Nano-second laser sources for use in analytical spectroscopy.

The remit for the work described in this study was to characterize an aging Nd:YAG laser to explore what could be done to (i) extend its useful life of operation and (ii) to enhance its capabilities for spectroscopic applications. In the first instance, the operating parameters of the Nd:YAG laser for its fundamental output at 1064nm were measured, including pulse energy (as a function of the Q-switch delay time which influences the pulse energy), pulse width and transverse intensity beam profiles (using bum paper to evaluate the uniformity). It was found that the laser still operated well, although its maximum pulse energy was down on the specifications of the laser when it was new. In the second phase, 2nd and 3rd harmonic generation at 532nm and 355nm were implemented, using salvaged units from another laser system (non-linear crystal and harmonic separator units). Once again, the 2nd / 3rd harmonic output from the laser system was investigated. It was found that overall the laser operated to expectations, but that the beam quality for the harmonics was not very good (most likely due to surface damage of the non-linear doubling crystal). In the third phase, the 2nd harmonic output was prepared for pumping a tuneable dye laser. For this, a telescopic beam expansion unit was built. The dye laser could be operated successfully, and as for the Nd:YAG laser itself, its output parameters were recorded, including pulse energy, pulse width and spectral tuning range. In a final step, the Nd:YAG laser and the dye laser were successfully tested in spectroscopic applications, namely laser-induced breakdown spectroscopy (LIBS) and opto-galvanic spectroscopy (OGS)

Sustainable drug release from polycaprolactone coated chitin‑lignin gel fibrous scaffolds

Non-healing wounds have placed an enormous stress on both patients and healthcare systems worldwide. Severe complications induced by these wounds can lead to limb amputation or even death and urgently require more effective treatments. Electrospun scaffolds have great potential for improving wound healing treatments by providing controlled drug delivery. Previously, we developed fibrous scaffolds from complex carbohydrate polymers [i.e. chitin-lignin (CL) gels]. However, their application was limited by solubility and undesirable burst drug release. Here, a coaxial electrospinning is applied to encapsulate the CL gels with polycaprolactone (PCL). Presence of a PCL shell layer thus provides longer shelf-life for the CL gels in a wet environment and sustainable drug release. Antibiotics loaded into core–shell fibrous platform effectively inhibit both gram-positive and -negative bacteria without inducting observable cytotoxicity. Therefore, PCL coated CL fibrous gel platforms appear to be good candidates for controlled drug release based wound dressing applications

The Effect of Poly (Glycerol Sebacate) Incorporation within Hybrid Chitin–Lignin Sol–Gel Nanofibrous Scaffolds

Chitin and lignin primarily accumulate as bio-waste resulting from byproducts of crustacean crusts and plant biomass. Recently, their use has been proposed for diverse and unique bioengineering applications, amongst others. However, their weak mechanical properties need to be improved in order to facilitate their industrial utilization. In this paper, we fabricated hybrid fibers composed of a chitin–lignin (CL)-based sol–gel mixture and elastomeric poly (glycerol sebacate) (PGS) using a standard electrospinning approach. Obtained results showed that PGS could be coherently blended with the sol–gel mixture to form a nanofibrous scaffold exhibiting remarkable mechanical performance and improved antibacterial and antifungal activity. The developed hybrid fibers showed promising potential in advanced biomedical applications such as wound care products. Ultimately, recycling these sustainable biopolymers and other bio-wastes alike could propel a “greener” economy

Enhancement in the Performance of Dye Sensitized Solar Cells (DSSCs) by Incorporation of Reduced Graphene Oxide (RGO) and Carbon Nanotubes (CNTs) in ZnO Nanostructures

In this work, a fast, environment-friendly and economic route was used to prepare ZnO and their nanocomposites containing reduced graphene oxide (RGO) and carbon nanotubes (CNTs) for the fabrication of dye-sensitized solar cells (DSSCs). The prepared nanostructures were well-characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman measurements. The XRD, Raman and TEM results confirmed that the ZnO nanostructures were crystallized into the hexagonal phase, and the nanocomposites containing RGO and CNTs. Morphological studies performed by using FESEM and TEM images showed that the ZnO possessed tube-like morphology with length and diameter in the range of ~1 micron and 90–200 nm, respectively, which were uniform and densely covered on the surface of the carbon materials. The DSSCs were fabricated using prepared nanostructures as a working electrode and platinum as a counter electrode with ruthenium-based dyes and iodide electrolytes. To further improve the efficiency of fabricated solar cells, nanocomposites of prepared nanostructures of ZnO with RGO and CNTs were synthesized, and their results were compared with the pristine samples. The results showed that the ZnO/CNTs (0.5 wt%) nanocomposites electrode exhibited the highest power conversion efficiency (PCE) of DSSCs with a maximum value of 0.612% compared to 0.326% of DSSC with pure ZnO, and 0.574% of DSSC with ZnO/RGO. Significantly, this technique could be used for large-scale production using the existing economical and highly effective DSSC fabrication technique

Resulting Effect of the p-Type of ZnTe: Cu Thin Films of the Intermediate Layer in Heterojunction Solar Cells: Structural, Optical, and Electrical Characteristics

The microstructural, electrical, and optical properties of Cu-doped and undoped ZnTe thin films grown on glass substrates are covered in this article. To determine the chemical makeup of these materials, both energy-dispersive X-ray (EDAX) spectroscopy and X-ray photoelectron spectroscopy were employed. The cubic zinc-blende crystal structure of ZnTe and Cu-doped ZnTe films was discovered using X-ray diffraction crystallography. According to these microstructural studies, the average crystallite size increased as the amount of Cu doping increased, whereas the microstrain decreased as the crystallinity increased; hence, defects were minimized. The Swanepoel method was used to compute the refractive index, and it was found that the refractive index rises as the Cu doping levels rises. The optical band gap energy was observed to decrease from 2.225 eV to 1.941 eV as the Cu content rose from 0% to 8%, and then slightly increase to 1.965 eV at a Cu concentration of 10%. The Burstein–Moss effect may be connected to this observation. The larger grain size, which lessens the dispersion of the grain boundary, was thought to be the cause of the observed increase in the dc electrical conductivity with an increase in Cu doping. In structured undoped and Cu-doped ZnTe films, there were two carrier transport conduction mechanisms that could be seen. According to the Hall Effect measurements, all the grown films exhibited a p-type conduction behavior. In addition, the findings demonstrated that as the Cu doping level rises, the carrier concentration and the Hall mobility similarly rise, reaching an ideal Cu concentration of 8 at.%, which is due to the fact that the grain size decreases grain boundary scattering. Furthermore, we examined the impact of the ZnTe and ZnTe:Cu (at Cu 8 at.%) layers on the efficiency of the CdS/CdTe solar cells