Does the Addition of Cellulosic Micro/nanofibrils Improve the Properties of Hydroxypropyl Methylcellulose Films?

Damages to ecosystems, due to the consumption of petroleum-based materials, can be mitigated with the use of biopolymers such as cellulose derivatives. The objective was to evaluate the influence of different proportions of cellulose micro/nanofibrils (MFC/NFC) on the properties of hydroxypropyl methyl cellulose (HPMC) films. Films were prepared using proportions of 0, 25, 50, 75 and 100% (w/w) of MFC/NFC of Pinus sp. in relation to HPMC. The physical, barrier, surface, optical, morphological and mechanical properties were evaluated. Data were analyzed with descriptive statistics, linear regression, principal component analysis and Pearson correlation. Solids content, basis weight and density values increased with higher MFC/NFC amount, while thickness and porosity were reduced. SEM images showed that films with more than 50% MFC/NFC had a more granular surface resulting in reduction of transparency from 80 to 65%. The water vapor penetration did not differ between films and the degradation in water was reduced from 40 to 5% as MFC/NFC was added. There were no differences for contact angle and wettability, but all films showed high resistance to fat penetration. Films with MFC/NFC contents between 75 and 100% showed higher values for tensile strength (50 to 65 MPa) and Young's modulus (6 to 10 MPa) and lower elongation at break (1 to 2%). The experimental results indicated that films with MFC/NFC contents above 50% have potential to be used as packaging material.

Plexciton Modes Guided by an Exciton Slab in a Columnar Thin Film

In this study, we reported plasmon-exciton coupling for excitation the surface plexciton in columnar thin film with a central exciton slab using the transfer matrix method in Kretschmann configuration. The optical absorption spectra for surface plasmon polariton, surface exciton and surface plexciton was investigated at different structural parameters in proposed structure. The characteristics of surface optical modes were analyzed and there was an anticrossing behavior between polariton branches of plexciton spectra. Localization of surface modes on interfaces and hybridization between plasmons and excitons at both interfaces of exciton slab were proved by the time-averaged Poynting vector. We found that the types of coupling regimes between plasmons and excitons from weak to strong could be achieved. We found a high Rabi splitting energy 840 meV corresponding to the time period 5 fs which includes to the fast energy transfer between surface plasmon polaritons and surface excitons.

The Efficacy of a Diode Laser on Titanium Implants for the Reduction of Microorganisms That Cause Periimplantitis

The paper presents the optimisation of a safe diode laser irradiation process applied to the surface of titanium implants in order to reduce microbial numbers in the treatment of inflammation classified as periimplantitis. The study comprised isolation and identification of microorganisms inhabiting surfaces of dental implants, crowns, teeth and saliva from patients with fully symptomatic periimplantitis. Microorganisms were detected by a culture-dependent method and identified with the use of MALDI-TOF mass spectrometry. The isolated microorganisms were inoculated on the surface of a new implant and then irradiated by a diode laser (wavelength of 810 ± 10 nm) in one, two or three repetitions and biocidal efficacy was assessed. To evaluate impact of laser irradiation on roughness, morphology and structure of the implant surface, optical profilometry, scanning electron microscopy and optical microscopy were used. Examination of the tested surfaces and saliva revealed the presence of Gram-positive and Gram-negative bacteria and one fungal species. In all patients, cultures from the endosseous part of the implant revealed the presence of the pathogenic and pyogenic bacterium Streptococcus constellatus. In 13 out of 20 samples laser-irradiated in duplicate and triplicate, all microorganisms were eliminated. The irradiation used did not cause any changes in the properties of the implant surface.

Investigation of the Phonon Spectra in CdSe/CdS Nanoplatelets by Raman Spectroscopy

We report the phonon spectra of core/shell CdSe/CdS nanoplatelets with different shell thicknesses studied using Raman scattering. The nanoplatelets are rectangular colloidal nanocrystals, with thicknesses of core and shell layers of a few nanometers. The Raman spectra show features corresponding to the dominating longitudinal optical (LO) and surface optical (SO) phonon modes of the CdSe core in CdS shell located in the frequency regions of 200-210 and 250-290 cm-1, respectively. As the shell thickness increases, the phonon modes reveal a frequency shift and a change in intensity. The frequency shift associated with a change in the stress state in the core and shell, as well as with confinement effects is discussed. The phonon mode intensities are determined by the thickness of the shell and the proximity to resonant Raman scattering conditions.

Fabrication of Three-Dimensional Multilayer Structures of Single-Walled Carbon Nanotubes Based on the Plasmonic Carbonization

We developed a complex three-dimensional (3D) multilayer deposition method for the fabrication of single-walled carbon nanotubes (SWCNTs) using vacuum filtration and plasmonic carbonization without lithography and etching processes. Using this fabrication method, SWCNTs can be stacked to form complex 3D structures that have a large surface area relative to the unit volume compared to the single-plane structure of conventional SWCNTs. We characterized 3D multilayer SWCNT patterns using a surface optical profiler, Raman spectroscopy, sheet resistance, scanning electron microscopy, and contact angle measurements. Additionally, these carbon nanotube (CNT) patterns showed excellent mechanical stability even after elastic bending tests more than 1000 times at a radius of 2 mm.

High-Efficiency, Wide Working Bandwidth Antenna Based on SOI Platform for Optical Phased Array

A novel structure of a subwavelength surface optical antenna for optical phased array is proposed in this paper. An asymmetric vertical grating structure is applied to achieve high emission efficiency (73% at 1550 nm). Optical antennas with large fabrication tolerances can also maintain a wide working bandwidth of 1 dB between 1350 and 1850 nm. The far-field scanning characteristics of 16-channel optical phased array are investigated in this study by employing the proposed antenna. The results show that the background suppression without considering side lobes caused by the antenna arrangement is −24.5 dB when the phase difference is 0 and when the scan range is as large as ±14.8° × 73.6°.