Mechanical Activation Research Articles

Investigation on mechanism of mechanical activation and chemical reactions in CMP of diamond assisted by hydroxyl free radicals

Chemical mechanical polishing (CMP) is a crucial manufacturing process for diamond substrate applications. However, due to the extremely high hardness and chemical stability of diamond, its CMP efficiency is extremely low. This study aims to achieve microscopic simulation of atomic oxidation removal at the three-phase interface between diamond abrasive particle, diamond substrate, and hydroxyl free radicals (∙OH) aqueous solution. The mechanical activation behavior, microscopic mechanism, and feasibility of elementary reactions in the ∙OH aqueous solution environment was studied using various perspectives of radial distribution function, central atomic coordination state, atomic bonding and removal forms, energy, electron orbitals, and density functional theory (DFT). The simulation results indicate that during the process of diamond atomic oxidation removal, the atomic density at the first adjacent position centered on one atom decreases, and the stable covalent bond structure is disrupted, resulting in an amorphous phase transition. The chemical adsorption reaction generates C-O and C–H bonds. The C atoms mainly separate from the diamond substrate by the forming products such as carbon monoxide (CO), carbon dioxide (CO2), and carbon chains. The mechanical activation behavior indirectly reduces the activation energy of chemical reactions, while increasing the absolute value of adsorption energy and improving the ability of chemical adsorption solution atoms H and O, as well as ∙OH groups. Based on DFT, it has been verified that the intrusion process of ∙OH groups in the elementary reactions involving the typical product C*O2 is an exothermic reaction that can occur spontaneously, and the energy barrier needs to be overcome by the mechanical action of abrasive particles. At the same time, the energetics of the oxidation of diamond C atoms to generate C*O2 have successfully confirmed that the combined action of ∙OH and diamond abrasive particles is expected to achieve efficient oxidation removal and finishing polishing of diamond atoms.

Adaptive Leadership: Navigating the Challenges of Post-Pandemic Working Arrangement

In the seemingly new world of work after the pandemic, managers are confronted with new difficulties in managing their teams. This research aims to answer the important research question on adaptive leadership dynamics: how do leaders steer in change? Drawing on the constantly evolving nature of flexible working environments. This paper seeks to establish the various approaches used by leaders in the current work environment. The purpose of this investigation is to provide critical recommendations to the organizational decision-makers on how to manage their employees in this post-COVID-19 world. Both quantitative and qualitative data collection methods will be employed to interview leaders in various sectors regarding the following: (1) identifying and contacting leaders who have effectively navigated the team’s post-pandemic; (2) identifying firsthand experiences and understanding of leadership strategies. The study used interviews, of which 70% were semi-structured, and the number of participants was 10. The analysis presented in this study revealed the type of leadership and their coping mechanisms, the factors that led to the activation of the coping mechanisms, and that post-pandemic, a leader’s style can be altered not only for business gain but also as a positive change for the leader themselves. The change that leaders had to undergo in post-pandemic working arrangements was diverse, and changing has never been unfamiliar to changing the leadership style. Despite the fact that our studies provide significant information regarding the main area of leadership in the management climate, there are certain aspects that deserve certain considerations. The coordination of this research is based only on middle managers, which restrains the viewpoint of our study with cross-industry background. However, there is one major limitation of the study because the study was conducted at the end of the pandemic, and therefore it may not be equally relevant as any other period of time. Therefore, the leadership phenomenon can be explored from the leader’s perspective alone, and this might result in ignoring crucial follower or any other stakeholder information. In this research, there was no other interview conducted to compare with the interview completed in this research to validate the respondent answers. In view of these, it would be appropriate to take a closer look at the leadership processes from different angles in order to gain a better appreciation of the phenomenon

Cakile maritima: A Halophyte Model to Study Salt Tolerance Mechanisms and Potential Useful Crop for Sustainable Saline Agriculture in the Context of Climate Change.

Salinity is an increasing problem for agriculture. Most plant species tolerate low or, at best, moderate soil salinities. However, a small (<1%) proportion of species, termed halophytes, can survive and complete their life cycle in natural habitats with salinities equivalent to 200 mM NaCl or more. Cakile maritima is a succulent annual halophyte belonging to the Brassicaceae family; it is dispersed worldwide and mainly grows in foreshores. Cakile maritima growth is optimal under slight (i.e., 100 mM NaCl) saline conditions, measured by biomass and seed production. Higher salt concentrations, up to 500 mM NaCl, significantly impact its growth but do not compromise its survival. Cakile maritima alleviates sodium toxicity through different strategies, including anatomical and morphological adaptations, ion transport regulation, biosynthesis of osmolytes, and activation of antioxidative mechanisms. The species is potentially useful as a cash crop for the so-called biosaline agriculture due to its production of secondary metabolites of medical and nutritional interest and the high oil accumulation in its seeds. In this review, we highlight the relevance of this species as a model for studying the basic mechanisms of salt tolerance and for sustainable biosaline agriculture in the context of soil salination and climate change.

ВЛИЯНИЕ ПРОДОЛЖИТЕЛЬНОСТИ МЕХАНИЧЕСКОЙ АКТИВАЦИИ МЕТАЛЛИЧЕСКИХ ПОРОШКОВ ПРИ ИХ СМЕШИВАНИИ НА ПРОЧНОСТЬ ПЛАЗМЕННОГО ПОКРЫТИЯ

The article considers the effect of the duration of mixing the components of the FeCoCrAlTiCuMo coating in a special mixer-activator on the strength of the resulting coating. Indirect confirmation of the effect of mechanical activation during mixing on the formation of the plasma coating was obtained and a rational mixing time was determined. Based on the data obtained, it is possible to judge the possibility of creating a HES coating by mixing the components in an inert atmosphere, which allows increasing the strength of the coating by more than 2 times, in comparison with mixing powders by the traditional method in an air atmosphere.

Resonant transport in a double-barrier heterostructure AlxGa1−xAs/GaAs and mass discontinuity: a semiclassical path integral approach

In this paper, we investigate the dependence of the resonant carrier transport in an AlGaAs/GaAs double-barrier heterostructure on the electron’s effective mass discontinuity between the well and the barrier layer. We use a one-dimensional model for the effective potential and consider the activation of the resonant tunneling mechanism when a bias is applied between the emitter and the collector. We calculate the system’s Green’s function through semiclassical path integration to obtain the complex spectrum. Electron’s effective mass discontinuity affects our calculations through the contributions of the various propagations inside the heterostructure and the multiple reflections from the turning points. Our findings show that the lowest resonance energy decreases linearly with increasing bias, while the real energy shift of the resonance decreases in a non-linear manner with the mass discontinuity. We also observe that the resonant transport time increases nearly linearly with the mass discontinuity. These results demonstrate the impact of the carrier’s inertia enhancement on the resonance characteristics and are consistent with established concepts in quantum mechanics and previously published works. Furthermore, we identify a critical bias value that distinguishes the behavior of the symmetric and asymmetric heterostructure. Additionally, the derivative of the transport time with respect to mass discontinuity is found to be independent of the applied bias. Our results provide concise analytical relationships involving parameters such as barrier and well thickness and shape, enabling the prediction and optimization of various nanoscale devices’ performance.

Mechanical (ball milling) activation to regulate microstructure of κ-carrageenan and improve freeze-thaw stability of κ-carrageenan gels and κ-carrageenan-based emulsion gels

To expand the wide range of applications of κ-carrageenan in the food and biomedical fields, we have physically modified the carrageenan and focused on its freeze-thaw stability. In this study, κ-carrageenan (KC) was modified by mechanically activated to prepare wet ball milling κ-carrageenan (WMKC), and its properties were determined. The research results indicate that mechanical activation helps improve the freeze-thaw stability of KC gels and enables KC to better maintain its gel network structure during the freeze-thaw process. These phenomena are related to the effects of mechanical activation on the particle morphology, molecular structure, molecular interactions, and moisture migration of κ-carrageenan. The particle morphology images demonstrated that the WMKC particles exhibited a more irregular surface, which facilitated greater penetration of water molecules into the interior of the κ-carrageenan particles. Furthermore, the results of molecular structure and molecular interaction analyses showed that mechanical activation resulted in the removal of sulfate groups from the κ-carrageenan molecular chain. This resulted in more free -OH being exposed on the molecular chain, which in turn provided more binding sites for KC molecules with water molecules. Low-field nuclear magnetic resonance (LF-NMR) results also proved that WMKC could better maintain the binding with water molecules during the freeze-thaw process. A better combination of WMKC molecules and water molecules can significantly diminish the irreversible damage to the gel network structure of WMKC during the freeze-thaw process, thereby effectively enhancing the freeze-thaw stability of WMKC. In addition, we further used WMKC as the gel matrix and investigated that the freeze-thaw stability of the WMKC-based emulsion gel was optimal when the mechanical activation duration was 3h, which well meets the demand of κ-carrageenan emulsion gels in the frozen food industry.

A survey of water quality in areas of Albanian ports

This study report data on physical-chemical parameters and on concentrations of organic pollutants in marine water samples of Albanian ports. Nutrients, PH, temperature, conductivity, TSS, DO, BOD, COD, chlorines, sulfates, magnesium and calcium ions were the indicators used for evaluation of water quality. Also, organic pollutants (organochlorine pesticides, PCBs, PAH and benzene) were determined in seawater samples. Albania is facing by Ionian and Adriatic seas in a coastline of more than 300 km. Several ports are in function in Albanian coastline. Ship transport and many activities (automobile transport, mechanical activities, deposits, etc.) are the main factors of water pollution in port areas. Water samples from seven ports (the main Albanian ports) starting from Saranda port in the South to Shengjini port in the North, were analyzed in this study. Sampling was realized in May 2023. Based on physical-chemical indicators the water in the port of Saranda was the cleanest water, while Porto-Romano, Petrolifera and the fishing port in Zvernec was the most polluted one. Organic pollutants were detected in all water samples. Presence of the degradation products of pesticides may be related with previous uses of them. Presence of PCBs can be because of atmospheric deposition (volatile congeners), water currents and mechanical businesses (heavy congeners). PAHs and Benzene were detected on more than 70% of the analyzed samples. Intense ship and automobile transport in the port areas, mechanical businesses discharge and hydrocarbon processing i(Petrolifera and Porto-Romano) can be main factor for their presence. Water currents and new arrivals from the rivers can influence the levels and profile of pollutants. The found levels of organic pollutants in water samples of Albanian ports were higher than reported levels in previous studies for the Adriatic Sea (Albania coastline).

The effect of Amazonian andiroba oil on antioxidant activity, mechanical, rheological and skin permeation properties of environmentally responsive emulgels

Emulgels are semi-solid systems that can improve the bioavailability of bioactive agents by combining the properties of gels and emulsions in a stable way. The use of bioadhesive systems by combining different polymers can prolong the release of various bioactive agents, such as the oil of Carapa guianensis (andiroba oil; AO), which has been of interest to researchers for years due to its antioxidant properties, antitumor, antibacterial and anti-inflammatory activity. Therefore, the aim of the present work was to evaluate the influence of different amounts of AO on the physicochemical properties of thermoresponsive bioadhesive emulgels composed of Carbopol 974 P® and poloxamer 407. The mechanical, rheological, bioadhesive, skin permeation and antioxidant activity characteristics were analyzed. AO and emulgel systems showed a potential antioxidant effect via different mechanisms. The formulations also displayed important results in terms of textural mechanical, bioadhesiveness, rheological and skin retention characteristics. However, F1 showed more promising results than F2, with differences mainly in softness, bioadhesion and rheology. These results ensure favorable properties for potential use as a topical semi-solid formulation and for therapeutic applications. However, additional studies are necessary to explore their in vitro biological and in vivo performance.

A green extraction technology of lignocellulose from cassava residue by mechanical activation-assisted ternary deep eutectic solvent

Lignocellulose (LC) is a natural polymer material that holds immense potential for various applications. However, extracting LC from biomass wastes with high-starch content has been challenging due to low selectivity and yield. In this study, LC was prepared from cassava residue (CR) via a combination of mechanical activation pretreatment and a citric acid (CA)-enhanced ternary deep eutectic solvent (TDES) consisting of choline chloride (ChCl), lactic acid (LA), and CA. The mechanical activation reduces the size of CR, greatly promoting the removal ability for starch, lignin and hemicellulose using TDES, and thus improving yield and selectivity of LC through this method. The CA esterified LC to prevent its excessive hydrolysis and increased a significantly higher LC content (82.52 wt%) compared to mechanical activation only and DES without CA, increasing by 6.97 times and 1.26 times, respectively. The extraction temperature significantly affected the structure, composition, thermal stability of LC and the properties of recovered TDES. The LC extracted at 90 °C (LC-90) had the highest cellulose content (82.52 wt%), crystallinity index (44.82 %), and higher degradation temperature (339.7 °C). The properties of the recovered TDES and extraction mechanism were analyzed. This study provides a strategy for the high-value utilization of biomass waste.

The influence of substantial intragranular orientation gradients on the micromechanical response of heavily-worked material

In this study, we employ high-energy X-ray characterization to examine the role of relatively large amounts of intragranular lattice misorientation – present after many thermomechanical processes – on the micromechanical response of Al-7085 with a modified T7452 temper. We utilize near-field high energy X-ray diffraction microscopy (HEDM) to measure three-dimensional (3D) spatial orientation fields, facilitated by a novel method that utilizes grain orientation envelopes measured using far-field HEDM to enable reconstruction of grains with intragranular orientation spreads greater than 20°. We then assess the consequences of consideration of intragranular orientation fields on the predicted deformation response of the sample through 3D micromechanical simulations of the forged Al-7085. We construct two virtual polycrystalline specimens for use in simulations: the first a faithful representation of the HEDM reconstruction, the second a microstructure with no intragranular misorientation (i.e., grain-averaged orientations). We find significant differences in the predicted deformation mechanism activation, distribution of stress, and distribution of plastic strain between simulations containing intragranular misorientation and those with grain-averaged orientations, indicating the necessity for consideration of intragranular orientation fields for accurate predictions. Further, the influence of elastic anisotropy is discussed, along with the effects of intragranular misorientation on fatigue life through the calculation and analysis of fatigue indicator parameters.

Using zero nano-valent iron/thin film composite (ZNVI/TFC) membrane for brackish water desalination and purification

This study looked at the use of synthetic Zero Nano-valent Iron (ZNVI) particles in a unique interfacial polymerization technique on a polyamide thin film PA(TF) composite membrane for the treatment and desalination of brackish wastewater. Zero nano-valent iron (ZNVI) particles were created utilizing chemical reduction technique. ZNVI/PA(TF) NCs membrane is the outcome of advancing the PA(TF) membrane by combining with different concentration of ZNVI particles into the organic phase 1,3,5-benzenetricarbonyl trichloride (TMC). ZNVI/PA(TF) NCs membranes and ZNVI particles' surface properties were examined by the use of mechanical activity, contact angle, BET, FTIR, SEM, XRD, zeta potential, TEM analysis, and EDX studies. Using a variety of salt solutions, such as NaCl, Na2SO4, MgSO4, NaHCO3, CaSO4, CaCl2, and MgCl2, the ZNVI/PA(TF) NCs membrane performance towards salt rejection, flux (at varying pressure), anti-fouling activity, and ZNVI particles stability was assessed. This work investigated the removal efficiency of four dyes: methylene blue (MB), methyl orange (MO), Congo red (CR), and malachite green oxalate (MG). The water flux of the pristine PA(TF) membrane improved from 22 to 35 L/m2.h at 15 bar, indicating a 63% flux enhancement and the NaCl rejection was improved from 88.5 to 98.6%, indicating an 11.4% rejection improvement by incorporation of 0.3 wt.% of ZNVI particles into PA(TF) matrix. The ZNVI/PA(TF) NCs membrane's separation performances were evaluated using 5000 mg/L feed solutions of various salts at 15 bar. It was discovered that the water flux and salt rejection are, respectively, 33.4, 33, 32.7, 32, 31, 30 and 29 L/m2.h for CaSO4, MgSO4, Na2SO4, NaCl, CaCl2, MgCl2, and NaHCO3, and 97.4, 97, 96.5, 96, 94, 93.2, and 92.8%. It demonstrates that the flux recovery ratio (FRR) of the ZNVI/PA(TF) NCs membrane is greater than that of pristine PA(TF) (78%), coming in at 87%. High stability and fixing of the ZNVI particles on the modified membrane surface is indicated by the low overall ZNVI particles release rate over the course of the 10-day experiment.

Investigating Mechanically Activated Currents from Trigeminal Neurons of Non-Human Primates.

Pain sensation has predominantly mechanical modalities in many pain conditions. Mechanically activated (MA) ion channels on sensory neurons underly responsiveness to mechanical stimuli. The study aimed to address gaps in knowledge regarding MA current properties in higher order species such as non-human primates (NHP; common marmosets), and characterization of MA currents in trigeminal (TG) neuronal subtypes. We employed patch clamp electrophysiology and immunohistochemistry (IHC) to associate MA current types to different marmoset TG neuronal groups. TG neurons were grouped according to presumed marker expression, action potential (AP) width, characteristic AP features, after-hyperpolarization parameters, presence/absence of AP trains and transient outward currents, and responses to mechanical stimuli. Marmoset TG were clustered into 5 C-fiber and 5 A-fiber neuronal groups. The C1 group likely represent non-peptidergic C-nociceptors, the C2-C4 groups resembles peptidergic C-nociceptors, while the C5 group could be either cold-nociceptors or C-low-threshold-mechanoreceptors (C-LTMR). Among C-fiber neurons only C4 were mechanically responsive. The A1 and A2 groups are likely A-nociceptors, while the A3-A5 groups probably denote different subtypes of A-low-threshold-mechanoreceptors (A-LTMRs). Among A-fiber neurons only A1 was mechanically unresponsive. IHC data was correlated with electrophysiology results and estimates that NHP TG has ∼25% peptidergic C-nociceptors, ∼20% non-peptidergic C-nociceptors, ∼30% A-nociceptors, ∼5% C-LTMR, and ∼20% A-LTMR. Overall, marmoset TG neuronal subtypes and their associated MA currents have common and unique properties compared to previously reported data. Findings from this study could be the basis for investigation on MA current sensitizations and mechanical hypersensitivity during head and neck pain conditions.

A PCA-based algorithm for online false data injection and jamming attacks detection in cyber-physical systems

Cyber-physical systems face cyberattacks that hinder performance, increase cost, or even collapse the system. Thus, rapid and accurate attack detection is crucial for quick activation of defense mechanisms. Model-based attack detection approaches are known for their precision; however, the unavailability of the exact system model poses a challenge. In response, model-free approaches have gained increased attention as a practical alternative. In this paper, an online model-free algorithm for detecting false data injection and jamming attacks on CPSs is proposed. The method leverages principal component analysis to reconstruct the expected observations in a reduced dimension space, emphasizing the most effective principal components. Then, deciding on attacked or normal operation relies on analyzing either the Euclidean distance or the cosine similarity of the discrepancy between the expected and actual observations. The proposed metrics effectively expose subtle deviations from expected behavior, as any alteration in these components augments the distance between the observed and reconstructed values. The proposed method was compared with the conventional cumulative sum discriminator and Kalman-based algorithm, using an IEEE-14, IEEE-30, and IEEE-118 bus systems. The results demonstrate the superiority of the proposed algorithm in terms of various evaluation metrics, including F-score, precision, recall, and miss detection ratio.

PMA-Zeolite: Chemistry and Diverse Medical Applications.

Numerous scientific studies have been conducted in recent decades with the aim to study targeted application of zeolites in various industries, ecology, agronomy and medicine. The biggest advances, however, have been documented in medical and veterinary research of the natural zeolite, clinoptilolite. Although the exact biological mechanisms of action of the zeolite clinoptilolite are not completely elucidated, obtained results point to its antioxidative, immunomodulatory and detoxifying effects, the latter partially based on release of soluble and bioavailable silica forms from the surface material. The studied zeolite clinoptilolite materials have different geographical origins which confer to the physicochemical differences in the material. In addition, the production process of the material for oral applications differs between different producers which also accounts for different properties of the surface upon mechanical activation. Recently, a well-characterized zeolite clinoptilolite material, namely the PMA-zeolite, has been tested in different clinical applications and has shown potential as supportive therapy in inflammatory conditions, osteoporosis as well as during tumor chemotherapy. We accordingly present a comprehensive review of the PMA-zeolite effects in the clinical applications and discuss its probable mechanisms of effect in vivo.

Investigating the impact of curcumin extract incorporation on PVA/Collagen/Chitosan/HAp nanofiber scaffold: morphological, mechanical, wettability, degradation rate, and antibacterial activity

This study investigates the impact of curcumin extract incorporation on the properties of PVA/Collagen/Chitosan/HAp nanofiber scaffolds for bone tissue engineering applications. Nanofibers were fabricated via electrospinning using PVA, collagen, chitosan, hydroxyapatite (HAp), and curcumin. Their morphology, mechanical properties, wettability, degradation rate, and antibacterial activity were comprehensively evaluated. Fourier transform infrared (FTIR) spectroscopy confirmed the successful incorporation of all components into the nanofibers and the potential for interactions between their functional groups. Scanning Electron Microscopy (SEM) revealed bead-free, fine nano-fibers with a decrease in diameter ranging from 139 nm to 108 nm. Simultaneously, enhanced mechanical properties were observed, with ultimate strength increasing from 2.8 MPa to 8.8 MPa as the diameter decreased. Notably, 15% curcumin extract maintained favorable hydrophilicity and degradation rates, crucial factors for tissue regeneration. Antibacterial activity was also enhanced, with an inhibition zone of 6.71 mm against E.coli observed at 15% curcumin treatment. Staphylococcus aureus exhibited the largest zone of inhibition (8.74 mm) at 15% curcumin concentration. This research demonstrates the feasibility of incorporating curcumin into nanofiber scaffolds for bone tissue engineering applications.

Piezoelectric Scaffolds as Smart Materials for Bone Tissue Engineering.

Bone repair and regeneration require physiological cues, including mechanical, electrical, and biochemical activity. Many biomaterials have been investigated as bioactive scaffolds with excellent electrical properties. Amongst biomaterials, piezoelectric materials (PMs) are gaining attention in biomedicine, power harvesting, biomedical devices, and structural health monitoring. PMs have unique properties, such as the ability to affect physiological movements and deliver electrical stimuli to damaged bone or cells without an external power source. The crucial bone property is its piezoelectricity. Bones can generate electrical charges and potential in response to mechanical stimuli, as they influence bone growth and regeneration. Piezoelectric materials respond to human microenvironment stimuli and are an important factor in bone regeneration and repair. This manuscript is an overview of the fundamentals of the materials generating the piezoelectric effect and their influence on bone repair and regeneration. This paper focuses on the state of the art of piezoelectric materials, such as polymers, ceramics, and composites, and their application in bone tissue engineering. We present important information from the point of view of bone tissue engineering. We highlight promising upcoming approaches and new generations of piezoelectric materials.

CO oxidation on single Pt atom supported by two-dimensional ZnO monolayer: Reaction mechanism and precursor activation

CO oxidation is an effective solution for controlling CO emissions, and supported single-atom catalysts have shown excellent catalytic reactivity for chemical reactions. CO oxidation on a single Pt atom supported by a two-dimensional ZnO monolayer is investigated by combing ab initio molecular dynamics and density functional theory calculations. Seven reaction mechanisms are identified, including two new trimolecular Elie-Riedel mechanisms; six of them, except for the Mars-van Krevelen mechanism, have rate-limiting step energy barriers between 0.31 and 0.47 eV, which is lower than the experimental activation barrier of 0.81 eV on single Pt atoms supported by bulk ZnO, and is much lower than that of about 1.0 eV on Pt(111) surface. Furthermore, two preferred reaction mechanisms are discovered, an Eley-Rideal mechanism and a trimolecular Eley-Rideal mechanism, both of which have rate-limiting step energy barriers as low as 0.31 eV. Our results show that the more antibonding orbitals are filled in the reaction precursor, the higher its activation level. Activation of precursors plays an important role in CO oxidation and leads to different mechanisms. These results provide insights into the design of efficient single-atom catalysts supported by two-dimensional materials for the removal of CO pollutants.

Effect of dimephosphone in a course administration on the mechanical activity of the intestine of rats with an autism model

BACKGROUND: Gastrointestinal tract dysfunctions are a very common problem in patients with autism spectrum disorders, which aggravates the underlying course of the disease, and therefore there is a need to find safe drugs to correct gastrointestinal dysfunctions. AIM: Evaluation of intestinal contractile activity in rats with an autism model after a course of intragastric administration of dimephosphone. MATERIAL AND METHODS: The mechanical activity of the duodenum and ileum of rats with the valproate model of autism after the administration of dimephosphone was studied in vitro. To model autism, female rats were given a single subcutaneous injection of sodium valproate at a dose of 500 mg/kg in the withers area on the 13th day of pregnancy. The offspring of these rats were divided into two groups. The experimental group of rats (n=12) was given dimephosphone at a dose of 50 mg/kg for 30 days, starting from the age of 2 months, control rats (n=12) were given physiological saline in an equal volume. Another group of rats was intact (n=9), which were born from female rats not exposed to valproic acid. The effect of carbachol (10–8–10–5 M), ATP (10–7–10–4 M), 2-methylthio-ATP (10–7–10–5 M) and electrical stimulation (1–5 Hz) on the mechanical activity of isolated intestinal smooth muscle preparations was assessed. Statistical processing was performed in IBM SPSS Statistics 26.0 using one-way analysis of variance. RESULTS: It was found that in rats with autism modeling, carbachol-induced intestinal contractions and ATP-induced intestinal relaxation increased. A course of intragastric administration of dimephosphone for 30 days normalized these changes, which became indistinguishable from the corresponding indices in intact animals. Thus, ATP at a concentration of 10–4 caused relaxation of the smooth muscles of the duodenum of rats with autism modeling after a course of dimephosphone administration by 77.1±14.7%, which significantly differed from the corresponding indices in control animals — 34.4±9.4% (p 0.05) and did not differ from the indices in intact rats. Similar changes occurred in the mechanical activity of the ileum. Intestinal relaxation in rats caused by 2-methylthio-ATP did not change significantly either in the control or in the group of animals receiving dimephosphone. CONCLUSION: Dimephosphone, when administered intragastrically, normalizes the disturbances in the mechanical activity of the intestines of rats with an autism model.

Synthesis of high purity Ti2AlC MAX phase by combustion method through thermal explosion mode: Optimization of process parameters & evaluation of microstructure

Obtaining high-purity MAX-phase powders is a challenging issue. Therefore, in this article, the effects of two key parameters, including mechanical activation time (1, 2, and 3 h), and preheating temperature (800 and 1000 °C) were investigated on the formation mechanism of Ti2AlC MAX phase using mechanically activated (assisted) self-propagating high-temperature synthesis (MA-SHS) combustion method through thermal explosion mode. For this aim, a powder mixture of titanium, aluminum, and carbon with a stoichiometry ratio of (2:1:1) was used. Differential thermal analysis (DTA) was carried out to evaluate the effect of mechanical activation and preheating temperature of the formation temperature of the target MAX phase. Subsequently, the microstructural, phase analysis, chemical composition, and determination of surface chemical states studies were carried out through scanning electron microscopy (SEM), X-ray energy distribution spectroscopy (EDS) transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), and X-ray photoelectric spectroscopy (XPS), respectively. DTA results illustrated that applying mechanical activation alters the formation temperature, which leads to an increase in the purity of the MAX phase. The quantitative measurements were carried out using the Rietveld method to determine the purity of the achieved MAX phase. The results indicated that samples subjected to 2 h of mechanical activation at a preheat temperature of 1000 °C exhibited to contain 96.1 % of Ti2AlC MAX phase, which is the highest value among other specimens and the lowest amount of secondary and oxide phases (3.9 % of TiC) during the combustion synthesis process compared to other samples.

Effect of inclusion complex formation and mechanoactivation on the structure and rheological behavior of starch-oleic acid mixtures

In the present work, for the first time, mechanical activation implemented in a rotor-stator device (RSD) has been used to enhance the formation of the amylоse-fatty acid complex in gelatinized starch at a moderate temperature (40 °C) using oleic acid (ОА) as a model guest compound. Mechanical activation was found to cause an increase in the complexing index from 10 to 30 % for non-activated mixtures to 83–92 %. The study of aqueous and dried starch-OA mixtures using optical and AFM microscopy and dynamic light scattering methods revealed a uniform distribution of amylose-OA complex particles with a size of 125–260 nm in the starch matrix. The freeze-dried starch-ОА sample prepared using mechanical activation exhibited a V-type crystalline structure. By rotational viscometry and dynamic rheometry, it was found that mechanical activation causes the gelation of aqueous starch-OA mixtures, which accompanies a decrease in their fluidity and an increase in elasticity. The developed method can be recommended for large-scale production of thickening and texture modifying materials based on gelatinised starch containing a fatty acid as a nutritional or structuring additive.