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B56 a system with a magenetic ring current that flows in the opposite direction of most of the aromatic systems.

The efficacy of chitosan and silicon oxide to prevent postharvest weight loss and fungi infection in 'Valencia Late' oranges was tested. Three silicon oxide concentrations (0.1%, 0.2%, 1%) were applied as preharvest treatments. Chitosan treatments were performed at the same concentrations in postharvest fruit. Preharvest applications were carried out by tractor spraying, while fruit were submerged for 30 seconds in baths with the chitosan concentrations in the postharvest applications. In both cases, a positive control (water treatment) and negative control (fungicide) were included. Treated fruit were stored in a chamber to simulate commercial storage conditions (4 ºC, 90% RH) for 9 weeks. After this time, the weight loss and damage caused by fungi due to natural infection were evaluated. Both silicon oxide and chitosan applications were effective in controlling natural infection by Penicillium species but had no positive effect on weight loss.

[EN] This work aims to study the effect of immersion in a ethanolic food simulant in mechanically recycled poly(lactic acid) (PLAR) and its nanocomposites reinforced with halloysite nanotubes (HNT). PLAR was obtained by subjecting PLA to an accelerated ageing process, which includes photochemical, thermal and hydrothermal ageing steps, followed by a final demanding washing step. PLAR was further reinforced with 4 %wt. HNT to improve the properties of the PLAR films. The materials were melt compounded by melt extrusion and processed into films by compression molding. The resulting films were exposed to food simulant D1 (50 %vol. ethanol solution) for 10 days at 40 °C. The intrinsic viscosity, crystallization behavior, thermal stability as well as the mechanical performance were analyzed before and after the contact with the food simulant. The swelling, plasticizing and hydrolyzing effect of the food simulant led to an important decrease of the intrinsic viscosity of all the samples, along with a significant increase of the crystallinity. Thermal stability was negatively affected by the decrease of the molecular weight, while the high crystallinity values resulted in materials with higher Vickers hardness values after the immersion in the food simulant., This work was supported by European Union’s Horizon 2020 research and innovation program [grant agreement No. 860407 BIO-PLASTICS EUROPE], by MINECO-Spain [project CTM2017-88989-P] as well as Universidad Politécnica de Madrid [project UPM RP 160543006].

The oxidation and thermal stability of low-density polyethylene (LDPE) films (stabilized and unstabilized) used as greenhouse covering have been investigated. A mixture of kaolin, UV absorber, hindered amine light stabilizers (HALS) and heavy metals was used to stabilize LDPE films; these films were also compared with unstabilized LDPE films. Both films were exposed to natural weathering in Laghouat, Algeria. The oxidation resistance of unstabilized specimens for different ageing periods was determined by measuring the oxidation induction time (OIT) at 180 °C. It has been found that the highest OIT value was obtained for the unaged film and the values decline with ageing time. On the other hand, the stabilized specimens showed a significant stability under the conditions of OIT determination experiments. Furthermore, the oxidation resistance of these samples was evaluated by measuring the oxidation onset temperature (OOT). The results obtained showed that the OOT of the stabilized films ranges from 219 to 236 °C. Finally, a comparative analysis of the thermal stability results of both films was conducted. The activation energy of the photodegradation process of the both films was calculated by using TGA thermograms following the isoconversional approach. The results revealed that the stability of the stabilized specimens diminishes with ageing time and that the stabilizer additives improve the thermal stability of LDPE films. The influence of the photooxidation on the degree of crystallinity (based on DSC and WAXS techniques) of both films was also reported. Generally, there is a strong correlation between TGA, OIT, OOT, UV and FTIR results.

A genetic search algorithm in conjunction with density functional theory calculations was used to determine the lowest-energy minima of the pure B22 cluster and thereby to evaluate the capacity of its isomers to form endohedrally doped cages with two transition metal atoms M (M = Sc and Ti). An important charge transfer from metal atoms M to the boron cage takes place, stabilizing the endohedral compounds, as predicted with the genetic algorithm implemented. High-level coupled-cluster theory CCSD(T) calculations were carried out to confirm that the structures found are the lowest-energy isomers. For a deeper understanding of the doping effects and related charge transfer, the best structural motif of the B22 isomers was also determined when the bare cages are in anionic states, such as B222- and B224-. It was found that B22 has an appropriate size, geometric shape and electronic state to host the chosen metal atoms and, consequently, to form stable endohedrally doped compounds Ti@B22 (C2v, 4-Ti) and Sc@B22 (C2v, 5-Sc). The chemical bonding was analyzed in order to understand the molecular orbitals that these novel systems form. The cage aromaticity was evaluated by means of the nuclear independent chemical shift (NICS(0)iso) indices, the isochemical shielding surface (ICSSzz), the anisotropy of the current induced density (ACID) maps, and the magnetic ring current Gauge-Including Magnetically Induced Current (GIMIC) method, indicating that aromaticity plays a crucial role in the stabilization of endohedrally doped boron clusters. Finally, the thermodynamic stability of the latter, using parameters derived from density functional theory (DFT), was evaluated. Ab initio molecular dynamics (AIMD) simulations were performed to elucidate the stability, at high temperature, of the most stable endohedrally doped boron clusters 4-Ti and 5-Sc.

The main objective of the present research is to study the effect of the incorporation of low amounts of silk fibroin nanoparticles (SFNs) and yerba mate nanoparticles (YMNs) on the migration phenomenon into ethanolic food simulants as well as on the disintegrability under composting conditions of mechanically recycled polylactic acid (PLA). Recycled PLA was obtained under simulated recycling conditions by melt processing virgin PLA into films and further subjecting them to an accelerated aging process, which involved photochemical, thermal, and hydrothermal aging steps followed by an intense washing step. SFNs were extracted from Bombyx mori cocoons and YMNs from yerba mate waste. Then, recycled PLA was melted, reprocessed, and reinforced with either 1%wt. of SFNs or YMNs, by melt extrusion, and further processed into films by compression molding. The obtained nanocomposites were exposed to ethanolic food simulants (ethanol 10% v/v, simulant A and ethanol 50% v/v, simulant D1) and the structural, thermal, and mechanical properties were studied before and after the exposure to the food simulants. The migration levels in both food simulants were below the overall migration limits required for food contact materials. The materials were disintegrated under simulated composting conditions at the laboratory scale level and it was observed that the nanoparticles delayed the disintegration rate of the recycled PLA matrix, but nanocomposites were fully disintegrated in less than one month.

[EN] Cultivar Macabeo is one of the most planted white grape varieties of northern Spain. A general agreement supports many Vitis vinifera cultivars possibly being self-fertile, although this seems to be a variety-dependent characteristic. No previous information about the mating system of cv. Macabeo was found. This study aimed to analyze its mating system and to compare the in vivo fertilization process with and without artificial cross-pollination. Two treatments were performed: emasculation and cross-pollination. The seed number was counted, and pollen tube growth was observed by microscopy. The results showed that cv. Macabeo is self-fertile and selfing probably occurs before the flower opens. Pollen was found over the stigma of flowers before capfall and ovule fertilization was observed even in emasculated flowers, which suggests that germination and pollen tube growth happened in a very early flower development stage. Cross-pollination increased the presence of the pollen tubes growing inside flowers but was not necessary for fruit set. Ovule fertilization was very fast as 24 h (h) were enough for pollen tubes to reach the end of stylar canals., This research was supported by the Asociacion Club de Variedades Vegetales Protegidas as part of a project undertaken with the Universitat Politecnica de Valencia (Spain, UPV 20190822), of which H. Merle was the principal researcher. There was no additional external funding received for this study.

[EN] Aim of study: Several studies point out that storage at -20 ºC is a suitable method for preserving pollen of many species in the long term. Part of those studies indicate the total storage time at which these conditions are optimal. However, we have found a lack of information about the freezing time conditions and incubation temperature of loquat pollen. The main objective of this study was to evaluate the effect of the -20 ºC conservation temperature on loquat (Eriobotrya japonica (Thunb.) Lindl.) pollen. Area of study: The study was conducted in Montserrat (Valencia, Spain). Material and methods: Loquat flowers were collected in November 2017 and stored at -20 ºC for three time periods: 4 (T1), 6 (T2) and 8 (T3) months. Subsequently, pollen grains were incubated at different temperatures for 72 h. We analyzed (i) the effect of freezing conservation time; (ii) the effect of incubation temperature on germination; (iii) the interaction between these two factors. Main results: T1 showed higher germination percentage and tube length values (mean and maximum) than T2 and T3. The highest germination percentage (52.77%) was detected for T1 at an incubation temperature of 25 ºC. The interaction between freezing time and incubation temperature showed more consistent results for T1 than for T2 and T3. Research highlights: This suggests that storing at -20 ºC for more than 4 months affects pollen grain and reduces germination and pollen growth. Therefore, -20 ºC loquat pollen storage should not exceed 4 months., Asociacion Club de Variedades Vegetales Protegidas, as a part of a project undertaken with the Universitat Politecnica de Valencia UPV-20190822.

In this work, yerba mate nanoparticles (YMNs) were extracted from Ilex paraguairiencis yerba mate wastes and further used to improve the overall performance of mechanically recycled PLA (PLAR). Recycled PLA was obtained by melt reprocessing PLA subjected to an accelerated ageing process, which involved photochemical, thermal and hydrothermal ageing steps, as well as a final demanding washing step. YMNs (1 and 3 wt. %) were added to the PLAR during the melt reprocessing step and further processed into films. The main goal of the development of PLAR-YMNs bionanocomposites was to increase the barrier properties of recycled PLA, while showing good overall performance for food packaging applications. Thus, optical, structural, thermal, mechanical and barrier properties were evaluated. The incorporation of YMNs led to transparent greenish PLAR-based films with an effective blockage of harmful UV radiation. From the backbone FTIR stretching region (bands at 955 and 920 cm−1), it seems that YMNs favor the formation of crystalline domains acting as nucleating agents for PLAR. The morphological investigations revealed the good dispersion of YMNs in PLAR when they are used in the lowest amount of 1 wt. %, leading to bionanocomposites with improved mechanical performance. Although the addition of high hydrophilic YMNs increased the water vapor transmission, the addition of 1 wt. % of YMNs enhanced the oxygen barrier performance of the produced bionanocomposite films. These results show that the synergistic revalorization of post-consumer PLA and nanoparticles obtained from agri-food waste is a potential way for the production of promising packaging materials that meet with the principles of the circular economy.

Fresh market demands high quality fruit and, therefore, citrus growers and researchers are constantly looking for solutions to avoid seed presence. Current horticultural techniques have low effectiveness or high cost. The objective of this study is to evaluate the inhibition effect of seven products on the in vivo pollen tube growth in Nadorcott mandarin, which is a high-value seedy variety. To achieve this main objective, three inorganic fertilizers (ammonium nitrate, potassium nitrate, sulfur), and four saccharides (saccharose, methyl cellulose, callose, chitosan) were applied to Nadorcott stigmas 24 h before and after hand pollination. Pollen tubes were counted 1, 3, and 5 days after treatment in longitudinal blue violet autofluorescence-stained sections. Of the seven evaluated products, only sulfur had a strong inhibitory effect. Elemental sulfur (S8) inhibited pollen tube growth by 94-100%. This strong effect was observed regardless of sulfur being applied 24 h before or after pollination, and on fixed flowers 1, 3 or 5 days after applications. Saccharose treatment seemed to have the opposite effect: stimulated pollen tube growth, but the difference with the positive control was small and non-significant. The sulfur effect could be useful for designing agronomic applications capable of preventing seed presence in Nadorcott mandarin.

Objetivo: Describir en pacientes con cáncer glótico temprano tratado con cirugía y radioterapia, la calidad y funcionalidad de la voz. Diseño: Estudio de serie de casos. Materiales y métodos: Los parámetros objetivos de la voz fueron evaluados con análisis acústico. La funcionalidad de la voz fue evaluada con el índice de incapacidad vocal (VHI). El análisis estadístico fue realizado con SPSS 11.5 y SuperSMITHWeibull. Resultados: 12 sujetos que recibieron tratamiento para cáncer glótico temprano fueron incluidos en la muestra. El seguimiento clínico fue de 53.1 meses en promedio. El control de la enfermedad se observó en 100% de los casos, sin recaídas. El análisis acústico evaluó la frecuencia fundamental de la voz, que fue normal en 63,6% de los casos; adicionalmente las medidas del Jitter y Shimmer fueron anormales en todos los pacientes. El valor del índice de incapacidad mostró una disfuncionalidad leve en 58,4% de los casos y normal en 41,6% de los casos. Conclusiones e importancia clínica: El manejo del cáncer glótico temprano con cirugía y radioterapia resultó en una alteración de los parámetros objetivos de la voz en todos los sujetos; sin embargo, en nuestra muestra los pacientes refieren poca o ninguna disfuncionalidad en la vida diaria.

The vine decline caused by Monosporascus cannonballus is a limiting factor in different crops in several countries. The objective of this study was to quantify the M. cannonballus ascospores in soils covered with tropical dry forest and areas cultivated with pineapple, cotton, coconut, corn, mango, melon, papaya, sorghum and watermelon. Five areas were sampled in tropical dry forest and every crop. The M. cannonballus ascospores were extracted using the flotation method of sucrose. Ascospores of M. cannonballus were detected in all soil samples from Rio Grande do Norte and Ceará states, including tropical dry forest. There were significant differences among the ascospores densities of M. cannonballus, which varied from 0.55 to 2.21 ascospores g-1 soil. The lower densities were found in areas with cotton, coconut, mango, pineapple, and melon within the first and fifth years of cultivation, in addition to uncultivated areas of tropical dry forest. The highest ascospores density was found in papaya areas. Up to date, there is no study to prove that this crop is considered host of this phytopathogen. Cultivated areas with cucurbitaceous with more years of cultivation presented higher densities of M. cannonballus ascospores in soils from Brazilian semiarid. However, there is no direct relationship between M. cannonballus population density in the soil and the susceptibility of the host being cultivated in the soil at the time of sampling.

From an environmental point of view, mechanical recycling is, in general, a good end-of-life option for poly(lactic acid) (PLA), one of the most important biobased polymers. However, the degradation of PLA during the service life and, especially, during the mechanical recycling process, leads to a decrease in the properties of PLA, thus reducing the applications of the recycled plastic. The main aim of this work was to study the addition of small amounts of halloysite nanotubes, during the recycling step, as the basis of a cost-effective method for improving the properties of the recycled PLA. Raw halloysite was modified with an aminosilane, and 2% by weight of both raw and modified halloysite were melt compounded with PLA previously subjected to accelerated ageing. The addition of the nanotubes led to recycled materials with improved properties because halloysite reduces the degradation of PLA by blocking the carboxyl groups, generated during the ageing and washing steps, which catalyze the degradation during the recycling process. This effect was more intense in the silanized nanotubes, because the carboxyl groups were effectively blocked by acid–base interactions with the amino groups of the chemical modification. The properties of the recycled plastic with only 2 wt% of silanized halloysite were very close to those of the virgin plastic., The authors would like to thank the Centro Nacional de Microscopía Electrónica of the Universidad Complutense de Madrid (Spain), for the collaboration in the TEM measurements. This work was supported by MINECO-Spain (Grant Number CTM2017-88989-P) and Universidad Politécnica de Madrid (project UPM RP 160543006).

Vortex state and magnetic response in a disk with an array of weakly-superconducting (or normal regions) created in the sample increasing the temperature T locally by using a continuous wave laser (CWL) that emits a beam with a controlled heat output, beam duration and intensity are studied. The time-dependent Ginzburg–Landau theory is used to describe the interaction of the light with the superconductor, where the defects are include through the spatially-dependent temperature. Vortices penetrating into the weak-superconducting regions which are generated considering that T > Tc (Tc is the critical temperature of the sample) where the CWL is pointing. Qualitative changes are observed in the dynamics of the superconducting condensate in the presence of pinning with different shapes and sizes which are possible to be modified in the same superconducting sample without any structural changes that could include metals, permanent magnets and implantation of heavy ions.

A theoretical study has been performed for deposited AumAgn (m + n = 1–6) clusters. The combined use of the Mexican Enhanced Genetic Algorithm (MEGA) and Density Functional Theory (DFT) calculations allows us to explore the potential energy surface and therefore, find the global minimum configuration for each composition. We have performed calculations of clusters deposited on defects (oxygen vacancies) known as F centers on MgO (100) surfaces. Our results show interesting differences in the geometries of the clusters upon deposition and as a consequence in their electronic properties. The combination of two metals with different electronegativities creates an inhomogeneous charge distribution on their exposed surface producing good conditions for a catalytic process to take place.

A comparative theoretical study has been performed on AumRhn (6 ⩽ m + n ⩽ 10) clusters in the gas phase. The combined use of Density Functional Theory (DFT) calculations and the Mexican Enhanced Genetic Algorithm (MEGA) has been employed to efficiently explore the potential energy surface. Our results show interesting structural changes, such as the 2D-3D transformation on varying the Au:Rh composition. New structures of high stability are obtained when compared with either gold or rhodium pure clusters. The results show that the cluster properties exhibit different kind of dependencies on both the Au:Rh ratio and the cluster size.

In recent years, a great effort has been devoted to the development of new automated identification and sorting methods for post-consumer plastics in the waste streams that reach the recycling processes, as the final properties of the recycled materials largely depend on the purity of the plastic residue. This work explores the use of fluorescence spectroscopy as a complementary technique to address the limitations of the current technologies. Specifically, the use of fluorescent markers for the removing, for technical or safety related issues, of selected high density polyethylene containers from the waste stream has been studied. The results indicate that identification by extrinsic fluorescence can be easily achieved even with small proportion of markers (10−3 wt%) without significant change of the polymer structure. The effect of thermal, hygrothermal and photochemical degradation on the fluorescence emission has been analyzed. Although the signal intensity decreases during the accelerated degradation, distinguishable fluorescent emission was recorded even after sample exposure to aggressive conditions, thus enabling the correct identification of the marked plastics.

The aim of the current study is to explore the structural evolution of neutral and negatively charged gas-phase gold clusters in the size range of 27–30 atoms. We conducted an improved Genetic Algorithm global search combined with the density functional theory study, which we present and explain. New and lower energy structures are reported; these new structures are found to exhibit core–shell structures with the number of core atoms increasing with cluster size. Important discrepancies were observed in the energy ranking and energy differences of the obtained geometries when two different functionals (TPSS and PBE) are used. In general terms Au27– and Au28– clusters form nanotube-like structures, whereas that geometry changes into cage-like structures for Au29– and Au30–. On the contrary, structures related to a fcc fragment were found to own lower energies for the neutral systems for Au27, Au28, and Au29, while for Au30 a nonsymmetric cage with one core atom was the lowest-energy isomer. The obtained st...

In the present work, we discuss the electronic properties of supported dispersed bimetallic clusters with respect to their size, geometry, and Au

Recently, the use of natural materials has grown in the plastics industry. In this study, novel bio-nanocomposites were developed from poly(lactic acid)/poly(ε-caprolactone) (PLA/PCL) blends and silk fibroin nanoparticles (SFNP). SFNP were successfully synthesized from silk fibroin (SF) and analyzed by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The obtained results revealed that the well-ordered structures in SF were changed to the amorphous structures in SFNP. Then (PLA/PCL) blends containing 10–30% of PCL were prepared and characterized. According to the obtained results, the PLA/PCL (70/30) blend was selected as the optimized sample for further studies. The scanning electron microscopy results illustrated that the addition of 1% of SFNP into this blend improved the compatibility between PLA and PCL and reduced the PCL droplet sizes from 1.170 ± 92 to 794 ± 46 nm. The results from TGA analysis indicated that the presence of SFNP enhanced the thermal stability of materials at high temperatures. The crystallization kinetics results revealed that while SFNP promoted the crystallization of neat PLA, the crystallization rate of PLA/PCL blend was decreased upon the incorporation of nanofiller. Furthermore, the PLA/PCL/SFNP exhibited higher microhardness and barrier properties than the neat blend. The results suggest that the developed bio-nanocomposites are promising materials for demanding applications such as food packaging., The authors thank Perstorp Co. Ltd., Sweden, for supplying the PCL Capa™ 6800, MINECO-Spain (Project CTM2017- 88989-P) and Universidad Politécnica de Madrid (Project UPM RP 160543006). This project has received funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 860407 BIO-PLASTICS EUROPE

Poly(lactic acid) (PLA) is one of the most used biobased and biodegradable polymers. Due to their high stability, some of the newest grades of PLA are only degradable under severe industrial conditions. For these grades, mechanical recycling is a viable end-of-life option, with great environmental advantages. However, the polymer undergoes degradation during its service life and in the melt reprocessing, which leads to a decrease in properties that can compromise the recyclability of PLA. The goal of this work was to evaluate the usefulness of adding small amounts of two organic fillers, chitosan, and silk fibroin nanoparticles, during the recycling process for improving the properties of the recycled plastic. The degradation level of the aged polymer and the nature and amount of filler affect the performance of the recycled plastics. The fillers reduce the degradation during the melt reprocessing of PLA previously subjected to severe hydrolysis, thus increasing the intrinsic viscosity of the recycled plastic. A careful selection of the added organic filler lead to recycled plastics with improvements in some key mechanical, thermal, and barrier properties. Thus, the use of organic fillers represents a cost-effective and environmentally sound way for improving the mechanical recycling of bioplastics., This work was supported by MINECO-Spain (pro-ject CTM2017-88989-P), Universidad Politécnica de Madrid (projectUPM RP 160543006), and the European Commission (Horizon 2020,project 860407-BIO-PLASTICS EUROPE). Dr. Lozano-Pérez’s researchcontract at IMIDA was partially supported (80%) by the ERDF/FEDEROperational Programme“Murcia”CCI N° 2007ES161PO001 (ProjectNo. 14-20/20)

In this work, yerba mate nanoparticles (YMNs) were extracted from Ilex paraguairiencis yerba mate wastes and further used to improve the overall performance of mechanically recycled PLA (PLAR). Recycled PLA was obtained by melt reprocessing PLA subjected to an accelerated ageing process, which involved photochemical, thermal and hydrothermal ageing steps, as well as a final demanding washing step. YMNs (1 and 3 wt. %) were added to the PLAR during the melt reprocessing step and further processed into films. The main goal of the development of PLAR-YMNs bionanocomposites was to increase the barrier properties of recycled PLA, while showing good overall performance for food packaging applications. Thus, optical, structural, thermal, mechanical and barrier properties were evaluated. The incorporation of YMNs led to transparent greenish PLAR-based films with an effective blockage of harmful UV radiation. From the backbone FTIR stretching region (bands at 955 and 920 cm&minus, 1), it seems that YMNs favor the formation of crystalline domains acting as nucleating agents for PLAR. The morphological investigations revealed the good dispersion of YMNs in PLAR when they are used in the lowest amount of 1 wt. %, leading to bionanocomposites with improved mechanical performance. Although the addition of high hydrophilic YMNs increased the water vapor transmission, the addition of 1 wt. % of YMNs enhanced the oxygen barrier performance of the produced bionanocomposite films. These results show that the synergistic revalorization of post-consumer PLA and nanoparticles obtained from agri-food waste is a potential way for the production of promising packaging materials that meet with the principles of the circular economy.

Poly(lactic acid) (PLA) is one of the most used biobased and biodegradable polymers. Due to their high stability, some of the newest grades of PLA are only degradable under severe industrial conditions. For these grades, mechanical recycling is a viable end-of-life option, with great environmental advantages. However, the polymer undergoes degradation during its service life and in the melt reprocessing, which leads to a decrease in properties that can compromise the recyclability of PLA. The goal of this work was to evaluate the usefulness of adding small amounts of two organic fillers, chitosan, and silk fibroin nanoparticles, during the recycling process for improving the properties of the recycled plastic. The degradation level of the aged polymer and the nature and amount of filler affect the performance of the recycled plastics. The fillers reduce the degradation during the melt reprocessing of PLA previously subjected to severe hydrolysis, thus increasing the intrinsic viscosity of the recycled plastic. A careful selection of the added organic filler lead to recycled plastics with improvements in some key mechanical, thermal, and barrier properties. Thus, the use of organic fillers represents a cost-effective and environmentally sound way for improving the mechanical recycling of bioplastics.

[EN] Background In Citrus spp., gibberellic acid (GA) has been proposed to improve different processes related to crop cycle and yield. Accordingly, many studies have been published about how GA affects flowering and fruiting. Nevertheless, some such evidence is contradictory and the use of GA applications by farmers are still confusing and lack the expected results. Purpose This review aims to collate, present, analyze and synthesize the most relevant empirical evidence to answer the following questions: (i) how does gibberellic acid act on flowering and fruiting of citrus trees?; (ii) why is all this knowledge sometimes not correctly used by farmers to solve yield problems relating to flowering and fruit set? Methods An extensive literature search to obtain a large number of records about the topic was done. Searches were done in five databases: WoS, Scopus, Google Academics, PubMed and Scielo. The search string used was "Gibberellic acid" AND "Citrus". Records were classified into 11 groups according to the development process they referred to and initial data extraction was done. Records related with flowering and fruit set were drawn, and full texts were screened. Fifty-eight full text records were selected for the final data extraction. Results Selected studies were published from 1959 to 2017 and were published mainly in Spain, USA, Brazil and Japan. Twelve species were studied, and Citrus sinensis, C. reticulata and C. unshiu were the principal ones. Most publications with pre-flowering treatments agreed that GA decreases flowering, while only 3 out of 18 did not observe any effect. In most of these studies, the effect on fruit set and yield was not evaluated. Studies with treatments at full bloom or some weeks later mostly reported increased fruit set. However, these increases did not imply higher yields. The results on yield were highly erratic as we found increases, decreases, no effects or variable effects. Conclusions Despite some limitations, the action of GA related to cell division and growth, stimulating the sink ability of the organ and discouraging its abscission, has been clearly established through reviewed studies. GA applications before flowering counteract the floral induction caused by stress reducing flowering. However, on adult trees under field conditions, reducing flowering by applying GA would be difficult because it would be necessary to previously estimate the natural floral induction of trees. During flowering and fruit set, many problems may arise that limit production. Only when the problem is lack of fruit set stimulus can GA applications improve yields. However, much evidence suggests that the main factor-limiting yield would be carbohydrate availability rather than GA levels. GA applications increased fruit set (often transiently), but this increase did not mean improved yields., This research was supported by the Asociacion Club de Variedades Vegetales Protegidas as part of a project undertaken with the Universitat Politecnica de Valencia (Spain, UPV 20170673), of which Merle H, was the principal researcher. There was no additional external funding received for this study.

Many watermelon (Citrullus lanatus) diseases are caused by soilborne pathogens in Brazil and worldwide. The goal of this study was to identify and quantify the frequency of phytopathogenic fungi associated with watermelon root rot and vine decline that were also present in the roots of weeds in the major watermelon production regions in the state of Rio Grande do Norte, Brazil. We collected root samples from 10 of the most prevalent weed species in 16 watermelon producing areas. The plants were identified and their frequencies in the fields were calculated. The fungi found in the weed roots were isolated and the main genera associated with watermelon vine decline were identified. We identified 13 weed species belonging to nine botanical families. The weed species with the highest frequencies found in the field were Amaranthus spinosus (25.0%), Trianthema portulacastrum (18.8%), Commelina sp. (18.8%), and Boerhavia diffusa (12.5%). The fungi Macrophomina, Rhizoctonia, and Monosporascus were isolated from the roots of the weed plants. While Macrophomina was isolated from 12 different types of plants, Rhizoctonia and Monosporascus were isolated from four and two different plant species, respectively. RESUMO Considerável número de doenças que acometem a melancia (Citrullus lanatus) são causadas por patógenos habitantes do solo no Brasil e no mundo. O objetivo do presente trabalho foi identificar e quantificar a frequência de fungos fitopatógenos associados a "podridão de raízes e declínio de ramas" em melancia, presentes nas raízes de plantas daninhas nas principais áreas produtoras no estado do Rio Grande do Norte. Foram coletadas 10 amostras de raízes de espécies de plantas daninhas de maior prevalência em 16 áreas produtoras de melancia. As plantas foram identificadas e, calculada a respectiva frequência em campo. Foi realizado o isolamento fúngico das raízes, sendo posteriormente identificados os principais fungos associados ao declínio de ramas. Foram identificadas 13 espécies de plantas daninhas, pertencentes a nove famílias botânicas. As espécies de plantas daninhas que apresentaram as maiores frequências em campo foram Amaranthus spinosus (25,0%), Trianthema portulacastrum (18,8%), Commelina sp. (18,8%) e Boerhavia diffusa (12,5%). Das raízes das plantas daninhas que apresentaram maior frequência foram isolados os gêneros Macrophomina, Rhizoctonia e Monosporascus. O primeiro foi isolado de 12 espécies de plantas, o segundo de quatro espécies e o terceiro de duas espécies.

Disease progression and soil population dynamics of Monosporascus cannonballus ascospores were studied and compared through the entire growing season in muskmelon, watermelon, and watermelon grafted onto Cucurbita rootstock crops. In muskmelon and watermelon, there was a decrease of ascospore counts in soil from transplanting until first symptoms of vine decline were observed. This decrease probably was related to ascospore germination and subsequent root infection. Later, there was a remarkable increase of ascospore counts in a parallel way to the quick development of vine decline symptoms, which lead to plant death. In these crops, root colonization adjusted to first-order linear equations and vine decline progression best correlated with exponential and logistic models. In contrast, there were no symptoms of vine decline on grafted watermelon. Furthermore, the isolation of M. cannonballus from Cucurbita roots was considerably lower, perithecia were never observed, and ascospore soil populations remained stable. These results suggest that disease control by grafting onto genus Cucurbita seems to be related primarily by the increased resistance of its root system to infection by M. canonballus, and provide further evidence of the use of grafting as a disease management measure for this disease.

The influence of nanoclays on the structural changes of hydrated poly(l-lactic acid) (PLLA) was investigated at two temperatures, above and below its Tg. Samples of a commercial PLLA and nanocomposites with 2 wt% of an organically modified montmorillonite and an unmodified halloysite were kept in a phosphate buffered solution for different times at 37 and 58 °C and then characterized. The crystallinity degrees and the nature of the crystalline structures developed were determined by differential scanning calorimetry, X-Ray Diffraction and Fourier Transform infrared spectroscopy. While in the cold crystallization of PLLA in dry conditions the α form is obtained only above 100 °C, different mixtures of α and α′ forms were obtained in water at 58 °C, depending on the clay used. The hydrolytic degradation of PLLA played a main role in the structural transformations found at long immersion times, since the short chains formed allowed greater crystallinity degrees and leaded to more perfect crystals. PLLA structure is changed by clays because of its ability as nucleating agents but also due to its effect on the hydrolytic degradation. The unmodified tubular halloysite inhibited degradation, so that lower degrees of crystallinity were obtained in the halloysite based nanocomposite. On the other hand, the modified montmorillonite acted as catalyst of degradation, which explained the appearance of crystalline structures in the nanocomposite with montmorillonite after 84 days of immersion at 37 °C.

The growing production of poly(lactic acid) (PLA) has increased the interest for the mechanical recycling of this polymer. The main objective of this work is to study the effect of different mechanical recycling processes on the hydrolytic degradation of PLA. A commercial grade of PLA was subjected to two different recycling processes, one of them comprising an accelerated thermal and photochemical aging and a second melt compounding and compression molding step, and other including a demanding washing step after the accelerated aging process. The accelerated aging and, especially, the washing step had a significant effect on degradation during recycling. Samples of virgin and recycled plastic immersed in a phosphate buffered solution at 37 or 58 °C were removed at selected times and then characterized by gravimetric analysis, IR and UV spectroscopy, thermal analysis, x-ray diffraction and microhardness and viscosity measurements. The water absorption process, at both temperatures, can be modeled using a Fickian model only when the immersion times were short. The different recycling processes caused an increase of the diffusion coefficient of PLA at 37 °C, while at 58 °C the differences were smaller. DSC results pointed out that mechanical recycling promotes a slight crystallization of PLA at 37 °C that explains the increasing of the hardness during the hydrolysis.

[EN] Between February 2018 and April 2018, flowers were collected from eight Rosaceae species. Flowers were kept in a freezer at -20 degrees C for three freezing times (Treatment 1, two months; Treatment 2, four months; Treatment 3, six months). After extracting pollen, in vitro germination was induced in a culture medium and incubated at six different temperatures for 72 h. The percentage of pollen germination, average pollen tube length and maximum pollen tube length were measured. Pollen germination was maximum for all species between 15 degrees C and 30 degrees C. Cydonia oblonga, Malus sylvestris, Prunus avium, Prunus domestica, Prunus dulcis, Prunus persica and Pyrus communis obtained 30-52% pollen germination between 15 degrees C and 20 degrees C. Prunus cerasifera had 40% pollen germination at 30 degrees C. All species studied reached the maximum pollen tube length between 10 degrees C and 25 degrees C. Germination did not change significantly for any of the species with freezing time, but we found significant differences in the three parameters measured between treatments. The highest germination percentages were obtained in Treatment 2 (four months frozen at -20 degrees C), while the maximum pollen tube length was reached in Treatment 1 (two months frozen at -20 degrees C). According to our results, freezing time affected the germination-temperature patterns. This could indicate that studies on the effect of temperature on pollen germination should always be carried out with fresh pollen to obtain more conclusive data., This work was supported by the Asociacion Club de Variedades Vegetales Protegidas as a part of a project with the Universitat Politecnica de Valencia (UPV 20170673). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

[EN] Phytotron has been widely used to assess the effect of numerous parameters on the development of many species. However, less information is available on how to achieve fast profuse flowering in young fruit trees with this plant growth chamber. This study aimed to outline the design and performance of a fast clear methodology to force flowering in young mandarin trees (cv. Nova and cv. Clemenules) and to analyze the influence of induction intensity on inflorescence type. The combination of a short water stress period with simulated spring conditions (day 13 h, 22 °C, night 11 h, 12 °C) in the phytotron allowed flowers to be obtained only after 68-72 days from the time the experiment began. Low-temperature requirements were adequately replaced with water stress. Floral response was proportional to water stress (measured as the number of fallen leaves): the greater the induction, the larger the quantity of flowers. Floral induction intensity also influenced inflorescence type and dates for flowering. Details on artificial lighting (lumens), photoperiod, temperatures, plant size and age, induction strategy and days for each stage are provided. Obtaining flowers from fruit trees at any time, and also several times a year, can have many advantages for researchers. With the methodology proposed herein, three, or even four, flowering periods can be forced each year, and researchers should be able to decide when, and they will know, the duration of the entire process. The methodology can be useful for: flower production and in vitro pollen germination assays; experiments with pests that affect early fruit development stages; studies on fruit physiological alterations. All this can help plant breeders to shorten times to obtain male and female gametes to perform forced-crosses., The authors thank Jose Javier Zaragoza Dolz for providing technical assistance and helping in the management tasks. This research was partially supported by the Asociacion Club de Variedades Vegetales Protegidas as part of a project undertaken with the Universitat Politecnica de Valencia (UPV 20170673).

Obtaining citrus fruits without seeds is a recurrent objective for farmers as it is one of the most valued characteristics, especially in mandarins. ‘Afourer’ tangor is a highly valuable well-established mandarin, and a high percentage of seeded fruits are produced under cross-pollination conditions. Several agronomic techniques have been suggested to control presence of seeds, such as covering with nets and copper sulfate (CuSO4) and gibberellic acid (GA3) treatments. Natural bee repellents are also proposed to reduce the number of seeds per fruit. In this study, we aimed to compare the effect of several agronomic treatments to reduce the seed number in 'Afourer' mandarin. To this end, we assessed the effect of chemical and bee repellent treatments on the seed number per fruit and the side effect on yield and fruit diameter. Under these experimental conditions the two bee repellents, one based on zinc and one based on Capsicum annuum, were not useful for reducing the seed number per fruit in ‘Afourer’ mandarin. The copper sulfate + GA3 treatment reduced the seed number per fruit by only 35%, and this efficiency was clearly not enough to reduce the seed number for commercial purposes. The most effective method to reduce the seed number per fruit was covering with nets, but this technique led to markedly reduced yields. Yield data was highly variable. Fruit diameter correlated positively with the seed number, but it was a weak relationship as the seed number explained only 15% of fruit size variability (R2 = 0.15).

En este trabajo, se describe la implementación y puesta en marcha de un juego de escape (escape room), diseñado para conmemorar el Año Internacional de la Tabla Periódica de los Elementos Químicos y destinado a estudiantes de primeros cursos universitarios en carreras técnicas, así como a estudiantes de cursos inferiores. Se pretende que, a través del juego, los participantes adquieran competencias específicas básicas de Química y competencias transversales como trabajo en grupo y creatividad y, al mismo tiempo, comprendan la dificultad que conlleva un descubrimiento científico de la magnitud de la Tabla Periódica de Mendeléyev. El escape room se ha probado con varios grupos de alumnos de la Escuela Técnica Superior de Ingenieros Industriales de la Universidad Politécnica de Madrid con éxito, aunque se espera su implementación más masiva durante los primeros meses del curso 2019-20. También se describen de forma cualitativa los resultados de la implementación preliminar realizada.

A theoretical study has been performed for deposited AumAgn (m + n = 1-6) clusters. The combined use of the Mexican Enhanced Genetic Algorithm (MEGA) and Density Functional Theory (DFT) calculations allows us to explore the potential energy surface and therefore, find the global minimum configuration for each composition. We have performed calculations of clusters deposited on defects (oxygen vacancies) known as F centers on MgO (100) surfaces. Our results show interesting differences in the geometries of the clusters upon deposition and as a consequence in their electronic properties. The combination of two metals with different electronegativities creates an inhomogeneous charge distribution on their exposed surface producing good conditions for a catalytic process to take place.