can be tailored by controlling fabrication current density in the range 40-120 mA/cm(2). The length scale of the characteristic surface structures that compose nPS allows the application of thermodynamic wettability approaches.

Gold Nanostructures for Surface-Enhanced Raman Spectroscopy, Prepared by Electrodeposition in Porous Silicon.

Electrodeposition of gold into porous silicon was investigated. In the present study, porous silicon with ~100 nm in pore diameter, so-called medium-sized pores, was used as template electrode for gold electrodeposition. The growth behavior of gold deposits was studied by scanning electron microscope observation of the gold deposited porous silicon.

Hybrid luminescent/magnetic nanostructured porous silicon particles for biomedical applications.

This work describes a novel process for the fabrication of hybrid nanostructured particles showing intense tunable photoluminescence and a simultaneous ferromagnetic behavior. The fabrication process involves the synthesis of nanostructured porous silicon (NPSi) by chemical anodization of crystalline silicon and subsequent in pore growth of Co nanoparticles by electrochemically-assisted infiltration. Final particles are obtained by subsequent sonication of the Co-infiltrated NPSi layers and conjugation with poly(ethylene glycol) aiming at enhancing their hydrophilic character.

Solid-state acquisition of fingermark topology using dense columnar thin films.

Various vacuum techniques are employed to develop fingermarks on evidentiary items. In this work, a vacuum was used to deposit columnar thin films (CTFs) on untreated, cyanoacrylate-fumed or dusted fingermarks on a limited selection of nonporous surfaces (microscope glass slides and evidence tape). CTF deposition was not attempted on fingermarks deposited on porous surfaces.

Mass fabrication technique for polymeric replicas of arrays of insect corneas.

Motivated to develop a technique for producing many high-fidelity replicas for the sacrifice of a single biotemplate, we combined a modified version of the conformal-evaporated-film-by-rotation technique and electroforming to produce a master negative made of nickel from a composite biotemplate comprising several corneas of common blowflies. This master negative can function as either a mold for casting multiple replicas or a die for stamping multiple replicas. An approximately 250 nm thick nickel film was thermally deposited on an array of blowfly corneas to capture the surface features with high fidelity and then a roughly 60 microm thick structural layer of nickel was electroformed onto the thin layer to give it the structural integrity needed for casting or stamping.

Fabrication of free-standing replicas of fragile, laminar, chitinous biotemplates.

The conformal-evaporated-film-by-rotation technique, followed by the dissolution of chitin in an aqueous solution of orthophosphoric acid, can be used to fabricate free-standing replicas of fragile, laminar, chitinous biotemplates. This novel approach was demonstrated using butterfly wings as biotemplates and GeSeSb chalcogenide glass for replicas.

Optical biosensors based on semiconductor nanostructures.

The increasing availability of semiconductor-based nanostructures with novel and unique properties has sparked widespread interest in their use in the field of biosensing. The precise control over the size, shape and composition of these nanostructures leads to the accurate control of their physico-chemical properties and overall behavior. Furthermore, modifications can be made to the nanostructures to better suit their integration with biological systems, leading to such interesting properties as enhanced aqueous solubility, biocompatibility or bio-recognition.