Contact Action Research Articles

Composite Materials with the Coating to Detect Barely Visible Impact Based on the Retroreflective Film

A new method of indicating contact damage of composite materials, using a polymer retroreflective film (PRF) with micro-prisms, is proposed. Impact contact action leads to deformation of microprisms and with directed lighting allows seeing the place of impact in the form of a dark spot. In experimental studies, using STEF fibreglass as an example, the dependences of the spot diameter on the contact pressure up to 530 MPa were studied. An assessment of the residual strength and stiffness of a composite specimen-beam with a contact defect was obtained with three-point bending. It is shown that, during bending, the strength of STEF with contact defects decreases from 615 to 386 MPa. The data obtained allow to assess the danger of contact pressure by the known diameter of the dark spot on the PRF.

Enhancement of engineering models for simulation of soft, and hard projectile impact on reinforced concrete structures

Protective Reinforced Concrete (RC) barrier walls of nuclear or industrial facilities are required to withstand accidental or intentional missile impact. The missiles (projectiles) can be classified as hard, semi-hard or soft. In particular, an airplane crash on a reinforced concrete structure causes local and global damage to the structure. Local damage mechanisms are usually associated with the impact of hard aircraft components such as engine shafts and wing boxes. In the event of a hard impact, the contact actions and target reactions are strongly coupled and therefore the calculation of capacity and damage effects is very sophisticated.There are various analysis methods for modelling both, hard and soft impacts. In this regard, empirical and semi-empirical models can be considered to calculate the load-bearing capacity in a simplified way with a few input parameters. However, validated numerical Finite Element (FE) simulation models allow further investigation on damage mechanism as well as detailed evaluation of stresses and strains in concrete and reinforcement.Hence, this paper investigates the efficiency of the existing analytical approaches as well as numerical simulation methods in predicting the load-bearing capacity of rc structures under hard and soft impact loads. Moreover, a novel simplified mechanical analytical method is proposed concerning hard impact loads. The mechanical principles are based on a nonlinear two degree of freedom (TDOF) system by Schlüter (Schlüter, 1987), which was extended for applications on hard impact scenarios considering the interaction between the impacting projectile and the rc target as well as penetration process of the projectile. FE-simulations and experimental test results of recent and ongoing research projects are presented and have been used for validation purposes and investigations.

Sasaki–Ricci Flow and Deformations of Contact Action–Angle Coordinates on Spaces T1,1 and Yp,q

In this paper, we are concerned with completely integrable Hamiltonian systems and generalized action–angle coordinates in the setting of contact geometry. We investigate the deformations of the Sasaki–Einstein structures, keeping the Reeb vector field fixed, but changing the contact form. We examine the modifications of the action–angle coordinates by the Sasaki–Ricci flow. We then pass to the particular cases of the contact structures of the five-dimensional Sasaki–Einstein manifolds T1,1 and Yp,q.

Thin Indicator Films to Assess the Residual Strength of a GFRP after a Local Contact Action

Thin Indicator Films to Assess the Residual Strength of a GFRP after a Local Contact Action

Patient tracking during treatment of children with cancer in India - An exploratory study.

BackgroundAbandonment of treatment, a major cause of treatment failure in low‐ and middle‐income countries like India, is particularly high during the diagnostic and initial phase of treatment. Tracking of patients during this risk period may reduce treatment abandonment rates and increase quality of care.AimThe primary aim was to pilot the use and check the acceptability of a tool for tracking children with cancer in New Delhi during the initial part of their treatment. Secondary aim was to estimate abandonment rates among these patients.MethodsThis prospective study was carried out in two centers of North India in New Delhi and enrolled children less than 18 years diagnosed with cancer at these centers and who had registered with Cankids for social support. Parent support group (PSG) workers maintained contact with the child's family at least once a week for the first 12 weeks. Details of each contact and subsequent action were recorded in a customized book (called “You are not alone” or YANA Book). Descriptive analysis of these contacts was done in Microsoft Excel and presented in frequencies and percentages. The five‐point Likert scale was used to check the acceptability of the tool among the PSG workers.ResultsSeven PSG workers enrolled and tracked 81 patients (73% male with a median age of 6 years). During the 12‐week study period, 986 contacts were attempted and three (3.7%) patients had abandoned their treatment. All PSG workers strongly agreed that the YANA book was simple to understand and use, decreased their workload, and helped provide better assistance to patients.ConclusionThe tool for patient tracking was well accepted by the PSG workers and considered easy to use. We now plan to implement our model as a routine service at all the partnering hospitals in India.

Nanochitin whisker enhances insecticidal activity of chemical pesticide for pest insect control and toxicity

BackgroundNanomaterials in plant protection promise many benefits over conventional pesticide products. Nano-enabled pesticides may alter the functionality or risk profile of active ingredients. Cationic nanochitin whiskers (NC) possess strong biological activity against wheat aphids. However, toxicity and synergistic effects of NC with chemical pesticides against pest insects has not been systemically reported. This study investigated the insecticidal enhancement by NC with Omethoate (40% EC), Imidacloprid (10% WP), and Acetamiprid (40% WG) for pest control using wheat aphid as piercing-sucking mouthparts insect. Fluorescein isothiocyanate labelled NC was used to monitor the uptake and transportation pathway of NC inside the target insects. Toxicity of NC was tested with Sprague-Dawley (SD) rat. Our findings provide a theoretical basis for future application of NC in plant protection against pest insects.ResultsNCs synthesized by acidic hydrolysis were rod-like nanoparticles in a range of 50–150 nm in length and 30–50 nm in width, which examined by electron microscopy and dynamic light scattering methods. The charge density and zeta potential were about 63 mmol/kg and + 36.4 mV, respectively. By absorption and/or contact action of 30–50 mg/L of NC suspension, the corrected mortality of wheat aphids reached up to 80% or above after 12 h treatment, NC could be distributed through digestive system and relocated from mouth to other tissues inside the insect body. When associated with dilutions of conventional pesticides, the corrected mortality were significantly increased up to 95% or above. The dosage of the chemical pesticide and nanochitin in the mixtures (1:1 by volume) were all reduced to half. The acute oral toxicity Lethal Dose 50% (LD50) to SD rat is greater than 5000 mg/kg BW (body weight) in male and female, acute dermal toxicity LD50 is greater than 2000 mg/kg BW of NC.ConclusionsNC has a strong promotive effect on insecticidal effectiveness of chemical insecticides. It was easily absorbed by plant, transported and distributed from mouth to other tissues of the insects while sucking plant fluid. Low acute oral and dermal toxicity to SD rat indicated that it is safe to apply in agriculture and food industry. NCs has a great potential for water-based nanopesticide formulation to reduce chemical pesticide use for future agro-environmental sustainability.

Contact pressure of high-voltage DC power relay change and life prediction and structure optimization

To effectively predict the life of high voltage dc power relay, the authors design the structure of the relay to extending its life. The contact failure mechanism of relay products is analyzed by observing the appearance of several contact failures. The electromagnetic-thermal field coupling model is established and the state of heat flow and distribution of temperature increase between electrical and thermal coupling contacts are analyzed through simulations and experiments. An adaptive neural network control system is established to conduct sample training, obtain the best stiffness coefficient of the main spring, and optimize the design of the main spring structure composed of composite springs. The action voltage, release voltage, contact resistance, contact pressure, action time, and release time as characteristic parameters, and the relative error, correlation degree, variance ratio, and small error probability of each characteristic parameter, are calculated. The precision grade index of contact resistance and action time is defined as level 1. The two characteristic parameters are selected as the prediction variables to establish the life-prediction model based on gray theory. The relative error between the predicted and test life is 5.31%–5.6%, indicating that the life-prediction model has high accuracy. The test results show that the combined main spring structure can extend the life of a relay by 18.15%.

Economic and energy efficiency of potato cultivation in different feeding areas and the use of fungicides in the Middle Urals

Abstract. The main factor in increasing the productivity of potatoes is the improvement of its cultivation technology. The purpose of the research was to determine the economic and energy efficiency of cultivating potato of the Gala variety under different feeding areas and the use of fungicides. The research was carried out on the experimental field of the educational and experimental farm of the Ural State Agrarian University during 2016–2018, in a two-factor field experiment according to the following scheme: Factor A (feeding area): 1400, 1750, 2100, 2450, 2800 cm2; Factor B (use of fungicides): “Shirlan”: 1400, 1750, 2100, 2450, 2800 cm2; “Infinito”: 1400, 1750, 2100, 2450, 2800 cm2. The objects of research in the experiment were medium early potato variety Gala and fungicides such as contact action “Shirlan” (0.3 l/ha) and “Infinito”systemic action (1.2 l/ha). The results showed that when using the fungicide “Shirlan” (factor B), the best in the experiments was the variant with a feeding area of 2450 cm2 (70 × 35 cm), where the highest yield of 36.6 t/ha was obtained, with a low cost price – 4446 rubles/ton, high profit – 269 172 rubles/ha and profitability – 165.43 %. In experiments on all variants, the energy efficiency coefficient did not reach 1.27. The scientific novelty of the research lies in the fact that for the first time the influence of the feeding area (factor A) and the use of fungicides (factor B) on the yield, economic and energy efficiency of potato cultivation in the Middle Urals was studied.

Biological activity of benzoxazolinone and benzoxazolinthione derivatives

The article presents the herbicidal, defoliating, fungicidal properties of the synthesized derivatives of benzoxazolinones and benzoxazolinethions. It was shown that 3-alkylbenzoxazolinones, 3-alkyl-6-halobenzoxazolinones and 2-alkylthiobenzoxazoles exhibit herbicidal action during the growing season of plants, and they also cause cotton leaves to drop up to 70%. It was found that 3-alkylbenzoxazolinones and 2-alkylthiobenzoxazoles exhibited fungicidal activity against the pathogen, Fugarium oxyporum and Verticillum dahlia. Among them, 2-methylthiobenzoxazole inhibited spores of the fungi Verticillum dahlia by 96.4% and benzoxazolyl-2-carbamic acid butyl ester by 65%. These compounds exhibit fungicidal action against the pathogens of powdery mildew on cucumbers - Erysiphe cichoraceorum and powdery mildew on wheat - Erysiphe graminis, approaching the control Karatan. Apparently, these compounds are chemicals of contact action.

WEED CONTROL IN “LL” MAIZE TOLERANT TO GLUFOSINATE-AMMONIUM

The glufosinate-ammonium is an herbicide with contact action and, whenused in tolerant LL maize, requires associations with other products to improve the weed control spectrum and increase the residual period in the area. The aim of this work was to evaluate the efficacy and selectivity of glufosinate-ammonium, applied alone and in combination with other herbicides, for weed control in maize crops. The treatments consisted of two strategies. In the first one, the following herbicides were applied in pre-emergence conditions: atrazine, [atrazine + simazine], [atrazine + oil], [atrazine + S-metolachlor], and S-metolachlor; with the subsequent application of glufosinate-ammonium in post-emergence condition of maize. The second application method corresponded to the use of glufosinate-ammonium, alone and combined with nicosulfuron + mesotrione and the other products used in the first strategy, in addition to two control areas, being one weed-infested and the other weed-free. Phytotoxicity on maize and weed control were assessed. Ear insertion height, number of rows per ear, number of grains per row, thousand grain weight and maize yield were determined upon harvesting. The herbicides were effective and did not cause yield loss to the crop. The herbicides applied in combination with glufosinate-ammonium were efficient in regard to weed control and selective to maize.

Повышение устойчивости дереворежущих пил термопластическим воздействием на распределение остаточных напряжений в полотне

The saw stability in operation defines the ability of the saw blade to resist the forces acting on it in the plane of greatest rigidity. The saw can work reliably only in case of maintaining stable balance, which is achieved through the creation of normalized residual stresses in certain zones of the saw blade by different methods. The stresses balance the forces of external influences. Compressive stresses are created in the central part of the blade to make the circular saw operational. These stresses compensate the forces of centrifugal acceleration, temperature heating of individual zones of the saw blade, external longitudinal and transverse bending forces arising in material processing. In practice, the creation of normalized stresses in the saw disk is traditionally carried out only by local mechanical contact action (forging, rolling) of the saw blade tool on the steel saw blade. It is proposed to form the stressed state of the disk by thermophysical action instead of the traditional mechanical processing of the saw blade. The thermophysical action involves the creation of normalized residual stresses in the saw blade by the concentrated thermal exposure to local differently directed narrow-band zones of straight or deflected shape, mainly radial or along concentric traces, controlling the process in real time. A new approach to the formation of residual stress fields in the saw blade by thermoplastic action enables to radically change the settingup procedure of the circular saw, ensuring its stability in operation.

May the odds be ever in your favor: The Hunger Games and the fight for a more equal society. (Negative) Media vicarious contact and collective action

AbstractVarious studies have found that reading books about positive interactions between ingroup and outgroup characters, known as media vicarious contact, can reduce prejudice. Focusing on the fantasy saga of The Hunger Games, we examined the effects of negative vicarious contact on collective action across two studies. Specifically, we tested whether reading about fantasy characters living in a postapocalyptic conflictual society with large social disparities between advantaged and disadvantaged groups leads advantaged group members to display greater willingness to engage in collective action on behalf of the disadvantaged group. Results from Study 1 (correlational survey in the United Kingdom and United States) and Study 2 (experimental intervention in Italy) revealed that reading The Hunger Games is indirectly associated with greater collective action intentions via increased anger toward injustice. In both studies social dominance orientation (SDO) acted as a moderator, but in opposite directions: mediation was significant for low‐SDOs in Study 1, and for high‐SDOs in Study 2. Results are discussed in relation to the importance of media vicarious contact via book reading for social change, and to the need to identify the contextual conditions allowing to anticipate the specific moderation pattern that is more likely to emerge.

Microsclerometry as Applied to Studying Rehbinder Effect. Review

Works devoted to studying the effect of active environments on damageability of surfaces of solid bodies and materials upon contact actions (Rehbinder effect) have been briefly reviewed. A novel procedure, which combines microscratching and electrochemical reduction of an active component on a studied material surface, has been described. This procedure enables one to simulate and study the liquid-metal embrittlement of the material in the absence of a liquid metal phase on its surface.

Mirror-touch experiences in the infant brain

ABSTRACT Several adult studies have proved the existence of a shared neural circuit in the somatosensory cortices that responds to both the body being touched and the sight of the body being touched. Despite the fundamental role of touch in infancy, the existence of similar visuo-tactile mirroring processes, supporting both felt and seen touch, still needs an in-depth empirical investigation. To this aim, we explored 8-month-olds mu desynchronization over somatosensory sites in response to felt and observed touch in a live experimental setting. EEG desynchronization (6–8 Hz mu frequency range) was measured during three experimental conditions: i) infants were stroked on their right hand by a parent (Touch condition); ii) infants observed a right hand being stroked (Observation Touch condition); iii) infants observed a right hand moving over the left hand without making contact (Action Control condition). Mu desynchronization of somatosensory sites contralateral to the hand being stroked emerged in response to both Touch and Observation Touch conditions, but not in the Action control condition. Further, greater mu desynchronization was found in the Touch and Observation Touch conditions as compared to the Action control condition. Our results highlight the early involvement of a shared somatosensory system, likely supporting infants’ understanding of others’ tactile sensations.

Immunosuppressive Effects of Mesenchymal Stem Cells-derived Exosomes.

Mesenchymal stem cells (MSCs) have become important seed cells in therapy because of their immunosuppressive function and anti-inflammatory effects. MSCs exert immunosuppressive effects through direct contact or paracrine action. The paracrine functions of MSCs are at least partially mediated by exosomes, which are membrane vesicles, carrying abundant proteins, nucleic acids and other active molecules. MSC-exos have heterogeneity. The exosomes from different donors, tissues generations of MSCs carry different bioactive molecules. These cargos are transferred to recipient cells by endocytosis or binding to proteins on the receptor surface to mediate intercellular communication between different cell types and affect the functions of the recipient cells. Exosomes play an important role in the regulation of the immune system. Exosomes derived from MSCs (MSC-exos) carry immunomodulatory effectors or transmit active signal molecules to regulate the biological activities of immune cells and thus mediating immune suppression, especially on macrophages and T cells. Mitochondria and autophagy-related pathways are also associated with MSC-exos immunosuppressive effects. Graphical Abstract.

Secondary Metabolites of Asclepias curassavica (Apocynaceae) and its Effects on Food Preference and Mortality of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Asclepias curassavica L. plant is toxic for vertebrates, and little is known about its effects on invertebrates, as well as whether its secondary metabolites have an influence on food preference and survival of insects. Thus, a study was conducted to verify the action of A. curassavica on Spodoptera frugiperda J.E.Smith. The plants were collected, dried and ground to compose a crude ethanolic extract. Food tests were carried out with and without opportunity of choice, using corn leaf discs immersed in the extract at concentrations of 1%, 2% and 4%, for assessment of food consumption (g) and preference index. Later, the extract was topically applied on second- and fifth-instar caterpillars, at concentrations of 1%, 2%, 4% and 6%, in order to observe its effect on survival. In parallel, analysis was conducted to verify the presence and measure the amount of total polyphenols and flavonoids in the extract. There was contact action between the extract and second-instar caterpillars at all concentrations, with treatment 6% causing 100% of mortality 72 hours after application. None of the treatments promoted contact action on fifth-instar caterpillars. In food tests with and without opportunity of choice, all treatments caused reductions in consumption, which classified all as phagodeterrent, with treatment 4% standing out as the least favorite. The presence of total polyphenols and flavonoids was found in the extract, presenting 58.75 ug/mL and 150.1 ug/mL, respectively. The A. curassavica extract proved promising in S. frugiperda control.

Newton's early metaphysics of body: Impenetrability, action at a distance, and essential gravity

In this paper, I discuss Newton's conception of body in De gravitatione and its relation to the legitimacy of action at a distance. Howard Stein has argued that such a conception privileges contact over distant action: by dint of being impenetrable, bodies must necessarily act through contact; yet there is no analogous property of which action at a distance is a consequence. This paper presents a challenge to Stein's reading. I begin by arguing that impenetrability cannot imply action through contact because such an implication hinges on one's laws of motion in three senses: it must be physically possible for contact to occur, the laws must make coherent the notion of a trajectory from which a body deviates, and the necessity of introducing collision dynamics renders impenetrability otiose. I then turn to a close reading of De gravitatione and consider whether Newton himself sees his account of body as establishing contact action as prior to distant action in any sense. Although Newton did see impenetrability as rendering bodily action intelligible, ample room remains for action at a distance once one takes into account certain textual ambiguities and the provisional character of the narrative. By way of substantiating this reading and answering an objection of Stein's, I pivot to Newton's remarks concerning the nature of gravity in his correspondence with Bentley. Although Newton is often held to reject essential gravity as being in conflict with his metaphysical commitments, I offer a more austere reading on which Newton is decrying a kind of action that is unmediated, or alleged to take place without a cause. By contrast, Newton carves out a place for action at a distance mediated by an immaterial agent as a perfectly acceptable explanation of natural phenomena.

Concept Designing of Armoured Fighting Vehicles for Future Combat

The experience of military conflicts in recent decades shows changes in the nature of warfare performance, which differ significantly from those conditions for which existing types of armoured fighting vehicles were created. The conducted analysis of the works on the designing of advanced armoured fighting vehicles shows that these changes have not yet been sufficiently taken into account. It still focuses on the creation of high-value combat vehicles with high combat performance for direct (contact) actions. Given the limited economic opportunities of the most countries this inevitably leads to unreasonable expenses. This article presents a conceptual approach to design up to date of armoured fighting vehicles which is based on the asymmetrical principle of their development. Given that the practical implementation of the proposed approach is complex and high-cost, the results of simulation modelling of typical situations of combat use of the offered types of armoured fighting vehicles are given as evidence.

Efeito letal de extratos de piperáceas ao ácaro-vermelho-das-palmeiras, Raoiella indica (Acari: Tenuipalpidae)

Desde a introdução do ácaro-vermelho-das-palmeiras, Raoiella indica, no Brasil, diversos métodos de controle têm sido estudados para supressão desta praga, a exemplo dos métodos de controle quarentenários, químicos, biológicos e com extratos vegetais. O presente estudo objetivou avaliar o potencial letal de extratos aquosos de folha de Piper aduncum, P. callosum, P. hostmannianum, P. marginatum e P. peltatum sobre R. indica. Foi avaliada a ação residual de contato dos extratos, aplicados por imersão, nas concentrações de 0, 5, 10, 15, 20, 25 e 30%, sendo a ação avaliada em três períodos de exposição, 24, 48 e 72 h. A partir dos dados de mortalidade nas diferentes concentrações e em cada período de exposição foram determinadas as mortalidades corrigidas e as concentrações letais (CL25% e CL50%) dos extratos das piperáceas para a população de R. indica. Apenas os extratos de P. aduncum, a 5% após 24 h de exposição, e P. callosum, nesta mesma concentração em todos os tempos de exposição, não apresentaram mortalidade corrigida diferente do controle. As CL25% variaram de 0,99 a 13,02%, 1,29 a 7,89% e 1,82 a 7,69%, respectivamente, para os períodos de exposição de 24, 48 e 72 h. Já as CL50%, respectivamente para os mesmos períodos, variaram de 2,27 a 21,29%, 2,33 a 13,26% e 2,84 a 10,94%. Os extratos aquosos de folha das cinco espécies de piperáceas apresentaram efeito toxicológico sobre a população de R. indica.

Performance and design of oval-ended elliptical CFT columns under combined axial compression-torsion

Previously, a series of studies focusing on the response of the oval-ended elliptical concrete-filled steel tubular (OECFT) columns under various single load conditions were performed due to its novel superiorities in flow smoothness, architectural aesthetics and structural efficiency. Nonetheless, the properties of the OECFT column imposed with combined forces have never been addressed. In attempt to fill this gap, this paper aims to present a numerical analysis via ABAQUS solver to explore the torsional behaviour of the axially-loaded OECFT column. Following that, the finite element (FE) modelling was verified by the existing experimental data, and then the comprehensive parametric research on the type of column was conducted. Detailed responses of the OECFT column subjected to combined axial compression-torsion, in aspect of the typical torque ratio (T/Tu) – angle (θ) curve, failure patterns, contact action and characteristic relationship of relative ultimate torque value (Tu/Tu0) versus axial compression ratio (N/Nu0), were respectively investigated. The numerical simulation revealed that the torsional resistance of the type of column increased with the increase of the steel strength, concrete strength and steel ratio, while a decrease was obtained with the increase of the aspect ratio. Accompanied by the changes in axial compression ratio, material strength and steel ratio, obvious influences on the Tu/Tuo-N/Nuo curve were obtained. Finally, a design provision to assess the torsional strength of the OECFT column under combined axial compression-torsion was proposed and was validated in compliance with the aforementioned analyses.