Roots were removed and the fresh weight of the individual shoot vegetation was measured. Basil is commercially important both as fresh and dry and hence both weights were measured and presented. After weighing, cut portions were dried in a Fisher Scientific Isotemp Standard Lab Oven at 60 C for 96 h. Fresh and dry weights of individual basil plants were used to calculate the fresh and dry crop yield.Nowadays, cyber-physical systems are drawn the attention within the industry, society and government, due to the enormous impact they have on the economy and the environment,and providing citizens and businesses with a wide range of innovative applications and services. The entry of the CPS in the industry allows high connectivity between the industrial systems and brought great advantages and a wide range of new opportunities to industries but also some questions and problems, such as those related to safety and security. Cyber security is a fundamental discipline that provides confidence in terms that CPS, their information, and supporting communications and information infrastructures are adequately safeguarded.
CPS have many unique characteristics,ebb flow including the need for real-time response and extremely high availability, predictability, and reliability, which impacts cyber security decisions. Besides, an even more critical problem is that the development of these systems has been carried out without taking into account the security aspects, nor the new risks that this automation of processes implies, which put at risk the complete industrial infrastructure,and where any security breaches to these systems could have catastrophic consequences. Taking into account the security from the earliest steps of CPS, i.e., at the design time is crucial to avoid security issues, even though it is a very challenging task. Therefore, security within industrial environments becomes a critical aspect that must be taken into account at all stages of information system development, by obtaining and defining, from early analysis and security requirements before the system is in place. Security and safety are nonetheless two key properties of CPS and they share the same goal, protecting CPS from failures. Security and safety refer to different but very important properties,in this paper just focus on those related to security properties for the CPS.Although security requirements are the appropriate solution for many researchers, they are difficult to obtain, analyse and manage by their subjective nature and their description in natural language. For CPS, in addition to software security requirements, we also have physical, control and communication requirements, which make the task of identifying security requirements and translating them into the design of our CPS system even more complicated.
Therefore, having a common model is essential, since it facilitates the definition of security requirements for CPS where any particularity of all these elements is taken into account. The high variability of the components involved in a CPS and their possible configurations make it extremely difficult to verify the correctness of the security requirements that reduce the threats and the possible risks. To manage this complexity, we propose the use of Feature Models and a set of reasoning techniques to verify the correctness of the security requirements and diagnose misconfiguration of the features,according to a catalogue of possible correct configurations. FMs have been previously used for checking security configurations,and the diagnosis of FM configurations is a studied problem by the community. However, how it can be adapted to the specific scenario of CPS is still an open challenge tackled in this paper. Based on the problems identified, we have developed a CARMEN framework that presents a systematic process to enable from the description of security requirements to the verification and diagnosis for CPS through variability models. CARMEN is focused on the design phase of CPS by presenting a support system for guiding the whole security requirement life-cycle: creating a meta model which enables the definition of security requirements for CPS based on security recommendations of ENISA and OWASP guidelines; load and update a variability model that encompassed the catalogue of possible correct configurations for CPS; map both security requirements and variability model resulting in a configuration; verify the correctness of the configuration, and; if it is not correct, the diagnosis of the configuration to modify for achieving a correct configuration according to requirements.
To explain in detail each of these steps, the paper has been organised as follows: Section 2 reviews the most relevant papers in the area. Section 3 details a case study based on Agriculture 4.0 and introduces the possible cyber-risks to which this type of systems are subject. Section 4 presents the proposed framework for the diagnosis of this type of system. Section 5 applies the proposed framework to the case study to show its applicability; and, finally, conclusions are drawn, and future work is outlined in Section 6.Feature-Oriented Domain Analysis have become mature fields in the Software Product Line arena in the last decades. Several are the scenarios where SPLs based on feature model analysis have been applied,and different researchers highlight the advantages of these systems since the use of Model-Driven Engineering methodology and the SPL paradigm is becoming increasingly important. The complexity and the high variability of a CPS, and how SPL can help were analysed in Arrieta et al. and Beek et al.,detecting the points of variability using feature model analysis. The analysis of the variability of CPS can also support the testing. Security is an understudied field in SPL area. Different approaches have been presented to manage the variability and specify security requirements from the early stages of the product line development. Similarly, other approaches addressed the idea of including the security variability into an SPL. In Fægri and Hallsteinsen,the authors established a software architecture as a reference to develop SPL, dealing with information security aspects. SPLs are currently being targeted for application in CPS, as for some researchers, no standard provides a structured co-engineering process to facilitate the communication between security engineers.
For other researchers, information security must be a top priority when engineering C-CPS as the engineering artefacts represent assets of high value, and the research is focused on the generation of new security requirements stemming from risks introduced by CPS. On the other hand, there are approaches focused on security as a use case, such as in Arciniegas et al. and the methodology SecPL,where is highlighted the importance of specifying the security requirements and product-line variability. These are annotated in the design model of any system. Other researchers developed a security requirements engineering framework for CPS, which is an extension of SREP. The capacity to support the high variability in the security context though Feature Models appeared in previous papers,where the authors analysed which vulnerabilities could be used to simulate attack-defence scenarios, but these simulations were not oriented towards more complex scenarios, such as cyberphysical systems.As seen in the introduction, nowadays CPS require an adequate security configuration. Therefore, some researchers are focused on the development of ontologies and security requirements. Some researchers have developed security tools based on ontologies capable of being integrated with the initial stages of the development process of critical systems. On the other hand, requirements have been analysed not only from the software side but also from the hardware perspective, including sensors and network security. Therefore they propose the development of a security requirements framework for CPS, analysing the existing ones, and concluding that currently there is no suitable requirement framework for this type of systems. Other researchers consider that CPS have unique characteristics that limit the applicability and suitability of traditional cyber security techniques and strategies, and therefore propose the development of a methodology of cyber security requirements oriented towards weapons systems. This methodology allows us to discover solutions that improve dimensions,being possible to use automated coding tools.
Therefore, we can conclude that at present different researchers have found the need to develop requirement grammars to control the security risks associated with CPS. Moreover, derived from the complexity of the CPS, feature models have been previously used in the context of security.The earth is facing the risks of increasing soil pollution caused by heavy metals, which is particularly critical for humans as pollution concentrates on farm land where food is produced. Among the heavy metals, cadmium is generally considered more detrimental than others in terms of toxicity and mutagenic effects on plants and humans. Cadmium has a similar structure to several essential elements, such as iron, manganese, and zinc, and it can enter the plant rely on the transporters of these elements; therefore, it can be transferred to all living organisms through the food chain, which raises concerns over risks on public health. Although some plant species, called hyper accumulators, greenhouse benches can accumulate exceptionally high amounts of Cd without obvious damage symptoms,most crops, including horticultural crops, are sensitive to Cd. The mechanisms of Cd toxicity in horticultural crops, as well as prevention of Cd accumulation in shoot tissues, have been frequently explored. Cd is absorbed from the environment into plants mainly by the roots and transported through the xylem to the plant shoots, where it can be distributed to various plant tissues. Oxidative damage is a typical symptom caused by Cd toxicity in plants. The Cd indirectly induced reactive oxygen species can react with lipids and proteins, leading to lipid peroxidation and membrane damage. Cd accumulation also alters chloroplast ultra structure and inhibits the electron transport chain, resulting in decreased chlorophyll content and reduced photosynthetic rate. An efficient way to improve plant Cd tolerance is to minimize root-to-shoot Cd2+ transportation or lower the Cd2+ concentration in the cytoplasm.
Several metal transporters on the root epidermal cell membrane relating to Cd transportation into root cells have been reported. For example, the gene encoding a natural resistance-associated macrophage protein 5 is mainly expressed in the rice root epidermal cells, which is an important plasma membrane-localized transporter for Cd2+. When Cd enters the root cells, it can be chelated or precipitated by specific small molecules, such as metallothionein,in the plant cytoplasm and transported to the vacuole, thereby reducing Cd2+ toxicity. Furthermore, the plant uses its antioxidant defense system to protect itself from Cd-induced oxidative damage. For example, the antioxidant enzymes in plants, such as superoxide dismutase,catalase,ascorbate peroxidase,and glutathione reductase,scavenge ROS through increased activity to maintain proper cellular ROS levels under Cd stress. Due to the high mobility nature in plant tissues, Cd can replace Fe from proteins and disturb nitrogen and sulfur metabolism. Nitrogen metabolism is central to the plant response to heavy metals and plays a vital role in Cd tolerance. Cd stress in plants can disrupt amino acids metabolism, as manifested by the accumulation of several specific free amino acids that are beneficial for Cd tolerance. For example, previous study found that proline accumulated in plants under Cd stress, which was conducive to the of ROS elimination and functioned as a protein compatible solute. Furthermore, the amino acids have been confirmed to serve as signaling molecules and affect synthesis and activity of some enzymes, which play an important role in maintaining plant cell metabolism and stability. Several studies indicated that amino acids rich in carboxyl, amino, thiol, and phenolic groups are crucial for metal detoxification due to their ability to form complex metal cations to decrease their toxicity. Autophagy, a highly conserved mechanism in plant cells, targets the cellular components for degradation in the vacuole by the resident hydrolytic enzymes. This recycling system involves the degradation of cytoplasmic proteins and organelles, promoting the maintenance of nutrient remobilization and other metabolic processes. Studies have demonstrated that autophagy can be induced during abiotic stress; meanwhile, it plays an essential role in plant tolerance to various abiotic stresses, such as heat,salt,and drought. Studies on the function of autophagy-related genes against Cd toxicity in animals are relatively clear, but lacking in plants. Previous studies provided evidence for autophagy induction in plant cells under Cd stress. However, the specific mechanisms of autophagy in the Cd tolerance of plants have yet to be explored. Here, three MdATG10-overexpressing apple lines were used to understand the involvement of autophagy in plant Cd tolerance. Results showed that MdATG10 over-expression enhanced the autophagic activity and improved the tolerance of apple plants in response to Cd stress.