Wall Structure Research Articles

ТЕХНОЛОГИЯ ПОЛУЧЕНИЯ НАНОКАПСУЛ ДЛЯ ДОСТАВКИ ЛЕКАРСТВЕННЫХ СРЕДСТВ

Encapsulation of active ingredients in solid capsules made of biodegradable materials has attracted considerable attention over the past decades. In this brief review, we focus on the preparation of micro- and nanosized capsules and emulsions based on artificial peptides as a fully degradable material. It discusses various approaches to the preparation of polymer-based capsules as well as their critical properties such as size and stability. Dispersed polymer nanocapsules can serve as nanosized drug carriers to achieve controlled release as well as effective drug administration. The stability of the dispersion is determined by the type of surfactant and the nature of the outer shell of the capsule. Their release and degradation properties largely depend on the composition and structure of the capsule walls. Another important criterion is the capsule size, where the optimum is usually observed in the radius range of 100 to 500 nm. Nanocapsules can be prepared in fundamentally different ways: nanoprecipitation, emulsion diffusion, double emulsification, emulsion coacervation, polymer coating and layer-by-layer, and depend on the methodological and mechanistic aspects, encapsulation of the active substance and the raw materials used. Nanocapsules made using various biodegradable polymers are attracting increasing attention and are considered as one of the most promising drug delivery systems. Nanoencapsulated systems have a relatively higher intracellular absorption compared to microparticles, which can be modified depending on the surface charges of the nanocapsules and the hydrophilic or hydrophobic nature of the polymer used to form the shell.

Intravascular Ultrasound Assessment of Distal Trans-Radial Access in Patients Undergoing Percutaneous Coronary Intervention.

Distal trans-radial access (dTRA) for percutaneous coronary interventions (PCI) is increasingly gaining attention due to its potential to mitigate radial artery occlusion (RAO). However, a comprehensive understanding of the mechanical impact of the devices on the radial artery (RA) wall remains limited. Using a complete intravascular ultrasound (IVUS) evaluation of the RA, including also the vascular access site, we aimed to evaluate all the consequences related to the catheterization on the RA wall, starting from the vascular access, comparing conventional sheath and sheathless approaches. This is an observational, prospective, multicenter study aimed to assess the entire RA wall immediately after IVUS-guided PCI via-dTRA. IVUS assessment included quantitative measurements (minimal lumen area [MLA], minimal vessel area [MVA]) and qualitative observations (dissections, vasospasm). Study objectives included delineating RA wall structure post-PCI and comparing findings between conventional and sheathless approaches. Fifty patients (21 [42%] with conventional sheath, 29 [58%] sheathless) were enrolled between March 2023 and February 2024. Female patients were more prevalent in the convention sheath group (38% vs. 7%, p < 0.001). Sheathless approach utilized 7-French guiding catheters more frequently (33% vs. 86%, p < 0.001). Post-procedural IVUS identified dissections in 12% of cases, with no significant difference between approaches. Arterial vasospasm was present in a quarter of patients, numerically higher in the conventional sheath group (29% vs. 21%, p = 0.5). MLA and MVA were comparable between groups, though MLA and MVA were lowest at the proximal segment of the RA only in the conventional sheath group (p < 0.001). No RAO was documented during the IVUS evaluation. The intravascular assessment of dTRA after coronary interventions, utilizing either conventional or sheathless approaches, including large-bore guiding catheters, demonstrated a relatively low incidence of access-related complications such as dissection and vasospasm, without affecting the flow and patency of the proximal RA.

Plant cell wall structure and dynamics in plant-pathogen interactions and pathogen defence.

Plant cell walls delimit plant cells from their environment and provide mechanical stability to withstand internal turgor pressure as well as external influences. Environmental factors can be beneficial or harmful for the plants and vary substantially depending on prevailing combinations of climate conditions and stress exposure. Consequently, the physicochemical properties of plant cell walls need to be adaptive, and their functional integrity needs to be monitored by the plant. One major threat to plants is posed by phytopathogens, which employ a diversity of infection strategies and lifestyles to colonise host tissues. During these interactions, the plant cell wall represents a barrier that impedes the colonisation of host tissues and pathogen spread. In a tussle over maintenance and breakdown, plant cell walls can be rapidly and efficiently remodelled by enzymatic activities of plant and pathogen origin, heavily influencing the outcome of plant-pathogen interactions. We review the role of locally and systemically induced cell wall remodelling and the importance of tissue-dependent cell wall properties for the interaction with pathogens. Furthermore, we discuss the importance of cell wall-dependent signalling for defence response induction and the influence of abiotic factors on cell wall integrity and cell wall-associated pathogen resistance mechanisms.

In vivo study of pulmonary artery remodeling and pulsatility in long Fontan patient

Abstract Background Pulmonary vasculopathy associated with Fontan circulation is a relatively unexplored entity that could have clinical and therapeutic implications. Purpose Our aim was to evaluate the physiology of the pulmonary artery in patients with Fontan circulation using conventional right heart catheterization (RHC) and intravascular ultrasound (IVUS). Methods From December 2022 to January 2024, data from all consecutive Fontan patients undergoing RHC were prospectively collected at a tertiary referral center for adult congenital heart disease. Pressures and pulmonary artery wall high-definition IVUS recordings (OptiCrossTM, 60 MHz, Boston Scientific) were recorded at rest and during apnea. Pathological Fontan pressure was defined when as exceeding 15 mmHg. IVUS pulsatility index was defined as [(systolic lumen area - diastolic lumen area)/(diastolic lumen area) ×100], Peterson's elastic modulus as (pulmonary pulse pressure/IVUS pulsatility index), and area of wall thickness as [(wall area - lumen area)/(lumen area) x100)]. In the literature, the mean ± standard deviation (SD) normal values of elastic modulus and wall thickness area have been reported as 21 ± 1.7 mmHg and 1.4 ± 1.3%, respectively, in healthy patients without pulmonary hypertension (1: doi: 10.1186/s12931-017-0568-z). We define an alteration in intrinsic pulmonary arterial wall viscoelastic properties as an elastic modulus &amp;gt; 70 mmHg, and we define structural pulmonary wall remodeling as an increase in wall thickness area greater than 5%. Results 13 patients were studied. Median age was 28.1 years interquartile range (IQR) (25.6- 41.4), 7 (53.9%) were female, and 4 (30,8%) were in functional New York Heart Associtation (NYHA) class I. RHC and pulmonary arterial wall IVUS values are presented in Figure 1. 6 (46.2%) had Fontan abnormal pressures at rest. All patients showed minimal pulse pressure in the pulmonary arteries synchronized with heart rate, median pulmonary pulse pressure (IQR) 3 (2-4) mmHg. This pulsatility was detected in the IVUS study in all patients, pulsatility index (median (IQR) 4.8 (3.3-10.1)) and elastic modulus (median (IQR) 51.5 (20.5-101.6) mmHg). All of them had some degree of structural pulmonary wall remodeling (&amp;gt;5% wall thickness area), and 10 (76.9%) of them had marked remodeling (&amp;gt; 10%). The median (IQR) of wall thickness area was 13.6 (10.5-18.3) % (Figure 2). We think that the pseudo-normality of the elastic modulus is due to a low pulmonary pulse pressure, however, structural remodeling could be secondary to the endothelial dysfunction present and described in arteries with very low pulsatility. Conclusions The IVUS evaluation of the pulmonary artery in Fontan patients may be useful for revealing significant information regarding pulmonary physiology. Pulmonary wall thickening has been observed, providing insight into altered structural remodeling of the pulmonary arteries in this population.

Sub‐assemblage testing and fragility analysis of connections of continuous‐plasterboard suspended ceiling systems

AbstractPast earthquake reconnaissance reports highlighted extensive seismic damages to suspended ceiling components and connections, including instances of complete ceiling failures. The seismic qualification of these nonstructural elements typically requires comprehensive evaluation through full‐scale shake table testing. However, such experimental evaluation is ordinarily not possible for every change made in various components and connections of ceiling systems due to the cost and effort involved. A feasible alternative is to obtain the behavior of components and connections from sub‐assemblage testing and incorporate them in appropriate numerical ceiling models to derive mechanical responses for developing alternative or new installation schemes. This paper considers critical connections of three continuous‐plasterboard suspended ceiling systems that were evaluated using shake table‐generated motions. The connections were classified according to their attachment to typical floors and walls of building structures, and sub‐assemblage testing was conducted using both monotonic and cyclic displacement loading. The observed failure modes in each connection were detailed, and appropriate damage states were assigned as the basis for constructing connection fragility curves. The results of the sub‐assemblage testing were presented in terms of the hysteresis responses, envelope curves, nonlinear backbone curves, and cumulative energy dissipation curves. Additionally, multilinear models of the connections were derived by approximating nonlinear backbone curves’ initial‐ and post‐yield behaviors. These multilinear models were further idealized to derive three equivalent linearized models for simplified yet reasonably accurate results for linear structural analyses. Finally, fragility curves were derived for all connections, considering their cyclic displacement failure capacities.

A novel ultra-light bio-based fiberboard from mexican feather grass for thermal and acoustic insulation in green building construction applications

The use of natural fibers as raw materials for insulation fiberboard production is emerging as a strategy to replace wood fibers. This study developed an ultralightweight natural fiber insulation core fiberboard (CFB) with high mechanical strength, hygroscopic resistance, and excellent acoustic and thermal insulation properties. This study examined the production of CFB, which utilizes Mexican feather grass fibers with an epoxy resin binder across a range of densities of 0.18–0.36 g∙cm−3. Furthermore, the impact of incorporating a reinforcing skin layer of woven glass fibers on the core fiberboard's physical, mechanical, acoustic, and thermal properties was evaluated. All the fiberboard samples exhibited excellent thermal conductivity values (0.048–0.057 W/mK), which increased with increasing panel density (0.18–0.36 g∙cm−3). In addition, all of them displayed superior mechanical properties following the ASTM C208 standard. In terms of climatic resistance of the fiberboards, the results displayed excellent water resistance, exhibiting minimal humidity content (<5 %), thickness swelling (<6.5 %), and a hydrophobic surface, as indicated by the high-water contact angle (>121.96 at 30 s). Sound reduction exhibited a frequency-dependent tendency, with denser and sandwich fiberboards showing greater sound reduction of up to 27.9–36.56 dB at 3150 Hz for CFB-0.36 and SFB-0.52, respectively. Following ASTM C208, both core fiberboards and those coated with woven glass fiber skins (sandwich fiberboards, SFB) met the thermomechanical property requirements for regular and structural wall sheathing applications, respectively. These findings highlight the potential of Mexican feather grass as a bio-based alternative to wood, enabling the production of eco-friendly ultralightweight fiberboards with excellent thermomechanical properties suitable for building construction, such as regular and structural wall sheathing applications and ceiling decorations.

A novel optimization‐based modal pushover analysis procedure for estimating the response of structures

AbstractIn recent years, studies have focused on the seismic behavior of various structural systems, including single‐ and double‐layered spatial structures. While nonlinear dynamic analyses are common for these studies, they are time‐consuming and complex. To address this, many pushover procedures have been developed, but their effectiveness in spatial structures remains underexplored. This study introduces an optimized lateral loading profile for evaluating the seismic response of walled bilayer spatial structures. By combining dominant inertial forces and optimizing their corresponding coefficients with the particle swarm optimization (PSO) algorithm, an optimal loading profile is derived. The method's accuracy was tested on models with varying arch height‐to‐span ratios and a constant wall height‐to‐span ratio, as well as a 15‐story frame structure. The results obtained showed that the proposed method closely matches incremental dynamic analyses (IDAs) in predicting base shear, initial stiffness, and displacements, especially for higher arch height‐to‐span ratios. Additionally, the method accurately estimates drift profiles and nodal displacements on roofs and walls, and performs better than similar mode‐based methods for frame structures.

Microstructure and Mechanical Properties of Bimetallic Structure Fabricated through Wire Plus Arc Additive Manufacturing

This study investigates the fabrication and mechanical assessment of bimetallic structure (BMS) wall using wire plus arc additive manufacturing (WAAM) technology, employing stainless steel (SS) 304 and SS 308L SS filler wire. The usage of BMS is promoted due to the limitation faced during dissimilar welding of the SS grades. The high or improper melting of the interface will lead to elemental segregation, leading to structural failure. Producing seamless BMS plates will be an ideal replacement for dissimilarly welded joints. Notably, 308L SS demonstrates superior mechanical properties compared to 304 SS, exhibiting impressive tensile strength (TS) and exceptional ductility. BMS, constructed with 308L filler wire, closely matches these better mechanical attributes, making it an attractive choice for applications prioritizing mechanical performance. Furthermore, when compared to WAAM‐processed SS 304, BMS consistently outperforms in terms of TS while retaining remarkable ductility. This is due to the variation in the microstructure caused by complex thermal cycles. Hence, this research provides valuable insights into manufacturing and characterization of BMS, emphasizing the potential of WAAM‐processed BMS (SS 304/SS 308L) in engineering applications demanding superior mechanical properties while replacing dissimilar joints in the fields of aerospace, aviation, automobile, and power generation industries.

Effect of the local and large-scale environment on the star formation histories of galaxies

The specific environment of galaxies may play a key role in their evolution. Large extragalactic surveys make it possible to study galaxies not only within their local environment, but also within the large-scale structure of the Universe. We aim to investigate how the local environment influences the star formation history (SFH) of galaxies across a range of large-scale environments. We categorised a sample of 9384 galaxies into the three primary large-scale structures (voids, walls and filaments, and clusters). We further classified them based on their local environment (as either 'singlets' or group members) through a search of companion galaxies within sky-projected distances of $ r_p &lt; 0.45$ Mpc and velocity differences of $ v &lt; 160$ $ km s $. Subsequently, we explored these subsamples using SFH data from previous works. Throughout this study, we divided galaxies into long-timescale SFH galaxies (LT-SFH), which assemble their mass steadily along cosmic time, and short-timescale SFH galaxies (ST-SFH), which form their stars early on. We then compared their characteristic mass assembly look-back times. The distributions of mass assembly look-back times in ST-SFH galaxies are statistically different for singlets and groups. These differences are only found in LT-SFH galaxies when studying these distributions in stellar mass bins. Our results indicate that the large-scale environment is related to a delay in mass assembly of up to sim 2 Gyr, while this delay is $&lt;$1 Gyr in the case of local environment. The effects of both types of environment are more significant in less massive galaxies and in LT-SFHs. Our results are consistent with galaxies in groups assembling their stellar mass earlier than in singlets, especially in voids and lower mass galaxies. Local environment plays a relevant role in stellar mass assembly times, although we find that large-scale structures also cause a delay in mass assembly, and all the more so in the case of cluster galaxies.

Application of the FDTD Method for Multivariate Analysis of the Influence of Conductivity and the Arrangement of Hollows Inside Bricks on the Values of Electric Field Intensity

The article contains a numerical analysis of the effects of electromagnetic wave propagation in an area containing a non-ideal, non-uniform, and absorbing dielectric. The analysis concerned the influence of the structure of the building material and its electrical parameters on the electric field intensity. The analysis took into account the variability of the number of hollows in the brick, the width of hollows, as well as the arrangement of these hollows relative to each other using the example of two types of bricks. The article also provides the most commonly used values of electrical parameters for building materials (brick, plaster). For this reason, the article includes results for different values of conductivity (0–0.2 S/m). The FDTD (Finite Difference Time Domain) method was used for multivariate analysis. The aim was to verify the correctness of the numerical assumptions adopted. Using the example of the most commonly used wall structure in construction, the results obtained using the FDTD method were compared with values obtained using another numerical method, the finite element method (FEM). The influence of an additional layer of plaster on the considered wall on the electric field was also checked. The analysis showed that a symmetrical arrangement of bricks results in higher values of the electric field by an average of 20%. Of course, this depends on the length of the hollows and the number of holes. The highest field values occur at low conductivities (0–0.04 S/m). A brick wall with a larger number of hollows and a symmetrical brick arrangement shows the highest electric field intensity, especially for hollow sizes (0.009–0.015 m).

Cell wall remodeling confers plant architecture with distinct wall structure in Nelumbo nucifera.

Lotus (Nelumbo nucifera G.) is a perennial aquatic horticultural plant with diverse architectures. Distinct plant architecture (PA) has certain attractive and practical qualities, but its genetic morphogenesis in lotus remains elusive. In this study, we employ genome-wide association analysis (GWAS) for the seven traits of petiole length (PLL), leaf length (LL), leaf width (LW), peduncle length (PLF), flower diameter (FD), petal length (PeL), and petal width (PeW) in 301 lotus accessions. A total of 90 loci are identified to associate with these traits across 4 years of trials. Meanwhile, we perform RNA sequencing (RNA-seq) to analyze the differential expression of the gene (DEG) transcripts between large and small PA (LPA and SPA) of lotus stems (peduncles and petioles). As a result, eight key candidate genes are identified that are all primarily involved in plant cell wall remodeling significantly associated with PA traits by integrating the results of DEGs and GWAS. To verify this result, we compare the cell wall compositions and structures of LPA versus SPA in representative lotus germplasms. Intriguingly, compared with the SPA lotus, the LPA varieties have higher content of cellulose and hemicellulose, but less filling substrates of pectin and lignin. Additionally, we verified longer cellulose chains and higher cellulose crystallinity with less interference in LPA varieties. Taken together, our study illustrates how plant cell wall remodeling affects PA in lotus, shedding light on the genetic architecture of this significant ornamental trait and offering a priceless genetic resource for future genomic-enabled breeding.

Antibacterial effect of semiconductor laser radiation against the strains of S. aureus and P. aeruginosa, leading pathogens in osteomyelitis

Introduction The study of the antibacterial effect of photodynamic therapy against the leading pathogens of chronic osteomyelitis is one of the promising directions today.Purpose of the work was to evaluate the antibacterial effect against the strains of Staphylococcus aureus and Pseudomonas aeruginosa with the ALOD-01 laser system in the presence of photodithazine.Materials and methods The object of the study was 24-hour archival cultures of gram-positive and gram-negative microorganisms belonging to two taxa: Staphylococcus aureus (25923), Pseudomonas aeruginosa (27853). The antibacterial effect after the exposure to laser radiation in the presence of photodithazine on the microbial cells of the studied cultures was assessed by the absence of microorganism growth in the area of the light beam.Results Laser exposure in combination with photodithazine (concentration 0.5–1.0 mg/ml) on S. aureus for two minutes at 200–300 J achieved a bactericidal effect in the beam area. A bactericidal effect on the entire surface of the Petri dish was achieved with light exposure of 400 J for 5 minutes and a photodithazine concentration of 1.0 mg/ml. Laser exposure for 2 minutes in the presence of photodithazine at a concentration of 0.5 mg/ml and 1 mg/ml did not have an antibacterial effect on P. aeruginosa strains. Continuous growth of microorganisms was observed on the dish. Increasing the light dose and exposure time contributed to a decrease in the growth of microbial cells. A bactericidal effect was obtained only in the center of the dish in treating the bacterial suspension with photodithazine at a concentration of 5 mg/ml.Discussion The effectiveness of PDT depends on the type of microorganisms, the anatomical location of the infection site, as well as the properties of the photosensitizer and the laser used. Depending on the structure of the cell wall, different susceptibility of bacteria to photodynamic effects is observed.Conclusion S. aureus strains can be successfully photoinactivated using photodithazine. For P. aeruginosa strains, it was not possible to find a regime in which microbial cell growth was absent throughout the dish. The photodynamic reaction occurs only when adequate doses of light energy act on the photosentisizer in the presence of oxygen in the medium, while the photodynamic damage is local and the bactericidal effect is limited by the zone of light exposure.

Seismic isolation design of high-rise shear wall structures in high-intensity areas

Taking a shear wall structure in a high-intensity area of 20 floors as an example, the seismic reduction scheme of the structure was determined, and the Etabs software was used to conduct time history analysis on the seismic and non-seismic structures. The floor shear force, overturning moment, and short-term surface pressure of the isolation support were obtained. The results showed that under frequent earthquake action, the average maximum floor shear force in the X direction of the isolated upper structure was only about 28 % of that of the non-isolated structure. The maximum inter story shear ratio was 0.34, and the maximum floor shear force in the Y direction was only about 25 % of that of the non-isolated structure. The maximum inter story shear ratio was 0.31. The average maximum overturning moment of the upper structure in the X direction after isolation is about 30 % of that of the non-isolated structure. The maximum overturning moment ratio is 0.36, and the average overturning moment of the maximum floor in the Y direction is about 22 % of that of the non-isolated structure. The maximum overturning moment ratio is 0.26. Under rare earthquake action, the maximum inter story displacement angles in the X and Y directions of each floor of the seismic isolation structure are 1/302 and 1/446, respectively. The maximum surface pressure value of the isolation bearing under rare earthquake is 28.9 MPa, the minimum surface pressure value is 5.58 MPa, and the maximum displacement is 579 mm, which meets the requirements of the specifications. Overall, the seismic performance of the seismic isolation structure is good, and the isolation scheme is feasible.

Analytical and numerical calculation and simulation of heat transfer in a composite wall made of polyethylene terephthalate bottle

The dynamics of heat transfer in composite walls made of Polyethylene Terephthalate (PET) bottles is studied using the energy conservation model. Ten walls of different structures were studied, including two control walls made of compressed earth brick (CEB) and cementitious material, cement-sand brick (CSB) and eight composite walls made of PET bottles filled with thermal insulation and/or mechanical stabilisation materials. The model equation is solved analytically using the separation of variables method and numerically using the finite difference method, and they are confirmed using CASTEM finite element software. As boundary conditions, a constant temperature (Text) is applied at one end of the wall, and the constant temperature (T0) is applied at any other point at the initial time. The effect of PET bottles filling on the thermal behaviour of the wall was then carried out to determine the optimum design that would give the wall better thermal inertia. The results obtained with CASTEM is fairly in agreement with the results obtained analytically and numerically, with a maximum relative error closed to that of the spatial evolution and 3.310−2 for the temporal one. It is found that heterogeneous filling of PET bottles provides better thermal inertia at the wall.

Recent Progress on 3D Printing of Lightweight Metal Thin-Walled Structures.

Metal thin-walled structures are ubiquitous in various industrial applications and fabricating them through additive manufacturing (AM) enables intricate thin-wall geometries with no assembly required. However, additively manufactured metal thin walls suffer from increased heat accumulation and reduced structural stability, making it difficult to print geometrically accurate thin walls with minimal distortion and defects. Thin-walled structures also experience different thermal histories and solidification conditions compared to bulk structures, leading to drastic differences in the microstructure and mechanical properties. In this review article, the AM processing of metal thin-walled structures will be introduced. An in-depth discussion on the design strategies of additively manufactured metal thin walls will be presented regarding the restrictions imposed by the AM technology, the integration of thin walls in lightweight structures, and novel design ideation through topology optimization. The effects that the thin wall design has on the geometrical accuracy, microstructure, and mechanical properties will then be elucidated. The utilization of AM for fabricating metal thin walls across various industries will also be summarized. Finally, this review article will close on some perspectives and future work on the AM of metal thin-walled structures.

Seismic experiment and performance analysis on embedded optimized steel plate-reinforced concrete composite shear wall under multi-dimensional loading

In order to investigate the seismic performance of reinforced concrete shear walls under multi-dimensional loading mode and its effect on performance improvement, an embedded optimized steel plate-reinforced concrete composite shear wall is proposed. Based on the design principle that the shear wall could adequately bear multi-dimensional loading and the embedded steel plate could reach the full stress state, the X-shaped optimized steel plate (for in-plane loading mode) and the triangular optimized steel plate (for out-of-plane loading mode) are determined using different optimization methods. The combination scheme of these two plates is utilized in the oblique loading mode. Quasi-static loading tests are conducted on eight typical shear wall specimens, and performance parameters such as hysteresis curve, skeleton curve, ductility, stiffness degradation, strain evolution, and damage evaluation of the specimens are compared and analyzed. In addition, variable parameter analysis is performed using finite element software to compare the strain distribution state of each steel plate. The results indicate that the embedded optimized steel plate-reinforced concrete composite shear wall structure exhibits higher bearing capacity, greater deformation capacity, and superior energy dissipation capacity under different loading angles compared to the tradition reinforced concrete shear walls. This composite structure can provide greater lateral stiffness, and the optimized steel plate can reach the full stress state at all loading angles, effectively reducing the damage of steel bars and concrete. These findings offer a foundation for the study of seismic performance and performance improvement methods for shear wall structures under multi-dimensional earthquake action.

Dynamic response of pile–slab retaining wall structure under rockfall impact

Abstract. Pile–slab retaining walls, as innovative rockfall protection structures, have been extensively utilized in the western mountainous regions of China. With their characteristics of a small footprint, high interception height, and ease of construction, these structures demonstrate promising potential for application in mountainous regions worldwide, such as the Himalayas, Andes, and Alps. However, their dynamic response upon impact and impact resistance energy remain ambiguous due to the intricate composite nature of the structures. To elucidate this, an exhaustive dynamic analysis of a four-span pile–slab retaining wall with a cantilever section of 6 m under various impact scenarios was conducted utilizing the finite-element numerical simulation method. The rationality of the selected material constitutive models and the numerical algorithm was validated by reproducing two physical model tests. The simulation results reveal the following. (1) The lateral displacement of the pile at the ground surface and the concrete damage under the pile at the impact center are greater than those under the slab at the impact center, implying that the impact location has a significant influence on the stability of the structure. (2) There is a positive correlation between the response indexes (impact force, interaction force, lateral deformation of pile and slab, concrete damage) and the impact velocities. (3) The rockfall peak impact force, the ratio of the peak impact force to the peak interaction force, and lateral displacement of the pile at the ground surface had strong linear relationships with rockfall energy. (4) Relative to the bending moment, shear force, and damage degree, the lateral displacement of the pile at the ground surface is the first to reach its limit value. Taking the lateral displacement of the pile at the ground surface as the controlling factor, the estimated maximum impact energy that the pile–slab retaining wall can withstand is 905 kJ in this study when the structure top is taken as the impact point. In cases where the impact energy of falling rocks exceeds 905 kJ, it is recommended to optimize the mechanical properties of the cushion layer, improve the elastic modulus of concrete, increase the reinforcement ratio of longitudinal tension bars, enlarge the section size of piles at ground level, or add anchoring measures to enhance the bending resistance of the retaining structure.

Seismically induced torsional amplification in limited ductile buildings

This article deals with the seismic demand on limited ductile buildings featuring plan asymmetry. When the yielding occurs in a structural wall positioned at the edge of the building remote from the centre of resistance (CR), the position of the CR would shift even further away from the wall, causing an additional, and momentarily, increase in torsion. The undesirable shift in the position of the CR is usually shortlived and would reverse as other walls in the building also surpass the yield limit. However, the limited ductile construction (typical of low to moderate seismicity regions) can be vulnerable. This additional amplification in torsion can only be captured by Incremental Dynamic Analyses (IDA), but not by elastic analyses nor by nonlinear analyses of high ductility demand. Thus, the phenomenon as described is not widely known in spite of torsion being a well researched topic. In this study, parametric studies employing IDA of limited ductile buildings of different structural configurations were undertaken to capture the trends and develop recommendations for guiding structural design.

INVESTIGATION OF FLUORINATED DOUBLE-WALL CARBON NANOTUBES

Experimental results of investigation of the original and fluorinated ultra-long double-walled carbon nanotubes (DWCNTs) with a length of at least 1000 μm are presented. The degree of fluoridation did not exceed 27 at.%. It has been shown that the process of fluorination of samples of double-walled carbon nanotubes deforms the outer surface of the nanotube wall although does not destroy its internal concentric structure, while the diameter of the fluorinated nanotube increases by 1.5-2 times. In addition, the fluorinated samples, which were thermochemically purified from iron particles and other forms of carbon before fluorination, demonstrated many split/cut ends of nanotubes. The effect of fluorination on the electrical properties of initial and purified samples of double-walled carbon nanotubes was studied. It was revealed that with an increase in temperature from 80 to 300 K for non-fluorinated and fluorinated purified nanotube samples, the resistivity decreases, which corresponds to the semiconductor nature of the conductivity. It was also revealed that when a sample of initial DWNT is fluorinated, a change in the nature of conductivity from semiconductor to metallic is observed. With an increase in temperature from 80 to 300 K, the resistance of the non-fluorinated sample of the original DWNTs decreased by 45%, while the resistance of the fluorinated sample increased by 11%. Despite the decrease in electrical conductivity as a result of fluorination of the purified samples, all samples remained conductors, which presumably indicates partial fluorination of the outer wall of the DWNTs while maintaining the structure of the inner wall. Thus, fluorination of double-walled carbon nanotubes with a well-aligned and concentric structure leads to the formation of fluorocarbon nanostructures, which can be promising materials for electronic nanodevices. For citation: Karaeva A.R., Khaskov M.A., Kurzhumbaev D.Zh., Kulnitskiy B.A., Mordkovich V.Z. Investigation of fluorinated double-wall carbon nanotubes. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 10. P. 38-48. DOI: 10.6060/ivkkt.20246710.4y.

Diethyl aminoethyl hexanoate reprogramed accumulations of organic metabolites associated with water balance and metabolic homeostasis in white clover under drought stress.

Diethyl aminoethyl hexanoate (DA-6) serving as a non-toxic and low-cost plant growth regulator is used for improving plant growth and stress tolerance, but the DA-6-mediated organic metabolites remodeling in relation to drought tolerance is not well documented in crops. The aims of the present study were to evaluate impacts of DA-6 on physiological functions including osmotic adjustment, photochemical efficiency, oxidative damage, and cell membrane stability as well as organic metabolites remodeling in white clover (Trifolium repens) leaves based on the analysis of metabolomics. Plants were foliarly treated with or without DA-6 and subsequently exposed to drought stress for 8 days. Results demonstrated that foliar application of DA-6 (1.5 mM) could significantly ameliorate drought tolerance, which was linked with better leaf water status, photosynthetic performance, and cell membrane stability as well as lower oxidative injury in leaves. Metabolic profiling of organic metabolites identified a total of 59 metabolites including 17 organic acids, 20 sugars, 12 alcohols, and 10 other metabolites. In response to drought stress, the DA-6 induced accumulations of many sugars and sugar alcohols (erythrulose, arabinose, xylose, inosose, galactose, talopyranose, fucose, erythritol, and ribitol), organic acids (propanoic acid, 2,3-dihydroxybutanoic acid, palmitic acid, linolenic acid, and galacturonic acid), and other metabolites (2-oxazoline, silane, and glycine) in white clover. These altered metabolites induced by the DA-6 could perform critical functions in maintenances of osmo-protection, osmotic adjustment, redox homeostasis, cell wall structure and membrane stability when white clover suffered from water deficit. In addition, the campesterol and stigmasterol significantly accumulated in all plants in spite of the DA-6 pretreatment under drought stress, which could be an important adaptive response to water deficit due to beneficial roles of those two metabolites in regulating cell membrane stability and antioxidant defense. Present findings provide new evidence of DA-6-regulated metabolic homeostasis contributing to drought tolerance in leguminous plants.