Benign Agents Research Articles

Resilient distributed optimization for cyber–physical systems under adversarial environments: An event-based method

This work presents a resilient distributed optimization algorithm based on the event-triggering mechanism for cyber–physical systems (CPSs) to optimize an average of convex cost functions corresponding to multiple agents under adversarial environments. Two attack scenarios, including the f-total (each agent is affected by at most f malicious agents in the whole network) and the f-local (each agent is affected by at most f malicious agents in its in-neighbor set) attacks are considered. Subsequently, the convergence conditions under these two attack scenarios are provided, respectively, both of which guarantee that the state values of benign agents converge to a bounded error range. The optimality conditions are also presented by theoretical analysis, which guarantee that the state values of benign agents converge to a safety interval constructed by local optimal values under certain graph conditions, despite the misbehavior of malicious agents. In addition, four numerical examples are presented to show the effectiveness and superiority of the event-triggering resilient distributed optimization (RDO-E) algorithm. Compared to existing resilient algorithms, the proposed method achieves resilient distributed optimization with higher accuracy and less demanding communication overheads. Finally, by applying the proposed method to the multi-microgrid system, a resilient economic dispatch problem (REDP) is successfully solved, which validates the practical viability of the RDO-E algorithm.

Synthesis of aglycones, structure-activity relationships, and mode of action of lycosides as inhibitors of the asexual reproduction of Phytophthora.

Phytophthora are plant pathogens that damage agricultural products. Lycosides (1a-d), found in vegetable juice, have the potential to curb the rapid outbreak and crop damage caused by the asexual reproduction of Phytophthora. Here, aglycones 2a, b with slightly higher activity than lycosides were synthesized as a diastereomeric mixture (mix-2) possessing activity (IC50=4.1 µm) comparable with that of lycosides. The importance of the cyclohexanone structure and side-chain length was demonstrated via structure-activity relationship analysis using synthetic intermediates. In addition, the action mechanism of lycosides was investigated using transcriptome analysis, which revealed a contribution to proline biosynthesis inhibition, a process crucial for the asexual reproduction of Phytophthora. These findings indicate that lycosides (and aglycone) are environmentally benign agents that can be used for protecting agricultural products from Phytophthora pathogens.

Inhibitors of Asexual Reproduction of the Plant Pathogen Phytophthora from Tomato Juice: Structure-Activity Relationships and Transcriptome Analysis.

Phytophthora is a genus of fungus-like microorganisms that damages important crops, such as potatoes and tomatoes. Its asexual reproduction, which results in the production of numerous motile zoospores, is the cause of quick and severe outbreaks and crop damage. The search for substances that selectively inhibit the asexual reproduction of Phytophthora led to the isolation of the known natural products naringenin and flazin from tomato juice. They inhibit the sporangia formation of Phytophthora capsici at IC50 values of 8.8 and 7.2 μM. The study of the structure-activity relationship of 11 flavonoids, including naringenin, demonstrated that genistein was the most active (IC50 = 4.6 μM) and flavonols/flavanonols possessing the 3-hydroxy function showed little activity (IC50 = from 100 to >1000 μM). To demonstrate the mechanism of asexual reproduction inhibition by genistein, transcriptome analysis was carried out, which revealed the downregulation of some genes related to cell differentiation. The results suggest that certain flavonoids are environmentally benign agents that could be used to protect agricultural products from Phytophthora pathogens.

Simultaneous dyeing and multifunctional finishing of natural fabrics with Hibiscus flowers extract

A new sustainable and environmentally benign approach was developed for multifunctional natural fabric/fiber surfaces for healthcare and technical textiles applications. This approach is to explore, identify and evaluate the bioactive compounds extracted from Hibiscus flowers by different solvents as a potential benign agent for multifunctional natural fabrics/fibers via three different designs. In the first design, a novel green route to producing multifunctional cotton gauze fabrics was adopted. In this design, the silver nanoparticles were simultaneously synthesized and deposited on the cotton gauze fabrics through in situ synthesis using silver nitrate and Hibiscus flower extract without further additives. The second design was focused on the application of Hibiscus flower extract for simultaneous coloration and bioactive functionalization of wool fibers. In the third design, cotton fabrics were dyed with Hibiscus flower extract were used to create an eco-friendly, reversible pH sensor. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX) and thermal analysis were used to investigate the chemical and thermal properties of the treated fabrics/fibers. Coloration, sensor properties, and protective properties against pathogenic microorganisms and UV radiation, as well as antioxidant properties, were evaluated in treated fabrics.

Resilient multi-dimensional consensus in adversarial environment

This paper considers the multi-dimensional consensus in networked systems, where some of the agents might be misbehaving (or faulty). Despite the influence of these misbehaviors, the benign agents aim to reach an agreement while avoiding being seriously influenced by the faulty ones. To this end, this paper first considers a general class of consensus algorithms, where each benign agent computes an “auxiliary point” based on the received values and moves its state towards this point. Concerning this generic form, we present conditions for achieving resilient consensus and obtain a lower bound on the exponential convergence rate. Assuming that the number of malicious agents is upper bounded, two specific resilient consensus algorithms are further developed based on the obtained conditions. Particularly, the first solution, based on Helly’s Theorem, achieves the consensus within the convex hull formed by the benign agents’ initial states, where the auxiliary point can be efficiently computed through linear programming. On the other hand, the second algorithm serves as a “built-in” security guarantee for standard average consensus algorithms, in the sense that its performance coincides exactly with that of the standard ones in the absence of faulty nodes while also resisting the serious influence of the misbehaving ones in adversarial environment. Some numerical examples are provided in the end to verify the theoretical results.

New discovery on the nematode activity of aureothin and alloaureothin isolated from endophytic bacteria Streptomyces sp. AE170020

Endophytic bacteria, a rich source of bioactive secondary metabolites, are ideal candidates for environmentally benign agents. In this study, an endophytic strain, Streptomyces sp. AE170020, was isolated and selected for the purification of nematicidal substances based on its high nematicidal activity. Two highly active components, aureothin and alloaureothin, were identified, and their chemical structures were determined using spectroscopic analysis. Both compounds suppressed the growth, reproduction, and behavior of Bursaphelenchus xylophilus. In in vivo experiments, the extracts of strain Streptomyces sp. AE170020 effectively suppressed the development of pine wilt disease in 4-year-old plants of Pinus densiflora. The potency of secondary metabolites isolated from endophytic strains suggests applications in controlling Bursaphelenchus xylophilus and opens an avenue for further research on exploring bioactive substances against the pine wood nematode.

Fall-related Injuries in Older Adults and Medications Prescribed within 30 Days Prior to the Injury

Fall-related injuries in older adults have serious consequences both for individuals and the public health care system. The purpose of this study was to identify medication classes prescribed within 30 days prior to the injury that were associated with fall-related injuries in older adults. This population-based, case-control study used secondary administrative health care data in Ontario, Canada. The cases were older adults, aged 66 years and older, who visited an emergency department for a fall-related injury. Controls were extracted from the Registered Person Database, and matched by same age, sex and residence area. Medication classes prescribed to both groups were recorded and logistic regression was conducted to examine the association between medications and fall-related injury. The case group included 255,270 older adults who experienced a fall-related injury over the five-year period (2010-2014). After adjustment for sex, age group, residence area, income level and number of medications prescribed, psychotropic medications (i.e., opioids, anti-epileptics, anti-Parkinson’s drugs, and antidepressants), drugs for treatment of constipation, infection and benign prostatic hyperplasia, antithrombotic agents, statins and bronchodilators were identified to be related to increased risk of fall-related injuries. In addition to medications already on the list of fall-risk increasing drugs or FRIDs, this study uncovered that drugs for benign prostatic hyperplasia, cephalosporins, biphosphates and bronchodilators increased the risk of fall-related injury in older adults. Well-designed prospective cohort studies considering prescription indication and drug-drug interactions are needed to provide more convincing evidence on medications that may be associated with increased risks of fall-related injury in older adults.

Antifungal Activity and Action Mechanism Study of Coumarins from Cnidium monnieri Fruit and Structurally Related Compounds.

The increasing resistance of plant diseases caused by phytopathogenic fungi highlights the need for highly effective and environmentally benign agents. The antifungal activities of Cnidium monnieri fruit extracts and five isolated compounds as well as structurally related coumarins against five plant pathogenic fungi were evaluated. The acetone extract, which contained the highest amount of five coumarins, showed strongest antifungal activity. Among the coumarin compounds, we found that 4-methoxycoumarin exhibited stronger and broader antifungal activity against five phytopathogenic fungi, and was more potent than osthol. Especially, it could significantly inhibit the growth of Rhizoctonia solani mycelium with an EC50 value of 21 μg mL-1 . Further studies showed that 4-methoxycoumarin affected the structure and function of peroxisomes, inhibited the β-oxidation of fatty acids, decreased the production of ATP and acetyl coenzyme A, and then accumulated ROS by damaging MMP and the mitochondrial function to cause the cell death of R. solani mycelia. 4-Methoxycoumarin presented antifungal efficacy in a concentration- dependent manner in vivo and could be used to prevent the potato black scurf. This study laid the foundation for the future development of 4-methoxycournamin as an alternative and friendly biofungicide.

Resilient output regulation in heterogeneous networked systems under Byzantine agents

In this paper, we consider the problem of output regulation in heterogeneous networked systems. In order to cooperatively achieve the global objective, each agent is required to share information in its neighborhood through communication channels, which might be exposed to malicious cyber attacks. Past work shows that the performance of cooperative control can be seriously affected by network misbehaviors. Inspired by such security concerns, this paper considers the resilient cooperative output regulation (COR) in adversarial environment. Despite the presence of so-called Byzantine agents, the normally behaving ones still aim to achieve the goal of trajectory tracking or disturbance rejection. Towards this end, resilient observers with low computational cost are first developed based on a continuous-time resilient consensus protocol. When the number of Byzantine nodes is locally upper bounded and the network structure satisfies certain robustness properties, the designed observers enable each benign agent to exponentially track the exogenous signal. After that, decentralized controllers are proposed facilitating the achievement of resilient COR in the heterogeneous networks. A numerical example is finally given to illustrate the effectiveness of our approach.

Synthesized oxadiazole derivatives as benign agents for controlling mild steel dissolution: Experimental and theoretical approach

This study explains about the two newly synthesized oxadiazole derivatives, namely 5-benzyl-3-((4-nitrophenylamino) methyl)-1,3,4-oxadiazole-2-(3H)-thione (B4NPAMOT) and 5-benzyl-3-((2-nitrophenylamino) methyl)-1,3,4-oxadiazole-2-(3H)-thione (B2NPAMOT). The corrosion inhibition efficiency of both oxadiazole derivatives tested onto mild steel in 1.0 M hydrochloric acid solution through weight loss measurement, electrochemical impedance spectroscopy, and potentiodynamic polarization techniques. The weight loss measurement was conducted at different concentrations (50 ppm–300 ppm) and varying temperatures 298 K–318 K for immersion periods of 12.0 h. Weight loss results shown that 96.29% and 93.42% was maximized inhibition efficiency by B4NPAMOT and B2NPAMOT respectively at 300 ppm concentration at 298 K. EIS study defined that the charge transfer resistance shifted high at an enhanced concentration of each derivative. Polarization studies revealed a mixed type of inhibition and well obeyed through Langmuir adsorption isotherm by both the derivatives. Surface analysis of the steel sheet performed using a Scanning Electron Microscope (SEM) equipped with electron dispersive X-ray spectroscopy (EDX), respectively. Computational simulation (Fukui functions, DFT and molecular dynamics) was further analyzed to corroborate with the experimental techniques.

Simplification of Natural β-Carboline Alkaloids to Obtain Indole Derivatives as Potent Fungicides against Rice Sheath Blight.

The increasing resistance of rice sheath blight caused by Rhizoctonia solani highlights the need for highly effective and environmentally benign agents. Natural β-carboline alkaloids were simplified to obtain a series of indole derivatives, and their fungicidal activity and preliminary mode of action against R. solani were also evaluated. The initial hit indole (7) displayed significant fungicidal activity with an EC50 value of 25.56 μg/mL, and was selected for further optimization. Importantly, compound 55, the most active compound, had an EC50 value of 0.62 μg/mL, and approximately 300-fold more potent than validamycin A (EC50 = 183.00 μg/mL). In vivo bioassay also demonstrated that compound 55 showed better fungicidal activities than validamycin A. Moreover, the mechanism studies revealed that compound 55 not only caused remarkable morphological and structural alterations of R. solani hyphae, but also induced the loss of mitochondrial membrane potential and interfered with DNA synthesis. Therefore, compound 55 showed superior fungicidal activity against R. solani, and the elucidated mode of action supported the potential application of compound 55 against rice sheath blight.

Debunking Brazilian Exceptionalism in its Africa Relations: Evidence from Angola and Tanzania

ABSTRACT From 2003, President Lula heralded a new dawn in Brazil’s expanding African relations. Brazil was claimed to be unlike other exploitative powers because of its cultural, geographic and historic connections; Africa’s true brother. Despite the passing of two decades and a number of scandals, this narrative of exceptionalism remains. Studies on Brazil–Africa relations tend to focus on the Brazilian state as the key, essentially benign agent. Our analysis uses the case studies of Angola and Tanzania to debunk the idea of Brazilian exceptionalism. We demonstrate the significant, overlooked agency of corporations in shaping and implementing Lula’s Africa Policy, and determining its developmentally dubious outcomes. Additionally, the paper shows how political elites in Africa directed Brazilian government and companies into their political and business norms. Thus, Brazil–Africa relations replicated much of the typical economic patterns of the continent’s trade, with oft-controversial and corrupt investment in commodity extraction and infrastructure.

A “Safe Kernel” Approach for Resilient Multi-Dimensional Consensus

This paper considers the resilient multi-dimensional consensus problem in networked systems, where some of the agents might be malicious (or faulty). We propose a multidimensional consensus algorithm, where at each time step each healthy agent computes a “safe kernel” based on the information from its neighbors, and modifies its own state towards a point inside the kernel. Assuming that the number of malicious agents is locally (or globally) upper bounded, sufficient conditions on the network topology are presented to guarantee that the benign agents exponentially reach an agreement within the convex hull of their initial states, regardless of the actions of the misbehaving ones. It is also revealed that the graph connectivity and robustness required to achieve the resilient consensus increases linearly with respect to the dimension of the agents’ state, indicating the existence of a trade-off between the low communication cost and system security. Numerical examples are provided in the end to validate the theoretical results.

Carbene-based Difluoromethylation of Bisphenols: Application to the Instantaneous Tagging of Bisphenol A in Spiked Soil for Its Detection and Identification by Electron Ionization Gas Chromatography-Mass Spectrometry

The rapid and efficient difluoromethylation of a panel of eleven bisphenols (BPs) for their enhanced detection and identification by Electron-Ionization Gas Chromatography-Mass Spectrometry (EI-GC-MS) is presented. The derivatization employs the inexpensive, environmentally benign agent diethyl (bromodifluoromethyl) phosphonate (DBDFP) as a difluorocarbene-generating species that converts the BPs into bis-difluoromethylated ethers that can be detected and identified by GC-MS means. Key attributes of the protocol include its extreme rapidity (30 seconds) at ambient temperature, high specificity for BPs amidst other alcohol-containing analytes, and its biphasic nature that allows for its convenient adaptation to the analysis of BPs in organic as well as aqueous matrices. The protocol furnishes stable, novel BP ethers armed with a total of four fluorine atoms for their subsequent analysis by EI-GC-MS. Furthermore, each derivatized bisphenol exhibits unique retention times vastly different from their native counterparts leading to their unequivocal identification. The effectiveness and robustness of the developed methodology was applied to the tagging of the most famous member of this family of compounds, bisphenol-A (BPA), when spiked (at 1 μg.g−1 concentration) in the physically and compositionally complex Nebraska EPA standard soil. The method detection limit (MDL) for the bis-difluoromethylated BPA was determined to be 0.01 μg.mL−1. The bis-difluoromethylated BPA was conveniently detected on the organic layers from the biphasic, derivatized mixtures, highlighting the protocol’s practicality and utility in the rapid, qualitative detection of this endocrine disruptor during environmental analysis.

Synthesis of new tetronamides displaying inhibitory activity against bloom-forming cyanobacteria.

The increasing frequency and intensity of cyanobacterial blooms pose a serious threat to aquatic ecosystems. These blooms produce potent toxins that can contaminate drinking water and endanger the life of wild and domestic animals as well as humans. Consequently, the development of effective methods for their control is a matter of high priority. We have previously shown that some γ-benzylidenebutenolides, related to the rubrolide family of natural products, are capable of inhibiting the photosynthetic electron transport chain (Hill reaction), a target of commercial herbicides. Here we report the synthesis and biological properties of a new class of rubrolide-inspired molecules featuring a tetronamide motif. A total of 47N-aryl tetronamides, including 38 aldol adducts, were prepared bearing phenyl, biphenyl, naphthyl, aliphatic and heteroaromatic groups. Some of the aldol adducts were dehydrated to the corresponding γ-benzylidenetetronamides, although satisfactory yields were obtained in only three cases (52-97%). None of the synthesized compounds were capable of blocking the Hill reaction. This notwithstanding, several aldol adducts equipped with a biphenyl substituent displayed excellent inhibitory activity against Synechococcus elongatus and other cyanobacterial strains (IC50 = 1-5μM). Further, these tetronamides were found to be essentially inactive against eukaryotic microorganisms. Several newly synthesized biphenyl-containing tetronamides were shown to display potent and selective inhibitory activity against cyanobacteria. These compounds appear to exert their biological effects without interfering with the Hill reaction. As such, they represent novel leads in the search of environmentally benign agents for controlling cyanobacterial blooms. © 2019 Society of Chemical Industry.

Mosquito Larvicidal Activities and Chemical Compositions of the Essential Oils of Leucas Zeylanica Growing Wild in Vietnam

Dengue fever and dengue hemorrhagic fever are hyperendemic to Vietnam with frequent outbreaks and epidemics. Control of the vectors for dengue viruses, Aedes mosquitoes, is critical to maintain control of this disease. In this work, the essential oil of Leucas zeylanica was examined for larvicidal activity against the Aedes mosquito vector. Leucas zeylanica was collected from three different locations in Vietnam. The essential oil was obtained by hydrodistillation and analyzed by gas chromatography—mass spectrometry. The essential oil from the aerial parts of L. zeylanica was screened for mosquito larvicidal activity against Aedes aegypti and Aedes albopictus. The major components of L. zeylanica essential oil from Vietnam are β-caryophyllene, α-humulene, germacrene D, β-selinene, caryophyllene oxide, 1-tetradecanol, and phytol. Leucas zeylanica essential oil showed good larvicidal activity against both Ae. albopictus and Ae. aegypti with median lethal concentration—LC50 (24 hours) values of 67 and 44 μg/mL, respectively. Thus, L. zeylanica essential oil represents an inexpensive and environmentally benign agent for control of the dengue virus vectors.

Biogenic magnetite nanoparticles: A potent and environmentally benign agent for efficient removal of azo dyes and phenolic contaminants from water.

A comprehensive study was conducted toward the green and facile synthesis of biocompatible magnetite nanoparticles for the efficient removal of organic contaminants from water. The nanoparticles were synthesized using a modified co-precipitation method and functionalized by the taxane diterpenoids extracted from Taxus baccata L., and fully characterized using UV-vis spectroscopy, SEM, FTIR, VSM, and XRD. The synthesized monodisperse magnetite nanoparticles, with a narrow size distribution of less than 50 nm, displayed significant and stable magnetic activity without surface oxidation after several months. The batch experiments clearly indicated the efficient iron-catalyzed removal of Nile blue, methylene blue, methylene orange, and 4-nitrophenol for several cycles without significant loss of catalytic activity. The relevant kinetic data of the dyes removal reactions were fitted to a pseudo-first order model. Moreover, in vitro MTT assay revealed high biocompatibility of the nanoparticles with no significant toxicity on different human cell lines. The overall results indicated high potential of green synthesized, biocompatible magnetite nanoparticles for the environmental applications especially wastewater remediation.

Isolation of Antagonistic Endophytes from Banana Roots against Meloidogyne javanica and Their Effects on Soil Nematode Community.

Banana production is seriously hindered by Meloidogyne spp. all over the world. Endophytes are ideal candidates compared to pesticides as an environmentally benign agent. In the present study, endophytes isolated from banana roots infected by Meloidogyne spp. with different disease levels were tested in vitro, and in sterile and nature banana monoculture soils against Meloidogyne javanica. The proportion of antagonistic endophytes were higher in the roots of middle and high disease levels. Among those, bacteria were dominant, and Pseudomonas spp., Bacillus spp. and Streptomyces spp. showed more abundant populations. One strain, named as SA, with definite root inner-colonization ability was isolated and identified as Streptomyces sp. This strain showed an inhibiting rate of >50% in vitro and biocontrol efficiency of 70.7% in sterile soil against Meloidogyne javanica, compared to the control. Greenhouse experiment results showed that the strain SA exhibits excellent biological control ability for plant-parasites both in roots and in root-knot nematode infested soil. SA treatment showed a higher number of bacterivores, especially Mesorhabditis and Cephalobus. The maturity index was significantly lower, while enrichment index (EI) was significantly higher in the SA treatment. In conclusion, this study presents an important potential application of the endophytic strain Streptomyces sp. for the control of plant-parasitic nematodes, especially Meloidogyne javanica, and presents the effects on the associated variation of the nematode community.

A Paradigm Shift in Glioblastoma Treatment and Research: A Multi-mechanistic, Multi-agent Approach to Target Glioblastoma Multiforme

The majority of patients with glioblastoma multiforme (GBM) suffer dismal outcomes. Adopting a broader, multi-mechanistic, multi-agent approach targeting GBM using readily available and fairly benign agents in combination with standard therapy may improve outcomes. Such agents include fluoxetine, fenofibrate, cimetidine, citrulline, valacyclovir, 1,3 1-6 beta glucan, and tadalafil, among others. In the context of in vitro and animal studies, these agents appear to target GBM cells and modify the tumor microenvironment. The current approach to GBM treatment focuses on limited molecular attributes of the condition. The following article highlights the relevance of the aforementioned agents in GBM treatment and proposes a multi-mechanistic, multi-agent paradigm shift, addressing a broader range of molecular attributes in the quest to improve patient outcomes.

SC06.03 Intraoperative Therapies in Malignant Pleural Mesothelioma

SC06.03 Intraoperative Therapies in Malignant Pleural Mesothelioma