Development of Novel Anti-Microbial Plant Essential-Oil Treatments to Reduce the Postharvest Incidence of Botrytis cinerea of Strawberries

Fresh strawberries have grown into a multi-billion dollar industry over the last few decades in California. Botrytis cinerea or grey mold, is the worst pathological disorder affecting strawberry fruit causing cull rates of up to 30% in the worst seasons. Strawberry fruits are fragile and have a short shelf-life making timely harvest, cooling, and marketing an absolute necessity. The current industry standard is to ship strawberries in an overwrapped CO₂-enriched headspace pallet in refrigerated trucks at 33 °F. However, B. cinerea has the ability to grow at very low temperatures and continues to plague the strawberry industry during postharvest storage and retail sale. Postharvest treatments available for strawberry preservation and disease management have been severely limited due to the reluctance to spray or wash the fruit. Consumers are also demanding produce that is free from synthetic chemical residues. Recent research with plant essential-oil volatile compounds has indicated that they have significant anti-fungal activity. Very little information is available regarding the use of essential-oil compounds for postharvest treatments on California strawberries to reduce the incidence of B. cinerea. The primary objective of this study was to investigate the potential for synergy to control B. cinerea through the combined application of volatile treatment constituents with uniquely different modes of action. Strawberries were acquired from commercial growers in the Santa Maria area of California on the day of harvest. Volatile essential-oil compounds were diluted in ethanol and applied to sachets which were then affixed to the inner lids of randomly selected clamshells. Clamshells were individually overwrapped with a micro-perforated 1-mil polyethylene film. The marketable shelf-life, percent rotted fruit, headspace atmosphere, postharvest quality, and sensory analysis were determined during 14-21 days storage at 40°F. The combination of ethanol (495.5 ppm), methyl jasmonate (4.5 ppm), citral (30 ppm), linalool (30 ppm), and vanillin (30 ppm) was the most effective formula to reduce rot and increase shelf-life overall and strawberries treated with 600 ppm of this blend maintained acceptable organoleptic quality. Applying high levels (750 ppm or more) of this formulation resulted in phytotoxic calyx desiccation after only 3 days at 40°F. However, moderate amounts (300-600 ppm per package) did not desiccate the calyx until 7-11 days of storage allowing sufficient time to market and consume the berries before the effect would be noticeable. A blend of essential-oil volatile compounds has the ability to significantly reduce postharvest losses from B. cinerea, can be applied without spraying on or washing fruit, and can be derived from natural sources. Additional Index Words: Methyl jasmonate, carvacrol, thymol, citral, linalool, vanillin, Induced Acquired Resistance

Introduction to Special Focus

Early childhood is a period that is marked by rapid changes in development. Exposure to enriched experiences such as positive family interactions, participation in early childhood education, and community engagement can foster healthy development and prevent many behavioral and mental health difficulties. Conversely, young children’s development can be negatively influenced by a variety of risk-factors that have unfortunate long-term outcomes. Given the pervasive impact of behavioral development on young children’s overall developmental outcomes, research examining strategies to enhance young children’s positive behavioral outcomes is needed. The purpose of this paper is to introduce Part 1 of a two part special issue in Perspectives on Early Childhood Psychology and Education that pertains to enhancing young children’s behavioral outcomes. Rationale for the special issue, content of included articles, and special considerations for readers are described

Metallurgical Structures of As-Cast and Heat-Treated High-Palladium Dental Alloys

Scanning electron microscope observations and energy-dispersive spectroscopic analyses have been performed on two first-generation and two second-generation high-palladium dental casting alloys. A specimen design simulating a maxillary central incisor coping was employed to conserve metal, while providing thin and thick sections to yield a range of solidification rates. The alloys were centrifugally cast in air, following standard dental laboratory techniques; three castings were prepared for each alloy. Each casting was sectioned to produce two mirror-image specimens, and one specimen received the appropriate oxidation heat treatment, followed by a simulated full porcelain firing sequence. After metallographic polishing, specimens were examined with a scanning electron microscope. The as-cast alloys displayed multi-phase microstructures which could be explained by the rapid solidification conditions and the relevant phase diagrams. The simulated porcelain firing heat treatment caused a variety of bulk microstructural changes in the coping sections, along with formation of complex subsurface oxidation regions which were less thick for the second-generation alloys. Elemental compositions of the palladium solid solution matrix in the heat-treated alloys were in good agreement with nominal alloy compositions provided by the manufacturers. Ruthenium-rich particles found in the microstructures of three alloys are consistent with a proposed mechanism for grain refinement

Metallurgical Structures of As-Cast and Heat-Treated High-Palladium Dental Alloys

Scanning electron microscope observations and energy-dispersive spectroscopic analyses have been performed on two first-generation and two second-generation high-palladium dental casting alloys. A specimen design simulating a maxillary central incisor coping was employed to conserve metal, while providing thin and thick sections to yield a range of solidification rates. The alloys were centrifugally cast in air, following standard dental laboratory techniques; three castings were prepared for each alloy. Each casting was sectioned to produce two mirror-image specimens, and one specimen received the appropriate oxidation heat treatment, followed by a simulated full porcelain firing sequence. After metallographic polishing, specimens were examined with a scanning electron microscope. The as-cast alloys displayed multi-phase microstructures which could be explained by the rapid solidification conditions and the relevant phase diagrams. The simulated porcelain firing heat treatment caused a variety of bulk microstructural changes in the coping sections, along with formation of complex subsurface oxidation regions which were less thick for the second-generation alloys. Elemental compositions of the palladium solid solution matrix in the heat-treated alloys were in good agreement with nominal alloy compositions provided by the manufacturers. Ruthenium-rich particles found in the microstructures of three alloys are consistent with a proposed mechanism for grain refinement

X-Ray Diffraction and Scanning Electron Microscopy Analyses of a Gallium-Based Dental Restorative Alloy

Specimens of a gallium-based dental alloy were prepared with different condensation techniques, with and without the removal of a surface layer, and after aging for 2 hours at 50°, 100° and 150°C. X-ray diffraction at times ranging from 10 minutes to 1 day showed the development of the four matrix phases (ß-Sn, CuGa2, Ga28Ag72, and In4Ag9) during the setting reaction. Scanning electron microscope (SEM) examination of specimens loaded to failure revealed brittle fracture, with greater porosity for hand-condensed specimens, and provided insight into crack propagation processes. Aging increased the amount of ß-Sn in freshly prepared specimens, and removal of the Ga-rich surface layer after condensation decreased the amount of this phase. For specimens stored for 5 weeks at room temperature, aging substantially increased the amount of the CuGa2 phase but caused only moderate increases in the amount of ß-Sn

Mechanical Properties of Dendritic Pd-Cu-Ga Dental Alloys

Three Pd-Cu-Ga dental alloys with very similar nominal compositions and dendritic as-cast microstructures were selected for study: Option (Ney Dental) and Spartan (Williams/lvoclar) contain a small amount of boron, while Spartan Plus (Williams/Ivoclar) is boron-free. Bars of each alloy were tested in tension for the as-cast and simulated porcelain-firing conditions, and values of mechanical properties were measured. Fracture surfaces and microstructures of axially sectioned and etched fracture specimens were observed with the scanning electron microscope (SEM). Except for the elastic modulus, significant differences were typically found in alloy properties. Heat treatment eliminated the dendritic microstructure, decreased strength and increased ductility. Values of mechanical properties depend on the presence (orientation and distribution) of dendrites but not boron content. The amounts of casting porosity in the samples were too small to affect their mechanical properties significantly

A Perspective on the Recent Progress in Solution-processed Methods for Highly Efficient Perovskite Solar Cells

Perovskite solar cells (PSCs) were developed in 2009 and have led to a number of significant improvements in clean energy technology. The power conversion efficiency (PCE) of PSCs has increased exponentially and currently stands at 22%. PSCs are transforming photovoltaic (PV) technology, outpacing many established PV technologies through their versatility and roll-to-roll manufacturing compatibility. The viability of low-temperature and solution-processed manufacturing has further improved their viability. This article provides a brief overview of the stoichiometry of perovskite materials, the engineering behind various modes of manufacturing by solution processing methods, and recommendations for future research to achieve large-scale manufacturing of high efficienc

Mindfulness meditation targets transdiagnostic symptoms implicated in stress-related disorders: Understanding relationships between changes in mindfulness, sleep quality, and physical symptoms

Mindfulness-Based Stress Reduction (MBSR) is an 8-week meditation program known to improve anxiety, depression, and psychological well-being. Other health-related effects, such as sleep quality, are less well established, as are the psychological processes associated with therapeutic change. This prospective, observational study (n=213) aimed to determine whether perseverative cognition, indicated by rumination and intrusive thoughts, and emotion regulation, measured by avoidance, thought suppression, emotion suppression, and cognitive reappraisal, partly accounted for the hypothesized relationship between changes in mindfulness and two health-related outcomes: sleep quality and stress-related physical symptoms. As expected, increased mindfulness following the MBSR program was directly correlated with decreased sleep disturbance (r=-0.21, p=0.004) and decreased stress-related physical symptoms (r=-0.38, p<0.001). Partial correlations revealed that pre-post changes in rumination, unwanted intrusive thoughts, thought suppression, experiential avoidance, emotion suppression, and cognitive reappraisal each uniquely accounted for up to 32% of the correlation between the change in mindfulness and change in sleep disturbance and up to 30% of the correlation between the change in mindfulness and change in stress-related physical symptoms. Results suggest that the stress-reducing effects of MBSR are due, in part, to improvements in perseverative cognition and emotion regulation, two “transdiagnostic” mental processes that cut across stress-related disorders

Presentación

La siguiente reunión de textos críticos sobre Vallejo se aproxima así, como toda crítica sobre la obra del autor, a una escritura y un personaje todavía en construcción. La idea surgió  después de un panel dedicado a su poética de la transgresión en la reunión anual de la Modern Language Association en Seattle, Estados Unidos en 2012 y también del reconocimiento de todo el terreno inexplorado por la crítica durante varios años de trabajo con su obra para nuestros proyectos doctorales. Este número especial de Cuadernos de Literatura se publica justo cuando se cumplen veinte años de la publicación de La virgen de los sicarios, la novela que le dio la entrada a Vallejo en el canon y que lo puso a circular en los mercados globales