Low Levels Of Damage Research Articles

Power law creep and delayed failure of gels and fibrous materials under stress.

Motivated by recent experiments studying the creep and breakup of a protein gel under stress, we introduce a simple mesoscopic model for the irreversible failure of gels and fibrous materials, and demonstrate it to capture much of the phenomenology seen experimentally. This includes a primary creep regime in which the shear rate decreases as a power law over several decades of time, a secondary crossover regime in which the shear rate attains a minimum, and a tertiary regime in which the shear rate increases dramatically up to a finite time singularity, signifying irreversible material failure. The model also captures a linear Monkman-Grant scaling of the failure time with the earlier time at which the shear rate attained its minimum, and a Basquin-like power law scaling of the failure time with imposed stress, as seen experimentally. The model furthermore predicts a slow accumulation of low levels of material damage during primary creep, followed by the growth of fractures leading to sudden material failure, as seen experimentally.

Autophagy confers aluminum tolerance by enhancing the antioxidant capacity and promoting oxidized protein degradation in wheat (Triticum aestivum.) roots

Aluminum (Al) usually disturbs redox homeostasis and causes irreversible oxidative damage to biomolecules in plants, efficiently removing damaged and toxic macromolecules is essential to Al tolerance. Here, we investigated the role of autophagy, a conserved cellular degradation pathway, in plant Al tolerance using two wheat genotypes with different Al sensitivity. Compared to the sensitive genotype, Al significantly upregulated the expression of autophagy-related genes (ATGs) and enhanced the formation of autophagosomes. Reinforcing autophagy by rapamycin substantially alleviated the inhibition of root growth by Al stress, accompanied by low levels of reactive oxygen species (ROS) accumulation and oxidative damage in wheat roots; whereas inhibition of autophagy by 3-methyladenine (3-MA) aggravated the adverse impacts of Al toxicity. Further experiments showed that Al significantly triggered the accumulation of oxidized proteins, particularly in the sensitive genotype. The content of Al-induced oxidized proteins was reduced by rapamycin but further increased by 3-MA in wheat roots. Wheat plants treated with the inhibitor of vacuole H+-ATPase, concanamycin A, were more sensitive to Al stress and accumulated higher levels of oxidatively-damaged proteins compared to Al treatment. These results reveal that autophagy-mediated redox homeostasis and the clearance of oxidatively damaged proteins play a crucial role in plant's tolerance to Al stress.

Sirtuin 6 activation rescues the age-related decline in DNA damage repair in primary human chondrocytes.

While advanced age is widely recognized as the greatest risk factor for osteoarthritis (OA), the biological mechanisms behind this connection remain unclear. Previous work has demonstrated that chondrocytes from older cadaveric donors have elevated levels of DNA damage as compared to chondrocytes from younger donors. The purpose of this study was to determine whether a decline in DNA repair efficiency is one explanation for the accumulation of DNA damage with age, and to quantify the improvement in repair with activation of Sirtuin 6 (SIRT6). After acute damage with irradiation, DNA repair was shown to be more efficient in chondrocytes from young (≤45 years old) as compared to middle-aged (50-65 years old) or older (>70 years old) cadaveric donors. Activation of SIRT6 with MDL-800 improved the repair efficiency, while inhibition with EX-527 reduced the rate of repair and increased the percentage of cells that retain high levels of damage. In addition to affecting repair after acute damage, treating chondrocytes from older donors with MDL-800 for 48 hours significantly reduced the amount of baseline DNA damage. Chondrocytes isolated from the knees of mice between 4 months and 22 months of age revealed both an increase in DNA damage with aging, and a decrease in DNA damage following MDL-800 treatment. Lastly, treating murine cartilage explants with MDL-800 lowered the percentage of chondrocytes with high p16 promoter activity, which supports the concept that using SIRT6 activation to maintain low levels of DNA damage may prevent the initiation of senescence.

Microscopic heterogeneity of low cyclic fatigue damage in Ni-based single crystal superalloy DD413

The heterogeneous low cyclic fatigue damage level in the Ni-based single crystal superalloy DD413 was quantitatively assessed under the strain control of ±0.8% and ± 1.1%. The specimens subjected to ±0.8% strain amplitude exhibited an almost pure elastic deformation response throughout the entire cyclic loading period. In contrast, the ±1.1% strain-controlled deformed specimen exhibited a gradual increase in plastic strain, rising from 0.046% in the 1st cycle to 0.072% by the 268th cycle. The brittle carbides caused a significant mechanical incompatibility with the matrix. This was observed through the orientation dispersal over 16° in the {001} pole figure of the ±1.1% specimen, which was substantially broader than the ±0.8% specimen where the dispersion was only 1.2°. The large orientation gradient in the interdendrite (IR) triggered the dispersion of the microstructure-averaged orientation of the ±1.1% specimen, as evidenced by a mean grain reference orientation deviation (GROD) angle three times higher in the IR compared to the dendrite (DR). While the DR and IR of ±0.8% specimen showed similar mean GROD angles. This substantial orientation gradient was sustained by the high density of geometrically necessary dislocations (GNDs) in the IR, which was double that of the DR. Differently, the DR and IR in the ±0.8% specimen exhibited similar mean densities of GNDs. The study suggests that minimizing microstructural heterogeneity at the dendritic scale may enhance the durability of DD413 alloy components when exposed to cyclical stress with greater strain amplitudes.

Empirical Modelling of Stem Cambium Heating Caused by Prescribed Burning in Mediterranean Pine Forest

Little is known about the interactions between the variables involved in the post-fire response of Mediterranean pine species to prescribed burning (PB). Thus, it is essential to develop an empirical model in order to assess the influence of tree and stand attributes, burn season, and fire severity on the probability of stem cambium damage occurring. Prescribed burnings were conducted in different seasons and areas covering a wide climatic and ecological range. Potential explanatory variables were measured. A random effects hurdle model framework was used to evaluate the temperature duration above 60 °C as a proxy for stem cambium damage at tree scale. The results showed significant differences in cambium damage between the PB seasons. Pinus nigra was more resistant than other pine species. Bark thickness was critical for protecting cambium. Volume of crown scorch, percentage of stem scorch, and maximum outer bark temperature were directly related to temperature duration above 60 °C in the cambium. Prescribed burning conducted under tree canopy in Mediterranean pine species generally results in a low level of cambium damage. Empirical models could help managers to predict the effects of PB and thus select the most suitable prescriptions.

A deep‐learning framework for classifying the type, location, and severity of bridge damage using drive‐by measurements

AbstractThis paper proposes a new deep‐learning framework for drive‐by bridge condition monitoring. The proposed approach represents a bridge monitoring regime that enables the presence, type, location, and severity of bridge damage to be identified purely from measurements taken on a passing vehicle, without needing any pre‐measured training data. The computational framework adopts a numerical vehicle–bridge interaction (VBI) model, which is automatically calibrated using only the vehicle vibration measurements. The calibrated model is used to generate labeled training data, eliminating the practical difficulties associated with collecting training data for damaged bridge scenarios. The numerically simulated data are used to train a convolutional neural network that can then classify the actual damage characteristics of a bridge. The method is tested using a laboratory‐scale VBI model, and results show that the algorithm can accurately identify the presence of seized bearings and cracking in the bridge beams. The algorithm shows good accuracy when identifying the type and extent of damage. The location of bearing damage can generally be identified; however, the location of cracking is less accurate at lower damage levels. The proposed framework represents a significant improvement on existing techniques for indirect bridge monitoring.

A rapid numerical-based vulnerability assessment method for masonry buildings subject to flood

Buildings exposed to high-intensity flood actions can experience severe damage and collapse. Rapid procedures can significantly aid in identifying the most vulnerable buildings within large flood-risk areas, enabling the implementation of retrofitting and mitigation measures. Motivated by this need, in this work we propose a simplified vulnerability assessment method that employs a mechanics-based approach. This strategy exclusively addresses the structural damage and is based on assigning a Vulnerability Index to each building. Then, considering some hazard intensity indicators, the method gives the most probable damage level. The main novelty of the proposed method lies in its calibration, which is performed on the results of a high number of numerical analyses. Results show a good agreement between the proposed simplified method and the numerical simulations, particularly in estimating high or low damage levels. Finally, the method is applied to a case study regarding the municipality of Crotone, in southern Italy.

Invasive Whitefly (Hemiptera: Aleyrodidae) Complex and Diversity in Coconut Landscapes in Tamil Nadu

Abstract Coconut, Cocos nucifera L., in Tamil Nadu, India, was invaded by four whitefly (Hemiptera: Aleyrodidae) species between 2016 and 2019, increasing the total to six, along with Aleurodicus dispersus Russell and Aleurocanthus arecae David and Manjunatha. We examined the complexity and diversity of whiteflies in coconut across different agroclimatic zones of Tamil Nadu and found high and low damage levels by whiteflies at Veppankulam (70.4%) and Rameswaram (11.0%), respectively. The rugose spiraling whitefly, Aleurodicus rugioperculatus Martin, was the most dominant species but was effectively managed by the parasitoids Encarsia guadeloupae Viggiani and E. dispersa Polaszek, with the highest rate parasitism of 83.8% at Aliyar Nagar and the lowest (2.9%) in the Kanchipuram district. Aleurodicus rugioperculatus and Bondar’s nesting whitefly, Paraleyrodes bondari Peracchi, have spread throughout Tamil Nadu. The population of A. rugioperculaus was high at Veppankulam and that of P. bondari was higher at Dharmapuri (28.6 and 31.1 adults/leaflet, respectively). All five invasive whitefly species in coconut were found only in 7 of 34 locations—Coimbatore, Sirumugai, Salem, Dharmapuri, Krishnagiri, Vellore, and Erode. Paraleyrodes minei Iaccarino and Aleurotrachelus atratus Hempel were distributed in the northwestern zone adjoining the western ghats of Tamil Nadu. Coconut plantations at Sirumugai (western ghats) supported the most diverse collection of whiteflies, with 0.61 and 1.09 Simpson and Shannon diversity indices. Among the 29 districts, adjoining Dindigul and Theni districts showed the highest Bray–Curtis Similarity Matrix. Butterfly palm, Dypsis lutescens H. Wendel, custard apple, Annona squamosa L., and guava, Psidium guajava L., are whitefly hosts in coconut landscapes.

Low levels of mouse sperm chromatin fragmentation delay embryo development.

We previously demonstrated that MnCl2 induces double-stranded DNA breaks in sperm in a process that we term as sperm chromatin fragmentation. Here, we tested if the levels of double-stranded DNA breaks were corelated to the concentration of MnCl2, and we compared this to another agent that causes single-stranded DNA breaks, H2O2. We found that both methods have the advantage of inducing DNA breaks in a concentration-dependent manner. Mouse sperm were treated with varying concentrations of either H2O2 or MnCl2, and the DNA damage was assessed by pulse-field gel electrophoresis, and the alkaline and neutral comet assays. Oocytes were injected with either treated sperm and the resulting embryos analyzed with an embryoscope to detect subtle changes in embryonic development. We confirmed that H2O2 treatment induced primarily single-stranded DNA breaks and MnCl2 induced primarily double-stranded DNA breaks, indicating different mechanisms of damage. These sperm were injected into oocytes, and the development of the resulting embryos followed with an embryoscope equipped with time lapse recording. We found that aberrations in early embryonic development by day 2 with even the lowest levels of DNA damage and that the levels of embryonic aberrations correlated to the concentration of either H2O2 or MnCl2. Low levels of H2O2 caused significantly more aberrations in embryonic development than low levels of MnCl2 even though the levels of DNA damage as measured by comet assays were similar. These data demonstrate that even low levels of sperm DNA damage cause delays and arrests in embryonic development.

Effect of ozone treatment on microbial and quality alteration of onions during 2 months storage.

Storing and preserving onion using pesticides is common in Brebes District. The study determined the use of ozone to reduce microorganisms and to maintain the onion quality during months of post-harvesting. There were three chambers with 2.5 m3 in size, and with a capacity of 20 kg onion used for this study. Each chamber received different treatment for 2 months; chamber I: no treatment; chamber II: pesticide; chamber III: ozone. The ozone treatment maintained better temperature and humidity for preservation. Ozone treatment was also observed to maintain low level of mass damage (1.8%) as compared to control and pesticide (6.5% and 2.4%). The protein, ash, fat and vit B1 of onions were remained high in ozone-treated chamber. Total Plate Count (CFU/mL) and the Mold Yeast Count (colonies/mL) decreased on day 30 and 60 after pesticides and ozone treatment. This study showed the importance of ozone treatment to maintain better quality of onion after months of storage as compared to pesticide treatment. Therefore, ozone can be a potential use to replace the pesticide for preservation at post-harvesting.

The Effects of Cellular Membrane Damage on the Long-Term Storage and Adhesion of Probiotic Bacteria in Caco-2 Cell Line.

Adhesion is one of the main factors responsible for the probiotic properties of bacteria in the human gut. Membrane proteins affected by cellular damage are one of the key aspects determining adhesion. Fluid-bed-dried preparations containing probiotic bacteria were analyzed in terms of their stability (temperature of glass transition) and shelf life in different conditions (modified atmosphere, refrigeration). Imaging flow cytometry was utilized to determine four subpopulations of cells based on their physiological and morphological properties. Lastly, adhesion was measured in bacteria cultured in optimal conditions and treated with heat shock. The results show that the subpopulations with no or low levels of cell membrane damage exhibit the ability to adhere to Caco-2 cells. The temperature of protein denaturation in bacteria was recorded as being between 65 °C and 70 °C. The highest glass transition temperature (Tg) value for hydroxypropyl methylcellulose (used as a coating substance) was measured at 152.6 °C. Drying and coating can be utilized as a sufficient treatment, allowing a long shelf-life (up to 12 months). It is, however, worth noting that technological processing, especially with high temperatures, may decrease the probiotic value of the preparation by damaging the bacterial cells.

Field-grown cotton shows genotypic variation in agronomic and physiological responses to waterlogging

ContextWaterlogging frequently occurs and causes serious damage to cotton. While genotypic variation in waterlogging tolerance has been reported in cotton, there is limited research on the difference in waterlogging tolerance among Chinese commercial cotton varieties, and whether waterlogging tolerance is related to their geographical origin remains unclear. MethodsTo this end, we conducted a comparative study to evaluate the waterlogging tolerance of commercial cotton varieties from three major cotton-growing regions in China. Field-grown cotton was subjected to seven days of waterlogging stress at early flowering. The effects of waterlogging on growth, seedcotton yield, yield reduction, and various physiological responses were assessed. ResultsThe losses of seedcotton yield and biological yield of cotton varieties from the Yangtze River valley were the lowest (7.6% and 4.7%), followed by those from the Yellow River valley (14.4% and 7.7%), while the losses of cotton varieties from the Northwest Inland were the greatest (21.8% and 15.5%). This indicated that cotton ecotypes from the Yangtze River valley and Yellow River valley, characterized by higher precipitation, exhibit greater tolerance to waterlogging than those from the Northwest Inland. The increases in H2O2, malondialdehyde (MDA), and abscisic acid (ABA) contents in the cotton variety from the Yangtze River valley (YZ1) were the lowest (10.8%, 18.6%, and 20.8%, respectively), followed by those from the Yellow River valley (YL1) (32.6%, 33.2%, and 79.9%, respectively), while the increases in cotton varieties from the Northwest Inland (NW1) were the greatest (37.9%, 42.8%, and 84.4%, respectively). The decreases in indole-3-acetic acid (IAA), nitric oxide (NO), and nitrogen (N) contents of YZ1 were the lowest (10.3%, 32.5%, and 25.6%, respectively), followed by those from YL1 (12.7%, 39.8%, and 30.2%, respectively), while the decreases of NW1 were the greatest (24.9%, 48.3%, and 45.1%, respectively). Quantitative real-time PCR analysis showed the highest expression of the NO (GhNIR) and IAA (GhYUC8) synthesis genes, but the lowest expression of the genes involved in H2O2 production (GhRBOHC), and ABA synthesis (GhNCED2) in YZ1, followed by those in YL1 and NW1, indicating that gene expression patterns aligned with the changes of NO, IAA, H2O2 and ABA contents. Ten days after waterlogging relief, waterlogged YZ1 exhibited the greatest increases in biomass, leaf area, and canopy photosynthesis (44.1%, 40.0%, and 46.4%, respectively), followed by YL1 (39.0%, 36.9% and 40.5%, respectively), while NW1 showed the lowest increases (36.3%, 32.6% and 35.4%, respectively), indicating stronger compensatory growth in the Yangtze River valley cotton variety. ConclusionsThe results suggest that cotton varieties from the Yangtze River valley were more tolerant to waterlogging as evidenced by the lower level of damage and stronger compensatory growth than those from other geographical origins. We propose that quiescence adaptation and compensatory growth are the two main strategies employed by cotton to cope with waterlogging stress. This study enhances our understanding of the damage caused by waterlogging and sheds light on the adaptive mechanisms of cotton. Furthermore, it provides valuable insights for the breeding waterlogging-tolerant cotton varieties and improving cultivation practices.

Evaluation of long-term residual activity of insecticides against Acanthoscelides obtectus (Say) on common bean in laboratory tests

There are insufficient data about long-term (longer than six-months) residual effects of insecticides against Acanthoscelides obtectus (Say) as an important economic insect pest of stored bean. Therefore, we evaluated, in laboratory conditions, the insecticide potential of recommended rates of commercial formulations: organophosphate malathion (10 mg active ingredient - AI/kg), spinosyns bioinsecticide spinosad (1 mg AI/kg) and pyrethroid deltamethrins (0,25 mg AI/kg, with and without the synergist piperonil butoxide – PBO) after 210-, 265-, 310- and 365-days of post-treatment. Testing was performed on two types of beans with kidney- and cranberry-shaped kernels to evaluate the insecticide residual effects on the survival of weevils, progeny production, and related levels of kernels damage. Survival of weevils depends mainly on adults exposure/living period in treated beans and on the recovering period. Small differencies in weevils survival in each insecticide were recorded. We found increases in progeny and thus higher damage in beans, as manifested effects of sublethal doses only in malathion treated bean. In spinosad treated bean we recorded low levels of progeny and damage, below the economic threshold. In deltamethrin treatments, we recorded weevils avoiding contact with beans, no progeny and no damages. The effect of bean type was very low or non existent. It can be concluded that bioinsecticide spinosad can provide long-term protection of common beans against A. obtectus, while organophosphate malathion has low control potential. Pyrethroid deltamethrins residues cause adults to avoid treated beans and no offspring to appear. The obtained results might have significant impact on better understanding of weevils behaviour in the presence of insecticide residues and on the creation of sustainable pest management programmes.

Xrcc5/Ku80 is required for the repair of DNA damage in fully grown meiotically arrested mammalian oocytes

Mammalian oocytes spend most of their life in a unique state of cell cycle arrest at meiotic prophase I, during which time they are exposed to countless DNA-damaging events. Recent studies have shown that DNA double-strand break repair occurs predominantly via the homologous recombination (HR) pathway in small non-growing meiotically arrested oocytes (primordial follicle stage). However, the DNA repair mechanisms employed by fully grown meiotically arrested oocytes (GV-stage) have not been studied in detail. Here we established a conditional knockout mouse model to explore the role of Ku80, a critical component of the nonhomologous end joining (NHEJ) pathway, in the repair of DNA damage in GV oocytes. GV oocytes lacking Ku80 failed to repair etoposide-induced DNA damage, even when only low levels of damage were sustained. This indicates Ku80 is needed to resolve DSBs and that HR cannot compensate for a compromised NHEJ pathway in fully-grown oocytes. When higher levels of DNA damage were induced, a severe delay in M-phase entry was observed in oocytes lacking XRCC5 compared to wild-type oocytes, suggesting that Ku80-dependent repair of DNA damage is important for the timely release of oocytes from prophase I and resumption of meiosis. Ku80 was also found to be critical for chromosome integrity during meiotic maturation following etoposide exposure. These data demonstrate that Ku80, and NHEJ, are vital for quality control in mammalian GV stage oocytes and reveal that DNA repair pathway choice differs in meiotically arrested oocytes according to growth status.

The Role of Chromatin Assembly Factors in Induced Mutagenesis at Low Levels of DNA Damage.

The problem of low-dose irradiation has been discussed in the scientific literature for several decades, but it is impossible to come to a generally accepted conclusion about the presence of any specific features of low-dose irradiation in contrast to acute irradiation. We were interested in the effect of low doses of UV radiation on the physiological processes, including repair processes in cells of the yeast Saccharomyces cerevisiae, in contrast to high doses of radiation. Cells utilize excision repair and DNA damage tolerance pathways without significant delay of the cell cycle to address low levels of DNA damage (such as spontaneous base lesions). For genotoxic agents, there is a dose threshold below which checkpoint activation is minimal despite the measurable activity of the DNA repair pathways. Here we report that at ultra-low levels of DNA damage, the role of the error-free branch of post-replicative repair in protection against induced mutagenesis is key. However, with an increase in the levels of DNA damage, the role of the error-free repair branch is rapidly decreasing. We demonstrate that with an increase in the amount of DNA damage from ultra-small to high, asf1Δ-specific mutagenesis decreases catastrophically. A similar dependence is observed for mutants of gene-encoding subunits of the NuB4 complex. Elevated levels of dNTPs caused by the inactivation of the SML1 gene are responsible for high spontaneous reparative mutagenesis. The Rad53 kinase plays a key role in reparative UV mutagenesis at high doses, as well as in spontaneous repair mutagenesis at ultra-low DNA damage levels.

A Blunt Force Trauma Analysis of Interpersonal Violence in Northern Patagonia and Southern Pampa (Argentina): An Experimental Perspective

AbstractThis article evaluates the level of interpersonal violence among human groups that inhabited northern Patagonia and southern Pampa (Argentina) during the Middle and Late Holocene, especially before contact with Europeans. We analyzed a particular type of trauma—blunt force trauma—in skull samples from several archaeological localities and compared our outcomes with those of a previous experimental work. The results agree with what is expected for small-scale societies within the regional historical and archaeological framework. The recorded percentages show a diachronic increase toward higher frequencies of this injury among males than among females and subadults, but the differences are not statistically significant. Generally, the levels of violence remained relatively constant during the period studied. Most of the injuries reflect low levels of damage, which allows us to hypothesize that the objects causing the injuries would be elements of everyday life. A smaller proportion show significant bone alteration that could be associated with weapons manufactured to exert violence or hunt animals.

Association between serum uric acid concentration and radiographic axial spondylarthritis: a cross-sectional study of 202 patients.

Association between serum uric acid concentration and radiographic axial spondylarthritis: a cross-sectional study of 202 patients.

Analysis of Cellular Damage Resulting from Exposure of Bacteria to Graphene Oxide and Hybrids Using Fourier Transform Infrared Spectroscopy.

With the increase in antimicrobial resistance, there is an urgent need to find new antimicrobials. Four particulate antimicrobial compounds, graphite (G), graphene oxide (GO), silver-graphene oxide (Ag-GO) and zinc oxide-graphene oxide (ZnO-GO) were tested against Enterococcus faecium, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. The antimicrobial effects on the cellular ultrastructure were determined using Fourier transform infrared spectroscopy (FTIR), and selected FTIR spectral metrics correlated with cell damage and death arising from exposure to the GO hybrids. Ag-GO caused the most severe damage to the cellular ultrastructure, whilst GO caused intermediate damage. Graphite exposure caused unexpectedly high levels of damage to E. coli, whereas ZnO-GO exposure led to relatively low levels of damage. The Gram-negative bacteria demonstrated a stronger correlation between FTIR metrics, indicated by the perturbation index and the minimal bactericidal concentration (MBC). The blue shift of the combined ester carbonyl and amide I band was stronger for the Gram-negative varieties. FTIR metrics tended to provide a better assessment of cell damage based on correlation with cellular imaging and indicated that damage to the lipopolysaccharide, peptidoglycan and phospholipid bilayers had occurred. Further investigations into the cell damage caused by the GO-based materials will allow the development of this type of carbon-based multimode antimicrobials.

Self‐healing study of impact damage in carbon fiber composites based on electrostatically spun polyacrylonitrile core–shell nanofibers

AbstractCarbon fiber composites containing core–shell nanofibers (PAN@CFRP) were prepared by incorporating electrospun polyacrylonitrile core–shell nanofibers between the layers of carbon fiber reinforced polymer composites and the damage healing ability was assessed after being subjected to low‐velocity impact. Three impact energies (25.2, 33.5, and 41.9 J) were selected for the study. The incorporation of core–shell nanofibers improved the impact resistance of the composites compared with pure carbon fiber composites (CFRP); the PAN@CFRP specimens were found to have a smaller damage area and a lower damage level by visual observation and optical microscopy. The healing efficiency was 66.3%, 43.5%, and 8.83% for the residual compressive strength and was normalized to the residual compressive strength when the impact energy was less than 37.5 J. The healed materials were found to recover more than 80% of their undamaged residual compressive strength when the impact energy was less than 37.5 J. Therefore, the core–shell nanofiber healing system can, to a certain extent, solve the problems caused by the incorporation of other healing systems, and can largely recover the impact damage encountered in practical applications.

МОДЕЛЮВАННЯ ТА ПЕРСПЕКТИВНІ НАПРЯМИ КОНСТРУКТИВНО-ТЕХНОЛОГІЧНИХ СХЕМ ГРУДКОРУЙНУЮЧИХ РОБОЧИХ ОРГАНІВ КОРЕНЕБУЛЬБОЗБИРАЛЬНИХ МАШИН

Для успішного виходу України на західні ринки необхідно забезпечити конкурентоспроможність власної продукції, яка досягається завдяки комплексній механізації технологічних процесів, зниженню витрат праці, збільшенню врожайності та якості одержуваної продукції. Відповідно, метою дослідження було проведення порівняльного аналізу технологій і машин для збирання картоплі, розроблення моделі вдосконалення грудкоруйнуючих робочих органів й окреслення перспективних напрямів удосконалення коренебульбозбиральних машин. Дослідження проводилися шляхом технологічно-конструкційного аналізу технологій і машин для збирання картоплі. У процесі досліджень використовувались методи порівняння та математичного моделювання конструктивно-технологічних схем грудкоруйнуючих робочих органів. Інформаційною базою досліджень слугували праці українських і зарубіжних науковців із технологій і машин для збирання картоплі. На основі проведеного порівняльного аналізу технологій і машин для збирання картоплі виявлено основні конструктивно-технологічні схеми, що впливають на агротехнічні показники збиральної техніки, розроблено модель грудкоруйнуючих робочих органів (збиральних машин). Дана модель включає руйнування ґрунтових грудок: по-перше, катками безпосередньо перед підкопом бульбоносного пласта; по-друге, грудкоподрібнюючими пристроями (балонами, бітерами або інтенсификаторами сепарації) різних конструкцій у процесі виконання технологічних операцій картоплезбиральної машиною. Попереднє руйнування бульбоносного пласта проводиться безпосередньо перед його підкопуванням і в момент підкопування опорними катками різних типів та інших конструктивних і кінематичних параметрів робочих органів машин.