Composition, Optical Resonances, and Doping of InP/InGaP Nanowires for Tandem Solar Cells: a Micro-Raman Analysis.

We present a micro-Raman study of InP/InGaP tandem junction photovoltaic nanowires. These nanowires render possible InGaP compositions that cannot be made in thin films due to strain. The micro-Raman spectra acquired along the nanowires reveal the existence of compositional changes in the InGaP alloy associated with the doping sequence. The heavily Zn-doped InxGa1-xP (x is the In molar fraction) side of the tunnel diode is Ga rich, x = 0.25, with respect to the n-type and intrinsic segments of the top cell, which are close to the nominal composition of the NWs (x = 0.35). The p-type end segment is still Ga-rich. Electromagnetic resonances are observed in the tunnel diode. The Raman signal arising from the InGaP side of the tunnel diode is significantly enhanced. This enhancement permits the observation of a Raman mode that can be associated with an LO phonon plasmon coupled mode (LOPCM). This mode has not been previously reported in the literature of InGaP, and it permits the Raman characterization of the tunnel diode. The analysis of this mode and its relation to the LO phonon modes of the alloy, InP-like and GaP-like, allows to establish an apparent one-mode behavior for the phonon plasmon coupling. It indicates that hole plasma couples to the GaP-like LO mode. The LOPCMs are modeled using the Lindhard Mermin formalism for the dielectric function.

The Influence of the Long-Term Outdoor Storage of Rockrose (Cistus laurifolius L.) Shrub Biomass on Biofuel's Quality, Pre-Treatment and Combustion Processes.

Biomass storage is an essential requirement in the supply chain of bio-refineries and power plants. This research aims to evaluate the influence of long-term outdoor storage (1 year) of baled rockrose (Cistus laurifolius L.) shrub biomass on biofuel's quality, pre-treatment processes and on combustion emissions in an industrial boiler. The raw material was obtained from different rockrose shrublands in north central Spain. A total of 233 tWM (tones of wet matter) of biomass were used to produce biofuels (30 mm of milled biomass and Ø 8 mm pellets) in the pre-treatment pilot plants at CEDER-CIEMAT. The combustion tests were conducted in an industrial moving grate boiler with a thermal power of 50 MWth, in a 17 MWe power plant. Outdoor storage improved some biofuel quality parameters, mainly the reduction in ash content, which allowed 30 mm of milled material to be classified as class I1 (ISO 17225-9:2022) and pellets as class I3 (ISO 17225-2-2021). No significant differences were observed in the total specific mass flow and energy consumption in the pre-treatment processes. The combustion tests had similar results, with the emissions being below the limits established in the directive (EU) 2015/2193. The results obtained indicated that the 1-year outdoor storage of rockrose-baled biomass, under Mediterranean conditions, was feasible for its subsequent use as biofuel.

Yield, Chemical Composition and Bioactivity of Essential Oils from Common Juniper (Juniperus communis L.) from Different Spanish Origins.

Essential oils (EOs) obtained from Juniperus communis L. are frequently used in the production of bioproducts. However, there are no studies regarding industrial crops' production, allowing for better control of the quality and production of juniper EOs. To select the plant material for developing future crops of this species in northern Spain, four locations where this shrub species grows in the wild were selected and samples of both genera were collected. The EOs were obtained by steam distillation, and their chemical composition and bioactivity were evaluated. The results showed that the yield of EOs from male and female samples were within the usual reported ranges, varying between 0.24 and 0.58% (dry basis, d.b.). However, limonene content in three locations varied between 15 and 25%, which is between 100% and 200% higher than the values usually reported for other European countries. The antibacterial activity was determined by broth microdilution and showed that gram-positive bacteria were more susceptible to the tested EOs since, in general, lower MIC values were obtained compared to gram-negatives. The EOs from location 1 (L1F) and 2 (L2M) inhibited the growth of six out of the eight clinical strains tested. Samples from location 1 were particularly effective, exhibiting MBC against two gram-negative (E. coli and P. mirabilis) and one gram-positive bacteria (E. faecalis). Moreover, the majority of the EOs tested showed anti-inflammatory activity. Cytotoxic effect has been demonstrated in tumor cell lines, with the best results observed against gastric carcinoma (AGS) cells (GI50 between 7 to 77 µg/mL). Although generally presenting higher GI50, most samples also inhibited the growth of non-tumoral cells, particularly hepatocytes (PLP2 cells). Therefore, its use for their anti-proliferative activity should consider specific conditions to avoid damaging normal cells. Finally, the results and conclusions obtained led to the selection of the female shrubs from location 1 (L1F) as the plant material to be propagated in order to produce plants for a future juniper crop.

Assessment of the Use of Common Juniper (Juniperus communis L.) Foliage following the Cascade Principle.

Juniperus communis L. is a species commonly grown in regions of the Northern Hemisphere, and is a good candidate to be cultivated in marginal lands. Plants coming from a pruning performed in a natural population located in Spain were used to assess the yield and quality of different products obtained following the cascade principle. A total of 1050 kg of foliage biomass were crushed, steam-distilled, and separated into fractions to produce biochar and absorbents for the pet industry using pilot plants. The obtained products were analysed. The essential oil, with a yield of 0.45% dry basis and a qualitative chemical composition similar to that described for the berries in international standards or monographs, showed antioxidant activity with promising CAA results (inhibition of 89% of the cell's oxidation). However, regarding antibacterial and antifungal activities, it only inhibited the growth of microorganisms at the maximum concentration tested, 2.5%. Concerning the hydrolate, it did not show bioactivity. Regarding the biochar, whose yield was 28.79% dry basis, interesting results were obtained for its characterisation as a possible soil improver for agronomic purposes (PFC 3(A)). Finally, promising results were obtained regarding the use of common juniper as absorbent, taking into account the physical characterisation and odour control capacity.

Catastrophic optical damage in 808†nm broad area laser diodes: a study of the dark line defect propagation.

We present a study of the propagation of dark line defects (DLDs) in catastrophically damaged 808 nm laser diodes, based on cathodoluminescence (CL) measurements and laser mode propagation simulations. Room temperature CL images show blurred DLDs running parallel to the laser cavity. Remarkably, low temperature images reveal their true morphology: the blurred lines are resolved as parallel narrow discontinuous DLDs. This morphology does not match the usually reported molten front scenario of DLD propagation. Low temperature images show that DLDs consist of a sequence of catastrophic optical damage (COD) events separated a few micrometers from each other. Consequently, a different propagation scheme is proposed. The points where the CODs occur suffer a temperature increase and these hot spots play a capital role in the propagation of the DLDs. Their influence on the beam distribution is modelled using finite element methods. The calculations evidence changes on the intensity distribution of the laser that qualitatively reproduce the DLD shapes. Additionally, the COD events result in the generation of defects in the region that surrounds them. The successive CODs in the discontinuous DLDs are rationalized in terms of the enhanced laser absorption in these sensitized regions where the laser beam is concentrated by thermal lensing.

Chemical and Bioactive Characterization of the Essential Oils Obtained from Three Mediterranean Plants.

Cupressus sempervirens L., Juniperus communis L. and Cistus ladanifer L. are Mediterranean arboreal and shrub species that possess essential oils (EO) in their leaves and branches. This study aimed at characterizing the EOs obtained by steam distillation from the three species collected in different locations from Spain (Almazán, Andévalo, Barriomartín, Cerezal, Ermitas and Huéscar). For this purpose, volatiles composition was determined by GC-MS, and different bioactivities were evaluated. The highest content in terpenes was observed in C. sempervirens (Huéscar origin) followed by J. communis (Almazán origin), corresponding to 92% and 91.9% of total compounds, respectively. With exception of C. ladanifer from Cerezal that presented viridiflorol as the most abundant compound, all the three species presented in common the α-pinene as the major compound. The EOs from C. ladanifer showed high antibacterial potential, presenting MIC values from 0.3 to 1.25 mg/mL. Concerning other bioactivities, C. ladanifer EO revealed an oxidation inhibition of 83%, while J. communis showed cytotoxicity in the MCF-7 cell line, and C. sempervirens and C. ladanifer EOs exhibited the highest potential on NCI-H460 cell lines. Nevertheless, some EOs revealed toxicity against non-tumoral cells but generally presented a GI50 value higher than that of the tumor cell lines.

Essential Oils from Residual Foliage of Forest Tree and Shrub Species: Yield and Antioxidant Capacity.

Increasing applications and markets for essential oils could bring new opportunities for cost-effective and sustainable management of unused forestry biomass; however, better knowledge of the production and application of such essential oils is necessary. The objective of this work is to contribute to greater knowledge of the essential oil production on a pilot scale from foliage biomass of wild shrubs and tree residues produced in some forestry enhancement operations and to study their antioxidant capacity (ORAC-oxygen radical absorbance capacity). Fresh biomass (twigs) of seven species (E. globulus, E. nitens, P. pinaster, P. sylvestris, R. officinalis, C. ladanifer, and J. communis) was manually collected in Spain in two different periods and was ground at 30 mm and distilled in a 30 L stainless steel still with saturated steam. The essential oil components were identified by GC-MS and quantified by GC-FID, and their antioxidant activity was determined with the ORAC method. Promising results on essential oil yield were obtained with E. globulus, E. nitens, R. officinalis, and J. communis. All essential oils studied exhibited antioxidant capacity by the ORAC assay, particularly that from C. ladanifer. Moreover, oxygenated sesquiterpenes contents, one of the minor components of oils, were significantly correlated with ORAC values.

Influence of the Storage of Cistus ladanifer L. Bales from Mechanised Harvesting on the Essential Oil Yield and Qualitative Composition.

Cistus ladanifer is a Mediterranean native plant from which valuable products, such as essential oil, are obtained. Manual harvesting of the plants in wild shrublands is usual during short periods of time. Their mechanised harvesting could increase the volume of harvested plants and prevent fires, further storage of the plants collected being necessary. The objective of this work is to study the influence of the storage period of mechanically harvested bales on the essential oil yield and qualitative composition. The harvesting trials were carried out with an adapted commercial harvester baler and the storage of the bales was performed indoors during 1-7 days, 15-30 days and 100-120 days. Afterwards, the bales were crushed (30 mm) and distilled in a 30 litre stainless steel still with saturated steam (0.5 bar). The essential oil components were identified by GC-MS and quantified by GC-FID. The storage of mechanically harvested Cistus ladanifer does not decrease the oil yield of steam distillation on a pilot scale. However, it leads to differences in the quantitative composition of the essential oils, decreasing the total monoterpene compounds content and increasing that of oxygenated sesquiterpenes, especially when the biomass is stored for 100-120 days, without affecting its qualitative composition.

Permittivity Measurements for Cypress and Rockrose Biomass Versus Temperature, Density, and Moisture Content.

Permittivity of materials is of utmost importance for microwave applicators' design and to predict high-frequency dielectric heating of materials. In the case of aromatic plant biomass, however, there are few data that help researchers design microwave applicators for microwave-assisted extraction. In this work, the permittivity of cypress and rockrose biomass samples were measured versus temperature, density, and moisture content. A resonant technique based on a coaxial bi-reentrant microwave cavity was employed to obtain the complex permittivity of biomass samples as a function of those magnitudes around the 2.45 GHz ISM frequency. The obtained measurements show that large variations for permittivity values can be found with moisture content and density changes for both cypress and rockrose biomass. Temperature also has effects in a lesser degree, although it has an important influence on the cypress biomass loss factor. Polynomial expressions fitting the experimental data were provided in order to facilitate the estimation of intermediate values, which were not explicitly arranged in this work. As a general trend, the permittivity of cypress and rockrose biomass increases with increasing values of moisture content and density, whereas the biomass loss factor increases when temperature rises.