scholarly journals The Use of Aerated Steam as a Heat Treatment for Managing Angular Leaf Spot in Strawberry Nursery Production and Its Effect on Plant Yield

2020 ◽  
pp. PHYTOFR-08-20-0
Author(s):  
William W. Turechek ◽  
Ole Myhrene ◽  
Janet Slovin ◽  
Natalia A. Peres

Xanthomonas fragariae, the bacterium causing angular leaf spot (ALS) of strawberry, is found routinely on strawberry nursery stock. Although ALS can be a serious disease in production fields, it can be particularly problematic in the sale and trade of commercial nursery stock because of international trade regulations. Heat treatment has been shown to be an effective treatment for managing ALS on nursery stock in small-scale experimental trials. The objective of this research was to design, build, and trial precision thermotherapy units for managing ALS for both research and commercial applications and to test a new thermotherapeutic protocol on strawberry nursery stock that combines a conditioning thermal treatment with an eradicative thermal treatment. Small-plot trials were conducted to evaluate the efficacy of precision thermotherapy on control of ALS using known sources of infected nursery stock. Additionally, trials were conducted in cooperation with commercial nurseries to determine the impact of thermotherapy on plant health and yield and on the natural development of ALS. In the small-plot trials, ALS incidence was significantly lower in plots treated with precision thermotherapy. In the commercial trials, precision thermotherapy had a variable, but negligible, effect on plant growth and yield. ALS, when it occurred, was always lower in thermotherapy-treated plots. Heat is a near-universal biocide. Thus, in addition to managing ALS, the commercial application of precision thermal therapy to strawberry nursery stock may be effective for managing a wide range of pest and disease threats to strawberry while simultaneously reducing pesticide usage. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CCO “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.

Plant Disease ◽  
2009 ◽  
Vol 93 (3) ◽  
pp. 299-308 ◽  
Author(s):  
William W. Turechek ◽  
Natalia A. Peres

Angular leaf spot is an important disease in strawberry nursery production. The European and Mediterranean Plant Protection Organization (EPPO) lists Xanthomonas fragariae as an A2 quarantine pathogen. Therefore, nurseries wishing to export plants to European countries must maintain phytosanitary standards to exclude X. fragariae. To help nurseries achieve these standards, heat treatment for killing or reducing the number of viable bacterial cells in strawberry crown tissue was investigated. First, the sensitivity of bacteria to heat was determined by dispensing 1-ml aliquots of standardized cell suspensions in microcentrifuge tubes for each of four isolates of X. fragariae, including the type culture, and submerging the tubes in water at 36, 40, 44, 48, 52, and 56°C for 0, 1, 2.5, 5, 10, 15, 30, 60, 120, 240, 360, and 480 min. Bacteria were transferred to growth medium to determine the proportion surviving heat treatment. Two trials were conducted in a greenhouse to determine the sensitivity of bare-root plants to heat treatment. In the first trial, plants of cvs. Camarosa and Diamante from two different nurseries were heat treated as follows: (i) plants placed in metallic mesh cages and immersed directly into water (industry standard, direct dip); (ii) plants sealed in a plastic bag and the bag immersed in water (bagged dry); or (iii) plants wetted in warm water, sealed in a plastic bag, and then immersed in water (bagged wet). Plants were treated at 44 or 48°C for 0, 60, 120, 180, and 240 min. In the second trial, plants of cvs. Camarosa, Camino Real, Diamante, Oso Grande, Strawberry Festival, and Ventana from a single nursery were subjected to the same treatments. In both trials, plants were potted after treatment and rated for growth characteristics. Results showed that populations of bacteria exposed to 56 and 52°C were killed completely after 15 and 60 min of exposure, respectively; both treatments killed plants. Bacterial populations exposed to 44°C for 4 h or 48°C for 2 h were reduced by 105 or 106 CFU/ml. The same treatments minimally affected vegetative growth of plants bagged dry or wet, but flowering was adversely affected. These heat treatments were selected for testing of nursery stock of several cultivars in field trials established at two locations in successive years. The survival rate among cultivars was similar to that observed in greenhouse trials, and angular leaf spot developed appreciably only in non-heat-treated control plots. Heat treatment of strawberry nursery stock is feasible and can be used to supplement standard production practices for producing pathogen-free nursery stock.


2018 ◽  
Vol 76 (4) ◽  
pp. 1122-1130 ◽  
Author(s):  
Lotta Clara Kluger ◽  
Sophia Kochalski ◽  
Arturo Aguirre-Velarde ◽  
Ivonne Vivar ◽  
Matthias Wolff

Abstract In February and March 2017, a coastal El Niño caused extraordinary heavy rains and a rise in water temperatures along the coast of northern Peru. In this work, we document the impacts of this phenomenon on the artisanal fisheries and the scallop aquaculture sector, both of which represent important socio-economic activities for the province of Sechura. Despite the perceived absence of effective disaster management and rehabilitation policies, resource users opted for a wide range of different adaptation strategies and are currently striving towards recovery. One year after the event, the artisanal fisheries fleet has returned to operating almost on a normal scale, while the aquaculture sector is still drastically impacted, with many people continuing to work in different economic sectors and even in other regions of the country. Recovery of the social-ecological system of Sechura likely depends on the occurrence of scallop seed and the financial capacity of small-scale producers to reinitiate scallop cultures. Long-term consequences of this coastal El Niño are yet to be studied, though the need to develop trans-local and trans-sectoral management strategies for coping with disturbance events of this scale is emphasized.


2019 ◽  
Vol 56 (1) ◽  
pp. 261-270
Author(s):  
Maria Stoicanescu ◽  
Aurel Crisan ◽  
Ioan Milosan ◽  
Mihai Alin Pop ◽  
Jose Rodriguez Garcia ◽  
...  

This paper presents and discusses research conducted with the purpose of developing the use of solar energy in the heat treatment of steels. For this, a vertical axis solar furnace called at Plataforma Solar de Almeria was adapted such as to allow control of the heating and cooling processes of samples made from 1.1730 steel. Thus temperature variation in pre-set points of the heated samples could be monitored in correlation with the working parameters: the level of solar radiation and implicitly the energy used the conditions of sample exposed to solar radiation, and the various protections and cooling mediums.The recorded data allowed establishing the types of treatments applied for certain working conditions. The distribution of hardness, as the representative feature resulting from heat treatment, was analysed on all sides of the treated samples. In correlation with the time-temperature-transformation diagram of 1.1730 steel, the measured values confirmed the possibility of using solar energy in all types of heat treatment applied to this steel. In parallel the efficiency of using solar energy was analysed in comparison to the energy obtained by burning methane gas for the heat treatment for the same set of samples. The analysis considered energy consumption, productivity and the impact on the environment. Thanks to various data obtained through developed experiences, which cover a wide range of thermic treatments applied steels 1.1730 model, we can certainly state that this can be a solid base in using solar energy in applications of thermic treatment at a high industrial level.


2015 ◽  
Vol 60 (3) ◽  
pp. 1825-1832 ◽  
Author(s):  
K. Żaba ◽  
M. Nowosielski ◽  
P. Kita ◽  
M. Kwiatkowski ◽  
T. Tokarski ◽  
...  

AbstractThe paper presents the results of corrosion resistance of heat treated aluminized steel strips. Products coated by Al-10Si alloy are used among others in a manufacturing process of welded pipes as the elements of the car exhaust systems, working in high temperatures and different environments (eg. wet, salty). The strips and tubes high performance requirements are applied to stability, thickness and roughness of Al-Si coating, adhesion and corrosion resistance. Tubes working in elements of exhaust systems in a wide range of temperatures are exposed to the effects of many aggressive factors, such as salty snow mud. It was therefore decided to carry out research on the impact of corrosion on the environmental influence on heat treated aluminized steel strips. The heat treatment was carried out temperatures in the range 250-700°C for 30, 180, 1440 minutes. Then the coatings was subjected to cyclic impact of snow mud. Total duration of treatment was 12 months and it was divided into three stages of four months and at the end of each stage was made the assessment of factor of corrosion. The results are presented in the form of macroscopic, microscopic (using a scanning electron microscope) observations and the degree and type of rusty coating.


Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 107 ◽  
Author(s):  
Maciej Nikodem ◽  
Marek Bawiec

This paper addresses the efficiency of Bluetooth Low Energy (BLE) communication in a network composed of a large number of tags that transmit information to a single hub using advertisement mode. Theoretical results show that the use of advertisements enables hundreds and thousands of BLE devices to coexist in the same area and at the same time effectively transmit messages. Together with other properties (low power consumption, medium communication range, capability to detect a signal’s angle-of-arrival, etc.), this makes BLE a competing technology for the Internet of Things (IoT) applications. However, as the number of communicating devices increases, the advertisement collision intensifies and the communication performance of BLE drops. This phenomena was so far analyzed theoretically, in simulations and in small-scale experiments, but large-scale experiments are not presented in the literature. This paper complements previous results and presents an experimental evaluation of a real IoT-use case, which is the deployment of over 200 tags communicating using advertisements. We evaluate the impact of the number of advertisements on the effective data reception rate and throughput. Despite the advertisement collision rate in our experiment varying between 0.22 and 0.33, we show that BLE, thanks to the multiple transmission of advertisements, can still ensure acceptable data reception rates and fulfill the requirements of a wide range of IoT applications.


2006 ◽  
Vol 54 (5) ◽  
pp. 59-68 ◽  
Author(s):  
E. Paul ◽  
P. Camacho ◽  
D. Lefebvre ◽  
P. Ginestet

Thermal treatment applied in association with a biological system allows for a significant reduction in excess sludge production (∼50%). In general, heat treatment is described as a sludge disintegration technique. This paper offers a thorough study on the impact of heat treatment, at temperatures below 100 °C, on the solubilisation of the sludge COD and its biodegradability. Discontinuous heating experiments were performed on activated and digested sludge. At all temperatures tested the released COD for digested sludge was systematically higher than that for activated sludge (15 and 40%, respectively, at 95 °C for 40 min of contact time). For the first 30 min, a 1st order kinetic, with respect to the residual COD, was systematically found. In the range of 40–95 °C, digested sludge had a lower activation energy than activated sludge (26 kcal/mol compared to 70–160 kcal/mol). COD solubilisation is thus more positively influenced by temperature in the case of activated sludge. This may be due to the significant difference in the ratio of protein/carbohydrate in digested and activated sludge (1–5 and 0.2–0.7, respectively). The increase in the COD/TKN ratio in the solubilised fraction after thermal treatment of activated sludge suggests a preferential solubilisation of proteins over carbohydrates. Respirometric tests performed on the solubilised COD showed that whatever the sludge origin, only 40–50% of released COD is biodegradable at a conventional hydraulic retention time (i.e. 24 h). Hence, heat treatment would act more through organic matter solubilisation rather than by a biodegradability increase.


2018 ◽  
Vol 12 (1) ◽  
pp. 151-170
Author(s):  
Hannah Vandegrift Eldridge

Abstract In recent years, theories of rhythm have been proposed by a number of different disciplines, including historical poetics, generative metrics, cognitive literary studies, and evolutionary aesthetics. The wide range of fields indicates the transdisciplinary nature of rhythm as a phenomenon, as well as its complexity, highlighting the degree to which many of the central questions surrounding rhythm remain extraordinarily difficult even to state in terms that can traverse the disciplinary boundaries effortlessly transgressed by rhythm as a phenomenon. In particular, any theory of rhythm, whether in music, dance, sociology, or language, must grapple with two quandaries. First, the precise site of rhythm remains opaque: rhythms occur in, affect, and are produced by all of bodies, cultures, and universals (whether metaphysical or species-physiological). What is the relation between species-wide characteristic, individual body, cultural context, and the history of art making in the experience of rhythm? Second, rhythm is simultaneously a phenomenon of fixed, organizing form and one of dynamic, changing flow. How can rhythm encompass both the measurement of regular recurrences across time and the organizing of temporal phenomena as they unfold? In this article, I draw on Emile Benveniste and Henri Meschonnic to elucidate these quandaries or conflicts before turning to Friedrich Nietzsche’s work on rhythm. I argue that Nietzsche’s work with rhythm provides a historically situated model for how we might continue to take the questions and conflicts within rhythm seriously, rather than privileging an abstract and universally applicable theory of rhythm. This model is especially crucial for our own historical moment, when cultural-political emphasis on science and technology at the expense of aesthetics devalues all insights not presented in the form of countable data points or empirically testable facts. Nietzsche is, of course, one of the great critics of positivist-scientistic epistemologies, part of a long tradition questioning the naturalness of natural-scientific paradigms and alerting us to the metaphors at play even in the ›hard sciences‹. I use rhythm as one paradigmatic place to resist the importation of scientistic thought into discussions of language, literature, and culture. I show how Nietzsche’s writings on rhythm prove illuminating for contemporary understandings of rhythm because the tensions in his work are shaped by the quandaries inherent to rhythm that I have used Benveniste and Meschonnic to elaborate, namely the question of rhythm’s site as individual, cultural, or universal, and the conflict between rhythm as form and as flow. The question of the site of rhythm appears in Nietzsche’s discussions of Greek and Latin meters both in his philological works, in his aphorisms, and in his letters: on the one hand, he argues that Greek and Latin metrical and rhythmic resources are irrevocably lost to modern cultures (indicating that rhythm is a product of culture), while on the other, he emphasizes the impact of rhythm on the body and offers advice for replicating Ancient metrical and rhythmic techniques (suggesting that rhythm is based on physiological universals). And the conflict between flow and form appears as Nietzsche praises both the productive constraint created by large-scale, architectonic, or macro-formal rhythms and the freedom from such constraint enabled by small-scale, leitmotiv-based, or micro-formal rhythms. The conflicts in Nietzsche’s work between the loss and recovery of Ancient rhythms and between rhythm as small scale freedom vs. large scale constraint thus represent one particular unfolding of the dilemmas for rhythmical theory worked out by Benveniste and Meschonnic. The various modern disciplines engaged with rhythm will answer different sets of these questions in different ways. Most practitioners of, e. g., evolutionary aesthetics, neuroaesthetics, or cognitive poetics would no doubt contend that they are using the tools of the natural sciences to investigate long-standing humanistic inquiries. Nietzsche, as a critic of his own era’s scientific positivism who allows tensions inherent in these questions to remain open in his own work, is an ideal interlocutor with whom to ask whether even the adoption of these tools ends up placing excessive faith in natural-scientific paradigms and undercutting other—affective, bodily, metaphorical, poetic, etc.—ways of knowing, as I demonstrate briefly in the examples of evolutionary aesthetics and generative metrics. Because Nietzsche leaves open the conflicts over rhythm’s site and its qualities as form or flow, he can use individual bodily experience to make physiological arguments about the effects of rhythm on culture and vice versa: Nietzsche takes his bodily response to be an index of cultural values inherent to rhythmical practices. The particular values that Nietzsche critiques shift across his career—early on he condemns German musical and poetic rhythms for being too rigid, while later he sees them as pathologically heightening affect and emotion. In both cases, detrimental rhythmic practices lead to detrimental bodily practices and to the degeneration of culture, while rhythmic practices work as a bodily and cultural corrective. In his critiques of German forms and praises of Greek forms, and in the moments in which he brings them together, Nietzsche thus asserts the complex interrelation of culture, body, and history.


Aerospace ◽  
2021 ◽  
Vol 8 (9) ◽  
pp. 255
Author(s):  
Naser Al Haddabi ◽  
Konstantinos Kontis ◽  
Hossein Zare-Behtash

Cavity flows occur in a wide range of low-speed applications (Mach number ≤0.3), such as aircraft wheel wells, ground transportation, and pipelines. In the current study, a steady jet is forced from a cavity leading edge at different momentum fluxes (0.11 kg/ms2, 0.44 kg/m·s2, and 0.96 kg/m·s2). The investigation was performed for an open cavity with length to depth ratio of 4 at the Reynolds number based on a cavity depth of approximately 50,000. Particle image velocimetry, surface oil flow visualisation, constant temperature anemometry, and pressure measurements were performed in this investigation. The aim of the jet blowing is to separate the cavity separated shear layer from the recirculation zone to reduce the cavity return flow, and hence stabilise the cavity separated shear layer. It was found that increasing the jet momentum flux causes an increase in the cavity return flow due to the increase in the thickness of the cavity separated shear layer. The study also found that the jet populates the separated shear layer with a large number of small-scale disturbances. These disturbances increase the broad band level of the pressure power spectra and Reynolds shear stress in the cavity separated shear layer. On the other hand, the jet disturbances make the shedding of the large vortical structures more intermittent.


1981 ◽  
Vol 24 (2) ◽  
pp. 22-40 ◽  
Author(s):  
Ray Bromley

The beggar-donor relationship raises a wide range of social and moral issues, and the study of begging can provide an interesting perspective on social structure and the impact of social welfare policies. This article discusses these issues by analyzing the practice of begging in the city of Cali, Colombia, by reviewing the portrayals of begging in the local press, by presenting six case studies of individual beggars, and by discussing the roles and functioning of the various social welfare institutions which receive beggars. The numerical significance and level of organization of begging are usually exaggerated in the local press and other communications media, and the sensationalized popular image of begging is used to justify repressive policies towards beggars. Contrary to such images, begging is shown to be relatively small-scale and atomistic, and beggars are generally severely disadvantaged and usually have very low incomes. The institutional res ponse to beggars' problems is very inadequate, with a strong concentration on simply 'storing' people to keep them off the streets, rather than on any effective preventative or rehabilitative measures. The idea, prevalent among Cali's elites, that 'begging is a serious problem' is criticized. The problem is not begging, but rather the poverty, extreme inequality and inadequate social provision of which begging is merely one of many superficial manifestations.


Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.


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